| 摘要 |
PURPOSE:To prevent generation of a hesitation mark by injecting synthetic resin until the whole cavity is filled therewith and then introducing gas into the synthetic resin and making one part of the synthetic resin unnecessary for molding of a hollow molding flow out into a tub. CONSTITUTION:Molten synthetic resin 90 is injected into a cavity 80 and all parts of the inside of the cavity 80 are filled with the synthetic resin 90. At this time, a small amount of synthetic resin 90 is allowed to flow through a small flow path 10 to the lower part of a tub 1. The cavity is filled with the synthetic resin and thereafter immediately when gas 7 is introduced by a sprue bush 85, the introduced gas 7 is introduced into the molten synthetic resin 90 in the cavity. While pressing the synthetic resin 90 in the direction of the inner wall and the front part of the cavity 80, the gas is progressed forth. The synthetic resin 90 pushed by the gas 7 flows out into the tub 1 through the small flow path 10. Thereby a hollow part 95 is formed in the synthetic resin 90. A hesitation mark is not generated by synthetic resin in the cavity 80. |
