A brief analysis of the auxiliary device of plasti

2022-08-16
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Brief analysis of the auxiliary device of plastic extruder

the auxiliary device of Plastic Extruder mainly includes setting out device, straightening device, preheating device, cooling device, traction device, meter counter,

spark tester, and take-up device. The purpose of the extruder unit is different, and the auxiliary equipment used for its selection is also different. For example, there are cutters, dryers, printing devices, etc

straightening device: the most common type of plastic extrusion waste is eccentricity, and various types of bending of wire core is one of the important reasons for insulation eccentricity. During jacket extrusion, the scratch on the jacket surface is often caused by the bending of the cable core. Therefore, the straightening device in various extrusion units is essential. The main types of straightening devices are: roller type (divided into horizontal type and vertical type); Pulley type (divided into single pulley and pulley block); Winch type, which plays a variety of roles such as dragging, straightening and stabilizing tension; Roller type (divided into horizontal type and vertical type), etc

preheating device in recent years: cable core preheating is necessary for insulation extrusion and sheath extrusion. For the insulation layer, especially the thin-layer insulation, the existence of pores is not allowed. The wire core can completely remove the water and oil on the surface by preheating at high temperature before extrusion. As for the extrusion of the sheath, its main function is to dry the cable core to prevent the possibility of pores in the sheath due to the effect of moisture (or moisture wrapped around the cushion). Preheating can also prevent the effect of residual internal pressure of plastic due to sudden cooling during extrusion. In the process of plastic extrusion, preheating can eliminate the cold line entering the high-temperature machine head, break the dependence on tangible resources, and avoid the wide temperature difference formed when contacting the plastic at the die mouth, so as to avoid the fluctuation of plastic temperature and the fluctuation of extrusion pressure, so as to stabilize the extrusion volume and ensure the extrusion quality. Electric cored preheating depth is adopted in the extrusion unit: > 860 mm; The device is required to have sufficient capacity and ensure rapid temperature rise, so that the wire core preheating and cable core drying efficiency are high. The preheating temperature is restricted by the setting out speed, which is generally similar to the head temperature

cooling device: the formed plastic extruded layer should be cooled and shaped immediately after leaving the machine head, otherwise it will deform under the action of gravity. The cooling method usually adopts water cooling, which is divided into rapid cooling and slow cooling according to different water temperatures. Quenching is the direct cooling of cold water, which is beneficial to the shaping of plastic extruded layer. However, for crystalline polymers, due to sudden heat cooling, it is easy to residual internal stress in the extruded layer tissue, resulting in cracking during use. Generally, PVC plastic layer adopts quenching. Slow cooling is to reduce the internal stress of the products. Water with different temperatures is placed in the cooling water tank in sections to gradually cool and finalize the products. Slow cooling is used for the extrusion of PE and PP, that is, it is cooled by three stages of hot water, warm water and cold water (PA: Pascal =n/m2)

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