A process automation or automation system (PAS) is employed to immediately get a handle on an ac...

Automation in Manufacturing Automation of manufacturing processes

Sensors

Manual Soft automation

Hard automation

Transfer machines

Computer aided

Programming

Numerical control

Adaptive control

Direct NC

AC constraint

Computer NC

AC optimization

Material handling

Manipulators, automated guided vehicles

Robots

Assembly

Design for assembly, disassembly, and service Fixed sequence, variable sequence, playback, NC, intelligent

FIGURE 14.1 Outline of topics described in this chapter.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Flexible fixturing

History of Automation Date 1500-1600 1600-1700 1700-1800 1800-1900 1808 1863 1900-1920 1920 1920-1940 1940 1943 1945 1947 1952 1954 1957 1959 1960 1965 1968 1970s 1980s 1990-2000s

Development Water power for metalworking; rolling mills for coinage strips.

Hand lathe for wood; mechanical calculator.

Boring, turning, and screw cutting lathe, drill press.

Copying lathe, turret lathe, universal milling machine; advanced mechanical calculators.

Sheet-metal cards with punched holes for automatic control of weaving patterns in looms.

Automatic piano player (Pianola).

Geared lathe; automatic screw machine; automatic bottle-making machine.

First use of the word robot.

Transfer machines; mass production.

First electronic computing machine.

First digital electronic computer.

First use of the word automation.

Invention of the transistor.

First prototype numerical control machine tool.

Development of the symbolic language APT (Automatically Programmed Tool); adaptive control.

Commercially available NC machine tools.

Integrated circuits; first use of the term group technology.

Industrial robots.

Large-scale integrated circuits.

Programmable logic controllers.

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

Artificial intelligence; intelligent robots; smart sensors; untended manufacturing cells.

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

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid Š 2008, Pearson Education ISBN No. 0-13-227271-7

TABLE 14.1 Developments in the history of automation and control of manufacturing processes. (See also Table 1.1.)

Flexibility and Productivity Flexible manufacturing system

Increasing flexibility

Conventional job shop

Manufacturing cell Stand-alone NC production

Flexible manufacturing line Conventional flowline Transfer line

Soft automation

Hard automation

Increasing 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.

Type of production Experimental or prototype Piece or small batch Batch or high quantity Mass production

Number produced 1-10 < 5000 5000-100,000 100,000+

Typical products All types Aircraft, machine tools, dies Trucks, agricultural machinery, jet engines, diesel engines, orthopedic devices Automobiles, appliances, fasteners, bottles, food and beverage containers

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

TABLE 14.2 Approximate annual quantity of production.

Characteristics of Production Type of production Job shop

Batch production

General purpose

Equipment

Mass production Special

Production rate Production quantity Process

Plant layout

Flow line

Labor skill Part variety

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

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Transfer Mechanisms Power heads Power heads

Workpiece Workpiece Pallet

Rotary indexing table (a)

(b)

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

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Transfer Line Start

Machine 1: Mill

Machine 2: Machine 3: Drill, ream, Mill, drill, ream, plunge plunge mill mill

Machine 12: Bore

Machine 11: Drill, ream, bore

Wash

Machine 10: Bore

Machine 5: Drill, bore

Machine 6: Drill, ream, bore, mill

Machine 9: Mill, drill, ream

Machine 8: Mill

Machine 7: Drill, ream, bore End

Wash

Machine 14: Machine 13: Finish hollow mill, Ream, tap finish gun ream, finish generate

Assemble

Machine 4: Drill, bore

Air test

Machine 15: hone, wash, gage, bore, mill

Assemble

Assemble

FIGURE 14.5 A traditional transfer line for producing engine blocks and cylinder heads. Source: Ford Motor Company.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Dimensioning Example

+

+

+ +

+

+ +

(a)

+ +

+

(b)

+

(c)

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.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Numerical Control

Limit switches

Position feedback

Drive signals

Computer: Input commands, processing, output commands

FIGURE 14.7 Schematic illustration of the major components of a numerical control machine tool.

Spindle

Work table Work table

Pulse train

Machine tool

Stepping motor

Gear Leadscrew (a)

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.)

Input

Work table

1 Comparator 2

DAC

DC

servomotor

Leadscrew Feedback signal (b)

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Gear Position sensor

Displacement Measurement Machine column Worktable Scale Machine bed Sensor

(a)

Ball screw

Worktable Rack and pinion

Rotary encoder or resolver Rotary encoder or resolver (b)

Linear motion (c)

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

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Tool Movement & Interpolation Workpiece 1

Cutter

Cutter radius

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.

3 4

Cutter path

2 Holes

Workpiece

(a)

Machined surface

(b)

y

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

y

y Quadrant 3

4

Full circle

5

x

2 1 x (a)

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Segment

x (b)

(c)

CNC Operations Point-to-point and straight line

Point-to-point Drilling and boring

Milling

Workpiece 2-axis contouring with switchable plane

3-axis contouring continuous path

2-axis contour milling

(a)

3-axis contour milling

(b)

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.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Adaptive Control Velocity Position Resolver Part manufacturing data

CNC

Commands

Servo drives

Tachometer

Machine tool

Spindle motor

% Spindle load Spindle speed Torque Parameter limits

AC

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.

Vibration

Readout

Workpiece Feed per tooth

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.

Cutter

Adaptive control Conventional

Variable depth of cut

Variable width of cut

Cutter travel

(a)

(b)

(c)

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

In-Process Inspection Gaging head

Workpiece

Cutting tool

Machine tool

Control unit

Final work size control

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 Education ISBN No. 0-13-227271-7

Self-Guided Vehicle

(a)

(b)

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.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Industrial Robots 5 4

6

2500 mm

3000 mm

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.

3

2

1 1200 mm 1075 mm (a)

2025 mm (b)

Vacuum line

Small power tool

Robot arm Suction cup Workpiece

FIGURE 14.18 Various devices and tools that can be attached to end effectors to perform a variety of operations.

Nut driver Deburring tool (a)

(b)

Electromagnet

(c)

Dial indicator Gripper

Sheet metal

Object (d)

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

(e)

(f)

Robot Types & Workspaces

(a)

(b)

(c)

(d)

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.

Rectangular

Cylindrical

Work envelope

Spherical Work envelopes

FIGURE 14.20 Work envelopes for three types of robots. The selection depends on the particular application (See also Fig. 14.17b.)

(a)

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

(b)

(c)

Robot Applications

FIGURE 14.21 Spot welding automobile bodies with industrial robots. Source: Courtesy of Ford Motor Co.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

FIGURE 14.22 Sealing joints of an automobile body with an industrial robot. Source: Cincinnati Milacron, Inc.

Robots and Transfer Lines Robots

Remote center compliance Circular transfer line

Linear transfer line Torque sensor Visual sensing

Programmable part feeder

FIGURE 14.23 An example of automated assembly operations using industrial robots and circular and linear transfer lines.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Advanced End Effectors Toolholder Inductive transmitter On-board electronics to process signals Chuck

Strain gages

Drill

FIGURE 14.24 A toolholder equipped with thrustforce and torque sensors (\it smart tool holder), capable of continuously monitoring the machining operation. (See Section 14.5). Source: Cincinnati Milacron, Inc. Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

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.

Applications of Machine Vision Controller Controller

Camera 1

Camera 2

Good

Good

Good

Camera

Reject

Reject

(a)

Reject

(b)

Camera view 1 Robot controller

Paint spray

Camera Vision view 2 controller

Workpiece

Reject

Workpieces Camera Vision controller with memory

(c)

Robot (d)

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.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Fixturing Relay

Microcomputer

Clamp Amp Hydraulic line

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

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Strain gage

Solenoid valve

Hydraulic cylinder

ADC

Workpiece Work table

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.

Design for Assembly Select the assembly method

Analyze for high-speed automatic assembly

Analyze for manual assembly

Analyze for robot assembly

Improve the design and re-analyze

FIGURE 14.29 Stages in the design-for-assembly analysis. Source: After G. Boothroyd and P. Dewhurst.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Indexing Machines Parts feeder Parts feeder Stationary workhead

Stationary workhead

Completed assembly

Work carriers

Work carriers indexed

Indexing table (a)

(b)

FIGURE 14.30 Transfer systems for automated assembly: (a) rotary indexing machine, and (b) inline indexing machine. Source: After G. Boothroyd.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Vibratory Feeder Guides Narrowed track

Bowl wall

V cutout

Widthwise parts rejected while only one row of lengthwise parts pass

To delivery chute

Part rejected if resting on its top To delivery chute

(a)

Slotted track

Bowl wall

Pressure break

(b)

Wiper blade

Bowl wall

Screws rejected unless lying on side

To delivery Slot in track chute to orient screws

Bowl wall

Screws rejected unless in single file, end-to-end, or if delivery chute is full (c)

To delivery chute

Scallop Wiper blade

Parts rejected if laying on side Cutout rejects cup-shaped parts standing on their tops (d)

FIGURE 14.31 Examples of guides to ensure that parts are properly oriented for automated assembly. Source: After G. Boothroyd.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7

Robotics Example: Toboggan Deburring Robot Cutouts

Toboggan

Deburring tool

Fixture

FIGURE 14.32 Robotic deburring of a blow-molded toboggan. Source: Courtesy of Kuka Robotics, Inc. and Roboter Technologie, GmbH.

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7