【導(dǎo)讀】機床是從早期的埃及人的腳踏動力車床和約翰.威爾金森的鏜床發(fā)展而來的。一般來說，在金屬切削中用一個磨尖的楔形工具以緊湊螺紋形的切屑形。式從有韌性工件表面上去除一條很窄的金屬。切屑是廢棄的產(chǎn)品，與其工件相比，它相當短但是比未切削的部分厚度有相對的增加。機器表面的幾何形狀取決于刀。具的形狀以及加工過程中刀具的路徑。不同的加工工序生產(chǎn)出不同幾何形狀的部件。如果一個粗糙的柱形工件繞中。旋轉(zhuǎn)面，這道工序叫車削。如果以類似的方式加工一根空心管的內(nèi)部，則這道工。制造一個直徑均勻變化的錐形外表面叫做錐體車削。其中刀具尖端沿垂直于旋轉(zhuǎn)軸的方向運動。在其他情況下，更方便的是固定工件。這種龍門刨削和牛頭刨削是在刨床上進行的。管是鉆頭轉(zhuǎn)動還是工件轉(zhuǎn)動，切削刃與工件之間的相對運動都是一個重要因素。因此，僅有4種使用專用可控幾何形狀的刀具基。能起到普通三爪或四爪卡盤同樣的作用。

　　

【正文】 ations, both the workpiece and cutter are moved in relation to each other and in relation to the milling machine. More frequently, however, the workpiece is advanced at a relatively low rate of movement or feed to a milling 11 cutter rotating at a paratively high speed, with the cuter axis remaining in a fixed position, a characteristic feature of the milling process is that each milling cutter tooth takes its share of the stock in the form of small individual chips. Milling operations are performed on many different machines. Since both the workpiece and cutter can be moved relative to one another, independently or in bination, a wide variety of operations can be performed by milling. Applications include the production of flat or contoured surfaces, slots, grooves, recesses, threads, and other configurations. Milling is one of the most universal, yet plicated machining methods. The process has more variations in the kinds of machines used, workpiece movements, and types of tooling than any other basic machining method. Important advantages of removing material by means of milling include high stock removal rates, the capability of producing relatively smooth surface finishes, and the wide variety if cutting tools that are available. Cutting edges of the tools can be shaped to form any plex surface. The major milling methods are peripheral and face milling。 in addition, a number of related methods exist that are variations of these two methods, depending upon the type of workpiece or cutter. Peripheral Milling On peripheral milling, sometimes called slab milling, the milled surface generated by teeth or inserts located in the periphery of the cutter body is generally in a plane parallel to the cutter axis. Milling operations with formrelieved and formed profile cutters are included in this class. The cross section of the milled surface corresponds to the outline or contour of the milling cutter or bination of cutters used. Peripheral milling operations are usually performed on milling machines with the spindle positioned horizontally, however, they can also be performed with end mills on vertiaslspindle machines. The milling cutters are mounted on an arbor which is generally supported at the outer end for increased rigidity, particularly when, because of the conditions of the setup, the cutter or cutters are located at some distance from the nose of the spindle. Peripheral milling should generally not be done if the peripheral milling should generally not be done if the part can be face milled. Face Milling Face milling is done on both horizontal and vertical milling machines. The milled surface resulting from the bined action of cutting edges located on the periphery and face of the cutter is generally at right angles to the cutter axis. The milled surface is flat, with no relation to the contour of the teeth, except when milling is done to a shoulder. Generally, face milling should be applied wherever and whenever possible. 12 Chip thickness in conventional (up) face milling varies from a minimum at the entrance and exit of the cutter tooth to a maximum along the horizontal diameter. The milled surface is characterized by tooth and revolution marks, as in the case of peripheral milling cutters. The prominence of these marks is controlled by the accuracy of grinding the face cutting edge of the teeth, or by the accuracy of the body/insert bination in indexable cutters and of mounting the cutter so that it runs true on the machine spindle. It is also controlled by the rigidity of the machine and workpiece itself. When the length of the face cutting edge is less than the feed per revolution (or the amount the work has moved in one revolution of the cutter), a series of roughly circular grooves or ridges results on the milled surface. Similar marking is produced by the trailing teeth drag on the milled surface of the work. This is known as heel drag. In face milling, it is important to select a cutter with a diameter suited to the proposed width of cut if best results are to be obtained. Cuts equal in width to the full cutter diameter should be avoided, if possible, since the thin chip section at entry of the teeth results in accelerated tooth wear abrasion plus a tendency for the chip to weld or stick to the tooth or insert and be carried around and recut. This is detrimental to surface finish. A good ratio of cutter diameter to the width of the workpiece or proposed path of cut is 5:3. 13 指 導(dǎo) 教 師 評 語 外文翻譯成績： 指導(dǎo)教師簽字： 年 月 日 注： 1. 指導(dǎo)教師對譯文進行評閱時應(yīng)注意以下幾個方面：①翻譯的外文文獻與畢業(yè)設(shè)計（論文）的主題是否高度相關(guān)，并作為外文參考文獻列入畢業(yè)設(shè)計（論文）的參考文獻；②翻譯的外文文獻字數(shù)是否達到規(guī)定數(shù)量（ 3 000 字以上）；③譯文語言是否準確、通順、具有參考價值。 2. 外文原文應(yīng)以附件的方式置于譯文之后。