| 摘要 |
PURPOSE:To execute chamfering with high accuracy by pressing the outside peripheral surface of a rotary tool of an inverted thread in which a pitch and a lead angle are equal to a thread of a thread rolling round die and a chamfering part of the thread rolling round die and rotating one of them, while supplying abrasive grains to a contacting part. CONSTITUTION:Thread rolling round dies 30a, 30b are pressed against a rotary tool 32 by pressure P respectively, and threads 34a, 34b in end parts 36a, 36b and an inverted thread 40 are engaged to each other. Thereafter, a work liquid 42 containing abrasive grains is supplied to their contacting part and by bringing one side thread rolling round die 30a to forced rotation, the rotary tool 32 and the other side thread rolling round die 30b are turned together. As the thread rolling round die 30a rotates, the abrasive grains are pressed repeatedly against the end parts 36a, 36b, a brittle decomposed layer by working is formed on its surface, a minute crack is generated before long and its decomposed layer is crushed and eliminated. Since such crushing is repeated, roundness chamfering can be executed with high accuracy. |
