Extruder auxiliary equipment

The auxiliary equipment of the plastic extrusion unit mainly includes a pay-off device, a straightening device, a preheating device, a cooling device, a traction device, a meter counter, a spark testing machine, and a take-up device. Depending on the purpose of the extrusion unit, the optional auxiliary equipment is also different, such as cutters, dryers, printing devices, etc.
straightening device
The most common type of plastic extrusion waste is eccentricity, and various types of bending of the wire core are one of the important reasons for insulation eccentricity. In sheath extrusion, scratches on the sheath surface are often caused by bending of the cable core. Therefore, alignment devices in various extrusion units are 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 group); winch type, which has multiple functions such as dragging, straightening, and stabilizing tension; Press wheel type (divided into horizontal type and vertical type), etc.
Preheating device
Cable core preheating is necessary for both insulation extrusion and sheath extrusion. For the insulation layer, especially thin layer insulation, the existence of pores cannot be allowed. The wire core can be completely removed from surface moisture and oil by high-temperature preheating before extrusion. For sheath extrusion, its main function is to dry the cable core to prevent the possibility of pores in the sheath due to moisture (or moisture around the cushion layer). Preheating can also prevent the residual internal pressure caused by the sudden cooling of the plastic during extrusion. During the plastic extrusion process, preheating can eliminate the large temperature difference formed when the cold wire enters the high-temperature machine head and contacts the plastic at the die mouth, avoiding fluctuations in the extrusion pressure caused by fluctuations in plastic temperature, thereby stabilizing the extrusion volume and ensuring Extrusion quality. The extrusion unit uses an electric heating wire core preheating device, which requires sufficient capacity and ensures rapid temperature rise, so that the wire core preheating and cable core drying efficiency are high. The preheating temperature is restricted by the pay-off speed and is generally similar to the temperature of the machine head.
cooling device
The formed plastic extrusion cladding should be cooled and shaped immediately after leaving the machine head, otherwise it will be deformed under the action of gravity. The cooling method usually uses water cooling, and is divided into rapid cooling and slow cooling according to different water temperatures. Rapid cooling is direct cooling with cold water. Rapid cooling is beneficial to the shaping of plastic extruded cladding. However, for crystalline polymers, due to the sudden cooling, internal stress is likely to remain inside the extruded cladding structure, resulting in cracks during use. Generally, PVC The plastic layer is rapidly cooled. Slow cooling is to reduce the internal stress of the product. Water of different temperatures is placed in the cooling water tank in sections to gradually cool down the product and shape it. For the extrusion of PE and PP, slow cooling is used, that is, through hot water, warm water, and cold water. Three stages of cooling.