Hydraulic system for a continuous casting plant

Abstract

The present invention relates to the field of continuous casting technology and describes a hydraulic system and a continuous casting plant. The hydraulic system comprises a hydraulic station (1), downstream of which at least one pressure amplifier having a control device (8) is connected, which pressure amplifier can output high pressure at the outlet. At least one valve assembly (5b) is connected to an output of the pressure amplifier having the control device (8), and the valve assembly (5b) can supply a downstream hydraulic actuator (5a) with high pressure. The continuous casting plant contains the hydraulic system, comprising a hydraulic station (1) for providing an operating pressure, as well as a plurality of strand guide units for guiding the strand and / or reducing the thickness of a casting strand, which have (hydraulic actuators 5a) for adjusting the casting gap. At least one pressure amplifier having the control device (8) is connected downstream of the hydraulic station, which pressure amplifier is supplied with the operating pressure at the input and can output high pressure at the output. At least one strand guide unit having at least one hydraulic actuator (5a) is connected, via an upstream valve assembly (5b), to an output of the pressure amplifier having the control device (8).

Description

[0001] Description

[0002] Title of the invention

[0003] HYDRAULIC SYSTEM FOR A CONTINUOUS CASTING PLANT

[0004] field of technology

[0005] The present invention is in the field of continuous casting technology and describes a hydraulic system for a continuous casting plant. The hydraulic system comprises a hydraulic station for supplying consumers with an operating pressure. Furthermore, the invention describes a continuous casting plant. This comprises several continuous casting segments or drivers, also referred to below as strand guide units, for guiding and / or reducing the thickness of a cast strand. The strand guide units each have at least one consumer, with each consumer including at least one hydraulic actuator for adjusting the casting gap.

[0006] State of the art

[0007] The continuous casting plant includes a hydraulic station that supplies the strand guide units with operating pressure. This operating pressure is used to control the hydraulic actuators via a hydraulic circuit to maintain a specific casting gap. The thickness of the casting gap is measured, and the measured value is sent to a control device, which controls the hydraulic circuit to achieve a specific setpoint. The setpoint is specified by a higher-level plant control system with an integrated process model. The casting gap is specified based on the shrinkage of the strand due to its cooling as the casting length progresses.The forces required to support the strand depend on the casting format and result from the hydrostatic pressure of the liquid metal in the strand and a reference surface defined by the support roller spacing and the strand width, as well as the straightening forces, i.e. those forces that cause the plastic deformation of the strand. An additional requirement is the so-called 'soft reduction'. Here, the contact pressure of the strand guide rollers is increased at the point where complete solidification of the cast strand is achieved, according to the calculation model. This measure leads to an improvement in the internal quality of the cast product. FR 2 652 020 discloses a continuous casting plant with a mold and cooling device, in which a device for thickness reduction is present at the point where complete solidification of the cast strand occurs.This consists of guide rollers and at least one frame to reduce the thickness of the cast strand during its passage. To limit the deflection of the guide rollers, hydraulic cylinders equipped with a pressure intensifier are used. The pressure intensifiers comprise a circuit for pressurizing a secondary fluid in an auxiliary chamber closed by a pressure intensifier piston that is mounted so as to be displaceable in the axial direction and has two opposing surfaces of different sizes: a large surface in the auxiliary chamber that is subjected to the pressure of the secondary fluid, and a small surface to which the pressure in the hydraulic cylinder chamber acts. The hydraulic system also includes means for controlling the deflection of the rollers.

[0008] DE 101 60636 discloses a method for adjusting a casting gap on a strand guide of a continuous casting plant, as well as a continuous casting plant for implementing this method. The casting gap is adjusted before casting begins according to an ideal strand thickness profile along the length of the strand guide. After casting begins, the operating load is calculated to adjust the casting gap under operating load. This operating load, as well as the stiffness of strand guide components that influence the casting gap, are taken into account when calculating correction values ​​for the casting gap adjustment.

[0009] DE 32 28494 shows a pressure amplifier whose task is to compress the pressure present in the gas or compressed air network to a higher pressure.

[0010] In the so-called 'hard reduction', the contact pressure of the strand guide rollers is increased to such an extent that a considerable reduction in the casting thickness is achieved through a rolling process. The plastic deformation of the cast strand required for this requires considerably greater actuating forces than would be the case with strand guide units, whose sole task is to support the strand. To achieve these forces, conventionally either the operating pressure of the hydraulic system is increased and / or cylinders with a larger piston area are used. From a technical point of view, the known measures entail considerable disadvantages. An increase in the operating pressure would affect the design of the entire system, even though this increased operating pressure is only required by certain strand guide units for certain casting formats during certain periods. On the other hand, larger hydraulic actuators entail design disadvantages due to the installation space available.would lead to additional embodiments of strand guide units. This particularly applies to the conversion of existing systems. The present invention overcomes these technical disadvantages.

[0011] Summary of the invention

[0012] The object of the present invention is to provide a continuous casting plant or a hydraulic system which allows particularly high setting forces of the strand guide rollers to be achieved in certain strand guide units of a continuous casting plant and / or during certain periods of time due to the process.

[0013] This object is achieved by a hydraulic system, wherein at least one pressure amplifier with control device is connected downstream of a hydraulic station, wherein the pressure amplifier with control device is supplied with the operating pressure at the inlet and can output a high pressure at the outlet.

[0014] The high pressure generated by the pressure booster with control device is measured with a pressure measuring device, and the pressure booster is controlled via a control device so that the high pressure is regulated within a predetermined range. The high pressure is greater than the operating pressure, and at least one valve arrangement is connected to the output of the pressure booster with control device. The valve arrangement can supply a downstream hydraulic actuator. In the context of this invention, the valve arrangement is understood to mean at least one hydraulic valve, but it can also be a hydraulic circuit composed of multiple hydraulic components.

[0015] In the context of this invention, a hydraulic actuator can be understood as a hydraulic cylinder, but it can also be another element that converts the volume flow of a hydraulic medium into a mechanical movement.

[0016] The invention thus makes it possible to adjust the casting gap on the strand guide units where particularly high force is required, without equipping these strand guide units with larger cylinders. Such a casting gap adjustment using particularly high force is carried out, for example, with certain casting formats and / or to change the thickness of the cast product during the continuous casting process, the so-called "hard reduction." The arrangement of the pressure booster upstream of the hydraulic valves that control the hydraulic actuators facilitates the implementation of dynamic control and regulation processes. It has been shown that arranging the pressure boosters directly on the cylinders, as is common in various industrial applications, has a detrimental effect on the dynamics of the control processes.

[0017] A further advantage of the invention relates to the conversion of existing plants. Here, the use of pressure boosters enables an increase in hydraulic forces without replacing hydraulic actuators and / or changing the operating pressure. Furthermore, advantages arise in terms of plant design due to the possibility of using smaller cylinders. This allows for narrower segment widths in slab plants, or shorter distances between the actuators in continuous casting plants for the production of long products.

[0018] In one embodiment of the invention, the high pressure can be regulated to a specific value. The generated high pressure is measured with a pressure measuring device, and the pressure amplifier is controlled via a control device so that the high pressure is regulated within a predetermined range.

[0019] A particularly significant advantage of the invention arises when at least one pressure booster is arranged on at least one continuous casting segment, and this supplies at least two hydraulic actuators with high pressure via the same valve arrangement. In this case, the pressure supply line to the respective continuous casting segment can be provided with standard operating pressures, for example, 200 bar. The high pressure can be supplied to several hydraulic actuators via appropriate hydraulic circuits. This principle makes it possible to achieve the advantages associated with high pressure supply, such as the use of compact hydraulic actuators.

[0020] In another embodiment, pressure accumulators, such as bladder accumulators or piston accumulators, can be used to smooth pressure curves. This provides advantages in the control behavior of the casting gap regulator.

[0021] In an advantageous embodiment, the pressure amplifier is designed on the basis of a bistable oscillating piston which has different surfaces on two sides such that the area ratio of these surfaces causes the pressure amplification.

[0022] In a further embodiment, the pressure booster is designed on the basis of two mechanically connected hydraulic pumps, for example gear pumps, wherein the pressure boost is achieved by the connected pumps having different delivery volumes per revolution and / or being connected to one another with a mechanical transmission ratio other than one.

[0023] In a further embodiment, the predetermined range in which the high pressure is regulated is 200 to 400 bar, preferably 250 to 350 bar, particularly preferably 270 to 300 bar. In a further embodiment, the range in which the high pressure is regulated can be specified to the control device via an input.

[0024] The problem is also solved by a continuous casting plant comprising several strand guide units, for example, continuous casting segments for strand guidance and / or thickness reduction of a cast strand. The strand guide units each have at least one consumer, with each consumer including at least one hydraulic actuator for adjusting a casting gap.

[0025] At least one strand guide unit with at least one hydraulic actuator is connected to the previously described hydraulic system, which is described in claims 1 - 7, and is supplied with high pressure.

[0026] In an advantageous embodiment, at least one pressure booster with a control device is arranged on at least one continuous casting segment. This pressure booster supplies at least two hydraulic actuators of this continuous casting segment with high pressure via the same valve arrangement.

[0027] In a further advantageous embodiment, all strand guide units each have hydraulic actuators of the same size. For example, if hydraulic cylinders are used, these each have the same effective area in a strand guide unit, thus generating the same force when actuated with the same pressure, or the same speed at the same flow rate.

[0028] Short description of the drawings

[0029] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in conjunction with the drawings.

[0030] Fig. 1 a continuous casting segment, including a pressure booster with control device, as well as consumers that are supplied with high pressure and another continuous casting segment, whose consumers are directly supplied with operating pressure.

[0031] Fig. 2 shows a schematic representation of a pressure booster with a control device, a hydraulic station, and consumers supplied with operating pressure and consumers supplied with high pressure. Description of the embodiments

[0032] Fig. 1 shows two exemplary embodiments of continuous casting segments. The first continuous casting segment contains a pressure booster with a control device 8, as well as consumers 5 which are supplied with high pressure, again comprising a valve arrangement 5b, and hydraulic actuators 5a controlled by the latter. The second continuous casting segment contains consumers 6 which are supplied with operating pressure, again comprising a valve arrangement 5b, and hydraulic actuators 5a controlled by the latter. The casting gap 7 can be adjusted using the hydraulic actuators 5a. The high pressure is only made available to the consumers 5 which are supplied with high pressure when necessary. Otherwise, they are provided with the operating pressure. As soon as an increased actuating force is required, it is possible at any time to make the high pressure, which is higher than the operating pressure, available to the consumers 5 which are supplied with high pressure.

[0033] Fig. 2 shows a schematic representation of a hydraulic system for a continuous casting plant with a hydraulic station 1, a pressure booster with control device 8, consumers 5 which are supplied with high pressure, and consumers 6 which are supplied with operating pressure. The pressure booster with control device 8 contains a pressure booster 4, a pressure measuring device 2, a control device 3, and hydraulic valves 9. The range in which the high pressure is regulated can be specified to the control device 3 via an input 10. These components form a control loop which makes it possible to switch the pressure booster 4 on and off in such a way that the consumers which are supplied with high pressure are provided with a high pressure which corresponds to a setpoint.

[0034] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0035] 1 hydraulic station

[0036] 2 pressure measuring device

[0037] 3 Control device

[0038] 4 pressure boosters

[0039] 5 consumers supplied with high pressure

[0040] 5a Hydraulic actuator

[0041] 5b Valve arrangement

[0042] 6 consumers supplied with operating pressure

[0043] 7 Casting gap

[0044] 8 pressure boosters with control device

[0045] 9 Hydraulic valve

[0046] 10 Entrance

Claims

Claims 1. Hydraulic system for a continuous casting plant, comprising a hydraulic station (1) for supplying consumers (6) which are supplied with an operating pressure, characterized in that at least one pressure booster with a control device (8) is connected downstream of the hydraulic station (1), wherein the pressure booster with a control device (8) is supplied with the operating pressure at an inlet, and a high pressure generated by the pressure booster with a control device (8) is measured with a pressure measuring device (2), and the pressure booster (4) is controlled via a control device (3) such that the high pressure is controlled within a predetermined range and the pressure booster (4) can output a high pressure at an outlet,wherein the high pressure is greater than the operating pressure and at least one valve arrangement (5b) is connected to the output of the pressure amplifier with control device (8) and the valve arrangement (5b) can supply a downstream hydraulic actuator (5a).

2. Hydraulic system for a continuous casting plant according to claim 1, characterized in that at least one pressure amplifier with control device (8) is designed such that it can supply at least two hydraulic actuators (5a) with high pressure via controlled hydraulic valves (5b).

3. Hydraulic system for a continuous casting plant according to one of claims 1 - 2, characterized in that a hydraulic accumulator, for example a bladder accumulator or a piston accumulator, is arranged at the outlet of the pressure amplifier (4), wherein the accumulator is designed in such a way that the pressure peaks of the high pressure occurring during the pressure amplification are smoothed out.

4. Hydraulic system for a continuous casting plant according to one of claims 1 - 3, characterized in that a pressure amplifier with control device (8) based on a bistable oscillating piston is used, which has different surfaces on two sides such that the area ratio of these surfaces causes the pressure amplification.

5. Hydraulic system for a continuous casting plant according to one of claims 1 - 4, characterized in that a pressure amplifier with control device (8) is used, which consists of at least two mechanically connected Hydraulic pumps, for example gear pumps, are formed, whereby the pressure amplification is achieved by the fact that the connected pumps have different delivery volumes per revolution and / or are connected to one another with a mechanical transmission ratio other than one.

6. Hydraulic system for a continuous casting plant according to one of claims 1 - 5, characterized in that the predetermined range in which the high pressure is regulated is 200 to 400 bar, preferably 250 to 350 bar, particularly preferably 270 to 300 bar.

7. Hydraulic system for a continuous casting plant according to one of claims 1 - 6, characterized in that the range in which the high pressure is regulated can be specified to the control device (3) via an input (10).

8. Continuous casting plant comprising a plurality of strand guide units, for example continuous casting segments for strand guidance and / or thickness reduction of a cast strand, wherein the strand guide units each have at least one consumer, wherein each consumer includes at least one hydraulic actuator (5a) for adjusting a casting gap (7), characterized in that at least one strand guide unit is connected to at least one hydraulic actuator (5a) via a hydraulic system according to one of claims 1 to 7 and is supplied with high pressure.

9. Continuous casting plant according to claim 8, wherein at least one pressure booster with control device (8) is arranged on at least one continuous casting segment, and this supplies at least two hydraulic actuators (5a) of this continuous casting segment with high pressure via the same valve arrangement (5b).

10. Continuous casting plant according to one of claims 8 - 9, characterized in that the strand guide units each have hydraulic actuators (5a) of the same size.

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