TAILOR WELDED BLANK

APPLICATIONS AND MANUFACTURING

A State-of-the-Art Survey

The Auto/Steel Partnership

Tailor Welded Blank Project Team 2000 Town Center - Suite 320

Southfield, MI 48075-1123 June 2001

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Auto/Steel Partnership

Bethlehem Steel Corporation DaimlerChrysler Corporation Dofasco Inc. Ford Motor Company General Motors Corporation Ispat Inland Inc. LTV Steel Company National Steel Corporation Rouge Steel Company Stelco Inc. U. S. Steel Group, a Unit of USX Corporation WCI Steel, Inc. Weirton Steel Corporation

This publication is for general information only. The material contained herein should not be used without first securing competent advice with respect to its suitability for any given application. This publication is not intended as a representation or warranty on the part of Auto/Steel Partnership – or any other person named herein – that the information is suitable for any general or particular use, or free from infringement of any patent or patents. Anyone making use of the information assumes all liability arising from such use. For more information or additional copies of this publication, please contact the Auto/Steel Partnership, 2000 Town Center, Suite 320, Southfield, MI 48075-1123 or phone: 248-945-7777, fax: 248-356-8511, web site: www.a-sp.org

Copyright 2001 Auto/Steel Partnership. All Rights Reserved.

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TABLE OF CONTENTS

EXECUTIVE SUMMARY.............................................................................................................................. 1

3.1.1 INTRODUCTION ............................................................................................................................. 3

1.1 STUDY OBJECTIVES AND SCOPE ...................................................................................... 3

1.2 CONTRIBUTORS ................................................................................................................... 4

3.1.4 TAILOR WELDED BLANK APPLICATIONS ................................................................................. 5

2.1 APPLICATION DESIGNS................................................................................................... 5

3.1.5 STRAIGHT LINE........................................................................................................ 6

3.1.6 NON-LINEAR............................................................................................................. 8

3.1.7 PATCH..................................................................................................................... 11

3.1.8 TUBES ..................................................................................................................... 13

2.1.6 HIGH STRENGTH STEEL....................................................................................... 16

2.2 NORTH AMERICAN APPLICATIONS.............................................................................. 16

2.3 EUROPEAN APPLICATIONS .......................................................................................... 19

2.4 JAPANESE APPLICATIONS............................................................................................ 22

3.1.9 WELD PROCESSING TECHNOLOGIES ..................................................................................... 26

3.2 WELDING POWER SOURCE.......................................................................................... 26

3.2.1 INTRODUCTION ..................................................................................................... 26

3.1.2 CO2 AND Nd:YAG................................................................................................... 27

3.1.3 PLASMA AUGMENTED LASER WELDING (PALW).............................................. 28

3.1.4 INDUCTION AND NON-VACUUM ELECTRON BEAM .......................................... 28

3.1.5 MASH WELDING..................................................................................................... 28

3.2 DUAL SPOT WELDING (MULTI-SPOT) .......................................................................... 30

3.3 EDGE & BLANK PREPARATION .................................................................................... 30

3.4 WELDING PARAMETERS ............................................................................................... 32

3.5 TAILOR WELDED BLANK FORMABILITY ..................................................................... 32

3.5.1 INTRODUCTION ..................................................................................................... 32

3.5.2 FORMABILITY TESTING: PARALLEL AND TRANSVERSE MAJOR STRAIN...... 33

3.5.3 WELDING AND WELD PROFILE............................................................................ 33

3.6 DEFECTS AND DEFECT DETECTION........................................................................... 34

3.6.1 WELD QUALITY ...................................................................................................... 34

3.6.2 WELD GEOMETRY................................................................................................. 34

3.6.3 POROSITY AND PINHOLES .................................................................................. 35

3.7 WELDING PATCH BLANKS................................................................................................. 36

4.0 MANUFACTURING SYSTEMS AND SUPPLIERS ............................................................................. 37

4.1 MANUFACTURING SYSTEMS - PRODUCTION................................................................. 37

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5.2 INTEGRATED LASER CUTTING AND WELDING (RESEARCH)...................................... 43

5.3 TAILOR WELDED BLANK SUPPLIERS ............................................................................. 48

5.4 NORTH AMERICA............................................................................................................ 48

4.3.2 EUROPE ........................................................................................................................ 48

5.5 ASIA.................................................................................................................................. 50

5.6 SUPPLY LOGISTICS........................................................................................................................... 51

5.7 PALLETS............................................................................................................................. 51

5.8 INVENTORY ....................................................................................................................... 51

5.9 DIMPLING............................................................................................................................ 52

5.4 STACK REQUIREMENTS................................................................................................... 52

5.5 OTHER................................................................................................................................. 53

6.0 APPENDIX ............................................................................................................................................. 1

6.1 EQUIPMENT SUPPLIER CONTACTS.................................................................................. 2

6.2 BLANK SUPPLIERS - NORTH AMERICA ............................................................................ 3

6.3 BLANK SUPPLIERS - EUROPE............................................................................................ 5

6.4 BLANK SUPPLIERS - SOUTH AMERICA............................................................................. 7

6.5 BLANK SUPPLIERS - ASIA................................................................................................... 8

6.6 BIBLIOGRAPHY .................................................................................................................... 9

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List of Illustrations Figure 1 - Worldwide breakdown of TWB applications. .............................................................................5

Figure 2 - B-pillar example of simple, one straight line weld application. ..................................................6

Figure 3 - Multi-straight line welded body side for Jeep Grand Cherokee. ................................................7

Figure 4 - Multi-straight line weld door inner (VW Golf). ............................................................................7

Figure 5 - Angular straight line weld on door inner. ...................................................................................8

Figure 6 - Non-linear prototypes produced by Fraunhofer. ........................................................................9

Figure 7- First known non-linear production TWB - produced by Laser Welding International. .............10

Figure 8 - Analysis of different door designs (Thyssen Krupp Stahl).......................................................10

Figure 9 - Curvilinear wheelhouse developmental application.................................................................11

Figure 10 - Two examples of patch-type tailor welded blanks. ..................................................................12

Figure 11 - Patch TWB comparison for door inner.....................................................................................13

Figure 12 - Four tube shapes: cylindrical, tailor shape, oval, and conical. ................................................14

Figure 13 - Tailor welded tubes: constant OD, constant ID, and “sleeve”. ................................................15

Figure 14 - Soudronic Soutube welding videos..........................................................................................15

Figure 15 - Soudronic Soutube welding unit for tailor tubes. .....................................................................16

Figure 16 - Projected tailor welded blank demand for North America – based on two sources ................17

Figure 17 - North American body side with over 4.8 meters of weld. ........................................................17

Figure 18 - ULSAB tailor welded blank applications. .................................................................................18

Figure 19 - Estimated worldwide TWB demand (in parts produced). ........................................................19

Figure 20 - Distribution of European applications by type and quantity.....................................................19

Figure 21 - Peugeot body side with “short” welds. .....................................................................................20

Figure 22 - BMW 3-series door inner. ........................................................................................................21

Figure 23 - The Toyota Camry body side outer (top), and the Toyota Crown body side inner (bottom). ..23

Figure 24 - Nissan TWB body side (1998 production start). ......................................................................24

Figure 25 - Nissan body side outer panel with high strength steel. ...........................................................24

Figure 26 - Comparison of Four Welding Methods. ...................................................................................29

Figure 27 - Soudronic SOUKA® process for edge preparation. .................................................................31

Figure 28 - Special blank die design for precise edge condition used at Nissan.......................................31

Figure 29 - Failure patterns for tailor welded blanks. .................................................................................33

Figure 30 - Typical process monitoring approach for potential defect identification. ................................35

Figure 31 - Soudronic laser shuttle system................................................................................................38

Figure 32 - Soudronic SOULAS welding system video..............................................................................38

Figure 33 - Thyssen Conti flow-through system (with jig pallets)...............................................................38

Figure 34 - Schematic of indexing jig/shuttle system with parallel turnover and stacking stations............39

Figure 35 - Schematic of Renault Automation indexing jig system with 2-axis weld capability. ................40

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List of Illustrations - Continued

Figure 36 - Nissan TWB welding system development strategy...............................................................41

Figure 37 - Nissan Generation III welding system. ....................................................................................41

Figure 38 - NissanGeneration III video.......................................................................................................42

Figure 39 - Layout of Thyssen non-linear welding line that uses jigs. .......................................................43

Figure 40 - Conceptual Fraunhofer welding system with two CO2 laser resonators – one for blank cutting

and one for welding. ...........................................................................................................................44

Figure 41 - Standardized steel pin pallets used by Mercedes Benz. .........................................................51

Figure 42 - Oblong embossment design that tends to hold up well. ..........................................................52

Table 1 – Comparative tradeoffs between welding technologies. ......................................................... 26

Table 2 – Process control variables for CO2 laser welding (Soudronic results) ..................................... 27

Table 3 – Commercially Available TWB Welding Systems .................................................................. 46

Table 4 – Proprietary TWB welding systems. ..................................................................................... 47

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EXECUTIVE SUMMARY

The tailor welded blank (TWB) industry continues to experience steady growth. Each auto company now has TWB applications and the growth rate is approximately 25% to 30% per year in North America, Europe and Japan. The leading objectives continue to be cost reduction, structural improvement and mass reduction. Certain companies continue to recognize quality improvements as a major objective, especially with door inners and one-piece body side TWBs. While there continue to be numerous small (under 0.75 meters), simple, one-weld applications, the growth is spreading into larger, more complex products. The leading TWB users, GM, DaimlerChrysler, Volkswagen and Toyota, all have door inner TWBs which were once considered an advanced application because of weld lengths exceeding one meter. Today, Mercedes, Volkswagen, and BMW have TWB door inners with multiple welds. GM, DaimlerChrysler, and Toyota are leaders in body side aperture TWBs. There is interest in Europe and among other Japanese companies, with Nissan having one in production, and looking at more, and Mazda planning one in the future. Japanese and European aperture designs tend to be markedly different than those seen in North America. The North American apertures tend to be a body side with multiple, long welds that are costly to process and weld. European and Japanese designs tend to be body side inner panels with two to three short welds on shallow draw panels that are simpler to process. The shallow draw panels are also more conducive to integrating high strength steel into the body side.

The greatest interest in non-linear welding (NLW) exists among North American companies, with some interest in Europe. Many Japanese companies are content to exploit the simpler, low-risk applications before "stretching" the technology when minimal additional benefit is gained. Nissan expressed some interest in NLW parts in the future and have designed their Generation III welding system with NLW blanks in mind. The simplest NLW designs involve circular arcs that may or may not be combined with straight lines. The only known production NLW applications today involve circular arcs in shock tower and floor pan applications. Multiple straight-line welds, or two straight lines that intersect at an angle are being produced with current production technology. In some cases, there is a blow-hole at the intersection point requiring a careful consideration for weld line placement in the design phase. Although technically feasible, there are no known “undefined” NLW applications in production. In general, this design requires a sophisticated multi-axis weld head along with equally complex seam tracking software. A key technical difficulty involves maintaining a constant angle and speed of the laser beam, even around curves, which requires a weld head employing changing acceleration. Other challenges include obtaining an acceptable edge fit-up and developing appropriate clamping hardware. Although there is considerable interest in the benefits of NLW, such as further material and cost optimization and moving the weld line out of critical forming areas, most OEMs can only justify a marginal cost premium, achievable today only with simple, circular/arc welds. The expanded definition of TWBs includes both tailor welded tubes (TWT) and patch-type TWBs. TWTs are thin-walled tubes with varying wall properties, such as differing thicknesses along the tube. TWT fabricating technology is available today, but economically viable applications have not yet been identified. TWTs would most likely be formed with hydroforming; however, both TWT production and hydroforming processes add considerable expense. As with tube hydroforming in general, design engineers have to address how the tube will be integrated into and joined with the rest of the body structure. It’s expected the TWTs will not approach the demand levels of conventional TWBs, but the demand may be beginning with the first application seen within the next few years. Patch-type TWBs are in production today, but with very few applications. Two such applications were observed at one OEM. Patch-type TWBs involve overlaying one blank of steel on top of another, or overlapping the blanks, and then joining them, usually with spot welds. A minimal number of spot welds are used and are located in flat, minimally formed areas of the part. Additional spot welds can be added later in a weld respot line. Advantages of this concept are that the welding is simple and readily able to be produced in-house at the stamping facility. Second, the fit-up of the two parts is very good since they

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both are formed together in the same die. Reinforcement tooling can be eliminated and respot welding of the patch is simplified. Lasers continue to be the dominant TWB welding technology. There is significant momentum to investigate the advantages provided by YAG over CO2 laser in the area of process flexibility, or beam delivery, and edge-fit-up robustness. With YAG prices falling and available power increasing, YAG shows considerable promise over the next few years. Several producers of TWBs even indicated the probability of changing from the CO2 processes to YAG in their next generation of welding lines. Standard weld process control technologies focus on three-level technology:

• The first level tracks edge fit-up quality prior to welding. Edge gap and mismatch can be detected.

• The second level involves monitoring the weld itself, usually by measuring the weld plume, which provides an indirect measure of weld quality in that it is not a 100% accurate predictor of weld quality.

• The third level is to measure the weld after it is completed. Weld geometry can be measured, or ultrasonic technology can be used to detect porosity and pinholes.

Although it is critical to not send defective parts to the customer, these technologies seem to work fairly well. Control limits can be stringent and flag suspect panels for manual inspection to minimize the likelihood of shipping defective panels. Edge preparation approaches continue to differ by welding process. The major approaches involve:

• Blank die preparation OF up to 1.3 meters in edge length, • Precision shear, • Laser cutting. • Cold working, or SOUKA mash edge process prior to weld, • Twin-beam power delivery to melt more steel into the gap, and

The blank die approach is the most common and sought after approach for achieving edge fit up. Even though the small tool clearance in the blank die requires additional maintenance over conventional shearing, this cost is significantly less than the alternatives. The limitation, however, appears to be just over one meter, after which straightness and shear/break quality deteriorate the weld edge. Laser cutting provides an excellent edge fit, which supports rapid welding speeds and complex shape fit-up. Laser cutting, however, is expensive, and there are no known systems in production. No inherent problems have been cited with the SOUKA, precision shear or twin-beam processes

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3.1.1 INTRODUCTION

1.1 STUDY OBJECTIVES AND SCOPE

The charter of this state-of-the-art study was to identify current and projected developments in Tailor Welded Blank (TWB) applications and manufacturing technologies. The TWB designation is used in the broad sense to include conventional TWBs, two or more sheets of steel welded along adjacent edges as flat blanks prior to forming, tailor welded tubes (TWT) of multi-gage or grade side-walls, and patch-type TWBs, or a steel "patch" overlapping another steel blank. Although the conventional joining method has been either CO2 and YAG laser or resistance mash welding, other joining methods were also considered, including spot welding in the case of patch-type TWBs. Applications and technologies of interest in the study include current and near-future possibilities. The majority of weld systems and applications investigated are in production today. All systems are evolving as welding experience is gained and product applications evolve in complexity. The dominant welding technology was confirmed to be shifting more toward laser from resistance mash seam, with a significant focus on YAG laser because of its overall operating robustness and flexibility for non-linear requirements. Applications are also becoming more complex with longer weld lines, as on door inner and body side aperture panels, steels that are more difficult to weld, and non-linear weld seams. A significant aspect of this study included exploring the application interests and state of technology development in these areas throughout North America, Europe, and Southeast Asia, primarily Japan. One objective of this investigation was to evaluate the direction of TWB applications and welding technologies to help guide research initiatives. The TWB industry has evolved rapidly over the past ten years with major developments in:

• Broad expansion of the supply base, • High-power welding sources, • Varied edge preparation techniques for butt welding, and • Flexible welding systems utilizing beam switching, flexible jigs, etc.

In spite of the industry’s steady growth with “easier-to-justify” applications, the North American automotive and steel companies recognize that long-term continued growth would require improved product and process optimization. TWB supply costs are a major barrier to implementation because of welding costs and the logistical costs of inventory, material handling, shipping, etc. Weld cost can be reduced through improved edge preparation technologies, increased weld system throughput, or increased welding speeds and processing efficiencies, and by better product design in light of the varied processing requirements seen across the supply base. In practice, different companies have taken a variety of approaches to reduce logistical costs. The Japanese have integrated significant portions of their TWB welding supply with their in-house blanking and stamping operations to reduce inventories, material handling and damage while improving communication. Several European companies have developed standard practices for packaging and pallet design to reduce material handling costs and damage. In North America, a number of companies are developing technologies that can develop precise edge fit-up and perform non-linear welding (NLW). NLW allows for refinements in material utilization, mass reduction and forming complexity in many applications. Another purpose of this study is to learn about TWB application design and welding technologies to help further advance the North American TWB supply industry. The principal sources of information for this study were public literature references, individual interviews, site visits and company-supplied documentation. Information or developments that companies did not want to publicly disclose were not pursued for inclusion with this study. The Auto/Steel partnership wishes to thank the companies and individuals that provided material for this report.

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1.2 CONTRIBUTORS 3.1.2 AUTO/STEEL PARTNERSHIP TAILOR WELDED BLANK PROJECT TEAM MEMBERS

Cindy Alflen DaimlerChrysler Corporation Donald Anderson General Motors Corporation Peter Badgley Stelco Inc. Karen Bayus General Motors Jay Baron University of Michigan/ERIM Jeremy Bennett AK Steel Corporation Ravir Bhatnagar Ispat Inland Inc. Paul Bucklin DaimlerChrysler Ron Carpenter Ford Motor Company Dawn Castelli DaimlerChrysler Corporation Geoffery Cooper Ford Motor Company Stephen Davis Ford Motor Company Dionisyj Demianczuk LTV Steel Company Theodore Diewald Auto/Steel Partnership Larry Du Bois General Motors Corporation Mariana Forrest DaimlerChrysler Corporation Mark Garnett DaimlerChrysler Corporation Charles Gregoire National Steel Corporation Kris Gregory Ford Motor Company Bruce Hartley National Steel Corporation Darrin Keener General Motors Corporation Alex Konieczny U.S. Steel Group Andrew Lee Dofasco Inc. Bernard Levy Ispat Inland Inc. Sean Martin Dofasco Inc. William Marttila DaimlerChrysler Corporation Raj Mohan Rouge Steel Jack Noel Auto/Steel Partnership Stanley Pilchowski DaimlerChrysler Corporation Vasu Rao AK Steel Corporation Wei Wang Rouge Steel Company Susannne Wilson Stelco, Inc. Connie Yao DaimlerChrysler

3.1.3 PARTICIPATING COMPANIES

ATB Bunschoten, Netherlands AWS Ontario, Canada Ford Research Center Aachen, Germany MakAuto Ontario, Canada Medina/Shiloh Industries Medina, Ohio

Noble Industries Detroit, Michigan Olympic Laser Processing Belleville, Michigan

ProCoil Canton, Michigan Prototech Laser Fraser, Michigan

Renault Automation Evry, France Soudronic Neftenbach, Switzerland Tailor Steel Genk, Belgium Tailor Steel of America Holt, Michigan Thyssen Krupp Stahl Duisburg, Germany

TWB Monroe, Michigan VIL Chicago, Illinois

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3.1.4 TAILOR WELDED BLANK APPLICATIONS

2.1 APPLICATION DESIGNS The uniqueness of TWB applications found globally is driven more by the differences in application objectives than by the technical capabilities of available welding systems. Door inner panels, most with a single weld from top to bottom, are the dominant application worldwide and are usually driven by one or more of the following:

• Cost reduction • Structural improvement • Mass reduction

The objective of a specific application affects the design. More sophisticated door designs are seen in Europe where structural objectives are more common and volumes are somewhat smaller than in North America. Rails and pillars are also more common in Europe than in North America because of crash behavior and, to a lesser extent, mass reduction. A common North American application is the body side inner, usually with several straight line welds, with a primary objective of mass reduction. The longest welds are generally found in North America, again on the body sides. The longest documented weld on a TWB is 2.2 meters on a North American body side. Soudronic Ltd. Conducted a survey in 1998 that summarized the worldwide applications based on percentage of market share and weld seam length. Although not shown in Figure 1 below, the majority of applications consisted of a single straight-line weld. All applications, present and future, can be categorized as one of the following: • Single straight line • Multiple straight line and angular • Non-linear (curvilinear) – circular arc and undefined • Patch • TWB tubes

0

10

20

30

0 500 1000 1500 2000 2500

Seam Length (mm)

Mar

ket S

hare

(per

cent

)

Data provided by Soudronic

Doors

PillarsRails

Tunnel & Wheelhouse

Doors (NLTB)Floors & Siderings (NLTB)

Floors & Siderings

Figure 1 – Worldwide breakdown of TWB applications.

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3.1.5 STRAIGHT LINE

Simple, one straight-line weld applications are the most common worldwide. These applications are simple to weld when the weld length is short, less than 1.3 meters, and if the two blanks have differing thicknesses as most do. Applications of this type include:

• Front door inners; • Rear door inners, with shorter welds than the front door; • Longitudinal rails; • Pillars, with the B-pillar as the most common; • Cross rails; • Reinforcements; and • Other applications such as floor pans, rocker panels, shock towers, wheelhouse inners,

sill panels, etc. Typical objectives for these applications include cost reduction, mass reduction, and structural improvements. An example of a single straight-line part is shown Figure 2 below, a Japanese B-pillar application.

1.8mm

(440 MPa)

1.2mm

(440 MPa)

Major Objective: mass reduction

weld = 400mm

Figure 2 – B-pillar example of simple, one straight line weld application.

2.1.2 Multiple Straight Line and Angular

Multiple, straight line welded blanks have two or more straight welds. (Figures 3 and 4 on Page 7) Some blanks have two to three welds in the same axis, in-line, and others have parallel welds or welds in different axes, perpendicular or at angles to the first weld. Demand for applications with multiple straight lines is increasing, not only for body sides, but for engine rails as well. The objective for most body side applications is cost and mass reduction, while engine rails have structural objectives including crash management. General Motors had nine multiple straight line welded body sides in production in 2000 and one multi-weld underbody cross sill (Ref. 95). Renault Automation indicated that the main objective for developing their multi-axis jig system

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was for the Renault demand for multiple straight line welded blanks (Ref. 10) now and into the future.

Figure 3 – Multi-straight line welded body side for Jeep Grand Cherokee.

1.0mm

1.75mm

1.5mm

hinge side

Figure 4 – Multi-straight line weld door inner (VW Golf).

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Angular straight line welds offer a compromise in benefit over non-linear welds without the welding complexity. Edge fit-up is usually simpler than with curved welds and many of the mass and structural benefits can still be achieved. Systems that provide angular straight line welds often produce a blow-hole at the intersection, often located in a spot that will be trimmed out in the stamping process. Figure 5 below shows a door inner application with an angular weld that includes a weld line approximately perpendicular to the material flow in the binder at both ends.

Figure 5 – Angular straight line weld on door inner.

3.1.6 NON-LINEAR

The market for non-linear TWBs is smaller than that for conventional blanks because the incremental cost is difficult to offset by the marginal advantages. There may be cases, however, where a curved weld is needed because of structural or formability requirements that can determine whether or not an application is feasible. Figure 6 on page 9 depicts prototype efforts in this area.

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(Shock Tower) Prototype non-linear tailor welded blank with high strength steel center.

(Door Inner) Prototype non-linear tailor welded blank.

Figure 6 - Non-linear prototypes produced by Fraunhofer.

Several non-linear, or curved, TWBs have been conceived, but few have reached the development stage. The first non-linear production TWB was made by Laser Welding International of Fraser, MI, formerly Prototech Laser, and is illustrated in Figure 7 on page 10. Thyssen Krupp Stahl of Duisburg, Germany, has researched the advantages of non-linear, or curvilinear, welding on door inner panels (Ref 113) and believes that curvilinear door inners will be in production in Europe in the near future (Figure 8, page 10). One advantage of a curvilinear weld over a multiple straight-line weld is that there is no blow-hole at the inflection point. There are physical limitations to the size of the weld radius depending upon the welding system. Figure 9 on page 11 illustrates a wheelhouse design for Ford-Cologne that has been investigated at Tailor Steel of Genk, Belgium. Circular TWB applications are found in shock towers, such as those at Renault (Ref. 11). The complexity of circular TWBs is much less than that of non-defined curves because of edge fit up, where a circular disc can be inserted into a round hole, and tooling for welding in a circular path as can be performed using a rotary table.

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Non-linear Weld ApplicationFloor Panel (double attached)

Figure 7- First known non-linear production TWB - produced by Laser Welding International, formerly Prototech Laser.

1.3 m

0.98

m

t = 0.7mmt = 2.0mmt = 2.2mm

Figure 8 - Analysis of different door designs (Thyssen Krupp Stahl).

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0.75mm

1.5mm

0.75mm

Figure 9 – Curvilinear wheelhouse developmental application.

3.1.7 PATCH

The concept of a patch TWB is not new and several applications are in production. A patch TWB overlays one blank of material on top of another blank to add strength where it is needed. The two blanks are joined, usually by spot welds, before forming (Figure 10 on page 12). TWB welding constraints such as edge condition for butt welding and designing blanks for linear welding systems are eliminated. Consequently, patch TWB designs have greater flexibility and generally less cost than the conventional TWB counterpart. Major questions regarding patch TWBs concern structural performance, fatigue, and formability. Evaluating these properties may be more difficult than with conventional welded blanks, where there may be multiple steel blanks, but each blank can be modeled somewhat independently, aside from the weld line. With the patch blank, the performance of multiple layered blanks must be considered and their performance will be affected by the joining design, whether spot welds, adhesives, or another technology. One advantage of patch blanks over conventional, multi-piece assemblies is the superior fit-up that is achieved. Since the multiple pieces are formed in the same die, the fit-up between the reinforcements and larger blank is excellent. This superior fit-up can simplify respot welding and improve the structural performance and quality over a non-TWB. There are two important design considerations for patch tailor welded blanks, which are illustrated in Figure 10 on page 12. The reinforcement patches on both blanks do not extend to the edge of the larger blank and therefore remain clear of the draw die binder. This simplifies binder design and forming complexity. A second observation is that each patch is joined using either two or three spot welds and the location of these spot welds is on the “flat” area of the finished part. Minimizing the spot welds will allow for material flow on the curved surfaces. Additional spot welds, or respot welds can be added later in the assembly process, as needed.

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Floor pan bar. Patch-type tailor welded blank with two patches, each with two spot welds. This double-attached tailor welded blank is shown before and after forming.

Longitudinal rail. Patch-type tailor welded blank with one patch reinforcement (fish shape). The patch has two locating holes (one at top and one at the bottom), and three spot welds. Additional spot welds are added after forming.

Figure 10 – Two examples of patch-type tailor welded blanks.

Figure 11 on page 13 illustrates a door inner example for a conventional design, a traditional TWB with a laser weld design, and a patch design. The patch design in this illustration results in lower overall door mass and lower cost.

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subject: patch blanks vs. co nv. & lase r

opti on - spot welded1.7

0.66 1.7 0.66

0.66

1.7

co nventional 2-pc laser w elded 3-pc p atch blank

doo r inn er panel pc cos t weight # inv( mil) p c cos t weight # in v(m il) p c c os t we ig ht # inv (m il)

raw material we ight 28.52 41.81 37.85

m aterial c ost $9.10 $13.68 $12.32

b lank die inves tment 0.07 0.15 0.07

b lanking $0.69 $1.05 $0.96

laser we lding (b lank ) $0.00 $3.49 $0.00

s pot welding / invest (blank ) $0.00 $0.00 $1.48 0.1

finis h weight 12.15 17.08 13.76

hing e reinforcement

raw material we ight 9 .32

m aterial c ost $3.08 $0.00 $0.00

b lank die inves tment 0.05

b lanking $0.41 $0.00 $0.00

s tamping $1.71 0.45 $0.00 $0.00

finis h weight 4 .75

assembly cos ts / pick-up welds $0.74 0.5 $0.00 $0.74 0.2

to tal $15.73 16.9 1.07 $18.22 17.08 0.15 $15.50 13.76 0.27

invest / 400000 units / 5years $0.54 $0.08 $0.14

$16.27 $18.30 $15.64

weight improvement over conventional 18.6%

weight improvement over laser welded 19.4%

cost improvement over conventional $0.63cost improvement over laser welded $2.66

Figure 11 – Patch TWB comparison for door inner.

3.1.8 TUBES

There are several factors that contribute to the increasing interest in tailor welded tubes (TWTs). In general, tubes for body-in-white applications are hydroformed. Currently available tubes have limitations regarding their diameter to wall thickness ratio and relatively low formability due to conventional tube production processes and the resulting weld quality. One tube-welding supplier, Soudronic, indicates that they can weld thin-walled tubes using their Soutube laser welding process with a D/t ratio (tube diameter to wall thickness) of 65 - 200, where standard tube ratios would be in the order of 17 - 38. Tube shapes and tailor welded tubes can come in a variety of shapes, and can be welded with mash or laser. Figure 12 on page 14 shows four tube options:

• Cylindrical tubes, • Tailor tubes (varied wall thickness), • Oval tubes, and • Conical tubes

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Figure 12 – Four tube shapes: cylindrical, tailor shape, oval, and conical.

Tailor welded tube applications are feasible wherever hydroformed tubular applications are considered. As in flat applications, the TWTs allow for added optimization of material use. Examples of possible tailor welded tubes include:

• Exhaust manifolds; • A-pillar; • Engine compartment rails; • Light truck side rails, • Rollbars, and • Side rails.

Several companies are researching TWTs. Soudronic and AWS have welded multi-gauge tubes to produce hydro-formed TWT parts. The production technology is available, as in the Soutube process by Soudronic, to produce cylindrical and conical TWTs, but a production application has yet to be determined. Soudronic has also experimented using filler wire and CO2 laser. They have welded aluminum tubes with and without filler wire with success. ATB company of Holland and Corus in the UK have purchased Soutube welders (Ref. 11). Corus indicates that the wall thickness on the TWTs can vary from 0.6 mm to 3.0 mm. ATB believes that design integration to incorporate hydro-formed tubes into conventional auto bodies will be the limiting factor controlling demand. Thyssen Krupp Stahl also indicated plans to produce TWTs in the near future. Another type of TWT uses a sleeve in the area where reinforcement is needed. This approach is analogous to the patch type TWB where butt welding two separate pieces of material is avoided and the material is simply overlapped and attached. A second type of TWT uses an expandable foam material that can be inserted into the tube. Several companies are developing expandable form technologies, including the Fraunhofer Institute.

15

Figure 13 – Tailor welded tubes: constant OD, constant ID, and “sleeve”.

The greatest interest in welded tubes is for cylindrical or conical tubes, with conical of greatest interest, with small diameter to thickness ratios. Much less interest has been shown for tailor welded tubes (Ref. 11) in Europe. Thyssen believes that the first TWB tubes will be in production in three to four years and that the greatest challenges to the auto manufacturers will be addressing the forming and joining challenges (Also Ref. 11).

Soudronic Concept Soutube Welding

Figure 14 - Soudronic Soutube welding videos.

16

Figure 15 - Soudronic Soutube welding unit for tailor tubes.

2.1.6 HIGH STRENGTH STEEL

There is a high level of interest in using high strength steel (HSS) in TWBs for further mass reduction and structural improvements. Two concerns limiting the use of HSS is the formability in conjunction with the weld bead and other materials in the TWB and the weldability of the steel. Typical applications include the B-pillar, as the Volvo S-80 uses DP600, and longitudinal rails, as the Focus uses 340 Mpa. Several auto companies are investigating use of high strength steel on the B-Pillar of the body side but are concerned with formability. Mazda indicated that they plan a body side with high strength steel, and Toyota has several body sides that incorporate HSS. Japanese body sides, however, tend to have less depth of draw than North American designs. Filler wire may be used to increase the formability of the weld when welding with laser. The Ford Research Center and Soudronic believe that mash welding may be a better method for welding HSS because of improved fatigue resulting from the overlapped joints (Ref. 11). The Ford Research Center in Aachen, Germany is developing design guidelines for the use of HSS in TWBs. They anticipate future research on HSS TWBs that will address usage of steel grades, weld line placement, and springback prediction (Ref. 11).

2.2 NORTH AMERICAN APPLICATIONS

Future estimates for TWB demand vary according to source, but all show continued linear growth over the next several years. Figure 16 on page 17 shows two projections, one by TWB (Ref. 81) and one by AWS (Ref. 62). Another source (Ref. 4) estimated the TWB market value in 1999 at $100 million, translating into an average TWB cost of a $4.25 per piece, excluding steel cost. The estimated tonnage sold in 1999 was 315,000 tons, which translates into approximately 27 pounds per TWB.

17

Figure 16 - Projected tailor welded blank demand for North America – based on two sources

General Motors and DaimlerChrysler lead in the number of TWB applications in North America, with Ford a distant third (Ref. 81). GM has been one of the world leaders in body side applications, including DeVille, Seville, LeSabre, Aurora, Bonneville, Silverado/Sierra regular, Silverado/Sierra extended, Tahoe, Tahoe XL, Suburban, and Blazer (Ref. 95). North American body side TWBs, including GM, have tended to apply more to body side panels and have resulted in fairly long total weld lengths (Figure 17, below). GM also has a number of door inner panels, including Impala front/rear, Monte Carlo, and DeVille front/rear. In 2000, GM had an estimated 65 TWB applications as follows (Ref. 96):

• 24 door inners • 18 body side frames • 23 other

DaimlerChrysler has slightly fewer TWBs at a 50, with a large percentage of door inners, body side inners, liftgate inners, rails and reinforcements. Two DaimlerChrysler products, the Jeep Grand Cherokee and the Durango had the most single line applications in North America with eleven and nine respectively (Ref. 4).

Big-3 Body Side

• Total length of w eld lines (incl. cut outs) , about 4867m m .

1.4 bare1.0 bare

0.8 H D G 1.0 H D G

19251425

1517

Figure 17 - North American body side with over 4.8 meters of weld.

Projected Tailored Blank Demand for North America

020406080

100

1999 2000 2001 2002 2003 2004 2005

Ann

ual V

olum

e (m

illio

n pc

s.)

TWB (1999) AWS (2000)

18

The greatest level of interest in non-linear (curvilinear) TWBs exists in North America. No one in Japan expressed any significant interest and there is only moderate interest in Europe, probably for door inners. GM has shown the most interest for a variety applications, while DaimlerChrysler has shown little interest beyond single and multi-straight line TWB applications for the near future. Production applications for tailor welded blanks are beginning to reach projections. One early study identified approximately twenty-two practical applications on a car body. In 1998, ULSAB identified fifteen cost-effective applications for a high-volume vehicle, shown in Figure 18 below:

• Rail front inner (left and right) • Rail front outer (left and right) • Rocker inner (left and right) • Rail rear inner (left and right) • Rail rear outer (left and right) • Wheelhouse outer (left and right) • Body side outer (left and right) • Panel skirt

Figure 18 - ULSAB tailor welded blank applications.

Figure 19 on page 19 charts the estimated worldwide TWB demand, in parts produced.

19

-

2040

6080

100120

140160

180

1998 1999 2000 2001 2002 2003 2004M

illio

ns o

f Par

ts p

er Y

ear

Data provided by Soudronic

Figure 19 - Estimated worldwide TWB demand (in parts produced).

2.3 EUROPEAN APPLICATIONS

The leading applications for TWBs in Europe are rails and pillars, most with a single weld. In most cases, these applications are multi-gauge blanks, sometimes with high strength steel, with the objectives of mass reduction and structural improvement. Door inners are the single largest application, followed by underbody components. A distribution of European applications, provided by Thyssen Krupp Stahl, is shown in Figure 20 below.

Figure 20 – Distribution of European applications by type and quantity.

20

Volkswagen is one of the world’s largest uses of TWBs, with the Golf having approximately 23 applications over 3 models, and the Golf 4 alone having 16 applications (Ref. 11). Two of the Golf’s rear rails have one side welded with mash welding while the other is laser welded because of production availability of the equipment. The major objective of most of the Golf’s applications is part integration, for cost reduction, and crash behavior. Tailor Steel, Genk, indicated that Ford-Cologne is interested in a non-linear wheelhouse application (Ref. 11), shown in Figure 9 on page 11. The Ford Mondeo is expected to have six TWBs. The Peugeot 607 sedan has a TWB with multiple straight line welds and a design that is similar to many of Toyota’s body sides. This design makes use of several short welds along the A and B pillar using developed blanks, as shown in Figure 21, below. Shallow draw body sides are compatible with this design.

Figure 21 – Peugeot body side with “short” welds.

BMW has several door applications with designs that differ from those seen in North America. The BMW 3-series makes use of a multi-straight line welded blank on a double-attached door inner. The multi-straight line weld is made for welding efficiency since the finished door inner only has a single weld line on it. This blank is welded at Tailor Steel in Belgium and is shown in Figure 22 on page 21. The objective of this application is structural, that is, to increase the stiffness near the door locking area will reduce high-speed wind noise. BMW also has front and rear TWB door inner panels on other vehicle models. The main purpose cited on these applications is for structural improvements, or increased rigidity, and mass reduction.

21

Volume: 62,000Objective: weight reduction, structural improvementGauges: 1.8mm/0.8mmWeld: 1300mm

Figure 22 - BMW 3-series door inner.

Rover also has several TWB applications, indicating that they have front and rear door TWBs on the Rover 75 for cost reduction. They also have a rear wheelarch, or wheelhouse inner, and a side rail on the same model. The objectives of the latter applications are cost reduction and structural, respectively. The Rover Mini (R50) will have tailor welded body sides made from four blanks and three weld lines. The Mini’s body sides are justified based on structural and cost improvements. Renault is becoming an aggressive user of TWBs. Renault has body sides on 3 models in production (Ref. 11). They also have one of the few non-linear TWB applications with a circular shock tower TWB used on the Kango mini van. The Renault Laguna, produced at the Sandouville plant, has 13 TWB applications justified mainly through crash management and mass reduction objectives. The 13 Laguna applications are:

• Body sides (2) • Lower compartment rails (2) • Upper compartment rails (2) • Front and rear doors (4) • Floor pan reinforcements (2) • Plenum (1)

Audi, Volvo, BMW and Renault all make significant use of high strength steels in TWB applications. High strength steel applications are seen in rails, reinforcements and cross members. In general, Europe has few TWB side rings in production or planned; however one is currently designed with bake hardenable steel for production.

22

2.4 JAPANESE APPLICATIONS Tailor welded blanks in the Asian market are spread across Toyota, Nissan, Honda, Mazda, Daewoo, and Hyundai, with other companies using them to a lesser extent. Toyota is the most dominate user of TWBs in Asia with over 70 applications in production, and the most aggressive with several multi-straight line weld body sides. Most of the applications seen in Japan are justified for economic reasons due to material savings or tooling cost reduction through the integration of parts. Typical Toyota applications are:

• Engine rails (upper and lower), • Door inners, • Sun roof (welded in the four corners to save the material in the center), • Pillars (especially B-pillars), and • Inner body sides.

At one time Toyota produced body side outers, but found the marginal savings insufficient. Greater savings were found by welding the body side inner. On the body side inner, greater gauge differences can be welded, thereby eliminating more parts, and there is minimal concern over laser welding exposed material. The (Japan) domestic Camry is now the only body side TWB with exposed welds, and these are on a class B surface. Figure 23 on page 23 contrasts the body side inner on the Crown with the body side outer on the Camry. The body side outer blanks are all made from 0.8 mm steel of the same grade but with different coatings. The body side inner has different gauges, 1.0 mm, 1.2 mm, and 1.6 mm, with different coatings, and different steel grades, from 390 Mpa to 440 Mpa. The total length of the four body side inner welds is only 780mm and the total for the body side outer is 1.425 m. The relatively low welding cost and high steel differentiation on the body side inner illustrates the greater savings potential on the inner panel. In Georgetown, Kentucky, Toyota makes TWBs for in-house use, producing:

• Camry front door inners • Avalon body side inner • Sienna front door inners • Sienna front side member inner

The door inners require the capacity of two of their turntable weld systems, and a third system is used for the other applications. The Avalon body side inner is a typical shallow draw design with three welds: B-pillar to roof, roof to upper A-pillar, and upper A-pillar to lower A-pillar, with no rocker panel). The total weld length is about 1.050 m for all three welds. Toyota has indicated very little interest in developing non-linear, or curvilinear weld TWBs. They generally believe that there are sufficient opportunities with multi-straight line welds still to be exploited, and these offer fewer complications and nearly the same benefits of curved welds (Ref. 10). Toyota is interested in a rear door application that has two straight line welds, connected and perpendicular to each other, because there is no mirror reinforcement.

23

Figure 23 – The Toyota Camry body side outer (top) and the Toyota Crown body side inner (bottom).

Nissan is perhaps second in Asia in TWB volume to Toyota with roughly fifteen applications. They currently have no door inners in production because of concern over weld quality for these relatively long welds. A door application has been planned for a headerless door to improve structure on a small volume vehicle. Applications include:

• A double-attached center pillar, • A double-attached roof rail, • A body side outer panel with two welds connecting the rocker panel to the A and B pillars as

shown in Figure 24 on page 24, and • A body side inner panel using high strength steel in the B-pillar, shown in Figure 25 on page 24.

24

525mm 450mm

SPC 0.8 mm

Dura 0.8 mm

Nissan Body Side (Outer)• 240,000 annual volume vehicles (480,000 body sides).• Total weld length: 975mm.• Same gauge blanks (0.8mm).• Steel coated on bottom, bare on top.• Design objective: cost reduction.

Figure 24 – Nissan TWB body side (1998 production start).

Nissan Body Side (Inner)• 66,000 annual volume vehicles (132,000 body sides).• Total weld length: 760mm.• Multi-gauge blanks (1.0mm to 1.6mm).• High strength steel in B-pillar.• Design objective: mass reduction.

240mm

215mm

SPC 1.4mm

440MPa 1.6mm

440MPa 1.2mm

440MPa 1.0mm

305mm

Figure 25 – Nissan body side outer panel with high strength steel.

25

Nissan justifies most applications based on cost savings. Nissan and Toyota body sides tend to be shallow drawn panels with overall short weld lengths. Mass savings are second in importance, to cost. Nissan will continue to look at door applications in the future. Mazda has two TWB applications, a lower B-pillar reinforcement and a cowl piece. The volumes are low and the parts are welded in-house with a CO2 laser system. One of the applications recycles two pieces of offal by welding them together into a larger blank, and the weld line is stamped out of the final part. The main objective at Mazda is cost reduction and the desire to gain knowledge of the technology. In the future, Mazda would like to implement door inners and a body side TWB. They expect the body side to use HSS. Mazda has found that laser welded blanks have better corrosion resistance than mash and that laser welded blanks have better formability than mash because of the HAZ (Ref. 10).

26

3.1.9 WELD PROCESSING TECHNOLOGIES

3.2 WELDING POWER SOURCE 3.2.1 INTRODUCTION

The development of different welding technologies is progressing rapidly and the relative advantages and disadvantages of these technologies change quickly. The formability tradeoffs between mash and laser welding are not conclusive. Mash welding has a lower overall micro-hardness, but over a wider area, or heat affected zone (HAZ). One OEM study shows that laser blanks have greater tensile elongation parallel to the weld than mash welds. In contrast, however, the study showed that the laser weld failed with a lower bending fatigue close to the weld line. The performance of these technologies is also dependent upon the weld automation system incorporated. The following table subjectively compares perceived performance tradeoffs of the major tailor welded blank welding technologies. Although non-vacuum electron beam blanks have been mass-produced in the past, no known system is in operation today. The other technologies are all in production. Induction is in production at Volvo in Sweden, and the other technologies of mash seam, CO-2 laser, and YAG-laser are in production in multiple locations throughout the world.

Electron Beam

Induction Mash Seam CO-2 Laser YAG-Laser

Rework Weld no needed cold rolling no no

Coated/Uncoated possible possible in production

in production in production

Curve Welds possible no no in production high favorable

High/Low Strength possible difficult possible in production high favorable

Changing Thicknesses possible no no in

production high favorable

T-Weld Lines possible no no in production high favorable

Industrial Integration difficult good good good possible

Forming behavior very good difficult good good very good

Edge Preparation precise easy medium high precision precise

Table 1 – Comparative tradeoffs between welding technologies.

27

Technological advancements in welding technologies and systems are being made in several areas, with several key developments are in the following areas:

• Non-linear welding capability, both multiple-linear welds and curvilinear welds; • Elimination of precision shear requirements for welding. Edge fit-up is being addressed

more precise blank dies and increased welding robustness, such as welding with dual spot beams;

• In-line quality checks to assure that no defective blanks are shipped to the customer. 100% inspection systems are becoming more accurate at identifying suspect blanks;

• General process improvements, including minimizing downtime between load/unload part cycles, welding speed approaching 10 meters/min., reduction in scrap rates to under 1% in many applications, and reduced material handling through lower inventories, steel pin pallets, etc.

3.1.2 CO2 AND Nd:YAG

CO2 laser is still the dominant welding technology worldwide. Thyssen estimates that approximately three-quarters of the total North American market uses CO2 for blank welding, with Yag and mash making up the remaining 25% (Ref. 71). There are numerous different TWB manufacturing systems, but over 90% employ either CO2 or Yag laser energy sources. The CO2 laser beam can be focused more precisely than a Yag beam, a condition that offers advantages when the blank edge condition has minimal gap. The more tightly focused beam can weld faster because more of the beam is concentrated at the edge. When the edge condition is poorer, than the more dispersed Yag beam, with its “top hat” shape, simpler delivery mechanism and twin-spot capability may have advantages, although there is also current research on a twin-spot CO2 laser as well. There is interest by weld system suppliers to consider adopting Yag over CO2 laser for more complex blank applications because of edge fit-up concerns. Thyssen Krupp Stahl has installed Nd:YAG on two of their welders (Ref. 11) and cited the advantages in gap tolerance and non-linear welding flexibility. Soudronic and VIL have also investigated using Nd:YAG in lieu of CO2 laser. Another reason for the growing appeal of Nd:YAG over CO2 laser is cost. Both laser technologies have seen reductions in their cost per kilowatt of power over the past several years. Nd:YAG, however, has decreased its cost/kw faster than CO2, while seeing significant increases in the available power output. A lagging concern over Nd:YAG is still the operating cost. In particular, the replacement cost of lamps is high at about $300 apiece and the operating life is highly variable, ranging from 300 to 800 hours. Twelve lamps may be required for replacement on a 4kw Nd:YAG laser. Soudronic has conducted controlled experiments to identify the critical laser welding process variables for CO2 lasers, and have prioritized the important variables into three groups: critical, delicate, and non-critical as shown in Table 2 below.

Critical Delicate Non-Critical

• Focus diameter

• Edge contamination

• Focus position

• Shield gas tube position

• Edge straightness

• Edge quality

• Weld speed

• Laser power

• Shield gas flow rate

Table 2 – Process control variables for CO2 laser welding (Soudronic results)

28

There are several resistance mash welding systems, mostly supplied by Soudronic. This technology has been displaced by laser systems because of minimal perceived cost advantages, weld geometry disadvantages (weld-seam thickness), and concern over corrosion along the weld bead. Toyota, Nissan and DaimlerChrysler have found several applications where mash welding offered lower costs, suggesting that demand for mash welding may be decreasing, but is not likely to go away completely. The most common concern expressed over mash welding is the challenge in welding galvanized steels. Certain galvanized coatings, such as galvanneal, have been welded in volume without significant difficulty. Thyssen Krupp, possibly the largest producer of mash welded blanks, had plans to phase out mash in favor of laser welded blanks by calendar year-end 2000 (Ref. 62).

3.1.3 PLASMA AUGMENTED LASER WELDING (PALW)

Plasma augmented laser welding is a welding methodology that supplements the laser heat source with one or two plasma jet heat source(s). Combined, the laser and plasma heat source produce a weld with a wider heat affected zone, which produces a more gradual weld transition from thicker to thinner gauge steels. This wider weld allows for a more forgiving gap tolerance, potentially eliminating the need for precision edge shearing or die cut edges. The increased energy also allows for faster weld speeds. Several companies have been experimenting with PALW for TWBs including BMW (Ref. 31). Liburdi Pulsweld (see appendix) has been conducting in-house research for TWB applications including aluminum welded blanks. Toyota has a production welded part today using plasma welding, supplied by Pacific Industry, on a center pillar (Ref. 10).

3.1.4 INDUCTION AND NON-VACUUM ELECTRON BEAM

Volvo continues to use induction welding, but the comparative success of this method versus laser is not well known. ABB and Kuka may be marketing this technology outside of Volvo, perhaps with a licensing agreement with Volvo; however, there has been low interest due primarily to the weld geometry (Ref. 11). Non-vacuum electron beam welding still has the potential to produce welded blanks. An electron beam equipment supplier, PTR of Enfield, CT, has conducted laboratory welds on both steel and aluminum. Thyssen Krupp Stahl indicated that they have conducted electron beam studies, and they believe that the technology has potential in the future. This technology was originally in production in the 1980s on heavy steel TWB components.

3.1.5 MASH WELDING

Mash welded blanks are joined with a technology that is more familiar to the auto companies than is laser welding. Resistance mash welding is a contact welding process that uses roller wheels and electrical current and welds on an overlapped sheet steel edge. This technology is not as new as butt-edge laser welding and has been widely applied to many applications including cans for the food industry and steel gas tanks for automobiles. Soudronic AG in Neftenbach, Switzerland, is a world leader in supplying this technology. One of the recognized advantages of mash welding is the fact that this resistance welding technology is familiar to automotive environments and the infrastructure to operate and maintain this equipment is fairly well established. A counter argument voiced by several welded-blank suppliers is, while they recognize the higher initial investment into learning laser welding technology, the long-term benefit is that laser technology has fewer moving parts and requires less ongoing maintenance.

29

The pros and cons between mash and laser welded blanks have been discussed for years, particularly in the early 1990s when it was not clear which technology would win favor. Most of the early disadvantages of laser welding have been overcome. Several of these disadvantages included higher operating complexity, higher investment costs, lower welding power and slow welding, edge preparation complexity, and formability concerns because of the harder weld. The disadvantages of mash welding were the number of moving parts that required maintenance, welding of coated materials, possible corrosion due to coating removal during weld, wider heat affected zone (HAZ), and increased weld bead thickness due to the overlapped edge. As both technologies have evolved, many of these issues for each have been resolved. An important issue remains relative to formability differences, which suggests that the harder but narrower HAZ from laser welds in many applications is advantageous over the mash weld. Mash welding is still more forgiving in edge fit-up than laser so this can be an advantage in some cases. The cost and power relationship between mash and laser has been eliminated. As blank applications trend toward more complex, multi-weld and even curvilinear welds, the more flexible laser can have an advantage with the proper tooling. In summary, the advantages of laser welding, on average, have outweighed the advantages of mash welding, and laser has become the dominant technology. There are still, however, applications where mash has advantages, and a mix of these technologies is likely for some time.

lide: 37

Weld Comparison

Figure 26 - Comparison of Four Welding Methods.

30

3.2 DUAL SPOT WELDING (MULTI-SPOT) Several companies have developed multi-spot welding, usually dual spot, which has been shown to be practical with both Nd:YAG and CO2 laser. The main advantage of dual spot welding is that more power is distributed wider along the path, thus allowing more steel to fill the gap. The result is a slower welding speed but a broader HAZ and greater likelihood of an acceptable weld. Another advantage of dual spot is that when a gap is present, energy is not lost through the gap, which can occur if the weld beam is too narrowly focused. Tailor Steel indicated that they are investigating dual spot welding for non-linear, or curvilinear welds because of the difficulty of achieving close edge fit-up. They are currently using dual spot even on linear welds because of its robustness to edge conditions. One challenge with curvilinear welds, though, is that the two spots do not travel at the same speed around a radius. Since the inner spot travels slower, the nature of the weld changes. Both process tracking software and associated hardware are under development for this problem (Ref. 11).

3.3 EDGE & BLANK PREPARATION Good edge conditions, or the lack of burrs and gaps between the blanks, is a key to achieving quality welds and maximizing weld speed. Poor edge conditions require special provisions such as close process control monitoring, twin-spot laser to melt material into the gap, and slower weld speeds. Most companies and welding systems rely on precise blank dies for edge preparation. In Asia, Toyota, Nissan and Mazda have all developed precise blank die edge technology and require that product design limit weld length based upon this capability. At Nissan, their blank die uses a closer shear edge clearance and special guides (Ref. 40). Toyota indicated that they require a die clearance of less than or equal to 0.05 mm for blank edges. This requirement results in doubling blank die maintenance. Thyssen Krupp Stahl indicated that 98% of the blanks that they weld utilize blanking dies as a means of producing a weld-able edge condition (Ref. 11). Thyssen estimates that about 85% of the blanks welded in Europe rely on blank dies for edge preparation. An oscillating shear is not adequate in most cases to produce weldable edges. Thyssen Krupp Stahl and Medina Blanking both indicated that edge condition, particularly straightness, couldn’t be maintained with an oscillating shear, even for edges to be mash welded. However, a fixed shear may produce an acceptable edge up to some length. Tailor Steel in Belgium uses a “slap die” to make blanks which produces an acceptable welding edge for Soudronic and Toyota systems. This die requires maintenance every 700,000 hits. Flattening rollers are required on the blanker with 22 roller sets. Blank flatness was cited as a major problem at the Tailor Steel of America facility during their early trials. The decision to use a blank die versus a precision shear is blank shape and volume dependent. Thyssen Krupp Stahl suggests that when the annual volume of a contoured blank exceeds 200,000 units per year, the volume warrants a blank die because of the material savings. The Soudronic SOUKA technology cold mashes the edges together before laser welding. Blanks are butt welded together and the roller mash process is reportedly, according to ATB, capable of tolerating gaps up to 0.3 mm (Ref. 11).

31

Figure 27 – Soudronic SOUKA® process for edge preparation.

Toyota and Renault have used a method wherein oversize blanks are crowned and then clamped down to exert pressure on the edge. Renault does this with a circular shock tower disc inserted into a blanked hole (Ref. 11). Toyota accomplishes this with blanked pieces, developed blanks produced from dies, in their assembly jig on body sides. Another strategy developed by Thyssen Krupp Stahl is the “sheet-in-sheet" method that can be used on circular shock tower applications. This method places both sheets on top of one another and punches the desired shape, a circular disc in this case, so that the top thicker gauge sheet displaces the same shape out of the bottom piece, leaving a close edge fit-up around the part. The sheared edge condition is sufficient to produce a good weld (Ref. 11).

Pad Power Up

Moving Increasing Side Force

Changing Blade Clearance

Pad

Lower Blade

UpperBlade

Blank

Guide Post

Backup Frame

Backup Flame Size up

Added Guide UnitSpecial Blade &

Cutting Condition

Figure 28 – Special blank die design for precise edge condition used at Nissan.

32

3.4 WELDING PARAMETERS Virtually all laser welding system suppliers suggest the use of a shielding gas during the welding process, with various combinations of helium and nitrogen typically used. AWS indicated that a shielding gas is not required with Nd:YAG welding (Ref. 62), but companies experienced with Nd:YAG recommend it. Clamping technology varies by system design, but predominant methods include hydraulic and magnetic clamps, sometimes with air, or vacuum, assistance. Several welding system employ seam tracking devices with adaptive control for welding. These systems typically use a laser beam to track and guide the weld path with the table or laser making small lateral adjustments, within a few millimeters. Seam tracking systems, like the Soudronic Souvis 1, can often test several criteria, including lateral edge position, excessive gap, mismatch, edge defects, and blank position. Not all welding systems rely on seam tracking, as Prototech Laser welds a semi-circular arc without tracking. Renault Automation indicated that they use seam tracking software from MVS, a Canadian company (Ref. 11). Their concern, however, is that commercially available software is adequate for tracking straight line paths, but software for non-linear paths is not yet commercially available. Weld systems that rely on seam tracking, as opposed to having rigidly programmed weld paths, may have a limitation on welding radii. One supplier indicated that a 100 mm radius may be the lower limit when seam tracking is used, as opposed to a 40-50 mm radius for non-seam tracking systems.

3.5 TAILOR WELDED BLANK FORMABILITY 1

3.5.1 INTRODUCTION

Press formability of TWBs is related to the relative material strengths and the ductility of the weld. The pattern of deformation has a strong impact on overall formability, making general rules-of-thumb difficult to develop. The deformation pattern, including weld line displacement, is governed largely by material selection, weld line placement or orientation, and the forming forces. Both laser and mash welds reduce ductility of parent mild steels by 50% to 75% for parallel strains. Generally, the weld properties themselves have much less affect on deformation behavior. TWB welds are equal to or greater in strength than the parent material when made to generally acceptable standards (Please see A/SP TWB Acceptance Guidelines). Generally, it was found that laser welds are stronger and mash welds are equal in strength to the stronger of the two blank materials. Weld line formability is important for at least two reasons:

• Rupture during forming; • Transverse weld line movements affect die design and wear, and possibly part

designs. The designer must consider these factors in designing the TWB, in conjunction with the part performance objectives. Weld line movement can be controlled using draw beads or differentiated blank holding. Differentiated blank holding technology is not in wide use because of added die cost and forming complexity. The reduced formability in the weld region versus that of the un-welded parent material can be managed in several ways:

• Weld line placement: amount of strain and its orientation to major strain; • Selecting a forming method: stretch, draw, stretch flange; • Weld profile: peak hardness versus width of weld, controllable in the welding process; • Material selection which affects weldability and the weld profile.

1 A significant contribution of information for this section was obtained from references 87 and 103.

33

Different forming methods affect TWB formability. Stretch forming results in the lowest formability when the weld is parallel to the major strain axis because of the limited weld bead ductility. When the major strain is perpendicular to the weld, the weaker material becomes the limiting factor. The TWB weld has minimal impact on deep drawing. Stretch flange forming has a 25% to 30% reduction in formability.

3.5.2 FORMABILITY TESTING: PARALLEL AND TRANSVERSE MAJOR STRAIN

Formability testing of the welded blank seam is recognized as an effective predictor for blank formability. The most common testing methods are tensile tests, various LDH tests with different punch geometries, Olsen Cup, and the OSU formability test. These physical tests showed significant sensitivity to punch and specimen shape. Finite element analyses also provide some meaningful results, but to a limited mix of weld profile and material types. Experimental results showed that weld failure in a laser welded blank depended on the weld line orientation relative to the major strain and the relative strength of the two materials. Blank failure occurred parallel to the weld in the weaker material when the major strain was perpendicular to the weld orientation. The size of the welded blank or test sample affected how close the failure was to the weld. Wider material samples showed the failure closer to the weld. Blank failure occurred across the weld when the major strain was parallel to the weld orientation, as shown in Figure 29 below. For optimum performance, the weld bead should be parallel to the major strain axis to prevent the failure in the weaker material.

stron g

stron g

w eak

w eak

M ajor S tra in

M ajor S tra in

w eld fa ilu re

Figure 29 - Failure patterns for tailor welded blanks.

3.5.3 WELDING AND WELD PROFILE

Several opinions exist regarding the importance of peak weld hardness versus the weld width. Greater hardness reduces the ductility and therefore reduces the formability of the weld. Increased welding speeds generally require higher energy intensity at the weld which increases peak hardness. In the case of laser welded blanks, this may require more precise edge fit-up so

34

that the energy beam can be more narrowly focused at the weld seam. Higher intensity laser weld seams generally produce narrower weld widths; however, some studies have shown that the cross-sectional area of increased hardness at the weld seam is more important than peak hardness. The formability appears to be related to a function of the weld hardness divided by the area of the HAZ (H/HAZ). Overall formability is then critically important to two offsetting factors:

• Reduced weld seam width, and • Reduced peak weld hardness.

Generally it has been found that mash welds are more ductile than laser welds because of their lower peak hardness. If the mash weld has to be cold planished to reduce the weld seam thickness, then the hardness can be equal to or greater than the laser weld. Warm planishing has minimal effect on mash seam ductility. The parent material significantly affects weld ductility. Low alloy, or mild, and interstitial-free steels can normally be welded at high speeds, produce narrower weld widths, and have higher formability than other steels. High strength steel tends to produce harder welds, which may require slower welding speeds in order maintain sufficient formability.

3.6 DEFECTS AND DEFECT DETECTION

3.6.1 WELD QUALITY

The most common method of direct testing of weld quality is a destructive test, such as the Erichsen cup test, and sometimes a peel test. Toyota reserves one blank per pallet for destructive testing, and tests the weld every several inches (Ref. 10). Renault also uses the Erichsen test, but tests welded blanks once per shift (Ref. 11). Tailor Steel of America in Holt, MI also conducts the Erichsen test on one blank per pallet. Many producers indicate that they are able to achieve defect rates of less than 2% once steady state is reached (Ref. 11). Tailor Steel of America indicated that they experienced 3%, but on fairly complex body sides for GM containing three long welds. Several on-line weld-monitoring technologies are in various stages of readiness today (Ref. 81). Two developmental systems involve video keyhole analysis and laser ultrasonic. The most commonly use systems today include:

• Weld plasma monitoring; • Structured light profilometry; • Electro-magnetic acoustic transducer (EMAT); • Pinhole detection.

3.6.2 WELD GEOMETRY

The weld profile is a strong indicator of an acceptable weld. Several welding systems incorporate weld profile tracking within a few inches after the welding process and send a signal to “reject” the part if the profile is outside an established tolerance. A laser beam is used in conjunction with a CCD camera. Typical test criteria include weld seam concavity, seam convexity, mismatch, bead width, weld penetration, or lack of, and lateral bead position. These systems have been observed on Soudronic (Souvis 2), TWB, Toyota, and other welding systems. In practice, the weld quality monitoring systems have not proven to be consistently and uniformly adequate for all welding operations. Companies wishing not to allow defects to be shipped either set the sensitivity of the monitoring software to identify a large percentage of false positive readings that are not actual defects or supplement the process with operator inspection. Operators in some cases are used to visually inspect welds 100% of the time. One supplier

35

indicated that approximately 2% to 3% of the welded blanks were defective, and that 0.15% of the defects were actually shipped.

THYSSEN KRUPP STAHLTHYSSEN KRUPP STAHLTHYSSEN KRUPP STAHL

Plasma Monitor

Profile Monitor

Pin-Hole MonitorFocusing Mirror

Laser Beam

Plasma Sensor Laser Scanner

Light Sensor

Light or Laser

Figure 30 – Typical process monitoring approach for potential defect identification.

Some companies, including Mazda and Power Lasers, are developing a weld plume monitoring technology that measures the plasma intensity, bead shape and temperature. Software algorithms are used to evaluate these parameters on-line and estimate whether or not a defective part is being produced (Ref. 10). Renault Automation uses a plasma sensor and an IR check that identifies gap and mismatch edge conditions (Ref. 11). Nissan has an in process monitoring system that detects pitting and weld underfill and can identify when the welding parameters deviate from optimal conditions (Ref. 67). This process uses two sensing systems that sense the intensity of light emission from the laser-induced plasma and the weld plume.

3.6.3 POROSITY AND PINHOLES

Pinholes are difficult to detect automatically. Thyssen Krupp Stahl, Prototech Laser, and Toyota have 100% operator inspection of the blanks to check for pinholes and other visual defects such as blow through. Several system providers and developers also use a CCD camera and laser beam to check the seam but with limited success in trying to detect porosity and other weld seam imperfections, such as discontinuities. One TWB producer indicated that their philosophy is to set the seam checker to “very sensitive”, thereby allowing an operator to manually check all suspect blanks. When this is done, 90% of the suspect blanks are acceptable. An ultrasonic technology has shown promise in detecting pinholes, porosity, concavity and gaps with a diameter greater than 0.2 mm. It can also identify if the edge gap between the blanks is

36

unacceptable. This equipment, Te mate, is in use at ProCoil. Tailor Steel of America also indicated that they use ultrasonic testing on 100% of their blanks.

3.7 WELDING PATCH BLANKS

Although there are several viable approaches to attaching patch blanks, such as laser welding or adhesives, spot welding is the only known method used in production today. Both examples shown in Figure 10 on page 12 use spot welds applied using an automated carousel. In these applications, the welding system is fast, producing welded blanks in 8 to 9 seconds per part. Several important considerations for patch spot welding include part gaging, the number of welds chosen for the blank, and their location. Part gaging, or locating the two parts relative to one another, is important for uniform quality. The “fish” shaped blank on the bottom in Figure 10 is gaged by using locating holes in both blanks. Two holes near the opposite ends of the patch blank are located with steel pins in the welding fixture. This method is simple, highly repeatable, and produces the desired result. Blanks that cannot accommodate holes through them, such as the blank on the top in Figure 10, require another means for locating. The method used in Figure 10 places the reinforcements on the fixture under the larger blank with stops in the fixture. This method occasionally results in double blanks and produces lower location repeatability.

The patch type blanks in Figure 10 show a minimal number of spot welds. The objective of these welds is to hold the parts together during forming and additional respot welds can be added later. The longitudinal rail in Figure 10 has twenty additional spot welds added after forming. The small blank has two spot welds and the larger one has three. These welds are located on the “flat” of the part as far apart as possible. The flat part area is less subject to forming strain and will be more likely not to fail during the forming operation.

37

4.0 MANUFACTURING SYSTEMS AND SUPPLIERS 4.1 MANUFACTURING SYSTEMS - PRODUCTION Tailor welded blank production has evolved significantly since the mid-1980s. Resistance mash seam welding has lost favor to CO2 and YAG laser principally due to falling prices, increased laser power, and the constraints of welding coated steels. Mash welding is still in production in several applications where it has advantages. Weld designs have also become more complicated with multi-weld and non-linear welding. These changes have encouraged a number of new welding technologies. Traditional welding systems began with clamping, straight-line weld lines using either fixed optics or flying optics such as VIL and Soudronic. Additional lines were developed with “flow-through” capability with high capacity, such as the Thyssen Conti line. Jig lines were developed for blanks with multiple welds where all the blanks can be loaded in a single step, such as at Toyota and Tailor Steel of America. Future system development is focusing on non-linear welding lines that require sophisticated edge tracking, multi-axis weld heads, complex clamping technology, and precise edge fit-up. Suppliers in North America and Europe use a mix of commercial welding systems and in-house proprietary systems. The most common systems are “flow-through” systems wherein blanks are loaded at one end, run through a series of processes, and unloaded at the other end. Many flow-through systems also use beam switching when the production volume is high enough to justify the added investment. Beam switching allows for increased capacity in situations where the weld time exceeds the load/unload time. If the load/unload time is significant, typically observed from 8 to 20 seconds per cycle, then the laser can switch to another weld gantry while the first one is re-cycling. Typical flow-through systems include AWS, Soudronic (Figure 31 on page 38), Thyssen Conti (Figure 33 on page 38), and VIL. The processing steps include some or all of the following:

• De-stack, sometimes with fanning magnets or devices to check for double blanks; • Precision edge shear, such as on VIL systems, or edge mashing, only on Soudronic; • Welding and online process monitoring; • Dimpling; • Weld seam cleaning and oiling; • Turnover; • Stacking of “good” and “bad” stacks

38

25

Figure 31 - Soudronic laser shuttle system.

Soudronic Laser Welding (SOULAS)

Figure 32 - Soudronic SOULAS welding system video.

Figure 33 - Thyssen Conti flow-through system (with jig pallets).

39

Another manufacturing approach is to use shuttle, or indexing, jig systems. These systems are in use by Renault, Tailor Steel of America, and Futaba. Indexing systems have a single weld tool with indexing parts, thus eliminating the need for beam switching. These systems usually index into the weld tool when the opposite side indexes out. In this fashion, blanks can be loaded and unloaded while the opposite shuttle is in the tool being welded. Secondary processing, such as weld cleaning or dimpling, are often offline. Tailor Steel of America has built in parallel turnover and stacking stations (Figure 34 below). Renault Automation (Figure 35 on page 40) has an indexing jig system wherein the gantry operates in one axis and the jig itself operates on a different axis. This system is capable of curvilinear welding with the necessary seam tracking and yet to be developed control software.

Figure 34 – Schematic of indexing jig/shuttle system with parallel turnover and stacking stations.

40

Figure 35 – Schematic of Renault Automation indexing jig system with 2-axis weld capability. Table 3 (pages 45 and 46) lists several of the major commercial welding systems available and which are currently in use around the world. See the appendix for specific contact information for these companies. In Asia, Toyota and Nissan have the most advanced strategies for developing TWB welding systems. The Japanese companies tend to favor CO2 laser for power, but are looking at Nd:Yag for possible future systems. Some outside suppliers provide blanks using mash welding. Nissan has a development path from their Generation I through Generation IV systems (Ref. 40). Major objectives are to develop robust systems requiring minimal maintenance and containing investment cost while maintaining current production volume capability (Ref. 10). Nissan currently has Generation II at Kyushu, U.S., and the UK, and Generation III at Oppama and Tochigi in production. Characteristics progress from a simple linear gantry system (Generation I, which is now phased out) to a state-of-the-art jig pallet system with beam switching for multiple straight line, multiple welds (Figure 36 on page 41). Nissan envisions that their next generation will be Generation IV with curvilinear capability, probably using a Nd:YAG laser. Because of the merger relationship between Renault and Nissan, Nissan is evaluating their Generation IV strategy in light of the curvilinear-capabilities of the system at Renault Automation. It is likely that a single curvilinear system strategy will be chosen.

41

P 2P0

50

100

150

0.5P 1.5P 2.5P

Prod

uctio

n C

apab

ility

K sheets/460hr

Generation IVSinge linear

&Curve

Generation IISinge linear

Generation IIISingle linear &

Multiple linear

Investment Cost

Door inner : weld length 53 inch

Welding cost:Target 2 cents / inch

Generation ISinge linear

Figure 36 – Nissan TWB welding system development strategy.

Figure 37 - Nissan Generation III welding system.

42

Nissan Welding Systems

Figure 38 - NissanGeneration III video.

The Toyota welding systems have not changed significantly since their original development. They continue to use a family of three systems, small, medium and large, with the majority of applications run on the medium-size turntable. Their large blank welder was designed primarily for body sides and has two laser resonators. Toyota indicated that the system is generally underutilized, using only one laser and making multiple small parts on a single jig. Toyota’s medium size turntable system has three axes, two on the gantry and one with a rotating laser head, which could be used for curvilinear welds. One of the shortcomings of the Toyota turntable system is the time it takes to rotate each time it loads a new set of blanks. This approximately 8.5 seconds is constant for all blanks, regardless of welding time. Tailor Steel Genk reported a preference for indexing systems over the turntable system because of this indexing time (Ref. 11). Tailor Steel’s indexing system that began with the Toyota turntable design can be seen at Tailor Steel of America (shown in Figure 34, page 39). Toyota indicated that they are not pursuing curvilinear welds. Toyota is known for using beam weaving during the welding process. Both Tailor Steel Genk and Tailor Steel of America have experienced mixed success using beam weaving, finding that it slows the welding process and does not always correct for edge fit-up problems. Even though Toyota continues to use beam weaving on most of its welding, both Tailor Steel facilities have stopped using it mainly because it reduces weld speed. One Toyota process in Georgetown, Kentucky was observed welding door inner panels with beam weaving at approximately 3.0 meters per minute, considerably slower than commercial speeds of around 7.0 meters per minute. The Mazda in-house welding system uses a CO2 laser and indexing jig concept. A jig is part-specific tooling for holding the blanks. The weld system has multi-axis capability with a moving optics, and Mazda may develop multi-straight line weld applications in the future. Similar to the Nissan development path, many TWB companies started with simple, usually single-weld application welding systems. The evolution has been toward multi-weld lines, which often meant connecting several single-weld gantries, usually with some intermediate edge preparation system. Several companies today are continuing the evolution into curvilinear system, including:

• ATB (X-Y Held gantry), • Thyssen Krupp Stahl (jig system), • Renault Automation (jig system), • Tailor Steel (Toyota turntable/indexing jig system), • TWB (jig system) • AWS

43

Figure 39 - Layout of Thyssen non-linear welding line that uses jigs.

5.2 INTEGRATED LASER CUTTING AND WELDING (RESEARCH) The Fraunhofer Institute has been developing a high-power CO2 laser welding system that relies on CO2 laser cutting for edge preparation. The precise edge fit-up provided by laser cutting eliminates the need for seam tracking. This system is capable of sophisticated shapes, including curvilinear welds, and fast welding speeds. Part specific jigs are used to hold parts during cutting and welding. The part jigs have a dimensional window of 2 by 4 meters, allowing for a single body side or multiple smaller parts on a single jig. The Fraunhofer Institute has welded linear and non-linear welds with this concept: however, a production version of the equipment has not yet been produced. Generally, this system is seen as having unique, sophisticated capabilities, but at a somewhat higher price than currently available equipment.

44

Figure 40 - Conceptual Fraunhofer welding system with two CO2 laser resonators – one for blank cutting and one for welding.

45

Name Companies

With Technology

Power Source Edge Prep. Welding

Capability Comments

Automated Welding Systems (AWS)

• Medina • Olympic Laser

Processing • Ohio Welded

Blanks • Eko Stahl

(Germany)

Nd:YAG Blank die 3-axis • Dual spot available with vision tracking and gap validation

• German subsidiary established to build and install in Europe

Nissan • Nissan (Japan, UK, North America)

CO2 Blank die 1-axis and multi-axis

• Weld bead monitoring for defect detection.

• Simple, straight line CO2 welding systems initially

• Beam switching systems with part-specific jigs now in production

• Working with Renault Automation in choosing a single best approach

• Curvilinear welds under development

Northelfer (Thyssen Conti)

• Thyssen Krupp Stahl

• TWB • Galvasud

CO2 Blank die and precision shear

1-axis • “Flow-through” system • Systems available

only in Thyssen group

Renault Automation

• Renault CO2 Blank die 1-axis and multi axis

• Shuttle system with curvilinear capability.

• Working with Nissan to identify combination of best technologies.

Soudronic • ProCoil (Michigan)

• ATB (Netherlands)

• Cockerill (Belgium)

• Voest Alpine (Austria)

• Ferolene (Brasil)

• Tailor Metal (Spain)

• Rio Negro (Brasil)

• Tailor Steel (Belgium)

CO2 Mash edges (Souka)

1-axis • CCD camera tracking and adaptive control, weld bead quality monitoring

• Developing multi-axis capability (multi-straight lines) and possible curvilinear systems for future

• Researching tradeoffs between CO2 and Yag

• Setting up R&D site in Michigan

46

Toyota • Toyota (Japan),

• Tailor Steel (Belgium)

• Tailor Steel (USA)

CO2 Blank die Multi-axis • Family of three welding systems (with derivatives from these three).

• All systems currently use CO2

• Investigating PALW and Yag power sources.

• Curvilinear welds possible, but not explored.

VIL • MakAuto • Ohio Welded

Blank • Jefferson

Blanking • LWB Ltd. (UK) • Honda (Ohio

and Canada) • Daewoo

(Korea) • TWB

CO2 and Nd:YAG

Precision Shear

1-axis • All systems rely on precision shear

• Provide weld systems with either CO2 or Yag – customer choice.

• Most recent systems developed with Yag.

• Also sell weld system components such as precision shear and automation

Table 3 – Commercially Available TWB Welding Systems

47

Name Companies Power Source

Edge Prep.

Welding Capability Comments

Thyssen • Thyssen Krupp Stahl

Blank die

• Multi-axis capability for curvilinear welds

Honda • Honda of America (Ohio)

• Honda (Japan)

Nd: Yag Precision shear

Noble Industries (formerly Utilase)

• CO2 Blank die and precision shear

• Mixture of manual and high-volume automated systems.

Laser Welding International (Prototech)

• Laser Weld International (Prototech)

CO2 Blank die • First production job for curvilinear weld (General Motors)

• Manual load/unload Power Lasers • Dofasco CO2 Blank

die and precision

shear

Table 4 – Proprietary TWB welding systems.

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5.3 TAILOR WELDED BLANK SUPPLIERS

5.4 NORTH AMERICA

The number of TWB suppliers has grown significantly during the 1990’s, and many of the North American suppliers have business relationships with steel companies or steel processors. In 1990 there were three suppliers offering a mix of CO2 laser and mash welded blanks. The “Big 2,” Thyssen and Utilase, dominated nearly 100% of the welding market. In 2000 there are approximately thirteen suppliers spread across seventeen locations (Ref. 81). But the “Big 2,” now, TWB, formerly Thyssen, and Noble Industries, which acquired Utilase, continue to dominate market share with about 80% to 90% of the market [Refs. 11, 81). The major commercial suppliers for TWBs in North America include (see Appendix for contact list):

• Jefferson Blanking (Shiloh Industries) • MakAuto • Noble Industries • Ohio Welded Blank (Shiloh Industries) • Olympic Laser Processing • Procoil • Prototech • Tailor Steel of America • TWB

Although still available, mash welding has lost favor to laser, and laser systems are readily available with either CO2 or Nd:YAG power sources. There is little interest today in mash welding lines, and the several applications today being welded by mash systems at Thyssen Krupp Stahl, ATB, Mazda and Toyota are welded on older equipment. Another factor contributing to the demise is that as fewer systems are available for production, fewer systems are also available for backup capacity. A list of North American suppliers can be found in the Appendix). Growth of in-house welding systems at the automotive OEMs has progressed more slowly. In the early 1990’s, GM installed a VIL CO2 laser system at its Oshawa plant but eventually discontinued production. Several other installations at GM plants were contemplated but did not materialize. DaimlerChrysler has successfully installed two Soudronic mash welding systems in Toluca, Mexico. Ford has not installed any welding systems in North America. The Japanese transplants have been slightly more aggressive with in-house welding lines at Toyota, with 3 in Georgetown, Nissan, with 1 in Smryna, and Honda, with 1 in Marysville.

4.3.2 EUROPE

The number of TWB suppliers has grown similarly in Europe, but with several differences. The majority of the suppliers in Europe are owned by or have strong ties to steel companies. Approximately 95% of the European welding capacity is owned by three steel conglomerates: Usinor of French, Thyssen of Germany, and Tailor Steel of Belgium. The philosophy of European producers has been to vertically integrate TWB supply with steel allowing for “full-service” support, thus improving the likelihood of selling more steel (Refs. 11, 62). By staying closely integrated with their larger steel company parents, they are able to offer more design engineering and technical support when needed.

European companies have been developing acceptance weld guidelines through the consortium VDI (Ref. 11). Thyssen Krupp Stahl has the world’s largest production resources with facilities and joint ventures throughout North America, South America, and Europe. They produce approximately 45% of the

49

European market’s demand, including ten of the parts on the VW Golf. They have mass-produced TWBs since 1991 with mash and 1992 with CO2 laser, and have facilities or joint ventures that include:

• 2 facilities in Duisburg Germany; • Dortmond (Hoest Plantinen); • A planned facility in Wolfsburg to supply VW; • TWB in Monroe, Michigan; • Euroweld joint venture in Italy to supply Fiat; • GalvaSud in Brazil; • A planned facility in the UK.

There are a few exceptions wherein automotive OEMs are welding TWBs in-house. Volvo has traditionally welded many of its blanks in-house. Today, they weld many of their own blanks using both mash welding, with Soudronic equipment), and their own in-house developed induction welding lines. A second exception is Renault, which welds blanks in-house at plants in Douai, Flin, Valladolid, and Sandouville using Renault Automation laser welding equipment. A third exception is Ford-Cologne where they mash weld the Fiesta engine rail using Soudronic equipment. Aside from the Renault and Volvo exceptions, the trend by European auto companies is to purchase TWBs from outside suppliers (Ref. 11). Some suppliers can support an argument for central supply sources rather than numerous satellite plants next to the customer. While satellite plants reduce shipping costs and improve communication, they can be a strain on the supplier. Small suppliers would become vulnerable to spreading expertise across too many facilities (Ref. 11). Both Thyssen Krupp Stahl and Solblanc are setting up satellite plants. Voest-Alpine Euro Platinen has indicated an interest in expanding their operations in Europe and into North America (Ref. 11). ATB has installed a Held gantry for welding large 4 x 6 meter blanks. Their current application is a truck roof that is welded down the center due to coil size limitations. This system uses a new 6.0 kw Wegmann laser being promoted as having lower operating costs than other resonators. The European companies may have some cost advantages over North America because of several logistical strategies. Similar to the Japanese, many European applications have short welds that allow them to rely more on blank edge preparation. Consequently, most European suppliers have blanking capability in-house. The use of blank dies aids in eliminating a secondary step of precision shearing and often produces more efficient material utilization due to nesting of blanks. Another advantage is the use of standardized steel pin pallets that reduce material handling and protect TWBs from damage. Finally, lower inventory levels reduce inventory holding costs and help to reduce or eliminate the need for dimpling and weld bead protection from corrosion. Several European companies are developing non-linear, or curvilinear, welding systems for applications in the near future. Renault Automation is constructing a system and developing necessary tracking software (Ref. 11). This system will likely be a derivative of their jig/shuttle system. Soudronic is also developing a system with curvilinear capability called Soutrac (Ref. 11). Soudronic already has a system capable of multiple straight line “chevron” blanks using their current CO2 laser system with an adjustment to turn the blank to weld at a different straight-line angle while continuing the same weld. Thyssen Krupp Stahl has developed a weld line with the capability to produce non-linear welds. Early trials in Duisburg have been on multi-straight line welds, but curvilinear welds are possible with additional developments. This system uses eight jigs that reduce part loading/unloading time between blanks, but increases investment cost. Flexibility and changeover time may also be improved through the multiple jig concept (Figure 39, page 43).

50

5.5 ASIA

The Asian market is more integrated than either Europe or North America. All of the in-house weld systems in Japan are engineered in-house or purchased from another company that developed it in-house, while Korean companies Hyundai and Daewoo have purchased commercial systems. The TWB suppliers do not perceive the Korean market as offering much potential in the near future because of the tendency to produce TWBs in-house. The Japanese cite several advantages to in-house production:

• Improved communication; • Lower logistical costs; • Control over development of the technology.

Ten years ago, there were no outside suppliers in Japan, but today, Toyota alone uses the following suppliers:

• Yajima; • Kanto Motors (laser); • Auto Works (laser); • Toyota Auto Body (laser and plasma); • Daihatsu (mash); • Toyota Iron Works (mash); • Pacific Industries (plasma), and • Futaba (laser)

Another company, Toa, has plans to sell blanks to Fuji Heavy Industries. Other Asian auto companies known to be using TWBs, including Nissan, Honda, Mazda, Daewoo and Hyundai, weld most applications in-house. Nissan has indicated that Nissan Shatai plans to install a Yag welding system next year to produce TWBs. There is a slow transition to outside suppliers as the technology matures and simpler applications, such as single, short welds can be cost justified outside (Refs. 10, 62).

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5.6 SUPPLY LOGISTICS

5.7 PALLETS Several European auto companies require steel pin pallets for shipment of completed blanks from the supplier to the stamping plant. VW is standardizing their steel pin pallet design to minimize material handling costs and to improve logistics (Ref. 11). Currently, all TWBs shipped to VW in Wolfsburg must be on a common pin pallet. Typical pin pallets weigh 5,000 pounds tare and 25,000 pounds fully loaded, and cost from $1,000 to $3,500 each. Mercedes Benz is standardizing pin pallets across all their plants to facilitate material handling (Figure 41, below). A disadvantage of steel pin pallets is the return shipment of empty pallets to the TWB facility. The Mercedes pallets shown have removable pallet pins to make them more stackable.

Figure 41 – Standardized steel pin pallets used by Mercedes Benz.

5.8 INVENTORY

ATB voluntarily maintains a one-week supply of finished welded blanks (Ref. 11), as their principal customer, VW, does not specify required inventory buffers. Tailor Steel of Genk maintains a one-week buffer of finished inventory. Having sufficient pin pallets available for inventory storage can be a problem and in this instance, blanks are stored on wooden pallets and transferred to pin pallets prior to shipment. North American auto companies have indicated a preference for two weeks of finished inventory at the supplier. In practice they have achieved inventory levels closer to one week because of steel pin pallet availability from the stamping plants.

52

The un-welded blank inventory at Toyota is approximately two hours. The finished welded blank inventory, prior to forming, is typically about three days (Ref. 10) when supplied by outside vendors. At Georgetown the finished inventory was about 1.5 shifts. Renault also welds many blanks in-house and minimizes inventory to 3 days of welded blanks, which allows them to eliminate weld oiling (Ref. 11). In some cases, large inventories are believed to create problems because of age hardening of the weld. Maintaining a rotating FIFO inventory will help to minimize this possibility (Ref. 10).

5.9 DIMPLING

Companies have had varying degrees of success using dimples to maintain blank separation. Most Japanese companies try not to use them at all by having lower stack heights, using pin pallets to maintain the stack, and using special destacking equipment. Toyota does use dimples on some mash-welded parts that are supplied by an outside vendor (Ref. 10). The use of dimples, particularly on large blanks, can offer minimal benefit because they tend to collapse. The stack weight, banding the pallets, and shipping all contribute to collapsing the dimples. Larger, oblong dimples tend to hold up better than smaller dimples (see Figure 42 below). North American and European companies tend to require dimples on supplied blanks, which add from $0.10 to $0.30 per blank.

Figure 42 – Oblong embossment design that tends to hold up well.

5.4 STACK REQUIREMENTS

General Motors' requirements for blank stacks supplied to GM plants (Ref. 95) are: • Blank to pallet tolerance of +/- 12.5mm; • Stack shift tolerance of 6.0 mm; • Blank stagger tolerance of 6.0 mm; • Stack lean tolerance of 6 mm; • Stack flatness tolerance of 25 mm.

53

VW requires stack flatness to be within 30 mm with a blank-to-blank edge tolerance of 2.5 mm (Ref. 11). ATB believes that these flatness and edge requirements may become a European standard.

5.5 OTHER

Tailor Steel has chosen to implement CMM technology at Tailor Steel in Belgium, and Tailor Steel of America. The purpose of this technology is to inspect incoming edge condition at the Holt plant and to monitor edge condition for process control at the Belgium plant. Both straightness and camber are inspected.

1

6.0 APPENDIX

2

6.1 EQUIPMENT SUPPLIER CONTACTS

Company Name & Address Automated Welding Systems 3900 14th. Avenue Markham, ON Canada L3R 4R2 (800-891-0513) VIL 145 Swift Road Addison, IL 60101 (630-916-7772) Soudronic Ltd. 37408 Hills Tech Dr. Farmington Hills, MI 48331 (248-848-1756) Renault Automation Z.1. du Bois de Iepine – CE 1119 Rue Jules Guesde F 91 031 Evry Cedes France (33 1 46 09 30 16) Nissan: Shuya Kamahori, Manager Nissan Motor Co., Ltd. Technical Center 560-2, Okatskoku, Atsugi City Kanagawa, 243-01 Japan (0462 70 1202) PTR Precision Technologies, Inc. 120 Post Road Enfield, CT 06082-5699 Gunter Schubert (860-741-2281) Toyota: Munetaka Toda, General Manager Toyota Motor Corporation 1, Motomachi, Toyota Aichi, 471 Japan (0565 26 3106) Thyssen Conti: Dr. Manfred Nagel, Executive VP Tailor Welded Blanks 1600 Nadeau Road Monroe, MI 48162 (313 289 6507)

3

6.2 BLANK SUPPLIERS - NORTH AMERICA

Group Address Est. No. Gantries Comments

Tailor Steel (Arbed)

Tailor Steel of America 1777 Holloway Dr.

Holt, MI 48842 (517-694-9070)

3 Shuttle system

10 Formerly Utilase. Manual and automated systems Noble

Industries

Todd Antenucci, VP Sales & Marketing 20101 Hoover

Detroit, MI 48205 (313 245 4810) 5 Manual systems

10 Thyssen Conti systems

Thyssen Worthington

Thyssen Conti: Dr. Manfred Nagel, Executive VP

Tailor Welded Blanks 1600 Nadeau Road Monroe, MI 48162

(313 289 6507)

4 Manual systems

National Steel ProCoil

5260 Haggerty South Canton, MI 48188

4 Soudronic CO2 laser

Automated Welding Systems (AWS)

Automated Welding Systems 3900 14th. Avenue

Markham, ON Canada L3R 4R2

(800-891-0513)

2 AWS Nd:YAG

Toyota Georgetown, Kentucky 3 Toyota turntable systems

Prototech Prototech Laser Welding, Inc.

18321 Mike C. Court Fraser, MI 48026

2 Welding prototypes; curvilinear laser blank welding; adding radius to TWB

weld lines

Dofasco

Powerlasers Ltd. 55 Confederation Parkway.

Concord, Ontario L4K 4Y7

6

Formerly Magna, now Dofasco; Production facilities in Concord,

Ontario & Pioneer, Ohio; R&D facility in Kitchener, Ontario; design and build laser systems for auto and

other applications.

4

Group Address Est. No. Gantries Comments

2

Aluminum, steel and plastic welding with CO2, Yag, and Diode; some

patch and insert welding

U.S. Steel Group

Olympic Laser Processing 6331 Schooner Drive Belleville, MI 48111

4 AWS weld systems

7

Formerly Medina Blanking. Soudronic mash welding

Soudronic CO2 laser systems AWS systems

VIL CO2 system 3 VIL systems

Shiloh Industries

Ohio Welded Blank, Division of Shiloh Industries

5389 West 130th Street Cleveland, OH 44130

1 VIL system

6 Soudronic mash VIL CO2 laser

Nd:YAG MakSteel

Makauto Division of MakSteel

Maksteel Inc. 7615 Torbram Rd.

Mississauga, Ontario L4T 4A8 2 VIL CO2 laser

Nissan Smyrna, Tennessee 2 Nissan system Honda Marysville, Ohio 1 Nd:YAG, precision shear

5

6.3 BLANK SUPPLIERS - EUROPE

Group Est. No. Gantries Name/Location Comments

6 Genk, Belgium Toyota turntable systems Shuttle system

2 Gent, Belgium Soudronic CO2 laser 2 Bremen, Germany Held shuttle systems

Tailor Steel (Arbed)

4 Zaragoza, Spain Soudronic CO2 laser 1 Port Talbot, Great Britain Held 3 Wolverhampton, Great Britain Power Lasers

CORUS

3 Bunschoten, Netherlands Soudronic CO2 laser Soudronic mash

2 Douai, France Renault CO2 laser

~ 2? Sandouville, France Renault Automation – CO2 shuttle system

2 Flin, France Renault CO2 laser 1 Guyancourt, France, Techno Centre Renault 3-D CO2 lab system

Renault

2 Valladolid, Spain Renault Automation CO2

shuttle system Renault circular weld system

6 Fugetechnik Huttenheim, Duisburg, Germany

Conti systems New Nd:YAG for non-linear

1 Fugetechnik Bruckhausen, Duisburg, Germany

Conti system

2 Dortmond, Germany Held shuttle system 4 Wolfsburg, Germany Conti systems

Thyssen Krupp

2 Euroweld, Turin, Italy Shuttle system

2 Cockerill, Liege, Belgium Soudronic CO2 laser Patch spot weld system

1 Eko Stahl, Eisenhuettenstadt,

Germany AWS Ultima Nd:YAG AWS manual system Include a blanking press

3 Solblank, Barcelona Sollac Polymatic systems

Usinor

6 Solblanc, Ukange, France Sollac Polymatic systems

6

Group Est. No. Gantries Name/Location Comments

2

LWB, Ltd., Birmingham, Great Britain Sollac Polymatic Joint venture with Steels & Alloys VIL Nd:YAG system on order

Voest Europlatinen 9 Linz, Austria Soudronic CO2 laser

Salzgitter Europlatinen 3 Salzgitter, Germany Soudronic CO2 laser

Nissan 2 Sunderland, Great Britain Nissan CO2 shuttle system

7

6.4 BLANK SUPPLIERS - SOUTH AMERICA

Group Est. No. Gantries Name/Location Comments

1 Ferrolene, Brazil Soudronic CO2 laser USIMINAS 2 Rio Negro, Brazil Soudronic CO2 laser CSN 1 GalvaSud, Brazil Nothelfer Conti Usinor 1 Gonvarri Renault Automation shuttle

system

8

6.5 BLANK SUPPLIERS - ASIA

Est. No. Gantries Name/Location Comments

Auto Works Laser ~ 1 Daewoo, Korea VIL CO2 laser

Daihatsu Mash ~ 3 Futaba, Japan In-house CO2 shuttle ~ 1 Honda, Japan Unknown ~ 1 Hyundai, Korea Nothelfer Conti

Kanto Motors Laser ~ 6 Nissan, Japan CO2 laser ~ 1 Nissan Shatai Plans Yag welding for Nissan in 2001

Pacific Industries Plasma ~ 1 Toa, Japan Purchased CO2 laser technology from Futaba

~ 12 Toyota, Japan Three families of systems (small jig, turntable, large jig)

Toyota Auto Body Laser and plasma Toyota Iron Works Mash

~ 1 Yajima, Japan ?

9

6.6 BIBLIOGRAPHY

No. AUTHOR COMPANY TITLE Year Publication Pages Abstract 1 Adonyi, Y.;

Chen, C.C. Laser-Welded Steel

Performance in Tailored Blank Applications

1996 Automotive Automation Limited

pp. 157-165

2 Andersen, H.J.; Holm, H.

Aalborg University

Method for Preparation of Laser Welding Control

1997 NIST Special publication 923

pp. 77-88

One of the most important characteristics of the laser welding process is the shape of the heat distribution, which only affects a very deep and narrow area near the weld groove. Hence to achieve a satisfactory weld quality, it is necessary to compensate the process parameters (e.g., welding speed) in order to compensate for even small disturbances in the workpiece geometry (e.g., in the gap size)...

3 Anon Mass Produced Laser Welded Blanks - a UK First

1998 Sheet Metal Industries

pp. 12-13

4 Antenucci, Todd

Noble International, Ltd.

The State of the Industry 1999 29 total

5 Aristotile, R.; Fersini, M.; Bosi, C.; Colombo, E.; Giolfo, M.; Penasa, M.; Rosellini, C.

Centro Sviluppo Materiali; Ansaldo Industria; Ansaldo Energia; RTM SpA; Instituto Italiano della Saldatura

Feasibility Study on the Application of Laser Butt Welding of Tubes to a Pipe Coil Production Line

1998 Welding International

pp. 539-547

This paper describes a feasibility study on the integration of a laser source as an automatic unit for circumferential butt welding of tubes on pipe coil production lines, immediately prior to the cold-bending station…

6 Ashley, Steven

Steel Cars Face a Weighty Decision

1997 Mechanical Engineering

pp. 56-61

The effort of car industries in the United States to improve automotive gas mileage by reducing the weight of steel body structures is reported.

10

No. AUTHOR COMPANY TITLE Year Publication Pages Abstract 7 Auty, T. VIL Laser Welded Tailored

Blanks--A Practical Guide

1998 Sheet Metal Industries

pp. 14, 16, 18, 20

Critical stress regions of automotive components (such as doors) can be reinforced economically by using tailored blanks in which a thicker section is laser welded to a thinner panel to produce a compound blank with resultant quality improvements, cost and weight savings and reduction in piece parts...

8 Bachmann, Friedrich G.

Rofin-Sinar Laser GmbH

High Power Diode Lasers and Their Applications

1999 ALAW Detroit

47 total

9 Bagger, C.; Rasmussen, M.; Olsen, F.

Institute for Product Development

Forming Tests for Laser Welded Blanks

1998 Proceedings 31st ISATA Conference

pp. 29-36

In this paper different means for testing the formability of new material combinations used as tailored blanks in the automotive industry are presented.

10 Baron, Jay; Hammett, Pat; Geddes, Steve; Noel, Jack

University of Michigan; Auto/Steel Partnership

Trip Report 1999 Report 10 total Visit to Japan - June 8-18, 1999

11 Baron, Jay; Noel, Jack

University of Michigan; Auto/Steel Partnership

Tailor Welded Blank Investigation

1999 Presentation 70 total Benchmark Trip to Europe - October 4-15, 1999

12 Belforte, D. A.

Non-Linear Welding System Attracts Customers

1998 Industrial Laser Review

pp. 9-11

The reasons for the purchase of the first Nd:YAG laser-powered tailor blank welder from Automated Welding Systems Inc. and Soudronic mash seam welders by Medina Blanking Corp (Mansfield, OH, USA) for joining dissimilar metals to produce tailor welded blanks for subsequent automotive component fabrication operations are discussed.

13 Blair, S.J.; Tran, T.

British Steel Numerical Simulation of Press Forming Laser-Welded Tailored Blanks

1997 Automotive Automation Limited

pp. 337-344

11

14 Blumel,

Klaus W.; Ufermann, Peter; Graham, John

Numerical Modeling of Tailored Blank Applications for Autobody Components

1999 SAE International Congress and Exposition, Detroit, Michigan

Tailored blank applications have become more and more important for the advanced lightweight and cost-effective steel automobile body. During the last decade, the production of tailored blanks with a straight weldline has been constantly increasing because their technical and economical advantages are well accepted by automobile manufacturers...

15 Blundell, N. Coventry University, UK

Arc Takes Laser Welding Into New Territory

1998 Materials World

pp. 537-538

The use of plasma arc augmented laser welding (PALW) to enhance the performance of industrial lasers while retaining the weld quality for manufacturing applications is described. The advantages of PALW: higher welding speed, faster production time, reduced processing costs and higher weld quality are discussed. Its application to tailor welded blanks, welding A1 alloys and lap welding of Zn coated material is discussed.

16 Buchholz, Kami (Detroit Editor)

USLAB: Proves Lighter is Stronger

1998 Automotive Engineering International

p. 36 The Ultralight Steel Auto Body (ULSAB) structure car has a mass of about 1341 kg, without any secondary mass savings. ULSAB's consortium of 35 sheet steel producers from 18 countries produced 13 identical body structures to demonstrate steel as a lightweight material with torsion and bending strengths beyond 9 of today's midsize sedans.

17 Chen, Kuo-Kuang; Sa, Chung-Yeh

Sheet Metal Stamping for Automotive Applications

1996 Special Publication - SAE

This current publication addresses the following subjects: forming limit diagram, modeling of sheet metal forming, springback and its control, optimum blank design, tailor welded blanks, coated sheet steel, aluminum alloy sheets, tube bending, binder force system, binder design, and tool design...

12

18 Corrias,

Silvio; Faccio, Francesco; Gallinaro, Gaetano; Savio, Pierino

Fiat Laser-Welded Tailored Blanks for Trucks: A Technical and Economical Feasibility Analysis

1997 International Body Engineering Conference and Exposition

In this paper, we present the results of a technical and economical feasibility evaluation of a laser-welded tailored blank application in an IVECO truck cab. The different aspects related to the economic comparison between a traditional and a tailored blank solution are analyzed.

19 Das, Sujit Oak Ridge National Laboratory

The Economic Viability of Aluminum Joining Technologies

2000 Report prepared for USDOE

9 total

20 Diehm, Oliver

TWB Company

Worldwide Applications of Laser Welded Blanks

1996 Automotive Laser Applications Workshop

In the early 1980's, the first laser welded blank application was introduced through Thyssen Stahl AG; an oversize panel was manufactured for the Audi 100. Two years after the introduction of several similar gauge Tailor Welded Blanks, applications included the use of different steel grades, thicknesses and coatings...

21 Dodd, A. Lumonics Laser-Welded Blanks Gain Ground

1998 Manufacturing Engineering

pp. 76-82

Tailor welded blanks promise significant cost savings for automakers by streamlining the fabrication of automotive vehicle bodies. Manufacturers currently employ four types of joining processes to weld coated-steel tailored blanks: mash seam welding, electron beam welding, and laser welding...

22 Dodd, A.; Stafford, D.

Lumonics; Honda of American Manufacturing, Inc. USA

Tailored Blank Welding Systems for Auto Manufacturing

1997 Fabricator pp. 70-73

The use of tailored blank welding, a process for joining different types and/or thicknesses of steel together for later stamping of one finished part. The factors considered by Honda of America Manufacturing Inc. in selecting a Nd:YAG laser blank welding system with fiber-optic delivery for the production of door inners are examined, and process procedures used in blank welding of 0.7 and 1.4 mm thickness steel sheet are described.

13

23 Ferguson, Norm

Automated Welding Systems, Inc.

Another Viewpoint; Automated Blank Welding Systems - Using Nd:YAG Lasers

1997 Automotive Laser Applications Workshop 1997

6 total

24 Gatenby, Kevin M.; Court, Stephen A.; Altshuller, Bernie

Alcan International Ltd.

Aluminum-Magnesium Alloys for Automotive Applications--Design Considerations and Materials Selection

1997 International Body Engineering Conference and Exposition

The aluminum magnesium or 5XXX alloys in sheet form have been considered for some time to be the most appropriate choice for vehicle structures as they offer attractive combinations of formability, strength, weldability and corrosion resistance…

25 Gerhard Tecklenburg

Haus Der Technik E.V.

Automotive Door Systems: Vision for Future Development

1999 Presentation 51 total

26 Glagola, M.A.; Pickering, E.R.

Reynolds Metals

Applications of Aluminum GTA Welded Tailored Blanks: Case Studies Comparing Processes and Materials

1996 29th International Symposium on Automotive Technology & Automation

pp. 781-789

The application of tailor welded blanks to automobiles has grown substantially in the last ten years. In an effort to reduce weight and save cost, steel tailored blanks are increasingly used to reduce part count, weight, offal and assembly costs…

27 Gu, Hongping; Duley, W.W.

University of Waterloo

A Statistical Approach to Acoustic Monitoring of Laser Welding

1996 Journal of Physics

pp. 556-560

Acoustic emission at frequencies between 20 Hz and 20 kHz during CO/2 laser welding of steel contains important diagnostic information related to weld morphology, depth of penetration and heat-affected zone…

28 Haran, F.M.; Hand, D.P.; Peters, C.; Jones, J.D.C.

Heriot-Watt University

Process-Control in Laser Welding Utilizing Optical Signal Oscillations

1996 Laser Institute of America

Described is an optical sensor for process monitoring of Nd:YAG laser welding (of mild steel). This sensor detects the broadband radiation produced by the welding process, dividing it into broad spectral bands (designated as UV/visible and IR). Fourier analysis is used to investigate an oscillatory intensity modulation of the optical signals...

14

29 Heidbuchel

, Peter; Wonneberger, Ingo; Mertens, Axel; Alber, Gerhard

Thyssen Stahl AG

Process for Marrying Two Parts Prior to Laser-Beam Welding of Circular and Non Circular "Tailored Blanks"

1997 International Body Engineering Conference and Exposition

There will be a significant increase in the application of "tailored blanks" in order to put existing lightweight automobile concepts into practice. Tailored blanks consist of several individual sheets combined in different thicknesses or steel grades welded by means of laser-beam energy...

30 Hong, J.P.; Oh, S.-I.; Kim, H.-Y.

Formability Study on Weld Line Location and Movement of Laser-Tailored Welded Blanks

1997 Proceedings of the International Pacific Conference on Automotive Engineering

pp. 295-300

31 Hornig, J. BMW Laser Applications and Strategies at BMW

1999 ALAW Detroit

3 total

32 Hsu, Rey; Heinemann, Stefan

Fraunhofer Resource Center

New System Concepts for Steel and Aluminum Tailored Blank Welding

1998 Society of Automotive Engineers

pp. 269-273

The demand for the use of tailor welded blanks in the automotive industry continues to grow. The competition in this business is also growing. In order to be competitive, a cost effective and reliable welding system is critical.

33 Irving, B. Laser Beam Welding Shifts Into High Gear

1997 Welding Journal

pp. 35-40

Despite its high initial cost, laser beam welding is being recognized as the best method for many production lines. The automotive industry is becoming a bigger believer, with more lines being added every day for weld transmissions, mufflers and many other products...

34 Irving, Bob Welding Journal, contributing editor

Interest in Welded Aluminum Automobiles Gathers Momentum Worldwide

1998 Welding Journal

pp. 31-35

Automobile companies worldwide are taking a serious look at producing all-aluminum vehicles…

15

35 Ishihara,

Loichi; Kubota, Koji

Sanyo Machine Works, Ltd.

Tailored Blank Welding of Vibration Damping Steel

1997 International Body Engineering Conference and Exposition

Tailored blank welding is coming to a turning point. It is not easy to find a profitable application in this technique matching the expensive investment cost except the common adoption like door inner or engine compartment rail…

36 Jansen, Steven

Utilase Blank Welding Technologies

Tailored Blanks: A Key Technology for Light Weight Steel Autobody Structures

1997 Automotive Laser Applications Workshop 1997

56 total

37 Jansen, Steven

Utilase Blank Welding Technologies

Formability of Laser Welded Blanks

1996 Automotive Laser Applications Workshop 1996

37 total

38 Jansen, Steven W.; Liu, Yi; Camplin, Ken; Geier, Dan

Noble Metal Processing, inc.

Automated Inspection of Laser Welded Blanks

1999 Automated Inspection of Laser Welded Blanks

Laser welded sheet metal blanks have been inspected for weld integrity using many different approaches. To date, visual inspection by human operators has been the most reliable method to detect weld defects. However, the ever increasing application of laser welded blanks in automotive body components has lead to larger blank sizes and volumes, resulting in the automation of the laser blank welding process...

39 Jones, Tim Tailor Blank - European Scene

1997 Memo 3 total European steel makers with existing or imminent capability in tailored blanks are Thyssen, Tailor Steel (Sidmar/Arbed Group), Krupp-Hoesch, Voest-Alpine, Sollac, Hoogovens (ATB), and Cockerill-Sambre. Equipment suppliers looking to supply/partner with European steel interests include Powerlaser/Triam, VIL, and Utilaser.

16

40 Kamahori,

Shuya Nissan Motor Co., Ltd.

Nissan's Challenge in Building the Most Lean System for Tailor Welded Blanks Production

2000 Automotive Laser Applications Workshop 2000

21 total

41 Khaleel, Moe; Davies, Rich

Pacific Northwest National Laboratory

Weldability, Formability and Structural Performance of Thin Gage High Strength Tailor Welded Blanks

2000 Presentation 46 total

42 Kim, H.Y.; Shin, Y.S.; Kim, K.H.; Cho, W.S.

Kangwon National University, South Korea

Stamping Analyses and Die Design of Laser Welded Automotive Body

1998 Metals and Materials

pp. 871-877

Computer simulations and test trials are carried out to get the optimal conditions of the design for the stamping of the laser tailor welded automotive body panels. Through test trials with new manufactured die for tailor welded blanks (TWB), the effects of the initial position of blank, blank holding force, drawbead shape, and corner radius are investigated...

43 Kinsey, Brad; Liu, Zhihong; Cao, Jian

Northwestern University

New Apparatus and Method for Forming Tailor-Welded Blanks

1999 SAE International Congress and Exposition, Detroit, Michigan

pp. 31-37

Tailored-welded blanks offer a unique opportunity to reduce manufacturing costs, decrease vehicle weight, and improve the quality of stampings through the consolidation of multiple-formed, then welded, parts into a single stamping…

44 Kluft, Werner; Boerger, Peter; Schwartz, Reinhold; Cremer, Volker

Prometec GmbH

on-line Process Monitoring of the Laser Welding of Sheet Metal Via Analysis

1997 International Body Engineering Conference and Exposition

As visual monitoring of the seam roots of pipes and other closed sections during laser welding is difficult and usually impossible, a method of controlling seam root formation via on-line monitoring of the plasma radiation above the workpiece from the machining side has been developed...

45 Kochan, Anna

Automotive News Europe

Tailored Blank Technology Expands

1997 Automotive News Europe

1 total

17

46 Kristensen,

Jens Klaestrup; Borggreen, Kjeld

Evaluation of Laser Welds in Structural Steels

1996 International Journal for the Joining of Materials

pp. 48-54

For the welding of structural steels high power laser welding offers many advantages in comparison with traditional processes. The advantages include high productivity, limited distortion and low filler metal consumption…

47 Kubel, Ed Manufacturers Want More Tailored Blanks

1997 Manufacturing Engineering

pp. 38-42, 44-45

Tailor welded blanks (TWBs) present an important step by which manufacturers can optimize weight reduction, dimensional control, nesting accuracy, scrap management, and manufacturability at a reasonable cost. Current applications of TWBs include body side frames, door inner panels, motor compartment rails, center pillar inner panels, and wheelhouse shock-tower panels.

48 Kubota, K. Isuzu Motors, Ltd.

Laser Welding Technology of Vibration Damping Steel Sheet for Tailored Blanking Method

1997 JSAE Review

pp. 415-157

Vibration damping sheet is made by laminating a plastic sheet in between steel sheets. Because of this structure, laser welding quality is considered difficult to assure in actual use…

49 Kuepper, Frank W.

Stiefelmayer, Inc.

New Concepts in Laser Blank Welding Manufacturing Systems

1998 6th Annual Automotive Laser Applications Workshop 1998 (ALAW '98) Proceedings

8 total

50 Kukui, K.; Uchihara, M.; Takahashi, M.; Kurita, M.

Formability Fatigue Performance and Corrosion Resistance of Tailor Welded Blanks

1996 IBEC Conference - Materials and Body Testing

pp. 100-105

18

51 Kusaka,

Shuichi; Shinbo, Yukio; Sekine, Yukio; Kojima, Shinji; Ohwaki, Joji

Quality of High Power Laser Welded Line Pipe

1998 Proceedings of the International Conference on Offshore Mechanics

14 pp Carbon steel and various stainless steels were Laser welded in production line and the weld mechanical and chemical properties were evaluated to confirm the quality of Laser welding…

52 Langerak, Nico A.J.

Hoogovens The Use of Steel and Aluminum in the Next Generation Auto Bodies

1997 Automotive Body Materials (IBEC '97)

pp. 3-10

In today's sheet metal industry, it is current practice for the metal supplier to become closely involved with the design and production of sheet metal parts. During the design and production stage, technical support is supplied relating to material selection design of parts, tooling and processing parameters...

53 Lankalapalli, Kishire

Model-Based Laser Weld Penetration Depth Estimation

1997 Welding in the World

pp. 304-313

Penetration depth is an important factor critical to the quality of a laser weld. In this paper, a model-based technique for penetration depth estimation by measuring the workpiece temperatures using infrared sensors is proposed…

54 Lankalapalli, Kishire N.; Tu, Jay F.; Gartner, Mark

Purdue University; Ford Motor Company

A Model for Estimating Penetration Depth of Laser Welding Processes

1996 Journal of Physics

pp. 1831-1841

Penetration depth is one of the most important factors critical to the quality of a laser weld. However, no on-line, non-destructive method exists by which to inspect this quantity. Indirect, model-based estimation schemes are feasible for monitoring laser welding processes...

55 Lee, Andy P.; Feltham, Erick; Van Deventer, Jon

Dofasco Inc. Tailor Welded Blank Technology for Automotive Applications

1996 SAE International Congress and Exposition, Detroit, Michigan

pp. 91-102

Tailor welded blanks (TWB) afford better utilization of sheet steel automotive and other applications. However, forming behavior can be complicated because of the interactions between the different sheet steels comprising the TWB and the welding processes used...

19

56 Lee, C.H.; Huh, H; Han, S.S.; Kwon, O.

Korea Advanced Institute of Science and Technology; Pohang Iron & Steel

Optimum Design of Tailor Welded Blanks in Sheet Metal Forming Processes by Inverse Finite Element Analysis

1998 Metals and Materials

pp. 458-463

Design of weld line in tailor welded blanks is indispensable for good manufacturing of stamped parts as assigned, since the initial weld line is distorted severely during the forming process. The initial weld line has to be determined such that desired weld line in a formed part can be obtained...

57 Leong, Keng H.

Argonne National Laboratory, Laser Applications Laboratory, Technology Development Division

Low Cost Laser Weld Monitoring System

1997 Automotive Laser Applications Workshop 1997

18 total

58 Li, L.; Brookfield, D.J.; Steen, W.M.

Plasma Charge Sensor for In-process, Non-contact Monitoring of the Laser Welding Process

1996 Measurement Science & Technology

pp. 615-626

Laser keyhole welding is an important modern manufacturing technology. During such welding a plasma cloud is generated and the behavior of this plasma is closely coupled to the behavior of the weld…

59 Liu, Yi Utilase Blank Welding Technologies

The Integration of Laser Blank Welding and QS-9000

1996 Automotive Laser Applications Workshop 1996

5 total

60 Loeffler, Klaus

Trumpf Laser Technology Center

Global Laser Innovations with Nd:YAG Lasers and Their Applications on Components in the Automotive Industry

1999 Automotive Laser Application Workshop

14 total

61 Marron, G.; Verrier, P.

Sollac A New Concept for Lighter Steel Wheels

1999 SAE International Congress and Exposition, Detroit, Michigan

Usually, wheels' dimensions are based on fatigue or impact loading and thus lead to one steel grade and one thickness. The use of tailored laser blanks permits wheel weight to be reduced considerably. Rims can be divided into different areas subject to different in-service stresses...

20

62 Martin,

John Automated Welding

Systems Incorporated 2000 Report 19 total

63 Mettke, Christoph; Ng, Eng S.; Watson, Ian A.

Monitoring Nd:YAG and CO/2 Laser Weld Quality

1998 Conference on Lasers and Electro-Optics Europe - Technical Digest

pp. 202 An image system was developed that offered real time capability to determine weld quality via measurement of the weld width, surface roughness and heat affected zone. The system comprised an inexpensive CCD camera, acquisition and processing boards…

64 Mohrbacher, Hardy; Rubben, Kris; De Rycke, Igor; leirman, Etienne

OCAS N.V. Design and Manufacturing Issues of Nonlinear Welded Tailored Blanks

1997 International Body Engineering Conference and Exposition

The tailored blank is a strategic steel flat product designed to reduce the weight of vehicles and to optimize the structural properties and the assembly by part integration. In both respects, the ULSAB study, a joint effort of the world steel industry and Porsche Engineering Services, has indicated the significant potential offered by tailored blanks...

65 Mombo-Caristan, J.C.

TC Arts and Laserfactures

High-Speed-High-Power Laser Lap Welding for Tailored Blanks

1996 Automotive Laser Applications Workshop 1996

15 total

66 Mombo-Caristan, Jean-Charles

TC Arts and Laserfactures

Improved Laser Lap Welding of Galvanized Steel

1997 International Body Engineering Conference and Exposition

An improvement of the laser lap welding of galvanized sheet steel is investigated experimentally. The method proposed consists of overlapping two sheet metals of possibly different thicknesses or metallurgies, and of controlling the width of overlap…

67 Mori, K.; Sakamoto, H.; Miyamato, I.

Nissan Motors

Detection of Weld Defects in Tailored Blanks: Development of an In-Process Monitoring System for Laser Welding

1997 Welding International

pp. 628-632

This paper describes an in-process system developed to monitor the quality of CO2 laser welding. It incorporates two photo sensors aligned at different angles to detect the long-term power stability and underfill and pitting defects and has been used on a production line for tailored blank welding of automotive parts since 1993...

21

68 Mori, Kiyokazu; Miyamoto, Isamu

Inprocess Monitoring of Laser Welding by the Analysis of Ripples in the Plasma Emission

1997 Journal of Laser Applications

pp. 155-159

A novel in-process monitoring system employing two detectors set above the workpiece at different aiming angles of 5 degree and 75 degree has been developed to detect whether or not CO/2 laser welding fully penetrates through to the back surface of steel sheets...

69 Mueller, Matthias.; Dausinger, Friedrich; Griebsch, Juergen

University of Stuttgart; Jurca Optoelektronik

On-Line Process Monitoring and Control of Laser Welding

1997 International Body Engineering Conference and Exposition

The common use of laser beam welding in industrial applications allows on-line, non-descriptive quality assurance based on reliable indicators. A new method uses the relationship between the geometry of the keyhole and emitted laser light to control welding depth and to monitor inner seam defects...

70 Naeem, Mohammed

Lumonics Ltd.

Tailored Blank Welding With a 4-kW CW Nd:YAG Laser

1997 International Body Engineering Conference and Exposition

Tailored blanks have made a great impact on pressed sheet components in the automotive industry. Larger pressings can be made than with standard-sized sheets and dissimilar steel types or thicknesses can be joined. Resulting benefits are improved material use, potential weight saving and a reduction in subsequent assembly operations...

71 Nagel, Manfred

Tailor Welded Blanks

New Developments in Laser Tailor Blanking

2000 Automotive Laser Applications Workshop 2000

40 total

72 Nagel, Manfred; Fischer, Rainer; Lowen, Joachim; Straube, Oliver

Thyssen Lasertechnik

Production and Application of Aluminum Tailored Blanks

1997 International Body Engineering Conference and Exposition

The demand for weight reduction and increasing requirements of passive safety of automobiles forces the use of lightweight vehicle components and new manufacturing processes. Besides the weight reduction there is also a priority to meet the cost targets...

22

73 Nava-

Rudiger, E.; Houlot, M.

Integration of Real Time Quality Control Systems in a Welding Process

1997 Journal of Laser Applications

pp. 95-102

The automation of laser welding processes requires the control of the various process components as well as the control of the laser-material interaction. These systems are essential for ensuring the quality of the weld seam as they are able to react to dynamic fluctuations during the process...

74 Neiheisel, G.L.

Armco Inc. USA

Operating, Maintenance, and Productivity Data from a Full Production Laser Blank Welding System

1996 SAE Paper 962351

The paper describes a full production laser tailored-blank welding system and provides some operating, maintenance and productivity data.

75 Ninforge, D.; Dawance, J.

Research and Development Cockerill Sambre; Cockerill Sambre Tailored Banks

Improvement of Tailored Blank Stamping by Using a Control and Localization of the Blank-Holder

1998 Proceedings 20th IDDRG

pp. 511-519

Tailored welded blanks are increasingly being used in the motor vehicle sector, the purpose of these blanks being to reduce weight and production costs by means of a reduction in the number of parts to be assembled…

76 Oh, S.I.; Lee, J.K; Kang, J.J.; Hong, J.P.

Seoul National University; Kia Motors

Applications of Simulation Techniques to Metal Forming Processes

1998 Metals and Materials

pp. 583-592

Sheet metal forming is one of the most widely used processes in manufacturing. Traditional die design practice based on trial and error method is time consuming and expensive. For this reason, the simulation technique based on finite element method (FEM) becomes more popular to develop and optimize die design...

77 Pohl, T.; Schultz, M.

University Erlangen-Nuremberg

Laser Beam Welding of Aluminum Alloys for Light Weight Structures Using Co2 and Nd:YAG-Laser Systems

1997 Proceedings Laser Assisted Net Shape Engineering 2

pp. 181-192

In mass production of car bodies laser beam welding offers different advantages as for example high feed rate, high weld quality and minimized heat affected zone. It is applied to different production purposes as e.g. for the welding of tailored blanks, which are an important element of net shape engineering nowadays...

23

78 Ponschab, Hellfried; Hinterhoelzl, Kurt; Muellner, Arthur; Radlmayr, Karl; Szinyur, Johann; Corrodi, Rudolf; Sommer, Dieter

Voest-Alpine Stahl; Soudronic

Advantages and First Experiences with a New Technology for the Production of Laser- Welded Blanks

1997 International Body Engineering Conference and Exposition

Welded blanks for the body-in-white of automobile are increasingly gaining importance. The successful use of tailored blanks instead of single pressed parts…

79 Posseln, T.; Glasbrenner, B.; Werkzeugtechnische, MaBnahmen beim Ziehen von

Tailored Blanks 1998 Proc. Neuere Entwicklungen in der Blechumformung, Fellbach

pp. 503-521

80 Rapp, J.; Dausinger, H. Hugel

University of Stuttgart

Laser Beam Welding of Aluminum Alloys for Light Weight Structures Using CO2 and Nd:YAG-Laser Systems

1996 Proceedings ECLAT (European Conference on Laser Treatment of Materials)

pp. 97-106

Laser beam welding of aluminum alloys is rendered difficult by their specific material properties. On the basis of a fundamental understanding of the relevant technological and metallurgical mechanisms, guidelines for a successful adaptation of the welding process are offered...

81 Ream, Stanley L.

Worthington Industries/TWB

Tailored Blank Welding in North America, 1999 Industry Review

1999 Presented at 7th Annual Automotive Laser Applications Workshop '99

26 total

24

82 Ream,

Stanley L. TWB/Worthington Industries

Comparative Analysis YAG vs. CO2 Lasers for Tailor Blank Welding

1997 Automotive Laser Applications Workshop 1997

31 total

83 Ream, Stanley L.

TWB/Worthington Industries

Weld Quality Monitoring for Tailor Welded Blanks

1996 Automotive Laser Applications Workshop 1996

14 total

84 Robertson, Scott

USS, Olympic in Joint Study

1996 American Metal Market

p. 4 In joint study. (U.S. Steel Group, Olympic Steel Inc. considering joint venture to produce laser- welded blanks of a joint venture is being discussed because of the growth of the market for laser -welded blanks. "The blanks offer the opportunity to bring all the advantages of steel to an automotive...

85 Sakurai, Hiroshi; Sugiyama, Takashi; Takahashi, Susumu; Shibata, Kimihiro

Nissan Motor Co. Ltd.

Stretch Formability of Laser- Welded Blanks

1997 International Body Engineering Conference and Exposition

In order to investigate the stretch formability of laser- welded blanks, the hemispherical punch stretching test was performed and the analysis was carried out using finite…

86 Saran, M.J. (Ed.); Meuleman, D.J. (Ed.)

Proceedings of the 1998 SAE International Congress & Exposition

1998 Developments in Sheet Metal Stamping; SAE Special Publications

The proceedings contain 19 papers. Topics discussed include stamping surface quality, metal forming, process optimization, computer simulation, cost modeling, tubular hydroforming and economic evaluation of the hydroforming technology.

87 Saunders, F.I.; Wagoner, R.H.

General Motors Corp.; Ohio State University

Forming of Tailor-Welded Blanks

1996 Metallurgical and Materials Transactions A

pp. 2605-2616

The issues governing the failure modes and the formability of tailor-welded blanks used in the automotive industry were studied. Blanks with two combinations of parent material were considered.

25

88 Scriven, P.J.; Brandon, J.A.; Williams, N.T.

University of Wales (Swansea)

Relative Influence of Sheet Rolling Direction and Weld Orientation on Formability of Laser Welded Steel Sheet

1997 Ironmaking and Steelmaking

pp. 79-83

89 Scriven, P.J.; Brandon, J.A.; Williams, N.T.

University of Wales (Swansea)

Influence of Weld Orientation on Forming Limit Diagram of Similar/Dissimilar Thickness Laser Welded Joints

1996 Ironmaking and Steelmaking

pp. 177-182

90 Shi, Ming F.

National Steel Corporation, Product Application Center

Formability Comparison Between laser and Electron Beam Welded Blanks

1998 6th Annual Automotive Laser Applications Workshop 1998 (ALAW '98) Proceedings

21 total

91 Shimbo, Y.; Ono, M.; Shiozaki, T.; Ohmura, M.; Sekine, Y.; Nagahama, H.; Kohno, K.

Development of High Power Laser Pipe Welding Process

1997 SEAISI Quarterly

pp. 31-37

NKK has installed the world's first 25k W laser welding machines at its 24-inch pipe mill at the Keihin Works. High-power laser pipe welding process with maintaining high productivity while assuring uniform welds with the base metal has been started to develop...

92 Shulkin, L.B.

Design for Temporal and Spatial Variation of Blank Holder Pressure in Sheet Metal Forming

1997 Ph.D. Thesis, Ohio State University

A design was developed for a hydraulic/nitrogen blank holder pressure (BHP) control system for sheet metal forming (e.g. of tailor-welded and non-welded sheet metal parts made from steel and aluminum). A systematic approach was used to design elastic blank holders and multi-point blank holder control systems...

26

93 Simpson, T.C.; Hoffman, J.D.; Soreide, L.; Meyer, D.H.

Bethlehem Steel; Ford Motor Company

Corrosion Performance of Tailor Welded Blanks

1998 Corrosion 98 pp. 745 The purpose of this study was to evaluate the corrosion performance of tailor welded blanks as a function of the type of weld. Cosmetic and perforation corrosion resistance of coated sheet products containing mash-seam and laser welds were evaluated using the GM954OP-Method B and SAE J2334 laboratory corrosion tests...

94 Stegemann, Thomas; Wonneberger, Ingo; Mertens, Axel

Thyssen Stahl AG

Tailored Blanks with Nonlinear Weld Seams--Properties and Production

1997 International Body Engineering Conference and Exposition

Tailored blanks with straight weld seams are now an accepted part of technical practice. In recent years, the welding facility technology developed by Thyssen Stahl AG and Nothelfer GmbH has constantly been advancing, so that this year alone four new welding plants could start operating in Duisburg. The introduction of this plant technology ensures economic, qualitatively high-grade series production of tailored blanks with straight weld seams...

95 Stevens, Mark W.

General Motors, Metal Fabricating Division

Automotive Laser Applications

2000 Presentation 39 total

96 Stiles, John

General Motors Corporation, Metallic Worldwide Purchasing

Laser Blank Welding, General Motors Global Perspective

1998 6th Annual Automotive Laser Applications Workshop 1998 (ALAW '98) Proceedings

7 total

97 Trogolo, J. Michael; Diffenbach, Jeff R.

IBIS Associates, Inc.

Evaluation of Tailor Welded Blanks Through Technical Cost Modeling

1998 Developments in Sheet Metal Stamping SAE Special Publications

27

98 Uchihara, M.; Takahashi, J.; Kurita, M.; Hirose, Y.; Fukui, K.

Sumitomo Metal Industries, Ltd.

Performance of Mesh Seam Welds in Tailor Welded Blanks

1997 SAE Meeting Science Lecture No. 974

pp. 245-248

Formability, fatigue properties and corrosion behavior of mash seam welded steel sheets were investigated and the results were compared with laser weld. The stretch formability of mash seam weld and laser weld panels were the same level. Mash seam weld however, showed slightly smaller formability in hole expansion test...

99 van den Berg, A.C.; Meinders, T.; Stokman, B.

Hoogovens Research and Development; University of Twente; Automotive Tailored Blanks

Deep Drawing Simulation of Tailored Blanks

1998 Proceedings 20th IDDRG

pp. 133-144

Tailored blanks are increasingly used in the automotive industry. A tailored blank consists of different metal parts, which are joined by a welding process. These metal parts usually have different material properties. Hence, the main advantage of using a tailored blank is to provide the right material properties at specific parts of the blank...

100 Van der Hoeven, J.-M; Rubben, K.; Lambert, F.; De Rycke, I.

OCAS Tailored Blanks: A Key Technology for Light Weight Steel Auto Body Structures

1996 Automotive Automation Limited

pp. 177-185

Steel is the material of choice for lightweight Body-in-White concepts. To meet new ecological requirements, the global steel industry designed a new BIW concept, called the ULSAB (Ultra Light Steel Auto Body Structure), and set new targets in weight, safety and structural performance...

101 Venkat, S.; Albright, C.E.; Ramasamy, S.; Hurley, J.P.

Ohio State University

CO/2 Laser Beam Welding of Aluminum 5754-0 and 6111-T4 Alloys

1997 Welding Journal

pp. 275.s-282.s

Legislative and market pressures have caused the automotive industry to consider more fuel efficient designs of vehicles in recent years.

102 Waddell, W.; Jackson, S.; Wallach, E.R.

British Steel Strip Products; University of Cambridge; University of Cambridge

The Influence of the Weld Structure on the Formability of Laser Welded Tailored Blanks

1998 Society of Automotive Engineers

pp. 257-268

Tailor Welded Blanks (TWBs) can offer significant benefits in terms of weight reduction, cost and performance. This paper considers the influence of the laser weld on the formability of TWBs in a range of steels with yield strengths from 15 MPa to 585 MPa...

28

103 Wadman,

Boel Institute of Production Engineering Research

Research Programs on Tailor Blank Formability

1999 8 total

104 Walters, C.T.; Ream, S.L.

Laser Weld Process Monitoring in Production of Tailor-Welded Blanks

1996 Laser Institute of America Proceedings-LIA

pp. 1-10

105 Watanabe, J; Nakabayasi, T; Hiraga, H.; Inoue, T.; Matsunawa, A.

Mitsubishi Heavy Industries

Appearance of Measured Signals with Changes in Basic Welding Conditions: Features of Monitoring Methods for Laser Welding and Their Application

1998 Welding International

pp. 21-28

This paper describes the appearance of the measured signals in response to changes in the basic welding conditions. The main results obtained are as follows: the average amplitude (V sub amp) of both the spectrum emission intensity and plasma potential is far better correlated with the penetration depth than the average output (Vsub ave)...

106 Watanabe, J; Nakabayasi, T; Hiraga, H.; Inoue, T.; Matsunawa, A.

Mitsubishi Heavy Industries

Correlation Between Process Parameters and Measured Signals During Laser Welding of Plates with Artificial Defects: Features of Monitoring Methods for Laser Welding and Their Application

1998 Welding International

pp. 29-38

The authors are engaged in a research program intended to clarify the behavior of laser-induced plasma during laser welding and to establish its applicability in monitoring laser welding parameters…

107 Watanabe, J; Nakabayasi, T; Hiraga, H.; Inoue, T.; Matsunawa, A.

Mitsubishi Heavy Industries

Effect of Shielding Gas Plasma on Monitoring Signals in Laser Welding: Features of Monitoring Methods for Laser Welding and Their Application

1998 Welding International

pp. 9-20

The shielding gas used in laser welding plays an important role in obtaining high-quality welds. Argon shielding gas, being cheap to use, has most notably entered widespread use, but it faces the growing problem of plasma generation in higher-power laser welding...

29

108 Wild, Peter Department

of Mechanical Engineering, Queen's University, McLaughlin Hall

Project on Tailor Welded Blanks

1999 CAMM (Centre for Automotive Materials and Manufacturing) Wed Page

The first sponsored CAMM research project is on "The Measurement of Weld Properties in Tailor Welded Blanks for Finite Element Modeling and Process Control"…

109 Wirth, Juerg

Soudronic New Laser Technologies for Laser Welded Tubes and Tailor Welded Blanks

2000 Automotive Laser Applications Workshop 2000

12 total

110 Wouters, P.; Monfort, G.; Defourny, J.

User Properties Department, CRM

For an Optimized Combination of Steels and Welding Processes Before Forming

1998 Proceedings 20th IDDRG

pp. 89-102

The most usual and practical technique of assembly is welding. The metallurgical and mechanical properties of the joint directly depend upon the thermal cycle imposed during welding. The weld has to comply with the same requirements as the parent materials namely formability and strength properties...

111 Xie, Jian Edison Welding Institute

Laser Lap Welding of Galvanized Steel with No Gap

1999 7th Annual Automotive Laser Applications Workshop

9 total

112 Yamasaki, Y.; Yoshida, M.; Kabasawa, M.; Ono, M.

NKK Effect of Chemical Composition, Mechanical Properties and Thickness of Base Steels on Formability of Laser-Welded Blanks

1996 University of Miskolc

pp. 357-366

30

113 Thyssen

Krupp Stahl; Thyssen Fugetechnik

Comparative Considerations for Design of Tailored Blanks and Thyssen Engineered Blank

1998 Technische Mitteilungen

pp. 29-35

As distinguished from conventional tailor welded blanks which are made with linear weld lines that extend to the boundaries of the blanks, Thyssen engineered blanks have weld lines that can be curvilinear and can provide thicker sheet sections in patches. The production line for producing engineered blanks by laser welding is described...

114 Hydroformed Structural Elements: Economic Evaluation of the Technology

1998 Automotive Engineering International

pp. 103-105

Analyses indicate the influence of the number of parts replaced and several other parameters in deciding whether stamping or hydroforming best suits a particular process.

115 Project Will Develop Automated Laser Welding System for Tailor Blank Production

1998 Welding Journal

p. 22 Modular Vision Systems, Inc. (Vienna, VA, USA) will sell LaserVision joint tracking systems to Automated Welding Systems (Markham, Canada) for incorporation into their laser automated tracking systems for cutting and welding. The companies will develop a fully automated laser welding system for producing tailor welded blanks for the car industry.

116 DCT Sells Blanks Business to Noble

1997 American Metal Market

…as a division of DCT since it was founded in 1990, sells most of its laser -welded blanks to General Motors Corp., Chrysler Corp., Volkswagen de Mexico S.A. and other automakers for…

117 Deep Drawing Tailor-Welded Blanks

1997 Stamping Journal

pp. 26-32

Laser-welded blanks of AKDQ steel 279.4 mm in diameter were deep drawn in a 160-ton press to 152.4-mm-diameter cups using a raw ratio of 1.83 with a view to developing new design guidelines for the deep drawing of tailor-welded blanks. Computer simulations were also performed...

31

118 Honda & Rover: To

Have Laser-Welded Body Panels

1997 Automotive News Europe

p. 13 Honda and Rover models will have laser-welded body panels in 1998, called tailor blanks. They are supplied by a joint venture of French steelmaker Sollac and UK-based Steel and Alloy Processing. Tailored blank technology reduces weight and costs…

119 Lasers Heating Up Blank Market

1997 American Metal Market

p. 12A One example is tailor -welded blanks, and within that category, laser-welded blanks. A manufacturing process that began in Germany in the early 1980s is now taking off…

120 MVSI Subsidiary Wins Contract for Laser Vision Systems for Use in Automated Welding Systems for the Automotive Industry

1997 PR Newswire p. 1009 …a fully automated laser welding system using MVS' laser vision technology for the production of tailor welded blanks for the automotive industry worldwide. Tailor welded blanks is an emerging technology used in the manufacturing of car door inner panels, body door...

121 Olympic Steel, Inc. and the US Steel Group of USX Corporation Form Laser Welding Joint Venture

1997 PR Newswire p. 120 …plants in that region. It is expected to employ approximately 25 persons at full production. Laser welded blanks are used in the automotive industry for an increasing number of body fabrication applications. Demand...

122 Usinor Seeks Share of UK Autobody Market

1997 Metal Bulletin …flat products subsidiary, Sollac and Steel & Alloy (UK), steel processor, are planning to build a laser welded blanks plant in the UK with a 20k t/y welding line. The move is an…

123 Shiloh Industries Announces Capital Improvements to Provide for Growth Opportunities

1996 PR Newswire p. 125 …and aluminum coils into conventional and welded blanks for the automotive industry, is upgrading its tailor welded blanking capabilities. The trends toward consolidation and outsourcing in the automotive components industry are presenting Shiloh…

32

124 Welding -- Electron and

Laser-Beam Welded Joints -- Guidance on Quality Levels for Imperfections; Part 1: Steel

1996 ISO International Standard 13919-1

This standard gives guidance on levels of imperfections in electron and laser beam welded joints in steel. Three levels are given in such a way as to permit application for a wide range of welded fabrications. The levels refer to production quality and not to the fitness-for-purpose of the product manufactured...