Optimization Study Of Machining Parameters For Weakly Rigid Aluminum Alloy Parts

In the quest for structural lightweight today,weakly rigid aluminum alloy parts are widely used in aircraft structural parts and other applications,but due to the material’s small modulus of elasticity,yield strength,relatively low stiffness of the machined surface and other reasons,resulting in its milling process,easily affected by milling forces,milling heat and deformation,resulting in large part processing errors,it is important to reduce the machining deformation of weakly rigid aluminum alloy parts through reasonable methods,so as to ensure the production requirements of high quality,high efficiency and low cost machining.In this paper,7050-T7451 weakly rigid aluminum alloy parts are taken as the research object,and the research goal is to reduce the milling deformation,appropriately improve the processing efficiency and reduce the processing cost.On the basis of optimization of milling parameters,this paper proposes to combine low melting point alloy to support weakly rigid aluminum alloy parts.Through optimization of milling parameters and pouring thickness of auxiliary support,the purpose of this paper is to provide a method for reducing machining deformation of weakly rigid aluminum alloy parts.The specific findings of this paper are reflected in the following:（1）Theoretical analysis of milling deformation.Milling model of weakly rigid aluminum alloy parts is established and analyzed by combining mechanical deformation and material thermal deformation characteristics,and it is found that the main factors influencing the machining deformation of the parts are spindle speed n,feed per tooth f_z,radial depth of cut a_p,tool front angleγ₀ and rigidity of the machined surface;finally,the measures to reduce the machining deformation are determined by studying the milling parameters and the influence of machining deformation,and the auxiliary support to improve the rigidity of the machined surface,and optimizing the milling parameters such as spindle speed n and the casting thickness of the auxiliary support material.The results of the above study lay the theoretical foundation for reducing the deformation of weakly rigid aluminum alloy parts by milling.（2）The influence of milling parameters on machining deformation.The research scope of milling parameters,the key parameters of the finite element analysis platform for machining deformation,and the location of machining deformation measurement points were analyzed.The influence degree and law of milling parameters and machining deformation were analyzed with response surface method（RSM）.It was found that among milling parameters,the radial depth of cut and the feed rate per tooth had a greater influence on the machining deformation,while the tool rake angle had a minimum influence on the machining deformation;With the increase of spindle speed,feed rate per tooth and radial cutting depth,the overall machining deformation shows an increasing trend in varying degrees;With the increase of tool rake angle,the machining deformation decreases gradually.The above research provides a basis for the finite element analysis of milling parameters and machining deformation,and provides a basis for the selection of better milling parameters later.（3）The establishment of machining deformation prediction model and the optimization of milling parameters.Based on the adaptive fuzzy inference system（ANFIS）and the improved neural network（BAS-BP）of the longicorn beetle whisker search algorithm,two milling parameters and machining deformation prediction models are established respectively.The comparison of error rates shows that the average error rate of BAS-BP is41.09%lower than that of ANFIS;combined with BAS-BP machining deformation prediction model,the multi-objective parameter optimization of milling parameters is carried out with the optimization goal of reducing machining deformation and improving machining efficiency.The optimal milling parameters are 8000rpm,0.143mm/tooth,0.42mm,15°,combined with response surface method;the analysis of the optimization effect of the better milling parameters shows that when the machining deformation decreases,the effect of deformation reduction is more obvious than the effect of machining efficiency reduction,and when the machining deformation increases,the effect of machining efficiency improvement is more obvious than the effect of deformation reduction,so the optimal milling parameters are better optimized.（4）Research on auxiliary support and optimization of pouring thickness.By analyzing the characteristics of auxiliary support materials and combining the physical and material characteristics of parts,the eutectic low melting point alloy composed of 55.5%（Bi）and44.5%（Pb）with a melting point of 124°C is selected as the auxiliary support materials;the optimization range of pouring thickness is analyzed based on factors such as part structure and size.In this range,the optimization goal is to reduce processing deformation and processing cost.The pouring thickness of auxiliary support materials is optimized by multi-objective parameters.Combining the change relationship between pouring thickness and part processing deformation,the optimal pouring thickness is finally selected as 14 mm;the analysis of the optimization effect of better casting thickness shows that when the processing deformation decreases,the effect of deformation reduction is more obvious than the effect of processing cost increase,and when the processing deformation increases,the effect of processing cost reduction is more obvious than the effect of deformation increase,so the optimal pouring thickness is better optimized.