1. Straightening device. During the extrusion of the sheath, the scratches on the surface of the sheath are caused by the bending of the cable core. The bending will cause insulation eccentricity, resulting in plastic extrusion of the product as waste. Therefore, straightening devices in various extrusion units are also indispensable. The main types of straightening devices are pressure wheel type, winch wheel type, pulley type and roller type.
2. Cooling device, the formed plastic extrusion cladding should be cooled and shaped immediately after leaving the machine head, otherwise it will be deformed, which requires the use of a cooling device. The cooling method is mainly water cooling, and water cooling is divided into rapid cooling and slow cooling. Rapid cooling is direct cooling, which is conducive to shaping; slow cooling is to reduce the internal stress of the product.
3. Preheating device, the preheating of the cable core of the double screw extruder machine is very important for sheath extrusion and insulation extrusion. For sheath extrusion, its function is to dry the cable core and prevent moisture from entering the sheath to form pores; it can also prevent the extruded plastic from remaining internal pressure due to sudden cooling; Preheating the core can completely remove oil and moisture on the surface; during the extrusion process, preheating can remove the cold wire entering the high-temperature machine head, forming a temperature difference, which can stabilize the extrusion volume and ensure the quality of extrusion. This is also a twin-screw extrusion process. The reason why the machine manufacturer must use the preheating device.
If the double screw extruder machine extrudes irregular or flat products, the temperature change of the molten material may affect the external dimensions of the product; but if the double screw extruder machine extrudes a round product, these changes will It will not cause serious consequences; in a flat mold, if the molten material is relatively cold, it may cause the periphery of the sheet to be thicker and the center to be thinner. It can be solved by correcting the manual or automatic adjustment of the mold. In addition, behind the filter screen changer, a gear pump can be equipped to ensure that the molten material can enter the mold stably.
Double-screw extruder filter is used in a large amount. When the filter becomes clogged and needs to be replaced, the pressure suddenly drops and the temperature of the molten material may drop as well, which changes the size of the product. Therefore, in order to keep the size of the product uniform, two methods can be used to solve it, one of which is to adjust the linear speed of the double screw extruder machine; the other is to adjust the screw speed of the double screw extruder machine.
The double screw extruder machine is composed of a screw, a barrel, a feeding device and a transmission device. During the operation, the material is added in the feeding device, and through the action of the screw, it reaches the machine head. During this operation, the movement of the material It will be different according to the direction of rotation of the screw and the way of engagement, among which the filter screen has a certain influence on the extrusion of plastic.
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