Measures for improving the precision of seamless carbon steel pipes

The control of the wall thickness of the seamless carbon steel pipe is a difficult point in the production of the steel pipe. The measures to improve the precision of the wall thickness of the seamless pipe mainly include the following aspects:
1. Tube heating
Thermal uniformity prohibits rapid increases in temperature. Each heating and cooling should be kept slow and steady, and the maximum temperature should not exceed 30°C.
2. Centering roller
Determine whether the centering roller is installed in place, adjust the core clamping center, the opening angle of the opening movement is the same, and clamp the core center on the rolling line.
3. Rolling center line
Ensure that the center line of the piercing car of the rolling piercing machine is consistent with the center line of the piercing, and avoid "rolling up" or "rolling down", so that the pipe maintains a uniform force during piercing.
4. Rolling tools
For worn heads, the guide rails and roller rolling tools must be replaced in time.
5. Installation of rolling tools
Rolling from the center of the guide rail must start from the rolling line. Make sure that the distance from the center line of the guide roll and from the center line during piercing and rolling, that is, the distance between the upper and lower rolls, is approximately equal to the guide.
6. Perforated mandrel
Perforated jacks usually use uniform thick-walled pipes with an outer diameter of Φ108mm-Φ114mm, and wall thickness and wall thickness requirements of ≥25mm.
7. Mandrel grinding
When selecting mandrels and thick-walled tubes, smaller mandrels can be used instead of solid billets. The thickness of the thick-walled pipe and the solid billet is uniform, which can significantly reduce the probability of bending deformation of the mandrel, and can effectively improve the thickness accuracy of the steel pipe.
8. Precision mandrel
The slenderness of the mandrel is relatively large. Generally, the outer diameter of the fracture is first turned and then welded, or the long material is directly turned and formed. The accuracy of the outer ring of the mandrel is controlled to ±0.1mm, and the deviation of the straight core is not more than 5mm. When welding, the mandrel is inserted between the two segments of the finish-machined locating pin to prevent excessive overall straightness tolerances during welding.
9. Process Improvement
Process improvement to prevent thinning of the wall thickness in the middle, increase the thickness beyond the control range, and improve the thickness accuracy.

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