首页
登录
职称英语
There are a number of methods of joining metal articles together, depending
There are a number of methods of joining metal articles together, depending
游客
2024-10-10
43
管理
问题
There are a number of methods of joining metal articles together, depending on the type of metal and the strength of the joint which is required. Soldering gives a satisfactory joint for light articles of steel, copper or brass, but the strength of a soldered joint is rather less than a joint which is brazed, riveted or welded. These methods of joining metal are normally adopted for strong permanent joints.
The simplest method of welding two pieces of metal together is known as pressure welding. The ends of metal are heated to a white heat—for iron, the welding temperature should be about 1 , 300℃—in a flame. At this temperature the metal becomes plastic. The ends are then pressed or hammered together, and the joint is smoothed off. Care must be taken to ensure that the surfaces are thoroughly clean first, for dirt will weaken the weld. Moreover, the heating of iron or steel to a high temperature causes oxidation, and a film of oxide is formed on the heated surfaces. For this reason, a flux is applied to the heated metal. At welding heat, the flux melts, and the oxide particles are dissolved in it together with any other impurities which may be present. The metal surfaces are pressed together, and the flux is squeezed out from the centre of the weld. A number of different types of weld may be used, but for fairly thick bars of metal, a vee-shaped weld should be employed. It is rather stronger than the ordinary butt weld.
The heat for fusion welding is generated in several ways, depending on the sort of metal which is being welded and on its shape. An extremely hot flame can be produced from an oxyacetylene torch. For certain welds an electric arc is used. In this method, an electric current is passed across two electrodes, and the metal surfaces are places between them. The electrodes are sometimes made of carbon, but more frequently they are metallic. The work itself constitutes one of them and the other is an insulated filler rod. An arc is struck between the two, and the heat which is generated melts the metal at. the weld. A different method is usually employed for welding sheets or plates of metal together. This is known as spot welding. Two sheets or plates are placed together with a slight overlap, and a current is passed between the electrodes. At welding temperature, a strong pressure is applied to the metal sheets. The oxide film, and any impurities which are trapped between the sheets, are squeezed out, and the weld is made. [br] The last type of welding introduced in the passage is______.
选项
A、fusion welding
B、gas welding
C、pressure welding
D、spot welding
答案
D
解析
细节题。文章末段的最后几句“This is known as spot welding…The oxide film,and any impurities which are trapped between the sheets,are squeezed out,and theweld is made.”介绍了点焊(spot welding)的方法和过程,所以[D]是正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3794691.html
相关试题推荐
Thereareanumberofmethodsofjoiningmetalarticlestogether,depending
Thereareanumberofmethodsofjoiningmetalarticlestogether,depending
Thereareanumberofmethodsofjoiningmetalarticlestogether,depending
Thereareanumberofmethodsofjoiningmetalarticlestogether,depending
I’vewrittenbeforeaboutSherryTurkle’snewbook,AloneTogether:WhyWeE
I’vewrittenbeforeaboutSherryTurkle’snewbook,AloneTogether:WhyWeE
Recentlyanumberofcaseshavebeenreportedofyoungchildren______aviolent
Atthepartywefoundthatshygirl______hermotherallthetime.A、dependingo
Whousedtolivetogetherinanextendedfamily?[br][originaltext]Thefa
______ismentionedabove,thenumberofthestudentsinseniorhighschoolsisi
随机试题
Ioweyousomemoney.Letmepayyou______now.A、backB、forC、inD、toApayback:
Thenumberofstudentscarryingmobilephonesisincreasing.Therearediffer
Thelargestanimalthateverlivedonlandorinwaterstillexists.Noteve
TheNBAlockout(停工)didnotfinishonThursdaynight,butitwasnearlyanen
【B1】[br]【B2】A、inspirationB、respirationC、aspirationD、perspirationA名词辨义题[考频:
不能。因为分液漏斗用于分离互不相溶的两种液体,而碘能溶于四氯化碳中,故不能用分液漏斗分离。
播音员主持人在职业活动中表现出来的形象,包括( )。A.个人形象 B.声音形
生姜性温归胃经,有止呕之功,善治A.胃热呕吐 B.胃虚呕吐 C.痰饮呕吐
了解∶领略A.步行∶徜徉 B.怅惘∶失落 C.坦露∶表达 D.追求∶痴迷
某建设工程按照国家工程建设消防技术标准进行消防设计。下列关于备案抽查制度规定的描
最新回复
(
0
)