March 21, 2022
The history of the blow molding machine
Enoch Ferngren and William Kopitke were the first to demonstrate the blow molding process. The principle of this process originates from the blowing of glass supplies. In 1938, Ferngren and Kopitke built a blow molding machine and sold it to the Hartford Imperial Company. 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 did not develop rapidly until much later. With the increase in product types and productivity, more and more plastic products are soon produced by blow molding. In the US soft drink industry, the number of plastic containers has grown from zero in 1977 to 10 billion in 1999.
The blow molding process began to be used to produce low density polyethylene vials during World War II. In the late 1950s, with the birth of high-density polyethylene and the development of blow molding machines, blow molding technology was widely used. The volume of hollow containers can reach thousands of liters, and some production has adopted computer control. Plastics suitable for blow molding include polyethylene, polyvinyl chloride, polypropylene, polyester, etc., and the obtained hollow containers are widely used as industrial packaging containers.
According to the method of making the parison, blow molding can be divided into extrusion blow molding and injection blow molding. The newly developed ones include multi-layer blow molding and stretch blow molding.
The extrusion process is to extrude the plasticized plastic into the extrusion blowing die head through a screw, and then cooperate with the lower mold and compressed gas to realize the molding of the product.
The extrusion blow molding process consists of 5 steps:
1. The plasticized raw material is made into plastic parison;
2. Cut off part of the parison by closing the mold and cut off the parison;
3. Fill the mold cavity with gas to form the parison and cool it down;
4. Open the mold and take out the molded container;
5. Trim the flash to get the finished product.
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