Introduction to Automation PDF

INTRODUCTION TO AUTOMATION « Automation is the technology by which a process or procedure is accomplished without human assistance. ~ It is implemented using a program of instructions combined with a control system that executes the instructions. To automate a process,power is required, both t...

INTRODUCTION TO AUTOMATION « Automation is the technology by which a process or procedure is accomplished without human assistance. ~ It is implemented using a program of instructions combined with a control system that executes the instructions. To automate a process,power is required, both to drive the process itself and to operate the program and control system. « Although automation can be applied in a wide variety of areas, it is most closely associated with the manufacturing industries. HISTORY OF AUTOMATION » The wheel (circa 3200 B.C.), ~ Lever, winch (circa 600 B.C.), « Cam (circa A,D. 1000), ~ Screw(A.D. 1405), * Windmills (circa A.D. 650), * Steam engines (A.D.1/65). « Flour mills ( circa 85 B.C. ), « Weaving machines (flying shuttle, 1733), « Machine tools (boring mill, 1775), * Steamboats (1787), ~ Railroad locomotives (1803). ~ Electrification (starting in 1881 ) HISTORY OF AUTOMATION CONT... “* The moving-assembty tine (t9t3)-_ Mechanized transfer tines for mass production, whose programs were fixed by their hardware configuration (1924), ** A mathematical theory of control systems (1938 and 1948); and *“* The MARK | electromechanical computer at Harvard University (1944). “* The first electronic digital computer was developed at University of Pennsylvania in 1946. “+ The first numerical control machine tool was developed and demonstrated in 1952 at Massachusetts Institute of Technology based on a concept proposed by John Pamons and Frank Stulen * By the late 1968 and early 1970s, digital computers were being connected to machine tools. **¢ In 1954, the first industrial robot was designed and patented (issued 1961) by George Devol *¢ The first commercial robot was installed to unload parts in a die casting operation in 1961. HISTORY OF AUTOMATION CONT... « In the late 1968, the first flexible manufacturing system in the United States was installed at Ingersoll Rand Company to perform machining operations on a variety of parts. « Around 1969, the first programmable logic controller was introduced. « In 1978, the first commercial personal computer (PC) had been introduced by Apple Computer, although a similar product had been introduced in kit form as early as 1975. ~ Developments in computer technology were made possible by advances in electronics, including the transistor (1948), » hard disk for computer memory (1956), - Integrated circuits (1960), » The microprocessor (1971) HISTORY OF AUTOMATION CONT... + Random accesss memory (1984), » Megabyte capacity memory chips (circa 1990), » The Pentium microprocessors (1993). + Software developments related to automation have been equally important, including the FO RIRAN computer programming language (1955), « The APT programming language for numerical control (NC) machine tools (1961), + The UNIX operating system (1969), » The VAL language for robot programming (1979), ~ Microsoft Windows (1985),and the JAVA programming language (1995). « Advances and enhancements in these technologies continue Ji ree, 77 ; -EMENTS OF AN Al Sh, (1)Power, _ (2)Program of instructions, and» _(3)Control systems. il YY MII Power 0) 0) | | Program of Control instructions hae system Ear Hi es +. POYYER TR O&&QhiPLish THE OLTRMATER PROCESS Process Power Form Action Accomplished Casting Thermal Melting the metal before pouring into a mold cavity where solidification occurs. Electric discharge Electrical Metal removal is accomplished by a series of discrete machining (EDM) Forging Mechanical Heat treating Thermal Injection molding Thermal and mechanical Laser beam cutting Light and thermal Machining Mechanical Sheet metal punching Mechanical and blanking Welding Thermal (maybe mechanical) electrical discharges between electrode (tool) and workpiece. The electric discharges cause very high localized temperatures that melt the metal. Metal workpart is deformed by opposing dies. Workparts are often heated in advance of deformation, thus thermal power is also required. Metallic work unit is heated to temperature below melting point to effect microstructural changes. Heat jis used to raise temperature of polymer to highly plastic consistency, and mechanical force is used to inject the polymer melt into a mold cavity. A highly coherent light beam is used to cut materia! by vaporization and melting. Cutting of metal is accomplished by relative motion between tool and workpiece. Mechanica! power is used to shear metal sheets and plates. Most welding processes use heat to cause fusion and coalescence of two (or more) metal parts at their contacting surfaces. Some welding processes also apply mechanical pressure to the surfaces. « The actions performed by an automated process are defined a program of instructions. « Whether the manufacturing operation involves low, medium, or high production each part or product style made in the operation requires one or more processing steps that are unique to that style. « These processing steps are performed during a work cycle. « Anew part Is completed during each work cycle. « The particular processing steps for the work cycle are specified in a work cycle program ~~. ™ + “ke FEATURES OF WORK CYCLE PROGRAMS sat Program Feature VAY IN AUTOMATED SYSTEMS A — Swe ne oe Examples or Alternatives Steps in work cycle Process parameters (inputs) in each step Manual steps in work cycle Operator interaction Different part or product styles Variations in starting work units Example: * Typical sequence of steps: (1) load, (2), process, (3) unload Alternatives: * One parameter versus multiple parameters that must be changed during the step + Continuous parameters versus discrete parameters + Parameters that change during the step; for example, a positioning system whose axes values change during the processing step Alternatives: + Manual steps versus no manual steps (completely automated work cycle) Example: * Operator loading and unloading parts to and from machine Alternatives: * Operator interaction versus completely automated work cycle Example: * Operator entering processing information for current workpart Alternatives: - Identical part or product style each cycle (mass or batch production) versus different part or product styles each cycle (flexible automation) Example: * Variations in starting dimensions or part features 3, CONTROL SYSTEM « The control element of the automated system executes the program of instructions. « The control system causes the process to accomplish its defined function, which for our purpose Is to carry out some manufacturing operation. + Let us provide a brief introduction to control systems here. « The controls In an automated system can be either closed loop or open loop A FEEDBACK CONTROL SYSTEM OR CLOSED LOOP CONTROL SYSTEM wrreepre Sf PE PRE NRA LEWE LW PAULYVITIOUURD (1) (5) (6) (2) (3) utput Input Controller x» Actuator —— Process > 0 yg parameter variable (4) Feedback Pee sensor Input parameter ~~ Controller} Actuator bro Praeese Output L: variable Open loop control system ee 3 Worktable Actual-x x-value input —meeet=} Controller Motor | Boas AWALALEESEE AT Optical Leadscrew encoder i Feedback signal to controller A positioning system consist of a lead screw driven by a DC Motor 4 Types of Automation = Fixed Automation = Programmable Automation » Flexible Automation — Fixed Automation « A system in which the sequence of the (usually simple) processing or assembly operation is fixed by the equipment configuration. The integration and coordination among the operation make the system very complex. = Consists of workstations connected by conveyers or machine transfer lines. a Fixed Automation 0 High initial investment for customised equipment (Jig, Die, etc.) o High production rate. oO Relatively flexible in accommodating product changes only. o Only product with high demands and volumes — automobile. Fixed Automation Press Automation Body Assembly Paint Finishing +} Programmable Automation « The production equipment is designed with the capability to change the sequence of operations to accommodate different product configuration. = Operation sequence controlled by program. Usually new program required for new product. « Consists of NC machining centres, industrial robots etc =" Programmable Automation o High investment in general-purpose equipment. o Low production rates relative to fixed automation-Usually low and medium-volume production. o Flexibility to deal with changes in product configuration. 0 Most suitable for batch production-change over time required. a Programmable Automation of Flexible Automation = Capable of producing a variety of products (or parts) with virtually no time lost for changeovers. = (Can produce various combinations and schedules of products (instead of batch production). = No down time for changeovers or program changes — physical setup needs to be placed simultaneously. a Flexible Automation o High investment for customised equipment. o Continuous production of variable mixtures of products, o Medium production rate. o Flexibility to deal with product design variations. ADVANCED AUTOMATION FUNCTIONS Advanced automation functions include the following: (1) safety monitoring, (2) Maintenance and repair diagnostics and (3) error detection and recovery. 1, SAFETY MONITORING The following list suggests some of the possible sensors and their applications for safety monitoring: » Limit switches to detect proper positioning of a part in a work holding device Photoelectric sensors triggered by the interruption of a light beam ~ Temperature sensors to indicate that a metal workpart is hot enough to proceed with a hot forging operation. + Heat or smoke detectors to sense fire hazards. » Pressure-sensitive floor pads to detect human intruders into the work cell. » Machine vision systems to supervise the automated system and its surroundings 2. MAINTENANCE AND REPAIR DIAGNOSTICS 1.Status monitoring: In the status monitoring mode, the diagnostic subsystem monitors and records the status of key sensors and parameters of the system during normal operation 2. Failure diagnostics: The failure diagnostics mode is invoked when a malfunction or failure occurs. 3. Recommendation of repair procedure: In the third mode of operation, the subsystem provides a recommended procedure to the repair crew as to the steps that should be taken to effect repairs. + + : Ya? FO ; a rea ate wmM | aA " In the operation of any automated system, there are hardware malfunctions and unexpected events that occur during operation. These events can result in costly delays and loss of production until the problem has been corrected and regular operation is restored. * Traditionally, equipment malfunctions are corrected by +, ** human workers, perhaps with the aid of a maintenance and repair diagnostics subroutine. With the increased use of computer control for manufacturing processes, there is a trend toward using the control computer not only to diagnose the malfunctions but also to automatically take the necessary corrective action to restore the system to normal operation. The term error detection and recovery is used when the computer performs these functions