Measures to improve wall thickness accuracy of seamless steel tubes

Seamless steel pipe wall thickness control is a difficult point for steel pipe manufacturers. The measures to improve the wall thickness accuracy of seamless steel pipe production mainly include the following aspects:

1. Tube heating
The heat is uniform, which is not conducive to rapid temperature rise. Each heating and cooling should be kept slowly and steadily, and the maximum temperature should not exceed 30°C for the lift.

2. Centering roller
Determine whether the centering roller is installed in place, adjust the clamping center of the roller core, the opening angle of the opening movement, etc., and fix the center of the roller core on the rolling line.

3. Rolling center line

Ensure that the center line of the piercer piercer is consistent with the center line, and avoid "rolling up" or "rolling down", so that the tube can remain stressed even when piercing.

4. Rolling tools
For worn heads, the guide roller rolling tool must be replaced in time.

5. Hob installation
Rolls starting from the center of the rail must start from the pass line. Make sure to start from the center line of the guide roller, and start from the center line during punching and rolling, that is, the distance between the upper and lower rollers from the guide roller is equal to about the guide roller.

6. Perforated mandrel
Perforated jacks generally use uniform thickness wall pipes with an outer diameter of Φ108mm-Φ114mm, and wall thickness and wall thickness requirements of ≥25mm.

7. Mandrel rolling mill
Smaller size mandrels can be used in place of solid billets when selecting mandrels and thick-walled tube processing. Thick-walled pipes and solid blanks with uniform wall thickness can greatly reduce the probability of bending deformation of the mandrel, and can effectively improve the accuracy of the thickness of the steel pipe.

8. Precision mandrel
The slender mandrel is relatively large, generally the outer diameter of the turning port is used first and then welded, or the long material is directly turned and formed. The outer precision of the mandrel is controlled by ±0.1mm, and the deviation of the straight mandrel is not more than 5mm. When welding, a mandrel is inserted between the two segments of the finish-machined dowel to prevent over-welding to the overall straightness tolerance.

9. Process improvement
The process improvement prevents the thinning of the wall thickness in the middle and the increase of the super-thickness, and improves the thickness accuracy.