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The auxiliary equipment of plastic extrusion unit mainly includes pay off device, straightening device, preheating device, cooling device, traction device, meter counter, spark tester and take-up device. The purpose of extruder is different, and the matching auxiliary equipment is also different, such as cutter, dryer, printing device, etc.

Straightening device

One of the most common types of plastic extrusion waste is eccentricity, and various types of core bending is one of the important reasons for insulation eccentricity. During the extrusion of sheath, the scratch of sheath surface is often caused by the bending of cable core. Therefore, the straightening device in various extrusion units is essential. The main types of straightening device are: roller type (divided into horizontal type and vertical type); Pulley type (divided into single pulley and pulley block); Winch type, with drag, straightening, stable tension and other functions; Roller type (divided into horizontal type and vertical type), etc.

Preheating device

Core preheating is necessary for insulation extrusion and sheath extrusion. For the insulation layer, especially the thin insulation layer, the existence of pores is not allowed. The moisture and oil on the surface of the core can be completely removed by high temperature preheating before extrusion. As for the extrusion of the sheath, its main function is to dry the cable core and prevent the possibility of air holes in the sheath due to the effect of moisture (or the moisture around the cushion). Preheating can also prevent the effect of residual internal pressure during extrusion due to sudden cooling. In the extrusion process, preheating can eliminate the temperature difference caused by the cold wire entering the high temperature die and contacting with the plastic at the die mouth, so as to avoid the fluctuation of extrusion pressure caused by the fluctuation of plastic temperature, so as to stabilize the extrusion quantity and ensure the extrusion quality. The electric heating wire core preheating device is used in the extrusion line, which requires sufficient capacity and rapid temperature rise, so that the wire core preheating and cable core drying efficiency is high. The preheating temperature is restricted by the setting out speed, which is generally similar to the head temperature.

cooling system

The plastic extrusion layer should be cooled immediately after leaving the die, otherwise it will deform under the action of gravity. The cooling method is usually water cooling, and according to the different water temperature, it can be divided into rapid cooling and slow cooling. Quench is the direct cooling of cold water. Quench is beneficial to the shaping of plastic extrusion cladding layer. However, for crystalline polymers, because of the sudden hot cooling, it is easy to residual internal stress in the extrusion cladding layer, which leads to cracking in the process of use. Generally, quench is used for PVC plastic layer. Slow cooling is to reduce the internal stress of the products. Water of different temperatures is placed in the cooling water tank in sections to gradually cool the products and set the shape. Slow cooling is used for PE and PP extrusion, that is, three stages of cooling are hot water, warm water and cold water.