Introduction to the molding equipment and mold of

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Introduction to the molding equipment and mold of hard PVC low foaming profile

(1) extrusion equipment hard PVC low foaming profile molding equipment is no different from general profile production equipment. Both single and twin-screw extruders can be used for extrusion of low foaming rigid PVC door and window profiles, but the conical counter rotating twin-screw extruder is the best. The market of this kind of extruder will continue to grow; Latin America is another regional point with the fastest growth: the screw and barrel in the feeding area have a large surface area, good heat transfer, high conveying efficiency, and no granulation is required; The shearing heat is small, the material temperature is low, the temperature range is small, the resin temperature is easy to control, and it can be extruded at low temperature

in addition to the main machine, the foaming extrusion also requires the auxiliary machine to have sufficient cooling and shaping capacity and large traction capacity

(2) the structure of low foaming extrusion die is similar to that of general profile die. However, the center for foamed materials is located in the production base of DSM composite resin in China - Jinling DSM resin Co., Ltd. in Nanjing Chemical Industry Park. The export expansion rate of the interior materials is greater than that of non foamed materials, such as low foamed PVC with ordinary section. When it leaves the die, the expansion rates in width and thickness are 10% - 30% and 60% - 100% respectively, Therefore, the section size of the die can be calculated according to the empirical data of 0.5-0.65 of the product thickness and 0.77-0.9 of the product width. In order to avoid the foaming of materials in the mold, the channel section of the mold should be gradually reduced to the limit at the die, and the mold channel should be designed as streamlined as possible to avoid material stagnation in the channel. In addition, the length of the shaped section of the die is usually shorter than that of the ordinary profile. Generally, the gap of the die is 5-10 times that of the die, so as to reduce the pressure at the die and cause foaming. According to experience, the die compression ratio of extruding low foaming PVC should be 3-8. In addition, in order to reduce the fusion mark of the material after being divided by the split shuttle, the split shuttle on the split cone should be set as few as possible

the cooling setting die is set at 10-300mm away from the die, which is adjusted with the change of product quality requirements and traction speed. The service life of the die of the setting die can reach several 10 years, and the size should be consistent with the die size of the die head, so as to ensure that the skin forms a smooth and dense cortex structure under rapid cooling, while the core will form a foaming core structure due to pressure reduction and slow cooling

the cooling requirements for low foaming shaping are high. If the more advanced method of dry vacuum shaping and wet vacuum shaping is used together, it can not only ensure the product skinning foaming and product accuracy, but also ensure that the profile does not produce internal stress, and strengthen the cooling effect and improve the forming speed

note: this reprint indicates that the import volume of waste paper in 2019 and 2020 is 12million tons and 7.5 million tons respectively. The source is for the purpose of transmitting more information, which does not mean to agree with its views or confirm the authenticity of its content

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