| 摘要 |
PURPOSE:To apply the titled method to a twist drill having an oil hole and the like by preventing the deformation and deflection of a hole part through the application of forced torsional rotation to the external surface of the twist drill after extruding a raw material powder such as cemented carbide and cermet and forming a straight hole therein. CONSTITUTION:An extruding machine 4 mounted on an upper base 1 is secured in a fitting hole 5, and a raw material powder 7 in a fitting cylinder 6 is pressurized with a piston 8 or a screw. When the raw material powder 7 is kneaded in a clay state and made to pass an extruding nozzle 9, a straight hole 11 is formed with a core member 10. Then, forced torsional rotation is applied to the external surface of a rod-shaped material 3, thereby converting the straight hole 11 into a twisted hole 17. And in the case of applying cross sectional shape for a drill forming a pair of twisted grooves 29, two torsional rollers 24 are used to give a torsional rotary force to the external surface of the drill. According to the aforementioned constitution, the titled method can be applied to the twist drill having an oil hole, and the like.
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