| Casting aluminum alloy wheel has the advantages of light weight and high strength,diverse shapes,convenient molding and easy mass production.It is of great significance for automobile lightweight,energy saving and emission reduction and improving handling performance,and has been widely accepted and recognized by the automotive industry at home and abroad.At present,T6 heat treatment is widely used in the industry to realize the comprehensive control of wheel mechanical properties.However,the reduction of structural stiffness caused by the non-uniform topology and lightweight of the wheel aggravate the deformation of the wheel heat treatment process.This method greatly increases the input of raw materials,the production cost is high and the energy consumption is large.How to realize the precise control of wheel quenching deformation has become the focus of industry experts.In order to solve the above problems,this paper aims to study a new technology of quenching deformation control of lightweight casting aluminum alloy wheels.The main research work includes:(1)The deformation control strategy of spray and spray + submersion water compound graded quenching process is innovated.Based on Workbench,a thermo-fluid-solid multiphase flow coupling model was established to analyze the gas-liquid phase change,heat transfer and quenching deformation characteristics of the wheel in the process of direct water injection.The results show that the heat transfer characteristics of the wheel surface are affected by the wheel structure,the quenching liquid flow field and the gas-liquid phase transition.There are a large number of uneven heat transfer areas in the outer rim and spokes,which affect the overall deformation characteristics.Affected by the spokes structure,the maximum deformation occurs at the outermost edge end face of the wheel.The temperature field,stress field and quenching deformation characteristics were compared by simulating the process of spraying for 10 seconds + immersion into water,and the feasibility of deformation control by spraying for 10 seconds was initially confirmed.(2)A high-precision detection device for wheel flange is independently developed,and a deformation detection algorithm based on Fourier transform is developed,which has the best detection accuracy with the coordinate measuring machine.The 3D geometric contour error is only ±5μm,which can be used for fast online detection of the axial deformation of the wheel flange end face.The deformation of the heat treated wheel was detected and characterized by a commercially mature handheld 3D laser scanner and a coordinate measuring machine,and the deformation characteristics of the outer rim,the rim and the spoke-wheel center were systematically studied.(3)A graded and sub-zone composite quenching experimental platform was independently built to meet the field production conditions and technical requirements,and the deformation characteristics of the outer rim under different quenching conditions(spray+ immersion water and spray + immersion water)were tested.Spraying 15s+ immersed water can effectively reduce the influence of spokes structural stiffness on the overall deformation characteristics of the wheel,and the maximum deformation reduction of the outer rim is 41.5 %.At the same time,the mechanical properties and hardness indexes of the typical test positions of the wheels after heat treatment under the condition of spray 15s+immersion quenching meet the requirements of the national standard.(4)Under the new process of spray 15s+ immersion quenching,the dynamic and static balance detection of the finished wheel,3D contour scanning,the appearance measurement of the wide and narrow sides of the finished car,the mechanical performance test and the bench durability and strength test were completed.The test results show that the average improvement of the outer dynamic balance is 43 %,the average improvement of the static balance is 47 %.The deformation of the casting surface near the outer flange is improved by about 0.2mm.The average improvement of width and narrow edge index was 18.4 %.The bending fatigue test,radial fatigue test,13° impact test and biaxial fatigue test are qualified.The results of 90° impact high energy test show that the deformation of the finished wheel under spray + immersion quenching process is about 4.2 % higher than that under immersion quenching process,still qualified.The mechanical properties of each characteristic area meet the technical requirements. |
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