The Calculation Of Cutting Force And Its Influence On Machining Accuracy

High-precision cutting is widely used in the machinery manufacturing industry,and the premise of excellent machine tool processing is that the error value is small and the processing process is stable.Due to the existence of cutting forces and turning chattering conditions,size and vibration errors appear on the surface of the workpiece,which greatly affects the machining efficiency and service life of the lathe.In practice,the geometry and process parameters of machine tools are generally uncertain.It is important to study their changes and effects to improve the quality of processing technology and reduce processing costs.In this paper,the cutting force model for turning is established based on the unequal shear zone theory.The finite element method and geometric analysis methods are used to establish the radial error model of the slender shaft machining process.Based on the regenerative chatter theory,the turning shaft workpiece dynamics model is established.Considering the influence of random uncertainty,reliability and sensitivity analysis was performed.Finally,the reliability optimization design of the turning process parameters is carried out.The specific research content is as follows:First,a two-dimensional cutting model is established,the cutting force is calculated,and the numerical calculation results are obtained with Matlab.In order to explore the difference between the model and experimental data values,simulation and analysis were performed with finite element software,and the results were compared with the experimental data in the literature for verification.Finally,the cutting force performance is analyzed to obtain the cutting force probability distribution map.Secondly,the slender shaft is simplified for finite element analysis,and the radial error model of the slender shaft is obtained.Finally,the reliability probability analysis is performed.Then the sensitivity analysis evaluates the degree of influence of each parameter on the radial error,and analyzes the depth of cut and the front of the tool.The changes of the angular value,the diameter of the slender shaft,the cutting speed,the cutting width,the distance from the tool post to the tool,and the aspect ratio are obtained,and the influence of the corresponding parameters on the radial error and system reliability is obtained.Thirdly,the formation mechanism of regenerative chatter was analyzed,and a turning dynamic model was established.Mathematical analysis was performed on ordinary and slender shafts,respectively.The relationship between the spindle speed and the turning depth is analyzed,and the influence of each processing parameter on the stability is summarized.Kriging method and Monte Carlo method were used to analyze the reliability and sensitivity of the system's flutter stability,and the degree of influence of each parameter on reliability was evaluated.Finally,the reliability optimization model of the turning process parameters is established.The turning radial error and the stability of the turning system are set as constraints,and the optimization objective function is set to the maximum value of material removal rate.The sequential optimization and reliability evaluation method and artificial bee colony algorithm were used to optimize the parameters,and finally the optimization results were obtained.