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As an energy-saving material, PVC profile has inherent advantages. The poor thermal conductivity of the non-metallic material itself makes the thermal conductivity of the PVC profile low. It is easy to realize a low heat transfer coefficient when doing doors and windows, which makes PVC profile a more ideal energy-saving building material.
Then how does PVC profile produce? There are many procedures including batching, mixing, extrusion, cooling, shaping, traction cutting, inspection, packaging and other processes.
PVC profile is a kind of polymer plastic with polyvinyl chloride as its main raw material. After research and development department determining formula, it comes to the batching process. It has both automated and manual methods. The composition of the formula contains PVC, heat stabilizers, fillers, lubricants, processing aids, light stabilizers, pigments and any other more than ten kinds of materials, each material has specific ratio requirements and each can not be added randomly and casually.
In the mixing stage, a variety of raw materials are measured in proportion according to a certain order and then added to the mixer. Special attention should be paid to the order of adding materials, because this procedure will affect the quality of the mixture. At the same time, the mixing time, temperature and speed of the mixer will also make a difference to the quality of the admixture.
Ⅲ. The Extruding Production Line
After going through the extrusion line, the mixed material will be settled and finish its product molding. Extruder is the key production equipment in this production, the principle of the machine is to use external heat and screw shear force on the material to make PVC powder plasticized into a molten state, and then it can produce different types of profiles through different mold.
There are various types of extruders: single-screw extruders and twin-screw extruders; among the types of twin-screw extruders, there are conical twin-screw extruders and parallel twin-screw extruders. When conducting a production, rightful extruder should be chosen appropriately according to its own situation. Profile extruder is a common equipment in industry. The extruder is mainly composed of screw, motor, control system, frequency converter and so on. The processing precision of the extruder is the key to the technical index.
The fully plasticized and melted PVC material passes through the mold to form the desired shape, and then goes into the vacuum shaping mold, which is cooled by circulating water to produce the desired shape. The profile is continuously pulled out of the mold head by the pulling force of the traction machine and then reaches the cut-to-length process, where it is cut to a certain length.
The speed of the profile in the shaping mold needs to be matched with the extrusion volume, it cannot be too fast or not too slow. If it runs too fast, it will easily make the wall too thick and the profile too thin, so that the product quality will be affected; If it runs too slow due to the inability to pull away the material from the mold head in time, the material will be gathered in the mold head, which caused a plugging accident, resulting in the shut down of production.
In the cooling and shaping process, the traction speed of the material, water temperature, vacuum, etc. are the key production parameters. The temperature of cooling water is one of the key factors, if you can not guarantee the temperature of the cooling water, the production line will not be able to carry out normal production, in that case, the product will cause a variety of problems, especially in summer, the temperature of the material comes from the mold head is around 200 degrees, if it can not be cooled in time then it can not guarantee the normal production, not to mention the material will also be affected by the impact of the internal force, thus affecting the quality of the product itself.
Generally speaking, in order to control the water temperature, the manufacturers usually equip their products with refrigerators, cooling pools, cooling water towers and other equipment to ensure the production of qualified products. It takes 24 hours at least to cool down the profiles and then go to load and ship.
Ⅳ. Precautions in the Operation Process
1、Special attention should be paid to fire fighting, fire extinguishers need to be placed near the use of machinery and equipment.
2、If abnormal situation exists, it should be reported to the relevant staff at once. If there are abnormal problems that is extremely dangerous, please immediately press the emergency stop button.
3、Do not use low-quality recycled materials with metal material residues or fine sand, and do not place metal objects that may fall into the vicinity of the feed opening to prevent problems of deepening of the extruder screw, barrel damage or jamming, damage.
4、Plastic machinery and equipment operation process requires cleanliness, viscosity and other indices are in line with the requirements of the gear oil, and meet the requirements of the water cooler to give sufficient flow of cooling water to prevent hydraulic parts and piping due to compressor lubricant environmental pollution or sustained high temperatures resulting in blockage, oil seepage and other damage problems. Extruder should add lubricating oil to the speed reducer to meet the requirements.
5、Plastic machinery and equipment operating process should be strictly in accordance with the provisions of the operating procedures, non-operating workplace for unauthorized behavior cannot be allowed. It’s important to ensure the reliability of the safety device and it is strictly prohibited to only pursue efficiency and destroy the safety protection measures of the equipment.
6、During the operation of plastic machinery and equipment, if the material temperature does not reach the set temperature and the holding time is insufficient, the extruder screw can not be started.
7、The operation process should be carried out by the staff who are trained and familiar with the structural performance and operating process of plastic mechanical equipment.
We hope that this article has been informative for you in understanding how these machines work. If you have any questions or suggestions about this topic or anything else related to plastic machinery technology, please don't hesitate to contact us!