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| Plastic extruder process requirements |
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Source：admin Popularity：2118 Release time：2019-02-06
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Cooling in the cold plastic extrusion process system is also an important one. Generally divided into screw cooling, fuselage cooling, and product cooling. 1. The cooling screw of the screw cools the friction and heats up, stabilizes the extrusion pressure, promotes uniform mixing of the plastic, and improves the quality of plasticization. However, its use must be appropriate, especially not too much, otherwise the plastic melt in the barrel suddenly cools, which can lead to serious accidents. Screw cooling is absolutely forbidden before extrusion, otherwise it will cause serious equipment accidents. 2. Cooling of the fuselage The function of cooling the fuselage is to increase the heat dissipation of the barrel to overcome the temperature rise caused by frictional overheating, because this temperature rise cannot be stopped during the extrusion process even after the heating power supply is cut off, thus making it reasonable. The temperature cannot be maintained for a long period of time, heat must be increased, and the barrel is cooled down to maintain heat balance during extrusion. The fuselage cooling is carried out in sections, mainly based on fan cooling. Considering the different functions of the fuselage sections, pay special attention to the use of homogenized section cooling. 3. Cooling of the product cooling is to ensure the geometry and internal structure of the product. Important measures. After the plastic extrusion layer leaves the machine head, it should be cooled immediately, otherwise it will be deformed under the action of gravity. For non-crystalline materials such as polyvinyl chloride, the problem of crystallization can be ignored. The plastic product can be quenched by direct cooling with water, so that it is cold-permeable in the cooling water tank and is no longer deformed. The cooling of crystalline polymers such as polyethylene and polypropylene should take into account the crystallization problem. If the quenching method is adopted, it will adversely affect the microstructure of the plastic product and generate internal stress, which is the result of cracking of the product in the future. One of the reasons must be paid attention to in the extrusion process; the extrusion coating of crystalline plastics such as polyethylene and polypropylene should be carried out by a stepwise cooling method using warm water cooling. Generally, depending on the auxiliary equipment of the equipment, the cooling water tank should be divided. Sectional section, the water temperature can be started from the plastic extrusion layer into the first section of the water tank from 75 ° C to 85 ° C, the water temperature is reduced step by step, until room temperature, the smaller the temperature difference of each section of water temperature is more reasonable.
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