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          What are the auxiliary devices of twin-screw extruder?
          Author:administrator ?? Posted on:2018-04-25 13:31:13 ?? Text:【Big】【Medium】【Small】Browse (109)
          Summary:The most common type of plastic extrusion waste is eccentricity......

          Straightening device:

          The most common type of plastic extrusion waste is eccentricity, and various types of wire core bending are one of the important causes of insulation eccentricity. In sheath extrusion, scratches on the jacket surface are also often caused by the bending of the cable core. Therefore, the straighteners in various extrusion units are indispensable. The main types of straightening devices are: drum type (divided into horizontal type and vertical type); pulley type (divided into single pulleys and pulley sets); twisted wheel type, which also functions as dragging, straightening, and stabilizing tension; Pneumatic wheel type (horizontal and vertical type) etc

          Preheating device:

          Core preheating is necessary for insulation extrusion and jacket extrusion. For the insulation layer, especially the thin layer insulation, the presence of pores cannot be allowed. The preheating of the core before high temperature can completely remove the moisture and oil on the surface. For sheath extrusion, its main role is to dry the core, preventing the possibility of air pockets in the sheath due to moisture (or moisture around the mat). Preheating can also prevent the residual pressure of the plastic from escaping during extrusion. In the process of squeezing plastic, preheating can eliminate the temperature difference between the cold line entering the high-temperature machine head and contact with the plastic at the die mouth, avoiding fluctuation of the plastic temperature and fluctuating the extrusion pressure, thereby stabilizing the extrusion volume and ensuring Extrusion quality. Extruder unit uses electric heating core preheating device, which requires sufficient capacity and guarantees rapid temperature rise, so that core preheating and core drying efficiency are high. The preheating temperature is restricted by the line speed, and it is generally similar to the head temperature.

          Cooling device:

          After the molded plastic extruded layer leaves the head, it should be immediately cooled and set, otherwise it will be deformed under the action of gravity. The cooling method is usually water-cooled and divided into quench and slow cooling depending on the water temperature. The quenching is the direct cooling of the cold water. The quenching is beneficial to the shaping of the extruded plastic layer. However, for the crystalline polymer, due to sudden cooling, internal stress is easily left in the extruded layer structure, resulting in cracks during use. Generally, PVC is used. The plastic layer is quenched. Slow cooling is to reduce the internal stress of the product. In the cooling water tank, water is placed at different temperatures in sections, so that the product gradually cools and stereotypes. The extrusion of PE and PP is performed by slow cooling, that is, through hot water, warm water, and cold water. Three stages of cooling.

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