Production technology Ch38

7/31/2019 Production technology Ch38

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Kalpakjian SchmidManufacturing Engineering and Technology 2001 Prentice-Hall Page 38-1

CHAPTER 38

Automation of Manufacturing Processes


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Chapter 38 Outline

Figure 38.1


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Development in the History of Automation ofManufacturing Processes

TABLE 38.1

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 in looms.1863 Automatic piano player (Pianola).19001920 Geared lathe; automatic screw machine; automatic bottlemaking 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.1960s Industrial robots.

1965 Large-scale integrated circuits.1968 Programmable logic controllers.

1970 First integrated manufacturing system; spot welding of automobile bodies with robots.1970s Microprocessors; minicomputer-controlled robot; flexible manufacturing systems; group technology.

1980s Artificial intelligence; intelligent robots; smart sensors; untended manufacturing cells,1990s Integrated manufacturing systems; intelligent and sensor-based machines; telecommunications and

global manufacturing networks; fuzzy logic devices; artificial neural networks; Internet tools.


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Approximate Annual Volume of Production

TABLE 38.2Type of production Number produced Typical products

Experimental or prototype 110 All

Piece or small batch 105000 Aircraft, special machinery, dies, jewelry, orthopedic

implants, missiles.

Batch or high volume 5000100,000 Trucks, agricultural machinery, jet engines, diesel engines;

computer components, sporting goods.

Mass production 100,000 and over Automobiles, appliances, fasteners, food and beveragecontainers.


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Flexibility and Productivity of ManufacturingSystems

Figure 38.2 Flexibility and productivity of various manufacturing systems. Note the overlapbetween the systems; it is due to the various levels of automation and computer control that arepossible in each group. See, also, Chapter 39, for details. Source: U. Rembold, et al., Computer

Integrated Manufacturing and Engineering. Addison-Wesley, 1993.


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Characteristics of Production Methods

Figure 38.3 General characteristics of three types of production methods: jobshop, batch, and mass production.


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Transfer Mechanisms

Figure 38.4 Two

types of transfermechanisms: (a)straight and (b)circular patterns.


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Transfer Line

Figure 38.5 A large transfer line for producing engine blocks and cylinder heads. Source: FordMotor Company.


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Dimensioning and Numerical Control

Figure 38.6 Positions of drilled holes in a workpiece.Three methods of measurements are shown: (a) absolutedimensioning, referenced from one point at the lower left ofthe part; (b) incremental dimensioning, made sequentiallyform one hole to another; and (c) mixed dimensioning, acombination of both methods.

Figure 38.7 Schematic illustration of the majorcomponents of a numerical-control machinetool.


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Open- and Closed-Loop Control Systems

Figure 38.8 Schematic illustration of the components of (a) an open-loop and (b) aclosed-loop control system for a numberical-control machine. DAC means digital-to-analog converter.


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Direct and Indirect Measurements

Figure 38.9 (a) Direct measurement of the linear displacement of a machine-tool work table. (b) and (c)Indirect measurement methods.


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Tool Movement and InterpolationFigure 38.10 Movement oftools in numerical-controlmachining. (a) Point-to-point,in which the drill bit drills a

hole at position 1, is retractedand moved to position 2, andso on. (b) Continuous path bya milling cutter. Note that thecutter path is compensated forby the cutter radius. This pathcan also be compensated for

cutter wear.

Figure 38.11 Typesof interpolation innumerical control:(a) linear, (b)continuous path

approximated byincremental straightlines, and (c)circular.


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Point-to-Point and Contour Maching

(a) (b)

Figure 38.12 (a) Schematic illustration of drilling, boring, and milling with various paths. (b)Machining a sculptured surface on a 5-axis numerical control machine. Source: The IngersollMilling Machine Co.


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Adaptive Control

Figure 38.13 Schematicillustration of the

application of adaptivecontrol (AC) for a turningoperation. The systemmonitors such parametersas cutting foce, torque,and vibrations; if they areexcessive, it modifies

process variables such asfeed and depth of cut tobring them back toacceptable levels.


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Adaptive Control in Milling

Figure 38.14 An example of adaptive control in milling. As the depth of cut or the width of cutincreases the cutting forces and the torque increase. The system senses this increase andautomatically reduces the feed to avoid excessive forces or tool breakage, in order to maintain cuttingefficiency. Source: Y. Koren.


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Workpiece Inspection for Adaptive Control

Figure 38.15 In-processinspection of workpiece

diameter in a turningoperation. The systemautomatically adjusts theradial position of the cuttingtool in order to produce thecorrect diameter.


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Self-Guided Vehicle

Figure 38.16 A self-guided vehicle (Caterpillar ModelSGC-M) carrying a machining pallet. The vehiclre isaligned next to a stand on the floor. Instad of following awire or stripe path on the factory floor, this vehiclecalculates its own path and automatically corrects for anydeviations. Source: Courtesy of Caterpillar Industrial,Inc.


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Six-Axis S-10 GMF RobotFigure 38.17 (a)Schematic illustrationof a six-axis S-10 GMFrobot. The payload at

the wrist is 10 kg andrepeatability is 0.2mm (0.008 in.). Therobot has mechanicalbrakes on all itrs axes,which are coupleddirectly. (b) The workenvelope of the robot,as viewed from theside. Source:GMFanuc RoboticsCorporation.


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End Effectors

Figure 38.18 (a) Various devices and tools attached to end effectors to perform a variety of operations. (b) Asystem of compensating for misalignment during automated assembly. Source: ATI Industrial Automation.


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Industrial Robots

Figure 38.19 Four types of industrial robots: (a) cartesian (rectilinear), (b) cylindrical, (c) spherical(polar), (d) articulated (revolute, jointed, or anthropomorphic).


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Work Envelopes

Figure 38.20 Workenvelopes for three types ofrobots. The choice

depends on the particularapplication. See also Fig.38.17.


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Examples ofIndustrial

Robot Use

Figure 38.21 Spotwelding automobilebodies with industrial

robots. Source: Courtesyof Cincinnati Milacron,Inc.

Figure 38.22 Sealing joints

of an automobile body withan industrial robot. Source:Courtesy of CincinnatiMilacron, Inc.


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Automated Assembly Operations

Figure 38.23Automated assemblyoperations usingindustrial robots and

circular and lineartransfer lines.


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Mechanical and Tactile Sensors

Figure 38.24 A toolholder equipped with thrust-force and torque sensors (smart toolholder), capableof continuously monitoring the cutting operation.Such toolholders are necessary for adaptive controlof manufacturing operations. (See Section 38.5.)Source: Cincinnati Milacron, Inc.

Figure 38.25 Arobot gripper withtactile sensors. Inspite of their

capabilities,tactile sensors arenow being usedless frequently,because of theirhigh cost andtheir lowdurability inindustrialapplications.Source: Courtesyof LordCorporation.


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Machine-Vision Applications

Figure 38.26 Examples of machine-vision applications. (a) In-line inspection of parts. (b) Identification ofparts with various shapes, and inspection and rejection of defective parts. (continued)


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Machine-Vision Applications (cont.)

Figure 38.26 (continued) (c) Use of cameras to provide positional input to a robot relative to the workpiece.(d) Painting parts having different shapes by means of input from a camera. The systems memory allows therobot to identify the particular shape to be painted and to proceed with the correct movementso f a paint sprayattached to the end effector.


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Flexible Fixturing

Figure 38.27 Schematicillustration of a flexiblefixturing setup. The clampingforce is sensed by the straingage, and the systemautomatically adjusts thisforce. Source: P. K. Wright.


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Design-for-Assembly Analysis

Figure 38.28 Stages in the design-for-assembly analysis. Source:Product Design for Assembly,1989 edition, by G. Boothroyd andP. Dewhurst. Reproduced withpermission.


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Automated Assembly Transfer Systems

Figure 38.29 Transfer systems for automated assembly: (a) rotary indexingmachine, (b) in-line indexing machine. Source: G. Boothroyd.


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Robot Assembly Station

Figure 38.30 Atwo-arm robotassembly station.Source:ProductDesign for

Assembly, 1989edition, by G.Boothroyd and P.Dewhurst.Reproduced withpermission.


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Guides

Figure 38.31 Variousguides that ensure that partsare properly oriented forautomated assembly.Source: G. Boothroyd.


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Automated Assembly Parts

Figure 38.32 Redesign of parts to facilitate automated assembly. Source: G. Boothroyd.


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Design ComparisonFigure 38.33

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Production technology Ch38