Development of a numerical strain modelling technique for the roll forming of ERW pipe

Conventional roll forming practices are used by many major steel companies for the manufacture of thin walled electric resistive welded (ERW) steel pipe. There is a trend in the pipe rolling industry towards the production of thinner walled pipe with higher strength steels. Since many of the existing conventional rolling mills were designed to accommodate heavier walled pipe, roll forming the lighter sections can result in quality control problems. As the sheet material, or skelp, becomes thinner, its lateral stiffness decreases, increasing the occurrence of edge kinking that can reduce the overall weld quality. Understanding this manufacturing difficulty is hampered by the lack of a theoretical model describing the strain history of the skelp during the roll forming process. Consequently, a general understanding of the cause and cure of the problem has been difficult to achieve.; This paper presents a method of describing the complex deformed geometry of the skelp material and a method of using this geometric description to define the strain state in the deformed skelp. By developing a geometric model of the deformation process that is based on the mill setup parameters, a study of the factors influencing the process has been possible.; Additionally, it has been demonstrated that the often assumed geometry of the deformed skelp is not an accurate representation of the actual geometry. A method that is accurate and relatively easy to use has been proposed to correct the theoretical definition.