Extrusion molding process is the polymer processing field in the production of the most varieties, the most variation, high productivity, adaptability, wide range of uses, the proportion of the production of the molding process method. Extrusion molding is to make the polymer melt (or viscous fluid) in the extruder screw under the action of extrusion through a certain shape of the mouth die molding, the product is a continuous profile with a constant section shape.