chapter 14 automation of manufacturing processes and systems.pdf

8/14/2019 Chapter 14 Automation of Manufacturing Processes and Systems.pdf

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Manufacturing Processes for Engineering Materials, 4th ed.

Kalpakjian Schmid

Prentice Hall, 2003

Chapter 14

Automation of

Manufacturing

Processes and

Systems


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Topics in Chapter 14

FIGURE 14.1 Outline of topics described in this chapter.


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History ofAutomation

TABLE 14.1

Developments in the

History of Automation

and Control of

Manufacturing

Processes (see also

Table 1.1)

Date Development

15001600 Water power for metalworking; rolling mills for coinage strips.16001700 Hand lathe for wood; mechanical calculator.17001800 Boring, turning, and screw cutting lathe, drill press.18001900 Copying lathe, turret lathe, universal milling machine; advanced mechanical

calculators.

1808 Sheet-metal cards with punched holes for automatic control of weaving patterns inlooms.

1863 Automatic piano player (Pianola).19001920 Geared lathe; automatic screw machine; automatic bottle making machine.1920 First use of the word robot.19201940 Transfer machines; mass production.1940 First electronic computing machine.1943 First digital electronic computer.1945 First use of the word automation.1948 Invention of the transistor.1952 First prototype numerical-control machine tool.1954 Development of the symbolic language APT (Automatically Programmed Tool);

adaptive control.1957 Commercially available NC machine tools.1959 Integrated circuits; first use of the term group technology.1960 Industrial robots.1965 Large-scale integrated circuits.1968 Programmable logic controllers.1970s First integrated manufacturing system; spot welding of automobile bodies with

robots; microprocessors; minicomputer-controlled robot; flexible manufacturingsystem; group technology.

1980s Artificial intelligence; intelligent robots; smart sensors; untended manufacturingcells.

1990-2000s

Integrated manufacturing systems; intelligent and sensor-based machines;telecommunications and global manufacturing networks; fuzzy logic devices;artificial neural networks; Internet tools; virtual environments; high-speedinformation systems.


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Flexibility vs. Productivity

FIGURE 14.2 Flexibility and productivity of various manufacturing systems. Note the overlapbetween the systems, which is due to the various levels of automation and computer controlthat are possible in each group. See also Chapter 15 for more details. Source: U. Rembold et al.,Computer Integrated Manufacturing and Engineering, Addison-Wesley, 1993.


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Characteristics of Production Methods

FIGURE 14.3 General characteristics of three types of production methods: job shop,batch production, and mass production.


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Transfer Mechanisms

FIGURE 14.4 Two types of transfer mechanisms: (a) straight, and (b) circular patterns.


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Transfer Line Example

FIGURE 14.5A traditional

transfer line for

producing

engine blocks

and cylinder

heads. Source:Ford Motor

Company.


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Measurement Approaches

FIGURE 14.6 Positions of drilled holes in a workpiece. Three methods of measurement are

shown: (a) absolute dimensioning, referenced from one point at the lower left of the part; (b)incremental dimensioning, made sequentially from one hole to another; and (c) mixeddimensioning, a combination of both methods.


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NumericalControl

Machine Tool

FIGURE 14.7 Schematic

illustration of the major

components of a numerical

control machine tool.


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Open and Closed Loop Control

FIGURE 14.8 Schematic illustration of the components of (a) an open-loop, and (b) aclosed-loop control system for a numerical control machine. DAC means digital-to-

analog converter.


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Measurement of Linear Displacement

FIGURE 14.9 Direct measurement of the linear displacement of a machine-toolworktable. (b) and (c) Indirect measurement methods.


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Path of Cutters in NC

FIGURE 14.10 Movement of tools in numerical control machining. (a) Point-to-point system:

The drill bit drills a hole at position 1, is then retracted and moved to position 2, and so on. (b)

Continuous path by a milling cutter. Note that the cutter path is compensated for by the cutter

radius. This path can also compensate for cutter wear.


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Types of Interpolation

FIGURE 14.11 Types of interpolation in numerical control: (a) linear; (b) continuouspath approximated by incremental straight lines; and (c) circular.


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Illustration of Cutter Paths

FIGURE 14.12 (a) Schematic illustration of drilling, boring, and milling operations withvarious cutter paths. (b) Machining a sculptured surface on a five-axis numerical control

machine. Source: The Ingersoll Milling Machine Co.


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Adaptive Control in Turning

FIGURE 14.13 Schematic illustration of the application of adaptive control (AC) for a turningoperation. The system monitors such parameters as cutting force, torque, and vibrations; if theyare excessive, it modifies process variables such as feed and depth of cut to bring them back toacceptable levels.


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Adaptive Control in Milling

FIGURE 14.14 An example of adaptive control in milling. As the depth of cut or the widthof cut increases, the cutting forces and the torque increase. The system senses this increaseand automatically reduces the feed to avoid excessive forces or tool breakage, in order tomaintain cutting efficiency. Source: Y. Koren.


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In-Process Inspection

FIGURE 14.15 In-process inspection of workpiece diameter in a turning operation. Thesystem automatically adjusts the radial position of the cutting tool in order to produce the

correct diameter.


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Self-Guided Vehicle

FIGURE 14.16 A self-guided

vehicle (Caterpillar Model SGC-M)

carrying a machining pallet. The

vehicle is aligned next to a standon the floor. Instead of following a

wire or stripe path on the factory

floor, this vehicle calculates its

own path and automatically

corrects for any deviations. Source:

Courtesy of Caterpillar Industrial,

Inc.


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Six-Axis

Robot

FIGURE 14.17 (a) Schematic of a six-axis S-10 GMF robot. The payload at the wrist is 10 kg

(22 lb.) and repeatability is 0.2 mm (0.008 in.). The robot has mechanical brakes on all itsaxes, which are coupled directly. (b) The work envelope of a robot, as viewed from the side.Source: GMFanuc Robotics Corporation.


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Grippers for Robots

FIGURE 14.18 (a) Various devices and

tools attached to end effectors to perform

a variety of operations. (b) A system that

compensates for misalignment duringautomated assembly. Source: ATI

Industrial Automation.


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Types of Industrial Robots

FIGURE 14.19 Four types of industrial robots: (a) Cartesian (rectilinear); (b) cylindrical; (c)spherical (polar); and (d) articulated (revolute, jointed, or anthropomorphic).


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Work

Envelopesfor Robots

FIGURE 14.20 Work

envelopes for three

types of robots. The

choice depends on theparticular application.

See also Fig. 14.17b.


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Robot Applications

FIGURE 14.21 Spot welding

automobile bodies with industrialrobots. Source: Courtesy of

Cincinnati Milacron, Inc.

FIGURE 14.22 Sealing joints of an

automotive body with an industrial

robot. Source: Courtesy of



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Automated

Assembly

FIGURE 14.23 Automated assembly operations using industrial robots and circular andlinear transfer lines.


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Smart Tool Holder

FIGURE 14.24 A tool holder

equipped with thrust force and

torque sensors (smart tool

holder), capable of

continuously monitoring the

cutting operation. Such tool

holders are necessary for

adaptive control of

manufacturing operations. (See

Section 14.5). Source:



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Gripper with Tactile

SensorsFIGURE 14.25 A robot gripper with tactile

sensors. In spite of their capabilities, tactile

sensors are now being used less frequently,

because of their high cost and their low

durability in industrial applications. Source:

Courtesy of Lord Corporation.


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Machine

VisionApplications

FIGURE 14.26 Examples of machine vision applications. (a) In-line inspection of parts. (b)Identification of parts with various shapes, and inspection and rejection of defective parts. (c)Use of cameras to provide positional input to a robot relative to the workpiece. (d) Painting of

parts that have different shapes by means of input from a camera. The systems memoryallows the robot to identify the particular shape to be painted and to proceed with the correctmovements of a paint spray attached to the end effector.


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Modular Workholding System

FIGURE 14.27 Typical components of a modular workholding system.Source: Carr Lane Manufacturing Co.


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Stages in

Design-for-Assembly

Analysis

FIGURE 14.29 Stages in the design-for-assembly analysis. Source: Product Designfor Assembly, 1989 edition, by G. Boothroyd and P. Dewhurst. Reproduced withpermission.


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Transfer Systems for Automated Assembly

FIGURE 14.30 Transfer systems for automated assembly: (a) rotaryindexing machine; (b) in-line indexing machine. Source: G. Boothroyd.


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Guides for

AutomatedAssembly

FIGURE 14.31 Various guides that ensure that parts are properly oriented for

automated assembly. Source: G. Boothroyd.


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Case Study Housing

FIGURE 14.32 Cast-iron housing and the machining operations required.


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Modular Fixture Components

FIGURE 14.33

Modular components

used to construct the

fixture for CNCmachining of the cast-

iron housing depicted

in Fig. 14.32.


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Completed Modular Fixture

FIGURE 14.34 Completed modular fixture with cast-iron housing in place, aswould be assembled for use ina machining center or CNC milling machine.

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