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首页 » 经典英文小说 » The Economy of Workshop Mainipulation » CHAPTER XXIX. FITTING AND FINISHING.
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CHAPTER XXIX. FITTING AND FINISHING.
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The fitting or finishing department of engineering establishments is generally regarded as the main one.

Fitting processes, being the final ones in constructing machinery1, are more nearly in connection with its use and application; they consist in the organisation2 or bringing together the results of other processes carried on in the draughting room, pattern shop, foundry, and smith shop.

To the unskilled, or to those who do not take a comprehensive view of an engineering business as a whole, the finishing and fitting department seems to constitute the whole of machine manufacture—an impression which a learner should guard against, because nothing but a true understanding of the importance and relations of the different divisions of an establishment can enable them to be thoroughly3 or easily learned.

Finishing, therefore, it must be borne in mind, is but one among several processes, and that the fitting department is but one out of four or more among which attention is to be divided.

Finishing as a process is a secondary and not always an essential one; many parts of machinery are ready for use when forged or cast and do not require fitting; yet a finishing shop must in many respects be considered the leading department of an engineering establishment. Plans, drawings and estimates are always based on finished work, and when the parts have accurate dimensions; hence designs, drawings and estimates may be said to pass through the fitting shop and follow back to the foundry and smith shop, so that finishing, although the last process in the order of the work, is the first one after the drawings in every other sense; even the dimensions in pattern-making which seems farthest removed from finishing, are based upon fitting dimensions, and to a great extent must be modified [119]by the conditions of finishing.

In casting and forging operations the material is treated while in a heated and expanded condition; the nature of these operations is such that accurate dimensions cannot be attained4, so that both forgings and castings require to be made enough larger than their finished dimensions to allow for shrinkage and irregularities. Finishing as a process consists in cutting away this surplus material, and giving accurate dimensions to the parts of machinery when the material is at its natural temperature. Finishing operations being performed as said upon material at its normal temperature permits handling, gauging5 and fitting together of the parts of machinery, and as nearly all other processes involve heating, finishing may be called the cold processes of metal work. The operations of a fitting shop consist almost entirely6 of cutting, and grinding or abrading7; a proposition that may seem novel, yet these operations comprehend nearly all that is performed in what is called fitting.

Cutting processes may be divided into two classes: cylindrical8 cutting, as in turning, boring, and drilling, to produce circular forms; and plane cutting, as in planing, shaping, slotting and shearing9, to produce plane or rectangular forms. Abrading or grinding processes may be applied10 to forms of any kind.

To classify further—cutting machines may be divided into those wherein the tools move and the material is fixed11, and those wherein the material is moved and the tools fixed, and machines which involve a compound movement of both the tools and the material acted upon.

There is also a distinction between machine and hand cutting that may be noted12. In machine cutting it is performed in true geometrical lines, the tools or material being moved by positive guides as in planing and turning; in hand operations, such as filing, scraping or chipping, the tools are moved without positive guidance, and act in irregular lines.

To attempt a generalisation of the operations of the fitting shop in this manner may not seem a very practical means of understanding them, yet the application will be better understood as we go farther on.

Cutting tools include nearly all that are employed in finishing; lathes14, planing machines, drilling and boring machines, shaping, slotting and milling machines, come within this class. The machines named make up what are called standard tools, such [120]as are essential and are employed in all establishments where general machine manufacture is carried on. Such machines are constructed upon principles substantially the same in all countries, and have settled into a tolerably uniform arrangement of movements and parts.

Besides the machine tools named, there are special machines to be found in most works, machines directed to the performance of certain work; by a particular adaptation such machines are rendered more effective, but they are by such adaptation unfitted for general purposes.

General engineering work cannot consist in the production of duplicate pieces, nor in operations performed constantly in the same manner as in ordinary manufacturing; hence there has been much effort expended15 in adapting machines to general purposes—machines, which seldom avoid the objections of combination, pointed16 out in a previous chapter.

The principal improvements and changes in machine fitting at the present time is in the application of special tools. A lathe13, a planing machine, or drilling machine as a standard machine, must be adapted to a certain range of work, but it is evident that if such tools were specially17 arranged for either the largest or the smallest pieces that come within their capacity, more work could be performed in a given time and consequently at less expense. It is also evident that machine tools must be kept constantly at work in order to be profitable, and when there are not sufficient pieces of one kind to occupy a machine, it must be employed on various kinds of work; but whenever there are sufficient pieces of the same size upon which certain processes of a uniform character are to be performed, there is a gain by having machines constructed to conform as nearly as possible to the requirements of special work, and without reference to any other.

It is now proposed to review the standard tools of a fitting shop, noticing the general principles of their construction and especially of their operation; not by drawings nor descriptions to show what a lathe or a planing machine is, nor how some particular engineer has constructed such tools, but upon the plan explained in the introduction, presuming the reader to be familiar with the names and purposes of standard machine tools. If he has not learned this much, and does not understand the names and general objects of the several operations carried [121]on in a fitting shop, he should proceed to acquaint himself thus far before troubling himself with books of any kind.

(1.) Why cannot the parts of machinery be made to accurate dimensions by forging or casting?—(2.) What is the difference between hand tool and machine tool operation as to truth?—(3.) Why cannot hand-work be employed in duplicating the parts of machinery?—(4.) What is the difference between standard and special machine tools?


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1 machinery CAdxb     
n.(总称)机械,机器;机构
参考例句:
  • Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗?
  • Machinery ought to be well maintained all the time.机器应该随时注意维护。
2 organisation organisation     
n.组织,安排,团体,有机休
参考例句:
  • The method of his organisation work is worth commending.他的组织工作的方法值得称道。
  • His application for membership of the organisation was rejected.他想要加入该组织的申请遭到了拒绝。
3 thoroughly sgmz0J     
adv.完全地,彻底地,十足地
参考例句:
  • The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
  • The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。
4 attained 1f2c1bee274e81555decf78fe9b16b2f     
(通常经过努力)实现( attain的过去式和过去分词 ); 达到; 获得; 达到(某年龄、水平、状况)
参考例句:
  • She has attained the degree of Master of Arts. 她已获得文学硕士学位。
  • Lu Hsun attained a high position in the republic of letters. 鲁迅在文坛上获得崇高的地位。
5 gauging 43b7cd74ff2d7de0267e44c307ca3757     
n.测量[试],测定,计量v.(用仪器)测量( gauge的现在分词 );估计;计量;划分
参考例句:
  • The method is especially attractive for gauging natural streams. 该方法对于测量天然的流注具有特殊的吸引力。 来自辞典例句
  • Incommunicative as he was, some time elapsed before I had an opportunity of gauging his mind. 由于他不爱说话,我过了一些时候才有机会探测他的心灵。 来自辞典例句
6 entirely entirely     
ad.全部地,完整地;完全地,彻底地
参考例句:
  • The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
  • His life was entirely given up to the educational work. 他的一生统统献给了教育工作。
7 abrading 8e12dee288abd0a8c2c417fe66346d69     
v.刮擦( abrade的现在分词 );(在精神方面)折磨(人);消磨(意志、精神等);使精疲力尽
参考例句:
8 cylindrical CnMza     
adj.圆筒形的
参考例句:
  • huge cylindrical gas tanks 巨大的圆柱形贮气罐
  • Beer cans are cylindrical. 啤酒罐子是圆筒形的。
9 shearing 3cd312405f52385b91c03df30d2ce730     
n.剪羊毛,剪取的羊毛v.剪羊毛( shear的现在分词 );切断;剪切
参考例句:
  • The farmer is shearing his sheep. 那农夫正在给他的羊剪毛。 来自《简明英汉词典》
  • The result of this shearing force is to push the endoplasm forward. 这种剪切力作用的结果是推动内质向前。 来自辞典例句
10 applied Tz2zXA     
adj.应用的;v.应用,适用
参考例句:
  • She plans to take a course in applied linguistics.她打算学习应用语言学课程。
  • This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。
11 fixed JsKzzj     
adj.固定的,不变的,准备好的;(计算机)固定的
参考例句:
  • Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗?
  • Once the aim is fixed,we should not change it arbitrarily.目标一旦确定,我们就不应该随意改变。
12 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
13 lathe Bk2yG     
n.车床,陶器,镟床
参考例句:
  • Gradually she learned to operate a lathe.她慢慢地学会了开车床。
  • That lathe went out of order at times.那台车床有时发生故障。
14 lathes cd4be0c134cfc2d344542ceda5ac462c     
车床( lathe的名词复数 )
参考例句:
  • They showed keen interest in the various lathes on exhibition. 他们对展出中的各类车床表现出了浓厚的兴趣。
  • To automate the control process of the lathes has become very easy today. 使机床的控制过程自动化现已变得很容易了。
15 expended 39b2ea06557590ef53e0148a487bc107     
v.花费( expend的过去式和过去分词 );使用(钱等)做某事;用光;耗尽
参考例句:
  • She expended all her efforts on the care of home and children. 她把所有精力都花在料理家务和照顾孩子上。
  • The enemy had expended all their ammunition. 敌人已耗尽所有的弹药。 来自《简明英汉词典》
16 pointed Il8zB4     
adj.尖的,直截了当的
参考例句:
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
17 specially Hviwq     
adv.特定地;特殊地;明确地
参考例句:
  • They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。
  • The machine was designed specially for demolishing old buildings.这种机器是专为拆毁旧楼房而设计的。


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