Bending system having bending head unit and robot unit

Abstract

The invention relates to a bending system for producing a bent part from an elongate workpiece (W), comprising a bending head unit having at least one controllable bending tool for producing at least one bend in the workpiece, and a robot unit for handling the workpiece before, during and after the production of bends. The robot unit comprises a base, an end effector (100) which can be positioned in space with multi-axial control relative to the base and which, in the installed state, can be rotated about an effector axis (110), and a gripping system (120) for gripping the workpiece before, during and after the production of bends. The gripping system (120) has two sub-units. A first sub-unit is in the form of a clamping unit (130) and has two clamping jaws (135) which delimit a clamping-jaw grasping region between inner sides facing one another and which can be moved in opposite directions between an open configuration and a clamping configuration by means of a drive system. The gripping system also has a second sub-unit which is in the form of a workpiece-catching unit and which comprises at least two catching arms (155) which can be moved relative to the clamping jaws by means of a drive system such that a portion of the workpiece which is positioned at least partially outside the clamping-jaw grasping region within a catching region of the catching arms can be gripped by the catching arms (115) and can be moved, by controlled movement of the catching arms relative to the clamping jaws, into a target position (SP) lying within the clamping-jaw grasping region.

Description

[0001] Bending system with bending head unit and robot unit

[0002] FIELD OF APPLICATION AND STATE OF THE ART

[0003] The invention relates to a bending system for producing a bent part from an elongated workpiece. Furthermore, the invention relates to a method for producing a bent part from an elongated workpiece using such a bending system and to an end effector for use in such a bending system.

[0004] The workpiece can be solid or tubular and have different cross-sectional shapes, e.g. a round or oval or polygonal cross-sectional shape, such as a rectangular cross-sectional shape.

[0005] The focus here is on the processing of relatively long and slender, initially more or less straight workpieces, which are kept in a length suitable for their later use and are to be formed with the help of suitable bending operations into a bent part with possibly complex bending geometry with several bends, possibly in different bending planes.

[0006] Numerically controlled bending systems have proven effective for bending such long workpieces. These systems comprise a bending head unit with at least one numerically controllable bending tool for generating at least one bend on the workpiece, as well as a controllable robot unit for handling or manipulating the workpiece to be bent before, during and after generating bends.

[0007] Document DE 102018 108 862 A1 discloses a bending device for bending a rod- or tubular workpiece, comprising a bending machine and a robot. The bending machine has a bending head configured to bend the workpiece in at least one forming operation, wherein the bending machine further comprises a control device that controls the operation of the bending machine. The robot has a motor-adjustable multi-joint arm with a gripping end configured to grip and hold the workpiece. The robot has a control unit configured to control the operation of the robot. At the beginning of a bending process comprising at least one forming operation, the robot inserts the workpiece into the bending head. During the at least one forming operation, the robot stabilizes the workpiece. After the at least one forming operation, and thus at the end of the bending process, it removes it from the bending head.The robot's control unit is switched to slave mode, at least during the bending process, in which it receives control commands from the bending machine's control unit. This allows the working movements of the bending machine and the robot to be particularly well synchronized.

[0008] The document DE 10 2018 108 863 A1 describes a bending device with at least one bending device and a multi-joint robot with a robot arm, at the end of which a rotating tong is provided, with which a workpiece can be clamped, fed to the bending device, rotated and tracked along the bending device during bending.

[0009] A particularly prominent example of relatively long, slender workpieces at the moment are so-called "busbars". These are insulated and bent copper or aluminum bars that can be used in vehicles with fully or partially electric drive, for example, to transport electrical energy between individual battery modules. Furthermore, the cable harnesses running lengthwise between the front and rear of vehicles are increasingly being replaced by busbars. Due to the ever-increasing currents, busbars with a correspondingly large current-carrying cross-section are required. Since the installation spaces available for busbars are sometimes relatively tight and geometrically complex, busbars with bends at one or more points are often required.

[0010] When machining long busbars or other similarly long, narrow workpieces, a defined bending sequence must generally be ensured. Long busbars are among the workpieces that are particularly susceptible to deflection during handling. Such deflections due to the effects of gravity and / or acceleration forces during workpiece movement can lead to plastic deformation, which can cause errors in the bending geometry of the finished bent part. Deflection of the workpiece and workpiece vibrations can also impair the gripping of a workpiece section that is to be clamped.

[0011] TASK AND SOLUTION

[0012] Against this background, the present invention is based on the object of providing a bending system of the type mentioned in the introduction, comprising a bending head unit and a robot unit, which, among other things, operates quickly and reliably when bending relatively long, unstable workpieces and reduces or avoids problems caused by vibrations and deflections of the workpiece to be bent during a bending process. A further object is to provide an advantageous method for producing a bent part from an elongated workpiece using such a bending system, as well as to provide an end effector that can be used on a robot unit of such a bending system.

[0013] To achieve this object, the invention provides a bending system having the features of claim 1, a method having the features of claim 13, and an end effector having the features of claim 16. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated into the description by reference.

[0014] According to one aspect of the claimed invention, a bending system for producing a bent part from an elongated workpiece is provided, comprising a bending head unit with at least one controllable bending tool for producing at least one bend on the workpiece and a robot unit for handling or manipulating the workpiece before, during and after the production of bends.

[0015] In its fully assembled state, the robot unit comprises a base and an end effector which is kinematically coupled to the base, can be positioned in space relative to the base in a multi-axis controlled manner, is rotatable about an effector axis and has a gripping system for gripping the workpiece before, during and after the creation of bends.

[0016] The gripping system comprises two controllable sub-units. A first sub-unit is designed as a clamping unit and has two clamping jaws that define a gripping area between mutually facing inner sides and can be moved in opposite directions between an open configuration and a clamping configuration by means of a drive system.

[0017] A second sub-unit is designed as a workpiece catching unit and has at least two gripping arms which can be moved by means of a drive system relative to the clamping jaws into different working configurations such that a section of the workpiece positioned at least partially outside the clamping jaw detection area within a detection area of ​​the gripping arms can be gripped by the gripping arms and moved by controlled movement of the gripping arms relative to the clamping jaws into a desired position lying within the clamping jaw detection area.Such a gripping system provides several coordinated functionalities that, among other things, make it possible to grasp and securely clamp workpiece sections that, due to deflections and / or vibrations, are temporarily or permanently not in the position in space that would be expected for a rigid workpiece and that could easily be taken into account by the motion control of the robot unit.

[0018] To perform a bending operation, the clamping unit must hold the workpiece at a fixed spatial position with a predefined orientation during every phase of the bending operation. This position, in conjunction with the bending unit, enables the corresponding bending operation on the workpiece. However, due to vibrations and / or deflections, the workpiece to be gripped may not be in the spatial position that would allow direct gripping by the clamping unit. The resulting problems can be avoided with the help of the second sub-unit, designed as a workpiece gripping unit.The workpiece catching unit offers a catching area that is significantly larger than the clamping jaw gripping area of ​​the clamping unit, so that the workpiece catching unit can also grip workpiece sections that are not or not completely within the clamping jaw gripping area when the end effector has been moved to the position in space intended for gripping the workpiece.

[0019] By moving the gripping arms relative to the clamping jaws, a section of the workpiece positioned within their gripping range can be grasped and moved to the target position within the clamping jaws' grasping range. The target position is the spatial position that the section of the workpiece to be clamped for the next machining operation would ideally occupy, and which is known to the robot unit's controller.

[0020] According to a further development, the gripping system has two independently controllable sub-units, wherein the first sub-unit has two clamping jaws that are movable by means of a first drive system, and the second sub-unit has at least two gripping arms that are movable relative to the clamping jaws by means of a second drive system that is controllable independently of the first drive system. If the clamping jaws and the gripping arms can be actuated independently of one another by means of separate drive systems, this results in particularly great flexibility for adapting the kinematics of the gripping processes to the respective gripping situation. However, it is not always necessary to be able to actuate the clamping jaws and the gripping arms independently of one another. There are also embodiments in which the movable components of both sub-units can be controlled by means of a single drive.In the variant with only one drive, the two subunits can be kinematically coupled, for example, in such a way that a movement of a gripping arm causes a subsequent movement of a clamping jaw via a suitable mechanical coupling mechanism, or vice versa. Such embodiments can be sufficient, for example, if the end effector repeatedly encounters the same repetitive situation when handling workpieces. Variants with only a single drive for the clamping jaws and gripping arms are generally lighter and more cost-effective to manufacture than variants with multiple drives, which can be used more flexibly.

[0021] According to a further development, the gripping arms are movable between an open gripping configuration, a closed positioning configuration, and a closed holding configuration. The second drive system is preferably provided for this purpose.

[0022] According to this development, the gripping arms can thus be moved in a coordinated manner between at least three different working configurations, e.g. with the aid of the second drive system. In the gripping configuration, the gripping arms are open such that a section of the workpiece positioned within a gripping area of ​​the workpiece gripping unit can be caught or grasped, even if the workpiece section is located completely or partially outside the gripping area of ​​the clamping jaws. A subsequent phase of the working movement transfers the gripping arms from the open gripping configuration to a positioning configuration which is characterized, among other things, by the fact that the gripping arms are now closed such that the gripped workpiece section is caught by the gripping arms and secured against falling out.In a subsequent phase of the working movement, the already closed gripping arms are moved into a likewise closed holding configuration, in which the captured workpiece section reaches its target position in the clamping jaw gripping area and can be held in the target position without clamping.

[0023] For the partial functionality of positioning the workpiece section at the target position, the gripping arms are in a closed positioning configuration, in which the workpiece section to be gripped can be moved towards the target position by coordinated movement of the gripping arms without losing its grip. The movement of the positioning operation ends when the gripping arms are in their holding configuration. The workpiece section caught and possibly positioned by the gripping arms is then in its target position within the clamping jaw detection range of the clamping unit, so that the clamping unit can now be transferred from the open configuration to the clamping configuration in order to fix the workpiece in the spatial position known to the control system of the robot unit by clamping.

[0024] When the gripping arms are in the holding configuration, the workpiece section to be clamped is located at the intended position in space. However, it is not clamped by the gripping arms and thus held in place by force, but can be moved longitudinally relative to the gripping arms. In the holding configuration, the gripping arms also serve as a guide for the workpiece, allowing for any compensating movements along the longitudinal direction of the workpiece section. These movements are only prevented when the clamping unit is in the clamping configuration.

[0025] The term "robot unit" here generally refers to a universal, programmable machine that generally comprises a manipulator, a controller, and an end effector, which in the case of the bending system has the gripping system. The robot unit can, for example, be equipped in the manner of an articulated-arm robot with serial kinematics. For example, the robot unit can have six axes of rotation, so that the end effector or gripping system can be aligned in any direction relative to the base at any point in space within the working area of ​​the robot unit. Conventional industrial robots with six electromechanically driven axes of rotation can be used, for example. A robot unit can also have one or more linear axes. These can, for example, be aligned orthogonally to one another, although other configurations are also possible.

[0026] The clamping jaws have clamping surfaces on their inner sides facing the workpiece, which are adapted to the outer contour of the workpiece to be bent. In the case of busbars made of flat material, the clamping surfaces are essentially flat and aligned relative to each other in such a way that, in the closed clamping configuration, they are oriented essentially parallel to each other and enclose the flat material between them.

[0027] The gripping arms, on the other hand, have a shape that, among other things, enables the secure capture of a workpiece section located in space. According to a further development, the gripping arms have free end sections designed like angled hooks with inward-facing retaining projections or retaining lugs. The inner sides of the gripping arms are the sides facing the workpiece during capture, positioning, and holding. In a closed configuration of the gripping arms, the retaining projections ensure that the captured workpiece section can be held by the gripping arms through a positive fit, without slipping out again.

[0028] The end effector is preferably designed as a replaceable assembly with which a conventional robot unit can be equipped to create a robot unit according to the claimed invention. According to a further development, the end effector has a base support with mounting structures for mounting on a mounting side of a member of the robot unit that can rotate about a rotation axis. These are designed such that, in the assembled state, the end effector can be rotated preferably indefinitely by rotating the member about the effector axis. The effector axis is thus the intended rotation axis of the end effector.

[0029] Some properties of the gripping system can be conveniently characterized with reference to a gripping system-specific reference system. The gripping system defines a main plane, a center plane oriented perpendicular to the main plane, and a gripping system axis. The gripping system axis lies in the main plane and the center plane, thus corresponding to the intersection of these planes. The center plane contains the gripping center or gripping center of the gripping unit. The design is such that working movements of the clamping jaws and gripping arms run parallel to the main plane and opposite to the center plane. Thus, all gripping elements execute planar movements.

[0030] Preferably, the clamping jaws are pivotable about first pivot axes oriented perpendicular to the main plane, while the gripping arms are pivotable about second pivot axes oriented perpendicular to the main plane, with the second pivot axes additionally being displaceable parallel to the gripping system axis. This offers the advantage, among other things, that in the open configuration, an outwardly opening clamping jaw gripping area and an outwardly opening gripping area of ​​the gripping arms are created, which facilitates gripping moving workpiece sections.

[0031] Alternatively, the clamping jaws and / or the gripping arms could also work like a parallel gripper, i.e. they could perform linear movements perpendicular to the center plane when opening and closing.

[0032] While in preferred embodiments, the working movements of the clamping jaws exclusively involve pivoting movements around the corresponding first pivot axes, the working movements of the gripping arms are a combination of pivoting movements (when opening and closing the gripping arms) and axial movements parallel to the gripping system axis (for retracting the gripped workpiece toward the target position). These complex working movements of the gripping arms are realized in preferred embodiments by providing a link guide for guiding the working movements of each of the gripping arms.

[0033] This can be designed such that for each gripping arm, a support-mounted guide element with a guideway is arranged. The guideway has an axial guide section parallel to the gripping system axis, which transitions towards a front end of the end effector into a front end section pointing diagonally outwards. Attached to the gripping arms is a rear guide element guided in the axial guide section of the guideway, and at a distance therefrom, a front guide element is attached, which can engage in the axial guide section or the front end section depending on the axial position of the gripping arm. The guideway and the sliding blocks thus together form a sliding joint in which the complex working movement of the gripping arm can be predetermined by the curved shape of the guideway.

[0034] It is possible for the gripping system axis to coincide with the effector axis (coaxial arrangement). Some embodiments, however, are characterized by the gripping system axis being aligned obliquely to the effector axis, with the angle between the gripping system axis and the effector axis preferably being in the range of 10° to 45°. It has been shown that this angled arrangement enables faster gripping and re-gripping operations in most bending processes than the aforementioned coaxial arrangement.

[0035] According to a further development, the second drive system for each gripping arm has a drive unit that acts by varying its length, which is connected directly or indirectly to the base support at one end and to the gripping arm at the opposite end. This drive design allows both the generation of working movements parallel to the gripping system axis and the pivoting movements when opening and closing the gripping arms. The drive unit can be, for example, a pneumatically or hydraulically operated cylinder-piston drive unit, or, if necessary, an electric cylinder or a length-adjustable drive unit with a linear motor. There are various options for the relative arrangement of the clamping jaws and gripping arms.A particularly reliable and compact design is characterized by the fact that the clamping jaw engagement area extends parallel to the center plane on both sides of the main plane from a first end to a second end over an engagement length, and the gripping arms are arranged between the first and second ends at a distance from them within the clamping jaw engagement area. The clamping jaws can have corresponding recesses within which the gripping arms can move.

[0036] The invention also relates to an end effector for use on a robot unit of a bending system for producing a bent part from an elongated workpiece, wherein the bending system comprises a bending head unit with at least one controllable bending tool for creating at least one bend on the workpiece, as well as the robot unit for handling the workpiece before, during, and after creating the bends. Useful technical features are explained in the preceding and following text.

[0037] Furthermore, the invention relates to a method for producing a bent part from an elongated workpiece using a bending system comprising a bending head unit with at least one controllable bending tool for creating at least one bend on the workpiece and a robot unit for handling the workpiece before, during, and after creating bends. The bending system is designed according to the claimed invention.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Further advantages and aspects of the invention emerge from the claims and from the description of embodiments of the invention, which are explained below with reference to the figures.

[0040] Fig. 1 shows a view of a bending system equipped with an articulated arm robot and a multi-axis bending head unit according to an embodiment;

[0041] Fig. 2 shows a view of an end effector according to an embodiment;

[0042] Figs. 3 to 6 show various successive phases of working movements of the gripping arms and the clamping jaws when gripping and clamping a workpiece; Figs. 7 and 8 show successive phases of working movements of the gripping arms and the clamping jaws in an end effector with a single drive.

[0043] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The schematic Fig. 1 shows a view of an embodiment of a bending system 200 designed to produce a bent part from an elongated workpiece W of a predetermined length. In the example, the bending system is configured to produce two-dimensionally or three-dimensionally bent busbars, such as those required, among other things, in the automotive industry for transporting electrical energy between vehicle assemblies or within battery groups.

[0045] The starting material or workpiece W in this case is an insulated flat material, which essentially consists of an electrically conductive, metallic carrier material, an adhesion promoter on the surface of the carrier material, and an electrically insulating insulation layer on the adhesion promoter. The carrier material usually has a flat rectangular cross-section with broad sides and perpendicular narrow sides. The insulation layer completely encloses the carrier material. The insulation layer is often made of certain polyamide plastics. The carrier material is usually made of copper (Cu) or aluminum (Al) or of Cu- or Al-based alloys and is responsible for conducting the current.

[0046] The workpieces to be processed are nominally straight and cut to a specified length. This can be on the order of one meter or several meters. The width of the flat material (measured in the width direction B perpendicular to the longitudinal direction L) can be several times the thickness (measured along the narrow sides), for example, three to seven times. Widths can be on the order of a few millimeters, e.g., in the range from 20 mm to 60 mm. The insulation layer is typically less than 1 mm thick.

[0047] The bending system 200 comprises a bending head unit 210 having a plurality of bending tools 215, whose working movements can be controlled via control signals from a control unit in order to create one or more bends on the workpiece W by cold forming. The bending head unit is an independently controllable forming device with multiple machine axes. The bending system 200 further comprises a robot unit 220 for handling (manipulating) the workpiece W before, during, and after the creation of bends.

[0048] The bending head unit 210 has a bending head with two rotary draw bending devices (one for left-hand bending and one for right-hand bending) with corresponding rotary bending tools 215, the components of which can be pivoted relative to one another about a horizontal axis of rotation. The tool-carrying bending head can be rotated about a horizontal axis of rotation 212 to change the bending direction. EP 1 350 577 A1 describes the movement sequence for right-left bending of pipes using a similarly constructed bending head unit. The rotatable bending head can also be attached to a pivot support to enable the bending head to be moved to the height of the workpiece. This pivot joint is omitted here, since the robot unit 220 can freely position the workpiece W.The bending form of each rotary draw bending machine is designed so that the workpiece can be bent along the short side (large bending radius) and along the long side (small bending radius). The interaction of the multi-axis robot and the bending head is controlled to ensure the positioning of the busbar relative to the bending form as quickly as possible.

[0049] If the workpiece is held by the robot unit 220 such that a portion of the workpiece is located within the engagement area of ​​a bending tool 215, the bending head unit 210 can perform a bending forming process on the workpiece. The workpiece can be held by the robot unit 220 at a distance from the bending head unit; if necessary, the robot unit can perform coordinated working movements with the working movements of the bending head unit, for example, to guide the workpiece.

[0050] The starting workpieces to be formed into busbars, in the form of straight pieces of flat material, are initially stored in a material supply. One task of the robot unit 220 is to pick up one workpiece at a time from the material supply, feed the workpiece to the bending head unit 210 such that a section of the workpiece to be bent lies within the engagement area of ​​a bending tool of the bending head unit, perform its own working movements during a bending process if necessary, and place the finished bent part on a support after all bending operations have been completed.

[0051] The robot unit 220 and the bending head unit 210 are mounted on a common base plate 213 with a fixed spatial relationship to each other. The robot unit is designed as an articulated-arm robot with six axes of rotation and is therefore capable of moving a gripper system 120 attached to the free end of the robot unit to any spatial position within the robot unit's working area, where it can be positioned and moved with any orientation of the gripper system.

[0052] The robot unit 220 comprises a base 222 mounted on the base plate 213 and supporting a multi-jointed robot arm. At the free end of the robot unit is an end effector 100, which is serially kinematically coupled to the base 222 via the links of the articulated arm and can be positioned in space relative to the base with multi-axis control. The link G6 of the robot arm closest to the end effector is infinitely rotatable about a sixth rotation axis A6.

[0053] The electromechanical drives for generating the rotational or pivoting movements around the six rotational axes of robot unit 220 are controlled by a central controller of the robot unit. Since industrial robots with six electromechanically driven rotational axes are known per se, further description will be omitted here.

[0054] The end effector 100 is mounted on the last (sixth) link G6 of the robot arm such that its effector axis EA is coaxial with the rotation axis A6 of the adjacent sixth link, so that the end effector is rotatable about the effector axis EA.

[0055] Details of the end effector 100 can be clearly seen in Fig. 2, among others. The end effector 100 has a multi-part base support 110, which comprises a flange-like mounting flange 111 with mounting structures for screwing the end effector to the adjacent link of the robot arm, as well as an approximately cuboid-shaped support block 112 carried by the mounting flange. The support block is inclined with respect to the mounting surface 113 (oriented perpendicular to the effector axis) so that the mutually parallel longitudinal edges of the support block are oriented at an acute angle Wl (here, for example, approximately 20° to 40°) obliquely to the effector axis EA.

[0056] The structure and operation of the end effector 100 and the gripping system 120 attached to it are explained below with reference to a reference system specific to the gripping system. The working movements described later when opening and closing subunits of the gripping system 120 run parallel to a main plane HE. A center plane ME leading through the gripping center of the gripping system is perpendicular to the main plane HE and intersects it along a line of intersection corresponding to the gripping system axis GA. The side axially opposite the mounting flange 111 is the front of the end effector; at the rear is the mounting surface 113 or, in the mounted state, the adjacent rotatable member G6 of the robot arm.

[0057] The gripping system 120 comprises two sub-units that can be controlled independently of each other and perform different tasks related to the manipulation of the workpiece.

[0058] A first sub-unit is designed as a clamping unit 130. This has two clamping jaws 135, which can be pivoted symmetrically to the center plane ME in opposite directions and define a clamping jaw engagement area 136 between the mutually facing inner sides of the clamping jaws. This is the space enclosed between the inner sides, which extends to the front ends of the clamping jaws. The areas of the inner sides of the clamping jaws intended for workpiece contact are flat in accordance with the cross-sectional shape of the workpiece (flat material). In an open configuration of the clamping jaws (cf. Fig. 3), the clamping jaw engagement area 136 is essentially V-shaped in cross-section and opens towards the front of the end effector 100. In the closed clamping configuration (cf. Fig.6) the inner sides run parallel to each other with a mutual distance from each other, lie on the broad sides of the flat material and clamp the workpiece W between them. The contact pressure caused by the clamping forces ensures a force-locking blocking of movements of the workpiece relative to the clamping unit.

[0059] The clamping jaws 135 are relatively long in the direction perpendicular to the main plane HE, so that the engagement length EL measured perpendicular to the main plane HE between the ends of the clamping jaws 135 is greater than the width of the broad sides of the flat material, for example, approximately twice as large. Due to the relatively large engagement length during clamping engagement, the flat material can be held securely in place even with moderate clamping forces.

[0060] For opening and closing the clamping jaws 135, the end effector 100 comprises a first drive system (not shown in detail). This system operates hydraulically and comprises a piston element which can be displaced (axially) within a cylinder bore formed inside the carrier block 112, parallel to the gripping system axis GA, against the force of a return spring in the direction of the front end of the end effector. The piston element acts on transmission levers which are mounted on the base support so as to be pivotable about first pivot axes oriented perpendicular to the main plane HE and which transmit the force of the piston to the clamping jaws 135 with an increase by a transmission ratio. These are mounted on the base support 110 so as to be pivotable about first pivot axes S1 oriented perpendicular to the main plane.

[0061] The position and orientation of the clamping jaws 135 in space and in relation to the coordinate system of the bending head unit 210 can be precisely specified via the control of the robot unit 220. However, such precisely predictable engagement conditions are generally not present, or not permanently, when processing long workpieces made of flat material, among other things. It has been shown that long busbars are susceptible to deflection during handling, which, in the worst case, can lead to plastic deformation. The flat material is also prone to vibrations during movement or after completion of a movement, which, depending on the extent of the vibrations, can make direct gripping by the clamping jaws difficult or even impossible, so that undesirable collisions between the workpiece and the tool can occur.

[0062] The gripping system 120 of the end effector 100 is designed, among other things, with such problems in mind, so that elongated workpiece material can be gripped quickly and yet gently with the required positional accuracy by the gripping system, despite possible vibrations and deflections, so that bent parts with a precisely predeterminable bending geometry can be produced.

[0063] For this purpose, in addition to the components of the first subunit (clamping unit 130), the gripping system comprises separate components of a second subunit, which is referred to in this application as a workpiece catching unit 150. The workpiece catching unit has a catching area 156 that is significantly larger than the clamping jaw gripping area 136 defined by the clamping jaws 135 and extends beyond its front boundary, so that workpiece sections can also be gripped that are at least partially located outside the clamping jaw gripping area 136, for example due to vibrations or deflections (see Fig. 3).

[0064] The workpiece catching unit has two catching arms 155 which can be moved between at least three different working configurations by means of a second drive system 170, which will be explained later with reference to Figs. 3 to 6.

[0065] The gripping arms 155 can be pivoted axially parallel to the clamping jaws about second pivot axes S2 running perpendicular to the main plane HE and enclose with their inner sides facing the center plane ME a spatial area 156 which is larger than the clamping jaw detection area 136 located between the clamping jaws and extends beyond the front end of which by at least 50% of the depth of the clamping jaw detection area measured in the axial direction.

[0066] The gripping arms can not only be pivoted relative to each other, but can also be moved parallel to the gripping system axis GA (i.e., in the axial direction of the gripping system). The gripping arms have free end sections at their front ends, which are designed like angled hooks and have retaining lugs 157 directed inward (toward the center plane ME).

[0067] The gripping arms 155 are made of plate-shaped, flat tool steel or sheet steel and have a thickness of a few millimeters in the direction of penetration of the workpiece material (perpendicular to the main plane HE). The flat, yet torsion-resistant gripping arms are not directly opposite each other with respect to the center plane ME, but rather on different sides of the center plane ME and on different sides of the main plane HE. The distance between the gripping arms, measured perpendicular to the main plane HE, is at least 10% or at least 20% less than the engagement length EL of the clamping jaws measured in this direction. In order to be able to integrate the gripping arms relatively close to one another in this way, but with a mutual distance between them, in the area of ​​the clamping jaws, each clamping jaw has a flat recess 158 to guide the associated gripping arm, in which the flat material of the associated gripping arm can slide freely inwards and outwards.The clamping jaws therefore also serve as guide elements for the gripping arms.

[0068] The mutual offset between the workpiece catching units is advantageous, among other things, because it allows for the widest possible length to be realized or covered between the two workpiece catching units. This is beneficial, among other things, for stability when catching and positioning the busbar.

[0069] If a workpiece section to be clamped or clamped is to be grasped using the end effector, the gripping arms 155 are first moved into the gripping configuration, in which the gripping arms are moved forward as far as they can and pivoted outward, and the angled front ends of the gripping arms are spaced in front of the front ends of the clamping jaws, so that the gripping area 156 enclosed by the gripping arms is significantly larger than the gripping area 136 of the clamping jaws (see Fig. 3). This means that the gripping arms can also be used to reach workpiece sections that are not in their desired position between the clamping jaws when the end effector is moved into the correct position for the next access.After grasping a workpiece section in the grasping configuration, a first phase of the working movement of the gripping arms 155 leads to a positioning configuration, which is shown in Fig. 4, by pivoting inwards in opposite directions. In the positioning configuration, the gripping arms are closed by pivoting inwards such that the retaining lugs 157 of the gripping arms engage behind the workpiece section, so that the workpiece can no longer slip out of the position predetermined by the gripping arms. However, in this closed configuration of the gripping arms, the workpiece is not clamped or held in place by them, but rather a slight play remains between the broad sides of the flat material and the facing inner sides of the gripping arms 155, so that the workpiece can be moved relative to the gripping arms in the longitudinal direction of the workpiece section without being hindered by the gripping arms.In this closed positioning configuration, the closed gripping arms thus form a guide for possible axial movements of the workpiece section relative to the gripping system.

[0070] The final working configuration, the holding configuration, is achieved when the gripping arms are displaced maximally toward the mounting flange, i.e., to the rear (see Fig. 5). The geometry of the gripping arms is adapted to the workpiece geometry so that the workpiece section to be gripped by the clamping jaws is now located exactly in the target position SP intended for gripping by the clamping jaws. Axial movement of the workpiece section relative to the gripping arms is still possible here.

[0071] This is prevented when the clamping jaws are closed by pivoting inward (see Fig. 6). In this clamped state, the workpiece can then be manipulated spatially by further movements of the end effector.

[0072] The relatively complex movement sequence of the working movement of the gripping arms 155 is made possible in the exemplary embodiment by the following design measures. For each gripping arm, there is an L-shaped guide element 160, which is mounted on the base support 110 using fastening screws, i.e., fixed to the support, such that its longer leg runs parallel to the axial direction (direction of the gripping system axis GA). Within this leg, a guide track 162 is machined, which has a longer axial guide section on the rear side facing the mounting flange, which curves forward into an end section that runs diagonally outwards. The guide track serves to guide the movement of two link elements, namely a rear link element 164 and a front link element 165, which are mounted at a distance from one another on the associated gripping arm.A pneumatic second drive system 170 is provided to generate the movements of the catching arm relative to the guide element. In the example, this comprises a dual-action cylinder-piston drive unit 172 for each catching arm, the effective length of which can be pneumatically adjusted. The cylinder side of the drive unit is pivotally connected to a support-fixed retaining bracket, and the opposite end of the piston rod is pivotally coupled to an outwardly directed retaining projection of the catching arm 155. If the catching arms are to be brought into the maximum open catching configuration (Fig. 3), the pistons are extended. The front guide elements then move into the outward-facing inclined end sections, causing the catching arms to pivot outward about the second pivot axes S2 running through the rear guide elements.To close the gripping arms, the pistons are retracted so that the front guide elements 165 move into the axially parallel axial guide section, thereby closing the gripping arms (Fig. 4). In this configuration, the closed gripping arms can then be pulled even further toward the rear end by retracting the pistons further. This allows the workpiece section to be moved to the target position SP between the clamping jaws at the end (see Fig. 5).

[0073] In a method for producing a bent part from an elongated workpiece using such a bending system, the end effector for gripping and clamping a workpiece section for a subsequent bending operation can be moved to a target position in space specified by a control program. This target position is calculated such that, given the target geometry of the workpiece, a workpiece section to be gripped is located in a target position within the engagement area of ​​the clamping jaws of a clamping unit of the gripping system. However, deflections and / or vibrations of the workpiece, for example, can lead to the workpiece section to be gripped not being in its target position.However, if its actual position deviates from the target position, the workpiece section can be grasped by the gripping arms of the gripping system's workpiece catching unit and moved relative to the clamping unit in such a way that, at the end of a grasping operation, the workpiece section is in its target position between the clamping jaws. The clamping jaws can then be moved into their clamping configuration to clamp the workpiece section in its target position.

[0074] The workpiece section can be held in the desired position by the gripping arms without clamping, so that the workpiece section remains movable relative to the clamping jaws in the longitudinal direction of the workpiece section and can be guided by the gripping arms. If the end effector is to be moved to a new workpiece section after the end of a bending operation and before the start of a subsequent bending operation in order to grip the workpiece in the longitudinal direction of the workpiece, the clamping jaws are opened before the start of the movement to release the workpiece section. The gripping arms, on the other hand, can remain closed and engage with the workpiece during the movement so that the workpiece can be immediately clamped again at the new clamping point. This results in considerable time savings in the bending process.

[0075] The embodiment is designed for processing flat material; accordingly, the clamping surfaces of the clamping jaws intended for workpiece contact are flat surfaces. The principle of the invention can also be used for processing workpieces with other cross-sectional profiles, e.g., round material with a circular or oval cross-section, or with a polygonal cross-section, e.g., a hexagonal or triangular cross-section. For this purpose, the inner surfaces of the clamping jaws and, if necessary, the inner sides of the gripping arms should be profiled accordingly.

[0076] With reference to Fig. 7 and Fig. 8, an embodiment will now be described which has only a single drive system that actuates both the gripping arms 155 and the clamping jaws 135. For reasons of clarity, the same reference numerals are used for identical or similar components as in the first exemplary embodiment.

[0077] Fig. 7 shows the configuration (positioning configuration) that corresponds to the configuration in Fig. 4. The gripping arms 155 have already grasped the workpiece W and the gripping arms 155 have already closed, so that the workpiece is already held but is not yet in the clamping position. Fig. 8 shows the configuration that results after the gripping arms have brought the workpiece W into the target position and the clamping jaws 135 have been closed.

[0078] All working movements of the gripping arms 155 and the clamping jaws 135 are effected by means of a single drive system, which corresponds to the first exemplary embodiment with regard to the controllable drives (pneumatically or hydraulically operated cylinder-piston drive units 172) and the guide rail (guide track 162, guide rail elements 164, 165) for controlling the working movement of the gripping arms. However, there is no separate hydraulic piston for actuating the clamping jaws 135. These are actuated via the pivoting gripping arms 155, also by the cylinder-piston drive units of the drive system. For this purpose, the clamping jaws 135 are kinematically coupled to the gripping arms 155 by a curved guide. For this purpose, a guide pin 176 is attached to each clamping jaw, which acts similarly to a sliding block and is guided along a guide rail 177 formed on the inward-facing side of the associated gripping arm.This mechanical coupling mechanism is designed in such a way that during the phase of the retraction movement of the catch arms to the rear (transition from Fig. 7 to Fig. 8), the bolt runs along the guide track in such a way that the clamping jaws 155 are pivoted inwards into their clamping configuration (Fig. 8).

[0079] In a further embodiment, the end effector is designed in the manner of a rotary tongs. For this purpose, a base plate 116, shown in dashed lines in Fig. 8, is mounted on the base support 110. This base plate can be rotated relative to the base support about a rotation axis 117 by means of a rotary drive, which axis runs perpendicular to the main plane HE and centrally through the engagement area of ​​the clamping jaws. The base plate can, for example, have teeth on its circumference into which pinions of a rotary drive engage (cf., for example, DE 10 2018 108 863 A1). The base plate carries the components of the gripping system, in particular the gripping arms, the clamping jaws and the associated drive units (one or two). Compared to the previously described embodiments, this creates a further controllable degree of freedom of movement, which makes it possible to rotate the components of the gripping system in a plane parallel to the main plane.This means that more complex gripping tasks can be completed even faster than with variants without the additional rotation option.

Claims

Patent claims 1. Bending system (200) for producing a bent part from an elongated workpiece (W), comprising: a bending head unit (210) with at least one controllable bending tool (215) for generating at least one bend on the workpiece; and a robot unit (220) for handling (manipulating) the workpiece before, during, and after generating bends, wherein the robot unit has a base (222) and an end effector (100) that is kinematically coupled to the base (222), can be positioned in space with respect to the base in a multi-axis controlled manner, and is rotatable about an effector axis (110) in the assembled state, and has a gripping system (120) for gripping the workpiece before, during, and after generating bends, characterized in that the gripping system (120) has two sub-units, wherein a first sub-unit is designed as a clamping unit (130) and has two clamping jaws (135),the inner sides facing one another define a clamping jaw engagement area (136) and are movable in opposite directions between an open configuration and a clamping configuration by means of a drive system, and a second sub-unit is designed as a workpiece catching unit (150) and has at least two catching arms (155) which are movable relative to the clamping jaws by means of a drive system such that a section of the workpiece positioned at least partially outside the clamping jaw engagement area (136) within a catching area (156) of the catching arms can be grasped by the catching arms (155) and moved by controlled movement of the catching arms relative to the clamping jaws into a desired position (SP) lying within the clamping jaw engagement area.

2. Bending system according to claim 1, characterized in that the gripping system (120) has two independently controllable sub-units, wherein the first sub-unit has two clamping jaws (135) which are movable by means of a first drive system (132), and the second sub-unit has at least two gripping arms (155) which are movable relative to the clamping jaws by means of a second drive system (170).

3. Bending system according to claim 1 or 2, characterized in that the catch arms (155) are movable between an open capture configuration, a closed positioning configuration and a closed holding configuration, preferably by means of the second drive system (170), 4. Bending system according to one of the preceding claims, characterized in that the workpiece catching unit is configured such that the workpiece positioned in the target position (SP) can be held in the target position by the catching arms without clamping.

5. Bending system according to one of the preceding claims, characterized in that the catch arms (155) have free end sections which are designed in the manner of angle hooks with inwardly directed holding projections (157).

6. Bending system according to one of the preceding claims, characterized in that the end effector (100) has a base support (110) with mounting structures for mounting on a mounting side of a member (G6) of the robot unit (220) that can be rotated about a rotation axis, such that the end effector, in the mounted state, can be rotated about the effector axis (EA) by rotating the member, that the gripping system (120) defines a main plane (HE), a center plane (ME) oriented perpendicular to the main plane, and a gripping system axis (GA) that lies in the main plane (HE) and the center plane (ME), and that working movements of the clamping jaws (135) and the gripping arms (155) run parallel to the main plane (HE) and in the opposite direction to the center plane (ME).

7. Bending system according to one of the preceding claims, characterized in that the gripping system axis (GA) is aligned obliquely to the effector axis (EA).

8. Bending system according to one of the preceding claims, characterized in that the clamping jaws (135) are pivotable about first pivot axes (S1) oriented perpendicular to the main plane (HE) and the gripping arms (155) are pivotable about second pivot axes (S2) oriented perpendicular to the main plane, wherein the second pivot axes (S2) are additionally displaceable parallel to the gripping system axis (GA).

9. Bending system according to one of the preceding claims, characterized in that a respective slotted guide is provided for guiding working movements of the gripping arms (155), wherein preferably for each gripping arm (155) a guide element (160) fixed to the support is arranged with a guide track (162), which has a rear axial guide section parallel to the gripping system axis (GA), which merges into an obliquely outwardly pointing front end section, and in that on the gripping arm (155) a rear slotted element (164) guided in the rear axial guide section of the guide track and at a distance therefrom a front slotted element (165) is attached, which in dependence from an axial position of the catch arm engages the rear axial guide section or the front end section.

10. Bending system according to one of the preceding claims, characterized in that the second drive system (170) has for each catch arm a drive unit (170) acting by changing the length, which is articulated with one end to the base support (110) and with an opposite end to the catch arm (155), wherein the drive unit is preferably designed as a pneumatically or hydraulically operable cylinder-piston drive unit.

11. Bending system according to one of the preceding claims, characterized in that the clamping jaw detection area (136) extends parallel to a center plane (ME) on both sides of a main plane (HE) from a first end to a second end over an engagement length (EL) and the catch arms are arranged between the first and the second end at a distance from these within the clamping jaw detection area.

12. Bending system according to claim 11, characterized in that the catch arms (155) are arranged on different sides of the main plane (HE).

13. A method for producing a bent part from an elongated workpiece by means of a bending system comprising a bending head unit with at least one controllable bending tool for producing at least one bend on the workpiece and a robot unit for handling the workpiece before, during and after the production of bends, wherein the robot unit has a base and an end effector kinematically coupled to the base and positionable relative to the base in a multi-axis controlled manner, which is rotatable about an axis of rotation and has a gripping system for gripping the workpiece before, during and after the production of bends, wherein the end effector is moved to grip and clamp a workpiece section for a next bending operation into a target position in space predetermined by a control program, which is calculated so thatthat a workpiece section to be gripped is located in a target position in the engagement area of clamping jaws of a clamping unit of the gripping system when the target geometry of the workpiece is present, that the workpiece section is gripped by gripping arms of a workpiece catching unit of the gripping system when its actual position deviates from the target position and is displaced relative to the clamping unit in such a way that the workpiece section is in its target position between the clamping jaws at the end of a catching operation, and that the clamping jaws are then moved into a clamping configuration in order to clamp the workpiece section in its desired position.

14. Method according to claim 13, characterized in that the workpiece section is held in the desired position by the gripping arms without clamping, so that the workpiece section remains movable relative to the clamping jaws in the longitudinal direction of the workpiece section and is guided by the gripping arms.

15. Method according to claim 13 or 14, characterized in that the end effector is moved after the end of a bending operation before the start of a subsequent bending operation to grasp the workpiece in the longitudinal direction of the workpiece to a new workpiece section, wherein before the start of the movement the clamping jaws are opened to release the workpiece section and the gripping arms remain closed and remain in engagement with the workpiece during the movement.

16. End effector (100) for use on a robot unit of a bending system for producing a bent part from an elongated workpiece, wherein the bending system has a bending head unit with at least one controllable bending tool for producing at least one bend on the workpiece and the robot unit for handling the workpiece before, during and after the creation of the bends, wherein the end effector (100) is rotatable about an effector axis (110) in the assembled state and has a gripping system (120) for gripping the workpiece before, during and after the creation of bends, characterized in that the gripping system (120) has two sub-units, wherein a first sub-unit is designed as a clamping unit (130) and has two clamping jaws (135),the inner sides facing one another define a clamping jaw engagement area (136) and are movable in opposite directions between an open configuration and a clamping configuration by means of a drive system, and a second sub-unit is designed as a workpiece catching unit (150) and has at least two catching arms (155) which are movable relative to the clamping jaws by means of a drive system such that a section of the workpiece positioned at least partially outside the clamping jaw engagement area (136) within a catching area (156) of the catching arms can be grasped by the catching arms (155) and moved by controlled movement of the catching arms relative to the clamping jaws into a desired position (SP) lying within the clamping jaw engagement area.

17. End effector according to claim 16, characterized by the features of the characterizing part of at least one of claims 2 to 12.

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