Molding method and molding apparatus for resin molded article

A molding apparatus for a thermoplastic resin, comprising:

• a primary molding unit that forms the thermoplastic resin by an extrusion molding, the primary molding unit extruding the thermoplastic resin to which a primary molding is performed in a drooping form;
• and
• a secondary molding unit that performs a secondary molding by a blow molding or a vacuum molding to the thermoplastic resin extruded by the primary molding unit, wherein
• the primary molding unit includes:
• a melting and mixing unit that melts and mixes the thermoplastic resin,
• an accumulating unit that accumulates the melted and mixed thermoplastic resin in a predetermined amount, and
• an extrusion slit that intermittently extrudes the accumulated thermoplastic resin so as to droop in a sheet shape in the molten state,
• the secondary molding unit includes:
• a pair of split mold blocks movable in a direction approximately perpendicular to a sheet surface between an opening position and a closed position with sandwiching the drooping sheet-shaped resin, the pair of split mold blocks including cavities formed on surfaces opposing to one another, and
• a mold moving unit that moves the pair of split mold blocks in the direction approximately perpendicular to the sheet surface between the opening position and the closed position, wherein
• the molding apparatus further includes:
• a pair of rollers positioned at a predetermined position below the extrusion slit and above the pair of split mold blocks, the pair of rollers including respective rotation axes disposed in parallel with one another and approximately horizontally, one being a rotationally driving roller, another being a driven roller,
• a roller rotationally driving unit that rotationally drives the rotationally driving roller,
• a roller moving unit that moves any one of the rollers among the pair of rollers with respect to the corresponding roller or moves both the rollers within a planar surface encompassing the pair of rollers, and
• a relative speed difference adjustment unit that adjusts a relative speed difference between an extrusion speed of the extruded sheet made of the thermoplastic resin in the molten state and a downward sending out speed by the pair of rollers of the sheet made of the thermoplastic resin sandwiched between the pair of rollers, wherein
• the molding apparatus further includes:
• a sheet-shaped resin drawing unit that includes:
• a clamp portion that is configured to clamp a lowest portion of the sheet-shaped resin sent out downward by the pair of rollers,
• a clamp portion moving unit that moves the clamp portion in a vertical direction, and
• a clamp portion moving speed adjustment unit that adjusts a moving speed of the clamp portion in the vertical direction by the clamp portion moving unit corresponding to the sending out speed of the sheet-shaped thermoplastic resin by the pair of rollers in a state where the lowest portion of the sheet-shaped thermoplastic resin is clamped by the clamp portion, wherein the clamp portion moving unit is configured to move the clamp portion between a clamp start position where clamping of the lowest portion of the sheet-shaped thermoplastic resin is started by the clamp portion and a clamp release position below the clamp start position and where clamping of the lowest portion of the sheet-shaped thermoplastic resin is released by the clamp portion, and the clamp release position is at a level lower than the pair of split mold blocks.