| As a crucial link in the manufacturing process of aviation gears,heat treatment plays a great role in improving the strength,hardness and wear resistance of gears.The key point of research is to predict the important performance indexes such as hardness,microstructure,residual stress and deformation after heat treatment through numerical simulation,and optimize the process parameters to realize the controllable manufacturing of heat treatment.However,the heat treatment process of aviation gear is usually characterized by multiple process flows and complex genetic evolution among processes,which greatly increases the difficulty of predicting the performance of gear after heat treatment.Therefore,it is of great significance to establish the numerical simulation model of aviation gear heat treatment to explore the performance evolution law in the whole process of gear heat treatment,and accurately predict the performance index after heat treatment.In this paper,the aviation thin-web gear made of 9310 steel is used as the research object to carry out the following researches:(1)The thermophysical parameters,mechanical properties and transformation dynamics parameters of 9310 steel are obtained by using the material performance calculation software,including young’s modulus,Poisson’s ratio,thermal conductivity,specific heat,thermal expansion coefficient,flow stress curve,TTT curve and martensitic transformation temperature.(2)Based on the multi-field coupling theory of numerical simulation of heat treatment and the three-dimensional part structure,actual heat treatment process route,material parameters,initial and boundary conditions of heat treatment of aviation thin web gear,the professional heat treatment simulation software DANTE was used to conduct simulation calculation of gear heat treatment process.The law of phase transformation and stress evolution during quenching and the influence of cryogenic treatment and tempering process on residual stress were investigated,and the final distribution of residual stress was obtained.(3)The hardness,metallographic structure,residual stress and deformation of the gear after the actual heat treatment were detected,and the simulation results were compared with the measured results to verify the accuracy of the simulation.The results show that the calculated hardness,metallographic structure,residual stress and deformation are in good agreement with the measured results.The maximum error between the hardness value obtained by the simulation calculation and the actual measured result is 7.6%.The metallographic structure obtained by the simulation calculation and the actual measurement are both tempered martensite.The residual stress state obtained by the simulation calculation is consistent with the actual one,that is,the surfaces of the gear teeth is the same compressive stress.The deformation trend obtained by the simulation calculation is consistent with the actual measured value,and the overall state of expansion is presented.(4)The method of reducing the heat treatment deformation of aviation thin web gear is studied by changing the furnace loading method,optimizing the process parameters and combining them.Based on the principle of multi-field coupling of heat treatment,the whole process of heat treatment of 9310 steel aviation thin-web gear is simulated by using finite element software.The performance evolution law of gear during heat treatment is obtained,the hardness,microstructure distribution,residual stress and deformation of gear after heat treatment were predicted accurately,and the optimization scheme was put forward to actively suppress the deformation of gear during heat treatment.Through this research,the performance evolution law and process improvement method of the whole heat treatment process of 9310 steel thin web gear which can guide the practical engineering application are obtained. |
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