Precautions for seamless steel pipe forming

The forming and sizing of seamless steel pipes are critical processes, and the design and adjustment of the hole can directly affect the quality of the pipes. When handling the forming of seamless steel pipes, the following eight points should be considered.

Pre-Perforation Adjustments:

Ensure that the hole shape of each rack is adjusted and the size of each pass is measured before perforation. This guarantees the seamless steel pipe enters each rack smoothly. The adjustment should be balanced, avoiding forced deformation on a single frame to maintain a stable and uniform change in the raising angle.

Traditional Roll Forming Techniques:

Utilize traditional roll forming techniques, such as single radius, double radius, and multi-roll kneading rolls (two, three, four, or five rolls). Sizing is often done with two or four rolls to ensure forming quality. This technique is commonly used for rectangular tube units with diameters less than φ114mm.

Equipment Control and Adjustment:

Control and adjust the equipment errors of the forming and sizing machine bases and the amount of roll bounce. Even older units can produce high-quality steel pipes with precise adjustments.

Advanced Roll Forming Skills:

Implement advanced roll forming techniques, such as the American roll forming skills, voestalpine's CTA forming skills, and Nakata's FF or FFX flexible forming skills. These techniques ensure the welded joint shape after forming and provide good appearance quality, suitable for a wider range of seamless pipes.

Unit Adjustment Process:

Ensure that the vertical center line of each pass is consistent during the adjustment process. Use the center as the base axis to find the positioning scale and the center sleeve, ensuring that the centerline of the unit (front, middle, and back) is straight and does not curve or deviate.

Reducing Elastic Deformation:

Add 2 to 3 passes to the processing deformation of seamless pipes compared to general rectangular pipes to reduce elastic deformation.

Deformation Structure:

Reduce the initial deformation angle to ensure a stable bite, increase the central curved angle appropriately, and reduce the rear deformation angle. Adding deformation passes not only reduces the deformation force but also allows the strip to release surface stress, preventing cracking in the seamless pipe by gradually increasing the surface stress gradient.

Selecting Forming Techniques:

Different forming techniques have their own advantages and disadvantages and are suitable for different conditions. When selecting equipment, consider the specific use of seamless carbon steel pipes and choose the appropriate forming methods accordingly.

By following these guidelines, the quality and integrity of seamless steel pipes can be maintained, ensuring they meet the required standards for various applications.