| 摘要 |
A rock drill bit of the impact type comprising a boring head, a shaft having ridges, a front surface and a number of peripherally spaced holes receiving inserts, said holes extending forwardly and outwardly at an acute angle phi with respect to the center line of the drill bit. The guiding surface of the insert mainly coincides with the jacket surface of the bit body when the insert has been fixed in the hole which emerges into both the jacket surface and the front surface of the bit body. This means that the guiding surface partly extends on both sides of the plane of the front surface. |
