The present invention relates to a multi-stand rolling mill (1) for tubular bodies. The rolling mill comprises a first section (10) for rolling on mandrel defined by a first plurality of rolling stands (15, 15, 15) arranged in sequence along a rolling axis (100). According to the invention, the rolling mill also comprises a second rolling section without mandrel, arranged down-stream of said first section, which comprises a second plurality of stands (25, 25, 26, 27, 26, 27) arranged in sequence along said rolling axis (100). Each stand (25, 25, 26, 27, 26, 27) of said second section (20) comprises three rollers having rotation axes which are arranged at 120? from one another. The rotation axes for each stand (25, 25, 26, 27, 26, 27) are rotated by 180? with respect to corresponding rotation axes of an adjacent stand. According to the invention, at least one stand of said second section (20) comprises a motorized roller having a vertical rotation axis.

The present invention relates to a multi-stand rolling mill (1) for tubular bodies. The rolling mill comprises a first section (10) for rolling on mandrel defined by a first plurality of rolling stands (15, 15, 15) arranged in sequence along a rolling axis (100). According to the invention, the rolling mill also comprises a second rolling section without mandrel, arranged down-stream of said first section, which comprises a second plurality of stands (25, 25, 26, 27, 26, 27) arranged in sequence along said rolling axis (100). Each stand (25, 25, 26, 27, 26, 27) of said second section (20) comprises three rollers having rotation axes which are arranged at 120? from one another. The rotation axes for each stand (25, 25, 26, 27, 26, 27) are rotated by 180? with respect to corresponding rotation axes of an adjacent stand. According to the invention, at least one stand of said second section (20) comprises a motorized roller having a vertical rotation axis.

A method to improve the collapse resistance of metallic tubular products is disclosed. The method comprises identifying the types of stress that can be applied in order to change the residual stress profile of metallic tubular products, such as those that have completed a straightening process, and results in a residual stress profile that improves collapse resistance. The metallic tubular product is subjected to radial compression processing to control the residual stress profile and to enhance collapse resistance. The radial compression process may be used after the tubular product has been subjected to a straightening process.

A method to improve the collapse resistance of metallic tubular products is disclosed. The method comprises identifying the types of stress that can be applied in order to change the residual stress profile of metallic tubular products, such as those that have completed a straightening process, and results in a residual stress profile that improves collapse resistance. The metallic tubular product is subjected to radial compression processing to control the residual stress profile and to enhance collapse resistance. The radial compression process may be used after the tubular product has been subjected to a straightening process.

A manufacturing method of a seamless metal pipe includes determining whether a preceding-stage stand group is used in outer diameter reduction or in thickness reduction of a hollow shell; and performing elongating on the hollow shell, into which a mandrel bar is inserted, based on the determination. In addition, in the elongating, when the preceding-stage stand group is used in the outer diameter reduction, the hollow shell is rolled in a state where an inner surface of the hollow shell does not come into contact with the mandrel bar in the preceding-stage stand group, and the hollow shell is rolled in a state where the inner surface of the hollow shell comes into contact with the mandrel bar in the succeeding-stage stand group.

A roll-holder cartridge for a three-tube rolling stand with means adapted to release a tube during rolling in case of emergency. The roll-holder cartridge (3) has on both side walls a substantially Y-shaped opening (10) laying with the foot at the vertical axis yoke support so as to be able to pull out the roll-holder cartridge according to a direction coinciding with the horizontal axis of the vertical axis yoke while leaving the support hanging from the fixed structure (13) of the rolling stand. In case of normal maintenance operation, the cartridge (3) is pulled out sideways from the structure of the rolling mill with the yoke support of the vertical axis roll anchored to the cartridge itself, like the other supports of the rolls.

A roll-holder cartridge for a three-tube rolling stand with means adapted to release a tube during rolling in case of emergency. The roll-holder cartridge (3) has on both side walls a substantially Y-shaped opening (10) laying with the foot at the vertical axis yoke support so as to be able to pull out the roll-holder cartridge according to a direction coinciding with the horizontal axis of the vertical axis yoke while leaving the support hanging from the fixed structure (13) of the rolling stand. In case of normal maintenance operation, the cartridge (3) is pulled out sideways from the structure of the rolling mill with the yoke support of the vertical axis roll anchored to the cartridge itself, like the other supports of the rolls.

A method and a device for releasing a tube during a rolling process in a three-roll rolling stand in case of an emergency. The roll holder cartridge (3) has a longitudinal open slot (10) at the yoke support of the vertical axis roll so as to remove the roll holder cartridge according to a direction coinciding with the horizontal axis of the yoke support of the vertical axis roll while the support remains anchored to the fixed structure in the stand of the roll mill. In case of routine maintenance, the cartridge (3) is pulled out laterally with the yoke support of the vertical axis roll anchored to the cartridge itself as the other roll supports.

Apparatus to detect a deformity in thickness of a tubular element. The apparatus comprises a plurality of sensors and is installed in at least a rolling stand, having at least three rolling rings, of a rolling train able to obtain said tubular element.

Apparatus to detect a deformity in thickness of a tubular element. The apparatus comprises a plurality of sensors and is installed in at least a rolling stand, having at least three rolling rings, of a rolling train able to obtain said tubular element.