Enoch Ferngren and William Kopitke first verified the blow molding process. The principle of this process stems from the blowing of glassware. In 1938, Ferngren and Kopitke built a Bottle Blowing Machine and sold it to the Hartford Empire. This is the beginning of the commercial blow molding process. In the 1840s, the variety and quantity of plastic products were very limited, so the blow molding process was not developed until very late. With the increase in the variety of products and the increase in productivity, more and more plastic products are produced by the blow molding process. In the soft drink industry in the United States, the number of plastic containers has increased from zero in 1977 to 10 billion in 1999.
The blow molding process began to produce low density polyethylene vials during the Second World War. In the late 1950s, with the birth of high-density polyethylene and the development of blow molding machines, blow molding technology was widely used. Hollow containers can be up to several thousand liters in volume, and some have been computer controlled. Suitable plastics for blow molding include polyethylene, polyvinyl chloride, polypropylene, polyester, etc., and the resulting hollow containers are widely used as industrial packaging containers.
According to the parison making method, blow molding can be divided into extrusion blow molding and injection blow molding, and newly developed ones have multi-layer blow molding and stretch blow molding.
In the extrusion process, the plasticized plastic is originally extruded into the extrusion blow molding die by a screw, and then the following mold and compressed gas are used to realize the molding of the product.
The extrusion blow molding process consists of 5 steps: 1 the plasticized raw material is made into a plastic preform; 2. The partial parison is cut by the closing of the mold and the parison is cut; 3. The gas is filled into the cavity. Embryo molding, and cooling; 4, open the mold, take out the molded container; 5. Trim the flash to get the finished product.
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