Factors affecting the formation of preform molds

The stage of polymer transportation, melting, mixing, and pumping out in the extruder to form the embryo; At this stage, the factors that affect the wall thickness distribution include: 1. the molecular weight distribution and average molecular weight of the material; 2. The temperature control system and screw speed of the blow molding machine include the temperature of the hopper, the temperature of the material cylinder in zones 1, 2, 3, and 4, the flange temperature, and the temperature of the storage mold head in zones 1, 2, 3, and 4.

The stage where the embryo is extruded from the gap between the mold lip and the mold core is called the cutting stage. At this point, common phenomena include embryo dilation and embryo elongation. The factors that affect these two phenomena include the die diameter and wall thickness control system of the blow molding machine. The control system includes an axial wall thickness control system and a circumferential wall thickness control system, which are used to adjust the gap between the die lip and the die core.

In the pre blowing stage of the embryo, in order to avoid contact and adhesion on the inner surface of the embryo, and to improve the uniformity of the product wall thickness, the embryo needs to be pre inflated. During the pre blowing stage of the embryo, air is sprayed from below into the embryo to protect it and reduce its elongation. At this stage, the factors that affect the distribution of wall thickness include pre blowing pressure and pre blowing time.

In the high-pressure blowing stage of the embryo, the embryo is inflated with high pressure to tightly adhere to the mold cavity, achieving plastic forming of the product. At this stage, common phenomena include deformation of the embryo due to high-pressure inflation and deformation of the embryo in contact with the mold cavity. The factors that affect such situations include: the shrinkage rate of the material; The pressure and duration of blowing air; The material and structure of the mold; Mold exhaust system and mold cooling system, such as distribution of cooling water channels, inlet temperature of cooling water, etc.

Although there are many factors affecting the quality of blow molded products, when the production conditions and product requirements are determined, adjusting the blow molding process factors can effectively improve the quality of products. After all, optimized process factors can improve production efficiency, reduce raw material consumption, and optimize the overall performance of products.