The Reverse Bending Calculation And The Research Of The Leveling Method For The Heavy Steel Plate

The wide and thick plates support the rapid development of the national economy and it is widely used.The traditional way is to manually set the stroke of the indenter,manually place the backing plate,and manually measure the residual deflection of the plate through the instrument for the leveling process of wide and thick plates.Supported by the major science and technology project of Shanxi Province(20181102016)and the design and development project of Jiangsu Dageng 25 MN pressure leveler,this project carries out the research on intelligent pressure leveling.In this paper,the pressure leveling of high-strength wide and thick plate is taken as the research object,and the full-automatic pressure leveling is taken as the research object.By establishing a mathematical model of three-point and four-point bending leveling of bent plate,the full-automatic placement method and device of backing plate are invented,and the calculation method of plate flatness based on point cloud data is developed;At the same time,the influence mechanism of different working conditions on plate flatness is studied by finite element simulation.The main contents of this paper are as follows:Firstly,this paper establishes the mathematical model of the bending force of the plate based on the mathematical analysis of the relationship between the bending force and the flat curvature of the plate,and realizes the calculation of the bending force and the flat curvature of the plate.The three-dimensional model of the plate three-point bending and leveling is established by using ANSYS software.The accuracy of the mathematical model is verified by simulating various processes of three-point bending and pressure straightening.In the experiment,the mathematical model is verified from three different plate thicknesses,which proves that the mathematical model has good accuracy.Thus,the problem of traditional manual setting of indenter stroke is solved,and the work efficiency is greatly improved.(2)The three-point bending is difficult to effectively eliminate bending defects in long-span bending.The four-point bending leveling method of plate is proposed based on the three-point bending leveling model,and the four-point bending leveling mathematical model of plate is established.The three-dimensional model of plate four-point bending and leveling is established by the ANSYS software.The accuracy of the mathematical model is verified by simulating various processes of four-point bending and pressure straightening.The process parameters of different span,plate thickness,yield strength and plate width are simulated by finite element method.The mathematical models of three-point and four-point bending are compared,and the effective criteria for three-point and four-point bending are constructed.(3)The dynamic process of three-point bending leveling of plate with different span,plate thickness,yield strength,plate width and holding time was simulated by finite element method taking the three-point bending leveling of plate as the research object.The effects of different process parameters on the deflection after three-point bending leveling were studied.The smaller the thickness of the plate,the better the flatness after leveling When the span,yield strength,plate width and other process parameters are the same;When the process parameters such as span,plate thickness and plate width are the same,the higher the yield strength of the plate,the better the flatness after leveling.In a certain pressure holding time,the longer the pressure holding time,the more sufficient the plastic deformation of the plate and the better the flatness of the plate.(4)The calculation model of plate flatness is established.The discrete three-dimensional coordinate points are fitted into the curve by using the method of mathematical interpolation.The plate flatness and curvature are calculated based on the point cloud data,and the automatic detection of plate flatness is realized;The automatic placement method and device of backing plate in narrow space have been developed,which solves the key bottleneck problem involved in full-automatic leveling.