METHOD OF BLOW-MOLDING HOLLOW VESSEL AND BLOW AIR CYLINDER

摘要

The present invention relates to a method of blow-molding a hollow vessel, wherein when a nozzle (1) for blowing air is thrust into a parison extruded from an extruder to thereby blow the air thereinto, the air is blown at least downward into the parison, an opening (8) is formed in the parison in the vicinity of a blow nozzle thrust-in portion (7) or thereabove after the hollow vessel is shaped by the blown air, and the blown air is circulated in the hollow vessel and then discharged therefrom. The invention also relates to a blow air cylinder suitably used for said method and has a particular construction wherein there is provided the blow nozzle (1) having an opening capable of blowing air at least downwardly at a rate of 30 % or above of the whole flow quantity of the blown air. The invention makes it possible to shorten the cooling time of the molded item after blow-molding and produce molded items excellent in accuracy of dimensions effectively. IMAGE