Numerical Simulation And Experimental Study On Gas-Assisted Co-Extrusion Of Polymer Profile With A Y Section

Plastic profile is a polymer extrusion products whose cross sections'shape is complex and irregular, not circular,it which has advantages of light and environment protection. The molding technology of co-extrusion which blends materials that have different performances and characters obtain composite materials, the technology comparing with extrusion technology of a single polymer which can be based on different properties of the composite materials can take advantage of the characters of different materials,But its products existed extrusion swelling and deformation defects. Gas-assisted extrusion which use gas in polymer extrusion establish a stable layer of air mattress to isolate between the wall of die and the extrusion polymer, it can greatly reduce the degree of polymer swelling, meanwhile,it can obtain products whose shape are the same with the die's cross section. In order to get better quality products,the gas-assisted co-extrusion process was put forward and studied, Previous of section is circular and linear stratification on coating coextrusion which were researched many times, but section of complex on extrusion coated was less researched. The Y type section whose curves and straight lines intersect and intersecting angle is not straight section of the usual Cartesian was studied, the thesis that the profile coated extrusion of gas-assisted would be studied got numerical simulation and experiment study. the main research contents are below:(1) Based on rheology theory and fluid mechanics, the finite element model of coated co-extrusion was established by taking the advantage of the gas-assisted extrusion.Then the PTT viscoelastic constitutive equations was adopted and simulated through CFD software, the melt flow inner and outer of the die were analyzed.(2) Through numerical simulation, the influence on gas-assisted coated co-extrusion which polymer physical parameters and extrusion moulding conditions made was analysed, including the extruded flow rate, combinations of material, relaxation time, viscosity, material parameters ? and ? so on. Exactly, and the length of gas in gas-assisted coated co-extrusion was studied, the traditional coated co-extrusion and the gas-assisted coated co-extrusion were contrasted.(3) After design and processing the Y-type coated co-extrusion of gas assisted die, built a gas-assisted coated co-extrusion roof and conduct the extrusion experiments. Verify the feasibility of gas-assisted coated co-extrusion, study the influence which different process conditions made on coated co-extrusion through experiments and make suggestions for improving on the gas-assisted coated co-extrusion device.