HOLLOW INJECTION MOLDING METHOD AND GAS SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To mold a molded article having no sink or gloss irregularity and excellent in appearance without increasing gas pressure when the molded article having a hollow part is to be molded by a blow injection molding method. SOLUTION: In a blow injection molding method for injecting gas in the molten resin injected in the cavity 5 of a mold, gas is injected under such a condition that the gas flow velocity on the downstream side of a gas injection valve 16 becomes faster than that on the upstream side of the gas injection valve 16. A gas generator 12, a gas injection control device 15 and a gas supply passage comprising the gas pipes connecting both of them to the mold 2 are provided, and the cross-sectional area of the gas flow passage 22 from the gas injection valve of the gas injection control device to the mold is set to 77% or less of that of the gas flow passage from the gas generator to the gas injection valve.