Lecture FourPart B: Exercises1 Answer the foUowing questins accordii to the text(X)Define the metal-cutting operation called u milling. What is a milling cutter? Name the three principal types of milling machines - How does a universal milling macliine dififer from a pladn milling machine? The milling machine is2. Translate the following sentences into Chinesea machine that removes metal from the work with a revolving milling cutter as the work is fed against it. Regular or irregular shaped work may be produced on a milling machine, designs varying according to the particular class of work wanted The table of the plain milling machine may travel only at right angles to the spindle while the universal milling macliine (Fig 3 - 2) is provided with a table that may be swiveled on the transveree slide for milling gear teetli, threads, etc Lesson 4 Grin ding MachinesPart A： TextA grinding machine is a machine which employs a grinding wheel for producing cylindrical ,conical or plane surfaces accurately and economically and to the proper shape， size, and finish. Hie 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 The machines that are generally used are cutter grinder surface grinder, centerless grinder, external grinder, internal grinder, tool grinder. These machines are usually classified as to size by the largestpiece of work which they can completely niachine(as 6 x 18 inch external grinder).Five types of grinding operaticms are performed on grinding machines：1. Cylindrical Grinding Exterior cylinders and tapers are ground on plain grinding machines and on centerless grindeTSHie construction of universal grinding machines is similar to that of plain grinder TTiey are equipped with mi iiilenial grinding allachinent, however, so that they can do both cylindrical and internal grinding.2. Internal Grinding Interior cylinder and tapers are ground on internal grinding machines and on centeriess grinder? 3 Surface Grinding, Plane surfaces are 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 Machine A plain grinding machine, illustraXed in Fig 4.2 is essentially a lathe on which a grinding wheel has been substituted for the sirie-point tool.Principal Parts of a Plain Grinding Machine1) Base The main casting of a plain grinding machine is a base that rests on the floor.internal grindingsurface grindingcylindricaJ grindingtool and cutter grindingform grindingFig 4 1Five Types Grinding Operations2) 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 sei at ar angle, a taper will be ground,3) Headstock and Tailstock. A motor-driven headstock and a tailstock are nwnted on the left and riht ends，respectivelyt of the headstock center on a grinder is a dead center; that is both centers are “deacT to insure concentricity of the periphery of ground work with its axis.4) Wheel Head. A wheel head that carries a grinding wheel and its driving motor ismounted on a slide at the top and rear of the base. The wheel head may be moved perpendicularly to the table w&ys, by hand or power, to feed the wheel to the work.Either of two methods may be used to grind cylinder and tapers on plain grinding machines- In traverae-cut grinding, the workpiece is fed longitudinally past the face of thegrinding wheel,and the wheel is fed towanl the work after each reversal of the table until the piece is finished to size. The infeed at each reversal should be from 0.001 to 0.005 grinding wheel that has a face width equal to or sliglitly longer than the surface of surfaces being ground is employed and is fed transversely until the woricpiece has the r ameter. No longitudinal feeding motion is used.infor mihing and from 0.5 to 0-002 5 in. for finishing In plunge-cut grinding aheadstockcxmtrol leversnooLuuwuriwheel headFig.4.2 Flam Grinding MachiiwWords and Termsconicala suiplusn surplus stock cutter grinder surface grinder external grinder internal grinder exterior n interior cylinder 、Ui|)er n.univeraal grinding machine attachment n intenial grinding attachment shaipen 讥 fom grinding substitute n & n single-point tool（圆）锥（形状体）的 过剩剩余余量工具磨床 平面磨床 外圆磨床 内圆磨床 外（面表） 圆柱体外表面 斜度圆锥形 逐渐变尖 万能磨床 附件内衬磨削附件刃磨削尖 成型磨削取（替）代;代替单刃车刀