BENDING MACHINE AND METHOD FOR OPERATING A BENDING MACHINE

Abstract

Bending machine with a machine bed including a workpiece table with a workpiece support surface and an upper tool which is linearly movable mounted to the machine bed along a movement axis and which has a bottom edge arranged adjacent to the workpiece support surface. The lower edge and the movement axis define a movement plane which separates a handling space from a workpiece receiving space, in which a first optical safety device is arranged in the handling space and a second optical safety device is arranged in the workpiece receiving space, and with a safety controller to process sensor signals from the optical safety devices and for switching off a drive associated with the upper tool. The safety controller provides a first operating mode, in which only the first sensor signals are processed, and a second operating mode, in which only the second sensor signals are processed.

Claims

1. A bending machine having a machine bed with a workpiece table which has a workpiece supporting surface, and with an upper tool mounted on the machine bed for linear movement along a movement axis, which upper tool has a bottom edge arranged adjacent to the workpiece support surface, the bottom edge and the movement axis defining a movement plane in which the bottom edge can move between an open position for the upper tool and a closed position for the upper tool, the movement plane separating a handling space, which extends from the upper tool in the direction of a front edge of the workpiece support surface, from a workpiece receiving space, which extends from the upper tool to a rear edge of the workpiece support surface support surface and wherein a first optical safety device is arranged in the handling space and a second optical safety device is arranged in the workpiece receiving space, and with a safety controller which processes first sensor signals of the first optical safety device and second sensor signals of the second optical safety device and is set up for switching off a drive associated with the upper tool dependent on the first sensor signals and/or dependent on the second sensor signals, wherein the safety controller is switchable between a first operating mode, in which only the first sensor signals are processed, and a second operating mode, in which only the second sensor signals are processed.

2. The bending machine according to claim 1, wherein the first optical safety device has a first lower beam source that provides a first lower optical beam parallel to the bottom edge and which has a first lower beam receiver that receives the first lower optical beam, and that the first optical safety device has a first upper beam source that provides a first upper optical beam parallel to the lower edge, and a first upper beam receiver that receives the first upper optical beam, wherein the first lower beam source is located at a smaller distance from the workpiece supporting surface than the first upper beam source.

3. The bending machine according to claim 1, wherein the second optical safety device has a second lower beam source that provides a second lower optical beam parallel to the bottom edge, and a second lower beam receiver that receives the second lower optical beam, and that the second optical safety device has a second upper beam source that provides a second upper optical beam parallel to the lower edge and a second upper beam receiver that receives the second upper optical beam, wherein the second lower beam source is located at a smaller distance from the workpiece supporting surface than the second upper beam source.

4. The bending machine according to claim 2, wherein the safety controller exclusively processes sensor signals of the first upper beam receiver and sensor signals of the first lower beam receiver in the first operating mode during a closing movement of the upper tool.

5. The bending machine according to claim 3, wherein the safety controller, when operating in the second operating mode, suppresses sensor signals of the second upper beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a first safety distance, and suppresses sensor signals of the second lower beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a second safety distance.

6. The bending machine according to claim 2, wherein a third operation mode for the safety controller may be selected, in which a processing of the first sensor signals and of the second sensor signals is provided.

7. The bending machine according to claim 6, wherein the safety controller, when operating in the third operating mode, suppresses sensor signals of the second upper beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a first safety distance, and suppresses sensor signals of the second lower beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a second safety distance.

8. The bending machine according to claim 1, wherein the first optical safety device and the second optical safety device are arranged in a fixed position on the machine bed.

9. The bending machine according to claim 1, wherein the first optical safety device and the second optical safety device are arranged on the upper tool such that they can be moved linearly.

10. The bending machine according to claim 1, wherein the upper tool is a workpiece holder for securing a workpiece to the workpiece table, and wherein a folding beam extending along the front edge of the workpiece supporting surface is attached to the workpiece table such that it can pivot, with a pivot axis of the folding beam being aligned parallel to the lower edge of the upper tool and to the front edge of the workpiece supporting surface.

11. A method for operating a bending machine comprising the steps of: carrying out a selection process for a workpiece-dependent operating mode for a safety controller of a bending machine from the group: first operating mode for a workpiece having a lateral upstand behind a bending line, second operating mode for a workpiece having a lateral upstand in front of the bending line; pushing a workpiece in a pushing movement in a pushing direction onto a workpiece supporting surface of the bending machine, wherein a bending line of the workpiece is arranged in a movement plane which is spanned by a lower edge of an upper tool of the bending machine and a movement axis of the upper tool, which upper tool is linearly movable with respect to the workpiece support surface; activation of a first optical safety device by the safety controller in the event that the first operating mode has been selected, the first optical safety device being arranged in a handling space of the bending machine, which handling space extends in front of the movement plane starting from the upper tool in the opposite direction to the pushing-on direction, or activation of a second optical safety device by the safety controller in the event that the second operating mode has been selected, the second optical safety device being arranged in a workpiece receiving space of the bending machine, which workpiece receiving space extends behind the movement plane in the pushing-on direction starting from the upper tool.

12. The method according to claim 11, wherein in the first mode of operation, during an approach of the upper tool to the workpiece supporting surface the safety controller continues a processing of sensor signals of the first upper beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a first safety distance, and continues a processing of sensor signals of the first lower beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a second safety distance.

13. The method according to claim 11, wherein in the second operating mode, during an approach of the upper tool to the workpiece supporting surface the safety controller processes sensor signals of the second upper beam receiver of the second optical safety device only until a distance between the lower edge and the workpiece support surface is smaller than a first safety distance, and processes sensor signals of the second lower beam receiver of the second optical safety device only until a distance between the lower edge and the workpiece support surface is smaller than a second safety distance.

14. The method according to claim 11, wherein, when the selection procedure for the workpiece-dependent operating mode of the safety controller of the bending machine is carried out, a third operating mode for a workpiece without lateral upturns is provided and upon selection of the third operating mode the first safety device and the second safety device are activated by the safety controller and during an approach of the upper tool to the workpiece support surface the safety controller suppresses sensor signals of the second upper beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a first safety distance, and suppresses sensor signals of the second lower beam receiver when a distance between the lower edge and the workpiece support surface is smaller than a second safety distance.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0062] An advantageous embodiment of the invention is shown in the drawing.

[0063] Here shows:

[0064] FIG. 1: a front view of a bending machine, designed purely as an example as a folding machine, which is equipped with a first optical safety device and with a second optical safety device, as well as an associated safety controller,

[0065] FIG. 2: a schematic, partially cut side view of the bending machine according to FIG. 1,

[0066] FIG. 3: a schematic, partially cut side view of a variant of the bending machine according to FIG. 1, in which the first optical safety device and the second optical safety device are arranged in a fixed position on the machine frame,

[0067] FIG. 4: a schematic representation of a workpiece that is provided with an upstand behind a bending line, and

[0068] FIG. 5 a schematic representation of a workpiece that is provided with an upstand in front of a bending line.

DETAILED DESCRIPTION

[0069] A bending machine 1 shown in FIGS. 1 and 2, designed purely as an example as a folding machine, comprises a machine bed 2 on which a workpiece table 3 is formed, which comprises a workpiece support surface 4 that is exemplarily formed to be flat.

[0070] As shown in FIGS. 1 and 2, the workpiece support surface 4, which is rectangular purely by way of example, is horizontally aligned and extends from a front edge 32 visible in FIG. 1 to a rear edge 33 visible in FIG. 2. Furthermore, the workpiece supporting surface 4 extends from a left side edge 34 to a right side edge 35.

[0071] Furthermore, a bending beam 5, also named folding beam, is arranged on the machine bed 2 so as to be pivotally movable, which bending beam 5 extends with a longest edge 31 along the front edge 32 of the workpiece supporting surface 4. The bending beam 5 is attached to the machine bed 1 by means of a pivot joint 6, 7 at each of its opposite end regions. The pivot joints 6, 7 have a common pivot axis 8 that is aligned parallel to the workpiece support surface 4.

[0072] A working surface 10 of the bending beam 5 can be pivoted by means of a pivoting drive 31 by a pivoting movement of the bending beam 5 out of the rest position shown in FIGS. 1 and 4, in which the working surface 10 is arranged parallel and flush with the workpiece support surface 4, into an operating position shown in FIG. 2 with a dashed line. In the operating position, the work surface 10, for example, assumes a right angle with respect to the workpiece support surface 4, but other angular positions are also possible.

[0073] The pivoting movement of the folding beam 5 is initiated by a foot switch 9, which is connected to a machine controller 12 that can control or regulate the movement of the pivoting drive 31. To fix a workpiece 41 or 47, as shown in FIGS. 3 and 4, to the workpiece table 3, an upper tool 21 is provided, which is movably attached to the machine bed 2 and is also referred to as a clamping beam.

[0074] The upper tool 21 is linearly guided on both sides by guide columns 15, 16, which in turn are fixed to the machine bed 2. A distance 22 between a lower edge 23 of the upper tool 21 and the workpiece table 3 can be adjusted by means of a spindle drive 17, which comprises an electric motor 18 and a drive spindle 19.

[0075] A movement of the upper tool 21 between a first operating position, as shown in FIG. 1, with a maximum distance 11 from the workpiece support surface 4 and a second operating position with a minimum distance 22 from the workpiece support surface 4 can thus be carried out along a movement axis 24, drawn as a double arrow. In this case, the lower edge 23 of the upper tool 21 moves between the first functional position and the second functional position in a movement plane 25, which is drawn in a dashed line in FIGS. 1 and 2, which movement plane 25 is aligned transversely to the workpiece support surface 4 and geometrically contains the lower edge 23.

[0076] The upper tool 21 is assigned a first optical safety device 51 and a second optical safety device 61. The first optical safety device 51 comprises a first lower beam source 52, a first upper beam source 53, a first lower beam receiver 54 and a first beam receiver 55. The second optical safety device 61 comprises a second lower beam source 62, a second upper beam source 63, a second lower beam receiver 64 and a second upper beam receiver 65.

[0077] Between the respective optical beam sources 52, 53 and 62, 63 and the associated optical beam receivers 54, 55 and 64, 65, first lower laser beams 56, first upper laser beams 57, second lower laser beams 66 and second upper laser beams 67 are provided respectively, as indicated by the different broken lines.

[0078] In order to be able to show all laser beams 56, 57, 66, 67 in FIG. 1, they are drawn at different distances from the workpiece support surface 4. In practice, however, it may be intended that the respective lower laser beams 56, 66 are arranged in a common horizontal plane, in particular in a plane oriented parallel to the workpiece support surface 4, and/or the respective upper laser beams 57, 67 are arranged in a common horizontal plane, in particular in a plane oriented parallel to the workpiece support surface 4, as can also be seen from FIG. 2.

[0079] The beam sources 52, 53, 62, 63 may, for example, be designed as discrete laser diodes and are preferably configured in such a way that the respective laser beams 56, 57, 66, 67 are emitted in the form of parallel beams with an almost punctiform cross-section.

[0080] As examples, the beam receivers 54, 55, 64, 65 are aligned in such a way that the respective laser beams 56, 57, 66, 67 each strike areas of the respective beam receivers 54, 55, 64, 65 that have maximum optical sensitivity.

[0081] Both optical safety devices 51 and 61 are each attached to holding devices 26, which in turn are linearly movably arranged on the upper tool 21 and allow a linear relative movement of the optical safety devices 51 and 61 along the movement axis 24 relative to the upper tool 21. In this case, it is envisaged that the linear movements of the holding devices 26 relative to the upper tool 21 are coordinated by the machine controller 12 in such a way that the respective radiation sources 52, 53, 62, 63 and the associated radiation receivers 50, 55, 64, 65 are always located opposite one another.

[0082] The safety controller 81 is electrically connected to the optical safety devices 51 and 61 via electric sensor lines and is designed to process sensor signals from the beam receivers 54, 55, 64, 65 and to activate a shutdown device 82, if necessary. The shut-off device 82 may, for example, be an electric contactor or switch for the electric motor 18.

[0083] This enables the safety controller 81 to shut down the drive motor 18 by interrupting the power supply even though the machine controller 12 provides electrical energy to the electric motor 18.

[0084] From the side view according to FIG. 2, only the beam receivers 54, 55, 64, 65 can be seen, while the respectively associated beam sources 52, 53, 62, 63 are not shown in FIG. 2. In FIG. 2, the movement plane 25 is drawn as a vertical plane and encompasses the lower edge 23 of the upper tool 21 both in the first functional position, in which the distance 22 between the upper tool 21 and the workpiece contact surface 4 is at a maximum, and in the second functional position, in which the upper tool 21 is only shown as a dashed line.

[0085] Furthermore, it can be seen from FIG. 2 that the first lower beam receiver 54 and the first upper beam receiver 55 are arranged in a handling space 71 adjacent to the movement plane 25. The handling space 71 extends from the movement plane 25 in the direction of the front edge 32 of the workpiece support surface 4 and beyond, the handling space 71 thus extending in the opposite direction to the pushing-on direction 91, which is used when pushing one of the workpieces 41 or 47 into the bending machine 1.

[0086] The handling area represents the spatial area in which a user handles workpieces and from where, for example, the workpieces 41, 47 are pushed into the bending machine 1 in the pushing direction 91 or are removed from the bending machine 1 in the direction opposite to the pushing direction 91 after the forming operation has been carried out.

[0087] The second lower beam receiver 64 and the second upper beam receiver 65, on the other hand, are accommodated in a workpiece receiving space 72 which, starting from the movement plane 25, extends in the direction of the rear edge 33 of the workpiece supporting surface 4 and thus in the pushing-on direction 91.

[0088] When the upper tool 21, with the optical safety devices 51, 61 mounted on it, moves from the first functional position to the second functional position, it is initially intended that the holding devices 26 do not move relative to the upper tool 21. However, as soon as the lower laser beams 56, 66 approach a safety distance, which may be 6 mm from the workpiece contact surface 4, for example, the safety controller 81 triggers the drives of the holding device 26, so that the safety distance of the lower laser beams 56, 66 is kept constant despite a further movement of the upper tool 21.

[0089] Depending on the selected operating mode for the bending machine 1, either only the sensor signals of the first optical safety device 51 or only the sensor signals of the second optical safety device 61 or the sensor signals of both optical safety devices 51, 61 are processed by the safety controller 81 during this approach movement. If, for example, a workpiece 41, which is only shown schematically in FIG. 4, is to be processed, which has a lateral upstand 42 that has to be arranged parallel to a bending line 43 and which is located in the workpiece receiving space 72 of the bending machine 1, the first operating mode for the bending machine 1 is selected, in which only the sensor signals of the first optical safety device 51 are processed.

[0090] In the first operating mode, it is intended that the sensor signals of the first optical safety device 51 are not blanked out during the entire closing process for the upper tool. If, on the other hand, a workpiece 47 is to be processed, which is only shown schematically in FIG. 5, and which has a lateral upstand 48 that has to be arranged parallel to a bending line 49 and which is located in the handling space 71 of the bending machine 1, the second operating mode is selected for the bending machine 1, in which only the sensor signals of the second optical safety device 61 are processed. In the second operating mode, it is preferably envisaged that, during the closing process for the upper tool, a path-dependent suppression of the sensor signals of the second optical safety device 61 is carried out.

[0091] The variant of a bending machine 99 shown in FIG. 3 differs from the variant of the bending machine 1 shown in FIGS. 1 and 2 only in the arrangement of the two optical safety devices 51 and 51, which in this variant are arranged in a fixed position on the machine bed 2. Otherwise, the components of the bending machine 99 are designed in the same way as for the bending machine 1, so that the same reference signs are used for the components and a new description of the components and their function is dispensed with.