Experimental and numerical study of bowing defects in cold roll-formed, U-channel sections

Because the cold roll forming process has been developed such that it is now widely used in profile production, the importance of improved product quality is felt more keenly now than in the past. In order to improve the quality of cold-roll-formed products, it is necessary to investigate how defects that may occur during production can be reduced. This paper experimentally and numerically studies profile bowing, because such bowing is one of the most common defects caused by the cold roll formation of symmetrical U-channel sections. To this end, the influence of various factors associated with profile geometry and the cold roll-forming line is investigated and discussed. These parameters include strip thickness, radius of bend, flange width, bend angle increment at each stand, and inter-distance between two successive stands. Then, a curve fitting based on the linear regression method is used to compare the effects of the different input parameters on product bowing, which is used as the output parameter. Results show that the most important parameters to profile bowing are the bending angle increment at each stand, the flange width, and the strip thickness. Conversely, the effects of the inter-distance between successive stands and the radius of bend on the bowing defect are negligible. (C) 2015 Elsevier Ltd. All rights reserved.