Cutting Simulation And Experimential Research Of OFHC Copper In Micro Milling Process

With the increasing demand for various kinds of high-precision small and micro-components in the fields of aerospace,biomedical,electronics,optics,and precision instruments,the processing and manufacturing of small and micro parts has attracted widespread attention and become a hot issue in modem scientific research.As the functions of small micro-products are increasing,and the structures are becoming more and more complex,micro-components have complex small-size geometric features.Micro-machining technology can be used to process these complex three-dimensional feature parts,applicable to a variety of metal materials and non-metallic materials,and thus has been widely used.Micro-cutting is not a simple process to reduce the size of the macro-cutting process.The reduction in size makes the micro-machining show different cutting characteristics than macro-cutting,such as the scale effect and the minimum cutting thickness.These characteristics make the traditional macro-processing experience can not be directly used in micro-cutting machining.In this paper,the oxygen-free copper of metal materials as the research object,to carry out related research on the mechanism of micro-milling,the establishment of a constitutive model of oxygen-free copper material,based on ABAQUS completed the material meso-scale milling simulation analysis,the micro-cutting related experiments are completed,laying a theoretical foundation for future applications.The main contents are as follows:(1)Establishment and simulation of OFHC Copper constitutive model in mesoscale cutting processApplying the strain gradient theory based on the dislocation mechanism,considering the micro-structure characteristics of materials,a material constitutive model under meso-scale was established,and the constitutive model of the material deduced under the meso-scale was analyzed and the stress-strain curves under different cutting conditions were obtained.On this basis,the finite element simulation model was established considering the cutting edge radius of the cutting tool and the failure criteria of the material fracture.The generated simulation model was used to analyze the mechanism of the scale effect under meso-scale.Through simulation,it was proved that the cutting edge radius of the cutter was the reason for the minimum cutting thickness in the micro-machining.(2)Establishment of OFHC Copper milling force model and study of experiments under the mesoscopic scaleBased on the theory of slip-line field,the milling force model of oxygen-free copper under the mesoscopic scale was established.The model was verified by milling experiments,which proved that the model has certain accuracy.Analytical models and experimental methods were used respectively to analyze and study the the influences of spindle speed,feed per tooth,and axial depth of cut on the milling feed force and the normal feed force.With the methods of range and variance analysis,the effects of these three factors were detemined.Finally through the methods of experiments and three-dimensional simulations,the effect of the micro-milling on the scale effect—the cutting specific energy can be studied.At the same time,the influence of cutting edge radius on the milling force in micro-milling was studied,which provided a basement for the study of theory in the future.(3)Study on the surface roughness under the mesoscopic scaleBased on the experiment of micro-milling of micro-milling grooves with oxygen-free copper,the surface roughness of the groove obtained by the experiment was measured,and the surface roughness on the center-line of the bottom surface was used as a criterion for evaluating the quality of milling f-orming,and the influences of different cutting parameters on surface roughness were studied.