123 6.6 GEAR MANUFACTURING Introduction（123年6.6齿轮制造业的介绍）.pdf

Valery Marinov, Manufacturing Technology Gear Manufacturing 123 6.6 GEAR MANUFACTURING Introduction Because of their capability for transmitting motion and power, gears are among the most important of all machine elements. Special attention is paid to gear manufacturing because of the specific require- ments to the gears. The gear tooth flanks have a complex and precise shape with high requirements to the surface finish. Gears can be manufactured by most of manufacturing processes discussed so far (casting, forging, extrusion, powder metallurgy, blanking). But as a rule, machining is applied to achieve the final dimensions, shape and surface finish in the gear. The initial operations that produce a semifinishing part ready for gear machining as referred to as blanking operations; the starting product in gear machining is called a gear blank . Two principal methods of gear manufacturing include Œ gear forming, and  gear generation. Each method includes a number of machining processes, the major of them included in this section. Gear forming In gear form cutting, the cutting edge of the cutting tool has a shape identical with the shape of the space between the gear teeth. The principle of gear forming. Two machining operations, milling and broaching can be employed to form cut gear teeth. Form milling In form milling , the cutter called a form cutter travels axially along the length of the gear tooth at the appropriate depth to produce the gear tooth. After each tooth is cut, the cutter is withdrawn, the gear blank is rotated (indexed), and the cutter proceeds to cut another tooth. The process continues until all teeth are cut. Setup of form milling. Form milling of a helical