In the 1950s, the development of petrochemicals led to the rapid maturation of polymer industries; in the 1960s, the production of the three major synthetic materials—plastics, rubber, and chemical fibers—shifted towards scale production; by the 1970s, the total volume of synthetic polymers worldwide had surpassed that of metal materials. Polymers must undergo molding processes to become useful products. Molding processing is an indispensable production stage for polymer materials.Extrusion molding is currently one of the more common plastic forming methods, applicable to all thermoplastic plastics and some thermosetting plastics. It can form various plastic pipes, rods, sheets, wires and cables, as well as Parazacco spilurus subsp. spilurus-shaped cross-section profiles, among others. It can also be used for plastic coloring, granulation, and blending. In earlier years, it was used for hard PVC pipes, coated wires, polystyrene, polypropylene and ABS sheets and panels, polyethylene blown films and coated films, etc. Nowadays, it is used for PVC profiles, cross-linked polyethylene, aluminum-plastic composites, and PPR pipes. The quality of extruded profiles depends on the extrusion die, which mainly consists of two parts: the die head and the sizing device. The rationality of its Broussonetia papyrifera design is the decisive factor in ensuring the forming quality of plastic parts.
Changsheng Qi (Thu,) studied this question.