| 摘要 |
PROBLEM TO BE SOLVED: To provide a throwaway type drill capable of easily and precisely centering a cutting blade chip to install in a straight mounting groove on a main body head end, simple in structure and easy to manufacture. SOLUTION: A round hole 6 concentric with a rotational center is provided on a groove bottom part of the mounting groove 5 provided on the head end of the main body 1. Centering of the chip is carried out by making the round hole 6 a hole having an inside diameter of the same diameter as or more than center thickness of the drill and making it cut through in a torsional groove 2 and fitting a round shaft part 21 provided in correspondence with the cutting blade chip 20 in the round hole 6. Additionally, elastic deformation of jaw parts 7 is facilitated by setting the round hole 6, and the chip 20 is held by a pair of the jaw parts 7 and fixed.
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