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1、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-siz
2、e 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
3、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 c
4、omponent 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 obje
5、ct 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
6、 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 pa
7、rt 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
8、，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 se
9、veral 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 prototy
10、ping 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 pro
11、totype 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
12、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
13、 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
14、 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
15、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 re
16、gions 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 accurac
