| In this paper,the optimization study of the intermeshing co-rotating twin-screw extruder is carried out,and the method of combining mechanical design theory,Solid Works three-dimensional modeling,ANSYS simulation,neural network and prototype experiment is used to explore the extrusion process,so that it can be used for granulation production of polylactic acid/starch degradation materials.The research content and conclusions are as follows:(1)The research status and development trend of existing biodegradable materials and twin-screw extruders at home and abroad are reviewed.Through the study of the twin-screw extruder structure and screw meshing principle,a new type of eccentric triangular prism element is proposed;through the design optimization of the transmission system,screw and barrel elements,extrusion device and feeding mechanism,the parts are completed Three-dimensional modeling work and assembly and debugging of the whole machine.(2)Through the comparative analysis of the steady-state flow field of the triangular prism element and the different screw combinations of the homogenization section,the distribution of the velocity and pressure field was discussed;the finite element model of a single barrel was established,and the barrel was preheated.The heating condition in the water cooling stage,and the temperature change around the monitoring point of the barrel are thermally analyzed.(3)Carry out prototype trial production experiment,firstly find suitable process conditions through single factor and orthogonal experiment,and study the influence of three process parameters of feeding speed,screw speed and conveyor speed on pelletizing and extrusion;secondly The screw speed,feeding speed,die melt pressure and temperature data of different temperature control zones are collected through experiments,and the melt pressure is analyzed using BP,RBF,GRNN and Elman neural network.In summary,the paper optimized and improved the twin-screw extruder.Through the flow field simulation of the screw,the mixing effect of the eccentric triangular prism element is stronger than that of the non-eccentric element,and the SE72+SE36 screw combination has higher pressure build-up ability;through the thermal analysis of the barrel,it is concluded that the temperature at the water hole of the barrel is large in the circumferential direction,and the temperature monitoring position should not be selected near the sharp corner of the barrel;finally,a better range of operating parameters is obtained through experiments: Screw speed 260-340r/min,feeding speed 30-35r/min,conveyor speed 60-65r/min,and get the primary and secondary relationship that affects pelletizing and extrusion: conveyor speed>screw speed> feeding speed;Through the analysis of the melt pressure,it is found that the four models can be applied to the melt pressure analysis,but the accuracy and precision of the analysis of the melt pressure of the Elman neural network is higher than that of the other three models,which can be better applied The preparation process of polylactic acid/starch blends. |
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