METHOD AND DEVICE FOR CONDITION CONTROLLING VACUUM CLAMPS OF A GRIPPING DEVICE

Description

[0001] The invention relates to a method and a device for condition control of vacuum suction cups of a gripping device which are subjected to vacuum for gripping workpieces.

[0002] WO 2010 / 038315 A1 discloses a method for condition monitoring of vacuum suction cups of a gripping device, which are pressurized with vacuum to grip workpieces. Each vacuum suction cup has a suction element that engages the workpiece. The suction elements are controlled by at least one valve. In the method for condition monitoring of vacuum suction cups, a test device and at least one suction plate of the gripping device are aligned relative to each other, with the test device in an initial state. To test the suction elements, the suction elements of the at least one suction plate and the test device are brought into contact, and the suction elements are pressurized with vacuum. For each test of the suction elements, the test device outputs a signal as soon as a change compared to the initial state is detected.

[0003] From US patent 5,164,558 A, a switch is known that consists of an upper electrode mounted on a deformable membrane and a lower electrode. These electrodes can remain separated in a first stable state of the membrane and be brought into contact in another stable state of the membrane. This switch can be used, for example, as a vacuum sensor. Several of these switches can also be assembled into a sensor.

[0004] From EP 1 967 301 A1, a machine arrangement for processing plate-shaped workpieces is known, comprising a processing unit and a handling device for the processed products. This machine is used for processing plate-shaped workpieces, particularly sheet metal. Preferably, punching and / or cutting operations are performed. For handling the workpieces, the handling device includes a gripping device. This gripping device has one or more suction plates, each with a plurality of vacuum suction cups. To grip the workpieces, the vacuum suction cups are brought into contact with the workpiece. Subsequently, a vacuum is applied, causing the workpiece to be gripped by the vacuum suction cups. The workpieces can then be handled.Each of these vacuum suction cups consists of a suction element that grips the workpiece and a valve for controlling the vacuum suction cup.

[0005] Such vacuum suction cups are subject to wear when used with this type of gripping device. This wear can occur at the edge of the suction opening, for example, in the form of cracks. Furthermore, overloading can occur in the area where the suction elements meet the suction plate, impairing the suction cups' functionality. Monitoring the condition of the valves is also essential for the vacuum suction cups' functionality, ensuring the suction elements are reliably controlled both for gripping and releasing the workpiece.

[0006] The invention is based on the objective of proposing a method for condition control of vacuum suction cups of a gripping device and a device for carrying out the condition control of vacuum suction cups in order to perform a simple test that can be carried out manually by the operator or automatically.

[0007] This problem is solved by a method for condition monitoring of vacuum suction cups of a gripping device, which are pressurized with vacuum for gripping workpieces, wherein each vacuum suction cup has a suction element engaging the workpiece and each suction element or group of suction elements is assigned at least one valve, wherein at least one suction plate of the gripping device, which comprises several vacuum suction cups, and a test device, which comprises several test devices, are aligned with each other so that each vacuum suction cup is opposite a test device, wherein each test device is arranged in an initial state or initial position, and according to a first embodiment, to test the suction elements, the vacuum suction cups of the at least one suction plate and the test devices of the test device are brought into contact and the vacuum suction cups are pressurized with vacuum and a signal is output from each test device.Provided the test device detects a change in the initial state or position, it allows the suction elements to be brought into contact with the respective test device and a vacuum applied. This enables the device to determine whether the suction element is performing its gripping function. If so, the test device triggers a signal. This allows for a simple determination of whether the applied vacuum is being converted into a holding force by the suction element.

[0008] Alternatively, in a second embodiment of the invention, for testing the valve(s) of the gripping device, each of which controls a suction element or a group of switching elements, it is provided that, after the suction elements and the test devices have been aligned relative to each other, the vacuum suction cups are pressurized with a vacuum, and subsequently the vacuum suction cups of the at least one suction plate and the test devices of the test apparatus are brought into contact. A signal is output from each test device if a change in its initial position is detected. If the initial position of the test device changes, this indicates to the tester that a defect exists in the valve(s).

[0009] This method allows for at least a simple functional check of a large number of vacuum suction cups. Particularly with suction plates containing numerous small suction elements, a time-saving functional test can be performed for both the suction elements and the valve(s) of the gripping device.

[0010] Changes in the initial position of the test device are detected by the shape or position of the test device, or by a combination of both. This enables a simple mechanical design of the test device, as well as reliable detection.

[0011] Furthermore, it is preferably provided that a change in the initial position of the test device is detected and output as a switching position of the test device by at least one optical signal. The output of the at least one optical signal enables simple manual control by the operator as well as automated evaluation. The output of electrical signals by the test device upon a change of state, which can be displayed on a screen or converted into optical signals, also enables simple identification of functional and damaged suction elements as well as valves of the gripping device.

[0012] The test device is preferably placed in a starting position in preparation for the test. If a suction element is assigned to the test device and a vacuum is applied, a change of state occurs, and the test device is moved into a switching position. This active transition to the switching position, for example, generates a signal. This signal can be optical or electrical, allowing for easy identification of the suction element or valve being tested. If no signal change occurs, this indicates that the suction element or valve is no longer functional or at least requires inspection.

[0013] In a first preferred embodiment of the test device for carrying out the method, the test device is designed as a snap disc which, in a starting position of the test device, is oriented opposite to the suction element. After contact with the suction element and the application of a vacuum, the snap disc, if the suction element is functional, is moved into a convex orientation as the switching position. Alternatively, instead of the snap disc, a film with a pole cap-shaped curvature can be provided which, in a starting position of the test device, is oriented concavely to the suction element. When moving into the switching position of the test device, the pole cap-shaped curvature is preferably oriented convexly.Alternatively, the test device can be designed as a flat film which also assumes a convex orientation in the switching position and thus signals that a functional suction element is engaging the test device.

[0014] The switching positions of the test devices can preferably be detected optically and / or haptically by the user, or optically and / or electrically by a sensor, by electrical switching elements, or by writable sensors with magnetic particles. All these embodiments enable simple detection.

[0015] Furthermore, it is preferably provided that the test device is designed as a magnetic disc in a chamber of a mounting plate, which is guided vertically within the chamber and that, after contact with the suction element and application of the vacuum, the magnetic disc is moved from a starting position to a switching position if the suction element is functioning. After the vacuum is switched off and the test device is removed from the suction plate, it can be visually determined which of the vacuum suction devices are functional, namely preferably those in which the magnetic disc has been moved from a lower position in the chamber to an upper position within the chamber. The switching position can be maintained by the magnetic holding force of the magnetic disc.

[0016] Another preferred embodiment of the method provides that the test device indicates the functionality of the suction elements by means of an electrical signal. The test device comprises at least one contact surface on a printed circuit board, to which a switching mat with contacts is assigned. Each contact is located in a pressure cell of the switching mat, and the contacts are positioned at a distance from the contact surfaces in an initial position. After contacting the suction elements and applying a vacuum via at least one bore in the printed circuit board adjacent to the contact surface, a negative pressure is generated in the pressure cell. If a suction element is functional, the contact is brought into contact with the contact surface, and an electrical signal is output. This enables simple and rapid testing.

[0017] Furthermore, in the method for functional testing of vacuum suction cups, it is preferably provided that, after contact between the vacuum suction cups and the test devices and a subsequent movement of the vacuum suction cups relative to the test devices, a signal is output by each test device as soon as a change in the initial position is detected by the test device. In this embodiment of the condition monitoring method, it is provided that an active movement of the test device and / or the at least one suction plate of the gripping device relative to each other causes a change in the test device from an initial position to a switching position, and this change is indicated or not indicated depending on the desired signal output and is evaluated accordingly.

[0018] A simple condition check of the vacuum suction cups is preferably achieved by guiding the test device, a spring-loaded plunger, in a positionally adjustable manner on a mounting plate of the test fixture. The change in the plunger's position from a starting position, achieved by moving the suction plate and the test device relative to each other with increasing distance, is detected by a sensor. When the suction element is functioning, this movement is triggered by a sensor. If the suction element generates the required suction force due to the application of a vacuum, the spring-loaded plunger moves relative to the mounting plate of the test fixture as the distance between the suction plate and the test device increases. This movement can trigger a switching signal.For example, an electrical contact can be provided at the end of the plunger. In its initial position, this contact rests against a contact on a conductor track, thus forming an electrical circuit. Lifting the plunger interrupts this circuit, and the test device is switched to the switching position. This also allows testing to determine whether the suction plate and its vacuum suction cups can still exert the required holding force, ensuring reliable handling of workpieces.

[0019] Furthermore, it is preferably provided that the distance traveled by the at least one suction plate and the test device relative to each other and away from each other is recorded, and that a breakaway force of the suction elements is determined from the recorded distance and a change in the switching position of the test device. This allows for a more detailed assessment of whether, for example, a sufficient holding force can still be generated by the suction element, or whether the holding force is still present, but a replacement is to be expected soon, and therefore such a suction element should be replaced as a precautionary measure.

[0020] Furthermore, it is preferable that the testing device for checking the valves of the gripping device is designed as a spring-loaded plunger, which is guided on the holding plate of the testing device in a positionally adjustable manner. When the plunger's position changes from its initial position, the distance between the at least one suction plate of the gripping device and the testing device increases, and a sensor detects a non-functional valve. The valve is tested by removing the at least one suction plate from the testing device. If the valve is functional, the suction element detaches from the plunger, leaving the plunger in its initial position, thus indicating a functional valve.If the plunger is lifted from its starting position and moved into a switching position, a signal is output during the valve test, indicating that the valve is no longer functional.

[0021] The problem underlying the invention is further solved by a test device comprising a plurality of test devices arranged side by side in a plane on the outer surface of a support arrangement or a housing, wherein each test device is provided in a starting position and can be moved into a switching position, and each test device can be moved into the switching position independently of the other test devices by means of a suction element associated with the test device, and the starting position and / or the switching position can be detected separately in each test device. This enables simple and rapid individual testing of all vacuum suction cups provided on a gripping device.Particularly with small-diameter suction elements and a large number of suction elements arranged on a single suction plate, this enables time-saving testing of some or all vacuum suction elements arranged on at least one suction plate. Furthermore, individual testing and detection, or condition monitoring, of each individual suction element is possible. Since each suction element or group of suction elements is activated by an associated valve, condition monitoring of the respective valve is also possible.

[0022] The test device consists of contact surfaces on a printed circuit board (PCB) to which a switching mat with contacts is assigned. Each contact is located in a pressure cell of the switching mat, positioned at a distance from the contact surface in its initial state. After contact with the suction element and application of vacuum to the PCB, a vacuum is created in the pressure cell via at least one bore in the PCB adjacent to the contact surfaces, causing the contact to make contact with the opposite contact surfaces. This alternative design has the advantage of eliminating mechanically moving parts. The switching mat is preferably made of silicone and is therefore flexible. With this test device, it is also possible to test the reliable blow-off function of the suction elements by creating overpressure in the pressure cell.Preferably, the switching mat can be deflected in both directions, and in particular, contact surfaces are provided on each side of the switching mat, and each contact surface is assigned to at least one contact of a printed circuit board.

[0023] The invention, as well as further advantageous embodiments and developments thereof, are described and explained in more detail below with reference to the examples shown in the drawings. The drawings show: Figure 1 a perspective view of a machining machine and a handling device with a gripping device having a vacuum suction cup, Figure 2 a schematic view from below of a suction plate of the gripping device in Figure 1 , Figure 3 a schematic side view of a first embodiment of a test device for vacuum suction cups in a test position, Figure 4 a schematic partial view of the test device according to Figure 3 , Figure 5a schematic side view of an alternative embodiment of the test device for vacuum suction cups in a test position, Figure 6 a schematic side view of another alternative embodiment of the test device for vacuum suction cups in a test position, Figure 7 a schematic side view of another alternative embodiment of the test device for vacuum suction cups in a test position, Figure 8 a schematic partial view of the test equipment of the test device, Figure 9 a schematic side view of another alternative embodiment of a test device for vacuum suction cups in a test position, Figure 10 a schematic side view of an alternative embodiment of a test device for vacuum suction cups Figure 9 in a test position Figure 11 a schematic side view of another alternative embodiment of a test device for vacuum suction cups in a test position, Figure 12a schematic side view of a test device according to the invention for vacuum suction cups in a test position and Figure 13 a schematic side view of an alternative embodiment of the test device according to the invention for vacuum suction cups in a test position.

[0024] In Figure 1A perspective view of a processing machine 11, which is designed, for example, as a punching machine, is shown. For the selective processing of a plate-shaped workpiece 12, for example in the form of a sheet metal part, a preferably stationary processing unit 21 with a punching head 14 and a punching die (not shown in detail) is provided. Alternatively, a laser punching machine can also be used, in which a laser processing head is provided adjacent to the punching head 14. The workpiece 12 to be processed rests on a workpiece support 16 during processing. The workpiece 12 is held during processing by a holding device 17, which preferably includes clamps 18, and can be moved relative to the punching head 14 in the X-direction of the workpiece plane (X / Y plane) by means of a conventional linear drive 19, indicated by an arrow.The workpiece 12 can be moved in the Y direction of the workpiece plane by moving the workpiece support 16 together with the holding device 17 relative to a base 24, on which the workpiece support 16 is mounted, by means of a conventional linear drive 20, indicated by an arrow. In this way, the workpiece 12 can be moved in the X and Y directions relative to the punching head 14, so that the area of ​​the workpiece 12 to be processed can be positioned within the processing area of ​​the punching head 14. The processing area lies between the punching head 14 and a punching die (not shown), which is interchangeable. Similarly, a laser optic can be arranged in the stationary processing area of ​​the laser processing head in a laser punching machine.

[0025] A handling device 26 is provided on one end face of the workpiece support 16 of the machine tool 11, which may also include a gripping device 27 that can be moved along at least one linear axis 28 from a loading and unloading position 29, 30 for the plate-shaped material 12 to a removal position or waiting position in order to pick up a machined workpiece 36 and, for example, remove it from the machine tool 11 or place it in a magazine 50.

[0026] The gripping device 27 can have a suction frame 34 which includes one or more suction plates 33, as shown in Figure 2is shown in a view from below. Several vacuum suction cups 35 are provided on each suction plate 33. Each of these vacuum suction cups 35 serves as a removal suction cup. According to a first embodiment, the vacuum suction cups 35 consist of a suction element 31, which projects from an outer surface 37 of a housing 38 of the suction plate 33, and a valve 40 associated with a suction element 31 but located within the housing 38 ( Figure 3Alternatively, the vacuum suction cup 35 can consist of a suction element 31, which can be controlled by a valve 40 together with several other suction elements 31 or a group of suction elements 31. These valves 40 can be purely mechanical valves, i.e., so-called passive valves. Such passive valves are switched solely by an airflow, for example, by applying a vacuum. Alternatively, the valve 40 can also be a controllable valve, in particular an electrically controllable valve, such as a solenoid valve. In this embodiment as well, it can be provided that each suction element 31 is assigned a valve 40 or that one valve 40 controls a group of suction elements 31 together. The latter embodiment is, for example, in Figure 5 shown. An electrical control device, not shown in detail, is provided for controlling such controllable valves 40, in particular solenoid valves.

[0027] The suction element 31 can be designed as a bellows or corrugated bellows made of elastic plastic. The suction plate 33 is connected to a vacuum pump via a hose. The valves 40 are controlled to individually actuate the suction elements 31. The number of vacuum suction cups 35, the size of the suction elements 31, and their arrangement in rows, columns, and other grids are arbitrary and can be adapted to the specific handling task. Furthermore, suction elements 31 of different diameters can be provided on a suction plate 33 within one or more suction cup fields 39. In the exemplary embodiment according to Figure 2 For example, three suction cup fields 39, each with five vacuum suction cups 35, are arranged. Each of these suction cup fields 39, and in turn each vacuum suction cup 35 within the suction cup field 39, is preferably separately controllable.

[0028] The suction plates 33 can be attached to the suction frame 34 in the Y and / or Z axis within the XYZ coordinate system, which is in Figure 1 As shown, it can also be driven by at least one linear drive.

[0029] In Figure 3 Figure 1 shows a schematic side view of a test device 41. This test device 41 and the suction plate 33 with the suction elements 31 are arranged in a test position 42 relative to the test device 41. The test device 41 is shown in a partial top view. Figure 4 The test device 41 comprises a housing or a support arrangement 44 which has a contour corresponding to a suction field 39 of the suction plate 33 or to several suction fields 39 of the suction plate 33 or to the suction plate 33 itself. The test device 41 can also have a planar extent corresponding to several suction plates 33 on the suction frame 34.

[0030] According to the first exemplary embodiment, the support arrangement 44 is rectangular and essentially conforms to the contour of the suction plate 33. Figure 2 corresponds.

[0031] The test device 41 has several test devices 45. Preferably, the number of test devices 45 corresponds to the number of vacuum suction cups 35 of the suction plate 33. Alternatively, the number of test devices 45 on the test device 41 can also correspond to the number of vacuum suction cups 35 of a suction cup array 39 of the suction plate 33.

[0032] The test device 45 of the test apparatus 41 is designed according to the first in Figures 3 and 4In the illustrated embodiment, the film 46 is formed by a foil that is clamped in a frame 47 of the support arrangement 44. This film 46 has pole-cap-shaped bulges 48, which may be embossed into the film 46. The bulges 48 are arranged concavely to an outer surface of the support arrangement 44 or a housing or test device 41 in a starting position 49. Opposite the film 46, a base 51 of the support arrangement 44 is provided. This base 51 is preferably transparent. Alternatively, the base 51 can be omitted.

[0033] To test the vacuum suction cups 35, in particular the suction elements 31, the test devices 45 of the test fixture 41 and the suction elements 31 of the suction plate 33 are aligned and moved towards each other so that a suction opening edge 32 of the suction elements 31 rests on the test fixture 41 and preferably surrounds the test device 45. A vacuum is then applied, which acts on the test device 45 via the suction elements 31. If the suction element 31 is functional, the test device 45 is moved from the initial position 49 to a switching position 52. This switching position 52 can be self-holding. However, this switching position 52 can also remain in place only as long as the vacuum is applied and acts on the test device 45 via the vacuum suction cup 35.

[0034] If the test device 45 is moved to switching position 52, this means that the suction element 31 is functional. If the test device 45 remains in the initial position 49, the suction element 31 is non-functional. It requires testing and, if necessary, replacement.

[0035] By viewing the test device 41 from below, it is possible to visually determine which of the vacuum suction cups 35 are in good working order and which are damaged. This can be determined by moving the respective test device 45 to its switching position 52. Alternatively, instead of visual inspection by the operator, visual detection can be performed using at least one image acquisition device. Furthermore, if the test devices 45 are self-retaining, it can be provided that, after switching off the vacuum and removing the test device 41 from the suction plate 33, it is possible to view the test device 41 from above and perform an evaluation.

[0036] An alternative embodiment of the test device 41 according to Figure 3The test device 45 is characterized by the fact that, instead of pole-cap-shaped bulges 48, it has so-called snap discs. These snap discs can be in the initial position 49 analogous to the concavely oriented pole-cap-shaped bulge. After the suction elements 31 are positioned relative to the test device 45 and the vacuum is applied, these snap discs can be moved towards the interior of the suction elements 31. A clicking sound indicates that functional vacuum suction cups 35 are present. Furthermore, these snap discs are self-locking in the switching position 52. This allows for the identification of functional and non-functional vacuum suction cups 35 by means of an optical inspection.

[0037] Another alternative embodiment of the test device 41 according to Figure 3The design provides for a film 46 in the support arrangement 44, which is clamped in the frame 47 and is designed as a continuously flat surface. As soon as the suction element 31 comes into contact with this film 46 and is subjected to a vacuum, the film 46 transitions from a flat initial position 49 to a switching position 52 and, with a functioning suction element 31, exhibits a convex curvature. This also enables testing of the vacuum suction cups 35.

[0038] In the embodiment of the test device 41 according to Figure 3 and the described alternatives thus result in a triggering or a change of the initial position 49 to the switching position 52 by means of negative pressure.

[0039] In Figure 5 is an alternative embodiment of the test device 41 to Figures 3 and 4 This embodiment of the test device 41 can be found in the structure of the one described in Figure 3The first and second alternatives of the test device 41 described above correspond to the test device 45. The test device 45 is thus formed from a film 46 with pole-cap-shaped protrusions 48 or with so-called snap discs. A writable sensor 54 is assigned to this film 46. This writable sensor 54 extends over a surface area, analogous to the test devices 45. Each pole of the pole-cap-shaped protrusion 48 or each downward-facing edge of the snap disc is in contact with the writable sensor 54 in the initial position 49. As soon as the suction element 31 rests on the film 46 and a vacuum is applied, the test device 45 can be moved from the initial position 49 to the switching position 52, provided the suction element 31 is functioning. This causes the pole 56 to no longer be in contact with the sensor 54. This can cause an optical change.For example, the writable sensor 54 can consist of a multitude of magnetic particles which, in the initial state 49, cause, for instance, a blackening in the area of ​​pole 56. In the switching position 52, the writable sensor 54 returns to an initial state or an initial color. The above can also be reversed.

[0040] In Figure 6 is an alternative design of the test device 41 to Figure 3 shown. In this embodiment in Figure 6 The suction element 31 is shown, for example, as a cup-shaped suction element. Both the bellows-shaped and the cup-shaped suction element 31 can be used optionally in all embodiments.

[0041] In this embodiment Figure 6 is also in addition to the in Figure 3In the described embodiments of the test device 41, each test unit 45 is assigned an optical sensor 58. This sensor can be one or more image acquisition devices, such as a CCD camera. It can detect both the initial position 49 and the switching position 52 and output the acquired data to a control and data processing unit 59. Preferably, a display can be provided on the data processing unit 59 to indicate the position of the functional and / or non-functional suction elements 31. This facilitates replacement.

[0042] As an alternative to the optical sensor 58, a proximity switch can also be provided which detects the change of the test device 45 from the initial position 49 to the switching position 52.

[0043] In Figure 7 is another alternative embodiment of the test device 41 to Figure 3This test device 41 comprises a test assembly 45, which is formed from a film 46 with pole-cap-shaped bulges 48 or from a film 46 with snap discs. An electrically conductive contact surface 61 is formed at the poles 56 or the downward-facing edges of the snap disc, which bears against an electrical sensor 63 in a starting position 49. The electrical sensor 63 can be designed as a printed circuit board 81, which has a plurality of conductor tracks 64, each leading to a contact 65 that is associated with the pole-cap-shaped bulge 48 of the film 46 or the edges of the snap disc of each test assembly 45. Figure 8In the initial position 49, a conductive contact exists between the pole-cap-shaped bulge 48 or the snap disc and the contact 65 of the electrical sensor 63. As soon as the test device 45 is moved to the switching position 52, this electrical contact is interrupted. This allows the control and data processing unit 59 to precisely determine the position of the functional and / or non-functional suction element 31.

[0044] In Figure 9A further alternative embodiment of the test device 41 is shown. The test device 45 consists of a chamber 71 in the housing or support arrangement 44, in which a disk 72, preferably a magnetic disk 72, is mounted so as to be movable up and down. An upper layer or plate 75, which partially covers the chamber 71, is made of a magnetic material. A first bore 73 and a second bore 74 are provided on the opposite side of the housing 44, facing the suction element 31, both of which open into the chamber 71 from the outside.

[0045] As soon as the suction element 31 is in contact with the test device 45 and a vacuum is applied, a functioning suction element 31 causes the disc 72 to deflect from a starting position 49 to the switching position 52. If the disc 72 is designed as a magnet, it remains in the switching position 52 after the suction plate 33 is removed from the plate 75 of the test device 41, so that an evaluation can then take place.

[0046] In the embodiments of the test device 41 described above, it is provided that, in order to carry out the condition check, after positioning the vacuum suction cups 35 and the suction plate 33 to the test device 41 and aligning them to the respective test equipment 45, a vacuum is created when the suction plate 33 is in a stationary position relative to the test device 41.

[0047] In Figure 10 is an alternative embodiment of the test device 41 to Figure 9The test device 41 is, for example, formed from three layers or plates. The uppermost plate 75 is made of a magnetic material. This magnetic plate 75 rests on a non-magnetic layer 94. The chambers 71 are formed in this non-magnetic layer 94. Opposite the magnetic layer or plate 75, another layer or plate 95 is associated with the non-magnetic layer 94. This can be made of a non-magnetic material. Preferably, this layer is magnetic. The bores 74, which open into the chamber 71, are provided in this layer 95.

[0048] Furthermore, in this embodiment, the bores 73 provided in the upper layer 75 are designed to be as large as possible, but with a small projection relative to the circumferential wall of the chamber 71, so that the disk 72 arranged in the chamber 71 cannot detach from the chamber 71. The diameter or cross-sectional geometry of the suction elements 31 is matched to the cross-sectional geometry of the bore 73, so that the suction element 31 can be moved through the first bore 73 into the chamber 71 or positioned in the chamber 71.

[0049] To perform a test of the suction elements 31, this embodiment provides that the suction plate 33 is moved towards the test device 41, so that each suction element 31 is assigned to a test device 45. Subsequently, the suction elements 31 each immerse themselves in the chamber 71. After the suction element 31 rests on the disk 72 in the initial position 49, the vacuum is applied. The suction plate 33 and the test device 41 are then moved away from each other. This can be achieved by a relative movement of the two or simply by a traversing movement of the suction plate 33 or the test device 41. If the suction element 31 is functional, the disk 72 is moved from the initial position 49 to the switching position 52. The disk 72 is held in this position 72 against the plate 75 by the magnetic holding force. The vacuum applied to the suction plate 33 is then switched off, and the suction elements 31 are lifted.A subsequent visual inspection reveals that the disc 72, remaining in the initial position 49, indicates the position of a defective suction element 31. When the disc 72 is moved to the switching position 52, a signal change is output, for example, indicating that this suction element 31 is functional.

[0050] In Figure 11A further alternative embodiment of the test device 41, compared to the embodiments described above, is shown in a side view. In this embodiment of the test device 41, the test unit 45 has a plunger 76 that can be moved up and down. This plunger 76 has a contact surface 77 for receiving the suction element 31. The plunger 76 is guided in a retaining plate 78 and is movable up and down relative to it. A force storage element 79 positions the plunger 76 in an initial state or starting position 49. In this starting position 49, a contact surface 61 formed on the plunger 76 rests against a contact 65 on the base 51. An electrical sensor 63 can again be provided here, as shown in Figures 7 and 8As described above, to test the suction element 31, the suction plate 33 is aligned and positioned relative to the test device 41, and the suction elements 31 are brought into contact with the test devices 45. In this case, the suction opening edges 32 of the suction elements 31 rest against the contact surface 77 of the respective plunger 76. The vacuum is then applied. In this embodiment, it is additionally provided that a relative movement is initiated between the suction plate 33 and the test device 41. The suction plate 33 can be lifted relative to the test device 41, or the test device 41 can be lifted relative to the suction plate 33, or a relative movement occurs between them by moving the suction element 31 and the test device 41 away from each other. If the suction element 31 is functional, the test device 45 is moved into a switching position 52. This means that the plunger 76 is removed from the position shown in the original text. Figure 11 The plunger 76 lifts off the starting position 49 shown. The contact surface 61 of the plunger 76 is separated from the contact 65. This transmits a signal to the data processing unit 59, indicating that this suction element 31 is functional. If the test device 45 remains in the starting position 49, no signal change occurs, and this is evaluated as a non-functional suction element 31.

[0051] The described testing equipment also makes it possible to check the condition of the respective valve that activates the suction element under test.

[0052] Furthermore, in this embodiment of the test device 41 ( Fig. 11The holding / breakaway force of the suction elements 31 is determined. A travel distance, through which the suction plate 33 and the test device 41 are moved away from each other, is recorded. During a lifting phase of the plunger 76, the test device 45 is in a switching position 52. At the moment the suction element 31 breaks away from the test device 45, in particular from the contact surface 77, the test device 45 returns to its initial position 49. This signal can also be recorded and evaluated together with the traveled distance to determine the breakaway force of the suction element 31, or a defined travel distance corresponding to a predetermined holding force can be covered. Based on the determined result, the existing holding force of the suction element(s) can be inferred.

[0053] The in Figure 11The described test device 41 is also intended for testing or for condition monitoring of the respective valve 40 of the vacuum suction cups 35. The suction plate 33 is positioned and aligned in a raised position relative to the test device 41 and the test unit 45. The test units 45 are in the initial position 49, as shown in Figure 11The vacuum suction cups 35 are then pressurized with a vacuum. Subsequently, the vacuum suction cups 35 are brought into contact with the test devices 41. Following this, the suction plate 33 is lifted from the test device 41, or the test device 41 is lifted from the suction plate 33, or both are moved away from each other. This preferably occurs along a predetermined path. If the vacuum suction cup 35 moves the test device 45 even slightly from its initial position 49 towards the switching position 52, a signal is generated due to the interruption between the contact 65 and the contact surface 61. This signal is then evaluated.

[0054] In Figure 12Figure 1 shows a test device 41 according to the invention and defined in the accompanying claim 12. The test device 41 in turn has a plurality of test elements 45. It is provided that a top surface of the support arrangement 44 is designed as a printed circuit board 81. Each test element 45 has contacts 65. A switching mat 82 is arranged between the printed circuit board 81 and the base 51 of the support arrangement 44. This switching mat 82 has a pressure cell 83 to form the test element 45, within which a contact surface 61 is provided. This contact surface is located opposite the contact 65. At least one bore 84, provided in the printed circuit board 81, opens into the pressure cell 83. Bores 85 are also preferably provided in the base 51 in the area of ​​the pressure cell 83. These bores 85 are covered by the switching mat 82. The switching mat 82 is preferably made of silicone.

[0055] As soon as the suction elements 31 are in contact with the test device 41, a vacuum is applied. A negative pressure is generated in the pressure cell 83 via the bores 84. The contact surface 61 is moved towards the contact 65. The contact surface 61 is moved from the initial position 49 to a switching position 52. A signal is output when the contact surface 61 makes contact with the contact 65. The functionality of the suction element 31, which is assigned to the test device 45, is verified. The bore 85 prevents the generation of a suction effect that could counteract a deflection movement of the contract surface 61 or the suction mat 82 from the initial position 49 to the switching position 52.

[0056] Alternatively, it can be provided that an air cushion or compressed air is additionally applied to the switching mat 82 via the bores 85 in the base 51. This allows a switching point between the initial position 49 and the switching position 52 of the switching mat 82 to be changed.

[0057] This embodiment described above has the advantage that no mechanically moving parts are required. Furthermore, it offers a cost-effective design.

[0058] In Figure 13An alternative embodiment of the test device 41 according to the invention is shown. This embodiment of the test device 41 has a plurality of test elements 45. These test elements 45 are formed by a first layer 88 and a second layer 89, which are preferably designed as a perforated layer. In particular, a perforated silicone film is provided. The size of the perforations is preferably adapted to the size of the contacts 65 on the upper and / or lower circuit board 81. A third layer 91 is provided between the two layers 88 and 89. This is preferably designed as a closed silicone film. On this third layer 91, contact surfaces 61 are preferably provided, one facing the upper circuit board 81 and the other facing the lower circuit board 81.The distance between the contact surfaces 61 and the contacts 65 of the circuit boards 81 is designed such that, in the event of a negative pressure in the pressure cell 83, the contact surface 61 can come into contact with the contact 65 of the upper circuit board 81. This pressure cell 83 is then pressed against a Figure 13 The initial position 49 shown is transformed into a switching position 52, which is, for example, the one shown in Figure 12 The third layer 91 can be deflected in the opposite direction under applied overpressure and moved into a switching position 52, as shown in Figure 13The deflection of the third layer 91 is therefore dependent on the test to be performed and can occur both in the direction of the upper circuit board 81 or the suction elements 31, and in the direction of the lower circuit board 81 or away from the suction elements. The test device 41 thus forms a differential pressure membrane by means of the third layer 91 between the two layers 88, 89. This allows both an overpressure and a vacuum to be generated in the pressure cell 83. The pressure cell 83 in Figure 13 In principle, its construction corresponds to pressure cell 83 in Figure 12Because the third layer 91 can be deflected towards both the upper and lower circuit boards 81, the pressure cell 83 can function as either a negative pressure or positive pressure cell, depending on how the valve 40 or the suction element 31 is controlled. For example, during testing, the valve 40 can be pressurized to cause a workpiece to be blown off the gripping device 27. To test this, the test fixture 41 is positioned in the initial position 49 relative to the suction elements 31. The valve 40 is pressurized. As soon as the contact surface 61 on the third layer 95 makes contact with the contact 65 on the lower circuit board 81 and assumes a switching position 52, it is detected that the required positive pressure for blowing off has been built up and is present.If no such contact is detected and the third layer 91 with the contact surface 61 remains in the initial position 49, it is recognized that the valve 40 is not opening and thus a defect in the valve 40 exists. Test devices 45 are formed by a first layer 88 and a second layer 89, which are preferably designed as a perforated layer. In particular, a perforated silicone film is provided. The size of the perforations is preferably adapted to the size of the contacts 65 on the upper and / or lower circuit board 81. A third layer 91 is provided between the two layers 88 and 89. This is preferably designed as a closed silicone film. On this third layer 91, contact surfaces 61 are preferably provided facing the upper circuit board 81 and facing the lower circuit board 81.The distance between the contact surfaces 61 and the contacts 65 of the circuit boards 81 is designed such that, in the event of a negative pressure in the pressure cell 83, the contact surface 61 can come into contact with the contact 65 of the upper circuit board 81. This pressure cell 83 is then pressed against a Figure 13 The initial position 49 shown is transformed into a switching position 52, which is, for example, the one shown in Figure 12 The third layer 91 can be deflected in the opposite direction under applied overpressure and moved into a switching position 52, as shown in Figure 13The deflection of the third layer 91 is therefore dependent on the test to be performed and can occur both in the direction of the upper circuit board 81 or the suction elements 31, and in the direction of the lower circuit board 81 or away from the suction elements. The test device 41 thus forms a differential pressure membrane by means of the third layer 91 between the two layers 88, 89. This allows both an overpressure and a vacuum to be generated in the pressure cell 83. The pressure cell 83 in Figure 13 In principle, its construction corresponds to pressure cell 83 in Figure 12Because the third layer 91 can be deflected towards both the upper and lower circuit boards 81, the pressure cell 83 can function as either a negative pressure or positive pressure cell, depending on how the valve 40 or the suction element 31 is controlled. For example, during testing, the valve 40 can be pressurized to cause a workpiece to be blown off the gripping device 27. To test this, the test fixture 41 is positioned in the initial position 49 relative to the suction elements 31. The valve 40 is pressurized. As soon as the contact surface 61 on the third layer 95 makes contact with the contact 65 on the lower circuit board 81 and assumes a switching position 52, it is detected that the required positive pressure for blowing off has been built up and is present.If such contact is not detected and the third layer 91 with the contact surface 61 remains in the initial position 49, it is recognized that the valve 40 does not open and therefore there is a defect in the valve 40.

Claims

1. A method for checking the state of vacuum suctioning devices (35) of a gripping apparatus (27), a vacuum being placed on the devices for the purposes of gripping workpieces (12, 36), wherein each vacuum suctioning device (35) has a suction element (31) engaging on the workpiece (12, 36), and each suction element (31), or a group of suction elements (31), is actuated by at least one valve (40), - in which at least one suction plate (33) of the gripping device (27), said plate comprising a plurality of vacuum suctioning devices (35), and a testing device (41) which comprises a plurality of testing apparatuses (45) are aligned with one another so that each vacuum suctioning device (35) lies opposite to a testing apparatus (45), wherein each testing apparatus (45) is arranged in an initial state (49), and - in which, to test the suction elements (31), the suction elements (31) of the vacuum suctioning devices (35) of the at least one suction plate (33) and the testing apparatuses (45) of the testing device (41) are brought into contact and a vacuum is placed on the vacuum suctioning devices (35), or - in which, for the testing of the at least one valve (40), a vacuum is placed on the valve or valves (40) of the gripping apparatus (27) and the vacuum suctioning devices (35) of the at least one suction plate (33) and the testing apparatuses (45) of the testing device (41) are brought into contact, and - in which, for the respective testing of the suction elements (31) or of the at least one valve (40), a signal is output by each testing apparatus (45) of the testing device (41) as soon as a change with respect to the initial state (49) is detected at the testing apparatus (45), characterized in that a change in the initial state (49) of the testing apparatus (45) is detected in the form or position of the testing apparatus (45) or, in a combination, by the shape and position of the testing apparatus (45).

2. The method according to claim 1, characterized in that a change in the initial state (49) of the testing apparatus (45) into a switching position (52) of the testing apparatus (45) is output by at least one optical or electrical signal.

3. The method according to any one of the preceding claims, characterized in that a signal is output by each testing apparatus (45) if a change in the initial state (49) is detected at the testing apparatus (45) after the contacting of the vacuum suctioning devices (35) with the testing apparatuses (45) and the placement of a vacuum on the vacuum suctioning devices (35).

4. The method according to claim 3, characterized in that the testing apparatus (45) is designed as a snap-action disk which is oriented in the opposite direction to the suction element (31) in an initial state (49), or in that the testing apparatus (45) is designed as a film (46) with at least one polar cap-shaped curvature (48) which is aligned concavely with respect to the suction element (31), or in that the testing apparatus (45) is designed as a flat film (46), and in that, after the testing apparatus (45) contacts the suction element (31) and the application of the vacuum in the case of a functional suction element (31), the snap-action disk or the film (46) with the at least one polar cap-shaped curvature (48) or the flat film (46) is transitioned to a convex orientation as the switching position (52).

5. The method according to claim 4, characterized in that the switching position (52) of the testing apparatuses (45) is detected optically or haptically by a worker or in that the switching position (52) of the testing apparatuses (45) is detected by an optical sensor (58), an electrical sensor (63) or an electrical switching element or a writable sensor (54).

6. The method according to any one of claims 1 to 3, characterized in that the testing apparatus (45) is designed as a disk (72), in particular a magnetic disk, in a chamber (71), the disk being guided in a height-variable manner within the chamber (71), and in that, after this testing apparatus (45) contacts the suction element (31) and the subsequent application of the vacuum in the case of a functional suction element (31), the disk (72) is transitioned from a starting position (49) in the chamber (71) to a switching position (52) in the chamber (71).

7. The method according to any one of claims 1 to 3, characterized in that the testing apparatus (45) is designed from contacts (65) on a printed circuit board (81) to which a switching mat (82) with contact surfaces (61) in a pressure cell (83) is assigned and which are positioned at a distance from one another in an initial state (49) and, after the suction elements (31) makes contact on the testing apparatus (45) and the applying of a vacuum to the vacuum suctioning devices (35), a negative pressure is generated in the pressure cell (83) via at least one bore (84) in the printed circuit board (81) adjacent to the contacts (65), and in the case of a functional suction element (31), the contact surface (61) bears against the contact (65) and a signal is output.

8. The method according to any one of claims 1 or 2, characterized in that, after the contact between the vacuum suctioning devices (35) and the testing apparatuses (45) and a subsequent displacement movement of the vacuum suctioning devices (35) relative to the testing apparatuses (45), a signal is output by each testing apparatus (45) as soon as a change in an initial state (49) is detected by the testing apparatus (45).

9. The method according to claim 8, characterized in that the testing apparatus (45) is guided as a spring-mounted tappet (76) positionally variably on a retaining plate (78) of the testing apparatus (41), and the change in the position of the tappet (76) from an initial state (49) due to a travel movement of the suction plate (33) and the testing device (41) away from one another into a switching position (52) in the case of a functional suction element (31) is detected by a sensor.

10. The method according to claim 9, characterized in that a distance of the displacement movement of the suction plate (33) and the testing apparatus (45) relative to one another is detected and a tear-off force and / or holding force of the suction element (31) is determined by the testing apparatus (45) from the detected path and a change in the switching state of the testing apparatus (45).

11. The method according to claim 8, characterized in that the testing apparatus (45) is guided positionally variably on the holding plate (78) of the testing device (41) as a spring-mounted tappet (76) and, in the event of a change in the position of the tappet (76) from the initial state (49) due to displacement movement of the suction plate (33) and the checking device (45) away from one another into a switching position (52) in the case of a non-functional valve (40) is detected by a sensor.

12. A testing device for checking the state of vacuum suctioning devices (35) of a gripping device (27), wherein each vacuum suctioning device (35) has a suction element (31) engaging on the workpiece (12, 36), and at least one valve (40) is assigned to each suction element (31) or to a group of suction elements (31), wherein the testing device has a plurality of testing apparatuses (45) which are arranged next to one another in a plane and are arranged toward an outer side of a support arrangement (44), wherein - each testing apparatus (45) is provided in an initial position (49) and can be transitioned to a switching position (52), and - each testing apparatus (45) can be transitioned to the switching position (52) independently of the other testing apparatus (45), and - the initial position (49) and / or the switching position (52) of each testing apparatus (45) can be detected separately, characterized in that each testing apparatus (45) comprises contacts (65) on at least one printed circuit board (81), the contacts being assigned to a switching mat (82) with contact surfaces (61) in a pressure cell (83) and being positioned at a distance from one another in an initial state (49) and, after the contacting of one of the suction elements (31) on the testing apparatus (45), a negative pressure or a positive pressure is generated in the pressure cell (83) via at least one bore (84) adjacent to the contacts (65), and in the case of a functional suction element (31) or valve (40) the contact surface (61) bears against the contact (65) and a signal is output.