Research On Computational Model And Simulation Analysis Of Sand Shooting Process

Sand shooting process is the key step of sand core making,which can determine the final quality of sand core.The simulation analysis of sand shooting process is of great significance to optimize the sand core production process,improve the quality of sand core and improve the production efficiency.Computational particle and fluid method Dynamics(CPFD)has been used to simulate the sand shooting process due to its high computational efficiency and accuracy,but the key model describing the force on particles in this method has never been studied;the coupling of drag model and CPFD method represents the momentum transfer between two phases,which affects the effect of gas on particles in the sand shooting process and directly determines the accuracy of simulation results Real drag models are rarely reported.In this paper,the CPFD model and the drag model are systematically studied,and the influence of model parameters on the sand flow process is analyzed.The simulation parameters and drag model suitable for sand shooting process are determined,and the sand filling process of actual parts is analyzed.The improvement measures for optimizing the quality of sand core are put forward.The main contents are as follows:(1)Based on the free fall experiment of particles,the normal stress model of particles,the momentum retention rate of particle wall and the maximum momentum redirection of particles in CPFD method are analyzed in detail.The rules and reasons of these models affecting the sand flow are studied,and the simulation parameters suitable for sand shooting process are determined.Three drag models,Ergun,WenyuErgun and EMMS,are used to simulate the sand injection filling process.Combined with the sand injection experiment results,the influence of the three drag models on the sand injection process is studied.The results show that the EMMS drag model is more accurate.(2)The sand flow behavior of the test piece is tested and simulated,and the influence of sand height on sand shooting process,the formation of sand perforation,the formation of "dead zone" and the influence law and mechanism of multiple sand shooting are analyzed.(3)The sand shooting filling process of actual parts(Handle and Circle workpiece)in the factory is simulated,and the causes of defects are analyzed.The solutions with strong operability are provided for engineering parts from adjusting the structure of sand shooting barrel,increasing sand shooting times,adjusting exhaust conditions,increasing sand shooting pressure,etc.In this paper,the calculation model of sand shooting process and the filling process of actual parts are studied.The research results can provide a new idea for the research of CPFD method and drag model,and provide an important reference for the actual production of the factory.