DECOILING OF A COILED STRIP

Abstract

An unwinding device (1) for unwinding a strip (5) which had been wound to form a coil (3), in order for the unwound strip (5) to be hot-rolled. The unwinding device (1) has at least two bottom rollers (7) for supporting the coil (3) on the lower side of the coil, a detaching mechanism (9) for detaching a strip end (11) from the coil (3) on an unwinding side of the coil, and a downholder roller (13), (14) which is disposed at the coil (3) such that the downholder roller (13), (14) stabilizes the position of the coil (3) when the strip end (11) is being detached.

Description

TECHNICAL FIELD

The invention relates to an unwinding device and to a method for unwinding a strip of metal which has been wound to form a coil, in order for the strip to be hot-rolled.

TECHNICAL BACKGROUND

In hot-rolling plants, pre-rolled strips are often wound to form a so-called coil. In order for the strips to be wound and/or unwound, winding and/or unwinding devices, which are also referred to as coiling boxes, are used. Hot-rolling plants having coiling boxes offer advantages in terms of the temperature, rolling speed, and rolling force which remain constant across the strip length. On the one hand, increasingly stronger material is being produced by hot-rolling, and the maximum strip thickness, in particular for tube grades, is being increased, on the other hand. One method for increasing the strength and tenacity of the material lies in thermo-mechanical rolling, for example, in which rolling is performed at very low temperatures in a finishing mill. Due to the increase in terms of strength and thickness, and/or in terms of the reduction in the temperature of the strips, there is an increasing demand for winding and/or unwinding thicker, colder, and stronger pre-strips in a coiling box.

DE 10339191 A1 discloses a method and a device for expanding the application of a winding and unwinding station (coiling box) between the roughing mill and the finishing mill for rolled strip material in hot-rolling works. It is inter alia proposed herein for the treatment of lower coil weights that a contact pressure which is directed toward the roller conveyor is forced upon the coil to be unwound in a mandrel-free coiling box.

JP H07 148522 A discloses a winding device for unwinding a coil, having a contact-pressure device for providing contact pressure to the coil.

SUMMARY OF THE INVENTION

The invention is based on the object of stating an improved unwinding device for unwinding a strip which has been wound to form a coil, in order for the strip to be hot-rolled. Furthermore, the invention is based on the object of stating an improved method for unwinding a strip which has been wound to form a coil, in order for the strip to be hot-rolled.

An unwinding device according to the invention for unwinding a strip which has been wound to form a coil, in order for that strip to be hot-rolled, comprises at least two bottom rollers for supporting the coil on the lower side, a strip-end detaching mechanism for detaching a strip end from the coil on an unwinding side, and a downholder roller which is disposed on the coil in such a manner that the downholder roller stabilizes the position of the coil when the strip end is being detached.

The downholder roller herein is disposed at a fixed spacing from an external surface of the coil.

An unwinding device of this type advantageously makes it possible to prevent or to restrict a positional displacement of the coil that may arise when the strip end is being detached from the coil. Positional displacements of the coil of this type in particular exist in a coil of relatively strong, thick, and/or cool strips being lifted from the bottom rollers when the strip end is being detached from the coil when the force-engagement point lies outside a region which is supported by the bottom rollers. The invention prevents or reduces positional displacements of this type in a simple and cost-effective manner by way of a downholder roller which is disposed on the coil, thus enabling risk-free unwinding of strips from a high-strength material, of cool strips, and of thick strips. By disposing the downholder roller at a fixed spacing from an external surface of the coil, a positional variation of the coil which displaces the coil beyond the spacing from the downholder roller is advantageously avoided.

One design embodiment of the invention provides that the downholder roller is disposed on an upper side of the coil.

An alternative design embodiment of the invention provides that the downholder roller is disposed on the unwinding side on the coil.

In the case of the two aforementioned design embodiments of the invention, the downholder roller is disposed above or on the unwinding side of the coil such that the downholder roller may advantageously prevent positional displacements of the coil that may arise when the strip end is being detached from the coil.

One further design embodiment of the invention provides that the longitudinal axes of the downholder roller and of the bottom rollers are disposed so as to be mutually parallel.

On account thereof, the downholder roller and the bottom rollers in an advantageous manner are of identical mutual alignment such that the longitudinal axes thereof run in the same direction as a winding axis of the coil.

In the method according to the invention for unwinding a strip which has been wound to form a coil, the coil on the lower side is supported by means of at least two bottom rollers, a strip end on an unwinding side is detached from the coil by means of a strip-end detaching mechanism, and a downholder roller is disposed at the coil in such a manner that the position of the coil is stabilized when the strip end is being detached. The downholder roller herein is disposed at a fixed spacing from an external surface of the coil.

Due to the advantages which have already been mentioned above, the method prevents or reduces positional displacements of the coil that may arise when the strip end is being detached from the coil.

Design embodiments of the method correspond to the design embodiments of the unwinding device according to the invention, offering the advantages which have already been mentioned above. These design embodiments provide that the downholder roller is disposed on an upper side of the coil, or on the unwinding side on the coil, and/or that the longitudinal axes of the downholder roller and of the bottom rollers are disposed so as to be mutually parallel, and/or that the downholder roller is disposed at a fixed spacing from an external surface of the coil.

The above-described properties, features, and advantages of this invention, and the manner by way of which the former are achieved, will be more clearly and better understood in conjunction with the following description of an exemplary embodiment which will be explained in more detail in conjunction with a drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The single FIGURE schematically shows a side view of an unwinding device for unwinding a strip which has been wound to form a coil, in order for the strip to be hot-rolled.

DESCRIPTION OF AN EMBODIMENT

The unwinding device 1 comprises two bottom rollers 7 for supporting the coil 3 on the lower side, a strip-end detaching mechanism 9 for detaching a strip end 11 from the coil 3 on an unwinding side, and a downholder roller 13 which is disposed on the coil 3 in such a manner that the downholder roller 13 stabilizes the position of the coil 3 when the strip end 11 is being detached.

In the exemplary embodiment which is illustrated in the FIGURE, a downholder roller 13 may be disposed at an upper side of the coil, so as to be at a fixed spacing from an external surface of the coil. Alternatively, a downholder roller 14 may be disposed at the unwinding side 15 of the coil 3, as shown in broken line. The downholder roller 13 or 14 is normally out of contact with the coil and contacts the coil when the strip end is detached, so that the downholder roller serves as a mechanical stop for the coil.

The longitudinal axes of the downholder roller 13, 14 and of the bottom rollers 7 are disposed so as to be mutually parallel. The strip-end detaching mechanism 9 is configured as a pivotable arm. Mountings of the downholder roller 13, 14 in the gap between the coil and the strip-end detaching mechanism 9 are not illustrated. The downholder roller is held at a fixed spacing from the external surface of the coil.

Furthermore, there are transfer rollers 15 and two drive rollers 17 for conveying the unwound strip 5. The drive rollers 17 are disposed on top of one another. The strip 5 is guided by way of the transfer rollers 15 to the drive rollers 17 and is pulled through between the drive rollers 17.

While the invention has been illustrated and described in more detail by way of preferred exemplary embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by a person skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE SIGNS

1 Unwinding device

3 Coil

5 Strip

7 Bottom roller

9 Strip-end detaching mechanism

11 Strip end

13 Downholder roller

15 Transfer roller

17 Drive roller

Claims

1.-4. (canceled)

5. A method for unwinding a strip which had been wound to form a coil, the method comprising: supporting the coil on the lower side below the coil by at least two bottom rollers;detaching a strip end from the coil on an unwinding side of the coil by a strip-end detaching mechanism; anddisposing a downholder roller at a fixed spacing from an external surface of the coil in a manner to stabilize the position of the coil when the strip end is being detached.

6. The method as claimed in claim 5, further comprising disposing the downholder roller at an upper side of the coil.

7. The method as claimed in claim 5, further comprising disposing the downholder roller at the unwinding side on the coil.

8. The method as claimed in claim 5, further comprising disposing respective longitudinal axes of the downholder roller and of the bottom rollers to be mutually parallel.