A Study On Spring-back Mechanism And Compensation Method Of Hot Die Forging Blade

The performance of the aero-engine is an important indicator of the country’s defense capabilities and technological development. Engine blade is one of the most important mechanical components in an aero-engine and it plays a key role in energy conversion. The quality of the blade has a direct effect on the performance and service life time of the aero-engine. In the hotdie forging process of blade, the existence of residual stress cause the spring-back, which leads to the deviation of the blade shape and size from the ideal design. The deviation will affect the quality of the blade.Considering the reduction of spring-back,the preform of the blade is designed. The affect of the holding time on the spring-back of the blade is analyzed. Considering the spring-back compensation of the blade, the die compensation method is used to eliminate the geometric errors. The main contents and results are as follows:Two preformed blank with different cross section is established with PRO/E. The hot-die forging process and the unloading process of preformed blank are simulated with DEFORM-3D. By comparing the temperature difference, the equivalent strain difference, the velocity field, the residual stress field and the equivalent elastic strain of the blade which are forged from the two different cross section blanks, it can be found that the blade forged by the elliptical cross section blank has the smaller spring-back. Therefore, the elliptical cross section blank is the optimal cogging mode.The affect of the holding time on the spring-back of the blade is analyzed. The results show that with the increase of the holding time, the residual stress gradually reduces, and it tends to a constant when the holding time is longer than 0.4s. Through comparing the spring-back of the different holding time, the results show that the spring-back reduces fast while the holding time is changing from 0 to 0.4s and it reduces slowly after the holding time is longer than 0.5s. Therefore, considering the production efficiency, the appropriate holding time is between 0.4-0.5s.The geometric model of the die is established based on the surface piece die model.The affect of elastic deformation of the dies on the blade quality is analyzed. The dies arecompensated with the die compensation method. The results show that after the first die compensation, the total size deviation of the blade caused by the elastic deformation of the die is 0.206 mm,which is 46% smaller, compared with thedeviation before the compensation. After the second die compensation, thetotal size deviation caused by the elastic deformation of the die is 0.058 mm, which is 85%smaller, compared with the deviation before the compensation. Therefore, the blade quality is improved through the die compensation method.