快速原型技术及在模具制造中的应用【中文2960字】
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1【中文 2960 字】快速原型技术及在模具制造中的应用摘要：论述了快速原型技术的工艺原理、加工特点、形成与发展概况以及在模具制造中的应用，指出该项技术可构成一种应用范围十分广泛、新颖的加工体系，市场前景广阔。关键词：快速原型技术 模具制造 产品开发快速原型技术是一种涉及多学科的新型综合制造技术。80 年代后，随着计算机辅助设计的应用，产品造型和设计能力得到极大提高，然而在产品设计完成后，批量生产前，必须制出样品以表达设计构想，快速获取产品设计的反馈信息，并对产品设计的可行性作出评估、论证。在市场竞争日趋激烈的今天，时间就是效益。为了提高产品市场竞争力，从产品开发到批量投产的整个过程都迫切要求降低成本和提高速度。快速原型技术的出现，为这一问题的解决提供了有效途径，倍受国内外重视。 1 快速原型技术的基本原理 快速原型技术是用离散分层的原理制作产品原型的总称，其原理为：产品三维 CAD 模型分层离散按离散后的平面几何信息逐层加工堆积原材料 生成实体模型。该技术集计算机技术、激光加工技术、新型材料技术于一体，依靠 CAD 软件，在计算机中建立三维实体模型，并将其切分成一系列平面几何信息，以此控制激光束的扫描方向和速度，采用粘结、熔结、聚合或化学反应等手段逐层有选择地加工原材料，从而快速堆积制作出产品实体模型。 2 快速原型技术的加工特点 快速原型技术突破了“毛坯切削加工成品”的传统的零件加工模式，开创了不用刀具制作零件的先河，是一种前所未有的薄层迭加的加工方法。与传统的切削加工方法相比，快速原型加工具有以下优点： (1)可迅速制造出自由曲面和更为复杂形态的零件，如零件中的凹槽、凸肩和空心部分等，大大降低了新产品的开发成本和开发周期。 (2)属非接触加工，不需要机床切削加工所必需的刀具和夹具，无刀具磨损和切削力影响。 (3)无振动、噪声和切削废料。 (4)可实现夜间完全自动化生产。 2(5)加工效率高，能快速制作出产品实体模型及模具。下表为快速原型技术与传统切削方法的比较。快速原型技术与传统切削方法比较表3 快速原型技术的发展 快速原型技术概念即 RP(Rapid Prototyping Technology)概念的提出可追朔到 1979 年，日本东京大学生产技术研究所的中川威雄教授发明了叠层模型造型法，1980 年小玉秀男又提出了光造型法，该设想提出后，由丸谷洋二于 1984 年继续研究，并于 1987 年进行产品试制。1988 年，美国 3D Systems 公司率先推出快速原型实用装置激光立体造型即 SLA(Stereo Lightgraphy Apparatus),并以年销售增长率为 30%40%的增幅在世界市场出售。近年来，随着扫描振镜性能的提高，以及材料科学和计算机技术的发展，快速原型技术已日趋成熟，并于 1994 年正式进入推广普及阶段。 按照所用材料的形态与种类不同，快速原型技术目前有以下四种类型。3.1 利用激光固化树脂材料的光造型法 光造型装置一直以美国 3D Systems 公司的 SLA 型产品独占鳌头，并形成垄断市场。其工作原理如图 1 所示。由激光器发出的紫外光，经光学系统汇集成一支细光束，该光束在计算机控制下，有选择的扫描液激光器扫描镜升降装置容器光敏树脂体光敏树脂表面，利用光敏树脂遇紫外光凝固的机理，一层一层固化光敏树脂，每固化一层后，工作台下降一精确距离，并按新一层表面几何信息使激光扫描器对液面进行扫描，使新一层树脂固化并紧紧粘在前一层已3固化的树脂上，如此反复，直至制作生成一零件实体模型。激光立体造型制造精度目前可达0.1mm,主要用作为产品提供样品和实验模型。此外，日本帝人制机开发的 SOLIFORM 可直接制作注射成型模具和真空注塑模具 图 1 立体光造型技术原理图3.2 纸张叠层造型法 纸张叠层造型法目前以 Helisys 公司开发的 LOM 装置应用最广。该装置采用专用滚筒纸，由加热辊筒使纸张加热联接，然后用激光将纸切断，待加热辊筒自动离开后，再由激光将纸张裁切成层面要求形状，如图 2 所示。 图 2 纸张叠层造型原理图LOM 可制作一些光造型法难以制作的大型零件和厚壁样件，且制作成本低廉（约为光造型法的 1/2）、速度高（约为木模制作时间的 1/5 以下），并可简便地分析设计构思和功能。 43.3 熔融造型法 熔融造型法以美国 Stratasys 公司开发的产品 FDM(Fused Deposition Modelling)应用最为广泛。工作时，直接由计算机控制喷头挤出热塑材料并按照层面几何信息逐层由下而上制作出实体模型。FDM 技术的最大特点是速度快（一般模型仅需几小时即可成型）、无污染，在原型开发和精铸蜡模等方面得到广泛应用。 3.4 热可塑造型法 热可塑造型法以 DTM 公司开发的选择性激光烧结即 SLS(Selective Laser Sintering)应用较多。该方法是用 CO2 激光熔融烧结树脂粉末的方式制作样件。工作时，由 CO2 激光器发出的光束在计算机控制下，根据几何形体各层横截面的几何信息对材料粉末进行扫描，激光扫描处粉末熔化并凝固在一起。然后，铺上一层新粉末，再用激光扫描烧结，如此反复，直至制成所需样件。如图 3所示。图 3 选择性激光烧结原理图SLS 技术造型速度快（一般制品，仅需 1 天2 天即可完成）、造型精度高（每层粉末最小厚度约 0.07mm,激光动态精度可达0.09mm,并具有自动激光补偿功能）、原型强度高（聚碳酸脂其弯曲强度可达 34.5MPa,尼龙可达55MPa），因此，可用原型进行功能试验和装配模拟，以获取最佳曲面和观察配合状况。 在快速原型技术的开发应用方面，美国和日本走在前列。近年来，我国快速原型技术的发展已十分迅速。华中理工大学在 1994 年开发研制成功两种快速成型系统样机 HRP 和 RPS,目前已进入商品市场，广泛应用于汽车、玩具、航空航天、造船、军工等行业。 4 快速原型技术在模具制造中的应用 4.1 快速制模铸造5将需铸零件的 CAD 模型转换为快速模壳制造，按模壳每层截面的几何形状生成陶瓷模壳然后按快速熔模铸造方法即可快速制造金属零件。此外，可将快速原型技术制作生成的样件作为铸造模具的原模，实现零件的快速铸造，其过程为：零件 CAD 三维设计计算流体动力学分析（CFD）LOM 模型制造熔模铸造金属零件。 4.2 快速模具制造 传统的模具制造方法周期长、成本高，一套简单的塑料注塑模具其价值也在 10 万元以上。设计上的任何失误反映到模具上都会造成不可挽回的损失。快速原型技术可精确制作模具的型心和型腔，也可直接用于注射过程制作塑料样件，以便发现和纠正出现的错误。 美国爱达荷国家工程与环境试验中心采用快速凝固工艺即 RSP 技术实现了注塑模具的快速经济制造。该方法采用快速原型技术制作的样件作为母体样板，通过喷涂到母体样板的金属或合金熔滴的沉积制造模具。其工艺过程为：熔融的工具钢或其它合金被压入喷嘴，与高速流动的隋性气体相遇而形成直径约0.05mm 的雾状熔滴，喷向并沉积到母体样板上，复制出母样的表面结构形状，借助脱模剂使沉积形成的钢制模具与母样分离，即可制出所需模具。 母样使用的材料取决于喷涂其上的合金材料。对于喷涂工具钢来说，可选用陶瓷材料，类似材料还有铝氧粉和氧化锆可供选择。该方法制作精度高（喷涂工具钢时最小表面涂层可达0.038mm,制造精度可达0.025mm0.05mm）、时间短（普通模具一周之内即可成型）、造价低（一般为传统模具制造费用的1/21/10）。 4.3 快速铸造模具 以聚碳酸脂为材料，用SLS快速制出母型，并在母体表面制出陶瓷壳型，焙烧后用铝或工具钢在壳内进行铸造，即得到模具的型心和型腔。该方法制作周期不超过4周，制造的模具可生产250000个塑料制品。 5 结论 综上所述，RP是一种正在进一步发展和完善且已获得了广泛应用的高技术。可以预见，随着CAD的广泛应用、市场竞争日趋激烈、快速造型技术本身和快速模具制造成套技术的完善，快速成形技术将发展为一种能被企业普遍采用的技术手段，并将给企业带来巨大的经济效益，这应引起各方面的高度重视。1The Rapid Prototyping Manufacturing and its application in molding manufacturingAbstract: By discussing the rapid prototyping technology the craft principle, characteristic of the processes, formation and the general situation of the develop of fast prototype and its application in molding, point out the technique can form a kind of a process system of extensive application and novel, and its foreground is vast.Key Words: rapid prototyping technology; molding manufacturing; development of productRapid prototyping technology is a new type of multidisciplinary integrated manufacturing technology. After the 1980s, following the application of computer-aided design, product shape and design capabilities have greatly improved, however, product design has completed, production, a system must be designed to convey the concept of samples, rapid feedback to product design, product design and assess the feasibility, and feasibility studies. The increasingly fierce competition in the market today, the time is effective. To enhance the competitiveness of products, from product development to volume production of the whole process are urgently required to reduce costs and increase speed. Rapid prototype technology appearance provides an effective solution to this problem which much attention at home and abroad.1. The basic principle of Rapid Prototyping TechnologyThe RP is the generic name of the principle creation product prototype that uses the long-lost layering, its principle is: Produce CAD model Stratified separated according to the plan geometry information which is dispersed to pile up the original material generating entity models.This technology integrates of computer technology, laser processing technology, new material technology, relying on CAD software in the creation of 3D computer models entities, and is divided into a series of plane geometry information to control the scanning laser beam direction and speed, using sinter, pooling or chemical reaction means exhaustive selective processing of raw materials, thus rapid accumulation manufacture products entities models.2. The characteristics of Rapid Prototyping TechnologyRapid Prototyping Technology breaks the traditional way to produce spare parts 2of “roughcast slice to pare to processfinished”, Needless cutlery created the first production of spare parts, is an unprecedented lamina reducing processing methods. Comparing to tradition, the fast prototype processes the following advantage:(1) Produce the spare parts of the curved face and more complicated appearance quickly, such as shoulder within spare parts and hollow and parts of etc.s, consumedly lowered the development cost of the new product and development period.(2) Is a non-contact processing, machine tool cutting processing is necessary cutlery and jig without cutlery wear and cutting force.(3) Without vibration, noise and slice to pare the waste.(4) Can carry out the nighttime over full-automatic production.(5) Process with high efficiency, produces the article entity model and molding tools quickly.The form follows the comparison of the method for the Rapid Prototyping Technology and tradition.Processing technologyComparison the item The tool machine slices to pare to processRP(Light shape method)processThe method of processDo away with the surplus material processFold the layer processThe object of process Solid Liquid, portrait, powderTool The tool of slice to pare Light beamMinimum processing unitsDots diameter is about 1msTriangles of 200ms longProduction of spare partsThe least processes come together the body of the unitThe least processes come together the body of the unitThe RP and traditions slice to pare the method comparison sheet3. The develop of RPRapid prototyping technology concept that the concept RP (Rapid Prototyping Technology) could be back to 1979. the profess of Zhong Chuan Weixiong in 3produce and technique institute of Japanese University of Tokyo invent the method of fold the layer model, the Xiao Yu Xiunan put forward the light shape method again in 1980, after the conceive put forward, it was continued to study in 1984 by Wan Gu Yanger, and carried on to produce manufacture on a trial basis in 1987.1988, the United States rapidly prototype 3D Systems Corporation was the first to introduce practical devices-laser three-dimensional shapes that SLA (Stereo Lightgraphy Apparatus), and annual sales growth rate 30%40% increase in the world market. In recent years, with increasing performance scanning-a mirror, and the development of materials science and computer technology, rapid prototyping technology matures, and in 1994 to promote universal access to the formal stage. In accordance with the patterns and materials used in the different types of rapid prototyping technology currently has the following four types.3.1 Solidification resin materials using laser light shapes lawThe light shape equipment is excellent with a product of the 3D Systems company of the United States, and the formation of a monopoly. Figure 1 shows the operating principles. Issued by the laser light, the optical system to compile into a small beam, the beam in the computer controlled, selective scanning resin surface, using an ultraviolet resin Frozen mechanisms, a layer of solidification resin, each layer of solidification, precision workstations in a distance with the new layer of surface geometric information to the laser scanner for scanning reading, solidification of the new layer of resin and firmly stick to the previous layer has solidification resin, so repeatedly until the production of spare parts entities generated a model. The laser stereoscopic shape manufacturing accuracy can reach the 0.1 mms, mainly used to provide the sample and the experiment models for the product. In addition, the SOLIFORM of the Japanese system machine developed can manufacture to inject to model the molding tool and vacuum molding tools directly.4Figure 1 Stereoscopic light shape technique principle diagram3.2The paper folds the layer shape methodThe paper folds the LOM that the layer shape method develops with the Helisys company currently applicant most widely. The devices used for roller paper from the paper heating roller cylinders connectivity, and then using the laser to cut paper, the question heating roller cylinders automatically leave, the paper will be ready by laser level requirements into shape, as shown in figure 2. Figure 2 Principle diagram of the paper folds the layer shapeThe LOM can manufacture some large spare parts and the thick wall kind pieces of the hard creation with lights shape method and create cost is cheap (about for the light shape method of 1/2), the speed is high (about manufacture time for the wood 5mold of below 1/5), and can simply analytic the design conceive outline and function.3.3 meltdown shape methods The meltdown shape method is most extensive used with the product FDM which is developed in American Stratasys,(the Fused Deposition Modeling), when it is working, the plastics material with hot extrusion sprayed directly by sprinkler head controlled by computer combine to layer to create an entity model from bottom to top according to several information of level. The biggest characteristics in FDM technical is a quick(general the model need several hours and can immediately model) and free from pollution, to get the extensive application in prototype, develop and cast wax mole and so on.3.4 hot and fictile shape methodsThe hot and fictile shape method burns the knot with the selectivity laser of the DTM company development namely the SLS (the Selective Laser Sintering) application is the most. That method is a way manufacture kind piece that burns with the CO2 laser machine controls by the calculator, carry on scanning on the material powder according to several information for faces of several pieces with horizontal each layer of the body, the powder is scanning by laser and solidify together. Then, spread up a new powder of layer, then scan to burn the knot with the laser, thus again and again, keep to go to make the kind piece which needed. As figure 3 shows.Figure 3 The principle chart of selectivity laser sinteringThe SLS technique shape speed is fast(general ware, need one or two days to complete), the shape accuracy is high(the minimum thickness of each layer powder is about 0.07 mms, the laser dynamic state accuracy can reach the 0.09 mms, and 6have the automatic laser repair function), the prototype strength is high(gather its bent strength of the carbonic acid fat and can amount to the 34.5MPa,the nylon can reach 55MPa), therefore, can carry on functions experiment and assemble the emulation with the prototype, to obtain the best curved face to match with the observation the condition.Develop and applied aspect technically in RP, the United States and Japans are the best. In Huazhong University develops two kinds of model system machine HRP and RPSs which is research to manufacture in 1994 successful quickly, have already entered the commodity market currently, be applied in the professions extensively, such as automobile, toy, aviation aerospace, shipbuilding and the soldier work etc.4. The application of the RP in molding manufacture4.1 Making the mold foundry fastPut the spare part CAD model converse to fast method, produce metal spare parts quickly according to each layer shape of face to for ceramic mold and then accord to fast method. In addition, can carry out the original mold that the fast prototype technique manufactures a conduct and actions founder molding tool, spare parts of fast cast, its process is: Design the spare parts CAD 3D the calculation hydrodynamics analysis(CFD)the LOM model manufacturingcast the metals spare parts.4.2 fast molding tool manufacturingThe traditional molding tool manufacturing method period is long, the cost is high, a set of simple plastics molding tool is worth above 100,000 dollars. Any error of design reflects the molding tool make the loss that cant be retrieved. Fast prototype technique can a heart and bodies of the accurate manufacture molding tool, also can used for injecting process to produce manufacture plastics piece directly, for the purpose of detection and the mistake that rectify to appear.The center of national engineering in American Idaho and environments experiment adopt the fast concretion craft namely the technique of RSP carried out the fast and economy of the plastics molding manufacture. That method adopt fast prototype technique produce sample to be sample product sink to accumulate to make the mold. The craft process is steel or tool used for other alloys of the meltdown were pressed to go in to the mouth of spray meet high speed Sui air to form fog of liquid which diameter about 0.05mms, spay to maternal sample and sink 7to accumulate on it, make duplicate the surface structure shape of maternal sample, with the help of chemical to separate the st
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