MALE SCREW BODY, FEMALE SCREW BODY, SCREW BODY DESIGN METHOD, SCREW THREAD STRUCTURE

摘要

A male screw body comprises a shaft part, a first spiral groove that is formed in a circumferential surface of the shaft part and that is set at an appropriate lead angle and/or lead direction, and a second spiral groove that is set at a lead angle and/or lead direction that is different from the lead angle and/or lead direction of the first spiral groove, wherein the thread angle formed by a pair of inclined surfaces that extend from the apex to the valley of a screw thread that is created as a result of the first spiral groove and the second spiral groove being formed to overlap is established at 61°-75°. It is thus made possible for a male screw body to have two types of overlapping spiral grooves with different lead angles and/or lead directions to retain high fastening force.