影響加工精度的基本因素--中英文翻譯

1、<p>　　Fundamentals of Manufacturing Accuracy</p><p>　　Manufacturing can be defined as the transformation of raw materials into useful products through the use of the easiest and least-expensive methods.

2、 It is not enough, therefore, to process some raw materials and obtain the desired product.</p><p>　　It is, in fact, of major importance to achieve that goal through employing the easiest, fastest, and most

3、efficient methods. If less efficient techniques are used, the production cost of the manufactured part will be high, and the part will not be as competitive as similar parts produced by other manufacturers. Also, the pro

4、duction time should be as short as possible to enable capturing a larger market share.</p><p>　　Modern industries can be classified in different ways. There include classification by process, classification

5、by product, and classification based on the production volume and the diversity of products. The classification by process is exemplified by casting industries, stamping industries, and the like. When classifying by prod

6、uct, industries may belong to the automotive, aerospace, and electronics groups. The third method, i.e., classification based on production volume, identifies three main</p><p>　　Mass production is character

7、ized by the high production volume of the same (or very similar) parts for a prolonged period of time. An annual production volume of less than 50 000 pieces cannot certainly be considered as mass production. As you may

8、expect, the production volume is based upon an established or anticipated sales volume and is not directly affected by the daily or monthly orders. The typical example of mass-produced goods is automobiles.</p>&l

9、t;p>　　Job-shop production is based on sales orders for a variety of small lots. Each lot may consist of 20 up to 200 or more similar parts, depending upon the customers` needs. It is obvious that this type of producti

10、on is most suitable for subcontractors who produce varying components to supply various industries. The machines employed must be flexible to handle variations in the configuration of the ordered components ,which are us

11、ually frequent. Also, the employed personnel must be highly skilled i</p><p>　　Moderate production is an intermediate phase between the job-shop and the mass-production types. The production volume ranges be

12、tween 10 000 to 20 000 parts, and the machines employed are flexible and multipurpose. This type of production is gaining popularity in industry because of an increasing market demand for customized products. </p>

13、<p>　　A very important fact of the manufacturing science is that it is almost impossible to obtain the desired nominal dimension when processing a workpiece. This is actually caused by the inevitable, though very s

14、light, inaccuracies inherent in the machine tool as well as by various complicated factors like the elastic deformation and recovery of the workpiece and/or the fixture, temperature effects during processing, and sometim

15、es the skill of the operator. Since it is very difficult to analyze and </p><p>　　Before two components are assembled together, the relationship between the dimensions of the mating surfaces must be specifie

16、d. In other words, the location of the zero line to which deviations are referred must be established for each of the two mating surfaces. This actually determines the degree of tightness or freedom for relative motion b

17、etween the mating surfaces. There are basically three types of fits, namely, clearance fit, transition fit, and interference fit. In all cases of clearance</p><p>　　There are two ways for specifying and expr

18、essing the various types of fits, the shaft basis and the hole basis systems. The location of the tolerance zone with respect to the zero line is indicated by a letter, which is always capital for holes and lowercase for

19、 shafts, whereas the tolerance grade is indicated by a number, as previously explained. Therefore, a fit designation can be H7/h6, F6/g5, or any other similar form.</p><p>　　When the service life of an elect

20、ric bulb is over, all you do is buy a new one and replace the bulb. This easy operation, which does not need a fitter or a technician, would not be possible without two main concepts, interchangeability and standardizati

21、on. Interchangeability means that identical parts must be interchangeable, i.e. , able to replace each other, whether during assembly or subsequent maintenance work; without the need for any fitting operations. As you ca

22、n easily see, interchangeab</p><p>　　影響加工精度的基本因素</p><p>　　制造業(yè)可以看作是通過(guò)使用最簡(jiǎn)便、最便宜的方法，把原材料轉(zhuǎn)化為有用的產(chǎn)品的方法，但這顯然還不夠準(zhǔn)確,它應(yīng)該是通過(guò)對(duì)原材料的加工,進(jìn)而獲得所期望得到的產(chǎn)品。</p><p>　　實(shí)際上，通過(guò)采用最簡(jiǎn)單、最快捷和最有效的方法來(lái)達(dá)到目標(biāo)是非常重要的。 如果

23、不能采用先進(jìn)而有效的方法來(lái)加工，則產(chǎn)品的制造費(fèi)用將增高，在與其他類(lèi)似的產(chǎn)品制造商競(jìng)爭(zhēng)時(shí)產(chǎn)品將會(huì)變得沒(méi)有競(jìng)爭(zhēng)力。 此外, 為了獲取更大的市場(chǎng)份額，產(chǎn)品生產(chǎn)的時(shí)間也應(yīng)盡可能短。</p><p>　　現(xiàn)代工業(yè)可以使用很多不同的方法來(lái)分類(lèi)，包括按加工方式分類(lèi)，按產(chǎn)品的類(lèi)型分類(lèi)，按產(chǎn)品生產(chǎn)的數(shù)量和產(chǎn)品的差異性分類(lèi)。按產(chǎn)品的加工方式來(lái)分類(lèi)，在鑄造行業(yè)及沖壓行業(yè)中被廣泛采用。而按產(chǎn)品的類(lèi)型來(lái)分類(lèi)的方法，則主要在汽車(chē)制造業(yè)、飛機(jī)

24、制造業(yè)及電氣業(yè)中采用。第三種方法,即按產(chǎn)品的生產(chǎn)量來(lái)分類(lèi)的方法，確定了三種主要的生產(chǎn)方法：大批量生產(chǎn)、單件小批量生產(chǎn)、中批量生產(chǎn)。下面讓我們來(lái)詳細(xì)的討論每種生產(chǎn)方式的特點(diǎn)。</p><p>　　大批量生產(chǎn)的特點(diǎn)是長(zhǎng)時(shí)間的生產(chǎn)同一種（或者非常類(lèi)似的）產(chǎn)品，如果一件產(chǎn)品的年生產(chǎn)量小于50000件則不能被視為大批量生產(chǎn)。正如你所能想到的，產(chǎn)品生產(chǎn)的數(shù)量是根據(jù)一個(gè)既定或預(yù)期的銷(xiāo)售數(shù)量來(lái)決定的，而不是由一天或一個(gè)月的訂單量

25、來(lái)決定。一個(gè)典型的例子就是汽車(chē)的大規(guī)模生產(chǎn)。</p><p>　　單件小批量生產(chǎn)主要是按種類(lèi)多而批量小的銷(xiāo)售訂單來(lái)生產(chǎn)，每個(gè)批量在20件到200件或者更多，主要決定于客戶(hù)的需求。顯而易見(jiàn)，這種類(lèi)型的生產(chǎn)最適合分包商，生產(chǎn)不同的零件來(lái)供應(yīng)各類(lèi)不同的行業(yè)需求。所采用的機(jī)器必須具有足夠的柔性，以適應(yīng)按訂單生產(chǎn)的零件的外形變化，而這種變化是經(jīng)常發(fā)生的。另外，操作機(jī)器的工人也必須掌握比較高的技術(shù)水平，這樣才能成功的完成各種

26、不同的任務(wù)，加工不同的零件。</p><p>　　中批量生產(chǎn)是介于大批量生產(chǎn)和單件小批量生產(chǎn)之間的一種類(lèi)型，生產(chǎn)量介于10000至20000件之間，而采用的機(jī)器也必須很靈活和多功能化。由于按客戶(hù)需求制造的產(chǎn)品的市場(chǎng)日益增長(zhǎng)，這類(lèi)類(lèi)型的應(yīng)用越來(lái)越多。</p><p>　　在制造科學(xué)中，有一個(gè)非常重要的事實(shí)是：加工一個(gè)工件時(shí)要想獲得理想的名義尺寸幾乎是不可能的。其實(shí)，雖然誤差可能非常的小，但這

27、是不可避免的，因?yàn)楹芏鄰?fù)雜的因素造成機(jī)器上的刀具存在有固有的誤差。比如工件的彈性變形及其回彈，又或者工件的裝夾、加工過(guò)程中溫度的影響，有時(shí)還包括操作人員的操作技能。由于準(zhǔn)確的分析并完全消除這些因素的影響是非常困難的，于是在名義尺寸之上建立一個(gè)允許的誤差或允許的偏差范圍更為可行，而這也不會(huì)影響工件的正常運(yùn)作。按照ISO (國(guó)際標(biāo)準(zhǔn)化組織)體系，公稱(chēng)尺寸被稱(chēng)為零件的基本尺寸，從基本尺寸向每一側(cè)的偏差（正或負(fù)）分別決定了上限和下限，而二者之間

28、的差值稱(chēng)為公差。公差是一個(gè)沒(méi)有標(biāo)志的絕對(duì)值，正如你可以想到的，公差的大小決定于基本尺寸的大小，而由一個(gè)指定的字母數(shù)字符號(hào)來(lái)表示，稱(chēng)為等級(jí)。在ISO質(zhì)量管理體系中，一共設(shè)有18個(gè)標(biāo)準(zhǔn)等級(jí)，公差可從公式算出或從ISO出版的表中查出來(lái)。顯然，公差較小的零件需要利用高精密機(jī)床來(lái)制造，而由此會(huì)導(dǎo)致產(chǎn)品成本的增加。</p><p>　　在兩個(gè)零件組裝在一起之前，尺寸的配合關(guān)系必須指定。換句話說(shuō)，必須在兩個(gè)尺寸之間指定零線的位

29、置。這其實(shí)是確定兩個(gè)物體配合的緊密或能自由運(yùn)動(dòng)的范圍?；旧峡梢苑譃槿N配合，即間隙配合，過(guò)渡配合，過(guò)盈配合。在所有的間隙配合中，軸的上極限尺寸常常比與其配合的孔的下極限尺寸還??；這與過(guò)盈配合不同，在過(guò)盈配合中軸的下極限尺寸通常比孔的上極限尺寸大；過(guò)渡配合,顧名思義,是一個(gè)中級(jí)的配合。按國(guó)際標(biāo)準(zhǔn)化組織的規(guī)定，被包圍在里面的部分常稱(chēng)之為軸，而包圍的表面則稱(chēng)之為孔。因此，從配合的觀點(diǎn)來(lái)說(shuō)，鍵被稱(chēng)為軸，鍵槽被稱(chēng)為孔。</p>&

30、lt;p>　　有兩種方式來(lái)指定和表示各種不同的配合，基軸制和基孔制。公差帶相對(duì)于基準(zhǔn)線的位置是用一個(gè)字母來(lái)表示的，總是用大寫(xiě)字母表示孔，用小寫(xiě)字母表示軸；而公差等級(jí)則如前所述用數(shù)字表示。正如先前解釋的， H7/h6，F(xiàn)6/g5都是正確的表示方式，其他類(lèi)似的形式也是對(duì)的。</p><p>　　當(dāng)一個(gè)電氣部件的使用壽命結(jié)束時(shí)，所有你能做的就是去買(mǎi)一個(gè)新的來(lái)代替它。這是一件非常容易的事情，不需要任何鉗工或技術(shù)員，