Numerical analysis of deformation behaviour of edge portion of sheet meta at breakdown pass in roll forming process

摘要

Damage to the edge of sheet metals caused by contact between the sheet edge corner and forming roll at the inlet stage is a major obstacle to obtaining high welding quality of electric welded pipes with heavy gauges. In this paper, the deformation behavior of the edge portion of the sheet metal was systematically investigated using FEM analysis based on an approximate model, and the relationship between edge damage and forming conditions at the breakdown (edge bending) stage was clarified. The following characteristics were found. (1) The metal flow pattern at the edge portion is dominated mainly by the contact condition between the sheet metal and rolls, especially the slope angle of bottom roll surface where the sheet's edge comes into contact with the bottom roll. (2) The deformed shape of the edge portion is also affected greatly by this contact condition. Based on these results, some methods for reducing edge damage during the edge bending at the breakdown stage were suggested, and the efficiency of these methods were verified by numerical simulation.