| 摘要 |
In a cold forming tap of the embodiment, those projections, which constitute a part of the projections and are axially adjacent to one another, are removed to valley bottoms, and cutting blades, a diametrical dimension of which corresponds to a thread inside diameter of a female thread that should have been formed at portions corresponding to the valley bottoms of the removed projections, are formed. In manufacturing the cold forming tap, a maximum diameter of a valley bottom is not formed in relief portions contiguous to projections of male thread portions but concave and convex configurations of peaks and valleys are in synchronism with one another in a circumferential direction, so that peaks and valleys of the male threads can be efficiently formed at one time with high precision in a processing called a thread grinding, in which grinding is carried out by a grinding stone formed at its outer peripheral surface with threads, and a dimensional management of the male threads is made much easy to enable easy and inexpensive manufacture of high-precision cold forming taps. |
