Study On The Quick Water Cooling Design Method Of Permanent Mold Casting

The permanent mold casting,due to its long service life of the mold,fast cooling speed,and can make the casting grain refinement and dense structure,is especially suitable for such as automobile aluminum alloy engine cylinder head,automobile wheel hub,torsion bar bracket,steering knuckle Automatic production of casting products in large quantities.However,in actual production,the multi-cycle casting process will cause the metal mold to continuously absorb the heat released by the casting during the filling and solidification stage,resulting in the continuous increase of mold temperature,leading to longer and longer time for solidification and cooling of the casting,and finally affects the casting Quality and production rhythm.Therefore,on the basis of meeting product quality and process yield,a reasonable and efficient water cooling system must be designed to ensure the stability of the mold temperature field and shorten the solidification time of the casting.However,the traditional water cooling system design method is more cumbersome and cannot accurately calculate the cooling water volume,which has certain shortcomings.This paper has done the following research work for this purpose:Based on the basic theory of heat transfer and traditional metal mold cooling channel design,after considering the casting hot spots and mold modulus calculation,a solution equation between the cooling water volume and the casting modulus is obtained:V_cw=k((M_C)/(M_m))V_c.It can be seen from the equation that the volume of the cooling water is directly proportional to the casting modulus and the volume of the casting hot zone affected by the cooling water,and inversely proportional to the die modulus.The larger the hot spot of the casting,the greater the amount of cooling required;the thicker the mold,the smaller the corresponding cooling water.The cooling coefficientk k=(k₁k₂?_c(c_c?T_c+L))/(c_cw?_cw?T_cw) is mainly affected by factors such as casting material and mold material.Using ProCAST software to study and analyze the changes in the solidification state of aluminum alloy castings under different mold wall thicknesses,it is found the time that the casting is superheating does not change with the change of the thickness of the metal mold;while the crystallization time of the casting decreases with the increase of the metal mold wall thickness,But it will no longer change when it is reduced to a certain fixed limit value.It means that the mold is affected by the alloy liquid and there is a limit range,and the mold beyond this part of the range will basically not be affected by the change of heat,that is,the metal mold has an economical wall thickness,and the mold beyond this economical wall thickness will not affect the casting Solidified state.For metal mold casting with A356aluminum alloy as the casting material,H13 steel as the mold material,and the initial mold temperature set to 250?,the economical wall thickness is twice the casting wall thickness.Taking A356 aluminum alloy torsion bar bracket and commercial wheel hub as examples,based on numerical simulation,different metal mold casting methods are used to verify the accuracy of the water cooling equation.After splitting and selecting the four hot spots where the typical wall thickness of the casting changes,the center of the hot spot is selected as the temperature measurement point,and the ProCAST software is used to monitor the casting and the mold at the center of the hot spot during the multi-cycle casting process without water cooling channels.The temperature field changes,combined with the actual casting model and water cooling to solve the equation,calculate the cooling water volume and water cooling channel parameters that need to be added to the hot section of the casting.After modifying the model,monitor the temperature field changes of the casting and mold at the center of the hot section after adding a water-cooling channel.Comparative analysis of the temperature field changes of the castings and molds poured in 10 cycles in the two simulation results.It is found that after the 6th cycle after the water cooling channel is added,the temperature field is basically the same as the previous cycle,and the solidification time of the casting in the selected area It is shortened and kept stable,and the mold and the casting are in a state of thermal equilibrium,which plays a role in stabilizing heat dissipation,which verifies the accuracy of the equation for the cooling water volume.