注射成型外文文献翻译@塑料模具类外文翻译@中英文翻译

2.3 注射成型 2.31 注射成型 注塑主要用于生产热塑性塑料零件，也是最原始的方法之一。目前注塑占所有塑料树脂消费量的 30%。典型的注塑成型产品“塑料杯、容器、外壳、工具手柄、旋钮、电气和通信组件 (如电话接收器 )、玩具、和水暖配件。 聚合物熔体由于其分子量具有很高的粘度；它们不能像金属液在重力的条件下倒进模 ,必须在高压力下注入模具。因此 ,金属铸造的力学性能是由模具壁传热的速度决定，同时也决定了在最终铸件的晶粒尺寸和晶粒取向 , 高压注射成型过程中熔体的注射剪切力产生的主要原因是材料最后的分子取向。力学性能影 响成品都是因为在模具里的注塑条件很冷却条件。 注塑已应用于热塑性塑料和热固性材料 ,发泡部分 ,也已被修改过用于展现注射成型（ RIM）反应过程，其中有两个部分组成，一种是热固性树脂体系，另一种是聚合物快速注射模具。然而大多数注射成型是热塑性塑料 ,后面的讨论集中于这样的模型。 一个典型的注塑周期或序列由五个阶段组成 (见图 2 - 1): 注射或模具填充 ； (2) 包装或压缩 ； (3) 保持 ； (4) 冷却 ； (5)部分排除物 图 2 - 1 注射成型过程 塑料颗粒（或粉末）被装入进料斗并通过注塑缸上的 开口在那里它们被旋转螺杆结转。螺杆的旋转使颗粒处于高压下加上受热缸壁使它们融化。加热温度范围从 265 到 500 F。随着压力的增大 ,旋转螺丝被迫向后 ,直到积累了足够的塑料可以进行注射。注射活塞 (或螺钉 )迫使熔融塑料从料桶通过喷嘴、浇口和流道系统 ,最后进入模腔。在注射过程中 ,熔融塑料充满模具型腔。当塑料接触冷模具表面 ,它迅速凝固 (冻结 )产生皮肤层。由于核心仍在熔融状态 ,塑料流经核心来完成填充。一般的，该空腔被注入期间填充到 95 ?98。 然后成型工艺转向了填充的阶段。型腔填充后，熔融塑料开始冷却。由于冷却塑料 会收缩产生缺陷，如缩孔、气泡，而且空间存在不稳定性。所以被迫实行空穴用来补偿收缩、添加塑料。一旦模腔被填充，压力应用熔体防止腔内熔融塑料会流进浇口。压力必持续到浇口部分就凝固了。该过程可以分成两个步骤（填充和保持）或者可能在一个步骤中（保持或第二级）所涵盖。在填充过程中，熔体被用于收缩的填充压力补偿压入型腔中。保持过程中，压力只是防止聚合物熔体的倒流。 保持阶段结束后冷却阶段开始。在冷却过程中，部分在模具持有指定期间。冷却阶段的持续时间主要取决于材料的性质和厚度。通常，该部分的温度必须冷却到低于材料的脱模温 度。 在冷却部件，这台机器塑性熔化在下一个周期。聚合物受剪切作用以及电热丝的能量。一旦开枪，塑化停止。这应该是在冷却阶段结束之前。然后将模具开启，一部分被排出。 2.3.2注塑模具 注塑模具的多种多样的设计、复杂程度和大小作为它们的生产部分。功能热塑性塑料模具，基本上是传授理想的形状，然后进行聚合物注射件的冷却。 一种模具是由两组部件组成：（ 1）型腔和型芯（ 2）空腔和型芯的安装。模塑部件的尺寸和重量限制了模腔的数量并且还决定了所要求的设备的能力。考虑成型工艺，模具必须设计的安全地吸收由于夹紧。注塑。脱模带来 的力。同时，浇口和流道的设计必须允许有效流动和统一的模具型腔填充。 图 2-2 示出了一个典型的注塑模具。模具主要由两部分组成：一个部分精止不动的（模腔板），在那边熔融聚合物被注入，另一部分可以移动（型心板）在截止面上或喷射器的注塑设备上。两个半模之间的分离线被称为分型线。注射的材料是通过中央进料通道，称为浇口。物料位于锥形流道，便于套管在打开的模具中释放模具材料。在多数模具、物料聚合物熔体助长了流道系统，通过一个浇口流向每个模具型腔。 核心板的主要核心。主要的核心的目的是建立内部部分的配置。核心目的是建立内部 结构。核心板具有备份或支撑板，支撑板是由支柱所支撑的，这个支柱是作为喷射器壳体的 u 型结构为人所知，它由后部夹持板和隔块组成。此 U 形结构是用螺栓固定在核心板，它为起模行程也就是脱模行程提供了空间。在凝固过程中该部分围绕主芯收缩，使模具打开时，第二部分和浇道一起被移动的半模进行。随后，中央喷射器被激活时，使顶出板向前移动，导致顶出杆可以推动这部分远离核心。两个半模设置有冷却通道，通过该冷却通道，水被循环以吸收由热塑性聚合物熔体输送到模具的热量。模腔还采用精细的通风口（ 0.02?0.08 毫米 5毫米）的，以确保填 充过程中没有空气残留。 注塑模具现在在使用中有六种基本类型。它们是：（ 1）双板模具，（ 2）三板模，（ 3）热浇道模，（ 4）绝缘热浇道模，（ 5）热歧管模具，以及层叠模具。图。 2-3 和图 2-4 说明了这六种基本类型的注塑模具。 图 2 - 2 注塑模具 1 - 顶杆 2 - 推板 3 - 导套 4 - 导柱 5 - 顶杆底板 6 钩料杆销 7 推回针 8 针限制 9 导柱 10 - 导柱 11 腔板 12 - 浇口套 13 塑料工件 14 芯 图 2-3 这说明三者的六种基本类型的注塑模具 (1) 两板注射模具（ 2）三板注塑模（ 3）热流道模具 见图 . 2-4 其他三种型。 图 2-4 这说明三者的六种基本类型的注塑模具 （ 1）绝缘热流道注塑模具（ 2）热歧管注塑模具（ 3）堆叠式注塑模具 见图 .2-3 对于其他三种类型。 1两板模 一种双板模具由两个板与腔和型芯安装在任一模版上 .板被固定到压板上。移动一半的模具通常含有推出结构和浇道系统。所有注塑模具的基本设计有这样的设计理念。两板模具是最合乎逻辑的类型对于一些需要使用那些需要很大浇口零件的工具来说。 2三板模具 这种类型的模具是由三块板组成：（ 1）固定或流道板是连接到静止的滚筒，通 常包含浇道和半流道，（ 2）中间板或模腔板，包含一半道和浇口，允许在开模时浮动，（ 3）移动板或受力板塑造和推出系统部分切除塑造的部分。当通道开始打开，中间板和可动板一起移动，从而释放浇道和流道系统和去浇口的成型部件。这种类型的模具的设计能够分隔流道系统和部件当模具打开时。这种模具的设计可以使用点浇口浇注系统。 3 .热流道模具 在注射成型的过程中，流道保持热量以保证熔融塑料是流体状态，在任何时候。实际上这是一个 无浇道 成型工艺而且有时被称为是相同的。在无流道模具中，流道包含在一个独立的板上。热流道模具类似三 板注塑模具，除了模具流道的部分在成型周期打不开。加热流道板与其余的冷模隔热。除了加热板是为了流道设计，模具剩余部分是一个标准两板模。 无流道成型较传统浇道式成型有很多优点。没有成型的副产物（浇口，流道，或主流道）被处理掉或循环再使用，没有从主流到分离。周期时间是成型部分被冷却，从模具中顶出。在这个系统中，一个均匀的熔体温度可以从注射模具型腔的汽缸达到的。 4绝缘热流道模具 这是一个变化的保温模具。在这种类型的模具中，流道的外表面材料是绝缘体的优质材料。在绝热模具中，成型材料铸造成型仍然通过保持热量。有时 一个分料梭和热探测器需要更多的灵活性。这种类型的模具多腔中心浇口部分是理想的。、 5.热流道模具 这是一个变化的保温流道模具。在热流道模具中，流道是加热的而不是流道板。这是通过使用一个电子嵌入探针完成的。 6.堆叠模具 堆叠注塑模具，顾名思义就是多个两板模具放置一起。这种结构也可以用于三板模具和保温流道模具。堆叠两模板的构造重点提出一个单一通道要求比同样数量的模具减少一般夹紧压力。这个方法有时候被称为“二级成型”。 2.3.3 成型机 1.传统注塑机 在这个过程中 ,塑料颗粒或颗粒注入机料斗并注入加热缸腔内 。然后柱塞压缩材料 ,迫使它逐步通过加热缸的温度区域 ,在那里它被分料梭分散的很薄。分料梭安装在缸的中心，目的是为了加快塑料中心的加热质量。分料梭也可从内部加热处理使塑料内外都加热。 材料从加热缸流动通过一个管口进入模具。这个管口是缸和和模具的分割点 ,它是用来防止产生压力导致物质泄漏。模具是关闭了有夹钳一端的机器。对于聚苯乙烯 ,夹钳上两到三吨的压力要用于材料和系统的每一寸空间。传统的柱塞机是唯一可以产生杂色部件的注塑机 ,其他类型的完全将塑料材料融合在一起 ,只会产生一种颜色。 2.柱塞式预塑机 这台机器使用一个分 料梭加热器来预塑塑料颗粒。融化阶段后 ,液体塑料是被排入一个存放腔内，直到可以进入模具。这种类型的机器生产速度比传统的机器快 ,由于成型室是在冷却时不断释放能量。由于注射柱塞作用于流体材料 ,在颗粒压缩时没有压力损失。这允许更大的部件有更大的投影面积。它其余的特性与传统单活塞注射机相同。图 2 - 5 演示了一个柱塞式预塑机。 3.螺杆式预塑机 这种注射机用挤出机塑化塑料材料。车削螺杆向挤压机内表面供料。将挤出机熔融、塑化的材料移动到另一个存放腔 ,然后从那里被注射柱塞挤入模具。使用螺旋有以下优点 :(1)塑性材料 能更好的融合和受力 ；(2)流动材料更硬，热敏感材料能流动 ；(3)颜色变化可以在更短的时间内处理 (4)模制品受更小的压力。 4.往复式螺杆注塑机 这种类型的注塑机在加热室处采用卧式挤压机。塑料材料由于螺杆的旋转被推进挤压机管道。随着材料通过加热筒与螺杆时 ,它正在从颗粒变成塑料熔融状态。在往复式螺杆注塑机中 ,热量传递到模塑料的热量是由螺杆之间的摩擦传导和挤压机管道壁。材料移动时 ,螺杆又回到极限状态 ,这种状态是决定材料在压力机管道前的体积的。这时 ,与典型压力机的相似之处结束了。在材料注入模具时 ,螺杆向前移动，重新 塑造管道中的材料。在这台机器中，螺杆的角色既是一个柱塞又是一个螺杆。在模型浇口部分已经凝固不能回流时，螺杆开始旋转回程，走下一圈。图 2-5 是一个往复式螺杆注塑机。 这种注塑方法有几个优点。它能使热敏材料更有效地塑化，使颜色融合更快 ,材料的温度通常更低，整个循环时间也更短。 2.3 Injection Molds 2.3.1 Injection Molding Injection molding is principally used for the production of thermoplastic parts, and it is also one of the oldest. Currently injection-molding accounts for 30% of all plastics resin consumption.Typical injection-molded products are cups, containers, housings, tool handles, knobs, electrical and communication components (such as telephone receivers), toys, and plumbing fittings. Polymer melts have very high viscosities due to their high molecular weights； they cannot be poured directly into a mold under gravity flow as metals can, but must be forced into the moldunder high pressure. Therefore while the mechanical properties of a metal casting are predominantly determined by the rate of heat transfer from the mold walls, which determines the grain size and grain orientation in the final casting, in injection molding the high pressure during the injection of the melt produces shear forces that are the primary cause of the final molecularorientation in the material. The mechanical properties of the finished product are therefore affected by both the injection conditions and the cooling conditions within the mold. Injection molding has been applied to thermoplastics and thermosets, foamed parts, and has been modified to yield the reaction injection molding (RIM) process, in which the twocomponents of a thermosetting resin system are simultaneously injected and polymerize rapidly within the mold. Most injection molding is however performed on thermoplastics, and the discussion that follows concentrates on such moldings.Chapter 2 Plastics Molds A typical injection molding cycle or sequence consists of five phases (see Fig. 2-1): （ 1） Injection or mold filling； (2) Packing or compression； (3) Holding； (4) Cooling； (5) Part ejection. Plastic pellets (or powder) are loaded into the feed hopper and through an opening in the injection cylinder where they are carried forward by the rotating screw. The rotation of the screw forces the pellets under high pressure against the heated walls of the cylinder causing them to melt. Heating temperatures range from 265 to 500 F. As the pressure builds up, the rotating screw is forced backward until enough plastic has accumulated to make the shot. The injection ram (or screw) forces molten plastic from the barrel, through the nozzle, sprue and runner system,and finally into the mold cavities. During injection, the mold cavity is filled volumetrically.When the plastic contacts the cold mold surfaces, it solidifies (freezes) rapidly to produce the skin layer. Since the core remains in the molten state, plastic flows through the core to complete mold filling. Typically, the cavity is filled to 95%98% during injection. Then the molding process is switched over to the packing phase. Even as the cavity is filled,the molten plastic begins to cool. Since the cooling plastic contracts or shrinks, it gives rise to defects such as sink marks, voids, and dimensional instabilities. To compensate for shrinkage,addition plastic is forced into the cavity. Once the cavity is packed, pressure applied to the melt prevents molten plastic inside the cavity from back flowing out through the gate. The pressure must be applied until the gate solidifies. The process can be divided into two steps (packing and holding) or may be encompassed in one step (holding or second stage). During packing, melt forced into the cavity by the packing pressure compensates for shrinkage. With holding, the pressure merely prevents back flow of the polymer melt. After the holding stage is completed, the cooling phase starts. During cooling, the part is held in the mold for specified period. The duration of the cooling phase depends primarily on the material properties and the part thickness. Typically, the part temperature must cool below the materials ejection temperature. While cooling the part, the machine plasticates melt for the next cycle. The polymer is subjected to shearing action as well as the condition of the energy from the heater bands. Once the shot is made, plastication ceases. This should occur immediately before the end of the cooling phase. Then the mold opens and the part is ejected. 2.3.2 Injection Molds Molds for injection molding are as varied in design, degree of complexity, and size as are the parts produced from them. The functions of a mold for thermoplastics are basically to impart the desired shape to the plasticized polymer and then to cool the molded part. A mold is made up of two sets of components: (1) the cavities and cores, and (2) the base in which the cavities and cores are mounted. The size and weight of the molded parts limit the number of cavities in the mold and also determine the equipment capacity required. From consideration of the molding process, a mold has to be designed to safely absorb the forces of clamping, injection, and ejection. Also, the design of the gates and runners must allow for efficient flow and uniform filling of the mold cavities. Fig.2-2 illustrates the parts in a typical injection mold. The mold basically consists of two parts: a stationary half (cavity plate), on the side where molten polymer is injected, and a moving half (core plate) on the closing or ejector side of the injection molding equipment. The separating line between the two mold halves is called the parting line. The injected material is transferred through a central feed channel, called the sprue. The sprue is located on the sprue bushing and is tapered to facilitate release of the sprue material from the mold during mold opening. In multicavity molds, the sprue feeds the polymer melt to a runner system, which leads into each mold cavity through a gate. The core plate holds the main core. The purpose of the main core is to establish the inside configuration of the part. The core plate has a backup or support plate. The support plate in turn is supported by pillars against the U-shaped structure known as the ejector housing, which consists of the rear clamping plate and spacer blocks. This U-shaped structure, which is bolted to the core plate, provides the space for the ejection stroke also known as the stripper stroke. During solidification the part shrinks around the main core so that when the mold opens, part and sprue are carried along with the moving mold half. Subsequently, the central ejector is activated,the ejector plates to move forward so that the ejector pins can push the part off the core.Both mold halves are provided with cooling channels through which cooled water is circulated to absorb the heat delivered to the mold by the hot thermoplastic polymer melt. The mold cavities also incorporate fine vents (0.02 to 0.08 mm by 5 mm) to ensure that no air is trapped during filling. There are six basic types of injection molds in use today. They are: (1) two-plate mold； (2)three-plate mold, (3) hot-runner mold； (4) insulated hot-runner mold； (5) hot-manifold mold； and（ 6） stacked mold. Fig. 2-3 and Fig. 2-4 illustrate these six basic types of injection molds. 1. Two-Plate Mold A two-plate mold consists of two plates with the cavity and cores mounted in either plate.The plates are fastened to the press platens. The moving half of the mold usually contains the ejector mechanism and the runner system. All basic designs for injection molds have this design concept. A two-plate mold is the most logical type of tool to use for parts that require large gates. 2. Three-Plate Mold This type of mold is made up of three plates: (1) the stationary or runner plate is attached to the stationary platen, and usually contains the sprue and half of the runner； (2) the middle plate or cavity plate, which contains half of the runner and gate, is allowed to float when the mold is open； and (3) the movable plate or force plate contains the molded part and the ejector system for the removal of the molded part. When the press starts to open, the middle plate and the movable plate move together, thus releasing the sprue and runner system and degating the molded part.This type of mold design makes it possible to segregate the runner system and the part when the mold opens. The die design makes it possible to use center-pin-point gating. 3. Hot-Runner Mold In this process of injection molding, the runners are kept hot in order to keep the molten plastic in a fluid state at all times. In effect this is a runnerless molding process and is sometimes called the same. In runnerless molds, the runner is contained in a plate of its own. Hot runner molds are similar to three-plate injection molds, except that the runner section of the mold is not opened during the molding cycle. The heated runner plate is insulated from the rest of the cooled mold. Other than the heated plate for the runner, the remainder of the mold is a standard two-plate die. Runnerless molding has several advantages over conventional sprue runner-type molding.There are no molded side products (gates, runners, or sprues) to be disposed of or reused, and there is no separating of the gate from the part. The cycle time is only as long as is required for the molded part to be cooled and ejected from the mold. In this system, a uniform melt temperature can be attained from the injection cylinder to the mold cavities. 4. Insulated Hot-Runner Mold This is a variation of the hot-runner mold. In this type of molding, the outer surface of the material in the runner acts like an insulator for the melten material to pass through. In the insulated mold, the molding material remains molten by retaining its own heat. Sometimes a torpedo and a hot probe are added for more flexibility. This type of mold is ideal for multicavity center-gated parts. 5. Hot-Manifold This is a variation of the hot-runner mold. In the hot-manifold die, the runner and not the runner plate is heated. This is done by using an electric-cartridge-insert probe. 6. Stacked Mold The stacked injection mold is just what the name implies. A multiple two-plate mold is placed one on top of the other. This construction can also be used with three-plate molds and hot-runner molds. A stacked two-mold construction doubles the output from a single press and reduces the clamping pressure required to one half, as compared to a mold of the same number of cavities in a two-plate mold. This method is sometimes called “two-level molding”. 2.3.3 Mold Machine 1. Conventional Injection-Molding Machine In this process, the plastic granules or pellets are poured into a machine hopper and fed into the chamber of the heating cylinder. A plunger then compresses the material, forcing it through progressively hotter zones of the heating cylinder, where it is spread thin by a torpedo. The torpedo is installed in the center of the cylinder in order to accelerate the heating of the center of the plastic mass. The torpedo may also be heated so that the plastic is heated from the inside as well as from the outside. The material flows from the heating cylinder through a nozzle into the mold. The nozzle is the seal between the cylinder and the mold； it is used to prevent leaking of material caused by the pressure used. The mold is held shut by the clamp end of the machine. For polystyrene, two to three tons of pressure on the clamp end of the machine is generally used for each inch of projected area of the part and runner system. The conventional plunger machine is the only type of machine that can produce a mottle-colored part. The other types of injection machines mix the plastic material so thoroughly that only one color will be produced. 2. Piston-Type Preplastifying Machine This machine employs a torpedo ram heater to preplastify the plastic granules. After the melt stage, the fluid plastic is pushed into a holding chamber until it is ready to be forced into the die. This type of machine produces pieces faster than a conventional machine, because the molding chamber is filled to shot capacity during the cooling time of the part. Due to the fact that the injection plunger is acting on fluid material, no pressure loss is encountered in compacting the granules. This allows for larger parts with more projected area. The remaining features of a piston-type preplastifying machine are identical to the conventional single-plunger injection machine. Fig. 2-5 illustrates a piston or plunger preplastifying injection molding machine. 3. Screw-Type Preplastifying Machine In this injection-molding machine, an extruder is used to plasticize the plastic material. The Chapter 2 Plastics Molds 41turning screw feeds the pellets forward to the heated interior surface of the extruder barrel. The molten, plasticized material moves from the extruder into a holding chamber, and from there is forced into the die by the injection plunger. The use of a screw gives the following advantages:(1) better mixing and shear action of the plastic melt； (2) a broader range of stiffer flow and heatsensitive materials can be run； (3) color changes can be handled in a shorter time, and (4)fewer stresses are obtained in the molded part. 4. Reciprocating-Screw Injection Machine This type of injection molding machine employs a horizontal extruder in place of the heating chamber. The plastic material is moved forward through the extruder barrel by the rotation of a screw. As the material progresses through the heated barrel with the screw, it is changing from the granular condition to the plastic molten state. In the reciprocating screw, the heat delivered to the molding compound is caused by both friction and conduction between the screw and the walls of the barrel of the extruder. As the material moves forward, the screw backs up to a limit switch that determines the volume of material in the front of the extruder barrel. It is at this point that the re- semblance to a typical extruder ends. On the injection of the material into the die, the screw moves forward to displace the material in the barrel. In this machine, the screw performs as a ram as well as a screw. After the gate sections in the mold have frozen to prevent backflow, the screw begins to rotate and moves backward for the next cycle. Fig.2-5 shows a reciprocating-screw injection machine. There are several advantages to this method of injection molding. It more efficiently plasticizes the heat-sensitive materials and blends colors more rapidly, due to the mixing action of the screw. The material heat is usually lower and the overall cycle time is shorter. 2.1 计算机辅助设计和计算机辅助 CAD/CAM 纵观人类工业社会的历史 ,许多发明获得了专利，整个新技术也逐渐形成。惠特尼的通用零件的思路 ,瓦特的蒸汽机和福特的流水线不仅是几个少数的发展阶段而且是人类工业的几个重要的发展阶段。正如我们所知的任何一个这样的发展都影响了制造业并且在历史的挂钩中赢得了这些个体应得的承认。或许单个的发展影响制造业更快，而影响比先前技术更大的是数字电脑。 自从电脑技术 出现以来 ,制造业人员一直希望自动化设计过程和使用数据库开发自动制造过程。计算机辅助设计 /计算机辅助制造 (CAD/CAM),当成功执行 ,应该消除存在于设计和生产部件之间的传统屏障。 CAD/CAM 意味着用电脑进行设计和制造过程。因为 CAD/CAM 的出现其他方面也 发展起来： 计算机图形 CG 电脑辅助工程 CAE 电脑辅助设计和绘图设计 CADD 计算机辅助工艺规划 CAPP 这些附带条件是指包括解答 11 项具体方面的 CAD / CAM 的概念而 CAD / CAM 本身就是一个更广泛平台 ,它是在生产的自动化和集成的核心。 CAD/CAM 成功的一个关键目标是创建可以用来产品的数据当成功实施的产品设计的发展数据库。 CAD/CAM 致力于一个在设计和生产部件分享通用的数据库的公司。 交 互 式 计 算 机 图 形 学 (ICG) 在 CAD/CAM 扮演一个重要角色，虽然 ICG 用途上 ,设计师冲洗被设计的产品的一个图表图象 ,当存放电子上组成图表图象的数据。图表图象在二维可以被提出二维 (2-D)三维 (3-D)或者固体格式化。 ICG 图象被修建使用这样基本的几何字符象点、线、圈子和曲线。一旦生成 ,这些图象可以容易地 被编辑和被操作用各种各样的方式包括扩大、减少、自转和运动。 lCG 系统有三个主要成份 ,1)硬件 ,包括计算机和各种各样的外围设备 ； 2)软件 ,包括系统的计算机程序和技术指南 ； 3)设计师 ,最重要三个组分。 ICG 系统的典型的硬件构造包括一个电脑 ,一个显示终端、磁盘的一个驱动器单位，一个硬盘或者两个 ； 并且输入 -输出设备例如键盘，绘图器和打印机。这些设备 ,与软件一起，是现代工具设计师用以开发和提供他们的设计的。 ICG 系统能通过允许人的设计师集中提高设计过程于设计过程的智力方面，例如概 念化 和做出基于评断的决定。计算机执行它更好地适合，例如数据的各种各样的反复操 作数学演算、存贮与检索，和各种各样的反复操作比如交叉涂画。 2.11CAD/CAM 的基本原理 CAD/CAM 的基本原理类似于制造业以前证明技术为基础的提高。它来源于一个需要不断提高生产率，质量和反过来的竞争力。还有其他原因，可能使公司从手工流程转换为 CAD / CAM 的。 提高生产力 质量更好 更好的沟通 共同的数据库与制造 降低建造成本原型 更快的响应客户 2.12 CAD/CAM 的历史发展 CAD/CAM 的历史发展在计算机科技的发展之后紧密跟随了和对应了 ICG 技术的发展。使得 CAD/CAM 的重大发展在 20 世纪 50 年代和 60 年代初期末期开始了。最先发展的是在麻省理工学院 (MIT)进行的刀具控制程序自动编制系统 (APT)计算机程式语言。 APT 的目的是将数字控制器部分方案的开发进行简化。它是为此计划被使用的第一 种计算机语言。 APT 语言代表了主要步往制造过程的自动化。 在 CAD/CAM 的历史中的另一重大发展在 APT 之后 紧密跟随了，也被开发在 MIT，一个项目被称之为草图项目。这个项目， Ivan Sutherland 诞生了 ICG 的概念。草图项目是第一个计算机在实时中被用于生成和操作在 CRT 中显示的图表图象。 在 20 世纪 60 年代和 70 年代的剩下的人中， CAD 继续被开发，多家厂商提出了自己的名字生产和销售生产全套 CAD 系统。这是一个完整的系统方案包括硬，软件，销售和维修培训。这些早期的系统被大型机和小型机左右。因此 ,它们太昂贵一直不能实现大规模被中小型制造业接受。 在 20 世纪 70 年代末之前 微型计算机在 CAD/CAM 的更加一步的发展中最终将扮演一个重要角色变得日益清晰。然而早期的微型计算机没有配置为 ICG 需要的处理能 力、记忆能力或者图表能力。结果 ,早期尝试在微型计算机附近配置 CAD/CAM 系统的尝试失败了。 在 1983 IBM 介绍了 IBM PC 第一个有处理能力、记忆能力和图表能力可被用于 CAD/CAM 的微型计算机。这使得了 CAD/CAM 供营商的数量的迅速增量。截止到 l989 安装 CAD/CAM 设施的数量的微型计算机等于安装在大型机和小型机上的数量 。 2.13 CAD 到 CAM 接口 使用 CAD/CAM，设计和制造之间的真正的接，是他们分享的共同的数据库。这是 CAD/CAM 精华。 手工设计和制造，工程师审阅在设计，起草生产图纸和其他文件传达设计的每步，生产人员使用图画开发处理计划，车间人员负责实际上的生产。 与旧方法相比 ,直到设计和起草人员完成他们的工作，生产人员都没有看到它。设计和起草部门做他们的工作，把计划再扔过墙再让制造部门做他们的工作。这种做法导致沟通的不畅通以及制造部分与设计部分的脆弱关系。其结果是生产力 的损失。 使用 CAD/CAM,生产人员可以尽快进入创建的数据的设计阶段。在任何一点在设计过程中，他们可以调用数据库中的信息并使用它。因为数据分享从开始到结束，所以当设计成到准备生产时没有一点吃惊。 当设计师创造时数据库和起草者提供的设计，使生产人员也成为项目的一部分。生产人员生产产品的任何需要都被包含在一个共同的数据库里。数学模型，图形图像，用料清单，零件清单，尺寸，从区位尺寸到公差规格和原材料明细表都包含数据库 。 2.1 Computer-aided Design and Computer-aided Manufacturing(CAD/CAM) Throughout the history of our industrial society ,many invention have been patented and whole new technologies have evolved .Whitney is concept of interchangeable parts ,Watts steam engine,and Ford is assembly line are but a few developments that are most noteworthy during our industrial period . Each of these developments has impacted manufacturing as we know it,and has earned these individuals deserved recognition in 0ur history hooks. Perhaps the single development that has impacted manufacturing more quickly and significantly than any previous technology is the digital computer. Since the advent 0f computer technology, manufacturing professionals have wanted to automate the design process and use the database developed therein for automating manufacturing processes. Computeraided design,computer-aided manufacturing (CAD/CAM),when successfully implemented, should remove the “wall” that has traditionally existed between the design and manufacturing components . CAD/CAM means using computers in the design and manufacturing processes. Since the advent of CAD/CAM other terms have developed: Computer graphics(CG) Computeraided engineering(CAE) Computer-aided design and drafting(CADD) Computer aided process planning(CAPP) These spin-off terms a11 refer to specific aspects of the CAD/CAM concept CAD/CAM itself is a broader,more inclusive term. It is at the heart of automated and integrated manufacturing. A key goal of CAD/CAM is to produce data that can be used in manufacturing a product while developing the database for the design of that product When successfully implemented, CAD/CAM involves the sharing of a common database between the design and manufacturing components of a company, Interactive computer graphics (ICG) plays an important role in CAD/CAM, Though the use of ICG, designers develop a graphic image of the product being designed while storing the data that electronically make up the graphic image. The graphic image can be presented in a two-dimensional (2-D) , three-dimensional(3-D),or solids format. ICG image are constructed using such basic geometric characters as points, lines, circles, and curves. Once created, these images can be easily edited and manipulated in a variety of ways including enlargements,reductions, rotations, and movements. An lCG system has three main components :1 ) hardware, which consists of the computer and various peripheral devices； 2) software, which consists of the computer programs and technical manuals for the system ； and 3) the human designer, the most important of the three components. A typical hardware configuration for an ICG System include a computer,a display terminal, a disk drive unit for floppy diskettes, a hard disk, or both； and input/output devices such as a keyboard,plotter, and printer. These devices, along with the software, are the tools modern designers use to develop and document their designs. The ICG systems could enhance the design process by allowing the human designer to focus on the intellectual aspects of the design process, such as conceptualization and making judgment-based decisions. The computer performs tasks for which it is better suited, such as mathematical calculations, storage and retrieval of data and various repetitive operations such as crosshatching. 2.1.1 Rationale for CAD/CAM The rationale CAD/CAM is similar to that used to justify any technology-based improvement in manufacturing . It grows out of a need to continually improve productivity,Quality and in turn competitiveness. There are also other reasons why a company might make a conversion from manual processes to CAD/CAM: increased productivity better quality better communication common database with manufacturing reduced prototype construction costs faster response to customers 2.12 Historical Development of CAD/CAM The historical development of CAD/CAM has followed close behind the development of computer technology and has paralleled the development of ICG technology. The significant developments leading to CAD/CAM began in the late 1950s and early 1960s. The first of these was the development, at Massachusetts Institute of Technology (MIT),of the Automatically Programmed Tools (APT) computer programming language. The purpose of APT was to simplify the development of parts programs for numerical control machines. It was the first computer language to be used for this purpose. The APT language represented a major step toward automation of manufacturing processes. Another significant development in the history of CAD/CAM followed close behind APT, also developed at MIT, was called the Sketchpad project. With this project, Ivan Sutherland gave birth to the concept of ICG.