冲模及复合模设计(Stamping and Punching Dies)

冲模及复合模设计(Stamping and Punching Dies)(中文9900字,英文6200字)
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。

Stamping and Punching Dies
Compound Die Design A 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 Die Drawing 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.