Pipe wall thickness control is a difficult in steel pipe production, measures to improve the production of wall thickness precision mainly includes the following aspects:
1, Tube heating
Heat uniformly prohibit rapidly elevating temperature. Each heating and cooling to maintain a slow and steady, the maximum temperature does not exceed the lift 30 ℃.
2, Centering rollers
Determine whether the centering roller is mounted in place, adjust the roll core holding center, the opening angle of the opening movement and all the same size, hold the center of the core roll to the rolling line.
3, Rolling centerline
Ensure a consistent rolling piercer piercing car center line and the center line, to avoid "rolled on" or "rolling down" so that the tube holding force even when the perforation.
4, Rolling tool
For wear head, guide and roller rolling tool must be promptly replaced.
5, Rolling tool mounting
Roll from the center of the guide must be from the rolling line. Guarantee from the centerline of the guide rollers and in piercing and rolling from the center line, ie upper and lower rollers from equal distance about equal to the guide.
6, Piercing mandrel
Perforation jack usually selected outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm uniform thick-walled tube.
7, The mandrel mill
To choose the mandrel and the thick walled tube processing, the smaller size of the mandrel can be used instead of a solid billet. Uniform thickness of the thick-walled tubes and solid blanks, you can make the probability of a significant reduction in the mandrel bending deformation, can effectively improve the precision of the thickness of steel pipe.
8, Precision mandrel
Slenderness mandrel is relatively large, generally use the first car to break the outer diameter of the mouth and then welding, or using a long material directly Turning molding. Mandrel outer precision control ± 0.1mm, straight mandrel deviation of not more than 5mm. Welding, finishing a mandrel inserted between the two pins positioned to prevent welding caused the total straightness deviation is too large.
9, Process improvement
Process improvement, preventing intermediate pull thin wall thickness and increase Haou exceeds the control range of the occurrence and improve the thickness accuracy.