COATING DEVICE WITH A VIBRATION SENSOR AND ASSOCIATED OPERATING PROCEDURE

Description

Technical field of the invention

[0001] The invention relates to a coating device (e.g., a painting robot) for coating components (e.g., automotive body components) with a coating material (e.g., paint). The invention further relates to a corresponding operating method. Background of the invention

[0002] In modern paint shops for painting automotive body components, rotary atomizers are commonly used as application devices, which rotate a bell-shaped plate at high speed, whereby the paint to be applied is flung off the rotating bell-shaped plate and atomized.

[0003] During operation, an imbalance can occur in the rotary atomizer, which can lead to a malfunction. Such an imbalance can arise, for example, if the bell-shaped disc collides with a boundary (e.g., the wall of the paint booth). These types of malfunctions in the rotary atomizer should be detected during operation so that they can be rectified without significantly disrupting the operation of the paint system.

[0004] From WO 2016 / 180521 A1, a painting system is known that detects such malfunctions of rotary atomizers. Vibration sensors are used for this purpose to analyze the mechanical vibrations emanating from the rotary atomizer and thereby detect a malfunction.

[0005] A disadvantage of this known concept, however, is that the evaluation of the vibration signals from the various vibration sensors only allows conclusions to be drawn about a specific malfunction of the rotary atomizer. With this known concept, it is not possible to detect and locate malfunctions in other failure-prone components of the paint system. Furthermore, it is not possible with this known concept to distinguish between different types of malfunctions.

[0006] Finally, the technical background of the invention is also described in US 2019 / 0314842 A1.

[0007] The invention is therefore based on the objective of creating an improved coating device and a corresponding operating method. Description of the invention

[0008] This problem is solved by a coating device according to the invention or a corresponding operating method according to the independent claims.

[0009] The coating device according to the invention is preferably used for painting motor vehicle body components with a paint. However, the invention is not limited to this specific field of application with regard to the type of components to be coated and the type of coating agent applied. For example, the coating device according to the invention can also apply other coating agents, such as insulating materials, sealants, or adhesives, to name just a few examples. There are also no restrictions within the scope of the invention with regard to the type of components to be coated. Instead of motor vehicle body components, the coating device according to the invention can also be designed for coating other components. Examples include aircraft components or components of wind turbines.

[0010] In a preferred embodiment of the invention, however, the coating device is a painting robot as is known from the prior art, so that a detailed description of the design details of the painting robot can be omitted at this point.

[0011] The coating device according to the invention, in accordance with the aforementioned known coating system, comprises several components prone to failure, in which malfunctions can occur during operation of the coating device. It has been mentioned above only that malfunctions can occur in a rotary atomizer, with these malfunctions being caused by an imbalance. However, the term "component prone to failure" is to be understood generally within the scope of the invention and is not limited to rotary atomizers. Rather, malfunctions can also occur in other components within the scope of the invention, as will be explained in detail later.

[0012] Furthermore, the coating device according to the invention, in accordance with the known painting system described above, also has at least one vibration sensor to detect mechanical vibrations in the coating device and to generate a vibration signal that can be evaluated by control technology and that represents the mechanical vibrations.

[0013] Furthermore, the coating device according to the invention, in accordance with the known painting system described at the outset, also has an evaluation unit which serves to evaluate the vibration signal emanating from the vibration sensor and, depending on this, to diagnose an operational malfunction of one of the fault-prone components of the coating device.

[0014] The evaluation unit of the coating device according to the invention diagnoses various operational malfunctions of various fault-prone components by evaluating the vibration signal.

[0015] Firstly, the evaluation unit can distinguish between different types of operational disturbances by evaluating the vibration signal.

[0016] Secondly, the evaluation unit can also differentiate between operational malfunctions of various failure-prone components. For example, by analyzing the vibration signal, the evaluation unit can distinguish whether there is an imbalance in a bell-shaped plate or a bearing failure in the painting robot.

[0017] Specifically, the invention enables the diagnosis and differentiation of the following operational malfunctions: Gearbox damage to at least one gearbox, collision of the coating robot with an obstacle, and malfunctions of the application device.

[0018] It has already been briefly mentioned above that, within the scope of the invention, various failure-prone components of the coating device can be monitored for operational malfunctions, i.e., not only rotary atomizers, as is known from the prior art.

[0019] For example, a component prone to failure that is monitored for operational malfunctions could be a coating robot (e.g., a painting robot), which as such has multiple robot axes. Typically, such coating robots have serial robot kinematics and at least six robot axes, as is known from the prior art. In the preferred embodiment of the invention, the coating robot has a robot base, a pivotable robot element, a proximal robot arm, a distal robot arm, and / or a robot wrist axis. Various operational malfunctions can occur in such a coating robot, such as bearing damage, gearbox damage, or motor damage.

[0020] Furthermore, a component prone to failure, which is monitored for operational malfunctions, can be an application device used to apply the coating material. A rotary atomizer has already been mentioned above as an example of such an application device. However, within the scope of the invention, other types of application devices can also be monitored for operational malfunctions, such as so-called printheads, which apply the coating material essentially without overspray.

[0021] Another component prone to failure, which can be monitored for malfunctions during operation, is a compressed air turbine, which can be used, for example, in a rotary atomizer to rotate a turbine shaft, as is known from the prior art. Malfunctions in such compressed air turbines can include, for example, bearing damage.

[0022] As mentioned briefly above, in a rotary atomizer, a collision between the bell-shaped nozzle and a boundary (e.g., the wall of the paint booth) can lead to an imbalance. Therefore, the component prone to failure, which is monitored for malfunctions during operation, could also be the bell-shaped nozzle.

[0023] Furthermore, within the scope of the invention it is possible to detect operational malfunctions of a metering pump that meters the coating agent to the application device.

[0024] Furthermore, as briefly mentioned above, conventional painting robots have motors, gearboxes, and bearings that can also experience malfunctions, which can be diagnosed within the scope of the invention. Therefore, the failure-prone components that are monitored for malfunctions within the scope of the invention can also be the motors, gearboxes, and / or bearings of the coating robot.

[0025] Finally, coating systems typically incorporate controllable pressure valves, such as a coating agent valve to control the flow of the coating agent or a rinsing agent valve to control the flow of the rinsing agent. These pressure valves can also malfunction during operation. Therefore, the component subject to failure, which is monitored for malfunctions during operation, could also be a controllable pressure valve, for example, in a rotary atomizer. More generally, the monitored component of the coating system could be any valve, such as one that is electrically actuated.

[0026] The foregoing description of various failure-prone components is not exhaustive. Rather, the concept according to the invention can also be used to detect operational malfunctions in other components of a coating system.

[0027] As mentioned above, the concept according to the invention is particularly suitable for fault detection on a coating robot (e.g., a painting robot) that carries an application device (e.g., a rotary atomizer). Here, it is possible to detect operational faults of the application device by evaluating the vibration signal of the vibration sensor. The vibration sensor can be mounted on the coating robot remotely from the application device. The mechanical vibrations emanating from the application device are transmitted to the vibration sensor via the coating robot, which has specific vibration transmission characteristics. The evaluation unit can then analyze the vibration signal of the vibration sensor, taking into account the vibration transmission characteristics of the coating robot.For example, the vibration sensor can be mounted on the robot base, on a rotatable robot limb, on the proximal robot arm ("Arm 1"), on the distal robot arm ("Arm 2") or on the robot hand axis, to name just a few examples.

[0028] The spatial separation between the application device being monitored and the vibration sensor is particularly advantageous when the coating robot has an electrostatic charge from the coating material. In this case, the application device is located in a high-voltage area, making it problematic to place the vibration sensor directly on or inside the application device, as the sensor would then also be at high-voltage potential. In contrast, the spatial separation between the application device being monitored and the vibration sensor allows the vibration sensor to be located in an electrically grounded area, thus simplifying the process of reading the vibration sensor, as no galvanic isolation is required.

[0029] It has already been briefly mentioned above that the concept according to the invention offers the possibility of diagnosing and differentiating various operational malfunctions of the coating device.

[0030] One possible malfunction – as briefly mentioned above – is an imbalance in the bell-shaped disc of a rotary atomizer. However, such an imbalance can occur not only in the bell-shaped disc itself, but also in other rotating components that rotate with it, such as the turbine shaft of the rotary atomizer.

[0031] Another possible malfunction is therefore an imbalance in a component of the rotary atomizer that rotates with the bell plate.

[0032] Another possible malfunction is mechanical wear of a bearing (e.g., a rolling bearing), for example, a bearing in the rotary atomizer or a bearing in the coating robot. The bearing in question could be any type, such as in a gearbox, axle, or motor, to name just a few.

[0033] Other potential malfunctions that can be detected during operation include oil leaks from a gearbox, a lack of gearbox oil, or oil leaks or a lack of engine oil from the coating robot's motor. Such malfunctions lead to increased friction, which causes measurable vibrations.

[0034] Furthermore, assembly errors can also be detected within the scope of the invention, such as an incorrect tightening torque of a fastening screw or a faulty assembly of a drive shaft.

[0035] Furthermore, a malfunction can also occur if a drive shaft of a metering pump is incorrectly installed or is not suitable in its design.

[0036] Finally, the invention also provides the possibility of detecting collisions of the coating robot with an obstacle, for example with a room boundary (e.g., the wall of a paint booth) or with another coating robot.

[0037] The foregoing description of various possible operational malfunctions is not exhaustive. Rather, the concept according to the invention also enables the detection of other operational malfunctions that manifest themselves in a change in vibration behavior.

[0038] Regarding the design and operation of the vibration sensor, the invention offers various possibilities. For example, the vibration sensor can be a two- or three-axis accelerometer. Alternatively, the accelerometer can also be a two- or three-axis accelerometer that includes a two- or three-axis gyroscope. Therefore, the invention is not limited to specific types of vibration sensors with respect to the design and operation of the vibration sensor.

[0039] As mentioned briefly above, painting equipment typically features an electrostatic coating charge, resulting in a high-voltage area and an electrically grounded area. The vibration sensor is then preferably located in the electrically grounded area, which simplifies the sensor's interrogation since no potential isolation is required.

[0040] Furthermore, it should be noted that painting facilities often include an explosion-proof room, which may, for example, have an air purge system. Such explosion-proof rooms are described, for example, in the technical standards IEC / EN 60079-11-Part 11, IEC / EN 60079-25-Part 25, and IEC / EN 60079-14-Part 14. The vibration sensor can optionally be located either inside or outside the explosion-proof room.

[0041] Regarding the spatial arrangement of the vibration sensor in a coating robot, it should also be noted that such coating robots have a separate drive unit with a housing for each robot axis. The vibration sensor can, for example, be located in the housing of the drive unit for the fourth, fifth, or sixth robot axis.

[0042] As mentioned above, the evaluation unit analyzes the vibration signal supplied by the vibration sensor to detect malfunctions in the coating system. It is also possible for the evaluation unit to first calculate a vibration characteristic value from the signal, and then perform the analysis based on this value. This vibration characteristic value could be, for example, the RMS value of the vibration signal, the maximum value of the vibration signal, the first-order amplitude of the vibration signal, a higher-order amplitude of the vibration signal, the total harmonic distortion (THD) of the vibration signal, or the crest factor of the vibration signal, to name just a few.

[0043] In one variant of the invention, the vibration characteristic value is calculated directly in the vibration sensor by sensor electronics integrated into the vibration sensor.

[0044] In another embodiment of the invention, the vibration characteristic value is calculated from the vibration signal only in the evaluation unit, which is preferably structurally separate from the vibration sensor. Alternatively, however, the evaluation unit can be structurally integrated into the vibration sensor or form a single structural unit with the vibration sensor by being arranged directly on the vibration sensor.

[0045] If the vibration sensor and evaluation unit are spatially separated, it is also possible that the evaluation unit consists of several spatially separated parts, such as an evaluation unit on the coating robot and a robot control unit.

[0046] Generally, part of the evaluation can be performed directly at the vibration sensor, while another part takes place in a spatially separate evaluation unit. For example, the individual signals can be filtered and superimposed to form a combined signal directly at the vibration sensor, while the vibration characteristic value is calculated from the combined signal in the physically separate evaluation unit.

[0047] In principle, the comparison of the vibration characteristic value(s) with one or more limit value(s) can also be carried out directly at the sensor, in the spatially separate evaluation unit, or partly directly at the sensor and partly in the spatially separate evaluation unit.

[0048] Furthermore, the invention also provides the possibility that the vibration characteristic value is calculated by software running in a microprocessor that is connected to or integrated into the evaluation unit.

[0049] When evaluating the vibration characteristic, the value can be compared to a limit value (e.g., a maximum value), and a second warning signal is generated if the vibration characteristic exceeds the limit value. This second warning signal can then be displayed visually and / or audibly to the operator of the coating system. Alternatively, the second warning signal could simply be an error flag in a machine control system.

[0050] According to the invention, the evaluation unit monitors the vibration characteristic value over the operating time of the coating system. The evaluation unit then compares the vibration characteristic value with a predefined component-specific aging behavior and generates a first warning signal if the comparison of the vibration characteristic value with the predefined aging behavior indicates that maintenance or replacement of a failure-prone component is required due to wear. The first warning signal can therefore be a maintenance signal, indicating to the operator that maintenance is due. However, the first warning signal can also be a stop signal, indicating to the operator that operation must be interrupted, whereby the stop signal can also automatically lead to an interruption of operation.

[0051] Furthermore, it should be mentioned that the frequency spectrum can also be determined during the evaluation of the vibration signal (e.g., for evaluating the amplitudes of the first order and / or higher orders). Several different combined signals can also be used to calculate one or more vibration characteristic values, e.g., calculating multiple vibration characteristic values ​​from different combined signals, or using several different combined signals to calculate a single vibration characteristic value.

[0052] Furthermore, the evaluation process allows for the calculation of multiple vibration parameters from several individual signals, for example from all individual signals or only from selected individual signals.

[0053] As mentioned above, the evaluation unit monitors the vibration behavior of the failure-prone components. This vibration monitoring can, for example, take place during normal operation of the coating system. Alternatively, however, the vibration analysis can also be performed in a specific measurement process outside of normal coating operation. For this purpose, a control unit can be provided that controls the coating system according to a predefined measurement process. The vibration sensor then detects the vibrations in the coating system during the measurement process, and the evaluation unit analyzes the detected vibration signals to identify operational malfunctions.

[0054] For example, the control unit can steer the coating robot into a specific robot position for vibration measurement during the measurement process, which enables or simplifies a meaningful vibration analysis.

[0055] Furthermore, within the scope of the invention, it is possible that the control unit drives the rotary atomizer for vibration measurement during the measurement process at a specific rotational speed that is not in the range of resonance frequencies.

[0056] Alternatively, the control unit can also selectively control the rotary atomizer for vibration measurement during the measurement process at a speed that corresponds to a resonant frequency.

[0057] Furthermore, the control unit can also drive the rotary atomizer for vibration measurement during the measurement process at successive increasing speeds, with a vibration measurement being performed at each individual speed. Additionally, the invention allows the control unit to drive the rotary atomizer at different speeds during the measurement process, traversing a predefined speed range. The evaluation unit can then determine actual values ​​of the natural frequencies of the fault-prone component within this speed range during the measurement process and compare these actual values ​​with predefined target values ​​of the natural frequencies to detect a malfunction.

[0058] Furthermore, it should be mentioned that, within the scope of the invention, a single vibration sensor can suffice to detect and differentiate various operational malfunctions in different failure-prone components of the coating device. However, it is also alternatively possible within the scope of the invention for the coating device to have multiple vibration sensors.

[0059] In principle, the invention allows for the evaluation of vibration signals in the time domain and / or the frequency domain. For monitoring purposes, in addition to the "intensity" of a vibration event (e.g., in the form of vibration parameters such as amplitudes, RMS values, etc.), its temporal properties (e.g., duration, transient or periodic) on the one hand and / or its frequency-related properties (e.g., contained frequency components, frequency-related "intensities") on the other hand can be taken into account.

[0060] Furthermore, it should be mentioned that the coating equipment (e.g., paint system) allows for various procedures for identifying errors or malfunctions, which are briefly described below. Procedure 1: The coating system (e.g., paint shop) operates in normal process mode, meaning that many or all parts of the system can be in operation / active simultaneously. The vibration signal therefore contains a multitude of vibration information from various sources (e.g., atomizers, motors, gearboxes, valves, axes, etc.). The vibration sensor "listens" for all possible disturbances simultaneously and analyzes / detects faults through "intelligent" evaluation, essentially by "isolating" individual faults from the multitude of vibration information using appropriate analysis. Procedure 2: The coating system (e.g., paint shop) is operated in specific measurement procedures, with only individual parts of the system active (e.g., a specific turbine speed with the robot stationary, a defined movement of an axis with the turbine not rotating, switching of specific valves with the system stationary, or similar).The vibration signal is therefore dominated by the vibration information that can be precisely attributed to this specific measurement procedure; that is, the evaluation is specifically based on this vibration information.

[0061] The "Procedure 2" described above can be carried out as a follow-up investigation if the "Procedure 1" described above did not initially yield a clear result regarding the fault / error.

[0062] However, the above-described "Procedure 2" can also be carried out as the only procedure as an alternative to the above-described "Procedure 1".

[0063] Furthermore, redundant monitoring is possible within the scope of the invention: To assess disturbances, the vibration analysis can be combined with results from other analyses, e.g., from other sensors (pressure, current, voltage, speed, torque, force, etc.). In practice, coating equipment (e.g., paint shop, robot) typically provides a large number of analyses and sensor results, all of which can be considered within the framework of redundant monitoring. The use of multiple vibration sensors at different locations is also conceivable in this context.

[0064] Furthermore, artificial intelligence (AI) can also be used in the evaluation process to derive assessments from the totality of these many different signals.

[0065] Furthermore, the invention enables a comparison of several robots with each other within a robot cell, within a painting line, or within a painting system. In this way, robots that are particularly prone to malfunctions ("black sheep") can be identified.

[0066] Furthermore, the invention is also suitable for so-called "predictive maintenance," whereby maintenance measures are initiated based on the evaluation of vibration signals, i.e., independently of fixed maintenance intervals. Even a seemingly positive change in vibration behavior (e.g., a reduction in a vibration parameter compared to a previous measurement) can indicate an unfavorable development, such as wear or aging processes. Here, the change itself is of interest, regardless of its direction. This change is then evaluated, for example, by artificial intelligence. Generally speaking, both the (absolute) vibration parameters and their associated limit values ​​(e.g., vibration intensity due to imbalance) and (relative) changes in vibration behavior or parameters (e.g., over time, compared to previous measurements, etc.) can be considered for evaluation.

[0067] Furthermore, it should be mentioned that the invention does not only claim protection for the coating device described above. Rather, the invention also claims protection for a corresponding operating method. The individual process steps of the operating method according to the invention are already evident from the preceding description, so that a separate description of the individual process steps can be omitted.

[0068] 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. Brief description of the drawings

[0069] Figure 1 Figure 1 shows a schematic representation of a painting robot according to the invention with a rotary atomizer, wherein a vibration analysis enables the detection of operational malfunctions. Figure 2shows a perspective view of the painting robot. Figure 3 Figure 1 shows a schematic representation of the calculation of a vibration characteristic value by sensor electronics in the vibration sensor. Figure 4 Figure 1 shows a schematic representation of the calculation of the vibration characteristic value by a microprocessor in the evaluation unit. Figure 5 shows a diagram to illustrate the vibration behavior in the case of an imbalance in a rotary atomizer. Figure 6 shows a diagram illustrating the vibration behavior of a rotary atomizer after a collision. Figure 7 shows a flowchart to illustrate the operating method according to the invention. Figure 8 shows a modification of the flowchart according to Figure 7 . Figure 9 shows a modification of the diagram according to Figure 6 to illustrate a vibration event during the operation of a valve. Figure 10shows a flowchart to explain a variant of the operating method according to the invention. Figure 11 The diagram shows a flowchart of another variant of the operating method according to the invention, in which it is possible to switch to a measurement process in order to facilitate the diagnosis of operational malfunctions. Detailed description of the drawings

[0070] The Figure 1 and 2Figure 1 shows various representations of a painting robot 1 according to the invention, which is largely of conventional design. The painting robot 1 initially has a stationary robot base 2, which carries a rotatable robot element 3, which in this embodiment is rotatable about a vertical axis of rotation. It should be noted that the painting robot 1 can alternatively have a movable robot base, so that the painting robot 1 can be moved along a guide rail. The rotatable robot element 3 in turn carries a proximal robot arm 4, which, according to the usual terminology in the field of robotics, is also referred to as "arm 1". The proximal robot arm 4 is divided into two arm sections 5, 6, which are rotatable relative to each other. The proximal robot arm 4 in turn carries a distal robot arm 7, with a multi-axis robot hand axis 8 mounted at the end of the distal robot arm 7.The robot hand axis 8 in turn carries a rotary atomizer 9 as an application device, with the rotary atomizer 9 in . Figure 2 Not shown for the sake of simplicity.

[0071] The rotary atomizer 9 can be largely of conventional design and contains a compressed air turbine 10 with a bearing 11, wherein the compressed air turbine 10 rotates a bell-shaped disc 12 during operation.

[0072] The painting robot 1 has a conventional electrostatic coating charge and therefore contains a high-voltage area 13 and a grounded, explosion-proof area 14.

[0073] In the high-voltage area 13 of the painting robot 1, in addition to the rotary atomizer 9, there is also a metering pump 15 as well as motors 16, gearboxes 17 and bearings 18 of the painting robot 1.

[0074] The electrically grounded area 14 also contains motors 19, gearboxes 20 and bearings 21 of the painting robot 1.

[0075] Furthermore, the painting robot 1 contains valves, for example in the rotary atomizer 9 and in the metering pump 15, although these valves are not shown for the sake of simplicity. Malfunctions of these valves can also be detected within the scope of the invention.

[0076] Furthermore, the electrically grounded area 14 also contains a vibration sensor 22, which detects mechanical vibrations of the aforementioned components of the painting robot 1 and generates a corresponding vibration signal that is forwarded to an evaluation unit 23. The evaluation unit 23 then analyzes the vibration signal to detect operational malfunctions.

[0077] Firstly, the evaluation unit 23 can identify the faulty component. Thus, by analyzing the vibration signal, the evaluation unit 23 can distinguish whether one of the motors 16 in the high-voltage area 13 is faulty or one of the motors 19 in the electrically grounded area 14, to name just one example.

[0078] On the other hand, the evaluation unit 23 can also identify the type of operational malfunction through vibration analysis. The evaluation unit 23 can therefore distinguish between different types of operational malfunctions.

[0079] In this embodiment, the vibration sensor 22 is arranged in the distal robot arm 7. Alternatively, however, the vibration sensor 22 could also be arranged in the proximal robot arm 4, in the rotatable robot section 3, or in the robot base 2. However, with increasing distance between the rotary atomizer 9 and the vibration sensor 22, it becomes increasingly difficult to deduce possible malfunctions of the rotary atomizer 9 by evaluating the vibration signal. This is due to the vibration transmission characteristics within the painting robot 1 and also to the damping of the mechanical vibrations on the path from the rotary atomizer 9 to the vibration sensor 22. Therefore, the vibration sensor 22 should not be mounted too far away from the rotary atomizer 9 to avoid complicating signal evaluation.However, the vibration sensor 22 is positioned so centrally that vibration events from differently located components, such as robot arms, links, or the rotary atomizer 9, can be detected centrally. This advantageously utilizes the good transmission properties of the robot arms.

[0080] Figure 3Figure 22 shows a schematic representation illustrating the signal evaluation of the vibration sensor 22. Integrated into the vibration sensor 22 is sensor electronics 24, which calculates a vibration characteristic value from the vibration signal, such as the RMS value, the total harmonic distortion (THD), or the crest factor. For this purpose, the time-related vibration signal is first decomposed into frequency components, for example, using a fast Fourier transform, and possibly filtered. This vibration characteristic value is then forwarded to the evaluation unit 23 for signal evaluation.

[0081] Figure 4 shows a variation of Figure 3 , wherein the vibration characteristic value is calculated by a microprocessor 25 which is integrated into the evaluation unit 23.

[0082] Figure 5This diagram illustrates the measurable intensity of the vibration characteristic due to an imbalance U on a rotary atomizer. The imbalance U can increase during operation, for example, due to collisions of the rotary atomizer 9 with a spatial boundary (e.g., the wall of the paint booth) and also due to normal component wear. However, the imbalance could also decrease for any number of reasons.

[0083] A first characteristic curve 26 shows the increase in the imbalance U at a relatively low rotational speed n1 of the rotary atomizer 9. At this low rotational speed n1, an operational malfunction occurs if the vibration characteristic S exceeds a relatively small limit value S MAX1.

[0084] In contrast, a second characteristic curve 27 shows the increasing imbalance U at a relatively high rotational speed n2. A malfunction occurs when the vibration characteristic S exceeds a larger limit value S MAX2.

[0085] The different curves shown in curves 26 and 27 are not necessarily solely attributable to the higher or lower rotational speed. The cause could also be, for example, the frequency-dependent transmission behavior of the robot arm, or other factors.

[0086] In the text and in Figure 5It is described that the rotational speed n1 is relatively low and the rotational speed n2 is relatively high, and that a relatively small limit value is used for the low rotational speed n1, and a larger limit value for the high rotational speed n2. However, this should only be understood as one possible example. In general, the following applies: Even if the higher rotational speed results in a higher excitation force (due to imbalance), this does not necessarily lead to higher vibration intensities at the measuring point. For example, this is not the case if the vibration transmission from the excitation point to the measuring point is correspondingly "worse" for the higher rotational speed (higher frequency) than for the lower rotational speed (lower frequency). Or, put another way: higher vibration intensities can also occur at the measuring point at a lower rotational speed than at a higher rotational speed (i.e., the opposite of what is shown / described). Then, for example,A higher limit value is used at the lower speed than at the higher speed.

[0087] The key general statement is therefore that different vibration intensities (or patterns) are generally to be expected at the measuring point at different rotational speeds n1 and n2. Accordingly, the limit value must be appropriate for the rotational speed.

[0088] For example, measurements / evaluations at two (significantly) different rotational speeds would also constitute a kind of redundant monitoring.

[0089] Figure 6 Figure 1 shows a vibration diagram in the area of ​​a collision between the painting robot and a spatial boundary (e.g., the wall of a paint booth). The collision occurs at time t=t1 and manifests itself in two different vibration events 28, 29.

[0090] At time t=t1 of the collision, the vibration event 28 initially occurs, which manifests itself in the vibrations exceeding a predetermined limit value A MAX. According to a further embodiment, however, the vibration event can also manifest itself in the vibrations falling below a predetermined limit value.

[0091] The other vibration event 29 occurs after the actual collision and manifests itself in the fact that the vibration behavior is subsequently changed and, in the specific embodiment, increased.

[0092] Figure 7 shows a flowchart to illustrate the operating method according to the invention.

[0093] In the first step, S1, the coating system is controlled according to a predefined measurement process. For example, the position of the painting robot can be specified. Furthermore, the measurement process can specify certain rotational speeds for the rotary atomizer. Alternatively, certain parts of the coating system can be in operation during the measurement process, while other parts are inactive. The measurement process can also stipulate that, with the rotary atomizer not rotating, only a specific robot axis is moved, in order to detect, for example, motor and / or gearbox damage during the measurement process.

[0094] During the measurement process, the vibrations are then measured by the vibration sensor in step S2.

[0095] In step S3, a vibration characteristic value is then calculated from the vibration signal.

[0096] In step S4, a diagnosis of operational malfunctions is then carried out, including a determination of the malfunctioning component and also a determination of the type of malfunction.

[0097] Figure 8 shows a variation of Figure 7 .

[0098] Here too, in step S1 a predetermined measurement process is initiated, whereby the rotary atomizer passes through a specific speed range in the measurement process.

[0099] In step S2, the natural frequencies of the rotary atomizer are then determined within the speed range.

[0100] In a further step S3, the determined natural frequencies are then compared with predetermined natural frequencies that would occur in a flawless rotary atomizer.

[0101] In step S7, a diagnosis of possible operational malfunctions is then carried out depending on the comparison.

[0102] Figure 9 shows a modification of the diagram according to Figure 6 To illustrate a vibration event during the operation of a valve. The valve can be any type of valve in a coating system, such as a paint valve, a solvent valve, a pulsed air valve, or a steering air valve, to name just a few examples.

[0103] The X-axis of the graph represents time t, while the Y-axis represents a vibration characteristic S, which is calculated from the recorded vibration signals.

[0104] For example, the vibration characteristic S can be the RMS value of the vibration signal, the maximum value of the vibration signal, the first-order amplitude of the vibration signal, a higher-order amplitude of the vibration signal, the distortion factor of the vibration signal, or the crest factor of the vibration signal, to name just a few examples.

[0105] Furthermore, the diagram shows a vibration event 30 during a switching process, which causes the vibration characteristic S to exceed a predetermined maximum value S MAX, indicating a malfunction of the valve.

[0106] Depending on reference measurements during switching operations of an intact valve, the malfunction of the valve may also manifest itself through the absence of the vibration event 30, or the failure to exceed the maximum value S MAX.

[0107] The flowchart will now be presented according to Figure 10 described, which shows a variant of the operating method according to the invention.

[0108] In a first step S1, the rotary atomizer is controlled to rotate at a specific measurement speed. This measurement speed can be selected to be either outside the resonance range or to match the resonance frequency. The rotary atomizer can therefore be controlled either to avoid resonances or to deliberately induce them.

[0109] In a second step S2, three individual signals are then measured in the three spatial directions (X, Y, Z) by a three-axis sensor. These individual signals were vibration signals in the three spatial directions (X, Y, Z).

[0110] The next step S3 then provides that the three individual signals are bandpass filtered with a center frequency that corresponds to the measuring speed of the rotary atomizer.

[0111] In the next step, S4, the individual signals are then processed to generate a combined signal. For example, the time course of the vector magnitude ("length of the orbit arrow") can be calculated from the three individual signals.

[0112] In the next step S5, a vibration characteristic value is calculated from the overall signal, which is, for example, the RMS value.

[0113] In the final step S6, a diagnosis of disturbances is then carried out based on the vibration characteristic value, as already described above.

[0114] The flowchart will now be presented according to Figure 11 described, which illustrates a variant of the operating method according to the invention.

[0115] In the first step, S1, the coating system is operated in a normal coating process, meaning all components (e.g., rotary atomizer, metering pump, motors, electrostatic coating agent charging, etc.) are active and components are coated. This coating process is therefore the normal operating mode of the coating system for coating components.

[0116] During this normal coating process, in a further step S2, the vibration signals are measured and evaluated to diagnose operational malfunctions, as already described in detail above.

[0117] In the next step, S3, it is checked whether the evaluation of the vibration signals leads to a clear diagnostic result. The clear diagnostic result could, for example, be that no malfunction is detected. However, it is also possible that a malfunction is detected, but it can be clearly identified which component of the coating system is experiencing the malfunction and what type of malfunction it is. In this case, the coating system can continue operating in the normal coating process, or an error message is generated.

[0118] However, during the normal coating process, it can happen that no clear diagnostic result is obtained. This can be due to the fact that the numerous components of the coating system generate vibrations, making it impossible to isolate and identify the malfunction given the multitude of different vibrations from various components. In such a case, the system switches from the coating process to a separate measurement process in step S4. In this measurement process, not all components of the coating system are actively operated, but only individual components or even just a single component.

[0119] In a further step S5, the vibration signals are measured and evaluated again in order to identify the operational malfunction.

[0120] The measurement process makes it easier to identify operational malfunctions because only a few components are active and consequently few vibration signals occur, making signal evaluation much simpler.

[0121] After identifying the operational malfunctions, the process can then be switched back to the coating process, which is not shown here for the sake of simplicity. Reference symbol list:

[0122] 1 Painting robot 2 Robot base 3 Rotating robot link 4 Proximal robot arm ("Arm 1") 5, 6 Arm parts of the proximal robot arm 7 Distal robot arm ("Arm") 8 Robot hand axis 9 Rotary atomizer 10 Compressed air turbine for driving the rotary atomizer 11 Bearing in the rotary atomizer 12 Bell plate of the rotary atomizer 13 High-voltage area of ​​the painting robot 14 Grounded explosion-proof area 15 Metering pump for metering paint 16 Motors for driving the robot axes of the painting robot in the high-voltage area 17 Gearboxes of the individual robot axes in the high-voltage area 18 Bearings of the painting robot in the high-voltage area 19 Motors for driving the robot axes of the painting robot in the grounded area 20 Gearboxes of the individual robot axes in the grounded area 21 Bearings of the painting robot in the grounded area 22 Vibration sensor 23 Evaluation unit 24 Sensor electronics in the vibration sensor for calculating a vibration characteristic value25 Microprocessor in the evaluation unit for calculating a vibration characteristic value 26 Unbalance characteristic curve for low speed 27 Unbalance characteristic curve for high speed 28 Vibration event during a collision 29 Vibration event after a collision 30 Vibration event at a valve

Claims

1. Coating device (1) for coating components with a coating agent, in particular painting robot (1) for painting motor vehicle body components with a paint, comprising a) a plurality of components (9-12, 15-18, 19-22) which are susceptible to malfunctions and in which operating malfunctions can occur during operation of the coating device (1), b) at least one vibration sensor (22) for detecting mechanical vibrations in the coating device (1) and for converting them into a vibration signal which can be evaluated in terms of control technology in accordance with the detected mechanical vibrations, and c) an evaluation unit (23) for evaluating the vibration signal from the at least one vibration sensor (22) and for diagnosing an operating malfunction in one of the components (9-12, 15-18, 19-22) of the coating device (1) which are subject to malfunctions as a function of the vibration signal, wherein the evaluation unit (23) c1) calculates and evaluates at least one vibration characteristic value from the vibration signal, c2) monitors the vibration characteristic value over the operating period of the coating device (1), and c3) diagnoses various operating malfunctions of various components (9-12, 15-18, 19-22) of the coating device (1) that are susceptible to malfunctions by evaluating the vibration signal of the vibration sensor (22), characterized in d) that the evaluation unit (23) compares the vibration characteristic value with a predetermined component-specific aging behavior, and e) that the evaluation unit (23) generates a first warning signal if the comparison of the vibration characteristic value with the predetermined aging behavior indicates that, due to wear, maintenance or replacement of one of the malfunction-prone components (9-12, 15-18, 19-22) is required.

2. Coating device (1) according to claim 1, characterized in that the malfunction-prone components (9-12, 15-18, 19-22) of the coating device (1) monitored for the operating malfunctions comprise several of the following components (9-12, 15-18, 19-22): a) a coating robot (1) with several robot axes, in particular with serial robot kinematics and / or at least six robot axes, in particular with a1) a robot base (2), which is optionally stationary or movable, a2) a pivotable robot member (3) which is pivotable relative to the robot base (2), a3) a proximal robot arm (4) which is pivotable relative to the pivotable robot member (3), a4) a distal robot arm (7) pivotable relative to the proximal robot arm (4), and / or a5) a robot hand axis (8) mounted on the distal robot arm (7), b) an application device (9) for applying the coating agent, in particular as a rotary atomizer (9) with a rotatable bell cup (12), wherein the application device (9) is guided by the coating robot (1), c) a compressed air turbine (10) in the application device (9), in particular for driving a rotatable turbine shaft of the rotary atomizer (9), d) a bell cup (12) mounted on the turbine shaft of the rotary atomizer (9), e) a metering pump (15) for metering the coating agent to the application device (9), f) at least one motor (16, 19), in particular an electric motor, for driving one of the robot axes of the coating robot (1), g) at least one gearbox (17, 20) driven by one of the motors (16, 19) and acting on one of the robot axes, h) at least one bearing (18, 21), in particular air bearing or roller bearing, for rotatably supporting a component of the coating device (1), i) an electrically or pneumatically controllable valve, in particular i1) a coating agent valve for controlling a coating agent flow, i2) a rinsing agent valve for controlling a flow of rinsing agent, i3) a valve for controlling an air flow, i4) a valve for opening / closing a disposal section through which alternately or mixed coating, rinsing / solvent and / or compressed air flows.

3. Coating device (1) according to claim 2, characterized in, a) that the vibration sensor (22) is mounted on the coating robot (1) remote from the application device (9), in particular on the robot base, on the pivotable robot member, on the proximal robot arm, on the distal robot arm or on the robot hand axis, b) that the mechanical vibrations emanating from the application device (9) are transmitted via the coating robot (1) to the vibration sensor (22), the coating robot (1) having certain vibration transmission properties, and c) that the evaluation unit (23) determines operating malfunctions of the application device (9) by evaluating the vibration signal and taking into account the vibration transmission properties of the coating robot (1).

4. Coating device (1) according to one of the preceding claims, characterized in that the evaluation unit (23) diagnoses and distinguishes from each other several of the following operating malfunctions of the coating device (1) by an evaluation of the vibration signal of the vibration sensor (22): a) unbalance of a bell cup (12) of a rotary atomizer (9) b) unbalance of a component rotating with the bell cup (12), in particular the turbine shaft, c) mechanical wear of a bearing (18, 21), d) oil loss or missing gear oil at a gearbox (17, 20), e) oil loss or missing motor oil on a motor (16, 19), f) assembly errors, in particular f1) incorrect tightening torque of a fastening screw or f2) incorrect assembly of a drive shaft, g) faulty drive shaft of a metering pump (15), h) collision of the coating robot (1) with an obstacle, in particular with a room boundary or with another coating robot (1), i) faulty valve circuit and / or faulty function of a valve, j) gearbox damage, k) motor damage.

5. Coating device (1) according to one of the preceding claims, characterized in that the vibration sensor (22) is a biaxial or triaxial acceleration sensor.

6. Coating device (1) according to one of the preceding claims, characterized in, a) that the coating device (1) comprises an explosion-proof chamber (14), in particular with an air purging system, in particular in accordance with the technical standards IEC / EN 60079-11-Part eleven, IEC / EN 60079-25-Part 25 and IEC / EN 60079-14-Part 14, and b) that the vibration sensor (22) is arranged in the explosion-proof chamber (14).

7. Coating device (1) according to one of the preceding claims, characterized in a) that the coating device (1) comprises a coating robot (1) with at least six robot axes which are arranged kinematically in series one behind the other, b) that the individual robot axes each have an axis drive with a housing, c) that the vibration sensor (22) is arranged in the housing of the axis drive for the fourth, fifth or sixth robot axis.

8. Coating device (1) according to one of the preceding claims, characterized in a) that the coating device (1) comprises an electrostatic coating agent charging system and therefore comprises a high-voltage area (13) and an electrically grounded area (14), and b) that the vibration sensor (22) is arranged in the electrically grounded area (14).

9. Coating device (1) according to one of the preceding claims, characterized in that the evaluation unit (23) calculates and evaluates at least one of the following vibration characteristic values from the vibration signal: a) RMS value of the vibration signal, b) maximum value of the vibration signal, c) 1st order amplitude of the vibration signal, d) higher order amplitude of the vibration signal, e) distortion factor of the vibration signal, f) crest factor of the vibration signal.

10. Coating device (1) according to claim 9, characterized in a) that the at least one vibration characteristic value is calculated from the vibration signal by sensor electronics (24) which are structurally integrated into the vibration sensor (22), or b) that the at least one vibration characteristic value is calculated from the vibration signal by the evaluation unit (23), the evaluation unit (23) being structurally separate from the vibration sensor (22), or c) that the at least one vibration characteristic value is calculated by software which runs in a microprocessor (25) which is connected to the evaluation unit (23).

11. Coating device (1) according to claim 9 or 10, characterized in a) that the evaluation unit (23) compares the at least one vibration characteristic value (S) with a limit value (SMAX1, SMAX2), b) that the evaluation unit (23) generates a second warning signal if the at least one vibration characteristic value (S) exceeds or falls below the limit value (SMAX1, SMAX2), c) that preferably the second warning signal is indicated optically and / or acoustically to the operator of the coating device (1).

12. Coating device (1) according to one of the claims 9 to 11, characterized in that the first and / or the second warning signal a) is a maintenance signal indicating to the operator that maintenance is due, or b) is a stop signal which indicates to the operator that the operation must be interrupted or automatically leads to an interruption of the operation.

13. Coating device (1) according to one of the preceding claims, characterized in a) that a control unit is provided which controls the coating device (1) for vibration measurement according to a predetermined measurement process, b) that the at least one vibration sensor (22) measures the vibrations in the coating device (1) during the measuring process, and c) that the evaluation unit (23) evaluates the vibration signals detected during the measuring process.

14. Coating device (1) according to claim 13, characterized in, a) that the control unit controls the coating robot (1) into a specific robot position for vibration measurement during the measurement process, and / or b) that the control unit controls the coating robot (1) for vibration measurement during the measuring process according to a predetermined movement pattern, and / or c) that the control unit controls the rotary atomizer (9) for vibration measurement during the measuring process at a specific rotational speed which is not in the range of resonance frequencies, and / or d) that the control unit controls the rotary atomizer (9) for vibration measurement during the measurement process successively at increasing rotational speeds, with vibration measurement taking place in each case at the individual rotational speeds.

15. Coating device (1) according to claim 13 or 14, characterized in, a) that the control unit controls the rotary atomizer (9) during the measuring process at different speeds which run through a speed band, b) that the evaluation unit (23) determines actual values of natural frequencies of the component susceptible to malfunction within the speed band during the measuring process by evaluating the vibration signal, and c) that the evaluation unit (23) compares the actual values of the natural frequencies with predetermined desired values of the natural frequencies in order to detect an operating malfunction.