| 摘要 |
According to the invention, an integral drill has a crown part 11 which is designed in its rear area with a conical waist portion 16. After the cutting edges or pins 12 in the crown front have become worn, the drilling equipment can be renewed by cutting off the front crown part level with the conical waist portion, after which the remaining rod part can serve as cone rod for attachment to a loose drill crown 20 by means of frictional fit. <IMAGE> |
