| 摘要 |
PROBLEM TO BE SOLVED: To provide a cross recess for a screw with a projection, of which contact part is gradually crushed by partial contact to be tightly fitted to a driver bit from eight directions to increase the galling force, and to obtain the strong galling force for surely galling the driver bit. SOLUTION: This cross recess 1 for a screw is formed with a molding recessed part 7, which is formed of an inlet projection 5 and an inside projection 6, by projecting at four positions in an upper end of a cross root 9 of the screw hole. COPYRIGHT: (C)2004,JPO
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