The main machine of plastic granulator is the extruder system

The main machine of plastic granulator is the extruder system, which consists of extrusion system, transmission system and heating and cooling system. 1. Extrusion system: Extrusion system consists of screw, barrel, hopper, head, and mold plastic through the extrusion system plasticized into a uniform melt, and in the process of establishing the pressure by the screw continuous Extruder head. (1) Screw: The most important part of the extruder, it is directly related to the application range and production efficiency of the extruder, made of high strength and corrosion-resistant alloy steel. (2) barrel: a metal seamless tube, generally with heat, high compressive strength, strong wear-resistant, corrosion-resistant alloy steel or lined steel alloy steel pipe made of. Barrel and screw with the realization of the smashing of plastics, softening, melting, plasticizing, exhaust and compaction, and to the molding system for the continuous delivery of rubber. The length of a typical barrel is 18: 1 of its diameter, so that the plastic is fully heated and fully plasticized into principle. (3) hopper: the bottom of the hopper equipped with truncation device, in order to adjust and cut off the stream, the side of the hopper equipped with visual hole and calibration metering device. (4) nose and mold: nose from the alloy steel sleeve and carbon steel jacket composition, the nose is equipped with forming mold. The role of the nose is the rotational movement of the plastic melt into parallel linear motion, uniform and smooth into the die set, and give the plastic with the necessary molding pressure. Plastic plastic compaction in the barrel, the porous filter plate along a certain flow through the neck neck into the nose molding machine, die core die sets appropriate fit to form a reduced cross-sectional annular gap so that the plastic melt in the Around the core wire to form a continuous dense tubular coating. In order to ensure the plastic flow in the nose is reasonable, to eliminate the dead ends of accumulated plastic, often with a manifold (sleeve), in order to eliminate the plastic extrusion pressure fluctuations, but also set the pressure ring. The nose is also equipped with mold correction and adjustment of the device, easy to adjust and correct mold core and die sets of concentricity. According to the direction of extrusion machine head and screw the direction of the center line angle, the head is divided into bevel head (120 degrees) and right angle (90 degrees) head. The head of the shell is bolted to the fuselage, the nose of the mold with a mold core to sit and nut fixed to the nose into the port, the front of the mold core with a mold core, mold core and core seat The center of the hole, for through the core line; in front of the nose are equipped with pressure ring, for equalization pressure; extrusion molding part by the die sets and die sets, the die sleeve position by the bolt through the support to adjust , In order to adjust the relative position of the mold sleeve to the mold core to facilitate the adjustment of the uniformity of the thickness of the extrusion coating. The nose is equipped with heating device and temperature measuring device. 2. Transmission system: The function of the transmission system is to drive the screw rod to supply the required torque and speed of the screw rod in the extrusion process, usually composed of a motor, a reducer and a bearing. 3. Heating and cooling device: Heating and cooling are the necessary conditions for the plastic extrusion process to be carried out. (1) The extruder is usually used for electric heating, divided into resistance heating and induction heating, heating film installed in the fuselage, neck, head of the various parts. Heating device by the external heating tube plastic, so that the temperature, in order to achieve the required temperature of the process operation. (2) The cooling device is set to ensure that the plastic is in the temperature range required by the process. Specifically, in order to exclude excess heat generated by the shear friction of screw rotation, to avoid the temperature is too high to break down the plastic, scorching or setting difficult. Cylinder cooling is divided into two kinds of water-cooled and air-cooled, the general small and medium-sized extruder with air-cooled more appropriate, large are more water-cooled or combined with the two forms of cooling; screw cooling is mainly used in the center of water-cooled, the purpose is to increase the solid material delivery rate , And stabilize the amount of plastic, while improving product quality; but in the hopper cooling, one is to strengthen the role of solid material transport to prevent the plastic particles due to temperature rise blockage mouth, and second, to ensure that the transmission part of the normal work. Second, auxiliary equipment: Auxiliary machines for pelletizing granulation units include pay-off devices, straightening devices, preheating devices, cooling devices, traction devices, meters, spark testing machines and wire take-up devices. The use of extrusion unit different auxiliary equipment used for matching Preparation is not the same. If there are cut off, dryer, printing devices. Straightening device: The most common type of plastic extrusion scrap is eccentricity, and bending of various types of core is one of the important reasons for insulation eccentricity. In jacket extrusion, the sheath surface scratches are often caused by the bending of the cable core. Therefore, straightening devices in various extrusion units are essential. The main types of straightening device are: drum type (divided into horizontal and vertical); pulley type (divided into single pulley and pulley block); winch type, combined with drag, straighten, stable tension and other functions; Pressure wheel type (divided into horizontal and vertical) and so on. Preheating device: Preheating of cable core is necessary for both insulation and jacket extrusion. For the insulation, especially thin insulation, can not allow the presence of pores, the core in the extrusion through the high temperature preheating can be completely clear the surface of the water, oil. For sheath extrusion, its main role is to dry the core to prevent the possibility of porosity in the sheath due to moisture (or moisture around the mat). Preheating can also prevent the extrusion of plastic due to the role of residual pressure and internal stress. In the process of extrusion of plastic, preheating can eliminate the cold line into the high temperature head, the mold at the mouth of the plastic contact with the formation of disparities in temperature, to avoid fluctuations in plastic temperature caused by pressure fluctuations, so as to stabilize the amount of extrusion, to ensure that Extruded quality. Extruder units are used electric heating wire preheater, requires adequate capacity and ensure rapid heating, so that the core preheating and core drying efficiency. Preheating temperature by the release line speed constraints, the general head temperature can be similar.