| 摘要 |
PURPOSE:To extremely improve working efficiency, by supplying electric power to a material to be worked, and compensating a sudden change of a current, to as to coincide with the timing with the time point when executing a plastic working means. CONSTITUTION:A material to be worked 1 is electrified and heated from a heating electric power supply 6, also a temperature of the material to be worked 1 is measured by a temperature detector, and voltage is controlled by a controlling circuit so as to be raised to a temperature set in advance. Electric resistance is suddenly changed in a point where a structure stage of the material to be worked 1 is changed suddenly, therefore, if this sudden change has been detected, an optimum working temperature, that is to say, a structure state whose plasticity is highest is obtained by raising a temperature of the material to be worked 1 by a prescribed temperature from said temperature. Subsequently, an inclination of plasticity is provided in the axial direction by blowing cooling gas to the material to be worked 1 from nozzles 11 of each air nozzle block 7, 8 and 9. Subsequently, when a chuck 3 is moved in the direction as indicated with an arrow and is elongated in the axial direction, an estimated thin diameter part (c) is elongated longest and becomes a thin diameter (c), and other part is elongated by different elongation percentage in accordance with plasticity, and becomes a tapered rod having a tapered part (b). |
