| Blisk is a key component of the new aero-engine for structure innovation and technological leapfrogging,and the surface quality and profile accuracy of the leading and trailing edges(LTE)of blisk blade have important effects on the aerodynamic performance and service life of the aero-engine.At present,the most effective machining method for blisk is multi-axis and line by line milling using ball-end mill in domestic,which leads to evident surface corrugation and dissatisfy the usage requirements.Therefore,the polishing process is an essential for blisk to remove the milling marks and improve the surface quality.Although many researches on the LTE polishing has been done at home,most of them are still in the experimental stage.Now the polishing method for LTE mainly depends on the manual method,which not only has the shortage of high labor intensity,poor working conditions and low efficiency,but also easily cause the surface burn.More than that,surface integrity,profile accuracy and the consistency are hard to guarantee.Thus,it has great theoretical and practical significance to study the automatic polishing technologies of LTE for establishing the precise and efficient polishing methods and revealing the polishing mechanism.LTE of blisk blade has the characteristics of thin thickness,changeful curvature and difficult-to-machine materials.In the automatic polishing process,there are many parameters,including the machining parameters(spindle speed,polishing force,feed rate,etc.),(spindle speed,polishing force,feed rate,etc.).If the polishing parameters are selected unsuitably,the surface integrity will be affected,and the profile accuracy will become poor,even the surface burning or damage will be caused.Based on this,the flexible polishing technology,polishing process control and surface integrity predictive control of five-axis abrasive belt flap wheel(ABFW)are deeply study in this paper.The main works of this research are as follows:(1)The five-axis ABFW polishing method for blisk blade LTE is proposed.Based on the analysis of problems existing in LTE polishing,combining with the characteristics of five-axis ABFW polishing,the five-axis ABFW polishing method for blade LTE is proposed by comparison with other polishing methods.After that,the structure and technical parameters of the five-axis polishing machine are explained in detail,which builds a foundation for the studies of the proposed polishing method.(2)The relationship model between polishing force and contact displacement is established.According to the distribution model of ABFW particles,the microscopic elastoplastic contact model between particle and workpiece is studied.Through the contrast of elastoplastic deformations and polynomial approximation method,the relationship model between polishing force and contact displacement is established.Then,the maximal deformation of ABFW is obtained with the stability of polishing force for the principle.After that,the correctness of relationship model is proved by polishing force experiment.And on this basis,the regression prediction model of polishing force is developed by the orthogonal experimental results,which lays the foundation for the realization of the polishing process control based polishing force control.(3)The models of surface roughness(SR)and material removal rate(MRR)are established of ABFW polishing.According to the definition of SR and the Rayleigh probability density function of undeformed chip thickness,the SR model is established.And the factors and their influence on SR are studied by simulating analysis,laying the foundation for the control and prediction of SR.After that,based on the Hertz elastic contact theory,the distribution functions of polishing pressure and cutting speed are gotten,and the MRR model is established using Preston equation.And then the factors and rules influencing MRR are analyzed,which provides the basis for the realization of constant MRR polishing and the improvement of surface integrity consistency and polishing efficiency.(4)Parameters optimization of LTE polishing by five-axis ABFW polishing method is studied.Firstly,according to the simulation results of SR and MRR models,the key polishing parameters are determined.Secondly,the LTE polishing experiments are designed with response surface method,and the optimization forecasting model of SR is developed through the regressive analysis on the experimental results.Then the optimal parametric field is obtained by the analysis of contour and 3D surface plots,and it is verified through the experiment.Furthermore,the orthogonal LTE polishing experiments are designed.Two objectives is transformed into single objective problem based on the grey relational analysis,and the influence weight of surface and material rate on the grey relational grade(GRG)are calculated.By the means of regression analysis of the experimental data,the second order prediction model of GRG is developed.And the effects of polishing parameters on SR and MRR are analyzed.Finally,the optimum combination of polishing parameters which can realize the holistic optimization of SR and MRR is obtained with response surface methodology based on maximum GRG,and its effectiveness is also verified by experiments.(5)The polishing experiments are carried out to verify the effectiveness of the proposed method.Through the comparison of polishing and milling,the path direction,step length,row space and tool orientation vector are studied by taking the standards of non-interference,stable quality and high efficiency.And the polishing path is obtained with section plane method.Finally,the polishing experiments are carried out on a compressor of turbine engine blisk,the test results show that the SR is smaller than 0.4μm and its consistency is significantly improved,the profile error is less than 0.06 mm and the consistency of profile accuracy is also improved,and there are no burns on LTE surface,which verify the effectiveness and feasibility of the proposed method. |
