Cleaning device and method for the electrolytic treatment of a metal strip

Abstract

The invention relates to a cleaning device (1) for the electrolytic treatment of a metal strip (B) in a cleaning section (2) of the cleaning device (1), which has a first spray nozzle (10), a second spray nozzle (20), a power supply device (30), and an electrolyte supply device (40) for supplying the first spray nozzle (10) and the second spray nozzle (20) with an electrolytic liquid (3), wherein the cleaning section (2) is arranged between the first spray nozzle (10) and the second spray nozzle (20), wherein the first spray nozzle (10) is configured to apply a first electrolyte jet (11) within the cleaning section (2) to a first surface (4) of the metal strip (B), and the second spray nozzle (20) is configured toto apply a second electrolyte jet (21) within the cleaning section (2) to a second surface (5) of the metal strip (B) opposite the first surface (4). The power supply device (30) is configured to apply an electrical voltage between the first jet nozzle (10) and the second jet nozzle (20), and the first jet nozzle (10) and the second jet nozzle (20) are each configured to apply an electrical voltage to the electrolytic liquid (3) contained therein. The cleaning device (1) is configured tothat during the application of the electrolytic fluid (3) to the metal strip (B), an electric current flows either from the first spray nozzle (10) along the first electrolyte jet (11) and the second electrolyte jet (21) through the metal strip (B) to the second spray nozzle (20), or from the second spray nozzle (20) along the second electrolyte jet (21) and the first electrolyte jet (11) through the metal strip (B) to the first spray nozzle (10).

Description

The invention relates to a cleaning device for the electrolytic treatment of a metal strip. The invention further relates to a method for the electrolytic treatment of a metal strip. The electrolytic treatment, particularly electrolytic cleaning, of metal strips, especially in steel production, is an essential process step primarily used to improve surface quality and achieve specific functional properties. It is frequently performed after rolling to prepare the surface of the treated metal strip for further processing steps such as coating or finishing. Various electrolytic processes are used, such as electrolytic degreasing or electrolytic pickling. In steel production, electrolytic degreasing is used to remove oils, greases, and other contaminants from the surface of the metal strip. This is particularly important before processes such as galvanizing or painting, as a clean surface is necessary for good adhesion. Electrolytic pickling is used to remove oxides from the surface of the metal strip that formed during rolling or annealing. This is a critical process for obtaining a metallically clean surface, which is necessary for subsequent treatments such as zinc plating or painting. Current state-of-the-art technology typically employs immersion baths that enable combined chemical and electrolytic cleaning. In this process, the metal strip is drawn through a bath containing a special cleaning solution that dissolves oils, greases, and other contaminants from the strip's surface. This process is enhanced by the application of an electric current, which triggers an electrolytic reaction in the bath and increases cleaning efficiency. Electrodes are positioned in an immersion bath, and a direct current voltage is applied between them. The metal strip acts as an electrical conductor between the cathode and anode, depending on the process design. The electrolytic reaction releases gases (usually hydrogen and oxygen) at the strip's surface, which mechanically detach or decompose the impurities. An exemplary cleaning device and an exemplary cleaning method for the electrolytic treatment of metal strips are shown in EP 3 514 263. The electrical voltage is introduced into the metal strip by means of a current roller. However, the use of current rollers in the electrolytic treatment of metal strips causes several problems. The mechanical contact leads to high wear and uneven current transmission, which promotes local overheating and surface defects on the strip. In addition, impurities reduce the efficiency of the current transmission, while uneven current distribution and mechanical stress impair the strip quality. This leads to the problem underlying the invention: cleaning the metal strip with known devices results in high wear of the electrodes and mechanically moving parts, and moreover, impairs the quality of the metal strip surface. Furthermore, this process requires a great deal of electrical energy. The present invention is therefore based on the objective of providing a device for the electrolytic treatment, in particular for the electrolytic cleaning, of metal strips, which enables particularly low-wear cleaning of the metal strips without impairing the strip quality and with lower energy consumption. The problem underlying the invention is solved by a device having the features of claim 1 of the present invention. Advantageous embodiments are described in the dependent claims. More precisely, the problem underlying the invention is solved by a cleaning device for the electrolytic treatment, in particular cleaning, of a metal strip in at least one cleaning section of the cleaning device. The cleaning device comprises at least one first spray nozzle, at least one second spray nozzle, a power supply device, and an electrolyte supply device for supplying the at least one first spray nozzle and the at least one second spray nozzle with an electrolytic liquid.In the cleaning device, the at least one cleaning section is arranged between the at least one first spray nozzle and the at least one second spray nozzle, wherein the at least one first spray nozzle is configured to apply a first electrolyte jet within the cleaning section to a first surface of the metal strip, and wherein the at least one second spray nozzle is configured to apply a second electrolyte jet within the at least one cleaning section to a second surface of the metal strip opposite the first surface.The power supply device is configured to apply an electrical voltage between the at least one first spray nozzle and the at least one second spray nozzle, wherein the at least one first spray nozzle and the at least one second spray nozzle are each configured to apply an electrical voltage to the electrolytic fluid contained therein. The cleaning device is configured such that, during the application of the electrolytic fluid to the metal strip, an electric current flows either from the first spray nozzle through the first electrolyte jet and the second electrolyte jet through the metal strip to the second spray nozzle, or from the second spray nozzle through the second electrolyte jet and the first electrolyte jet through the metal strip to the first spray nozzle. In this way, a cleaning device is provided in which, during cleaning operation, the current required for electrolytic cleaning is introduced into the metal strip by means of the electrolyte jet, instead of by means of a mechanically moved current roller that establishes frictional contact, as is usual in the prior art. This prevents mechanical damage to the surface of the metal strip, resulting in an increase in the surface quality of the metal strip being cleaned. Another advantage is that the current-conducting path through the metal strip can be significantly reduced in this way, resulting in advantages with regard to electrode wear and energy consumption of the electrolytic treatment carried out by means of the cleaning device according to the invention. An electrolytic treatment, especially cleaning of a metal strip, can be a method for removing contaminants from metal surfaces, in which electric current is used in an electrolytic fluid to promote chemical reactions that aid in the cleaning of the metal strip. The cleaning device is designed for the electrolytic treatment of a metal strip in a cleaning section of the cleaning device. The cleaning section can be a three-dimensional area within the cleaning device, wherein the cleaning device is designed such that, during the intended use of the cleaning device, a portion of a metal strip located within the cleaning section at that time is electrolytically treated and, in particular, cleaned. The cleaning section need not be completely delimited by a physical device. It can also be an imaginary, defined area within the cleaning device, where cleaning takes place during a cleaning process carried out by the device. Preferably, however, the cleaning section is at least partially delimited by the first and second spray nozzles. In particular, the cleaning device can be configured such that the metal strip is located between the first and second spray nozzles during the cleaning process. The cleaning device can preferably be set up for the electrolytic treatment of metal strips made of steel or stainless steel alloys or of non-ferrous metals, copper or aluminum alloys. The cleaning device can be configured such that the metal belt passes through the cleaning section at an angle of less than or equal to 30°, preferably less than 20°, and more preferably less than 10°, to the gravity vector during cleaning. In particular, the cleaning device can be configured so that the metal belt passes through the cleaning section parallel to the gravity vector. In this way, the electrolytic fluid applied to the metal strip can flow off by gravity, which has advantages in terms of energy efficiency and surface quality. A surge nozzle can be a nozzle for applying a fluid to a surface, which has a particularly high aspect ratio of the outlet opening and applies the fluid to be applied at low pressure. The power supply device is designed to supply the cleaning device, in particular the first and second spray nozzles, with electrical current. The power supply device can consist of one or more individual power supply modules. In particular, the power supply unit can have a separate power supply module for each of the first and second spray nozzles. This allows the cleaning device to be designed to be particularly energy-efficient. The power supply device is preferably a switch-mode rectifier. A switch-mode rectifier can be an electronic device that generates direct current (DC) from alternating current (AC) by using electronic switching elements to increase conversion efficiency. In this way, the cleaning device can be designed to be particularly energy-efficient. The power supply device can be configured to provide currents in the range of 0 A to 2500 A, preferably in the range of 0 A to 1000 A, preferably 30 A to 500 A, and more preferably 50 A to 300 A. The power supply device can be configured to provide a voltage in a voltage range of 0 V to 500 V, preferably 10 V to 300 V, and more preferably 30 V to 120 V. This allows for a particularly efficient and thorough cleaning of the metal strip, which offers advantages in terms of low wear, surface quality and energy efficiency. The power supply device can be configured to apply a DC voltage between the first and second spray nozzles. It is also possible, of course, for the power supply device to be configured to apply an AC voltage between the first and second spray nozzles. The cleaning device includes an electrolyte supply device. The electrolyte supply device may include at least one electrolyte tank, a fluid pump, an electrolyte treatment device for cleaning and treating the electrolyte fluid, and pipes and / or hoses for transporting the electrolyte fluid. The electrolyte supply system can be configured so that only the treated electrolyte fluid is ever directed to the spray nozzle and thus comes into contact with the belt during cleaning. This prevents any mixing of treated and contaminated electrolyte fluid. As a result, a higher level of dirt removal can be achieved, leading to improvements in surface quality. An electrolytic liquid can be a solution that contains dissolved ions and is able to conduct electric current. An electrolytic liquid can also be called an electrolyte. The electrolytic liquid used here can have an electrical conductivity between 1 mS / cm and 550 mS / cm, preferably between 5 mS / cm and 200 mS / cm, and more preferably between 60 mS / cm and 90 mS / cm. In this way, the electric current can be introduced into the metal strip particularly efficiently and evenly, resulting in advantages in terms of energy efficiency and surface quality. The cleaning device preferably has two spray nozzles. However, it is also conceivable that the cleaning device has more than two spray nozzles, for example three, five, seven, nine or more spray nozzles, in particular an even number of spray nozzles. The first and second spray nozzles can also be referred to as "the spray nozzles". If the cleaning device has more than two spray nozzles, all or a subgroup of the spray nozzles can be referred to collectively as "the spray nozzles". The spray nozzles can be arranged with their respective outlet openings at the same height. However, it is also conceivable that the spray nozzles are arranged in such a way that there is a height difference between the outlet openings. The first and / or the second spray nozzle may have a coating, particularly in their respective internal areas. The coating may preferably be designed to increase the conductivity of the first and / or the second spray nozzle at its surface. The first and second spray nozzles are each configured to apply a first electrolyte jet and a second electrolyte jet within the cleaning section to a first and a second surface of the metal strip, respectively. The first and second surfaces are located on opposite sides of the metal strip. An electrolyte jet can be a jet of an electrolytic liquid. The first and / or second spray nozzle can be arranged such that the exit vector of the respective electrolyte jet is perpendicular to the gravity vector. Alternatively, the first and / or second spray nozzle can be arranged such that an angle of attack is created between the exit vector of the respective electrolyte jet and the normal to the gravity vector, wherein the angle of attack lies in the range of -90° to +90°, preferably in the range of -45° to +45°, and more preferably in the range of -10° to +20° to the normal of the gravity vector. Furthermore, the first and second spray nozzles are configured to apply an electrical voltage to the electrolytic liquid contained therein. Preferably, this voltage is provided by the power supply device. In particular, the first and second spray nozzles are configured such that the first and second electrolyte jets, respectively, are subjected to a voltage, preferably the voltage provided by the power supply device. The first and second spray nozzles are therefore designed so that during the cleaning process, in particular during the application of electrolytic fluid to the metal strip by the first and second electrolyte jets respectively, a current flows from one of the spray nozzles through the metal strip to the other spray nozzle. This can mean that the first electrolyte jet and the second electrolyte jet are the electrical conductors for the flowing current. If the current flows through the metal strip, this can specifically mean that the current flows from the part of the first or second surface of the metal strip where the respective first or second electrolyte jet strikes the metal strip to the respective other part of the surface of the metal strip where the respective other electrolyte jet strikes the metal strip. The cleaning device can be configured to generate a current density in the range of 0 to 500 A / dm2, preferably 1 to 200 A / dm2, during the application of the first electrolyte jet and / or the second electrolyte jet. This increases the cleaning device's effectiveness, resulting in advantages in terms of wear resistance and surface quality. Furthermore, it can lead to improvements in energy efficiency. The cleaning device can also include a pair of squeegee rollers. Such a pair of squeegee rollers can be used to remove any electrolytic fluid remaining on the surface of the metal strip. This allows for higher strip speeds, thereby increasing the energy efficiency of the cleaning device. According to an advantageous embodiment of the invention, the cleaning device comprises, in addition to a first pair of spray nozzles comprising the first and second spray nozzles, a second pair of spray nozzles comprising a further first spray nozzle and a further second spray nozzle. A further cleaning section is arranged between the further first spray nozzle and the further second spray nozzle. The further first spray nozzle is configured to apply a first electrolyte jet to the first surface of the metal strip within the further cleaning section, and the further second spray nozzle is configured to apply a second electrolyte jet to the second surface of the metal strip within the further cleaning section.The power supply device is configured to apply an electrical voltage between the second and third nozzles. Each of the second and third nozzles is configured to apply an electrical voltage to the electrolytic fluid contained within them. The cleaning device is configured so that, during the application of the electrolytic fluid to the metal belt, an electric current flows either from the second nozzle through the first and second electrolyte jets across the metal belt to the second nozzle, or from the second nozzle through the second and first electrolyte jets across the metal belt to the first nozzle. The specially designed cleaning device enables even better cleaning of a metal strip. The second pair of spray nozzles can be positioned vertically below or above the first pair of spray nozzles, or at the same height as the first pair of spray nozzles, in the installation position of the cleaning device. The power supply device can be configured to apply an electrical voltage both between the first spray nozzle and the second spray nozzle, and between the further first spray nozzle and the further second spray nozzle. According to the invention, the power supply device can have a first power supply device and a second power supply device, wherein the first power supply device can be configured to apply an electrical voltage between the first spray nozzle and the second spray nozzle, and wherein the second power supply device can be configured to apply an electrical voltage between the further first spray nozzle and the further second spray nozzle. Preferably, the cleaning device has a deflection device for deflecting the metal belt, wherein the deflection device is arranged between the first pair of spray nozzles and the second pair of spray nozzles with respect to a transport direction of the metal belt through the at least one cleaning section. The cleaning device, designed accordingly, has the advantage of being more compact. In particular, the height of such a cleaning device can be reduced, while simultaneously achieving improved cleaning of a metal strip. The deflection device can, for example, have one deflection pulley or a plurality of deflection pulleys. Preferably, the cleaning device is designed such that the power supply device is configured to apply the same or an opposite electrical voltage between the further first spray nozzle and the further second spray nozzle as between the first spray nozzle and the second spray nozzle. According to an advantageous embodiment of the invention, the first electrolyte jet and the second electrolyte jet are the sole electrical conductors through which an electric current is introduced into the metal strip. This eliminates the need for mechanical current delivery devices, particularly current rollers or brushes. This offers advantages in terms of wear behavior and surface quality. Furthermore, the current path can be reduced, resulting in improved energy efficiency. If the first and second electrolyte jets are the only electrical conductors through which an electric current is introduced into the metal strip, this can also mean that at any given time, only one of the first or second electrolyte jets introduces an electric current into the metal strip. In this case, the other electrolyte jet can serve to carry away the current introduced into the metal strip. This aspect is relevant when using alternating currents. According to an advantageous embodiment of the invention, the first spray nozzle and / or the second spray nozzle comprise a base body and at least one, preferably slot-shaped, outlet opening for releasing the respective first electrolyte jet and / or second electrolyte jet. The outlet opening is preferably limited by an upper baffle and / or a lower baffle. In this way, a particularly efficient application of the first electrolyte jet and the second electrolyte jet can be achieved, resulting in advantages in terms of energy efficiency and wear behavior. A slot-shaped outlet opening can be one whose horizontal extent is significantly greater than its vertical extent. In particular, the horizontal extent can be more than three times, preferably more than five times, the vertical extent of the outlet opening. This can result in a particularly efficient application of electrical voltage to the first or second electrolyte jet, leading to advantages in terms of energy efficiency and wear behavior. The at least one outlet opening or a plurality of outlet openings can also be rectangular and / or square and / or round and / or elliptical. The omission of the first electrolyte jet and / or the second electrolyte jet can in particular include the generation of the first electrolyte jet and / or the second electrolyte jet. The basic body can at least partially limit a storage volume in three, four, five or all six spatial directions. The upper and / or lower aperture can be adjustable. This allows the size of the outlet opening to be adjusted, which has advantages with regard to the jet formation of the first electrolyte jet and / or the second electrolyte jet, and thus with regard to the surface quality of the strip. The cleaning device does not necessarily have an upper and / or a lower baffle. The at least one outlet opening can also be formed directly in the base body of the cleaning device. According to an advantageous embodiment of the invention, the base body of the first surge nozzle and / or the base body of the second surge nozzle is provided to apply an electrical voltage to the electrolytic liquid contained therein. This can result in a particularly efficient application of electrical voltage to the electrolytic fluid located in the respective base body, leading to advantages in terms of energy efficiency and wear behavior. The base body can be in direct electrically conductive contact with the power supply device. This can result in a particularly efficient application of electrical voltage to the first or second electrolyte jet, leading to advantages in terms of energy efficiency and wear behavior. The base body can be configured as an electrode. In particular, it can be provided that the entire internal surface of the base body allows an electric flow into the electrolytic fluid. The internal surface of the base body can be the surface of a receiving volume of the base body. This can result in a particularly efficient application of electrical voltage to the first or second electrolyte jet, leading to advantages in terms of energy efficiency and wear behavior. According to an advantageous embodiment of the invention, the upper aperture of the first spray nozzle and / or the lower aperture of the first spray nozzle and / or the upper aperture of the second spray nozzle and / or the lower aperture of the second spray nozzle are arranged to apply an electrical voltage to the electrolytic liquid located in the first spray nozzle and / or the second spray nozzle, respectively. This method allows for the particularly efficient introduction of an electrical voltage directly into the electrolytic fluid, especially at the point of origin of the respective electrolyte jet. This offers advantages in terms of energy efficiency. The first aperture and / or second aperture can each have a first end and a second end, with both the first and second ends being electrically connected to the power supply device. In this way, the respective aperture can be supplied with an electrical voltage particularly efficiently. This has advantages in terms of energy efficiency. The body of the first spray nozzle and / or the body of the second spray nozzle can preferably have an upper part and a lower part, wherein the upper part and the lower part are configured to apply the same voltage to the electrolytic fluid. Alternatively or additionally, the respective upper and lower apertures of the first and / or the second spray nozzle can be configured to apply the same voltage to the electrolytic fluid. This method allows for the particularly efficient introduction of an electrical voltage directly into the electrolytic fluid, especially at the point of origin of the respective electrolyte jet. This offers advantages in terms of energy efficiency. According to an advantageous embodiment of the invention, the power supply device is configured to apply an alternating voltage or a direct voltage between the first spray nozzle and the second spray nozzle. This allows for particularly efficient and electrode-friendly cleaning, as dirt particles deposited on the respective electrode, especially on the spray nozzles, are repelled during the phases in which the electrode functions as the anode. This results in advantages regarding wear behavior, surface quality, and energy efficiency. In particular, the power supply device can be configured to generate the applied voltage with a pulse pattern other than a sine wave. This can optimize the cleaning effect. For example, the pulse pattern can be quasi-sinusoidal, rectangular, triangular, or even interrupted. Such a pulse pattern can be generated by a switching rectifier. The pulse patterns can be implemented with alternating polarity (AC) or constant polarity (DC). According to an advantageous embodiment of the invention, the first spray nozzle and / or the second spray nozzle are arranged so that the respective first electrolyte jet and / or second electrolyte jet strike the first surface and / or the second surface of the metal strip at an angle in the range of 0° to 180°, preferably in the range of 20° to 160°, more preferably in the range of 45° to 135° and more preferably at an angle of 90° during the application of the electrolytic liquid to the metal strip. This allows the applied electrolytic fluid to wet the surface of the metal strip particularly evenly and also to flow off particularly efficiently by means of gravity, which has advantages in terms of surface quality and energy efficiency. The angle here is the angle between the surface of the metal strip and the motion vector of the respective electrolyte jet at the point where the electrolyte jet hits the respective surface of the metal strip. Those skilled in the art are aware that the angle of impact during actual operation of the cleaning device can vary due to variable environmental influences, such as fluctuations in the pressure of the electrolyte jet or air movements in the vicinity of the cleaning device. Therefore, the theoretical angle of impact must be used as a basis. Those skilled in the art are familiar with determining this angle, given the mechanical parameters of the cleaning device and the set operating parameters. According to an advantageous embodiment of the invention, the first spray nozzle and / or the second spray nozzle are arranged so that the respective first electrolyte jet and / or second electrolyte jet wets the respective first surface and / or second surface over the entire width of the metal strip with electrolyte liquid during the application of the electrolytic liquid to the metal strip. This allows the applied electrolytic fluid to wet the surface of the metal strip particularly evenly and also to flow off particularly efficiently by means of gravity, which has advantages in terms of surface quality and energy efficiency. "During the contact of the metal strip with the electrolyte fluid" can refer specifically to the steady-state cleaning operation. During a possible start-up phase, in which the pressure required for operation is built up in the electrolyte supply device, the cleaning device may not wet the surface of the metal strip across its entire width. The important point here is that wetting across the entire width of the metal strip occurs during steady-state cleaning operation, in which all operating parameters have approached their respective target values. Steady-state cleaning operation also includes situations where target values, such as pressure, are changed during operation. According to an advantageous embodiment of the invention, the cleaning device is designed to carry out the electrolytic treatment of the metal strip during movement of the metal strip at a strip speed of 1 m / min to 3,000 m / min, preferably from 10 m / min to 1,200 m / min, more preferably from 30 m / min to 500 m / min, and more preferably again from 100 m / min to 500 m / min. This allows for optimal cleaning of the metal strip, resulting in advantages in terms of surface quality and energy efficiency. According to an advantageous embodiment of the invention, the horizontal distance between the first spray nozzle and the second spray nozzle is between 1 mm and 1000 mm, preferably between 20 mm and 200 mm. In particular, the distance can be adjustable within this range. This results in a low voltage drop in the electrolyte jets. This allows the electric current to be introduced into the surface particularly efficiently via the electrolytic fluid, and also enables the use of a particularly advantageous area for the electric current. This offers benefits in terms of wear resistance, surface quality, and energy efficiency. In particular, the distance between the first surge nozzle and the second surge nozzle can be the distance between their respective outlet openings. According to an advantageous embodiment of the invention, the vertical distance between the first surge nozzle and the second surge nozzle is provided to be between 0 mm and 10000 mm, preferably between 0 mm and 8000 mm, more preferably between 0 mm and 5000 mm, more preferably between 1 mm and 3000 mm, more preferably between 10 mm and 1000 mm, more preferably between 20 mm and 500 mm, more preferably between 30 mm and 300 mm, and is particularly adjustable within this range. The distance can be adjusted by uniformly adjusting the first and second spray nozzles. This ensures that the distance between the first and second spray nozzles and the respective first and second surfaces of the metal strip remains constant. This results in particularly efficient wetting of each strip surface with electrolytic fluid. The present invention also aims to provide a method for the electrolytic treatment, preferably cleaning, of a metal strip which produces particularly low wear of the electrodes used, produces a particularly high surface quality of the cleaned strip and is particularly energy efficient. The problem underlying the present invention is solved by a method for the electrolytic treatment, preferably cleaning, of a metal strip that is transported along a transport direction or against the transport direction through a cleaning section of a cleaning device, the method comprising the following steps: - Applying an electrical voltage between at least a first spray nozzle and at least a second spray nozzle of the cleaning device. The first spray nozzle and the second spray nozzle transmit the electrical voltage to an electrolytic liquid exiting from the first spray nozzle and the second spray nozzle, respectively. - Applying the electrolytic liquid under electrical voltage to a first surface and a second surface of the metal strip by means of a first electrolyte jet and a second electrolyte jet.The application is carried out in such a way that an electric current either flows from the first jet nozzle through the first electrolyte jet, through the metal band and the second electrolyte jet to the second jet nozzle, or flows from the second jet nozzle through the second electrolyte jet, through the metal band and through the first electrolyte jet to the first jet nozzle. In this way, the current is introduced into the metal strip solely through the first or second electrolyte jet. This has the advantages that no mechanical wear is generated during current application, the surface of the metal strip being treated remains undamaged and is therefore of higher quality, and overall, less electrical power is lost, making the process more energy-efficient. In particular, the first electrolyte jet and / or the second electrolyte jet can be generated as a predominantly laminar flow. This allows for particularly efficient wetting of the strip surface, thereby improving surface quality. The person skilled in the art is sufficiently familiar with the process parameter settings and the necessary design of the cleaning device used to generate laminar flows. In particular, they know that the exit velocity of the electrolytic fluid, the pressure prevailing in the respective nozzle, the edge rounding of the outlet opening, and the transition radii existing inside the respective nozzle are essential setting parameters for achieving a laminar flow. According to an advantageous embodiment of the invention, the method is carried out using a cleaning device as described above. This involves using a cleaning device for the process which, due to its characteristics, enables a particularly wear-free and energy-efficient cleaning of a metal strip, producing a surface of particularly high quality. According to an advantageous embodiment of the invention, it is provided that an alternating or direct voltage is applied between the first spray nozzle and the second spray nozzle, wherein the alternating voltage preferably has a frequency between 0 Hz and 500 Hz, more preferably between 2 Hz and 200 Hz, and more preferably between 20 Hz and 60 Hz. This allows for particularly efficient and electrode-friendly cleaning, as dirt particles deposited on the respective electrode, especially on the spray nozzles, are repelled during the phases in which the electrode functions as the anode. This results in advantages regarding wear behavior, surface quality, and energy efficiency. According to an advantageous embodiment of the invention, the pulse pattern of the alternating or direct voltage is sinusoidal, triangular, rectangular, trapezoidal or intermittent. This allows for particularly efficient and electrode-friendly cleaning, resulting in advantages in terms of wear behavior, surface quality and energy efficiency. In particular, such a pulse pattern can be generated by a switching rectifier. According to an advantageous embodiment of the invention, the current density in the first electrolyte jet and / or in the second electrolyte jet is in the range of 0 A / dm2 to 1500 A / dm2, preferably in the range of 0 A / dm2 to 850 A / dm2, particularly preferably in the range of 1 A / dm2 to 550 A / dm2, and more preferably in the range of 2 A / dm2 to 350 A / dm2. This method utilizes particularly high current densities for cleaning, thereby increasing the effective power. This offers advantages in terms of surface quality. The current density can be measured, in particular, perpendicular to the principal velocity vector in the electrolyte jet. According to an advantageous embodiment of the invention, the electrical voltage applied between the first spray nozzle and the second spray nozzle is in the range of 0 V to 500 V, preferably in the range of 10 V to 300 V, and more preferably in the range of 30 V to 120 V. Such tensions enable particularly efficient cleaning, which has advantages in terms of energy efficiency and wear behavior. According to an advantageous embodiment of the invention, the electric current flowing from the first surge nozzle to the second surge nozzle and / or from the second surge nozzle to the first surge nozzle has a current strength in the range of 0 A to 2500 A, preferably in the range of 0 A to 1000 A, more preferably in the range of 30 A to 500 A, and more preferably in the range of 50 A to 300 A. In this way, particularly efficient current densities can be achieved, resulting in energy-efficient and low-wear cleaning. Further advantages, details and features of the invention will become apparent from the exemplary embodiments described below. Specifically, the figures show: Fig. 1: a schematic representation of a cleaning device according to the invention; Fig. 2: a schematic representation of a cleaning device according to a further embodiment; Fig. 3: a schematic representation of a cleaning device according to a further embodiment; Fig. 4: a schematic, three-dimensional representation of a first or second spray nozzle; and Fig. 5: a schematic, partial representation of a metal strip to be cleaned by means of a cleaning device according to the invention in the area of ​​the cleaning section. In the following description, identical reference numerals denote identical components or identical features, so that a description of a component given in relation to one figure also applies to the other figures, thus avoiding repetitive descriptions. Furthermore, individual features described in connection with one embodiment can also be used separately in other embodiments. Fig. 1 shows a schematic representation of a cleaning device 1 according to the invention. The cleaning device 1 is designed to electrolytically clean a metal strip B moving along a transport direction T or opposite to the transport direction T through a cleaning section 2. For this purpose, the cleaning device 1 has a first spray nozzle 10 and a second spray nozzle 20. The first spray nozzle 10 is configured to apply a first electrolyte jet 11 to a first side 4 of the metal strip B moving through the cleaning section 2 during the cleaning process. Similarly, the second spray nozzle 20 is configured to apply a second electrolyte jet 21 to a second side 5 of the metal strip B moving through the cleaning section 2 during the cleaning process. For this purpose, an electrolytic liquid 3 is located in a receiving volume V of the first surge nozzle 10 and the second surge nozzle 20. The first spray nozzle 10 and the second spray nozzle 20 are located on the first side 4 and the second side 5 of the metal strip B, respectively. Thus, the first spray nozzle 10 and the second spray nozzle 20 are located on two opposite sides 4 and 5 of the metal strip B. In the embodiment shown here, the first spray nozzle 10 and the second spray nozzle 20 are identical, but mirror images of each other. In another embodiment, not shown here, the first spray nozzle 10 and the second spray nozzle 20 are designed differently. Fig. 2 shows a schematic representation of a cleaning device 1 according to a further embodiment of the invention. The structure and function of the cleaning device shown in Fig. 2 essentially correspond to that of the cleaning device 1 shown in Fig. 1, wherein the cleaning device 1 shown in Fig. 2 has, in addition to the first pair of spray nozzles 10, 20, a second pair of spray nozzles 10', 20', which has a further first spray nozzle 10' and a further second spray nozzle 20'. A further cleaning section 2' is arranged between the further first spray nozzle 10' and the further second spray nozzle 20'. The further first jet nozzle 10' is designed to apply a first electrolyte jet within the further cleaning section 2' to the first surface 4 of the metal strip B, and the further second jet nozzle 20' is designed to apply a second electrolyte jet within the further cleaning section 2' to the second surface 5 of the metal strip B. The power supply device 30, or another power supply device not shown in the figures, is configured to apply an electrical voltage between the further first spray nozzle 10' and the further second spray nozzle 20'. For clarity, the electrical connections between the power supply device 30 and the further first spray nozzle 10' and the further second spray nozzle 20' are not shown. The further first spray nozzle 10' and the further second spray nozzle 20' are each configured to apply an electrical voltage to the electrolytic fluid contained within them. As can be seen in Fig. 2, the second pair of spray nozzles 10', 20' is arranged vertically below the first pair of spray nozzles 10, 20 in the installation position of the cleaning device 1 shown in Fig. 2. The cleaning device 1 is configured such that, during the application of the electrolytic liquid 3 to the metal strip B, an electric current flows either from the second first spray nozzle 10' through the first electrolyte jet 11 and the second electrolyte jet 21 through the metal strip B to the second second spray nozzle 20', or from the second second spray nozzle 20' through the second electrolyte jet 21 and the first electrolyte jet 11 through the metal strip B to the second first spray nozzle 10'. Fig. 3 shows a schematic representation of a cleaning device 1 according to a further embodiment of the invention. Like the cleaning devices 1 shown in Figs. 1 and 2, the cleaning device 1 shown in Fig. 3 has a deflecting device 50 for deflecting the metal belt B. In the cleaning device 1 shown in Fig. 3, the deflecting device 50 is arranged, with respect to the transport direction T of the metal belt B through at least one cleaning section 2, 2', between the first pair of spray nozzles 10, 20 and the second pair of spray nozzles 10', 20'. As can be seen particularly in Fig. 4, the first spray nozzle 10, 10' and the second spray nozzle 20, 20' each have a base body 12, 22 and each have an outlet opening 13, 23. The outlet openings 13, 23 are each limited by an upper orifice 14, 24 and a lower orifice 15, 25. The upper orifices 14, 24 and the lower orifices 15, 25 can be adjusted such that the respective sizes of the outlet openings 13, 23 can be changed. This makes it possible to adjust the exit velocity of the electrolyte fluid 3 and thus the pressure and the flow characteristics, in particular the state of laminar flow, of the first electrolyte jet 11 and the second electrolyte jet 21. The cleaning device 1 is configured for electrolytic cleaning. For this purpose, the cleaning device 1 includes a power supply unit 30. The power supply unit 30 is electrically connected to both the first spray nozzle 10, 10' and the second spray nozzle 20, 20' by means of suitable electrical conductors. This enables the power supply unit 30 to apply an electrical voltage to both the first spray nozzle 10, 10' and the second spray nozzle 20, 20', which can be either a direct current or an alternating current. In the embodiments of the cleaning device 1 shown in Figures 2 and 3, the electrical conductors between the power supply unit 30 and the spray nozzles 10', 20' are not shown for clarity. Due to the application of alternating voltage to the first jet nozzle 10, 10' and to the second jet nozzle 20, 20', an electric current either flows from the first jet nozzle 10, 10' through the first electrolyte jet 11 and through that section of the metal strip on which the first and second electrolyte jets 11, 21 strike, and further through the second electrolyte jet 21 to the second jet nozzle 20, 20'. Or an electric current flows in exactly the opposite direction, i.e., from the second jet nozzle 20, 20' through the second electrolyte jet 21 and through that section of the metal strip on which the first and second electrolyte jets 11, 21 strike, and further through the first electrolyte jet 11 to the first jet nozzle 10, 10'.In particular, an electrical circuit is closed by means of the electrolyte jets 11, 21 from the power supply device 30 through the first and second jet nozzle 10, 20; 10', 20', the first and second electrolyte jet 11, 21 and the metal band B. In this way, areas are created on the surfaces 4, 5 of the metal strip which are wetted by an electrolytic liquid 3 under voltage, thus enabling the electrolytic cleaning process. The power supply device 30 can be a switching rectifier 30. The cleaning device 1 includes an electrolyte supply device 40 for supplying the first spray nozzle 10, 10' and the second spray nozzle 20, 20' with electrolyte fluid 3. In the example shown here, this consists of an unspecified collection basin for the electrolyte fluid 3 and several pumps and processing devices for the treatment and transport of the electrolyte fluid 3. In the embodiments of the cleaning device 1 shown here, the cleaning section 2, 2' is located above the collection basin. Furthermore, the cleaning device 1 is configured so that the metal strip B runs vertically through the cleaning section 2, 2'. This allows the electrolyte to run down the metal strip B by gravity after impacting it and drip or flow into the collection basin. In this way, a cycle of the electrolyte 3, including its purification, is enabled. Fig. 4 shows a surge nozzle 10, 20; 10', 20' according to the invention in a more detailed, albeit schematic, three-dimensional view. The base body 12, 22 encloses a receiving volume V for receiving electrolytic fluid 3. The spray nozzle 10, 20; 10', 20' also has an outlet opening 13, 23. This is bounded above and below by an upper orifice 14, 24 and a lower orifice 15, 25. The upper apertures 14, 24 and the lower apertures 15, 25 are designed as electrodes. For this purpose, the apertures 14, 15, 24, 25 have electrical contacts that are electrically conductively connected to the power supply device 30. In a second embodiment, also according to the invention, the respective base bodies 12, 22 are designed as electrodes. In further embodiments according to the invention, any combination of the upper aperture 14, 24, lower aperture 15, 25 and base body 12, 22 are designed as electrodes. Regardless of which parts of the spray nozzles 10, 20; 10', 20' are configured as electrodes, the first spray nozzle 10, 10' and the second spray nozzle 20, 20' are configured to transmit the voltage provided by the power supply device 30 to the electrolytic fluid 3 located in the receiving volume V and / or the outlet opening 13, 23. This allows an electric current to flow through the first electrolyte jet 11 and the second electrolyte jet 21. It can be seen that the electrolytic liquid 3 leaves the outlet opening 13, 23 along an outlet direction 16, 26 in the form of the first or second electrolyte jet 11, 21. Fig. 5 shows a partial view of the metal strip B located in the cleaning section 2, 2'. It can be seen that the first electrolyte jet 11 and the second electrolyte jet 21 strike the first and second surfaces 4, 5 of the metal strip B at an angle β, β'. The inventive method for the electrolytic cleaning of a metal strip is carried out on a cleaning device described above. Reference is therefore made to the above explanations. The method serves for the electrolytic cleaning of a metal strip B, which is transported along a transport direction T or against the transport direction T through a cleaning section 2, 2' of the cleaning device 1. The method comprises the following steps: The metal strip B is transported by means of a transport device, not described in detail here, along a transport direction T or against the transport direction T through the cleaning section 2, 2' of the cleaning device. The transport direction T is vertically oriented. An alternating or direct current (AC) voltage is applied between the first spray nozzle 10, 10' and the second spray nozzle 20, 20' of the cleaning device 1 by means of the power supply device 30. The AC or DC voltage has a frequency of 20 to 60 Hz and voltage levels in the range of 30 V to 120 V. This results in currents in the range of 50 A to 200 A. The current density in the two electrolyte jets is 1 A / dm² to 200 A / dm². The AC voltage is designed with a triangular, rectangular, trapezoidal, or intermittent pulse pattern. The spray nozzles 10, 20; 10', 20' are supplied with electrolytic fluid 3 by means of the electrolyte supply device 40 and each generates a first and second electrolyte jet 11, 21, which are directed towards the opposite surfaces 4, 5 of the metal strip B. The first electrolyte jet 11 and the second electrolyte jet 21 are designed as laminar or turbulent flow. This electrolytic fluid 3, which is under electrical voltage, is applied to a first surface 4 and a second surface 5 of the metal strip B by means of the first electrolyte jet 11 and the second electrolyte jet 21. The application is carried out such that an electric current flows either from the first jet nozzle 10, 10' along the first electrolyte jet 11 and the second electrolyte jet 21 to the second jet nozzle 20, 20', or from the second jet nozzle 20, 20' along the second electrolyte jet 21 and the first electrolyte jet 11 to the first jet nozzle 10, 10'. Thus, the two electrolyte jets 11, 21 act as electrical conductors, introducing the current necessary for electrolytic cleaning into the metal strip B and also carrying it back out. Further devices for introducing the current, in particular by mechanical contact, are therefore unnecessary. Reference symbol list 1 Cleaning device 2 Cleaning section 3 Electrolytic fluid 4 First surface 5 Second surface 10, 10' First jet nozzle 11 First electrolyte jet 12 Base body (of the first jet nozzle) 13 Outlet opening (of the first jet nozzle) 14 Upper orifice (of the first jet nozzle) 15 Lower orifice (of the first jet nozzle) 20, 20' Second jet nozzle 21 Second electrolyte jet 22 Base body (of the second jet nozzle) 23 Outlet opening (of the second jet nozzle) 24 Upper orifice (of the second jet nozzle) 25 Lower orifice (of the second jet nozzle) 30 Power supply device 40 Electrolyte supply device 50 Deflection device B Metal belt T Transport direction (of the metal belt) V Absorption volume (of the first or second jet nozzle) β Angle (of the first electrolyte jet) β' Angle (of the second electrolyte jet) QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature EP 3 514 263

[0008]

Claims

Cleaning device (1) for the electrolytic treatment, in particular cleaning, of a metal strip (B) in at least one cleaning section (2, 2') of the cleaning device (1), wherein the cleaning device (1) comprises: - at least one first spray nozzle (10, 10'), - at least one second spray nozzle (20, 20'), - a power supply device (30), and - an electrolyte supply device (40) for supplying the at least one first spray nozzle (10, 10') and the at least one second spray nozzle (20, 20') with an electrolytic liquid (3), wherein the cleaning device (1) has the following features: - the at least one cleaning section (2, 2') is arranged between the at least one first spray nozzle (10, 10') and the at least one second spray nozzle (20, 20');- the at least one first spray nozzle (10, 10') is configured to apply a first electrolyte jet (11) within the at least one cleaning section (2, 2') to a first surface (4) of the metal strip (B), and the at least one second spray nozzle (20, 20') is configured to apply a second electrolyte jet (21) within the at least one cleaning section (2, 2') to a second surface (5) of the metal strip (B) opposite the first surface (4); - the power supply device (30) is configured to apply an electrical voltage between the at least one first spray nozzle (10, 10') and the at least one second spray nozzle (20, 20');and- the at least one first spray nozzle (10, 10') and the at least one second spray nozzle (20, 20') are each configured to apply an electrical voltage to the electrolytic liquid (3) contained therein, characterized in that the cleaning device (1) is configured such that, during the application of the electrolytic liquid (3) to the metal strip (B), an electric current flows either from the first spray nozzle (10, 10') through the first electrolyte jet (11) and the second electrolyte jet (21) through the metal strip (B) to the second spray nozzle (20, 20') or from the second spray nozzle (20, 20') through the second electrolyte jet (21) and the first electrolyte jet (11) through the metal strip (B) to the first spray nozzle (10, 10'). Cleaning device (1) according to claim 1, characterized by the following features: - the cleaning device (1) has, in addition to a first pair of spray nozzles (10, 20) comprising the first spray nozzle (10) and the second spray nozzle (20), a second pair of spray nozzles (10', 20') comprising a further first spray nozzle (10') and a further second spray nozzle (20'); - a further cleaning section (2') is arranged between the further first spray nozzle (10') and the further second spray nozzle (20'); - the further first spray nozzle (10') is configured to apply a first electrolyte jet (11) within the further cleaning section (2') to the first surface (4) of the metal strip (B), and the further second spray nozzle (20') is configured to apply a second electrolyte jet (21) within the further cleaning section (2') to the second surface (5) of the to apply metal band (B);- the power supply device (30) is configured to apply an electrical voltage between the further first jet nozzle (10') and the further second jet nozzle (20'); - the further first jet nozzle (10') and the further second jet nozzle (20') are each configured to apply an electrical voltage to the electrolytic fluid (3) contained therein; and - the cleaning device (1) is configured so that, during the application of the electrolytic fluid (3) to the metal belt (B), an electric current flows either from the further first jet nozzle (10') through the first electrolyte jet (11) and the second electrolyte jet (21) through the metal belt (B) to the further second jet nozzle (20') or from the further second jet nozzle (20') through the second electrolyte jet (21) and the first electrolyte jet (11) through the metal belt (B) to the further first jet nozzle (10'). Cleaning device (1) according to one of the preceding claims, characterized by the following features: - the cleaning device (1) has a deflecting device (50) for deflecting the metal belt (B); - the deflecting device (50) is arranged with respect to a transport direction (T) of the metal belt (B) through the at least one cleaning section (2, 2') between the first pair of spray nozzles (10, 20) and the second pair of spray nozzles (10', 20'). Cleaning device (1) according to claim 2 or 3, characterized in that the power supply device (30) is configured to apply the same or an opposite electrical voltage between the further first spray nozzle (10') and the further second spray nozzle (20') as between the first spray nozzle (10) and the second spray nozzle (20). Cleaning device (1) according to one of the preceding claims, characterized in that the first electrolyte jet (11) and the second electrolyte jet (21) are the sole electrical conductors through which an electric current is introduced into the metal strip (B). Cleaning device (1) according to one of the preceding claims, characterized in that the first spray nozzle (10, 10') and / or the second spray nozzle (20, 20') have a base body (12, 22) and at least one, preferably slot-shaped, outlet opening (13, 23) for releasing the respective first electrolyte jet (11) and / or second electrolyte jet (21), wherein the outlet opening (13, 23) is preferably limited by an upper aperture (14, 24) and / or a lower aperture (15, 25). Cleaning device (1) according to claim 6, characterized in that the base body (12) of the first spray nozzle (10, 10') and / or the base body (22) of the second spray nozzle (20, 20') is configured to apply an electrical voltage to the electrolytic liquid (3) contained therein. Cleaning device (1) according to claim 6 or 7, characterized in that the upper orifice (14) of the first spray nozzle (10, 10') and / or the lower orifice (15) of the first spray nozzle (10, 10') and / or the upper orifice (24) of the second spray nozzle (20, 20') and / or the lower orifice (25) of the second spray nozzle (20, 20') are configured to apply an electrical voltage to the electrolytic fluid (3) located in the first spray nozzle (10, 10') and / or the second spray nozzle (20, 20'). Cleaning device (1) according to one of the preceding claims, characterized in that the power supply device (30) is configured to apply an alternating voltage or direct voltage between the first spray nozzle (10, 10') and the second spray nozzle (20, 20'). Cleaning device (1) according to one of the preceding claims, characterized in that the first spray nozzle (10, 10') and / or the second spray nozzle (20, 20') are configured to ensure that the respective first electrolyte jet (11) and / or second electrolyte jet (21) strikes the first surface (4) and / or the second surface (5) of the metal strip (B) at an angle (β, β') in the range of 0° to 180°, preferably in the range of 20° to 160°, more preferably in the range of 45° to 135° and more preferably at an angle of 90° during the application of the electrolytic liquid (3) to the metal strip (B). Cleaning device (1) according to one of the preceding claims, characterized in that the first spray nozzle (10, 10') and / or the second spray nozzle (20, 20') are configured to ensure that the respective first electrolyte jet (11) and / or second electrolyte jet (21) wets the respective first surface (4) and / or second surface (5) over the entire width of the metal strip (B) with electrolyte liquid (3) during the application of the electrolytic liquid (3) to the metal strip (B). Cleaning device (1) according to one of the preceding claims, characterized in that the cleaning device (1) is configured to carry out the electrolytic treatment of the metal strip (B) during a movement of the metal strip (B) at a strip speed of 1 m / min to 3,000 m / min, preferably from 10 m / min to 1,200 m / min, more preferably from 30 m / min to 500 m / min, and more preferably from 100 m / min to 500 m / min. Cleaning device (1) according to one of the preceding claims, characterized in that the horizontal distance of the first spray nozzle (10, 10') to the second spray nozzle (20, 20') is between 1 mm and 1000 mm, preferably between 20 mm and 200 mm, and is in particular adjustable within this range, and / or that the vertical distance of the first spray nozzle (10, 10') to the second spray nozzle (20, 20') is between 0 mm and 10000 mm, preferably between 0 mm and 8000 mm, more preferably between 0 mm and 5000 mm, more preferably between 1 mm and 3000 mm, more preferably between 10 mm and 1000 mm, more preferably between 20 mm and 500 mm, more preferably between 30 mm and 300 mm, and is in particular adjustable within this range. A method for the electrolytic treatment, preferably cleaning, of a metal strip (B) which is transported along a transport direction (T) or against the transport direction (T) through a cleaning section (2) of a cleaning device (1), the method comprising the following steps: - Applying an electrical voltage between at least a first spray nozzle (10, 10') and at least a second spray nozzle (20, 20') of the cleaning device (1), wherein the first spray nozzle (10, 10') and the second spray nozzle (20, 20') transmit the electrical voltage to an electrolytic liquid (3) exiting from the first spray nozzle (10, 10') and the second spray nozzle (20, 20'), respectively; - Applying the electrolytic liquid (3) under electrical voltage to a first surface (4) and a second surface (5) of the metal strip (B) by means of a first electrolyte jet (11) and a second electrolyte jet (21) such thatthat an electric current flows either from the first jet nozzle (10, 10') through the first electrolyte jet (11), through the metal band (B) and the second electrolyte jet (21) to the second jet nozzle (20, 20') or from the second jet nozzle (20, 20') through the second electrolyte jet (21), through the metal band (B) and through the first electrolyte jet (11) to the first jet nozzle (10, 10'). Method according to claim 13, characterized in that the method is carried out by means of a cleaning device (1) according to one of claims 1 to 13. Method according to one of claims 14 or 15, characterized in that an alternating voltage or direct voltage is applied between the first surge nozzle (10, 10') and the second surge nozzle (20, 20'), wherein the alternating voltage preferably has a frequency between 0 Hz and 500 Hz, more preferably between 2 Hz and 200 Hz, more preferably between 20 Hz and 60 Hz. Method according to claim 16, characterized in that the pulse pattern of the alternating voltage or direct voltage is sinusoidal, triangular, rectangular, trapezoidal or intermittent. Method according to one of claims 14 to 17, characterized in that the current density in the first electrolyte jet (11) and / or in the second electrolyte jet (21) is in the range of 0 A / dm2 to 1500 A / dm2, preferably in the range of 0 A / dm2 to 850 A / dm2, particularly preferably in the range of 1 A / dm2 to 550 A / dm2, and further preferably in the range of 2 A / dm2 to 350 A / dm2. Method according to one of claims 14 to 18, characterized in that the electrical voltage applied between the first surge nozzle (10, 10') and the second surge nozzle (20, 20') is in the range of 0 V to 500 V, preferably in the range of 10 V to 300 V, more preferably in the range of 30 V to 120 V. Method according to one of claims 14 to 19, characterized in that the electric current flowing from the first surge nozzle (10, 10') to the second surge nozzle (20, 20') and / or from the second surge nozzle (20, 20') to the first surge nozzle (10, 10') has a current strength in the range of 0 A to 2500 A, preferably in the range of 0 A to 1000 A, more preferably in the range of 30 A to 500 A, and more preferably in the range of 50 A to 300 A.

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