數(shù)控專業(yè)外文資料翻譯

1、<p>　　Passage Three Milling</p><p>　　Milling introduction</p><p>　　Milling is a machining processing that is carried out by means of a multi edge rotating tool known as a milling cutter

2、. In this process, metal removal is achieved through combining the rotary tool motion of the milling cutter and linear motion of the work piece simultaneous. Milling operations are employed in producing flat, contoured a

3、nd helical surfaces as well as for thread and gear cutting operations.</p><p>　　Each of the cutting edges of a milling cutter acts as an individual single point cutter when it engages with the work piece met

4、al. Therefore, each of those cutting edges has appropriate rake and relief angles. Since only a few of the cutting edges are engaged with the work piece at a time, heavy cuts can be taken without adversely affecting the

5、tool life. In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling. Moreover, the</p><p>　　A wide variety of milling cutters is availab

6、le in industry. This, together with the face that a milling machine is a very versatile machine tool, makes the milling machine the backbone of a machining workshop.</p><p>　　As far as the direction of cutte

7、r rotation and work piece fed are concerned, milling is performed by either of the following two methods.</p><p>　　Up milling (conventional milling).In up milling the work piece is fed against the direction

8、of cutter rotation. The depth of cut gradually increases on the successively engaged cutting edges. Therefore, the machining process involves no impact loading, thus ensuring smoother operation of the machine tool and th

9、e longer tool life. The quality of the machined surface obtained by up milling is not very high. Nevertheless, up milling is commonly used in industry, especially for rough cuts.</p><p>　　Down milling (climb

10、 milling). In down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the work piece. The maximum depth of cut is achieved directly as the cutter engages with the w

11、ork piece. This results in a kind of impact, or sudden loading. Therefore, this method cannot be used unless the milling machine is equipped with a backlash eliminator on the feed screw. The advantages of this method inc

12、lude higher quality of the machined surfa</p><p>　　Milling machine</p><p>　　There are several types of milling machines employed in industry. They are generally classified based on their constru

13、ction and design feature. They vary from the common general purpose types to duplicators and machining centers that involve a tool magazine and are capable of carrying out many machining operations with a single work p

14、iece setup. Following is a survey of the milling machine types commonly used in industry. </p><p>　　Plain horizontal milling machine. The construction of the plain horizontal milling machine is very similar

15、to that of the universal milling machine except that the machine table cannot be swiveled. Plain milling machines usually have column and knee type construction and also have three table motions, i.e., longitudinal, tran

16、sverse, and vertical. The milling cutter is mounted on a short arbor, which is, in turn, rigidly supported by the over arm of the milling machine.</p><p>　　Universal milling machine. The construction of a u

17、niversal milling machine is similar to that of the plain milling machine, except that it is more accurate and has sturdier frame, and its table can be swiveled with an angle up to 50°. Universal milling machine are

18、usually equipped with an index or dividing hear, allows cutting of gear and cams.</p><p>　　Vertical milling machine. As the name vertical milling machine suggests, the axis of the spindle that holds the mi

19、lling cutter is vertical. Table movements are generally similar to those of plain horizontal milling machines; however, an additional rotary motion is sometimes provided for the table to enable machining helical and circ

20、ular grooves. The cutter used with vertical milling machines are almost always of the end mill type.</p><p>　　Duplicators. A duplicators is sometimes referred to as a copy milling machine because of reproduc

21、ing an exact replica of a model. The machine has a stylus that scans the model, at which the counterpoints on the part are successively machined. Duplicators were used for the production of large forming dies for the aut

22、omotive industry, where models made of wood, plaster of Paris, or wax were employed. Duplicators are not commonly used in industry nowadays because they have been superseded by the CA</p><p>　　Machining cent

23、er. Machining center are NC machines that are capable of performing a number of different machining processes at a time. A machining center has a tool magazine in which many tool are held. Tool changes are automatically

24、carried out, and so are functions such as coolant on or off. Machining centers are, therefore, highly versatile and are employed to perform a number of machining operations on work piece with a single setup. Parts having

25、 intricate shapes can easily be produced with </p><p><b>　　譯文：</b></p><p><b>　　銑削</b></p><p><b>　　銑削簡介</b></p><p>　　銑削是通過旋轉(zhuǎn)多刃刀具即銑刀，進(jìn)

26、行加工的切削方法。這個過程中，金屬的切除是通過銑刀的旋轉(zhuǎn)運動與同時進(jìn)行的工件的直線運動的組合來實現(xiàn)的。銑削加工主要用在平面、輪廓、螺旋面及螺紋和齒輪的加工。</p><p>　　切削工件時，銑刀的每一條切削都是一把獨立的刀具。因此，每一條切削刃都有合適的前角和后角。既然每次切削只有少數(shù)切削刃切削，大切削用量不會減少刀具的使用壽命。實際上，銑削允許的切削速度和進(jìn)給量是車削和鉆削的3到4倍。而且銑削得到的加工表面質(zhì)量

27、一般高于車削、成型加工或鉆削。</p><p>　　工業(yè)生產(chǎn)中使用的銑刀種類繁多，加之銑床的通用性使得銑床成為機(jī)械加工車間的支柱。</p><p>　　根據(jù)銑刀旋轉(zhuǎn)方向和工件的進(jìn)給方向，銑削可以采用以下兩種方式。</p><p><b>　　逆銑</b></p><p>　　逆銑中工件進(jìn)給方向與刀具旋轉(zhuǎn)方向在接觸點處相反

28、。切削深度隨著切削刃連續(xù)進(jìn)入切削而逐漸增加。因此，切削中無沖擊載荷，這樣可以保證刀具平穩(wěn)工作和較長的刀具壽命。逆銑獲得表面質(zhì)量不高。然而逆銑在工業(yè)中仍廣泛使用，主要用與粗加工。</p><p><b>　　順銑</b></p><p>　　順銑時刀具旋轉(zhuǎn)方向與工件進(jìn)給方向在接觸點同向。最大切削深度在刀具切削工件時直接獲得。結(jié)果導(dǎo)致沖擊產(chǎn)生。因此，只有銑床在進(jìn)給絲桿上安

29、裝了齒隙消除裝置才采用順銑。這種加工方法的優(yōu)點是加工表面質(zhì)量高，工件因為切削力方向向下而容易裝夾。</p><p><b>　　銑床</b></p><p>　　工業(yè)生產(chǎn)中使用的銑床有幾種類型。通常按結(jié)構(gòu)設(shè)計特征來分。它們從普通的一般用途的型號到仿形銑床及配有刀具庫使得工件在一次裝夾后就能完成多種加工操作的加工中心等多種型號。以下是對工業(yè)中常用銑床的概述。</p

30、><p><b>　　平面臥式銑床</b></p><p>　　除了工作臺不能旋轉(zhuǎn)，平面臥式銑床的結(jié)構(gòu)與萬能銑床類似。平面銑床一般裝備柱式升降臺式，工作臺有三個運動方向，縱向、橫向和垂直方向。銑刀安裝在短心軸上，心軸由銑床懸臂支承。</p><p><b>　　萬能銑床</b></p><p>　　除了

31、更高精度和更高強度結(jié)構(gòu)，萬能銑床的結(jié)構(gòu)與平面臥式銑床相似，工作臺最大旋轉(zhuǎn)角度可達(dá)50°。萬能銑床一般裝有指針或分度頭，可以加工齒輪和凸輪。</p><p><b>　　立式銑床</b></p><p>　　如名稱所示，立式銑床裝夾銑刀的主軸是鉛垂的。工作臺移動方式與平面臥式銑床相似，另外，附加一個旋轉(zhuǎn)運動，使銑床可以加工螺旋形或圓弧形槽。立式銑床一般使用立銑

32、刀。</p><p><b>　　仿形銑床</b></p><p>　　仿形銑床有時被稱為復(fù)制銑床，因為它就是在生產(chǎn)一個模型的復(fù)制品。機(jī)床有一個觸頭，靠在模型上進(jìn)行掃描，這樣零件的對應(yīng)部分就能被連續(xù)加工出來。仿形銑床一般用于自動化生產(chǎn)中大型成型模具的加工，自動化工業(yè)中材料一般使用木材、熟石膏或蠟?，F(xiàn)代工業(yè)已經(jīng)很少使用仿形銑床，它已被CAD/CAM系統(tǒng)替代。</p