The Theoretical Study On Forming Process In Rubber Tire Co-Extrusion And Optimal Design Of Die

With the rapid development of automotive industry in domestic and foreign markets, the quality of rubber tire products are facing increasingly high requirements and this requires the products forming with high precision in co-extrusion process. As the forming process of tire products usually with high technical requirements and difficult to produce, it has got more and more attention in the field of rubber tire forming processing, especially for co-extrusion.Based on the analysis of the simulation to the co-extrusion Die, the impact of flow channel structures and working conditions has been studied. The rubber materials belong to linear flexible polymers which rheological properties will lead to the instability flow in the channel and impact the quality of final product. At this time, the damping block in the flow channel play a regulation role which shape and position can directly affect the uniformity of the flow and generated a certain pressure changing in flow channel. In the processing of co-extrusion, the factors of flow rate ratio, physical properties of the material and the angular distribution of extrusion will also affect the uniformity of co-extrusion and the interface fluctuation. In this paper, finite element methods were used to study the flow distribution and the interface. The main tasks are as follows:1. Typical flow channel of the Extrusion Die has been classified and finite element software Fluent was used to simulate the polymer flow state in the channel. Then, structure of damping block and stereotypes length have been analyzed through the simulation results to study the effect on flow distribution. Finally, by means of orthogonal experiment and numerical calculation, the relationship between parameters were obtained.2. The mechanism of co-extrusion has been studied and finite element software Polyflow was also used to simulate the stability of co-extrusion. According to simulation results, the effects of geometric and process parameters were studied. The mechanism of composite interface has also been studied to analyze the distribution and fluctuation of interface. Proposed some optimal suggestions to improve the composite flow channel.3.According to the specific flow channel simulation, the geometric structures has been optimized and the results are applied to the practical flow model. By means of experiments to get the actual flow distribution of the rubber material and to compare the actual flow distribution with theoretical simulation. Based on the experiments data to verify the theoretical research and draw the conclusions which can be used to improve the flow channel of extrusion Die.