| 摘要 |
The piloted drill tip (14) is located at the leading end of drill bit (10) and which has a diameter less than the drill bit (18) diameter. The tip (14) is securely fastened, usually by brazing, to the leading end of the drill bit. The tip provides better penetration, line holding and spoil removal than with existing drill bits. In one arrangement, the leading end of the drill bit (10) is machined to define a slot (22) into which is inserted a combined-drill tip (16) and piloted tip (14) of reduced diameter, to be inserted and brazed in position. The tips (14, 16) can be separate and coupled by a slotted coupler (30). <IMAGE> |
