| 摘要 |
Drill crown has body with diamond-containing die placed at the end, separated with washing slots to working sectors with changing profile in cross-radial section of each working sector of crown, those alternate in perimeter of working end of the die. Sectors alternating in perimeter of working end of die are rectangular in shape, and as rectangular trapezoid. At that sectors that are in shape of rectangular trapezoid are equipped with more strong diamonds and are smaller in length and larger height of part of sector that comes compared to sectors that are rectangular in shape, and parts of leaving sectors that are in shape of rectangular trapezoid are at one level with working surface of sectors in rectangular shape. |
