EP3227035B1 - Folding tool, folding method and folding device - Google Patents

Description

The invention relates to a hemming tool, a hemming method and a hemming device with the features of the independent claims.

the JP H04 266433 A shows a hemming tool for multi-stage bending hemming of a workpiece, the hemming tool having a plurality of driven hemming elements which are advanced to a common hemming point. The hemming tool has three hemming elements arranged one above the other, the hemming elements each executing a pivoting movement for pre-hemming and intermediate hemming and the hemming element executing a sliding movement for final hemming.

Another hemming tool for two-step bending hemming of a workpiece is from the WO 99/37419 A known. The hemming or flanging tool has two driven hemming elements for pre-hemming and finishing hemming, which can be delivered to a common hemming point on the workpiece. The two hemming elements are designed as pre-hemming and finishing hemming steel and are arranged on a rotatable hemming head. From the DE 200 04 498 U1 Another version of such a hemming tool with two hemming elements is known.

the WO 98/02260 discloses a hemming tool in which several hemming elements that are jointly driven from a central point are fed to different hemming locations on a workpiece.

It is the object of the present invention to show an improved folding technique.

The invention solves this problem with the features in the independent claims.
The hemming technology claimed, ie the hemming tool and the hemming process and the hemming device, have various technical and economic advantages.

On the one hand, thanks to the three or more folding elements on the folding tool, the folding angle can be increased significantly. Folding angles of 160 ° and more can be formed by a single folding tool. This can be done in a single cycle or folding process. The workpiece can keep its position for this. The folding technique claimed is very efficient and inexpensive. It requires little construction and control effort and takes up little space.

On the other hand, the hemming process can be carried out very quickly and safely and in a single setting. The bending or hemming process takes place quickly, whereby the rebate or flange of the workpiece is plastically deformed into the end position without annoying springback. Overloading of the workpiece material during the bending or hemming process and the resulting defects, e.g. flow marks, can be avoided.

The folding elements can be fed to the common folding point one after the other in three or more folding steps and, in doing so, gradually bend the workpiece fold or flange until the desired end angle is reached. The flange or fold is bent in the same direction in each of the successive folding steps. This folding process can be carried out with high precision. The folding steps follow one another quickly, with the dwell time of the respective folding element on the other hand is sufficiently long in engagement with the workpiece rebate or flange to achieve the desired permanent deformation.

There is no need to reclamp the workpiece and divide the hemming process into several different hemming tools or hemming devices and the inaccuracies associated therewith. The folding technology claimed is significantly faster, more efficient and more cost-effective than the state of the art. This also has a positive effect on integration in a clock-based production system, e.g. in the body-in-white of vehicles.

The folding elements can have a common drive. This can be designed as a follow-up drive and ensure the rapid and precise movement and delivery sequence of the folding elements. The folding elements can also be removed from the folding point again after their respective folding step. The three or more folding elements can move without collisions and in a defined sequence of movements. It is also advantageous here if the folding elements are each mounted so that they can move independently.

The folding elements can have different kinematics, the pre-folding element executing a linear sliding movement. At least one other folding element for intermediate folding and / or final folding performs a pivoting movement during folding. The intermediate hemming element can perform a pivoting movement or a multi-axis sliding / pivoting movement and the final hemming element can execute a pivoting movement. The bearings of the folding elements are designed accordingly.

In a particularly favorable embodiment, the drive has a rotating drive shaft and a gear for transmitting the drive to the folding elements. The gearbox can also be used to control the sequence of steps and movements as well as the evasive or retreat movements of the folding elements. Such a drive design has particular advantages in terms of performance and low construction costs. A 360 ° rotation of the drive shaft is sufficient for the hemming process. At the end of this, the hemming tool automatically resumes its starting position, in which all the hemming elements are in a retracted position and enable a collision-free workpiece change. In addition, the control is significantly simplified. A gear design as a link gear has particular advantages for the defined kinematics and movement sequences as well as positions and alignments of the folding elements.

For the gear kinematics and the optimization of the performance and the hemming forces of the hemming tool, it is advantageous if the gear is divided into several gear groups, with each hemming element preferably being assigned its own gear group. The direct coupling of at least two transmission groups is also beneficial. This offers advantages for the exact control and coordination of the step and movement sequence of the folding elements and for the folding forces that can be applied. A coupling of the gear groups for an intermediate and a finished hemming element is particularly advantageous. A design of the gear groups as a respective toggle lever gear allows high folding forces.

Thanks to the gear unit, the hemming tool used also has advantages in terms of operational reliability, low wear and tear and energy consumption. The transmission can also be used advantageously for actuating and controlling the mounting of a folding element, in particular a multi-axis pivoting / sliding bearing. Due to the common drive, the drive energy can be supplied for all movements of the various parts of the hemming tool. A single drive means is sufficient, which can be designed in any suitable manner, e.g. as a controllable or regulatable electric motor.

Further advantageous refinements of the invention are specified in the subclaims.

Figur 1:

ein Falzwerkzeug und Teile einer Falzeinrichtung in einer Seitenansicht,

Figur 2:

eine vergrößerte Darstellung des Falzes an einem Werkstück in verschiedenen Winkelstellungen entsprechend der Falzschritte,

Figur 3 bis 7:

das Falzwerkzeug mit seinen Falzelementen in verschiedenen Betriebs- und Falzstellungen und

Figur 8 bis 10:

vergrößerte Detaildarstellungen des Falzes zu den Betriebs- und Falzstellungen von Figur 4, 6 und 7.

The invention is shown schematically and by way of example in the drawings. Show in detail:

Figure 1:

a folding tool and parts of a folding device in a side view,

Figure 2:

an enlarged view of the fold on a workpiece in different angular positions corresponding to the folding steps,

Figure 3 to 7:

the hemming tool with its hemming elements in various operating and hemming positions and

Figure 8 to 10:

enlarged detailed representations of the fold to the operational and fold positions of Figure 4 , 6th and 7th .

The invention relates to a hemming tool (2) for multi-stage bending hemming of a flange or hinge (6) on a workpiece (5). The invention also relates to a folding device (1) with one or more such folding tools (2) and a folding method.

The workpiece (5) is preferably thin-walled and made of metal. It can be single-ply or multi-ply. With a bent fold (6) according to Figure 2 and 10 another workpiece part (5 ') can be clamped. The further workpiece part (5 ') rests on the workpiece (5) and is overlapped by the plastically deformed fold (6) in its end position during the bending fold and clamped against the workpiece (5).

In the exemplary embodiments shown, the workpiece (5) is designed as a sheet metal part made of steel. The workpiece (5) can be used for any purpose. They are preferably sheet metal parts for the shell construction of vehicle bodies. The fold or flange (6) is designed to protrude from the outer edge of a workpiece (5), for example.

In Figure 1 a folding device (1) with an associated folding tool (2) is shown schematically and broken off. The folding tool (2) acts on a folding point (7) on the workpiece (5) and its fold (6). The hemming tool (2) can be present several times and at different points on the workpiece periphery. The design and function of the hemming tool (2) are explained below.

The folding device (1) can also have a workpiece support (4), in particular a folding bed, on which the workpiece (5) rests and is guided in a suitable manner. The workpiece position is preferably horizontal. Furthermore, the hemming tool (2) can have a hold-down device (3), for example a clamp, for the workpiece (5). The hold-down device (3) can be designed as desired and be present several times. He is in Figure 1 for the sake of clarity, symbolized by an arrow.

The hemming tool (2) is used for multi-stage bending hemming of the workpiece (5) or the hinge (6). The bending hemming takes place in three or more stages. The flange or fold (6) is bent in the same direction in each of the successive folding steps or steps. In Figure 2 various bending positions of the fold (6) are shown for this purpose.

The hemming tool (2) has three or more driven hemming elements (13, 17, 21). With the hemming tool (2), the hinge (6) can over a hinge angle ( α ) of, for example, 160 ° and to be bent more. The folding angle ( α ) can also be smaller depending on the design and setting of the folding tool (2).

As Figure 2 clearly shows, the fold (6) in the starting position (8) assumes an obliquely upwardly directed position with respect to the main plane of the workpiece (5). The fold (6) protrudes a little laterally beyond the edge of the workpiece support (4) directed vertically or transversely to the main plane of the workpiece.

In the first folding step, the fold (6) is bent into a more steeply upwardly directed intermediate layer (9), in particular perpendicular to the main plane of the workpiece. This first step is known as the pre-hemming step. In a next folding step, a so-called intermediate folding step, the fold (6) is bent back obliquely towards the workpiece (5) into an inclined intermediate layer (10). In the third folding step, the so-called final folding step, the fold (6) is bent into the end position (11), in which it is aligned e.g. parallel to the main plane of the workpiece (5).

In Figure 2 the folding angle ( α ) is approx. 160 °. It can also be smaller or larger than 160 °. Particular advantages over previously known two-stage hemming tools result from hinge angles ( α ) above 100 °, in particular 120 °. A preferred range for the folding angle ( α ) in practice is 120 ° to 180 °. In special cases it can be more than 180 °.

The three folding elements (13, 17, 21) are referred to as the pre-folding element (13), the intermediate folding element (17) and the final folding element (21). In the aforementioned three folding steps, they are fed one after the other to the common folding point (7) on the workpiece (5). They act in a row on the same fold point (7) and bend the fold (6) with plastic deformation in the aforementioned three folding steps.

The pre-fold element (13) performs a linear sliding movement. In the exemplary embodiment shown, this takes place during pre-folding. At least one other folding element (17, 21), preferably both folding elements (17, 21), perform a pivoting movement during folding. In the exemplary embodiment shown, this takes place during intermediate hemming and final hemming.

The intermediate fold element (17) can perform a multi-axis movement in the folding process, whereby it pivots about a joint or its axis (18 ') and this joint (18') can be displaced on the other hand. This displacement movement can be a pivoting movement or a linear movement.

The hemming tool (2) has a frame (12) which is supported in a suitable manner. It is preferably attached to the side of the workpiece support (4). The folding elements (13, 17, 21) are mounted on the frame (12) so as to be continuously movable. The pre-hemming element (13) has a bearing (14) which is designed, for example, as a sliding bearing. The bearing axis or direction of movement is oriented perpendicular to the main plane of the workpiece or, in the embodiment and workpiece position shown, vertically.

The intermediate fold element (17) has a bearing (18) which is designed, for example, as a multi-axis pivoting / sliding bearing. In the exemplary embodiment shown, the mounting (18) is formed by an adjusting means (41) that can move relative to the frame (12), in particular a pivot lever, and its articulated connection (18 ') with the intermediate fold element (17). In the exemplary embodiment shown, two pivoting movements are carried out, each with a horizontal axis (18 ', 45). That Actuating means (41) can alternatively be, for example, a slide or have a different design and kinematics.

The prefabricated rabbet element (21) has a bearing (22) which is designed, for example, as a frame-mounted pivot bearing with a horizontal axis.

In the embodiment shown with a horizontal workpiece arrangement, the folding elements (13, 17, 21) are arranged one above the other, with the pre-folding element (13) being arranged at the bottom, the intermediate folding element (17) in the middle and the finished folding element (21) being arranged above.

The folding elements (13, 17, 21) can be designed in any suitable manner, in particular in one piece or in several pieces. In the exemplary embodiments shown, they each have a folding jaw (15, 19, 23) with a folding contour suitable for the process and a jaw carrier (16, 20, 24). The jaw carrier (16, 20, 24) carries the permanently or exchangeably mounted folding jaw (15, 19, 23) at one end. At the other end of the end area or at another point, the jaw carrier (16, 20, 24) is connected to the bearing (14, 18, 22) of the folding element (13, 17, 21).

The jaw carriers (16, 20, 24) can have different shapes. The jaw carriers (16, 20) of the pre-hemming and intermediate hemming elements (13, 17) can be block-like. The jaw carrier (24) of the finished hemming element (21) has a curved shape which extends upwards from the mounting (22) located approximately at the level of the workpiece (5) and in an arc towards the workpiece (5). As a result of this design, the finished hemming element (21) can overlap the intermediate hemming element (17) in an arc from behind and from above and offers space for an in Figure 7 shown retraction position of the intermediate fold element (17). The folding elements (13, 17, 21) preferably have a common drive (25). They can be driven together and at the same time. The drive (25) can also be used to adjust the pivot / slide bearing (18).

The drive (25) has a drive means (26) which is connected to a suitable drive means (not shown), for example a controllable or regulatable motor, in particular an electric motor. In the exemplary embodiment shown, the propellant (26) is designed as a rotating drive shaft. The shaft axis is preferably aligned parallel to the axes of the bearings (18, 22). Alternatively, the propellant can be designed as a push rod or in any other suitable manner.

The hemming tool (2) also has a gear (28) for the drive transmission from the propellant (26) to the hemming elements (13, 17, 21). The gear (28) can also act on the pivot / slide bearing (18). The gear (28) is mounted and supported on the frame (12). The gear (28) can be designed in any suitable manner. In the exemplary embodiment, it is designed as a link mechanism.

The drive (25) also has a crank (29) connected to the propellant (26). This can be part of the transmission (28). In addition, in the exemplary embodiment shown, the drive (25) has a rotating cam (30) connected to the propellant (26). The connection is non-rotatable and is used to actuate the pivot / slide bearing (18).

The cam disk (30) is designed as a cam mounted eccentrically on the drive shaft (26). This has an arcuate section (31) which is concentric to the axis of rotation and is connected on both sides and is conical to the axis of rotation (26) tapered flank sections (32,33). The cam is rounded at the rear end diametrically opposite the arched section. Said sections (31,32,33) have rounded transitions. They are located on the outer circumference of the cam. The arc section (31) is wider than the rear cam end. Alternatively, the cam (30) can be designed in another suitable manner.

The cam disk (30) is operatively connected to the pivot / slide bearing (18). The connection is such that the intermediate fold element (17) executes a multi-axis pivoting movement to the fold (6) and then a retraction movement during the hemming process.

In the exemplary embodiment shown, this is implemented via the pivot lever (41), which on the one hand is pivotably connected to the folding element (17) via the joint (18 ') and on the other hand is coupled to the cam disk (30), e.g. via a roller (44). The pivot lever (41) is designed as an angle lever. It can have two lever arms (42, 43) of different lengths. The pivot lever (41) has a lever bearing (45) fixed to the frame. This is preferably located in the corner area or transition area between the lever arms (42, 43). The shorter lever arm (42) extends from the lever bearing (45) to the intermediate fold element (17), in particular to its jaw carrier (20), and the joint (18 ') there. The longer lever arm (43) extends from the lever bearing (45) to the roller (44) and to the cam disk (30).

The transmission (28), preferably the link mechanism shown, has several preferably jointly driven transmission groups (34, 40, 49). In the exemplary embodiment shown, these are three gear groups, each folding element (13, 17, 21) being assigned a gear group (34, 40, 49). One or more, preferably all gear groups (34, 40, 49) are designed as toggle mechanisms. They are connected to the rotationally driven crank (29) and generate high folding forces.

The mutual assignment of the transmission groups (34, 40, 49) and their connection with the crank (29) can be designed differently. They can each have their own crank connection, e.g. as with the gear group (34). In the exemplary embodiment shown, at least two transmission groups (40, 49) are directly coupled to one another. As a result, their movements are dependent on one another or coordinated with one another. The coupling preferably relates to the gear groups (40, 49) for intermediate and final hemming.

One gear group (34) for pre-hemming has a drive link (35) which is designed, for example, as a push rod. The drive link (35) is arranged horizontally and is articulated at one end to the crank (29) and at the other end is connected to two toggle levers (36, 38) via a hinge (39). The toggle levers (36, 38) act on the lower folding element (13), in particular the pre-folding element. You move it up and down according to the push rod position along the sliding bearing (14). The lower toggle lever (36) is rotatably mounted on a lever bearing (37) fixed to the frame. The upper toggle lever (38) is connected in an articulated manner to the folding element (13), in particular to its jaw support (16).

Another gear group (40), in particular for intermediate hemming, has a pull rod (46), a pivot lever (50) and a drive link (48), each of which is connected to one another at the end via a joint (47). The pull rod (46) is articulated at the other end to the crank (29). The drive link (48) is articulated at its other end to the folding element (17), in particular its jaw carrier (20). In the exemplary embodiment shown, the pivot lever (50) is designed as a wishbone. It has a lever bearing (51) fixed to the frame.

The third gear group (49), in particular for finishing hemming, has a drive link (52) and the said pivot lever (50), which are connected to one another in an articulated manner. The drive link (52) is articulated at the other end to the folding element (21), in particular its jaw carrier (24). The links (35,46,48,52) are preferably designed as straight and slender rods. The pivot lever (50) is common to both gear groups (40, 49) and couples them. The bearing (51) fixed to the frame, the joint (47) and the articulation point of the drive link (52) are spaced apart from one another and are each arranged at a corner area of the triangular lever (50).

The function and the sequence of movements of the hemming tool (2) are described below.

Figure 3 shows the starting position of the hemming tool (2) and its parts. The same position is also in Figure 1 shown. In Figure 3 the frame (12) is not shown for reasons of clarity.

From the starting position, the drive shaft (26) is rotated in the direction of rotation (27), with the crank (29) and the cam disk (30) being moved in a rotationally locked manner. This rotary movement has initially according to Figure 4 a retraction movement of the central and upper folding element (17, 21) and an infeed movement of the lower folding element (13) result. The crank (29) pushes the push rod (35) in the direction of the folding bed (4) and the workpiece (5), whereby the toggle levers (36,38) move from the initial bent position to the in Figure 4 Go shown stretched position and thereby the pre-hemming element (13) upwards push. As a result, the fold (6) is bent into the aforementioned first and upright intermediate layer (9). Figure 8 illustrates this position of the folding jaw (15) and the fold position (9).

During the aforementioned initial rotation of the drive shaft (26), the angle lever (41) with the roller (44) rests on a flank section (33). As a result of its rotation, the angle lever (41) is rotated counterclockwise about its bearing (45) fixed to the frame. On the other hand, the intermediate fold element (17) is rotated clockwise about its joint (18 ') on the angle lever (41) via the gear group (40). The two rotating or pivoting movements are superimposed with the result that the folding jaw (19) is removed from the fold (6) and tilted backwards.

The finished hemming element (21) is also pivoted clockwise backwards into said retracted position via its gear unit (49). If necessary, the finished hemming element (21) can also retain its initial position, the movements of the drive link (52) and the pivot lever (50) being neutralized.

Figure 5 shows a next rotational position of the drive (25) and the drive shaft (26). The toggle levers (36, 38) of the gear group (34) again assume a bent position which is directed opposite to the starting position. The pre-hemming element (13) is lowered again due to the bent position.

As the cam disc (30) continues to rotate, the roller (44) of the angle lever (41) reaches the concentric curved section (31). As a result, the angle lever (41) is supported and its in Figure 5 position shown. As a result, the joint (18 ') between the angle lever (41) and Fixed intermediate fold element (17). As a result of the previous pivoting movement of the angle lever (41), this joint (18 ') has been moved or shifted towards the fold (6) and assumes the maximum approximate position.

From the in Figure 5 The operating position shown of the hemming tool (2) is then followed by the intermediate hemming step, according to FIG Figure 6 The intermediate fold element (17) is pivoted away via the further drive rotation and presses with the folding jaw (19) against the fold (6) located in the upright fold position (9) and bends it into the inclined fold position or intermediate position (10). Figure 9 shows this fold and jaw position.

During the intermediate folding step, the angle lever (41) and the pivot / sliding bearing (18) are held stationary, whereby the intermediate folding element (17) in the said manner around the joint due to the action of the gear (40) with the pull rod (46) and the drive link (18 ') is pivoted. The links (46, 48) act as toggle levers. The pre-hemming element (13) has been lowered even further by its gear unit (34).

Figure 7 illustrates the final hemming step in which the intermediate hemming element (17) is removed from the hinge (6) and assumes a retracted position. For this purpose, the joint (18 ') has been removed from the workpiece (5) and moved back. As a result of the roller (44) now sliding on the other flank section (32), the angle lever (41) has been pivoted clockwise, whereby the gear group (40) also swings back the intermediate fold element (17) clockwise around the displaced joint (18 ') causes.

During the final hemming, the gear group (49) causes a pivoting movement of the final hemming element (21) about the bearing (22) counterclockwise into the hemming position shown. As Figure 10 shows, the folding jaw (23) bends the fold (6) from the intermediate position (10) into the end position (11). The folding jaw (23) can overlap the intermediate folding element (17).

The lower folding element (13) has the in Figure 6 shown bottom dead center of its shifting movement is exceeded and is again in the upward movement. The hemming jaw (15) is still positioned below the hinge (6). After a further rotation of the drive shaft (26), the folding elements (13,17,21) take the in Figure 1 and 3 starting position shown. The toggle levers (36, 38) can once again pass their extended position. In this starting position, all of the folding elements (13, 17, 21) are in their retracted position, so that the folded workpiece (5) is exposed and can be changed.

Modifications of the embodiments shown and described are possible in various ways. The gear (28) can be designed in a different way. It can have rolling parts, for example. The group formation and group subdivision of the gear parts can be different. The gear (28) can also have different kinematics. The same applies to the arrangement and function of the folding elements (13,17,21). The arrangement and kinematics of the bearings (14,18,22) are also variable. The number of folding elements and the folding steps can be greater than three. Instead of a common single drive (25), several drives and propellants (26) can be present, which are then each connected to only one or a few gear groups. Furthermore, the workpiece position can be different and, for example, have a vertical directional component. The aforementioned orientations of the hemming tool (2) and its parts then change accordingly.

Furthermore, the features of the above-described exemplary embodiments and modifications can be combined with one another as desired within the scope of the claims, in particular also interchanged.

REFERENCE LIST

1

Folding device

2

Hemming tool

3

Hold-down

4th

Workpiece support, rebate bed

5

workpiece

5 '

Workpiece part

6th

Fold

7th

Fold

8th

Fold position, initial position

9

Fold position, intermediate layer

10

Fold position, intermediate layer

11

Fold position, end position

12th

frame

13th

Folding element below, pre-folding element

14th

Storage, sliding bearing

15th

Rebate jaw

16

Jaw carrier, slide

17th

Central rebate element, intermediate rebate element

18th

Storage, swivel / slide bearing

18 '

Joint, joint connection, axis

19th

Rebate jaw

20th

Jaw carrier

21

Rebate element above, finished rebate element

22nd

Storage, swivel bearing fixed to the frame

23

Rebate jaw

24

Cheek support, curved

25th

drive

26th

Propellant, propellant shaft

27

Direction of rotation

28

Gearbox, handlebar gear

29

crank

30th

Cam, cam

31

Arch section

32

Flank section

33

Flank section

34

Gear group below, toggle gear

35

Drive link, push rod, pre-fold lever

36

Knee lever down

37

Lever bearing fixed to the frame

38

Knee lever up

39

joint

40

Gear group in the middle, toggle lever gear

41

Adjusting means, swivel levers, angle levers

42

Lever arm short

43

Lever arm long

44

Caster

45

Lever bearing fixed to the frame

46

Drawbar, knee lever

47

joint

48

Drive link, intermediate fold lever

49

Gear group above, toggle lever gear

50

Swivel lever, triangle lever

51

Lever bearing fixed to the frame

52

Drive link, ready-to-fold lever

α

Rebate angle

Claims (15)

1. Folding tool for the multi-stage bend folding of a workpiece (5), wherein the folding tool (2) has a plurality of driven folding elements (13, 17, 21), which can be fed to a common folding location (7), wherein the folding tool (2) has three or more folding elements (13, 17, 21) arranged one above the other, wherein a folding element (13) for preliminary folding executes a linear sliding movement and a folding element (17, 21) for intermediate folding and/or definitive folding executes a pivoting movement.
2. Folding tool according to Claim 1, characterized in that the folding tool (2) is provided and designed for a folding angle (α) of more than 100°, in particular 120° to 180°, preferably approximately 160°, wherein the folding elements (13, 17, 21) can be fed to the common folding location (7) one after the other in a number of folding steps.
3. Folding tool according to Claim 1 or 2, characterized in that the folding elements (13, 17, 21) have a common drive (25), in particular a sequencing drive.
4. Folding tool according to one of the preceding claims, characterized in that the folding tool (2) has a framework (12), on which the folding elements (13, 17, 21) are mounted in an independently movable manner, wherein a folding element (13) for preliminary folding has a sliding bearing (14) and a folding element (19) for intermediate folding has a pivot/sliding bearing (18) and a folding element (21) for definitive folding has a pivot bearing (22).
5. Folding tool according to one of the preceding claims, characterized in that the drive (25) a drive means (26), in particular a rotating drive shaft, and is connected to a transmission mechanism (28), in particular a control-arm mechanism, for drive transmission to the folding elements (13, 17, 21).
6. Folding tool according to Claim 5, characterized in that the drive (25) has a crank (29), which is connected to the drive means (26), and a rotating crank disc (30), which is connected to the drive means (26).
7. Folding tool according to Claim 6, characterized in that the crank disc (30) is designed in the form of an eccentrically mounted cam having a concentric curved portion (31) and conically tapering flank portions (32, 33), which adjoin the curved portion on both sides.
8. Folding tool according to one of Claims 5, 6 or 7, characterized in that the transmission mechanism (28), in particular the control-arm mechanism, has a plurality of, in particular three, transmission-mechanism groups (34, 40, 49) .
9. Folding tool according to Claim 8, characterized in that each folding element (13, 17, 21) is assigned a transmission-mechanism group (34, 40, 49).
10. Folding tool according to Claim 8 or 9, characterized in that a transmission-mechanism group (34, 40, 49) is designed in the form of a toggle-lever mechanism.
11. Folding tool according to Claim 10, characterized in that a transmission-mechanism group (34) has a driving control arm (35), in particular a pinch rod, which is connected in an articulated manner at one end to the crank (29) and at the other end to toggle levers (36, 38), wherein a transmission-mechanism group (40) has a pull rod (46), a pivot lever (50) and a driving control arm (48), which are connected to one another via an articulation (47), and wherein a transmission-mechanism group (49) has a driving control arm (52) and a pivot lever (50), which are connected to one another in an articulated manner, wherein the driving control arm (52) is connected in an articulated manner at the other end to the folding element (21).
12. Folding apparatus for the multi-stage bend folding of a workpiece (5), wherein the folding apparatus (1) has a workpiece support (4), in particular a folding bed, and a folding tool (2) with a plurality of driven folding elements (13, 17, 21), which can be fed to a common folding location (7), characterized in that the folding tool (2) is designed according to at least one of Claims 1 to 11.
13. Method for the multi-stage bend folding of a workpiece (5) by means of a folding tool (2) which has a plurality of driven folding elements (13, 17, 21), which are fed to a common folding location (7), wherein the folding tool (2) has three or more folding elements (13, 17, 21) arranged one above the other, wherein a folding element (13) for preliminary folding executes a linear sliding movement and a folding element (17, 21) for intermediate folding and/or definitive folding executes a pivoting movement.
14. Method according to Claim 13, characterized in that the folding elements (13, 17, 21) are fed to the common folding location (7) one after the other in three or more folding steps, wherein a common sequencing drive (25) moves the three or more folding elements (13, 17, 21), without collisions to the common folding location (7) in a defined movement sequence and removes them again in each case following their respective folding step.
15. Method according to Claims 13 or 14, characterized in that the folding process is carried out in a single set-up, wherein the folding tool (2) bends a fold (6) via a folding angle (α) of approximately 160° and more.

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