We use wood fiber filler (wood flour, rice husk, straw and so on) and waste thermoplastic as main raw materials, plus a part of processing aids, and melt and plasticized and mixed extrusion to make products, called wood plastic composite products. It is an important research achievement of composite materials research and development and recycling of waste plastics in recent years. It is a natural green environmental protection material, and can be made into plates, profiles, pipes and so on. It is widely used in packaging, building, decoration and other industries. Because extrusion process is short, high efficiency, and molding process is simple and practical, it can produce many kinds and multi specifications of wood and plastic products. Therefore, extrusion molding is the most ideal method in wood plastic material processing and molding. This unit is developed for the processing and forming characteristics of wood plastic composite material.
The special extruder for wood plastic profile is designed by foreign advanced technology, mainly composed of extrusion system, transmission and torque distribution device, quantitative feeding device, vacuum exhaust device and temperature control system.
(1) the extrusion system is the heart part of the extruder. High quality alloy steel and nitriding are used in screw and cylinder, with high strength, hardness and corrosion resistance. The material falls from the feeding device to the screw feed section, and it quickly separates to the two sides. With the screw's rotation movement, it is continuously transported forward, and at the same time, the material contacts with the heated cylinder, and gradually absorbs heat and starts melting. The compression of the material is mainly realized by the change of the number of threads on the screw and the pitch of the screw. In view of the characteristics of wood plastic composite material, a section of mixing material is added to the screw structure of the machine in order to make the material well mixed and uniform. The screw pitch of the exhaust section is increased, which is beneficial to the discharge of the gas through the vent in the front of the cylinder. The screw thread of the measurement section is optimized to achieve quantitative constant pressure extrusion, without the shear overheating, so as to achieve the stable extrusion of the material.
(2) the transmission parts of the gearbox and distribution box are made of ultra-high strength alloy steel and carburized and quenched. The hardness of the gear surface reaches HRC55. The box body is made of nodular cast iron and has many sides cutting process, which is rigid, smooth and beautiful. The life of the combined design is up to 2 to 50 thousand hours.
(3) this machine feeding system is equipped with a spring automatic feeding machine and a screw type quantitative feeding device. In order to prevent the phenomenon of "bridging", the agitator is added. The quantity of feeding of the extruder can be continuously and uniformly changed by the variable frequency speed regulation.
(4) the vacuum exhaust system consists mainly of the vacuum exhaust system, the pipeline and the vacuum table, and the natural and forced exhaust can be used.
(5) the temperature control system is mainly composed of the heater, the fan and the screw core temperature regulating device. Through the electrical control system, the temperature can be controlled automatically. Two screw ends are equipped with two copper sealing rings, which are connected with the core temperature regulating device through four metal hoses. The seal of the heat conducting oil is realized by two high temperature skeleton oil seals at the ends, and there is a high temperature resistant O ring in the middle to separate the oil from the inlet and outlet.