Analysis And Experiment Of Reverse Bending Characteristics On Linear Guide Straightening Process Considering Hardened Layer

As one of the core components of machine tool equipment,linear guide is the benchmark of main functional components of manufacturing equipment and the key to improve machining precision of manufacturing equipment to ensure the straightness of guide rail.In this paper,the effect of hardening layer produced by heat treatment on subsequent straightening of guide rail is studied.Firstly,the distribution of hardened layer of linear guide rail,the microstructure and mechanical properties of the hardened layer are analyzed.By simplifying the mechanical model of the hardened layer and combining elastic-plastic bending theory,the elastic-plastic evolution path of section and the stress-strain relationship in straightening process of guide rail are analyzed.Secondly,according to straightening theory,the prediction model of straightening travel of linear guide rail considering the hardened layer is established,and an adaptive straightening stroke prediction model of hardened layer parameters was fitted by experiment straightening is proposed.Finally,the theoretical results obtained in this paper are verified by metallographic analysis and microhardness experiment,as well as the comparison between the simulation and the straightening process and the theory.The main research contents and work of this subject are as follows:(1)Analyze the distribution law of the hardened layer of linear guide rail after quenching,and explore the difference between the hardened layer of the linear guide rail and the mechanical properties of matrix according to the structure change and hardness change trend of the hardened layer after quenching.The stress-strain law of linear guide under different distribution of hardened layer is analyzed.The research shows that the distribution law,effective depth and yield strength of the hardened layer are related to the straightening process parameters,and the deviation of the neutral layer will occur in the straightening process of the guide rail with single hardened layer distribution.(2)Based on the straightening theory,the straightening travel-deflection prediction model was established by analyzing the bending moment and curvature of the guide rail section and introducing time factor to deduce the stress coupling law of the section with the increase of straightening times.According to the elastoplastic state evolution of the section caused by the hardened layer,an adaptive straightening stroke prediction scheme was proposed by fitting the parameters of the hardened layer with the experimental straightening test.(3)ANSYS simulation software was used to simulate the straightening process of linear guide rail with hardened layer.The analysis results show that the stress neutral layer in the straightening process of the single hardened layer deviates to the side with stronger yield strength.The initial deflection-straightening stroke curves obtained by simulation and theoretical calculation are compared.The correctness of the theoretical analysis is verified.(4)According to metallographic analysis,microhardness test and pressure straightening test.The reliability and high efficiency of the prediction model of straightening travel are verified.Comparing the parameters of the hardened layer measured by microhardness experiment and the fitting of the adaptive straightening stroke prediction scheme,the validity of the adaptive straightening stroke prediction scheme is proved.