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.

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 device and method for producing an arc-shaped roll-formed part having an outer contour with a predetermined constant curvature and an inner contour with a varying curvature, having an outer contour with a varying curvature and an inner contour with a predetermined constant curvature, or having an outer contour with a varying curvature and an inner contour with a varying curvature. Circuitry obtains a third amount of movement corresponding to a sum of first and second amounts of movement of a bending roll as an amount by which the bending roll moves in a width direction during roll bending.

A device and method for producing an arc-shaped roll-formed part having an outer contour with a predetermined constant curvature and an inner contour with a varying curvature, having an outer contour with a varying curvature and an inner contour with a predetermined constant curvature, or having an outer contour with a varying curvature and an inner contour with a varying curvature. Circuitry obtains a third amount of movement corresponding to a sum of first and second amounts of movement of a bending roll as an amount by which the bending roll moves in a width direction during roll bending.

A rolling mill for solid elongated products, defining a rolling axis, including first and second rolling stations. Each station includes a load-bearing structure, a removable roll-holder cartridge with three rolling rolls movable radially and rotating around three equally spaced axes of rotation, and a roll having a vertical rotational axis. Three actuators mount on the load-bearing structure; three gear motor groups connect to the rolls by single extensions. The position of the second station rolls is rotated 60° from the first stations. The rolls with a vertical axis of the first and second stations are arranged on opposite sides of the rolling axis. All rolling stations allow lateral extraction of roll-holder cartridges from the same side of the rolling mill. The stations on the cartridge extraction side have actuators movable relative to the load-bearing structure. The stations with vertical rolls arranged on the opposite side have fixed actuators.

A rolling mill for solid elongated products, defining a rolling axis, including first and second rolling stations. Each station includes a load-bearing structure, a removable roll-holder cartridge with three rolling rolls movable radially and rotating around three equally spaced axes of rotation, and a roll having a vertical rotational axis. Three actuators mount on the load-bearing structure; three gear motor groups connect to the rolls by single extensions. The position of the second station rolls is rotated 60° from the first stations. The rolls with a vertical axis of the first and second stations are arranged on opposite sides of the rolling axis. All rolling stations allow lateral extraction of roll-holder cartridges from the same side of the rolling mill. The stations on the cartridge extraction side have actuators movable relative to the load-bearing structure. The stations with vertical rolls arranged on the opposite side have fixed actuators.

There are provided an electric resistance welded steel pipe for producing a high strength hollow stabilizer excellent in fatigue resistance and a high strength hollow stabilizer. In an electric resistance welded steel pipe (5) for producing a hollow stabilizer, an internal weld bead cut portion (30) has a three-peak shape and a depth (H) of a trough portion (30a) of the three-peak shape is 0.3 mm or less and an angle (θ) formed by a central portion in the circumferential direction of the trough portion (30a) and the top of right and left peak portions (30b, 30c) located on both the right and left sides of the trough portion (30a) is 160° or more and less than 180°.

There are provided an electric resistance welded steel pipe for producing a high strength hollow stabilizer excellent in fatigue resistance and a high strength hollow stabilizer. In an electric resistance welded steel pipe (5) for producing a hollow stabilizer, an internal weld bead cut portion (30) has a three-peak shape and a depth (H) of a trough portion (30a) of the three-peak shape is 0.3 mm or less and an angle (θ) formed by a central portion in the circumferential direction of the trough portion (30a) and the top of right and left peak portions (30b, 30c) located on both the right and left sides of the trough portion (30a) is 160° or more and less than 180°.

A rolling mill for solid elongated products, defining a rolling axis, including first and second rolling stations. Each station includes a load-bearing structure, a removable roll-holder cartridge with three rolling rolls movable radially and rotating around three equally spaced axes of rotation, and a roll having a vertical rotational axis. Three actuators mount on the load-bearing structure; three gear motor groups connect to the rolls by single extensions. The position of the second station rolls is rotated 60° from the first stations. The rolls with a vertical axis of the first and second stations are arranged on opposite sides of the rolling axis. All rolling stations allow lateral extraction of roll-holder cartridges from the same side of the rolling mill. The stations on the cartridge extraction side have actuators movable relative to the load-bearing structure. The stations with vertical rolls arranged on the opposite side have fixed actuators.