BENDING DEVICE HAVING WORKPIECE GUIDANCE BY A MULTI-ARTICULATED ARM ROBOT

Abstract

The invention relates to a bending device (2) for bending a rod-like or tubular workpiece (4), comprising a bending machine (6), which has a bending head (8), which is designed for bending the workpiece (4) in a forming process, and a control means (24), which controls the operation of the bending machine (6), a robot (10), which comprises a multi-joint arm (11) which can be adjusted by motors, having a gripper end (12), which is designed for gripping and holding the workpiece (4), and a control unit (22), which is designed to control the operation of the robot (10), wherein the control means (24) is designed to control the bending machine (6) and the robot (10) during the bending process. The control unit (22) of the robot (10) is switched, at least during the bending process, to a slave mode in which it receives control commands from the control means (24) of the bending machine (6), and the control means (24) of the bending machine (6), during the bending process, continuously issues setting specifications for the motor-adjustable multi-joint arm (11) and the gripper end (12) to the control unit (22) of the robot (10) which has been switched to slave mode and thereby controls the robot (10) to introduce the workpiece (4) into the bending head (8), to stabilize the workpiece during the forming process and to remove the workpiece from the bending head (8) after the forming process.

Claims

1. A bending apparatus for bending a rod-shaped or tubular workpiece into a multiple-bend geometry in a working process, the apparatus comprising: a bending machine comprising a bending head for bending the workpiece, wherein position and status of the bending head are described according to bending machine axes; a bending machine control device including a bending machine processor controlling operation of the bending machine, wherein the bending machine control device comprises a programming system for creating a bending program on basis of the multiple-bend geometry, wherein the bending program defines a sequence of working each generating a bend with the bends being located in specified spacings from each other and each bend being located in a particular bending plane; a robot comprising: a multi-articulated arm comprising an arm end and several robot arm axes which are individually adjustable by motor regarding rotation angles of the robot arm axes; a gripping tool mounted to the arm end and, thus moved by the arm, and adapted to grip and hold the rod-shaped or tubular workpiece, the gripping tool having a tool center referenced to the workpiece that is held by the gripping tool; and a robot control unit adapted to control the arm regarding the rotational angles of the robot arm axes, wherein the programming system generates target values for the bending machine axes and for the robot arm axes on basis of the bending program and by performing an axis transformation that uses a mathematical relationship between the rotation angles of the robot arm axes and the position of the tool center, wherein during the working process, the robot control unit runs in a slave mode, in which the robot control unit receives control commands and adjusts the rotational angles of the robot arm axes according to the control commands, and wherein the bending machine processor is adapted to indirectly control the robot during the working process by providing the generated target values and for the robot arm axes as the control commands to the robot control unit running in the slave mode, such that the gripping tool stabilizes the workpiece during the sequence of workings producing the multiple-bend geometry.

2. The bending apparatus as claimed in claim 1, wherein in the slave mode the robot control unit feeds-back actual values of the robot arm axes and of the gripping tool to the bending machine control device.

3. The bending apparatus as claimed in claim 1, wherein the robot arm axes and the bending machine axes have different coordinate systems and the bending machine control device interpolates the coordinate system of robot arm axes with the bending machine axes.

4. The bending apparatus as claimed in claim 1, comprising at least one second comprising a second multi-articulated arm comprising an second arm end and several second robot arm axes which are individually adjustable by motor regarding second rotation angles of the second robot arm axes, a second gripping tool mounted to the arm end and, thus moved by the second arm, and adapted to grip and hold the rod-shaped or tubular workpiece, the second gripping tool having a second tool center referenced to the workpiece that is held by the gripping tool, and a second robot control unit adapted to control operation of the second arm, wherein all of the robot control units are switched to the slave mode during the working process and receive the control commands from the bending machine control device such that the two robots cooperate in the working process.

5. The bending apparatus as claimed in claim 1, wherein the gripping tool repositions the workpiece during the working process.

6. The bending apparatus as claimed in claim 1, wherein the robot inserts the workpiece into the bending head prior to the working process and removes it from the bending head after the working process is finished.

7. The bending apparatus as claimed in claim 1, wherein the robot control unit comprises an independent mode of operation, in which the robot control unit controls the multi-articulated arm without receiving control commands.

8. The bending apparatus as claimed in claim 1, wherein the robot orients the workpiece for the sequence of workings each generating a bend and sets the spacings and the bending planes of the bends by means of appropriate alignment of the gripping tool.

9. A method for bending a rod-shaped or tubular workpiece into a multiple-bend geometry in a working process, the method comprising the steps of: providing a bending machine comprising a bending head for bending the workpiece and using bending machine axes to describe position and status of the bending; providing a bending machine control device including a bending machine processor controlling operation of the bending machine, wherein the bending machine control device comprises a programming system creating a bending program on basis of the multiple-bend geometry by using the programming system, wherein the bending program defines a sequence of workings each generating a bend with the bends being located in specified spacings from each other and each bend being located in a particular bending plane; providing a robot comprising: a multi-articulated arm comprising an arm end and several robot arm axes which are individually adjustable by motor regarding rotation angles of the robot arm axes; a gripping tool mounted to the arm end and, thus moved by the arm, and adapted to grip and hold the rod-shaped or tubular workpiece, the gripping tool having a tool center referenced to the workpiece that is held by the gripping tool; and a robot control unit adapted to control the arm regarding the rotational angles of the robot arm axes, generating target values for the bending machine axes and for the robot arm axes on basis of the bending program and by performing an axis transformation using a mathematical relationship between the rotation angles of the robot arm axes and the position of the tool center; operating the robot control unit in a slave mode, in which the robot control unit receives control commands and adjusts the rotational angles of the robot arm axes according to the control commands; and performing the working process according to the bending program, wherein the bending machine processor indirectly controls the robot by providing the generated target values and for the robot arm axes as the control commands to the robot control unit running in the slave mode, such that the gripping tool stabilizes the workpiece during the sequence of workings producing the multiple-bend geometry.

10. The method as claimed in claim 9, wherein in the slave mode the robot control unit feeds-back actual values of the robot arm axes and of the gripping tool to the bending machine control device.

11. The method as claimed in claim 9, wherein the robot arm axes and the bending machine axes have different coordinate systems and the bending machine control device interpolates the coordinate system of robot arm axes with the bending machine axes.

12. The method as claimed in claim 9, further including the step of providing at least one second robot comprising a second multi-articulated arm comprising an second arm end and several second robot arm axes which are individually adjustable by motor regarding second rotation angles of the second robot arm axes, a second gripping tool mounted to the arm end and, thus moved by the second arm, and adapted to grip and hold the rod-shaped or tubular workpiece, the second gripping tool having a second tool center referenced to the workpiece that is held by the gripping tool, and a second robot control unit adapted to control operation of the second arm, wherein all of the robot control units are switched to the slave mode during the working process and receive the control commands from the bending machine control device such that the two robots cooperate in the working process.

13. The method as claimed in claim 9, wherein the gripping tool repositions the workpiece during the working process.

14. The method as claimed in claim 9, wherein the robot inserts the workpiece into the bending head prior to the working process and removes it from the bending head after the working process is finished.

15. The method as claimed in claim 9, wherein the robot control unit comprises an independent mode of operation, in which the robot control unit controls the multi-articulated arm without recieving control commands.

16. The method as claimed in claim 9, wherein the robot orients the workpiece for the sequence of workings each generating a bend and sets the spacings and the bending planes of the bends by means of appropriate alignment of the gripping tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the figures:

[0029] FIG. 1 shows a depiction of a bending apparatus for bending rod-shaped or tubular workpieces and

[0030] FIG. 2 shows a block diagram of the control of the bending apparatus in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1 shows a bending apparatus 2, designed to bend a workpiece 4, which is tubular in this instance. The bending apparatus 2 comprises a bending machine 6 having a bending head 8. Such bending machines are known in principle to a person skilled in the art, for example from the cited EP 3266529 A1. When the workpiece 4 is inserted on the bending head 8, the latter performs a bending working process for the workpiece 4. The workpiece 4 is supplied by a robot 10, inserted into the bending head 8 and held during the working process. To this end, the robot 10 has a gripping tool 12 that grips and holds the workpiece 4, in particular while it is machined by the bending head 8. The bending head 8 in FIG. 1 operates on the basis of the unrolling working process. Unrolling bending does not involve the workpiece 4 being drawn in. The gripping tool 12 and the robot 10 therefore hold the workpiece 4 during the working process. In other embodiments, the working process can require the workpiece 4 to be drawn in on the bending head 8. For these cases, the robot 10 uses its gripping tool 12 to reposition the workpiece 4 by virtue of the gripping tool 12 following the movement of the workpiece 4 during the working process. In both variants, the gripping tool 12 of the robot 10 stabilizes the workpiece during the working process. Furthermore, the robot 10 orients the workpiece for the multiple bends. Appropriate alignment of the gripping tool 12 sets the intervals between the bends and the rotation of the bending planes relative to one another. In the case of 2D workpieces, the bending planes remain unchanged; the same bending plane is therefore stipulated for all bends.

[0032] The robot 10 is a multi-articulated arm robot having a robot arm 11 that has a multiplicity of rotary joints 16-21. A robot of this type is available from Kuka AG, for example. In the present case, a robot 10 having six axes is involved. The number of axes is purely exemplary, however. The robot arm 11 is adjustable at the rotary joints 16-21 by electric motors, which means that the gripping tool 12 is adjustable in three dimensions in space, as is the orientation of the workpiece 4 for the bending cold reshaping operations therefore.

[0033] The robot is a multipurpose robot and therefore has a separate control unit 22 allowing the robot 10 to be controlled freely. If the robot 10 is operated independently, the control unit 22 would have an appropriate program stored that controls the operation of the robot 10. This independent operation quite consciously does not take place, however. The bending machine 6 has a control device 24 that controls the operation of the bending machine 6 and in particular the action of the bending head 8. The control unit 22 and the control device 24 are connected to the robot 10 or bending machine 6 that they control via lines, which are not designated more specifically. They are also connected to one another for control purposes in order to ensure the coordinated operation of the robot 10 and the bending machine 6 during the working process on the workpiece 4. The control device 24 is hierarchically superordinate to the control unit 22 in this instance.

[0034] The interaction of the control unit 22 and the control device 24 is depicted schematically in FIG. 2. The control device 24 is connected to the control unit 22 by means of bidirectional data interchange. The control device 24 sends stipulation data 26 to the control unit 22 and receives confirmation data 28 therefrom. It also comprises a programming device 30.

[0035] The movements to be carried out by the robot 10 are not stored in the control unit 22 in the form of a control program, but rather are programmed completely in the control device 24 of the bending machine 6, for example by means of the programming device 30. To machine a workpiece 4, the control unit 22, which would be inherently and independently capable of independent control of the robot 10, runs in a slave mode, in which it merely receives stipulation data 26 from the control device 24 and sets the drives at the rotary joints 16-21 in accordance with these stipulation data 26. The control device 24, which is provided as a CNC controller in the exemplary embodiment, interprets the bending program entered for it and generates setpoint data both for the axes of the bending machine 6 and for the robot. The target values for the robot are routed as stipulation data 26 to the control unit 22, which sets the drives at the rotary joints 16-21 and the gripping tool 12 as appropriate.

[0036] In a first variant embodiment the stipulation data 26 indicate the orientation of a tool center point of the gripping tool 12 in a coordinate system 25. The tool center point is the center of the gripping tool 12 referenced to the workpiece 4 that is held. In this manner, the tool center point of the gripping tool 12 of the robot 10 can be moved in the Cartesian coordinate system 25. The stipulation data 26 contain the setpoint location and the setpoint orientation for the tool center point of the gripping tool 12.

[0037] In a second variant embodiment the stipulation data 26 indicate the setting of the axes of the robot 10. For this purpose, the control device 24 performs an axis transformation that produces a mathematical relationship between rotation angles of the robot axes and the position of the tool center point on the robot 10. This axis transformation can be performed in the control device 24 or else in the control unit 22.

[0038] It is fundamental for the stipulation data 26 in both variant embodiments that the control device 24 can interpolate the axes of the bending machine 6 with the Cartesian coordinate system 25 for the tool center point of the gripping tool 12 of the robot 10. In this manner, the robot 10 can e.g. hold or suitably reposition the workpiece 4 on the bending head 8 during bending and perform the change of orientation between multiple working processes.

[0039] Since the control is ultimately stipulated by the control device 24, and the control unit 22 is only in the slave mode, optimum synchronism of the movement of the robot 10 and the bending machine 6 is automatically produced and the accuracy with which the workpiece 4 is bent is increased.

[0040] Further, the programming device 30 is not used to produce a specific robot control program in the syntax stipulated by the control unit 22, but rather the robot axes are programmed in exactly the same manner as the axes of the bending machine 6. It is possible both to program the individual rotational axes of the robot 10 and to program the robot in the coordinate system 25. The selection can be made in this instance on the basis of simplicity of the programming or prior knowledge of the operator. In both cases, he requires no knowledge of the programming interface of the robot 10.