Device for applying a coating agent

Abstract

Device (100) for electrostatically applying a liquid, atomized coating agent (1) to a substrate (110) movable in a propulsion direction F, in particular a metal strip or sheet strip to be wound into a coil, having a delivery device (2) or pump for the coating agent (1) provided in a reservoir or in another way, having a control unit (3) for the application process, having a carrier (5) for holding a discharge device (2) in the form of a nozzle beam (50), wherein the discharge device (2) is arranged at least above the substrate (110), preferably above and below the substrate (110), at a distance from the substrate, and is provided with at least one chamber (51, 52) and a plurality of discharge openings, slits or nozzle openings (54) in the direction of the substrate (110), wherein the nozzle beam (50) has at least two chambers (51, 52) which are hydraulically separated from one another, each with a separate supply line (41, 42) for a coating agent (1) of a selectable different or identical type in the chambers (51, 52), and in the nozzle beam (50) for each of the chambers (51, 52) a dedicated and integrated switching valve (60) is provided for opening / closing the chambers (51, 52) and the connection to the nozzle openings (54) or a group of nozzle openings (54).

Description

Technical Field

[0001] This invention relates to an apparatus having at least one nozzle beam for electrostatically applying a coating agent or different types of coating agents to a substrate that can move at a constant or variable speed beside the nozzle beam, particularly for applying a coating agent in the form of a corrosion inhibitor, such as oil, to a sheet, metal strip, or sheet strip being conveyed beside the nozzle beam. Various facilities and methods have been proposed in the prior art as apparatus for such strip coating processes. This invention relates to an electrostatic coating process in which an atomized coating agent is sprayed through a so-called nozzle beam having multiple individual nozzle openings or slit-like elongated openings. Background Technology

[0002] It is known that in the manufacture of sheet metal strips, before being wound into so-called coils, or before further manufacturing steps and processing into products composed of sheet metal strips, the sheet metal is coated with a corrosion inhibitor of a defined thickness to protect the surface from corrosion until further processing. Other types of coating agents are also used within the framework of such metal strip processing facilities, which can be applied as thin layers continuously to the surface of the sheet metal strip using such devices. For this purpose, in such known devices in the prior art, a so-called nozzle beam is arranged above and / or below the substrate or metal strip to be coated, using which a pre-programmed amount of corrosion inhibitor as a coating can be applied uniformly and uninterruptedly on the upper side of the sheet metal strip, and if necessary, simultaneously on the lower side.

[0003] Such devices, as known to date in the prior art, are described, for example, in IT 1223608 B and DE 83 19 162U1. The nozzle beam of these known devices has one or two chambers internally filled entirely or partially with oil as a coating agent, and holes or alternatively through slots connected to the chambers along the length of the nozzle beam, serving as discharge devices. A finely atomized corrosion inhibitor is discharged from these chambers due to the application of a high-voltage electric field for electrostatic application. This corrosion inhibitor wets the surface of the sheet or metal strip passing alongside the nozzle beam in the conveying direction as a coating film.

[0004] In the apparatus from IT 1223608 B, a first chamber for oil or corrosion inhibitor is provided in the nozzle beam, wherein a parallel-extending second chamber is traversed by a heat carrier fluid to provide heating equipment for the nozzle beam for heating the coating agent used in the coating process. The apparatus requires a costly shutdown of the manufacturing process when changing the type of coating agent used, because the chamber filled with oil must first be completely flushed or cleaned in order to fill with a new coating agent.

[0005] As described in the prior art according to DE 83 19 162 U1, different slit widths of the discharge device can be manually adjusted by adjusting the distance between multiple plates of the nozzle beam to regulate the desired coating amount. Two oil chambers formed between the inner and outer plates are filled with the same corrosion inhibitor, and only the slit width is varied to accommodate different amounts of corrosion inhibitor. In these known devices, the chambers in the nozzle beam for the coating agent are individually filled, either completely or partially, with significant amounts of the coating agent. When changing to another type of coating agent (e.g., another type of oil), these remaining amounts must first be completely drained, leading to losses and defects during the coating process. Customers of such coated metal strips or coils often specify different corrosion inhibitors as coating agents for corrosion protection and subsequent application purposes. Therefore, during the operation of the coating facility, it is frequently necessary to change from one coating agent to another, a second coating agent.

[0006] One disadvantage of the apparatus with the nozzle beam known from the prior art, particularly IT 1223608 B and DE 83 19 162 U1, is that when changing the coating agent to another type, the chamber in the nozzle beam that is completely or partially filled with the coating agent or oil must first be emptied by extruding the old coating agent in order to be filled with the new coating agent. This process results in a considerable downtime for the production line, as the next coating process can only be restarted when the coating agent replacement in the nozzle beam is completely finished. Alternatively, a certain amount of oil mixing must be accepted on the substrate to be coated for a specific period of time. The duration of oil mixing on the substrate varies depending on the oil application and facility speed, and is generally a significant quality defect for that portion of the sheet or substrate.

[0007] Furthermore, in known devices, in the relatively large and long coating agent chamber of such devices in the nozzle beam, mixing occurs between the previous coating agent and the next coating agent each time the coating agent is changed, which requires a rinsing process or cleaning, in which a significant amount of mixed oil that should be disposed of as waste is generated.

[0008] Therefore, in the daily operation of such coating facilities, these known units with conventional nozzle beams incur high costs due to downtime during coating agent replacement, and generate a significant amount of unusable mixed oil as waste each time the coating agent is replaced, which must be disposed of in compliance with regulations. Consequently, flexibility regarding the replacement or matching of oil spray volume cannot be provided. Even in cases where the seam width can be manually changed by adjusting the distance between the plates, as in DE 83 19 162 U1, the facility must still be shut down to match larger or smaller amounts of applied corrosion inhibitor. Summary of the Invention

[0009] Against this backdrop, the objective of this invention is to improve the apparatus of the type mentioned at the beginning, providing greater flexibility in matching different amounts and types of coating agents, and especially enabling very rapid switching between two different types of coating agents with minimal downtime and with minimal unwanted mixed oil as waste. With this invention, switching between more than two coating agents should also be possible without downtime of the entire facility.

[0010] This task is accomplished by a device having the features of claim 1. Advantageous designs and improvements of the invention are the subject of the dependent claims.

[0011] According to the present invention, an apparatus is provided for electrostatically applying a liquid, atomized coating agent to a substrate movable in a propulsion direction F, particularly a metal strip or sheet strip that can be wound into a roll. The apparatus includes a delivery device or pump for supplying the coating agent in a tank or otherwise, particularly from an external source; a control unit for the application process; and a carrier for maintaining a discharge device in the form of a nozzle beam. The discharge device is arranged at least above, preferably above and below, the substrate at a distance from it, and has at least one chamber and a plurality of discharge ports, slots, or nozzle openings along the direction toward the substrate. The apparatus is characterized in that the nozzle beam has at least two hydraulically separated chambers, separate supply lines for selectively different or identical types of coating agents in the chambers, and a dedicated and integrated switching valve is provided in the nozzle beam for each chamber, for opening / closing the chamber and connecting to the nozzle opening or a set of nozzle openings. Therefore, an efficient and flexible apparatus for electrostatically applying coating agents is provided, in which a nozzle beam has at least two, preferably more than two, chambers for coating agents, allowing separate or different coating agents to be selectively filled into the chambers and sprayed out via a switching valve when a rapid change from one coating agent to another is desired. The apparatus according to the invention can also utilize the presence of the same coating agent in two or more chambers of the nozzle beam, enabling a thicker coating on the substrate by means of two delivery pumps and from the nozzle openings or discharge devices of the respective chambers. For this purpose, the invention features an integrated switching valve configured to switch the connection from at least two chambers to the nozzle openings. The switching valve can be configured for a single nozzle opening or for specific sections or areas of multiple combined nozzle openings. Using the integrated switching valve directly mounted in the nozzle beam, not only can at least two different chambers for applying different coating agents be opened and closed separately, but different coating patterns can also be flexibly adjusted.

[0012] Unlike existing devices, this new device allows for uninterrupted operation of coating facilities or sheet metal processing facilities, even if a change from type A to type B coating agent is necessary, such as the application of a coating agent used as a corrosion inhibitor. This is achieved by simply closing one chamber while simultaneously opening the other via a switching valve through a control unit to continue applying the corrosion inhibitor. By utilizing at least two hydraulically separated chambers integrated into the nozzle beam, the coating agent sprayed through the discharge device in the nozzle beam can be varied—more precisely, this relates to its application amount in a specific area, its total application amount, or its type and composition among different types of coating agents. Therefore, the technological advantages of this new device for applying coating agents are considerable compared to existing devices of this kind. As at least two separate chambers for the coating agent, cavities can be directly integrated into the same nozzle beam. It is also possible to manufacture a one-piece nozzle beam based on a split housing, in which at least two separately constructed chambers for the coating agent are present. In both cases, the discharge device is connected to the two chambers via corresponding internal pipes, channels or the like, in the form of multiple rows of nozzle openings or alternatively in the form of elongated slits, and can be switched on or off via an integrated switching valve.

[0013] In this way, the complete hydraulic application of the coating agent can be controlled from within the nozzle beam, and this control can be operated by a control unit preferably located externally. The number of nozzle openings is not limited, and each of the coating chambers / switching valves can either open or close an entire row of nozzle openings, or only open or close a segment of a defined number or group of nozzle openings. Thus, the invention advantageously produces different coating patterns on the surface of a substrate without requiring costly matching and modification of the nozzle beam. According to the invention, at least two chambers and correspondingly associated at least two switching valves can be provided. Alternatively, more than two chambers and correspondingly more switching valves may also be present.

[0014] In the nozzle beam, different nozzle openings of the device can be controlled by a separate switching valve integrated in the nozzle beam, allowing individual nozzle openings to be selectively opened or closed via a control unit. Signal lines are preferably connected to control the nozzle beam and, particularly, the switching valves for opening and closing the chambers and nozzle openings. Similarly, the control unit can also be used to control the delivery pump for supplying pressured coating agent at the nozzle beam. According to the invention, separate supply lines are provided for each of the provided chambers, i.e., at least two chambers, allowing for the use of different types of coating agents during continuous operation.

[0015] For the replacement of the first coating agent with another alternative second coating agent within the chamber, the existing second chamber can continue to be operated for coating. The first chamber only needs to be completely flushed, which does not affect the continued operation of the second chamber. Thus, different types of coating agents can be replaced without interrupting continuous operation using the present invention. Alternatively, the same coating agent can be filled into both chambers and applied via separate supply lines using corresponding delivery pumps for fine atomization by means of an electrostatic coating method. Here, the delivery pumps can also be operated at different speeds, in such a way that the control unit operates them accordingly. Alternatively, one of the delivery pumps can be stopped, so that only oil is applied from one of the chambers. Thus, at a preset delivery speed to the substrate to be coated, a variable spray volume can be easily achieved by changing the corresponding coating amount.

[0016] According to an advantageous design of the invention, a central branch line is provided between at least two chambers of the nozzle beam and the nozzle opening in the nozzle beam. The central branch line is selectively connected to a first chamber, a second chamber, or another chamber via an internal channel in the nozzle beam or via a switching valve, respectively, to apply the coating agent currently present in the desired chamber onto the substrate or sheet material as a thin coating. The branch line is integrated into the nozzle beam and correspondingly has a relatively short length. Thus, when changing between the first chamber, the second chamber, or another chamber to apply a different coating agent to the substrate, only this small amount of residual material in the branch line needs to be drained. This does not require stopping the continuous operation of the coating facility or the production equipment for sheet material. Therefore, no downtime occurs, and the device according to the invention also achieves low maintenance due to the compact nozzle beam.

[0017] According to an advantageous design of the invention, the control unit is configured for individually operating the control valves. Therefore, the control unit, preferably located outside the nozzle beam and outside the electrostatic high-voltage field, is specifically matched to operate the individual control valves, so that each chamber, group of nozzle openings, or even the individual nozzle opening itself can be individually operated in each of the nozzle beams of the device. This allows for flexible adjustment of a wide variety of applications at the device according to the invention, such as variably setting or changing different coating patterns or coating thicknesses as needed. For this purpose, the corresponding operation of the switching valves must be performed only by means of the central control unit. Therefore, no modification to the nozzle openings, switching valves, or the nozzle beams themselves is required.

[0018] According to another advantageous embodiment of the invention, a pneumatically operable directional valve is integrated as a switching valve within the nozzle beam, respectively positioned for at least two chambers or for each of the nozzle openings. This switching valve can be operated from outside the nozzle beam via an electrically insulated pneumatic hose using a control unit. Therefore, the switching valve is protected from the high electrical voltage required for electrostatic coating by applying the device according to the invention. Furthermore, the switching valve is thus implemented as a low-maintenance and safe-operating directional valve, ensuring that it will not fail and requires no maintenance over extended periods. The control valve is operated via a control unit, which can operate individual switching valves individually or collectively, for example, to open or close the entire chamber of the nozzle beam.

[0019] According to an advantageous embodiment of the invention, the nozzle beam of the device has a heating unit for heating the coating agent, particularly in the form of a chamber and / or channel for a heat carrier fluid, which is provided with or through which heated heat carrier fluid flows. For example, the heating unit can be arranged parallel to the chamber for the coating agent, i.e., along the length of the nozzle beam, as an additional chamber also integrated in the nozzle beam. The chamber for the heat carrier fluid can be filled and circulated externally with heated heat carrier fluid via corresponding channels or pipes and a delivery pump. In this way, sufficient heating is ensured for the desired viscosity of the coating agent, which is necessary for electrostatic coating processes and for the fine atomization of oils or other corrosion inhibitors. The heating unit can also be externally disposed and mounted on the nozzle beam as a separate component. Alternatively, the heating unit can also exist in the form of other heating elements that do not have a liquid heat carrier fluid flowing through them.

[0020] According to another advantageous design of the invention, at least one flushing valve is provided for each of the chambers (i.e., at least two chambers), which allows flushing of the respective chambers to be performed even during continuous operation of the coating process, when changing from a coating agent of type A to a coating agent of type B. For example, the flushing valves for this purpose are respectively installed at the ends of the nozzle beam of the device in the longitudinal direction, with corresponding conduits for flushing and cleaning the internal space of the chambers. The internal space of the coating agent chambers is connected to the flushing valves, so that automatic flushing for cleaning the chambers can be performed when changing the type of coating agent (e.g., changing the type of oil in the case of corrosion inhibitors) or for overall cleaning of the device. In this way, cleaning, flushing, and efficient replacement with another coating agent can be performed even during continuous operation. Therefore, the device according to the invention can more flexibly match different types of coating agents and does not require the costly and long downtime of facilities required by prior art when matching each requirement of the substrate to be coated.

[0021] According to another advantageous design of the invention, each of the chambers in the nozzle beam is provided with a plurality of nozzle openings, and each nozzle opening is provided with two associated switching valves. With this measure, each nozzle opening can potentially be coated with the coating agent by either the first chamber or the second chamber of the two chambers. Therefore, the double number of switching valves in the nozzle beam for each nozzle opening provides the possibility of delivering the coating agent from the first chamber or from the second chamber, or, if necessary, from another chamber, for spraying onto the substrate.

[0022] According to another advantageous design of the invention, the switching valve and opening in the nozzle beam are respectively arranged as defined groups in the form of segments for switching on and off. This allows individual areas to be switched on or off. Therefore, the variability in the generation of the coating pattern for the coating agent is further improved.

[0023] According to another advantageous design of the invention, one or more nozzle beams are assembled at an adjustable distance relative to the substrate. By adjusting the height in a direction perpendicular to the surface of the substrate to be coated, larger or smaller lateral spraying areas can be produced. Height adjustment also has the advantage of being able to accommodate different viscosities of the coating agent, for example, when one form of oil requires a closer arrangement to the substrate surface compared to another easier-to-spray coating agent.

[0024] According to another advantageous design of the invention, the flushing valve of the nozzle beam (which is additionally provided at the nozzle beam at least in the number of corresponding chambers) is implemented as a pneumatically controllable directional valve or switching valve, which can be operated by an electrically insulated hose or conduit. This avoids the effects caused by a high-voltage electric field, and the device is less susceptible to effects caused by the atomization method used for the coating agent to be applied. Attached Figure Description

[0025] Further advantages, features, and aspects of the invention will be described in more detail below, in conjunction with the accompanying drawings, in which various embodiments of the invention are illustrated. In the drawings: Figure 1 A schematic cross-sectional view of an embodiment of the device according to the invention is shown, wherein the nozzle beam is located above and below the plate strip; Figure 2 A detailed cross-sectional view of an embodiment of the device according to the invention is shown, wherein the chamber and the switching valve are integrated in the nozzle beam; and Figure 3 A schematic top view of an embodiment of the device according to the invention is shown, having flushing valves for two separate chambers. Detailed Implementation

[0026] According to the embodiment shown in the accompanying drawings, the apparatus 100 for electrostatically applying a liquid, atomized coating agent 1 onto a movable substrate 110 (e.g., a sheet or strip) includes a discharge device 2, which is in the form of nozzle beams 50 or a plurality of nozzle beams 50 arranged side-by-side or placed on the ground opposite to the substrate 110. The nozzle beams 50 are provided with supply lines 41, 42 for the coating agent 1 (see...). Figure 3 In the illustrated embodiment, a coating agent of type A and a different type B are supplied via respective pumps or delivery devices (not shown) to two separate hydraulic chambers 51, 52. That is, the nozzle beam 50 internally has at least two mutually separate chambers 51, 52, which can be controlled by an integrated switching valve 60, which is operated by a signal from the control unit 3 to open or close the nozzle opening 54 respectively for applying the coating agent 1 onto the substrate 110. Figure 1 In this embodiment, the discharge device 2, in the form of a nozzle beam 50, is arranged above and below via a carrier 5 or a suspension device, respectively. For example, the carrier 5 may be in the form of a plastic beam or other non-conductive component, respectively disposed at the end face of the nozzle beam 50. Thus, an electrostatic field can be undisturbedly constructed and maintained constant between the nozzle beam 50 and the substrate 110.

[0027] exist Figure 1 In the first embodiment, nozzle beams 50 are respectively provided above and below the substrate 110 or sheet material as dispensing devices 2 for the coating agent 1, so as to achieve a double-sided coating of the sheet material 110, for example, using oil as a corrosion inhibitor. Here, precise coating thickness and continuous coating shape are crucial to avoid defective or uncoated areas. For this purpose, the device 100 according to the invention has at least one nozzle beam 50 according to the invention, with at least two separate chambers 51, 52 in the nozzle beam 50 and a separate switching valve 60 specifically designed for dispensing different coating agents 1 of type A, B, or C. In this example, the switching valve is implemented as a pneumatic switching valve, which can be controlled by the control unit 3 via pneumatic lines 61 to open or close the connection between the chambers 51, 52 and the dispensing port in the form of a nozzle opening 54 or a slit-like dispensing port of the nozzle beam 50. Other types of switching valves 60 can also be used in this invention.

[0028] exist Figures 1 to 3 The present invention illustrates an embodiment of an apparatus 100 for applying two coating agents 1 to a substrate 110 (e.g., a metal strip or sheet) via supply lines 41 and 42, in order to illustrate the basic structure and components of the apparatus 100 according to the invention.

[0029] According to Figure 1 As shown in the schematic cross-sectional view of one embodiment, the device 100 according to the invention includes at least one nozzle beam 50 mounted on a carrier 5 or other non-conductive member, at least two switching valves 60 integrated therein, at least two mutually separated chambers 51 and 52 for supplying coating agent 1, and a central branch line 53 leading to a nozzle opening 54 of a discharge device 2 located at the tapered end of the nozzle beam 50. The device 100 is preferably used to alternately apply at least two types of coating agents 1, A, B, or C, to a substrate 110 via a pump (not shown) and supply lines 41, 42 (see...). Figure 3 It is permanently present in the two chambers 51 and 52 of the nozzle beam 50. The central branch line 53 leading to the nozzle opening 54 of the nozzle beam 50 can be alternately connected to chamber 51 or 52 by opening and closing the integrated switching valve 60, which can be filled with two different coating agents 1.

[0030] Alternatively, only the same coating agent 1 of type A may be present in both chambers 51 and 52. Due to the high-voltage electric field 70 applied by the high-voltage cable 72, the selected coating agent 1 is finely atomized from the nozzle opening 54 of the discharge device 2 and delivered through the nozzle opening 54 to the surface of the substrate 110. By switching the branch line 53 from one of chambers 51 and 52 to the corresponding other chamber 51, 52 via the switching valve 60 through the control unit 3, a rapid switch from the first type A coating agent 1 to another type B coating agent can be achieved without the need for complete flushing of chambers 51 and 52. In the alternating operation of the two coating agents 1, long downtime of the device 100 and thus the entire facility for sheet metal processing, along with the corresponding costs, is avoided, and the amount of mixed oil produced is minimized, which is far less in the short and narrow branch line 53 than is required by the prior art for complete flushing of large and long chambers 51 or 52.

[0031] according to Figure 2In one embodiment shown in cross-section, the device 100 according to the invention includes at least one nozzle beam 50 and at least two integrated switching valves 60 therein, at least two chambers 51, 52 for supplying coating agent 1, and a central branch line 53 leading to a nozzle opening 54 of a discharge device 2. The device 100 is preferably used to alternately apply two coating agents 1 to a substrate 110, which are persistently present in the two chambers 51 and 52 of the nozzle beam 50 via pumps and supply lines 41, 42. The central branch line 53 leading to the nozzle opening 54 of the nozzle beam 50 can be alternately connected to chambers 51 or 52 by a central control unit 3 through opening and closing the integrated switching valves 60, and the chambers can be filled with two different coating agents 1 of type A or B. Due to an applied high-voltage electric field 70, the selected coating agent 1 is finely atomized from the nozzle opening 54 and delivered to the surface of the substrate 110. By using the switching valve 60 to switch the branch line 53 from one of chambers 51 and 52 to the corresponding other chamber 51, 52, it is possible to quickly switch from one coating agent 1 to another coating agent 1 without having to completely flush chambers 51 and 52.

[0032] The switching valve 60 is pneumatically operated via an electrically insulated hose 61 by a signal from the control unit 3, so that the high-voltage electric field 70 applied via the high-voltage cable 72 does not interfere with the operation of the switching valve 60, and the operation of the switching valve 60 can be automated by externally arranged cost-effective commercially available solenoid valves and control devices, without the need to use expensive high-voltage applicable components in the area of ​​the nozzle beam 50.

[0033] exist Figure 2 In this embodiment, a heated heat carrier fluid circulates in two additional chambers 55 on both sides of the nozzle beam 50. Through symmetrical heating on both sides of the nozzle beam 50, the entire nozzle beam 50 is set to a uniform operating temperature. Thus, the coating agent 1 in chambers 51 and 52 is gently and reliably heated along the entire beam length to a defined viscosity conducive to optimal atomization at the nozzle opening 54. In the illustrated embodiment, chambers 51, 52, and 55 are closed on the sides of the nozzle beam 50 by caps 6 with seals. They can be machined into a two-piece aluminum housing for the nozzle beam 50, similar to the channels for oil.

[0034] according to Figure 3As shown in the schematic top view of one embodiment, the device 100 according to the invention includes at least one nozzle beam 50 with chambers 51, 52 and at least two switching valves 60 integrated therein. The switching valves 60 are arranged in pairs in N sections at the nozzle beam 50, transverse to the advance direction F of the substrate 110 to be coated, as numbered 1 to 40. In the illustrated embodiment, in the first section, switching valve 1 and switching valve 21 are connected to the nozzle opening 54 via a common branch line 53. In this example, switching valve 1 is open, and switching valve 21 is closed. Type A coating agent 1 from chamber 51 reaches the branch line 53 via the open switching valve 1, and from there reaches the substrate 110 via the nozzle opening 54 and a high-voltage electric field 70.

[0035] To replace the Type B coating agent 1 in another chamber 52 located in the nozzle beam 50, switch valve 1 is closed, and then switch valve 21 is opened. After a few seconds, the new Type B coating agent has forced the remaining portion of the Type A coating agent out of the short, thin branch line 53, and at this point only the Type B coating agent 1 flows out of the nozzle opening 54.

[0036] exist Figure 3 In this embodiment, two flushing valves 71 are located at the end of the nozzle beam 50. When the coating agent 1 is changed from type A or B to a third type C coating agent 1, these flushing valves can be used to quickly flush chambers 51 or 52, thereby enabling the rapid replacement of type B coating agent 1 with type C third coating agent 1. Preferably, while coating the substrate 110 with the type A coating agent from chamber 51, the flushing valve 71 at the end of chamber 52 is opened, and the type B coating agent 1 still remaining in chamber 52 is flushed out using the new type C coating agent 1. To replace it with the new type C coating agent 1 now located in chamber 52 of the nozzle beam 50, switching valve 1 is closed, and then switching valve 21 is opened. After a few seconds, the new type C coating agent 1 has forced the remaining portion of the type A coating agent out of the short, thin branch pipe 53, and at this time, the new type C coating agent 1 flows out from the nozzle opening 54.

[0037] Customers of coated sheet materials do not wish for the substrate 110 to have the mixed oil generated in the branch line 53 during replacement. Therefore, the replacement between the two coating agents 1 of type A and type B located in the nozzle beam 50 is preferably performed when the roll length of the substrate 110 to be coated ends and a new roll with a weld to the end of the first roll is guided through. With the present invention, the mixed oil can be forced out from the short, thin branch line 53 and applied from one or more nozzle openings 54 without causing downtime for the entire facility while the end of the last coated roll and the beginning of the uncoated new roll (along with unusable welds) are in the coating chamber of the device 100. Because of the device 100 and, in particular, the flushing valve 71 according to the invention, this is also effective when the coating agent 1 of type B is replaced with the coating agent 1 of type C, since the chamber 52, which is not currently being coated, can be pre-equipped with the new coating agent 1 of type C by flushing during continuous coating operation, without stopping the facility that applies the coating agent 1 of type A from chamber 51 to the substrate 110.

[0038] List of reference numerals 1 Coating agent 2 Discharge equipment 3 Control Unit 4 heating units 5. Carrier 6. Cover 41,42 Supply lines 50 Nozzle Beam Chambers 51 and 52 53 Branch Piping 54. Nozzle opening or discharge slot of discharge device 2 55. The chamber of heating unit 4 for the heat transfer fluid. 60 Switching valve 61 Electrically insulated pneumatic hose for switching valve 70 High-voltage electric field 71 Flushing valve 72 High-voltage cables 100 devices 110 Substrate or sheet material F: Direction of advancement of the substrate or sheet material.

Claims

1. An apparatus (100) for electrostatically applying a liquid, atomized coating agent (1) onto a substrate (110) movable in a propulsion direction F, particularly onto a metal strip or sheet strip to be wound into a roll, comprising a conveying device (2) or pump for supplying the coating agent (1) in a tank or otherwise, a control unit (3) for the application process, and a carrier (5) for holding the discharge device (2) in the form of a nozzle beam (50), wherein, The discharge device (2) is arranged at least above the substrate (110), preferably above and below the substrate (110), and is provided with at least one chamber (51, 52) and a plurality of discharge ports, slots or nozzle openings (54) in the direction toward the substrate (110). The nozzle beam (50) is characterized in that the nozzle beam (50) has at least two hydraulically separated chambers (51, 52), each having a separate supply line (41, 42) for selectively different or the same type of coating agent (1) in the chambers (51, 52), and a dedicated and integrated switching valve (60) is provided in the nozzle beam (50) for each of the chambers (51, 52) for opening / closing the chambers (51, 52) and for connection with the nozzle openings (54) or a set of nozzle openings (54).

2. The apparatus (100) according to claim 1, characterized in that, A central branch pipe (53) is provided in the nozzle beam (50) between the chamber (51, 52) and the nozzle opening (54).

3. The apparatus (100) according to claim 1 or 2, characterized in that, The control unit (3) is configured to operate the control valve (60) individually.

4. The apparatus (100) according to any one of the preceding claims, characterized in that, A pneumatically controllable reversing valve is provided as a switching valve (60), which can be operated from outside the nozzle beam (50) via an electrically insulated pneumatic hose (61) using the control unit (3).

5. The apparatus (100) according to any one of the preceding claims, characterized in that, The nozzle beam (50) has a heating unit (4) for heating the coating agent (1), particularly in the form of a chamber (55) and / or channel for the heat carrier fluid.

6. The apparatus (100) according to any one of the preceding claims, characterized in that, Each of the chambers (51, 52) is provided with a flushing valve (71) so that the chambers (51, 52) can be flushed even during the continuous operation of the coating process when the coating agent (1) is changed from type A to another type B.

7. The apparatus (100) according to any one of the preceding claims, characterized in that, For each of the chambers (51, 52), there are N nozzle openings (54) and for each of the nozzle openings (54), there are two associated switching valves (60).

8. The apparatus (100) according to any one of the preceding claims, characterized in that, The switching valve (60) and the nozzle opening (54) sections are configured as a defined group for switching on and off.

9. The apparatus (100) according to any one of the preceding claims, characterized in that, The one or more nozzle beams (50) are assembled with the substrate (110) at an adjustable distance.

10. The apparatus (100) according to any one of claims 6 to 9, characterized in that, The flushing valve (70) is a pneumatically controllable directional valve or switching valve (71), which can be operated via an electrically insulated hose or pipeline.

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