Design And Optimization Of Die-Casting Mould Gating System Of Aluminum Alloy Water Pump Base And Insert With Conformal Cooling Channels

With the concept of low carbon and environmental protection,the potential of automobile lightweight in energy saving and emission reduction has been deeply explored.The use of die-cast aluminum alloy parts in automobiles can achieve a good lightweight,and die-cast aluminum alloy parts are widely used in automobiles.Reasonable die casting mold design is the key to ensure casting quality.In order to solve the die casting mold design problem of complex aluminum alloy water pump base,this topic is based on die casting mold design experience criteria,Pro CAST numerical simulation and response surface experiment to study the gating system of complex die casting aluminum alloy die casting mold and the design and optimization of insert conformal cooling channels.Specific research contents are as follows:Firstly,the cross-sectional area of the inner gate was calculated according to the structure of the pump seat and the traditional die casting design method.Four inner gate were designed according to the structure of the pump seat,and the cross-sectional area of the inner gate was 246.2mm~2.The corresponding direct runner,cross runner and overflow groove were preliminarily designed.Secondly,the mold locking force was calculated according to the empirical formula,and the Haitian HDC400 die casting machine was selected according to the locking force.In view of the high metal liquid temperature near the gate in the deep cavity at the top of the pump base,the casting was easy to cause tension defects and erosion damage to the insert,and the conformal cooling channels was designed inside the insert.Then,the die casting process of the pump base is simulated based on Pro CAST to verify the rationality of the pouring system and the conformal cooling channels design of the insert.Furthermore,the pouring system is improved according to the simulation results,and the left inner gate is divided into four by two,which increases the flow rate and hydraulic pressure of the side inner gate,thus making the volume distribution of the metal liquid flowing into each inner gate more uniform.The uniform filling of the pump seat is basically realized.Casting solidification time is reduced from 21.1s to16.3s by 4.8s(22.75%).The shrinkage cavity volume decreased from 0.638cm~3to0.466cm~3by 26.91%.It is not difficult to see that the rationality and scientific nature of the scheme to improve the pouring system has been further verified.Thirdly,in order to obtain the more reasonable die casting process parameters,response surface experiments were carried out in this thesis to study the influence rule of different die casting process parameters on the die casting process of water pump seat.On this basis,a reliable mathematical model was established for the solidification time and shrinkage cavity volume of water pump seat die casting,and the optimal process parameters were obtained by optimizing the module of Design-Expert software:Mold preheating temperature 220℃,liquid aluminum temperature 630℃,piston speed3m/s.Finally,based on the optimal process parameters,the water pump base die casting production,die casting product surface clean,no flow marks,cracks,undercasting,strain and other defects;No obvious shrinkage porosity,shrinkage porosity,porosity and other defects were detected by X-ray.The castings have good internal and external quality,and the local grain size can reach grade 4.The tensile specimens were prepared,and the average tensile strength and yield strength were 253.7MPa and 120.3MPa,respectively.The average microhardness is 96.9HV at the thick wall and 99.1HV at the thin wall.The hardness of the ADC12 aluminum alloy water pump base is not less than85HV,so the hardness of the water pump base die-casting parts meets the requirements of the product.