| 摘要 |
PURPOSE:To improve stability of a deep hole processing drill which uses throwaway tips during its operation by providing a center drill in the middle part of a main body of said drill and installing right and left tips so as to make a special tip angle with each other. CONSTITUTION:A main body 1 of a nearly cylindrical drill with a notch part 2 for discharging chip on its periphery is provided, in the middle part of its tip, with a hole 3 into which a center drill 4 is inserted and fixed with a screw 5a. Equilateral triangular throwaway tips 6 are fixed on both sides of the tip part of the main body 1 by means of a screw 5b in such a way as their cutting edges 6a form a tip angle theta of 120 deg. with each other. An oil hole 7a, passing through the interior of the drill main body 1, branch off at the tip into a discharging port 8a in the vicinity of the tip 6 and a discharging port 8b for the center drill 4. At the time of processing, the center drill 4 performs a guide motion to control whirling at starting and during hole processing, besides excellent cutting can be executed due to the tip angle of 120 deg. of tips 6. |
