| 摘要 |
A rotary rock drill bit includes a bit body and three conical roller cutters rotatably mounted thereon. Each roller cutter has at least first, second, and third circumferential rows of buttons spaced apart in the direction of rotation of the roller cutter. The three rows of buttons are arranged successively from a rear end toward a front end of the roller cutter. The buttons of each of the first and second rows have lengths of attack which are longer in a direction of rotation of the roller cutter than in a direction perpendicular thereto. Those longer lengths of attack are also longer than a length of attack of the buttons of the third row in the rotational direction. |
