WO2021175636A1

WO2021175636A1 - Roll stand

Info

Publication number: WO2021175636A1
Application number: PCT/EP2021/054323
Authority: WO
Inventors: Markus Koch; Martin Oppermann; Martin Schmidt
Original assignee: Sms Group Gmbh
Priority date: 2020-03-06
Filing date: 2021-02-22
Publication date: 2021-09-10
Also published as: DE102020211770A1

Abstract

The invention relates to a roll stand (1), in particular for flexibly rolling strip material, comprising at least two working rollers (2, 3), which can be adjusted relative to one another by means of a hydraulic assembly in order to set a roll gap (4), wherein the hydraulic assembly comprises at least one hydraulic adjusting unit (5), wherein the hydraulic adjusting unit (5) has at least one cylinder (6), in which a piston (7) is moveably arranged, wherein the piston (7) divides the cylinder (6) into a first hydraulic chamber (8) and a second hydraulic chamber (9), wherein the flow of hydraulic oil into the first hydraulic chamber (8) is controlled in an open-loop or closed-loop manner by means of a first hydraulic valve assembly (10). In order to achieve an accurate setting of the roll gap, even with wear in the hydraulic valve assembly, the invention proposes that the first hydraulic valve assembly (10) is designed as an assembly with a simply operating valve controller.

Description

Roll stand

The invention relates to a roll stand, in particular for the flexible rolling of strip material, with at least two work rolls which can be adjusted relative to one another for setting a roll gap by means of a hydraulic arrangement, the hydraulic arrangement comprising at least one hydraulic adjustment unit, the hydraulic adjustment unit having at least one cylinder, in which a piston is displaceably arranged, the piston dividing the cylinder into a first hydraulic chamber and a second hydraulic chamber, the flow of hydraulic oil into the first hydraulic chamber being controlled or regulated by means of a first hydraulic valve arrangement.

A generic roll stand is known from WO 2019/215197 A1. The aim here is to provide such a hydraulic system that allows a variable and highly dynamic setting of the roll gap with high positioning accuracy. To achieve this, a relatively complex hydraulic control system with two hydraulic valve assemblies coupled to one another is proposed, the two valve assemblies being connected to both the first and second hydraulic chambers for double-acting actuation of the piston-cylinder system.

This previously known concept for the hydraulic control of the hydraulic adjustment units is not only relatively complex and therefore cost-intensive. A further disadvantage here is that the pressure conditions in the hydraulic system change in the event of wear in the hydraulic valve arrangement in such a way that it is no longer possible to adjust the rolls in the roll stand in a sufficiently reproducible manner. In this case, the system behavior depends on the wear and tear, which has a very negative impact, especially under the aspect that stable operation is required, which is then no longer guaranteed. The invention is based on the object of developing a roll stand of the type mentioned at the outset in such a way that it can be ensured that the roll gap can be set precisely even if there are signs of wear, in particular in the hydraulic valve arrangement. A cost-effective solution is sought. Furthermore, the hydraulic rigidity of the piston-cylinder system should be reproducible even when it is worn.

The solution to this object by the invention is characterized in that the first hydraulic valve arrangement for the first hydraulic chamber is designed as an arrangement with a single-acting valve control.

Accordingly, the first hydraulic chamber is controlled by the first hydraulic valve arrangement in the form of a single-acting valve control (see FIG. 2 in this regard).

The first hydraulic valve arrangement preferably has no connection to the second hydraulic chamber. Accordingly, the control of the second hydraulic chamber takes place independently of the control of the first hydraulic chamber (see FIGS. 5, 6, 7 and 8 in this regard).

According to one embodiment of the invention, the second hydraulic chamber can be connected to a hydraulic pressure source with which it can be acted upon with a predetermined hydraulic pressure, in particular with a constant pressure.

As an alternative to this, however, it is also possible for the hydraulic oil to flow into the second hydraulic chamber by means of a second hydraulic valve arrangement, the second hydraulic valve arrangement being designed as an arrangement with a single-acting valve control. This allows the hydraulic preload to be set to a desired level in an advantageous manner. A force directed towards the roll gap can be applied to the two work rolls by means of two further rolls, in particular by means of two backup rolls, the further rolls being acted upon by the at least one hydraulic adjusting unit.

The two work rolls can also be subjected to a bending moment by means of a bending or balancing system, this having further hydraulic adjustment units with respective further cylinders and further pistons, the further piston moving the further cylinder into a further first hydraulic chamber and a further second The hydraulic chamber is divided, the flow of hydraulic oil into the further first hydraulic chamber being controlled or regulated by means of a further hydraulic valve arrangement and the further hydraulic valve arrangement being designed as an arrangement with a single-acting valve control.

It is also possible for several hydraulic adjustment units to be arranged so as to act in parallel.

Furthermore, several hydraulic valve arrangements (of the same or different nominal size) can be arranged acting in parallel and jointly supply a hydraulic chamber with hydraulic oil.

A pressure accumulator and / or a pressure reducer can be arranged in the hydraulic flow path to the second hydraulic chamber.

Furthermore, it can be provided that a damping unit is arranged in the hydraulic flow path of the system pressure supply and / or the return line of the first and / or second hydraulic valve arrangement, this preferably having a hydraulic damper or accumulator. Additional components for damping and pre-tensioning can also be provided as an option. The hydraulic adjustment unit can also have a flushing control, by means of which the two hydraulic chambers can be hydraulically connected to one another or to the return line. With the proposed single-acting valve control (also referred to as single-edge control) in the hydraulic valve arrangement, there is a functional separation with regard to the application of the two hydraulic chambers. The two hydraulic chambers can thus be acted upon with hydraulic oil independently of one another

The present invention thus proposes a simplified hydraulic concept for a roll stand and specifically for its hydraulic adjustment units, with which the roll gap can nevertheless be set precisely and flexibly to a desired dimension. This enables flexible rolling of strip material.

Even if the hydraulic valve arrangements in particular are worn, it is ensured that the pressure ratios in the piston-cylinder system can be set in a reproducible manner. Furthermore, the hydraulic rigidity of the adjustment system can be influenced in a simple manner if wear occurs. This means that the system behavior is no longer dependent on valve wear.

In the previously known double-acting valve arrangement (also referred to as two-edge or multi-edge control), there are in particular problems that can arise due to cavitation when external interfering influences occur. This problem no longer arises with the proposed solution.

Relatively simple and inexpensive components can thus be used, which nevertheless ensure stable operation. According to an advantageous development, the use of the flushing control mentioned for the hydraulic adjustment unit and the use of the Pulsation damping is provided in the pressure line or tank line, so that flexible rolling is promoted.

Exemplary embodiments of the invention are shown in the drawing. Show it:

1 schematically shows a roll stand, with hydraulic adjustment units being shown, with which both the backup rolls (with a force directed towards the roll gap) and the work rolls (with a bending moment) are acted upon,

2 schematically shows a hydraulic adjustment unit, the supply of a first fly hydraulic chamber with hydraulic oil being shown, for which a hydraulic valve arrangement with a single-acting valve control is used,

3 schematically shows the supply of the first hydraulic chamber with several hydraulic valve arrangements arranged parallel to one another with single-acting valve control, FIG. 4 schematically shows a known piston-cylinder system with a hydraulic valve arrangement with single-acting valve control,

5 schematically shows a hydraulic adjustment unit, the supply of a second hydraulic chamber with hydraulic oil being shown,

6 shows an alternative to the supply according to FIG. 5 with a pressure reducer,

7 shows an alternative to the supply according to FIG. 6 with the possibility of setting a variable pressure, 8 shows an alternative to the supply according to FIG. 5, a hydraulic valve arrangement with a single-acting valve control being used (several such valve arrangements are also possible), FIG. 9 an alternative to the supply according to FIG. 2, using a hydraulic damping unit,

Fig. 10 to Fig. 12 three variants of a hydraulic circuit with which flushing can be made.

In Figure 1, a roll stand 1 is indicated, which has two interacting work rolls 2 and 3, between which a roll gap 4 is formed in order to roll in this rolling stock. The two work rolls 2 and 3 are supported by backup rolls 12 and 13.

To adjust the rolls and thus to define the roll gap 4, the backup rolls 12 or 13 are provided with hydraulic adjusting units 5 on both roll sides. These have a cylinder 6 in which a piston 7 is displaceably arranged. Accordingly, two hydraulic chambers are formed in the cylinder, namely a first hydraulic chamber 8 and a second hydraulic chamber 9. The force generated is denoted by Fa in FIG. Likewise, the work rolls 2, 3 are provided with respective hydraulic adjustment units 5, which, however, serve here to apply a bending moment to the rolls. The hydraulic adjusting units 5 are thus part of known roller bending or balancing systems. Here, two or more adjusting units are provided per roll side. The force generated in this way is denoted by Fb in FIG. 1. The first hydraulic chamber 8 is connected to a hydraulic line, which is designated in FIG. 1 by “cylinder side 1”. The second hydraulic chamber 9 is correspondingly connected to a hydraulic line, which is designated in FIG. 1 by “cylinder side 2”.

The supply of hydraulic oil to the first hydraulic chamber 8 is shown in FIG. It is shown here how hydraulic oil is made _{available under pressure from a hydraulic pressure source Ps yst} , that is to say from a pump, and how this is passed into the first hydraulic chamber 8. A first hydraulic valve arrangement 10 is provided for this purpose.

It is essential that this first hydraulic valve arrangement 10 is designed as an arrangement with a single-acting valve control. For a configuration in this regard, reference is made to the above statements and to FIG. 4, in which such a hydraulic control is sketched, which is known as such in the prior art.

In Figure 4, three partial images of a single-acting valve control are shown, namely the hydraulic circuit symbol (left), the functional mode of operation (middle) and schematically the structural design of such a valve (right). The movement of the piston 7 in the cylinder 6 is controlled by a single-acting control valve with an active control edge in the covered adjusting range of the control piston, which is part of the hydraulic valve arrangement 10.

The single-acting valve control used according to the invention is therefore known as such in the prior art. The hydraulic oil flow is controlled in the covered actuating range of the control piston using a single active control edge. As can be seen from Figure 3, several single-acting control valves (hydraulic valve assemblies 10) of the same or different nominal size, each with an active control edge in the covered actuating area of the control piston, can be used, these being arranged parallel to one another, as shown in the figure.

The supply of the second fly hydraulic chamber 9 with hydraulic oil is shown in four alternative configurations in FIGS. In FIG. 5 it can be seen that the second hydraulic chamber 9 is directly connected to the hydraulic pressure source Ps _ys t, ie with a hydraulic pump, and is supplied with hydraulic oil by this. The hydraulic oil is kept under the given system pressure Psyst. After the piston area in the first hydraulic chamber 8 is larger than the piston area in the second hydraulic chamber 9 (since the area of the piston rod must be deducted here), a movement of the piston 7 in the cylinder 6 can also take place if the first hydraulic chamber 8 with the system pressure Psyst is applied.

In FIG. 5 it can also be seen that a pressure accumulator or a hydraulic damper 14 is arranged in the hydraulic line to the second hydraulic chamber 9, which ensures that the pressure is equalized or smoothed.

According to the solution according to FIG. 5, the system pressure is applied directly to the second hydraulic chamber 9.

A solution is sketched in FIG. 6 in which the pressurized second hydraulic chamber 9 takes place with a constant pressure which is reduced (compared to the system pressure from the hydraulic pressure source Psyst). For this purpose, a pressure reducer 15 is arranged in the line. The pressure which is kept constant here and which is applied to the second hydraulic chamber 9 is therefore below the system pressure. A solution similar to this can be seen in FIG. 7, the difference to FIG. 6 here being that the second hydraulic chamber 9 is acted upon by a variable and adjustable constant pressure.

Optionally, a pressure accumulator or a hydraulic damper 14 can also be used again in these solutions, as shown in FIGS. 6 and 7.

A particularly preferred embodiment of the invention is shown in FIG. 8, according to which it is provided that the second hydraulic chamber 9 is also acted upon with a dynamically controllable pressure. For this purpose, a second hydraulic valve arrangement 11 is provided in the supply line to the second hydraulic chamber 9, which, just like the first hydraulic valve arrangement 10, is one with a single-acting valve control.

In Figure 9 it is illustrated that pulsation damping can also be used, which is outlined here in the hydraulic flow path for the system pressure supply and the return line of the first valve arrangement 10 for the first hydraulic chamber 8, but is also provided for the hydraulic connection of the second hydraulic chamber 9 can. After this, a damping unit 16 is arranged in the hydraulic line, the more detailed structure of which is sketched in the right partial image in FIG. According to this, the damping unit 16 has a hydraulic damper or reservoir 17 with which the pressure can be smoothed.

Thus, a damping unit is provided in the system pressure supply and / or return line, which is connected with its connection A to the fluid-dynamically disruptive subsystem and with its connection B to the damped subsystem. Additional components for damping and pre-tensioning the pressure, such as throttles, orifices and pre-tensioning valves, can be provided as an option. FIGS. 10 to 12 illustrate how a flushing control can be designed in which hydraulic oil can be passed through the system in order to flush it.

FIG. 10 illustrates the possibility of short-circuiting the two hydraulic chambers 8 and 9 here. For this purpose, a connecting line 18 is provided in the vicinity of the cylinder, in which an adjustable hydraulic resistance 19 (throttles, diaphragm) is arranged, with which the connecting line 18 can be blocked or released. For flushing, the hydraulic resistance 19 is switched to pass so that the hydraulic oil can circulate.

In the solution according to FIG. 11, the connecting line 18 is placed directly in the piston 7, including the hydraulic resistance 19 which is also provided here, although it is adjustable but rather kept constant; accordingly, the two cylinder sides “1” and “2” can be short-circuited here in order to carry out a flushing process.

In FIG. 12, a further solution is finally sketched, according to which a circulation control of the cylinder sides “1” and “2” is provided. For this purpose, two flushing lines 20 are provided, which are connected to the inflow line “1” below the cylinder (the same applies to the outflow line “2”) and into which hydraulic resistors 19 (throttle, orifice) are installed. The flushing lines 20 are blocked or released via switchable valves 21. The flushing function is thus activated or blocked with the latter.

With the hydraulic actuation of the adjusting unit 5 designed in this way, there are significant advantages: Due to the single-acting valve control, the speed gain of the positioning system is lower and thus the resolution and the positioning accuracy are higher. The pressure level in the cylinder system is reproducible regardless of valve wear; the same applies to the hydraulic stiffness of the system.

The control system can better compensate for valve wear so that the components have a longer service life. An inexpensive design can also be implemented.

Both the pressure level in the second hydraulic chamber (through which the restoring force is generated) and the rigidity of the hydraulic adjustment system can be freely selected. This allows the preload and rigidity of the cylinder system to be adapted to the required conditions. The preload and the rigidity of the hydraulic adjustment system can thus also be freely selected, since the two hydraulic chambers can be controlled independently. This also means that cavitation and diesel effects can be counteracted on the passive side.

List of reference symbols:

1 roll stand

2 work roll 3 work roll

4 roll gap

5 hydraulic adjustment unit

6 cylinder 7 piston 8 first hydraulic chamber

9 second hydraulic chamber

10 first hydraulic valve arrangement 11 second hydraulic valve arrangement 12 roller (support roller) 13 roller (support roller)

14 pressure accumulator / hydraulic damper

15 pressure reducers

16 Damping unit 17 Hydraulic damper / accumulator 18 Connection line

19 hydraulic resistance

20 flushing line 21 switchable valve Psyst hydraulic pressure source tank hydraulic tank

Claims

Patent claims:

1. Roll stand (1), in particular for the flexible rolling of strip material, with at least two work rolls (2, 3) which can be adjusted relative to one another for setting a roll gap (4) by means of a hydraulic arrangement, the hydraulic arrangement having at least one hydraulic adjustment unit (5 ), the hydraulic adjusting unit (5) having at least one cylinder (6) in which a piston (7) is slidably arranged, the piston (7) moving the cylinder (6) into a first hydraulic chamber (8) and into a second hydraulic chamber (9), the flow of hydraulic oil into the first hydraulic chamber (8) being controlled or regulated by means of a first hydraulic valve arrangement (10), characterized in that the first hydraulic valve arrangement (10) is designed as an arrangement with single-acting valve control is.

2. Roll stand according to claim 1, characterized in that the first hydraulic valve arrangement (10) has no connection to the second hydraulic chamber (9).

3. Roll stand according to claim 1 or 2, characterized in that the second hydraulic chamber (9) is connected to a hydraulic pressure source (Ps _yst ) with which it can be subjected to a predetermined hydraulic pressure, in particular a constant pressure.

4. Roll stand according to claim 1 or 2, characterized in that the flow of hydraulic oil into the second hydraulic chamber (9) takes place by means of a second hydraulic valve arrangement (11), the second hydraulic valve arrangement (11) being designed as an arrangement with single-acting valve control .

5. Roll stand according to one of claims 1 to 4, characterized in that the two work rolls (2, 3) are acted upon by a force directed towards the roll gap (4) by means of two further rolls (12, 13), in particular by means of two backup rolls , the further rollers (12, 13) being acted upon by the at least one hydraulic adjusting unit (5).

6. Roll stand according to one of claims 1 to 5, characterized in that the two work rolls (2, 3) can be subjected to a bending moment by means of a bending or balancing system, this further hydraulic adjusting units with respective further cylinders and further pistons wherein the further piston divides the further cylinder into a further first hydraulic chamber and a further second hydraulic chamber, the flow of hydraulic oil into the further first hydraulic chamber being controlled or regulated by means of a further hydraulic valve arrangement and the further hydraulic valve arrangement as an arrangement single-acting valve control is designed.

7. Roll stand according to one of claims 1 to 6, characterized in that several hydraulic adjustment units are arranged to act in parallel.

8. Roll stand according to one of claims 1 to 7, characterized in that several hydraulic valve arrangements (10) are arranged acting in parallel and jointly supply a hydraulic chamber (8, 9) with hydraulic oil.

9. Roll stand according to one of claims 1 to 8, characterized in that a pressure accumulator (14) and / or a pressure reducer (15) is arranged in the hydraulic flow path to the second hydraulic chamber (9).

10. Roll stand according to one of claims 1 to 9, characterized in that a damping unit (16) is arranged in the hydraulic flow path of the system pressure supply and / or the return line of the first and / or second hydraulic valve arrangement (10, 11), this preferably as has a hydraulic damper or accumulator (17), with additional components for damping and pretensioning being provided in particular.

11. Roll stand according to one of claims 1 to 10, characterized in that the hydraulic adjusting unit (5) has a flushing control by means of which the two hydraulic chambers (8, 9) can be hydraulically connected to one another or to the return line.