Measures for improving the accuracy of steel pipe wall thickness
The control of steel pipe wall thickness is a difficult point in steel pipe production. Measures to improve wall thickness accuracy in production mainly include the following aspects:

1. Tube blank heating
   Heating should be uniform, and rapid temperature rise and fall is prohibited. The temperature should be kept stable and slow each time, and the maximum temperature should not exceed 30 ℃.
2. Centering roller
   Determine whether the centering roller is installed in place, adjust the center, opening angle, and opening size of the relevant core holding roller to be consistent. The center of the core holding roller should be on the rolling line.
3. Rolling center line
   Ensure that the rolling center line of the piercing machine is consistent with the center line of the piercing car, avoid “up rolling” or “down rolling”, and maintain uniform stress on the tube blank during piercing.
4. Rolling tool
   Rolling tools such as worn plugs, guide plates, and rollers should be replaced in a timely manner.
5. Rolling tool installation
   The center of roller pitch and guide pitch must be on the rolling line. Ensure that the center line of the guide distance and the roll distance is on the center line of the piercing rolling, that is, the upper and lower roll distances are equal, and the left and right guide distances are equal.
6. Perforated ejector pin
   The outer diameter of the perforated ejector pin is generally selected as Φ 108mm- Φ 114mm thick wall pipe with a wall thickness requirement of ≥ 25mm and uniform wall thickness.
7. Mill mandrel
   The core rod shall be processed with thick wall pipes with thicker wall thickness. For core rods with smaller specifications, solid blanks can be used instead. Thick walled pipes and solid billets with uniform wall thickness can significantly reduce the probability of mandrel bending deformation, and can effectively improve the wall thickness accuracy of steel pipes.
8. Accuracy of mandrel
   The slenderness of the core rod is relatively large, and it is generally used to turn the outer diameter first and then break it for welding, or to directly turn the long material into shape. The external processing accuracy of the core rod shall be controlled within ± 0.1mm, and the straightness deviation of the core rod shall not exceed 5mm. During welding, a precision machined pin is inserted between the two core rods for positioning to prevent excessive overall straightness deviation caused by welding.
9. Improve the process
   Improve the process to prevent intermediate thinning and wall thickness increase beyond the control range, and improve wall thickness accuracy.