Research On Machining Allowance Design And Deformation Prediction Of 3D Printed Titanium Alloy Thin-walled Parts

Titanium alloy thin-walled parts are widely used in aerospace field,such parts are often complicated in structure and the traditional processing methods have high material removal rate,low efficiency,high cost.Laser selective melting(SLM),as a new material saving manufacturing technology,provides a new technical way for the high-quality blank manufacturing of titanium alloy thin-walled parts.However,the dimensional accuracy and surface quality of SLM-parts can not meet the requirements directly,so secondary processing is needed.In this paper,the secondary processing of SLM titanium alloy thin-walled parts is studied from the aspects of processing deformation and determination of dimensional allowance,which provides theoretical basis and common technical support for the high-precision integrated manufacturing of such SLM titanium alloy complex thin-walled parts.The specific research contents are as follows:(1)Based on ANSYS,this paper explores the key technology of machining deformation simulation of SLM forming titanium alloy thin-walled parts,studies the influence of different size allowance and its distribution on machining elastic deformation,and lays a foundation for optimization of allowance allocation strategy.(2)Aiming at the optimal allocation of machining allowance,a mathematical model for predicting the milling deformation of thin-walled parts based on Rayleigh-Ritz energy solution is established.Based on the mathematical model,a discrete allowance volume element design idea is proposed and the non-uniform allowance design of workpieces is completed.The correctness of the non-uniform allowance distribution strategy is verified by the comparative test of workpieces with different allowance distribution strategies.The results show that the surface machining error of the workpiece is the better,the range of error distribution is 23.6% of the traditional uniform allowance strategy,and the average machining error of the cantilever end with the largest machining deformation is only 37.41%,54.98%and 74.85% of the other three allowance design strategies.(3)The SLM forming experiment of thin-walled titanium alloy parts is completed,and the influence of different allowance distribution strategies on the forming accuracy of thin-walled titanium alloy parts is studied;the difference of residual stress distribution between the SLM and the common titanium alloy thin-walled parts before and after machining is studied;from the perspective of residual stress,the deformation mechanism of SLM forming titanium alloy thin-walled parts is studied and the maximum machining deformation is reduced by 84.8% by symmetrical milling.(4)Taking SLM forming titanium alloy cantilever blade as the application object,based on the non-uniform allowance design strategy proposed in this paper,the allowance design is completed,and the simulation prediction of thin-walled workpiece machining deformation under the condition of five axis linkage machining is carried out,and the effectiveness of the non-uniform allowance allocation strategy proposed in this paper for the deformation control of SLM forming titanium alloy complex curved thin-walled workpiece machining is verified through five axis machining test.The maximum machining errors of the basin and back are988)and 1048),and the optimization effect is over 50%.