| 摘要 |
PROBLEM TO BE SOLVED: To provide a die for manufacturing a screw part having improved loosening preventive effect, and a manufacturing method therefor. SOLUTION: One pair of flat dies 30, 40 are the dies for applying form-rolling to thread ridges 20 of a step-lock-bolt 10 having both flanks 21 and 22 formed in such a manner that flat parts 21a and 22a and tilted parts 21b and 22b alternately continue. Then, in the fixing side flat die 30, flat projecting line parts 33a and tilted projecting line parts 33b in the form-rolling surface 31 are respectively formed by electrical discharge machining with the use of flat electrical discharge parts 52a and tilted electrical discharge parts 52b of respective projecting lines 51 for electrical discharge machining arranged in an electrode 50 for electrical discharge machining, and further, the form-rolling surface 41 of the moving side flat die 40 is formed similarly. COPYRIGHT: (C)2009,JPO&INPIT
|
