本科毕业设计(论文)外文资料翻译.doc

华南理工大学成人高等学历教育本科毕业设计（论文）外文资料翻译学生姓名辛柳军学号10561085301501045年级、专业机械工程及自动化英文原文题目Mechanical Design and System Architecture of a Tracked Vehicle Robot for Urban Search and Rescue Operations 中文译名注塑模和注塑机、模具冷却系统、型腔和型芯英文原文出处王浩刚,曹艳清.模具专业英语.人民邮电出版社,2005翻译水平评定（五级制）指导教师签名 译文（英译中）：第1课 注塑模和注塑机1. 注塑模尽管成型某些热固性材料的方法取得了一定进步，但注塑模主要（还是）用来生产热塑性塑件。（这主要是因为）热固性塑料熔体在很短时间内就会固化和硬化，在从料斗向模具型腔注入热固性塑料熔体的过程中，也会出现这种情况，这个问题一直非常难解决。注塑成型原理和铸造十分相似。注塑成型的工艺过程包括：首先把料斗中的粉状或粒状的塑料混合物依次输送到计量区和熔化区，然后再注射到模具型腔中，经过短时冷却后，开模，推出成型塑件。注塑机分为手动、半自动及全自动操作。注塑模具具有以下优点：（i）较高的成型速度使大批量生产成为可能；（ii）为成型具有不同使用性能的热塑性材料提供了较宽的选择；（iii）可以成型带有螺纹的塑件、侧向凹陷的塑件、带有侧孔的塑件以及较大的薄壁件。2、注塑机熔融塑料注入模具中通常有几种方式。在大型注塑机上常采用往复螺杆的注入方式，如图1-1所示。螺杆同时具有注射和塑化的功能。树脂原料进入旋转的螺杆时，要经过图示的三个区域：喂入区、压实区和计量区。经过喂入区后，为压实树脂原料，螺杆螺旋部分的深度逐渐降低，同时传递树脂原料间因剪切作用而产生的热量，使原料呈半流动状态。在计量区，螺杆表面的加热装置对熔体进一步加热。当熔体充满螺杆前部区域时，螺杆在熔体压力的作用下后退，触动限位开关使液压缸工作，在液压力的作用下推动螺杆向前运动，将熔融塑料注射到闭合的模具型腔中。防倒流阀能够阻止受压熔体倒流进螺杆的螺旋区。注塑机的锁模系统所提供的锁模力由（塑件在分型面的投影）尺寸决定，锁模力以吨为单位。通常靠经验来决定塑件所需要的锁模力总吨数，一般在塑件投影面积上每平方英寸需要作用两吨锁模力。如果熔体流动困难或塑件较薄，锁模力应提高到三到四吨。许多往复螺杆式注塑机能生产热固性塑料。以前，热固性塑料由挤出模具或传递模具生产。热固性塑料熔体在模具内固化或发生聚合反应，并在温度为375C410C范围内推出。热塑性塑料熔体必须在模具内冷却成型，以保证推出时不发生变形。这种固性循环速度很快。当然，生产热塑性塑件时，模具必须被加热，而不是冷却。第3课 模具冷却系统注塑生产的基本原理是把高温熔体注入模具型腔，熔体在型腔内迅速冷却到固化温度，并保持一定形状。由于模具温度在一定程度上控制塑件的整个成型周期，因此（在生产中）非常重要。熔体在高温模具内流动顺畅，但固化塑件推出前，一定的冷却阶段是必不可少的。另一方面，熔体在温度较低放的模具中固化较快，但有可能造成塑件末端填充不满。因此必须在这两种极端条件中选择一个平衡点，以取得最佳的成型周期。模具的工作温度与几种因素有关，包括成型材料的等级与类型、熔体在型腔内的流动路线、塑件壁厚以及浇注系统长度等。使用比充模要求稍高的温度注塑比较有利，这样生产的塑件熔接痕少、流痕不明显，其他缺陷也较少，因此，提高了塑件的表面质量。为保持模具和塑料熔体之间所需的温差，水（或其他液体）在模具上的通道或通孔中循环。这些通道或通孔称为流道5或水道，整个水道系统称为冷却循环系统。在充模阶段，温度最高的熔体位于进入口，即浇口附近；温度最低的熔体位于距进入口最远的地方。冷却介质在模具内循环时，介质温度将升高。因此，为使塑件表面获得均匀的冷却速率，冷却通道的入口应开设在高温塑件附近，受热后冷却介质温度升高，出口开设在低温塑件附近。然而由下面讨论可知， 这种理想状态并不总是可行的。为避免不必要的模具费用，设计者往往凭借经验设计冷却通道。冷却水（或其他冷却介质）回路所需的部件在市场上就可以买到。这些部件通过软管与模具直接连在一起，通过这些部件（形成的冷却回路）模具温度便控制在要求的范围内。但是，使用这种直接与冷水相连的冷却回路却是不可能精确地控制模具温度的。为模具提供适合的冷却系统是设计者的责任。通常，最简单的冷却系统是在模板上纵向钻出通孔。然而，对于精密模具，这不是最有效的冷却方法。然而，使用钻孔的方式加工冷却水道时，冷却通道与塑件的距离一定不能太近（即距离小于16mm），如果距离太近，有可能引起整个型腔的温度发生显著改变，使塑件出现问题。由于冷却通道不能距离同一模板上任何其他的孔道太近，这使得冷却回路的布局通常比较复杂。可以想到模板上存在大量的孔道或凹陷，用来安装推杆、导柱、导套、浇口套以及镶件等。冷却通道与其他孔道之间的安全距离为多远，很大程度上取决于所需的冷却通道的钻入深度。流道深度较深时，钻头有偏离预定（加工）路线的趋势。常用的规则是钻入深度达到150mm是的冷却水道与其他孔道距离不小于3mm，比这更深的流道所需的距离增加到5mm。为获得最佳的冷却回路，设计初期就考虑冷却回路的位置不失为一种好办法。其他模具零件，如推杆、导套等，根据需要确定安装位置。第11课 型腔和型芯模具的型腔和型芯分别形成塑件内部和外部形状，型腔（形状）决定了塑件形状。接下来我们简要说明选择哪种方式把型腔和型芯安装在模具中。这些方式可以归属为两大类，即整体式和镶拼式（结构）。另一种组成型腔的方式为加入拼块或滑块。1、整体式型腔和型芯板当型腔或型芯由一块大的钢板或钢块加而成，或者铸成一体，不需使用支撑件而形成一块模板时，就构成整体式型腔和型芯板。这种设计因具有强度高，尺寸小和成本低的特性，主要应用在单型腔模具中。整体式型腔和型芯一般不用在多型腔模具中，因为（多型腔模具）设计时必须考虑一些其它因素，例如模具的找正等。在众多模具制造的方法中，用于加工整体式型腔或型芯板的方法主要有两种：（a)使用传统机床对粗锻钢材坯料直接加工；（b)利用精确的熔模铸造技术将坯料加工成型腔和型芯。用于制造型腔和型芯的坯料京城需要特殊的处理过程。通常，4.25%的镍铬钼合金钢（BS970-835M30）是生产整体式模板的指定材料，这采用直接的机加方式。精确的熔模铸造常常用来加工高铬钢。2、镶拼式型腔和型芯对于成型部位复杂的模具和多腔模具，也像整体式模具那样用一块钢材加工型腔和型芯并不容易。（如果采用整体式结构）加工顺序和操作过程将变地非常负责，成本也高。因此镶拼式装配方式替代了整体式。镶拼式型腔是用小刚块加工（装配）而成。加工后的小钢块作为镶件，形成公模（型芯）部分的称为型芯镶件，相反地，形母模（型腔）部分的称为型腔镶件。然后，把这些镶件牢固地安装在被称为垫板的孔中，垫板直接由实芯钢板或钢块加工而成。这些安装孔有的是由垫板的局部凹陷形成，有的是在垫板直接加工形成。在有一种方式中，垫板后部还要增加一块模板，起加固作用，确保镶件安装到位。3、整体式和镶拼式的优缺点整体式和镶拼式结构均有优点，这取决于塑件尺寸和形状、模具的复杂程度、所需的是单腔模具还是多腔模具，以及模具胡制造成本等。通常，一旦塑件的（形状、尺寸）等特性确定后，采用哪种形式的型腔和型芯就已经确定了。在不同的章节中，（我们）已经讨论过型腔和型芯的安装方式所涉及的问题，例如成本等。但是，为使读者在处理特殊问题时更容易知道重点所在，（我们）将用一定的章节再次讨论每种结构优缺点的对比。毫无疑问，对于单型腔模具，无论是简单还是复杂，整体式型腔是首选方式。这样，模具的强度高，尺寸小，成本低，而冷却系统的设计却比镶拼式模具的简单、方便。设计时需要常记于心的是，适当地使用镶件可以简化模具型腔的加工制造难度。对于多腔模具，选择哪种方式不是很明显。大多数多腔模具采用镶拼式结构，这种结构加工简单，装配容易，模具成本低，这是影响选择哪种结构形式的最重要因素。一种非常简单且具有很多优点的设计形式是采用一种形式设计模板，而采用另一种形式设计模具的其他部分。例如，采箱形组件设计多腔模具。型腔板设计成小型整体式模板，满足模具高强度的要求，型芯板则设计成镶拼式，可以简化模板加工过程，并且能根据模具需要进行调整。原文 (英文) ：Lesson 1 The Injection Molding and Machine1. The injection moldingInjection molding is principally used for the production of the thermoplastic parts, although some progress has been made in developing a method for injection molding some thermosetting materials. The problem of injecting a melted plastic into a mold cavity from a reservoir of melted material has been extremely difficult to solve for thermosetting plastics which cure and harden under such conditions within a few minutes. The principle of injection molding is quite similar to that of die-casting. The process consists of feeding a plastic compound in powdered or granular form from a hopper through metering and melting stages and then injecting it into a mold. After a brief cooling period, the mold is opened and the solidified part ejected. Injection-molding machines can be arranged for manual operation, automatic single-cycle operation, and full automatic operation. The advantage of injection molding are: (i) a high molding speed adapted for mass production is possible; (ii) there is a wide choice of thermoplastic materials providing a variety of useful properties; (iii) it is possible to mold threads, undercuts, side holes, and large thin sections.2. The injection-molding machineSeveral methods are used to force or inject the melted plastic into the mold. The most Commonly use system in the larger machines is the in-line reciprocating screw, as shown in figure1-1. The screw acts as a combination injection and plasticizing unit. As the plastic is fed to the rotating screw, it passes through three zones as shown: feed, compression, and metering. After the feed zone, the screw-flight depth is gradually reduced, forcing the plastic to compress. The work is converted to heat by shearing the plastic, making it a semifluid mass. In the metering zone, additional heat is applied by conduction from the barrel surface. As the chamber in front of the screw becomes filled, if forces the screw back, tripping a limit switch that activates a hydraulic cylinder that forces the screw forward and injects the fluid plastic into the closed mold. An antiflowback valve prevents plastic under pressure from escaping back into the screw flights.The clamping force that a machine is capable of exerting is part of the size designation and is measured in tons. A rule-of thumb can be used to determine the tonnage required for particular job. It is based on two tons of clamp force per square inch of projected area. If the flow pattern is difficult and the parts are thin, this may have to go to three or four tons.Many reciprocating-screw machines are capable of handing thermosetting plastic materials. Previously these materials were handled by compression or transfer molding. Thermosetting materials cure or polymerize in the mold and are ejected hot in the range of 375c410c. Thermoplastic parts must be allowed to cool in the mold in order to remove them without distortion. Thus thermosetting cycles can be faster. Of course the mold must be heated rather than chilled, as with thermoplastics.Lesson3 Mould coolingOne fundamental principle of injection molding is that hot material enters the mould, where it cools rapidly to a temperature at which it solidifies sufficiently to retain the shape of the impression. The temperature of the mould is therefore important as it governs a portion of the overall molding cycle. While the melt flows more freely in a hot mould, a greater cooling period is required before the solidified molding can be ejected. Alternatively, while the melt solidifies quickly in a cold mould, it may not reach the extremities of the impression. A compromise between the two extremes must therefore be accepted to obtain the optimum molding cycle.The operating temperature for a particular mould will depend on a number of factors which include the following: type and grade of material to be molded; length of flow within the impression; wall section of the molding; length of the feed system, etc. It is often found advantageous to use a slightly higher temperature than is required just to fill the impression, as this tends to improve the surface finish of the molding by minimizing weld lines, flow marks and other blemishes. To maintain the required temperature differential between the mould and plastic material, water (or other fluid) is circulated through holes or channels within the mould. These holes or channels are termed flow-ways or water-ways and the complete system of flow ways is termed the circuit.During the impression filling stage the hottest material will be in the vicinity of the entry point, i.e. the gate, the coolest material will be at the point farthest from the entry. The temperature of the coolant fluid, however, increases as it passes through the mould. Therefore, to achieve an even cooling rate over the molding surface, it is necessary to locate the incoming coolant fluid adjacent to “hot” molding surfaces and to locate the channels containing “heated” coolant fluid adjacent to “cool” molding surfaces. However, as will be seen from the following discussion, it is not always practicable to adopt the idealized approach and the designer must use a fair amount of common sense when laying out coolant circuits if unnecessarily expensive moulds are to be avoided.Units for the circulation of water (or other fluids) are commercially available. These units are simply connected to the mould via flexible hoses, with these units the moulds temperature can be maintained within close limits. Close temperature control is not possible using the alternative system in which the mould is connected to a cold water supply.It is the mould designers responsibility to provide an adequate circulating system within the mould. In general, the simplest systems are those in which holes are bored longitudinally through the mould plates. However, this is not necessarily the most efficient method for a particular mould.When using drillings for the circulation of the coolant, however, these must not be positioned too close to the impression (closer than 16mm) as this is likely to cause a marked temperature variation across the impression, with resultant molding problems.The layout of a circuit is often complicated by the fact that flow ways must not be drilled too close to any other hole in the same mould plate. It will be recalled that the mould plate has a large number of holes or recesses, to accommodate ejector pins, guide pillars, guide bushes, sprue bush, inserts, etc. How close it is safe to position in a flow way adjacent to another hole depends to a large extent on the depth of the flow way drilling required. When drilling deep flow ways, there is a tendency for the drill to wander off its prescribed course. A rule which is often applied is that for drillings up to 150mm deep the flow way should not be closer than 3mm to any other hole. For deeper flow ways this allowance is increased to 5mm.To obtain the best possible position for a circuit, it is good practice to lay the circuit in at the earliest opportunity in the design. The other mould items such as ejector pins, guide bushes, etc., can then be positioned accordingly.Lesson 11 The cavity and coreThe cavity and core give the molding its external and internal shapes respectively, the impression imparting the whole of the form to the molding. We then proceed to indicate alternative ways by which the cavity and core could be incorporated into the mould and found that these alternatives fell under two main headings, namely the integer method and the insert method Another method by which the cavity can be incorporated is by means of split inserts or splits.1. Integer cavity and core platesWhen the cavity or core is machined from a large plate or block of steel, or is cast in one piece, and used without bolstering as one of the mould plates, it is termed an integer cavity plate or integer core plate. This design is preferred for single-impression moulds because of the strength, smaller size and lower cost characteristics. It is not used as much for multi-impression moulds as there are other factors such as alignment which must be taken into consideration.Of the many manufacturing processes available for preparing moulds only two are normally Used in this case. These are (a)a direct machining operation on a rough steel forging or blank using the conventional machine tolls, or(b) the “precision” investment casting technique in which a master pattern is made of the cavity and core. The pattern is then used to prepare a casting of the cavity or core by a special process. A 4.25% nickel-chrome-molybdenum steel(BS 970-835 M30) is normally specified for integer mould plates which are to be made by the direct machining method. The precision investment casting method usually utilizes a high-chrome steel.2. Inserts cavity and core For moulds containing intricate impressions and for multi-impression moulds, it is not satisfactory to attempt to machine the cavity and core plates from single blocks of steel as with integer moulds. The machining sequences and operation would be altogether too complicated and costly. The insert-bolster assembly method is therefore used instead.The method consists in machining the impression out of small blocks of steel. These small blocks of steel are known, after machining, as inserts, and the one which forms the male part is termed the core insert and, conversely, the one which forms the female part the cavity insert. These are then inserted and securely fitted into holes in a substantial block or plate of steel called a bolster. These holes are either sunk part way or are machined right through the bolster plate. In the latter case there will be a plate fastened behind the bolster and this secures the insert in position.3. For and against integer and insert-bolster methodsBoth the integer and the insert-bolster methods have their advantages depending upon the Size, the shape of the molding, the complexity of the mould, whether a single impression or a multi-impression mould is desired, the cost of making the mould, etc. It can therefore be said that in general, once the characteristics of the mould required to do a particular job have been weighed up, the dec