Patent attributes
A molding die includes an upper die, upper-die pins arranged in the upper die to be movable up and down, springs arranged in the upper die to urge the upper-die pins downwardly, a lower die, lower-die pins arranged in the lower die to be movable up and down and springs arranged in the die to urge the pins upwardly. In molding, a hollow primary molded piece is accommodated in a cavity defined by the upper die and the lower die. Then, the piece is mounted on the pins with retained apart from a concave bottom surface of the lower die. Before closing the molding die, it is started to inject molten resin into the cavity. As a result, the molten resin enters a space between the primary molded piece and the concave bottom surface of the lower die. Even after completing to close the molding die, the injection of the molten resin is continued.
