A first steel strip and a second steel strip (7) are rolled in succession in at least one roll stand (1) of a cold rolling mill. A rolling pause, in which no steel strip is rolled, is provided between the rolling of the first and the second steel strip (7). The first steel strip is fed over a first path starting from a first pay-off reel (2), and the second steel strip (7) is fed over a second path starting from the first pay-off reel (2), or from a second pay-off reel different from the first pay-off reel (2). The first steel strip is not heated as it is fed to the rolling mill (1), whereas, by contrast, the second steel strip (7) is heated. The second path is longer than the first path.

A method for operating a roll stand for the stepped rolling of metal strip is described. The metal strip is initially fed into a roll stand on the infeed side, where it is step-rolled. This creates a leading and a trailing section of the metal strip, each with different thicknesses. After the roll stand, the step-rolled metal strip initially passes through an outfeed-side strip accumulator before it is wound into a coil by an upcoiler. The outfeed-side reel is controlled to a constant strip tension. To keep the outfeed-side strip tension sufficiently constant even in the case of rapid changes in the size of the roll gap and the resulting rapid changes in thickness in the rolled metal strip the control of the strip tension with the aid of the upcoiler is supplemented by a position control for a roller unit in the outfeed-side strip accumulator.

An apparatus for controlling a strip tension during flexible rolling of metal strip comprises a roll arrangement with at least one dancer roll, the position of said dancer roll being adjustable for controlling the strip tension of the metal strip, at least one hydraulic drive coupled to the dancer roll for adjusting the dancer roll, a hydraulic tank for hydraulic fluid, which is fluidly connected to the hydraulic drive via a hydraulic supply line, a controllable valve arrangement between the hydraulic tank and the hydraulic drive for controlling the hydraulic drive, a hydraulic pump with which the hydraulic drive is supplied with hydraulic fluid from the hydraulic tank, and at least one hydraulic pressure accumulator for temporarily storing hydraulic fluid previously delivered by the hydraulic pump, the hydraulic pressure accumulator being arranged between the hydraulic pump and the valve arrangement, wherein a pressure sensor is arranged in the hydraulic drive for determining the hydraulic pressure.

A contactless braking system and a related method for decelerating long products (bi) exiting from a rolling mill (100). At least one braking module (6) includes a multiplicity of electromagnets (60) in a series along a braking line (1b). Each magnet has an open magnetic core (61) and a coil (62) around the magnetic core (61). The open magnetic core (61) has a gap formed by two opposed poles. The electromagnets (60) are configured so that the gap of each open magnetic core (61) lets contactlessly slide therethrough each long product (bi) exiting from the rolling mill (100). A braking magnetic force (Fd) is exerted on the long product (bi) contactlessly sliding through the gap. The braking magnetic force (Fd) is opposite to the direction of movement of the long product (bi) exiting the rolling mill (100).

Methods to drive material conditioning machines are described. An example method includes determining a first torque of a first roller of a material conditioning machine through which the strip material moves, calculating a second torque of a second roller of the material conditioning machine based on a relationship between the second torque and the first torque, and maintaining the relationship between the second torque and the first torque by adjusting the second torque after a change in the first torque.

The invention relates to a device for rolling, in particular for stepped rolling, of rolling stock with at least one pair of rolls and at least one linear drive arranged downstream of the pair of rolls in the rolling direction, which together with the pair of rolls can apply tensile stress to the rolling stock, and with means for detecting the tensile stress. In order to enable an improved method of flexibly rolling stock, the rolling device is characterized by means for detecting the tensile stress and by a control device for controlling the drive power of the linear drive as a function of the tensile stress detected, in order optionally to vary the tensile stress applied to the stock or to keep the tensile stress constant as the drive speeds behind the roll gap change. The invention also relates to a method of rolling the rolling stock using such a device.

The invention relates to a device for rolling, in particular for stepped rolling, of rolling stock with at least one pair of rolls and at least one linear drive arranged downstream of the pair of rolls in the rolling direction, which together with the pair of rolls can apply tensile stress to the rolling stock, and with means for detecting the tensile stress. In order to enable an improved method of flexibly rolling stock, the rolling device is characterized by means for detecting the tensile stress and by a control device for controlling the drive power of the linear drive as a function of the tensile stress detected, in order optionally to vary the tensile stress applied to the stock or to keep the tensile stress constant as the drive speeds behind the roll gap change. The invention also relates to a method of rolling the rolling stock using such a device.

A roll bending machine includes a roller unit and a tension device. The roller unit rolls and bends a strip member at a rolling rate varying in a width-wise direction of the strip member. The tension device applies tension to the strip member after being rolled by the roller unit in a rolling direction of the strip member, thereby reducing compressive stress which usually result in formation of wrinkles on the strip member. This minimizes the probability of formation of wrinkles on the strip member.

In a normal operation of a roll stand (e.g. 4) of a roll train, working rolls (10) of the roll stand (4) are adjusted to a roll gap (s4) by adjusting a control element position (p4) of a control element (14) of the roll stand (4), such that the working rolls (10) roll the metal band (5). To determine the control element position (p4) to be adjusted, a calibration value (sC4) of the respective roll stand (4), further status parameters (P4) of the roll stand (4) and a target roll gap (s4*) are specified to a model (15) of the roll stand (4). The model (15) determines the control element position (p4) to be adjusted therefrom. In the calibration operation, a control element position (p4) is initially adjusted such that the metal band (5) passes through the roll stand (4) without being rolled. The control element position (p4) is varied such that the working rolls (10) roll the metal band (5). A thickness (d) of the metal band (5) is detected by a downstream thickness-measuring device (9). The thickness (d), further status parameters (P4) and the control element position (p4) are supplied to the model (15), which determines the calibration value (sC4) of the respective roll stand (4) therefrom. Subsequently, normal operation is resumed and the previously determined calibration value (sC4) is used to determine control element positions (p4) to be adjusted as the calibration value (sC4) of the respective roll stand (4).

A variable thickness roll forming system for forming a variable thickness blank including at least two sets of cylindrical shaped rollers. Each of the sets of rollers include: a first roller including a face which is linear where the first roller contacts the metal sheet; and a second roller including multiple shaping faces positioned about a perimeter and directed toward the face of the first roller. Each roller set incrementally alters a thickness of a metal sheet in a direction transverse to a metal sheet feed direction when the metal sheet is passed between the first and second rollers. The metal sheet after passing between the first and second rollers forms a roll formed blank having a first portion and a second portion positioned in the direction transverse to the feed direction with respect to the first portion, the first portion thicker than the second portion.