外文翻译--模具制造科学

1 英文翻译 The Science of Die Making The traditional method of making large automotive sheet metal dies by model building and tracing has been replaced by CAD/CAM terminals that convert mathematical descriptions of body panel shapes into cutter paths.Teledyne Specialty Equipments Efficient Die and Mold facility is one of the companies on the leading edge of this transformation. by Associate Editor Only a few years ago,the huge steel dies requited for stamping sheet metal auto body panels were built by starting with a detailed blueprint and an accurate full-scale master model of the part. The model was the source from which the tooling was designed and produced. The dies,machined from castings,were prepared from patterns made by the die manutacturers or somethimes supplied bythe car maker.Secondary scale models called” tracing aids” were made from the master model for use on duplicating machines with tracers.These machines traced the contour of the scale model with a stylus,and the information derived guided a milling cutter that carved away unwanted metal to duplicate the shape of the model in the steel casting. All that is changing.Now,companies such as Teledyne Specialty Equipments Effi cient Die and Mold operation in Independence,OH,work from CAD data supplied by customers to generate cutter paths for milling machines,which then automatically cut the sheetmetal dies and SMC compression molds. Although the process is uesd to make both surfaces of the tool, the draw die still requires a tryout and “benching” process.Also, the CAD data typically encompasses just the orimary surface of the tool,and some machined surfaces, such as the hosts and wear pads, are typically part of the math surface. William Nordby,vice president and business manager of dies and molds at Teledyne,says that “although no one has taken CAD/CAM to the point of building the entire tool,it will eventually go in that direction because the “big thrdd”want to compress cycle times and are trying to cut the amount of time that it takes to build the tooling.Tryout, because of the lack of development on the design end,is still a very time-consuming art,and vety much a trial-and-error process.” No More Models and Tracing Aids The results to this new technology are impressive. For example, tolerances are tighter and hand finishing of the primary die surface with grinders has all but been eliminated. The big difference, says Gary Kral, Teledynes director of engineering, is that the dimensional control has radically improved. Conventional methods of making plaster molds just couldnt hold tolerances because of day-to-day temperature and humidity variations.” For SMC molds the process is so accurate , and because there is no spring back like there is when stamping sheet metal, tryouts are not always required.SMC molds are approved by customers on a regulate basis without ever running a part .Such approvals are possible because of Teledynes ability to check the tool 2 surface based on mathematical analysis and guarantee that it is made exactly to the original design data. Because manual trials and processes have been eliminated, Teledyne has been able to consider foreign markets.” The ability to get a tool approved based on the mathe gives us the opportunity to compete in places we wouldnt have otherwise,” says Nordby. According to Jim Church, systems manager at Teledyne, the company used to have lots of pattern makers ,and still has one model maker.” But 99.9 percent of the companys work now is from CAD data. Instead of model makers, engineers work in front of computer monitors.” He says that improvenents in tool quality and reduction in manufacturing time are significant. Capabilities of the process were demonstrated by producing two identical tools. One was cut using conventional patterns and tracing mills, and the other tool was machined using computer generated cutting paths. Although machining time was 14 percent greater with the CAM-generated path, polishing hours were cut by 33 percent. In all ,manufacturing time decreased 16.5 percent and tool quality increased 12 percent. Teledynes CAD/CAM system uses state-of-the-art software that allows engineers to design dies and molds, develop CNC milling cutter paths and incorporate design changes easily. The system supports full-color, shaded three-dimensional modeling on its monitors to enhance its design and analysis capabilities. The CAD/CAM system also provides finite element analysis that can be used to improve the quality of castings , and to analyze the thermal properties of molds. Inputs virtually from any customer database can be used either directly or through translation. CMM Is Critical Teledynes coordinate measuring machine(CMM),says Church,”is what has made a difference in terms of being able to move from the traditional manual processes of mold and die making to the automated system that Teledyne uses today.” The CMM precisely locates any point in a volume of space measuring 128 in, by 80 in, by 54 in, to an accuracy of 0.0007 in. It can measure parts, dies and molds weighing up to 40 tons. For maximum accuracy,the machine is housed in an environmentally isolated room where temperature is maintained within 2 deg.F of optimum. To isolate the CMM from vibration, it is mounted on a 100-ton concrete block supported on art cushions. According to Nordby, the CMM is used not only as a quality tool, but also as a process checking tool. “ As a tool goes through the shop, it is checked several times to validate the previous operation that was performed.” For example, after the initial surface of a mold is machined and before any finish work is done, it is run through the CMM for a complete data check to determine how close the surface is to the required geometry. The mold is checked with a very dense pattern based on flow lines of the part. Each mold is checked twice, once before benching and again after benching. Measurements taken from both halves of the mold are used to calculate theoretical stock thickness at full closure of the mold to verify its accuracy with the CAD design data. Sheet Metal Dies Are Different 3 “Sheet metal is a different ballgame,” says Nordby, “because you have the issue of material springback and the way the metal forms in the die. What happens in the sheet metal is that you do the same kinds of things for the male punch as you would with SMC molds and you ensure that it is 100 percent to math data. But due to machined surface tolerance variations, the female half becomes the working side of the tool. And there is still a lot of development required after the tool goes into the press. The math generated surfaces apply primarily to the part surface of the tool.” EMS Tracks the Manufacturing Process Teledynes business operations also are computerized and carried over a network consisting of a VAX server and PC terminals. IMS (Effective Management Systems) software tracks orders, jobs in progress, location of arts, purchasing, receiving, and is now being upgraded to include accounting functions. Overall capabilities of the EMS system include bill-of-material planning and control, inventory management, standard costing, material history, master production scheduling, material requirements planning, customer order processing, booking and sales history, accounts receivable, labor history, shop floor control, scheduling, estimating, standard routings, capacity requirements planning, job costing, purchasing and receiving, requisitions, purchasing and receiving, requisitions, purchasing history and accounts payable. According to Frank Zugaro, Teledynes scheduling manager, the EMS software was chosen because of its capabilities in scheduling time and resources in a job shop environment. All information about a job is entered into inventory management to generate a structured bill of material. Then routes are attached to it and work orders are generated. The system provides daily updates of data by operator hour as well as a material log by shop order and word order. Since the database is interactive, tracking of materials received and their flow through the build procedure can be documented and cost data sent to accounting and purchasing. Gary Kral, Teledynes director of engineering, says that EMS is really a tracking device, and one of the systems greatest benefits is that it provides a documented record of everything involving a job and eliminates problems that could arise from verbal instructions and promises. Kral says that as the system is used more, they are finding that it pays to document more things to make it part of the permanent record. It helps keep them focused. 4 模具制造科学 传统的通过制造模具加工大 型板材的方法已经被可以把实体的形状信息转换为切削路径的CAD/CAM 所取代了。这个专门的高效的灵活的公司就是这种转换技术前言的一部分。 在几年以前，大型的需要自动送料的巨大金属模具在详细的蓝图上和一个准确的全面的模形上开始建造，这个模形是工具被设计和生产的起源。 模具是由浇铸转化来的，它由模形制造演化而来，而且由模具制造商和汽车生产商赞助。第二种类型的模型叫做路线辅助追踪，他由替代追踪的模型发展而来，这些机器用探头扫描机器的轮廓，所获得的信息控制加工机切去不需要的金属以便复制模型。 现在所有这些都被改变了， 现在像 TSEED 这类大公司独立运作，用客户提供的 CAD 数据产生加工机的加工路线，用于自动加工板材模和 SMC 复合材料。 虽然这个工艺只被应用于加工工件的俩个表面，但模具还需要一个实验过程，而且， CAD 数据只包含工件原始表面的数据和像垫圈这类的机加工过的表面和一些数学模型的部分。 威廉是在泰勒德尼的模具制造工业的代主官，他说“虽然没人把 CAD/CAM 用于制造所有工件，但他终将向这个方向发展，因为三巨头要压缩循环时间而且试图减少制造工具的时间。因为缺少向设计结果的发展，试验仍然是一向非常费时间的工作，也是一个不断 改进的过程。 不再需要模型和辅助追踪 这项技术的结果是令人振奋的。举个例子，公差过于苛刻使得手工加工模具表面是无论如何也无法完成的。格尔说，最大的不同在于泰勒迪尼的工程师的空间控制被很快的发展了。传统的加工塑料模具的发发不能满足公差的要求，这是因为气温的不同和人为地差别。 对于 SMC，制造过程是如此的精确以至于试验有时候可以省略，因为在定位板材的时候没有滑移。SMC 技术已经在没有进行任何运行基础的情况下被客户所证实了。这些人同时可能的，因为泰勒迪尼公司有能力在数学分析的基础上检查这些工件的表面并保证是按照原 始的设计数据设计的。 因为人工的操作和工艺被排除了，泰勒迪尼能够考虑海外市场，在数学基础上制造工具的能力是我们有机会在以前没有涉及的领域发展，盖瑞说。 据泰勒德尼的系统主管吉姆说，公司以前有许多图案设计师和一个模型设计师。但现在 99.9%的公司业务是由 CAD 进行的。代替了以前的模型设计师，现在工程师们在电脑显示器前面工作。 他说，在工件质量的提高和生产时间的缩短是至关重要的。工艺的能力已经被生产俩个完全一样的工件所证明。一个是使用传统的加工图案的追踪方法而另一个是用计算机产生的路径进行加工。虽然机加工时间后 一种方法只领先 14%，但是磨光时间减少了 33%。总之，生产时间减少了 16.5%，工件的质量提高了 12%。 泰勒德尼的 CAD/CAM 系统使用了阶段操作软件，是工程师们可以设计模具，研究 CNC 切削路径，并方便的改变设计。系统支持所有颜色，可以在显示器上产生三维模型以增强效果，还有分析功能。CAD/CAM 系统也提供有限单元分析，这可以提高加工质量和分析加工的主要特征