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Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Automation in Manufacturing
FIGURE 14.1 Outline of topics described in this chapter.
Flexible fixturing
Assembly Robots Material handling
Design for assembly, disassembly, and service
Fixed sequence, variable sequence, playback, NC, intelligent
Manipulators, automated guided vehicles
AC optimization
AC constraint
Computer NC
Adaptive control
Numerical control
Programming
Direct NC
Computer aided
Manual
Soft automation
Hard automation
Transfer machines
Automation of manufacturing processes Sensors
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
History of AutomationDate Development1500-1600 Water power for metalworking; rolling mills for coinage strips.1600-1700 Hand lathe for wood; mechanical calculator.1700-1800 Boring, turning, and screw cutting lathe, drill press.1800-1900 Copying lathe, turret lathe, universal milling machine; advanced mechanical calcu-
lators.1808 Sheet-metal cards with punched holes for automatic control of weaving patterns in
looms.1863 Automatic piano player (Pianola).1900-1920 Geared lathe; automatic screw machine; automatic bottle-making machine.1920 First use of the word robot.1920-1940 Transfer machines; mass production.1940 First electronic computing machine.1943 First digital electronic computer.1945 First use of the word automation.1947 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 manufacturing sys-tem; group technology.
1980s Artificial intelligence; intelligent robots; smart sensors; untended manufacturingcells.
1990-2000s Integrated manufacturing systems; intelligent and sensor-based machines; telecom-munications and global manufacturing networks; fuzzy-logic devices; artificial neuralnetworks; Internet tools; virtual environments; high-speed information systems.
TABLE 14.1 Developments in the history of automation and control of manufacturing processes. (See also Table 1.1.)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Flexibility and Productivity
FIGURE 14.2 Flexibility and productivity of various manufacturing systems. Note the overlap between the systems, which is due to the various levels of automation and computer control that are applicable in each group. See also Chapter 15 for more details.
Transfer line
Conventional flowline
Flexible manufacturing
line
Conventional job shop
Flexible manufacturing
system
Increasing productivity
Incre
asin
g f
lexib
ility
Soft automation Hard automation
Manufacturing cell
Stand-alone NC production
Type of production Number produced Typical productsExperimental or prototype 1-10 All typesPiece or small batch < 5000 Aircraft, machine tools, diesBatch or high quantity 5000-100,000 Trucks, agricultural machinery, jet engines, diesel
engines, orthopedic devicesMass production 100,000+ Automobiles, appliances, fasteners, bottles, food
and beverage containers
TABLE 14.2 Approximate a n n u a l q u a n t i t y o f production.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Characteristics of Production
FIGURE 14.3 General characteristics of three types of production methods: job shop, batch production, and mass production.
Production rate
Production quantity
Plant layoutProcess Flow line
Labor skill
Part variety
General purpose Equipment Special
Mass production
Type of production
Batch productionJob shop
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Transfer Mechanisms
FIGURE 14.4 Two types of transfer mechanisms: (a) straight, and (b) circular patterns.
(a) (b)
Powerheads
Workpiece
Rotaryindexing table
Workpiece
Power heads
Pallet
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Transfer Line
FIGURE 14.5 A traditional transfer line for producing engine blocks and cylinder heads. Source: Ford Motor Company.
Machine 2:
Mill, drill,ream, plunge
mill
Start
Machine 1:
Mill
Machine 3:
Drill, ream,plunge mill
Machine 4:
Drill, bore
Machine 5:
Drill, bore
Machine 6:
Drill, ream,bore, mill
Machine 10:
Bore
Machine 8:
Mill
Machine 7:
Drill, ream, bore
Machine 9:
Mill, drill, ream
Machine 12:
Bore
Machine 11:
Drill, ream,bore
Wash
Wash
Machine 13:
Finish hollow mill,finish gun ream,finish generate
Machine 14:
Ream, tap
Machine 15:
hone, wash, gage,bore, mill
Air test
AssembleAssembleAssemble
End
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Dimensioning Example
FIGURE 14.6 Positions of drilled holes in a workpiece. Three methods of measurements 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) mixed dimensioning, a combination of both methods.
(a)
+ + + + +
++
+
+
+
+
(b) (c)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Numerical Control
FIGURE 14.8 Schematic illustration of the components of (a) an open-loop, and (b) a closed-loop control system for a numerical control machine. (DAC is digital-to-analog converter.)
Computer:
Input commands, processing,output commands
Spindle
Work table
Machine tool
Lim
it s
witches
Positio
n feedback
Drive s
ignals
FIGURE 14.7 Schematic illustration of the major components of a numerical control machine tool.
(a)
Steppingmotor
Pulse train
Work table
Leadscrew
Gear
(b)
Feedback signal
DC
servomotor Gear
Input 1
2
Work table
Leadscrew
Comparator DAC
Positionsensor
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Displacement Measurement
FIGURE 14.9 (a) Direct measurement of the linear displacement of a machine-tool worktable. (b) and (c) Indirect measurement methods.
(a)
(b) (c)
Rack and pinion
Rotary encoderor resolver Linear motion
Worktable
Rotary encoderor resolver
Ball screw
Machine column
Worktable
Scale
Sensor
Machine bed
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Tool Movement & Interpolation
FIGURE 14.11 Types of interpolation in numerical control: (a) linear; (b) continuous path approximated by incremental straight lines; and (c) circular.
(a) (b)
Holes
1
2
3
4
Workpiece
Cutter
Workpiece
Cutterpath
Cutterradius
Machinedsurface
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.
(a)
y
x
(b) (c)
1
2
34
5
y
y
x
x
Quadrant
Segment
Full circle
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
CNC Operations
FIGURE 14.12 (a) Schematic illustration of drilling, boring, and milling operations with various cutter paths. (b) Machining a sculptured surface on a five-axis numerical control machine. Source: The Ingersoll Milling Machine Co.
(a) (b)
Point-to-point
Workpiece
Milling
3-axis contourmilling
2-axis contourmilling
Point-to-point andstraight line
2-axis contouring withswitchable plane
3-axis contouring continuous path
Drilling andboring
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Adaptive Control
FIGURE 14.13 Schematic illustration of the application of adaptive control (AC) for a turning operation. The system monitors such parameters as cutting force, torque, and vibrations; if they are excessive, AC modifies process variables, such as feed and depth of cut, to bring them back to acceptable levels.
Spindlemotor
Tachometer
Servodrives
Machinetool
Position
CNC Commands
% Spindle load
Spindle speed
Torque
VibrationAC
Part manufacturing
data
Velocity
Parameterlimits
Readout
Resolver
FIGURE 14.14 An example of adaptive control in slab milling. As the depth of cut or the width of cut increases, the cutting forces and the torque increase; the system senses this increase and automatically reduces the feed to avoid excessive forces or tool breakage. Source: After Y. Koren.
Conventional
Cutter travel
Adaptive control
Fe
ed
pe
r to
oth
(a)
WorkpieceCutter
Variable width of cut
(b) (c)
Variable depth of cut
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
In-Process Inspection
Cutting tool
Final worksize control
Gaginghead
Controlunit
Machinetool
Workpiece
FIGURE 14.15 In-process inspection of workpiece diameter in a turning operation. The system automatically adjusts the radial position of the cutting tool in order to machine the correct diameter.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Self-Guided Vehicle
FIGURE 14.16 (a) A self-guided vehicle (Tugger type). This vehicle can be arranged in a variety of configurations to pull caster-mounted cars; it has a laser sensor to ensure that the vehicle operates safely around people and various obstructions. (b) A self-guided vehicle configured with forks for use in a warehouse. Source: Courtesy of Egemin, Inc.
(a) (b)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Industrial Robots
FIGURE 14.18 Various devices and tools that can be attached to end effectors to perform a variety of operations.
2500 mm 3000 mm
2025 mm1075 mm
1200 mm
(a) (b)
2
3
1
4
5
6
FIGURE 14.17 (a) Schematic of a six-axis KR-30 KUKA robot; the payload at the wrist is 30 kg and repeatability is ±0.15 mm (±0.006 in.). The robot has mechanical brakes on all of its axes. (b) The work envelope of the KUKA robot, as viewed from the side. Source: Courtesy of KUKA Robotics.
Nut driver
(a) (b) (c)
(d) (e) (f)
Small power tool
Deburring tool
Dial indicator
Sheet metal
Electromagnet
Gripper
Object
Vacuum line
Suction cup
Robot arm
Workpiece
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Robot Types & Workspaces
FIGURE 14.19 Four types of industrial robots: (a) Cartesian (rectilinear); (b) cylindrical; (c) spherical (polar); and (d) articulated, (revolute, jointed, or anthropomorphic). Some modern robots are anthropomorphic, meaning that they resemble humans in shape and in movement. These complex mechanisms are made possible by powerful computer processors and fast motors that can maintain a robot's balance and accurate movement control.
(d)(a) (b) (c)
FIGURE 14.20 Work envelopes for three types of robots. The selection depends on the particular application (See also Fig. 14.17b.)
Rectangular
(a)
Cylindrical Spherical
Workenvelope
Workenvelopes
(b) (c)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Robot Applications
FIGURE 14.21 Spot welding automobile bodies with industrial robots. Source: Courtesy of Ford Motor Co.
FIGURE 14.22 Sealing joints of an automobile body with an industrial robot. Source: Cincinnati Milacron, Inc.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Robots and Transfer Lines
FIGURE 14.23 An example of automated assembly operations using industrial robots and circular and linear transfer lines.
Circulartransfer line
Robots
Remote center compliance
Torque sensor
Visual sensing
Linear transfer line
Programmablepart feeder
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Advanced End Effectors
FIGURE 14.24 A toolholder equipped with thrust-force and torque sensors (\it smart tool holder), capable of continuously monitoring the machining operation. (See Section 14.5). Source: Cincinnati Milacron, Inc.
Toolholder
Chuck
On-board electronicsto process signals
Drill
Straingages
Inductive transmitter
FIGURE 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 low durability (lack of robustness) in industrial applications. Source: Courtesy of Lord Corporation.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Applications of Machine Vision
FIGURE 14.26 Examples of machine vision applications. (a) In-line inspection of parts. (b) Identifying 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 with different shapes by means of input from a camera; the system's memory allows the robot to identify the particular shape to be painted and to proceed with the correct movements of a paint spray attached to the end effector.
(c)
(b)
(d)
(a)
Robotcontroller
Cameraview 1
Cameraview 2
Visioncontroller
Work-piece
Controller Camera 2Camera 1
Camera
Controller
Good Good Good
RejectRejectRejectReject
Robot
Camera
Workpieces
Visioncontrollerwith memory
Paintspray
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Fixturing
FIGURE 14.27 Components of a modular workholding system. Source: Carr Lane Manufacturing Co.
FIGURE 14.28 Schematic illustration of an adjustable-force clamping system. The clamping force is sensed by the strain gage, and the system automatically adjusts this force. Source: After P.K. Wright and D.A. Bourne.
Clamp
Amp ADC
Relay Microcomputer
Solenoidvalve
Work table
Workpiece
Hydraulicline
Hydraulic cylinder
Strain gage
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Design for Assembly
FIGURE 14.29 Stages in the design-for-assembly analysis. Source: After G. Boothroyd and P. Dewhurst.
Analyzefor manualassembly
Analyze forhigh-speedautomaticassembly
Analyzefor robotassembly
Select theassembly method
Improve the designand re-analyze
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Indexing Machines
FIGURE 14.30 Transfer systems for automated assembly: (a) rotary indexing machine, and (b) in-line indexing machine. Source: After G. Boothroyd.
(a)(b)
Stationaryworkhead
Completedassembly
Work carriersindexed
Parts feeder
Indexing table
Work carriers
Stationaryworkhead
Parts feeder
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Vibratory Feeder Guides
FIGURE 14.31 Examples of guides to ensure that parts are properly oriented for automated assembly. Source: After G. Boothroyd.
(a)
(c) (d)
(b)
Cutout rejectscup-shaped partsstanding on their tops
Parts rejectedif laying on side
Bowl wall Scallop Wiper blade
To deliverychute
Bowlwall
Slottedtrack
To deliverychute Slot in track
to orient screws
Screws rejected unlessin single file, end-to-end,or if delivery chute is full
Screws rejectedunless lying on side
Wiperblade
Pressurebreak
Bowl wallNarrowed track
Widthwise parts rejectedwhile only one row oflengthwise parts passTo delivery
chute
Bowl wallV cutout
To deliverychute
Part rejected ifresting on its top
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Robotics Example: Toboggan Deburring
FIGURE 14.32 Robotic deburring of a blow-molded toboggan. Source: Courtesy of Kuka Robotics, Inc. and Roboter Technologie, GmbH.
Toboggan
Robot
Deburring toolFixture
Cutouts