Analysis of Factors Affecting Preform Molding

2019-11-19

At present, the application scale of preform molds is relatively extensive, which has the characteristics of high quality, energy saving, high efficiency, and long service life, which are favored by more and more manufacturers. So what are the factors that affect preform mold forming? Let's take a look together.

First, the polymer is transported, melted, mixed in the extruder, pumped out into the formation stage of the parison; at this stage, the factors affecting the wall thickness distribution are: 1. The molecular weight distribution of the material and the average molecular weight; 2. The temperature control system and screw speed of the blow molding machine. The temperature control system includes the temperature of the hopper, the temperature of the zone 1, 2, 3, and 4 of the cylinder, the temperature of the flange, and the zone 1 and 2 of the storage die. , Zone 3, zone 4 temperature.

2. The stage where the parison is squeezed from the gap between the die lip and the die core is called the blanking stage. At this moment, common phenomena are the swelling of the embryo and the vertical extension of the embryo. The factors affecting these two phenomena are: the die diameter and wall thickness control system of the blow molding machine, where the control system includes the axial wall thickness control system and the circumferential wall thickness control system, which are used to adjust the gap between the die lip and the core of.

3. Pre-blowing stage of preform In order to prevent the inner surface of the preform from touching and adhering, and to improve the uniformity of the wall thickness of the product, pre-blowing of the preform is required. During the pre-blowing stage of the embryo, air is sprayed from below the embryo to the embryo to protect the embryo and reduce its vertical extension. At this stage, the factors affecting wall thickness distribution are: pre-blowing pressure and pre-blowing time.

4. In the stage of high-pressure blow of the parison, the parison is inflated under high pressure to make it close to the mold cavity to complete the plastic molding of the product. At this stage, the common phenomenon is that the embryo is deformed by high pressure inflation, and the embryo and the cavity are deformed by touching. The factors that affect such conditions are: the shortening rate of the material; the pressure and time of blowing; the material and structure of the mold; the mold exhaust system and the mold cooling system, such as cooling water channel distribution, cooling water inlet temperature, etc.

Although there are many factors that affect the quality of blow molded products, after the production conditions and product requirements are confirmed, adjusting the blow molding process factors can effectively improve the quality of the products. After all, the optimized process elements can improve production efficiency, reduce raw material consumption, and optimize the comprehensive functions of the product.

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