| 摘要 |
PURPOSE:To prevent the generation of sinks completely, or to decrease sinks extremely even when the sinks are generated by protruding a reinforcing rib to one inner surface of a hollow molded form while fast sticking the front end section of the reinforcing rib to the other inner surface of an opposed hollow molded form. CONSTITUTION:In an odd-shaped extruded hollow molded form composed of a synthetic resin, the front end section of a reinforcing rib 12 protruded from the inner surface of a hollow form 11 is fast stuck 13 to another opposed inner surface of the form. A cross section is formed in uniform thickness on the side, to which the reinforcing rib 12 is fast stuck, of an top face hollow form, thus generating no sink resulting from the shrinkage of the unequal section of the cross section. On the other hand, the generation of sinks is recognized slightly on the protruding side of the reinforcing rib 12, i.e, the surface of the hollow form of an underside, but the generation of the sinks are made considerably smaller than conventional products. An extrudable thermoplastic resin such as polyvinyl chloride, polystyrene, a polystyrene resin, etc. is used as the synthetic resin. A foamable synthetic resin containing a foaming agent such as polystyrene, polyvinyl chloride, polyethylene, etc. is also suitable. |
