EP2403663B2 - Method and cooling device for cooling the rollers of a roll stand - Google Patents

Description

The invention relates to a method and a cooling device for cooling the rolls, in particular the work rolls of a roll stand, see e.g. JP-A 63303609 .

When rolling metals, the rolls involved in the rolling process, the work rolls, are heated. To protect them from damage and to achieve the longest possible service life, the rollers are cooled. Most rolling mills nowadays use cooling systems that spray a cooling liquid onto the roll surface with the aid of nozzles (preferably flat jet nozzles). Such cooling is referred to as spray cooling. Depending on the rolling mill, the selected pressure level is between 6 bar and 12 bar and in exceptional cases 20 bar. In addition to the task of cooling the work rolls as intensively as possible in order to limit their thermal load and geometric expansion, the work roll cooling should keep the roll free of dirt, oxide and scale particles. The cooling effect increases as the amount of coolant increases and the coolant pressure increases. The disadvantage of the system is that a large amount of energy is required and the maintenance of the pumps is more complex at higher pressures.

Another option for cooling the work rolls is low pressure cooling. From the WO 2008/104037 A1 a cooling device with highly turbulent cooling in the low-pressure range is known, in which a roller is cooled with the aid of nozzles or bores which are arranged on a concave-shaped cooling beam. By arranging the cooling bar and with the help of side plates that are attached to the front of the cooling bar, a uniformly designed water cushion with a turbulent and undirected flow is formed. However, the cooling device only works satisfactorily and reproducibly if the diameter range of the roller, which results from the grinding, is matched to the curvature of the cooling device. Since the sanding area of a roller that is customary today is approx. 10% of the maximum roller diameter, several cooling devices are necessary for different roller diameters, which makes sophisticated roller logistics necessary. It should be noted as a disadvantage that it is not possible to adjust the curvature of the cooling device to the changed roll diameter for each stand and after each work roll change and thus the distance between the nozzles or bores and the roll surface and thus the cooling effect during the rolling process changes from roll change to roll change.

Low-pressure cooling in the form of flow cooling is used in the DE 36 16 070 C2 described, with the cooling liquid in a directed manner in a defined, relatively narrow gap between the work roll surface and a cooling shell and is guided past the roller surface with external pressure. The pressure level is lower and depends on the gap width and flow velocity. Higher cooling effects are achieved here through higher flow velocities. Due to the lower pressure level, the system has no cleaning effect on the roll surface. The disadvantage of this device is that a separate cooling block is required for each roller, since this is mounted on the roller chocks. A large number of these cooling blocks is therefore required for a conventional hot rolling mill. The adjustment of the gap width to different work roll diameters as well as the following of the cooling block of the respective work roll position has also proven to be disadvantageous or very complex, since the gap has to be set manually and outside the roll stand.

The JP 07-232203 discloses a method and a device for cooling the rolls of a roll stand with low-pressure cooling, in which the rolls are acted upon with a low-pressure cooling liquid, the rolls also being subjected to high-pressure cooling at the same time as the low-pressure cooling, the rolls being subjected to high-pressure cooling directly a coolant under high pressure can be sprayed.

Based on the described prior art, the object of the invention is to provide a method and a cooling device with which the rolls of a roll stand are optimally cooled in order to protect them from thermomechanical fatigue and wear, with energetic aspects such as minimizing the The required coolant flow and the coolant pressure as well as any construction and manufacturing costs must be taken into account.

In terms of the method, the set object is achieved with the features of claim 1 and in terms of the device with the features of claim 11.

In principle, all rolls of a roll stand can be cooled with the cooling device according to the invention; however, the invention has particular application to work rolls.

Appropriately, about 20% of the total amount of coolant is fed to the high-pressure cooling system and about 80% of the total amount of coolant is fed to the low-pressure cooling system that produces the main cooling effect. The cooling liquid can be taken from an elevated tank, for example 7-12 m high, or generated directly by low-pressure pumps. The required pressure range for the coolant of the Low pressure roller cooling is dependent on the thermal load on the rollers and is between z. B. 0.5 to less than 5 bar. A spray cooling, coolant curtain, gap cooling or flow cooling, highly turbulent cooling ( Figure 2 ) or a combination of the various low-pressure systems can be used.

As with conventional systems, a single-row or double-row spray nozzle bar can be used for high-pressure roller cooling, which simultaneously fulfills the task of cleaning the roller surface or removing scale. The small amount of cooling liquid of approx. 20% of the total amount of cooling liquid is sufficient for this task, with a pressure range between 5 and 50 bar, preferably 12 bar, being required for the cooling liquid. The pressure range used for the cooling liquid for high-pressure roll cooling depends on the rolling parameters, thickness reduction, specific surface pressure in the roll gap, rolling speed, strip temperatures, roll material and rolled material.

• Energiebedarf der Pumpe (ohne Berücksichtigung des Pumpenwirkungsgrades) am Beispiel für eine 2m-Warmbandstraße mit 5000 m³/h Gesamt-Walzenkühlmittelstrom (Pumpenleistung = Volumenstrom * Druckerhöhung (Hinweis: 36 ist ein Umrechnungsfaktor)

From an environmental point of view, a reduction in the total energy that the pumps consume while at the same time fulfilling all system tasks in the sense of "Green Plant Technology" is advantageous. If you compare the pump energy used for conventional roller cooling at higher pressure with the proposed combined low-pressure / high-pressure cooling system, the following differences emerge:

• Energy requirement of the pump (without considering the pump efficiency) using the example of a 2m hot strip mill with 5000 m ³ / h total roll coolant flow (pump output = volume flow * pressure increase (note: 36 is a conversion factor)

• Druckniveau z. B. 12 bar
• Pumpenleistung = 5000 m³/h * 12 bar/36
• Pumpenleistung = 1667 KW

Conventional roller cooling:

• Pressure level z. B. 12 bar
• Pump output = 5000 m ³ / h * 12 bar / 36
• Pump power = 1667 KW

• Druckniveau z. B. 12 bar
• Hochdruckkühlmittelmenge 1000 m³/h und
• Druckniveau z. B. 2 bar
• Niederdruckkühlmittelmenge 4000 m³/h
• Pumpenleistung = 1000 m³/h * 12 bar/36 + 4000 m³/h * 2 bar/36
• Pumpenleistung = 333 KW + 222 KW = 555 KW

Combined low-pressure and high-pressure cooling:

• Pressure level z. B. 12 bar
• High pressure coolant quantity 1000 m ³ / h and
• Pressure level z. B. 2 bar
• Low pressure coolant quantity 4000 m ³ / h
• Pump output = 1000 m ³ / h * 12 bar / 36 + 4000 m ³ / h * 2 bar / 36
• Pump power = 333 KW + 222 KW = 555 KW

With the combined low-pressure and high-pressure cooling, a significantly lower amount of energy is required. For the above example, the drive power for the pumps is reduced by approx. 1.1 MW.

In the case of increased dirt or scale particles and, for example, a rough roll surface or a fire crack pattern, the pressure level can be increased accordingly. The roller surface can be observed by a camera in order to deduce the change in pressure level. Furthermore, to influence the oxide layer thickness on the roller, the pressure level can be individually adjusted in steps (for example by switching pumps on or off) or steplessly.

The combined low-pressure and high-pressure cooling is provided for the front stands of a hot strip mill, for example. Pure low-pressure cooling can then also be used in the rear frames.

The high-pressure chilled beam works over almost the entire length of the bale or in the width direction and can be designed with a local cooling effect. If only a simple low-pressure shell cooling is used in an application, then a combination with the cooling is in accordance with the Japanese patent application JP 07290120 conceivable and intended. With the help of a motor, two spray nozzle bar sections are moved axially or in the width direction and the work roll is cooled differently locally. Instead of an electric or hydraulic motor with a threaded rod or two motors for separate adjustment on the left and right side, a hydraulically moved single or multi-part articulated rocker arm with spray bars or rotatable nozzle units attached to it can be implemented to direct the coolant jets onto the desired areas of the work roll (within or next to the belt area) to have a positive influence on the belt profile and flatness.

Analogous to the embodiment with the spray bar sections that can be moved in the width direction, short segment shell parts with a width of 150 mm, for example, can be axially adjustable in the width direction and only act locally (e.g. symmetrically at two points on the work roll) for a segment of the low-pressure shell cooling be.

The task of the low-pressure work roll cooling system used in accordance with the invention is to cool optimally and efficiently, the cooling effect (heat transfer from the roll to the cooling liquid) being high despite the low cooling liquid pressure. this causes a lower roller temperature or can be used to reduce the amount of coolant. Flow cooling is preferably used as efficient low-pressure roller cooling, in which the cooling liquid is conducted past the roller surface in a relatively narrow gap between the work roller and an arcuate cooling shell.

According to the invention, the cooling device consists essentially of movable cooling shell segments that are connected to one another in an articulated manner. Preferably three, but usually two cooling shell segments are used. In special cases, however, only one cooling shell segment can be used. The individual cooling shell segments preferably have joints or joint halves on their sides or at their ends. On the middle cooling shell segment there is at least one pivot point which accommodates at least one, preferably two cylinders (hydraulic or pneumatic cylinders). The cylinders have their second stop on the other links of the adjacent cooling shell segments. The cylinders can be arranged in the center of the cooling beam or on both sides at the edges. Instead of the shell adjustment with cylinders, adjustment with, for example, hydraulic motors or electric motors is conceivable. The console or the cooling beam support with mounting holes is located on the middle cooling shell segment. Using the cooling beam support, it is possible to move the central cooling shell segment and thus all components connected to it, with horizontal, vertical and rotating movement being possible. The position adjustment is carried out with a multi-link articulated gear, which is operated pneumatically, hydraulically or electromechanically. An advantageous adjustment of the central cooling beam support in the horizontal direction is also possible via, for example, a longitudinal or elongated hole guide and pneumatic or hydraulic cylinder.

• Kalibrieren der Kühlschalen
  Zum Einstellen der Positionen der Kühlschalensegmente werden die Kühlbalkenträgeranstellung und die Kühlschalensegmente mit den zugeordneten Zylindern und Gelenkgetrieben mit definiertem Druck gegen die Walze angedrückt. In dieser Position werden die Weggeber auf Null gesetzt. Ausgehend hiervon und mit Kenntnis der geometrischen Zusammenhänge kann danach ein definierter Spalt zwischen Kühlschalensegment und Walze eingestellt werden. Der Kalibrierprozess des Kühlsystems kann während der Gerüstkalibrierprozedur durchgeführt werden.
• Berechnen der Positionen
  Da die geometrischen Zusammenhänge (Walzendurchmesser, Walzenpositionen in vertikaler Richtung, Zylinderpositionen, Abstände der Gelenke und Drehpunkte, Position des mehrgliedrigen Gelenkgetriebes etc.) bekannt sind, kann in guter Näherung die Schalenposition bzw. mittlere Spaltbreite errechnet werden. Jede relative Änderung der Walzenposition (bei z. B. Banddickenänderung) während des Walzprozesses ist so umrechenbar.
• Einsatz von Sensoren
  Durch Einsatz von Abstandssensoren kann der Spalt direkt gemessen und die Zylinder und Gelenkgetriebe entsprechend mit einem Regelsystem eingestellt werden.

The cylinders have position measuring systems and pressure sensors. The position of the cylinder and thus the gap setting or determination of the distance between the cooling shell segment and the roller as well as the monitoring of the set positions can be determined and carried out in the following different ways, whereby a combination of the methods listed is also possible:

• Calibrating the cooling shells
  To adjust the positions of the cooling shell segments, the cooling beam support adjustment and the cooling shell segments with the associated cylinders and articulated gears are pressed against the roller with a defined pressure. In this position, the position sensors are set to zero. Based on this and with knowledge of the geometric relationships, a defined gap can then be created between the cooling shell segment and the roller. The cooling system calibration process can be performed during the framework calibration procedure.
• Calculate the positions
  Since the geometrical relationships (roller diameter, roller positions in the vertical direction, cylinder positions, distances between the joints and pivot points, position of the multi-link joint gear, etc.) are known, the shell position or mean gap width can be calculated to a good approximation. Any relative change in the roll position (e.g. in the event of a change in strip thickness) during the rolling process can thus be converted.
• Use of sensors
  By using distance sensors, the gap can be measured directly and the cylinders and articulated gears can be adjusted accordingly with a control system.

Compared to a cooling device according to the prior art, the cooling device according to the invention adapts to the respective roll diameter and roll positions thanks to the existing joint mechanisms, since the adjustment systems of the cooling beams are connected to the thickness control and follow the vertical movement of the work rolls, for example when changing the thickness. When the scaffolding is opened (for example in the event of an emergency opening), the cooling shells are automatically swiveled back a little.

In a constructive embodiment, the cooling device forms, with the aid of a sealing function, a space from which only a small amount of cooling liquid reaches the environment. Sealing takes place by placing the shell at the top and bottom of the work roll, which can be pressed on with a predetermined pressure, and / or by applying dynamic pressure to the edge of the cooling shells. This arrangement makes it possible to form an almost closed cooling circuit.

Positioning the shells just in front of the roller creates a gap through which the coolant flows. The gap widths between the cooling shell and the work roll are set specifically and reproducibly during operation, regardless of the roll diameter, between 2 and 40 mm, for example to 5 mm. The gap between the work roll and the cooling shell can - seen tangentially - be approximately the same or the shell is adjusted to narrow towards the outlet.

When using the flow cooling provided according to the invention, two different cooling variants are possible, the flow cooling in sections and the continuous flow cooling.

The section-by-section flow cooling is divided into sections. The cooling liquid flows from a, for example, funnel-shaped rectangular slot into the individual areas of the cooling shell against the roller and is deflected to both sides (up or down) or mainly to one side, the cooling shell forcing a flow along the roller. As a result of the flow deflection and the flow at a higher relative speed along the roller, the cooling liquid efficiently absorbs the heat from the roller. The heated coolant then flows back to the rear, making space for new, cold coolant. The cooling bars are designed in such a way that the cooling liquid flowing backwards (away from the roller) can flow away well, primarily with a gradient. The coolant flowing back on the upper side is also deflected to the side by means of deflection plates in order to reduce the pool effect above the scraper. The individual cooling areas are separated from one another by a mutual shield, so that the cooling liquids of the adjacent cooling beams hardly interfere with one another.

With continuous flow cooling, the cooling liquid is guided over a larger continuous angular range of the roller. A small, adjustable gap width and a high flow velocity are required in order to generate good heat transfer. The width of the gap and the amount of coolant must therefore be coordinated. The coherent flow cooling can be operated on the countercurrent or co-current principle. Due to the long distance between the inlet and outlet side, the cooling shell needs to be sealed on the side. As an alternative to the counter-current or co-current principle, an operating mode can also be carried out in which the cooling liquid is supplied to the upper and lower cooling beam piping. The process then takes place specifically to the sides. With this principle, the cooling liquid flowing tangentially to the roller absorbs the heat and is then deflected to the side. The warm cooling liquid thus heats the roller areas next to the strip running area and there leads to the desired positive influence on the thermal crowns. This system is particularly effective when zone cooling is carried out in which the areas next to the belt are not directly cooled.

In the case of zone cooling, only certain areas in the length of the roller in the coolant supply channel of the cooling beam are released for the flow or narrow cooling shells with differently set gap widths are arranged next to one another and spaced apart. Due to the different gap widths result for the narrow ones Cooling shells a corresponding different specific cooling liquid flow and thus a different cooling of the work roll for each cooling shell. To separate the different coolant flows, a barrier coolant or a gap seal is inserted between the narrow cooling shells, depending on the design.

• Einstellung der Kühlmittelmenge und Druckniveau für den Niederdruckund ggf. für den Hochdruckteil abhängig von Banddickenabnahme, spezifische Flächenpressung im Walzspalt, Walzgeschwindigkeit, Bandtemperaturen, Walzenwerkstoff und gewalztes Material sowie der gemessenen und/oder der berechneten Walzentemperaturen und/oder beobachteten Walzenoberfläche und ebenfalls abhängig von der eingestellten Kühlmittel-Beaufschlagungsbreite,
• Einstellung der Kühlmittelmenge über der Bandbreite durch Verstellung der Austrittsöffnungen des Zuführkanals (parabolisch, Kurve höherer Ordnung oder zonenweise) oder/und Verstellung der Spaltbreite zwischen Kühlschale und Arbeitswalze in Abhängigkeit der Bandbreite und/oder Einstellung der Position der in Breitenrichtung verstellbaren Spritzdüsenbalkenabschnitte und/oder gemessenem Profil- und Planheitszustand über der Bandbreite,
• Austausch von Signalen mit der Dickenregelung (Gerüstanstellung),
• Beschreibung der geometrischen Zusammenhänge der beweglichen Teile der Kühleinrichtung sowie Berücksichtigung der Anstellposition, Passlineposition und Arbeitswalzendurchmesser zwecks optimaler Positionsermittlung bzw. Berechnung der Positionsänderungen,
• Festlegung der Anschwenkposition von Kühlbalkenträger sowie Kühlschalenanstellposition mit Hilfe der Zylinder unter ggf. Verwendung der Druck- und Weggebersignalen,
• Steuerung der Kalibrierprozedur für die Kühlschalenpositionen.

A computer model (process model or level 1 model) that fulfills the following tasks is used for optimal control of the cooling device:

• Setting of the coolant quantity and pressure level for the low pressure and, if applicable, for the high pressure part depending on the strip thickness decrease, specific surface pressure in the roll gap, rolling speed, strip temperatures, roll material and rolled material as well as the measured and / or calculated roll temperatures and / or observed roll surface and also dependent on the set Coolant application width,
• Adjustment of the amount of coolant over the bandwidth by adjusting the outlet openings of the feed channel (parabolic, higher-order curve or zone-wise) and / or adjustment of the gap width between the cooling shell and work roll depending on the bandwidth and / or adjustment of the position of the spray nozzle bar sections adjustable in the width direction and / or measured Profile and flatness condition over the strip width,
• Exchange of signals with the thickness control (stand adjustment),
• Description of the geometrical relationships of the moving parts of the cooling device as well as consideration of the pitch position, pass line position and work roll diameter for the purpose of optimal position determination or calculation of position changes,
• Determination of the swiveling position of the cooling beam support as well as the cooling shell positioning position with the aid of the cylinder, possibly using the pressure and displacement encoder signals,
• Control of the calibration procedure for the cooling tray positions.

Further advantageous refinements of the invention are the subject of the dependent claims.

Further details of the invention are explained in more detail below using exemplary embodiments shown in schematic drawing figures.

• Fig. 1 eine Sprühkühlung nach dem Stand der Technik,
• Fig. 2 eine hochturbulente Strömungskühlvorrichtung nach dem Stand der Technik,
• Fig. 3 eine erfindungsgemäße Kühlvorrichtung mit mehreren Kühlschalensegmenten, die gelenkig miteinander verbunden sind,
• Fig. 4 die Kühlvorrichtung der Fig. 3 mit alternativer Kühlflüssigkeitsströmung,
• Fig. 5 eine erfindungsgemäße Kühlvorrichtung mit radial geteilter Kühlschale
• Fig. 6 die Kühlvorrichtung der Fig. 5 mit austauschbarer Kühlschale bzw. Kühlplatte,
• Fig. 7 eine Kühlvorrichtung mit durch Federn angepresste Kühlschalensegmente,
• Fig. 8 eine Kühlvorrichtung mit Walzspaltkühlung / Walzspaltschmierung und kombinierter Niederdruck-Hochdruckwalzenkühlung,
• Fig. 9 eine Kühlvorrichtung mit in den Kühlschalen eingebrachte Löcher,
• Fig. 10a-f Düsen- und Schalenausbildungen,
• Fig. 11a-c eine Spaltbreitenverstellung,
• Fig.12 eine Spaltbreitenverstellung,
• Fig. 13 eine Zonenkühlung,
• Fig. 14 eine Spaltabdichtung,
• Fig. 15a, b eine örtlich wirkende axial verstellbare Walzenkühlung,
• Fig. 16 Biegefedern als gelenkige / elastische Verbindung zwischen benachbarten Kühlschalensegmenten.

Show it:

• Fig. 1 state-of-the-art spray cooling,
• Fig. 2 a highly turbulent flow cooling device according to the state of the art,
• Fig. 3 a cooling device according to the invention with several cooling shell segments that are articulated to one another,
• Fig. 4 the cooling device of the Fig. 3 with alternative coolant flow,
• Fig. 5 a cooling device according to the invention with a radially divided cooling shell
• Fig. 6 the cooling device of the Fig. 5 with exchangeable cooling tray or cooling plate,
• Fig. 7 a cooling device with cooling shell segments pressed on by springs,
• Fig. 8 a cooling device with roll gap cooling / roll gap lubrication and combined low-pressure / high-pressure roll cooling,
• Fig. 9 a cooling device with holes made in the cooling shells,
• Figures 10a-f Nozzle and shell designs,
• Figures 11a-c a gap width adjustment,
• Fig.12 a gap width adjustment,
• Fig. 13 a zone cooling,
• Fig. 14 a gap seal,
• Figures 15a, b a locally acting axially adjustable roller cooling system,
• Fig. 16 Flexural springs as an articulated / elastic connection between adjacent cooling shell segments.

In the Figure 1 a spray cooling system according to the prior art is shown, in which a cooling liquid 7 is sprayed onto the roll surface of the work rolls 1, 2 by means of nozzles 27. Due to the relatively large distance between nozzle and roller, a higher coolant pressure range (e.g. 6 ... 15 bar) is selected. Wipers 17 arranged on the inlet and outlet sides ensure that as little cooling liquid as possible can come into contact with the rolling stock 4.

The Figure 2 shows another known possibility for cooling the work rolls 1, 2. This is a highly turbulent cooling in the low pressure range. With the aid of nozzles 27 arranged on the inlet side and through the bores made on the outlet side in the concavely curved, connected cooling shell 11, water is raised the roll surface of the work rolls 1, 2 is sprayed and a water cushion with a turbulent and undirected flow is formed in front of the work roll. The exchange of water happens relatively slowly in this construction, which has a negative impact on the cooling efficiency.

A coherent flow cooling according to the invention with a coherent cooling shell 11 is in the Figure 3 shown. The cooling device 10 according to the invention here essentially consists of articulated cooling shell segments 13 which surround the work roll 1, 2 at a distance, forming a gap 30 in a larger angular range.

Due to the articulated connection claimed between the individual cooling segments of a cooling shell, an optimal adaptation of the cooling shell to the individual diameter of the rollers and thus an energetically more favorable cooling of the rollers is possible. The hinge axis of the articulated connection is preferably parallel to the longitudinal axis of the roller.

Via a feed pipe 25 and the inlet opening 29, the cooling liquid 7 flows in countercurrent to the direction of rotation of the roller 5 into the gap 30, in order then to flow out again through the outlet opening 24 and the discharge pipe 26. If the discharge pipe 26 or the outlet opening 24 is closed or not implemented in a special case, a coolant drain can be generated transversely to the roller in a targeted manner. Lateral seals are then only partially present here. The segment lengths of the cooling shell segments 13 forming the gap 30 should be approximately the same, so that when the diameter of the work roll 1 changes, the cooling shell segments 13 can optimally follow the change in curvature of the roll jacket surface 6. The individual cooling shell segments 13 have joints or joint halves at their ends which, when connected to one another, form a corresponding number of joint pivot points 22 and pivot points 21 which are connected to one another by cylinders 20, for example hydraulic or pneumatic cylinders. On the middle cooling shell segment 13 is the cooling beam support 16 with a pivot point 23 through which it is possible to move the cooling shell segments 13 and all components connected to it in the illustrated (horizontal, vertical and rotating) adjustment directions 45 of the cooling beam support with a to move multi-link linkage, not shown here. A stripping device 17 arranged below the cooling shell 11 ensures that as little cooling liquid 7 as possible reaches the rolling stock 4.

Via sensors 37 for distance measurement, pressure gauges 36 in the cylinder connection lines and displacement gauges 39 arranged on or in the cylinders 20 the entire cooling shell 11 can be positioned. With temperature sensors 38 (in the middle of the roll or across the width), the roll temperature is measured continuously in order to regulate the size of the gap 30 accordingly in order to maintain the desired cooling effect.

The cooling devices described below are constructed in a similar way, which is why the equivalent details relating to the construction are no longer described, but in some cases only the reference symbols already mentioned above are shown.

An alternative flow guidance of the cooling liquid 7 within the gap 30 formed by the cooling shell segments 13 of the cooling shell 11 and the roller jacket surface 6 compared to that in FIG Figure 3 described flow is in the cooling device 10 of the Figure 4 shown. The supply pipes 25 for the cooling liquid 7 to be used with low pressure LP are arranged here on the upper and lower cooling shell segment 13, so that here the partial quantities of cooling liquid are fed through the gap 30 in countercurrent and cocurrent, based on the direction of rotation of the rollers 5. The directions of flow are indicated by arrows 43. To seal the gap 30, the upper and lower edges of the cooling shell 11 are designed with a contact surface 46, for example a hard tissue plate, which is guided in a sealing manner against the roller jacket surface 6. Since only a lateral drainage of the cooling liquid 7 from the gap 30 is possible (discharge pipes are not present), the gap 30 is opposite to the gap width Fig. 3 enlarged. The adjustment of the individual cooling shells is carried out as in Figure 3 by means of cylinder 20. Instead of cylinders, helical springs can also be used there in a simplified manner. In addition to the cooling carried out on the outlet side with the cooling shell 11 arranged there, each work roll 1, 2 is also cooled on the inlet side. Since the achievable cooling is not in the foreground here, z. B. Spray cooling with low pressure LP using nozzles 27.

A cooling device 10 with a sectional low-pressure flow cooling is shown in FIG Figure 5 . In contrast to the Figures 3 and 4th , in which the cooling shells 11 are composed of cooling shell segments 13, but coherently form a uniform, self-moving cooling shell 11, the cooling shell segments 13 of the now radially divided cooling shell 12 are also spatially separated from one another and form separate flow cooling areas s1, s2, s3. From low pressure (LP) feed pipes 25 the cooling liquid flows here via a funnel-shaped output slot 44 in the middle area of a cooling shell segment 13 from an outlet opening 24 against the work roll 1, 2 and is deflected up and down on both sides. To the cross To limit the amount of water flowing (in the width direction), mechanical side seals can be arranged. Each cooling shell segment 13 forces a flow in accordance with the drawn arrows 43 along the roller jacket surface 6 and then backwards. The cooling shell segments 13 are designed in such a way that the cooling liquid flowing backwards (away from the roller) can flow away well with a gradient. By means of deflection plates (not shown), the cooling liquid flowing back on the upper side is additionally directed to the side in order to reduce the pool effect above the scraper 17. The outlet openings 24 of the cooling shell segments 13 can be provided with an exchangeable mouthpiece (e.g. rectangular nozzle) so that, if necessary, the cross-section and the shape can be easily adapted to changed conditions. In this exemplary embodiment, high-pressure (HP) nozzles are arranged between the scrapers 17 and the cooling shells 12, by means of which the low-pressure / high-pressure cooling combined according to the invention is implemented. As shown, the high-pressure spray bar can be arranged separately on the cooling bar support 16 or attached to a cooling shell segment so that it can be adjusted with it.

In the Figure 6 it is indicated that a completely exchangeable cooling shell plate 47 is attached to the cooling beam of the cooling device 10. Since the mouthpieces of the nozzle openings of the outlet openings 24 can also be exchanged here, the possibility of changing the entire cooling bowl with mouthpiece or also separately is possible. The cooling shells of a flow cooling area can also be divided into two parts, so that the outlet opening 24 can be easily adjusted by relative displacement and subsequent fixing of the two halves. Furthermore, slightly different shell thicknesses or gap widths per cooling beam can be set and the amount of cooling liquid that flows up and down can be influenced.

Instead of the previous exemplary embodiments Figures 3 to 6 To use cylinder for adjusting the individual shells, is in the cooling device 10 of the Figure 7 an alternative solution is disclosed and illustrated. Here the cooling beam support 16 with the central cooling shell segment 13 is positioned in front of the roller. The two other cooling shell segments 13 rest against the work rolls 1, 2 with the aid of a straight or curved transverse bar 48 which can be rotated in a small defined area with the corresponding spring contact pressure of the spring 8. Alternatively, in the area of the cylinder (see Figures 3 - 6 ) Coil springs 8 with appropriate brackets at the ends. The gap 30 is determined by spacer plates 49 between the cooling shell 13 and the work roll 1, 2. The material for the spacer plates is such. B. hard fabric, aluminum, cast iron, self-lubricating metals or plastic. The spacer plates 49 are arranged only in the cooling bar edge area to the Not to disturb coolant flow in the middle. Optional spacer plates 49 that extend over the length of the chilled beam are also conceivable. These can be used to adjust the distance or to influence the direction of flow of the coolant. These spacer plates can also be attached to the central cooling shell segment 13 (not shown). With a generated coolant flow to the side, the edge areas of the work roll (next to the strip) are specifically heated from the center by the heated coolant.

If the work roll diameter areas in which the cooling is operated are small or in the same area per stand, a rigid cooling system is required as a special case, i. H. provided with immovable cooling shells (without cylinder between the shells and without springs 8). The use of rigid spacer rods instead of movable cylinders 20 is then also advantageously possible. The gaps between the roller and the cooling shell then vary somewhat, but the system with the sectional flow cooling is still effective and the system is simpler to manufacture. Only the cooling beam support has to be positioned in front of the roll, depending on the work roll diameter and the work roll position, so that the gaps, that is to say the outlet openings, are arranged relatively close in front of the roll. The construction can be carried out the same for several stands and the adaptation to the different stand diameter ranges of a rolling train is done only by means of the length-adjustable rods.

In the cooling device 10 of the Figure 8 In addition to the combined low-pressure / high-pressure cooling described so far, a low-pressure flow cooling system with integrated roll gap lubrication 19 and roll gap cooling 18 is also arranged on the inlet side. At the same time, the Fig. 8 discloses how different high and low pressure systems can be combined with one another. The flow of the cooling liquid 7 can be divided under a cooling shell or, as is shown here by way of example on the inlet side and outlet side, a larger amount of coolant can preferably be directed in one direction. To increase the heat transfer, a flow against the direction of rotation is advantageous.

The area in which the roll gap lubrication 19 is arranged is kept largely dry by the generated flow direction of the work roll cooling and / or by cooling shells 50 or cooling shells 51 provided with an elastic plastic surface with elastic plastic or hard tissue panels, for which a slight contact pressure is applied by the cooling beam support mechanism is generated over the plates on the roller. The panels themselves are continuous across the width and have an elastic effect due to their structural design (not shown). The area of the roll surface (seen in the direction of rotation) before the application of the Roll gap lubricant is optionally designed with a compressed air jet (not shown) in order to blow the roll surface dry in a defined manner.

Instead of using, for example, three cooling bars with a rectangular nozzle, it is according to the cooling device 10 of the Figure 9 It is also possible to design the three cooling bars with exchangeable cooling shells 47 in which many offset holes 52 are drilled, from which individual jets of coolant spray against the rollers 1, 2 from a short distance. Flow cooling in sections can also be established in this way. The holes are offset in the width direction so that the most uniform possible cooling effect is created across the width. The cross-sectional size and spacing of the holes 52 can be designed differently over the width of the barrel so that a coolant crown can also be generated with this system. The holes 52 can be aligned perpendicular to the rollers 1, 2 or also enable the cooling liquid to be sprayed obliquely against the rollers 1, 2.

In a special variant, not shown, it is provided that the cooling shells are designed in such a way that the coolant outlet opening is made simultaneously through a rectangular slot 24 or 44 combined with holes 52 in the plate in order to increase turbulence in the flow gap.

• Fig. 10a eine symmetrische Anordnung des unteren Teils des Kühlbalkens 54 auf der Kühlschale 11, 12 mit austauschbarer Düse 27,
• Fig. 10b Kühlflüssigkeitsaustritt aus der Düse 27 mit Winkel α schräg zur Walze,
• Fig. 10c Düse 27 mit alternativer Querschnittsform sowie mögliche Ausführungsformen der Stege bzw. Rillen 9,
• Fig. 10d asymmetrisch zur Düse 27 verkürzte bzw. verlängerte Kühlschale 11, 12.

Further details on the nozzle and shell design can be found in the Figures 10a to 10f can be seen, the arrangement of the nozzle in the middle of the shell or alternatively in a symmetrical arrangement with a shell that is shortened on one side, for example at the top. By changing the angle of incidence of the nozzle or different cooling shell thicknesses above / below (not shown), the distribution of the cooling liquid flow upwards and downwards can also be influenced. Different nozzle shapes (focusing or "atomizing" jet) are also indicated. The cooling shell can additionally be smooth or provided with grooves or webs 9 on the side facing the rollers in order to positively influence the cooling effect by causing turbulence. The following are shown in detail:

• Figure 10a a symmetrical arrangement of the lower part of the cooling bar 54 on the cooling shell 11, 12 with exchangeable nozzle 27,
• Figure 10b Cooling liquid exit from the nozzle 27 at an angle α obliquely to the roller,
• Figure 10c Nozzle 27 with an alternative cross-sectional shape and possible embodiments of the webs or grooves 9,
• Fig. 10d Cooling shell 11, 12 that is shortened or lengthened asymmetrically to the nozzle 27.

The funnel-shaped outlet opening shaped in the direction of flow can, if required, be designed with baffles in order to direct the coolant in a targeted manner inwards, outwards or straight ahead, so that ultimately a closed and even jet of cooling liquid emerges over the length of the cooling beam. A funnel-shaped design of the cooling liquid supply channel on the broad sides of the cooling beam is also possible in order to reduce the amount of cooling liquid flowing under the shell transversely to the side (beam edges).

Furthermore, it is possible to design the cooling shell in sections over the length of the cooling beam with a gap width adjustment in the cooling liquid supply channel and thus to influence the coolant distribution and the cooling effect over the length of the roller. In order to be able to carry out a parabolic change in the gap width of the outlet opening over the width in a simplified manner, according to the example of FIG Figures 10e (Side view) and 10f (top view) with an adjusting mechanism (not shown) bendable spring plates 53 are arranged within the funnel-shaped feed channel 55. In the normal position, the spring steel sheets are in contact with the side surfaces of the outlet opening. If the middle is adjusted on one side, the gap is reduced there. The edges are held in place in a slot guide. Alternatively, if the spring plate is positioned at the two edges, the gap width is reduced there.

The embodiment according to Figure 10e and Figure 10f represents only the principle. Other constructions with the same effect are also possible.

Details for an exemplary embodiment of the gap setting in the feed channel 55 are shown in FIGS Figures 11a to 11c in side view and in the Figure 12 shown in the corresponding top view. Here the elongated exit cross section 58 of the cooling bar is divided into individual width sections 59. For each width section 59, the flow opening b and thus the volume flow of the cooling liquid can be set individually. The width section 59 can be made, for example, 50-500 mm wide. Alternatively, the zone cooling can be controlled in pairs symmetrically to the center of the stand (gap setting). All cooling beams of a scaffolding can be provided with zone-wise control of the cooling cross-sections and the zones can be connected accordingly, or the individual beams of a scaffolding can be controlled separately. The closing mechanism for the outlet cross-section is shown in FIG Figure 11 an air or fluid pressure operated system is provided. Depending on the pressure level of the system or the measured volume flow, the flow opening b can be set from open to partially open or closed. Instead of section-wise arranged stretchable plastic tabs 60 can be used for segment-wise To influence the cross section of the outlet opening, rotatable or displaceable flaps or tappets, eccentric adjustments or other mechanical actuators can also be used.

In the embodiment of Figures 11a to 11c A pressure chamber 56 is arranged laterally on the feed channel 55 as a closure member, the expandable plastic tube 60 of which forms part of the feed channel 55. In the initial state of the Figure 11a the air chamber 56 is in the unpressurized state, so that, as in FIG Figure 12 shown on the width section 59a, the flow opening b is fully open. In the Figure 11b the pressure chamber 56 was partially filled with compressed air or a liquid via a pressure line 57, as a result of which the plastic hose 60 was partially pressed into the feed channel 55 and the flow opening b is now partially closed, as in FIG Figure 12 is shown at width portion 59b. A completely closed flow opening b shows Figure 12 at width section 59c. According to the Figure 11c the pressure chamber 56 is completely filled and thus the feed channel 55 is blocked in this area. By closing the zones, the thermal expansion of the roller and thus the strip profile and flatness can be positively influenced. Closing the cooling zones next to the belt with simultaneous adjustment (reduction) of the water flow rate can advantageously contribute to a further reduction in energy.

Another working principle of zone cooling is in Figure 13 shown. Here, narrow cooling shells 14 are arranged next to one another in the length of the roller, the gaps 31, 32, 33 of which can be set with different gap widths W1, W2, W3. By different gap widths and a different application of pressure and volume flow of the cooling liquid to the gaps 31, 32, 33, a different specific cooling liquid flow 41 per unit of time can be generated over the length of the roller. In order to separate the individual zones with different coolant flow rates 41 per unit of time, a barrier coolant generating a dynamic pressure can be introduced into the gap 34 existing between the cooling shells 14. In a simplified manner, a cooling shell can also be implemented without an adjusting device such that the gap between the cooling shell and the roller is of any size over the length of the roller.

A material can advantageously be used as the material for the cooling shells 13, 14 which may rest against the roller without damaging it and which is elastic. This can be, for example, a sand-free cast iron, lubricious plastic, self-lubricating metals, aluminum or hard fabric.

In the Figure 14 a way of sealing the gap 30 formed between the work roll 1 and the cooling shell 14 is shown at its edges. A fluid jet 28, for example air or coolant, is targeted into the via a pipe 25 and a nozzle 27 Blown opening of the gap 30. The fluid jet 28 thus generates a dynamic pressure which prevents the cooling liquid 7 from escaping from the gap 30.

A locally acting axially adjustable work roll spray cooling, which can be designed as high pressure but also as low pressure cooling, show Figures 15a and 15b . This cooling represents an additional cooling and can be operated in combination with the low-pressure shell cooling (not shown). The local positioning of the spray nozzles or application of the cooling liquid 7 is preferably carried out as a function of the profile and flatness control or regulation. In Figure 15a For this purpose, the spray nozzle bar sections 40 ′ are moved on a guide rod 63. The two spray nozzle bar sections 40 'are positioned symmetrically to the roll center with the aid of a hydraulic cylinder 61, articulated rods 62 and nozzle bar support 64. Alternatively, two hydraulic cylinders 61 are also conceivable, which position both sides 65 individually. The spray nozzle bar sections 40 'are fed individually on the right and left via the respective feed line 25. A similar arrangement of locally acting work roll cooling is provided Figure 15b A hydraulic cylinder 61 is used here to move articulated rods and articulated rockers 62 with spray nozzle bar sections 40 'attached to them over a pivot point 66 on a circular path 64, thus directing the cooling jet 7 to different positions within or next to the strip area on the work roll 1. As an alternative to the articulated swing arm, not shown, the two spray nozzle bar sections 40 'can each be moved with a coupling gear (4-joint arch) if movement on a circular path 64 is to be avoided. The use of electric or hydraulic stepper motors at the positions of the pivot points 66 for direct movement of the nozzle units on the spray nozzle bar sections 40 'via a rod on the circular path 64 is also possible.

The low-pressure cooling system can also be used alone, i.e. not in combination with the high-pressure cooling system.

Fig. 16 shows spiral springs 8 as an elastic connection between the adjacent cooling shell segments 13.

List of reference symbols

• 1, 2 work roll
• 3 roller width
• 4 rolling stock
• 5 Direction of roll rotation
• 6 roller surface
• 7 coolant
• 8 spring
• 9 grooves or ridges
• 10 cooling device
• 11 connected cooling bowl
• 12 radially divided cooling shells
• 13 cooling shell segments
• 14 narrow cooling trays
• 15 Articulation point of the cooling shell
• 16 cooling beam supports
• 17 scrapers
• 18 Roll gap cooling
• 19 Roll gap lubrication
• 20 cylinders
• 21 pivot point of the cylinder
• 22 Joint pivot point of the cooling shell segments
• 23 Articulation point of the cooling beam support
• 24 outlet opening
• 25 feed tube
• 26 discharge pipe
• 27 nozzle
• 28 fluid jet
• 29 Entrance opening
• 30 Gap between roller surface and cooling shell
• 31 gap with gap width W1
• 32 gap with gap width W2
• 33 Gap with gap width W3
• 34 Gap between the narrow cooling shells
• 36 pressure gauges
• 37 Sensor for distance measurement
• 38 temperature sensor
• 39 odometer
• 40 spray nozzle bars for high pressure cooling
• 40 'spray nozzle bar section
• 41 specific coolant flow rate per unit of time
• 42 Sealing coolant for separating the cooling shell strips
• 43 Direction of flow of the coolant
• 44 funnel-shaped dispensing slot
• 45 possible directions of adjustment of the cooling beam support
• 46 contact surface
• 47 replaceable cooling plate
• 48 crossbars
• 49 spacer plate
• 50 cooling bowl with elastic plastic surface
• 51 Cooling bowl with elastic plastic plate
• 52 cooling bowl with holes
• 53 spring plate
• 54 lower part of the cooling beam
• 55 funnel-shaped feed channel
• 56 pressure chamber
• 57 Pressure line
• 58 outlet cross-section
• 59 Width section of the outlet cross-section
• 60 stretchable plastic tubing
• 61 cylinders
• 62 articulated rods
• 63 guide rod
• 64 trajectory
• 65 movable nozzle beam support
• 66 pivot point
• b flow opening
• LP coolant supply low pressure cooling
• HP coolant supply high pressure cooling
• s1-s3 cooling area of the cooling shell segments

Claims (19)

1. Method of cooling the rolls (1, 2) of a roll stand with low-pressure cooling, in which the rolls are acted on by a cooling liquid standing under low pressure, characterised in that the rolls are also subjected to a high-pressure cooling simultaneously with the low-pressure cooling, wherein the rolls during the high-pressure cooling are directly sprayed with a cooling liquid standing under high pressure; and for the high-pressure cooling a single-row or multi-row spray nozzle bar (40, 40') with nozzles for high-pressure cooling of the rolls is used, which acts over almost the entire roll width or is configured to be movable in width direction and with a local cooling action.
2. Method according to claim 1, characterised in that approximately 20% of the entire cooling liquid quantity of the high-pressure cooling and approximately 80% of the entire cooling liquid quantity of the low-pressure cooling producing the main cooling effect are supplied.
3. Method according to one of the preceding claims, characterised in that for preference a pressure range for the cooling liquid (7) between 0.5 to < 5 bars for the low-pressure roll cooling and a pressure range for the cooling liquid (7) between 5 - 50 bars, preferably 12 bars, for the high-pressure roll cooling are set with the help of a process model in dependence on the rolling parameters of thickness reduction, specific area pressure in the rolling gap, rolling speed, strip temperature, roll material and rolled material.
4. Method according to any one of the preceding claims, characterised in that the low-pressure cooling is formed as a low-pressure spray cooling, as a low-pressure cooling curtain or as low-pressure flow cooling, as low-pressure cooling of high turbulence or in the form of a combination of the said forms of cooling, wherein in the case of low-pressure flow cooling the cooling liquid flows in a gap (30, 31, 32, 33) between the roll surface and at least one cooling shell segment opposite a partial region of the roll surface.
5. Method according to claim 4, characterised in that adaptation of the position of the cooling shell segment (13) to the respective roll diameter and/or roll positions is undertaken for producing a reproducible cooling effect.
6. Method according to one of the preceding claims 4 and 5, characterised in that by way of the cooling shells (13) predominantly a coolant flow (43) tangentially along the roll surface (1, 2) is produced or, with the help of spacer plates or spacer strips (49) sealed in tangential direction, a coolant flow or coolant outflow preferably to the side is optionally performed in order to heat the roll region at the edges by warm cooling liquid (7) apart from the strip region in the middle.
7. Method according to claim 6, characterised in that in the case of a coolant outflow conducted preferably parallel to the roll axis the coolant feed near the strip region is blocked by the features of the zonal cooling, for example the cooling shell spacing from the roll (1, 2) or from the coolant feed channel (55).
8. Method according to any one of the preceding claims, characterised in that the cooling intensity of the low-pressure cooling, particularly in the case of the low-pressure cooling curtain or the flow cooling, is set to be different over the roll length.
9. Method according to any one of the preceding claims, characterised in that the nozzle spray bars, which are optionally movable in width direction, of the high-pressure cooling system are utilised for zonal cooling and are constructed axially, with the help of electric or hydraulic motors with threaded rods or by hydraulically moved single-element or multi-element articulated transmissions (62) with a spray nozzle bar section (40') attached thereto or rotatable nozzle units, in order to guide the cooling liquid (7) with a directed jet onto the desired region of the roll (1, 2).
10. Method according to any one of the preceding claims, characterised in that a computer model, for example a process model or Level 1 model, is used, which fulfils the following tasks:

    setting of the coolant quantity and pressure level for the low-pressure and high-pressure part in dependence on strip thickness reduction, specific area pressure in the rolling gap, rolling speed, strip temperatures, roll material and rolled material as well as the measured and/or calculated roll temperatures and/or observed roll surface and equally in dependence on the set width of coolant action,

    setting of the coolant quantity over the strip width by adjustment of the outlet openings of the feed channel (parabolic, other curves or zonally) and/or adjustment of the gap width between cooling shell and roll in dependence on the strip width and/or setting of the position of the spray nozzle bar sections, which are adjustable in width direction, and/or measured profile state and planarity state over the strip width,

    exchange of signals with the thickness regulating means,

    description of the geometric correlationships of the movable parts of the cooling device as well as consideration of the adjustment position, pass-line position and roll diameter for the purpose of optimal positional determination or calculation of the position changes, and

    determination of the pivot position of cooling bar carriers as well as cooling shell adjustment position with the help of the cylinders optionally with use of pressure and travel transmitter signals.
11. Cooling device (10) for cooling the rolls (1, 2) of a roll stand with a low-pressure cooling system, in which the rolls are acted on by a liquid standing under low pressure, characterised in that in addition to the low-pressure cooling system a high-pressure cooling system is also provided, which is equipped with spray pipes and nozzles for direct spraying of the rolls with the cooling liquid, which is disposed under high pressure, simultaneously with the low-pressure cooling by the low-pressure cooling system and comprises a single-row or multi-row spray nozzle bar (40, 40') with the nozzles for high-pressure cooling of the rolls, and which acts over almost the entire roll width or is configured to be movable in width direction and with a local cooling action.
12. Cooling device according to claim 11, characterised in that the low-pressure cooling system is constructed for producing a low-pressure spray cooling, a low-pressure cooling curtain or a low-pressure flow cooling or a low-pressure cooling with high turbulence or a combination of the said types of cooling.
13. Cooling device according to claim 12, characterised in that the low-pressure cooling system for producing the low-pressure flow cooling comprises at least one cooling shell (11) with at least one, preferably curved cooling shell segment (13, 52), which together with the surface of the roll (1, 2) to be cooled forms a gap (20), which is fillable with the flowing cooling liquid (7) and which is preferably settable with respect to its gap width in the form of the spacing between the roll surface the cooling shell.
14. Cooling device according to any one of claims 11 to 13, characterised in that in the case of the combined low-pressure/high-pressure cooling system the spray nozzle bars (40, 40') of the high-pressure cooling system are arranged above and/or below and/or within the low-pressure cooling system to be fixed in location or to be movable in width direction.
15. Cooling device according to any one of claims 11 to 14, characterised in that two or more of the cooling shell segments are movably connected together.
16. Cooling device according to any one of claims 11 to 15, characterised in that the movable connection between the cooling shell segments is executed in the form of a universal joint and/or a spring and/or a resilient connection and/or a multi-element articulated transmission arrangement.
17. Cooling device (10) according to one of more of claims 14 to 16, characterised in that at least one of the cooling shell segments (13, 52), for example the middle one, is positionable by the cooling bar carrier (16) in front of the roll (1, 2) and the other cooling shell segments (13, 52) spaced by spacer plates (49) can be urged by way of springs (8) towards the roll (1, 2).
18. Cooling device (10) according to one or more of claims 11 to 17, characterised in that a space, from which a small amount of cooling liquid (7) passes into the environment, is formed between the cooling shells (11, 12) or the cooling shell segments (13) and the roll surfaces (1, 2) with the help of a sealing function or a sealing means by a predetermined pressure towards the rolls (1, 2).
19. Cooling device (10) according to any one of claims 11 to 18, characterised in that the high-pressure cooling system is arranged on the stand outlet side.

Images