| 摘要 |
PROBLEM TO BE SOLVED: To prevent the sore of the leading end surface of a press member or the heating and softening of the bottom part of a preform by forming the leading end surface of the press member into a protruding surface and providing a large diameter metal core to the central part thereof and forming the central part of the contact surface of the press member by the leading end surface of the metal core and connecting the rear end part of the metal core to a metal rod. SOLUTION: The leading end surface of the press member 12 of a drawing rod 10 is formed into a protruding surface and a metal core 13 made of aluminum is inserted in the screw hole 14 bored in the central part thereof to be screwed in the screw hole 15 within the leading end of a metal rod 11 from its leading end surface and the press member 12 is threaded with the leading end of the metal rod 11. Further, the central part 16 of the contact surface of the press member 12 is formed by a countersink. Since the central part of the press member 12 is composed of the metal core 13 good in heat conductivity, the heat accumulation quantity of the press member 12 is little and the central part 16 of the contact surface always precedes at a time of drawing to closely come into contact with an inner bottom surface to stretch a bottom part and, therefore, the heat effect on the peripheral edge part of the press member 12 from the bottom part is reduced and the problem caused by heat accumulation is hard to generate. |
