Research On Multi-objective Optimization Of Wire Surface Defect Removal By Turning

High-temperature alloy wire is an important raw material for the manufacture of aviation fasteners,with the characteristics of small diameter and large length.After melting,forging,rolling,drawing and reducing processes will often appear surface cracks,surface folding and surface black skin and other defects.At the same time,there will be problems of large ellipticity and poor dimensional uniformity.The traditional process for surface defects mostly uses grinding and chemical pickling.On the one hand,grinding processing high-temperature alloy r causes surface burns on the workpiece,and grinding processing can only process small-sized workpieces.On the other hand,chemical pickling is easy to produce damage erosion on the surface of the workpiece,producing new defects such as pitting,resulting in poor surface roughness.And chemical pickling is more polluting,which is not conducive to the promotion of green manufacturing.In this paper,a new process for surface turning of high-temperature alloy wire containing surface defects using a centerless lathe.A multi-objective optimization method is used to improve the cutting surface integrity and machining accuracy of the wire containing surface defects.This paper focuses on the multi-objective optimization of surface integrity and machining accuracy for turning of wire containing surface defects.The article takes the new process of removing surface defects of GH2132 high temperature alloy wire by centerless lathe turning as the core of research.First,the effects of different surface defect types and different surface defect thicknesses on the removal of wire surface defects by centerless lathe turning are analyzed.Then,the cutting surface integrity and machining accuracy of wires containing different surface defect types and different surface defect thicknesses were compared when the process parameters were changed.Also,the mechanism of formation of cutting surface integrity and machining accuracy of wire containing defects is investigated.Finally,the surface integrity and machining accuracy of GH2132 wire turning after removing surface defects are predicted and optimized,and the feasible process parameter domain and optimal process parameter set of single-objective optimization and the feasible process parameter domain and optimal process parameter set of multi-objective optimization in engineering application are obtained.The main work of the thesis is as follows.（1）The basic principle of removing surface defects of wire by centerless lathe turning is described.Design a single-factor test to analyze the surface integrity and machining accuracy of turning wire with different surface defect types and surface defect thicknesses.It can be obtained that different wire surface defect types and surface defect thicknesses have no effect on the overall trend of surface roughness,surface microhardness and dimensional error.Detection of surface defects wire turning surface residual stress,you can get the axial is residual compressive stress,circumferential is a smaller residual tensile stress,also can get the distribution range of surface residual stress.（2）Determine the trend of influence of centerless lathe process parameters on surface integrity and machining accuracy of surface defective wire turning,and analyze the formation mechanism.It can be found that when the spindle speed reaches about380 r/min,the centerless lathe will produce cutting chatter when machining wire,and the tool surface will easily produce chip tumor when cutting at low feed rate,which will lead to the deterioration of surface integrity and machining accuracy of wire.The regression models of surface roughness,surface microhardness and dimensional error were constructed.It can be obtained that the effect of feed speed on surface roughness and dimensional error is greater than that of spindle speed,and the effect of feed speed on surface microhardness is less than that of spindle speed.The minimum surface roughness process parameters,the minimum dimensional error process parameters and the maximum surface microhardness process parameters for the removal of wire surface defects by centerless lathe turning can also be obtained.（3）Determine the multi-objective optimization process parameters for removing surface defects of GH2132 wire by centerless lathe turning,and analyze the influence of centerless lathe process parameters on multi-objective optimization.Using the analytic hierarchy process,we can obtain a surface roughness weight of 0.6,a dimensional error weight of 0.27,and a surface microhardness weight of 0.13 in the multi-objective optimization.Using grey theory,it can be obtained that the spindle speed has more influence on the multi-objective response than the feed rate.Using a combination of response surface method and gray relational grade method,a multi-objective optimized gray relational grade model for surface integrity and machining accuracy of surface defect line turning can be obtained.The optimal multi-objective optimization parameter set can also be obtained.According to the requirements of engineering applications,the minimum evaluation index GRG_minfor the multi-objective optimization of surface integrity and machining accuracy of surface defective wire turning is determined to be0.59,and the feasible process parameter domain for multi-objective optimization of wire surface defect removal by turning can be obtained.