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The working principle of blow molding machine

Sep,20,2022

Blow molding machine, also known as hollow blow molding, is a rapidly developing plastic processing method. The blow molding machine is a machine that uses the wind blowing from the machine to blow the plastic body to a certain shape of the cavity after spraying the liquid plastic to make the product.

Blow molding machines can be divided into three categories: extrusion blow molding machines, injection blow molding machines and special structure blow molding machines.

Blow molding machine is mainly composed of extruder, machine head, hydraulic system, mold clamping system, electrical control system, inflation system, automatic clamping and other parts. It is used for blowing PE and other hollow products of various materials. Such as: barrels, drums, beer preservation containers, tool boxes, lampshades, etc. The machine has high performance, low energy consumption and easy operation.

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At present, the high-end hollow machine on the market is a newer product developed and developed in combination with my country's national conditions. It selects high-quality hydraulic components, adopts PLC control, and adopts the most advanced FIFO type storage head. On the basis of the advantages of traditional hollow aircraft, coupled with today's most advanced technology, its performance is more excellent and reliable. High efficiency and applicability have reached the level of similar products in Japan and Germany. It can be said that products at this level will become more and more advanced. Because of the market demand, the quality requirements are also relatively high. And it will continue to be renovated, and new tricks will continue to come out.

The tubular plastic parison obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while it is hot (or heated to a softened state), and compressed air is introduced into the parison immediately after closing the mold to blow the plastic parison. It expands and sticks closely to the inner wall of the mold, and after cooling and demoulding, various hollow products are obtained. The manufacturing process of blown film is very similar in principle to blow molding of hollow products, but it does not use a mold. From the perspective of plastic processing technology classification, the molding process of blown film is usually included in extrusion.

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 blow molding machine can plasticize the preformed products by heating, and then enter the mold for blow molding. This method is mainly used for the production of high-speed and high-volume PET bottles and BOPP bottles, that is, a two-step process; blow molding can also be combined with The injection molding process is combined into an injection-stretch-blow integrated machine, which is also a common method for producing containers in PET; the plastic is melted and quantitatively extruded in a screw extruder, and then formed through the oral film, and then cooled by an air ring, and then a The tractor pulls at a certain speed, and the winder winds it into rolls.

After the liquid plastic is sprayed out, the wind blowing from the machine is used to blow the plastic body to a certain shape of the mold cavity to make a product. This machine is called a blow molding machine. The plastic parison is placed in the split mold while it is hot, and compressed air is introduced into the parison immediately after the mold is closed, so that the plastic parison is inflated and adhered to the inner wall of the mold. After cooling and demoulding, various hollow products are obtained. . The manufacturing process of blown film is very similar in principle to blow molding of hollow products, but it does not use a mold. From the perspective of plastic processing technology classification, the molding process of blown film is usually included in extrusion.

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