| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a multi-pitch screw, which has desirable threads and pitches, through rolling. SOLUTION: A locus of a general helical screw (having a constant lead angle) is formed using constant pitch projections 610, 620 of existing rotary dies 61, 62, and then the locus is superposed onto a locus of a step-wise screw, which is formed using a step-wise projection 632 of a rotary die 63 having inconstant lead angles. Thereby, a multi-pitch screw thread is efficiently manufactured by rolling. In this case, since only one piece of the rotary die 61 having inconstant lead angles is used, the thread is not smoothed by the step-wise projections of a plurality of rotary dies having inconstant lead angles. COPYRIGHT: (C)2006,JPO&NCIPI |
