When an injection stretch blow molding machine in which the molding cycle is tried to be shortened manufactures hollow molded bodies, blow molding in which shaping and cooling are simultaneously performed by blowing compressed air from a single compressed air supply source while discharging compressed air is performed to achieve energy saving for manufacturing hollow molded bodies.

A blowing apparatus 10 of a stretch blow molding apparatus 11 includes a compressed air supply source 32 configured to send out compressed air adjusted to have an air pressure at which an object to be shaped e is inflated to be shaped into a hollow molded body, an inflow passage 33 through which the compressed air from the compressed air supply source 32 flows to the internal space of the object to be shaped e disposed in a blow mold 8, and a non-closed outflow passage 34 through which the compressed air flows out from the internal space of the object to be shaped e to a discharging space outside the blow mold. In the entire process of the blowing operation by the blowing apparatus 10, a compressed air flow passage 36 is formed through which the compressed air from the compressed air supply source 32 flows through the inflow passage 33 and the internal space of the object to be shaped e and through the outflow passage 34 into the discharging space. Shaping and cooling are simultaneously performed by blowing the compressed air adjusted to have an air pressure at which the object to be shaped e being in the form of a preform is inflated to be shaped into the hollow molded body throughout the entire process of the blowing operation.

The injection-blow-moulding mould comprises: a punch (1) having a blow opening (3) connected to a first conduit (5) which is in communication with a first source of pressurised gas supply (6) configured to supply pressurised gas through the blow opening (3) at an overpressure (OP) above a blowing pressure (BP) suitable to blow a preform (30a) into a container (30b) and an exhaust opening (4) connected to a second conduit (7) which is in communication with a pressure-limiting device set at the blowing pressure (BP); a blow-moulding cavity (2) configured to receive therein the punch (1) with a hot and soft preform (30a) arranged thereon; and a cooling device associated to the blow-moulding cavity (2). Gas inside the container (30b) exceeding the blowing pressure (BP) is allowed to escape through the exhaust opening (4) thereby a cooling gas stream is created from the blow opening (3) to the exhaust opening.

The injection-blow-moulding mould comprises: a punch (1) having a blow opening (3) connected to a first conduit (5) which is in communication with a first source of pressurised gas supply (6) configured to supply pressurised gas through the blow opening (3) at an overpressure (OP) above a blowing pressure (BP) suitable to blow a preform (30a) into a container (30b) and an exhaust opening (4) connected to a second conduit (7) which is in communication with a pressure-limiting device set at the blowing pressure (BP); a blow-moulding cavity (2) configured to receive therein the punch (1) with a hot and soft preform (30a) arranged thereon; and a cooling device associated to the blow-moulding cavity (2). Gas inside the container (30b) exceeding the blowing pressure (BP) is allowed to escape through the exhaust opening (4) thereby a cooling gas stream is created from the blow opening (3) to the exhaust opening.