| 摘要 |
OF THE DISCLOSURE A cavity formed in a mold is preparatorily expanded to a volume sufficient for preventing the flow of resin flowing into said cavity from being divided and held at a temperature capable of maintaining the resin in a flowing state. Into this expanded cavity, thermoplastic resin heated and in a molten state is injected after the quantity required for obtaining a molded article or more is preparatorily measured. The cavity is reduced in volume before the total quantity of said measured thermoplastic resin is injected into the cavity. This cavity reduction operation is controlled so that no unfilled portion which will cause a flow mark remains in the cavity when the cavity is reduced to a volume equal to the sum of the volume of the molded article and a volume of molding shrinkage due to the cooling of the thermoplastic resin. At the time of this cavity reduction, injection pressure is reduced to a pressure which would not obstruct back flow of the thermoplastic resin likely to have been overcharged into the cavity as a result of cavity reduction and which permits the injection of the resin to any unfilled portion likely to exist in the cavity. |
