Abstract
A framework cooler (20) for cooling a steel strip (50), installed in a roller framework (11), in place of the work rolls (5) and their associated installation pieces (5a and 5b). The framework cooler (20) is sized to be installed into the roller framework (11) through the operator-side roller stands (1) of the roller framework (11). The cooler (20) includes a lower (21b) and an upper water tank (21a), each having a connection (22) for a coolant, and includes a plurality of cooling nozzles (23), or cooling tubes (23a) arranged in the depth direction (T) of the framework cooler (20) or at least one cooling slot (24) extending in the depth direction (T). The bottom and top sides of the steel strip (50) may be cooled.
Claims
1. A method for installing a stand cooler for cooling a steel strip in a roll stand of a rolling train, wherein the stand cooler comprises a coolant supply comprising a lower coolant tank and an upper coolant tank, each coolant tank having one connector for a coolant, and having a coolant outlet positioned in the depth direction of the stand cooler, the coolant outlet comprising a plurality of cooling nozzles or cooling pipes or at least one cooling slot; the method comprising: removing chocks for rollers from the roll stand and removing an upper and a lower working roller from the roll stand; installing the stand cooler in the roll stand, wherein the stand cooler is incorporated horizontally through an operator side roller housing in the width direction of the roll stand; and connecting the connectors of the upper and the lower coolant tanks to the coolant supply configured to cool the upper and the lower sides of the steel strip, the coolant provided via the coolant outlet of the lower coolant tank and of the upper coolant tank.
2. The method as claimed in claim 1, further comprising performing the installation of the stand cooler during ongoing operation of the rolling train or during an interruption in the operation of the rolling train.
3. The method as claimed in claim 1, wherein the coolant is supplied at at least one connector at a pressure of 2 to 5 bar.
4. The method as claimed in claim 1, wherein the coolant is supplied at at least one connector at a pressure of 0.1 to 1 bar.
5. A method for rolling steel strips in a hot-rolling train which has a plurality of roll stands, the method comprising: hot-rolling a first steel strip in at least two roll stands of the rolling train in series; cooling the first steel strip in a cooling section; then conveying away the cooled first steel strip; installing a stand cooler according to the method as claimed in claim 1; hot-rolling a second steel strip in at least one roll stand of the rolling train; cooling the second steel strip in at least one roll stand of the rolling train by operation of the stand cooler; cooling the cooled second steel strip in the cooling section; and conveying away the cooled second steel strip.
6. A method for uninstalling a stand cooler for cooling a steel strip from a roll stand of a rolling train, wherein the stand cooler comprises a lower coolant tank and an upper coolant tank, wherein the lower coolant tank and the upper coolant tank each have one connector for receiving a coolant and a coolant outlet positioned in a depth direction of the stand cooler, the coolant outlet comprising a plurality of cooling nozzles or cooling pipes or at least one cooling slot, the method comprising: separating the connectors of the upper and the lower coolant tank from a respective coolant supply; uninstalling the stand cooler from the roll stand, by extracting the stand cooler in the width direction (B) of the roll stand horizontally from an operator-side roller housing; and then installing chocks and an upper and a lower working roller in the roll stand.
7. The method as claimed in claim 6, further comprising uninstalling the stand cooler during ongoing operation of the rolling train or during an interruption in the operation of the rolling train.
8. The method as claimed in claim 1, wherein the coolant is water.
9. The method as claimed in claim 5, wherein the coolant is water.
10. The method as claimed in claim 6, wherein the coolant is water.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further advantages and features of the present invention are derived from the description of non-limiting exemplary embodiments. In the schematically illustrated figures hereunder:
(2) FIGS. 1A and 1B show two views of a roll stand having installed chocks and working rollers as in the prior art, wherein FIG. 1A is a lateral view and FIG. 1B is a schematic sectional illustration of the roll stand;
(3) FIG. 2 shows two views of chocks and working rollers as per the prior art, wherein FIG. 2A is a lateral view thereof and FIG. 2B is a front view thereof;
(4) FIG. 3 shows a lateral view of a roll stand ahead of a cooling section as per the prior art;
(5) FIG. 4 shows a lateral view of a finishing rolling train having five roll stands ahead of a cooling section as per the prior art;
(6) FIG. 5 shows a lateral view of a finishing rolling train having five roll stands, wherein one stand cooler according to the invention is installed in each of the last three roll stands;
(7) FIG. 6A shows an end view of a stand cooler and FIG. 6B shows a sectional view thereof;
(8) FIG. 7 shows a further view of the stand cooler from FIGS. 6A and 6B;
(9) FIG. 8 shows two views of a roll stand having an installed stand cooler, with FIG. 8A including chocks and FIG. 8B showing the roll stand with the chocks removed;
(10) FIG. 9A shows a plan view of a stand cooler having a cooling slot;
(11) FIG. 9B shows a sectional view of the stand cooler;
(12) FIG. 10 shows a schematic illustration of the hydraulic management for a roll stand having an installed stand cooler;
(13) FIG. 11 shows a section in the width direction through a roll stand having an installed stand cooler;
(14) FIG. 12 shows a view of a stand cooler having cooling pipes instead of cooling nozzles;
(15) FIG. 13 shows a front view of a stand cooler having an installed stand cooler and baffle plates; and
(16) FIG. 14 shows a view of a one-piece stand cooler in a C-shape.
DESCRIPTION OF THE EMBODIMENTS
(17) FIG. 1A shows a lateral view of a prior art roll stand 11 having installed chocks 4a, 4b, respectively for an upper and a lower supporting roller 4 and installed chocks 5a, 5b for an upper and a lower working roller 5. FIG. 1B shows the roll stand 11 in a schematic sectional illustration without any chocks 4a, 4b, 5a, 5b. A hot strip (not illustrated), here a steel strip, in the roll stand 11 is rolled by the working rollers 5, wherein the working rollers 5 are supported on the supporting rollers 4 lying therebehind. A bending block 6 can flex the working rollers 5 and thus readjust the profile, or the planarity, respectively, of the rolled hot strip. The chocks 4a, 4b, 5a, 5b of the so-called AGC (short for Automatic Gap Control) cylinders 3 and the bending block 6 are installed in the two housing windows 2 of the roller housings 1. Only the operator-side roller housing 1 can be seen in FIG. 1. The drive-side roller housing is obscured by the operator-side roller housing 1. The drive-side roller housing 1 can be seen only in FIG. 11, but is not provided with a reference sign there.
(18) The hot strip is guided on a rolling table 10 and is moved to the working rollers 5. To limit the temperature of the working rollers 5, at least one upper cooling head 8a (here, two are illustrated) and at least one lower cooling head 8b (here, two) of the working roller cooling are provided ahead, or upstream of and behind or downstream of the working rollers 5. Moreover, an upper cooling head of the intermediate stand cooling 7a is installed ahead, or upstream of the roll stand 11, and a lower cooling head of the intermediate stand cooling 7b is installed behind, or downstream of the roll stand 11. Of course, one upper and one lower cooling head of the intermediate stand cooling 7a, 7b can in each case also be disposed ahead of and behind the roll stand 11.
(19) A pivotable loop lifter roll 9 can set the tension in the hot strip. The temperature of the hot strip before and after rolling can thus be modified. Since roll stands 11 having so-called stand chocks are known, a more detailed description of the prior art is dispensed with.
(20) A chock 5a having an upper working roller 5 and a chock 5b having a lower working roller 5 are illustrated in a lateral view in FIG. 2A and in a front view in FIG. 2B. The working rollers 5 are thus mounted so as to be displaceable in the roll stand 11 by the respective chocks 5a, 5b.
(21) FIG. 3 shows the roll stand 11 of FIG. 1 in a rolling mill. A steel strip (not illustrated) extending on an upstream roller table 12 is fed in a transportation direction TR to the roll stand 11 and is there rolled in the roll gap between the two working rollers 5. After hot-rolling, the rolled strip on a subsequent downstream roller table 12 is in turn fed to a cooling section 45 having a plurality of cooling manifolds 13, where the strip is cooled by an adjustable intensity from the manifolds.
(22) FIG. 4 shows a potential situation when rolling a thick hot strip in a rolling train 40. The train 40 is configured as a finishing rolling train, having five roll stands 11. Since a thick hot strip is being rolled, the last rolling pass takes place in the third (that is to say the central) roll stand 11. The thickness of the hot strip herein illustrated is reduced from 45 mm to 20 mm, for example in the first three roll stands. After its having been rolled, the rolled finished strip exits the central roll stand 11 at a speed of 0.4 m/s, for example. The finished strip in the regions identified by C, between successive roll stands, may be cooled by the upper and the lower cooling heads of the intermediate stand cooling 7a, 7b. The finished strip cannot be cooled in the roll stand 11 per se. The non-cooled regions of the strip are identified by NC. Since the horizontal spacing between the stand centerline of the third roll stand 11 and the beginning of the cooling section 45 having the cooling manifolds 13 (In an example of two downstream roll stands 11 that are not used for rolling the strip 50 and of typical spacings between the roll stands 11) is approx. 20 m, the rolled hot strip according to the example above requires 50 s to reach the cooling section 45. This time is already excessively long for specific types of steel such that that steel strip can no longer achieve desired microstructure and phase properties, respectively. The intermediate stand cooling (marked by C in FIG. 4) having the upper and lower cooling heads 7a, 7b (see FIG. 1) makes no difference herein since the cooling output is insufficient and the rolled hot strip is largely not cooled on its way to the cooling section 45.
(23) FIG. 5 shows the situation when hot-rolling a thick steel strip in a rolling train 40, configured as a finishing rolling train having originally five roll stands 11. The chocks 5a, 5b and the working rollers 5 (see FIG. 1) are removed from the last three roll stands (see FIG. 4). Instead, one stand cooler 20, with details pertaining thereto in FIGS. 6 to 11), is in each case installed in each roller housing 1. The last rolling pass takes place in the second roll stand 11 from the left. The finished strip is in each case intensively cooled by one stand cooler 20 in the three subsequent roller housing 1. Because the steel strip has been cooled by the stand coolers 20, the finished strip is already cooled as from the central roller housing 1. This makes it possible to generate thick strips of specific steel grades (demanding tube grades, for example), which could not be produced without use of a stand cooler 20.
(24) Two views of a stand cooler 20 are shown in FIGS. 6A and 6B, including a lateral view in FIG. 6A and a sectional illustration in FIG. 6B. The stand cooler 20 has an upper water tank 21a and a lower water tank 21b. The lower side of the upper water tank 21a and the upper side of the lower water tank 21b are populated by cooling nozzles 23 such that a hot strip (not illustrated here) may be cooled in the width direction B transversely to the feed direction. To further increase the cooling output, seven cooling nozzles are in each case disposed one behind another in the transportation direction (see FIG. 6B). The water tanks 21a, 21b have lateral support lugs 25, wherein the support lugs 25 of the lower water tank 21b have in each case one guide face 26. The stand cooler 20 can be moved in the width direction B of the hot strip into a roll stand (not illustrated here) on the guide faces 26. The stand cooler 20 illustrated as embodied in one piece, wherein the upper and the lower water tank 21a, 21b are connected to one another by uprights 27. The cooling nozzles 23 are supplied with coolant through four connectors 22, wherein two connectors 22 supply the upper and the lower water tanks 21a, 21b.
(25) A front view of the stand cooler of FIGS. 6A and 6B is additionally illustrated in FIG. 7. The cooling nozzles 23 are typically supplied with coolant at a positive pressure of 2 to 5 bar. The cooling intensity is a function of the pressure and is adjustable by the positive pressure of the cooling medium.
(26) A roller housing 1 having a stand cooler 20 is illustrated in a lateral view in FIG. 8A and in a sectional illustration in FIG. 8B. The stand cooler 20 from FIGS. 6A, 6B and 7 in the installed state bears, and can be installed and uninstalled, on the two guide faces 26 of the lower support lugs 25, on guide rails in the roller housing 1, or on the counter guides of the chock 4b of the lower supporting roller. As can be seen, the stand cooler 20 is disposed between the supporting rollers 4, thus in line with the supporting rollers 4.
(27) FIGS. 9a and 9b show a stand cooler 20 which, as an alternative to the cooler shown in FIGS. 6A, 6B and 7, has cooling slots 24 instead of cooling nozzles. Since the steel strip 50 in the width direction B thereof, or in the depth direction T of the stand cooler 20, respectively, is not cooled to dissimilar extents it is sufficient for the upper and the lower water tank 21a, 21b to have in each case only one connector 22. The uprights 7 and the support lugs 25 are embodied as in FIGS. 6A, 6B and 7.
(28) An example of a plan of water lines for supplying a roll stand having an installed stand cooler 20 with coolant is illustrated in FIG. 10. A pump 30 fed from a tank 31 represents the coolant supply. The pressure of the cooling medium water is reduced from 13 bar to 4 bar by the pressure regulator valve 28. After the water passes the opened switch valve 29 and the flow regulator valves 32, the cooling medium, is fed by connectors to the upper and lower water tanks 21a, 21b. The upper and the lower sides of a hot strip (not illustrated here) are cooled by coolant from the cooling nozzles 23. The switch valves 29 for supplying the cooling medium to the cooling heads for the working roller cooling are closed in the installed state of the stand cooler 20 in the roll stand 11. For better use of energy, it would be more favorable for the stand coolers 20 to be fed by a separate cooling circuit without any pressure reduction caused by pressure regulator valves 28, and instead for example, to be directly fed at a pressure between 0.1 to 5 bar. These are typical pressures of existing low-pressure cooling systems. Alternatively, it would be possible for the stand cooler 20 to be connected directly to the existing coolant supply of the roll stand, without any pressure reduction.
(29) Installation of a stand cooler 20 in the roller housings 1 or a roll stand 11 is schematically illustrated in FIG. 11. After the AGC cylinders 3 and the chocks 4a for the upper supporting roller 4 have been raised, the chocks 5a, 5b for the working rollers 5 as well as the working rollers 5 are removed. The stand cooler 20 is subsequently pushed-fitted horizontally in the width or transverse direction B of the roll stand 11 through the operator-side roller housing 1 (illustrated on the right here). The connectors 22 of the stand cooler 20 are finally connected to a coolant supply such that an upper and a lower side of a hot strip (not illustrated) are cooled by the cooling nozzles 23.
(30) FIG. 12 shows a schematic section through a stand cooler 20 having cooling pipes 23a instead of cooling nozzles 23 (see FIG. 6B). Cooling pipes 23a are typically operated at a positive pressure between 0.1 and 1 bar, such that said cooling pipes 23a can implement so-called laminar cooling in a simple manner.
(31) The uninstalling of a stand cooler 20 from a roller housing 1 is not separately illustrated since the steps for the installation are simply carried out in the reverse order.
(32) Masking of the edge regions (edge-masking) of a steel strip 50 is shown in FIG. 13. At least one edge region of the steel strip 50 herein, four edge regions in the figure, is masked by sliding in a baffle plate 33 or a channel between the cooling nozzles 23, the cooling pipes 23a, (see FIG. 12) or the cooling slot 24 (see FIG. 9b), respectively, of the stand cooler 20 and the surface of the steel strip 50 such that edge region of the strip is not there cooled. The cooling water of the cooling nozzles 23, or cooling pipes, respectively, is discharged outward in the width direction of the steel strip 50. The position of the baffle plate 33 or of the channel can be finely set manually or automatically (for example by an actuator not illustrated which displaces the baffle plate 33 in the direction of the arrow) such that excessive cooling of the edge regions is reliably prevented.
(33) A stand cooler 20 in a C-shape as an alternative to the stand cooler in FIG. 7 is shown in FIG. 14. Since the C-shaped stand cooler 20 in the width direction B is open at one end, the stand cooler 20 can be installed in a roll stand and uninstalled again therefrom in a simple manner during the ongoing operation of the rolling mill. The connectors 22 of the upper and the lower water tank 21a, 21b, the cooling nozzles 23, as well as the guide faces 26 are identical to those of FIG. 7. As an alternative to the guide faces, the stand cooler 20 could also have wheels for guiding on a rail. The uprights are disposed on only one end of the stand cooler, for example the operator-side end.
(34) While the invention has been illustrated and described in more detail by way of the preferred exemplary embodiments, the invention is not limited to the disclosed examples, and other variants can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.
LIST OF REFERENCE SIGNS
(35) 1 Roller housing 2 Housing window 3 AGC cylinder 4 Supporting roller 4a Chock for the upper supporting roller 4b Chock for the lower supporting roller 5 Working roller 5a Chock for the upper working roller 5b Chock for the lower working roller 6 Bending block 7a Upper cooling head of the intermediate stand cooling 7b Lower cooling head of the intermediate stand cooling 8a Upper cooling head of the working roller cooling 8b Lower cooling head of the working roller cooling 9 Loop lifter roll 10 Rolling table 11 Roll stand 12 Roller table 13 Cooling manifold of a cooling section 20 Stand cooler 21a Upper water tank 21b Lower water tank 22 Connector 23 Cooling nozzle 23a Cooling pipe 24 Cooling slot 25 Support lugs 26 Guide face 27 Upright 28 Pressure regulator valve 29 Switch valve 30 Pump 31 Tank 32 Flow regulator valve 33 Baffle plate 40 Rolling train 45 Cooling section 50 Steel strip B Width direction of the roller housing C Cooled region LC Cooled region of the cooling section NC Non-cooled region T Depth direction of the stand cooler TR Transportation direction of the steel strip
