Swivel bending machine

Abstract

The invention relates to a swivel bending machine (1) comprising, in a region in front of a front side (18) of a workpiece holding unit (3), a support table (17) for workpieces to be bent. A workpiece manipulator (23) is provided, which is designed to pick up workpieces to be bent from at least one of the table end regions (20, 21) and to take the workpieces, in parallel with the longitudinal direction (12) of a bending beam, to a portion in the region of the longitudinal centre (24) of the workpiece holding unit (3). The workpiece manipulator (23) has a first pair of clamping tongs (25) and a second pair of clamping tongs (26), which is spaced apart from the first pair in the longitudinal direction (12) of the bending beam, for establishing a clamping connection with respect to a workpiece. At least one of the two pairs of clamping tongs (25, 26) has a first stop surface for referencing positioning of a workpiece in relation to the longitudinal direction (12) of the bending beam and has a second stop surface for referencing positioning of said workpiece in relation to a depth direction (16) of the swivel bending machine (1).

Description

[0001] The invention relates to a swivel bending machine for the automated or semi-automated forming of sheet metal workpieces that are initially flat.

[0002] JP2001-205343A and US5950484A disclose folding machines with various workpiece manipulators for workpieces to be bent. WO96 / 32214A1 discloses a folding machine with referencing stops for a workpiece to be bent.

[0003] From WO2017 / 181208A1, which originates from the applicant, a generic folding machine with a workpiece holding unit and a bending beam that is adjustable relative to it is known. In order to be able to reliably process even relatively large-format or relatively heavy sheet metal workpieces with such folding machines, passive support tables or support tables with automatically operated conveyor devices for the workpieces are provided. These support tables are arranged in the area in front of the workpiece holding unit, so that, with respect to a depth direction of the folding machine, the support table is formed first, followed by the workpiece holding unit, and then the bending beam. A disadvantage of the designs known from the prior art is that, with large-area support tables, it is relatively difficult for an operator to feed small-format workpieces to the central section of the workpiece holding unit.As a remedy for this, it is known to assign a conveyor device to the support table, which conveyor device conveys the workpieces to be bent from the front area of ​​the support table in the depth direction backwards to the workpiece holding unit.

[0004] A folding machine according to the introductory part of claim 1 is also known from the product video on youtube.com or on Trumpftube: "TRUMPF Bending: Automated loading and unloading of the TruBend Center 7030", March 18, 2019 (2019-03-18), XP093013179.

[0005] The folding machines known from the state of the art have the disadvantage that feeding small-format workpieces is not very ergonomic for an operator and proper positioning and exact referencing of a workpiece to be machined can be difficult for an operator.

[0006] The object of the present invention was to overcome the disadvantages of the prior art and to provide technical means by means of which even small-format workpieces can be fed and positioned precisely without any particular effort for an operator.

[0007] This object is achieved by a swivel bending machine according to the claims.

[0008] The bending machine according to the invention comprises a machine frame; a workpiece holding unit connected to the machine frame, comprising a first clamping tool and an adjustable second clamping tool cooperating therewith, for fixing a workpiece in a horizontal working plane such that a workpiece section to be bent can protrude relative to the workpiece holding unit; a bending beam adjustably mounted on the machine frame and connected to an adjustment drive for bending the workpiece section; wherein the bending beam has an approximately C-shaped beam cross-section and two bending tools opposite and facing one another with respect to a horizontal center plane, extending in the longitudinal direction of the bending beam, between which bending tools a workpiece section to be bent can be inserted;a support table for workpieces to be bent in an area in front of a front side of the workpiece holding unit, which front side represents the side of the workpiece holding unit opposite the bending beam, which support table has a table length measured parallel to the longitudinal direction of the bending beam of more than 1.5 m, in particular of more than 2 m, between its two table end areas and which support table has a table depth measured parallel to the horizontal working plane and perpendicular to the front side of more than 1.0 m, in particular of more than 1.5 m, wherein a depth direction of the folding machine is defined by the serial sequence of the support table, the workpiece holding unit and the bending beam;a workpiece manipulator which is designed to pick up workpieces to be bent from at least one of the table end regions and to move them parallel to the longitudinal direction of the bending beam into a section in the region of the longitudinal center of the workpiece holding unit, wherein the workpiece manipulator has a first clamping tong and a second clamping tong spaced therefrom in the longitudinal direction of the bending beam for establishing a clamping connection with a workpiece, ; and wherein at least the first clamping tongs have a first stop surface for referencing a workpiece with respect to the longitudinal direction of the bending beam and a second stop surface for referencing this workpiece with respect to the depth direction of the folding machine.

[0009] Workpiece referencing refers to the positioning or alignment of the workpiece relative to a zero or reference point specified by the control system of the folding machine. Such a zero or reference point for a workpiece to be machined can also be referred to as the starting point, which is typically located within the working plane.

[0010] The folding machine according to the invention offers the advantage that an operator can feed a workpiece to be machined to the workpiece manipulator from one of the two side areas of the support table, and the workpiece can then be automatically transferred to the central section of the tool holding unit. This enables ergonomic workpiece feeding for the operator, both for small-format and relatively heavy workpieces. Furthermore, an operator can always feed a workpiece precisely and easily to the specified workpiece manipulator because the first and second clamping tongs are clearly visible and easily accessible for the operator. In particular, the operator can quickly and easily verify that the workpiece to be bent has assumed the planned reference position.

[0011] It may also be advantageous for the workpiece manipulator to be movable into and out of the interior of the bending beam, enclosed by the C-shaped beam cross-section, by means of a guide arrangement running parallel to the longitudinal direction of the bending beam. This allows for a compact design of the workpiece manipulator. Furthermore, by coupling the movement to the bending beam, the workpiece manipulator can be easily adjusted vertically and vertically.

[0012] Furthermore, it can be provided that the workpiece manipulator can be moved beyond at least one longitudinal end of the bending tools by means of the guide arrangement. This significantly improves the operator's visibility of the two clamping tongs, and in particular their stop surfaces.

[0013] Furthermore, it may be expedient if the first and second clamping tongs are each mounted on a translational adjustment axis, and these adjustment axes are provided for the controlled positioning of the first and second clamping tongs along the depth direction of the folding machine. This allows for rapid and technically reliable positioning of a workpiece to be bent relative to the depth direction of the folding machine. In particular, the transfer of the workpiece from the workpiece manipulator to the workpiece holding device can take place taking into account the target position of the first bending edge to be created.

[0014] Furthermore, it can be provided that the first and second clamping pliers each comprise a pneumatically actuated actuating cylinder for closing the respective clamping pliers. This enables alternate or independent activation of the clamping action against a workpiece. Accordingly, it is possible to utilize the clamping action of only one of the two clamping pliers. Pneumatic actuation of the clamping pliers offers a good compromise between technical simplicity, cost-effectiveness, and functional availability.

[0015] Furthermore, it can be provided that the first and second clamping pliers each have a wedge-shaped, tapered actuating section, and that an actuating piston, extendable from the actuating cylinder, can be inserted into the actuating section with an expanding effect. This allows high and reproducibly available clamping forces to be generated against a workpiece even with a pneumatically actuated actuating cylinder.

[0016] According to a further development, it is possible for the first and second adjustment axes each to have an electric motor and a threaded spindle coupled to the electric motor for translational adjustment of the first and second clamping tongs. These measures enable precise and repeatable positioning of the clamping tongs and thus of the workpiece to be transported with respect to the depth direction of the folding machine or the workpiece holding unit.

[0017] Furthermore, it may be expedient if the first or second clamping tongs, or the first and second clamping tongs, are configured to grip a side edge of a workpiece that runs parallel to the longitudinal direction of the bending beam and is located closest to the bending beam. This utilizes the workpiece's rear boundary edge, which is essentially at the rear of the workpiece relative to the user's position and the depth direction of the folding machine, for clamping and referencing. This improves ergonomics and also provides visibility to the workpiece manipulator. This allows the operator to perform quick, uncomplicated, and repeatable positioning and transfer processes relative to the workpiece manipulator.

[0018] Furthermore, it can be provided that the first stop surface, which is intended for referencing or referencing the positioning of a workpiece with respect to the longitudinal direction of the bending beam, runs vertically and transversely to the longitudinal direction of the bending beam and is positioned outside a clamping section of the first and second clamping pliers. This advantageously makes it possible to use the stop or referencing function of the first and / or second clamping pliers independently of the active or inactive state of the clamping function of the first and / or second clamping pliers.

[0019] Furthermore, the first and / or second clamping pliers can comprise a non-pivoting lower support finger and an upper clamping finger, which upper clamping finger is pivotally mounted relative to the lower support finger about a horizontal pivot axis. This enables precise and reliable positioning or referencing of a workpiece in the vertical or vertical direction. Furthermore, this allows for stable and functionally reliable holding and clamping of a flat or properly positioned workpiece.

[0020] The first and second stop surfaces for the planned positioning and alignment of a workpiece to be machined are formed directly on the first and second clamping tongs. It is expedient if the first stop surfaces for the relative positioning of a workpiece with respect to the longitudinal direction of the bending beam are formed on the pivotably mounted clamping fingers of the first and second clamping tongs. The second stop surfaces for the relative positioning of a workpiece in the depth direction of the folding machine are preferably formed on the support fingers of the first and second clamping tongs, which are fixed with respect to the pivotable clamping fingers.

[0021] According to a special embodiment, the workpiece manipulator can be configured to use the first stop surface of only one of the two clamping tongs to reference a workpiece in the longitudinal direction of the bending beam, while only using the other of the two clamping tongs to clamp the workpiece. Accordingly, one of the clamping tongs, for example the first clamping tong, ensures reference to the control-related zero point, while the other, for example the second clamping tong, clamps or holds the workpiece. This division of the referencing and holding or clamping functions makes it easier for the operator to load the workpiece manipulator with sheet-like or plate-like workpieces.

[0022] In particular, it can be advantageous if a support body of an additional manipulator projects vertically from a table plane of the support table. This additional manipulator has a rotary punch rotatable about a vertical axis for rotating workpieces to be machined about the vertical axis, and if the support body projects vertically in the longitudinal center or in the region of the longitudinal center of the support table. This allows workpieces on which angled or perpendicular bending edges are to be produced can be automatically rotated about their vertical axis. The restricted accessibility of the workpiece holding device caused by such an additional manipulator can be compensated for by the workpiece manipulator, which can be positioned and loaded on one of the two longitudinal sides of the support table.

[0023] For a better understanding of the invention, it is explained in more detail using the following figures.

[0024] They show in simplified, schematic and exemplary representation: Fig. 1 shows a perspective view of a folding machine with a support table for workpieces to be machined arranged on the front side; Fig. 2 shows the support table, the workpiece holding unit and the bending beam of the folding machine according to Fig. 1 in schematic side view; Fig. 3 a detail of the folding machine according to Fig. 1 with the workpiece manipulator; Fig. 4 an operator of the folding machine during the transfer of a sheet metal workpiece to the workpiece manipulator of the folding machine; Fig. 5 the first and second clamping tongs of the workpiece manipulator for a folding machine according to Fig. 1 ; Fig. 6the left clamping pliers from Fig. 5 cut along lines VI-VI in Fig. 5 ; Fig. 7the left clamping pliers from Fig. 5 cut along lines VII-VII in Fig. 5 .

[0025] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied analogously to the new position in the event of a change in position.

[0026] In the Fig. 1 to 4 an embodiment of a swivel bending machine 1 for forming workpieces 2 made of sheet metal is shown, wherein in the Fig. 2 to 4Details of this folding machine 1 are illustrated. This machine comprises at least one machine frame (not shown in detail), in particular a supporting structure for the individual machine components or machine assemblies. Accordingly, a workpiece holding unit 3 connected to the machine frame is provided for fixing or clamping a sheet metal workpiece 2 during its forming. Such a workpiece holding unit 3 comprises a first, usually stationary clamping tool 4 and a relatively adjustable second clamping tool 5 which cooperates with the first clamping tool 4 and for fixing a workpiece 2 in a horizontal working plane 6. The fixing or clamping of a workpiece 2 to be machined takes place in such a way that a workpiece section 7 to be bent protrudes like a tongue with respect to the workpiece holding unit 3.

[0027] A bending beam 8 is also mounted on the machine frame, which is connected to a controllable adjustment drive 9 and is thus mounted so that it can be adjusted relative to the machine frame. The bending beam 8 serves to bend the workpiece section 7 protruding from the workpiece holding unit 3 vertically upwards and / or vertically downwards.

[0028] The bending beam 8 has an approximately C-shaped beam cross-section 10 and two longitudinally oriented beam sections 12, which are opposite and facing each other with respect to a horizontal center plane 11. Fig. 1- of the bending beam 8 or the folding machine 1. A workpiece section 7 of a workpiece 2 to be bent can be inserted between the lower and upper bending tools 13, 14. By relative adjustment of the bending beam 8 in the vertical direction 15 and / or in the depth direction 16 of the folding machine 1, the desired deformation of the workpiece 2 can be achieved by an upward or downward bending of the workpiece section 7.

[0029] The folding machine 1 further comprises a support table 17 for workpieces 2 to be bent in an area in front of a front side 18 of the workpiece holding unit 3. The front side 18 of the workpiece holding unit 3 is the side of the workpiece holding unit 3 facing away from the bending beam 8. Accordingly, the support table 17 and the bending beam 8 are arranged opposite one another with respect to the workpiece holding unit 3. The support table 17 has a table length 19, measured parallel to the longitudinal direction 12 of the bending beam 8, of more than 1.5 meters between its two table end regions 20, 21. The support table 17 has a table depth 22, measured parallel to the horizontal work plane 6 and perpendicular to the front side 17, of more than 1.0 meter. The depth direction 16 of the folding machine 1 is defined by the serial sequence of the support table 17, the workpiece holding unit 3, and the bending beam 8.Accordingly, the support table 17 has such a large horizontal surface area that an operator can only reach the workpiece holding unit 7 or the edge of the support table 17 closest to the workpiece holding unit 7 with difficulty or can only see it relatively poorly. The support table 17 extends directly or essentially gap-free to the workpiece holding unit 3. In particular, the support table 17 extends so close to the workpiece holding unit 3 that it is impossible for an operator to find space between it or to enter it.

[0030] Preferably, the table length 19 of the support table 17 corresponds at least to the maximum settable length of the workpiece holding unit 3. Typically, the table length 19 is greater than the maximum settable length of the workpiece holding unit 3 or greater than the maximum settable length of the bending tools 13, 14. All length specifications in the present description refer to a direction parallel to the longitudinal direction 12 of the bending beam 8.

[0031] The folding machine 1 further comprises a workpiece manipulator 23 which is configured to pick up workpieces 2 to be bent, in particular flat sheet metal blanks, from at least one of the two table end regions 20, 21, for example, from the right table end region 21. The workpiece manipulator 23 is further configured or provided to move a picked up or gripped workpiece 2 parallel to the longitudinal direction 12 of the bending beam 8 into a section in the region of a longitudinal center 24 - Fig. 1 , 2 - the workpiece holding unit 3 or the bending beam 8. Workpieces 2 to be machined are generally clamped in the region of the longitudinal center 24 of the workpiece holding unit 3 and then subjected to a forming force by at least one of the bending tools 13, 14.

[0032] The workpiece manipulator 23 has at least one first clamping tong 25 and a second clamping tong 26 spaced apart therefrom in the longitudinal direction 12 of the bending beam 8 for establishing a clamping connection with respect to a workpiece 2 to be machined. The clamping function of the two clamping tongs 25, 26 with respect to a workpiece 2 to be transported is preferably used selectively, i.e. used by only one of the two clamping tongs 25, 26, as shown in Fig. 4 can be seen by way of example. Accordingly, a workpiece to be transported is clamped either with the first clamping pliers 25 or, alternatively, with the second clamping pliers 26.

[0033] How best to continue Fig. 4As can be seen, at least the first clamping tongs 25, but preferably both clamping tongs 25, 26, have a first stop surface 27, 28 for referencing, in particular for referencing positioning, a workpiece 2 to be machined with respect to the longitudinal direction 12 of the bending beam 8. In addition, at least the first clamping tongs 25, but preferably both clamping tongs 25, 26, have a second stop surface 29, 30 for referencing this workpiece 2 with respect to the depth direction 16 of the folding machine 1.

[0034] By manually placing or striking a workpiece 2 to be machined against at least three of the stop surfaces 27 or 28 and 29, 30, the workpiece 2 can be precisely positioned with respect to the zero point or reference point of a control device 31 of the folding machine 1 and precisely aligned (oriented) with respect to a reference line or reference orientation. Subsequent manipulation processes with respect to the workpiece 2, in particular transport and bending processes, can then refer to this reference point or the reference line. Since the support plane for the workpiece 2 to be fed is also predefined or known at the workpiece manipulator 23, the orientation and position of the workpiece 2 to be machined in three-dimensional space is defined for the control device 31.The subsequent manipulation processes with respect to the correspondingly aligned and positioned workpiece 2 are initiated or controlled partially or fully automatically by the control device 31.

[0035] How best to use the Fig. 2 to 4 As can be seen, the workpiece manipulator 23 is movable in an automated or controlled manner into and out of the inner region 33 of the bending beam 8, which is enclosed by the C-shaped beam cross-section 10, by means of a guide arrangement 32 running parallel to the longitudinal direction 12 of the bending beam 8. In particular, the workpiece manipulator 23 with its two clamping tongs 25, 26 is movable beyond at least one longitudinal end 34 of the first or second clamping tool 4, 5 or bending tool 13, 14 by means of the guide arrangement 32 and at least one adjustment drive (not shown in detail), as can be seen by way of example from the Fig. 3 , 4 is evident.

[0036] An embodiment of the two clamping tongs 25, 26 of the workpiece manipulator 23 is shown in Fig. 5 shown. The first and second clamping tongs 25, 26 are each mounted on a translational adjustment axis 35, 36. These adjustment axes 35, 36 are provided for the controlled positioning of the first and second clamping tongs 25, 26 along the depth direction 16 of the folding machine 1. An adjustment movement or a positioning process of the adjustment axes 35, 36 can occur independently of one another or be decoupled from one another. The maximum available travel of the adjustment axes 35, 36 can be between 30 mm and 100 mm, in particular approximately 50 mm.

[0037] The first and second clamping pliers 25, 26 each have a pneumatically actuated actuating cylinder 37, 38 for closing the respective clamping pliers 25, 26. The actuating cylinders 37, 38 can be designed as single-acting cylinders. For returning to the open position or to the starting position, the clamping pliers 25, 26 can each have a return spring 39, as shown in Fig. 6 can be seen. For controllable closing, the first and second clamping pliers 25, 26 can each have an internal, wedge-shaped tapered actuating section 40. An actuating piston 41, which can be extended from the actuating cylinder 37, 38, can be inserted into the actuating section 40 with an expanding effect in order to activate the clamping pliers 25, 26. Such an active clamping or closed position without a workpiece 2 is in Fig. 6 illustrated.

[0038] The first and preferably also the second clamping pliers 25, 26 have a non-pivoting lower support finger 42, 43 and an upper clamping finger 44, 45. The upper clamping finger 44, 45 is pivotally mounted relative to the lower support finger 42, 43 about a horizontal pivot axis 46, 47.

[0039] The first and second adjusting axes 35, 36 each have an electric motor 48, 49 and a threaded spindle 50, 51 coupled to the electric motor 48, 49 for the translational adjustment of the first and second clamping tongs 25, 26 along the depth direction 16 of the folding machine 1.

[0040] How best to Fig. 1 to 4 As can be seen, the first and second clamping pliers 25, 26 are designed to grip the side edge 52 of a workpiece 2 running parallel to the longitudinal direction 12 of the bending beam 8 and arranged closest to the bending beam 8.

[0041] The first stop surface 27, 28 of the clamping tongs 25, 26 is provided for referencing or for referencing the positioning of a workpiece 2 with respect to the longitudinal direction 12 of the bending beam 8. The first stop surface 27, 28 extends vertically and transversely to the longitudinal direction 12 of the bending beam 8. The first stop surface 27, 28 is preferably positioned outside a clamping section 53, 54 or outside the horizontally extending clamping surface of the clamping tongs 25, 26. As shown by way of example, the first stop surface 27, 28 and the second stop surface 29, 30 can also be cambered or rounded.

[0042] The workpiece manipulator 23 can be configured to use the first stop surface 27 or 28 for referencing a workpiece 2 in the longitudinal direction 12 of the bending beam 8 with only one of the two clamping tongs 25 or 26, and to use the clamping action against this workpiece 2 exclusively with the other of the two clamping tongs 26 or 25. Accordingly, only one of the two clamping tongs 25, 26 ensures the referencing of the workpiece 2 relative to the zero or starting point, while the other clamping tongs 25, 26 clamps or holds the workpiece 2 in such a way that it can be transported along the longitudinal direction 12 and along the depth direction 16 by means of the workpiece manipulator 23.

[0043] Again Fig. 1As can be seen, a support body 56 of an additional manipulator 57 can protrude vertically from a horizontal table plane 55 of the support table 17. This additional manipulator 57 has a rotary punch 58 that can be rotated about a vertical axis for rotating workpieces 2 to be machined about the vertical axis. The rotary punch 58 is mounted on a substantially horizontal support arm, which extends from the support body 56 in the direction of the workpiece holding unit 3. The support body 56 protrudes vertically in the longitudinal center 24 or in the region of the longitudinal center 24 of the support table 17. As a result, feeding the folding machine 1 with workpieces 2 from that longitudinal side of the support table 17 that faces away from or is furthest away from the workpiece holding unit 3 is difficult. This problem can be remedied by the previously described workpiece manipulator 23.The invention is not limited to the specifically illustrated embodiment. The scope of protection is determined by the claims.

[0044] Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying the independent inventive solutions can be found in the description.

[0045] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure, some elements have been shown out of scale and / or enlarged and / or reduced in size. Reference symbol list

[0046] 1 folding machine 30 second stop surface 31 Control device 2 workpiece 32 Guide arrangement 3 Workpiece holding unit 33 Interior 4 first clamping tool 34 Longitudinal end 5 second clamping tool 35 Adjusting axis 6 horizontal working plane 36 Adjusting axis 7 Workpiece section 37 Actuating cylinder 8 Bending beam 38 Actuating cylinder 9 Adjustment drive 39 Return spring 10 Beam cross-section 40 Operating section 11 horizontal center plane 41 Actuating piston 12 Longitudinal direction 42 Support fingers 13 Bending tool 43 Support fingers 14 Bending tool 44 Clamping finger 15 Altitude direction 45 Clamping finger 16 Depth direction 46 Swivel axis 17 Support table 47 Swivel axis 18 Front 48 electric motor 19 Table length 49 electric motor 20 Table end area 50 threaded spindle 21 Table end area 51 threaded spindle 22 Table depth 52 side edge 23 Workpiece manipulator 53 clamping section 24 Longitudinal center 54 clamping section 25 first clamp pliers 55 Table level 26 second clamp 56 Supporting body 27 first stop surface 57 Additional manipulator 28 first stop surface 58 Rotary stamp 29 second stop surface

Claims

1. A swivel bending machine (1), comprising - a machine frame; - a workpiece holding unit (3) connected with the machine frame and having a first clamping tool (4) and an adjustable second clamping tool (5) interacting therewith for fixing a workpiece (2) in a horizontal working plane (6) in such a way that a workpiece portion (7) to be bent can protrude beyond the workpiece holding unit (3); - a bending beam (8) mounted adjustably on the machine frame and connected to an adjusting drive (9) for bending the workpiece portion (7); - wherein the bending beam (8) has an approximately C-shaped beam cross section (10) and two bending tools (13, 14) running opposite to and facing one another with respect to a horizontal center plane (11) in the longitudinal direction (12) of the bending beam (8), between which a workpiece portion (7) of a workpiece (2) is insertable; - a support table (17) for workpieces (2) to be bent in a region in front of a front side (18) of the workpiece holding unit (3), said front side (18) representing the side of the workpiece holding unit (3) opposite the bending beam (8), said support table (17) having a table length (19) when measured in parallel to the longitudinal direction (12) of the bending beam (8) of more than 1.5m between its two table end regions (20, 21) and said support table (17) having a table depth (22) when measured in parallel to the horizontal working plane (6) and perpendicularly to the front side (18) of more than 1.0m, wherein a depth direction (16) of the swivel bending machine (1) is defined by the series arrangement of the support table (17), the workpiece holding unit (3), and the bending beam (8); - a workpiece manipulator (23) which is configured to receive workpieces coming from at least one of the table end regions (20, 21) and place them parallel to the longitudinal direction (12) of the bending beam (8) in a section in the region of the longitudinal center (24) of the workpiece holding unit (3), characterized in that the workpiece manipulator (23) has a first pair of clamping tongs (25) and, spaced apart from the first pair in the longitudinal direction (12) of the bending beam (8), a second pair of clamping tongs (26) for establishing a clamping connection with respect to a workpiece, and that at least one of the two pairs of clamping tongs (25, 26) has a first stop surface (27, 28) for the referencing positioning of a workpiece in relation to the longitudinal direction (12) of the bending beam (8) and a second stop surface (29, 30) for referencing positioning of this workpiece in relation to the depth direction (16) of the swivel bending machine (1).

2. The swivel bending machine according to Claim 1, characterized in that the workpiece manipulator (23) is movable into and out of the inner region (33) of the bending beam (8) enclosed by the C-shaped beam cross section (10) by means of a guide arrangement (32) running parallel to the longitudinal direction (12) of the bending beam (8).

3. The swivel bending machine according to Claim 2, characterized in that the workpiece manipulator (23) is movable beyond at least one longitudinal end (34) of the first or second clamping tool (4, 5) or the lower or upper bending tool (13, 14) by means of the guide arrangement (32).

4. The swivel bending machine according to one of the preceding claims, characterized in that the first and the second pair of clamping tongs (25, 26) are each fixed on a translational adjusting axle (35, 36) and these adjusting axles (35, 36) are provided for the controlled positioning of the first and second pair of clamping tongs (25, 26) along the depth direction (16) of the swivel bending machine (1).

5. The swivel bending machine according to one of the preceding claims, characterized in that the first and the second pair of clamping tongs (25, 26) each comprise a pneumatically actuable adjusting cylinder (37, 38) for closing the respective pair of clamping tongs (25, 26).

6. The swivel bending machine according to Claim 5, characterized in that the first and the second pair of clamping tongs (25, 26) each have a wedge-shaped, tapering activating section (40), and that an adjusting piston (41) extendable from the adjusting cylinder (37, 38) is insertable with an expanding effect into the activating section (40).

7. The swivel bending machine according to one of Claims 4 to 6, characterized in that the first and the second adjusting axles (35, 36) each have an electric motor (48, 49) and each have a threaded spindle (50, 51) coupled with the electric motor (48, 49) for the translational adjustment of the first and second pair of clamping tongs (25, 26).

8. The swivel bending machine according to one of the preceding claims, characterized in that the first or the second pair of clamping tongs (25, 26) or the first and the second pair of clamping tongs (25, 26) are configured to grip a side edge (52) of a workpiece (2) which runs parallel to the longitudinal direction (12) of the bending beam (8) and is arranged closest to the bending beam (8).

9. The swivel bending machine according to one of the preceding claims, characterized in that the first stop surface (27, 28), which is provided for referencing a workpiece (2) in relation to the longitudinal direction (12) of the bending beam (8), runs vertically and transversely to the longitudinal direction (12) of the bending beam (8) and is positioned outside of a clamping portion (53, 54) of the first and second pair of clamping tongs (25, 26).

10. The swivel bending machine according to one of the preceding claims, characterized in that the first and / or the second pair of clamping tongs (25, 26) comprise(s) a non-pivotable lower support finger (42, 43) and an upper clamping finger (44, 45), which upper clamping finger (44, 45) is, in relation to the lower support finger (42, 43), mounted pivotably around a horizontal pivot axle (46, 47).

11. The swivel bending machine according to one of the preceding claims, characterized in that the workpiece manipulator (23) is configured such as to only use the first stop surface (27, 28) of one of the two pairs of clamping tongs (25, 26) for referencing a workpiece (2) in the longitudinal direction (12) of the bending beam (8) and to exclusively use the clamping effect of the other of the two pairs of clamping tongs (26, 25) with respect to that workpiece (2).

12. The swivel bending machine according to one of the preceding claims, characterized in that a supporting body (56) of an additional manipulator (57) protrudes from a table level (55) of the support table (17) in vertical direction, which additional manipulator (57) has a rotation stamp (58) rotatable around a vertical axis for turning workpieces (2) to be machined around the vertical axis, and in that the supporting body (56) protrudes vertically in the longitudinal center (24) or in the region of the longitudinal center (24) of the support table (17).

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