Measures to improve the accuracy of steel pipe wall thickness
The control of steel pipe wall thickness is a difficulty in steel pipe production, and measures to improve wall thickness accuracy in production mainly include the following aspects:
1. Tube billet heating
Heating should be uniform and rapid temperature fluctuations are prohibited. Every time the temperature is raised or lowered, it should be kept stable and slow, 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, and ensure that the center of the core holding roller is on the rolling line.
3. Rolling centerline
Ensure that the rolling centerline of the piercing machine is consistent with the centerline of the piercing car, avoid "up rolling" or "down rolling", and ensure that the pipe blank is evenly stressed during piercing.
4. Rolling tools
Rolling tools such as worn heads, guide plates, and rollers should be replaced in a timely manner.
5. Installation of rolling tools
The center of the roll distance and guide distance must be on the rolling line. Ensure that the centerline of the guide distance and roll distance is on the centerline 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 top rod
The outer diameter of the perforated top rod is generally selected as Φ 108mm- Φ 114mm thick walled pipe with a wall thickness requirement of ≥ 25mm and uniform wall thickness.
7. Rolling mill mandrel
The core rod should be processed using thick walled pipes with thicker wall thickness. For smaller core rods, solid billets can be used instead. Thick walled pipes with uniform wall thickness and solid billets can significantly reduce the probability of core rod bending deformation, which can effectively improve the wall thickness accuracy of steel pipes.
8. The accuracy of the core rod
The length and thickness of the core rod are relatively large, and it is generally used to turn the outer diameter first and then weld the break, or to directly turn and shape the long material. 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 exceeding the control range, and improve wall thickness accuracy.
