What is a hollow blow molding machine? What types are there? What are the characteristics of each?

(1) Hollow blow molding Hollow blow molding is an important method of thermoplastic molding. It is a plastic molding method that uses the pressure of gas to inflate the hot mold closed in the mold into a hollow product. Blow molding is mainly used to produce plastic hollow packaging containers and industrial hollow parts.

(2) Types of hollow blow molding

There are many types of hollow blow molding processes. According to the different molding processes of the parison, they can generally be divided into two categories: extrusion hollow blow molding and injection hollow blow molding; according to the different blow molding conditions, they can be divided into ordinary Blow molding, stretch blow molding and three-dimensional (3D) extrusion blow hollow plastic molding; according to the product structure, it can be divided into two categories: single-layer blow molding and multi-layer blow molding.

(3) Characteristics of various types of hollow blow molding

①Extrusion hollow blow molding Extrusion hollow blow molding is to melt and plasticize the thermoplastic, and extrude the parison through the extruder head, then place the parison in the blow mold, and introduce compressed air (or Other media), inflate the parison, and after cooling and setting, the product can be obtained. Extrusion hollow molding can be divided into continuous extrusion hollow molding and intermittent extrusion hollow molding according to its discharging method. The continuous extrusion hollow molding method means that the extruder directly and continuously extrudes the parison through the head, which is mainly used to produce hollow products with large output and small volume (no more than 8L capacity). The intermittent extrusion hollow molding method means that the extruder directly extrudes the parison intermittently or squeezes the melt into a storage tank. When the melt in the storage tank meets the needs, it is extruded through the die of the die. The parison, after blowing, cooling and shaping, can obtain a large-capacity hollow product.

②Injection hollow blow molding Injection hollow blow molding is a method of injecting molten material into the mold with an injection machine to prepare a parison, and then placing the parison into the blow mold while it is hot, and introducing air to inflate the parison. molding method. Injection blow molded products generally do not need to be trimmed, with less leftover material, good parison wall thickness uniformity, and good dimensional accuracy of products, especially bottle containers, with high bottle mouth accuracy and good surface finish. However, in small batch production, the product cost is high, and it is not suitable to form products with too complex shape and structure.

③Stretch blow molding Stretch blow molding is to heat the prefabricated parison to an appropriate temperature below the melting point, put it in a blow mold, use a stretch rod to stretch axially, and then blow horizontally to stretch it. stretched forming method. Stretch blow molding can be divided into extrusion-stretch-blow molding and injection-stretch-blow molding according to the different preparation methods of the parison. Extrusion-stretch-blow molding is to melt and plasticize the material through an extruder first, and then extrude the parison, then heat the parison to the stretching temperature, and then carry out axial stretch blow molding. Injection-stretch-blow molding is to mold the parison by injection method, then heat the parison to the stretching temperature, and then perform axial stretch blow molding. Stretch blow molded products have transparency, impact strength, surface hardness, rigidity, permeability resistance and solvent resistance.

Post time: Sep-19-2022