Method for manufacturing hollow molded article and apparatus for molding hollow molded article

A method for manufacturing a hollow molded article, the method comprising:

• forming a fluid passage having a through-hole in a first thermoplastic resin sheet to be vacuum-molded by a first vacuum molding die;
• heating and softening the first thermoplastic resin sheet;
• heating and softening a second thermoplastic resin sheet to be vacuum-molded by a second vacuum molding die;
• holding both the sheets by the first and second vacuum molding dies, in a state where the first and second vacuum molding dies are clamped and the first and second thermoplastic resin sheets are superimposed;
• sealing a molding surface of the first vacuum molding die by the first the thermoplastic resin sheet;
• sealing a molding surface of the second vacuum molding die by the second thermoplastic resin sheet;
• joining the first and second thermoplastic resin sheets around the molding surfaces of the first and second vacuum molding dies;
• connecting an opening on the first vacuum molding die side among openings of the fluid passage to a fluid supply source;
• pressing a region of the first thermoplastic resin sheet, extending between the molding surface of the first vacuum molding die and the fluid passage of the first thermoplastic resin sheet, with the second thermoplastic resin sheet into a concave section provided in the second vacuum molding die by a convex section of the first vacuum molding die, the convex section having (a) a top surface, (b) a first side surface and (c) a second side surface, the first side surface and the second side surface being arranged separated from each other in a first direction and both extending in at least a second direction that intersects with the first direction, the top surface being arranged extending in the first direction between the first side surface and the second side surface;
• forming a seal section extending along the convex section of the first vacuum molding die between the first vacuum molding die and the first thermoplastic resin sheet, the seal section having (i) a first portion extending along the top surface of the convex section, (ii) a second portion extending along the first side surface of the convex section and (iii) a third portion extending along the second side surface of the convex section;
• performing vacuum-molding of the first thermoplastic resin sheet by the first vacuum molding die;
• forming a first shaping section in the first thermoplastic resin sheet by a molded section of the first vacuum molding die;
• performing vacuum-molding of the second thermoplastic resin sheet by the second vacuum molding die;
• forming a second shaping section in the second thermoplastic resin sheet by a molded section of the second vacuum molding die;
• defining a hollow section between the first thermoplastic resin sheet and the second thermoplastic resin sheet by the first shaping section and the second shaping section, by suctioning air from the fluid supply source into between the first thermoplastic resin sheet and the second thermoplastic resin sheet through the fluid passage, accompanying the process of molding of the first shaping section and the second shaping section;
• and opening the first and second vacuum molding dies to take out a molded article having the hollow section.