机械专业英语董建国第12章

1、Unit 12 TEXT READING MATERIAL Unit 12 Unit 12 TEXT Milling Machines The milling machine is a machine that removes metal from the work with a revolving milling cutter as the work is fed against it. The milling cutter is mounted on an arbor where it is held in place by spacers or bushings. The arbor i

2、s fixed in the spindle with one end, while the other end of the arbor rotates in the bearing mounted on the arbor yoke. Unit 12 Fig.12-1 Type of milling cutter Unit 12 The milling cutters are generally made from high speed steel and are available in different sizes and shapes. There are such kinds o

3、f milling cutters (as shown in Fig.12-1) as cylindrical cutters, end milling cutters (for face milling), form milling cutters, angular cutters, side and face cutters, slitting saw, etc. These cutters may differ in the direction of their operation, i.e. they may cut revolving either clockwise or coun

4、ter-clockwise. Unit 12 Regular or irregular shaped work may be produced on a milling machine, designs varying according to the particular class of work wanted. According to the position of the spindle, the milling machines may be divided into two groups of vertical spindle milling machines and horiz

5、ontal spindle milling machines. Milling machines may be grouped into various classes. Unit 12 According to the variation in general design as the “column and knee type”, the manufacturing types, and the planer type of milling machine. According to the table design, the milling machines may be classi

6、fied as universal and plain milling machines. The most important parts of the milling machine are starting levers, spindle, column, knee, elevating screw, table, index head, speed levers, feed levers, table movement levers, foot stock, arbor yoke. Unit 12 The spindle of the milling machine is driven

7、 by an electric motor through a train of gears mounted in the column. The table of the plain milling machine may travel only at right angles to the spindle, while the universal milling machine (as shown in Fig.12-2) is provided with a table that may be swiveled on the transverse slide for milling ge

8、ar teeth, threads, etc. Unit 12 Fig.12-2 Universal milling machine Unit 12 The dividing head (also called an index head) is a device used to divide the periphery of a piece of work into any number of equal parts, and to hold the work in the required position while the cuts are being made. Various ki

9、nds of vises may be used for holding the work in a milling machine, the most common being the plain vise, and the swivel vise. Unit 12 LEARN TO SPEAK Miss Li:Hi, Mr. Liu. Mr. Liu:Hi, Miss Li. How are you? Miss Li:I am fine. Thank you. But I have some problem with the machine tools. Could you give me

10、 a favour? Mr. Liu:Yes, my pleasure. What are these problems? Miss Li:What can shaper and planer do? Unit 12 Mr. Liu:The shaper and planer are generally used for machining flat surfaces, which are usually preformed by a cutter that peel the chip from the work. Miss Li:What are the shape and planers

11、motion forms? Mr. Liu:The main motion is reciprocating and the feed aims at the direction of the main motion. Miss Li:Are the shaper and planer used in mass production? Mr. Liu:No. Miss Li:Why? Mr. Liu:Because they are rather slow in operation. Unit 12 Miss Li:But, for mass production, what methods

12、should we use? Mr. Liu:Milling machines and grinders are more widely used for producing flat surfaces in mass production. Miss Li:What structures are there on a typical shaper? Mr. Liu:There are tool head, ram, column, table, rocker mechanism, etc. Miss Li:How is the feed obtained on a shaper? Mr. L

13、iu:The feed is obtained by a pawl which engages in a notched wheel or ratchet. Miss Li:I am really appreciated you for telling me these knowledge. Mr. Liu:I was glad to be of some services. Unit 12 NEW WORDS AND PHRASES remove rI5mu:v v. 旋转，运行 mount maJnt v. 固定，安装 arbor 5B:bE(r) n. 刀杆，心轴 spacer 5spe

14、IsE(r) n. 衬套，衬垫，垫片 bushing 5bJFIN n. 轴套，衬套 yoke jEJk n. 刀杆支架 slit slIt v. 切开 n. 切口，切缝 clockwise 5klRkwaIz adj. 顺时针的 n. 顺时针 Unit 12 regular 5rejJlE(r) adj. 规则的，对称的 particular pE5tIkjJlE(r) adj. 特别的，单个的 horizontal hBrI5zRnt(E)l adj. that is both centers are“dead”to insure concentricity of the peripher

15、y of groundwork with its axis. (4) Wheel head. A wheel head that carries a grinding wheel and its driving motor is mounted on a slider at the top and rear of the base. The wheel head may be moved perpendicularly to the table ways, by hand or power, to feed the wheel to the work. Unit 12 Either of tw

16、o methods may be used to grind cylinders and tapers on plain grinding machines. In traverse-cut grinding, the work- piece is fed longitudinally past the face of the grinding wheel, and the wheel is fed toward the work after each reversal of the table until the piece is finished to size. The infeed a

17、t each reversal should be from 0.001 to 0.005 inch for roughing, and from 0.0005 to 0.0025 inch for finishing. In plunge-cut grinding, a grinding wheel that has a face width equal to or slightly longer than the surfaces being ground is employed and is fed transversely until the work- piece has the r

18、equired diameter. No longitudinal feeding motion is used. Unit 12 PROFESSIONAL WORDS AND PHRASES conical 5kBnIkEl adj. 圆锥(体，形)的 surplus 5sE:plEs n. 过剩，剩余 exterior eks5tiEriE adj. 外面的 taper 5teIpE(r) n. 锥形，锥度 v. 逐渐变细 sharpen 5FB:pEn vt. 使锐利，变尖 substitute 5sQbstItju:t n. 代替者 Unit 12 v. 代替，替换 base beIs n. 床身 concentricity kBnsEntrIsEtI n. 同轴度 periphery pErifEri n. 圆周，圆柱表面 infeed 5Infi:d n. 横向进给 interior In5tIErIE adj. 内(部)的 grinding machine 磨床 surplus stock 余量 cutter grinder 工具磨床 Unit 12 surfa