| 摘要 |
A driver bit or wrench and screw combination wherein the arrangement of the front end of a driver bit or wrench tip edge is improved to make it possible to effectively prevent the come-out phenomenon of said bit or wrench and the arrangement of the portion of an applicable screw abutted by the front end of said tip edge is likewise improved to develop a screw holding function, whereby the proper and quick screw tightening operation is always achieved and the operating efficiency is greatly improved, wherein the front end of a polygonal tip edge is provided with a cylindrical projecting portion forming a circle inscribed in a polygon, the front end surface of this cylindrical projecting portion being in the form of a conical protrusion, a projection is locked in the central portion of said conical protrusion, an extension edge is provided which is formed with a vertical wall vertically extending from said tip edge, the screw head is centrally formed with a polygonal hole defined by a substantially vertical wall surface extending to a required depth, and a conical bottom surface is formed which extends from the lower end of this vertical wall surface toward the center of the screw head; thus, the driver bit or wrench is suitable for use with such screw with a polygon socket head.
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