| 摘要 |
PROBLEM TO BE SOLVED: To prevent carbide tips from dropping out because of abrasion of the base material resulting from excavating soil. SOLUTION: Front carbide tips 11-1 are fixed to the corners between the front face 21 and both side faces 23, 23 of a base material 10 respectively, in the fishtail bit. And end part carbide tips are fixed to the corners between the end face and both side faces 23, 23 of the base material 10 respectively. In this way, since excavated soil moves to the cutter head along the side faces 11a of the front carbide tips 11-1 and the side faces of the end part carbide tips, the base material is protected from abrasion and hence, the carbide tips are protected from dropping out. |
