Author: MULAN -Plastic Molding Manufacturer
Stretch blow molding is to make a parison by extrusion, injection, etc., and then heat the parison to the stretching degree, and then stretch it longitudinally by internal (such as a mandrel) or external (such as a clamp) mechanical force. , at the same time or later by compressed air inflation for transverse stretching. Therefore, stretch blow molding is essentially biaxial stretch blow molding, also known as biaxial orientation blow molding. Blow Mold Manufacturer According to the method of parison manufacturing, stretch blow molding is divided into injection stretch blow molding and extrusion stretch blow molding. According to the heating experience of the parison, it can be divided into one-step method (hot parison method) and two-step method (cold parison method). Injection stretch blowing is mainly used for the molding of polyester bottles, blow mold manufacturers One-step injection stretch blowing and two-step injection stretch blowing are adopted. One-step injection stretch blowing, the parison is hot, it completes the three processes of pre-turning parison, stretching and blow molding in one equipment. The equipment used is composed of injection device, injection mold, temperature adjustment device, blow mold and mold clamping device. When molding the parison, the injection machine injects the molten plastic into the pre-side parison mold, and the mold is in a vertical position. After cooling, the core of the mold goes up, and the cavity part moves down, and then the parison is rotated to the heating and adjusting station by the turntable. After reaching the required temperature, it is transferred to the stretching and blowing station for stretching, blowing and Cool to set. Finally, turn to the ejection station to eject the bottle. One-step bottle making has the advantages of low investment and good product appearance, but its disadvantages are low efficiency, difficult optimization of preform design, high requirements for operation control, and difficult control of product quality. Two-step injection stretch blow molding is performed separately from prefabricated parison and stretch blow molding. The D step is to make parison by injection method. The second step is to preheat the preform in an oven, clamp it with a clamp, and rotate it at a certain speed. When the temperature of the inner and outer layers of the preform has reached equilibrium, it leaves the oven and puts it on a bracket, and is transported to the stretching station for forming. The injection conditions of the two-step method are similar to those of the one-step method, except that the preform used in the two-step method needs to be cooled below the glass transition temperature to make it in an amorphous state. Blow Mold Manufacturer The early two-step method used 8-cavity hot-runner injection molds to inject prefabricated parisons, but now it can be molded with 48-cavity hot-runner injection molds, which greatly improves production efficiency. The two-step method of producing polyester bottles has low cost and good quality (isolation and strength). It can also concentrate on the production of preforms and disperse processing of bottles. Its disadvantage is large investment and high energy consumption. Proficient in mold | Blow mold manufacturer | Started in 1998, trustworthy.