機(jī)械專業(yè)英語(yǔ)董建國(guó)第13章

1、Unit 13TEXT READING MATERIAL Unit 13Unit 13TEXTForging, Stamping and Rolling In drop forging, a piece of metal, roughly or approximately of the desired shape, is placed between die faces having the exact form of the finished piece, and forced to take this form by drawing the dies together. This meth

2、od is widely used for the manufacture of parts both of steel and brass. Large ingots are now almost always forged with hydraulic presses instead of with steam hammers, since the work done by a press goes deeper. Unit 13Fig. 13-1 Forging machinerUnit 13 Metal in the form of hot-rolled or cold-rolled

3、sheets or strips may be formed into many shapes by forcing the sheet into the impressions in metal dies. This process is known as stamping, or pressing of metals, and involves many different operations, such as bending, drawing, punching, etc. These operations are successfully carried out through th

4、e proper die design and proper operation of the press in which the dies are placed. Sheets or strips of steel, brass, copper, aluminium, or other metal are placed between dies, and a slow action of the power press brings the dies together, forcing the metal to assume the required shape. Unit 13 Roll

5、ing is the process of shaping metal in a machine called rolling mill. Ingots of metal are rolled by forcing them between two rollers rotating in opposite directions, thus pressing the metal into the required shape. If the rollers have no grooves on their surfaces, the metal is rolled into the form o

6、f a sheet or plate. If the rollers have grooves of a certain shape, the metal will take the form of these grooves, thus it may be shaped into the form of bars or rods.Unit 13 There are two kinds of rolling: hot rolling and cold rolling. Before cold rolling, the scale covering the surface of the hot-

7、rolled object should be removed. Cold rolling produces a higher surface finishing sheet and gives it a very exact size. The process has innumerable advantages. Many shapes may be manufactured in quantities at a rapid rate and at a relatively low cost. Unit 13LEARN TO SPEAKMiss Candy: Hello, Mr. Smit

8、h. Nice to meet you!Mr. Smith: Hi. Miss Candy. Nice to meet you, too.Miss Candy: What are you doing?Mr. Smith: I am preparing for some welding experiments.Miss Candy: I know your major is welding engineering. Could you tell me how many kinds of welding method there are in common use?Mr. Smith: There

9、 are four kinds.Miss Candy: What are they?Unit 13Mr. Smith: They are oxyacetylene welding, arc welding, spot welding and forged weld. Miss Candy: How do the welding work?Mr. Smith: Welding is the joining of two metal pieces by softening with heat and then pressing, hammering, or fusing them together

10、.Miss Candy: How does the arc welding work in detail?Mr. Smith: Arc welding is the heating of two pieces of metal to be welded by electricity. This heat is the hottest that can be obtained for engineering purposes; it is about 7,232 degrees fahrenheit. The ends are thus melted together, making a wel

11、ded joint.Miss Candy: Im really very grateful to you.Mr. Smith: Not at all.Unit 13NEW WORDS AND PHRASESdie daI n. 沖模，鍛模draw drC: vt. 拉伸ingot 5INBt n. 鑄錠，鋼錠press pres vt. 壓，沖壓n. 沖壓，壓力機(jī)hydraulic haI5drC:lIk adj. 水力的，液壓的roll rEJl vt. 軋制，滾軋 n. 卷軸，軋輥rolling 5rBlIN n. 軋制，滾軋roller 5rEJlE(r) n. 軋輥sheet Fi:t

12、 n. 張，片，薄鋼板Unit 13strip strIp n. 條鋼，帶鋼，狹條impression Im5preF(E)n n. 凹膛，壓痕，型腔stamp stAmp v. 沖壓stamping 5stAmpIN n .沖壓punch pQntF n. 沖床 vt. 沖孔，穿孔punching pQntF n. 沖孔，穿孔assume E5sju:m; (?) E5su:m vt. 呈現(xiàn)，表現(xiàn)為形式rotate rEJ5teIt; (?) 5rEJteIt v. 回轉(zhuǎn)，轉(zhuǎn)動(dòng)rotation rEJ5teIF(E)n n. 回轉(zhuǎn)，轉(zhuǎn)動(dòng)bar bB:(r) n. 條鋼，型鋼Unit 13sc

13、ale skeIl n. 氧化皮vt. 測(cè)量，起氧化皮innumerable I5nju:mErEb(E)l adj. 無(wú)數(shù)的welding 5weldIN n. 焊接oxyacetylene BksIE5setIli:n adj. 氧乙炔的fuse fju:z v. 熔合fahrenheit 5fArEnhaIt adj. 華氏溫度計(jì)的n. 華氏溫度計(jì)Unit 13drop forging 模鍛，落錘鍛finished piece 完成件steam hammer 蒸汽錘hydraulic press 液壓機(jī)，水壓機(jī)oxyacetylene welding 氧乙炔焊arc welding 電弧

14、焊spot welding 點(diǎn)焊forged weld 鍛焊Unit 13NOTES 1Large ingots are now almost always forged with hydraulic presses instead of with steam hammers, since the work done by a press goes deeper. 由于壓力機(jī)所做的功能夠傳遞得較深，因此，目前大鑄錠幾乎總是由液壓機(jī)代替蒸汽錘進(jìn)行鍛造的。 “instead of ”是復(fù)合介詞，作“代替”、“而不是”解。 “since the work done by a press goes d

15、eeper”是原因狀語(yǔ)從句，表示主句中的某一動(dòng)作或狀態(tài)所發(fā)生的原因。 “done by a press”是過(guò)去分詞短語(yǔ)作定語(yǔ)，修飾名詞“the work”。 Unit 13EXERCISES 1Discuss the following questions in English: (1) What is produced, if the metal is rolled with rollers having no grooves on their surface? (2) How many kinds of rolling are there? Name them. Which kind pr

16、oduces more exact size? (3) How many kinds of ways which produce a rough work? What are they?Unit 132Use English for replacing Chinese or use English for replacing English. (1) 模鍛(2) 沖壓一個(gè)零件(3) 軋制薄鋼板(4) Weld a work-piece by oxyacetylene welding(5) Punch a hole of a work-piece(6) A work-piece have bee

17、n forgedUnit 13 3Place a “T” after sentences that are true and an “F” after those that are false. (1) All ferrous and non-ferrous metals may be forged.( ) (2) In drop forging, the die faces must have the exact form of the finished pieces.( ) (3) Ingots of metal are rolled by forcing them between two

18、 rollers rotating in the same direction, thus pressing the metal into the required shape.( ) (4) All methods of forging are basically related to hammering or pressing of metal, the main difference between two being the speed of pressure application.( ) (5) Pressing causes metal to move as the result

19、 of a rapidly applied force.( )Unit 13READING MATERIAL Soldering and Brazing 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 b

20、rass, but the strength of 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 joint. Soldering is the process of joining two metals by a third metal to be applied in the molten state. Solder consists

21、of tin and lead, while Unit 13bismuth and cadmium are often included to lower the melting point. One of the most important operations in soldering is that of cleaning surfaces to be joined, this may be done by some acid cleaner. Although the oxides are removed by the cleaning operation, a new oxide

22、coating forms immediately after cleaning, thus preventing the solder to unite with the surface of the metal. Flux is used to remove and prevent oxidation of the metal surface to be soldered, allowing the solder to flow freely and unite with the metal. Zinc chloride is the best flux to use for solder

23、ing most ferrous and nonferrous metals, for soldering aluminum stearine or vaseline is to be used as fluxes. The soldering copper is a piece of copperUnit 13attached to a steel rod having a handle. Soldering coppers are made in different lengths, forms and weights. The quality of soldering depends to a great degree on the form and size of the soldering co