MANUFACTURE OF UNEQUAL TWISTED CHIP FOR CUTTING TOOL

PURPOSE:To form a long seamless unequal twisted chip easily by extruding a flat chip specified distance from a forming die having an unequal twisting groove and stopping without passing through the die. CONSTITUTION:A flat chip of sintered hard alloy is put in the linear groove 2 of a twist forming die 1 and extruded to a twisting groove 3 by a punch 4, and the extruding of the punch 4 is stopped at a position of the groove 3 at which a specified angle of torsion can be obtained. A part that plastic deforms the flat chip profiling the groove 3 is heated by a high frequency coil 5 to 1,000- 1,200 deg.C at which the flat chip can obtain sufficient capacity of deformation and material defects such as growth of particles etc. After plastic deforming the flat chip by the groove 3, the power source of the coil 5 is cut off, and released from a mold when the temperature of the chip becomes below 500 deg.C. It is necessary to divide an outliner 6 beforehand to make this releasing. By this method, manufacture of a long, seamless unequal twisted chip in which changing angle of torsion continues becomes possible, and the accuracy of torsion of each part of the chip is high.