Construction Of H-beam Straightening Model And Optimization Of Process Parameters

H-section beam is an important structural material in the field of engineering infrastructure.However,there are various defects such as bending and distortion in the process of rolling,extrusion and transportation process.These defects are usually need to be removed by the straightening process.The traditional straightening theory simplifies too many influenced factors to make obvious difference between calculated results and actual data.It may need a long time to simulate the straightening process using finite element method.Therefore,it is important to build the precise mathematical model to describe the H-section beam straightening process and control the residual stress based on curvature integration method.Also,it is meaningful to solve the straightening parameters of H-section beam and improve the final quality.The main contribution of this paper is concluded as follow.(1)The contact angle and coordinate equation of the H-section beam straightening process was derived according to the curvature integral method and elastoplastic bending theory.The relationship between the roller gap and curvature distribution was given.Finally,the precise mathematical straightening model was built based on the curvature integration method.This model was solve quickly by using the fsolve function in Matlab? software.The important parameters such as straightening force,residual stress distribution after straightening,flatness and plastic deformation rates were analyzed.The finite element software MSC.Marc? was used to simulate the straightening process.The simulated results were compared with the analytical data.(2)To validate the analytical data,an experimental straightening machine was designed and assembled.The stiffness and strength were analyzed.The experimental flatness after straightening was used to validate the analytical data of the proposed model.(3)The nonlinear buckling analysis of H-section beam with initial residual stress was carried out by Abaqus? software.The influence of the residual stress after straightening process on the limit load of H-section beam was analyzed to get the allowable range of the residual stress.The result can provide boundary conditions for the straightening process parameters optimization model.(4)The straightening process parameters optimization model was built based on the curvature integration method.The roller gap was defined as the design variables.The residual stress and flatness after straightening process were defined as the inequality boundaries.The total straightening force was defined as the objective function.The parameter optimization model was optimized by fmincon function in Matlab? software.The optimal roller gap was analyzed to validate the analytical data.This paper proposed the precise straightening mathematical model of H-section beam,as well as the roller gap optimization model.It is useful to set the roller gap quickly for the practical production.Also,it can be used to evaluate the final straightening quality.