Design And Optimization Of Double-lumen Microtubules Extrusion Die Based On Flow Balance

Multi-lumen microtubules are widely used in interventional medicine,optoelectronic communication and other fields.However,unlike ordinary extruded products,multi-lumen microtubules have complex cross-sections and large wall thickness variations,and it is quite difficult to control the melt flow balance at the die outlet during extrusion.Aiming at the problem of unbalanced flow in the design of multi-lumen microtubules die,this paper takes a double-lumen microtubules with typical uneven wall thickness as the research object,combined with extrusion mold design theory,finite element numerical simulation technology and optimal design Theoretically,the design and analysis of the double-lumen microtubules extrusion die is carried out,and the influence of the extrusion die flow channel structure on the flow balance of the multi-lumen microtubules is explored.First of all,according to the design requirements of the target product dual-lumen microtubules,combined with the design principles of the extrusion die,the traditional empirical formula is used to preliminarily design the flow channel structure of the dual-lumen microtubules extrusion die with independent air supply for each inner cavity.The shape of the die cross-section is determined by the forward extrusion simulation and pre-compensation method of ANSYS POLYFLOW software.Three-dimensional parametric modeling was carried out based on the runner structure parameters of the extrusion die obtained by the traditional empirical design formula,and the defects in the flow balance of the die runner structure designed by the traditional empirical formula design method were analyzed by finite element software.Secondly,on the basis of the die runner structure designed by the traditional empirical formula design method,combined with the optimal design theory,an optimal design method of extrusion die based on flow balance as the design objective and combined with finite element simulation analysis is proposed.The method takes the flow balance on the exit section of the double-lumen microtubules extrusion die as the objective function,the maximum pressure drop is the constraint condition,and the structural parameters of the preformed section and the blocking block are introduced as the design variables.The optimal design of the double-lumen microtubules extrusion die.The results show that after optimization,the maximum speed area on the die exit section is reduced to 1.5 mm/s,and the minimum speed area is increased to 1.0 mm/s.The objective function after optimization by finite element analysis is reduced from 1.86 before optimization to 1.28.This shows that the flow balance on the optimized die outlet section has been greatly improved.Finally,the obtained double-lumen microtubules extrusion die using traditional empirical formula design method and optimal design method is manufactured and verified and analyzed by start-up experiments.The products obtained from the double-lumen microtubules extrusion die designed by the traditional empirical formula design method have uneven wall thickness that cannot be adjusted by process parameters,the size does not meet the design requirements,and the contour is severely deformed.The orality of the crescent cavity and the circular cavity of the product obtained by the double-lumen microtubules extrusion die designed by the optimal design method is less than 5 %,and the maximum deviation of each size from the corresponding size required by the target product design is less than 0.08 mm.It is basically consistent with the design requirements of the target product in terms of dimensional accuracy and shape outline.The validity and correctness of the method are verified.