EP3600711B1 - Device and method for removing a workpiece part from the rest of the workpiece - Google Patents

Description

The present invention relates to a device for removing an electrically conductive workpiece part from an electrically conductive remaining workpiece, comprising: a holding device movable in a removal direction, which can be switched between a fixing state for fixing the workpiece part on the holding device and a release state for releasing the workpiece part from the holding device , wherein the holding device has at least one electrically conductive first contact element for contacting the workpiece part at at least one first contact point, in particular a plurality of electrically conductive and electrically conductively interconnected first contact elements for contacting the workpiece part at a plurality of first contact points, and wherein the holding device at least one electrically conductive second contact element for contacting the workpiece part at at least one second contact point, in particular a plurality of electr isch conductive and electrically conductively interconnected second contact elements for contacting the workpiece part at a plurality of second contact points. The invention also relates to an associated method for removing a workpiece part from a remaining workpiece. The workpiece from which the workpiece part and the remaining workpiece are formed are typically plate-like, electrically conductive components, for example metal sheets.

From the DE 10 2014 209 811 A1 a device for the mutual separation of two workpiece parts of a plate-like workpiece has become known, one of which forms a removal part and the other forms a residual part. The device comprises a workpiece support which defines a support plane. On one side of the storage level there is a lifting device, on the opposite side of the storage level there is a counter holder which can be transferred into a fixation state and into a release state. To separate the two workpiece parts, the removal part acted on by the lifting device on the one hand and supported by the counter holder on the other hand can be moved in a lifting direction by means of the lifting device perpendicular to the storage plane relative to the remaining part with a removal movement.

The manual and, in particular, the automated removal of a workpiece part produced during the separating processing of workpieces, for example when punching or (laser) cutting sheet metal, from the remaining workpiece is difficult, since the workpiece part and the remaining workpiece are usually in a common , are located on the workpiece plane defined by a workpiece support and are only separated from one another by a narrow separating gap. When the workpiece part is unloaded, it can therefore jam on the remaining workpiece. The possible consequences are interruptions in production but also damage to the workpiece part to be removed and possibly the device used to remove the workpiece part.

For the process reliability in the automated removal of a workpiece part from a remaining workpiece, it is necessary to check whether the workpiece part was completely separated from the remaining workpiece during the previous separating machining by means of a machining tool or whether the workpiece part is possibly still in contact with the remaining workpiece, for example because it is on the remainder of the workpiece tilted or still with the remainder of the workpiece over a thin web connected is. For process reliability during automated removal, it is also necessary to check whether the workpiece part is fixed on the holding device during movement in the removal direction and during subsequent transport to store the workpiece part in a magazine or the like, which can include one or more suction grippers, for example .

From the DE 102 59 190 B3 a device for detecting the material on the surface of flat objects on a stack, for example printing plates, has become known, which device can be integrated into a lifting device with suction devices for printing plates. For this purpose, the surface is contacted with sensor electrodes and a measuring current is passed through the surface. On the basis of the determined current strength, a distinction is made between which material the object surface consists of. The material surfaces that can be distinguished in this way can be, for example, paper on a printing plate or a printing plate.

In the DE 101 44 048 A1 a device for handling cover glasses for microscope slides is described which has a base block in which at least two receiving means are provided. Between the two receiving means, a sensor can be provided in the base block which determines the presence or the state of a received cover glass. The sensor can be designed as a capacitive sensor.

JPH04-293250A discloses a substrate holder for a wafer in which two capacitive thin-film sensors are embedded in a trench for holding the wafer. In the U.S. 6,024,393 describes a sheet for handling a semiconductor substrate in which at least one capacitive sensor is embedded.

Object of the invention

The invention is based on the object of providing a device and a method which improve the process reliability when removing a workpiece part from a remaining workpiece.

Subject of the invention

This object is achieved according to the invention by a device of the type mentioned at the outset, the device having a sensor device which is designed, based on the first and second contact elements, to completely separate the workpiece part from the remaining workpiece in a first test state and to fix the workpiece in a second test state To check the workpiece part on the holding device in the fixed state.

On the one hand, the sensor device of the device according to the invention enables, in a first test state, a test to determine whether the workpiece part has been completely separated from the remaining workpiece or whether it is still in contact with the remaining workpiece. In the latter case, there is an electrically conductive connection between the (electrically conductive) workpiece part and the (electrically conductive) remaining workpiece. The contact elements can be used to check whether or not there is an electrical connection between the workpiece part and the remaining workpiece. The check as to whether the workpiece part has been completely separated from the remaining workpiece is typically carried out when the workpiece part has been moved in a removal movement in the removal direction out of the workpiece plane so far that it is above the surface of the remaining workpiece.

The second test state of the sensor device is typically used when the workpiece part has been moved out of the workpiece plane in a removal movement in the removal direction and the separation from the remaining workpiece has been tested. In order to check in a position of the workpiece part spaced apart from the remaining workpiece in the removal direction whether the workpiece part is fixed to the holding device, it can be checked whether the at least one first and the at least one second contact element are electrically connected to one another via the workpiece part.

In one embodiment, the sensor device is designed, in the first test state, an electrical resistance between the at least one first and / or to determine the at least one second contact element on the one hand and a reference potential on the other hand. The electrical resistance is determined using known measurement methods by connecting the contact elements to a current or voltage source and measuring the current strength or a voltage drop. The remaining workpiece can be held at a reference potential, for example, via electrically conductive clamping claws or via a workpiece support on which the workpiece part and the remaining workpiece lie, which can be, for example, the ground potential of the device or the processing machine in which the Device is usually integrated. In the first test state, in which it is checked whether the workpiece part has been completely separated from the remaining workpiece, either the first electrically conductive contact element or the second electrically conductive contact element or both are electrically conductive to the ground potential of the device for workpiece removal or to the ground potential of the processing machine , in which the device for removing the workpiece is integrated. If the workpiece part is still in contact with the remaining workpiece, a closed circuit is created when a voltage is applied between the contact elements on the one hand and the ground potential on the other, and a very low electrical resistance is measured between the contact elements and the ground potential. If, on the other hand, the workpiece part is completely detached from the remaining workpiece, the current flow to the remaining workpiece is interrupted, so that a high resistance is established between the contact elements on the one hand and the ground potential on the other. The device according to the invention can each have a plurality of first and second contact elements which are each conductively connected to one another in a group. In this way, the process reliability of the measurement can be increased.

The sensor device is preferably also designed to determine an electrical resistance between at least one first contact element and at least one second contact element in the second test state. In order to check in a position of the workpiece part at a distance from the remaining workpiece in the removal direction, whether the workpiece part is fixed to the holding device, a voltage is applied by means of the sensor device in a second test state applied between the first and the second contact element and determined an electrical resistance between the contact elements. If a plurality of first and second contact elements are present, an electrical resistance is determined between the plurality of electrically conductively interconnected first contact elements on the one hand and the plurality of electrically conductively interconnected second contact elements on the other hand. If the workpiece part is fixed to the holding device, at least one first contact element contacts the workpiece part at a first contact point and at least one second contact element contacts the workpiece part at a second contact point, so that the first and second contact elements are connected in an electrically conductive manner via the workpiece part. Correspondingly, when the workpiece part is fixed on the holding device, a lower electrical resistance is measured between the first and second contact elements than in the event that the workpiece part is no longer fixed on the holding device. In the latter case there is no electrical contact between the first and second contact elements and the electrical resistance is practically infinite.

For the tests described above, it is necessary that at least one first contact element come into contact with the workpiece part at one of the first contact points and at least one second contact element at one of the second contact points. In order to be able to carry out these tests even with comparatively small workpiece parts to be removed, the first and second contact points or the corresponding first and second contact elements should not be arranged too far apart from one another on the holding device.

In one embodiment, the holding device has a plurality of holding elements for fixing the workpiece part, the holding elements being switchable between a fixing state for fixing the workpiece part and a release state for releasing the workpiece part. The holding elements are spaced apart from one another on the holding device, typically in a regular arrangement, for example in a grid arrangement.

In a further development, the holding elements are designed as suction grippers. At Holding elements in the form of suction grippers, the fixing state is achieved by applying a vacuum or by a negative pressure by which the workpiece part is held on the suction gripper. In the case of suction grippers with passive flow valves, the detection of whether the workpiece part is fixed to the suction gripper is not possible via the vacuum or via a negative pressure generator, since with such suction grippers the flow valves also close if the workpiece part is not fixed to the suction gripper .

In a further embodiment, the at least one first contact element and / or the at least one second contact element are formed on the holding elements. In this case, individual or all of the holding elements, for example in the form of suction grippers, are made of an electrically conductive material, at least on one side that is brought into contact with the workpiece part or the remaining workpiece. For example, in this case, folded suction cups of the suction grippers, which are used to contact the workpiece part or the remaining workpiece, can be formed from an electrically conductive plastic. In this case, the first and second contact points coincide with the fixing points of the holding elements. In this case, however, there is the problem that the two tests described above are not possible on workpieces or sheets with foil or rust, since the foil or rust layer applied to the surface is generally not electrically conductive.

In a further development, the first contact element (s) and / or the second contact element (s) are / are arranged between the holding elements. Like the holding elements, the first or the second contact elements can also be arranged in a regular arrangement or in a grid on the holding device. Since holding elements in the form of suction grippers have an essentially circular geometry, at least on the inlet side on which the fixation or suction takes place, there is usually enough space between the suction grippers to arrange contact elements between the suction grippers.

In a further embodiment, first contact elements alternate with second ones in at least one direction perpendicular to the removal direction Contact elements. The holding device or the holding elements are typically integrated in a substantially plate-shaped housing which extends in a plane perpendicular to the removal direction. The first and second contact elements alternate in at least one direction in this plane. If the holding elements are arranged in a grid, a respective holding element can be arranged in one or in both directions of the grid between a first contact element and a second contact element. It goes without saying that the contact elements do not necessarily have to alternate in more than one direction in order to carry out the tests described above. However, the distance between the first and second contact elements or between the first and second contact points should not be too large so that the tests described above can also be carried out on small workpiece parts.

In a further embodiment, the first contact elements and / or the second contact elements have resilient contact pins for contacting the workpiece part or the remaining workpiece. If the holding device has a rigid abutment, for example in the form of a flat contact surface, in which bores are made for receiving the holding elements, for example in the form of suction grippers, as cited in the introduction DE 10 2014 209 811 A1 is described, the contact pins of the first and the second contact elements typically protrude with their free end over the flat contact surface and are pressed in when the workpiece part or the remaining workpiece presses against the flat contact surface, the electrical contact being established. The use of resilient contact pins, if dimensioned appropriately, makes it possible, in the case of foiled or rust-bearing sheets, to slightly scratch the sheet or rust layer and in this way to establish electrical contact with the sheet below.

In a further embodiment, the first contact elements and the second contact elements are each connected to one another in an electrically conductive manner via conductor tracks on the same circuit board. It goes without saying that the conductor tracks which connect the first contact elements to one another in an electrically conductive manner and the conductor tracks which connect the second contact elements to one another in an electrically conductive manner are not in an electrically conductive connection to one another. The contact elements are in this case attached to the circuit board and can be arranged at a comparatively small distance from one another.

In an alternative embodiment, the first contact element (s) are attached or fastened to a first electrically conductive component and the second contact element (s) to a second electrically conductive component offset in the removal direction to the first . The first and the second electrically conductive component are electrically isolated from one another. The two components can be designed, for example, as electrically conductive perforated plates into which the contact element or elements are screwed. In this case, second contact elements, which are fastened to the second perforated plate, can be guided through the first perforated plate via an electrically insulating spacer (electrically insulated).

In a further embodiment, the device comprises at least one lifting device which can be moved in the removal direction to remove the workpiece part from the remaining workpiece, the workpiece part being held between the at least one lifting device and the holding device during at least part of the removal. The lifting device engages the workpiece part on the side opposite the holding device and serves to support or support the workpiece part. The holding device serves as a counter-holder and enables the workpiece part to be stored during movement in the removal direction between the lifting device and the holding device perpendicular to the workpiece plane, so that it does not get caught on the remaining workpiece during removal. The lifting devices can be designed, for example, in the form of lifting pins which can be actuated in a controlled manner independently of one another. The lifting devices are actuated in such a way that the workpiece part is aligned parallel to the workpiece plane when it is moved in the removal direction.

Another aspect of the invention relates to a processing machine for the separating processing of plate-like electrically conductive workpieces, in particular sheet metal, by means of a processing tool, for example a laser cutting device or a punching tool, further comprising: a Device as described above for removing a workpiece part that has been separated from the remaining workpiece during separating machining. A workpiece support, which serves to support the workpiece during the separating machining, can also form a workpiece support of the device for removing workpiece parts from the remaining workpiece. A workpiece transfer device can be arranged in the processing machine, by means of which the remaining workpiece can be moved together with the separated workpiece part from a processing position of the processing machine for the cutting processing of the workpiece to an unloading position of the device for removing the workpiece part.

Another aspect of the invention relates to a method for removing a workpiece part from a remaining workpiece, in particular by means of a device as described above, comprising: contacting the workpiece part at at least one first contact point by means of at least one first contact element, and contacting the workpiece part at at least one second contact point by means of at least one second contact element, wherein the first and second contact elements are formed on a holding device and connected to a sensor device, moving the workpiece part in a removal direction, transferring the holding device to a fixing state for fixing the workpiece part on the holding device, and checking the complete Separation of the workpiece part from the remaining workpiece in a first test state of the sensor device and testing of the fixation of the workpiece part on the holding device in a second test state of the sensor device.

In the method according to the invention, it is irrelevant whether the workpiece part is first moved in the removal direction and then the holding device is transferred into the fixing state, or vice versa. The workpiece part can be moved in the removal direction by means of the holding device, by means of a lifting device or by means of a combination of holding and lifting device. It is also irrelevant in which order the complete separation of the workpiece part from the remaining workpiece and the fixation of the workpiece part on the holding device are checked. Both tests can also be carried out alternately several times in a row.

In one variant, in the first test state, an electrical voltage is typically applied between the at least one first and / or the at least one second contact element on the one hand and a reference potential on the other hand, and an electrical resistance between the at least one first and / or the at least one second contact element Contact element and the reference potential determined. In the second test state, an electrical resistance between the first contact element and the second contact element is measured. Instead of a single contact element, a plurality of first or second contact elements that are conductively connected to one another can alternatively be used.

As described above, a resistance measurement between the first and / or second contact elements on the one hand and a reference potential, typically ground potential, on the other hand can be used to determine whether the workpiece part has been completely separated from the remaining workpiece or not.

The workpiece part can be fixed to the holding device before or after the workpiece part is moved in the removal direction. If the workpiece part is moved in the removal direction, for example with the aid of one or more lifting devices, the workpiece part is not fixed to the holding device until after the removal movement. If, on the other hand, the holding device is also used to move the workpiece in the removal direction, the workpiece is fixed before the removal movement and the fixed workpiece is lifted by the holding device. To check the fixation, a voltage is applied between the first and the second contact element or between a first and second plurality of contact elements in the second test state. In the event that at least one of the first contact elements and at least one of the second contact elements contact the workpiece part, a lower resistance is measured during the resistance measurement in the second test state than in the event that the first and second contact elements are not electrically connected to one another via the workpiece part Are connected so that the resistance measurement can be used to check whether the workpiece part is attached to the Holding device is fixed.

Further advantages of the invention emerge from the description and the drawing. The features mentioned above and those listed below can also be used individually or collectively in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for describing the invention.

Fig. 1

eine schematische Darstellung eines Beispiels einer Bearbeitungsmaschine zum trennenden Bearbeiten eines Werkstücks mittels eines Laserstrahls,

Fig. 2

eine Darstellung einer Vorrichtung zur Entnahme eines Werkstückteils aus einem Restwerkstück an der Bearbeitungsmaschine von Fig. 1,

Fig. 3a,b

Darstellungen der Entnahme eines Werkstückteils aus dem Restwerkstück mittels einer Halteeinrichtung, die eine Mehrzahl von ersten und zweiten Kontaktelementen aufweist, sowie mittels einer Aushebevorrichtung,

Fig. 4

eine Darstellung einer Leiterplatte, an der erste und zweite Kontaktelemente der Halteeinrichtung befestigt sind.

Show it:

Fig. 1

a schematic representation of an example of a processing machine for the separating processing of a workpiece by means of a laser beam,

Fig. 2

a representation of a device for removing a workpiece part from a remaining workpiece on the processing machine from Fig. 1 ,

Fig. 3a, b

Representations of the removal of a workpiece part from the remaining workpiece by means of a holding device, which has a plurality of first and second contact elements, and by means of a lifting device,

Fig. 4

a representation of a circuit board on which the first and second contact elements of the holding device are attached.

In the following description of the drawings, identical reference symbols are used for identical or functionally identical components.

Fig. 1 shows a processing machine 1 for the separating processing of a workpiece 2 in the form of a sheet metal, which has a laser cutting device 3 as a processing tool. The laser cutting device 3 has a portal-like guide structure 4 with a portal cross member 5 and a laser cutting head 6 guided on the portal cross member 5. The laser cutting head 6 is relative to the portal cross member in directions perpendicular to one another 5 movable in the direction of double arrows 7, 8. The laser cutting head 6 is connected to a laser beam source in the form of a conventional solid-state laser 50 via an optical fiber cable 49.

The portal-like guide structure 4 engages over a two-part workpiece table 9 on which a sheet metal 2 is mounted before, during and after the cutting machining. The sheet metal 2 is processed by means of the laser cutting head 6 of the processing machine 1. The sheet metal 2 is supported on the workpiece table 9. Slag formed during machining, as well as dust and smoke, are extracted by a discharge device (e.g. a suction box, not shown) which is arranged between the two parts of the workpiece table 9 below the machining area and connected to a fan. After the sheet metal processing, workpiece parts that have been cut free by means of the laser cutting head 6 are separated from a residual workpiece (scrap skeleton) also produced during the sheet metal processing and then removed from the vicinity of the processing machine 1.

To move the sheet 2 before, during and after its processing, an in Fig. 1 Sheet metal moving unit 10, shown highly schematically. The sheet metal moving unit 10 comprises a rail 11 which is movably guided in the direction of a double arrow 12 by a guide device (not shown) and to which a sheet metal 2 can be fixed by means of clamping claws 13.

By means of the sheet metal moving unit 10, the sheet metal 2 is positioned in the working area of the laser cutting head 6 for processing. During processing, the sheet metal 2 can be moved in the direction of the double arrow 12 by the sheet metal moving unit 10. Processing movements in the transverse direction of the double arrow 12, which are superimposed on this, are carried out by the laser cutting head 6 in the direction of the double arrow 7. In addition, the laser cutting head 6 has an additional axis which enables short, highly dynamic movements of the laser cutting head 6 in the direction of the double arrow 8 and thus in the direction of movement of the sheet metal moving unit 10. With a final separating cut, the laser cutting head 6 cuts (in Fig. 1 not shown) workpiece part of the (in Fig. 1 not shown) residual lattice free, which encloses the cut workpiece part. There the workpiece part and the skeleton on the processing machine 1 are each in a processing position. After the sheet metal processing has been completed, the sheet metal moving unit 10 transfers the workpiece part that has now been cut free and the scrap skeleton together from the respective processing position into an unloading position.

Once the workpiece part 14 that has been cut free and the remaining workpiece 15 have been transferred into their unloading positions, the results in FIG Fig. 2 depicted relationships. Fig. 2 shows a device 16 for removing the workpiece part 14 from the remaining workpiece 15. For the sake of clarity, FIG Fig. 2 only a single workpiece part 14 on the processed sheet metal 2, which is enclosed by the remaining workpiece 15 (scrap lattice). The workpiece part 14 is removed from the remaining workpiece 15 by means of the device 16 before the workpiece part 14 can be transported away from the vicinity of the processing machine 1. The remaining workpiece 15 remains on the workpiece table 9 (cf. Fig. 1 ), before it is also removed from the vicinity of the processing machine 1 after all workpiece parts have been removed.

A plate-like workpiece support 17 of the workpiece table 9 serves as workpiece support for the remaining workpiece 15 and the workpiece part 14. In a known manner, the workpiece support 17 is shown on its top side Fig. 2 bristles or rollers that cannot be seen are provided which enable the processed sheet metal 2 to move over the stationary workpiece support 17 without friction or scratches. The support points of the processed sheet metal 2 on the bristles or the rollers of the workpiece support 17 define an in Fig. 2 indicated workpiece plane 18 of the workpiece support 17. The workpiece plane 18 runs parallel to the main plane of the plate of the workpiece support 17. Along the workpiece plane 18, the workpiece part 14 and the remaining workpiece 15 are aligned with one another.

How out Fig. 2 As can be seen, the workpiece support 17 of the processing machine 1 is designed as a perforated plate with a multiplicity of through openings 19 in the illustrated example. A lifting unit 20 is arranged below the workpiece support 17, and a counter-holding unit 21 of the device 16 is arranged above the workpiece support 17. The lifting unit 20 comprises two structurally identical Lifting devices 22, 23, the counter-holding unit 21, two identical holding devices 24, 25.

The lifting devices 22, 23 can be advanced by means of a lifting movement unit 26 parallel to the storage plane 18 to any point below the workpiece support 17. For this purpose, the lifting movement unit 26 has a longitudinal rail 27, along which the lifting devices 22, 23 can move in a motor-driven manner. A drive motor 28 of the lifting devices 22, 23 is shown in FIG Fig. 2 to recognize. Together with the lifting devices 22, 23, the longitudinal rail 27 can be moved on two transverse rails 29, 30 of the lifting movement unit 26 that run perpendicular to the longitudinal rail 27. The transverse rails 29, 30 can be raised and lowered together with the longitudinal rail 27 and the lifting devices 22, 23 guided by this perpendicular to the workpiece support 17 or the workpiece plane 18.

In a corresponding manner, the holding devices 24, 25 of the counter-holding unit 21 can move to any point on the processed sheet metal 2 parallel to the storage plane 18 and can be raised and lowered perpendicular to the storage plane 18. A holding device movement unit 31 comprises a longitudinal rail 32, along which the counterholders 24, 25 can be advanced in a motor-driven manner. Together with the counterholders 24, 25, the longitudinal rail 32 can be driven by a motor along two transverse rails 33, 34, which in turn run perpendicular to the longitudinal rail 32 and which are raised and lowered in the vertical direction together with the longitudinal rail 32 and the holding devices 24, 25 guided thereon can be.

All essential functions of the processing machine 1 and thus in particular all essential functions of the device 16 are numerically controlled. A numerical control unit 35 used for this purpose is shown in FIG Fig. 1 indicated. The coordinate axes of the numerical control of the processing machine 1 and the device 16 are shown in FIG Figure 1 denoted by x, y, z.

As in Fig. 3a, b it can be seen which each of the first holding device 24 of Fig. 1 and the first lifting device 22 interacting therewith show the holding device 24 has a box-like housing 36 with a flat contact plate 37 serving as a support body, which is provided with a multiplicity of bores 38. The bores 38 receive holding elements in the form of suction grippers 39, which have suction sleeves 40 that are elastically deformable perpendicular to the contact plate 37. In Fig. 3a, b if two suction cups 40 of suction grippers 39 rest on workpiece part 14, while two of suction grippers 39, which do not rest on remaining workpiece 15, protrude from contact plate 37.

A suction chamber (not shown) in the interior of each suction sleeve 40 can be connected to a vacuum generator via a switchable valve. In Figures 3a-d the valves are open, ie there is a connection between the suction chambers of the suction grippers 39 and the vacuum generator, so that it can suck in air via the suction chambers. If the inlet side of the suction sleeve 40 of a suction gripper 39 is open and the vacuum generator is switched on, the relevant valve is closed and the initially existing flow connection between the relevant suction chamber and the vacuum generator is interrupted. If the inlet side of the suction sleeve 40 of a suction gripper 39 is closed by the workpiece part 14 or the remaining workpiece 15, a negative pressure is applied to the relevant suction chamber when the negative pressure generator is switched on. There is no significant air flow in the direction of the vacuum generator, so that the valve remains open and a holding force can build up on the suction gripper 39. If the open or closed state of the valve is not monitored, the vacuum generator cannot distinguish whether the inlet side of the nipple sleeve 40 is open or closed.

In the Fig. 3a, b The first of the two identical lifting devices 22, 23 shown has evidently Fig. 2 a lifting housing 46 to which the lifting devices 22, 23 are connected to the longitudinal rail 27 of the lifting movement unit 26. In the interior of the lifting housing 46 is a plurality of conventional pneumatic piston-cylinder units, each of which is not shown in detail in the figures, each with a double-acting one Cylinder housed. A lifting device in the form of a lifting pin 47 is connected to each of the pistons.

The piston-cylinder units in the interior of the lifting housing 46 can be controlled separately and can be connected independently of one another to a pressure source not shown in detail. By actuating the piston-cylinder units, the lifting pins 47 are extended in the vertical direction out of the lifting housing 46 or are moved back into the lifting housing 46. The cross-section of the lifting pins 47 must not exceed the cross-section of the passage openings 19 on the workpiece support 17 (cf. Fig. 2 ) correspond. In the example shown, the cross section of the lifting pins 47 is smaller than the cross section of the through openings 19.

The following is based on Fig. 2 and Fig. 3a, b the process of removing the workpiece part 14 from the remaining workpiece 15 is described. First, the processed sheet metal 2 and the workpiece support 17 are positioned relative to one another in such a way that the workpiece part 14 covers a sufficient number of passage openings 19 of the workpiece support 17. The sheet metal moving unit 10 functions as an adjusting device, by means of which the processed sheet metal 2 with the workpiece part 14 and the remaining workpiece 15 can be fed to the processing machine 1 in the x-direction of the coordinate system. The position which the workpiece part 14 assumes in the coordinate system of the numerical control of the machine arrangement 1 is defined.

The lifting movement unit 26 below the workpiece support 17 is actuated numerically controlled in such a way that the lifting device 22 moves to a lifting position below the workpiece part 14. Simultaneously with the positioning of the lifting device 23, the holding device 24 on the opposite side of the workpiece support 17 is moved by numerically controlled actuation of the holding device moving unit 31 into a position above the workpiece part 14 in the unloading position. This results in the conditions according to Fig. 3a, b , these showing the highly schematized lifting device 22 and the opposing holding device 24. The workpiece support 17 is in Figs. 3a, b not shown for the sake of simplicity.

The vacuum generator for the holding device 24 is initially switched off, the suction grippers 39 on the holding device 24 are spaced from the workpiece part 14 and also from the remaining workpiece 15, which is also arranged in an unloading position. The suction grippers 39 are consequently in an inoperative state, and the holding device 24 is thus in a release state. With this functional state, the holding device 24 is lowered by a corresponding vertical movement of the holding device moving unit 31 and thereby placed on the processed sheet metal 2 or on the workpiece part 14 and the remaining workpiece 15. The suction cuffs 40 of the suction grippers 39 are compressed and consequently folded more strongly and pushed back into the interior of the bores 38 on the contact plate 37 of the holding device 24 until the contact plate 37 of the holding device 24 touches the sheet metal surface.

Then, on the lifting device 22, those lifting pins 47 are actuated which are located below the workpiece part 14 and for which the workpiece part 14 is accessible via through openings 19 in the workpiece support 17. The remaining lifting pins 47 of the lifting device 23 retain their initial position. With the lift-out pins 47 extended from the lift-out housing 46, the lift-out device 22 is moved into the position according to FIG Fig. 3a raised. In the process, the extended lifting pins 47 are placed against the underside of the workpiece part 14. The workpiece part 14 is now acted upon on its underside by the lifting device 22 in a removal direction Z and is supported over a large area in the removal direction Z on its upper side by the holding device 24, more precisely by the contact plate 37. The suction grippers 39 of the holding device 24, which are still in the non-functional state, rest on the upper side of the workpiece part 14, which is aligned parallel to the workpiece plane 18, with a prestress resulting from their elastic deformation.

A control signal causes the lifting device 22 and the holding device 24 by means of the lifting-out movement unit 26 and the holding-device movement unit 31 to be synchronized with a removal movement in the Removal direction Z are moved. The prefabricated part 14, which is initially arranged in the plane of the remaining workpiece 15, is excavated from the remaining workpiece 15 ( Fig. 3a ).

As soon as a value is determined for the amount of the lifting movement, for example by means of a displacement measuring system of the numerical control of the device 16, on the basis of which it is ensured that the suction grippers 39 arranged next to the workpiece part 14 and protruding from the contact plate 37 of the holding device 24 are a clear distance from the Have surface of the remaining workpiece 15 on the workpiece support 17, the vacuum generator of the holding device 24 is switched on. As a result, those suction grippers 39 which are in contact with the workpiece part 14 are switched from the non-functional state to a functional state. The holding device 24 is thereby transferred from the released state to the fixing state in which the workpiece part 14 is fixed or fixed on the holding device 24.

If the workpiece part 14 is fixed on the holding device 24, the lifting pins 47, which previously acted on the workpiece part 14, are retracted into the lifting housing 46 of the lifting device 23 and the lifting device 23 is moved into the position according to FIG Figure 3b lowered. The holding device 24 then moves with the workpiece part 14 fixed to it with the aid of the counterholder movement unit 31 from the vicinity of the workpiece support 17. In order to release the workpiece part 14 from the holding device 24 at a storage location for the workpiece part 14, the suction grippers 39, the Hold workpiece part 14, depressurized.

As in Fig. 3a As can be seen, the holding device 24 has a first electrically conductive contact element 41 which is fastened to a first electrically conductive component in the form of a first electrically conductive perforated plate 42, more precisely screwed into it. In addition, the holding device 24 has a plurality of second electrically conductive contact elements 43 which are fastened to a second electrically conductive component in the form of a second perforated plate 44. The second contact elements 43 are electrically insulated by means of spacers Holes in the first perforated plate 42 out. The first perforated plate 42 and the second perforated plate 44 are spaced apart from one another and electrically isolated from one another.

Connection contacts of the two perforated plates 42, 44 are fed to a sensor device 45. A first resistance measuring device W1 and a second resistance measuring device W2 are arranged in the sensor device 45. The first resistance measuring device W1 is used to determine a resistance R1 between the first and second contact elements 41, 43 on the one hand and a reference potential on the other hand, in the example shown the ground potential M of the device 16 or the processing machine 1 in a first test state P1 of the sensor device 45. The second resistance measuring device W2 is used to determine a resistance R2 between the first contact elements 41 and the second contact elements 43 in a second test state P2 of the sensor device 45. A first switch S1 is connected in parallel to the second resistance measuring device W2, and a second switch S2 is in series connected to the first resistance measuring device W1 and to the first and second contact elements 41, 43, respectively.

The first contact element 41 and the second contact elements 43 have resilient contact pins 41a, 43a, the free ends of which bear against a first contact point K1 and second contact points K2 on the workpiece part 14, respectively.

The sensor device 45 enables a check to be made as to whether the workpiece part 14 has been completely separated from the remaining workpiece 15 or whether there is still an electrically conductive connection between the workpiece part 14 and the remaining workpiece 15. For this purpose, the sensor device 45 is in an in Fig. 3a first test state P1 shown, in which the first switch S1 is closed, so that the first contact element 41 and the second contact elements 43 are connected to one another in an electrically conductive manner. In the first test state P1, the second switch S2 is also closed, so that the electrical resistance R1 between the first and second contact elements 41, 43 on the one hand and the reference potential M on the other hand can be measured via the first resistance measuring device W1. The reference potential M corresponds to im The example shown shows the potential of the remaining workpiece 15, which is connected to the ground potential of the processing machine 1 via the clamping claws 13 or via the workpiece support 17.

In the event that the workpiece part 14 and the remaining workpiece 15 are still in contact with one another, current can flow from the workpiece part 14 via the remaining workpiece 15 to the ground potential of the processing machine 1. In this case, a very low electrical resistance R1 is measured. If, on the other hand, the workpiece part is completely separated from the remaining workpiece 15 and lifted out, no closed circuit is formed and a large resistance R1 is determined between the first and second contact elements 41, 43 on the one hand and the ground potential on the other.

Using the value of the measured first resistance R1, it can thus be recognized whether the workpiece part 14 has been completely separated from the remaining workpiece 15. In the event of an error, i.e. if the workpiece part 14 is still connected to the remaining workpiece 15, the lifting process can be repeated or an error signal can be output. In the event that the workpiece part 14 has been completely separated from the remaining workpiece 15, the removal of the workpiece part 14 can be continued.

The sensor device 45 also enables a check to be made as to whether the workpiece part 14 is actually fixed on the holding device 24 in the fixed state. For this purpose, the sensor device 45 is operated in a second test state P2, in which the first switch S1 and the second switch S2 are open, as shown in FIG Figure 3b is shown. When a voltage is applied between the first contact element 41 on the one hand and the second contact elements 43 on the other hand, the second resistance measuring device W2 determines the resistance R2 between the first contact element 41 and the second contact elements 43, which at the corresponding first contact point K1 and the second contact points K2 with the workpiece part 14 are in contact, provided that this is fixed on the holding device 24. If electrical contact is established between the first and second contact elements 41, 43 via the workpiece part 14 fixed on the holding device 24, the electrical resistance R2 is that of the second Resistance measuring device W2 is measured, very small. If, on the other hand, the workpiece part 14 is not fixed to the holding device 24, the first contact element 41 is electrically isolated from the second contact elements 43, so that the electrical resistance R2, which is measured by the second resistance measuring device W2, is very high or practically approaches infinity . If it is recognized during the check that the workpiece part 14 is not fixed on the holding device 24, an attempt can be made again, for example, to fix the workpiece part 14 on the holding device 24. Alternatively, an error signal can be output.

As in Fig. 3a, b is shown, the first contact element 41 alternates with the second contact elements 43 in the Y direction. If more contact elements 41, 43 are provided, the first contact elements 41 and the second contact elements 43 also alternate in the X direction, both the first contact elements 41 and the second contact elements 43 being arranged in a regular arrangement in the manner of a grid .

The mode of operation of the removal device 16 according to the invention has been described above on the basis of a processing machine 1 with a combined movement of the workpiece 2 and the laser cutting head 6. However, the removal device can also be used in an analogous manner on a processing machine in which the workpiece rests during processing and is, for example, arranged on a bridge support that can be moved into and out of the processing area of the machine with the help of a pallet changer.

If the removal device 16 is used to automate such a flying optics machine, this is also possible without an additional lifting device. To remove a workpiece part from the remaining workpiece, the holding device 24 is in this case first placed on the surface of the workpiece part 14 and then the vacuum generator of the holding device 24 is switched on. The holding device 24 is thereby transferred from the released state to the fixing state in which the workpiece part 14 is fixed or fixed on the holding device 24. In order to prevent the remaining workpiece 15 from being fixed to the holding device 24, the holding elements 39 can be used, for example, as Active suction devices can be designed, the opening state of which can be changed by means of a controller. Alternatively, the holding device 24 can be adapted to the shape of the workpiece parts 14 to be removed such that holding elements 39 are arranged only in the region of the workpiece part 14. A contact plate 37 is not necessary in this example.

Fig. 4 FIG. 11 shows a plan view of the underside of an alternative holding device 24 with suction grippers 39. Unlike in FIG Fig. 3a, b are shown in Fig. 4 the first contact elements 41 and the second contact elements 43 are fastened on a common printed circuit board 54. The first contact elements 41 are connected to one another in an electrically conductive manner via first conductor tracks 51, while the second contact elements 43 are electrically conductively connected to one another via second conductor tracks 53, which are electrically isolated from the first conductor tracks 51, as shown in FIG Fig. 4 is shown by way of example only for two rows of contact elements 41, 43. The in Fig. 4 In the example shown, the first contact elements 41 alternate with the second contact elements 43 only in the X direction, but not in the Y direction. The fastening of the first and second contact elements 41, 43 on a common printed circuit board 54 makes it possible to position the first and second contact elements 41, 43 at a smaller distance from one another than in the case of the one in FIG Fig. 3a, b shown example.

As an alternative to the in Fig. 3a, b and in Fig. 4 The examples shown, the suction grippers 39 themselves can be designed as (first or second) contact elements. In this case, the nipple sleeves 40 are typically made from an electrically conductive material, for example from an electrically conductive plastic. In this case, the suction grippers 39 can be divided into two groups, which are each connected to one another in an electrically conductive manner in order to form the first and second contact elements 41, 43. It goes without saying that only the first contact elements 41 can be formed on the suction grippers 39, while the second contact elements 43 are arranged between the suction grippers 39, or vice versa. In contrast to the resilient contact pins 41a, 43a, the tips of which in the case of a foiled sheet metal 2 can easily scratch the surface of the sheet applied to the sheet metal 2 so that electrical contact is made, this is the case with the use of the suction grippers 39 with the suction cups 40 made of plastic as contact elements is not easily possible.

Claims (14)

1. A device (16) for removing an electrically conductive workpiece part (14) from an electrically conductive remaining workpiece (15), comprising:

   a holding apparatus (24, 25) which can be moved in a removal direction (Z) and which can be switched between a fixing state for fixing the workpiece part (14) to the holding apparatus (24, 25) and a release state for releasing the workpiece part (14) from the holding apparatus (24, 25),

   wherein the holding apparatus (24, 25) has at least one first electrically conductive contact element (41) for contacting the workpiece part (14) at at least one first contact point (K1),

   and wherein the holding apparatus (24, 25) has at least one second electrically conductive contact element (43) for contacting the workpiece part (14) at at least one second contact point (K2),

   characterized in that

   the device (16) comprises a sensor apparatus (45) which is designed, making use of the at least one first and second contact element (41, 43), to check in a first check state (P1) the complete separation of the workpiece part (14) from the remaining workpiece (15) and to check in a second check state (P2) the fixing of the workpiece part (14) to the holding apparatus (24, 25) being in the fixing state.
2. The device as claimed in claim 1, in which the sensor apparatus (45) is designed, in the first check state (P1), to determine an electrical resistance (R1) between the first and/or the second contact element (41, 43) on the one hand and a reference potential (M) on the other.
3. The device as claimed in claim 1 or 2, in which the sensor apparatus (45) is designed, in the second check state (P2), to determine an electrical resistance (R2) between the first contact element (41) and the second contact element (43).
4. The device as claimed in one of the preceding claims, in which the holding apparatus (24) comprises a plurality of holding elements (39) for fixing the workpiece part (14), wherein the holding elements (39) can be switched between a fixing state for fixing the workpiece part (14) and a release state for releasing the workpiece part (14).
5. The device as claimed in claim 4, in which the holding elements are designed as suction grippers (39).
6. The device as claimed in claim 4 or 5 in which the at least one first contact element (41) and/or the at least one second contact element (43) are formed at a holding element (39).
7. The device as claimed in one of claims 4 to 6 in which the at least one first contact element (41) and/or the at least one second contact element (43) are arranged between the holding elements (39).
8. The device as claimed in one of the preceding claims, in which first contact elements (41) alternate with second contact elements (43) in at least one direction (x, y) perpendicular to the lift-out direction (z).
9. The device as claimed in one of the preceding claims, in which the at least one first contact element (41) and/or the at least one second contact element (43) comprise resilient contact pins (41a, 43a) for contacting the workpiece part (14) or the remaining workpiece (15).
10. The device as claimed in one of the preceding claims, in which the holding apparatus (24) comprises a plurality of first contact elements (41) and second contact elements (43), and the first contact elements (41) and the second contact elements (43) are respectively connected electrically conductively to one another by conductive tracks (51, 53) of the same circuit board (54).
11. The device as claimed in one of the preceding claims, further comprising at least one lift-out device (47) that is movable in the removal direction (Z) for removing the workpiece part (14) from the remaining workpiece (15), wherein the workpiece part (14) is held during at least part of the removal between the at least one lift-out device (47) and the holding apparatus (24).
12. Processing machine (1) for the separating machining of plate-like, electrically conductive workpieces, in particular of metal sheets (2), by means of a machining tool (3), further comprising:
    a device (16) as claimed in one of the preceding claims for removing a workpiece part (14) that is separated from a remaining workpiece (15) during separating machining.
13. A method for the removal of a workpiece part (14) from a remaining workpiece (15), in particular by means of a device (16) as claimed in one of claims 1 to 11, comprising:

    contacting the workpiece part (14) at at least a first contact point (K1) by means of at least one first contact element (41) as well as contacting the workpiece part (14) at at least one second contact point (K2) by means of at least one second contact element (43), wherein the first and second contact elements (41, 43) are formed at a holding apparatus (24, 25) and are connected to a sensor apparatus (45),

    moving the workpiece part (14) in a removal direction (Z),

    switching the holding apparatus (24) into a fixing state for fixing the workpiece part (14) to the holding apparatus (24), as well as

    checking the complete separation of the workpiece part (14) from the remaining workpiece (15) in a first check state (P1) of the sensor apparatus (45) and

    checking the fixing of the workpiece part (14) to the holding apparatus (24) in a second check state (P2) of the sensor apparatus (45).
14. The method as claimed in claim 13, in which, in the first check state (P1) an electrical resistance (R1) between the first and/or the second contact element (41, 43) on the one hand and a reference potential (M) on the other hand is determined and in which, in the second check state (P2) an electrical resistance (R2) is determined between the first contact element (41) and the second contact element (43).

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