The entire process of extrusion blow molding generally includes the following five steps:
1 The polymer is melted by an extruder and the melt is formed into a tubular parison by a handpiece;
When the parison reaches a predetermined length, the blow mold is closed, the parison is clamped between the mold halves, and cut off and moved to another station;
3 Inject the compressed air into the parison, inflate the parison, and mold it closely to the mold cavity;
5 mold, remove the molded product.
According to different ways of discharging, extrusion blow molding can be divided into two categories: direct extrusion blow molding and extrusion storage, extrusion molding and blow molding. The advantages of direct extrusion blow molding are: simple equipment, low investment, easy operation, suitable for blow molding of various plastics. However, the product wall thickness uniformity is poor. The process of extruding a stock material and extruding a blow-molding process is characterized in that a large container can be produced with a small apparatus; the desired parison length can be obtained within a short period of time and the uniformity of wall thickness of the product can be ensured. The disadvantages are: the equipment is complex, the design and maintenance of the hydraulic system is difficult, and the investment is large.