A non-destructive method for determination of twist angle of an outlet product during rolling of an inlet product into said outlet product, comprising the steps of measuring a rotational inlet speed of the inlet product during said rolling, measuring a rotational outlet speed of the corresponding outlet product during said rolling in order to determine a delta rotation, measuring a longitudinal speed and determining a twist angle from said delta rotation and said longitudinal outlet and/or inlet speed.

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 stretch reducing rolling mill for rolling pipes has a plurality of roll stands arranged in series in a conveying direction of a pipe. A wall thickness measuring device determines a wall thickness progression of the pipe prior to rolling. A control unit controls respective rotational speeds of the roll stands. A pipe position measuring device is arranged in front of the roll stands and continuously measures a current longitudinal coordinate of the pipe. The measured values of the longitudinal coordinate of the pipe are transmitted to the control unit. The control unit controls the rotational speeds of the roll stands based on both the determined wall thickness progression and the transmitted measured values of the current longitudinal coordinate of the pipe, in order to compensate for wall thickness variations of the pipe. A stretch reducing rolling mill is designed to carry out the method.

A stretch reducing rolling mill for rolling pipes has a plurality of roll stands arranged in series in a conveying direction of a pipe. A wall thickness measuring device determines a wall thickness progression of the pipe prior to rolling. A control unit controls respective rotational speeds of the roll stands. A pipe position measuring device is arranged in front of the roll stands and continuously measures a current longitudinal coordinate of the pipe. The measured values of the longitudinal coordinate of the pipe are transmitted to the control unit. The control unit controls the rotational speeds of the roll stands based on both the determined wall thickness progression and the transmitted measured values of the current longitudinal coordinate of the pipe, in order to compensate for wall thickness variations of the pipe. A stretch reducing rolling mill is designed to carry out the method.

A method for producing a tube (101-104), the method comprising: providing a preform (1a-c, 70) in a mandrel (2), the preform (1a-1c, 70) having two ends; flow forming the preform (1a-c, 70) with a plurality of rollers (4-5,31-38) such that in one flow forming pass neither one of the two ends of the preform (1a-1c, 70) is flow formed, thereby producing the tube (101-104); and mechanically forming mechanical connection ends on the two ends of the tube (101-104). Also, a seamless tube (101-104), a pipeline comprising a plurality of seamless tubes (101-04), and a machine for flow forming a preform (1a-1c, 70) into a tube (101-104).

A method for producing a tube (101-104), the method comprising: providing a preform (1a-c, 70) in a mandrel (2), the preform (1a-1c, 70) having two ends; flow forming the preform (1a-c, 70) with a plurality of rollers (4-5,31-38) such that in one flow forming pass neither one of the two ends of the preform (1a-1c, 70) is flow formed, thereby producing the tube (101-104); and mechanically forming mechanical connection ends on the two ends of the tube (101-104). Also, a seamless tube (101-104), a pipeline comprising a plurality of seamless tubes (101-04), and a machine for flow forming a preform (1a-1c, 70) into a tube (101-104).

A rolling mill for rolling hollow or, in all cases, concave rod-shaped bodies, in particular tubes, in particular seamless tubes, said rolling mill comprising a rolling section (10) with a plurality of mill stands and/or rolling dies (11) arranged in succession to define a rolling axis Y, said rolling mill further comprising moving means for moving a mandrel (20) and a tubular blank (21) fitted onto an end portion (22) of said mandrel (20) along said rolling axis and through said mill stands or rolling dies (11) in succession; wherein said moving means are structured so as to move said mandrel (20) and said blank (21) along said rolling axis Y and through said mill stands or rolling dies (11) in succession by applying a traction on said mandrel.

A stretch reducing rolling mill for rolling pipes has a plurality of roll stands arranged in series in a conveying direction of a pipe. A wall thickness measuring device determines a wall thickness progression of the pipe prior to rolling. A control unit controls respective rotational speeds of the roll stands. A pipe position measuring device is arranged in front of the roll stands and continuously measures a current longitudinal coordinate of the pipe. The measured values of the longitudinal coordinate of the pipe are transmitted to the control unit. The control unit controls the rotational speeds of the roll stands based on both the determined wall thickness progression and the transmitted measured values of the current longitudinal coordinate of the pipe, in order to compensate for wall thickness variations of the pipe. A stretch reducing rolling mill is designed to carry out the method.

A cross-rolling mill for rolling a block over a mandrel forms a hollow block. It includes a plurality of working rollers, each of which exerts a substantially radially aligned rolling force onto the block. The working rollers are supported in a roll stand, and the gap between the working rollers and preferably also the alignment of the rolling axis of at least one of the working rollers relative to the block can be modified. Hydraulic actuators, preferably hydraulic capsules, are provided in order to modify the rolling gap and preferably also the alignment of the rolling axis of at least one of the working rollers relative to the block.

An apparatus for forming a round or oval shaped duct for all AC systems in one continuous operation where two driving rolls advance a flat metal sheet to at least one multi-positioning bending roll, where the at least one bending roll is moveable to a bending position for different curvatures and a non-bending position. The driving rolls advance the sheet through while the bending roll bends the sheet to form the curved sides, and the bending roll in the non-bending position form the flat sides of the oval shaped duct. A position sensor detects the position of the flat metal sheet in the rolls to control the location along the sheet where the bending roll is moved to either of the bending or non-bending positions while the driving rolls are stopped. An adhesive dispenser joins both ends of the sheet, resulting in a complete duct.