Research On Roll Forming And Edge Wave Of Hat-shaped Based On Boundary Condition Forming Angle Distribution Function

The hat-shaped part is an economic section profile with high structural strength,high economic efficiency and low energy consumption,and thus is widely used in industries such as automobile,aviation,construction and civil.At the present stage,the roll forming technology mainly relies on the production experience to randomly distribute the roll forming angle of each pass,and lacks the scientific theory guidance of dividing the forming angle,so that the defects such as edge wave and springback often occur in the forming process,reducing the forming precision and quality of products.In this paper,the hat-shaped roll forming parts with small section are taken as the research object in industrial production.Firstly,the five-boundary condition forming angle distribution function is proposed to determine the forming angle of hat-shaped.COPRA finite element software is used to simulate the peak longitudinal strain in the forming process,based on the optimal five-boundary condition forming angle distribution interval determined by previous research,the optimal forming angle distribution method is obtained by optimization.Then ABAQUS software is used to simulate and compare the stress and strain of sheet metal in roll forming process under the influence of forming parameters,such as forming angle of five-boundary condition forming angle,four-boundary condition forming angle and forming angle increment by 10°,sheet thickness,material yield strength and other forming parameters,in order to evaluate the forming angle distribution method,obtain the forming law of process parameters on the roll forming process.Finally,based on the optimized forming angle distribution method,the generation mechanism of the edge wave of hat-shaped in the roll forming is simulated and analyzed,the effect of forming angle,sheet thickness and material yield strength on the edge wave in roll forming is studied through the edge wave fluctuation ?z and maximum deviation ?z of z coordinate of the flange edge and the change of the contour curve of the flange edge designed in this paper,and the experimental verification of roll forming is carried out.The results show that the stress,strain and fluctuation ?z of edge wave and maximum deviation ?z of z coordinate based on the optimized five-boundary condition distribution method is smaller than those of other forming methods,which shows its forming superiority.The stress and plastic strain in the sheet bending zone are much higher than the web zone and the flange zone,and the transverse strain in the bending zone is higher than the longitudinal strain.With the increase of sheet thickness,the stress and strain of sheet bending zone increase correspondingly.The peak longitudinal strain increases with the increase of forming angle.The edge wave of the flange edge of hat-shaped is caused by the uneven distribution of the longitudinal stress and plastic strain along the longitudinal direction.The results of simulation and experiment show that the edge wave of the flange edge of hat-shaped decreases with the increase of the sheet thickness and material yield strength.