Research On The Sub-layer Grinding Residual Stress Regulation Based On The Induction Heating With Magnetic Flux Concentrator

Inconel 718 superalloy, poesses high temperature strength and corrosion resistance, is widely applied as the high temperature components of the gas turbine engine in the aerospace manufacturing industry. Grinding is generally applied as the final process in order to acquire a good size precision and high surface quality. However, the large residual tensile stress is often obtained in the grinding surface, which is harmful to the fatigue strength and life of the component. It is necessary to ensure the grinding surface formed smaller tensile stress even compressive stress.The paper firstly introduces the application background of Inconel718 and the current status of processing technology. It is suggested that the problem is the active control of the grinding surface residual stress. The residual grinding stress formation reason, current status of research on improving the method and measurement techniques are reviewed and summarized. According to the principle of reducing the grinding temperature gradient, this paper put forward a new type of composite grinding process, in which a heat source is embedded within the workpiece by the good control of the induction heating process and finally achieve the active control of residual stress.By analyzing the mechanism of implanting a subsurface heat source to control the distribution of residual stress, the right subsurface temperature distribution target is suggested. By introducing induction heating without contact and surface cooling technique, a heat source is implanted into the subsurface of the workpiece. This paper analyzes the function mechanism of the strengthed induction heating and concentrator in electromagnetic heat conversion process. Based on the simulation and experimental system, the influence of the process parameters in the induction heating process is studied, and the mathematical model for the prediction of the temperature field distribution is established. Through the example analysis and experimental verification, it is proved that the temperature control model established can effectively realize the temperature field.Combined with the induction heating model and the suitable grinding heat analysis model, the finite element simulation model of the residual stress process system is established. The new process control model can reach to the calculation of the temperature field and the stress field in the workpiece layer. In order to achieve the active control of the final residual stress distribution state, the mathematics model based on the response surface technology between the residual stress and the four important process parameters is established. On this basis, the method of the active control of the residual stress and the optimization of the process parameters are analyzed.The experimental platform of the new induction heating assisted grinding system is established, and a large number of experimental studies are carried on. The results show that, compared with ordinary grinding, the surface residual stress under the new technology has been improved a lot, which further verifies the proposed regulation mechanism of residual stress through temperature gradient in this paper is useful. At the same time, the influence of the new process parameters on the final residual stress distribution is studied. Combined with the results of the simulation and experiment analysis, the ultimate realization of active control under the new technology of residual stress is achieved.