| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot bulge forming apparatus capable of suppressing generation of a sink mark at a center portion in the length direction of a workpiece. SOLUTION: In the hot bulge forming apparatus 1, a preliminarily heated tubular material 10b is placed at a cavity 33A of dice 21A, 31A, air is supplied into the tubular material 10b, and the tubular material 10b is pressed to cavity surfaces 211A, 311A by the air pressure so as to be molded. Thereafter, a tubular material 10c is placed at a cavity 33B of dice 21B, 31B, air is supplied into the tubular material 10c, and the tubular material 10c is pressed to cavity surfaces 211B, 311B by the air pressure so as to be molded while the tubular material 10c is cooled by the cavity surfaces 211B, 311B. Projecting portions 331 having a circular-arc shape in cross section are formed at parts of the cavity surfaces 211A, 311A to which the end side in the length direction of the tubular material 10b is pressed. COPYRIGHT: (C)2011,JPO&INPIT |
