Pipe forming the strip is unequal curvature composite longitudinal deformation process and continuous operation in cross section, and the strip is bent by the force of a multi-directional deformation process.


The basic principle of straight seam steel pipe forming theory is by the action of an external force to produce plastic deformation of the steel strip into a desired shape and size tubes. Since the steel pipe in the process of deformation of the main surface in a continuous horizontal and vertical aspects, the binding applied thereon is arranged in two aspects to implement and pass through the mill roll forming, roll passes is to make transverse deformation of steel, the steel sheet rolling mill is arranged to produce longitudinal deformation, the specific operation models and a variety of differences in engineering is a continuous steel deformation process to be implemented in stages, from the corresponding mill (including the roll groove and mill arrangement) to achieve. Longitudinal deformation in the rolling direction of the plate means into a cylindrical shape deformation, the tube cross-section transverse deformation means bend deformation.


Pipe forming process is broadly divided into three stages: crude profiled section, an intermediate stage of transition and finishing forming stage, they have in common is "ellipse a circle" principle, resulting in deformation of the reasons to spend pass system is vastly different, mainly in the conditions the classical methods, there is an edge bending method, the circumferential bending method, center and later bending method derived from the single radius, double radius, "w" molding method. Row roll forming and roll forming deformed flowers are retractable, its elliptical cross-section major axis in the transverse direction.