Straight seam steel pipe wall thickness control is a difficult production. At present, the straight seam steel pipe manufacturers to improve the wall thickness in the production of precision uses the methods generally including:
1, Tube heating
Heating to the average to prevent rapid up and down temperature. Each take-off and landing temperature is to maintain a smooth slow, the maximum rise and fall temperature does not exceed 30 ℃.
2, Rolling mill mandrel
Average wall thickness of thick wall tube and solid billet make the probability of mandrel bending deformation significantly reduced, can effectively improve the wall thickness of the precision.
3, The accuracy of mandrel
The outer core of the machining accuracy control in ± 0.1mm, mandrel straightness bias does not exceed 5mm. Welding, the two core rods between the piercing a finishing pin positioning, welding in order to avoid the formation of the total straightness bias is too large.
4, The perfect process
Determing whether the centering roll device in place, adjust the relevant core roller in the middle, open the angle and the size of the initiative of the same opening, the middle of the rolling core in the rolling line.
5, Centering roller
Perfect process is to avoid the center pull thin and wall thickness beyond the control limitations of the state of attack, improve wall thickness accuracy.
6, Perforated mandrel
General choice of perforated mandrel diameter Φ108mm-Φ114mm, wall thickness requirements ≥ 25mm and wall thickness of the average thick-walled tube.
7, Rolling the middle line
Making sure that the middle line of the piercing mill is consistent with the middle line of the piercing trolley to prevent "upper rolling" or "lower rolling", so that the billet sticks to the average force during the piercing.
8, Rolling things
On the wear of the head, guide, roll and other rolling things to be real-time change.
9, Rolling things device
Roller distance, the distance must be in the middle of the rolling line. Guaranteed the distance between the guide and the middle of the roller in the middle of the piercing rolling, the upper and lower roller equal to the left and right lead from the same.