首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
There are a number of methods of joining metal articles together, depending on the type of metal and the strength of the joint w
There are a number of methods of joining metal articles together, depending on the type of metal and the strength of the joint w
admin
2013-09-23
75
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.
Which method of welding is the simplest for the welders to operate?
选项
A、Fusion welding.
B、Gas welding.
C、Pressure welding.
D、Spot welding.
答案
C
解析
细节题。从文章第二段第一句“The simplest method of welding two pieces ofmetal together is known as pressure welding.”可知,加压焊(pressure welding)操作起来最简便,所以[C]是正确答案。
转载请注明原文地址:https://www.kaotiyun.com/show/9HLK777K
0
专业英语四级
相关试题推荐
SomehowCaliforniaisalwaysatthecuttingedge,beitintheflower-powerdaysofthe1960sorthedotcomboomofthe1990s.A
Acommonassumptionabouttheprivatesectorofeducationisthatitcatersonlytotheelite.【C1】______recentresearchpoints
Acommonassumptionabouttheprivatesectorofeducationisthatitcatersonlytotheelite.【C1】______recentresearchpoints
Educatorstodayismoreandmoreoftenhardtosaythatcomputerliteracyisabsolutelynecessaryforcollegestudents.Manyeve
Themedicalexpertswarnedtheauthoritiesofthedangerofdiseaseinthe______oftheearthquake.
whyistheweightlossplancalledtheScarsdalediet?
Inthedigitalrealm,thingsseemalwaystohappenthewrongwayround.WhereasGooglehashurriedtoscanbooksintoitsdigita
Withoutfacts,wecannotformaworthwhileopinionforweneedtohavefactualknowledge______ourthinking.
Altogetherhowmanypeoplewereinjuredduringtheviolence?
随机试题
IngmaBergman’slatestworkasascreenwriteris"Sunday’sChildren".SetinruralSwedenduringthelate1920s,thestorycent
患儿,男,2岁,诊为室间隔缺损,分流量大。护士对家长的健康教育可除外( )。
男,33岁,15年前曾发现蛋白尿,一直未检查和治疗。三周前出现恶心、呕吐,查:血压190/120mmHg,轻度浮肿,血肌酐360μmol/L,B超双肾缩小。下列生化异常不应出现的是
敷设于保护管中的电缆,应具有()。
不锈钢餐匙(非成套)()
当价格连续下降远离移动平均线,又上升至移动平均线附近再度下降时,一般可以认为这是一个买入信号。()[2012年5月真题]
李某退休后于2000年1月起承包了一家饭店,承包期为一年,按规定李某一年取得承包收入50000元,此外李某还按月领取退休工资,每月600元,作为饭店承包人,李某还按规定履行个人所得税代扣代缴义务,一年来取得扣缴手续费1000元。根据以上资料回答下列问题:
下面四个立体图形中,哪一项不能用一个平面分割为两个完全相同或互为镜像的部分?
清代儒学有所谓汉学、宋学之争,汉学即()。
关于软件测试,(31)的叙述是正确的。①测试开始越早,越有利于发现软件缺陷②采用正确的测试用例设计方法,软件测试可以做到穷举测试③测试覆盖度和测试用例数量成正比④软件测试的时间越长越好
最新回复
(
0
)