EP2794137A1 - Cleaning device and method for removing a lubricant from the rolls of a roll stand - Google Patents

Abstract

The invention relates to a cleaning device (16) and a method for removing a lubricant from the rolls (4) of a roll stand (2). To achieve economical and efficient cleaning of the rolls (4), the cleaning device (16) comprises at least one ultrasonic generator (18) for generating ultrasonic waves, said ultrasonic waves being routed to the surface of the rolls (4) by means of cleaning water. The cleaning device also comprises a supply line (26) for the cleaning water, wherein said supply line (26) is a branch of a cooling water circuit for the roll stand (2). In particular, this enables the water consumption for the roll stand to be kept constant during the cleaning phase; the water is merely redistributed in that a portion of the cooling water is supplied to the cleaning device. This creates the advantage of the roll temperature rising slightly, with the result that the cleaning performance is supported by the higher roll temperature at which the lubricant is better released from the surface of the roll.

Description

description

Cleaning device and method for removing a

Lubricant from the rolls of a rolling stand

The invention relates to a cleaning device and a method for removing a lubricant from the rolls of a roll stand. Roll stands, especially in hot strip mills, typically include nip lubrication equipment, usually mounted to the upstream side of the mill in the area of the work roll. A lubricant is applied to the Ar ^¬ beitswalze, wherein as lubricant usually a water-oil emulsion is sprayed. The lubricant redu ^¬ decorates the coefficient of friction between each roll and the rolling significantly. This reduces the rolling forces and the surface quality of the rolling stock is improved. As a result, few rolling steps are required and / or the profile and the flatness of the rolling stock can be better influenced by a greater degree of freedom in the rolling force. In addition, energy consumption is reduced and the production spectrum increased. Before the tapping of the rolling stock, which for example a

Rolled strip, the rollers, in particular the Arbeitswal ^¬ zen must, however, be free of lubricant to increase of friction ^¬ coefficient of the roll, otherwise there is a risk that the rolling stock is not fed into the rolling stand, which of an interruption Rolling process leads. For this reason, the roll gap lubrication is switched off just before unloading the rolling stock, thereby burns the lubricant due to the high belt temperature completely in the remaining Walzenumläufen. Only after renewed threading of the next rolling stock, the roll gap lubrication is switched on again. The head and foot of the rolling stock are rolled without lubrication. This, however, adversely affects the Rolling, since the foot of the rolling stock, which is usually the coldest, requires the highest rolling force.

From the published patent application JP 2002-178011-A it is known to remove the lubricant from the roller in a targeted manner after the previous rolled strip has been threaded out by spraying hot water under pressure. The required water pressure is, depending on the temperature of the water, between 3 MPa and 15 MPa. The water temperature is at least 50 ° C. The disadvantage here is that the generation of pressure and the heating of the water in order to achieve a good efficiency, however, are very energy-consuming.

From WO 2006/089730 Al a method for cleaning a metal strip is also known, in which the metal strip is subjected to ultrasonic cleaning, in which the metal strip is passed through a container filled with a liquid. The invention has for its object to increase the efficiency in the cleaning of the rolls of the mill stand, without increasing the water consumption for cooling the rollers during operation of a roll stand substantially. The object is solved by a cleaning ^¬ constriction device of a lubricant from the rollers of a rolling mill for removing, wherein the cleaning device comprises at least one ultrasonic generator for generating ultrasonic waves, the ultrasonic waves by means of cleaning water to the surface of the rollers be conducted, wherein the cleaning device comprises a The supply line for the cleaning water comprises, wherein the supply line is a branch of a cooling water circuit for the rolling stand. The object is also achieved according to the invention by a Ver ^¬ drive for removing a lubricant from the rolls of a rolling stand, wherein the cleaning water to the surface of the rolls and is conveyed by means of the ultrasonic cleaning water waves are directed to the surface of the rollers, wherein the cleaning water is diverted from a cooling water circuit for the rolling stand. The advantages and preferred embodiments listed below in connection with the cleaning device can be applied analogously to the method.

The invention is based on the finding that the pressure of the cleaning liquid can be reduced, but still there is an intensive surface cleaning with a high efficiency by the cleaning is supplemented by ultrasonic waves, which propagate with the cleaning liquid to the surface of the roller and increase the cleaning effect , Ultrasound is known to work even in small wells of the surface and mechanically bring adhering particles or substances into solution. Thanks to the ultrasonic waves, the risk of damage to the surface of the roller is minimized. In addition, notches on the surface of the roller, such as fire cracks, can be cleaned efficiently. The cleaning liquid is applied in particular to the roll surface at a pressure of 5 to 15 bar, wherein the pressure is about ten times lower than the required pressure according to JP 2002-178011-A. The at least one ultrasonic generator is integrated in particular in the cleaning ^¬ device, and type of the cleaning liquid to ^¬ so that the ultrasonic waves are supplied directly to the cleaning liquid and with this weiterge ^¬ passes. The result is a fluid bridge between the ultrasonic generator and the roller surface, which transmits the sound waves. This type of cleaning can be applied to both the work rolls and the back-up rolls of a rolling stand. Conveniently, water is as a cleaning agent USAGE ^¬ det. Since water is chemically neutral, the use of water is gentle on the rollers. In addition, water is anyway a wide application in the rolling process, so that in a rolling mill large amounts of water are available.

The main advantage of such a cleaning is that the lubrication can be used for the whole band foot and for the essential part of the band head. This reduces the rolling force, resulting in a significant energy saving effect. In addition, the product range is broadened: with an identical design of the system (drives, hydraulics and stands), harder steel products can be rolled.

A particularly good synergistic effect, which increases the efficiency of the cleaning, is achieved by the cleaning water is diverted from the cooling water circuit for the mill, wherein the water is supplied via a supply line of the cleaning device and this supply line is a Abzwei ^¬ tion of the cooling water circuit for the roller. In particular, during the cleaning phase, the water consumption for the roll stand can be kept constant, it is merely a redistribution of the water by a part of the

Cooling water is supplied to the cleaning device. This has the advantage that the rolling temperature rises slightly to ^¬ so that the cleaning performance is supported by the higher Wal ^¬ zentemperatur at which the lubricant better detached from the roll surface.

Preferably, the ultrasonic generator for generating

Ultrasonic waves with a frequency between 20 kHz and

2 MHz, in particular between 35 kHz and 200 kHz. This frequency range has proved to be particularly advantageous for the ultrasonic cleaning of fine dirt. Conveniently, at least two ultrasonic generators of different frequency are provided, e.g. an ultrasonic generator with 40 kHz and an ultrasonic generator with 80 kHz frequency.

According to a preferred variant, a sealing element is provided, which faces a nip between the rollers is, so that the sealing ^element seals the roller against a forth ^¬ outflowing liquid in the direction of rotation of the roller. With the help of the sealing element prevents the cleaning water flows due to the rotational movement of the roller to the rolling stock, while the rolling stock is unnecessarily cooled.

In order to enable a propagation of the cleaning water against the direction of rotation of the roller, an opening facing the nip ^{¬ is} provided on the cleaning device, through which the cleaning water is conveyed to the surface of the roller. Through the exit of cleaning water ge ^¬ gene, the rotational direction of the roll that is not removed from the roll surface lubricant dissolved in rotation Rich ^¬ processing of the roll and is not in contact with the rolling stock is ensured.

Preferably, the cleaning device is arranged at least on the inlet side of the respective roller. In a rever ^¬ sible rolling stand cleaning devices can also be provided on the outlet side. Since the cleaning device is characterized by a manageable number of additional components, it requires a small installation space and can be easily installed in a protected installation position in existing components of the mill stand. In this case, the cleaning device is integrated in particular in a chock of the work rolls or in a chilled beam for the rolling stand. With regard to a particularly effective surface cleaning, at least one cleaning device arranged on the inlet side is provided per roll; in the case of reversibly operated rolling stands, two cleaning devices per roll make sense - one inlet and one outlet side.

According to a further preferred embodiment, the cleaning water contains an emulsifier. With the aid of the emulsifier, the cleaning performance is increased, since lubricant particles which are thrown up during the cleaning process do not settle again so easily on the roll surface can. In particular, the same emulsifier is used, which is admixed with the lubricant. In this way, it is ensured that no additional resources must be made available, but the cleaning of the roll surface is carried out only with the help of Betriebsmit ^¬ stuffs, which are anyway required and approved for the operation of the mill stand.

Conveniently, the temperature of the cleaning water is between 0 ° C and 70 ° C. In particular, the temperature of the cleaning water corresponds to an ambient temperature, so that no additional heating effort for the Reinigungswas ^¬ water is required, or such a heating effort is limited.

In order to keep the cleaning time as short as possible, the Rei ^¬ nigungsvorrichtung is preferably only between a tapping of a preceding material to be rolled by the rolling mill and a ^¬ An engraving of a subsequent material to be rolled running. Thus, only the portion of the roll is cleaned, comes into contact with the head of nachfol ^¬ constricting rolling stock. If the subsequent rolling ^¬ tape is already fed in the nip, the cleaning process ^¬ supply is interrupted and resumed normal operation of the rolling stand. However, especially with longer breaks between two rolling belts, it may happen that the cleaning of the roll surface does not start with the tapping or that it is not thoroughly cleaned to the piercing point.

An embodiment of the invention will be described with reference to a

Drawing explained in more detail. Herein schematically and greatly simplified show:

1 shows a section through a roll stand with an ^ultrasonic cleaning of the work rolls,

2 shows a cross section through a cleaning device for an upper work roll of the roll stand according to FIG. 1, FIG. 3 shows a longitudinal section through the cleaning device according to FIG. 2, FIG.

4 shows a coolant circuit and a lubricant circuit of a roller.

The same reference numerals have the same meaning in the various figures. In Fig. 1, a rolling stand 2 is shown, which comprises two working ^¬ rollers 4 and two support rollers 6. Between the work rolls, a roll gap 8 is formed, through which rolled goods, run in the embodiment shown rolling belts. In Fig. 1, a preceding, already rolled rolled strip 10 is shown with a reduced thickness, the foot part is still in the nip 8, and a subsequent, prepared for rolling rolled strip 12th

To reduce the coefficient of friction between the respective rolled strip 10, 12 and the work rolls 4, a lubricant is supplied to the work rolls 4 through lubricant nozzles 14. Before tapping the subsequent rolled strip 12, however, the nip 8 must be lubricant-free, so that the rolling ^¬ band 12 can be easily fed into the rolling stand 2. To this end, each is provided a Reinigungsvor ^¬ device 16 for each drive roller 4 with the aid of a Reinigungsflüs ^¬ sigkeit, in the embodiment shown, water is applied to the surfaces of the working rolls. 4 The cleaning water is only applied to a part of the surface. By rotating the work rolls 4, however, the effective range of the cleaning water shifts around the circumference of the respective work roll 4, so that ultimately the entire surface area of the work rolls 4 is exposed to the cleaning water. In the cleaning device 16, an ultrasonic generator 18 is integrated, are generated with the aid of ultra ^¬ sound waves, which are passed by means of water from the cleaning device 16 to the surface of the work rolls. 4 The respective cleaning device 16 is in the embodiment 16 shown installed in the cooling circuit of Ar ^¬ beitswalzen 4 and attached to a einlaufseifigen fender 20. The function of the mudguard 20 is to prevent cooling water from reaching the rolled strip 10, 12.

The coolant circuit has per work roll on the inlet and outlet side a coolant supply 22, which opens into a chilled beam 24, which extends substantially over the length of the work rolls perpendicular to the plane of the drawing. From the coolant supply 22, a feed line 26 is also branched off on the inlet side, through which water is introduced into the cleaning device 16.

The construction of the cleaning device 16 can be seen in FIGS. 2 and 3. The cleaning device 16 has a

Cavity 28, which is filled in operation with water. In the cavity 28, the ultrasonic generator 18 is arranged, so that the ultrasonic generator 18 is in particular continuously washed by the water during operation, which is conveyed in the direction of the roll zen surface. At a side facing the nip 8 side 30 of the cleaning device 16 is a sealing element 32, which is in the manner of a sealing lip ^¬ forms, arranged. In particular, by its contact with the roll surface, the sealing element prevents water from the cleaning device 16 during the rotational movement of the work roll 4 down to the rolled strip 10, 12, flows. Only at a side facing away from the nip 8 side 34 of the cleaning device 16, an opening 36 is formed through which the water is passed from the cleaning device 16 in the opposite direction to the direction of rotation of the work roll 4 to the roll surface. When the lower roller 4 (see Fig. 1) shows the opening 36 downwards, so as to ^¬ additionally affects the force of gravity and increases the discharge of the cleaning water supply ^¬. As an alternative or in addition to the openings 36 facing away from the roll gap 8, openings which are not shown here in detail can also be provided in the region of the front sides of the work rolls 4. In this case, the side The drain of the cleaning water, for example, is collected via lines or baffles and can be recirculated.

As can be seen from FIG. 3, baffles 38 are optionally provided in the cleaning device 16, which effect a uniform flow through the cavity 38, so that the formation of dead zones in the cavity 28 is suppressed.

The water transmits the sound waves from the ultrasonic generator 18 to the rolling surface and thus forms a kind of flues ^¬ sigkeitsbrücke between the ultrasonic generator 18 and the work roll 4. The lubricant on the roll surface is sputtered and removed from the water via the ultrasonic waves in the water. Which is set einge- as cleaning water, the water is conveyed with a pressure of about 10 bar to the working ^¬ roller 4 and in particular has a temperature that corresponds to the resultant of the process control and / or the tool state temperature. Thus, in particular, no further heating measures for the removal of

Lubricant required by the roll surface.

The fluidic connection between the cleaning ^¬ device 16, the cooling water circuit and a lubricant circuit of the roll stand 2 is shown in Fig. 4. Reference numeral 40 denotes a lubricant tank in FIG. 4 and an emulsifier tank 42. The lubricant, the emulsifier and water from a water supply line 48 for scaffolding cooling are brought together in a mixer 44 and via a lubricant line 46 of the lubricant nozzle 14, which is arranged in the Ausführungsbei ^¬ game below the mudguard 20 in the vicinity of the rolling gap ^¬ 8 in the shown Ausführungsbei ^¬ , fed.

Cooling water is introduced from the water supply line 48 into the cooling water line 22, which is sprayed onto the surface of the work roll 4 via the cooling bars 24. A portion of the cooling water is umgelei ^¬ tet via the supply line 26 before it has reached the chilled beam 24. The cooling water Ström is in a ratio to the cleaning stream between 10: 1 to 2: 1. The portion of water in the Zufuhrlei ^¬ tung 26 is mixed in a second mixer 50 with the emulsifier from the Emulgatortank 42 and then introduced into the cleaning device sixteenth For this purpose, an emulsifier line 52 leads directly from the emulsifier tank 42 to the second mixer 50, which likewise is arranged on the protective plate 20 like the cleaning device 16. The emulsifier increases the efficiency of the cleaning water. The supply line 26 also opens into the second mixer 50.

The cooling water and the cleaning water, which runs off the side of the work rolls 4, is finally collected in a cooling water sump 54 and discharged from the rolling stand 2 for processing.

Is characteristic of the cooling water circuit shown in FIG. 4 that the Wasserzufüh ^¬ tion can be controlled in the lines 22 and 26 in dependence on the Walzvor- gear effort and in a short time by means of the valves 56a and 56b. For example, the water supply to the cleaning device 16 is interrupted during the rolling of the preceding roll ^¬ belt 10, so that the total amount of water used in the Kühlwas ^¬ water pipe 22 for cooling purposes. The cleaning device 16 is only briefly turned on between a tapping of the preceding rolled strip 10 and a tapping of nachfol ^¬ constricting rolled strip 12th For this purpose, part of the water in the cooling water line 22 is diverted into the supply line 26 and finally reaches the cleaning device 16. In particular, as long as the cleaning device 16 is active, at least from the inlet-soapy Kühlbal ^¬ ken 24 less water to the roll surface. However, this has the positive side effect that the lubricant is easier to solve by heating the roll surface.

Overall, both during the rolling of the rolled strip 10 and between the tapping and the subsequent tapping of the new roll strip 12 despite cleaning the Walzenoberfläz the same amount of cooling water is used with cooling water. The roll stand 2 is thus characterized not only by an efficient operation thanks to the increase in the coefficient of friction during the start of the rolling belts 10, 12, but also by a minimized energy requirement and by a potentially constant water requirement.

Claims

claims A cleaning device (16) for removing a lubricant from the rolls (4) of a rolling stand (2), comprising at least one ultrasonic generator (18) for generating ultrasonic waves, wherein the ultrasonic waves with the aid of cleaning water to the surface of the rollers (4) are conductive , and a supply line (26) for the cleaning water, wherein the supply line (26) is a branch of a cooling water circuit for the rolling mill (2). 2. Cleaning device (16) according to claim 1, wherein the ultrasonic generator for generating ultrasonic waves having a frequency between 20 kHz and 2 MHz, in particular between 35-200 kHz, is formed. 3. Cleaning device (16) according to one of the preceding claims, comprising a sealing element (32) facing a roll gap (8) between the rolls (4) and sealing at least one roll (4). 4. Cleaning device (16) according to one of the preceding claims, wherein a roller gap (8) between the rollers (4) abge ^¬ facing opening (36) is provided for the cleaning water. 5. Cleaning device (16) according to one of the preceding claims, which is angeord ^¬ net at least upstream of the respective roller (4). 6. Cleaning device (16) according to one of the preceding claims, wherein the cleaning water contains an emulsifier. 7. Cleaning device (16) according to one of the preceding claims, wherein the temperature of the cleaning water is between 0 ° C and 70 ° C. 8. Cleaning device (16) according to one of the preceding claims, which is active between a tapping and a subsequent tapping by means of the roll stand (2). 9. A method of a lubricant for removal from the rollers (4) of a roll stand (2), wherein the cleaning water to the surface of the rollers (4) is conveyed and guided by means of the cleaning ^¬ supply water ultrasonic waves to the surface of the rollers (4), wherein the cleaning water is diverted from a cooling water circuit for the rolling stand (2). 10. The method according to claim 9, wherein a frequency of the ultrasonic waves between 20 kHz and 2 MHz, in particular between 35-200 kHz, is set. 11. The method according to claim 9 or 10, wherein at least one roller (4) is sealed by means of a sealing element (32) against outflow of the cleaning water in the direction of rotation of the roller (4). 12. The method according to any one of claims 9 to 11, wherein the cleaning water is conveyed to the surface of the corresponding roller (4) through an opening of the cleaning device (16) facing away from a roller gap (8) between the rollers (4). 13. The method according to any one of claims 9 to 12, wherein the respective roll (4) at least on the inlet side gerei ^¬ nigt. 14. The method according to any one of claims 9 to 13, wherein an emulsifier is added to the cleaning water. 15. The method according to any one of claims 9 to 14, wherein the temperature of the cleaning water between 0 ° C and 70 ° C is set. 16. The method according to any one of claims 9 to 15, wherein the cleaning device (16) is activated between a tapping and a subsequent tapping by means of the roll stand (2).