Research On The Key Technology Of Rolling Technology Of Large-scale Four-roll Plate Rolling Machine

With the rapid development of modern manufacturing industry,metal curved coil products have occupied an increasing proportion in various metal products,and their accuracy requirements have become higher.In the field of roll forming,with the advantages of small remaining straight edges and saving materials,the demand for four-roller rolling machines is increasing.Aiming at the problems that the forming mechanism of medium-thick plates rolled by large four-roller plate bending machines is still unclear and the forming accuracy is difficult to meet the process requirements,this paper further studies the forming mechanism of four-roller plate bending machines and the key technologies of the bending process.The main contents include:(1)Analyze the forming mechanism of the four-roller plate rolling machine,and derive the stress-strain relationship and curvature-bending moment relationship of the plate bending;Analyze the classic unloading rebound model,and obtain the calculation formula of the plate spring radius;Analyze the geometric position of the roll bending process and the force of the plate,and establish the geometric model of the pre-bending stage and the multi-pass rolling stage of the four-roller plate bending.(2)Use ABAQUS to establish a finite element model of the axis roller and the plate during the rolling and unloading rebound phases,analyze the influencing factors of the phenomenon of edge angle,and establish a theoretical model of the distance of the pre-bending section of the plate;Through the analysis of the strain field on the lower surface of the plate,the analysis of the circumferential curvature of the plate and the quality analysis of the joint of the plate,the reasons for the edges and corners of the plate are obtained,and the influence of single pass forming and multi-pass forming on the edge phenomenon of the plate is analyzed.(3)Derive the calculation formula for the driving torque of the four-roller plate bending and the deflection equation of the lower roller,and obtain the influence of the width of the plate on the minimum bending radius,the driving torque of the coiler and the straightness of the cylinder;combining mathematical model and finite elements model,compares and analyzes the maximum stress,maximum driving torque,and maximum forming force in single-pass roll forming and multi-pass roll forming,and studies the effect of different bending processes on width effects.(4)Study the influence of the number of bending turns and the target forming radius on the bending of the plate;Calculate the driving torque and contact stress in the bending process by combining the effect of the width of the plate to determine the minimum number of bending turns and the minimum bending radius;Analyze the multi-pass paths in the existing research,and optimize the multi-pass paths based on the forming efficiency and forming quality.The experimental results show that the optimized paths are feasible.