Springback Research On Aerofoil Blade In Hot Die Forging

A blade is one of the most important mechanical components in an aero-engine.However, it has characteristics of complex molding surface and very large ratio ofcross-sectional width to thickness and a certain rotational angle between eachcross-section, so the residual stress makes it the springback of the blade after the hot dieforging. The blade springback affects the accuracy of the forming blade. Therefore, ithas important theoretical significance and practical value for the development ofhigh-end manufacturing industry to study the mechanism of the blade springback, topredict the unloaded springback after the hot die forging, to analyze quantitatively theeffects of process and material parameters on the springback, and find reasonable andeffective process to control the springback for an accuracy beyond a desired range.In this thesis, taking the blade of titanium alloy into consideration, the keytechnologies of the elastic-plastic finite element simulation of the hot die forging of theblade are studied and set. A geometry model of the blade blank has been establishedusing the software Pro/E. Based on the above key technologies, an elastic-plastic finiteelement model of the hot die forging of the blade has been developed in a commercialfinite element analysis software DEFORM-3D, and the reliability of this FE-model hasbeen verified.The final forging process of the blade is simulated and the deformation laws arestudied systematically. Furthermore, the distribution laws of the residual stress areanalyzed after the forces are removed from the billet and the conclusion can be drawn as:after the final forging process of the blade, both the elastic recovery of the elasticdeformation area and the unloaded springback of the plastic deformation area occur, andthe residual stress over the blade decreases gradually. The resilience of the blade isforecasted after removing the forces and it is found that maximum elastic strain of theblade is located at the leaf area of the front blade body with the biggest springback of112μm.The influences of the forming parameters on the springback are studied and it isindicated that all the blade resilience decreases firstly and then increases with the increase of mould temperature, top die velocity and friction coefficient. Differentmaterials of titanium alloy are selected and it is found that the springback of the bladedecreases gradually with the increase of their strength coefficient. A way is taken in thisthesis and can be used to control the springback of the blade. The way is to increase theholding time. With the increase of the holding time, the maximum springbackdeformation of the blade has a great reduction first, and then a small increase, andfinally the tendency chart to be linear. Observing the entire curve, maximum springbackdeformation of the blade is calculated in33μm which can reach the precisionrequirement of the blade when the holding time for0.4s.