2QY4.8-17蒸汽泵汽缸机械加工工艺及工装设计-镗孔夹具含5张CAD图
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中英文资料RP&M 1. What is RP&MManufacturing community is facing two important challenging tasks:(1)substantial reduction of product development time; and (2) improvement on flexibility for manufacturing small batch size products and a variety of types of products. Computer-aided design and manufacturing(CAD and CAM) have significantly improved the traditional production design and manufacturing. However, there are a number of obstacles in true integration of computer-aided design with computer-aided manufacturing for rapid development of new products. Although substantial research has been done in the past for computer-aided design and manufacturing integration, such as feature recognition, CNC programming and process planning, the gap between CAD and CAM remains unfilled in the following aspects:rapid creation of 3-D models and prototypes.cost-effective production of patterns and moulds with complex surfaces.To substantially shorten the time for developing patterns, moulds, and prototypes, some manufacturing enterprises have started to use rapid prototyping(RP)methods for complex patterns making and component prototyping. Over the past few years, a variety of new rapid manufacturing technologies, generally called Rapid Prototyping and Manufacturing(RP&M), have emerged; the technologies developed include Stereolithography(SL), Selective Laser Sintering(SLS), Fused Deposition Modeling(FDM), Laminated Object Manufacturing(LOM), and Three Dimensional Printing(3-D Printing). These technologies are capable of directly generating physical objects from CAD databases. They have a common important feature: the prototype part is produced by adding materials rather than removing materials, that is, a part is first modeled by a geometric modeler such as a solid modeler and then is mathematically sectioned(sliced)into a series of parallel cross-section pieces. For each piece, the curing or binding paths are generated. These curing or binding paths are directly used to instruct the machine for producing the part by solidifying or binding a line of material. After a layer is built, a new layer is built on the previous one in the same way. Thus , the model is built layer by layer from the bottom to top. In summary, the rapid prototyping activities consist of two parts: data preparation and model production.2.The history of RP&M As usual with invention, one individuals impatience was the prototyping industry, now barely a decade old. Its father, Charles W Hull, 58 , still works as vice chairman and chief technology officer at the RP company he helped found in 1986, 3D Systems of Valencia, Calif. As an engineer, Hull had always been bothered by the long time it took to make prototype models of plastic. They had to be machined by hand, he recalls. If more than one was needed, generally the case in industry, molds for making plastic prototypes had to be individually machined.The building blocks of a better system were lying around. Hull had been working for a small company that used ultraviolet lamps to substitute a laser for an ultraviolet lamp. “But taking that insight to a practical machine came slowly,” Hull recalls, and required several years of Edison-style inspiration. (In fact, a prototyping machine based on conventional UV light was developed in 1998 by The Institute of Advanced Manufacturing Technology, Xian Jiaotong University, China).The results was the first prototyping machine, introduced by 3-D Systems in 1987. It could fabricate small, transparent plastic parts from CAD drawings in hours or at most days. The machine builds the model in layers, from the bottom up. A laser, which causes molecules of a photosensitive liquid resin to polymerize, scans above a vessel filled with the resin. The laser first traces the outline of a layer on the resins surface. Next, like an artist shading a panel in a pencil drawing, the beam crisscrosses the whole outlined area to harden it. Then the platform holding the model sinks so the layer is barely awash in liquid resin, the laser goes to work solidifying another layer atop it, and so on. When the translucent object is done, it is raised from the vat, dripping like a mermaid just emerged from the sea.Hull dubbed the process stereolithography, and it still dominates RP. The resins were, and still are very expensive: A gallon of acrylic blends of photo-curable liquids fetches about $750. But so great is industrys hunger for prototypes, in an era when the pool of high-paid artisans who can make them by hand is shrinking and time to market is king, that designers were glad to get the first RP machines at any price. 3-D Systems has grown to an $80-million-a-year public company thats still No.1 in the field by far.Before long other inventors jumped in. Michael Feygin, an immigrant Russian engineer, hit on the idea of building prototypes from inexpensive slices of paper. His company, Helisys of Torrance, Calif., makes remarkably sturdy objects by a process called laminated-object manufacturing(LOM).A blue CO2 laser traces each layer by burning, moving like a crazed ice dancer carving a turn here, a straight line there. Successive layers are bonded by adhesive. Helisys, whose machines have modeled auto steering wheels, bumpers, and other shapes that feel like wood to the touch, is a 12-million-a-year public company.Meanwhile, a group of MIT inventors led by Emanuel Sachs, a slender, unassuming professor of mechanical engineering, chafed at the RP industrys inability to make prototype, as well as molds and production parts, from ceramics and metal. The early RP machines could make a metal prototype only in a roundabout way. First a plastic model had to be “invested”, or clad in a heat-resistant material such as a ceramic. Then the model was “sacrificed” by melting, just as the ancient Egyptians melted a wax model inside a mold to clear the way for a bronze casting. This leaves a mold suitable for making a metal or plastic prototype. Why not skip that stage, Sachs asked, and make sturdy parts directly from CAD designs? He and his 30-person shop at MIT have become the leaders in a branch of RP based on the same technique enabling computer printers to produce documents by squirting ink through jets. Instead of ink, MITs RP machines squirt a binder on layers of powdered steel, ceramics, or even starch that are spread by rollers.The machines to which Sachs idea has given birth, called 3-D printers, are fairly inexpensive by RP standards, with low-end versions in the $50,000 range. The bigger 3-D printers are only now realizing Sachs goal of making commercially usable metal objects and molds directly from CAD designs. Soligen, a Northridge, Calif., company founded in 1992 by expatriate Israeli engineer Yehoram Uzirl, has developed, under license from MIT, the ink-jet machine Specific Surface employed to make those ceramic filters. On its machines, Soligen also makes ceramic molds, directly from CAD drawings, suitable for casting metal automotive parts that are as strong as those used in commercial products and suitable for testing and small production runs.Soligens process still has limitations. The ceramic molds are made in one piece and can only be used once, since they must be destroyed to get at the part. But Soligen can make lots of molds quickly as needed. Many RP users, eager to go further, want rapidly made molds that can be used over and over for mass production. That would shrink the manufacturing middle some more, bypassing a conventional process in which a long-lasting mold is carefully carved out of a block of high-grade steel with CNC and other machines, then painstakingly finished by hand, a process that can take months.Quickly made reusable molds, which put RP squarely in rapid-manufacturing territory, have started to appear. When Rubbermaid Office Products of Maryville, Tenn., got an urgent order in 1996 from Staples, the office-products chain, for a small plastic stand that holds sheets of paper vertically, Rubbermaid went to an RP service bureau in Dallas that had a machine made by DTM of Austin, Texas. The ten-year-old company, whose initials stand for “desk top manufacturing,” has developed a sintering process in which loosely compacted plastic are heated by a laser to combine with powdered steel, layer after layer, into a solid mass.The DTM machine speedily produced a metal mold from which Rubbermaid was able to make more than 30,000 plastic stands for staples, priced at $3. Says Geoff Smith-Moritz, editor of the newsletter Rapid Prototyping Report in San Didgo:“ Though not very impressive looking, this product is a pioneer. More and more molds are being made this way.”In its purest form, rapid manufacturing would eliminate molds: Machines would fabricate products directly from CAD designs. Extrude Hone, a company in Irwin, Pa., is getting ready to market a machine, based on MITs ink-jet technology, that will make not only metal molds but also salable metal parts. In Extrude Hones machine, powdered steel is hardened with a binder and infiltrated with bronze powder to create a material that is 100% metal.Powerful new laser may also open doors to direct manufacturing. Such laser systems are being explored at national laboratories such as Sandia and Los Alamos, as well as at the University of Michigan, Penn State, and elsewhere. They may soon be available commercially. In the Sandia system, a 1,000-watt neodymium YAG(yttrium-aluminum-gallium)laser melts powdered materials such as stainless and tool steels, magnetic alloys, nickel-based superalloys, titanium, and tungsten in layers to produce the final part. The process is slow: three hours to make a one-cubic-inch object. But the part is just as metallically dense as one made by conventional means. Sandia vic president Robert J. Eagan says the labs researchers hope to see the process used to make replacement parts for the militarys stored nuclear weapons. Commercial interest is high too. Ten companies, including AlliedSignal and Lockheed Martin, are participating in the program. Another 20 companies support research at Penn State, where the goal is to make big objects, such as tank turrets and portions of airplanes, as a single part.Some experts look to a manufacturing future extensively liberated from todays noisy, hot routines. Instead of molds and machine tools, these visionaries foresee rows of lasers building parts, 3-D printers fashioning convoluted shaped no CNC machine can carve, and silent ceramic partsmakers replacing the traditional noisy factory din. Many products turned out in future factories could be designed to take advantage of rapid-manufacturing techniques. Implantable drug-release devices, with medicine sealed in, could be made in a single operation, since 3-D printers can make a sandwich-like product.Manufacturing pioneers find such possibilities intoxicating.“We could have naval ships carry not an inventory of parts but their images digitized on a 3.5-inch diskette, plus a bag of powdered metal and a rapid manufacturing machine,”says 3-Ms Marge Hartfel.Adds Brock Hinzmann, director of technology assessment at SRI International:“In two or three years rapid manufacturing will be on everybodys lips.”In the meantime, the feats of fast prototyping are giving the factory folks plenty to talk about.3. Current application areas of RP&MAlthough RP&M technologies are still at their early stage, a large number of industrial companies such as Texas Instruments, Inc., Chrysler Corporation, Amp Inc. and Ford Motor Co. have benefited from applying the technologies to improve their product development in the following three aspects.(1)Design engineering 1)Visualization. Conceptual models are very important in product design. Designers use CAD to generate computer representations of their design concepts. However, no matter how well engineers can interpret blue prints and how excellent CAD images of complex objects are, it is still very difficult to visualize exactly what the actual complex products will look like. Some errors may still escape from the review of engineers and designers. The touch of the physical objects can reveal unanticipated problems and sometimes spark a better design. With RP&M, the prototype of a complex part can be built in short time, therefore engineers can evaluate a design very quickly. 2)Verification and optimization. Improving product quality is always a important issue of manufacturing. With the traditional method, developing of prototypes to validate or optimize a design is often time consuming and costly. In contrast, an RP&M prototype can be produced quickly without substantial tooling and labour cost. Consequently, the verification of design concepts becomes simple: the product quality can be improved within the limited time frame and with affordable cost.3)Iteration. Just like the automotive industry, manufacturers often put new product models into market. With RPA&M technology, it is possible to go through multiple design iterations within a short time and substantially reduce the model development time. 快速原型制造和制造业1、RP&M是什么了呢?制造业团体面临着两项重要的富有挑战性的任务:(1) 大量的减少了产品的开发时间; (2)提高了制造小批量产品和各种各样类型的产品的制造业的灵活性。 计算机辅助设计和制造业(CAD和CAM)显著改进了传统生产设计和制造业。然而,为新产品的迅速发展,对于确切地整合计算机辅助设计与计算机辅助生产,有许多的障碍。尽管在过去对计算机辅助设计和制造业整合进行了大量的研究,例如特征识别,CNC编程和处理计划,CAD和CAM之间的空白在以下方面依然是未填充: 三维模型和原型的迅速创作。 有复杂表面的样式和模子的有效成本的生产。极大地缩短了为开发样式,模具和原型的时间,一些制造业企业开始使用快速的原型机制造方法用于制作复杂的样式做和原型机制造组件。在过去几年里,各种各样的新的快速的制造业技术,一般被称作快速原型制造和制造业(RP&M)已经形成了;被开发的技术包括立体平版印刷术(SL),有选择性的激光焊接(SLS),被熔化的沉积物塑造(FDM),分层物体的制造业(LOM)和三维空间打印(三维打印)。这些技术具有直接地从CAD数据库中生成实体的能力。他们有一个共同的重要特点:原型机零件是通过增加材料而不是取消材料来生产的,即,零件首先要被制成几何学的模型,然后被划分成(切成)一系列的平行的短剖面片断。对于每个片断,都要就行红外线固化或是装订路径。这些红外线固化或装订路径通过凝固或是绑定一系列的材料直接地被用来指导生产零部件的机器。在层数被建立之后,新的层数将会以相同的方式早先被建立。 因此,模型是被从底部到顶端一层一层地建立。总之,快速的原型机制作活动包括两部分:数据准备和模型生产。2、快速原型制造和制造业(RP&M)的历史像平常一样的发明,一个人的不耐烦是原型制造产业,现在仅仅十年的样子。其父亲,查尔斯瓦特赫尔,58岁,仍是工程副委员长和技术总监,在1986年帮助他发现了RP公司,加利福尼亚3D巴伦西亚系统。 作为工程师,赫尔很懊恼因为他花了很长时间用塑料来制作原型机的模型。他们必须亲自加工,他回忆说。 如果有一个以上的需要,一般情况下在企业里的情况是,做塑料原型的模子必须单独地用机器制造。在四周矗立一个更好的系统的建筑群。赫尔一直致力于为一家小公司而工作,这家小公司过去常常使用紫外光灯替代紫外激光灯。“但是这种做法对于了解一个实用机器变得很缓慢,”赫尔回忆道,并且需要几年爱迪生式的启发。(实际上,在1998年基于常规紫外光的原型制造机已经形成了,这是由中国西安交通大学先进的制造业技术研究院主导的。)结果是第一个原型制造机器,在1987年引进了三维系统。 它可以示在几小时或好几天的时间里用CAD画图,制造出小的、透明的塑料部分。机器在层上建立模型,从下到上。激光,可以造成光敏液体树脂分子聚合,并且在充满树脂的容器之上扫描。 接着,它可以像一个艺术家一样用素描在面板上留下底纹,射线在整个大致的区域交叉往来以使它硬化。然后让这个平台将模型沉下去,因此有着层数的平台是几乎不可能充满液体树脂的,激光继续起作用在它上面去另一层工变硬,等等。当半透亮的物体形成时,水滴就像是从海底涌现出来的美人鱼一样。赫尔复制了立体平版印刷术的过程,并且它仍然控制着RP。树脂仍然是非常昂贵的:一加仑的丙烯酸酯用可医治的液体的混合可售得大约750美元。但更重要的是企业对原型制造机的渴求,在这样一个时代里,有着大量的高薪酬的能工巧匠们正在减少,上市的时间是很宝贵,设计师们很高兴得到第一个RP机器的以所有价格。 三维系统已经成长为每年都有八千万股票公开的上市公司,这个公司在将来在它所属的领域仍然会是第一位的。不久以后其他发明者开始跳槽。迈克尔Feygin,一位移民的俄国工程师,偶然间有了这么一个用低廉的切片纸建立原型机的想法。他的公司,托兰斯Helisys,位于加利福尼亚,靠被称作是碾压对象生产(LOM)的程序取得了显著的成果。蓝色二氧化碳激光器通过燃烧、移动追踪着每个层数,像一位在这里雕刻轮的疯狂的冰上舞蹈家一样,像那里的一条直线。连续层数由胶粘剂结合。Helisys,它的机器已经形成了自动方向盘、防撞器和感觉触摸起来像木头一样的其他形状的模型,是每年都有1200万公开股票的上市公司。同时,这个MIT发明者的小组是由Emanuel Sachs领导的,他是一位身材匀称的,不摆架子的机械工程教授,对于RP产业从陶瓷和金属起,就没有能力做原型制造机以及模子和生产零件,他甚是愤怒。早期的RP机器只能用一种环形交叉的方式来做一个金属原型制造机。首先塑料模型必须“被投资”或者像陶瓷一样用一种耐热材料来覆盖。然后模型通过熔化就“牺牲”了,就像古埃及人在模子里面熔化蜡模为一个古铜色铸件扫清道路。这种遗留下来的很适合做金属或塑料原型制造机。为什么没有跳跃那个阶段,塞克斯问道,并且直接地由CAD设计做出实用性的零件?他和他的在MIT里销售的30个人成为了RP分支里的领导,其根据相同的技术使计算机打印机通过喷气机喷射墨水来打印文件。而不是墨水,MIT的RP机器在喷一种研成粉的钢、陶瓷,甚至淀粉的层数的黏合剂。三维打印机的机器诞生了,这种机器是采用相当低廉的RP标准,以终端版本是在$50,000的范围内。更大的三维打印机现在可以明确地实现塞克斯的目标,只能用做商业用的直接地由CAD设计出来的金属实体和模型。Soligen, 诺斯里奇,加利福尼亚,公司始建于1992年,是由移居国外的以色列工程师Yehoram Uzirl创立的,在根据MIT的特许下已经开发了喷墨打印,个别机器的表面用来做那些陶瓷过滤器。使用它的机器,Soligen直接地由CAD画图做出了陶瓷模型,适合于像那些用于商用的产品一样坚硬的铸件的金属汽车零件和适合于为测试和小生产运行。Soligen的过程仍然有限制。因为必须毁坏他们获取零部件,陶瓷模子被做成一整件,并且仅能使用一次。但Soligen能够按照需要迅速地做出全部模子。许多RP用户,渴望走的更远,想要可以为大量生产多次使用的迅速地被制作的模子。那将收缩制造业中部有些,绕过一个个常规过程,持久模子用CNC和其他机器精心地雕刻在高等级钢外面块,然后用手费力地完成,过程可能需要几个月。迅速被制作的可再用的模子,将RP直接地投入到了快速制造业领域,已经开始出现。当马利维乐博美办公用品,田纳西州,在1996年从史泰博得到了主要的订单,这是一家办公室产品连锁店,对于一家小型的塑料展台它可以直接地保存大量的材料, 乐博美有克萨斯奥斯汀的DTM制造的机器,去达拉斯的一个RP服务处。十年的老公司,最初代表“桌面制造业”,开发了焊接过程,松散地用激光器加热将研成粉的钢组合从而变紧密塑料,逐层地加固。DTM机器迅速地生产了一个金属模子,乐博美能使用原料做超过30,000个塑料展台的,定价在3美元。杰夫.史密斯.莫里兹,他是圣Didgo的一位做迅速成型制造机报告的时事通讯编辑,他说:“虽然看起来印象不非常深刻,但是这种产品是先驱。 越来越多的模子被用这种方式来制作”。以它最抽象的形式,迅速制造业将剔除模子:机器将能使用CAD设计来直接地制造产品。Extrude Hone,是一家巴拿马欧文的公司,将准备好基于MIT的喷墨机技术来销售机器,将不仅做金属模子,而且也做畅销的金属零件。在Extrude Hone的机器中,研成粉的钢将会用夹器和渗入粉末状的青铜来使其变硬,创造出100%金属的材料。强有力的新的激光器也许为直接制造业敞开着大门。这种激光器系统在像桑迪亚和洛斯阿拉莫斯的国家实验室里被探索着,除了在宾西法尼亚州的密歇根大学外,还有其他地方。他们也许很快就会在商业上适用。 在桑迪亚系统中, 1,000瓦特钕YAG (钇铝镓) 激光器融解在层里熔接粉末状的材料例如不锈和工具钢、磁性合金、基于镍的超耐热不锈钢、钛和钨,目的是为了生产最后的零部件。过程是很缓慢的:做一立方体英寸的物体需要三个小时。但零件通过常规手段做的很密实。桑迪亚副总裁罗伯特J. 爱德华说实验室的研究员希望看到这么一个过程用为军事目的而被存放的核武器的替代品。商业利益也是很高的。十家公司,包括联信公司和洛克希德马丁公司,都参与到了这个项目里来了。另外20家公司也支持在宾夕法尼亚州得研究,目标是做大物体,例如坦克的塔楼和飞机的部件,作为单件。有些专家看到从今天喧闹的,热的常规性工作中解放出来的制造业的更加广泛的未来。而不是模子和机床,这些有远见者预见激光器的建筑零部件,三维打印机的回旋收放针,CNC机器的雕刻成形的,安静的陶瓷部件制造厂将会替换传统喧闹的工厂。利用迅速制造业技术,许多产品在未来工厂中被证明是能够被设计的。因为三维打印机可能做像三明治一样的产品,可植入释放药物的设备,当医学被密封,可能做在一次简单的操作。制造业先驱们发现这种可能性很令人陶醉。“我们可能安排军舰运载不仅仅是零件,还可以是他们3.5英寸磁盘数字化的影像,加上大量的粉末状的金属和快速的制造业机器”, 3M的Marge Hartfel.Adds Brock Hinzmann, SRI国际技术评估的主任,他说:“在两三年内迅速制造业将是在大家经常谈论的事情。”同时,快速成型机的壮举将会给予给工厂伙计们丰足谈论。3、当今RP&M的适用领域尽管RP&M技术还仍然处于早期阶段,但是大多数的工业公司诸如德洲仪器公司,克莱斯勒公司, 安普公司和福特汽车公司已经受益于申请技术改进他们的产品开发,主要表现在以下三个方面(1)工程设计1)可视化。概念型的模型在产品设计中是非常重要的。设计师使用CAD来使他们的设计观念在计算机中表示。然而,无论好的工程师怎么解释蓝图打印方案及复杂的实体是多么好的CAD图象,将看起来实际复杂的产品确切地形象化仍然是非常难的。有些错误也许在工程师和设计师的检查过程中仍然会漏掉。对实体的接触可能会显露意外的问题和有时会激发一个更好的设计。由于有了RP&M,某种复杂部件的原型制造可以在很短的时间里建立,所以工程师们也就可以非常迅速的评估一项设计。2)检验和优化。提高产品的质量一直以来都是制造业中的一项重要的课题。与传统的方法相比,确认或者是优化一项设计的原型机的发展通常是很耗时并成本挺高的。相比之下,这种RP&M的成型机可以在没有充足的工具和劳动力成本下快速的生产。结果是,设计概念的检验变得很简单:产品质量在有限的时间框架和可以支付的成本条件下得到了提高。3)循环。就像自动化工业一样,制造商们通常会把新产品模型推向市场。由于有了RPA&M技术,在短时间内进行多次的设计循环并且大量的减少模型的研发时间成为可能。
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