Extrusion blow-molding process in hollow blow molding
Stretching-blow molding is a method in which a bottomed parison heated to a suitable temperature and below the melting point is placed in a mold, stretched first with a stretching rod, and then blow-molded, which includes extrusion-stretching. A blow molding (referred to as "pulling and blowing") and injection-stretching blow molding (referred to as "Note-pulling and blowing"). This chapter only elaborates on how to squeeze.
Stretch blow molding can be divided into one step and two steps. In the one-step process, parisons are formed, cooled (not blown and blown), heated (not blown and blown), drawn, blown, cooled, and removed from the product in a single molding machine. The two-step method first uses an extrusion or injection method to shape a parison and cool it to room temperature to make it a semi-finished product. The parison is then sent to a molding machine for reheating, stretching, and blow molding into a product.
One-step and two-step stretch blow molding each have their own characteristics.
The main advantages of the one-step method are as follows: 1 The cost of the equipment is lower; 2 The thermal history of the parison is shorter; 3 The energy consumption is lower; 4 The product has fewer surface defects; 5 It can be used for small batch production.
The main advantages of the two-step method are: 1 can optimize the parison molding and stretch blow molding; 2 equipment operation and maintenance easier; 3 high output; 4 product cost is lower; 5 suitable for mass production.
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