SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING Various attempts have been made to prevent this effect. in particular by continuing rotation without any further cutter infeed but if the shaping machine is not very rigid and the cutter very sharp then no further cutting will occur and the error will not be removed Hobbing Hobbing, the most used metal cutting method, uses the rack generating principle but avoids slow reciprocation by mounting many racks" on a rotating cutter. The tacks"are displaced axially to form a gashed worm. The" racks "do not generate the correct involute shape for the whole length of the teeth since they are moving on a circular path and so the hob is fed slowly along the teeth either axially in normal hobbing or in the direction of the helix in"oblique" hobbing gash深砍,划开worm蜗杆helⅸx螺旋线 oblique倾斜的SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING Various attempts have been made to prevent this effect, in particular by continuing rotation without any further cutter infeed but if the shaping machine is not very rigid and the cutter very sharp then no further cutting will occur and the error will not be removed. Hobbing Hobbing, the most used metal cutting method, uses the rack generating principle but avoids slow reciprocation by mounting many "racks" on a rotating cutter. The "tacks" are displaced axially to form a gashed worm. The "racks" do not generate the correct involute shape for the whole length of the teeth since they are moving on a circular path and so the hob is fed slowly along the teeth either axially in normal hobbing or in the direction of the helix in "oblique" hobbing. gash 深砍，划开 worm 蜗杆 helix 螺旋线 oblique 倾斜的