Research On Solidification Technology Of Melting And Casting Charge Based On Numerical Simulation

Compared with other charging methods,the melt-cast charging method has significant advantages.For example,it is not restricted by the shape and size of the inner cavity of the projectile,and it is easy to realize automatic production.It is currently one of the most commonly used charging methods.However,the prone to charging defects have become a bottleneck restricting the development of the molten-cast charging method.Therefore,reducing charge defects has become a research hotspot in molten cast charge.At the same time,the charge test has the disadvantages of high cost,poor consistency,complex process and low universality,making simulation technology an important method and means for charge research.The research on the solidification technology of molten cast charge through numerical simulation technology is a subject that many scholars are committed to researching,and it is of great significance to the development of ammunition and the development of weapons.In this thesis,numerical simulation is used to study the solidification technology of molten cast charge,with the purpose of reducing charge defects.Based on the study of the mechanism of charge defects,the process flow is simulated by changing the process parameters.The main research contents of this paper are as follows:(1)First,the theoretical analysis of the impact mechanism of the charge defect on the safety is carried out,and the finite element simulation method is used to establish the projectile drop test model.The Autodyn software is used to carry out the analysis of the charge with large holes,small pores and no pore defects.The numerical simulation of the drop test has obtained the cracks and the reaction degree inside the charge during the drop process.By comparing the test results of various defective charges,the mechanism of the charge defect is found,and the theory is verified at the same time.Within a certain numerical range,the smaller the defect of the charge,the better the safety of the charge.In order to reduce the defects of the charge,improve the quality of the melt-cast charge,and ensure the safety of the charge,it is necessary to improve and optimize the charge process.(2)For the optimization of the hot mandrel process,the method of numerical simulation is used to establish a three-dimensional molten cast charge model.The traditional casting process and the hot mandrel process are simulated and the simulation results are compared to verify the hot core.The mechanism of the stick process.Combining the defect generation mechanism and the improvement mechanism of the traditional hot mandrel process on the charge quality,a hot mandrel process with multi-level optimized temperature control is designed.The finite element simulation of the casting process is carried out,and the influence of the multi-level hot mandrel process on the charge quality is predicted by setting multiple sets of temperature parameters.The results show that when the temperature combination parameters are 95°C,91°C,and 86°C from outside to inside,the effect is the best and meets the expected requirements.It is concluded that the traditional hot mandrel casting process cannot change the radial solidification sequence of the grains,and shrinkage and porosity will still occur in the wide area of the chamber.The multi-layer hot mandrel process can improve the solidification sequence of the grains.Effectively prevent the appearance of shrinkage cavities and porosity.(3)For the graded casting process,the method of numerical simulation is still used.First,the molten casting charge system is modeled,the traditional casting process and the graded casting process are simulated by finite element,and the simulation results of the two are compared and analyzed.The forming mechanism of the staged casting process is obtained.Combining the defect generation mechanism and the forming mechanism of the graded casting process,a single-point multi-layer casting process is designed.And by setting nine sets of different parameters for the single-point multi-layer casting process to simulate the casting process,the results show that the staged casting process can only change the solidification sequence of the charge to a certain extent,and it is still easy to shrink on the central axis of the grain.The single-point multi-layer casting process completely changes the solidification sequence of the traditional cast charge,solidifies the charge layer by layer from bottom to top,and fundamentally prevents the shrinkage cavity and porosity defects of the charge.When the drop explosive mass is 5kg and the interval time is 400 s,the charge quality is the best.Through data fitting,the objective function of the maximum shrinkage under the constraint of temperature synchronization is obtained,and the result of charging under different process conditions can be predicted.Compared with the traditional casting process,the multi-layer hot mandrel process and the single-point multi-layer casting process have obvious advantages,and the new process can make the solidification of each part of the charge strictly follow human control to meet the needs of intelligent charge.The research results play a certain guiding role in the development of automation and intelligentization of molten cast charge.