Tube rolling plant

A method for rolling a seamless tube, the method comprising:

• rolling a semi-finished article with a mandrel in a main rolling mill to produce a semi-finished tube, wherein the main rolling mill includes a first plurality of rolls, each of the first plurality of rolls having adjustable radial positions;
• extracting the semi-finished tube from the mandrel, the extraction performed using a fixed-roll extracting/reducing mill positioned downstream to the main rolling mill;
• reducing the diameter of the semi-finished tube to a first predetermined value in the extracting/reducing mill, the first predetermined value being proximate to a desired final diameter of a completed version of the semi-finished tube;
• and
• calibrating the diameter of the semi-finished tube to a second predetermined value for a finished tube in a sizing mill positioned downstream to the extracting-reducing mill, wherein the sizing mill comprises a second plurality of rolls, each of the second plurality of rolls having adjustable radial positions.

A method for rolling a seamless tube, the method comprising:

• rolling a semi-finished tube with a mandrel in a first mill to produce a semi-finished tube, the first mill including a first plurality of rolls, each of the first plurality of rolls having adjustable radial positions, wherein the mandrel includes at least two sections, the mandrel held such that none of the mandrel's sections are subjected to the action of any two successive rolls;
• extracting the semi-finished tube from the mandrel, the extraction performed using a second mill positioned downstream to the first mill, the second mill including a second plurality of rolls, each of the second plurality of rolls having a fixed radial position;
• reducing the diameter of the semi-finished tube to a first predetermined value in the second mill, the first predetermined value being proximate to a desired final diameter of a completed version of the semi-finished tube;
• and
• further reducing the diameter of the semi-finished tube to a second predetermined value for a finished tube in a third mill positioned downstream to the second mill, wherein the third mill comprises a third plurality of rolls, each of the third plurality of rolls having adjustable radial positions, wherein the radial positions of the third plurality of rolls are adjustable according to a temperature of the semi-finished tube entering the third mill and according to a diameter of a completed version of the semi-finished tube leaving the third mill.