| 摘要 |
The drill has a long shaft (2), a shank (5) at one end, and a boring head (10) with cutters at the other. An annular shoulder (6) is arranged on the shaft facing the boring head (10). The latter includes centring cutters. These retreat back from the centring tip, itself located on the extended shaft axis, to the boring periphery. The boring head also carries an auxiliary cutter. This extends normal to the shaft axis, a portion projecting beyond the shaft circumference. The portion is 10%-100% of its total extension |
