Hollow blow molding application
Hollow blow molding mainly suitable for processing and packaging containers for the molding hollow products. The raw materials are: high pressure polyethylene (HDPE), polyethylene (LDPE), hard polyvinyl chloride (HPVC) and ethylene. Soft polyvinyl chloride (SPVC), plastics, cellulose, polystyrene (Ps) poly propylene (PP), polycarbonate (Pc) etc.. At present, the most commonly used blow molding products are polyethylene (PE) and polyvinyl chloride (PVC) as the main raw material. Because polyethylene products are non-toxic, easy to process, low cost, transparency and good printing performance. Is the hollow molding molten plastic parison, the mold is closed into mould to pass into the compressed air (pressure of 2.7 ~ 5Kg / cm2), the parison blowing into the shape of the cavity in the mold products packing conditions, cooling and shaping mold removal. According to the different molding methods, can be divided into the following five forms. (1) extrusion blow molding is the main method in our country at present. Melt type billet is extruded by extruder. The utility model has the advantages of simple equipment and simple mould, and the disadvantage is that the wall thickness of the slab is not easy to be uniform, thereby causing the difference of the wall thickness of the plastic parts. (2) injection blow molding by injection molding blank, then heat the parison into hollow blow mould for blow molding. The utility model has the advantages of uniform wall thickness and no fly edge, and no need of post processing. The blank bottom, so the bottom parts are no splicing seams, the production efficiency is also high strength. But the equipment and mold price is more expensive. Used for small and high precision parts and mass production. (3) the method of stretch blow molding is based on the injection blow molding, which increases the process of the extension of the slab. The principle of this method is the same as that of the biaxial drawing die. The molecular biaxial orientation and the plastic part can be improved, and the strength is increased.
