Optimization Of Gating System For Casting Based On Genetic Algorithm And BP Neural Network

The casting production shows that most defects in castings are born in the filling stage,mainly due to the unreasonable gating system and pouring method.It is still significant for the casting industry to explore the gating system,which can effectively avoid casting defects during the filling process of the metal liquid.In this paper,genetic algorithm and BP neural network,Pro Cast numerical simulation,A356 aluminum alloy metal mold gravity casting experiment,SEM fractography analysis,Weibull statistical analysis,and other methods were used to study the geometric characteristics of spin bait,the location of the filter,the mold design of gravity casting tension specimens,casting defects and mechanical properties of the tension specimens.The main results are as follows:（1）According to the principle of equal flow,the cross-sectional areas of the spure inlet and outlet of gravity casting tensile sample mold gating system are 75.72mm² and32.3mm²;The cross-sectional areas of the entrance and exit of the runner are 46.35mm²and 69.53mm².The cross-sectional area of the ingate is 69.53mm².The filling simulation results of Pro Cast show that the molten metal can fill the runner during the filling process of the gating system.However,the metal liquid shows obvious splashing and turbulence when entering the cavity,and the maximum velocity is 1.37m/s.（2）The simulation results of Pro Cast show that with the increase of the volume of spin bait,the flow rate of molten metal melt at the initial stage of the ingate also increases,and the maximum pressure at the inner gate also increases.The influence of the geometric characteristics of spin bait on the initial flow rate and maximum pressure of the ingate is ordered as diameter>height>distance.The maximum pressure of the gate adjacent to the spure was 0.1054Mpa,the maximum pressure away from the gate in the spure was 0.1055Mpa,the initial flow rate near the gate in the spure was 1m/s,and the initial flow rate away from the gate in the spure was 0.9m/s.The optimal geometric characteristics of spin bait were d_spin=63.04mm.h_spin=60.89mm;l_spin=82.44mm.（3）A filter is set at the runner’s entrance,and the metal liquid at the outlet surface of the filter sputters.Compared with the top of the ingate,the filter set at the bottom of the ingate can better play the role of speed reduction and flow stability.The maximum initial flow rate at the ingate is only 0.61m/s.（4）The average tensile strength and elongation of A356 casting aluminum alloy are 124.37Mpa and 5.71%under non-spining bait and filter conditions.The tension specimens’s average tensile strength and elongation are 170Mpa and 8.11%under the condition of spining bait only.The average tensile strength and elongation of tensile specimens increased to 183Mpa and 9.13%under spin bait and filter conditions.Weibull modulus of tensile strength of tensile specimens under three conditions areβ₁=6.96,β₂=17.77,andβ₃=47.6,respectively.Weibull modulus of elongation wereβ’₁=2.84,β’₂=9.38,andβ’₃=13.1,respectively.The casting defects such as shrinkage cavity,porosity,and bifilm can be effectively reduced by setting spin bait and filter simultaneously.The comprehensive mechanical properties and consistency of tensile specimens can be improved.Based on the above research,a metal mold gravity casting mold conforming to the national standard GB6397—86 tensile specimens was developed.