JP2748990B

PURPOSE:To prevent both vibration of the axial center of a blow pin and fluid leakage of a parison and to prevent generation of a sink by freely rotatably providing the inner pipe of a blow pin engaged in a double tubular shape and providing a plurality of pieces of blowout holes of fluid in the direction crossing the axial line of the blow pin to the tip part of the sharp inner pipe and preventing rotation of an outer pipe. CONSTITUTION:The tip part 11a is stuck into a parison 1, by advancement of a blow pin 9 and inserted into the parison 4. When a piston rod 17 reaches the advancement limit and an unrotated outer pipe 12 is positioned in the parison 4 part, an inner pipe 11 is rotated by actuation of a motor 19 and also fluid such as air is force-fed through a passage 22. Thereby the air is introduced into a passage 20 of the inside of the blow pin 9 from a passage 21 and allowed to flow out from the injection holes 13 of the tip part 11a while being rotated in the inside of the parison 4. Therein fluid leakage to the outside of the parison from the inside thereof is not caused because the outer pipe 12 is not rotated. The parison 4 is expanded in a cavity 5 and thereby becomes a prescribed shape and also the inside of the parison 4 is uniformly heated or cooled. Inconvenience such as a sink and failure in elongation and shrinkage is not caused.