53 巻 (2012) 612 号 p. 54-58
A hot metal gas forming process for an aluminium alloy tube using sealing pressure and resistance heating was developed. In this process, the sealed tube is bulged by resistance heating without controlling internal pressure. A hot metal gas forming process for an aluminium alloy tube without and with axial feeding was carried out. The deformation behaviour of the tube inside the die was observed through a heatproof glass plate attached to the side wall of the die. The sealing pressure, current density, timing of axial feeding, feeding velocity and amount of axial feeding were optimized. For excessive sealing pressure, fracture occurred, and the tube partially melted at a small sealing pressure and a large current density. Since the temperature of the tube rapidly drops after coming into contact with the die, the axial feeding before the contact is effective in preventing fracture. A ceramic die with a small thermal conductivity is useful for improving the temperature decrease and die filling.