| 摘要 |
A screw with a polygonal hole (30) formed with a polygonal hole (32) disposed in the center of a screw head (30a) and comprising a vertical wall (33) with a preset depth, and with a cone base oriented from the lower edge of the vertical wall toward the center of a screw neck, wherein a vertical step forming an inscribed circle of the polygon is provided at the lower edge (33a) of the vertical wall (33) of the polygonal hole (32) formed in the screw head (30a), the cone base (35) oriented from the lower edge (34a) of the vertical step (34) toward the center of the screw neck is formed, and a driver bit (40) or wrench (41) to be fitted to this screw is provided at the tip of a peak edge (42) with a cylindrical projection (44) forming the inscribed circle of the polygon. <IMAGE> |
