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Measures to improve the wall thickness accuracy of seamless steel tubes
- Apr 09, 2018 -

The control of steel seamless tube wall thickness is a difficulty in  seamless steel tube production. Measures to improve wall thickness accuracy of seamless steel pipe in production include the following aspects.

1,Seamless tube billet heating

The heating should be uniform and the rapid rise and fall temperature is prohibited. Every time, the temperature should keep steady and slow, and the maximum lifting temperature is no more than 30 degrees.

2. Centering roll

Determine whether the center of the centering roll is in place, adjust the center of the cored roller, open the angle and the size of the opening of each movement, and the center of the core roller should be on the rolling line.

3. Rolling center line

Make sure that the central line of the piercing mill is consistent with the central line of the perforated car, so as to avoid "rolling up" or "rolling down", so as to keep the seamless tube blank evenly perforated.

4. Rolling tools

The worn tools such as plug, guide plate and roller should be replaced in time.

5. Rolling tool installation

The center of the roll distance and guide distance must be on the rolling line. The center line that ensures the distance between guide and roll is equal in the center of piercing rolling, that is, the distance between upper and lower rolls is equal, and the distance between left and right guides is equal.

6. Perforated top rod

Piercing bar generally choose 108mm- in outer diameter 114mm, wall thickness is more than 25mm and the requirements of thick walled tube wall thickness.

7. Mill mandrel

The mandrel should be made of thick walled seamless tube with thick wall thickness. For solid mandrel with smaller specification, solid billet can be used instead. Thick wall seamless tube and solid billet with uniform wall thickness can greatly reduce the probability of bending deformation of mandrel, and effectively improve the accuracy of wall thickness of steel seamless tube.

8, The precision of the mandrel

The mandrel's slenderness is relatively large. Generally, the outer diameter of the first car is then welded, and the long material is directly turned to form. The accuracy of external machining of mandrel is controlled at + 0.1mm, and the straightness deviation of mandrel is no more than 5mm. When welding, a finishing pin is inserted between the two segments of the mandrel so as to prevent the total straightness deviation caused by welding is too large.

9, Perfect the process

To improve the process, prevent the occurrence of the middle and thin wall thickness increased more than Haou control range, improving wall thickness accuracy of seamless pipes.