| 摘要 |
The present invention relates to a rotary drill bit for rock drilling and a roller cutter therefore. The rotary drill bit (10) comprises a bit body (11) and three roller cutters (12, 13, 14), each said roller cutter being rotatably mounted on a journal (15) protruding from the bit body. Each roller cutter has a substantially conical basic shape with a base (16) facing towards the periphery of the drill bit and a top (17) essentially facing towards the center of the drill bit. A number of buttons (18-20) are provided on each roller cutter in circumferential rows. Each button has a working end which during rotation of a roller cutter comes into engagement with the rock and thereby is provided to form a surface of attack with the rock. A first row (I) next to the base comprises button (18) the length of attack of which against the rock is greater in the rotational direction (R) of the roller cutter than perpendicularly thereto. A second row (II) provided beyond the first row (I) in direction from the base (16) comprises buttons (19) the length of attack of which is greater in the rotational direction (R) of the roller cutter than perpendicularly thereto. A third row (III) provided beyond the second row (II) in direction from the base (16) comprises buttons (20) the length of attack of which in the rotational direction (R) of the roller cutter is smaller than the length of attack in the rotational direction (R) of the buttons (18, 19) in both the first and the second rows (I, II).
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