In the 1840s, the variety and quantity of plastic products were very limited, so the blowing process did not develop rapidly until very late. With the increase in the variety of products and the increase in productivity, more and more plastic products such as blow molding machines have been made quickly.
The blow molding process began during the Second World War and was used to produce low-density polyethylene vials. In the late 1950s, with the birth of high-density polyethylene and the development of blow moulding machines, blowing molding technology has been widely used. The volume of the hollow container can reach several thousand liters, and some production has been controlled by computer. Suitable for blowing plastics are polyethylene, polyvinyl chloride, polypropylene, polyester, etc.. The resulting hollow containers are widely used as industrial packaging containers.
According to the type of billet production method, blow molding can be divided into extrusion blow molding machine and injection blow molding machine. The newly developed multi-layer blow molding and stretch blow molding.
Extrusion process is to plasticize the original plastic through the screw squeeze into the extruding die head, and then with the following mold and compressed gas to achieve product molding.
Extrusion blowing process consists of 5 steps:
1. The plasticized raw materials are made into plastic embryos;
2. Intercepting part of the embryo and cutting off the embryo by closing the mold;
3. Fill the cavity with gas to form the embryo and cool it;
4. open the mold, take out the formed container;
5. Finishing the flying edge to obtain a finished product.