| 摘要 |
PROBLEM TO BE SOLVED: To provide a screwdriver tool for removing a screw in which the tip of an operation part can be prevented from being broken when the operation part is driven in a cone-shaped damaged concave part, and furthermore, by making an operation edge bitten into the damaged concave part by weaker power, the loosening operation of the screw can be surely performed.SOLUTION: A valley groove 14 comprising a first valley surface 15, a second valley surface 16 and a bottom surface 17 is formed at an operation part 3 to be extended from the peripheral wall surface 22 of the operation part to the tip surface 23 of the operation part. Each rib-shaped projection 13 comprises: the first valley surface 15 and the second valley surface 16 of the valley groove 14 which are opposed to each other while interposing the rib-shaped projection 13 therebetween; and a rib peripheral surface 18. A tip sloping surface 19 is formed at the tip surface 23-side end of the rib peripheral surface 18. The operation edge 20 bitten into the damaged concave part 9 is formed at a ridge line where the second valley surface 16 and the rib peripheral surface 18 are made to cross each other. A biting edge 21 is formed at another ridge line where the rib peripheral surface 18 and the tip sloping surface 19 are made to cross each other. A first sloping surface 24 extended over the tip sloping surface 19, the tip surface 23, the first valley surface 15 and the bottom surface 17 is formed to form the tip sloping surface 19 to be an inverted trapezoid shape. |
