Folding robot with central folding force detection and method for operating and modernizing folding robot

Abstract

The invention relates to a folding robot which is designed to perform a folding operation, having a folding head (1) which comprises an attachment element (16), a connection element (11), a head element (13) and a folding roller (151, 152, 153), the connection element (11) being arranged between the attachment element (16) and the head element (13) and the folding roller (151, 152, 153) being arranged on the head element (13). A part of the connecting element (11) is designed as a measuring body (111), the measuring body (111) being designed with a sensor element (17) for detecting a folding force (5) exerted on the folding flange by one of the folding rollers (151, 152, 153) during a folding operation. The invention also relates to a method for modernizing a folding robot, in which the old connecting element is replaced with a new connecting element (11) having a measuring body (111) and a sensor element (17). Finally, the invention relates to a method for operating a folding robot having a folding head (1), in which the folding force exerted on the folding flange is determined by detecting an elastic deformation of the connecting element (11).

Description

[0001] The present invention relates to a hemming robot having a robotic hemming head for performing a hemming operation, the robotic hemming head including an attachment element, a connecting element, a head element, and at least one hemming roller, wherein the connecting element is arranged between the attachment element and the head element, and the at least one hemming roller is arranged on the head element. Furthermore, the present invention relates to a method for operating a hemming robot of this type, and the present invention relates to a method for modernizing a hemming robot having an attachment element, a first connecting element, a head element, and at least one hemming roller, wherein the first connecting element is arranged between the attachment element and the head element, and the at least one hemming roller is arranged on the head element.

[0002] This type of hemming robot is known in the prior art and is used, for example, in the automotive industry to connect an outer body part to an inner body part. Typical components of this type of assembly are the hood, the doors, and the wings. In particular for quality control reasons, during the hemming operation, an as-ideal-as-possible hemming force should be applied to the hemming flange. In this regard, KR 2086813B1 has disclosed monitoring the hemming operation for this purpose. Additionally, DE 10 2010 051025A1 has disclosed a hemming robot having a force measurement section, wherein the force measurement section detects the contact force of the hemming roller and is arranged between the joint area of the robot arm and the hemming roller. Furthermore, DE 10 2004 032 392A1 has disclosed a hemming device, wherein the hemming force of the hemming roller is detected by means of a sensor on the axis of the hemming roller, wherein the actual force applied by means of the hemming roller of the incremental hemming path is detected and compared with a setpoint force in order to adapt the hemming force to be applied in the next increment to the setpoint force in the case of a deviation.

[0003] Disadvantageously, in the case of the described embodiments, the sensor is in each case precisely assigned to one hemming roller. In the case of a hemming robot having a plurality of hemming rollers configured for different hemming operations, a corresponding number of sensors must be provided in this regard, especially in the case where the hemming rollers are interchanged. This is because new sensors must be integrated in the case of each replacement of a hemming roller or the entire head element. As a result, the wiring complexity and the calibration complexity are increased. Additionally, existing hemming robots may not be satisfactorily retrofitted without this type of force detection. Additionally, since the adaptation of the actual force to the setpoint force is actually carried out in real time, a high-performance and thus expensive computing unit is required, or the hemming operation may be carried out only relatively slowly.

[0004] Furthermore, WO 2013 / 149 894A1 describes a forming die and a forming method for hemming workpieces by means of a robotic operation. Here, without changing the path programming in the robot controller, the hemming force exerted by the forming die during hemming is adjusted by means of a controllable actuating element. A detection device for the contact force by which the hemming roller presses against the workpiece provides values for the control device of the actuating element and thus increases or decreases the contact force exerted via the forming die.

[0005] In this context, the object of the present invention is to provide an improved hemming robot and an improved method for operating a hemming robot. Additionally, the possibility should be provided that existing hemming robots can be retrofitted in a relatively simple manner to have a hemming force measuring device. In particular, the force measuring device should act independently of the roller configuration, in particular independently of the type of hemming roller and independently of the position of the hemming roller, and the force measuring device should be advantageously retrofittable in a modular manner.

[0006] To achieve this object, a hemming robot, a method for modernizing a hemming robot, and a method for operating a hemming robot as claimed in the independent claims are proposed. Further advantageous refinements of the invention are described in the dependent claims and the description and illustrated in the drawings.

[0007] The proposed solution provides a hemming robot configured to perform a hemming operation, the hemming robot having a robotic hemming head, wherein the robotic hemming head includes an attachment element, a connecting element, a head element, and at least one hemming roller. Here, the connecting element is arranged between the attachment element and the head element, at least one hemming roller is arranged on the head element, and at least one part of the connecting element is configured as a measuring element, wherein the measuring element is configured to have at least one sensor element, and at least one sensor element is arranged on the measuring element for detecting the hemming force applied to the hemming flange by means of one of the at least one hemming rollers during the hemming operation. Relative to the measuring element by means of which the hemming force can be measured, in particular by means of applied strain gauges, the connecting element advantageously serves as a central element of the hemming robot, in particular as a middleware or a complete connecting element of the connecting element, so that the force measurement can advantageously be carried out independently of the roller configuration. Due to the fact that the complete connecting piece between the attachment element and the head element is thus advantageously configured as a measuring element, the measuring element with the sensor element assigned to the measuring element is advantageously configured for the precise detection of the hemming force applied by the hemming roller to the hemming flange and is also advantageously configured for the detection of the direction of action of the force. Here, the measuring element and the at least one sensor element advantageously form a sensor unit for detecting the hemming force during the hemming operation. Due to the configuration of the measuring element as an intermediate element between the connecting element and the head element, the force vector for the correspondingly detected hemming force can advantageously be assigned, in each case, in particular to a discrete number of predefined measuring points. Thus, not only the pure absolute value for the hemming force is advantageously determined, but also, in particular, the direction of action of the hemming force. In particular, it is provided that the hemming robot includes a plurality of hemming rollers, and the plurality of hemming rollers are preferably arranged on the head element in a star-shaped manner. The hemming robot advantageously includes a plurality of hemming rollers with different configurations arranged on the head element, wherein the hemming robot is advantageously configured to perform different hemming operations by means of the hemming rollers with different configurations.

[0008] Here, the acting hemming force is particularly affected by the movement path predefined for the hemming robot by the robot, which movement path is also frequently referred to hereinafter as the hemming path. The hemming robot advantageously does not include additional actuators acting on the hemming rollers and by means of which the hemming force can be changed, which advantageously makes the hemming robot cheaper, more robust and thus less prone to failure.

[0009] The hemming force exerted by the corresponding hemming roller on the hemming flange is advantageously detected in each case by means of a measuring element and at least one sensor element arranged on the measuring element. In particular, an improvement is provided in which the measuring element precisely comprises one sensor element. In particular, a plurality of sensor elements can be provided in order to improve the measurement result. However, in order to be able to assign one sensor element to each hemming roller, a plurality of sensor elements are not required. In particular, the sensor unit formed by the measuring element and at least one sensor element, in particular one sensor element, is provided for a plurality of hemming rollers, and the sensor unit is advantageously configured to detect the respective hemming forces for the hemming operations of the plurality of hemming rollers.

[0010] According to a particularly advantageous improvement, the measuring element has an elastically deformable configuration, in particular capable of elastic deformation in all three spatial directions, that is to say, in particular, in the X direction, the Y direction and the Z direction. Here, at least one sensor element, in particular a plurality of sensor elements, is advantageously configured to detect the elastic deformation of the measuring element. Due to the deformability in all three spatial directions, the force vector can advantageously be determined for the acting hemming force, and thus, in addition to determining the magnitude of the acting force, the direction of action of the force can also be advantageously determined. Strain gauges, in particular strain gauges with measuring amplifiers, are particularly provided as sensor elements for force measurement. In particular, it is provided that the sensor element is a sensor element utilizing the piezoelectric effect, a sensor element utilizing the (piezo)resistive effect, a sensor unit utilizing the thermoresistive effect, a sensor element utilizing the magnetoresistive effect, a sensor element utilizing the magnetostrictive effect, a sensor element utilizing the Hall effect, a sensor element utilizing the inductive effect and / or a sensor element utilizing the capacitive effect. In particular, the sensor element can also be constructed on the basis of other known physical principles for this purpose, in particular also constructed as a vibrating wire sensor instead of utilizing a strain gauge.

[0011] Another advantageous improvement of the hemming robot provides that the connecting element, in particular the measuring element, has a columnar configuration. Due to the replaceability of the "column" element and the fact that the force measurement achieved by means of the measuring element and at least one sensor element is practically the same in terms of installation space, there is advantageously the possibility of retrofitting an "old" system. Additionally, in the case of the columnar improvement, the deformation acting on the measuring element during the hemming operation can be detected particularly satisfactorily.

[0012] The measuring element also advantageously has a geometrically optimized design for measurement. In particular, the measuring element is formed by struts which are connected to one another and in particular form a frame structure. In this type of improvement, the elastic deformation of the struts at the nodes can be detected particularly advantageously in an improved manner. Thus, the hemming force can be detected advantageously with further improved accuracy.

[0013] According to another advantageous refinement, the connecting element has a first connecting part and a second connecting part, wherein the connecting element is advantageously connected to the attachment element via the first connecting part and to the head element via the second connecting part. In this regard, the connecting parts are advantageously connecting joints leading to the attachment element and the head element, and the attachment element can in particular be configured as a docking plate. The measuring element is advantageously the part of the connecting element between the first connecting part and the second connecting part.

[0014] Another advantageous refinement provides that the hemming robot is assigned a computing unit. The computing unit is advantageously configured to detect and process sensor signals provided by at least one sensor element, in particular for determining the hemming force distribution. The hemming operation, in particular the hemming force applied, is also advantageously controlled by means of the computing unit. Here, at least one actuating unit is advantageously actuated by means of the computing unit in order to perform the hemming operation. The computing unit also advantageously includes a measuring amplifier for the sensor signals provided by at least one sensor element. In particular, it is provided that the hemming robot includes a computing unit, wherein the computing unit can in particular be arranged on the attachment element. According to a design variant, it is provided that the computing unit assigned to the hemming robot is arranged remotely from the hemming robot, wherein the computing unit is connected to the hemming robot via a communication connection for data transmission. The communication connection can here be a wired or wireless connection, in particular a radio connection, and furthermore, in particular, a connection using infrared, or a WLAN (WLAN: Wireless Local Area Network) connection. In particular, one design variant provides that the hemming robot is connected to the computing unit via the Internet.

[0015] The force distribution of the hemming force for the respective hemming operation can also advantageously be stored in the computing unit. Here, the force distribution, in particular the initial force distribution, is stored in particular by storing the parameters for the first initial hemming operation. In particular, the computing unit is configured here to evaluate whether the initial force distribution conforms to a predeterminable limit value for the hemming force. Furthermore, the hemming robot, in particular the computing unit of the hemming robot, is advantageously configured to adapt the control parameters for performing the hemming operation taking into account the evaluation result, with the result that the limit value is complied with or at least exceeding the limit value does not occur frequently.

[0016] The set point force distribution of the hemming force for a predetermined hemming operation is advantageously stored in the calculation unit. Here, in particular, the stored set point force distribution can be a copy of a previously performed real force distribution, in particular a real force distribution that meets the defined set point specification. Here, the calculation unit is advantageously further configured to detect the actual hemming force distribution of the hemming force for the hemming operation according to the detected sensor signal, and the calculation unit is particularly configured to adapt the hemming force applied by means of one of the at least one hemming rollers for the subsequent hemming operation, in particular by changing the actuation of the hemming robot, and in particular by adapting the hemming path performed by the robot so that the hemming force distribution during the hemming operation corresponds as much as possible to the set point force distribution. Therefore, a high-quality hemming operation can be advantageously ensured. In addition, overloading of the mechanical components, in particular continuous overloading, is prevented by this delayed force control, and an idealized force distribution can be advantageously maintained. In addition, an advantageous real-time reaction of the system does not have to be achieved in normal operation. Furthermore, the computing unit is advantageously configured so that the control parameters for the current actual force distribution corresponding to the set point force distribution within a predetermined tolerance are stored as set point control parameters, in particular as long as the actual force distribution caused by these set point control parameters does not differ inadmissibly from the set point force distribution. Then, new control parameters that again lead to an acceptable actual force distribution are advantageously stored as new set point control parameters. The computing unit is advantageously configured to monitor this and to perform this operation accordingly. The hemming path of the robot is advantageously optimized by bringing the actual force distribution close to the set point force distribution.

[0017] Furthermore, another advantageous improvement provides that the computing unit is configured to detect an overload occurring during a folding operation that is associated with the folding robot, in particular an overload associated with at least one component of the folding robot, and more particularly an overload associated with the folding roller of the folding robot that performs the folding operation, by evaluating sensor signals. Furthermore, in particular, the computing unit is configured to adapt the folding force applied by means of one of the at least one folding rollers for subsequent folding operations in such a way that a continuous overload associated with the folding robot is prevented. Thus, the wear of the components of the folding robot can be advantageously reduced, and thus the service life of the folding robot can be increased.

[0018] According to another advantageous refinement, the hemming robot comprises a communication interface which is advantageously configured to transmit sensor signals detected by at least one sensor element to a remote computing unit via a communication network. Here, the remote computing unit can be a computing unit assigned to the hemming robot. In particular, the remote computing unit can also be another computing unit, however, in particular, remote maintenance functions associated with the hemming robot and furthermore in particular remote maintenance functions associated with the hemming operation performed by the hemming robot can be carried out by this computing unit. In particular, the remote computing unit can be implemented as a cloud application. In particular, the remote computing unit is configured here for maintenance and configuration tasks associated with the hemming robot, wherein the hemming operation can be adapted in particular with the aid of the remote computing unit, in particular with regard to improved hemming results and / or overload protection of components of the hemming robot by preventing the regular recurrence of excessive forces during the execution of the hemming operation.

[0019] Furthermore, the hemming robot is advantageously configured to operate in accordance with a method for operating a hemming robot configured according to the invention.

[0020] Furthermore, the proposed method for modernizing a hemming robot with a robotic hemming head provides for removing a first connecting element and replacing the first connecting element by a second connecting element, the robotic hemming head comprising an attachment element, a first connecting element, a head element and at least one hemming roller, wherein the first connecting element is arranged between the attachment element and the head element and the at least one hemming roller is arranged on the head element, wherein at least one part of the second connecting element is configured as a measuring element, the measuring element being configured to have at least one sensor element, the at least one sensor element being arranged on the measuring element for detecting the force exerted on a hemming flange during a hemming operation by means of one of the at least one hemming rollers. In particular, it is provided here that the hemming robot constructed according to the invention is produced from an "old" hemming robot by modernization. In this regard, the "old" hemming robot can advantageously be further used to a large extent with a then extended range of functions. Since even if the "old" hemming robot comprises a plurality of hemming rollers, only the first connecting element, i.e. the "old" connecting element, has to be replaced by the second connecting element, i.e. the "new" connecting element, the modernization can advantageously be carried out in a relatively simple manner. In particular, in the method for modernizing a hemming robot, a computing unit is also provided, the computing unit being configured to detect sensor signals provided by the at least one sensor element and to process the sensor signals, in particular as described in connection with the refinement of the hemming robot constructed according to the invention. In particular, it is provided that the computing unit is arranged on the attachment element, in particular screwed to the attachment element. According to a design variant, the computing unit is integrated into the attachment element or the connecting element. The computing unit is advantageously connected to a control unit for controlling the hemming robot for data transmission, and the control unit is correspondingly adapted so as to be able to adapt the hemming operation based on the data of the computing unit, in particular so as to approach a setpoint force distribution and / or to avoid a continuous overload of the components of the hemming robot during the execution of the hemming operation.

[0021] A method for operating a hemming robot with a robotic hemming head, also proposed for achieving the object mentioned at the beginning, provides for detecting the elastic deformation of a connecting element during a hemming operation, where the elastic deformation can occur particularly in all three spatial directions, and determining, based on the detected elastic deformation, the hemming force exerted on a hemming flange by a hemming roller of the hemming robot during the hemming operation, in particular the force vector representing the hemming force, where the robotic hemming head includes an attachment element, a connecting element, a head element, and at least one hemming roller, where the connecting element is arranged between the attachment element and the head element, and at least one hemming roller is arranged on the head element. Here, it is advantageous that each hemming roller of the hemming robot does not necessarily have to be assigned a dedicated sensor system. Further advantageously, the hemming operation can be controlled in an improved manner by the determined hemming force, and thus can contribute particularly to quality control. Advantageously, a force vector is determined for the hemming force exerted on the hemming flange, with the result that not only the magnitude of the hemming force is advantageously determined, but also the direction of action of the hemming force.

[0022] According to an advantageous refinement of the method, it can be provided that during the hemming operation, the hemming rollers of the hemming robot move along the component according to predefined waypoints. Here, the hemming force determined during the hemming operation is advantageously assigned to the respective waypoints for determining the hemming force distribution. The values determined for the hemming force are advantageously stored, particularly as value pairs together with the respective waypoints. In particular, each waypoint is assigned a force vector as the hemming force. By evaluating the hemming force distribution determined in this way, faults and / or overloads can be advantageously detected at an early stage.

[0023] An advantageous refinement of the method provides for comparing the determined actual hemming force distribution with a setpoint hemming force distribution predefined for the hemming operation. Further advantageously, the deviation between the determined actual hemming force distribution and the setpoint hemming force distribution for the respective waypoints is determined. Thus, it can be advantageously detected whether the specifications for the hemming operation are met. Further advantageously, the hemming operation can be optimized using the determined deviation such that the deviation tends towards zero, but in particular overloads are avoided, and furthermore, persistent overloads are particularly avoided. The hemming path of the robot is advantageously adapted, particularly adjusted, with the aid of the detected actual hemming force distribution for such an optimization of the hemming operation.

[0024] It can be set particularly advantageously that, for a subsequent hemming operation, the hemming force exerted by the hemming roller on the hemming flange is adapted, in particular by adapting the actuation of the hemming robot, such that the deviation determined with respect to a previously performed hemming operation is reduced. In particular, adapting the actuation of the hemming robot also includes changing the parameters of the robot control, in particular the parameters that cause a change in the hemming path, such as in particular the adaptation of the offset. The delay force regulation advantageously achieved by the corresponding adaptation control of the robot is advantageously achieved by adapting the hemming force exerted on the hemming flange. In particular, the hemming path predetermined for controlling the hemming robot is optimized in this regard by influencing the corresponding regulation of the hemming path and in particular by exchanging regulation data with the computing unit of the hemming robot, in order to adapt the actual force distribution to the setpoint force distribution. Furthermore, in particular, according to a design variant for influencing the hemming path, it is set that at least one parameter, in particular the offset, is changed, and this change of at least one parameter, in particular the offset, is copied to the control of the robot, and thus, in particular, in this design variant, there is no direct exchange between the robot and the force measurement performed by means of the measuring element. The continuous overload of the mechanical components of the hemming robot can be prevented by adapting the force distribution, in particular by bringing the actual force distribution closer to the setpoint force distribution. Furthermore, a high-quality and consistent-quality hemming connection can be achieved. Furthermore, thus, a hemming force distribution adapted to a predetermined idealized setpoint hemming force distribution can be advantageously achieved without the need to provide a regulation system with real-time capabilities for this purpose.

[0025] Force regulation is advantageously achieved by the proposed method such that the hemming force measured first during the hemming operation is stored together with the associated waypoint. After the hemming operation, according to a user instruction, the resulting force distribution is advantageously calibrated using the idealized force curve predetermined for this hemming operation. In a subsequent step, the next hemming operation and the hemming force exerted thereby by the hemming roller are advantageously adapted based on the deviation determined according to the idealized force curve such that the deviation is minimized in the next step. Thus, the adaptation of the hemming operation is advantageously only carried out in a subsequent cycle. In particular, the adaptation of the hemming force exerted by the hemming roller during hemming is carried out by adapting the control parameters, and the actuator of the hemming robot is controlled by the control parameters during hemming.

[0026] It can be set according to another advantageous improvement of the method that, based on the determined hemming force for the hemming operation, in particular by means of the computing unit assigned to the hemming robot, the occurrence of an overload related to the hemming robot is checked. If an overload is detected, the subsequent hemming operation is advantageously adapted, in particular by adapting the control parameters, in order to avoid the overload, and the actuator of the hemming robot is controlled by the said control parameters during hemming. Thereby, the wear of the hemming robot is advantageously reduced, and the service life of the robot is increased.

[0027] Other advantageous details, features and implementation details of the present invention will be explained in more detail in connection with the exemplary embodiments shown in the accompanying drawings (FIGS.: accompanying drawings), in which:

[0028] Figure 1 A schematic diagram showing an exemplary embodiment of a hemming robot constructed according to the present invention is shown;

[0029] Figure 2 A perspective view showing an exemplary embodiment of a robot hemming head of a hemming robot constructed according to the present invention is shown;

[0030] Figure 3 A perspective view showing details of another exemplary embodiment of a robot hemming head of a hemming robot constructed according to the present invention is shown;

[0031] Figures 4a to 4c Each shows a schematic diagram of an exemplary embodiment of the hemming force 5 detected according to the present invention plotted against the stroke s;

[0032] Figure 5 An exemplary embodiment of a method for operating a hemming robot configured according to the present invention is shown based on a block diagram; and

[0033] Figure 6 A perspective view showing an exemplary embodiment of a connecting element of a robot hemming head of a hemming robot constructed according to the present invention is shown.

[0034] In the different drawings, the same parts are generally provided with the same reference numerals, and are therefore sometimes only explained in connection with one of the drawings in each case.

[0035] Figure 1 A schematic diagram showing a hemming robot 4 configured to perform a hemming operation is shown. The robot 4 includes a robot arm 41 having an articulated configuration and a robot hemming head 1 disposed at the end of the robot arm 41. Figure 2 An advantageous embodiment of the robot hemming head 1 is shown. The robot hemming head 1 includes an attachment element 16, a connecting element 11, a head element 13, and a first hemming roller 151, a second hemming roller 152, and a third hemming roller 153, and the first hemming roller 151, the second hemming roller 152, and the third hemming roller 153 are each disposed on the head element 13. The connecting element 11 is disposed between the attachment element 16 and the head element 13. The connecting element 11 is configured as a measuring element, and the measuring element is configured to have at least one sensor element, and at least one sensor element is disposed on the measuring element ( Figure 1(not shown explicitly) for detecting the hemming force applied to the hemming flange by one of the hemming rollers 151, 152, 153 during the hemming operation. Here, the measuring element together with at least one sensor element forms a sensor unit for detecting the hemming force. By means of the hemming rollers 151, 152, 153, the component arrangement structure 2 arranged on the hemming bed 3 can be hemmed according to a predetermined hemming operation. Here, the component device structure 2 includes a first component 21 and a second component 22. The component edge 23 of the first component 21 is folded by means of one of the hemming rollers 151, 152, 153, and the first component 21 and the second component 22 are joined together. Reference will be made to Figure 2 Other details of an advantageous embodiment of the robotic hemming head 1 will be explained.

[0036] As shown by the example in Figure 2 the robotic hemming head 1 includes an attachment element 16, a connecting element 11, a head element 13, and a plurality of hemming rollers 151, 152, 153, wherein the connecting element 11 is arranged between the attachment element 16 and the head element 13, and the hemming rollers 151, 152, 153 are arranged on the head element 13. Here, the hemming rollers 151, 152, 153 have different configurations and are arranged in a star-shaped manner on the head element 13, wherein the hemming robot 4 is configured to perform different hemming operations by means of the hemming rollers 151, 152, 153 with different configurations, in particular hemming operations suitable for different component arrangement structures 2 and different component geometries. A part of the complete intermediate piece of the connecting element 11 forming the connecting element 11 of the robotic hemming head 1 is configured as a measuring element 111, and a plurality of sensor elements 17, in particular a plurality of strain gauges with preferably different orientations, are arranged on the measuring element 111. Here, the measuring element 111 together with the sensor elements 17 forms a sensor unit configured to detect the hemming force applied to the hemming flange by one of the hemming rollers 151, 152, 153 during the hemming operation. As Figure 2 shown in, the measuring element 111 has a columnar configuration in this exemplary embodiment. In addition, the measuring element 111 has an elastically deformable configuration, and the sensor elements 17 attached to the measuring element 111 are configured to detect the elastic deformation of the measuring element 111. In this exemplary embodiment, the measuring element 111 is formed by a recess 1112 and struts 1111 in a frame-like manner and has defined elastic deformation properties, so that the occurring deformations can be advantageously assigned unambiguously to specific hemming forces.

[0037] In this exemplary embodiment, the attachment element 16 of the robotic hemming head 1 is configured as a docking plate through which the robotic hemming head 1 can be arranged on the robotic arm 41, as inFigure 1 shown in the exemplary embodiments in. A computing unit 12 is arranged on the attachment element 16, and the computing unit is configured to detect and process the sensor signals provided by the sensor element 17. Here, in this exemplary embodiment, the computing unit 12 includes a microprocessor unit and a measuring amplifier for processing the (strain) signals recorded at the measuring element 111 (the microprocessor unit and the measuring amplifier are not explicitly shown in Figure 2 . Additionally, the setpoint force distribution of the hemming force for a predetermined hemming operation is stored in the computing unit 12 in each case and is saved in the corresponding memory unit of the microprocessor unit for this purpose. Furthermore, the tolerance lower limit TH1 and the tolerance upper limit TH2 regarding the setpoint force distribution are saved. Additionally, an overload threshold TH3 is stored, and continuous exceeding of this overload threshold TH3 will cause an overload of the hemming robot 4. Here, the computing unit 12 is configured to detect the actual force distribution of the hemming force during the hemming operation based on the detected sensor signals. It is provided here that when performing the hemming operation, where one of the hemming rollers 151, 152, 153 of the robot hemming head 1 moves along the component arrangement structure 2 according to a predetermined waypoint, the hemming force is determined for the corresponding waypoint, and the waypoint and the detected value of the hemming force are saved as a value pair. The actual force distribution then results from these saved value pairs.

[0038] Furthermore, the computing unit 12 is configured to compare the detected actual force distribution with the setpoint force distribution stored in the computing unit 12 and to detect deviations, in particular those below the tolerance lower limit TH1 or exceeding the tolerance upper limit TH2. Taking into account these detected deviations, subsequent hemming operations are adapted by the computing unit 12 such that the subsequently detected actual force distribution is adapted to the setpoint force distribution to a greater extent, in particular such that it does not fall below the tolerance lower limit TH1 and does not exceed the tolerance upper limit TH2. In particular, it is provided here that the computing unit 12 is configured to actuate the corresponding actuators of the hemming robot 4. However, in particular, it can also be provided that the robot 4 is assigned a control unit by which the actuators of the robot 4 and thus the hemming operation are controlled, and the results of the computing unit 12, in particular the detected deviations, are then transmitted to this control unit, with the result that the control unit can control the robot 4 based on the evaluation results of the computing unit 12.

[0039] Figure 3 Another exemplary embodiment is shown, where only a part of the robot hemming head 1 is shown. It is provided here that the hemming force distribution determined by the computing unit 12 based on the strain or elastic deformation 6 of the detected central measuring element 111 is also transmitted to the output device 7 in order to display the actual force distribution of the force 5 acting on the hemming roller 153 during the hemming operation. Here, the force 5 acting during the hemming operation is inFigure 3 is shown as a vector. In this way, it is clear that in this exemplary embodiment, the measuring element 111 that forms the complete intermediate member between the attachment element 16 and the head element 13 is configured to have an associated sensor element 17. The sensor element 17 is used not only to determine the magnitude of the acting force 5, but also to determine the direction of action of the acting force 5. Therefore, the actual force distribution 9 can advantageously be adapted to the predetermined setpoint force distribution in an improved manner. In particular, the quality of the hemming result can thus be improved in an improved manner. In Figure 4a , Figure 4b and Figure 4c examples of the detected actual force distribution 9 are shown.

[0040] Here, Figures 4a to 4c the actual force distribution 9 shown in Figures 4a to 4c follows one after another in time. Here, in each case, for the same hemming roller, the actual force distribution 9 for the hemming operation is shown with the force 5 plotted against the stroke S. In addition, Figures 4a to 4c the setpoint force distribution 8 stored in the computing unit 12, the lower tolerance limit TH1 for the setpoint force distribution 8, the upper tolerance limit TH2 for the setpoint force distribution 8, and the overload threshold TH3 starting with hatched lines are each shown.

[0041] Here, the computing unit 12 is configured to detect whether the actual force distribution 9 exceeds the overload threshold TH3 (not shown in Figures 4a to 4c ). If it is detected in this way that the overload threshold TH3 is exceeded, it is specifically provided that the actuation of the actuator of the hemming robot 4 occurs directly to avoid damage to the components of the hemming robot 4, so that the force is reduced. In particular, a warning message can be additionally output, in particular by means of the output device 7.

[0042] In addition, the computing unit 12 is configured to influence the control parameters for controlling the hemming robot such that the actual force distribution 9 approaches the setpoint force distribution 8 as closely as possible. Here, the computing unit 12 monitors whether the lower tolerance limit TH1 is undershot during the hemming operation, or whether the upper tolerance limit TH2 is exceeded, or whether the overload threshold TH3 is exceeded, and adapts the control parameters accordingly, and thus adapts the actual force distribution 9 for subsequent hemming operations. This is because continuous exceeding of the overload threshold TH3 may lead to mechanical overload of the components of the hemming robot 4 and result in increased energy demand, and continuous undershooting of the lower tolerance limit TH1 and continuous exceeding of the upper tolerance limit TH2 may mean defective production of the hemming flange. By way of example, Figure 4a an undershoot of the lower tolerance limit TH1 between waypoint S1 and waypoint S2 is shown. In addition, Figure 4a multiple exceedances of the upper tolerance limit TH2 at the start of the hemming operation are shown. By corresponding control, for subsequentFigure 4b and Figure 4c In the hemming operation shown in, the actual force distribution 9 is adapted such that in Figure 4b , the actual force distribution 9 exceeds the upper tolerance limit TH2 only twice and does not fall below the lower tolerance limit TH1. By further adaptation in the hemming operation shown in the subsequent Figure 4c , the actual force distribution 9 approaches the setpoint force distribution 8 to the extent that the actual force distribution 9 lies within the tolerance limits TH1, TH2.

[0043] Figure 5 By way of example, a flow chart is used to show how, according to the proposed method, a hemming robot, in particular as referred to in Figure 1 and Figure 2The hemming robot 4 described operates. Here, the hemming robot includes a robotic hemming head, wherein the robotic hemming head has an attachment element, a head element, a connecting element arranged between the attachment element and the head element, and folding rollers arranged on the head element. Here, the hemming robot is assigned a computing unit and a control unit, wherein the computing unit and the control unit can form a common unit. The hemming robot together with the computing unit and the control unit forms a robotic system. In a first step A, a hemming path is specified for the hemming operation along which the hemming robot should move together with the hemming rollers in order to engage an initial hemming path of the component arrangement structure. Here, the hemming path specifies the distance of the hemming rollers of the hemming robot along the hemming flange to be produced and the hemming force applied. In this exemplary embodiment, the initial hemming path results in a first actual hemming force distribution. In step C, the hemming operation is then started by the hemming robot. During the hemming operation, in method step D, the elastic deformation of the connecting element of the robotic hemming head is detected. The hemming force applied to the hemming flange by the hemming rollers of the hemming robot during the hemming operation is determined by the detected elastic deformation and recorded. For this purpose, in particular, the hemming rollers are moved along the component arrangement structure according to predetermined waypoints specifying the hemming path, wherein the determined hemming forces are assigned to the corresponding waypoints for determining the actual hemming force distribution. The hemming operation ends in step E. In step F, an evaluation of the recorded hemming forces takes place. Here, in particular, the determined actual hemming force distribution is compared with a setpoint hemming force distribution predetermined for the hemming operation. Here, within the scope of the evaluation, the deviation between the determined actual hemming force distribution and the setpoint hemming force distribution is determined for the respective waypoints, wherein, in particular, it is checked by threshold comparison whether the deviation is within the specified tolerance. Taking into account the determined deviation, in step G, the control parameters are adapted and thus the specified hemming path is adapted in order to reduce the deviation determined for subsequent hemming operations and in particular to avoid continuous overloading of the components of the hemming robot. Thus, in step G, in particular, a robotic path correction is defined. In step H, the hemming path adapted in this way is specified as a new specification for the hemming path. Thus, this new hemming path replaces the initial hemming path specified in step A. In a subsequent method step C, a new hemming operation is carried out according to the newly specified hemming path. The other steps D to H follow accordingly. It goes without saying here that it can be provided that the determined deviation is very small or within a defined tolerance range, such that the hemming path is not adapted, but only adapted when the deviation is outside the tolerance range. In an additional optional method step, the occurrence of an overload related to the hemming robot is checked based on the determined hemming forces for the performed hemming operation, and the hemming path is adapted to avoid the overload, and preferably a warning is output in the case of detected overload, and in the case of detected overload, there is also a deviation outside the tolerance range.

[0044] Figure 6 An exemplary embodiment of a connecting element 11 of a robotic hemming head 1 for a hemming robot 4 is shown, wherein a part of the connecting element 11 is configured as a measuring element 111 in a frame structure having a strut 1111. The measuring element 111 is in each case adjacent to a first connecting part 112 and a second connecting part 113, wherein the connecting element 11 can be attached to an attachment element 16 of the robotic hemming head 1 via the first connecting element 112 and can be attached to a head element 13 of the robotic hemming head 1 via the second connecting element 113. If, in the case of a hemming robot, a conventional connecting element is exchanged for this connecting element 11, the modernization of the hemming robot advantageously takes place by means of the corresponding possibility of hemming force measurement. The corresponding computing unit is likewise arranged and correspondingly connected within the scope of the modernization. In particular, a signal processing unit with a communication interface can also be provided, wherein sensor signals detected by at least one sensor element 17 arranged on the measuring element 111 can then be transmitted, for example, via a mobile radio module to a remote computing unit, wherein the sensor signals can be evaluated, for example, for a remote maintenance function.

[0045] The exemplary embodiments shown in the drawings and explained in connection with the drawings are used to explain the invention and not to limit the invention.

[0046] List of reference numerals

[0047] 1 Robotic hemming head

[0048] 11 Connecting element

[0049] 111 Measuring element

[0050] 1111 Strut of the measuring element (111)

[0051] 1112 Recess of the measuring element (111)

[0052] 112 First connecting part

[0053] 113 Second connecting part

[0054] 12 Computing unit

[0055] 13 Head element

[0056] 151 Hemming roller

[0057] 152 Hemming roller

[0058] 153 Hemming roller

[0059] 16 Attachment element

[0060] 17 Sensor element

[0061] 2 Component Arrangement Structure

[0062] 21 First Component

[0063] 22 Second Component

[0064] 23 Component Edge

[0065] 3 Flanging Bed

[0066] 4 Flanging Robot

[0067] 41 Robot Arm

[0068] 5 Flanging Force

[0069] 6 Elastic Deformation

[0070] 7 Output Device, Especially Image Display Device

[0071] 8 Setpoint Force Distribution

[0072] 9 Actual Force Distribution

[0073] TH1 Lower Tolerance Limit

[0074] TH2 Upper Tolerance Limit

[0075] TH3 Overload Threshold

[0076] S1 First Waypoint in Flanging Operation

[0077] S2 Second Waypoint in Flanging Operation

[0078] A Initial Flanging Path

[0079] C Start Flanging Process

[0080] D Record Flanging Force

[0081] E End Flanging Process

[0082] F Evaluate Flanging Force

[0083] G Adapt Flanging Path, Especially by Defining Robot Path Correction to Adapt Flanging Path

[0084] H Designate the Adapted Flanging Path as the New Predetermined Flanging Path

Claims

1. A hemming robot (4), the hemming robot (4) being configured to perform a hemming operation, the hemming robot (4) having a robotic hemming head (1), the robotic hemming head (1) including an attachment element (16), a connecting element (11), a head element (13), and at least one hemming roller (151, 152, 153), wherein, The connecting element (11) is arranged between the attachment element (16) and the head element (13), and the at least one flanging roller (151, 152, 153) is arranged on the head element (13), characterized in that at least one part of the connecting element (11) is constructed as a measuring element (111), wherein the measuring element (111) is constructed to have at least one sensor element (17), and the at least one sensor element (17) is arranged on the measuring element (111) for detecting the flanging force (5) applied to the flanging flange by means of one of the at least one flanging rollers (151, 152, 153) during the flanging operation.

2. The hemming robot (4) according to claim 1, characterized in that, The intermediate piece of the connecting element (11) or the complete connecting element (11) is designed as the measuring element (11).

3. The hemming robot (4) according to claim 1 or claim 2, characterized in that, The measuring element (111) has a design that allows elastic deformation in all three spatial directions, wherein the at least one sensor element (17) is designed to detect the elastic deformation of the measuring element (111).

4. The hemming robot (4) according to one of the preceding claims, characterized in that, The measuring element (111) has a cylindrical configuration.

5. The hemming robot (4) according to one of the preceding claims, characterized in that, The measuring element (111) is formed by struts (1111) connected to one another.

6. The hemming robot (4) according to one of the preceding claims, characterized in that, The connecting element (11) has a first connecting portion (112) and a second connecting portion (113), wherein the connecting element (11) is connected to the attachment element (16) via the first connecting portion (112) and to the head element (13) via the second connecting portion (113).

7. The hemming robot (4) according to one of the preceding claims, characterized in that, The hemming robot (4) is assigned a computing unit (12), wherein the computing unit (12) is configured to detect and process sensor signals provided by the at least one sensor element (17).

8. The hemming robot (4) according to claim 7, characterized in that, A set point force distribution (8) of a hemming force (5) for a predetermined hemming operation is stored in the computing unit (12), and the computing unit (12) is further configured to: detect an actual force distribution (9) of the hemming force (5) for the hemming operation based on the detected sensor signal, and adapt the hemming force (5) applied by means of at least one of the hemming rollers (151, 152, 153) for a subsequent hemming operation by changing the actuation mode of the hemming robot (4) so ​​that the force distribution of the subsequent hemming operation during the hemming operation corresponds as closely as possible to the set point force distribution (8).

9. The hemming robot according to claim 7 or claim 8, characterized in that, The computing unit is also configured to detect an overload associated with the hemming robot occurring during a hemming operation by evaluating the sensor signal, and to adapt the hemming force (5) applied by means of one of the at least one hemming rollers (151, 152, 153) for a subsequent hemming operation so as to prevent a continuous overload associated with the hemming robot.

10. The hemming robot (4) according to one of the preceding claims, characterized in that, A communication interface is configured to transmit a sensor signal detected by the at least one sensor element (17) to a remote computing unit via a communication network.

11. The hemming robot (4) according to one of the preceding claims, characterized in that, A plurality of hemming rollers (151, 152, 153) with different configurations arranged on the head element (13), wherein the hemming robot (4) is configured to perform different hemming operations by means of the hemming rollers (151, 152, 153) with different configurations.

12. The hemming robot (4) according to one of the preceding claims, characterized in that, The hemming robot (4) is configured to operate according to the method according to one of claims 15 to 20.

13. A method for modernizing a hemming robot (4), the hemming robot (4) having a robotic hemming head (1), the robotic hemming head (1) including an attachment element (16), a first connecting element, a head element (13), and at least one hemming roller (151, 152, 153), wherein, The first connecting element is arranged between the attachment element (16) and the head element (13), and the at least one hemming roller (151, 152, 153) is arranged on the head element (13), characterized in that the first connecting element is removed and replaced by a second connecting element (11), wherein at least one part of the second connecting element (11) is configured as a measuring element (111), and the measuring element (111) is configured to have at least one sensor element (17), and the at least one sensor element (17) is arranged on the measuring element (111) for detecting the hemming force (5) applied to the hemming flange by means of one of the at least one hemming roller (151, 152, 153) during the hemming operation.

14. The method according to claim 12, characterized in that, The hemming robot (4) according to one of claims 1 to 12 is produced in a modern way.

15. A method for operating a hemming robot (4), the hemming robot (4) having a robotic hemming head (1), the hemming robot (4) being in particular a hemming robot according to one of claims 1 to 11, wherein, The robotic hemming head (1) includes an attachment element (16), a connecting element (11), a head element (13) and at least one hemming roller (151, 152, 153), wherein the connecting element (11) is arranged between the attachment element (16) and the head element (13), and the at least one hemming roller (151, 152, 153) is arranged on the head element (13), characterized in that the elastic deformation of the connecting element (11) during the hemming operation is detected, and the hemming force (5) applied to the hemming flange by means of the hemming rollers (151, 152, 153) of the hemming robot (4) during the hemming operation is determined according to the detected elastic deformation.

16. The method according to claim 15, characterized in that, During the hemming operation, the hemming rollers (151, 152, 153) of the hemming robot (4) move along the component (2) according to a predetermined waypoint, and the determined hemming force (5) is assigned to the corresponding waypoint for determining the actual hemming force distribution (9).

17. The method according to claim 16, characterized in that, The determined actual hemming force distribution (9) is compared with the setpoint hemming force distribution (8) predetermined for the hemming operation, and the deviation between the determined actual hemming force distribution (9) and the setpoint hemming force distribution (8) for the corresponding waypoint is determined.

18. The method according to claim 17, characterized in that, For a subsequent hemming operation, the hemming force (5) applied by the hemming roller to the hemming flange is adapted so that the deviation determined with respect to the previously performed hemming operation is reduced.

19. The method according to claim 18, characterized in that, In order to adapt the applied hemming force, the predetermined movement path of the robot for the hemming robot (4) is changed.

20. The method according to one of claims 15 to 19, characterized in that, For the hemming operation to be performed, the determined hemming force is used to check for the occurrence of an overload associated with the hemming robot (4), and in the event of an overload being detected, subsequent hemming operations are adapted to avoid the overload.

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