STRAIGHT SEAM STEEL PIPE, TUBE BLANK DEFORMATION PROCESS KNOWLEDGE

The deformation process of the straight seam steel pipe and the tube in the forming machine is very complicated. It includes the longitudinal deformation, the transverse deformation of the straight seam steel pipe and the deformation of the section.
(1) longitudinal deformation Longitudinal deformation refers to the tube from the flat into a cylindrical process in the direction of the deformation of the rolling line. Longitudinal deformation is not uniform. In the preform section, the extension L ‘of the edge portion of the strip is larger than the extension L of the central portion and reaches the finish frame of the closed hole, and the extension L of the central portion is larger than the extension L’ of the edge portion. This longitudinal uneven deformation is the main feature of strip deformation during continuous roll forming.
Longitudinal Deformation of Strip Steel Strip
(2) Transverse deformation Transverse deformation refers to the bending deformation of the tube in each forming frame, that is, deformation caused by the forming hole. The problem of transverse bending deformation of the tube in each particular type of rack is the problem of roll hole design.
(3) Deformation of the cross section The deformation of the cross-section refers to the change in the thickness of the steel pipe after the molding (in fact, after the straightening). The change in wall thickness is less noticeable when forming thicker wall pipes. Thin-walled tube molding, straight seam steel pipe thickness on the one hand than the slab thickness of a slight thickening, on the one hand the same section of the wall thickness of a regular, uneven distribution. The wall thickness of the edge portion is smaller than the wall thickness of the bottom portion of the tube, which is the result of the edge extension. As the deformation of the section is very small, no significant impact on the quality, so negligible. Generally do not focus on research.
The molded tube is bent and deformed only in the plane perpendicular to the center line of the strip and pipe relative to the flat strip: the strip edge should also be restored when the strip is shaped as a tube and elongated The same length as the middle of the strip. This involves the edge of the extension and rebound of these two issues.
Straight seam steel pipe (4) Edge extension and rebound The actual deformation of the strip in the forming process is much more complex than the above situation, in the general roller continuous molding process, the strip is actually segmented molding, the so-called ladder forming The The edge of the strip in the ladder forming produces a waveform, as shown in Fig. This situation will inevitably lead to increased local stress of the strip