Research On Optimization Of Grinding Parameters For Ball-end Grinding Tool Grinding SKD-11 Steel

SKD-11 steel has a high carbon content and a large amount of martensite.It has many excellent properties such as low elongation,high hardness,high wear resistance and so on.It is a kind of high chromium alloy steel material,which is widely used in aerospace,complex surface die and other fields.In the traditional finishing process,when grinding and polishing hard materials such as SKD-11 steel,the workpiece is often tempered at low temperature,which is prone to cracking and burning.Ball-head abrasive tool is a kind of extrusion of residual peak on the workpiece surface by small abrasive particles with soft surface.It has good contact with the workpiece surface.It can effectively reduce surface damage of hard material and improve the material removal rate.However,the grinding mechanism between workpiece and ball-end grinding tool is very complex.The surface of the workpiece after grinding is affected by many factors.The relationship between grinding parameters and surface accuracy is not clear.Therefore,it is of great significance to improve grinding and polishing technology to optimize grinding parameters and obtain a surface with higher processing accuracy.In this paper,SKD-11 steel cylindrical specimens are studied.Corundum ball-end grinding tools are used to grind them.The grinding fluid is injected into the grinding area by a high pressure jet nozzle with a diameter of 1.2mm.On this basis,the grinding parameters are optimized and the optimal combination of process parameters is obtained.Firstly,the material removal model of ball-end grinding tool is established based on the basic theory of grinding and polishing and Preston equation.The modified Preston coefficient is determined by experiment,and the reliability of the model is verified by simulation and experiment.The grinding parameters of this paper are the diameter ofgrinding tool,the depth of grinding,the feed speed of the workpiece and the jet speed of grinding fluid.Secondly,select the processing sample,elaborate the relevant experimental equipment,introduce the commonly used test methods and select the suitable test methods for this paper.Then,the range of each factor in the orthogonal test is determined by a single factor method,and the orthogonal test is designed,and the grey correlation degree analysis is carried out.According to the range analysis table and the grey correlation degree table,the optimum technological parameters combination and the order of the influence of each parameter on the polishing effect are determined respectively.Finally,the basic knowledge of Support Vector Machine(SVM)is introduced,and orthogonal experimental data are optimized by using the theory of Support Vector Machine(SVM).The optimum parameter combination is obtained.The experiment is carried out on the optimum parameter combination.The results are compared with the orthogonal experimental results and the results of grey correlation analysis,which proves the rationality of the SVM model.In the material removal model,the grinding fluid velocity is not clearly reflected,but related to Preston coefficient.The jet velocity is further analyzed,and the jet velocity of grinding fluid is further optimized by a single factor method.Finally,it is concluded that the optimized combination of grinding parameters can obtain lower surface roughness value and improve the surface accuracy of the workpiece.