How to straighten steel pipe after bending and deformation?

Long steel products such as seamless pipes and welded pipes are often bent or distorted due to external forces, temperature changes, internal forces, etc. during rolling, forging, extrusion, drawing, transportation, cooling and various processing processes. In order to obtain a straight finished strip, these defects can be eliminated through a straightening process. The reasons why the above strips are bent or twisted are as follows:

(1) During the rolling process, the rolled piece is deflected due to uneven reduction (especially for steel with special-shaped sections), uneven cooling, inconsistent upper and lower roller speeds, or inaccurate pass adjustment;
(2) Due to the asymmetric shape and uneven cross-section thickness of the bar, uneven heating and cooling after rolling result in longitudinal or transverse bending deformation of the bar;
(3) Operations such as sawing and shearing the strip under hot conditions will also cause the strip to bend;
(4) If the strip is in a hot state after rolling and stays on the conveyor roller table for too long, the strip will also bend due to its own weight and other reasons.

Steel pipe straightening

The essence of straightening is the elastic-plastic deformation of the steel pipe after it is subjected to the same type and size of external force. When the external force is removed, elastic recovery occurs under the action of the internal force until the internal force reaches a new balance and reaches the desired shape. The straightening of steel pipes is a repeated elastic-plastic deformation process. That is to say, in the case of obvious elastic-plastic bending, the elastic recovery capacity of the steel pipe is almost the same. Therefore, no matter how inconsistent the original curvature of the steel pipe is, after a large bend, the curvature can be almost uniform everywhere, thereby achieving a straight effect. Considering the different bending characteristics of steel pipes with different cross-sectional shapes and the differences in straightening objectives, the reverse bending straightening method is generally used to straighten plates and profiles, while the rotation straightening method is used to straighten pipes.

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