Wall thickness accuracy of straight seam steel pipe

Controlling the wall thickness of straight seam steel pipes is a difficult point in the production of steel pipes.

1. Tube billet heating

The heating should be average to prevent the rapid rise and fall of the temperature. The temperature of each rise and fall should be steady and slow, and the temperature of the rise and fall should not exceed 30 ℃.

2. Rolling mill mandrel

Thick-walled pipes and solid blanks with an average wall thickness greatly reduce the probability of bending deformation of the mandrel, which can effectively improve the wall thickness accuracy of the steel pipe.

3. The accuracy of the core rod

The outer machining accuracy of the core rod is controlled within ±0.1mm, and the straightness deviation of the core rod does not exceed 5mm. During welding, a precision-machined pin is inserted between the two core rods for positioning, to prevent the overall straightness of the welding from being too large.

4. Process

Determine whether the centering roller device is in place, adjust the center of the relevant core-holding roller, the opening angle and the size of the opening teeth of each action, and the center of the core-holding roller must be on the rolling line

5. Centering roller

Technology, to avoid the occurrence of central thinning and wall thickness increase, and the situation that Haou exceeds the limitation of control, improve the wall thickness accuracy.

6. Perforated ejector

The perforated ejector rod generally chooses a thick-walled tube with an outer diameter of Φ108mm-Φ114mm, a wall thickness of ≥25mm, and average wall thickness.

7. Rolling middle line

Ensure that the rolling middle line of the piercing machine is consistent with the middle line of the piercing trolley to prevent “up rolling” or “down rolling” so that the tube billet maintains an even force during piercing.

8, Rolling things

The worn plugs, guide plates, rolls, and other rolling things should be changed in real-time.

9. Rolling device

The middle of the roll pitch and guide pitch must be on the rolling line. It is guaranteed that the middle line between the guide pitch and the roll pitch is on the middle line of the piercing and rolling, that is, the upper and lower roll pitches are equal, and the left and right guide pitches are equal.