How to form small and medium diameter ERW pipes?

Posted by zora li on March 20th, 2023

How to form small and medium diameter ERW pipes?

Small and medium diameter ERW pipes mainly adopt continuous roll forming method, and also use row roll forming method

1. Continuous roll forming method. Continuous radial forming is to continuously plastically bend the tube blank into a tube on a multi-stand rolling mill with a certain roller table.

The forming machine is generally composed of 6~10 double-roller horizontal frames. Passive guide vertical rollers are installed between each horizontal frame, its function is to prevent the tube billet from moving in series, make it guide correctly, and prevent the strip steel from springing back. The number of horizontal frames depends on steel pipe specifications. There are two types of horizontal shelves: cantilever type and fulcrum type. Cantilever type can be used for small-diameter or thin-walled pipes, which is easy to replace and light in weight. Double-pivot type can be used for large-diameter pipes, which has good rigidity.

2. Rolling cold bending forming method is a new forming technology developed on the basis of medium-sized straight seam electric welded pipe forming process in recent years. When forming large-diameter (400mm) thin-walled tubes on a continuous roll forming machine, the biggest problem is the elongation of the edges on both sides of the tube. "Wrinkles are easy to produce, resulting in unstable molding and difficult welding. Therefore, try to prevent wrinkles in the pass design.

In order to prevent edge wrinkling, one is to control the edge extension. The second is to absorb edge compressive strain extending between the rollers. The column-column (CF) forming method is characterized in that a set of rolls are set outside the edge along the axial direction of the tube blank to control the edge extension. At the same time, the roller group is wrapped around the edge of the tube blank from the outside, and the edge extension is absorbed in the form of compression deformation, so this is a forming method that can prevent the edge from "extending" and absorbing the edge "expansion".