EP0899030B1 - Device and method for cooling the working rolls on the outlet side of a roll stand - Google Patents

Description

The invention relates to a device for cooling the work rolls of a roll stand, comprising one for each roll Spray nozzles equipped cooling water channel on a spray bar as well Means for supplying cooling water or for removing heated water, as well as one in the point of assignment to the upper work roll Angle to the surface of the rolling stock arranged cooling water guide plate with a front wiper associated with the roller, and tight an approximately horizontal cooling water guide plate below the rolling stock level with a scraper assigned to the lower roller. The invention further relates to a related method for Cooling of the work rolls. Such a device and such a method are according to the Preambles of claims 1 and 10, respectively known for example from JP-06339712 A.

Devices and methods for work roll cooling are known. Usually there is an inlet side and an outlet side Cooling applied. The effect of the inlet-side work roll cooling is despite its comparatively large apparatus technology Little effort.

• Verhinderung der Überschreitung eines definierten Temperaturlimits, um die mechanischen Eigenschaften der Arbeitswalzen zu erhalten,
• Begrenzung von thermischen Spannungen in den Arbeitswalzen und somit Verhinderung von Walzenbrüchen,
• Minimierung von Fire Cracks in der Oberfläche der Arbeitswalzen,
• positive Beeinflussung des Oxidationsfilms auf den Arbeitswalzen, insbesondere bei Chromstahlwalzen.

The need for effective work roll cooling results from their tasks in connection with the rolling process, namely:

• Preventing a defined temperature limit from being exceeded in order to maintain the mechanical properties of the work rolls,
• Limitation of thermal tensions in the work rolls and thus prevention of roll breaks,
• Minimization of fire cracks in the surface of the work rolls,
• positive influence on the oxidation film on the work rolls, especially with chrome steel rolls.

The main amount of heat is in contact with the work rolls the rolling stock in the roll gap, increased by that in the plastic Shape change of the rolling stock additionally developed rolling heat, still due to the frictional heat generated between the rolling stock and the rolls and the introduction of frictional heat in the contact area between Work roll and backup roll as well as additional heating by Radiant heat in the inlet and outlet area.

In order to achieve adequate roll cooling, the influence of the outlet-side cooling of considerable importance because of the induced Warm the surface area of a roller as early as possible after leaving the roll gap must be withdrawn to prevent penetration heat as deeply and efficiently as possible to prevent.

DE 36 16 070 A1 discloses a roll cooling device for a Roll stand comprising cooling water guide plates, each a curved one Have area along the circumferential direction of a roller and located near the respective roller, further a cooling water supply manifold for supplying cooling water to a cooling water channel, which is limited by the cooling water guide plate and the roller, one Water drainage manifold to drain the from the cooling water supply manifold supplied cooling water from the cooling water channel, a support element for holding the cooling water guide plate and curvature adjustment elements, which corresponds to the curvature of the guide plate Change the diameter of the roller. The thickness of the guide plate increases from the edge sections to the center of the guide plate in the circumferential direction of Roller closed. With the curvature adjustment organs when changing the Roller diameter of the clearance between the guide plate and the Maintain the roller as necessary so that the roller is sufficiently cooled. This device results in a forced cooling water flow, the shape of which is the outer circumference Corresponds to the roller, being at a constant distance from the roller a space between the cooling water guide and the roller results, is conveyed by the cooling water under pressure, whereby an average heat transfer coefficient with about four times the value of conventional heat transfer coefficient is to be achieved.

The known device requires a very large technical Effort, in addition, the curvature adjustment organs are difficult are arranged accessible and the periodic readjustment continues the curvature requires a high level of maintenance. Because besides the coolant in a narrow gap along part of the Roll surface is forcibly guided, this takes when flowing through heat in the gap and loses to the same extent Cooling intensity.

The Japanese published under publication number JP-01091903 A. Laid-open specification discloses a device for the outlet side Cooling of work rolls with one upper and one lower, Wiper cooling water guide plate attached to the work rolls facing end with spray nozzles for a cooling water-air mixture is equipped. By spraying water mist into the outlet-side, tapered corner areas between work rolls and rolling stock should have a sufficient cooling effect of the work rolls and at the same time a reduction in consumption can be achieved.

The Japanese published under publication number JP-01057908 A Laid-open patent discloses on the front of cooling water baffles arranged water mist nozzles, as well as additional upper and lower spray nozzles for cooling water. With this device should prevent cracking on the surface of the work rolls become.

The Japanese published under publication number JP-06339712 A Laid-open patent discloses an outlet-side cooling device for work rolls with triple one above the other or one below the other arranged cooling water channels equipped with spray nozzles as well as an upper and lower cooling water baffle with end Wringing. The top baffle is spaced from the top Roll a channel parallel to the roll with openings for draining Cooling water assigned to the one open at both ends Cooling water drainage channel forms. This is supposed to warm a drain Cooling water from the middle area of the work roll evenly can be reached on both sides. Because, however, heated cooling water in this device only with a natural slope and through relatively narrow channel cross-section from the center to both sides flows out, the liquid throughput is comparatively low and also cannot be increased arbitrarily. This results in a water level between the upper cooling water baffle and a lower area the upper work roll in approximately the height of the inlet openings of the Drain channel. With this construction, the creation of a Vacuum only to suck in air, but not to increase it Drain the liquid. It also allows this device not, in different areas of the culvert - in to the rollers parallel to the axis - different draw-off quantities of liquid and thereby influence the To take formation of a given thermal crown. A Extraction device for cooling water running off the lower work roll is not scheduled.

The present invention is based on the aforementioned prior art the task of an apparatus and a method for Cooling the work rolls of a roll stand in the preamble of Claim 1 to further develop the type mentioned and to improve that the above difficulties and technical Limits are overcome, in particular the influence of outlet-side cooling to the thermal behavior of the work rolls optimized and the heat of the roller surface as early as possible can be deprived of the penetration of heat into the depth of the Reduce work rolls as much as possible and beyond by zone-wise enforcing the removal of cooling water on the zonal formation of the thermal crown along the Take axis of the rollers.

• daß in sandwichartiger Zuordnung oberhalb der oberen Kühlwasser-Leitplatte eine Deckplatte unter Ausbildung eines flüssigkeitsführenden Spalts angeordnet und der Spalt an seinem der Walze abgewandten Ende mit einer Kühlwasser-Absaugung in Verbindung steht, und
• daß das unterhalb der unteren Kühlwasser-Leitplatte,. in den sich zwischen dieser mit dem Abstreifer und einem Oberflächenbereich der unteren Walze ergebenden flüssigkeitsführenden Eckbereich hineinragend, wenigstens ein Absaugrohr angeordnet und an eine Kühlwasser-Absaugung angeschlossen ist.

To achieve this object, the invention proposes in a device for cooling the work rolls of a rolling stand of the type mentioned in the preamble of claim 1,

• that in a sandwich-like arrangement above the upper cooling water guide plate, a cover plate is arranged to form a liquid-carrying gap and the gap is connected at its end facing away from the roller to a cooling water suction, and
• that that below the lower cooling water baffle. protruding into the corner of the liquid-carrying area resulting from this with the scraper and a surface area of the lower roller, at least one suction pipe is connected and connected to a cooling water suction device.

With the device according to the invention is through training a liquid-carrying gap and its connection to a powerful cooling water extraction for the upper work roll as well by arranging suction pipes in the between the lower Cooling water guide plate and a surface area of the lower roller resulting fluid-carrying corner area and its connection a powerful cooling water extraction system Optimization of the discharge conditions of the "used" cooling water created by a pressure drop artificially increased by means of negative pressure. This results in the possibility of removing the cooling water, For example, by connecting the laxative organs according to the invention to the suction side of powerful pumps within Control borders. This also results in an advantageous one Possibility of forcibly draining used cooling water on the outlet side of the rollers to increase them so far that dispensing with the arrangement of work roll cooling on the inlet side can be, which results in significant cost savings or extraction of space for installing new technologies on the inlet side of the Work rolls, such as B. roll gap lubrication, inline grinding system, Measuring systems etc result.

Further advantageous embodiments of the device according to the Invention are provided according to the subclaims. there can the measure taken with the device according to the invention be that the liquid-carrying gap through longitudinal walls in at least three - side - middle - side - parallel channel areas is subdivided and each of these channel areas has a predetermined one axial extension and individual cooling water extraction assigned. This can influence within predetermined limits on the cooling effect of the work rolls - seen in the axial direction - Be exercised to keep the thermal crown in the desired Way to influence.

A method for cooling the work rolls on the outlet side Roll stand of the type characterized in claim 1 is thereby characterized in that on the one hand in the inlet area in front of the suction piece of the gap and on the other hand in the corner area between the lower Work roll and the assigned cooling water guide plate after heat exchange water generated by the rollers by applying Vacuum through an upper and a lower cooling water suction is subtracted.

Furthermore, the method according to the invention provides that the cooling water suction via the axial extension of the work rolls divided into a number of suction areas and this different suction powers can be assigned.

Figur 1

eine Seitenansicht und teilweise im Schnitt eine Vorrichtung zur auslaufseitigen Kühlung der Arbeitswalzen eines Walzgerüstes entsprechend dem Stand der Technik,

Figur 2

in Seitenansicht und teilweise im Schnitt eine Vorrichtung zur auslaufseitigen Kühlung der Arbeitswalzen eines Walzgerüstes nach der Erfindung.

Further details, features and advantages of the invention result from the following explanation of an exemplary embodiment shown schematically in the drawings. Show it:

Figure 1

2 shows a side view and partly in section a device for cooling the work rolls of a roll stand on the outlet side in accordance with the prior art,

Figure 2

in side view and partly in section, a device for cooling the outlet side of the work rolls of a roll stand according to the invention.

The device shown in Fig. 1 for cooling the outlet side Work rolls 1, 2 of a roll stand 15, not shown in detail comprises for each roller a cooling water channel equipped with spray nozzles 3, 4 7, 8 on a height-adjustable spray bar. The The device has means 5 for supplying cooling water. medium for the orderly discharge of heated water are in this construction not provided. The rolling line is with x-x and in one dash-dotted line indicated. Assigned to the upper work roll 1 is a cooling water guide plate at an acute angle to the surface of the rolling stock 9 with a front, abutting the roller 1 Scraper 11 arranged. Is just below the rolling stock level x-x also an approximately horizontal cooling water guide plate 10 with a wiper 12 resting on the lower roller 2 is provided. The upper cooling water guide plate 9 is on the work roll 1 end facing away in a universal joint 17 and is supported by a power means, for example a pneumatic cylinder 13 with the Scraper 11 under given force approximately tangential to the upper work roll 1 created. The lower cooling water guide plate 10 is at the end facing away from the work roll 2 in a joint 18 stored and is with the scraper 12, for example, under the action their own weight in the stripping position.

Corresponding to the areas indicated with dark hatching cooling water flowing out there to a level of 16 and on the one hand the formation of free spray jets 3 and 4 considerably hinder, and on the other hand not drain quickly enough. This applies in particular to the upper cooling, since the scraper 11 with the upper cooling water guide plate 9 prevents the liquid can flow down freely. Have experiences further shown that the water of the lower work roll cooling is not can flow freely. This can lead to backflow come, which can have the consequence, for example, that the lower outlet side Scraper is raised.

This has the disadvantage that the fresh cooling liquid does not reach the rollers 1, 2 unhindered. As a result, it splashes in the backwater that forms, which means that only one in the Limited cooling effect compared to direct spraying of the rollers is achieved.

Figure 2 shows the design of the device on the outlet side Cooling of the work rolls 1, 2 of a roll stand according to the invention. The same functional elements with the same reference numbers Mistake.

The solution to the above problem is in the inventive Execution of the device achieved in that in sandwich Assignment above the upper cooling water guide plate 9 a cover plate 20 to form a liquid-carrying Gap 21 is arranged. The gap 21 is on the roller 1 facing away end 22 with a cooling water suction 30 in connection.

Below the lower cooling water guide plate 10, in which between this with the scraper 12 and a surface area of the lower roller 2 resulting liquid-carrying corner region 24 protruding, at least one suction pipe 25 is arranged and on a cooling water suction 31 connected.

• Die frische Kühlflüssigkeit wirkt direkt auf die Arbeitswalze 1, es muß daher nur ein geringer Flüssigkeitsfilm durch den Impuls der Sprühstrahlen durchdrungen werden;
• der Spritzbalken kann tiefer, d.h. näher am Walzspalt x-x angeordnet werden.
• infolge der Wirkung der Absaugung 30 wird Kühlflüssigkeit mit einer forcierten Geschwindigkeit an der Walze 1 vorbeigeführt. Dies führt zu einer signifikanten Erhöhung der Wärmeübergangszahl und damit zur Verbesserung der Kühlwirkung;
• es fließt weniger Wasser in undefinierbarer Weise ab, somit werden die Verschleißplatten der unteren Stützwalzen-Einbaustücke mit weniger Wasser umspült; die dort vorhandene Fettschicht wird länger aufrechterhalten, wodurch die Korrosion der Verschleißplatten erheblich reduziert wird.

The technical advantage of the embodiment according to FIG. 2 consists essentially in the fact that the stripper plate 9 is constructed in a sandwich construction and the cooling beam can be adjusted in height depending on the current work roll diameter and roll gap as shown in the double arrow 19. The gap 21 created by the sandwich construction is now used as a suction channel for the used cooling liquid. This has the following advantages:

• The fresh cooling liquid acts directly on the work roll 1, so only a small film of liquid has to be penetrated by the impulse of the spray jets;
• the spray bar can be arranged lower, ie closer to the roll gap xx.
• due to the action of the suction 30, cooling liquid is guided past the roller 1 at a forced speed. This leads to a significant increase in the heat transfer coefficient and thus to an improvement in the cooling effect;
• less water flows out in an indefinable way, so the wear plates of the lower support roller chocks are washed with less water; the grease layer there is maintained for a longer time, which considerably reduces the corrosion of the wear plates.

Below the scraper 12 and the lower cooling water guide plate 10 is also essential here due to the arrangement of the suction channel 25 Reduction of the undefined amount of cooling water reached. The same advantages apply here as with the upper one Cooling water extraction 30. For example, the extraction per roll stand carried out with a vertical submersible pump in dry installation which is also suitable for slurping. Alternatively offers it is important to have several individual pumps in parallel per spray bar to arrange. This has the advantage that depending on the Different volume flows can be sucked off and thus influence on the thermal crown of the work rolls 1, 2 can be taken.

The cover plate 20 is at its area facing the roller 1 below Formation of a flow-optimized suction piece 23 at the inlet area of the gap 21 bent upwards. This will be very beneficial Flow conditions reached when the cooling water draining off.

This becomes very straightforward with the lower work roll realized by the or the suction pipes 25 in the range of their suction openings are bent upwards.

It can be provided that at least the aerodynamic Suction piece 23 of the liquid-carrying gap of the axial extent corresponds to the roller 1, and that the liquid-carrying gap 21 on its transverse sides with the formation of at least one channel 26 is closed.

Furthermore, the measure can be taken that the cooling water suction 30, 31 each with a number of flexible hoses 32, 33 are connected to the suction side of at least one pump.

To create the possibility that depending on the bale width different volume flows can be sucked off in order to To influence the thermal crown of the work rolls 1, 2, can also be provided that the liquid-carrying Gap 21 through longitudinal walls in at least three sides - middle - side - parallel channel areas and each of these channel areas is divided a given axial extent and an individual Cooling water suction is assigned.

It can also the cooling water suction 31 of the lower work roll 2 over the axial extent of each, a number in some areas of suction pipes 25 can be assigned, each to an individual Cooling water suction are connected.

During operation of the device, on the one hand, in the inlet area the suction piece 23 of the gap 21 and on the other hand in the corner region 24 between the lower work roll 2 and the associated cooling water guide plate 10 after heat exchange with the rollers 1, 2 accruing Water by applying negative pressure through an upper and a lower one Cooling water suction 30, 31 deducted in a defined manner. The Cooling water suction 30, 31 are on the axial extent the work rolls 1, 2 divided into a number of suction areas and assigned different suction capacities to them.

LIST OF REFERENCE NUMBERS

1

upper work roll

2

lower work roll

3

upper spray nozzles

4

lower spray nozzles

5

upper cooling water supply

6

lower cooling water supply

7

upper cooling water channel

8th

lower cooling water channel

9

upper cooling water guide plate

10

lower cooling water guide plate

11

upper scraper

12

lower scraper

13

pneumatic cylinder for lifting / lowering

15

Rolling mill stand

16

Drain liquid level

17

universal joint

18

joint

19

Double arrow, height adjustability

20

cover plate

21

gap

22

averted end

23

suction piece

24

corner

25

suction tube

26

channel

30

Cooling water suction on top

31

Cooling water suction at the bottom

32

flexible hose on top

33

flexible hose below

Claims (13)

1. Device for cooling working rolls (1, 2) of a roll stand, comprising, for each roll, a cooling water channel (7, 8), which is equipped with spray nozzles (3, 4), at a spray beam as well as means (5, 6) for feed of cooling water and for discharge of heated water, as well as in association with the upper working roll (1) a cooling water guide plate (9), which is arranged at an acute angle to the roll stock upper surface, with a stripper (11) at the front side and associated with the roll (1), and closely below the roll stock plane (x-x) an approximately horizontal cooling water guide plate (10) with a stripper (12) associated with the lower roll (2), characterised in that

   a cover plate (20) is arranged in sandwich-like association above the upper cooling water guide plate (9) with formation of a liquid-conducting gap (21) and the gap (21) is disposed in connection at the end (22) thereof remote from the roll (1) with a cooling water suction means (30), and

   at least one suction pipe (25) is arranged below the lower cooling water guide plate (10) and projects into the liquid-conducting comer region (24) resulting between this plate with the stripper (12) and a surface region of the lower roller (2), the suction pipe being connected with a cooling water suction means (31).
2. Device according to claim 1, characterised in that this is arranged only at the outlet side of the working rolls (1, 2).
3. Device according to claim 1 or 2, characterised in that the cover plate (20) is bent over at the region thereof facing the roll (1) with formation of a suction member (23) at the inlet region of the gap (21).
4. Device according to claim 1, 2 or 3, characterised in that the suction pipe or pipes (25) are bent over in the region of the suction openings thereof.
5. Device according to one or more of claims 1 to 4, characterised in that at least the suction member (23) of the liquid-conducting gap (21) corresponds with the axial length of the roll (1).
6. Device according to one or more of claims 1 to 5, characterised in that the liquid-conducting gap (21) is closed at its transverse sides with formation of a channel (26).
7. Device according to one or more of claims 1 to 6, characterised in that the cooling water suction means (30, 31) are each connected with a respective number of flexible hoses (32, 33) at the suction side of at least one pump.
8. Device according to one or more of claims 1 to 7, characterised in that the liquid-conducting gap (21) is divided by longitudinal walls into at least three - side - middle - side - parallel channel regions and a preset axial length and an individual cooling water suction means are associated with each of these channels regions.
9. Device according to one or more of claims 1 to 7, characterised in that the cooling water suction means (31) of the lower working rolls (2) are associated over the axial length thereof in each instance regionally with a number of suction pipes (25) which are each connected with an individual cooling water suction means.
10. Method of cooling the working rolls (1, 2) of a roll stand of the category characterised in claim 1, characterised in that water precipitating after heat exchange with the working rolls (1, 2) on the outlet side of the working rolls (1, 2) and in the inlet region of a gap (21) between the upper working roll (1) and an associated cover plate (20) on the one hand and in the comer region (24) between the lower working roll (2) and an associated cooling water guide plate (10) on the other hand is removed by application of underpressure via an upper and a lower cooling water suction means (30, 31).
11. Method according to claim 10, characterised in that the cooling water suction means (30, 31) are divided over the axial length of the working rolls (1, 2) into a number of suction regions and these are associated with different suction performances.
12. Method according to claim 10 or 11, characterised in that the suction away per roll stand is carried out by at least one vertical immersion pump in dry format, which is also suitable for sucking-up operation.
13. Method according to at least one of claims 10 to 12, characterised in that the spray beam together with the cooling water channel (7) can be adjusted in height in relation to the actual working roll diameter and the rolling gap independently of the stripper (11) and the cooling water guide plate (9, 10).

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