外文翻译---冲模及复合模设计.docx

外文资料翻译 Stamping and Punching Dies, Compound Die DesignA compound die performs only cutting operations (usually blanking and piercing) which are completed during a single press stroke. A characteristic of compound dies is the inverted position of the blanking die and blanking punch which also functions as the piercing die. The die is fastened to the upper shoe and the blanking punch having a tapered hole in it and in the lower shoe for slug disposal is mounted on the lower shoe. The guide pins, or posts, are mounted in the lower shoes. The upper shoes contains bushing which slide on the guide pins. The assembly of the lower and upper shoes with guide pins and bushing is a die set. Die sets in many sizes and designs are commercially available.On the upstroke of the press slide, the knock out rod of the press strikes the ejector plate, forcing the ejector tie rod and shedder downward, thus pushing the finished work piece out of the blanking die. Four special shoulder screws (stripper bolts), commercially available, guide the stripper in its travel and retain it against the preload of its springs. The blanking die as well as the punch pad is screwed and doweled to the upper shoe.1、 Bending Die Bending is the uniform straining of material, usually flat sheet or strip metal, around a straight axis which lies in the neutral plane and normal to the lengthwise direction of the sheet or strip. Metal flow takes place within the plastic range of the lengthwise direction of the bend retains a permanent set after removal of the applied stress. The inner surface of a bend is in compression; the outer surface is in tension. A pure bending action does not reproduce the exact shape of the punch and die in the metal; such a reproduction is one of forming. The neutral axis is the plane area in bend metal where all strain is zero.2、 Bending Methods Metal sheet or strip, supported by a V bending, produces a bend having an included angle which may be acute, obtuse, or of 90. Friction between a spring-loaded knurled pin in the Vee of a die and the part will prevent or reduce side creep of the part during its bending. Other methods are Z-bending edge bending and U-bending etc.3、 Drawing DieDrawing is a process of changing a flat, precut metal blank into a hollow vessel without excessive wrinkling, thinning, or fracturing. The various forms produced may be cylindrical or box-shaped with straight or tapered sides or sides or a combination of straight, tapered, or curved sides. The size of the parts may vary from 0.25mm diameter or smaller, to aircraft or automotive parts large enough to require the use of mechanical handing equipment.4、 Single-action Die The simplest type of draw dies is one with only a punch and die. One type of drawing die use in a single-action press is shown in Fig.3-4. This die is plain single-action type where the punch pushes the metal blank into the die, using a spring-loaded pressure pad to control the metal flow. The punch has an air vent to eliminate suction which would hold the cup on the punch and damage the cup when it is stripped from the punch by the pressure pad. The sketch shows the pressure pad fitting the stop pin, which acts as a spacer that an even and proper pressure is exerted on the blank at all times. If the spring pressure pad is used without the stop pin, the more the springs are depressed, the greater the pressure exerted on the blank, thereby limiting the depth of drawing. Because of limited pressures obtainable, this type of die should be used with light- gage stock and shallow depths. Mold Cavities and Cores The cavity and core give the molding its external shapes respectively, the impression imparting the whole of the form to the molding. When then proceeded to indicate alternative ways by which the cavity and core could be incorporated into the mold and we 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.When 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 mold plates, it is termed an integer cavity plate or integer core plate. This design is preferred for single-impression molds because of characteristics of the strength, smaller size and lower cost. It is not used as much for multi-impression molds as there are other factors such as alignment which must be taken into consideration.Of the many manufacturing processes available for preparing molds only two are normally used in this case. There are a direct machining operation on a rough steel forging or blank using the conventional machine tool, or 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 or special process. A 4.25% nickel-chrome-molybdenum steel (BS 970-835 M30) is normally specified for integer mold plates which are to be made by the direct machining method.The precision investment casting method usually utilizes a high-chrome steel. For molds containing intricate impressions, and for multi-impression molds, it is not satisfactory to attempt to machine the cavity and core plates from single blocks of steel as with integer molds. The machining sequences and operation would be altogether too complicated and costly. The inset-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 inserts. 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.Both the integer and the insert-bolster methods have their advantages depending upon the size, the shape of the molding, the complexity of the mold, whether the single impression or a multi-impression mold is desire, the cost of making the mold, etc. It can therefore be said that in general, once the characteristics of the mold required to do a particular job which have been weighed up, the decision as to which design to adopt can be made.Some of these considerations have already been discussed under various broad headings, such as cost, but to enable the reader to weigh them up more easily, when faced with a particular problem, the comparison of the relative advantages of each system is discussed under a number of headings.Unquestionably, for single impression molds integer design is to be preferred irrespective of whether the component form is a simple or a complex one. The resulting mold will be stronger, smaller, less costly, and generally incorporate a less elaborate cooling system than the insert-bolster design. It should be borne in mind that local inserts can be judiciously used to simplify the general manufacture of the mold impression.For multi-impression molds the choice is not so clear-cut. In the majority of cases the insert-bolster method of construction is used, the ease of manufacture, mold alignment, and resulting lower mold costs being he overriding factors affecting the choice. For components of very simple form it is often advantageous to use one design for one of the mold plate and the alternative design for the other. For example, consider a multi-impression mold for a box-type component. The cavity plate could be of the integer design to gain the advantages of strength, thereby allowing a smaller mold plate, while the core plate could be of insert-bolster design which will simplify machining of the plate and allow for adjustments for mold alignment. 冲模及复合模设计复合模是指在一次冲压行程中完成几道冲裁工序（通常包括落料和冲孔）的模具。复合模的特点是能够调转落料模和冲孔模（凸模和凹模）的位置，即落料模也可以作为冲孔模。冲头和内部带有锥孔的落料凹模被固定在上模座板上，下模座板上开有推杆放置孔。导料销或导柱安装在下模座上，导套安装在上模座上且可以沿导柱滑动。上、下模座（带有导柱和导套）组合成模架。模架在市场上可以买到，且有多种尺寸和结构供选择。 在冲压机滑块的向上行程中，冲压机的打料杆接触到推件板，作用在连接推杆上的力使卸料装置下移，将冲压件从落料凹模中推出。四个特殊的带肩螺钉（卸料螺钉，在市场上可以买到）引导卸料装置移动，并使其抵抗弹簧的预压。与冲孔凹模一样，落料凹模也用螺栓和销钉安装在上模座上。1、 弯曲模弯曲是指材料（通常是板料或条料）围绕位于中性面上纵向的直线轴产生均匀变形的冲压工艺。因为弯曲时金属流动发生在金属塑性变形范围内，所以去除施加的外力后，弯曲将保持永久的变形。弯曲件的内表面处于压缩状态，外表面处于拉伸状态。单一的弯曲工序并不能使金属材料呈现出与模具的凹模或凸模完全一致的状态，这种复制工艺也是一种成型方法。在受到弯曲作用的金属中，中性面是弯曲金属上张力为零的平面区域。2、 弯曲方式 放置在V 形支撑块中的板料或条料在楔形冲头的作用下压入V形凹模，这类弯曲方式称为V形弯曲。V形弯曲能够生产带有钝角、锐角或直角的弯曲件。V形模具内的弹簧加载压销和零件之间的摩擦力将组织或减少弯曲时边缘的移动。其他弯曲方式有Z形弯曲、侧边弯曲和U形弯曲等。3、 拉深模拉深是把一定形状的金属平板制成空心零件而不发生起皱、变薄或开裂现象的冲压工序。不同形状的拉深可得到不同圆柱形或盒形制件，这些侧壁的形式有直壁、锥形壁、直壁和锥形壁混合的侧壁以及曲面壁。拉深件的尺寸相差很大，从直径为0.25mm或更小的拉深件，到足以覆盖机械设备的航天器或汽车覆盖件。4、 单次拉深模最简单的拉深模指带有一对凹模和凸模，这种结构是简单的单动冲压类型，冲头把金属胚料压入凹模，利用弹压板控制金属流动。冲头上开设的排气孔能够消除推出拉深件时产生的真空吸力，这种真空现象能使杯形拉深件包紧在冲头上，若有压料板强制脱模，则会损坏杯形件。模具装有压料板，压料板起压料作用冲压时能为冲头外的胚料提供均匀而合适的压力。如果弹簧板没有安全垫圈，那么弹簧压缩量越多，板料承受的压力就越大，这将限制拉深的程度。由于有效的压力有限，故这种拉深模使用于所需冲压力较小及深度较浅的冲压件。 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外部形状，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，这些方式可归纳为两大类，即整体式和镶拼式。另一种组成型腔的方式是加入拼块或滑块。当型腔或型芯由一块大的钢板或刚块加工而成，或者铸成一体，不需使用支承板件而形成一块模板时，就构成整体式型腔板