| 摘要 |
By screwing a threaded shaft (24) provided on a tip (14) into a threaded hole (26) provided on a body (12), the tip (14) is detachably installed on the body (12). Additionally, a restraining part (40) of the tip (14) is fitted into a restraining hole (38) provided in the body (12) and the body (12) and the tip (14) are positioned to be concentric with the shaft center (O). As a result, a separate installation screw is unnecessary and the tool is configured from two parts, the body (12) and the tip (14). Therefore, high centering precision is easily obtained. Additionally, the cross-sectional areas of the respective parts increase and strength increases, variation in tool life is limited, and excellent tool life can be stably obtained. Moreover, because the surface (24f) of the tip of the threaded shaft (24) is pressed to adhere closely to the bottom surface (26f) of the threaded hole (26) and the tip (14) is fixed to the body (12) to form a unit, a compressive stress acts on the threaded shaft (24) and the tip (14) can be fastened to the body (12) with a higher fastening strength than when a tensile stress is in operation. |
