机械毕业设计英文外文翻译255计算机与制造业

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英语原文

The Computer and Manufacturing

Computer Aided Design

The computer is bringing manufacturing into the Information Age. This new tool, a long familiar one in business and management operations, is moving into the factory, and its advent is changing manufacturing as certainly as the steam engine changed it 100 years ago.

The basic metal working processes are not likely to change fundamentally, but their organization and control definitely will.

IN one respect, manufacturing could be said to be coming full circle. The first manufacturing could was a cottage industry: the designer was also the manufacturer, conceiving and fabricating products one at a time. Eventually, the concept of the interchangeability of parts was developed, production was separated into specialized functions, and identical parts were produced thousands at a time.

Today, although the designer and manufacturer may not become one again, the functions are being drawn close in the movement toward an integrated manufacturing system,

It is perhaps ironic that, at a time when the market demand a high degreed of product diversification, the necessity for increasing productivity and reducing costs is driving manufacturing toward integration into a coherent system, a continuous process in which parts do not spend as much as 95% of production time being moved around or waiting to be worked on.

The computer is the key to each of these twin requirements. It is the only tool that can provide the quick reflexes, the flexibility and speed, to meet a diversified market. And it is the only tool that enables the detailed analysis and the accessibility of accurate data necessary for the integration of the manufacturing system.

It may well be that, in the future, the computer may be essential to a company’s survival. Many of today’s businesses will fade away to be replaced by more-productive

combinations.

Such

more-productive

combinations

are

super-quality, super-productivity plants. The goal is to design and operate a plant that would produce 100% satisfactory parts with good productivity.

A sophisticated, competitive world is requiring that manufacturing begin to settle for more, to become itself sophisticated, To meet competition, for example, a company will have to meet the somewhat conflicting demands for greater product diversification, higher quality, improved productivity, and low prices.

The company that seeks to meet these demands will need a sophisticated tool, one that will allow it to respond quickly to customer needs while getting the most out of its manufacturing resources.

The computer is that tool.

Becoming a “super-quality, super-productivity” plant requires the integration of an extremely complex system. This can be accomplished only when all elements of manufacturing—design, fabrication and assembly, quality assurance, management, materials handling—are computer integrated.

In product design, for example, interactive computer-aided-design (CAD) systems allow the drawing and analysis tasks to be performed in a fraction of the time previously required and with greater accuracy. And programs for prototype testing and evaluation further speed the design process.

In manufacturing planning, computer-aided process planning permits the selection, from thousands of possible sequences schedules, of the optimum process.

On the shop floor, distributed intelligence in the form of microprocessors controls machines, runs automated loading and unloading equipment, and collects data on current shop conditions.

But such isolated revolutions are not enough. What is needed is a totally automated system, linked by common software from front door to back.

The benefits range throughout the system. Essentially, computer integration provides widely and instantaneously available, accurate information, improving communication between departments, permitting tighter control, and generally enhancing the overall quality and efficiency of the entire system.

Improved communication can mean, for example, designs that are more producible. The NC programmer and the tool designer have a chance to influence the product designer, and vice versa.

Engineering changes, thus, can be reduced, and those that are required can be handled more efficiently. Not only does the computer permit them to be specified

more quickly, but it also alerts subsequent users of the data to the fact that a change has been made.

The instantaneous updating of production-control data permits better planning and more0effective scheduling. Expensive equipment, therefore, is used more productively, and parts move more efficiently through production, reducing work-in-process costs.

Product quality, too, can be improved. Not only are more-accurate designs produced, for example, but the use of design data by the quality-assurance department helps eliminate errors due to misunderstandings.

People are enabled to do their jobs better. By eliminating tedious calculations and paperwork—not to mention time wasted searching for information—the computer not only allows workers to be more productive but also frees them to do what only human beings can do: think creatively.

Computer integration may also lure new people into manufacturing. People are attracted because they want to work in a modern, technologically sophisticated environment.

In

manufacturing

engineering,

CAD/CAM

decreases

tool-design.

NC-programming, and planning times while speeding the response rate, which will eventually permit in-house staff to perform work that is currently being contracted out.

According to the Tool & Manufacturing Engineers Handbook, process planning is the systematic determination of the methods by which a product is to be manufactured economically and competitively. It essentially involves selection, calculation, and documentation. Processes, machines, tools, and sequences must be selected. Such factors as feeds, speeds, tolerances, dimensions, and costs must be calculated. Finally, documents in the form of setup instructions, work instructions, illustrated process sheets, and routings must be prepared. Process planning is an intermediate stage between designing and manufacturing the product. But how well does it bridge design and manufacturing?

Most manufacturing engineers would agree that, if ten different planners were asked to develop a process plan for the same part, they would probably come up with ten different plans. Obviously, all these plans cannot reflect the most efficient manufacturing methods, and, in fact, there is no guarantee that any one of them will constitute the optimum methods for manufacturing the part.

What may be even more disturbing is that a process plan developed for a part during a current manufacturing program may be quite different manufacturing program and it may never be used again for the same or similar part during a previous similar part. That represents a lot of wasted effort and produces a great many inconsistencies in routing, tooling, labor requirements, costing, and possibly even purchase requirements.

Of course, process plans should not necessarily remain static. As lot sizes change and new technology, equipment, and processes become available, the most effective way to manufacture a particular part also changes, and those changes should be reflected in current process plans released to the shop.

A planner must manage and retrieve a great deal of data and many documents, including established standards, machine ability data, machine specifications, tooling inventories, stock availability, and existing process plans. This is primarily an information-handling job, and the computer is an ideal companion.

There is another advantage to using computers to help with process planning. Because the task involves many interrelated activities, determining the optimum plan requires many iterations. Since computers can readily perform vast numbers of comparisons, many more alternative plans can be explored than would be possible manually.

A third advantage in the use of computer-aided process planning is uniformity. Several specific benefits can be expected from the adoption of computer-aided process-planning techniques:

● Reduced clerical effort in preparation of instructions. ● Fewer calculation errors due to human error.

● Fewer oversights in logic or instructions because of the prompting capability available with interactive computer programs.

● Immediate access to up-to-date information from a central database. ● Consistent information, because every planner accesses the same database. ● Faster response to changes requested by engineering of other operating departments.

● Automatic use of the latest revision of a part drawing.

● More-detailed, more-uniform process-plan statements produced by word processing techniques.

● More-effective use of inventories of tools, gages, and fixtures and a