Method of manufacturing resin hollow body using a blow molding die assembly

A method of manufacturing a resin hollow body using a blow molding die assembly which comprises:

• a pair of main dies (2), (4) formed with a dividable cavity therein by closing the open end surfaces (2a), (4a) thereof with each other;
• and
• a pair of slide dies (12a), (12b) being disposed outside of the pair of main dies (2), (4) and having abutting portions (12c), (12d) that move between first positions where the abutting portions (12c), (12d) project outward from the open end surfaces (2a), (4a) of the main dies (2), (4) and second positions where the abutting portions are located inward of the open end surfaces (2a), (4a), the method comprising:
• a step of obtaining a hollow molded body by blow molding a thermoplastic resin parison in the cavity in the dividable dies in a state in which the abutting portions (12c), (12d) are located at the first positions where the abutting portions (12c), (12d) project outward from the open end surfaces (2a), (4a), wherein the parison is not cut off to two or more pieces before it is blow molded;
• a step of dividing the hollow molded body by opening the dividable dies after the parison is blow molded in the cavity in the dividable dies;
• a step of attaching at least one part on an inner surface of the divided hollow molded bodies and/or modifying the inner surfaces of the divided hollow molded bodies in a state in which the abutting portions (12c), (12d) are located at either of the first positions and the second positions;
• and
• a step of obtaining an integrated hollow body by welding the divided hollow bodies with the dies closed in a state in which the abutting portions (12c), (12d) are located at the second positions where the abutting portions (120c), (12d) are located inner than the open end surfaces (2a), (4a).

A method of manufacturing a resin hollow body using a blow molding die assembly which comprises:

• a pair of main dies (2), (4) formed with a dividable cavity therein by closing the open end surfaces (2a), (4a) thereof with each other;
• and
• a pair of slide dies (12a), (12b) being disposed outside of the pair of main dies (2), (4) and having abutting portions (12c), (12d) that between first positions where the abutting portions (12c), (12d) project outward from the open end surfaces (2a), (4a) of the main dies (2), (4) and second positions where the abutting portions are located inward of the open end surfaces (2a), (4g), the method comprising:
• a parison clamping step (10) for clamping a thermoplastic resin parison (6), extruded to a tubular state, in the cavity of the pair of main dies (2), (4) and clamping the parison (6) by the abutting portions (12c), (12d) of the slide dies (12a), (12b) by disposing the slide dies (12a), (12b) at the first positions where they project from open end surfaces (2a), (4a) of the main dies (2), (4);
• an inside die suctioning step (15) for sucking the space between the outer surface of the parison (6) and inner surfaces of the main dies (2), (4) by suction means from the outside, wherein parison (6) is clamped by the abutting portions (12c), (12d) of the pair of slide dies (12a), (12b) at the parison clamping step (10);
• a parison expanding step (20) for expanding the parison (6) by introducing a gas into the inside of the parison (6) either before the inside die suctioning step (15) is carried out, after the inside die suctioning step (15) is carried out, or at the time when the inside die suctioning step (15) is carried out;
• a primary die opening step (30) for opening the pair of main dies (2), (4) along with half-divided hollow molded bodies (6a), (6b) after the outer surface of the parison (6) is expanded at the parison expanding step (20) and is caused to come into intimate contact with inner peripheral surfaces of the main dies (2), (4);
• a parts assembly step (40) for attaching predetermined parts (32), (34) and the like, which are previously formed as separate members, on the inner surfaces of the parison (6) in the pair of main dies (2), (4) separated from each other at the primary die opening step (30),
• a secondary die closing step (50) for closing the pair of main dies (2), (4) again after the predetermined parts (32), (34) and the like are assembled to the inner surface of the hollow molded body (6) in the main dies (2), (4) at the parts assembly step (40);
• a re-fuse bonding step (60) for joining the abutting portions of the half-divided hollow molded bodies (6a), (6b) closed at the secondary die closing step (50);
• and
• a secondary die opening step (70) for taking out a product of a hollow molded body integrated at the re-fuse bonding step (60) from the main dies (2), (4),
• wherein the steps of the parison clamping step (10), the an inside die suctioning step (15), the parison expanding step (20) and the primary die opening step (30) are carried out in a state in which the abutting portions (12c), (12d) of the slide dies are located at first positions where they project outward from the open end surfaces (2a), (4a) of the main dies (2), (4);
• and
• the steps of the secondary die closing step (50) and the re-fuse bonding step (60) are carried out in a state in which the abutting portions (12c), (12d) of the slide dies are located at second positions where they are located inward of the open end surface (2a), (4a) of the main dies (2), (4).