Device for applying a coating agent onto metal substrates

Abstract

The invention relates to a device (100) for applying a coating agent (11) onto a substrate (5) which can be moved by means of a feed device, in particular for applying a lubricant onto a sheet metal or a continuous metal strip which can be supplied to a forming press or a deep drawing process, comprising at least one spray valve (4), to which the coating agent (11) is permanently provided in a pressurized manner, said coating agent being applied onto the substrate (5) through a nozzle opening (13) and an air cap (14) for atomization purposes. The spray valve (4) is provided with a spray air valve (17) and a nozzle opening (13), the outlet area of which can be changed by a nozzle needle (17) with an adjustable position, and an electric actuator (8) for opening / closing and adjusting the nozzle needle (7) and a position sensor (9) for detecting the current position of the nozzle needle (7) are provided, said actuator and position sensor being connected to a control unit (10) of the spray valve (4) and directly or indirectly to a central controller (3) of the device (100) so as to transmit signals, wherein the actuator (8) has an electric linear drive which adjusts the nozzle needle (7) in a stop-free manner, and the control unit (10) or the central controller (3) is adapted so as to generate, code, and decode a pulse width-modulated coded command signal (1) and / or feedback signal (2) for multiple actuators of the at least one spray valve (4) in order to apply a pre-defined variable amount of coating agent (11) onto the substrate (5) by means of the spray valve (4).

Description

[0001] Amtec Kistler GmbH

[0002] Device for applying a coating agent to metallic substrates

[0003] The invention relates to a device for applying a coating agent to a substrate moving at a constant or variable speed, in particular for applying a lubricant to a movable sheet metal that can be fed to a forming press.

[0004] In the production of deep-drawn blanks, it is known to coat the sheet metal with a defined layer thickness of a lubricant prior to the deep-drawing process in order to achieve high part quality. For this purpose, such known devices employ several spray valves arranged in rows above and / or below the substrate to be coated. These spray valves can be used to apply pre-programmed amounts of a lubricant as a coating to the top surface and, if necessary, the underside of the substrate, either over the entire surface or in specific sections at specific positions.

[0005] Such devices are described, for example, in DE 10 2020 116 668 A1 and DE 102 16 631 B4. To adjust the desired application rate of the coating agent, the nozzle needles of the spray valves are pneumatically opened against an electrically adjustable stop at the rear end, which is specified by a higher-level control system. This requires at least three control signals.A first signal for the electrical adjustment of the stop for the opening position of the nozzle needle of the spray valve, with which the desired quantity is specified, a second signal for the pneumatic opening of the nozzle needle from the closed position to the preset stop position, with which the desired position of the coating surface on the substrate to be coated is specified, and a third signal for switching on the spray air via a solenoid valve, with which the coating agent is then transported from the spray nozzle to the substrate to be coated and atomized over the entire surface.With increasing feed speed of the metal sheet or substrate, the minimum lengths of the areas to be coated in the transport direction become increasingly longer in the known systems with pneumatic opening of the needle of the spray valves, because the opening speed of the nozzle needle is limited by the series connection of an electro-pneumatic valve and the pneumatic piston actuation.

[0006] In addition, with the increasing number of spray valves, the communication effort between a central system control and the individual spray valves increases due to the separate control signals or commands for adjusting the various necessary actuators, such as the desired stop position of the nozzle needles depending on the degree of opening, the pneumatic opening and closing of the nozzle needles at the desired coating surfaces of the substrate, and the switching of the spray air on and off. All of this makes these known systems technically complex and therefore cost-intensive.

[0007] Furthermore, the adjustment devices in the stop elements, as well as the nozzles and needles, have a relatively limited service life due to mechanical wear during pneumatic opening and closing against hard stop points, and often result in high maintenance costs during operation. Furthermore, these mechanically adjustable stops, from nozzle needles to cam elements, etc., require a relatively large number of individual parts to assemble and adjust.

[0008] Against this background, the object of the present invention is to improve a device of the type mentioned at the outset in such a way that a reduction in manufacturing costs, an increase in the adjustment speed of the nozzle needle of spray valves for coating agents and an increase in the reliability and service life of such devices are achieved at the same time.

[0009] This object is achieved by a device having the features of claim 1. Advantageous embodiments and further developments of the invention are defined in the dependent claims. According to the invention, a device for applying a coating agent to a substrate movable by a feed device, in particular a lubricant to a metal sheet or continuous metal strip that can be fed to a forming press or a deep-drawing process, is proposed, comprising at least one spray valve, usually a plurality of spray valves, to which the coating agent is permanently applied under pressure and can be applied to the substrate through a nozzle opening and an air cap for atomization, wherein the spray valve is provided with a spray air valve and with a nozzle opening that can be changed in an outlet surface by means of a nozzle needle whose position is adjustable.wherein an electric actuator is provided for opening / closing and for adjusting the nozzle needle, as well as a position sensor for detecting the current position of the nozzle needle, wherein both the actuator and the position sensor are both signal-connected to a control unit of the spray valve and directly or indirectly to a central control of the device as a whole, wherein the device is characterized in that the actuator has an electric linear drive that adjusts the nozzle needle without stop, and that the control unit or the central control is adapted to generate, encode, and decode a pulse-width-modulated coded command signal and / or feedback signal for a plurality of actuators of the at least one spray valve for applying a predefined, variable amount of coating agent through the spray valve onto the substrate.

[0010] According to the invention, a combination of a rapidly adjustable electric actuator as a linear drive for positioning and opening / closing the nozzle needle and a specific control unit is provided, in which a pulse-width modulated coded signal with a digital command code can be generated and processed jointly for several actuators of the spray valves. Such a command signal, also referred to as a pulse-width coded PWM signal, has the advantage that the device's control system can react very quickly to different requirements in the spray pattern of the coating agent.The control is carried out by the central system control via a quasi-digital, quickly transmitted common command signal for several actuators of the spray valve simultaneously, namely in particular for, for example, opening the spray air valve for atomizing the coating agent and for adjusting and positioning the nozzle needle, which can change the outlet opening in the surface according to the respective requirements. With these measures and in combination with the position sensor, which determines the current position of the nozzle needle and feeds it back to the control unit, very fast reaction times of the spray valve can be achieved with relatively simple and inexpensive measures. This significantly reduces the amount of required components in the structure and design of the device - even when using a large number of individual spray valves in a system.

[0011] With the described inventive measures, namely the rapidly controllable electric linear drive as the actuator of the nozzle needle and the pulse-width-modulated common signal for the control unit for controlling the spray valve, the effort required for communication between the central system control and the control unit of the spray valves themselves, which are provided in a number of up to 100 spray valves across the width of a substrate to be processed, is significantly reduced. At the same time, a much higher reaction speed of the multiple spray valves can be achieved. This allows for a much faster response to desired changes in the coating quantity on the substrate or changes that are necessary due to errors than previously possible with the nozzle needles of spray valves that were mechanically activated and pneumatically controlled against a stop in previously known systems.Electronically controlled rapid opening and, if necessary, gentle closing of the nozzle needles of the spray valves also prevents the nozzle needle from hitting previously necessary mechanical end stops, such as cams or similar, thus reducing overall wear in the spray valves to a minimum. The device according to the invention is thus relatively durable and requires little maintenance, without any disadvantages in the speed and quality of coating substrates or in the complexity of the design.

[0012] In this way, and in particular through the use of pulse-width-modulated command signals and / or feedback signals in the spray valve control unit, a technically new and very fast transmission of necessary signals from a central system control to the spray valve itself is possible. The information required for the various actuators and the information regarding the timing of the switching point for the nozzle needle actuators in the spray valve, as well as for switching the spray air on or off for atomizing the coating agent in the desired amount to be applied to the substrate, can be transmitted via a quasi-digital central signal. Thus, all necessary information from the various actuators, as well as the exchange between the position sensor for the nozzle needle, etc., is contained in a common, pulse-width-modulated signal.The signal is transmitted in coded form from the spray valve to the system control system and then transmitted back. This allows for rapid activation and rapid opening and closing of the spray valve with far greater flexibility than previously possible with such devices.

[0013] For the physical transmission of the pulse-width-modulated digital command signal or the feedback signal between a central system controller and the control unit of the spray valve itself, various designs with digital outputs / digital inputs on the controllers and corresponding combined cabling for the control signals can be provided. Coding them into a single PWM signal eliminates the need to provide separate connection elements and connecting lines outside the spray valves for controlling the nozzle needle, as is the case with conventional spray valves, and for opening and closing the compressed air valve for the spray air.With the solution according to the invention, the spray valves are also significantly simplified in terms of design and thus more cost-effective despite high efficiency and, in particular, increased speed in the reaction to different desired spray profiles on the substrate.

[0014] According to an advantageous embodiment of the invention, a single-phase or multi-phase electric linear drive, a voice coil actuator, or a piezo actuator is provided as the electric, stopless actuator for the nozzle needle of the spray valve according to the invention, which can be controlled by a control unit based on the pulse-width modulated command signal. The control unit itself can be directly integrated into the spray valve itself, for example, in its housing. Alternatively, the control unit can also be provided separately from the spray valve with a corresponding connection to the actuators of the spray valve and a digital output for the connection to the system control. By means of such a form of stopless actuator, ieBy using an actuator that is not mechanically adjusted via a rear cam stop or similar device, for example, using compressed air, the speed of the spraying process and the response options are significantly increased. The nozzle needle is essentially a quickly controllable electric linear drive, which also exhibits no signs of wear due to a hard mechanical stop or similar device. With a possible soft control at the end during the closing process, further advantages can be achieved with such a multi-phase electric linear drive, voice coil drive, or piezo actuator according to the invention.

[0015] According to a further advantageous embodiment of the invention, the pulse-width-modulated command signal and / or feedback signal generated and processed by the central system control or in the control unit is a combined, uniform signal adapted for controlling multiple actuators of the spray valve, in particular for controlling signals for the nozzle needle or the actuator with regard to their closing / opening degree, for the spray air valve for ejecting the coating agent, and the respective temporal sequence of these, in particular in relation to the advance of the substrate. With these two control variables alone, the various variable spray profiles can be quickly and directly controlled, adapted, and modified according to the needs of individual spray valves, with comparatively little design effort and thus reduced costs.The combined use of a uniform, common coded PWM signal also has the advantage that precise timing and timing can be achieved digitally for the various control processes in the spray valve. A digital feedback signal for the central system control can also be generated in this way using coded pulse-width modulated signals in the same control unit, which is adapted either in terms of programming or hardware to convert analog signals into digital signals for the PWM command signals and PWM feedback signals.This also makes it easy to integrate other required signals, such as those from the position sensor, so that only a single digital output / input on the spray valve control unit and a digital input / output on the central control unit with the appropriate cabling are required to transmit the various actuators and control instructions to the spray valve. Closed-loop control is thus also possible according to the invention, since the respective command signals are also processed as feedback signals in the central system control unit and the control unit, with decoding and encoding into a pulse-width modulated signal.

[0016] According to a further advantageous embodiment of the invention, the control unit of each of the spray valves is signal-connected to a central system controller via a dedicated digital output and digital input with a uniform cable connection. In this way, each of the spray valves, which are usually installed in large numbers in a system, can be connected to the system controller via a cable connection using a conventional digital cable. The coded signals, which are pulse-width modulated for the command signal and the feedback signal, are simply transmitted between the system controller and its digital input or digital output to the control unit of the spray valve using a single cable. The control unit in the spray valve itself has a corresponding module for encoding, decoding, and processing the pulse-width modulated signal.In this way, a highly effective control system for controlling the various actuators in the spray valve can be provided using relatively simple components.

[0017] According to a further advantageous embodiment of the invention, a common cable with combined, consolidated connections for the signal transmission of the command signal, feedback signal, and power supply of the spray valve is provided for each spray valve for connection to the control unit and / or the system control. The at least three components described in this way are transmitted in the form of a pulse-width-modulated signal between the system control and the control unit and are broken down into the individual required components via corresponding modules in the control unit of the spray valve, so that the individual control elements—namely, the nozzle needle of the spray valve, the spray air valve, and the actuator—for adjusting the nozzle needle can be controlled quickly and directly.

[0018] According to a further advantageous embodiment of the invention, an electronic position controller for rapidly controlling the nozzle needle actuator, as well as a coding unit and a decoding unit for converting the digital, pulse-width-modulated signal into analog signals and vice versa, are provided in the spray valve control unit. The spray valve control unit thus has special modules implemented either in programmatic or hardware form, which serve as a coding unit and a decoding unit for converting the digital signals into analog signals and vice versa. The control unit preferably has corresponding program-based modules specifically designed to generate command signals and feedback signals for the various components and actuators of the spray valves. The programmed form of the coding unit, etc.has the advantage that the several necessary individual signals can be transmitted together and combined as PWM signals and yet are quickly and effectively provided for control in the spray valve itself by its specially adapted control unit.

[0019] According to a further advantageous embodiment of the invention, a memory module is provided in the control unit for storing information, in particular deviations, with regard to target and actual values ​​in the coating process, in particular for storing information with regard to the opening and duration of the opening of a spray valve. With such a memory module, the control and regulation of the spray valve can be further optimized. The correct function of the valve can thus be monitored and documented, as can the extent of the nozzle needle opening. Using this method, errors in the hardware of the spray valve can also be easily detected and corrected via appropriately corrected control for the desired, predefined spray field with the coating agent on the substrate.

[0020] According to a further advantageous embodiment of the invention, the control unit is adapted to regulate the opening duration and opening position of the nozzle needle for a uniform or varying spray pattern of coating agent on the substrate. By quasi-targeted control of the nozzle needle with the control unit via the actuator and based on information from the nozzle needle position sensor, a very precise and rapid opening, closing, and adjustment of the spray valves can be achieved. The control unit is optimally configured for the rapid and precise control of the respective desired degree of opening and, thanks to the combination of the pulse-width-modulated control signals and the fast-reacting electrical actuators of the nozzle needle, reacts accordingly quickly to the desired requirements.The control with the control unit can be implemented in a closed control loop or in an open control loop, depending on the requirements profile of the user of the device.

[0021] According to a further advantageous embodiment of the invention, an adjusting device is provided for adjusting the position of the spray valve relative to the substrate, in particular for adjusting the distance of the spray valve from the surface of the substrate or the lateral position in the width direction of the substrate. In this way, the device can be easily adapted to different conditions. For wider or narrower shapes of metal sheets or metal strips, for example, the device can be used to adjust the position of the spray valve. The adjusting device can have any form known in the field. In particular, electromotive adjusting devices or manual spindle units are used, which enable precise and exact positioning and adjustment with a secure end position of the spray valve.

[0022] According to a further advantageous embodiment of the invention, the control unit is provided with a soft-close function for the nozzle needle, with which a closing speed that is specifically reduced compared to the normal adjustment speed is set shortly before the spray valve is fully closed and the nozzle needle comes into contact with a nozzle seat. Such a soft-close function can, for example, be provided in the control unit of the spray valve in the form of a software-based solution, in which approaching the end position of the nozzle needle, which is stored in the control unit, leads to a then lower speed in the adjustment via the nozzle needle actuator. In other words, compared to the normally very fast adjustment movement, the nozzle needle's closing speed is specifically reduced only in the final phase before it comes into contact with a valve seat or nozzle seat, and thus approached gently.The advantage of this measure is that even when the spray valve is fully closed, the nozzle needle is not forced against the nozzle seat, which could result in mechanical wear. This allows for a longer service life without major maintenance requirements for the device as a whole. Wear caused by mechanically impacting the nozzle needle within the spray valve is effectively avoided. The device has a longer maintenance-free service life and requires less maintenance than previously known devices of this type with stops for the nozzle needle in the form of adjustable camshafts or similar devices.

[0023] According to a further advantageous embodiment of the invention, an encoder, a Hall sensor, or a potentiometer is provided as a position sensor for the nozzle needle in the spray valve. The position sensors thus formed are connected to the control unit of the spray valve via a signal line, whereby the position information can also be converted into a pulse-width-modulated, coded signal and processed in the control unit. The information regarding the exact positioning of the nozzle needle is thus transmitted directly and very quickly to the central system control system, enabling appropriate response to deviations in the position of the nozzle needle, etc.

[0024] According to a further advantageous embodiment of the invention, an electronic position controller is provided in the spray valve control unit for fast, direct control of the nozzle needle actuator and for generating amplitude modulation of the nozzle needle stroke. The position controller in the spray valve control unit receives an electrical actual value signal from the nozzle needle position sensor in the spray valve, compares this actual value signal with the target value of the needle stroke from the pulse-width-coded default value from the system control, and varies the current or voltage for the nozzle needle actuator to immediately adjust the actual value of the needle stroke to the target value. This measure allows the nozzle needle actuator to be quickly controlled electronically without the need for additional devices or components between the control unit and the actuator.This also enables connection via standardized control lines, eliminating the need for a multitude of individual connections with the associated complexity of cabling and connecting lines, etc. This ensures rapid control of the nozzle needle for rapid response and variation of the spray pattern in the control of the spray valve(s). This enables uniform application of the coating agent to the substrate, either in a uniform, consistent pattern across the entire width and length of the substrate despite the feed movement, or in a desired, varying form of a spray profile that is stored in advance in the system control system or control unit, or can be set by a user of the device.

[0025] The amplitude modulation of the position of the spray valve's nozzle needle by the position controller in the control unit is so fast that, thanks to the integration across the length of the spray jet, a gap-free and uniform coating of the passing substrates or metal sheets is achieved on the substrate to be coated, even at feed speeds of at least 180 m / min. This overall increases the part quality of metal parts formed in deep drawing processes, for example.

[0026] Further advantages, features, and aspects of the present invention will be described in more detail below with reference to the accompanying drawings, in which several embodiments of the invention are shown. In the drawings:

[0027] Fig. 1 is a schematic view of a first embodiment of a device according to the invention with a control unit integrated into the spray valve; Fig. 2 is a schematic view of a second embodiment of a device according to the invention for applying a coating agent with a control unit separate from the spray valve;

[0028] Fig. 3 is a schematic flow diagram of an embodiment of a pulse width modulated digital command signal for use in a control unit of a device according to the invention in a spray valve;

[0029] Fig. 4 is a schematic flow diagram of an embodiment of a pulse-width modulated digital feedback signal according to the invention for use in a control unit of a spray valve of a device according to the invention; and

[0030] Fig. 5 is a schematic flow diagram of a signal processing in the control unit of the spray valve according to the invention according to an embodiment for illustrating error handling via pulse width modulated digital signals.

[0031] In Fig. 1 and Fig. 2 two embodiments of a device 100 according to the invention for applying a coating agent 11 to a substrate 5, for example a metal strip or a metal sheet, are shown in schematic representations to illustrate the structure and the components of the devices 100 according to the invention, while Figs. 3 to 5 illustrate exemplary forms of pulse-width modulated signals and the processing of the signals for controlling the spray valve 4, a feedback in the sense of a feedback signal to the system control 3 or control unit 10 of the spray valve and a possible error handling as flow charts.

[0032] According to the first embodiment shown in Fig. 1, the device 100 according to the invention comprises a spray valve 4, a control unit 10 integrated therein, a fast electric actuator 8 for actuating a nozzle needle 7, and a central system controller 3, which is signal-connected to the control unit 10 of the spray valve 4. The device 100 serves to apply a coating agent 11, which is permanently present at an inlet of a housing of the nozzle 6 of the spray valve 4, to a substrate 5. The nozzle needle 7 can be closed against a nozzle seat 13 via the actuator 8 and can be varied in its open position in different stroke positions in order to vary an annular gap at the end of the nozzle 6 of the spray valve 4.A spray air valve 17 supplied with spray air 16 (compressed air) causes a type of atomization of the coating agent 11 via an annular gap 15 in such a way that a desired amount and defined area of ​​a surface of the substrate 5 can be provided with the coating agent 11.

[0033] The substrate 5 to be coated with coating agent 11 can be either a single metal sheet or a continuous metal strip, which is guided in a feed direction V at a feed speed below the nozzle 6 of the spray valve 4. In reality, a system with such a device 100 is provided with a plurality of spray valves 4, which, depending on the application, can comprise several tens or even hundreds of individual spray valves 4. The central control of the spraying process is carried out via a system controller 3, which, according to the invention, is connected to the control unit 10 of the spray valve 4 via a special signaling coupling and digital data line.The system controller 3 supplies a command signal 1 to the control unit 10 and receives from it a feedback signal 2 according to this embodiment, wherein both signals are transmitted centrally in the form of a pulse-width modulated coded signal via a uniform, combined signal line and digital outputs / inputs.

[0034] For the use of a pulse-width modulated coded signal as command signal 1 or feedback signal 2, a coding unit 10.2 and a decoding unit 10.3 are provided in the control unit 10 according to the embodiment of the invention shown in Fig. 1, in which corresponding analog signals can be generated or corresponding digital signals for the control unit can be reconstructed from the digital signals of the PWM signal. To control the electrical, rapidly movable actuator 8, an electronic position controller 10.1 is present in the control unit 10, which enables direct and rapid control of the actuator 8. Furthermore, the control unit 10 in this embodiment shown in Fig. 1 also has a memory module 10.4, in which, in particular, predetermined spray profiles or error messages or position signals of the nozzle needle 7 from the position sensor 9 are stored.The nozzle 6 itself of the spray valve 4 comprises a central housing with a valve chamber 12, into which the connection for the permanently present coating agent 11 opens and in which the nozzle needle 7 is arranged so as to be movable by the actuator 8 according to the stroke illustrated by the double arrow. In this exemplary embodiment, the nozzle needle 7 is conically tapered at its lower end, and a correspondingly conically shaped nozzle opening 13 is provided at the lower end of the nozzle 6, in which opening the nozzle needle 7 sits in a form-fitting manner when the spray valve 4 is closed. At the lower end of the nozzle 6, there is also an annular gap 15 in an air cap 14, into which compressed air can be introduced as spray air 16 via the spray air valve 17 to atomize the coating agent 11. As indicated by the dotted arrows in Fig. 1, with the nozzle 6 open, ie the nozzle needle 7 raised upwards as shown in Fig.1, the coating agent 11 is atomized and applied in a defined form to the surface of the substrate 5, which is moved underneath in the feed direction V.

[0035] The device 100 according to the invention thus formed enables a very precise, fast, and cost-effective application of a coating agent 11 to substrates 5. The combination of a rapidly controllable electric actuator 8 for adjusting and opening or closing the nozzle needle 7 via the electronic position controller 10.1 and the use of a special digital signal for communication between the system controller 3 and the control unit 10 achieves significant technical and economic advantages for such devices 100 for spraying coating agents 11 such as oil coatings. Communication between the central system controller 3 and the spray valves 4, which are generally provided in large numbers in such systems, requires significantly fewer components and connections than before, and the reaction speed for controlling the spray valves 4 is also reduced.Desired changes or adjustments to a predefined spray profile with the desired coating quantity on the substrate 5 can be set and controlled quickly and effectively. Furthermore, with such a device 100 according to the invention, a relatively smooth opening and closing of the spray valves 4 can be achieved by easily setting a type of reduced speed shortly before the nozzle needle 7 reaches its closed position. In previously known devices of this type, mechanical stop elements such as adjustable cams at the rear end, as well as the rapid closing movement of the nozzle needle 7, frequently caused damage and premature inoperability of the device 100.

[0036] In the pulse-width-modulated coded signals between the system controller 3 and the control unit 10 of the spray valve 4, several pieces of signal information for the necessary control and regulation of the spray valve 4 are advantageously combined and summarized in a coded digital signal. For cost-efficient transmission of the command signal 1 and also, if required, a feedback signal 2, the required information about, for example, the timing of the next switching point of the spray valve 4, the switching on or off of the spray air 16 via the valve 17 for atomizing the coating agent 11, and / or the desired position or stroke of the opening position of the nozzle needle 7, with which the application quantity is specified, can be controlled by the central system controller 3 in a single pulse-width-modulated digital command signal 1. This command signal 1 is then transmitted to the control unit 10 of the spray valve 4 via the coding unit 10.2 is converted back into its components in order to effect the targeted control of, for example, the electrical, fast-reacting actuator 8 for the nozzle needle 7 via the electronic position controller 10.1. At the same time, the decoded signals are used to control the spray air 16 via the valve 17 and the timing of the respective actuators with the control unit 10 according to the specifications from the system control 3.

[0037] As an electric actuator 8 according to the invention for the rapid and impact-free actuation of the nozzle needle 7 according to the invention, for example, a single-phase or multi-phase electric linear drive, a voice coil actuator, or a piezo actuator can be used. According to the invention, all of these variants of an actuator 8 are controlled via the fast-reacting electronic position controller 10.1 from the control unit 10 using the command signal 1 coming from the system controller 3, which is delivered according to the invention as a specific digital signal, namely as a pulse-width-modulated signal with a combined, uniform summary of several manipulated variables for the actuators of the spray valve 4. According to the invention, an encoder, a Hall sensor, or a potentiometer, for example, can be used as a position sensor 9 in the embodiment of the device 100 according to Fig. 1.

[0038] The novel spray valve 4 according to the invention provides a type of dual-fluid nozzle in which the transport of a permanently present coating agent 1 is initiated at the valve chamber 12 and expelled to the substrate 5 to be coated by means of the spray air 16 at the lower end. The spray air 16, which can consist of compressed air or another carrier gas mixture, essentially atomizes the coating agent 11 in the annular gap 15 of the air cap 14 as soon as the nozzle needle 7 is raised from the nozzle seat 13 by the actuator 8. The strength of the stroke of the nozzle needle 7 and the time of opening and closing of the spray valve 4 are realized by the very fast-acting electronic position controller 10.1 on the part of the control unit 10 and by the stopless electric actuator 8.The coating agent 11 then emerging from the nozzle seat 13 is atomized and applied in the form of droplets via additional lateral bores in the air cap 14 onto the coated substrate 5 below the spray valve 4. The thickness and shape of the coating by means of one of the spray valves 4 depends on the position of the spray valve 4 relative to the substrate 5, which is conveyed past it at the feed rate V. The device 100 can have an adjusting device (not shown in Fig. 1) with which the position and distance of the nozzle 6 or the spray valve 4 relative to the substrate 5 conveyed past it can be adjusted.

[0039] According to the embodiment shown in Fig. 1, the control unit 10 is integrated into the spray valve 4. Alternatively, as shown in Fig. 2 in the second embodiment, the control unit 10 can also be provided separately in a separate part of the device 100. In both variants, the signal transmission of the digital signal between the system controller 3 and the control unit 10 is realized via conventional digital outputs and digital inputs as well as data transmission cables, so that separate cabling, lines, etc. for the individual control of the actuators of the spray valve 4 are no longer required according to the invention. In both cases of the first and second embodiments according to Fig. 1 and Fig. 2, fast control by the actuator 8 and the electronic position controller 10.1 is also possible for rapid response to different spray profiles.The nozzle needle 7 is actuated very quickly, almost simultaneously, with the other actuators of the spray valve 4, namely the opening of the valve 17 for the spray air 16. For this purpose, the control unit 10 according to the invention advantageously has an optional memory module 10.4 in both cases, via which the feedback signals 2, position signals from the sensor 9, and opening states of the nozzle needle 7 can be stored and retrieved. Predefined spray profiles for applying the coating agent 11 to the substrate 5 can also be stored in the memory module 10.4, so that they can then be retrieved as needed for specific applications.

[0040] Possible embodiments of pulse-width-modulated coded signals for the command signal 1 and an (optional) feedback signal 2, as well as error correction, are shown in flowcharts in the further illustrations of Figs. 3 to 5. These pulse-width-modulated signals of the command signal 1 and the feedback signal 2 (hereinafter also referred to as PWM signals) are an example of an embodiment of the invention for use in the control unit 10 of the device 100 according to the invention, as shown in the two previous Figs. 1 and 2.

[0041] A command signal 1 can, for example, be used to control several actuators of the control unit 10 of the device 100 according to the invention via the central system control 3 in the following form: The combined, uniform command signal 1 comprises, for example, the required information in digital form about the timing of the next switching point of the spray valve 4 of the plurality of the several spray valves 4 provided in a system, the switching on or off of the spray air via the spray air valve 16 for atomizing the coating agent 11 and, as a third piece of information, for example the desired position of the nozzle needle 7 of the spray valve 4, which is set with the actuator 8 and is permanently detected by the position sensor 9 (cf. Fig. 1 and Fig. 2 above).These three different pieces of information from the control of the spray air valve 4 are transmitted from the central system controller 3 to the control unit 10 in the form of a pulse-width modulated command signal (PWM signal) 1, whereby they are encoded or decoded into a digital signal with the corresponding information content. In this way, the individual components of the information required to control the various actuators of the spray valve 4 can be transmitted centrally between the system controller 3 and the control unit 10 using a simple, single digital output and a digital input.

[0042] The physical transmission of the command signal 1 and the corresponding feedback signal 2 between the system controller 3 and the control unit 10 of the spray valve 4 is thus carried out according to this exemplary embodiment using commercially available digital connections (digital inputs / digital outputs) on the controllers 3, 10 and corresponding digital signal cables. Coding and decoding of the digital, pulse-width-modulated command signal 1 and / or feedback signal 2 is carried out in this exemplary embodiment on a software basis via corresponding modules 10.2, 10.3 in the control unit 10: By a suitable selection of a PWM basic clock (also referred to as "duty cycle") and the bit timing according to the attached representation of the temporal sequence of an example of a command signal 1 according to Fig.1 In such a pulse-width modulated digital command signal 1, the speed of the command transmission to the actuators of the spray valve 4 as well as the digital resolution of the desired position of the nozzle needle 7 of the spray valve 4 from 1 to N values ​​in a relatively wide range can be adapted to the requirements of the respective coating process with coating agent 11 according to the example of the device 100.

[0043] Fig. 3 shows a variant with N = 4 for illustration purposes. Depending on the application, other values ​​for N are also possible and useful for spray profiles on the substrate 5. The circuits of the actuators of the spray valve 4 in the temporal sequence in Fig. 3 are implemented between a high state (e.g. 24 V) and a low state (e.g. 0 V) ​​of a PLC output module with 24 VDC to a microcontroller in the control unit 10 of the spray valve 4. The PWM basic clock (duty cycle) can be, for example, 8 ms, while the initial trigger clock signal T (or bit timing) can be, for example, 1 ms. After the trigger clock signal T, the valve 17 for the spray air 16 is switched on under S (spray air switch on). Commands 1, 2, 3 and 4 in Fig.3 correspond to different application quantities 1 to 4 within the PWM basic cycle, namely in this example an application quantity between 25% (command 1), 50% (command 2), 75% (command 3), and 100% (command 4). The nozzle needle 7 is raised from the valve seat 13 by different needle strokes, thus opening the spray valve 4 to different degrees (see Fig. 1 and Fig. 2 above). Depending on the setting in the control unit 10 or the position controller 10.1 as a microcontroller in the control unit 10, the spray valve 4 is opened more or less strongly in the respective cycles of the PWM basic cycle and then closed again. In the first opening range according to Fig. 3, command 4 is given with an opening of 100% of the spray valve 4, in the second PWM basic cycle then with an opening according to command 1 (= 25%) etc. When command signal 1 is terminated according to Fig.3, the spray air valve 17 is then controlled accordingly to close again, and the coating process is completed. R denotes a reset, while P according to Fig. 3 represents a pause for reliable detection of a rising edge of the carrier clock signal. In a corresponding manner, different spray patterns can be realized for each of the spray valves 4 used in a system via the system control 3 according to the device 100 according to the invention. The clocking can be carried out, for example, at 125 Hz, and the values ​​for controlling the microcontroller with 24 V or 0 V (high and low) are also only examples.Other values ​​and forms of a PWM signal for the command signal 1 can be used within the scope of the present invention, as defined in the appended claims, in order to realize a fast and effective, but at the same time cost-efficient device 100 for uniformly applying coating agent 11 to substrates 5 with corresponding digital PWM control.

[0044] By cyclically varying the quantity specification by the system control 3 by means of the control unit 10 of the spray valves 4 in the pattern A - B - A - B, more than ten different application quantities on the substrate 5 to be coated can be realized in a surprisingly simple manner in the variant shown in Fig. 3 with N = 4 without gaps in the spray pattern.

[0045] Fig. 4 shows, by way of example, a flowchart of a feedback signal 2 for use in an embodiment of the present invention of a device 100 (cf. Fig. 1 and Fig. 2). In the feedback signal 2 according to Fig. 4, after the first PWM basic clock of the command signal 1, the trigger clock signal T and an acknowledgment or acknowledgment A are switched (high in the lower time slot). This confirms that the first PWM basic clock of the command signal after T acts as the trigger clock signal and that the received command has essentially been accepted. At the subsequent switching points according to the trigger, a feedback signal is generated in real time, as shown in Fig. 4, in parallel with the generation of the command signal 1. It is transmitted via the position sensor 9 of the spray valve 4 and the control unit 10 and the encoder 10.3 or decoder 10.2 checks the actual position of a stroke of the nozzle needle 7 and returns it as feedback to the system controller 3 in the form of a PWM signal as feedback signal 2 analogous to the command signal (see Fig. 1 and Fig. 2 above). In the example shown in Fig. 4, an error occurred after the third PWM basic clock pulse because the control of the spray valve 4 with the command 3 of quantity 1 was incorrect. The system controller 3 thus receives direct and real-time feedback of an incorrect generation of a spray pattern of coating agent 11 with the device 100. After the end of the last PWM basic clock pulse of the command signal 1, the feedback signal 2 is also ended again with a basic clock offset (switching from high (24 V) to low (0 V) of the microcontroller on the PLC output module of the control unit 10).In this way, a direct feedback of the spraying processes actually carried out is provided to the spray valves 4 of a device 100, which can be used to adapt the control of the control unit 10 or to correct faulty parts within the device 100.

[0046] The further procedure in the event of such an error in the control unit 10 for controlling the various spray valves 4 of the device 100 for applying coating agent 11 according to the invention is illustrated in the timing diagram according to Fig. 5. The upper timeline illustrates the digital switching between high (24 V) and low (0 V) of the command signal 1, corresponding to the previous example in Fig. 3. After completion of a coating process, according to the lower timeline, after the first PWM basic clock pulse, the spray air valve 17 of the spray air 16 is switched off, and the error is retrieved to initiate a reset in the third PWM basic clock pulse. The various error codes 1, 2, 4, 8, etc. are forwarded as binary coding to the system control 3 by the control unit 10 with the coding device 10.2, where they are used to read out and evaluate the control of the device 100 and, if necessary, to counteract the control of the device 100.Errors can also be handled promptly and virtually in real time according to the invention using feedback signal 2 in the pulse-width-modulated digital form of the signal. This largely prevents incorrect application of the coating agent 11. The system control system 3 of the device 100 can react directly and immediately to errors that occur or, with appropriate control by a user, can be adjusted after error messages are displayed.

[0047] The device 100 according to the invention thus provides a very fast-acting and highly efficient coating device for such applications, wherein different spray profiles of coating agent 11 as well as a uniform and evenly distributed coating can be applied to the substrates 5. Through the combined use of, on the one hand, rapidly controllable electrical actuators 8 for the nozzle needle 7 and, on the other hand, a specific conversion of the necessary signals and information into a pulse-width-modulated command signal 1 or feedback signal 2, the invention allows for a significantly improved device 100 compared to such devices known in the prior art.Only relatively inexpensive digital inputs and digital outputs in the system controller 3 and in the control unit 10 of the device 100 as well as corresponding digital signal lines are required in order to convert the various and diverse types of information into a uniform, combined signal 1, 2.

[0048] The generation, coding and decoding of the various information in the control unit 10 according to the invention takes place, for example, via hardware-related or preferably via program-based modules, such as a coding module 10.2 and a decoding module 10.3 according to Fig. 1 and Fig. 2.

[0049] By means of the virtually freely programmable combination in the control unit 10 of, for example, relatively small stroke amplitudes of the nozzle needle 7 with small values ​​of the change in the position of the nozzle needle according to 1 to N and correspondingly variable opening duration or timing of the nozzle needle, a very precise, yet relatively low exclusion rate of coating agent 11 at the various spray valves 4 can be set, while simultaneously maintaining a very fast PWM basic clock or "duty cycle." This is not possible with nozzle needles 7 of known devices of this type that are pneumatically opened constantly against a mechanical stop (e.g., adjustable cams).With the present device 100 according to the invention, however, an equal amount of coating agent 11 per square meter can be applied very precisely even at very low feed speeds V of the substrate 5 to be coated, as is also possible at relatively high feed speeds V of the substrate 5. Such a device 100 is particularly advantageous with a coil of metal strip as the substrate 5, which is fed, for example, to a deep-drawing press for a deep-drawing process by a predetermined cycle feed with a variable feed speed V, or also in a steelworks before winding, when such a metal strip as the substrate 5 must be provided with a corrosion protection medium as the coating agent 11.

[0050] By simultaneously varying the stroke amplitude of the nozzle needle 7 of the spray valve 4 in the rapid and effective manner according to the invention and by changing the opening duration of the spray valve 4, a virtually identical amount of coating agent 11 per square meter can be applied uniformly and without errors from a standstill up to the maximum feed speed V of the substrate 5 in the feed cycle. By very quickly opening and closing the nozzle needle 7 via the electrical actuators 8 according to the invention in combination with the high amplitude modulation of the needle stroke generated via the pulse-width modulated command signal 2, the present invention thus ensures a uniform layer thickness of the coating agent 11 with a uniform droplet distribution at all times, even with a variable feed speed V of the substrate 5 to be coated.

[0051] With the device 100 according to the invention, it is thus also possible to move the nozzle needle 7 of the spray valve 4 very quickly into a constantly open nozzle needle position 1 to N (corresponding, for example, to an application of 25%, 50%, 75%, or 100%) and to hold it in this desired opening position with the electronic position controller 10.1 of the control unit 10 until the next travel command. The device according to the invention also enables a very effective combination of rapid timing of the actuators 8 of the nozzle needle 7 with simultaneous amplitude modulation (opening degree of the spray valve 4) for low feed speeds of the substrate 5 and permanently open operation in various positions of the nozzle needle 7 for higher feed speeds with the present invention, while maintaining a consistently high quality and uniformity of the coating result.With the device 100 according to the invention, different spray profiles and spray patterns can be easily realized on the respective substrates 5 by digital programming and control via the command signal 1 in combination with the feedback signal 2. Either the entire surface of substrates 5 can be coated, or the coating can be applied to predefined locations that may be particularly critical for the subsequent deep-drawing process of the substrates 5. The droplet jet of coating agent 11, which is generated by the spray valves 4 according to the invention, can also be generated over a larger area or in a more concentrated manner via the adjustment unit. Furthermore, an increase in the local resolution of the coating with the coating agent 11 on the substrate 5 for sectional coating in the feed direction V can be adjusted accordingly by various factors.With such an increased spatial resolution, results improved by a factor of 4 can be achieved according to the inventors' investigations on the coating of substrates 5 even with different.

[0052] Feed speeds V. The advantages from a technical point of view are that a deterioration in the deep drawing process, which affects the quality, due to the friction conditions in the deep drawing press, is avoided and better results and less waste with high-quality end products can be achieved.

[0053] For global system monitoring of the device 100, the information in the control unit 10 of the spray valve 4, for example, about timing signals to be received, the switching state of the spray air with the spray air valve 17, or the positioning of the nozzle needle 7 via the actuator 8, is stored in a memory module 10.4 and converted, if necessary, into a single, common, pulse-width-modulated digital signal 1. The stored data serves to improve the results and to learn the best-quality form of the coating process with the respective hardware components of the device 100, namely the spray valve 4 and the connected lines or the spray air valve 17.

[0054] In a device 100, a plurality of such spray valves 4 according to the invention can be used with respective control units 10, each having its own digital input for the command signal 1 and the feedback signal 2. This allows multiple spray valves 4 to be simultaneously retrieved, monitored, and controlled by the central system control 3. According to the invention, this enables very short communication times by virtually simultaneously retrieving pending messages for multiple spray valves 4 and their multiple actuators inside the spray valves 4, with minimal hardware expenditure. Rapid response and modification of the spray profiles is thus possible with the device 100 according to the invention.

Claims

Claims 1. Device (100) for applying a coating agent (11) to a substrate (5) that can be moved by a feed device, in particular a lubricant to a metal sheet or continuous metal strip that can be fed to a forming press or a deep-drawing process, with at least one spray valve (4), to which the coating agent (11) is permanently present under pressure and can be applied to the substrate (5) through a nozzle opening (13) and an air cap (14) for atomization, wherein the spray valve (4) is provided with a spray air valve (17) and a nozzle opening (13) that can be changed in an outlet surface by a nozzle needle (7) that is adjustable in its position, wherein an electric actuator (8) for opening / closing and adjusting the nozzle needle (7) and a position sensor (9) are provided for detecting the current position of the nozzle needle (7), both of which are connected in terms of signal technology to a control unit (10) of the spray valve (4) and directly or indirectly to a central control (3) of the device (100), characterized in that the actuator (8) has an electric linear drive that can adjust the nozzle needle (7) without stops, and in that the control unit (10) or the central control (3) is adapted to generate, encode and decode a pulse-width modulated coded command signal (1) and / or feedback signal (2) for a plurality of actuators of the at least one spray valve (4) for applying a predefined, variable amount of coating agent (11) through the spray valve (4) onto the substrate (5).

2. Device (100) according to claim 1, characterized in that a single-phase or multi-phase electric linear drive, a voice coil actuator or a piezo actuator is provided as the electric, stop-free actuator (8) for the nozzle needle (7), which is controlled by a decoded signal from the pulse-width modulated command signal (1) by the control unit (10) can be controlled.

3. Device (100) according to claim 1 or 2, characterized in that the pulse-width modulated coded command signal (1) and / or feedback signal (2) generated and processable by the control unit (10) or the central controller (3) is a combined, uniform signal which is adapted for controlling a plurality of actuators of the spray valve (4), in particular for controlling with signals for the nozzle needle (7) with regard to its degree of closing / opening, for the spray air valve (17) for ejecting the coating agent (11) and the respective temporal sequence of them, in particular in relation to a feed of the substrate (5).

4. Device (100) according to one of the preceding claims, characterized in that the control unit (10) of each of the spray valves (4) is signal-connected to a central system control (3) via a dedicated digital output and digital input with a uniform cable connection (41).

5. Device (100) according to one of the preceding claims, characterized in that a common cable (41) with combined, summarized connections for the signal transmission of command signal (1), feedback signal (2) and power supply of the spray valve (4) is provided for each spray valve (4) for connection to the control unit (10) and / or the system control (3).

6. Device (100) according to one of the preceding claims, characterized in that an electronic position controller (10.1) for rapid control of the actuator (8) of the nozzle needle (7) as well as a coding unit (10.2) and a decoding unit (10.3) for converting the digital, pulse-width modulated signal (1, 2) into analog signals are provided in the control unit (10).

7. Device (100) according to one of the preceding claims, characterized in that in the control unit (10) a memory module (10.4) for storing information, in particular deviations with regard to Target and actual values in the coating process, in particular the opening and duration of the opening of a spray valve (4), are provided.

8. Device (100) according to one of the preceding claims, characterized in that the control unit (10) is adapted to regulate the opening duration and position of the nozzle needle (7) for a uniform or varying spray pattern of coating agent (11) on the substrate (5).

9. Device (100) according to one of the preceding claims, characterized in that an adjusting device is provided for adjusting the position of the spray valve (4) in relation to the substrate (5), in particular the distance from its surface or the lateral position in its width direction.

10. Device (100) according to one of the preceding claims, characterized in that the control unit (10) is provided with a soft-close function for the nozzle needle (7), with which a closing speed reduced compared to the normal adjustment speed is set shortly before the spray valve (4) is completely closed and the nozzle needle (7) is placed on a nozzle seat (13).

11. Device (100) according to one of the preceding claims, characterized in that an encoder, a Hall sensor or a potentiometer is provided as the position sensor (9) of the nozzle needle (7).

12. Device (100) according to one of the preceding claims, characterized in that an electronic position controller (10.1) is provided in the control unit (10) for fast, direct control of the actuator (8) of the nozzle needle (7).

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