Analysis And Optimization Of Crucial Straightening Parameters Of Medium-thick Plate Straightener

As an important equipment to eliminate shape defects,reduce residual stress and ensure flatness of medium thick plate,roller straightening machine is widely used in steel and metal production workshops.However,it is found in the actual use process that it is difficult to straighten the plate quickly even in strict accordance with the straightening process,and it must rely on the site workers to repeatedly try and correct.This problem has become a key factor that affects the economic benefit and long-term development of enterprises.Under this background,an innovative technology company wants to improve the design of 2800 medium-thick plate roller straightener,so it is urgent to determine the process parameters.Based on this,this dissertation determines a set of new methods to determine and optimize the key parameters of straightening equipment,which has important field guiding significance for the research and development of straightening equipment.The main contents of the study include:(1)Firstly,according to the geometric and mechanical properties followed in the straightening process,the varying laws of curvature and strain in the bending process are analyzed,and the mathematical models of bending curvature,residual curvature,total deformation curvature,straightening force and straightening moment are established.Then,according to the assumption principle of plane section,the elastic complex curvature model is established and the relationship between the elastic complex curvature and the total curvature is analyzed.Finally,the similarities and differences of large and small deformation straightening schemes are analyzed according to the different ways of eliminating residual curvature.(2)The analytical model of straightener is established.Firstly,the method of calculating the number of straightening rollers and the straightening speed is determined,and the structural model of the straightening roller system under the four conditions of bite condition,torsion strength,surface contact strength and straightening mass is derived.Then,a straightening precision model is established to evaluate whether the straightening results are qualified,followed by a bending model during the straightening process.Finally,according to the similarities and differences between large and small deformation straightening schemes,the straightening process of Q460 medium thickness plate with plate thickness of 40 mm in the nine-roll straightening machine is taken as an example to analyze and solve them respectively,and the analytical results are compared,and it is found that the large deformation straightening scheme is obviously better than the small deformation straightening scheme.(3)Finite element simulation analysis of straightening process.Firstly,the finite element model was established based on ANSYS/LS-DYNA finite element software,and the correctness of the straightening model was verified through three different methods,so as to ensure the simulation results were true and reliable.Then it is found that the stress variation of the plate in the straightening process is mainly located in the longitudinal fiber.Finally,the residual stress and straightness of the plate after correction are analyzed,and it is found that the change of the residual stress and straightness of the plate after correction is mainly in the direction of length.(4)Key parameters of straightening were determined and optimized.Firstly,based on the control variable method,the straightening results under each straightening parameter are compared,and the bending volume is determined as the key parameter that affects the straightening quality.Then,on this basis,an optimization model of the bending volume is established aiming at the minimum residual curvature of the outlet plate,and fmincon optimization toolbox in Matlab mathematical software is used to optimize and solve the bending model.Finally,the analytical results of the optimization model are compared and analyzed,and it is found that the optimization results can obviously improve the straightening quality of the plate,confirming the value of this new set of methods.