Profile Die Design And Flow Analysis Of PVC/wood Composite

Wood plastic composite (WPC) integrates the advantages of wood and plastics. The addition of some kinds of additives can make it have some special performances. It is friendly to environments and its raw materials are cheap and plenteous. So it gets the attentions of many investigators.But the special performances and requests of WPC make it have rigourer requests to extrusion equipments, technology and die than general plastics. The design of dies determinates the quality of products in a great degree. At present, the investigations of WPC die are very little.Aiming at this situation, the rheologic properties of PVC/wood composites were studied in this paper. According to the rheologic properties, the geometry and finite element model were set up and simulated with inverse extrusion function of POLYFLOW. The flow field of the melt in the die and the shape of the lip to get I-shape products were obtained. The effects of different geometry parameters to the flow field were analyzed with orthogonal tables. The main achievements and conclusions are as following:1. The melt flows slowly and calmly in the joint segment and stabilization segment. The speed of melt and its difference in the sectionincrease rapidly and there is little melt stagnating in the compression segment and calibrating segment. The speed of the melt flow becomes identical and the shape of the profile becomes regular I-shape after leaving the lip 40 mm. Among the geometric parameters, the length of the compression zone L3 and the compression gap Adi have the most important influence on the speed distribution of the section 2 mm away from the lip. The next are the length of the stabilization zone L2, the length of the calibrating zone L4, the compression gap Ad2 and Ad4. And when they take the big value the distribution of the speed is uniform. The effect of the compression gap Ad3 is the least among the geometric parameters.2. The pressure drop is little in the joint segment and becomes nonlinear in the compression segment. The pressure drop mainly happens in the calibrating segment, which is about 4/5 of the whole pressure drop and the pressure grads in the calibrating segment is the biggest. The length of the calibrating zone L4 has the most important effects on the pressure drop. The second of the most important factors is the length of the compression zone L3. And when they adapt the bigger value, the pressure drop is bigger. The compression gap Ad4 has the least effect on the pressure drop.3. The shear rate increases gradually along the extrusion direction, but the maximum of the shear rate in 8 kinds of simulate is less than 100 s"1. Among the geometric parameters, the length of the compression zone L3...