Numerical Analysis And Experimental Study Of Polymer Micro Extrusion Flow

With the development of mico/nano science technology, product gradually develops into the direction of miniaturization, micromation and lightweight. The traditional plastic extrusion technology is progressing in the direction of micromation. So, the micro-extrusion technology has been produced. Micro-section plastic products using micro-extrusion technology such as intervention catheter, a new type of plastic optical fiber, automobile oil and gas pipe are widely used in the field of iatrology, telecommunication and automobile. As the flow state of polymers flowing in microchannel is different from that in traditional macro-channel, the study on simulation and test of polymer melts flowing process during micro-extrusion has great theoretical significance and applied value for the rheological design of micro-extrusion die.Firstly, combining the polymer rheological testing theory with micro-machining technology, the viscosity and wall slip of polymers under micro scale effect during the process of micro-extrusion are investigated. According to the result, the unknown parameters of Carreau viscosity model and Navier wall slip model are determined which provides the theoretical foundation for numerical analysis of micro extrusion.Secondly, regarding the flowing process of single cavity extrusion as the research content, designing the structure of die parameters according to the theory of extrusion die, and making use of the viscosity model and wall slip model in the condition of micro scale effect, the data of single cavity extrusion process is analyzed. According to the results of data analysis, the parameters of die's structure are corrected; the single cavity extrusion die is designed and fabricated; and the experiment with single cavity extrusion die is carried on. Besides, the experience about the design of multi-cavity extrusion die and experiments is accumulated.At last, regarding the flowing process of double cavities as the research object, the orthogonal analysis methodology is adopted to study the effects of dividing angle, the compression ratio, compressed angle and the length of center feeding zone which are in the structural parameters of double cavities extrusion die, on the flow uniformity. The results of range analysis show that, dividing angle has notable effects on flow uniformity, and the length of center feeding zone and compressed angle have some effects on flow uniformity, and also, the compression ratio has few effects on flow uniformity. From all above, the structural parameters of extrusion die's channel are settled according to the experimental results of orthogonal experiment. As a result, double cavities extrusion die is designed, and the structural parameters of double cavities extrusion die' channel are reasonable, which is proved by the experimental results of extrusion test.