摘要
介绍了生产硬PVC低发泡挤出制品的三种成型工艺──自由发泡工艺、向内发泡工艺和受限自由发泡挤出成型工艺。结合不同工艺原理，分析指出了机头口模的结构特点和设计要点。
Introduces three Kinds of forming process for extrudering gard PVC product with low forming extrusion-free fotring process, inward forming process and limited free forming extrusion forming process. With different process principle, given the structure property and key design point of die mold of the head.
