The Design Of Extrusion Die For Polymer Three-Lumen Microtubules And The Research Of Molding Process Conditions

Plastics microtubules has been more and more widely used in the modern medical science with their good chemical stability, durability, biological stability, detectability. Plastics microtubules has been an important component of medical products. However, it was difficult to design the extrusion die of medical plastic microtubules and research the molding process because medical plastic microtubules had complex cross-section shape, small size, high geometric accuracy, etc. Aimed at the polymer extrusion molding of three-lumen microtubules and combined with Polyflow computer numerical simulation method, three-lumen microtubules extrusion die was designed and molding processes was researched in this paper.It was summarized that the advantages and disadvantages among the Straight-through extrusion die, right angle extrusion die and lateral extrusion die. Combined with the cross section and design essentials of three-lumen microtubules products, the right-angle extrusion die structure of three-lumen microtubules which can realize independent gas injection were preliminary designed.The finite element model of three-lumen microtubules extrusion swell was established and the extrusion swell behavior of three-lumen microtubules was analyzed by Polyflow. The theory basis was found for the design of cross section. Meanwhile, in order to reduce the times of tests and save time and costs, the inverse extrusion had been used to solve the design of die for three-lumen microtubules. On this basis, the orthogonal analysis method was applied to research the effects of main structural parameters on the flow uniformity of polymer melt at the die exit and the optimum parameters of the extrusion die structure was determined.Combined with finite element method, numerical simulation was performed for the main process parameters of three-lumen microtubules extrusion forming process to research the effect of traction speed, gas injection pressure and volume flow on the cross-sectional shape precision of three-lumen microtubules products. It was found that traction speed has less effect on shape precision of products, and the gas injection pressure and volume flow affected the shape precision observably.