1、 外文资料 Piercing Die Design A complete press tool for cutting two holes in work material at one stroke of the press, classified and standardized by a large manufacturer as a single-station piercing die. Any complete press tool ,consisting of a pair( or a combination of pairs ) of mating members for pr
2、oducing pressworked ( stamped ) parts, including all supporting and actuating elements of the tool, is a die .Pressworking terminology commonly defines the female part of any complete press tool as a die. The guide pins, or posts,are mounted in the lower shoe .The upper shoe contains bushings which
3、slide on the guide pins .The assembly of the lower and upper shoes with guide pins and bushings is a die set .Die sets in many sizes and designs are commercially. A punnch holder mounted to the upper shoe holds two round punches (male members of the die) which are guided by bushings inserted in the
4、stripper.A sleeve, or quill, encloses one punch to prevent its buckling under pressure from the ram of the press .Afer penetration of the work material,the two punches enter the die bushing for a slight distance. The female member, or die, consists of two die bushings inswetwd in die block. Since th
5、is press tool punches holes to the diameters required, the diameters of the die bushings are larger than those of the punches by the amount of clearance. Since the work material stock or workpiece can cling to a punch on the upstroke, it may be necessary to strip the material from the punch .Spring-
6、loaded strippers hold the work material against the die block until the punches are withdrawn from the punched holes .A workpiece to be pierced is commonly held and located in a nest composed of flat plates shaped to encircle the outside part contours. Stock is positioned in dies by pins, blocks, or
7、 other types of stops for locating before the downstroke of the ram. Blanking Die Design A die replace the die bushing and the two piercing punches are replaced by one blanking punch .A stock stop is incorporated instead of nest plates .This is a drop-through design since the finished blanks drop th
8、rough the die , the lower shoe , and the press bolster . Large blanks are commonly produced by an inverted die in which the die is mounted to the upper shoe with the punch secured to the bottom shoe . The passing of a large blank through the bolster is often impractical but its size may necessitate
9、sectional die design . Draft ,or angular clearance in an inverted die is unnecessary because the blank does not pass through it . For ease of construction , regrinding , and strength the cutting edges of each section should not include points and intricate contours . The springs-loaded stripper is m
10、ounted on the lower shoe ； it travels upward in stripping the stock from the punch fastend to the lower shoe . Stripper bolts hold and guide the stripper in its travel . On the upstroke of the ram , the upper end of the knockout rod strikes an arm on the press frame , which forces the lower end of t
11、he rod downward , through the die , and ejects the finished blank from the die cavity . A stop collar retains the rods and limits their travel . Center of Pressure If the coutour to be blanked is irregularly shaped , the summation of shearing forces on one side of the center of the ram may greatly e
12、xceed the forces the on the other side . Such irregularity results in a bending moment in the press ram , and undesirable deflections and misalignment . It is therefore necessary to find a point about which the summation of shearing forces will be symmetrical . This point is called the center of pre
13、ssure , and is the center of gravity of the line that is the perimeter of the blank .It is not the center of gravity of the area . The press tool will be designed so that the center of pressure will be on the axis of the press ram when the tool is mounted in the press . 中文翻译 冲孔模设计 在一个压力机行程中，在原材料上冲裁出
14、两个孔的一个完整的冲压模具。一家大制造商将其分类并标准化为单工位冲孔模。 任意一副完整的冲压模具，都是由一对（或多对）生产冲压零件的配合零件组成的，同时还包括模具上的固定支承零件和传力连接零件。压力加工术语上通常把所有冲压模具上的凹件定义为凹模。 导柱安装在下模座上。上模座安装与导柱滑动配合的导套。上、下模座连同导柱、导套组成的部件称为模架。市场上有多种模架尺寸和设计形式供选用。 安装在上模座上的凸模固定板固定了两个圆形凸模，这两个圆形凸模（模具中的凸出部分）通过嵌入在卸 料板上的模套进行导向。安装在一个细小凸模外围的护套可以防止凸模在压力机滑动的压力作用下弯曲。在冲裁完工件后，两个凸模还要伸
15、入凹模衬套一小段距离。 凹模是由两个嵌入在凹模板内的衬套组成。由于冲孔模应冲出所要求的孔径，所以凹模的衬套内径应稍大于凸模一个间隙值。 当废料或工件粘在上行的凸模上时，必须从凸模上卸掉废料。弹簧驱动的卸料板相对凹模板运动，将原材料卸下，直到凸模从 冲过的孔内抽出。被冲孔的工件用定位板定位，定位板是与重建外形轮廓相符的平板。在滑块下行之前，毛坯要在凹模内通过定位销、定位板或其它类型的定位装置定位。 落料模设计 用一块 凹模板代替了凹模衬套和用一个落料凸模代替两个冲孔凸模，而坯料的定位用定位板代替。由于冲出的落料件经凹模、下模座和压力机垫板内孔下落，所以这是一幅下出料方式的结构设计。 大型落料件通
16、常采用倒装式落料模，其凹模被安装在上模座，而凸模被固定在下模座。大型落料件通过垫板的下出料方式来实现通常是不切实际的，而采用镶拼式结构设计则比较合适。 对于倒装 式落料模，斜度或倾斜角处的间隙是不必要的，因为落料件不会采用下出料方式。为了使冲裁刃口结构简单，便于修模，保证强度，每一个拼块不应该存在刃口轮廓线的交点和复杂轮廓。 弹簧驱动的卸料装置固定在下模座，它向上运动可以从固定在下模座上的凸模上卸掉废料，卸料螺栓对卸料动作起固定和导向作用。 在压力机滑块回程时，推杆的上端将撞到固定在压力机机身上的打杆，推杆下端向下施力，通过模具使冲制的零件从模腔内被推下。限位环用来挡住推杆并限制它的运动行程。 压力中心 如果所冲裁的零件 轮廓是不规则形状，滑块一侧的剪切力的总和将远 远超
