Stability Analysis Of Micro-Grinding Of Reciprocating Large Length-to-diameter Ratio External Circle

In recent years,with the rapid development of micro-science and technology,the ultra-refinement of micro-mechanisms,micro-electromechanical systems has directly affected the development of cutting-edge technology,modern medicine,aerospace and defense industry,especially those with feature sizes ranging from micrometers to millimeters The demand for ultra-precise and complex three-dimensional and small parts is increasingly urgent.Like traditional grinding,micro-grinding still plays an important role as the last step of micro-machining.The stability of the machining process requires high,especially the existence of regenerative chatter greatly affects the quality of the grinding workpiece.In order to improve the processing quality of micro-grinding,increase the processing efficiency,and reduce the processing cost,this paper proposes that based on the macro-grinding dynamic model,linear and nonlinear dynamic micro-models are established respectively,and the linear and non-linear micro-grinding are derived respectively Linear dynamic equations.For the linear dynamic equation,the two-parameter limit stable lobe diagram is obtained according to the system eigenvalues,and the stability prediction is performed.The main process parameters include grinding rod speed,workpiece speed,feed speed and equivalent grinding rod length.Studies have shown that:the higher the feed rate,the larger the upper limit of the two-parameter limited stable lobe diagram;the larger the equivalent rod length,the smaller the limited stable region,and the more unstable the processing.The third-order approximation of the nonlinear dynamic equations increases the parameters of the grinding system and linearizes the nonlinear dynamic equations.According to the system eigenvalues,the corresponding two-parameter limit stable lobe diagram is obtained,and the stability prediction is performed.The main parameters include grinding rod speed,workpiece speed,feed speed,equivalent grinding rod length,equivalent grinding rod diameter,grinding rod blade density,initial feed and grinding force coefficient.Studies have shown that the larger the equivalent grinding rod diameter,the larger the processing stability area and the greater the grinding rod edge density,the smaller the processing stability area.Increasing the initial feed will make the limit stable area increase and the grinding process becomes stable.Increasing the grinding force coefficient makes the stable area decrease,and the grinding process becomes more unstable.The effect of feed speed and equivalent rod length on stability is consistent with the conclusion of linear dynamics.The study also shows that the nonlinear model has more sensitive influence on stability than the linear model.Based on the linear and nonlinear theoretical basis,the parameter sensitivity analysis is established,and it is concluded that increasing the rotation speed of the grinding rod is the optimal solution to change the grinding process from the flutter state to the stable grinding state.Finally,the above theoretical analysis is partially verified.The optical glass BK7 was selected as the experimental material,and the theoretical analysis data in the previous article was selected as the experimental parameters.The experimental analysis was carried out.After the data was processed,the chatter time domain diagram and power spectrum diagram were obtained.The experimental results prove the correctness of the above theoretical model.At the same time,in the analysis,it is found that the change law of power and energy in micro grinding is the same as that of macro grinding.