kassel - hot stamping

7/27/2019 Kassel - Hot Stamping

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CPF

Center for Precision Forming (CPF)

Progress on the Finite Element

Simulation of the Hot Stamping Process

Ambi Naganathan,

Dr. Partchapol Sartkulvanich,

Deepak Ravindran,

Norbert Pierschel,

Dr. Taylan Altan

June 13-16, 2011 Kassel, Germany

3rd International Conference on Hot Sheet Metal Forming of

High-Performance Steel


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Center for Precision Forming (CPF)2

Outline

Introduction

Partners/Supporters

Current work / Strategies & Case Studies

Future Plans

Summary (Capabilities/Suggestions)


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Introduction/Technology Overview

- Manganese Boron steel (22MnB5) has ferritic pearliticmicrostructure in as received condition

- These blanks are heated to austenitization temperature

(~950C) for 5 minutes

- The heated blanks are formed and quenched in the press

at a cooling rate higher than 27K/sec

- Quenching changes the microstructure from austenite to

martensite and the final part is hardened and has an

ultimate tensile strength of around 1500 MPa


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Introduction/Direct Hot Stamping

Direct hot stamping process


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Partners/Supporters

National Science Foundation (NSF)- Supporting CPF/finite element simulations of hot

stamping

IMRA , Japan

- data base of references and information in hot stamping

POSCO (South Korea) and COSKUNOZ (Turkey)

- Providing geometry and experimental data on example

hot stamped components (details are proprietary)

International Cooperation with Various Universities:

Lulea, Erlangen, Hannover, Padova, Graz, Munich,

Dortmund


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FE Simulation of Hot Stamping

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Status / Update

Various companies/research groups are using combination of differentFE codes like LS-Dyna, ABAQUS, PAMSTAMP, FORGE, MSC. Marc,

AUTOFORM for simulating the entire hot stamping process

Our Strategy

Use PAMSTAMP and DEFORM 2D and 3D to predict

-Temperature distribution

-Thickness distribution

-Metal flow

-Elastic tool deflection

-Cooling channel optimization

Simulate and compare results with example parts a) from literature b)

provided by our partner companies


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Our Strategies

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1) Using Pam-Stamp and DEFORM together:

2) Using Pam-Stamp 2011, both for forming and quenching

simulations (work on-going)

Blank

Heating &

Transfer

Forming Quenching

Interface Software

DEFORM PAM-STAMP DEFORM


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Our Strategies: 1

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PAM-STAMP for forming, DEFORM for quenching simulations

3D simulation with PAM-STAMP

Generated new mesh for DEFORM 2D

Section information:

Coordinates, thickness and pressuredistribution from PAM-STAMP


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Our Strategies: 2

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PAM-STAMP 2011 for both Stamping and Quenching Simulations

Preliminary quenching simulations are completed, these have to be

validated by Hardness from literature and sponsor companies.


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Case Study-1/ Hat Shape

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Preliminary hot stamping simulations (Supported by NSF)

Hot stamping simulations are conducted using the FE code

DEFORMTM

Case Study-1

The hot stamping experiment conducted at Lulea University of

Technology, Sweden is simulated (Reference: AKER06).

In the experiment, hot 22MnB5 blank at 827C is formed with a tool

at 26C.

Forming force and temperature at a specified location are

measured during the experiment.


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11

Experimental Tool (left) and Blank(right) geometry [AKER06]

*All dimensions are in m


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Initial and final step in the simulation (Half of Hat Shape sample is

shown)


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0

5

10

15

20

25

30

35

0 1 2 3 4 5 6

Forming

force(kN)

Time (s)

Ex eriment

DEFORM 3D (FEA)

Forming Force vs Time


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720

740

760

780

800

820

840

0 1 2 3 4 5 6

Average

Temperature(

C)

Time (s)

DEFORM 3D (FEA)

Experiment

Average Temperature vs Time


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Case Study-1 /Hat Shape

Conclusions

-The forming force during the experiment and temperature

calculated at a specified point are matching closely with the

experiment

-The commercial software package DEFORM 3D handles

combined thermal and mechanical simulation well for

simple geometries.

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Case Study-2/ AUDI B-Pillar

-Bench Mark problem-3 given in

Numisheet-2008.

-2D section of the part is

simulated using DEFORM 2D

and the full model was handled

by PAM-STAMP 2011.

-The objective is to predict in the

formed part:

(1) thickness distribution,(2) hardness distribution,

(3) potential defects.

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Tooling for hot stamping of B-Pillar


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Input geometries for simulation

PunchDie

Blank holderBlank

Assembly

Reference: Benchmark problem-3, Numisheet 2008


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-A critical section of the B-Pillar is chosen for 2-dimensional

simulation (DEFORM 2D /Variable mesh density)

Initial simulation setupFinal simulation setup

Top die

(75 C)

Blank

holder(75 C)

Punch (75 C)

22 MnB5

Blank (810 C)

Section DEFORM 2D


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Full model - PAM-STAMP 2011

Non-isothermal die and blank,

Strain rate dependent material, Heat transfer coefficient = f(P),

Microstructure evolution,

Thermal/microstructural dilatation,

No cooling channels (at this point).


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0 15 30 45 60 75 90 1051.6

1.65

1.7

1.75

1.8

1.85

1.9

1.95

2

Curvilinear Distance to P2 [mm]

Thickness

(t)[mm]

Section 2a

Numisheet

PamStamp 11


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- Thickness of sheet can be calculated accurately.

- Hardness calculation is under progress.

0 15 30 45 60 751.6

1.65

1.7

1.75

1.8

1.85

1.9

1.95

2

Curvilinear Distance to P2 [mm]

Thickne

ss(t)[mm]

Section 2b

Numisheet

PamStamp 11


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Case study-3/ Cooling Channel Design

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Section of B-pillar fromNumisheet 2008

-Different combination

of cooling channelconfigurations and

examples from the

literature are simulated

to achieve uniformcooling and martensite

microstructureTemperature distribution at the

end of forming stage.

DEFORM 2D


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Summary / Ongoing Work

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- Material properties of 22MnB5 (Flow stress data, coefficient offriction, heat transfer coefficient, formability and forming limit

diagrams, phase transformation, anisotropy coefficient, elastic

properties),

- Material models,- Example finite element simulations (in cooperation with

participating companies),

- Tools for hot stamping / Cooling channel optimization,

- Blank heating methods (induction, resistance, furnace).


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Current and future work

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Optimization / selection of cooling channels,

Elastic deflection of dies / effect on heat transfer

between thinned sections and dies, Modification of die surface geometry,

Novel quenching methods (quenching holes in the

dies),

Correlation of microstructure to hardness.


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Non-proprietary information can be found at web sites:

www.cpforming.org

www.ercnsm.org

Dr. Taylan Altan ([email protected]), Ph-614-292-5063
http://www.cpforming.org/http://www.ercnsm.org/mailto:[email protected]:[email protected]://www.ercnsm.org/http://www.cpforming.org/

kassel - hot stamping

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