METHOD AND DEVICE FOR DYNAMICALLY SUPPLYING COOLANT TO A COOLING DEVICE FOR COOLING METAL STRIP OR OTHER ROLLED STOCK

Abstract

The present invention relates to a method of dynamically supplying coolant to a cooling device, in particular at least one spray bar, for cooling metal strip or other rolled stock. According to the method, a pre-accelerated stream of coolant is provided, which passes by the cooling device (1) and is fed into a return (3). Furthermore, the presence and/or the temperature of a metal strip or other rolled stock to be cooled is monitored and, dependent on the presence and/or the temperature of the metal strip or the other rolled stock, the stream of coolant is diverted to the cooling device (1), wherein, instead of passing by the cooling device (1) and being fed into a return (3), the stream of coolant is fed to the cooling device (1) for cooling the metal strip or the other rolled stock. The present invention also comprises a corresponding device for carrying out the method.

Description

FIELD OF THE INVENTION

The present invention is directed to a method of and a device for dynamically supplying a cooling device for cooling a metal strip or other rolled stock with coolant. The cooling device can include, in particular one or several spray bars.

STATE-OF-THE ART

State-of-the art discloses a number of systems for providing cooling water from a deep tank for a laminar or pressure cooling in hot rolling mill trains. For cooling a hot rolled stock, a substantial amount of cooling water is needed for a sufficiently defined and rapid cooling of a finished strip in accordance with the requirement to the finished product. For achieving a predetermined cooling rate, the necessary amount of water often varies in a range from several hundred m³/hr to even several thousand m³/hr. This extraordinarily large amount of water is fed, e.g., from a deep tank through valves of a throttled conduit system to spray bars.

Such a system according to the state-of-the art is shown, e.g., in FIG. 1. Water which is stored in a deep tank/storage 4 is fed to a central distributor 6 via conduit 2. From the common distributor 6, water is fed by further conduits to separate spray bars 1. However, this known device has certain drawbacks. For contemporary alloyed metals and steels, a large cooling rate should be adjusted and controlled as precisely as possible. However, a very large amount of water which is used makes this very difficult. In particular, switch-on and switch-off processes cannot be executed sufficiently quick, using the available approach that includes the use, primarily, of control valves, wherein the cooling switch-on process often requires more than 10 sec. for achieving the desired cooling rate. Because the rolled stock is displaced, in many cases, through the installation with a speed of several meters per second, a large strip length is not cooled with a desired cooling rate, which results in loss of quality of this strip section.

A further drawback consists in that during the cooling switch-on process, large forces act on conduit systems and/or cooling installations. In particular, the danger of a rapid switch-on process of the cooling water (coolant) supply consists in that the strong pressure surges damage the cooling system. Such pressure peaks can even result in the breakdown of the cooling installation and, thus, of the entire rolling mill train.

Proceeding from the known state-of-the art, the object of the invention is to provide an improved coolant supply which, in particular, would prevent pressure surges during the switch-on process or at least noticeably reduce them. Further object of the invention consists in achieving a more rapid cooling rate than the existing cooling rates in order to supply the coolant in most optimal manner to the rolled strip.

DESCRIPTION OF THE INVENTION

The object of the invention is achieved by features of a method of dynamically supplying coolant to a cooling device, in particular, to at least one spray bar for cooling a metal strip or a similar rolled stock with the coolant according to claim 1. The method comprises at least the steps of providing a pre-accelerated or flowing coolant flow, wherein the coolant flow by-passes the cooling device and is delivered to a return line, and monitoring presence and/or temperature of the to-be-cooled metal strip or the similar rolled stock. According to the invention, the pre-accelerated coolant flow is diverted to the cooling device dependent on the presence and/or predetermined temperature of the metal strip or the similar rolled stock, so that the coolant flow instead of by-passing the cooling device and being delivered to the return line, is fed, being already pre-accelerated, to the cooling device for cooling the metal strip or the similar rolled stock.

By pre-acceleration of the coolant flow and diversion of the pre-accelerated coolant flow, the pressure surges acting on the installation components can be eliminated or noticeably reduced. Further, the cooling reaction time is noticeably improved. The diversion process can be carried more rapidly than the process of acceleration of the remote amount of water. In addition, the desired cooling rate can be achieved or adjusted more rapidly and more precisely. Overall, the adjustability of the used volume flow is, thus, improved.

According to a preferred embodiment, the pressure loss of the coolant stream at by-pass of the cooling device and the pressure loss of the coolant stream at feeding of the coolant stream to the cooling device deviate from each other by less than 50%, preferably by less than 20%, or even by less than 10%. Advantageously, both values are essentially the same. Thus, pressure surges, at the deviation of the already accelerated coolant stream toward the cooling device, are prevented. In other words, the flow resistance to the coolant flow during deviation or feeding to the cooling device is essentially the same or differs less, as indicated above.

The deviation takes place, preferably, in less than 5 sec. or even in less than in 1.5 sec. The inventive method is particularly advantageous at such a relatively small switching time.

According to a further preferred embodiment, the deviation of the coolant stream takes place at less than 5 m, preferably at less than 1 m upstream of the cooling device (so that the path of the coolant stream between the deviation site and the outlets of the device for cooling the strip is kept as small as possible).

According to a still further advantageous embodiment a to-be-deviated volume flow of the coolant or the coolant flow amounts to more than 150 m³/hr and, preferably, to more than 400 m³/hr. Especially in view of such large volume flows, the present invention is particularly advantageous.

The invention is likewise directed to a device for cooling a metal strip, in particularly for carrying out the method according to one of the preceding claims.

The device comprises a cooling device for cooling a metal strip or a similar rolled stock and having at least one spray bar with coolant outlets for applying the coolant to the metal strip. The devices further includes conduit means for conducting a coolant flow from a coolant source to the spray bars, and by-pass means for conducting the coolant flow from the conduit means to a return line. There is further provided switchable deflection means formed for switchingly conducting the coolant flow through the conduit means to the spray bars or for deviating the coolant flow from the conduit means into the by-pass means.

The advantages of the device correspond to those already discussed with respect to the method.

In a preferred embodiment of the invention, the cooling device has at least one valve for controlling the volume flow of the coolant flow that flows through the conduit means, wherein the deflection means is located downstream of the control valve.

In a further advantageous embodiment, the switchable deflection means comprises either at least one switchable valve for conducting the coolant flow to the spray bars or to the by-pass means.

According to a still further advantageous embodiment, the conduit means comprises a pump for increasing an available, from the source, coolant volume flow. With such a pump, an even stronger pre-accelerated volume flow can be made available.

In a yet further advantageous embodiment, the coolant flow by-passes the pump through the by-pass. With such an arrangement, cooling with an available adequate coolant pressure is possible without the use of the pump. The water pressure can, e.g., be provided by a water tower.

Generally, an availability of very small volume flows (e.g., laminar operations) and likewise very large volume flows (pressure operations with a pump) are possible.

According to a further advantageous embodiment, a plurality of spray bars, preferably maximum ten spray bars are assembled in a first cooling group, wherein the first conduit means feeds the coolant to the first cooling group, and at most three spray bars of the first cooling group are provided with switchable deflection means for conducting the coolant flow from the first conduit means in the return line, so that cooling flow from at most three spray bars of the first cooling group is deviated into the by-pass means or the return line independent from the remaining spray bars of the first cooling group.

In a yet another advantageous embodiment of the invention, a plurality of further spray bars, preferably maximum ten spray bars are assembled in a second cooling group and the second conduit means feeds the coolant to the second cooling group, and at most three spray bars of the second cooling group are provided with switchable deflection means for conducting the coolant flow from the second conduit means in the return line, so that cooling flow from at most three spray bars of the second cooling group is deviated into the by-pass means or the return line independent from the remaining spray bars of the second cooling group.

In a yet further advantageous embodiment of the invention, the volume flow to each separate cooling group is increased by using a separate pump.

In a still further advantageous embodiment of the invention, the device comprises a plurality of spray bars, and each spray bar is associated with the switchable deflection means separately from the further spray bars, so that either the pre-accelerated coolant flow is fed to each spray bar by the conduit means, or deflection means associated with each spray bar feeds the coolant flow to the by-pass means.

In a yet another advantageous embodiment, at least one of the spray bars is supported by a support device, and the switchable deflection means is mounted on the support device. Alternatively or in addition, the switchable deflection means is located by less than 5 m, preferably by less than 3 m upstream of the spray bar.

The features of the described embodiments can be combined with each other or replace each other.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the drawings of examples of embodiments are described. Further details will become apparent from a detailed description of the examples of the embodiments.

The drawings show:

FIG. 1 (State-of-the Art) a schematic view of a device for supplying a plurality of spray bars with coolant;

FIG. 2 a schematic view of a device for cooling metal strips or the like rolled stock according to an example of one of the inventive embodiments; and

FIG. 3 a schematic view of a device for cooling metal strips or the like rolled stock according to an example of another of the inventive embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENT EXAMPLES

For a better understanding, first, a reference to the state-of-the art shown in FIG. 1 will be made. There is provided a storage 4 that serves as a storage for coolant. As a rule, the coolant is fed to a distributor 6 or a manifold 6 via conduits.

From the distributor 6, the coolant can be fed to a plurality of spray bars 1. Here, the spray bars 1 are provided with a plurality of outlets 7 for applying coolant to a metal strip from a respective outlets. As shown, a measurement sensor 15 (e.g., for measuring coolant pressure or volume flow), a regulator 9, or a stop cock 8 can be arranged between the distributor 6 and a respective spray bar 1. These elements permit to monitor and adjust the cooling stream fed to respective spray bars 1.

FIG. 2 shows a diagram of an embodiment example according to the present invention. The coolant is stored, similar to the state-of-the art according to FIG. 1, in a storage 4. Contrary to the arrangement shown in FIG. 1, the inventive embodiment according to FIG. 2 does not include any distributor 6. Rather, coolant is fed from the storage 4 to each spray bar 1 separately via a conduit 2. The available coolant flow can be increased using pumps 11, 11′ or booster-pump 11, 11′. In addition, the pumps 11, 11′ for the coolant can be provided, e.g., with a by-pass 13. The by-pass 13 can be switchable, so that the coolant is delivered either by the pumps 11, 11′ or by-passes the pumps 11, 11′ and is simply forwarded through the conduit system 2 by the (static) pressure in the storage 4. The volume flow can be monitored with a measurement sensor 15 and/or regulated by a control valve or regulator 9. Actual control of the volume flow per se is not subject of the present invention and can, e.g., be carried out with already known means of control technology. The essential consists in that the inventive device is provided with the switchable deflection means 5 which can divert the pre-accelerated coolant flow away from the spray bar 1. Thus, the running or pre-accelerated volume flow can, e.g., be directed in a downflow or overflow pipe 3. Such coolant flow then can be, e.g., returned back to the storage 4. Further processing of the coolant is dispensed with because the coolant is not contaminated by means 5 in case of diversion. The deflection generally includes two switchable shut-off valves or stop cocks or dampers so that the volume flow is forwarded either to the storage 4 or in the overflow pipe 3. An arrangement with one switchable damper is also possible. The described device can provide an already pre-accelerated flow that, if needed, can be fed to the spray bar 1 via the deflection means 5. The means 5 can be switched on, e.g., by a sensor that registers presence or inflow or discharge of the coolant. Alternatively, or in addition the temperature of the strip can be monitored with a temperature sensor. Dependent on the temperature, as a control variable, the deflection means 5 (actuator) can be switched off and on to control the inflow of the coolant (control value) through the spray bar 1 and its outlets 7 and onto the strip.

FIG. 3 shows a diagram of the cooling device according to another embodiment of the invention. Contrary to the device shown in FIG. 1, here, a plurality of spray bars 1 are assembled to form a cooling group 10, and another cooling bars 1′ are assembled to form a cooling group 10′. Within each of the cooling groups 10, 10′, a deflection device 50, 50′ is associated with each separate spray bar 1, 1′, being located upstream of a respective spray bar 1, 1′. I.e., the pre-accelerated volume flow can be fed to each spray bar 1, 1′ by the associated deflection device 50, 50′. Preferably, the deflection devices 50, 50′ are located as close as possible to the spray bars 1, 1′ in order to keep the time necessary for the volume flow to cover the path between the deflection location through the deflection means 5 and the spray bar low, whereby the reaction velocity or controllability of the system is noticeably improved.

The deflection means 5, 50, 50′ can generally be switched electrically, pneumatically, or hydraulically.

The above-described embodiments serve for better understanding of the invention and should not be understood as its limitations. The scope of protection of the present invention is defined by the claims.

The features of the described embodiments can be combined with each other or be exchanged with each other.

Further, the described features can be adapted by one of ordinary skill in the art to available conditions or requirements.

LIST OF REFERENCE NUMERALS

• 1 Spray bar
• 1′ Spray bar
• 2 Conduit
• 3 Circuitous means/backflow
• 4 Storage/deep tank
• 5 Switchable deflection means/switching armature
• 6 Distributor pipe
• 7 Coolant outlet of the spray bar
• 8 Stop cock
• 9 Control armature
• 10 First cooling group
• 10′ Second cooling group
• 11 Pump/booster pump
• 11′ Second pump
• 13 By-pass
• 15 Measurement sensor
• 20 First conduit means
• 20′ Second conduit means
• 50 First switchable deflection means
• 50′ Second switchable deflection means

Claims

1. A method of dynamically supplying coolant to a cooling device (1, 1′), in particular to at least one spray bar (1, 1′) for cooling a metal strip or a similar rolled stock with the coolant, comprising the steps of:

a) Providing a pre-accelerated coolant flow, wherein the coolant flow by-passes the cooling device (1, 1′) and is delivered to a return line (3);

b) monitoring presence and/or temperature of the to-be-cooled metal strip or the similar rolled stock;

c) diverting the already pre-accelerated coolant flow to the cooling device (1, 1′) dependent on the presence and/or predetermined temperature of the metal strip or the similar rolled stock so that the coolant flow instead of by-passing the cooling device and being delivered to the return line, is fed, being already pre-accelerated, to the cooling device (1, 1′) for cooling the metal strip or the similar rolled stock.

2. A method according to claim 1, wherein the pressure loss of the coolant stream at by-pass of the cooling device (1, 1′) and the pressure loss of the coolant stream at feeding of the coolant stream to the cooling device deviate from each other by less than 20%, or are essentially the same, so that pressure surges, at the deviation of the already accelerated coolant stream, toward the cooling device (1, 1′) are prevented.

3. A method according to claim 1, wherein for minimizing the path between the deviation location of the coolant flow and the outlets of the cooling device (1, 1′), the deviation of the coolant stream takes place at less than 5 m, preferably at less than 3 m upstream of the outlets of the cooling device (1, 1′).

4. A method according to claim 1, wherein a to-be-deviated volume flow of the coolant amounts to more than 150 m3/h and, preferably, to more than 400 m3/h.

5. A device for cooling a metal strip, comprising:

a cooling device for cooling a metal strip or a similar rolled stock and having at least one spray bar (1, 1′) with coolant outlets for applying the coolant to the metal strip;

conduit means (2, 20, 20′) for conducting a coolant flow from a coolant source (4) to the spray bars (1, 1′);

by-pass means for conducting the coolant flow from the conduit means (2, 20, 20′) to a return line (3);

switchable deflection means (5, 50, 50′) formed for switchingly conducting the coolant flow through the conduit means (2, 20, 20′) to the spray bars (1, 1′) or for deviating the coolant flow from the conduit means (2, 20, 20′) into the by-pass means.

6. A device according to claim 5, wherein the cooling device has at least one valve (9) for controlling the volume flow of the coolant flow that flows through the conduit means, wherein the deflection means (5, 50, 50′) is downstream of the control valve (9).

7. A device according to claim 5, wherein the switchable deflection means (5, 50, 50′) comprises either at least one switchable valve for conducting the coolant flow to the spray bars (1) or by-pass means, and/or wherein the switchable deflection mans (5, 50, 50′) carries out a switching process in less than 5 sec, preferably in less than 1.5 sec.

8. A device according to claim 5, wherein the conduit means (2, 20, 20′) comprise a pump (11, 11′) for increasing an available, from the source, coolant volume flow.

9. A device according to claim 8, wherein the coolant flow by-passes the pump (11, 11′) through a by-pass (13).

10. A device according to claim 5, wherein a plurality of spray bars (1), preferably maximum ten spray bars (1) are assembled in a first cooling group (10) and the first conduit means (20) feeds the coolant to the first cooling group (10), and at most three spray bars (1) of the first cooling group (10) are provided with switchable deflection means (50) for conducting the coolant flow from the first conduit means (20) in the return line, so that cooling flow from at most three spray bars (1) of the first cooling group (10) is deviated into the by-pass means independent from the remaining spray bars of the first cooling group (10).

11. A device according to claim 10, wherein additionally a plurality of further spray bars (1′), preferably maximum ten spray bars (1′) are assembled in a second cooling group (10′) and the second conduit means (20′) feeds the coolant to the second cooling group (10) and at most three spray bars (1′) of the second cooling group (10′) are provided with switchable deflection means (50) for conducting the coolant flow from the second conduit means (20′) in the return line, so that cooling flow from at most three spray bars (1′) of the second cooling group (10′) is deviated into the by-pass means independent from the remaining spray bars (1′) of the second cooling group (10′).

12. A device according to claim 11, wherein the first and second groups (10, 10′) are separately supplied with coolant from the source (4).

13. A device according to claim 11, wherein a separate pump (11, 11′) increases the volume flow to each of separate cooling group (10, 10′).

14. A device according to claim 5, wherein the device comprises a plurality of spray bars (1), and maximum three of the spray bars (1) are associated, separately from further spray bars (1) with a respective deflection means (5), so that maximum three spray bars (1) either are fed with the pre-accelerated coolant via the conduit means (2), or the coolant flow is fed to by-pass means by deflection means (5) associated with the maximum three spray bars (1); or in particular each spray bar (1) is associated with the switchable deflection means (5) separately from the further spray bars (1) so that either the pre-accelerated coolant flow is fed to each spray bar by the conduit means (2)m, or deflection means (5) associated with each spray bar (1) feeds the coolant flow to the by-pass means.

15. A device according to claim 5, wherein at least one of the spray bars (1) is supported by a support device, and the switchable deflection means (5) is mounted on the support device; and/or wherein the switchable deflection means (5) is located by less than 5 m upstream of the spray bar (1).