冲压模具英文文献

1、Forming DiesForming dies, often considered in the same class with bending dies, are classified as tools that form or bend the blank along a curved axis instead of a straight axis. There is very little stretching or compressing of the material. The internal movement or the plastic flow of the materia

2、l is localized and has little or no effect on the total area or thickness of the material. The operations classified as forming are bending, drawing, embossing, curling, beading, twisting, spinning, and hole flanging.A large percentage of stampings used in the manufacturing of products require some

3、forming operations. Some are simple forms that require tools of low cast and conventional design. Others may have complicated forms, which require dies that produce multiple forms in one stroke of the press. Some stampings may be of such nature that several dies must be used to produce the shapes an

4、d forms required.A first consideration in analyzing a stamping is to select the class of die to perform the work. Next to be considered is the number of stampings required, and this will govern the amount of money that should be spent in the design and building of the tools. Stampings of simple chan

5、nels in limited production can be made on a die classed as a solid form die. It would be classified under channel forming dies. Others- the block and pad type-are also channel forming dies. Such operations as curling, flanging, and embossing as well as channeling employ pressure pads.A forming die m

6、ay be designed in many ways and produce the same results; at this point the cost of the tool, safety of operation, and also the repairing and reworking must be considered. The tool that is cheapestand of the simplest design may not always be best because it may not produce the stamping to the drawin

7、g specifications. Where limited production is required, and a liberal tolerance is allowed in a stamping, a solid form die can be used.Drawing DiesDrawing is a process of changing a flat, precut metal blank into a hollow vessel without excessive wrinkling, thinning, or fracturing. The various forms

8、produced may be cylindrical or box-shaped with straight or tapered sides or a combination of straight, tapered, or curved sides. The size of the parts may vary from 0.250 " (6.35mm)diameter or smaller, to aircraft or automotive parts large eno ugh to require the use of mecha ni cal han dli ng e

9、quipme nt.Die Design PrinciplesCoining Dies. In backward extruding dies the punch is always smaller in diameter tha n the die cavity in order to give the clearanee between punch and die equali ng the desired wall thick ness of the part to be produced. The punch is loaded as a column. To minimize pun

10、ch failure it is desirable to coin the slugs to a close fit in diameter to assure concentricity. Figure 8-66 illustrates a coining die to prepare a slug for backward extrusi on. Coining the slug to fit the diepot and coining the upper end to fit and guide the free end of the punch will mini mize pun

11、ch breakage of the extrud ing die.Backward Extrusion Dies. A typical backward extrusi on die is show n in Figure 8-67. The use of a carbide die cavity will minimize wear due to excessive pressures. The carbide in sert is shr unk into a tapered holder. The holder has a 1? side taper that prestresses

12、the carbide insert to minimize expansion and fatigue failure. The inserts are well supported on hardened blocks. The extrud ing punch is guided by a spring-loaded guide plate which in tur n is positi oned by a tapered piloti ng ring on the lower die. Ejectio n of the finished part from the die is by

13、cushi on or pressure cyli nder. Figure 8-68 illustrates a backward extrusion die with an unu sual punch pen etrati on ratio of 5: 1 made possible with a modified flat-e nd punch profile.Forward Extrusion Dies. Figure 8serves as a guide for the punch duri ng the operati on. Figure 8-70 illustrates an

14、o therforward extrusion die in which the punch creates the orifice through which the metal69 is an example of a typical forward extrusion die in which the metal flows in the same directi on as the pun ch, but at a greater rate owing to change in the cross sectional area. The lower carbide guide ring

15、 is added to maintain straightness. The nest above the upper carbide guide ring flows. The extrud ing pressure is applied through the punch guide sleeve.Combination Extruding Dies. A typical comb in ati on forward and backward extrusi on die is show n in Figure 8-71. In this die, the two iece pressu

16、re an vil acts as a bottom extrud ing punch and a shedder. The upper extrud ing punch is guided by a spring-loaded guide plate into which the guide sleeve is mounted. To maintainconcen tricity betwee n the punch and die, the punch guide sleeve is cen tered in to the die in sert.Punch Design. The mos

17、t importa nt feature of punch desig n is end profile. A punch with a flat end face and a corner radius not over 0.020 " (0.51mman penetrate three times its diameter in steel, four to six times its diameter in aluminum. A punch with a bullet-shaped nose or with a steep angle will cut through the

18、 phosphate coat lubricant quicker than a flat-end pun ch. Whe n the lubrica nt is displaced in extrusi on, severe galli ng and wear of the punch will take palce. The punch must be free of grinding marks and requires a 4 in. (0.10 m) fini sh, lapped in the direct ion of metal flow. The punch should b

19、e made of harde ned tool steel or carbide. In some backward extrusi on dies a shoulder is provided on punch to square up the metal as it meets this shoulder.Pressure Anvil Design. The function of the pressure anvil is to form the base of the diepot, to act as a bottom extrudi ng pun ch, and to act a

20、s a shedder unit to eject the fini shed part. Heat treatme nt and surface finish requireme nts are the same for pressure an vils and for pun ches.Diepot Design. To resist diepot bursti ng pressure, the tool steel or carbide die ring is shr unk into the shri nk ring or die shoe. The die shoe is no rm

21、ally in compressi on. A shrink fit of 0.004 " pen.(0.004mm per mm) of diameter of the insert is desirable. Material, heat treatment, and finish requirements of the diepot are the same as for the pun ch. The recomme nded material for shri nk rings is a hot-worked alloy tool steel which is harden

22、ed to Rc 50-Rc 52. A two-piece diepot insert is sometimes used for complex workpiece shapes.Punch Guide Design.The guide ring minimizes the column loading on the punch above the diepot. The spri ng-loaded guide sleeve pilots the punch into the diepot and maintains concentricity between them. The gui

23、de ring can also act as a stripper. The proper use of guide sleeves permits higher pen etrati on ratios.成型模成型模具，通常被认为是与弯曲模属于同一类，被作为工具，沿着弯曲的 轴线而非直线轴线使工件半成品成型或弯曲。材料有非常小的拉伸和压缩。材 料的内部运动或塑性流动是定域化的，并已很少或者几乎没有影响材料的总面 积或者厚度。操作成型的分类为弯曲，拉伸，压花，卷曲，弯边，扭曲，旋压, 和孔翻边。用于制造冲压件产品的很大一部分需要一些成形操作。一些简单的成型， 需要工具的成本低，常规设计。其他

24、的一些可能复杂的成型，这需要在一个压 缩冲程中可以产生多种形式的模具。表现一些冲压件性质的几种模具必须用于 生产所需的形状和形式。在分析一个冲压过程时，首先考虑的是来完成这个工件的模具等级的选择。 下一个要考虑的是冲压件的数量，这将支配的钱应该被花在工具的设计和制造 上的数量。用于固定产品上的一些简单的途径生产的冲压件，可以通过被归类 为固体成型模具的模具来制造。它将被归类为通道成形模。其他的一些类型一 模块式和垫板式 也是通道成形模。卷曲，翻边，压花这样的操作，和应 用通道的压力垫是一样的。成型模具可以和通过许多方法来设计，并且产生相同的结果；在这一点上 的工具的成本，操作安全性，还有维修和

25、改造，这些必须被考虑。该工具是最 便宜和最简单的设计不一定是最好的，因为它可能不会产生符合制图规范的冲 压件。在一个冲压过程中， 有允许有限的产量是和丰富 的公差的要求的方面，也可 以应用固体成型模。拉伸模拉伸是一种将一种平面 的、预先切割完的金属坯料 转化为中空容器，并且使其没有皱纹、变薄、或压裂。成型生产的各种形式可 以是圆筒形的或立方体或棱锥形的侧边或混合直线、圆锥的组合、或曲边。零 件的尺寸可能会有所不同，变化可以从 0.250 （ 6.35毫米）直径或更小的, 到需要足够大的机械设备来搬运的飞机或汽车上的零件。模具设计原则压印模具。在反挤压模中，冲头的直径小于模腔，为了使凸凹模之间的

26、间隙等于部件所需的要生产壁厚。冲头是一个圆柱的。为了最大限度的减少冲头 失效，最可取的是压印嵌条密切配合尺寸，以保证同心度。图8-66说明压印模具准备一个嵌条作为反挤压塞。压印塞来适应空心模和压印的上端以适应和引 导冲头的自由端，将减少挤压凸模的断裂。反向挤压模具。一个典型的反挤压模具如图8-67所示。一种硬质合金模腔的使用，将减少由于过度的压力造成的磨损。硬质合金刀片被缩小为一个锥形座。这个锥形座有一个1?侧锥角，来保证施加预应力时，硬质合金刀片减少膨胀和疲劳失效。这将是很好的支持硬块。挤压冲头是由下模锥形环依次定位的一个弹簧导板来导向。从模具中推出完成的部件是用缓冲器或压力缸。图8-68显示了一个不寻常的渗透率比为5:1，与修改后的平头冲头的反向挤压模具正挤压模具。图8-69是在同一方向的