PURPOSE: To mold the internal form of a cylindrical body accurately to predetermined size by holding airtight properties between the nose of the cylindrical body inserted into a core and the outer circumferential surface of a rear die by using a ring slidably inserted into the core.
CONSTITUTION: When the end section of a tube body 1 previously heated is inserted into a core 10, the diameter of the end section is increased by a taper 11a formed at the rear section of a front die 11 and a taper 11a shaped at the front section of an intermediate split die 13, and the end section continues to an annular projection 13b. When an intake is started through intake paths 14W17 while a ring 20 is retreated in the direction of the center of the arrow at approximately the same time as the starting of the intake, the ring 20 is separated from the nose section of the tube body 1, and the tube body 1 is molded to a final shape. The intake is stopped, water is sprinkled over the tube body 1 to solidify the tube body, the diameter of the intermediate split die 13 is reduced and made the same as or smaller than those of the front die 11 and a rear die 12, the ring 20 is advanced to the center of the arrow, and the tube body 1 is pulled out of the core 10.
SUZUKI KATSUICHI
NODA KIMIO
