Measures to improve the wall thickness accuracy of steel pipes

1. Tube blank heating

Heating shall be uniform, and rapid temperature rise and fall are prohibited. The temperature rise and fall shall be kept steady and slow each time, and the maximum temperature rise and fall shall not exceed 30C

2. Centering roll

Determine whether the centering roll is installed in place, adjust the center, opening angle and opening size of the relevant core holding roll to be consistent

The core roll center shall be on the rolling line.

3. Rolling center line

Ensure that the rolling center line of the piercer is consistent with the center line of the piercing trolley, and avoid "upper rolling" or "lower rolling". Make the tube blank threading

The force shall be uniform when drilling.

The worn plug, guide plate, roll and other rolling tools shall be replaced in time.

5. Rolling tool installation

The center of roll pitch and guide distance must be on the rolling line. Ensure that the center line of guide distance and roll distance is on the center line of piercing and rolling, i.e. up and down

The roll spacing is equal, and the left and right guide distances are equal.

6. Perforated ejector rod

Generally, thick wall pipes with a diameter of 108mm 1114mm, a wall thickness of>25mm and uniform wall thickness are selected as the piercing ejector

7. Mill mandrel

The mandrel shall be processed by thick wall tube with soft wall thickness. For the mandrel with smaller specification, solid blank can be used instead. Uniform wall thickness

The wall tube and solid blank of can greatly reduce the probability of mandrel bending deformation, and can effectively improve the wall thickness accuracy of steel tubes.

8. Accuracy of mandrel

The slenderness ratio of the mandrel is large. Generally, the outer diameter of the mandrel is turned first, then the opening is welded, or the mandrel is formed by direct turning of long materials. Mandrel

The external processing accuracy shall be controlled within ± 0.1m, and the straightness deviation of the mandrel shall not exceed 5mm. During welding, two sections of mandrel shall be inserted - one for finishing

The pins of shall be positioned to prevent excessive total straightness deviation caused by welding.

9. Ginger finishing process

Improve the process to prevent intermediate thinning and wall increase beyond the control range, and improve the wall thickness accuracy