Abstract: To further improve hollow resin molded article manufacturing technology, a hollow resin molded article manufacturing method includes: injecting a melted resin material into a cavity of a mold; injecting gas and liquid into the cavity in which the resin material has been injected, via an injector connected to the cavity, to form a hollow portion in the resin material in the cavity; and discharging the liquid in the cavity to outside of the cavity. The hollow portion forming step includes injecting the gas in a compressed state into the injector and then injecting the liquid pressurized at higher pressure than the gas. The injector is connected to a vertically lowermost end of the cavity. In the discharging step, the liquid is discharged via the injector.

Abstract: In a multicolored resin molding apparatus, a primary molding is molded while a cavity core having a die surface is held by and between dies provided in a primary molding station, and a secondary molding is molded while the cavity core having the primary molding is held by and between dies provided in a secondary molding station. Further, the cavity core having the primary and secondary moldings is delivered to a die removing station, where a molded product is removed from the dies. Since the cavity core is delivered to the respective stations, there is eliminated the need for use of a large-sized and complicated molding machine and, instead of this, a simple general-purpose molding machine can be used.