Heating thermoplastic parison interior - by locking parison in vertical position, blowing hot air through central tube positioned inside it, and venting air round this tube

摘要

A thermoplastic parison is heated by at least one part of its outer surface; at least one part of its inside face is also heated, using a hot gas for the purpose. A prefd. parison is made of polyethyleneterephthalate. More specifically, a parison is placed on a tool and subjected to external heating together with internal heating by hot gas which flows through a heater to a centre tube and its open end in the parison. The parison rests on the base of the tool whose top is conveniently tapered. A flange is gripped by an outer tool. The cooled hot air is vented out through the space. If desired the incoming air is also dried. The system can be fitted with automatic controls e.g. to raise the temp. of the air; the air flow can be modified to suit the shape of the parison. The equipment can e.g. move the parison during heating.