PURPOSE: To prevent forming goods from being cracked due to overheating by measuring electric power supplied to a plank material and a push-in quantity of the blank material, and controlling electric power so that a value of electric power/push-in quantity per unit time and electric power/unit volume becomes a reference value, when manufacturing upsetter forming goods by a direct electric conduction heating system.
CONSTITUTION: A blank material 1 is pressed against a anvil 2 by an hydraulic cylinder 3, also the lower part is held by an electrode 4, and the blank material 1 is subjected to electric conduction and is softened by the anvil 2 and the electrode 4, by which forming is executed. In this case, voltage, a current, a power factor and a push-in quantity of the blank material 1 are measured by a measuring part 10, its result is inputted to an operating part 11, electric power/unit volume is derived by calculating electric power per unit time and a push-in volume, and it is inputted to a comparing part 12. In the comparing part 12, a reference value C set in advance is compared with the electric power/unit volume, this value is fed back to voltage, the voltage is controlled so as to become C=electric power/unit volume, by which forming goods are prevented from being cracked due to overheating.
NAKAMURA TERUSHIGE
SHIRAI TOSHIO
