Measures for Improving Steel Pipe Wall Thickness Precision

1. Tube billet heating: the heating should be uniform, and the temperature should not be raised or lowered rapidly. Each temperature rise and fall should be kept steady and slow, and the maximum temperature rise and fall should not exceed 30°C.

2. Centering roller: Make sure that the installation of the centering roller is in place, adjust the center of the core-holding roller, the opening angle, and the opening size of each action to be consistent, and 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 trolley, avoid "up rolling" or "bottom rolling", and keep the tube billet under uniform force when piercing.

4. Rolling tools: The worn-out plugs, guide plates, rolls, and other rolling tools should be replaced in time.

5. Installation of rolling tools: the center of the roll distance and guide distance must be on the rolling line. Ensure that the center line of the guide distance and roll distance is on the center line of piercing and rolling, that is, the upper and lower roll distances are equal, and the left and right guide distances are equal.

6. Perforated mandrel: The perforated mandrel generally chooses a thick-walled pipe with an outer diameter of Φ108mm-Φ114mm, a wall thickness of ≥25mm, and uniform wall thickness.

7. Rolling mandrel: The mandrel should be processed with a thick-walled tube with a thicker wall thickness. For a mandrel with a smaller specification, a solid billet can be used instead. Thick-walled pipes and solid billets with uniform wall thickness can greatly reduce the probability of mandrel bending deformation, and can effectively improve the wall thickness accuracy of steel pipes.

8. The precision of the mandrel: The mandrel is relatively large in length, and the outer diameter is generally turned first and then welded by breaking the hole, or the long material is directly turned into shape. The external processing accuracy of the mandrel is controlled at ±0.1mm, and the straightness deviation of the mandrel does not exceed 5mm. When welding, insert a finely machined pin between the two core rods for positioning to prevent excessive deviation of the total straightness caused by welding.

9. Improve the process: improve the process to prevent the occurrence of intermediate thinning and wall thickness increase beyond the control range, and improve the wall thickness accuracy.