Study On Control Of Roughness And Residual Stress Of Flexible Polishing For Blisk Blade

The blisk is widely used in aviation,aerospace,navigation,energy and other fields,the surface integrity of it has an important impact on the working performance and working life of related components.Surface roughness is closely related to the matching properties,wear resistance,fatigue strength,contact stiffness,vibration and noise of mechanical parts,and has an important impact on the service life and reliability of mechanical products.Residual stress affects the structure’s fatigue strength,resistance to brittle fracture,resistance to stress corrosion cracking and high temperature creep cracking,which are two key factors that affect surface integrity.In this paper,the five-axis CNC machine is used as the polishing equipment,and the flexible abrasive tool of the flap disc is used as the polishing tool.The self-adaptive polishing process of the TC17 titanium alloy blisk is studied to improve the polishing surface roughness and residual stress.In order to improve the surface roughness and residual stress of the blisk after flexible polishing.In this paper,the main problems that affect the roughness and residual stress of the polished surface is analyzed.Analytical methods such as theoretical calculation,experiment and simulation are used to improve the polishing process and improve the surface integrity of the blisk.The main research contents and results of the article are as follows.(1)The structure and basic working principle of the flexible and adaptive polishing of the experimental platform are analyzed,and the abrasive cutting model of flap disc is established.The theoretical calculation of the effect of elastic deformation on the contact length between the flap disc and the blade body of the blisk.The effective number of abrasive particles per unit length are analyzed.The theoretical modeling and analysis of the polishing force and polishing temperature during the polishing process are carried out respectively.(2)Based on the distribution characteristics of the knife marks on the blade surface and the abrasive wear on the surface of the flap disc,the phenomenon leading to the knife marks during the polishing process of the flap disc is preliminary analyzed.The theory and simulation analysis of the force deformation of the blade are carried out.And the polishing path of the flap disc is revised and verified by experiments.Take a single row of abrasive grains and make a theoretical calculation of the fore on the middle and edge abrasive grains during the polishing process.The stress on the single row of abrasive grains in different parts are analyzed.The shape of the flap disc is optimized to improve the phenomenon of knife marks,reduce the roughness and improve the consistency of the polishing surface.(3)Through theoretical analysis and finite element analysis,the relationship between the polishing pressure of the flap disc and the roughness is preliminarily determined.According to the polishing principle,the influence of process parameters on polishing pressure and roughness is analyzed.A reasonable prediction model is selected.A test plan is formulated,The prediction model of polishing pressure and roughness during the polishing process with different size of flap disc is obtained,and the accuracy of the model is analyzed.Then the influence of process parameters on polishing pressure and roughness is analyzed by response surface method.Then the effect of polishing pressure and roughness is analyzed.The polishing test is carried out according to the optimal results of the prediction model,which proved that choosing a reasonable polishing pressure can improve the polishing efficiency and improve the roughness of the polished surface.(4)The two-stage parameter method is used to study the influence of process parameters on the reason factors(polishing force and polishing temperature),the reason factors on the residual stress and the process parameters on the residual stress.The gray correlation theory is used to optimize the process parameters and the reason factors,and the grey correlation analysis of the process parameters to the reason factors and the optimization analysis results of the process parameters to the residual stress are compared and analyzed.Experiments show that polishing with optimized process parameters can effectively improve the residual stress on the blade surface.(5)A single factor experiment combined with the surface micro-topography is used to analyze the influence of process parameters on roughness and residual stress.The orthogonal test of the roughness and residual stress of the polished blade is designed,and the prediction models of roughness and residual stress are established respectively.Sensitivity analysis and stability region division for roughness and residual stress according to prediction model,the optimization model is established by using gray correlation analysis and equal weight correlation analysis.Combined with the final optimization interval obtained by sensitivity analysis,the results obtained by the equal weight correlation optimization method and the gray correlation optimization method are tested and compared.And the final optimal method is determined.(6)Through the study of flexible adaptive polishing of TC17 engine blades,the influence of process parameters on polishing force and polishing temperature,the process parameters on surface roughness are analyzed,and the debris shape under different process parameters are analyzed.Combining the relationship between polishing force,polishing temperature and residual stress,the influence of process parameters on the residual stress of the polished surface is analyzed.By comparing the variation of residual stress with depth after milling and polishing,the microstructure of the modified layer after milling and polishing is analyzed.Through reasonable polishing parameters,the blade surface integrity is effectively improved.