Numerical Simulation Of Superalloy Blade During Cold Roll Forming And Study Of Edge Tearing Damage

Cold roll forming technology is a new technology in the field of rolling.The production has stable working process,less process with minimal cost,satisfactory work-piece mechanical properties and high production efficiency.Therefore,it has been part of the development trends of aviation blade manufacturing.However,it will appear defects of lateral bending,groove is sometimes difficult to fill,surface distortion,edge tearing phenomenon.So it is necessary to understand the cold roll forming laws and forming mechanism of blade.This paper establishes a numerical simulation platform in the software DEFORM-3D to research GH4169 alloy blade of cold roll forming laws and study of the edge tearing.At the beginning of the paper,it chooses the Yoshida-Uemori constitutive model for superalloy blade during cold rolling process.Then the secondary development technology is carried out and the constitutive model is added to the flow stress in user subroutine.The numerical simulation of cold roll forming is carried out with the developed constitutive model.Secondly,in order to an accurate study of the blade edge tearing,this paper analyses eight kinds of ductile fracture criterion.The mechanical properties experiment and the simulation of GH4169 alloy are grouped together to obtain the corresponding parameters in fracture criterion formula.The ductile fracture criterion that is the most suitable for cold roll forming is obtained by comparing difference and coefficient of variation.The normalized GH4169 material specific threshold value of this damage factor is 0.9095.Then,rolling theory is applied to analyze equivalent stress distribution,equivalent strain distribution,rolling force,velocity field and other parameters in the rolling process.The laws of cold roll forming are preliminaries revealed.Several simulations are made to study the influence of friction coefficient,roll speed and the magnitude of thickness reduction on the blade forming.The results show that the slip increases slightly as friction coefficient increases,and the increase of friction coefficient is not conducive to the formation of broadening.The optimization parameter with rolling speed of 0.8rad/s is helpful for ideal broadening.The thickness reduction becomes the primary factor to be adapted to limit the edge tearing.The research provided the theoretical basis for the optimum design of the blade forging and the roller die rolling.Finally,basing on the ductile fracture criteria,this paper analyzes the impact of friction coefficient,the rolling speed and the magnitude of thickness reduction on the edge tearing of blade.The results show that the blade thickness variation is the main factor that affects the edge tearing,and optimized parameters range is 0-0.10mm.Meanwhile,entire process from the generation and development of visible damage to the occurrence of fracture has been simulated,which provided the forming mechanism of the edge tearing of the blade and the prevention of edge tearing.