| 摘要 |
PURPOSE:To promote cutting force, breaking force and durability by arranging alternately two kinds of bits into which angle-shaped carbide tips are buried at proper intervals to the ends of excavation head bodies so as to have a different radius of gyration in a cutting section. CONSTITUTION:Carbide tips 4 having angle-shaped cut and penetration sides are buried into shanks 3 at proper intervals and, at the same time, V-shaped channels are provided to intermediate sections of the shanks between the tips 4, and two kinds of bits 1 and 2 having different arrangements of the tips 4 are formed. After that, the bits 1 and 2 are arrange alternately to the ends of excavation head bodies 7 so as to have a different radius of gyration tracks in a cutting section. The excavation heads 7 are rotated to excavate. According to the constitution, the excavation heads having excellent excavation force, breaking force and durability can be obtained. |
