Views: 0 Author: Uplion Publish Time: 2021-11-30 Origin: Uplion
Features of special production equipment for wood plastic materials
Although the extrusion processing methods and main equipment of wood-plastic materials are similar to plastics on the surface, as an emerging industry with marginal, multi-faceted, and specialized characteristics, its equipment, technology and processes involve chemical engineering, fine chemicals, and precision. Machinery, hydraulic transmission, vacuum technology, heat conduction, fluid mechanics, sensor technology, electronic automatic control, computer programming and physical chemistry and other majors and disciplines, its production equipment is unique. After years of development and application, practice has proved that as a new type of material with independent characteristics, wood-plastic materials are far more difficult to process than ordinary plastic products, and production equipment is becoming more and more specialized and specialized.
The key technology for the production of wood-plastic materials is to ensure that the wood powder has high fluidity and plasticization under the premise of high filling content, so as to promote the plastic melt to be fully combined with the wood powder to achieve the purpose of joint compounding. The product has high physical and mechanical properties and good use performance. Finally, products with excellent functions and high added value can be manufactured at a lower cost. Compared with processing plastics, wood-plastic material production equipment has many new characteristics and requirements. In the production process of wood-plastic composite materials, there are a large amount of wood or other biomass materials in the raw materials, which hinder the transfer of heat, which makes the plasticization performance of the melt decrease, the fluidity deteriorates, and the extrusion resistance increases. The torque of the screw increases, and the wood is easily decomposed at high temperature, which causes the quality of the product to decrease. Therefore, it is required to adopt a special process in the screw design to meet the requirements of good material plasticization performance and material conveying function at lower temperatures. In addition, due to the existence of a large amount of wood powder, it will increase the abrasion of the barrel and screw in the equipment. Therefore, the steel used in the equipment used for the production of wood-plastic composite materials cannot continue to use the steel used in traditional plastic machinery. Due to the small specific gravity and large filling volume of wood materials, the volume of the feeding area is larger and longer than that of conventional models; if the volume of wood powder is large, the molten resin has strong rigidity, and a high back pressure resistant gearbox is required; the screw driving force is strong, so it should be used The screw with fast compression and melting and short metering section ensures short residence time of wood flour and so on. At the same time, the degree of fiber orientation of wood-plastic composites during processing has a greater impact on product performance, so it is necessary to rationally design the flow channel structure to obtain appropriate fiber orientation to meet the performance requirements of the product. In terms of mold design, the melt fluidity of wood-plastic composites is poor, and the melt self-repairing ability is poor, which can easily cause melt fracture.
Therefore, it is required that the inner cavity has a higher smoothness or special materials are used for processing in the mold design.
In addition, under the same strength requirements, wood-plastic composite materials have a larger thickness than pure plastics, and they are mostly special-shaped materials with complex structures. This makes it more difficult to cool. Generally, water cooling is used, but for larger cross-sectional areas or complex structures Products also need to use special cooling devices and methods.