机械工程计划英语第二版part2unit11翻译.doc

/机械工程英语（第 11 单元）Rapid Prototyping and Manufacturing Technologies 快速原型制造和快速制造技术Introduction介绍Manufacturing community is facing two important challenging tasks：（1）Substantial reduction of production development times; and (2) Improvement on flexibility for manufacturing multi-variety and small batch-size 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-design with computer-aided manufacturing for rapid development of new products.制造社会面临两个重要的艰巨任务：1 大幅度减少产品开发时间，以及改善对弹性制造多品种，小批量大小的产品。电脑辅助及制造大大改善了传统的生产设计和制造。但是，有一个数字障碍计算机辅助设计与真正的一体化电脑辅助制造新产品的快速发展。To substantially shorten the time for developing patterns, and prototypes, some manufacturing enterprises have started to use rapid prototypes(RP)methods for complex patterns making and component prototyping. Over the past few years, A variety of new rapid manufacturing theologies, generally called Rapid Prototyping and /Manufacturing ,have emerged; the technologies developed include stereo lithography(SL),selective laser sintering (SLS), fused deposition modeling(FSM),laminated object manufacturing(LOM),and three dimensional printing (3D Printing)。These technologies are capable of directly generating physical objects from CAD databases. They have a common important feature: the prototype part is produced 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.为了大大缩短母摸、模具和样件的制作时间，一些制作厂开始利用快速原型制造技术来制作复杂的母模和零部件的原型。在过去几年中，各种新的快速制造技术，通常被称为快速成型与制造，有涌现，这些技术包括立体开发，选择性激光烧结，熔融沉积成型，分层实体制造，三维打印。这些技术能够直接从 CAD 数据库生成实体对象。他们都有一些共同的重要特征：原型件都是通过增材制造，而不是材料去除工艺制作的，也就是说，零件首先通过几何建模软件，比如一个实体建模模块来建模，然后用数学的方法进行切层处/理，使其成为一连串平行的横截面片。每件，固化或具有约束力的路径生成。这些固化或具有约束力路径是直接用于指导生产的部分机器固化或具有约束力的材料一致。建成后，一层是，一个新的层是建立在以同样的方式前一个。因此，该模型建立一层一层从底部到顶部。RR Processes RP 反相进程As mentioned earlier, there are several technologies available for model production based on the principle of “growing” or “additive” manufacturing. The major differences among these technologies are in two aspects (1) Materials used, and (2) Part building techniques. The following sections will explain in detail these rapid prototyping technologies with respect to the above two aspects.如前所述，有几种技术可以为模型生产的基础上，增加或添加剂生产原则。这些技术之间的主要分歧是在两个方面;材料使用，而部分建筑技术。以下部分将解释快速原型技术，这些细节就上述两项方面。1.Stereo lithography 光固化Stereo lithography apparatus (SLA) was invented by Charles Hull of 3D Systems Inc. It is the first commercially available rapid prototype and is considered as the most widely used prototyping machine. The material used is liquid pho-to-curable resin, acryl ate (monomers) are polymerized /into large molecules. Based on this principle, the part is built in a vat of liquid resin as shown in Figl.1.光固化成型机由 3D 系统公司的 Charles Hull 发明。它是世界第一台使用最广的商业快速成型机。使用的材料为丙烯酸光敏树脂。在光子的引发下，小分子（单体）聚合成大分子。原型零件就是根据这一原理从树脂槽中制作出来的。The SLA machine creates the prototype by tracing layer cross-section on the surfaces of the liquid photopolymer pool with a laser beam. Unlike the contouring or zigzag cutter movement used in CNC machining, the beam traces in parallel lines. The laser beam is deflected horizontally in X and Y axes by galvanometer-driven mirrors so that it moves across the surface of the resin to produce a solid resin covers the solidified layer. A wiper helps appeared the viscous polymer over for building the next layer. The laser draws a new layer on the top of the previous one. In this way, the model is built layer by layer from bottom to top.苏丹解放军机上创建的跟踪层横截面的原型表面用激光束液体感光树脂池。同数控机床加工时刀具的轮廓走刀和循环走刀方式不一样，激光束是以平行方式扫描的。 （4） 该激光束偏转在 X 和 Y 轴的横向振驱动镜子，以便它在整个行动的树脂表面产生了坚实的格局。建成后 1 层，电梯下降一个用户指定的距离和新的液态树脂固化涂料覆盖层。刮板用来将粘稠的树脂均匀涂覆在零件表面以便于下一层的制作。激光在前一层的顶部进行新一层的扫描。这样，原/型就自下而上地逐层制作而成。There are several features worthy of mentioning of SLA有许多值得一提的 SLA 的几个特点。1.Material. 材料。There are five commercially available photopolymers. All of them are a kind of acryl ate.这五个商用光聚合物。他们都是一种丙烯酸类。(1)Support. （2）支持。Because a model is created in liquid, the overhanging regions of the part (unsupported below) may sag or float away during the building process. The prototype thus needs some predesigned support until it is cured or solidified. These additional features are built on the model parts and have to be trimmed after the model building is completed.因为模型是在液体中创建了一部分（不受支持低于）悬垂地区可能骤降或漂浮在建设过程中走。因此，需要一些原型预先设计的支持，直到它被治愈或凝固。这些附加功能是建立在模型部分，要修剪后建设完成。(3)Model accuracy and performance. （3） 模型的精度和性能。The accuracy achieved is about 0.5% .The layer thickness is between 0.004”and 0.003”.Presently,the SLA machines made by 3D Systems Inc. are the most accurate machines among the RP&M systems.精度达到约/0.1的整体尺寸和体积较大的恶化，但不超过 0.5。层厚度为0.03 和 0.004 之间。目前，苏丹解放军机由 3D 系统公司。反相属于机电系统中最精确的机器。1.Selective laser sintering(SLS) 2。选择性激光烧结SLS uses a carbon dioxide laser to sinter successive layers of powder instead of liquid. In SLS processes, a thin layer of powder is applied by a rotating roller mechanism onto the work place. The powder material is preheated to a temperature slightly below its melting point. The laser beam traces the cross-section on the powder surface to heat up the powder to the sintering temperature so that the powder scanned by the laser is bonded. The powder that is not scanner by the laser will remain in place to serve as the support to the next layer of powder, which aids in reducing distortion. When a layer of the cross-section is completed, the roller levels another layer of powder over the sintered one for the next pass.Fif.11.2 shows the working principle of SLS.选择性激光烧结采用二氧化碳激光烧结粉末，而不是连续的液体层。选择性激光烧结过程中，一薄层粉是由地方上的工作辊旋转机制的应用。粉末材料预热的温度稍低于其熔点。激光束的痕迹跨粉末表面上的部分来加热粉末烧结温度，使粉末激光扫描是保税。即不是由拉斯特扫描将继续留在当地作为未来的粉层，减少失真艾滋病支助粉末。当一个截面层完成后，滚筒的水平在未来通过彼此的粉末 烧结层。 Fig.11.2 显示了选择性激光烧结的工/作原理。2.Fused deposition modeling (FDM) 3。熔融沉积建模In an FDM process as shown in Fig.11.3, a spool of thermoplastic filament feeds into a heated FDM extrusion head. The movement of the FDM head is controlled by computer. Inside the flying extrusion head, the filament is melted into liquid (1C above the melting temperature) by a resistant heater. The head traces an exact out line of each cross-section layer of the part. As the head moves horizontally in X and Y axes, the thermoplastic material is extruded out of a nozzle by a precision pump. The material solidifies in 1/10 second as it is directed onto the workplace. After one layer is finished, the extrusion head moves up a programmed distance in direction for building the next layer. Each layer is bonded to the previous layer through thermal heating.在熔融沉积在 Fig.11.3 建模过程中，阀芯的热塑性长丝饲料入加热熔融沉积造型挤出头。对熔融沉积造型头部运动是由电脑控制。 在高速运动的挤压头里，丝材被电阻加热融化成液态（高于熔点1。C 左右） 。挤压头精确按零件截面轮廓形状移动（从而逐层将原型零件制作出来） 。 水平移动的头在 X 和 Y 轴，热塑性材料挤压出一府精密泵喷嘴。固化材料在 1 / 10 秒，因为它是把工作场所的指示。完成后，1 层，挤压头移动了下一层建设的一个程序在 Z 方向的距离。每一层粘合到上一层，通过热供暖。3.Laminated object manufacturing (LOM) 4。分层实体制造/（LOM）的The LOM process produce parts from bonded paper plastic, metal or composite sheet stock. LOM machines bond a layer of sheet material to a stack of previously formed laminations, and then a laser beam follows the contour of the part cross-section generated by CAD to cut it to the required shape. The layers can be glued or welded together and the excess material of every sheet is either removed by vacuum suction or remains as next layers support.Fig.11.4 shows the working principle of LOM.洛美进程从保税纸塑，金属复合板股票或亲达斯部分。洛美机器结合一板层材料一叠以前形成的薄片，然后用激光束遵循的部分轮廓截面由 CAD 生成的删减至所需要的形状。该层可以胶合或焊接在一起，每片材过剩是可以通过真空抽吸删除或仍然是下一层的支持。 fig.11.4 显示奥尔姆的工作原理。4.Three-dimensional printing was developed at Massachusetts Institute of Technology. In the 3Dprinting process, a 3D model is sliced into 2D cross-section layers in a computer. A layer of powder is spread on the top of the piston, the powder barding a cylinder, and then an ink-jest printing head projects duplets of blinder material onto the powder at the place where the solidification is required according to the information from the computer model. After one layer is /completed, the piston drops a predefined distance and a new layer of powder is spread out and selectively glued. When the whole part is completed, heat treatment is required to enhance the bonding of the glued powder, and then the unbounded powder is removed. Fig.11.5 shows the working process of 3D Printing. 5. 亲切体贴的三维印刷（三维印刷）三维打印是开发的麻省理工学院。在三维印刷过程中，三维模型切成二维截面层在一台计算机。 首先在气缸的活塞（粉末床）顶部铺上一层粉末，然后一个喷墨打印头根据计算机模型信息在要求固化的粉末部分表面喷上粘结材料。 完成后，1 层，活塞下降一个预定义的距离和一个新的层粉分散和选择性粘贴。当整个部分完成，热处理必须加强粘粉粘接，然后无界粉被删除。 fig.11.5 显示了三维打印的工作流程。当前的 RPM 的应用Current Applications of RP&MA 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. 一个大型的工业企业，例如得克萨斯文书所公司，克莱斯勒公司，放大器公司,和福特汽车公司。得益于采用的技术，以改善他们在以下三个方面的产品开发利用策略。设计工程/1. Design engineering 设计工程(1) Visualization. . （1）可视化。 Conceptual models are very important in product design. 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 a short time, therefore engineers can evaluate a design quickly 概念模型在产品设计中十分重要。触摸真实的物理实体可以暴露某些无法预料的问题，有时还会引发出更好的设计。 采用 RPM 的，是一个复杂的零件原型可以在很短的时间，因此工程师可以评估一个设计非常快。(2) Verification and optimization. （2）验证和优化。Improving product quality is always an important issue of manufacturing. With the traditional method, developing of prototypes can be produced quickly without substantial tooling and labor cost. Consequently, the verification of design concepts becomes simple: the product quality can be improved within the limited time and with affordable cost.期完善产品质量始终是制造业的重要问题。与传统的方法，来验证原型开发或优化一出大量的工具和劳动力成本的设计。因此，设计概念验证变得简单：产品质量可以在有限的时间内可承受的成本提高。(3) Iteration. （3）迭代Just like the automotive industry, manufacturers often put new product /models into market. With RP&M technology, it is possible to go through multiple design iterations within a short time and substantially reduce the model development time.。就像汽车行业，制造商奥芬投入市场的新产品型号。 有了快速原型与制作技术，就有可能在较短时间里通过多次设计迭代，从而大大减少模型的开发周期。2. ManufacturingWe can use the RP&M prototype for reducibility studies. By providing a physical product at an earlier design stage, we can speed up process planning and tooling design. In addition, by accurately describing complex geometry, the prototype can help reduce problems in interpreting the blue also be used as master patterns for castings. 2。我们可以利用的可生产性研究的转原型。在较早提供一个物理产品设计阶段，我们可以加速设计流程规划和托林。此外，通过精确地描述复杂的几何图形，原型可以帮助减少在解释蓝色的问题打印在车间。另一个应用是模具的模具开发利用策略。原型也可以用作铸件主模式。3. Marketing 3。市场营销To assist product sales, a prototype can be used to demonstrate the concept, design ideas, as well as the companys ability to produce it. Also, the prototype can be used to gain customers” feedback for design modifications so that the final product will meet customers” requirements. Meeting customers” demand in a timely manner is the key to penetrating /the market in todays economy. 协助产品销售，原型可以用来展示的概念，设计理念，以及该公司能够生产它。同时，原型可以用来获得客户的反馈意见，以便为修改设计，最终产品将满足客户的需求。满足客户的及时需求是要打入在当今经济市场的关键。