Research Of White Layers During The Dry Hard Turning Different Hardened State Cr12MoV

There are many factors that reflect the quality of the machined surface, the white layer is an important technology index. The white layer has special physical properties: on the one hand, more matrix material of high hardness,good wear resistance; on the other hand, more brittle, process parameter control will not produce micro cracks within the organization in the process of using materials, parts surface with crack and fall off. Therefore, to improve the machined surface, it is necessary to conduct in-depth research of white layer dry hard turning in. According to the problems during real production, on the one hand the need for experimental study on formation mechanism of machined surface of white layer on the other hand, the prediction model to establish the surface of white layer, for the development and optimization of cutting parameters for the actual production to provide scientific and theoretical basis.At present, domestic and foreign scholars mainly of bearing steel GCr15 machined surface layer were studied, of Hardened Mould steel Cr12 Mo V research less, in studying the factor of influence the thickness of white layer, effect of different hardening state the thickness of white layer is scarcely studied.The polycrystalline cubic boron nitride cutting tools(PCBN) dry hard turning hardened die steel were finite element simulation and experimental research, on the machined surface layer of white tissue morphology and cutting parameters on the thickness effects are analyzed and the establishment of the prediction model of the thickness of white layer. As follows there are main contents and results:(1) A right angle cutting model of PCBN tool steel Cr12 Mo V was established by the finite element simulation analysis method, and the equivalent stress, equivalent stress, and the effect of heat and force were analyzed.(2) Of the obtained experimental has machined on the surface of the sample in the scanning electron microscope(SEM) and energy spectrum(EDS) were scanning analysis, analysis of the white layer formation mechanism and microstructure of the surface by dry-hard turning Cr12 Mo V.(3) The single factor method, cutting parameters, cutting speed, cutting depth, feed rate and hardness of work-piece material as the independent variable, the thickness of white layer as the dependent variable. According to the test data, explore various cutting parameters of white layer thickness influence and the use of multiple nonlinear regression method to establish forecast model of the thickness of white layer.The results of the study indicate that: dry, hard state turning machined surface produce larger equivalent stress, cutting temperature is from machined surface to the internal conduction of the work-piece; have been processing the surface of white layer formation is under the combined action of thermal and mechanical results; to white layer thickness cutting speed and depth affect larger, feed the thickness of white layer is not significant; establishment of whit-e layer thickness prediction model through the complex correlation coefficient test and F test, the test model of regression effect is very significant to the thickness of white layer for more accurate prediction.