Circumferential circle process modulo null magnetic body of revolution finishing

摘要

PURPOSE:To prevent a shift between the center of a magnetic rotary body adapted to be used in an automobile anti-lock system and the center of a hole so as to obtain a precise output characteristic by machining the bore of the magnetic rotary body, and by remachining the bore after heat-treatment. CONSTITUTION:A magnetic rotary body 1 which has been produced by a powder metallurgy method is formed therein with a hole 1b in a predetermined method with such a degree of accuracy that a bearing 2 or the like is fitted therein. Then, all surfaces of the magnetic rotary body 1 are subjected to a baking-finish heat treatment process. The rotary body formed thereon with a surface treatment film is set on the bottom surface 2b of a recess 2a in a working table 2 in such a condition that the side surface 1a of the rotary body 1 makes contact with the recess surface without being bound. Further, after the center of the hole 1b in the rotary body 1 being aligned with the center of a broach 3, the latter is moved in the direction of the arrow and is made to pierce through the hole 1b. The maximum diameter of the branch 3 is made to be substantially equal to the inner diameter of the hole 1b before surface treatment, and accordingly the surface treatment file of the hole 1b is removed, thereby it is possible to obtain a precise hole which has been obtained before the surface treatment.