Die Casting Process Optimization And Mold Design For Automotive Shell Castings

In the lightweight technology of automobile parts,the selection of aluminium alloy parts has always occupied an important position.In this paper,the aluminum alloy shell castings are taken as the research object,and the die casting method is adopted.The simulation software is used to visualize the die casting process parameters,and the simulation results are compared and adjusted with the actual production experiments,so as to achieve the guiding role for the actual production of die casting.The die-casting technology and die design method of shell castings were revealed by taking the die-casting of specific aluminum alloy shell as the research object.Firstly,according to the wall thickness characteristics and structure shape of castings,the initial scheme of pouring and overflow system is designed.Thermodynamic and hydrodynamic simulation of the initial design scheme is carried out by using ProCAST software.The simulation results show that there is a serious internal entrainment phenomenon in the initial design scheme during filling.In order to eliminate the entrainment phenomenon,an overflow groove connecting four walls was added to the top of the castings to enhance the internal gas flow.The optimized design scheme is further simulated by ProCAST.The simulation results show that the original serious internal entrainment phenomenon has been eliminated.Secondly,the die-casting die for the shell was designed according to the casting shape and casting scheme.In order to solve the demoulding problem in two difficult parting areas,the required core-pulling force and distance are calculated respectively,and the corresponding core-pulling mechanism is designed according to the calculation results.By adding inserts and core pulling mechanism,the mold cavity is modeled.In addition,the solidification temperature field of the die was also studied.The thermal balance of the die was improved by the design of point cooling water channel.After the die design is completed,the above optimized casting scheme is tested by trial production.X-ray flaw detection was carried out on the castings obtained from the model test,and the results showed that there was an obvious shrinkage.By analyzing the shrinkage defect of castings,it is found that the original "flow method" simulation is not suitable for actual production.Although the "flow method" can effectively simulate the flow state of liquid metal in the cavity,it ignores the state of liquid metal before entering the runner from the chamber,which results in errors between simulation and practice.The first injection velocity of die casting process parameters corresponds to the stage of filling chamber with liquid metal,which shows that the "flow method" simulation has limitations.In order to solve this problem,the simulation model is built by the method of pressing chamber punch pushing metal liquid,which makes the simulation highly coincide with the actual production process.Finally,the improved simulation model was used to carry out orthogonal experiments on the specific die casting process parameters through the ProCAST simulation software.Based on the simulation results,the visual analysis of die casting process parameters is carried out.The optimized die casting process parameters are as follows: die casting temperature 650 C,first stage die casting speed 0.2m/s,high and low speed switching position 320mm(punch stroke)and second stage die casting speed2m/s.The new X-ray flaw detection results show that the original shrinkage defect can be effectively eliminated by applying the above parameters to the production test.