Method for injection molding a large thickness flange at end of blow molding tube

摘要

A method for forming a large thickness flange at an end of a blow molding tube by injection molding using a die assembly. The blow molding tube is sufficiently cooled down before insertion into injection molding dies. The sizes and dimensions of tube holding portions of the injection molding die assembly, which hold the blow molding tube at a portion adjacent to the end, and those of a mating injection molding mandrel are set in conformity to its size and dimension of the blow molding tube after thermal shrinkage thereof caused by cooling of the tube. Thus, any gap between the blow molding tube and injection molding die assembly is eliminated, so that any leakage of molten resin through such a gap between the contact surfaces of the blow molding tube and those of the injection molding dies and mandrel can be perfectly prevented during the injection molding step. For instance, the method is useful for producing an intake manifold used in an automotive engine room.