| 摘要 |
PROBLEM TO BE SOLVED: To efficiently and easily obtain a good internally foamed molded product having a dense surface layer and a highly foamed inner layer. SOLUTION: A foamable molten molding compound is injected in a mold cavity 2 with which a lightening cavity 3 communicates through an on-off valve 4 to fill the cavity 2, and pressurized gas, of which the pressure can suppress the foaming of the molten molding compound, is injected in the molten molding compound in the mold cavity 2 to form a hollow part 8. Thereafter, the on-off valve 4 is opened to burst the molten molding compound in the periphery of the hollow part 8, and the pressurized gas in the hollow part 8 is discharged to foam the molten molding compound in the hollow part 8 from which the pressurized gas is discharged. |
