Core stabilization by sequential injections

摘要

A method for controlling the dimensions of a hollow plastics product injection molded within the cooling cavity of a mold having a core section and a cavity section defining the cooling cavity therebetween and separated by a parting line comprising stabilizing the core section in the cooling cavity and comprising the steps of: 1. Injecting a first plastics material into the cooling cavity so that only a part of the cooling cavity is filled. 2. Cooling the injected first plastics material in the cooling cavity; 3. Injecting subsequent to injecting the first plastics material a second plastics material into the cooling cavity so that the cooled injected first plastics material in said part of the cooling cavity stabilizes the core section by impeding movement of the core section caused by injecting the second plastics material and whereby the injected second plastics material fills the cooling cavity and fuses with the cooled previously injected plastics material.