| 摘要 |
PROBLEM TO BE SOLVED: To provide a suction mechanism which reduces manufacturing cost. ! SOLUTION: A bit 2 includes an engagement part 2a which is formed on a tip end of the bit and engages with a head part of a screw W, and is structured of: a small-diameter shaft part 2b connected to the engagement part 2a and formed in a dimension which does not contact with an insertion hole 3a; a connection shaft part 2c connected to the small-diameter shaft part 2b and formed in an outer diameter larger than the small-diameter shaft part 2b; and a large-diameter shaft part 2f connected to the connection shaft part 2c and formed in an outer diameter larger than the connection shaft part 2c. A metal fitting 3 is arranged on the bit 2. The metal fitting 3 includes a screwing part 3c screwing with the connection shaft part 2c, and a ventilation groove 3b arranged in a direction that the insertion hole 3a extends. The ventilation groove 3b is formed so as to reach the insertion hole 3a from one end of the metal fitting 3 |
