Measuring device for a handling robot of a bending machine

Abstract

The invention relates to a measuring device (1) for a handling robot (2) of a bending machine (3), the measuring device comprising: a first fastening section (4) for fastening the measuring device (1) to an end section (5) of a robot arm (6) of the handling robot (2); and a second fastening section (7), which is arranged opposite the first fastening section (4) in the direction of a longitudinal axis (L) of the measuring device (1), for fastening a workpiece gripper (8) which is designed to grip a workpiece to be bent (W), wherein the measuring device (1) comprises a sensor unit (9) which is designed to detect a force (F) that acts on the workpiece gripper (8) and is transmitted to the measuring device (1) via the second fastening section (8), and / or to detect a transmitted torque (M).

Description

[0001] MEASURING DEVICE FOR A HANDLING ROBOT OF A BENDING MACHINE

[0002] The invention relates to a measuring device for a handling robot of a bending machine, a handling robot for a bending machine, a bending machine and a method for operating a bending machine.

[0003] In automated bending processes on bending machines, especially free bending, the workpieces, particularly sheet metal, are automatically fed between the (upper and lower) tools of the bending machine by a handling robot and positioned against a backgauge on the opposite side. The handling robot is equipped with a workpiece gripper that can grasp and hold the workpiece. Precise positioning of the workpiece against the backgauge is crucial to achieving consistently high quality. Since the mechanical stiffness of the robot arm, the workpiece gripper, and the workpiece typically vary, this leads to inaccuracies in positioning against the backgauge, as there is usually no feedback signal when the workpiece is stopped against the backgauge.Although the motor currents of the robot arm can be evaluated to obtain information about the impact forces, such an evaluation is too inaccurate for precise positioning.

[0004] The object of the present invention was to overcome the disadvantages of the prior art and to enable improved positioning of a bent workpiece on the back gauge of a bending machine.

[0005] The problem is solved with a measuring device comprising a first mounting section for attaching the measuring device to an end section of a robot arm of the handling robot and a second mounting section, opposite the first mounting section in the direction of a longitudinal axis of the measuring device, for attaching a workpiece gripper designed for gripping a bent workpiece. The measuring device includes a sensor device designed to detect a force and / or a transmitted torque acting on the workpiece gripper and transmitted to the measuring device via the second mounting section. The measuring device can therefore be easily retrofitted to existing bending machines using handling robots.The measured force and / or torque can be evaluated, for example to implement simple double sheet detection or to determine the position of a force application point on the backstop.

[0006] The measuring device preferably has a sensor interface for transmitting acquired measurement data from the sensor device to a robot control unit of the handling robot and / or to a machine control unit of the bending machine. The robot control unit can, for example, evaluate the measurement data and use it to position the workpiece being bent, which is held by the workpiece gripper. The measured, unprocessed sensor parameters can be made available via the sensor interface.

[0007] The sensor device preferably comprises at least one force sensor, wherein the force sensor preferably comprises a piezoelectric sensor and / or strain gauges. This allows a force transmitted to the measuring device to be measured. A transmitted torque can also be determined from the measured force, if necessary.

[0008] The measuring device, in particular the sensor assembly, may, for example, also include a signal processing unit configured to determine a desired measured quantity from the sensor quantity measured by the sensor assembly, in particular its force sensor. Furthermore, the measuring device may include a power supply connection for supplying the signal processing unit with electrical energy. The power supply connection and the sensor interface may be integrated. For example, the signal processing unit could be configured to determine a force proportional to a change in electrical resistance (as sensor quantity) measured by a strain gauge. The measured quantity could be provided in the form of measurement data via the sensor interface.Of course, the unprocessed sensor data could also be provided via the sensor interface, and processing of the sensor data could take place, for example, in the robot control unit or in the machine control unit of the bending machine.

[0009] The measuring device preferably has a substantially cylindrical housing with the longitudinal axis as the cylinder axis. Due to its cylindrical shape, the measuring device can be easily and compactly integrated into an existing system between the workpiece gripper and the robot arm. The measuring device, in particular the housing, can have a measuring plate which includes the sensor assembly. The sensor assembly comprises at least three force sensors, in particular piezoelectric sensors, which are arranged circumferentially spaced apart from each other with respect to the longitudinal axis on the measuring plate. The force sensors are preferably located in one or the same sensor plane perpendicular to the longitudinal axis. This provides a simple and compact embodiment that can also be replaced if necessary.

[0010] The first fastening section is preferably designed so that it cannot be detached during operation of the handling robot. The first fastening section may, for example, have a screw flange. The second fastening section is preferably designed so that it can be detached during operation of the handling robot to allow for a change of the workpiece gripper, preferably automated. The second fastening section may, for example, include a quick-release fastener.

[0011] In a further aspect, the invention relates to a handling robot for a bending machine for handling bent workpieces, wherein the handling robot comprises a workpiece gripper for gripping a number of bent workpieces and a robot control unit for controlling the handling robot, wherein the handling robot comprises a measuring device as described above, which mechanically connects an end section of a robot arm of the handling robot to the workpiece gripper, wherein the end section of the robot arm comprises a third mounting section to which the first mounting section of the measuring device is attached, and the workpiece gripper comprises a fourth mounting section which is attached to the second mounting section of the measuring device, and wherein the robot control unit is configured to use the measurement data obtained from the measuring device to control the handling robot, in particular a positioning drive.to use. This provides a handling robot that enables improved positioning of the workpiece against the backgauge of the bending machine. It also enables simple double-sheet detection.

[0012] The workpiece gripper can comprise a vacuum gripper and / or a gripper. It is particularly advantageous if the workpiece gripper comprises a gripper on one side and a vacuum gripper on the opposite side. This allows the appropriate workpiece gripper to be used depending on the situation. The robot control unit is preferably configured to determine the mass of a number of bending workpieces held by the workpiece gripper based on the measurement data obtained from the measuring device, and to determine the actual number of bent workpieces held from the determined mass and a predetermined or predefinable mass of a single bent workpiece. This enables simple double-sheet detection. The known mass can be provided to the robot control unit, for example, by a machine control unit of the bending machine.

[0013] Furthermore, the robot control unit is preferably designed to determine, based on the measurement data obtained from the measuring device, the position of a force application point of a force acting on a bending workpiece held by the workpiece gripper, relative to a known reference point of the handling robot. The determined position can be used, for example, for position correction at the backgauge.

[0014] The robot control unit can, for example, contain a coordinate transformation model, particularly a mathematical one, and be configured to determine the position of the force's point of application relative to the handling robot's reference point using this model. A coordinate transformation allows for a rapid and precise calculation of the position. The reference point can be fixed or, if necessary, variable via the robot control unit. Mathematical coordinate transformations are known in the prior art.

[0015] In a further aspect, the invention relates to a bending machine with a stationary lower bending beam and an upper bending beam movable relative to it in a bending plane, wherein a lower tool is arranged or can be arranged on the lower bending beam and an upper tool is arranged or can be arranged on the upper bending beam, wherein the bending machine comprises a machine control unit for controlling at least one drive of the upper bending beam, wherein a handling robot as described above is provided on a first side of the bending plane.

[0016] Preferably, a backgauge, preferably sensorless, is provided on a second side of the bending plane opposite the first side for positioning a workpiece to be bent relative to the bending plane, and the robot control unit is designed to determine, on the basis of the measurement data obtained from the sensor device of the measuring device, an actual position of a force application point of a workpiece held with the workpiece gripper on the backgauge relative to the reference point of the handling robot, on the basis of the actual position and a predetermined target position of the force application point, to determine a control variable for the positioning drive of the handling robot and to control the positioning drive with the control variable in order to position the workpiece to the target position.

[0017] The machine control unit can be designed to determine the target position for the bending workpiece from process data for a bending operation to be carried out on the bending workpiece, which are implemented in the machine control unit, and to transmit the target position to the robot control unit.

[0018] The problem is further solved by a method for operating a bending machine with a stationary lower bending beam and an upper bending beam movable relative to it in a bending plane, wherein the lower bending beam comprises a lower tool and the upper bending beam comprises a upper tool, wherein a movement of the upper bending beam is controlled by a machine control unit, wherein a handling robot is provided on a first side of the bending plane for feeding a workpiece to be bent into the bending plane, wherein the handling robot comprises a workpiece gripper for gripping a number of workpieces and wherein the handling robot is controlled by a robot control unit, wherein a sensor device of a measuring device, which mechanically connects an end section of a robot arm of the handling robot to the workpiece gripper,A force and / or torque acting on the workpiece gripper is detected, and the robot control unit uses the detected force and / or torque to control the handling robot, in particular a positioning drive. This results in the advantages already described.

[0019] Preferably, the robot control unit uses the detected force and / or torque to determine the mass of a number of bending workpieces held by the workpiece gripper. Based on this determined mass and a predefined mass of a single bending workpiece, the robot control unit then determines the number of bending workpieces actually held. Preferably, the bending process is interrupted if more than one bending workpiece is detected. This enables simple double-sheet detection without the need for complex sensors, such as laser-based ones.Preferably, a backgauge, preferably sensorless, is provided on a second side of the bending plane opposite the first side for positioning the workpiece relative to the bending plane. The robot control unit uses measurement data from the sensor device of the measuring device to determine the actual position of a force application point of a workpiece held by the workpiece gripper on the backgauge relative to a known reference point of the handling robot. Based on the actual position and a predetermined target position of the force application point, a control variable for a positioning drive of the handling robot is determined, and the positioning drive is controlled with this variable to position the workpiece at the target position. This enables simple and precise position correction of the workpiece.

[0020] To better understand the invention, it is explained in more detail with reference to the following figures.

[0021] They each show, in a highly simplified, schematic representation:

[0022] Fig. 1 shows a bending machine with a handling robot in an exemplary embodiment of the invention;

[0023] Fig. 2 shows a perspective view of a measuring device according to the invention;

[0024] Fig. 2a shows an exemplary measuring plate in a perspective view;

[0025] Fig. 3 shows a perspective view of a section of a handling robot with a workpiece gripper and a measuring device according to the invention;

[0026] Fig. 4 shows an example of a coordinate transformation for determining the position of a force application point.

[0027] It should be noted at the outset that in the differently described embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the positional designations chosen in the description, such as top, bottom, side, etc., refer to the figure directly described and illustrated, and these positional designations must be applied analogously to the new position if the position changes.

[0028] Figure 1 shows an exemplary embodiment of a bending machine 3. The bending machine 3 is designed to perform a bending operation on a workpiece W. The workpiece W is, in particular, a sheet metal workpiece. The bending machine 3 has a lower bending beam 20 with a lower tool holder 23 for receiving a lower tool 24 and an upper bending beam 21 with an upper tool holder 25 for receiving a top tool 26. The top tool 26 and the lower tool 24 can be interchangeable, preferably automatically.

[0029] To perform the bending operation, the upper bending beam 21 is movable in a bending plane 22, preferably vertical, relative to the lower bending beam 20. The bending machine 3 further comprises a known backgauge 19 for positioning the workpiece 3 relative to the bending plane 22 for the bending operation. The backgauge 19 is arranged on a first side of the bending plane 22. The backgauge 19 can be designed in a known manner, for example, as a 4-axis, 5-axis, or 6-axis backgauge. Depending on the design, the backgauge 19 has one or more stop fingers that can be positioned in space. A suitable actuator 31 is generally provided for positioning. The function and design of the backgauge 19 are known in the prior art, therefore no further description is given here.

[0030] The bending machine 3 further comprises a machine control unit 12 for controlling the bending machine 3. The machine control unit 12 can, in a known manner, include suitable hardware and / or software. Such control units are known in the prior art. The machine control unit 12 can, for example, also control the actuator 31 of the backgauge 19 to position the backgauge finger(s) in space.

[0031] On the second side of the bending plane 22, opposite the first side, a handling robot 2 is provided, which is designed to position the workpiece W in the bending machine 3 against the backgauge 19. The handling robot 2 can be a suitable industrial robot, such as a multi-axis robot, in particular a 6-axis robot. The handling robot 2 comprises a robot arm 6 with an end section 5 to which a workpiece gripper 8, preferably interchangeable, is attached. The workpiece gripper 8 serves to grasp and hold the workpiece W to be bent. The workpiece gripper 8 can, for example, comprise a known vacuum gripper, as indicated in Fig. 1. However, the workpiece gripper 8 could also be designed differently, for example, in the form of a pincer gripper or a combined gripper that comprises both a pincer gripper and a vacuum gripper (see Fig. 3).

[0032] Furthermore, the handling robot 2 can assist in moving the workpiece W during the bending process, if necessary according to a predefined bending trajectory T. The bending trajectory T is indicated by an arrow in Fig. 1. The handling robot 2 comprises a robot control unit 11, which may include suitable hardware and / or software. The robot control unit 11 can be connected to the machine control unit 12 via a suitable communication link or may optionally be integrated into the machine control unit 12. The machine control unit 12 can communicate with the robot control unit 11 to coordinate the movement of the upper bending beam 21 and the movement of the robot arm 6 or the workpiece gripper 8 attached to it during the bending process.

[0033] A measuring device 1 according to the invention is attached to the end section 5 of the robot arm 6, which mechanically connects the end section 5 to the workpiece gripper 8. An exemplary embodiment of the measuring device 1 is described in more detail below with reference to Fig. 2.

[0034] Fig. 2 shows a perspective view of the measuring device 1. The measuring device 1 has a first mounting section 4 for attaching the measuring device 1 to the end section 5 of the robot arm 6 of the handling robot 2. Furthermore, the measuring device 1 has a second mounting section 7, opposite the first mounting section 4 in the direction of a longitudinal axis L of the measuring device 1, for attaching the workpiece gripper 8. The measuring device 1 also includes a sensor device 9, which is configured to detect a force F acting on the workpiece gripper 8 and transmitted to the measuring device 1 via the second mounting section 7, and / or a transmitted torque M. The force F is indicated by an arrow in Fig. 1.Depending on where and in which direction the force F acts on the workpiece W being bent, a torque can also be transmitted to the measuring device 1, which can be detected by the sensor device 9. In the illustrated embodiment, the measuring device 1 has a sensor interface 10 for transmitting the acquired measurement data from the sensor device 9 to the robot control unit 11 of the handling robot 2. Alternatively or additionally, the measurement data could also be transmitted via the sensor interface 10 to the machine control unit 12 of the bending machine 3. The measurement data processing can take place in the respective control unit. However, the measuring device 1 could also include a suitable signal processing unit 32, which processes the sensor signals acquired by the sensor device 9 and, if necessary, converts them into desired measured values.To supply the signal processing unit 32 with the necessary electrical energy, a power supply connection 34 can be provided, e.g. in the form of a plug. In the illustrated embodiment, the power supply connection 34 and the sensor interface 10 are structurally combined, i.e., designed for both data transmission and power transmission.

[0035] The sensor device 9 can, for example, comprise at least one force sensor 13, wherein the force sensor 13 preferably comprises a piezoelectric sensor and / or strain gauges. Such sensors are well known in the prior art. The force sensor 13 is shown schematically in Fig. 2 and can be mounted at a suitable location on the measuring device 1. Of course, several force sensors 13 can also be provided, for example, at least one force sensor 14 per axis of a Cartesian reference coordinate system of the measuring device 1.

[0036] In the illustrated example, the measuring device 1 has a substantially cylindrical housing 14 with the longitudinal axis L as the cylinder axis. The housing 14 contains a measuring plate 33, which includes the sensor device 9.

[0037] The first fastening section 4 is designed such that it cannot be detached during operation of the handling robot 2. In particular, the first fastening section 4 in the illustrated example has a screw flange 29. The second fastening section 7 is designed such that it can be detached during operation of the handling robot 2 to allow for a change of the workpiece gripper 8, preferably automated. The second fastening section 7 includes, in particular, a quick-release fastener 30. Fig. 2a shows a perspective view of an exemplary measuring plate 33. The measuring plate has a significantly shorter length in the direction of the longitudinal axis L compared to its radial extent, in particular its diameter. The length can, for example, be in the range of a few millimeters to a few centimeters. The measuring plate 33 can be easily integrated into the housing 14. The measuring plate 33 includes the sensor device 9.The sensor device 9 can be arranged on an end face of the measuring plate, for example in a suitable recess in the end face.

[0038] The sensor device 9 comprises three force sensors 13 in the form of piezoelectric sensors, which are arranged circumferentially spaced apart from one another with respect to the longitudinal axis L on the measuring plate 33. The force sensors 13 are preferably located in the same sensor plane, which is perpendicular to the longitudinal axis L. The force sensors 13 are each connected to the sensor interface 10. The sensor interface 10 is located on the sound side and aligned parallel to the longitudinal axis L. Of course, a radial arrangement as shown in Fig. 2 would also be conceivable. The measuring plate 33 can also include a signal conditioning unit 32 with a power supply connection 34, as indicated in Fig. 2. For attachment to the housing 14, several mounting holes 35 can be provided, for example. However, other types of attachment are also conceivable.

[0039] Figure 3 shows a perspective view of a section of a robot arm 6 of a handling robot 2 for a bending machine 3. The measuring device 1, described with reference to Figure 2, is arranged at an end section 5 of the robot arm 6 and mechanically connects the end section 5 to the workpiece gripper 8. The end section 5 of the robot arm 6 has a third mounting section 15 to which the first mounting section 4 of the measuring device 1, here the screw flange 29, is attached. The workpiece gripper 8 has a fourth mounting section 16, which is attached to the second mounting section 7 of the measuring device 1, here the quick-release clamp 30.

[0040] The robot control unit 11 is designed to use the measurement data received from the measuring device 1 by the sensor device 9 to control the handling robot 2, in particular a positioning drive 27. The positioning drive 27 is indicated in Fig. 1 and serves to position the robot arm in space. For this purpose, the positioning drive 27 can comprise several separate drives, e.g., one drive for each axis of the multi-axis robot. Control of the workpiece gripper 8 based on the measurement data is also possible.

[0041] The workpiece gripper 8 in Fig. 3 has a vacuum gripper 18 on one side and a gripper 17 on the opposite side. Depending on the type of workpiece W to be bent, either the vacuum gripper 18 or the gripper 17 can be used.

[0042] The robot control unit 11 is preferably designed to determine the mass of a number of bending workpieces W held by means of the workpiece gripper 8 on the basis of the measurement data obtained from the measuring device 1 and to determine the actual number of held bending workpieces W from the determined mass and a predetermined (or predeterminable) mass of a single bending workpiece W.

[0043] Figure 3 shows, by way of example, the weight force FG of the workpiece W to be bent, which is proportional to its mass. The weight force FG can be detected by the sensor device 9, in particular by a force sensor 13 contained therein. The robot control unit 11 can calculate the mass of the workpiece W from the measured weight force FG. The mass of an individual workpiece W to be bent is usually known. The robot control unit 11 can compare the known mass with the measured or determined mass and thus recognize whether more than one workpiece W is being held. The known mass can be transmitted to the robot control unit 11, for example, by the machine control unit 12 of the bending machine 3 (see Figure 1).

[0044] According to an advantageous embodiment, the robot control unit 11 is configured to determine, based on the measurement data obtained from the measuring device 1, the position of a force application point of a force F acting on a bent workpiece W held by the workpiece gripper 8, relative to a known reference point TCP of the handling robot 2. For this purpose, the robot control unit 11 can, for example, include a coordinate transformation model, particularly a mathematical one, and determine the position of the force application point of the force F relative to the reference point TCP of the handling robot 2 using the coordinate transformation model.

[0045] For this purpose, the robot control unit 11 can, for example, have knowledge of the geometry of the bending workpiece W. The geometry data can be transmitted to the robot control unit 11, for example, from a higher-level machine control unit 12 of a bending machine (see Fig. 1) or, if necessary, from another (not shown) overall control unit, which, for example, can in turn be a higher-level control unit of the machine control unit 12.

[0046] Fig. 4 shows a mechanical surrogate model of the bending machine 3 in a top view. The end section 5 of the robot arm 6 of the handling robot 2 is indicated, to which a measuring device 1 according to the invention is attached, as described with reference to Fig. 3. The handling robot 2 (not shown) is located on a first side of the bending plane 22, which is indicated here by a dashed line. The X-axis is perpendicular to the bending plane 22, and the Z-axis runs parallel to the bending plane 22. The R-axis (see Fig. 1) is perpendicular to the X- and Z-axes. The three axes X, Z, R form a (global) orthogonal coordinate system known for bending machines.

[0047] The measuring device 1 connects the end section 5 to the workpiece gripper 8, which is shown here only as an example of a pincer gripper. The workpiece gripper 8 holds a bent workpiece W in the form of a rectangular, flat sheet metal. The bent workpiece W intersects the bending plane 22.

[0048] On the second side of the bending plane 22, opposite the first side, a backgauge 19 is provided for positioning a workpiece W to be bent relative to the bending plane 22. The backgauge 19 is designed without sensors, i.e., it does not include a sensor, in particular no force sensor, for measuring the impact force with which the workpiece W strikes the backgauge 19.

[0049] To perform the coordinate transformation, each component is assigned at least one (local) coordinate system K1-K6 with axes X, R, Z. The origin of the first coordinate system Kl of the backgauge 19 is the desired point of force application of the bending workpiece W on the backgauge 19. The origin of the second coordinate system K2 is the corresponding point of force application of the backgauge 19 on the bending workpiece W. In Fig. 4, the bending workpiece W is in a position before being attached to the backgauge 19; the coordinate systems Kl and K2 are therefore spaced apart. When the bending workpiece W is attached to the backgauge 19, the coordinate systems Kl and K2 are congruent.

[0050] The origin of the third coordinate system, K3, is located, for example, at the center of gravity of the bending workpiece, W. The parameters (e.g., dimensions, position of the center of gravity, etc.) of the bending workpiece, W, are generally known. The origin of the fourth coordinate system, K4, is located, for example, at a defined contact point of the bending workpiece, W, on the workpiece gripper, 8. The origin of the fifth coordinate system, K5, is located, for example, at a defined contact point at the interface between the workpiece gripper, 8, and the measuring device, 1. The origin of the sixth coordinate system, K6, is located, for example, at a defined contact point at the interface between the measuring device, 1, and the end section, 5, of the robot arm, 6, of the handling robot, 2. The origin of the sixth coordinate system, K6, also forms the defined reference point, TCP (tool center point), of the handling robot, 2.

[0051] The robot control unit 11 can determine the actual position of the force application point of the bending workpiece W on the backgauge 19 relative to the reference point TCP of the handling robot 2 based on the measurement data received from the measuring device 1. Instead of the reference point TCP of the handling robot 2, another reference point of interest could of course be chosen, for example, the origin of the aforementioned fifth coordinate system K5 of the measuring device 1.

[0052] The robot control unit 11 can use coordinate transformation to calculate the position of the force application point (here at the origin of the second coordinate system K2) back to the sixth coordinate system K6 or, if necessary, to the fifth coordinate system K5. The handling robot 2, whose control is generally designed for a fixed reference point, for example, the described "tool center point" (TCP), can now use the transformed or calculated position of the force application point to control the handling robot 2. Based on the determined (transformed) actual position and a predefined target position of the force application point, the robot control unit 11 can, for example, determine a control variable for the positioning drive 27 of the handling robot 2 and control the positioning drive 27 with this control variable to position the workpiece W at the predefined target position.The actual position determined from the measured force can therefore be used for position control.

[0053] The target position for the workpiece W being bent can be determined, for example, by the machine control unit 12 from known process data for a bending operation to be performed on the workpiece W. The target position can be transmitted to the robot control unit 11. The process data can be implemented in the machine control unit 12. Of course, multiple sets of process data for different bending operations and / or for different workpieces W can also be stored, which the machine control unit 12 can access.

[0054] The exemplary embodiments show possible embodiment variants, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiment variants, but rather various combinations of the individual embodiment variants are also possible and this possibility of variation lies within the skill of the person skilled in this technical field due to the teaching on technical action by the present invention.

[0055] The scope of protection is defined by the claims. However, the description and drawings must be consulted for the interpretation of the claims. Individual features or combinations of features from the different embodiments shown and described can, in themselves, represent independent inventive solutions. The problem underlying these independent inventive solutions can be found in the description.

[0056] All references to value ranges in this description are to be understood as encompassing any and all sub-ranges thereof, e.g., the reference 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit 1 and the upper limit 10, i.e., all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g., 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0057] Finally, for the sake of clarity, it should be noted that, for better understanding of the structure, some elements have been shown not to scale and / or enlarged and / or reduced. Reference symbols for the table of contents.

[0058] Measuring device 32 Signal processing unit

[0059] Handling robot 33 measuring plate

[0060] Bending machine 34 Power supply connection

[0061] First fastening section 35 fastening hole

[0062] End section of the robot arm TCP reference point

[0063] Robot arm F force

[0064] Second fastening section W Bend workpiece

[0065] Workpiece gripper T bending trajectory

[0066] Sensor device FG weight force

[0067] Sensor interface X, Z, R coordinate axes

[0068] Robot control unit K1-K6 coordinate systems

[0069] Machine control unit E Longitudinal axis of the measuring device

[0070] Force sensor

[0071] Housing

[0072] Third fastening section

[0073] Fourth fastening section

[0074] Gripper gripper

[0075] Vacuum gripper

[0076] Backgauge lower bending beam upper bending beam

[0077] Bending plane first tool holder

[0078] Lower tool second tool holder

[0079] Upper tool

[0080] Positioning drive

[0081] drive of upper bending beam

[0082] screw flange

[0083] quick-release fasteners

[0084] actuator

Claims

Patent claims 1. Measuring device (1) for a handling robot (2) of a bending machine (3), characterized in that the measuring device (1) has a first fastening section (4) for fastening the measuring device (1) to an end section (5) of a robot arm (6) of the handling robot (2) and a second fastening section (7) opposite the first fastening section (4) in the direction of a longitudinal axis (L) of the measuring device (1) for fastening a workpiece gripper (8) designed to grip a bending workpiece (W) and in that the measuring device (1) includes a sensor device (9) designed to detect a force (F) acting on the workpiece gripper (8) and transmitted to the measuring device (1) via the second fastening section (7) and / or a transmitted torque (M).

2. Measuring device (1) according to claim 1, characterized in that the measuring device (1) comprises a sensor interface (10) for transmitting recorded measurement data from the sensor device (9) to a robot control unit (11) of the handling robot (2) and / or to a machine control unit (12) of the bending machine (3).

3. Measuring device (1) according to claim 1 or 2, characterized in that the sensor device (9) comprises at least one force sensor (13), wherein the force sensor (13) preferably comprises a piezo sensor and / or strain gauges.

4. Measuring device (1) according to one of claims 1 to 3, characterized in that the measuring device (1) has a substantially cylindrical housing (14) with the longitudinal axis (L) as the cylinder axis.

5. Measuring device (1) according to one of claims 1 to 4, characterized in that the measuring device (1) has a measuring plate (33) which includes the sensor device (9), wherein the sensor device (9) includes at least three force sensors (13), in particular piezo sensors, which are spaced apart from each other in the circumferential direction with respect to the longitudinal axis (L) on the measuring plate (33), wherein the at least three force sensors (13) are preferably located in a sensor plane normal to the longitudinal axis (L).

6. Measuring device (1) according to one of claims 1 to 5, characterized in that the measuring device (1) has a signal conditioning unit (32) which is configured to determine a measured quantity from the sensor quantity measured by the sensor device (9) and comprises a power supply connection (34) for supplying the signal conditioning unit (32) with electrical energy, wherein preferably the power supply connection (34) and the sensor interface (10) are structurally combined.

7. Measuring device (1) according to one of claims 1 to 6, characterized in that the first fastening section (4) is designed to be non-releasable during operation of the handling robot (2), wherein the first fastening section (4) preferably has a screw flange (29), and / or that the second fastening section (7) is designed to be releasable during operation of the handling robot (2) in order to enable a, preferably automated, change of the workpiece gripper (8), wherein the second fastening section (7) preferably comprises a quick-release fastener (30).

8. Handling robot (2) for a bending machine (3), for handling bent workpieces (W), wherein the handling robot (2) comprises a workpiece gripper (8) for gripping a number of bent workpieces (W) and has a robot control unit (11) for controlling the handling robot (2), characterized in that the handling robot (2) comprises a measuring device (1) according to one of claims 1 to 7, which mechanically connects an end section (5) of a robot arm (6) of the handling robot (2) to the workpiece gripper (8), wherein the end section (5) of the robot arm (6) comprises a third mounting section (15) to which the first mounting section (4) of the measuring device (1) is attached, and the workpiece gripper (8) comprises a fourth mounting section (16) which is attached to the second mounting section (7) of the measuring device (1), and that the robot control unit (11) is configured toto use the measurement data obtained from the measuring device (1) to control the handling robot (2), in particular a positioning drive (27) of the handling robot (2).

9. Handling robot (2) according to claim 8, characterized in that the workpiece gripper (8) comprises a vacuum gripper (18) and / or a gripper (17).

10. Handling robot (2) according to claim 8 or 9, characterized in that the robot control unit (11) is designed to determine a mass of a number of bending workpieces (W) held by means of the workpiece gripper (8) on the basis of the measurement data obtained from the measuring device (1) and to determine the actual number of held bending workpieces (W) from the determined mass and a predetermined or predeterminable mass of a single bending workpiece (W).

11. Handling robot (2) according to one of claims 8 to 10, characterized in that the robot control unit (11) is configured to determine, on the basis of the measurement data obtained from the sensor device (9) of the measuring device (1), a position of a force application point of a force (F) acting on a bending workpiece (W) held by the workpiece gripper (8), relative to a known reference point (TCP) of the handling robot (2).

12. Handling robot (2) according to claim 11, characterized in that the robot control unit (11) contains a coordinate transformation model and is configured to determine the position of the force application point of the force (F) relative to the reference point (TCP) of the handling robot (2) using the coordinate transformation model.

13. Bending machine (3) with a stationary lower bending beam (20) and an upper bending beam (21) movable relative to it in a bending plane (22), wherein a lower tool (24) is arranged or can be arranged on the lower bending beam (20) and an upper tool (26) is arranged or can be arranged on the upper bending beam (21), wherein the bending machine (3) comprises a machine control unit (12) for controlling at least one drive (28) of the upper bending beam (21), wherein a handling robot (2) according to one of claims 8 to 12 is provided on a first side of the bending plane (22).

14. Bending machine (3) according to claim 13 with a handling robot (2) according to claim 11 or 12, wherein a backgauge (19), preferably sensorless, for positioning a bending workpiece (W) relative to the bending plane (22) is provided on a second side of the bending plane (22) opposite the first side, characterized in that the robot control unit (11) is configured to determine the position of the workpiece (W) relative to the bending plane (22) on the basis of the The sensor device (9) of the measuring device (1) obtains measurement data to determine the actual position of a force application point of a bending workpiece (W) held by the workpiece gripper (8) at the back gauge (19) relative to the reference point (TCP) of the handling robot (2), to determine a control variable for the positioning drive (27) of the handling robot (2) based on the actual position and a predetermined target position of the force application point, and to control the positioning drive (27) with the control variable in order to position the bending workpiece (W) at the target position.

15. Bending machine (3) according to claim 14, characterized in that the machine control unit (12) is configured to determine the target position for the bending workpiece (W) from process data for a bending operation to be carried out on the bending workpiece (W), which are implemented in the machine control unit (12) and to transmit the target position to the robot control unit (11).

16. Method for operating a bending machine (3) with a stationary lower bending beam (20) and an upper bending beam (21) movable relative to it in a bending plane (22), wherein the lower bending beam (20) comprises a lower tool (24) and the upper bending beam (21) comprises a upper tool (26), wherein a movement of the upper bending beam (21) is controlled by a machine control unit (12), wherein a handling robot (2) for feeding a bending workpiece (W) to the bending plane (22) is provided on a first side of the bending plane (22), wherein the handling robot (2) comprises a workpiece gripper (8) for gripping a number of bending workpieces (W) and wherein the handling robot (2) is controlled by a robot control unit (11), characterized in that a sensor device (9) of a measuring device (1),which mechanically connects an end section (5) of a robot arm (6) of the handling robot (2) with the workpiece gripper (8), a force (F) and / or torque (M) acting on the workpiece gripper (8) is detected, and the robot control unit (11) uses the detected force (F) and / or torque (M) to control the handling robot (2), in particular a positioning drive (27) of the handling robot (2).

17. Method according to claim 16, characterized in that the robot control unit (11) determines the mass of a number of bending workpieces (W) held by the workpiece gripper (8) based on the detected force (F) and / or torque (M), that the robot control unit (11) determines the number of bending workpieces (W) actually held based on the determined mass and a predetermined mass of a single bending workpiece (W), and that preferably the execution of the further bending process is interrupted if more than one bending workpiece (W) is detected.

18. Method according to claim 16 or 17, characterized in that a backstop (19), preferably sensorless, is provided on a second side of the bending plane (22) opposite the first side for positioning the bending workpiece (W) relative to the bending plane (22), that the robot control unit (11) determines an actual position of a force application point of a bending workpiece (W) held by the workpiece gripper (8) on the backstop (19) relative to a known reference point (TCP) of the handling robot (2) on the basis of the measurement data obtained from the sensor device (9) of the measuring device (1), determines a control variable for a positioning drive (27) of the handling robot (2) on the basis of the actual position and a predetermined target position of the force application point, and controls the positioning drive (27) with the control variable in order to position the bending workpiece (W) at the target position.

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