In Situ Analysis Of Dynamic Process Of Polycrystalline Metal Micro Cutting

In the micro-cutting of polycrystalline metals,the blunt radius of the cutting edge of the tool is equivalent to the cutting thickness and grain size in the order of magnitude.Therefore,compared with macro cutting,the blunt radius of the cutting edge of the tool is related to the material deformation during the cutting process.Chip formation and microstructure evolution have a significant impact.In this paper,a series of orthogonal micro-cutting experiments are carried out for polycrystalline metal materials.The optical measurement method is used to record the complete chip formation process through a high-speed camera.The plastic deformation and microstructure evolution of the material are analyzed,and the displacement and strain of the deformation zone are calculated.In-depth and comprehensive investigation of the essential characteristics of metal micro-cutting.The specific research work is as follows:In order to carry out multi-crystal metal orthogonal micro-cutting experiments on ultraprecision machine tools,it is necessary to design and develop necessary auxiliary devices,mainly including sample fixtures,six-degree-of-freedom micro-adjustment platform,highspeed camera brackets and other auxiliary mechanical structures.In the experiment,a highspeed camera is used to capture the dynamic process of chip formation and material deformation.The optical equipment used mainly includes a high-speed camera,a metallographic microscope objective,a zoom lens body and an LED point light source.In order to obtain the image of the grain change during the cutting process,the test specimens were prepared by heat treatment and surface corrosion.For two typical materials of H70 brass and TU1 oxygen-free copper,a series of orthogonal micro-cutting tests were carried out.The shear angle of H70 brass was measured at different cutting depths.The study found that although the cutting depths are different,the shear The size of the cutting angle remained basically unchanged.The rapid stop method was used to measure TU1 oxygen-free copper at different cutting depths.The study found that as the cutting depth increases,the size of the cutting angle increases significantly;the microcutting process is observed Changes in the microstructure;analysis of the H70 brass chip formation process at different cutting depths,the results show that although the cutting depths are different,the chips have always been sawtooth;observation and analysis of the minimum cutting thickness range of H70 brass,the study found that the cutting depth is Continuous chip formation can still be observed at 5% of the edge radius.Digital Image Correlation technology(DIC)is used to calculate the displacement and strain during the formation of sawtooth chips in the micro-cutting process,and analyze the plastic flow trend of the material and the formation of shear slip bands when the sawtooth chips are formed.