PLASTIC MOLDING METHOD

摘要

A method of forming a plastic material by using a mold 30 that has a split-mold structure forming air vent 39 in the split surfaces which are the butt surfaces of split molds, the air vent 39 being communicated with gas passages 37, wherein a resin is fed into the mold 30 so as to be formed, and after the formed article is taken out from the mold but before the rein is fed into the mold 30 so as to be formed in the next cycle, a cleaning gas G is fed through the gas passages 37 into the air vent 39 in a state where there is formed at least part of the mold 30 inclusive of the air vent 39, the cleaning gas G being discharged through passages separate from the gas passages 37. The method is capable of effectively preventing the oligomers from building up in the vent groove and, therefore, automatically executing the cleaning without the need of halting the forming cycle.