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文献出处：She C H, Chang C C, Kao Y C, et al. A study on the computer-aided measuring integration system for the sheet metal stamping dieJ. Journal of Materials Processing Technology, 2006, 177(1-3):138-141.Milling is a basic machining process by which a surface is generated by progressive cut- ting removal. The workpiece is fed into a rotating cutting tool. Sometimes the workpiece re- mains stationary, and the cutter is fed to the work. In nearly all cases, a multiple-tooth cutter is used so that the material removal rate is high. Often the desired surface is obtained in a single pass of the cutter or workpiece, and because very good surface can be obtained, milling is particularly well suited and widely used for mass-production work. Many types of milling machines are used, ranging from relatively simple and versatile machines that are used for general-purpose machining in job shops to highly specialized machines in tool-and die work shop.The cutting tool used in milling is known as a milling cutter. Equally spaced peripheral teeth will intermittently engage and machine the workpiece. This is called interrupted cut-ting.Milling operations can be classified into two broad categories called peripheral milling and face milling. Each has many variations In peripheral milling the surface is generated by teeth located on the periphery of the cutter body. The surface is parallel with the axis of rotation of the cutter. Both flat and formed surfaces can be produced by this method, the cross section on the resulting surface corresponding to the axial contour of the cutter. This process, often called slab milling, is usually performed on horizontal-spindle milling machines.In face milling and end milling, the surface is generated at right angles to t he is. Most of the cutting is done by the peripheral portions of the teeth, with the face portions. providing some finishing action. Face milling is done on both horizontal and vertical-spindie machines.For either slab or face milling, surfaces can be generated by two distinctly different methods. Up milling is the traditional way to mill. The cutter rotates against the direction of feed rate of the workpiece. In climb or down milling, the cutter rotation is in the same direction as the feed rate. The method of chip formation is completely different in the two cases.(3) Electro-discharge MachiningWhen applying the electro-discharge machining (EDM) process, the material is eroded as a result of an electrical discharge between tool and workpiece. Due to discharge time is short, but the voltage is very high and temperature rises, metal particles at the point of discharge are molten, partially vapourized and removed from the melt by mechanical and electromagnetic forces. The working medium is a dielectric, which washes the eroded material a way and simultaneously acts as a coolant.As in the case of ECM (electrochemical machining). EDM is a copying process where there is no contact between tool and workpiece. Contrary to ECM, however, there is some erosion of the tool in EDM, which must be allowed for in the tool design to ensure accuracy of machining.A further difference arises from the fact that in EDM there is no fixed tool feed, but the gap size must be maintained in accordance with the rate of metal removal and the conditionsexisting within the gap. Electro-discharge de-sinking machine. The construction principle of an EDM die-sinking machine are shown in Fig. 1-59. Spark erosion takes place in a container filled with the dielectric in which the workpiece is clamped. The controlled feed of the electrode is through an electrohydraulic or electromechanical servo system. The electrical energy for erosion is provided by the erosion generator. The filtering unit separates the eroded material from the dielectric. In the upper left of Fig. 5-59, a single discharge is illustrated in enlarged form. The applied voltage ionizes the gap at the beginning of the discharge. At the point of highest field strength, a channel is formed, through which the discharge current flows. At each end of the channel, the material melts and the channel and its surrounding gas bubble expand. When the voltageis fully discharged, the channel collapses and the molten material vaporizes, simulating a miniature explosion. The resultant of the discharge is a hallmark of the irregular crater and scars on the spark-eroded work surface.Electro-discharge cutting machine. An important application of the spark-erosion process is the cutting of metal by wire electrodes. The process is used for the production of aperture in cutting tools and the manufacture of tool electrodes for EDM. Fig. 1-60 illustrates the prin for this reason wire position is constantly supplied. The apparatus required for wire feeding can be seen in Fig. 1-61. The degree of wire tension, therate of wire consumption and the reach of the wire support arms are adjusted in accordance with the work to be done and the size of the workpiece. The working medium for electrodischargecutting is usually ionized watter, which is fed to the work area with the use of flushing jets.According to the required contour of the workpiece, the table with the work piece clamped to it and the slide with the wire feed unit must be suitably positioned. The relative advance of the wire electrodes to the workpiece does not have a constant velocity, but must be varied in accordance with the conditions existing in the gap throughout the process, depending onthe progress of the cutting, as was the case in electrodischarge machining.铣削是一种基本的加工过程，通过逐步切削去除产生表面。工件被送入旋转切削刀具。有时工件重新固定，刀具被输送到工件上。在几乎所有的情况下，使用多齿切割器，使得材料去除率高。通常所需的表面是在刀具或工件的单道次中得到的，并且因为可以获得非常好的表面，所以铣削特别适合并广泛用于大规模生产工作。使用许多类型的铣床，从用于车间通用加工的相对简单和多用途的机器到工具和模具车间的高度专业化的机器。铣削用的刀具称为铣刀。等间距的外齿会间歇地啮合并加工工件。这叫做间断切割。铣削操作可分为两大类，即周边铣削和端面铣削。每一个都有许多变化在周边铣削表面产生的牙齿位于牙齿周围的刀体。该表面与切割器的旋转轴线平行。用这种方法可以生产出平面和形状表面，所得表面上的横截面与刀具的轴向轮廓相对应。这个过程，通常称为板坯铣削，通常是在水平主轴铣床上进行的。在端面铣削和端铣加工中，表面与工件成直角产生。大部分的切割是由牙齿的外围部分完成的，面部部分提供了一些完成动作。面铣是在水平和立式铣床上进行的。无论是板坯还是端面铣削，都可以通过两种截然不同的方法产生表面。上铣是传统的铣削方式。刀具沿工件进给方向旋转。在爬升或向下铣削中，刀具的旋转方向与进给速度相同。芯片的形成方法在两种情况下完全不同。（3）电火花加工当应用电火花加工（EDM）工艺时，由于刀具和工件之间的放电，材料被腐蚀。由于放电时间短，但是电压很高，温度升高，在放电点金属颗粒熔融，部分蒸发，并通过机械和电磁力从熔体中除去。工作介质是一种电介质，它以一种方式洗涤被侵蚀的材料并同时起冷却剂的作用。在电解加工（ECM）的情况下。电火花加工是一种在刀具和工件之间没有接触的复制过程。然而，与电火花加工相反，电火花加工存在刀具磨损，为了保证加工精度，在刀具设计中必须考虑这些磨损。另一个不同之处在于，在电火花加工中，没有固定的刀具进给，但是间隙大小必须根据金属去除的速度和条件来维持。GAP 内存在的电火花沉模机。电火花成型机的结构原理如图 1-59 所示。火花腐蚀发生在充满工件夹持件的电介质的容器中。电极的控制进给是通过电液伺服或机电伺服系统。侵蚀产生的电能由侵蚀发生器提供。过滤单元将腐蚀材料与电介质分离。在图 5-59 的左上角，以放大的形式示出单个放电。施加的电压在放电开始时电离间隙。在最高场强点处，形成一个通道，通过该通道，放电电流流动。在通道的每一端，材料熔化，通道及其周围的气泡膨胀。当电压完全放电时，通道坍塌，熔融材料蒸发，模拟微小爆炸。放电的结果是火花腐蚀工作表面上不规则的火山口和疤痕的特征。电火花加工的一个重要应用是线切割加工。该工艺用于切割工具的孔的制造和电火花加工工具电极的制造。图 1-60 示出了由于这个原因，导线位置不断提供的原则。在图 1-61 中可以看到送丝所需的设备。根据所要完成的工件尺寸调整钢丝张力的程度、导线消耗量和导线支撑臂的伸长量。电火花加工用的工作介质通常是电离水，用冲洗喷嘴送入工作区域。根据所要求的工件外形，夹持工件的台和带送丝装置的滑块必须适当定位。丝电极相对于工件的相对前进速度不是恒定的，而是必须根据整个加工过程中间隙中存在的条件而变化，这取决于切削的进度，就像电火花加工的情况一样。理解综述本文主要讲解了铣削的基本加工过程和电火花加工过程及原理。首先，什么是铣削？铣削是指使用旋转的多刃刀具切削工件，是高效率的加工方法。适于加工平面、沟槽、各种成形面(如花键、齿轮和螺纹)和模具的特殊形面等。按照铣削时主运动速度方向与工件进给方向的相同或相反，又分为顺铣和逆铣。在加工之前一定要将工件固定，检查刀具安装是否到位再进行铣削加工。在铣削过程中为保证工件的表面质量一般都用顺铣，但不同的工件就会有不同的进刀方式，根据具体情况采用顺铣与逆铣。铣刀在铣削过程中起到了主导地位，铣刀铣削部分材料应该具备高硬度、耐磨性、足够的强度和韧性、良好的热硬性和加工工艺性。根据不同的铣刀它能根据加工程序完成各种工序，铣削加工需要经过粗加工、半精加工、精加工，最后才得到成型的工件。本文将铣削加工分为周边铣削和端面铣削，周边铣削可分为顺铣逆铣，顺铣切削厚度大，接触长度短，铣刀寿命短，加工表面光洁，但不宜加工带硬皮工件，且进给丝杆与螺母间应消除间隙。否则，应该采用逆铣。端面铣削可根据铣刀与工件相对位置的不同可分为对称铣与不对称铣，根据工件的具体材料选择合理的铣削方式。电火花加工的原理是基于工具和工件（正、负电极）之间的脉冲电火花时电腐蚀现象来腐蚀多余的金属，以达到对工件的尺寸、形状及表面质量等预定的加工要求。电火花腐蚀的主要原因：电火花放电时火花通道中瞬时产生大量的热，达到很高的温度，足以使任何金属材料局部熔化、气化而被腐蚀掉，形成放电凹坑。脉冲放电产生的高温火花通道足以熔化任何材料，所以它便于加工用机械加工方法难于加工或无法加工的特殊材料。加工时工具电极与工件不接触，两者之间宏观作用力极小，不存在因切削力而产生设备和工艺问题，因此，可不受工件几何形状的影响。由于电火花加工的原理，也给这种工艺带来了局限性。例如，生产效率较低，工具电极会损耗、影响工件尺寸，这些问题还需要进一步研究提高。电火花线切割时电极丝接脉冲的负极，工件接脉冲电源的正极。当来一个电脉冲时，在电极丝和工件之间产生一次火花放电，在放电通道中心温度可达到 10000以上，高温使工件金属熔化甚至有少量气化，高温也使电极丝和工件之间的工作液部分气化，这些气化后的工作液和金属蒸气瞬间迅速热膨胀，并且有爆炸的特点。电火花线切割适用于难以切削材料的加工，特殊及复杂形状的零件，自动化程度高，操作方便，加工周期短，成本低，材料利用率高。但工件必具导电性。
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