1、附：外文翻译 电火花加工 电火花加工法对加工超韧性的导电材料（如新的太空合金）特别有价值。这些金属很难用常规方法加工，用常规的切削刀具不可能加工极其复杂的形状，电火花加工使之变得相对简单了。在金属切削工业中，这种加工方法正不断寻找新的应用领域。塑料工业已广泛使用这种方法，如在钢制模具上加工几乎是任何形状的模腔。 电火花加工法是一种受控制的金属切削技术，它使用电火花切除（侵蚀）工件上的多余金属，工件在切削后的形状与刀具（电极）相反。切削刀具用导电材料（通常是碳）制造。电极形状与所需型腔想匹配。工件与电极都浸在不导电的液体里，这种液体通常是轻润滑油。它应当是点的不良导体或绝缘体。用伺服机构是电极和
2、工件间的保持 0.00050.001 英寸（ 0.010.02mm）的间隙，以阻止他们相互接触。频率为 20000Hz 左右的低电压大电流的直流电加到电极上，这些电脉冲引起火花，跳过电极与工件的见的不导电的液体间隙。在火花冲击的局部 区域，产生了大量的热量，金属融化了，从工件表面喷出融化金属的小粒子。不断循环着的不导电的液体，将侵蚀下来的金属粒子带走，同时也有助于驱散火花产生的热量。 在最近几年，电火花加工的主要进步是降低了它加工后的表面粗糙度。用低的金属切除率时，表面粗糙度可达 2 4vin.(0.05 0.10vin)。用高的金属切除率 如高达 15in3/h(245.8cm3/h)时，表
3、面粗糙度为 1000vin.(25vm)。 需要的表面粗糙度的类型，决定了能使用的安培数 ,电容 ,频率和电压值。快速切除金属（粗切削）时，用大电流 ,低频 率 ,高电容和最小的间隙电压。缓慢切除金属（精切削）和需获得高的表面光洁度时，用小电流 ,高频率 ,低电容和最高的间隙电压。 与常规机加工方法相比，电火花加工有许多优点。 1 .不论硬度高低，只要是导电材料都能对其进行切削。对用常规方法极难切削的硬质合金和超韧性的太空合金，电火化加工特别有价值。 2 .工件可在淬火状态下加工，因克服了由淬火引起的变形问题。 3 .很容易将断在工件中的丝锥和钻头除。 4 .由于刀具（电极）从未与工件接触过，
4、故工件中不会产生应力。 5 .加工出的零件无毛刺。 6 .薄而脆的工件很容易 加工，且无毛刺。 7 .对许多类型的工件，一般不需第二次精加工。 8 .随着金属的切除，伺服机构使电极自动向工件进给。 9 .一个人可同时操作几台电火花加工机床。 10.能相对容易地从实心坯料上，加工出常规方法不可能加工出来的极复杂的形状。 11.能用较低价格加工出较好的模具。 12.可用冲头作电极，在阴模板上复制其形状，并留有必须的间隙。 Electrical discharge machining Electrical discharge machining has proved especially valua
5、ble in the machining of super-tough, electrically conductive materials such as the new space-age alloys. These metals would have been difficult to machine by conventional methods, but EDM has made it relatively simple to machine intricate shapes that would be impossible to produce with conventional
6、cutting tools. This machining process is continually finding further applications in the metal-cutting industry. It is being used extensively in the plastic industry to produce cavities of almost any shape in the steel molds. Electrical discharge machining is a controlled metal removal technique whe
7、reby an electric spark is used to cut (erode) the workpiece, which takes a shape opposite to that of the cutting tool or electrode. The cutting tool (electrode) is made from electrically conductive material, usually carbon. The electrode, made to the shape of the cavity required, and the workpiece a
8、re both submerged in a dielectric fluid, which is generally a light lubricating oil. This dielectric fluid should be a nonconductor (or poor conductor) of electricity. A servo mechanism maintains a gap of about 0.0005 to 0.001 in. (0.01 to 0.02 mm) between the electrode and the work, preventing them
9、 from coming into contact with each other. A direct current of low voltage and high amperage is delivered to the electrode at the rate of approximately 20 000 hertz (Hz). These electrical energy impulses become sparks which jump the dielectric fluid. Intense heat is created in the localized area of
10、the park impact, the metal melts and a small particle of molten metal is expelled from the surface of the workpiece . The dielectric fluid, which is constantly being circulated, carries away the eroded particles of metal and also assists in dissipating the heat caused by the spark. In the last few y
11、ears, major advances have been made with regard to the surface finishes that can be produced. With the low metal removal rates, surface finishes of 2 to 4 um. (0.05 to 0.10um) are possible. With high metal removal rates finishes of 1 000uin. (25um) are produced. The type of finish required determine
12、s the number of amperes which can be used, the capacitance, frequency, and the voltage setting. For fast metal removal (roughing cuts), high amperage, low frequency, high capacitance, and minimum gap voltage are required. For slow metal removal (finish cut) and good surface finish, low amperage, hig
13、h frequency, low capacitance, and the highest gap voltage are required. Electrical discharge machining has many advantages over conventional machining processes. 1. Any material that is electrically conductive can be cut, regardless of its hardness. It is especially valuable for cemented carbides an
14、d the new supertough space-age alloys that are extremely difficult to cut by conventional means. 2. Work can be machined in a hardened state, thereby overcoming the deformation caused by the hardening process. 3. Broken taps or drills can readily be removed from workpieces. 4. It does not create stresses in the work material since the tool (electrode) never comes in contact with the work. 5. The process is burr-free. 6. Thin, fragile sections can be easily machined without deforming.
