The working principle of the extruder is: the use of a specific shape of the screw, rotating in the heated barrel, the plastic sent from the hopper to squeeze forward, so that plastic uniform plastic (that is, melting), through the nose and different shapes Of the mold, so that the plastic extrusion into a continuous need for a variety of shapes of plastic layer, squeezed on the core and cable.
1. The plastic insulation and sheath of the wire and cable are carried out by means of continuous extrusion. The extrusion equipment is generally a single screw extruder. Plastic before the extrusion, to check whether the plastic in advance or no other debris, and then the screw preheated after adding to the hopper. In the extrusion process, the plastic loaded into the hopper by means of gravity or feeding screw into the barrel, under the action of the rotating screw thrust, continue to move forward, from the preheat section began to gradually moving to the homogenization section; the same time, plastic By the screw stirring and squeezing effect, and in the barrel of the external heat and plastic and equipment under the action of the shear friction into a viscous flow in the groove to form a continuous uniform flow. In the process under the provisions of the temperature, the plastic from the solid state into a molten state of the plastic body, and then by the screw to promote or stirring, will be fully plasticized plastic pushed into the head; to reach the nose of the material, And the mold sleeve between the ring gap, extruded from the mold mouth, squeezed in the conductor or core around the formation of a continuous dense insulation layer or jacket layer, and then by cooling and curing, made of wire and cable products. The three stages of the extrusion process.
2. Material extrusion is the most important basis for the plastic mold has. Plastic molding in the extruder is a complex physical process that involves mixing, crushing, melting, plasticizing, venting, compaction and final shaping. Everyone’s attention is that this process is continuous to achieve. However, it is customary that people tend to squeeze the continuous process of the extrusion process according to the different reaction of the plastic, which is divided into different stages, namely: the plasticizing stage (mixing, melting and homogenizing the plastic); the molding stage (plastic extrusion Molding); the molding stage (cooling and curing of the plastic layer).
1. plasticization stage. Also known as the compression phase. It is completed in the extruder barrel, through the rotation of the screw, so that the plastic from the granular solid into plasticity of the viscous fluid. Plastic in the plasticization stage to obtain the source of heat there are two aspects: First, the external heating of the barrel; Second, the friction generated when the screw friction. The initial heat is generated by the external heating of the barrel, when the normal drive, the heat is obtained by the screw optional material in the compression, cutting, mixing process with the barrel of the friction between the material and molecules Friction produced.
2. Molding stage. It is carried out in the head, due to the role of screw rotation and pressure, the sticky fluid to the nose, the nose of the mold, the viscous fluid into the required size of the various sizes of extruded material, and package Covered with a core or conductor.
3. Stereotyping stage. It is in the cooling water tank or cooling pipe carried out, the plastic extrusion layer after cooling, from the amorphous plastic state into a solid state of stereotypes.