Specializing in the production of sheet extruder heads and molds: the head is composed of an alloy steel inner sleeve and a carbon steel outer sleeve, and the head is equipped with a forming die. The function of the machine head is to transform the plastic melt that rotates into parallel and linear motion, introduce it evenly and smoothly into the mold sleeve, and give the plastic the necessary forming pressure. The plastic is plasticized and compacted in the barrel, and passes through the porous filter plate along a certain flow path through the neck of the head and flows into the head forming mold. The core mold sleeve is properly matched to form a circular gap with a decreasing cross-section, so that the plastic melt is in the A continuous and dense tubular coating is formed around the core wire. In order to ensure that the plastic flow path in the machine head is reasonable and eliminate the dead angle of the accumulated plastic, a shunt sleeve is often installed. In order to eliminate the pressure fluctuation when the plastic is extruded, there is also a pressure equalizing ring. The head is also equipped with a mold correction and adjustment device, which is convenient for adjusting and correcting the concentricity of the mold core and the mold sleeve. The extruder divides the machine head into a beveled machine head (with an included angle of 120o) and a right-angle machine head according to the angle between the head material flow direction and the centerline of the screw. The shell of the machine head is fixed to the fuselage with bolts. The die in the machine head has a core seat and is fixed to the wire inlet port of the head with a nut. The front of the core seat is equipped with the core, the core and the core seat. There is a hole in the center for passing the core wire; a pressure equalizing ring is installed at the front of the machine head to balance the pressure; the extrusion molding part is composed of a die sleeve and a die sleeve; the position of the die sleeve can be adjusted by the bolt through the support In order to adjust the relative position of the mold sleeve to the core, it is easy to adjust the uniformity of the thickness of the extrusion cladding. The head is equipped with a heating device and a temperature measuring device. 2. Transmission system The function of the transmission system is to drive the screw and supply the torque and speed required by the screw during the extrusion process. It usually consists of a motor, a reducer and a bearing. 3. Heating and cooling device Heating and cooling are necessary conditions for the plastic extrusion process. (1) Currently, extruder usually uses electric heating, which is divided into resistance heating and induction heating. The heating sheet is installed in the body, neck and head. The heating device heats the plastic in the cylinder externally to increase the temperature to reach the temperature required for the process operation. (2) The cooling device is set to ensure that the plastic is in the temperature range required by the process. Specifically, it is to exclude the excess heat generated by the shear friction caused by screw rotation, so as to avoid the temperature being too high to make the plastic decompose, scorch, or shape difficult. The barrel cooling is divided into two types: water cooling and air cooling. Generally, small and medium-sized extruders are more suitable for air cooling, and large-sized ones are mostly water-cooled or combined with two forms of cooling. To stabilize the amount of glue and improve product quality; but the cooling at the hopper is to strengthen the transport of solid materials, to prevent plastic particles from sticking due to temperature rise, and to ensure the normal operation of the transmission part. 2. 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 tester, and a take-up device. Extruder units have different optional auxiliary equipment for different purposes. Such as cutters, blow dryers, printing devices and so on. Straightening device: The most common type of plastic extrusion waste is eccentricity, and the bending of various types of cores is one of the important reasons for eccentric insulation. In sheath extrusion, scratches on the sheath surface are also often caused by the bending of the cable core. Therefore, the straightening device in various extrusion molding units is essential. The main types of straightening devices are: roller type (divided into horizontal and vertical type); pulley type (divided into single pulley and pulley group); winch type, which has multiple functions such as dragging, straightening, and stable tension; Wheel type (divided into horizontal type and vertical type). Preheating device: Preheating of the cable core is necessary for both insulation extrusion and sheath extrusion. For the insulation layer, especially the thin layer insulation, the existence of pores cannot be allowed. The core of the wire can be completely removed from the surface by oil and oil before being extruded. For the extrusion of the sheath, its main function is to dry the cable core to prevent the possibility of air holes in the sheath due to the action of moisture (or moisture around the cushion layer). Preheating can also prevent the residual internal pressure of the plastic from being quenched during extrusion. In the process of extruding plastic, preheating can eliminate the cold wire entering the high-temperature head and the disparity in temperature formed when the die is in contact with the plastic. It can avoid the fluctuation of the extrusion pressure caused by the fluctuation of the plastic temperature. Extrusion quality. The extruder unit uses an electric core preheating device, which requires sufficient capacity and ensures rapid heating, so that the core preheating and cable core drying efficiency are high. The preheating temperature is restricted by the speed of the discharge line, which is generally similar to the temperature of the machine head. Cooling device: After leaving the machine head, the formed plastic extrusion cladding should be cooled and shaped immediately, otherwise it will be deformed by the force of gravity. The cooling method usually uses water cooling, and it is divided into rapid cooling and slow cooling according to different water temperatures. Quenching is the direct cooling of cold water. The quenching is beneficial to the shaping of the plastic extrusion cladding, but for crystalline polymers, due to the rapid cooling, it is easy to leave internal stress inside the extrusion cladding structure, which causes cracks during use. Generally PVC The plastic layer is quenched. Slow cooling is to reduce the internal stress of the product. Water of different temperatures is placed in sections in the cooling water tank to gradually reduce the temperature of the product. Three-stage cooling. discount price.
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