The disclosure relates to a method for controlling a stretch-reducing mill. Tube ends of stretched tubes are optimized by controlling one or more motors of the stretch-reducing mill. The method includes at least one outlet-side wall thickness measurement and an automatic adjustment of the value of a speed change of the motors to the tube wall thickness profile. The progression of the speed changes over time of individual or all motors is also automatically adjusted on the basis of the tube wall thickness measured values.

The disclosure relates to a method for controlling a stretch-reducing mill. Tube ends of stretched tubes are optimized by controlling one or more motors of the stretch-reducing mill. The method includes at least one outlet-side wall thickness measurement and an automatic adjustment of the value of a speed change of the motors to the tube wall thickness profile. The progression of the speed changes over time of individual or all motors is also automatically adjusted on the basis of the tube wall thickness measured values.

A controller (2) and method for controlling a stretch-reducing mill (1) for rolling tubes are presented. The stretch-reducing mill (1) has several roll stands (10) arranged behind one another in a conveying direction (F) of the tubes (R) and at least one outlet-side wall thickness measuring device (20). The controller (2) is set up to receive measurement data from the wall thickness measuring device (20) which identifies one or more outlet-side wall thicknesses (s.sub.r) of a tube (R) exiting from the last roll stand (10) and one or more of the received measurement data wall thickness on the inlet-side (s.sub.l_t), preferably to determine an inlet-side wall thickness profile of the tube (R) before entering the first roll stand (10), and preferably to calculate and control one or more of the roll stands (10), taking into account the determined inlet-side wall thicknesses (s.sub.l_t).

An electric resistance welded steel pipe having excellent formability and torsional fatigue resistance and a method for manufacturing the same. The electric resistance welded steel pipe includes a seam region and a base metal region, the seam region having a range of ±10 degrees in a pipe circumferential direction with respect to an electric resistance welded seam formed in a pipe longitudinal direction, the base metal region being a region other than the seam region. The electric resistance welded steel pipe has an r-value in the pipe longitudinal direction of 1.0 or greater, H (mm) and W (mm) satisfy a specified formula, and Ts.sub.(MAX) (mm) and Tb.sub.(Ave) (mm) satisfy a specified formula.

Metallic tubular products having improved collapse resistance are disclosed. The metallic tubular products are produced by compressive forming processes. 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 products are 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.

Metallic tubular products having improved collapse resistance are disclosed. The metallic tubular products are produced by compressive forming processes. 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 products are 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 rolling mill stand for rolling rod-shaped bodies, in particular tubular bodies, said stand comprising at least three rolls (10) mutually arranged to define a rolling pass line for said rod-shaped and/or tubular bodies, wherein at least one of said three rolls (10) is rigidly mounted on a roll holder shaft (20), freely fixed in turn in a rotational manner to said stand by means of a first hollow support (40) and a second hollow support (30) arranged on opposite sides of said at least one roll (10), respectively, wherein a first portion (21) and a second portion (22) of said roll holder shaft (20) are housed in said first hollow support (40) and in said second hollow support (30), respectively, where the constraint between at least said first hollow support and said first portion (21) of the roll holder shaft is of elastic type.

A rolling mill stand for rolling rod-shaped bodies, in particular tubular bodies, said stand comprising at least three rolls (10) mutually arranged to define a rolling pass line for said rod-shaped and/or tubular bodies, wherein at least one of said three rolls (10) is rigidly mounted on a roll holder shaft (20), freely fixed in turn in a rotational manner to said stand by means of a first hollow support (40) and a second hollow support (30) arranged on opposite sides of said at least one roll (10), respectively, wherein a first portion (21) and a second portion (22) of said roll holder shaft (20) are housed in said first hollow support (40) and in said second hollow support (30), respectively, where the constraint between at least said first hollow support and said first portion (21) of the roll holder shaft is of elastic type.

A controller (2) and method for controlling a stretch-reducing mill (1) for rolling tubes are presented. The stretch-reducing mill (1) has several roll stands (10) arranged behind one another in a conveying direction (F) of the tubes (R) and at least one outlet-side wall thickness measuring device (20). The controller (2) is set up to receive measurement data from the wall thickness measuring device (20) which identifies one or more outlet-side wall thicknesses (s.sub.r) of a tube (R) exiting from the last roll stand (10) and one or more of the received measurement data wall thickness on the inlet-side (s.sub.l_t), preferably to determine an inlet-side wall thickness profile of the tube (R) before entering the first roll stand (10), and preferably to calculate and control one or more of the roll stands (10), taking into account the determined inlet-side wall thicknesses (s.sub.l_t).

A method to improve the collapse resistance of metallic tubular products is disclosed. Stress is applied to the metallic tubular products in order to change the residual stress profile of the metallic tubular products, such as those that have completed a straightening process, resulting 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 applied after the tubular product has been subjected to a straightening process.