PURPOSE: To make a drilling tool in a throwing away style and thus to maintain the cutting performance of the drilling tool by providing the main body of the drilling tool with a plurality of throw-away tips at the free end thereof.
CONSTITUTION: A drill main body 1 is provided with chip-discharging grooves 11 and 12 and several tip-mounting seats 13 and 14 at the top. In the tip-mounting seat 13, a central cutting tip 17 is detachably fixed by a clamp wedge 18 and a screw 19, while in the tip-setting seat 14, a circumferential cutting tip 20 is similarly fixed detachably by a clamping device. The cutting tips, when worn out, can be thrown away and replaced by tips available on the market. This construction serves to maintain the cutting efficiency of the tool.
TANIMOTO IWAO
TOYOTA MOTOR CO LTD