EP2279812A1 - Bending tool for a machine, in particular a wire or belt bending machine - Google Patents

Abstract

The tool has bending stamps (22b, 22c) comprising stamp elements (30b, 30c, 32b, 32c, 34b, 34c), which are connected together in a hinged force-transfer connection. The stamp elements are moved from a release position into a deformation position. The stamp elements are relatively rotated together around a stamp axis that is extended parallel to a bending axis of a bending core. The bending stamps comprise a stamp guiding element (38) that is concentrically arranged towards the stamps at a region of the stamp axis. The guide laments are accommodated in guide rails (36a, 36d).

Description

The present invention relates to a bending tool for a work machine, in particular wire or strip bending machine, for forming workpieces passing through the work machine, wherein the bending tool comprises at least one bending punch, which in the direction of a bending core of the bending tool in a forming position and away from this in a Release position is movable.

In such bending tools are used in known machines bending punch, which can be moved to the workpiece usually only linear. This purely linear movement of the punch leads, in particular in the case of strong deformations or large-dimensioned workpieces, to shear loads on the workpiece material, so that it is partially damaged during the forming process. The here discussed strong forming of a workpiece may be, for example, the manufacture of tubular sleeves made of strip material, wherein the workpiece to be formed has a thickness of several millimeters and is to be bent into sleeves with diameters of several centimeters. If such forming operations are carried out with linear bending dies, the forces required for forming can not be optimally transferred from the punch to the workpiece, so that the mentioned undesirable shear loads occur.

The object of the invention is to provide a bending tool for a work machine, in which an improved introduction of force from the punch to the workpiece is made possible to mitigate or prevent the above disadvantages.

To achieve this object, the invention proposes that the bending punch comprises a plurality of punch members, which are in force transmission connection with each other, that they are movable together from the release position to the forming position, wherein at least two punch members are hinged together, in particular rotatable relative to each other about a first Stamp rotation axis, which preferably extends substantially parallel to a bending axis of the bending core.

The multi-memberedness of the bending punch (s) in a bending tool according to the invention makes it possible for the bending punch to be movable relative to the workpiece to be reshaped or at least one punch member of the bending punch to be movable relative to the workpiece. This relative movement of the punch members, made possible by the articulated power transmission connection, superimposes the generally rectilinear and linear feed movement of the punch in the direction of the workpiece. As a result of this superimposition of several movements, other force introduction points or regions on the workpiece are made possible, and the force applied by the bending punch can be better transmitted to the workpiece to be machined.

It is proposed that the bending punch has a first punch member and a second punch member hingedly connected thereto, wherein the first punch member is coupled to a punch drive, and wherein the first punch member is preferably received linearly movable in a punch guide.

The first punch member therefore represents the connecting piece to an arbitrarily designed stamp drive, which can be designed, for example, as an eccentric drive, linear drive or the like. The first punch member is preferably received in a linear punch guide, so that is made possible by the punch guide a kind of linear basic movement of the punch from the release position into the forming position and back.

Further, it is proposed that the second punch member is designed such that at its end remote from the first punch member, a third punch member is attached or attached, wherein the third punch member is rotatable relative to the second punch member about a second punch axis and / or together with the second punch member is rotatable about the first punch axis relative to the first punch member, wherein the two punch axes are substantially parallel to each other.

Due to the articulated mounting of the third punch member on the second punch member are the possibilities of how the punch with the workpiece during the forming process in contact for the purpose of power transmission, further expanded. In particular, such an articulated connection of the third punch member to the second punch member allows the third punch member to be pivoted relative to the direction of basic movement (linear motion) such that the third punch member performs a combined movement during forming, in particular a linear basic motion and a pivotal motion superimposed thereon ,

Preferably, the bending punch in the region of the second punch axis in particular concentric with this arranged stamp guide elements, which are accommodated in respective slotted guides, which are formed in a base plate and a cover plate of the bending tool between which the bending punch is arranged. The proposed slotted guides can be straight or curved, in particular circular arc-shaped.

The punch guide elements are preferably constructed in the manner of a sliding bearing, with the second and the third punch members being connected to one another in an articulated manner between two punch guide elements received in respective slotted guides. Such a punch guide in the region of the joint between the second and third punch member makes it possible that this joint superimposed a desired, possibly the linear basic movement Movement performs. In the case of a linear guide slot this can coincide with the linear basic movement direction of the punch. Alternatively, the slide guides can be curved, so that the bending punch, in particular the second and the third punch member, can be pivoted together about the first punch axis in the articulated connection between the first and second punch member. Such a curved, in particular arc-shaped link guide allows a further degree of freedom in the feed movement of the punch during the forming process. In particular, the position of the punch can be influenced relative to the workpiece in order to create the best possible force introduction conditions during the forming process.

The third punch member is preferably the one which comes into direct contact with the workpiece to be formed. For this purpose, it is proposed that the third punch member has a forming contour facing the bending core in the forming position, which is in contact with the workpiece during forming, such that the workpiece lies between the forming contour of the punch member and the bending core. As usual with such bending tools, the punch member coming into contact with the workpiece and the bending core have complementary contours in order to be able to produce the desired forming on the workpiece.

Preferably, the third punch member on the second punch member facing stop surfaces, which are in contact with corresponding stop surfaces on the second punch member can be brought or stand, such that the relative rotational or pivotal movement between the third and the second punch member is limited or limited. The abutment surfaces of the third punch member are preferably formed on the side facing away from the forming contour of the third punch member.

For this purpose, it is further proposed that the third punch member during the Movement of the punch from the release position into the forming position from its stop position on the second punch member is pivotable about the second punch axis. In this case, the abutment surfaces of the second and the third punch member may be advantageously formed such that the third punch member by about 25 ° to 50 °, preferably about 30 ° to 45 ° relative to the direction of movement of the punch is pivotable. the direction of movement is considered in this case as a linear basic movement direction of the punch toward the workpiece or away from it (movement of the punch from the release position to the forming position and back).

The pivotal movement of the third punch member is preferably carried out by its support on the workpiece and by the support of the punch guide elements in the above-mentioned slotted guides. As already mentioned above, the punch guide elements are incorporated in link guides and the joint between the second and the third punch member is supported on these stamp guide elements on the bending tool, in particular its base plate and cover. In such a configuration, the pivotal movement of the third punch member is thus passive due to the articulated connection with the second punch member, the support of the punch guide elements in the slide guides and the support of the third punch member on the workpiece to be formed.

It is also proposed that the third punch member during movement of the punch moves from the forming position to the release position in its stop position on the second punch member automatically back, especially under gravity and / or under a biasing force acting in the direction of the stop position. The automatic pivoting back of the third punch member in its stop position makes it possible that the bending punch, starting from the release position always equal attacks on a workpiece to be machined or reshaped. An acting in the stop position bias can in particular of Be advantageous if the pivoting of the third punch member should be done as quickly as possible in its stop position.

The third punch member is preferably designed such that it rests against at least two different contact areas of the workpiece during the forming, in particular at the beginning of the forming operation, such that forces exerted by the bending punch are exerted on the contact areas. Such a configuration of the third punch member allows dividing the forces applied by the second and the first punch member on two contact areas on the workpiece, so that no extremely high loads occur at these contact areas at the beginning of the forming process. This leads to improved thrust loads on the workpiece, so that no material damage occurs.

As an alternative to the pivotable attachment of the third punch member on the second punch member, it is proposed that the stop surfaces are designed such that the second and third punch members are positively and firmly connected to one another in such a way that they are pivotable together about the first punch axis. In such an embodiment, a positive engagement of the second and the third punch element is effected by the stop surfaces, so that a pivoting of the third punch element relative to the second punch element is no longer possible. It is also conceivable that the stop surfaces are formed such that pivoting in one direction is possible, but the pivoting in the opposite direction is limited or prevented.

The bending core preferably has the shape of a circular cylinder, and further the bending tool may comprise a plurality of bending punches, preferably four bending punches, which are distributed uniformly in the circumferential direction around the bending core, such that they are in a substantially radial direction to the bending core or the bending axis are movable. In such an arrangement thus the basic movement of the punch takes place (Linear movement) of the release position in the forming position and back in the radial direction, based on the circular cylindrical bending core or the associated bending axis. The evenly distributed over the circumference arranged bending punch allow the partial deformation of the workpiece, preferably two adjacent bending punch bend the workpiece first by about half the circumference of the bending core and then press two opposing punch the workpiece on the other peripheral side of the cylinder against this to a plate-like trained workpiece to form a hollow cylinder or a sleeve can. The two ends of the workpiece to be joined together may possibly be pre-bent in a separate step, so that when bending along the bending core the connection of the two free ends of the workpiece takes place substantially tangentially to the bending core. The free ends of the workpiece are preferably connected to one another via a clinch connection.

Fig. 1

zeigt eine schematische Vorderansicht einer Biegemaschine mit einer Ausführungsform eines erfindungsgemäßen Biege- werkzeugs.

Fig. 2

zeigt eine perspektivische Teildarstellung des Biegewerk- zeugs von schräg vorne.

Fig. 3

zeigt eine Querschnittsdarstellung durch die Biegemaschine entsprechend der Linie III-III der Fig. 1.

Fig. 4

zeigt in den Teilfiguren a) bis c) den Biegevorgang mit einem gelenkigen Biegestempel.

Fig. 5

zeigt in den Teilfiguren a) und b) die Fortsetzung des Biege- vorgangs der Fig. 4.

Fig. 6

zeigt schematisch eine Ausführungsform des Biegewerk- zeugs mit geradlinigen und gekrümmten Kulissenführungen für die Biegestempel, wobei das umzuformende Werkstück zuerst von oben umgebogen wird.

Fig. 7

zeigt eine alternative Anordnung der Biegestempel, um ein Werkstück zuerst von unten umzubiegen.

The invention will be described by way of example with reference to the accompanying drawings, by way of non-limiting example.

Fig. 1

shows a schematic front view of a bending machine with an embodiment of a bending tool according to the invention.

Fig. 2

shows a partial perspective view of the bending tool obliquely from the front.

Fig. 3

shows a cross-sectional view through the bending machine according to the line III-III of Fig. 1 ,

Fig. 4

shows in the partial figures a) to c) the bending process with an articulated bending punch.

Fig. 5

shows in the subfigures a) and b) the continuation of the bending process of Fig. 4 ,

Fig. 6

schematically shows an embodiment of the bending tool with straight and curved slide guides for the punch, wherein the workpiece to be formed is first bent from above.

Fig. 7

shows an alternative arrangement of the punch to first bend a workpiece from below.

Fig. 1 shows a work machine 10, which is set up as a bending machine for the production of sleeves. It concerns with the Fig. 1 to a simplified schematic view of a front side A of the bending machine 10. The bending machine comprises a supported on a substrate U wall-like base body 12, on which a serving for machining workpieces bending tool 14 (also referred to as bending station) is mounted. From the illustration it can be seen that 12 openings 16 are recessed on the base body, through which the view of an indicated central drive wheel 18 is released. Drive devices 20a to 20d for bending punches 22a to 22d of the bending tool 14 can be coupled to this drive wheel 18. The bending punches 22a to 22d shown here are movable relative to a bending axis BA substantially in the radial direction towards a bending core 24 and away from it. The bending tool 14 further comprises a base plate 12 attached to the base plate 26 and a cover plate, not shown here, which is attachable to the bending tool 14 that the bending punch 22 a to 22 d between it and the base plate 26 are received.

The bending core platinum-like workpieces in different flow levels DE-1 and DE-2 along the body 12 can be supplied. When workpieces are fed in the DE-1 pass plane, they are first picked up by the upper bending dies 22a and 22b around the bending core 24 bent and then the finished forming by actuation of the punch 22c and 22d. In the case of the introduction of workpieces on the continuous plane DE-2, first the bending punch 22c and 22d upwardly deform the workpiece, and then the workpiece is brought into the cylindrical final shape by the punching punches 22a, 22b deliverable from above. In the region 28 of the bending machine 10, a press can be attached to form from an endless strip material to be formed platinum-like workpieces. Alternatively, such workpieces can also be fed directly from a kind of magazine device, so that no press is required on the bending machine 10. As usual with such machines, it also has an associated, not shown here indentation in the case of punching of workpieces of endless material. With regard to different material sources, reference is made to the simultaneously filed patent application entitled "Working machine, in particular wire or strip bending machine", whose content is incorporated herein by reference.

Fig. 2 shows a schematic, partial perspective view of the bending tool 14, wherein the base plate 26 and the bending punch 22b and 22c are shown as essential components. The bending punches 22a to 22d comprise, in the direction of the bending axis BA, a first punch member 30, a second punch member 32 and a third punch member 34. These three punch members are shown in FIG Fig. 2 for the bending dies 22b and 22c. The first punch member 30b, c is pivotally connected to the second punch member 32b, c, such that these two punch members 30b, c and 32b, c are pivotable relative to each other about a first punch axis S1. The third punch member 34b, c is also hinged to the second punch member 32b, c and, depending on the configuration of the third punch member 34b, c relative to the second punch member 32b, c are pivoted about a second punch axis S2. Referring to the Fig. 2 the bending punch 22b has a second punch member 32b and a third punch member 34b which are pivotable relative to each other about the punch axis S2b. This here in the Fig. 2 For the bending punch 22b and 22c what is said applies, of course also for those in the Fig. 1 shown bending punch 22a and 22d. The first punch members 30a to 30d are connected to the respective punch driver 20a to 20d, and the first punch members 30a to 30d are linearly guided in the radial direction with respect to the bending axis B. Thus, by these first punch members 30a to 30d, a linear basic movement for moving the bending punch 22a to 22d into a forming position and back to a releasing position is generated. Of course, to generate this linear basic movement, the rotational movement generated by the central drive 18 must be correspondingly translated in the respective punch drives 20a to 20d. However, this movement translation will not be discussed in detail here.

From the Fig. 2 is also seen that in the base plate 26 slide guides 36 are provided, of which only the slotted guides 36a and 36d can be seen. In this slide guides 36 stamp guide elements 38 are added, which are in communication with the second punch axis S2 forming swivel joint. Such slotted guides are also formed on the cover plate of the bending tool, not shown, so that the bending punch 22a to 22d guided and supported both by slotted guides 36 in the base plate 26 and by slide guides in the cover plate.

The base plate has an opening 40 in a central area, through which workpieces to be formed can also be supplied to the bending tool 14 from a transverse direction Q orthogonal to the base body 12. In particular, workpieces can be supplied from a rear side of the main body 12 through the opening 40 and subsequently be deformed by the bending punches 22a to 22d. For the transport of workpieces in the transverse direction Q, a transverse transport device 42 is provided, which is the subject of a simultaneously filed with the present application, the Applicant's patent application entitled "work machine with cross-transport device and method for producing a sleeve using the working machine". The content of this patent application with respect the embodiment of the transverse transport device is incorporated by reference in the present application.

Fig. 3 shows a cross-sectional view along the section line III-III of Fig. 1 , From this illustration, the base body 12 can be seen with its front side A and its rear side B. On the front side A, the bending tool 14 with its base plate 26 is attached. In the main body 12, a passage opening 44 is recessed, through which extends the previously mentioned transverse transport device 42. The transverse transport device 42 is supported on the back B via a protruding flange 46. On the front side A, the transverse transport device 42 has a support element 48, which is received in a recess 50 formed in the base plate 26. In the axial extension of the transverse direction Q, the bending core 24 is attached to the transverse transport device 42. Thus, in the bending process, the bending forces acting on the bending core, the support element 48 and the base plate 26 on the main body 12 of the bending machine are first supported from above in this embodiment. In the present embodiment, workpieces are fed to the bending tool 14 in the transverse direction pass plane DE-1 q above a transport rail 52 belonging to the transverse transport device 42. The transverse transport device 42 is designed such that, relative to the transverse axis Q, it can also be installed turned by 180 ° into the bending machine so that the support element 48 is directed upwards in the recess 50 of the base plate 26. In such a case, workpieces are fed in the continuous plane DE-2q below the transport rail 52 and lie below the bending core 24. The first forming step consists in such a case in a bending from below, so by the bending punch 22c and 22d, the then acting Forces are supported on the above-arranged support member 48 in the same manner as in the Fig. 3 for the opposite case. The transverse transport device 42 is assembled by the support member 48 and by the attachment of the bending core 24 on the transverse transport device 42 with the bending tool 14 to a kind of unit, which optimally also the feeding of pre-bent workpieces in the transverse direction Q allows. Further details on the transverse transport device and on a production method for sleeves can be found in the patent application "Working machine with transverse transport device and method for producing a sleeve using the working machine" already mentioned above.

The Fig. 4 and 5 show in their respective subfigures the bending process on the example of the punch 22b with the articulated third punch member 34b. A workpiece 54 fed to the bending tool is first fixed to the bending core 24 by means of a merely indicated holding device 56 coming from vertically above. Subsequently, the bending punch 22a, 22b are moved in the radial direction with respect to the bending axis BA to the bending core 24. The third punch member 34b is in the release position of the punch 22b in a stop position on the second punch member 32b, as shown in Fig. 4a ) can be seen. The stop position of the third punch member 34b on the second punch member 32b depends, in particular, on the configuration of the associated stop faces 58 or 60 on the two punch members 34b and 32b.

As already with reference to the Fig. 2 explained, the joint between the second punch member 32b and the third punch member 34b is guided via punch guide elements 38 in a slotted guide 36b. This slotted guide is in examples of Fig. 4 executed in a straight line.

When a workpiece 54 has been inserted into the bending tool, the force K acting on the third punch member 34b in the radial direction by the first punch member 30b and the second punch member 32b is split and transmitted to two contact portions KB1 and KB2 on the workpiece, respectively. These contact areas KB1 and KB2 arise in particular in that the third punch member 34b has a contour 62 facing the workpiece, which corresponds approximately to a quarter circle arc. Of course, other contours 62 may be provided. The contact area KB1 is due to the articulated connection of the third punch member 34b and whose pivotability about the second punch axis S2b is very far away from the bending axis or very far from the tangential bearing region 64 of the workpiece 54 at the bending core 24. The lever effect is correspondingly large, so that the workpiece 54 can be bent over with relatively little force, avoiding high and possibly material-damaging shear loads.

Upon further advancement of the bending punch 22b in the radial direction to the bending core 24, the third punch member 34b is continuously supported with its contact projections 66 and 68 on the workpiece 54. The workpiece 54 is thereby continuously bent around the bending core 24, wherein the contact projections 66, 68 are displaced along the workpiece 54 due to the radial feed movement and the superimposed pivoting movement of the third punch member 34b ( Fig. 4b) and 4c )). In the state of Fig. 4c ) or the Fig. 5a ), the contact projection 68 is already on the workpiece so that it is held between the contact projection 68 and the bending core 24. At the latest in the condition according to Fig. 5a ) can be in Fig. 4a ) illustrated holding device 56 are moved upward, since the workpiece 54 is now held on the bending core by means of the bending punch 22a, 22b. At the end of the bending process ( Fig. 5b )), the third punch member 34b is located over its entire surface with its inner contour 62 on the workpiece 54, such that the workpiece 54 is received and held between the outer circumference of the bending core 24 and the inner contour 62. In this situation, the force K acts on the entire surface of the workpiece 54. The in the Fig. 4a) to 4c ) and 5a), 5b) illustrated pivoting of the third punch member 34b is a passive movement due to the support of the punch member 34b on the workpiece and the guidance of the hinge connection in the slotted guide 36b. When the bending punch 22b of the in Fig. 5 shown forming position back into the in Fig. 4a is moved, the third punch member 34b pivoted under gravity automatically back into the stop position in which the corresponding stop surfaces 58 and 60 of the third punch member 34b and the second punch member 32b are in contact with each other. This automatic, gravitational Provision of the third punch member 34b may optionally also be assisted by a spring bias (torsion spring or the like).

The in the Fig. 4 and 5 for the bending punch 22b described sequence results for each bending punch, which has such a hinged third punch member 34e, so for example also for the punch 22a.

The movement performed by the two bending punches 22a and 22b during the forming process of the workpiece 54 can also be compared with a manual forming of a plate-like object by a human with both his hands. The third punch members 34a and 34b with the respective contact projections 66, 68 assume the function of hands and fingers (in particular spread thumb and forefinger), this hand via the hinge connection (wrist) with the second punch member 32b (Unteram) is connected. The forearm is then connected via a kind of elbow joint to the linearly movable upper arm and the first punch member 30a and 30b.

Fig. 6 shows for the lower bending punch 22c and 22d the possibility of a curved link guide 136c and 136d in contrast to a in Fig. 2 apparent linear slide guide 36d. In the case of the punch dies 22c and 22d, the third punch member 34c or 34d is designed such that it is not pivotable relative to the second punch member 32c or 32d, since the abutment surfaces between the second and third punch members do not permit such a pivoting movement. The inherent hinge connection is thus stiffened by design of the abutment surfaces. This shows that the possibilities of pivotal movement of the third punch member relative to the second punch member can be made very variable by corresponding shaping of the corresponding stop surfaces on the second and third punch members. Due to the arcuate slotted guide 136c and 136d, the second and third ram members 32c, 32d and 34c, 34d become common about the first one Stamp axis S1c or S1d pivoted. This pivoting movement is superimposed on the basic movement of the bending punch 22c, 22d which extends linearly in the radial direction and also serves to bring the third punch member, which comes into contact with the workpiece, into an optimum position for the forming operation. Of course, the shape of the slide guide and the embodiment of the pivotability of the third punch members relative to the second punch members can be combined with each other. Thus, it is quite conceivable that in the bending dies 22a and 22b differently shaped link guides are provided as the rectilinear link guides shown here.

Fig. 7 shows a bending tool 14, in which the workpiece 54 is first bent from the bottom of the punch 24 upwards. In this case, the bending dies 22c and 22d have the pivotable third punch members 34c and 34d.

In this context, it should be noted that the third punch members are removable from the second punch members, so that depending on Umformrichtung (from bottom to top or from top to bottom relative to the punch) or depending on umzuformendem workpiece differently configured third punch members are attached can. The bending tool according to the Fig. 1 to 5 Thus, by simply replacing the third punch members 34a and 34b downward and by changing the third punch members 34c and 34d upward in a bending tool according to FIG Fig. 7 be rebuilt. For this purpose, only the cover plate of the bending tool must be removed and the third punch members can be removed along the punch axis S2 of the second punch members and replaced.

Claims (15)

Bending tool for a work machine, in particular wire or strip bending machine, for forming workpieces (54) passing through the work machine, the bending tool (14) comprising at least one bending punch (22a-d) which is directed towards a bending core (24) of the bending tool (14) is movable into a forming position and away from it into a release position,
characterized in that the bending punch (22a-d) comprises a plurality of punch members (30, 32, 34) in force-transmitting connection with each other so as to be movable together from the release position to the forming position, at least two punch members (30, 32, 34) are hinged together, in particular are relatively rotatable about a first punch rotational axis (S1), which preferably extends substantially parallel to a bending axis (B) of the bending core (24). Bending tool according to claim 1, characterized in that the bending punch (22a-d) has a first punch member (30a-d) and a second punch member (32a-d) hingedly connected thereto, the first punch member (30a-d) having a punch drive (20a-d) is coupled, wherein the first punch member (30a-d) is preferably received linearly movable in a punch guide. Bending tool according to claim 2, characterized in that the second punch member (32a-d) is designed such that at its from the first punch member (30a-d) remote end, a third punch member (34a-d) is attachable or attached, wherein the third Punch member (34a-d) relative to the second punch member (32a-d) about a second punch axis (S2) is rotatable and / or together with the second punch member (32a-d) about the first punch axis (S1) relative to the first punch member (30a -d) is rotatable, the two Stamp axes (S1, S2) are substantially parallel to each other. Bending tool according to claim 3, characterized in that the bending punch (22a-d) in the region of the second punch axis (S2) has in particular concentrically arranged thereon punch guide elements (38) which are received in respective slotted guides (36a-d; 136c, d) which are formed in a base plate (26) and a cover plate of the bending tool (14), between which the bending punch (22a-d) is arranged. Bending tool according to claim 4, characterized in that the slotted guides are rectilinear (36a, d) or curved (36c, d), in particular circular arc-shaped. Bending tool according to one of claims 3 to 5, characterized in that the third punch member (34a-d) in the forming position the bending core (24) facing forming surface (62) which is in the forming of the workpiece (54) in contact therewith such that the workpiece (54) lies between the forming surface (62) and the bending core (24). Comprises bending tool according to one of claims 3 to 6, characterized in that the third punch member (34a-d) to the second stamping member (32a-d) facing stop surfaces (58) which (in contact with the corresponding stop surfaces (60) on the second stamping member 32a -d) can be brought or stand, such that the relative rotational movement between the third and the second punch member is limited or limited. Bending tool according to claim 7, characterized in that the third punch member (34a, b) during the movement of the bending punch (22a, b) from the release position to the forming position its stop position on the second punch member (32a, b) about the second punch axis (52a, b) is pivotable. Bending tool according to claim 8, characterized in that the abutment surfaces (58, 60) of the second and the third punch member are formed such that the third punch member (34 a, b) by about 25 ° to 50 °, preferably about 30 ° to 45 ° is pivotable relative to the direction of movement of the punch. Bending tool according to claim 8 or 9, characterized in that the pivoting movement of the third punch member (34a, b) is caused by its support on the workpiece (54) and by the support of the punch guide elements (38) in the slide guides (36). Bending tool according to one of claims 8 to 10, characterized in that the third punch member (34a, b) when moving the punch (22a, b) of the forming position in the release position in its stop position on the second punch member (32a, b) pivoted back automatically , in particular under the action of gravity or / and under a biasing force acting in the direction of the stop position. Bending tool according to one of claims 8 to 11, characterized in that the third punch member (34a, b) is formed such that it during the forming, in particular at the beginning of forming at least two different contact areas (KB1, KB2) of the workpiece (54 ) is applied, such that forces exerted by the bending punch (22a, d) are exerted on the contact areas (KB1, KB2). Bending tool according to claim 7, characterized in that the stop surfaces (58, 60) are formed such that the second and the third punch member (32c, d; 34c, d) are positively and firmly connected to each other such that they are pivotable together about the first punch axis (S1c, d). Bending tool according to one of the preceding claims, characterized in that the bending core (24) has the shape of a circular cylinder and in that a plurality of bending punches (22a-d), preferably four bending punches, are distributed uniformly in the circumferential direction around the bending core, such that they are in essentially radial direction to the bending core (24) are movable. Work machine, in particular wire or strip bending machine, for machining, in particular forming, of continuous workpieces (54), with a wall base (12) standing on a substrate (U) and having a front and a rear machining side (A, B) characterized in that it further comprises at least one bending tool (14) according to one of claims 1 to 14, wherein preferably the bending tool (14) is attachable or attached to the front or the rear machining side (B), preferably workpieces (54) the bending tool (14) along the bending axis (B) and / or along the base body (12) are fed.

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