《机械专业英语》课件第19章.ppt

1、Unit 19TEXT LEARN TO SPEAK NEW WORDS AND PHRASES NOTES EXERCISES READING MATERIAL PROFESSIONAL WORDS AND PHRASES Milling MachinesThe 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 w

2、here it is held in place by spacers or bushings.The arbor is fixed in the spindle with one end,while the other end of the arbor rotates in the bearing mounted on the arbor yoke.Fig.19-1 Type of milling cutter The milling cutters are generally made from high speed steel and are available in different

3、 sizes and shapes.There are such kinds of milling cutters(as shown in Fig.19-1)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 revolv

4、ing either clockwise or counter-clockwise.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 ma

5、chines and horizontal spindle milling machines.Milling machines may be grouped into various classes.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 class

6、ified 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.The spindle of the milling machine is driven by an electric moto

7、r 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.19-2)is provided with a table that may be swiveled on the transverse slide for milling gear teeth,threads,etc.Fig

8、.19-2 Universal milling machine Various attachments are used for increasing the range of work that can be performed on a milling machine.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

9、required position while the cuts are being made.Various kinds of vises may be used for holding the work in a milling machine,the most common being the plain vise,and the swivel vise.LEARN TO SPEAKMiss 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

10、 the machine tools.Could you give me a favor?Mr.Liu:Yes,my pleasure.What are these problems?Miss Li:What can shaper and planer do?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

11、shape and planers 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.Miss Li:But,for mass production,what methods s

12、hould 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.Liu:The feed is

13、 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.NEW WORDS AND PHRASES remove v.旋转，运行 mount v.固定，安装 arbor n.刀杆，心轴 spacer n.衬套，衬垫，垫片 bushing n.轴套，衬套 yoke n.刀杆支架 slit v.切开 n.切口，切缝

14、 clockwise adj.顺时针的 n.顺时针 regular adj.规则的，对称的 particular adj.特别的，单个的 horizontal adj.水平的 n.水平线 various adj.不同的，多样的 variation n.变化，改变 knee n.(铣床)升降台 universal adj.万能的，通用的 elevate vt.升高，提升 index n.(铣床)分度头；指针 stock n.台，座 vt.储存，供应 transverse adj.横向的 n.横梁 attachment n.附件机构，装置 vise n.虎钳，台钳，夹具 vt.(用虎钳，台钳)钳住

15、，夹紧 remove from 从除去according to 根据，视而定，按照be divided into 分成be grouped into 分类为be provided with 装有，备有 NOTES1The milling machine is a machine that removes metal from the work with a revolving milling cutter as the work is fed against it.铣床是一种当工件向铣刀进给时，铣刀旋转着从工件上切除金属的机床。“that”引导定语从句，修饰“machine”；“as”引导时间

16、状语从句，意为“当时候”。2Regular or irregular shaped work may be produced on a milling machine,designs varying according to the particular class of work wanted.在铣床上可以加工规则的或不规则的工件，铣床结构的不同取决于所要加工工件的类型特点。“irregular”一词中，“ir-”为前缀，意为“不、非”。3The table of the plain milling machine may travel only at right angles to the

17、 spindle,while the universal milling machine(as shown in Fig.19-2)is provided with a table that may be swiveled on the transverse slide for milling gear teeth,threads,etc.普通铣床的工作台只能沿着垂直于主轴的方向运动，而万能铣床(如图19-2所示)在铣削轮齿、螺纹等时，工作台可以在横向滑板上转动。这句较长，它是由连词“while”连接的表示转折的并列句。在第二个句子中，“that”引导的从句作定语修饰“table”。EXERC

18、ISES1Place a“T”after sentences that are true and an“F”after those that are false.(1)The milling machine is a machine that removes metal from the work with a stationary milling cutters as the work is fed against it.()(2)A large proportion of milling machines are of the type having the worktable adjus

19、table for height.()(3)The worktable may be moved longitudinally by hand or automatically,in one direction.()(4)The dividing head(also called an index head)is a device used to divide the diameter of a piece of work into any number of required position while the cuts are being made.()(5)The vertical s

20、pindle milling machine is so called because the axis of rotation of the spindle is horizontal.()2Fill the blanks with the words and expressions given below:swivel(ed),most,high speed steel,vertically or horizontally,least,fixed,ordinary tool steel,clockwise or counter-clockwise,dividing,putting.(1)T

21、he milling cutters are generally made from_and are available in different sizes and shapes.(2)The universal milling machine is provided with a table that may be _on the transverse slide for milling gear teeth,threads,etc.(3)These cutters may differ in the direction of their operation,i.e.they may cu

22、t revolving either_or_.(4)Indexing is the process of_the periphery or face of a work-piece into any number of equally spaced divisions.(5)Various kinds of vises may be used for holding the work in a milling machine,the_common being the plain vise,and the swivel vise.3Answer the following questions:(

23、1)Define the metal-cutting operation called“milling”.(2)What is a milling cutter?(3)Name the three principal types of milling machines.(4)How does a universal milling machine differ from a plain milling machine?READING MATERIALGrinding MachinesA grinding machine is a machine which employs a grinding

24、 wheel for producing cylindrical,conical or plane surfaces accurately and economically and to the proper shape,size,and finish.The surplus stock is removed by feeding the work against the revolving wheel or by forcing the revolving wheel against the work.There is a great variety of grinding machines

25、.The machines that are generally used are cutter grinder,surface grinder,centerless grinder,external grinder,internal grinder,and tool grinder.These machines are usually classified as to size by the largest piece of work which they can completely machine(as 618 inch External grinder).Five types of g

26、rinding operations are performed on grinding machines,as shown in Fig.19-3.Fig.19-3 Five types of grinding operations(1)Cylindrical grinding.Exterior cylinders and tapers are ground on plain grinding machines and on centerless grinders.The construction of universal grinding machines is similar to th

27、at of plain grinders.They are equipped with an internal grinding attachment,however,no that they can do both cylindrical and internal grinding.(2)Internal grinding.Interior cylinders and tapers are ground on internal grinding machines and on centerless grinders.(3)Surface grinding.Plane surfaces are

28、 ground on several types of surface-grinding machines.(4)Tool and cutter grinding.Reamers,milling cutters and other tools are sharpened on tool and cutter grinding machines.(5)Form grinding.Some machine tools such as thread,and gear grinders are designed especially for form grinding.Plain grinding m

29、achine.A plain grinding machine illustrated in Fig.19-4 is essentially a lathe on which a grinding wheel has been substituted for the single-point tool.Fig.19-4 Plain grinding machine Principal parts of a plain grinding machine are as follows:(1)Base.The main casting of a plain grinding machine is a

30、 base that rests on the floor.(2)Tables.A sliding table,which is mounted on ways at the front and top of the base,may be moved longitudinally by hand or power to feed work-pieces past the face of the grinding wheel.If the centerline of the swivel table is set at an angle,a taper will be ground.(3)He

31、adstock and tailstock.A motor-driver headstock and a tailstock are mounted on the left and right ends,respectively,of the swivel table for holding work-pieces on centers.The headstock center on a grinder is a dead center;that is both centers are“dead”to insure concentricity of the periphery of groun

32、dwork 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.Either of two methods may be used to

33、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 at each reversal should be from

34、 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 required diameter.No longitudinal f

35、eeding motion is used.PROFESSIONAL WORDS AND PHRASES conical adj.圆锥(体，形)的 surplus n.过剩，剩余 exterior adj.外面的 taper n.锥形，锥度 v.逐渐变细 sharpen vt.使锐利，变尖 substitute n.代替者 v.代替，替换 base n.床身 concentricity n.同轴度 periphery n.圆周，圆柱表面 infeed n.横向进给 interior adj.内(部)的 grinding machine 磨床 surplus stock 余量 cutter gr

36、inder 工具磨床 surface grinder 平面磨床 ceterless grinder 无心磨床 external grinder 外圆磨床 internal grinder 内圆磨床 exterior cylinder 圆柱体外表面 universal grinding machine 万能磨床 internal grinding attachment 内圆磨头 form grinding 成形磨削 single-point tool 单刃车刀 traverse-cut grinding 横向磨削 plunge-cut grinding 横向全面进给磨削 interior cylinder 圆柱孔