Device for cleaning metallic surfaces

Abstract

A device (1) for cleaning metallic surfaces comprises a housing (2) and a cleaning electrode (3) projecting from the housing (2). The cleaning electrode (3) can be moved relative to the housing (2) by means of a tracking device (4) having a linear drive device (5) in order to adjust the cleaning electrode (3) to compensate for wear. Wear of the cleaning electrode (3) can be detected by means of a detection device (6).

Description

[0001] The invention relates to a device for cleaning metallic surfaces, comprising a housing and a cleaning electrode protruding from the housing. Furthermore, the invention relates to a method for tracking a cleaning electrode of a device for cleaning metallic surfaces.

[0002] A device of this type is known from DE 20 2017 105 145 U1.

[0003] EP 3 142 804 B1 describes an electrolytic brush arrangement whose cleaning brush can be adjusted in length by means of an actuator.

[0004] Another device for cleaning metallic surfaces is described in US 10 518 352 B2.

[0005] The process described in DE 20 2017 105 145 U1 for electrochemical cleaning and passivation of weld seams, particularly on chromium-nickel materials, has recently become increasingly popular. This has given rise to the desire for automation of the process.

[0006] In the electrochemical cleaning process, a carbon fiber brush is typically used as the cleaning electrode. The brush's fibers shorten with use, similar to a burning electrode. This reduces the contact between the carbon fiber brush and the workpiece after extended use, which can lead to a complete loss of contact with the workpiece. To ensure that the fibers protruding beyond the housing always remain the same length and ensure even contact with the workpiece, it is necessary to compensate for this wear.

[0007] Typically, the length of the individual fibers of the carbon fiber brush is adjusted by twisting a PTFE sleeve in which they are housed. While this regulates the length of the protruding fibers, the carbon fiber brush becomes shorter due to wear. Since this changes the so-called TCP (tool center point or end effector), this procedure cannot be performed on a handling robot, or only with considerable effort. However, manual intervention is naturally undesirable in automated processes.

[0008] It is therefore an object of the present invention to provide a device and a method for cleaning metallic surfaces with which an automated tracking of the cleaning electrode is possible.

[0009] According to the invention, this object is achieved by the features mentioned in claim 1.

[0010] In the device according to the invention for cleaning metallic surfaces, which comprises a housing and a cleaning electrode protruding from the housing, the cleaning electrode can be tracked relative to the housing by means of a tracking device having a linear drive device in order to track the cleaning electrode to compensate for wear thereof. Wear of the cleaning electrode can be detected by means of a detection device.

[0011] The device according to the invention enables fully automatic and self-regulating tracking of the cleaning electrode, allowing wear occurring during use to be compensated for by measuring and readjusting. The linear drive system is independent of both the power source and the handling robot that accommodates the device, making it very easy to operate. In this way, the device according to the invention enables an automated electrochemical cleaning process without the need for manual intervention.

[0012] The linear drive device can be designed very compactly, allowing it to be housed within the housing of the device according to the invention while ensuring good accessibility for most of the components. The linear drive device can be moved galvanically isolated from the carbon fiber brush. To achieve galvanic isolation, the components used can be made of non-conductive, acid-resistant, and temperature-resistant materials, particularly suitable plastics, to avoid creating an electrical connection between the components.

[0013] In a very advantageous development of the invention, it can be provided that the linear drive device and the detection device can be controlled by a control device. Such a control device, which can have a suitable driver for the linear drive device, serves to control the individual components of the device according to the invention and enable them to communicate with each other. This preferably also allows the system to be expanded in the future to integrate new functions and requirements.

[0014] A further advantageous embodiment of the invention can consist in the cleaning electrode being arranged in a sleeve which is rigidly connected to the housing. The rigid connection of the sleeve to the housing ensures that the TCP, i.e. the tool center point, does not change. The sleeve can be easy to remove, thus ensuring quick access to the cleaning electrode in the event of complete wear. The sleeve also ensures that the individual fibers of the cleaning electrode are bundled together in the event of fraying, which can occur during use due to the fibers moving in different directions. This is achieved by simply moving the cleaning electrode in and out of the sleeve, as the individual fibers bundle together when moved in and retain their condition when moved out.

[0015] If the linear drive device has a drive motor, this provides a simple and reliable drive option for the linear drive device. This is preferably an electric motor, such as a stepper motor.

[0016] Furthermore, it can be provided that the drive motor is connected via a connecting element to a receiving element guided on a linear guide for receiving the cleaning electrode. This results in a parallel arrangement of the drive motor and the cleaning electrode, which saves space and allows the size of the device to be kept to a minimum. Furthermore, this ensures that the linear drive device can move precisely and that no components can become jammed. Preferably, the linear guide is maintenance-free, play-free, and compact.

[0017] In order to achieve the simplest possible supply of the cleaning electrode, in an advantageous embodiment of the invention a cleaning agent supply line can be provided for supplying a cleaning liquid to the cleaning electrode.

[0018] It can be particularly advantageous if the cleaning agent supply line is attached to the receiving element. This ensures that the cleaning fluid always reliably reaches the cleaning electrode via the cleaning agent supply line. The cleaning agent supply line can be at least partially spirally wound or telescopically designed, allowing the cleaning agent supply line to expand and move with the movement of the receiving element.

[0019] Furthermore, an air supply line leading to an air nozzle arranged on the housing and a water supply line leading to a water nozzle arranged on the housing can be provided. Since the electrochemical cleaning process involves acids, which must be removed from the component after cleaning, such air and water nozzles, which ensure cleaning and subsequent drying, are advantageous.

[0020] A method for cleaning metallic surfaces is specified in claim 9.

[0021] In the event of wear being detected by the detection device, the cleaning electrode is adjusted by means of the tracking device, thus ensuring that there is always sufficient contact with the electrode to clean the metallic surfaces.

[0022] In order to increase the reliability of the method according to the invention, it can further be provided that the detection of wear is carried out at regular time intervals.

[0023] An embodiment of the invention is shown in principle below with reference to the drawing.

[0024] It shows: Fig. 1 shows a device according to the invention in a first position; Fig. 2 a section along the line II-II Fig. 1; Fig. 3 a section along the line III-III Fig. 1; Fig. 4 the device according to the invention in a second position; Fig. 5 a section along the line VV Fig. 4; and Fig. 6 a section along the line VI-VI Fig. 4.

[0025] Fig. 1 shows a device 1 for cleaning metallic surfaces not shown in the figures, in particular weld seams on workpieces.

[0026] The device 1 comprises a housing 2 and a cleaning electrode 3 protruding from the housing 2, which is brought into contact with the metallic surface to clean it. The cleaning electrode 3 is designed as a brush in a conventional manner and comprises a plurality of metallic fibers, which, however, are not shown in detail in the figures.

[0027] During operation, the cleaning electrode 3 is subject to wear, which leads to a shortening of the length of the cleaning electrode 3. In order to compensate for this wear, a tracking device 4 is provided, which has a linear drive device 5 and with which the cleaning electrode 3 can be tracked or moved relative to the housing 2. Wear of the cleaning electrode 3 can be detected by means of a detection device 6, which is also described in more detail below.

[0028] Both the linear drive device 5 and the detection device 6 are connected by means of a Fig. 1. The connection between the control device 7 on the one hand and the linear drive device 5 and the detection device 6 on the other hand can be made in a manner known per se. The control device 7 can be part of a handling robot (not shown), with which the device 1 is moved towards the metallic surface and away from it. Even during the cleaning process, the device 1 is preferably moved by the handling robot. The control device 7 can control all processes carried out with the device 1. By integrating the remaining required components in the external control device 7, the linear drive device 5 can be designed to be very compact and lightweight. A flange 2a is attached to the housing 2, with which the device 1 can be connected to the handling robot.

[0029] The control device 7 can also process the input signals of the handling robot, allowing the handling robot to communicate with the logic unit of the linear drive device 5 to find the appropriate operating point. Furthermore, the control device 7 can also output an output signal to the handling robot, ensuring that the handling robot only continues working when the cleaning electrode 3 has measured the optimal distance from the workpiece and the cleaning electrode 3 is not worn. Furthermore, it can be provided that, when the cleaning electrode 3 has fallen below its minimum working length, the user is warned by a visual and / or acoustic signal that the cleaning electrode 3 should be replaced.

[0030] In the cut of Fig. 3 shows that the cleaning electrode 3 is arranged in a sleeve 8, which is rigidly connected to the housing 2. The sleeve 8 is preferably made of an acid-resistant material, such as polytetrafluoroethylene. However, other materials for the sleeve 8 are also conceivable.

[0031] The linear drive device 5 has an electric drive motor 9, which is connected via a connecting element 10, for example a rotating shaft, to a receiving element 12, which is guided by means of a sliding carriage on a linear guide 11, for receiving the cleaning electrode 3. As can be seen from a comparison of Fig. 2 with Fig. 5 or from Fig. 3 with Fig. 6, the drive of the connecting element 10 by the drive motor 9 causes the receiving element 12 to move on the linear guide 11 in the direction of the arrow marked "x", whereby the cleaning electrode 3 is moved relative to the housing 2. The linear drive device 5 has two limit switches 5a and 5b, which limit the movement of the receiving element 12 in both directions, thus preventing collisions in the event of unexpected events. For example, a maximum travel length of the receiving element 12 of 40 mm can be provided. In addition, the linear drive device 5 can be limited by software via a defined step size; however, the limit switches 5a and 5b provide increased security against various causes of errors. In addition, a reference run of the linear drive device 5 can be carried out in this way.

[0032] In the present case, the length of the cleaning electrode 3 has changed from the state according to the Fig. 1 to 3 to the condition according to the Fig. 4 to 6 are significantly shortened due to wear. However, due to the described movement of the cleaning electrode 3 by means of the linear drive device 5, the front end 3a of the cleaning electrode 3, which is remote from the housing 2 of the device 1, protrudes from the sleeve 8 by the same amount. The linear drive device 5 can therefore be used to adjust the cleaning electrode 3 as it wears.

[0033] The detection of the wear of the cleaning electrode 3 by means of the detection device 6 can be carried out by contacting the cleaning electrode 3 with a Fig.3. If the cleaning electrode 3 has not been subjected to any wear since its last contact with the test surface 13, it will come into contact with the test surface 13 when the handling robot moves to the same point. In this case, when a voltage is applied to the cleaning electrode 3, a current flows, which is detected by the detection device 6. In addition, a signal can be output via an optocoupler. If, however, no current can be detected, this means that the cleaning electrode 3 has not come into contact with the test surface 13 and must therefore have shortened due to wear. This is detected by the detection device 6 and forwarded via the control device 7 to the tracking device 4, in this case to the linear drive device 5.The linear drive device 5 then moves the cleaning electrode 3 in the direction of the arrow x until the cleaning electrode 3 comes into contact with the test surface 13. In this case, a current flows through the cleaning electrode 3, thereby detecting contact between the cleaning electrode 3 and the test surface 13. Once a desired current level is reached, the adjustment of the cleaning electrode 3 is complete. This procedure can be performed at regular intervals.

[0034] Alternatively or additionally, it can be provided that the detection device 6 is configured to detect the wear of the cleaning electrode 3 and to carry out a measurement of the energy supplied to the cleaning electrode 3. Furthermore, it can be provided that the detection device 6 is configured to detect or determine the wear of the cleaning electrode using an algorithm based on the measured, preferably temporally accumulated, energy. This allows the cleaning electrode 3 to be readjusted when a certain level of wear is determined, even during operation, so that only a few, or almost none, of the previously described detections by means of the current measurement on the test surface 14 are necessary. This allows the above-mentioned time intervals to be extended considerably if necessary.

[0035] It may be provided that a series of detections be performed using current measurements on the test surface 13 to calibrate the algorithm. This allows the measured applied energy to be correlated with the actual wear of the cleaning electrode 3.

[0036] Instead of the test surface 13, the metallic surface of the workpiece to be cleaned can also be used. After reaching the reference point of the test surface 13, the cleaning electrode 3 can be further adjusted so that an ideal length protrudes from the sleeve 8 in order to achieve the desired or required contact pressure of the cleaning electrode 3 on the metallic surface for the respective cleaning process and to utilize the cleaning process as effectively as possible.

[0037] To ensure the circuit is not closed during the cleaning process, the test voltage is applied via a relay. In addition, the test voltage circuit should be galvanically isolated from the cleaning circuit to protect the electronics from fault currents.

[0038] The device 1 further comprises a cleaning agent supply line 14, which serves to supply a cleaning fluid (not shown) to the cleaning electrode 3. The cleaning agent supply line 14, with which the cleaning fluid reaches the cleaning electrode 3 automatically and in the correct amount, is attached to the receiving element 12 so that it can move with the latter and the connection to the cleaning electrode 3 is always ensured. In order to be able to change the length of the cleaning agent supply line 14 when the receiving element 12 moves, it is partially wound spirally. Alternatively, the cleaning agent supply line 14 can also be telescopic. The cleaning agent supply line 14 is preferably made of polytetrafluoroethylene to ensure both acid resistance and sufficient flexibility. The cross-section of the cleaning agent supply line 14 should be at least 1 mm 2The cleaning agent supply line 14 is continued through a bore in the receiving element 12, so that it ultimately ends at the cleaning electrode 3. The receiving element 12 is sealed from the housing 2 by means of a shaft sealing ring 12a, so that no acid can penetrate into the interior of the housing 2. The shaft sealing ring 12a protects the components located inside the housing 2. The shaft sealing ring 12a, like the sleeve 8, is located in a fixed position, so that the TCP does not vary.

[0039] The device 1 further comprises an air nozzle 15 and a water nozzle 16. An air supply line 17 leads to the air nozzle 15, and a water supply line 18 leads to the water nozzle 16. With the two nozzles 15 and 16, the area of ​​the metallic surface cleaned by the cleaning electrode 3 can be subsequently cleaned and dried, so that no residue of the cleaning fluid remains on the workpiece after the cleaning process.

[0040] Both the cleaning agent supply device 14 and the air supply line 17 and the water supply line 18 are routed from the outside through the housing 2. Suitable seals can be provided for this purpose.

[0041] A power supply cable 19 is used to supply power to the cleaning electrode 3, the cross-section of which must be at least 10 mm 2should be, whereby due to the attachment of the same to the movable receiving element 12 a certain flexibility should nevertheless be given. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2017 105 145 U1 [0002, 0005] EP 3 142 804 B1

[0003] US 10 518 352 B2

[0004]

Claims

[1] Device (1) for cleaning metallic surfaces, comprising a housing (2) and a cleaning electrode (3) protruding from the housing (2), characterized by in that the cleaning electrode (3) can be tracked relative to the housing (2) by means of a tracking device (4) having a linear drive device (5) in order to track the cleaning electrode (3) to compensate for wear thereof, and wherein wear of the cleaning electrode (3) can be detected by means of a detection device (6). [2] Device (1) according to claim 1, characterized by that the linear drive device (5) and the detection device (6) can be controlled by means of a control device (7). [3] Device (1) according to claim 1 or 2, characterized by that the cleaning electrode (3) is arranged in a sleeve (8) which is rigidly connected to the housing (2). [4] Device according to claim 1, 2 or 3, characterized bythat the linear drive device (5) has a drive motor (9). [5] Device according to claim 4, characterized by that the drive motor (9) is connected via a connecting element (10) to a receiving element (12) guided on a linear guide (11) for receiving the cleaning electrode (3). [6] Device according to one of claims 1 to 5, characterized by a cleaning agent supply line (14) for supplying a cleaning liquid to the cleaning electrode (3). [7] Device according to claims 5 and 6, characterized by that the cleaning agent supply line (14) is attached to the receiving element (12). [8] Device according to one of claims 1 to 6, characterized by an air supply line (17) leading to an air nozzle (15) arranged on the housing (2) and a water supply line (18) leading to a water nozzle (16) arranged on the housing (2). [9] Method for tracking a cleaning electrode (3) of a device (1) for cleaning metallic surfaces according to one of claims 1 to 8, wherein the cleaning electrode (3) is tracked by means of the tracking device (4) when wear thereof is detected by means of the detection device (6). [10] Method according to claim 9, characterized by that the detection of wear is carried out at regular intervals.

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