A method for producing hot-rolled, seamless pipes having at least one wall thickening which can be arranged at any positions over the length of the pipe, wherein by means of a multiple-stand mandrel bar rolling mill, the rolls roll a hollow shell on a mandrel bar as an inner tool to a required nominal wall thickness and produce at specified positions over the length of the pipe a required wall thickening on the outer side of the pipe by opening the rolls in the rolling stands. The thickened wall is produced and finish-rolled by two rolling stands that are consecutive as seen in the rolling direction, in which the deviations of the finished contour of the thickening from an ideal circular cross-section are minimised, wherein the rolling stands located upstream are likewise opened as to avoid any contact of the rolls of these rolling stands with the previously produced thickening.

The present invention relates to a method and an apparatus for changing the effective contour of a running surface (8) of a working roller (3, 4) during the hot rolling of rolling stock in a roll stand (2) to form a rolled strip (1). The intention is to be able to change the contour of the running surface (8) during the hot rolling by means of the invention. This object is achieved according to the invention by the axial displacement of the working rollers (3, 4) in opposite directions by a displacement distance s, wherein s is greater or less than

[00001]$\frac{\Delta r}{\tan \left(\alpha \right)}$

and Δr indicates the wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).

The invention concerns a method and a plant for producing flat rolled products, in order to obtain strips having a multiple crown transverse profile that subsequently have to be divided in a longitudinal direction into strips of a smaller width; the method provides a rolling step carried out in a rolling mill comprising roughing stands and finishing stands equipped with respective work rolls, in order to supply a strip of a determinate width.

A method for producing hot-rolled, seamless pipes having at least one wall thickening which can be arranged at any positions over the length of the pipe, wherein by means of a multiple-stand mandrel bar rolling mill, the rolls roll a hollow shell on a mandrel bar as an inner tool to a required nominal wall thickness and produce at specified positions over the length of the pipe a required wall thickening on the outer side of the pipe by opening the rolls in the rolling stands. The thickened wall is produced and finish-rolled by two rolling stands that are consecutive as seen in the rolling direction, in which the deviations of the finished contour of the thickening from an ideal circular cross-section are minimised, wherein the rolling stands located upstream are likewise opened as to avoid any contact of the rolls of these rolling stands with the previously produced thickening.

A roller stand (1) that has a roller stand frame (3) in which working rollers (4, 5), or working rollers (4, 5) and support rollers (8, 9), or working rollers (4, 5), intermediate rollers (10, 11), and support rollers (8, 9) are mounted. Each roller (4, 5, 8, 9, 10, 11) can be rotated about a respective rotational axis (6, 7). In a roller stand (1) without intermediate rollers (10, 11), the working rollers (4, 5) can be moved relative to one another in the direction of the respective rotational axis (6, 7), i.e. axially. In a roller stand (1) with intermediate rollers (10, 11), the same applies to the working rollers (4, 5) or the intermediate rollers (10, 11). Each of the axially movable rollers (4, 5 or 10, 11) has an effective barrel length (L) and a curved contour (R1, R2) which extends over the entire effective barrel length (L). Each of the axially movable rollers (4, 5 or 10, 11) has a contour (R1, R2) made by superimposing a respective base function (B1, B2) with a respective additional function (Z1, Z2). The base functions (B1, B2) and the additional functions (Z1, Z2) are functions of the location (x) in the direction of the respective rotational axis (6, 7). The base functions (B1, B2) are determined so as to complement each other in a specified relative axial position in an unloaded state of the axially movable rollers (4, 5 or 10, 11) and form a convex or concave roller gap profile depending on a movement direction upon being moved from the axial position. The sum of the additional functions (Z1, Z2) is a symmetrical function, which is monotonous on both sides, with respect to the barrel center of the axially movable rollers (4, 5 or 10, 11) in the unmoved state.

The invention concerns a method and a plant for producing flat rolled products, in order to obtain strips having a multiple crown transverse profile that subsequently have to be divided in a longitudinal direction into strips of a smaller width; the method provides a rolling step carried out in a rolling mill comprising roughing stands and finishing stands equipped with respective work rolls, in order to supply a strip of a determinate width.

A compensation method of an asymmetric strip shape of a strip rolling mill, for compensating the asymmetric strip shape of a strip caused in a machining process of the strip rolling mill in the prior art. The compensation method is realized by generating a non-linear asymmetric no-load roll-shaped profile curve through polishing an upper working roll and a lower working roll of a rolling mill and forming a non-linear asymmetric no-load roll gap between a transmission side and a working side of the upper and lower working rolls. The strip rolling mill in the prior art refers to a presently commonly used two-roll rolling mill driven by the transmission side of the working roll, a four-roll rolling mill equipped with a support roll and a multi-roll rolling mill equipped with a middle roll.

A roller stand (1) that has a roller stand frame (3) in which working rollers (4, 5), or working rollers (4, 5) and support rollers (8, 9), or working rollers (4, 5), intermediate rollers (10, 11), and support rollers (8, 9) are mounted. Each roller (4, 5, 8, 9, 10, 11) can be rotated about a respective rotational axis (6, 7). In a roller stand (1) without intermediate rollers (10, 11), the working rollers (4, 5) can be moved relative to one another in the direction of the respective rotational axis (6, 7), i.e. axially. In a roller stand (1) with intermediate rollers (10, 11), the same applies to the working rollers (4, 5) or the intermediate rollers (10, 11). Each of the axially movable rollers (4, 5 or 10, 11) has an effective barrel length (L) and a curved contour (R1, R2) which extends over the entire effective barrel length (L). Each of the axially movable rollers (4, 5 or 10, 11) has a contour (R1, R2) made by superimposing a respective base function (B1, B2) with a respective additional function (Z1, Z2). The base functions (B1, B2) and the additional functions (Z1, Z2) are functions of the location (x) in the direction of the respective rotational axis (6, 7). The base functions (B1, B2) are determined so as to complement each other in a specified relative axial position in an unloaded state of the axially movable rollers (4, 5 or 10, 11) and form a convex or concave roller gap profile depending on a movement direction upon being moved from the axial position. The sum of the additional functions (Z1, Z2) is a symmetrical function, which is monotonous on both sides, with respect to the barrel center of the axially movable rollers (4, 5 or 10, 11) in the unmoved state.

A compensation method of an asymmetric strip shape of a strip rolling mill, for compensating the asymmetric strip shape of a strip caused in a machining process of the strip rolling mill in the prior art. The compensation method is realized by generating a non-linear asymmetric no-load roll-shaped profile curve through polishing an upper working roll and a lower working roll of a rolling mill and forming a non-linear asymmetric no-load roll gap between a transmission side and a working side of the upper and lower working rolls. The strip rolling mill in the prior art refers to a presently commonly used two-roll rolling mill driven by the transmission side of the working roll, a four-roll rolling mill equipped with a support roll and a multi-roll rolling mill equipped with a middle roll.