Operating method for electrostatically charging a coating agent, and coating system for carrying out the operating method

Abstract

The invention relates to an operating method for electrostatically charging a coating agent in a coating system for coating components (e.g. vehicle body components) with a coating agent (e.g. paint) by means of an applicator (e.g. a rotary atomiser), comprising the following steps: • charging a high-voltage electrode (12), wherein a charging voltage (U) is at a high-voltage level at the high-voltage electrode (12) and a charging current (I) flows via the high-voltage electrode (12), • measuring the charging voltage (U) and / or the charging current (I) of the high-voltage electrode (12), and • determining a state variable (e.g. degree of contamination) of the high-voltage electrode (12) or of the applicator (3) from the measured charging voltage (U) and / or charging current (I). The invention also relates to a coating system for carrying out the operating method according to the invention.

Description

[0001] DESCRIPTION

[0002] Operating procedure for electrostatic coating material charging and coating system for carrying out the operating procedure

[0003] Technical field of the invention

[0004] The invention relates to an operating method for electrostatically charging a coating agent in a coating system for coating components (e.g., automotive body components) with a coating agent (e.g., paint) using an applicator (e.g., rotary atomizer). The invention further relates to a coating system for carrying out the operating method according to the invention.

[0005] Background of the invention

[0006] In modern paint shops for painting automotive body components, rotary atomizers are most commonly used as application devices. These are guided by a painting robot within a paint booth and spray a jet of paint onto the body components being painted. However, some of the sprayed paint does not settle on the surfaces of the body components being painted, but instead forms overspray, which can contaminate the interior of the paint booth and, in particular, the rotary atomizer itself.

[0007] To minimize disruptive overspray and thus increase the application efficiency, electrostatic paint charging is typically used in paint shops for automotive body components. The applied paint is electrostatically charged while the vehicle body components to be painted are electrically grounded, resulting in a very high application efficiency and correspondingly low overspray on the component surfaces. This electrostatic paint charging can be achieved using an external charging ring attached to the rotary atomizer, which has several finger-shaped external electrodes that charge the sprayed paint through ionization.As part of this electrostatic paint charging process, the charging voltage and / or charging current of the electrostatic paint charge are usually measured in order to enable high-voltage control.

[0008] The electrostatic paint charging described above advantageously increases the application efficiency and thus minimizes disruptive overspray. Nevertheless, a certain amount of disruptive overspray still occurs, causing some of the paint sprayed by the rotary atomizer to deposit on the atomizer, the external charging ring, and especially on the finger-shaped external electrodes, leading to contamination. As the external electrodes become increasingly contaminated, their function can be impaired, which must be carefully monitored by the paint system operator. If the external electrodes become excessively contaminated, they must be cleaned. However, this presents several problems.

[0009] Firstly, some contamination-related errors cannot be detected by the operating personnel of the paint system from outside the paint booth, which applies, for example, to individual finger-shaped external electrodes that have a functional impairment due to contamination.

[0010] On the other hand, the contamination caused by the disruptive overspray requires careful monitoring of the painting process by the operating personnel of the painting system.

[0011] Regarding the state of the art, reference should also be made to DE 10 2021 121 552 Al, DE 199 03 824 Al, DE 34 45 946 Al, DE 10 2019 112 099 B3 and DE 10 2021 121 553 Al.

[0012] The invention is therefore based on the objective of creating an operating method for electrostatic coating agent charging that solves the problems described above. Furthermore, the invention is based on the objective of creating a corresponding coating system adapted to carry out the operating method according to the invention.

[0013] This task is solved by an operating procedure or a corresponding coating system in accordance with the independent claims.

[0014] The invention is based on the newly acquired technical-physical insight that the measured values ​​for charging voltage and charging current of electrostatic paint charging not only enable high-voltage control - as in the prior art - but also contain information about a state variable (e.g. degree of contamination) of the high-voltage electrode or the applicator (e.g. rotary atomizer) and can be automatically evaluated with the help of artificial intelligence without observation of the painting process by the operating personnel.

[0015] The operating method according to the invention therefore initially provides, in accordance with the prior art described above, for electrostatic charging of the coating material, wherein a high-voltage electrode is charged to a high-voltage level and a corresponding charging current flows through the high-voltage electrode. In accordance with the prior art, the charging voltage and / or the charging current of the high-voltage charging process are measured. In the prior art described above, the measured values ​​of charging current and / or charging voltage are used only for high-voltage control. However, the invention now provides that a state variable (e.g., degree of pollution) of the high-voltage electrode or the applicator (e.g., rotary atomizer) is determined from the measured values ​​of charging voltage and / or charging current.This can preferably be automated using artificial intelligence, so that monitoring of the painting process by the operating personnel is not absolutely necessary.

[0016] The terms charging current and charging voltage used within the scope of the invention preferably denote actual values ​​of the current and voltage of the electrostatic coating agent charging, respectively. These terms are therefore preferably not limited to the charging voltage and charging current during the start-up of the electrostatic coating agent charging. Rather, these terms preferably also include the current and voltage of the electrostatic coating agent charging during coating operation, i.e., in the started-up state of the electrostatic coating agent charging.

[0017] Furthermore, it should be noted that the state variable of interest (e.g., pollution degree) of the high-voltage electrode or the applicator (e.g., rotary atomizer) does not have to be derived directly from the measured values ​​of the charging voltage and / or charging current within the scope of the invention. Rather, it is also possible for the state variable of interest (e.g., pollution degree) to be determined from a value derived from the charging current or charging voltage. For example, within the scope of the invention, it is possible to first calculate the time derivative of the charging voltage and / or charging current, whereby the state variable of interest (e.g., pollution degree) is then determined as a function of this time derivative. The state variable of interest (e.g., pollution degree) can therefore also be derived indirectly from the measured values ​​of the charging voltage and / or charging current.

[0018] It should be noted that the operating method according to the invention is preferably used in a paint shop for coating motor vehicle body components with a paint, using a rotary atomizer as the applicator. However, the invention is not limited to motor vehicle body components with regard to the components to be coated, but can also be implemented in principle for coating other types of components. Furthermore, the invention is not limited to paint with regard to the coating material to be applied, but can also be implemented in principle with other types of coating materials. Finally, the invention is not limited to rotary atomizers with regard to the applicator to be used, but can also be implemented in principle with other types of applicators (e.g., air atomizers, airless, airmix, and ultrasonic devices).

[0019] It has already been mentioned above that, within the scope of the invention, a state variable of the high-voltage electrode or the applicator is determined from the measured values ​​of charging voltage and / or charging current of the electrostatic coating agent charging.

[0020] This state variable can, for example, be a degree of contamination, which indicates the extent to which the high-voltage electrode or the applicator is contaminated by coating residues ("overspray").

[0021] Alternatively, the determined state variable could be a degree of wetness, indicating how moist the surface of the applicator or high-voltage electrode is due to adhering liquid coating material.

[0022] Furthermore, the determined state variable can also be a type identifier that reflects the component type of the high-voltage electrode, in particular to distinguish a mounted external charging ring from a dummy.

[0023] Furthermore, within the scope of the invention, it is possible that the determined state variable indicates whether one or more high-voltage electrodes are impaired in their function due to contamination.

[0024] Furthermore, within the scope of the invention, it is also possible that the determined state variable indicates how many of several high-voltage electrodes have failed due to contamination or whether many high-voltage electrodes have failed due to contamination.

[0025] The above-described possibilities of various state variables that can be derived from the measured values ​​of charging voltage and / or charging current can also be combined with each other, i.e., various state variables can be derived from the measured values ​​of charging voltage and / or charging current.

[0026] Furthermore, it should be noted that the determined state variable can be either quantitative or qualitative. For example, the degree of contamination, as a quantitative state variable, can take a value from 0 (completely clean) to 100 (completely contaminated). As a qualitative state variable, however, the degree of contamination can indicate whether the contamination leads to a functional impairment (error flag is set) or not (error flag is not set).

[0027] As mentioned above, the degree of soiling of the high-voltage electrode or the applicator (e.g., rotary atomizer) can be derived from the measured values ​​of charging voltage and / or charging current as state variables. The determined degree of soiling can then be compared with a limit value, and a warning signal can be displayed if the determined degree of soiling exceeds the limit value. Furthermore, a cleaning process can be initiated if the limit value is exceeded; this process can be carried out mechanically or manually. For mechanical cleaning of the applicator and / or the high-voltage electrode, the applicator can, for example, be inserted into a cleaning device ("cleaner") by a painting robot, where it is then cleaned. Such cleaning devices are known from the prior art and therefore do not need to be described in detail (see [reference]).EP 3 140 042 Bl, EP 2 643 096 Bl). Before initiating a cleaning process of the applicator, the charging voltage is preferably switched off to allow subsequent cleaning in a de-energized state.

[0028] As mentioned above, the applicator can be cleaned mechanically in a cleaning device if testing reveals that the measured degree of contamination exceeds a limit. After mechanical cleaning, the degree of contamination can then be determined again by evaluating the charging voltage and / or charging current to check whether the degree of contamination still exceeds the limit. If so, manual cleaning can then be requested to remove any remaining contamination after mechanical cleaning. The measurement and evaluation of the charging voltage and / or charging current of the electrostatic coating agent charging, as provided for in the invention, also enables optimization of the position and / or orientation of the applicator relative to the component to be coated.When coating complex component contours with difficult access, strong voltage spikes or dips often occur, which is undesirable. Minor adjustments to the applicator's orientation and / or position can remedy this and prevent the unwanted voltage spikes or dips. Therefore, the invention also provides the possibility of slightly modifying the applicator's position and / or orientation relative to the component being coated when identifying a disruptive voltage spike or dip, in order to prevent voltage spikes or dips in the charging voltage of the high-voltage electrode.This minor adjustment of the position and / or orientation of the applicator can be achieved, for example, using artificial intelligence, whereby an artificial intelligence algorithm determines which change in the position and / or orientation of the applicator leads to the desired result, namely to the avoidance of the disturbing voltage spikes or voltage dips.

[0029] As mentioned above, the degree of pollution of the applicator or components of the electrostatic coating system can be determined from the measured values ​​of charging voltage and / or charging current. This can be done using a machine learning algorithm that estimates the degree of pollution based on the measured values ​​of charging voltage and / or charging current. The machine learning algorithm can be trained using supervised learning by receiving the actual degree of pollution as input information. This actual degree of pollution can be specified, for example, by user input or by evaluating a camera image of the applicator and / or the high-voltage electrode.The machine learning algorithm receives as input information the measured values ​​of charging current and / or charging voltage on the one hand, and the actual degree of pollution on the other, so that the machine learning algorithm can be trained accordingly to learn the relationship between the measured values ​​of charging current or charging voltage on the one hand and the associated degree of pollution on the other.

[0030] The evaluation of charging current and / or charging voltage according to the invention also enables, within the scope of the invention, the detection and differentiation of various operating states of the coating system. For example, the following operating states of the coating system can be detected and distinguished from one another:

[0031] • Flawless coating operation,

[0032] • Contamination of the high-voltage electrode due to the deposition of coating residues ("overspray") on the high-voltage electrode,

[0033] • Contamination of the steering air ring due to the deposition of coating residues ("overspray") on the steering air ring,

[0034] • Contamination of the applicator (e.g. rotary atomizer) due to the deposition of coating material residues ("overspray") on the applicator, and / or

[0035] • Contact fault between the high-voltage electrode and a high-voltage generator supplying the high-voltage electrode.

[0036] In a preferred embodiment of the invention, all of the aforementioned different operating states can be detected and distinguished from one another. However, it is also possible within the scope of the invention that only some of the aforementioned operating states are detected and distinguished from one another.

[0037] The aforementioned various operating states can be detected within the scope of the invention by evaluating the measured values ​​of charging current and / or charging voltage. Thus, fault-free coating operation is preferably detected when the following conditions are met:

[0038] • The charging current is essentially equal to a predetermined target value and

[0039] • The charging voltage varies within a permissible voltage range between a predetermined maximum value and a predetermined minimum value.

[0040] Excessive soiling of the high-voltage electrode, on the other hand, is preferably recognized as an operating condition when the following conditions are met:

[0041] • The charging voltage rises to a predetermined maximum value,

[0042] • the charging current drops from a predetermined target value, and / or

[0043] • The time derivative of the charging voltage and / or the charging current exceeds a limit value.

[0044] Excessive contamination of the steering air ring, on the other hand, is preferably recognized as an operating condition when the following conditions are met:

[0045] • The charging voltage drops from or below the specified maximum value, in particular to a specified minimum value, the charging current is essentially equal to the specified target value, and / or the time derivative of the charging voltage and / or the charging current exceeds a limit value.

[0046] In contrast, a contact fault of the high-voltage electrode is preferably recognized as an operating condition when the following conditions are met:

[0047] • The charging voltage is at the specified maximum value and

[0048] • The charging current is below a predetermined target value and also below a predetermined minimum value, especially zero.

[0049] Furthermore, the invention preferably also enables the detection and differentiation of various contact defects of the high-voltage electrode by evaluating the measured values ​​of charging voltage and charging current. For example, the following contact defects can be detected and distinguished from one another:

[0050] • Missing connector of a high-voltage cable at the high-voltage generator,

[0051] • missing connector of the high-voltage cable at the high-voltage electrode, and / or

[0052] • Partially existing plug connection of the high-voltage cable, especially if an electrical contact exists, but the high-voltage cable is not fully plugged in.

[0053] The missing connector of the high-voltage cable at the high-voltage generator can be detected, for example, if the following conditions are met:

[0054] • The charging voltage is at the specified maximum value and

[0055] • The charging current is zero.

[0056] The missing plug connection of the high-voltage cable to the high-voltage electrode can, however, be detected within the scope of the invention if the following conditions are met:

[0057] • The charging voltage is at the specified maximum value and

[0058] • The charging current is smaller than the specified target value of the charging current, in particular more than 5% smaller.

[0059] However, a partially existing connection of the high-voltage cable (e.g., if there is an electrical contact, but the high-voltage cable is not fully plugged in) can be detected if the following conditions are met:

[0060] • The charging voltage is at the specified maximum value and the charging current is less than the specified target value.

[0061] The above outlines how charging voltage and charging current can be evaluated, with one evaluation criterion being that a measured value (e.g., charging voltage) is "essentially" equal to a given reference value. A mathematically exact match between the measured value and the reference value is not required. Rather, agreement is preferably assumed even if the deviation between the measured value and the reference value is relatively small, with deviations of 1%, 2%, 5%, 10%, or even 20% being acceptable.

[0062] It should also be mentioned in general that the state variable of interest (e.g. pollution degree) within the scope of the invention is preferably not derived from instantaneous measured values ​​of charging voltage and / or charging current, but rather from the time course of the measured values ​​of charging current and / or charging voltage.

[0063] Furthermore, it should be noted that the invention can be used for both external charging and contact charging (direct charging) of the coating material. In external charging, the electrostatic charging of the applied coating material is achieved by means of an external charging electrode, which electrostatically charges the spray jet of the coating material through ionization. In direct charging (contact charging), on the other hand, a contact electrode (e.g., in the form of a bell-shaped disc) is provided, which electrostatically charges the coating material through direct contact.

[0064] Furthermore, it should be mentioned that the measured values ​​of charging voltage and / or charging current within the scope of the invention can not only be used to determine the state variable of interest (e.g., pollution degree). Rather, the measured values ​​of charging current and / or charging voltage within the scope of the invention are preferably also used for the high-voltage regulation known per se, as is known from the prior art.

[0065] Furthermore, it should also be mentioned that the high-voltage electrode and / or an external charging ring containing the high-voltage electrode can contain an RFID transponder (RFID: radio-frequency identification). The RFID transponder can then be programmed with an error signal if the determined state variable indicates a malfunction or impairment of the high-voltage electrode or the external charging ring. The operating method according to the invention for a coating system has been described above. However, the invention also claims protection for a coating system configured to carry out the operating method according to the invention.

[0066] The coating system according to the invention, in accordance with the prior art, initially comprises an applicator (e.g., a rotary atomizer) for applying the coating agent. The applicator is preferably guided by a multi-axis application robot, as is known from the prior art.

[0067] Furthermore, the coating system according to the invention, in accordance with the prior art, includes a high-voltage electrode for electrostatically charging the coating material, as is known from the prior art. For this purpose, an external charging ring containing several external electrodes can be arranged on the applicator (e.g., rotary atomizer) to electrostatically charge the sprayed coating material by ionization charging.

[0068] Furthermore, the coating system according to the invention comprises a high-voltage generator for supplying a charging voltage to the high-voltage electrode.

[0069] Furthermore, the coating system according to the invention, in accordance with the prior art, includes an evaluation unit for recording the charging voltage and / or the charging current.

[0070] The coating system according to the invention is characterized in that the evaluation unit executes the operating process according to the invention during operation. For this purpose, a control program can be stored in the evaluation unit, which, when executed on a computer of the evaluation unit, carries out the operating process according to the invention.

[0071] Furthermore, the coating system according to the invention can include a camera to capture an image of the applicator and / or the high-voltage electrode so that the degree of contamination can be derived from it. This enables the aforementioned training of the machine learning algorithm, which can then derive the degree of contamination from the measured values ​​of charging voltage and / or charging current. The coating system according to the invention can also include a cleaning device for cleaning the applicator and / or the external charging ring or the high-voltage electrode.

[0072] Furthermore, the coating system according to the invention can also have a display to indicate the degree of contamination.

[0073] Other advantageous embodiments of the invention are characterized in the dependent claims or are explained in more detail below together with the description of the preferred embodiments of the invention with reference to the figures.

[0074] Figure 1 shows a simplified schematic representation of a painting system according to the invention for painting motor vehicle body components.

[0075] Figure 2 shows a schematic representation of a camera booth for recording a camera image of the rotary atomizer to determine the actual degree of contamination.

[0076] Figure 3 shows a representation of a rotary atomizer with an external charging ring to illustrate the different levels of soiling of the external electrodes.

[0077] Figure 4A shows the time course of charging voltage and charging current during fault-free operation.

[0078] Figure 4B shows a flowchart for detecting fault-free operation by evaluating charging current and charging voltage.

[0079] Figure 5A shows the time course of charging voltage and charging current during rapid electrode fouling.

[0080] Figure 5B shows a flowchart to illustrate the evaluation of charging current and charging voltage for the detection of rapid electron pollution.

[0081] Figure 6A shows the time course of charging voltage and charging current during progressive electrode contamination.

[0082] Figure 6B shows a flowchart to illustrate the evaluation of charging current and charging voltage in the case of progressive electrode contamination.

[0083] Figure 7A shows the time course of charging voltage and charging current with increasing tube contamination.

[0084] Figure 7B shows a flowchart to illustrate the evaluation of charging current and charging voltage for the detection of increasing tube contamination.

[0085] Figure 8A shows the time course of charging current and charging voltage during progressive tube contamination.

[0086] Figure 8B shows a flowchart to illustrate the evaluation of charging voltage and charging current for the detection of progressive tube contamination.

[0087] Figure 9A shows the time course of charging voltage and charging current in the event of a contact fault of the high voltage cable.

[0088] Figure 9B shows a flowchart to illustrate the evaluation of charging current and charging voltage for the detection of the contact fault of the high voltage cable.

[0089] Figure 10 shows a flowchart to illustrate the training of the machine learning algorithm using a camera image to improve the estimates of the pollution level.

[0090] Figure 11 shows a flowchart to illustrate how the machine learning algorithm estimates the degree of pollution.

[0091] Figure 12 shows a flowchart illustrating machine and manual cleaning depending on the determined degree of soiling. Detailed description of the drawings

[0092] The following describes first an exemplary embodiment of a painting system according to the invention as shown in Figure 1.

[0093] The paint shop has a control unit 1 that manages its operation. Here, control unit 1 is depicted as a single component. In practice, however, the control tasks can be distributed across various control components, which are assigned to the individual components of the paint shop, described below.

[0094] Furthermore, the painting system includes a painting robot 2, which is arranged in a paint booth and carries a rotary atomizer 3 as an application device, as is known from the prior art. For the sake of simplicity, only the painting robot 2 with the rotary atomizer 3 is shown here. In practice, however, there are several such painting robots 2 in the paint booth, each with its own rotary atomizer 3.

[0095] Furthermore, the paint system has a mechanical cleaning device 4, also referred to as a "cleaner", which can be located, for example, inside the paint booth. For a mechanical cleaning process, the paint robot 2 then introduces the rotary atomizer 3 into the cleaning device 4, where the rotary atomizer 3 can then be cleaned.

[0096] For electrostatic paint charging, the rotary atomizer 3 has an external charging ring 5, as is known from the prior art. For example, the external charging ring 5 can have several finger-shaped outer electrodes that project from the external charging ring 5 in a finger-like manner in order to electrostatically charge the spray jet of paint dispensed by the rotary atomizer 3.

[0097] The charging voltage for charging the outer electrodes of the external charging ring 5 is provided by a high-voltage generator 6.

[0098] Furthermore, the paint system has an evaluation unit 7 that determines the charging voltage and / or charging current of the electrostatic paint charging and uses a machine learning algorithm to estimate the degree of soiling of the rotary atomizer 3 and the external charging ring 5. In addition, the machine learning algorithm can also recognize and differentiate between various operating states of the paint system by evaluating the charging voltage and charging current, as will be described in detail later.

[0099] Furthermore, the paint system has a camera 8 that can capture an image of the rotary atomizer 3 and the external charging ring 5 in order to derive the degree of contamination. The actual degree of contamination determined in this way can then be fed to the evaluation unit 7 so that the machine learning algorithm can be trained accordingly to improve the estimation of the degree of contamination from the measured values ​​of charging voltage and charging current.

[0100] Finally, the painting system according to the invention has a display 9 to indicate, for example, the operating status of the painting system and the degree of contamination of the rotary atomizer 3 or the external charging ring 5.

[0101] Figure 2 shows a simplified schematic representation of a camera booth 10 for capturing the camera image of the rotary atomizer 3 using the camera 8. Such booths ("cubicles") are also described, for example, in WO 2023 / 110511 Al, so that the content of this earlier patent application is fully applicable to the present description with regard to the design of the camera booth 10. To capture a camera image, the painting robot 2 inserts the rotary atomizer 3 through an insertion opening 11 into the camera booth 10, specifically into the field of view of the camera 8. The camera 8 is directed at the rotary atomizer 3 and then captures a camera image of the rotary atomizer 3 with the external charging ring 5 in order to determine the degree of soiling.

[0102] The drawing also shows that the external charging ring 5 has several finger-shaped external electrodes 12, which are arranged distributed around the circumference of the external charging ring 5 and protrude forward in a finger-like manner.

[0103] Furthermore, the drawing shows that the rotary atomizer 3 carries a bell-shaped plate 13 which rotates around a rotational axis 14 during operation, with the rotational axis 14 coinciding with the jet axis of the spray jet emitted by the rotary atomizer 3.

[0104] Figure 3 shows an image of the soiled rotary atomizer 3 as captured by camera 8. The varying degrees of soiling on the outer electrodes 12 are represented by hatching of different shades. Camera 8 can detect these varying degrees of soiling on the outer electrodes 12, which allows for the training of the machine learning algorithm to improve the estimation of the degree of soiling from the measured values ​​of charging voltage and charging current.

[0105] Figure 4A shows the time course of charging voltage U and charging current I during fault-free operation. The charging current I, shown with a dashed line, rises to a predefined setpoint ISOL and then remains at this setpoint ISOL. The charging voltage U also rises and then fluctuates within a permissible voltage range between a predefined maximum value UMAX and a predefined minimum value UMIN.

[0106] Figure 4B shows a flowchart illustrating the detection of fault-free operation as depicted in Figure 4A. Fault-free operation is detected when the charging current I is essentially constant and equal to the specified setpoint ISOL, while the charging voltage U fluctuates between the specified maximum value U AX and the specified minimum value UMIN.

[0107] Figure 5A shows the time course of charging voltage U and charging current I during rapid electrode fouling. Initially, the charging current I rises back to the specified setpoint ISOL, while the charging voltage U remains within the permissible voltage range between the specified maximum value UMAX and the specified minimum value UMIN. However, the charging current I then drops from the specified setpoint ISOL, while the charging voltage U rises to the specified maximum value UMAX.

[0108] Figure 5B shows a flowchart for detecting the rapid electrode fouling depicted in Figure 5A. Rapid electrode fouling is detected when the charging current I is initially essentially equal to the specified setpoint ISOL and the charging voltage U rises within the permissible voltage range. Furthermore, the time derivative of the charging voltage U and / or the charging current I exceeding a predefined limit can also be considered as a criterion for detecting rapid electrode fouling.

[0109] Figure 6A shows the time course of charging current I and charging voltage U during progressive electrode fouling. The charging current I does not rise to the specified target value ISOL, but instead drops again after exceeding a specified minimum value IMIN. Meanwhile, the charging voltage U remains constant at the specified maximum value UMAX.

[0110] Figure 6B shows a flowchart for detecting the progressive electrode contamination shown in Figure 6A. Progressive electrode contamination is assumed when the charging voltage U is essentially equal to the predefined maximum value UMAX, while the charging current I is less than the predefined ISOL and is decreasing. Furthermore, the time derivative of the charging voltage U and / or the charging current I exceeding a predefined limit can also be considered as a criterion for detecting progressive electrode contamination.

[0111] Figure 7A shows the time course of charging current I and charging voltage with increasing tube fouling, i.e., with increasing fouling of the tube (front housing section) of the rotary atomizer. Increasing tube fouling is characterized by the charging voltage U initially rising to or below the specified maximum value UAX, while the charging current I initially only exceeds the specified minimum value IMIN, but does not reach or even approach the specified target value IOLL. Then, however, the charging voltage U drops from or below the specified maximum value UMAX.

[0112] Figure 7B shows a flowchart illustrating the detection of increasing tube contamination according to Figure 7A. Increasing tube contamination is assumed when the charging voltage U is initially essentially equal to or below the specified maximum value UMAX, while the charging current I is smaller than the specified target value ISOL, but is increasing. In the case of pure tube contamination, the voltage U then drops. Furthermore, the time derivative of the charging voltage U and / or the charging current I exceeding a specified limit can also be considered as a criterion for detecting increasing tube contamination.

[0113] Figure 8A shows the time course of charging voltage U and charging current I during progressive tube fouling. The charging current I rises to the specified target value ISOL and then remains relatively constant at this value. The charging voltage U initially exceeds the specified minimum value UMIN, but then falls relatively linearly back to the specified minimum value UMIN.

[0114] Figure 8B shows a flowchart illustrating the detection of progressive tube contamination as depicted in Figure 8A. Progressive tube contamination is assumed to be the operating state when the charging voltage U is within the permissible voltage range but decreasing, while the charging current I remains relatively constant at the specified target value ISOL. Furthermore, the time derivative of the charging voltage U and / or the charging current I exceeding a predefined limit can also be considered as a criterion for detecting progressive tube contamination.

[0115] Figure 9A shows the time course of charging voltage U and charging current I in the event of a contact fault in the high-voltage cable that supplies the external charging ring with high voltage. In this case, the charging voltage U rises to the specified maximum value UMAX, while the charging current I remains almost at zero.

[0116] Figure 9B shows a flowchart to illustrate the detection of the contact fault shown in Figure 9A. A contact fault of the high-voltage cable is assumed when the charging voltage U is essentially at the specified maximum value UAX, while the charging current I remains essentially at zero.

[0117] Figure 10 shows a flowchart to illustrate the training of the machine learning algorithm.

[0118] In a first step, S1 first measures the charging current I and charging voltage U.

[0119] In addition, in step S2 a camera image of the rotary atomizer with the external charging ring is taken in order to be able to derive the degree of contamination.

[0120] In the next step S3, the machine learning algorithm is then trained using the camera image and the measured values ​​of charging current and charging voltage.

[0121] Figure 11 shows a flowchart illustrating the estimation of the degree of soiling of the rotary atomizer and the external charging ring by evaluating the charging current I and charging voltage U. In a first step S1, the charging current I and the charging voltage U are measured. In the next step S2, the previously trained machine learning algorithm then estimates the degree of soiling based on the measured values ​​of charging current I and charging voltage U.

[0122] Figure 12 shows a flowchart to illustrate the cleaning process depending on the degree of soiling.

[0123] In the first step S1, the charging current and charging voltage are measured again.

[0124] In the next step S2, the machine learning algorithm then estimates the degree of pollution based on the measured values ​​of charging current and charging voltage.

[0125] In the next step, S3, it is checked whether the level of contamination is too high. If this is not the case, the normal painting process continues.

[0126] Otherwise, in step S4, the rotary atomizer is cleaned mechanically in a cleaning device, as is known from the prior art.

[0127] After the atomizer has been cleaned mechanically in the cleaning device, the charging current I and charging voltage U are measured again.

[0128] In the next step S6, the machine learning algorithm then estimates the degree of pollution again based on the measured values ​​of charging current and charging voltage.

[0129] In the next step, S7, it is checked again whether the level of contamination is too high despite the previous machine cleaning. If the machine cleaning has reduced the level of contamination sufficiently, normal painting operations continue.

[0130] Otherwise, in step S8, the atomizer is manually cleaned.

[0131] The invention is not limited to the preferred embodiments described above. Rather, a multitude of variants and modifications are possible, which also make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the dependent claims, irrespective of the claims referenced. The invention thus comprises various aspects of the invention that enjoy independent protection.

[0132] Advantages of the invention

[0133] The invention prevents errors in a paint shop and avoids damage that could be caused by errors of the operating personnel.

[0134] Furthermore, the painting time is extended by delaying the cleaning process. The inventive evaluation of the high-voltage data allows for the control of production interruptions for cleaning only when absolutely necessary.

[0135] Furthermore, the invention enables efficient painting, which increases the cost-effectiveness, sustainability and service life of the painting system and all components.

[0136] Finally, saving on cleaning products improves sustainability and reduces costs.

[0137] 1 Control

[0138] 2 painting robots

[0139] 3 rotary atomizers

[0140] 4 Cleaning device (“Cleaner”)

[0141] 5 external charging ring

[0142] 6 High-voltage generator

[0143] 7 Evaluation unit with machine learning algorithm

[0144] 8 Camera

[0145] 9 ads

[0146] 10 camera booths (“Cubicle”)

[0147] 11 Camera cabin entry opening

[0148] 12 external electrodes

[0149] 13 bell plates

[0150] 14 Rotation axis of the bell plate

[0151] UMAX maximum value of the charging voltage

[0152] U M Minimum value of the charging voltage

[0153] ISOL setpoint of the charging current

[0154] I IN Minimum value of the charging current t Time

Claims

REQUIREMENTS 1. Operating method for electrostatic coating agent charging in a coating system for coating components with a coating agent using an applicator (3), in particular in a painting system for painting motor vehicle body components with a paint using a rotary atomizer (3), comprising the following steps: a) charging a high-voltage electrode (12), wherein a charging voltage (U) at high voltage level is applied to the high-voltage electrode (12) and a charging current (I) flows through the high-voltage electrode (12), and b) measuring the charging voltage (U) and / or the charging current (I) of the high-voltage electrode (12), characterized by the following step: c) determining a state variable of the high-voltage electrode (12) or of the applicator (3) from the measured charging voltage (U) and / or from the measured charging current (I).

2. Operating method Claim 1, characterized in that a) the determined state variable is a degree of contamination indicating the extent to which the high-voltage electrode (12) or the applicator (3) is contaminated by coating material residues, and / or b) the determined state variable is a degree of wetness indicating how moist the surface of the applicator (3) or the high-voltage electrode (12) is due to adhering liquid coating material, and / or c) the determined state variable is a type identifier indicating the component type of the high-voltage electrode (12), in particular for distinguishing an external charging ring (5) from a dummy, and / or d) the determined state variable indicates whether one or more high-voltage electrodes (12) are impaired in their function due to contamination, and / or e) the determined state variable indicates whether one of several high-voltage electrodes (12) has failed due to contamination.and / or f) that the determined state variable indicates how many of several high-voltage electrodes (12) have failed due to contamination, and / or, g) that the determined state variable indicates whether a certain number of high-voltage electrodes (12) have failed due to pollution, and / or h) that the determined state variable indicates how high the number of high-voltage electrodes (12) have failed due to pollution is.

3. Operating method according to one of the preceding claims, characterized by the following steps: a) Displaying a warning signal when the determined pollution level exceeds a limit value, and / or b) Cleaning the applicator (3) and / or the high-voltage electrode (12) when the determined pollution level exceeds a limit value, and / or c) Switching off the charging voltage (U) for cleaning the applicator (3) and / or the high-voltage electrode (12).

4. Operating method according to one of the preceding claims, characterized by the following steps: a) checking whether the determined degree of contamination exceeds a limit value, b) machine cleaning of the applicator (3) in a cleaning device (4) if the determined degree of contamination exceeds the limit value, in particular by inserting the applicator (3) into the cleaning device (4) by means of an application robot, c) optionally subsequently checking again whether the degree of contamination exceeds a limit value, d) optionally evaluating the quality of the machine cleaning, e) optionally requesting manual cleaning if the retest after machine cleaning shows that the degree of contamination still exceeds the limit value even after machine cleaning in the cleaning device (4), f) optionally evaluating the quality of the manual cleaning.

5. Operating method according to one of the preceding claims, characterized by the following steps: a) determining the position and / or orientation of the applicator (3) relative to the component to be coated, and b) adjusting the position and / or orientation of the applicator (3) relative to the component to be coated to minimize voltage peaks of the charging voltage (U) of the high-voltage electrode (12), in particular by means of artificial intelligence.

6. Operating method according to one of the preceding claims, characterized by the following steps: a) Estimating the degree of pollution by means of a machine learning algorithm by evaluating the charging voltage (U) and / or the charging current (I) and / or the time derivative of the charging voltage (U) and / or the time derivative of the charging current (I), b) optionally determining the actual degree of pollution by bl) a user input and / or b2) by evaluating a camera image of the applicator (3) and / or the high-voltage electrode (12), and c) optionally training the machine learning algorithm on the determined actual degree of pollution to improve the estimation of the degree of pollution by the machine learning algorithm, wherein the machine learning algorithm preferably also takes into account the type of component and the type of coating material.d) optional manual input of values ​​regarding the contamination tendency of certain components and coating materials.

7. Operating method according to one of the preceding claims, characterized in that a) the charging current (I) and the charging voltage (U) are measured, b) the following operating states are detected and distinguished from one another by evaluating the charging current (I) and the charging voltage (U): b1) Error-free coating operation, b2) Contamination of the high-voltage electrode (12) by deposition of coating material residues on the high-voltage electrode (12), b3) Contamination of the steering air ring by deposition of coating material residues on the steering air ring, b4) Contamination of the applicator (3) by deposition of coating material residues on the applicator (3), and / or b5) Contact fault between the high-voltage electrode (12) and a high-voltage generator (6).

8. Operating method according to claim 7, characterized in that a) the error-free coating operation is recognized when the following conditions are met: a) the charging current (I) is essentially equal to a predetermined setpoint (ISOLL), and a2) the charging voltage (U) varies within a permissible voltage range between a predetermined maximum value (UMAX) and a predetermined minimum value (UMIN), and / or b) that contamination of the high-voltage electrode (12) is detected when one or more of the following conditions are met: bl) the charging voltage (U) rises to a predetermined maximum value (UAX), and b2) the charging current (I) falls from the predetermined setpoint (ISOLL), b3) the time derivative of the charging voltage (U) or the charging current (I) exceeds a limit value, and / or c) that contamination of the steering air ring is detected when one or more of the following conditions are met: cl) the charging voltage (U) falls from or below the predetermined maximum value (UMAX), in particular to a predetermined minimum value (UMIN), and c2) the charging current (I) is substantially equal to the predetermined setpoint (ISOLL), c3) the time derivative of the charging voltage (U) or the charging current (I) exceeds a limit value, and / or d) that the contact fault of the high-voltage electrode (12) is detected,if the following conditions are met: 1) the charging voltage (U) is at the specified maximum value (UMAX), and 2) the charging current (I) is below a specified setpoint (ISOLL) and also below a specified minimum value (IMN), in particular zero.

9. Operating method according to claim 8, characterized in that the following connection errors of the high-voltage electrode (12) are detected and distinguished from one another by an evaluation of the charging voltage (U) and the charging current (I): a) Missing plug connection of a high-voltage cable at the high-voltage generator (6), b) missing plug connection of the high-voltage cable at the high-voltage electrode (12), and / or c) partially existing plug connection of the high-voltage cable, in particular if the high-voltage cable only has a contact in contact, but is not fully plugged in.

10. Operating method according to claim 9, characterized in that a) the missing plug connection of the high-voltage cable to the high-voltage generator (6) is detected when the following conditions are met: a) the charging voltage (U) is at the specified maximum value (UMAX), and a2) the charging current (I) is zero, b) that the missing connection of the high-voltage cable to the high-voltage electrode (12) is detected when the following conditions are met: b1) the charging voltage (U) is at the specified maximum value (U AX), and b2) the charging current (I) is less than the specified target value (ISOLL) of the charging current (I), in particular more than 5% less, c) that the partially existing connection of the high-voltage cable is detected when the following conditions are met: b1) the charging voltage (U) is at the specified maximum value (UMAX), and b2) the charging current (I) is less than the specified target value (ISOLL).

11. Operating method according to one of the preceding claims, characterized in that the state variable of the high-voltage electrode (12) is derived from the time course of the measured charging voltage (U).

12. Operating method according to one of the preceding claims, characterized in that a) the high-voltage electrode (12) is an external charging electrode (12) that electrostatically charges a spray jet of the coating material by ionization charging, or b) that the high-voltage electrode (12) is a contact electrode that electrostatically charges the coating material by direct contact.

13. Operating method according to one of the preceding claims, characterized in that a) within the framework of a current control the charging current (I) is controlled by the charging current (I) is set as a control variable, the voltage (U) changes with the load conditions or b) that, within the framework of a voltage control, the charging voltage (U) is controlled by setting the charging voltage (U) as a control variable, the current (I) changes with the load conditions.

14. Operating method according to one of the preceding claims, characterized in that a) the high-voltage electrode (12) and / or an external charging ring (5) containing the high-voltage electrode (12) contains an RFID transponder, and b) the RFID transponder is written with an error signal when the determined The state variable indicates a malfunction of the high-voltage electrode (12) or the external charging ring (5).

15. Coating system for coating components with a coating agent, in particular in a painting system for painting motor vehicle body components with a paint, comprising a) an applicator (3) for applying the coating agent, in particular as a rotary atomizer (3), b) a high-voltage electrode (12) for electrostatically charging the coating agent, c) a high-voltage generator (6) for supplying a charging voltage (U) to the high-voltage electrode (12), and d) an evaluation unit (7) for detecting the charging voltage (U) and / or the charging current (I), characterized in that the evaluation unit (7) performs the operating procedure according to one of the preceding claims during operation.

16. Coating system according to claim 15, characterized by a) a camera (8) for capturing an image of the applicator (3) and / or the high-voltage electrode (12) for determining the contamination of the applicator (3) and / or the high-voltage electrode (12), and / or b) a cleaning device (4) for cleaning at least a part of the applicator (3) and / or the high-voltage electrode (12), and / or c) a display (9) for displaying an indication of the contamination of the applicator (3) and / or the high-voltage electrode (12), and / or d) an application robot (2) for moving the applicator (3).

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