Plastic hollow body producing method, involves detecting variations of wall thickness distribution of hollow bodies, and correcting variations by intervening molding process or by changing outflow speed of plastic melt from die gap

摘要

The method involves widening a tubular preform (2) with a gaseous medium to hollow bodies (8), and controlling formation of the preform. Net weight of the bodies and a control variable are measured, where the variable indirectly describes an axial position of a selected region of a wall profile of the preform before closing of a blow mold (4). Variations of wall thickness distribution of the bodies are detected, and are corrected by intervening a molding process or by changing outflow speed of a plastic melt from a die gap, where the speed causes embossment of the preform.