成组技术外文文献翻译、机械加工工艺方面外文翻译、中英文翻译

外文原文： Group Technology Group technology (GT) is a very important methodology in todays manufacturing significant. The reason for this is that group technology, when utilized to its fullest extent, can affect most areas of manufacturing, including design, process planning, scheduling, routing, factory layout, procurement, quality assurance, machine tool utilization, tool design, producibility engineering, and assembly. 1 Introduction Group technology is a simple concept that is used widely in various forms. For a variety of reasons, it is logical to collect and associate things based on features that they have in common. This approach is familiar to everyone for plants, animals, and chemicals. Such organizational structures have also been used for hardware and other obviously similar products within the manufacturing world. Group technology represents structured categorization of particular value to the manufacturing community. It is already widely used； perhaps 50% of manufacturing companies use some form of GT. Bath or lot production suffers from many inefficiencies due to part variety and the general-purpose nature (flexibility requirements) of machine tools in use on the shop floor. In fact, a Cincinnati Milacron study showed that 95% of the time a part spends on the shop floor is idle time, the other 5% is divided between setup and teardown of the machine tool. The future breakdown of the 5% of on-machine time was developed by Dunlap. Based on this estimate, only 24% of the 5% is time which actually involves cutting； i.e., parts are being machined during only 1.2% of the total time spent in manufacturing. Group technology makes possible the application of several methods of analysis which assist in making batch production more efficient by reducing part variety via part families and improving throughout and work-in-process inventory. It is for this reason that group technology is becoming a key concept in manufacturing. 2 Definition Manufacturing philosophy to some, fundamental building block for more efficient production to most, group technology is a simple concept which utilizes/exploits similarities for more efficient production in bath manufacturing. Group technology usually classifies parts in the form of a code which is assigned to each part based on its shape or production processing characteristics. In use, coding parts assists in the control of planning and processing. This added control, which exploits similarities, leads to economies in the overall manufacturing process. The actual operator on the shop floor may never know this code, but designers, engineers, and planners find it an invaluable tool, allowing them to do more productive and useful analysis. 3 General Benefits In practice, group technology is really nothing more than an information/indexing system. However, because of its focus on part design and processing similarities, analysis is possible which creates manufacturing economies of scale, encourages standardization, and eliminates duplication in design and process planning. Mass production enjoys the benefits of what are called economies of scale. Economies of scale achieved by processing a large number of parts over the same workstations or equipment. This result in less labor per part, more efficient machine utilization, and a faster turnover of inventory. Batch production in the past has not enjoyed economies of scale because of the need to remain flexible for changing part types and products. However, by grouping parts into families based on their similarities, much of the manufacturing processing of these parts can be done on entire families. This increases the number of parts processed with the same equipment conditions, thereby permitting some of the economies of scale of mass production. Standardization is achieved in both design and part process planning. Essentially, group technology creates an efficient design retrieval system since parts have been code based on shape. Similar design are located quickly and aspects such as part tolerances and producibility can be better understood, more easily applied, and kept more consistent from design to design. When standardized process planes are developed and include in the group technology code, new parts and repeat orders can follow similar processing routes through the shop floor, simplifying scheduling and flow through the shop. Group technology eliminates duplication. In both design and process planning, there is much les “reinventing of the wheel” since there is sufficient retrieval of standard designs and process plans. 4 Application of GT in Process Planning Although many areas of business operation can benefit from GT, manufacturing, the original application area, continues to be the place where GT is most widely practiced. Two important tasks in manufacturing planning and manufacturing engineering are scheduling and process planning. Job scheduling sets the order in which parts should be processed and can determine expected completion times for operation and orders. Process planning, on the other hand, decides the sequence of machines to which a part should be routed when it is manufactured and the operations that should be performed at each machine. Process planning also encompasses tool, jig, and fixture selection as well as documentation of the time standards (run and setup time) associated with each operation. Process planning can directly affect scheduling efficiency and, thus, many of the performance measures normally associated with manufacturing planning and control. Some of the largest productivity gains have been reported in the creation of process plans that determine how a part should be produced. With computer-aided process planning (CAPP) and GT it is possible to standardize such plans, reduce the number of new ones, and store, retrieve, edit, and print them out very efficiently. Process planning normally is not a formal procedure. Each time a new part is designed, a process planner will look at the drawing and decide which machine tools should process the parts, which operations should be performed, and in what sequence There are two reasons why companies often generate excess process plans. First, most companies have several planners, and each may come up with a different process plan for the very same part, Second, process； planning is developed with the existing configuration of machine tools in mind. Over time, the addition of new equipment will change the suitability of existing plans. Rarely are alterations to old process plans made. One company reportedly had 477 process plans developed for 523 different gears. A close look revealed that more than 400 of the plans could be eliminated. Process planning using CAPP can avoid these problems. Process planning with CAPP takes two different forms； With variant-based planning, one standardized plan (and possibly one or more alternate plans) is created and stored for each part family. When the planner enters the GT code for a part, the computer will retrieve the best process plan. If none exists, the computer will search for routings and operations for similar parts. The planne r can edit the scheme on the CRT screen before printout. With generative planning, which can but does not necessarily rely on coded and classified parts, the computer forms the process plan through a series of questions the computer poses on the screen. The end product is also a standardized process plan, which is the best plan for a particular part. The variant-based approach relied on established plans entered into the computer memory, while the generative technique creates the process plans interactively, relying on the same logic and knowledge that a planner has. Generative process planning is much more complex than variant-based planning； in fact, it approaches the art of artificial intelligence. It is also much more flexible； by simply changing the planning logic, for instance, engineers can consider the acquisition of a new machine tool. With the variant-based method, the engineers must look over and possibly correct all plans that the new tool might affect. CAPP permits creation and documentation of process plans in a fraction of the time it would take a planner to do the work manually and vastly reduces the number of errors and the number of new plans that must be stored. When you consider that plans normally are handwritten and that process planners spend as much as 30% of their time preparing them, CAPPS contribution of standardized formats for plans and more readable documents is important. CAPP, in effect, functions as advanced text editor. Furthermore, it can be linked with an automated standard data system that will calculate and record the run times and the setup times for each operation. CAPP can lead to lower unit costs through production of parts in an optimal way. That is, cost savings come not only via more efficient process planning but also through reduced labor, material, tooling, and inventory costs. GT can help in the creation of programs that operate numerically (NC) machinery, n area related to process planning. For example, after the engineers at Otis Engineering had formed part families and cells, the time to produce a new NC tape dropped from between 4 and 8 hours to 30 minutes. The company thereby improved the potential for use of NC equipment on batches with small manufacturing quantities. 编 者：吴非晓等 机械英语 2 外语教学与研究出版社 2002.7 译文： 成组技术 在当今的制造环境下，尤其是对批量生产来说，成组技术（ GT）是一个很重要的生产方式而且它正变得越来越重要。其原因在于，当成组技术发挥最大作用的时候，能够影响大多数的制造领域，其中包括设计、工艺规划、调度、路线、工厂布局、采购、质量保证、车床应用、刀具设计、生产 能力设计及组装。 1 简介 成组技术是一个以各种形式广泛应用的简单概念。基于各种原因，我们有理由根据事物的共同特征把它们收集并联系在一起。对于植物、动物和化合物来说，每个人都很熟悉这种方法。在制造业内，这种组织结构也被用于硬件和其它明显相似的产品中。成组技术对于生产团体来说，代表着具有具体价值的组织分类。它早就被广泛应用，大约有 50%的生产企业在使用某种形式的成组技术。 由于零件多种多样以及生产车间使用的车床的通用特性（灵活性要求），造成了批量和规模生产效率差的情况很多。一份辛辛那提麦尔克伦的研究表明，实际 上一个零件花费在生产车间的时间有 95%是闲置的，另外 5%的时间在车床的装配和拆卸之间进行分配。 Dunlap对这 5%的机上时间进一步的分解进行了研究。据此估计， 5%的机上时间中只有 24%的时间用于切割。也就是说，只有 1.2%的总时间用于零部件的加工。成组技术能够利用几中不同分析的方法，通过零件族来减少零件的种类，从而使批量生产更具有效率，提高生产能力并缓解加工过程的库存问题。正是由于这个原因，成组技术才在生产中成为一个至关重要的概念。 2 定义 成组技术在某种程度上是一种生产观念，而在很大程度上是高效率生产的 基本构件，它是一个简单的概念，它在批量生产过程中利用或使用相似性提高制造效率。成组技术通常利用代码将零件分类。代码是根据零件的形状或生产过程的特征分配给每个零件的。使用中，代码零件有助于对规划和加工的控制。这种利用相似性的附加控制能给整个生产过程带来许多经济效益。车间里的实际操作者可能永远也不知道这个代码，但是设计者、工程师和规划人员把它当成一种最宝贵的工具，能够使他们进行更加有用和富有成效的分析。 3 益处 实际上，成组技术其实就是一个信息或索引系统。然而，由于它着眼于零件设计和加工的相似性就有可能进行分 析，规模生产的经济效益，促进标准化并避免重复设计和工艺规划。 批量生产有利于规模经济。规模经济效益通过用同一车间或设备加工大量零件来实现。这意味着每个零件所用劳动力较少，机械利用率更高，库存周转更快。过去的批量生产并没有获得规模生产的经济效益，原因在于需要保持灵活性来更换零件的种类和产品。然而，通过根据相似性对零件进行分组，在整个族内就可以完成这些零件的大部分生产加工。这就增加了同一个生产设备条件下加工零件的数量，因此就能带来规模生产所追求的一些经济效益。 标准化是在设计和零件工艺规划中完成的。重要的是，由 于零件根据形状被编码，成组技术提供了一个有效率的设计检索系统。相似的设计很快就能找到，一些诸如零件公差和可制造性问题得到了更好的解决，利用更方便，而且从设计到设计都保持一致性。一旦制定了标准化的工艺规划并被编入成组技术代码中，新零件和重复命令就能通过生产车间在相似的加工路线上运行，简化了车间的计划和流程。 成组技术减少重复。在设计和加工计划中只有较少的“操纵轮的重新设定”，因为有足够的标准化的设计和工艺规程供检索。 4 成组技术在工艺规划中的应用 虽然很多商业领域可以从成组技术中获益，但是制造这一 GT最初的 应用领域仍然是 GT 最为广泛实践的地方。制造计划与制造工程的两个重要任务是调度和工艺规划。作业调度安排零件所加工的流程，并可确定工序期望完成的时间和流程；在另一方面，工艺规划决定了零件制造时所应发送的机器流程以及在每台机器上所应完成的工序。工艺规划还包括刀具、夹具和定位器的选择以及有关每道工序的时间标准（运转时间与准备时间）的文件编制。工艺规