SCREW WITH BIT ENGAGEMENT HOLE, COMBINATION OF GROUPS OF SCREWS WITH BIT ENGAGEMENT HOLES AND DRIVER BITS, AND GEOMETRY SETTING METHOD FOR BIT ENGAGEMENT HOLE

摘要

PROBLEM TO BE SOLVED: To provide a screw with a bit engagement hole extensively elongating a service life of a punch forming a step part in a blade engagement groove, not causing buckling or the like of a fiber flow, and of a shape with superior biting characteristics.;SOLUTION: The bit engagement hole 4 is equipped with a center hole part 5 formed along an axis line N passing through an axis of a shaft part 1, and a plurality of the blade part engagement grooves 6 radially extending from the center hole part 5. A groove end wall of the blade part engagement groove 6 is equipped with an inclined plane part 71 inclined in a direction approaching the axis line N toward a bottom 51 of the center hole part 5, and a parallel part 73 connected to the inclined plane part 71 via an inclined step part 72 and extending toward a head top face 31. The inclined step part 72 is composed such that it is slanted in a direction wherein an inner end becomes deeper than an outer end with respect to an orthogonal line orthogonal to the axis line N.;COPYRIGHT: (C)2010,JPO&INPIT