Safety Analysis Of Continuous Mixing Process In Co-rotating Twin Screw Mixer For Energitic Materials

Energetic materials are widely used in military,aerospace and industrial fields,which is the main source of the modern weapon system.The co-rotating twin screw has the characteristics of stable mixing,reliable operation and small mixing volume per unit time.The safety of the co-rotating twin screw mixer is significantly higher than that of the batch mixer,so it has been widely applied.Numerical simulation is used to study the safety problems of energetic materials in continuous mixing of co-rotating twin screw extruder.The static analysis of the screw mandrel is carried out by using the static structure module of Workbench software.The stress and deformation of different core mandrel under specific load constraints are analyzed,and the safety of the mandrel in the mixing process is studied in this paper.Screw elements are designed according to the meshing theory and the physical properties of energetic materials.The finite element model of the screw element flow channel is set up.The POLYFLOW software is used to simulate the flow channel.The temperature field,the pressure field and the shear stress field are analyzed,and the safety of the mixing process is compared.Based on the influence of screw elements on the safety of mixing process,a screw configuration is combined.The influence of process conditions on the safety of mixing process is also studied for this configuration.Simulation results show that:The deflection,maximum reverse angle and maximum stress value of the involute spline mandrel are relatively small,which is more safe;The safety performance of the screw element with small lead is better than that of screw element with large lead;In the four kneading block elements with different stagger angle,the kneading block elements with a stagger angle of 60 degrees have the best safety performance.With the increase of kneading disc thickness,the weighted average shear stress increased and the maximum temperature value increased,and its safety performance decreased;and the safety performance of the reversed screw element and the "S" type element is poor.When designing the screw configuration,the two components should be avoided as much as possible;With the increase of speed,the pressure,shear stress and temperature in the screw channel are all rising,and the safety is obviously decreased.The high screw speed should not be used when mixing the energetic material;Increasing the feed amount of the inlet,the temperature and shear stress in the flow channel change little,and the pressure between the inlet and outlet becomes smaller.But due to the increase in the amount of feed,the possibility of friction between solid particles,and energetic materials between barrel and screws increases Therefore,production is usually based on the mode of lower yield or feeding rate in actual production.