The seamless pipes has a hollow cross-section and is widely used as a pipeline for conveying fluids, such as octg pipes for conveying oil, natural gas, gas, water, and pipes for certain solid materials. Compared with solid steel such as round steel, the steel pipe is lighter in weight when the bending and torsional strength is the same, and it is an economical section steel.

Some pass design and adjustment methods will directly affect the quality of seamless steel pipe forming and sizing, so we should pay attention to the following when dealing with seamless steel pipe forming:

1) Before the belt is threaded, the pass shape of each frame should be adjusted, and the size of each pass should be measured to ensure that it matches the size of the seamless steel pipe and can enter each frame stably. During the adjustment, the force should be balanced, and it should not be deformed forcibly on one frame, so as to ensure that the lifting angle changes steadily and evenly;

2) Traditional roll forming technology has single radius and double radius, plus two, three, four or five kneading rolls, and two or four sizing to ensure the forming quality. This traditional roll forming technology is mostly used for rectangular tube units with a diameter less than φ11mm;

3) In the production of seamless steel pipes, control and adjust the machine forming and sizing machine base equipment, accumulation errors and roll bounce will affect the production of seamless steel pipes by older units;

4) Roll forming technology from the United States, CTA forming technology from VAI, FF or FFX flexible forming technology from Nakata, Japan, etc. It can ensure the shape of the welded joint and good appearance quality after forming, and is suitable for seamless steel pipes with a wider standard range;

5) In the process of unit adjustment, first of all, ensure that the passes of the vertical center line are consistent, and use the center as the base axis to find out the positioning scale and center sleeve. In the direction of the horizontal line, it should be arranged according to the technology to form a straight line for the uphill line (downhill line) without curve jumps;

6) In order to reduce elastic deformation, 2 to 3 passes should be added to the deformation passes of seamless steel pipes compared to ordinary rectangular pipes;

7) In terms of deformation structure, the initial deformation angle should be reduced to ensure the stable bite of the seamless steel pipe, the central bending angle should be appropriately increased, and the rear deformation should be appropriately reduced. Increasing the deformation pass is not only to reduce the deformation force, but also to slow down the gradient of the surface stress when the surface stress of the strip occurs, which can prevent the seamless steel pipe from cracking;

8) Various forming skills have different advantages and disadvantages, and are suitable for different conditions. According to the use of seamless steel pipes, carefully consider when selecting equipment to choose different forming skills.