1、外文翻译 英文原文： Flexible Manufacturing System A logical step from the concepts of group layout and of NC machine tools and robotics are computer-controlled interlinked outstation machining complexes, or 11exibe manufacturing systems(FMS)as they have bedclothes call.do.Such systems can be looked upon as h
2、ighly automated cells manufacturing families of components. The concept of FMS is not a new one； the first proposals were made in the mid 1960s. In recent years we have seen a growth in the number of systems, particularly in Japan, such that it is estimated that in excess of a hundred systems have b
3、een installed worldwide. A flexible manufacturing system contains a number of features as follows: 1. Interlinked NC workstations operating on a limited range or family of work pieces. In early propos-ales the machines were of modular construction, but in recent systems general-purpose NC machines,
4、in particular machining centers, are most commonly used. 2. Automatic transportation, loading at unloading of work pieces and tools, using automatic guided vehicles (AGVs), robots,etc. 3. Work pieces mounted on pallets ft* transportation, pattly to overcome the problems of new setups at each worksta
5、tion. 4. Centralized NC or DNC, together with overall computer control of the system. 5. Operation for significant periods of time with little or no manual intervention. With FMS the tern flexibility means the ability to aptness a variety of components without having to adjust machine setups. Or cha
6、nge tooling. High flexibility implies that a large family of different components can be produced by the particular system. Figure 5. 17 show that several variants of the basic FMS con-kept exist. These are； l.Flexible manufacturing cells(FMs): These are basically machining centum but with the addit
7、ion of a pallet pool or magazine(Fig.5. t8 ).The aim is to machine the work piece with one stupefies type of machine can be operated unmanned for long periods of time, with the palletized work pieces transformed au-somatically to and from the machine. Flexible manufacturing cells of this type must b
8、e served by machines or operators engaged in blank preparation and polarization of work pieces. These cells are highly flexible in operation, having the ability to deal with a wide range of pats (40 to 800), in small batches of from 15 to 500. 2. Flexible transfer lines (fall): These, systems consis
9、t of a number of NC or head-changeable ma chine tools connected by automatic material transfer systems. The system can machine different components but without flexible routing of the workpieces.The family of components is relatively small ( 20) and the components must be quite similar to one anothe
10、r, as the overall flexibility of tote system is too low for a larger variety to be accommodated. In consequence, the work cycles at each station nulls are quite well balanced. Production quantities must be quite large for economic use of these system (1 500 to 15000 per annum for each component). 3.
11、 Flexible manufacturing systems (FMS), in these systems NC workstations are linked by automatic work piece transfer and handing. With flexible routing and automatic work piece loading and unloading. A-chining times at each station can differ considerably. The number of different components that can
12、be pro-cussed by these systems is ohm 10 o 150 in general and moderate quantities can be produced (15 to 500 components per annum for type) 1 Work Handling for FMS Work pieces are usually mounted on standard pallets for processing in FMS and these pallets locate automatically at each workstation in
13、the system. A variety of work-handling devices are used to transport parts, pallets, and tools around the system. Some of these ate as follows: 1. Tow carts: These are the most cannon devices used； they consist of a simple platform on castors and are towed around the system by engagement with under
14、floor, continuously moving chains. Cats stop at workstations by means of a mechanism total releases the tow pin at the appropriate time. Branches and loops are canalled in a similar manner to railway systems. 11te main advantage of tow carts is their simplicity and low cost, since no on-board power
15、is required for their movement or control. Facilities must beavailable at each workstation to load and unload pallets from the carts. Also, the circulation of carts must be unidirectional. 2. Automatic guided vehicles (AGVs). These devices are usually designed to follow wins buried in the floor of t
16、he plant or lines painted on tote floor. On-board power and control is required for bolt move mint and steering ate for tote handling of pallets. Automatic guided vehicles ate more expensive than tow cats and are both larger and heavier. Tale main advantage of AGVs is their greater flexibility of op
17、era-ton. These devices may move in either direction, but for ease of control, circulation is usually restricted to one direction only in practice. 3. Rail cats: These carts move on rails and are generally restricted to backward and forward motion along straight tracks. Power and control instructions
18、 ate ttunsferred by overhead conductors or extra rails.Rail carts often accommodate two pallets to allow for pallet exchange at the system workstations. 4. Roller conveyors: Most of tote early FMS developments utilized powered-roller conveyors for moving work pieces from statuette to station. The us
19、e of these convents in modern systems is less common.Roller conveyors are expensive to install and occupy valuable floor space. In addition, these conveyors are relatively inflexible in operation and difficult to alter if the overall system is expanded. 5. Industrial robots: Robots are used in FMS b
20、ut not extensively unless the cell consists of only a few machines. They may be used as second at) handling devices, particularly for turned work pieces, which may be transported around the system in hatches on pallets by other handling devices and then transferred to the machine tool by robots at e
21、ach workstation. Gripper designs suitable for handling a wide variety of components are important in this case. 2 Layouts for FMS A variety of different layouts for the machine tools in FMS have been adopted, The choice depends on the scope of the system and the type of handling devices used for tra
22、nsporting work pieces from workstation to workstation. The use of rail carts mean that a straight track must be used, with machines located at the side of tote track. Early systems using roller conveyors usually employed a simple loop configura-tio11, with branches to the workstations. The increased
23、 use of tow carts and AGVs has resulted in more complex multicolor or tree-type layouts being used. The latter type is most suitable for AGVs and is particularly useful if expansion of the system with additional workstations is anticipated. Figure 5.19 shows a typical multicolor layout using tow car
24、ts, and Fig.5.20 shows a typical layout where AGVs are used for work handling. 3 Factory of the Future On the basis of the advances made to date in all aspects of manufacturing technology and computer controls, we may envisage the factory of the future as a fully automated facility in which human be
25、ings would not be directly involved with production on the shop i1oor (hence the term unmanned factories).All manufacturing, material handling, assembly, and inspection would be done by automated and computer-controlled machinery and equipment. Similarly, activities such as processing incoming order
26、s, production planning and scheduling, cost accounting, and various decision-making processes (usually performed by management) would also bedone automatically by computers. The role of human beings would be confined to activities such as supervising, maintaining (especially preventive maintenance),
27、 and upgrading machines and equipment； ship-ping and receiving supplies and finished products ； providing security for the plant facilities ； and programming, upgrading, and monitoring computer programs, and monitoring, maintaining, and upgrading hard-ware. Industries such as some food, petroleum, a
28、nd chemical already operate automatically with little human intervention. These are continuous processes and, unlike piece part manufacturing, are easier to automate fully. Even so, the direct involvement of fewer people in manufacturing products is already apparent: Surveys show that； only 10-15 pe
29、rcent of the workforce is directly involved in production. Most of the workforce is involved in gathering and processing information. Virtually unmanned manufacturing cells already make products such as engine blocks, axles, and housings for clutches and air compressors .For large-scale, flexible ma
30、nufacturing systems, however, highly trained and skilled personnel will always be needed to plan, maintain, and oversee operation. The reliability of machines, control systems, and power supply is crucial to full factory automation. A local or general breakdown in machinery, computers, power, or communications networks will, without rapid human intervention cripple production.
