METHOD FOR PRODUCING A BENDED PART AND BENDING MACHINE FOR CARRYING OUT THE METHOD

Description

FIELD OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a method for producing a bent part according to the preamble of claim 1 and to a bending machine designed to carry out the method according to the preamble of claim 5. A preferred field of application is the bending of workpieces with a rectangular cross-section.

[0002] In the automated production of two- or multi-dimensionally bent parts using numerically controlled bending machines, the movements of machine axes of a bending machine are controlled in a coordinated manner using a control device in order to produce one or more permanent bends on the workpiece, e.g. a bar, a tube or a wire, by plastic forming.

[0003] In an automated bending process of the type considered in this application, the workpiece is formed using a bending machine comprising a bending head with a bending die and a bending arm rotatable about the bending die. The bending arm has a clamping device for clamping an end portion of the workpiece against a peripheral portion or outer contour of the bending die. The bending arm is rotatable about a bending axis by means of a bending drive controlled by the control device.

[0004] The bending machine further comprises a counterholder device which can be brought into engagement with a feed-side section of the workpiece for the bending operation in order to stabilize the orientation of the longitudinal axis of the feed-side section during a bending operation by absorbing transverse forces.

[0005] During the bending process, a section of the workpiece to be formed is first brought into a starting position within the engagement area of ​​the bending head. If prefabricated, already cut-to-length workpieces are to be bent, they can be inserted into the bending machine. It is also possible to move a piece of a suitable length from a longer workpiece stock into the starting position using a feed operation.

[0006] The clamping device is then brought into contact with the end section to clamp the end section against a peripheral portion of the bending die and secure it to the bending die. The end section can be fixed between a clamping jaw of the clamping device and the bending die.

[0007] At the same time or at a different time, the counterholder device is brought into engagement with a feed-side section of the workpiece in order to stabilize the alignment of the longitudinal axis of the feed-side section during a bending operation.

[0008] Then, in a bending operation, a bend is created between the feed-side section, which is stabilized against transverse forces by the counter-holder device, and the end section by rotating the bending arm around the bending axis. Through the synchronous rotation of the bending die and the clamping device around the bending axis, the workpiece is "pulled" around the bending die or a peripheral section of it. The outer contour of the bending die can stabilize the inner contour of the bend and precisely define its radius. The rear, straight leg of the workpiece, i.e., the feed-side section, is supported by the counter-holder device, which acts as a counterbearing and absorbs the transverse forces resulting from the bend. It thus ideally remains aligned parallel to a feed direction. The feed direction is the direction in which material is fed or pulled toward the bending die during bending.

[0009] Ideally, a flat bend is created in which the legs before and after the bend, formed by the end section with a changed orientation and the feed-side section with its unchanged orientation, lie in a common plane. The relative orientation of the end section to the feed-side section is usually described by the bend angle.

[0010] These characteristics are typical of the "rotary draw bending" process. Rotary draw bending is a widely used and precise bending process, especially for pipes with a small bending ratio (bending radius / pipe diameter) and a high wall thickness factor (pipe diameter / wall thickness).

[0011] US 2005 / 126245 A1 discloses a method for producing a bent part according to the preamble of claim 1 and a bending machine according to the preamble of claim 5. Other similar bending machines and methods are known from US 4 757 702 A and JP 2010 188406 A. TASK AND SOLUTION

[0012] It is an object of the invention to further develop a generic method and a generic bending machine in such a way that bent parts with improved bending geometry can be produced.

[0013] To achieve this object, the invention provides a method having the features of claim 1 and a bending machine having the features of claim 5. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated into the description by reference.

[0014] In a method according to the claimed invention, the counterholder device engages the feed-side section of the workpiece. The engagement or engagement of the counterholder device on the workpiece occurs in such a way that a torsional moment is introduced into the workpiece by means of the counterholder device and / or that a torsional moment can be absorbed. The counterholder device and / or the bending head is then rotated at least in phases about an axis of rotation before, during and / or after the rotation of the bending arm. The bending arm is rotated about its bending axis during its rotation. The axis of rotation of the counterholder device and / or the bending head runs parallel to the longitudinal direction of the feed-side section. The rotation of the counterholder device and / or the bending head occurs in such a way that a twisted section is created in an area between the counterholder device and the bending mold arranged behind it.The twisted section is also referred to as the twisted section. The relative rotation between the counterholder device and the bending head, i.e., the rotation of the counterholder device and / or the bending head, which leads to the creation of the twisted section, only begins after the end section has been clamped between the bending die and the clamping device, so that the end section can no longer twist.

[0015] In addition to the planar bending around the bending axis, a further forming operation is performed, namely a torsion of the workpiece in an area between the bending die and the counterholder device. The workpiece is held in place on one side (at the end section) by the fixation between the bending die and the clamping device and on the other side by the counterholder device, which acts on the feed-side section in such a way that a torsion-generating torque can be introduced into the workpiece and / or that a torsional moment generated by rotation of the bending die around the rotation axis can be absorbed. This makes it possible to create a permanent deformation in the form of a twisted or twisted section near a bend. The bend and the twisted section can merge directly into one another.

[0016] The decisive factor for creating the twisted section is a relative rotation between the bending head and the counterholder device about the axis of rotation, which runs parallel to the longitudinal direction of the feed-side section. The relative rotation can be created in different ways. It is possible for only the counterholder device to be rotated, while no rotation about the axis of rotation takes place at the bending head. It is also possible for the counterholder device to remain stationary during the creation of the twisted section and only the bending head is rotated about the axis of rotation. It is also possible for both the counterholder device and the bending head to be rotated about the axis of rotation to create the relative rotation. The two rotations, which usually run in opposite directions to each other, can be created synchronously or at different times.

[0017] This new functionality can be realized on the bending machine according to the claimed invention in that the counterholder device is designed to introduce and / or absorb a torsional moment on the feed-side section and in that the counterholder device and / or the bending head can be rotated about an axis of rotation running parallel to a feed direction of a workpiece by means of a rotary drive controllable by the control device. The control device of the bending machine is configured or configurable to rotate the counterholder device and / or the bending head at least in phases about an axis of rotation running parallel to the longitudinal direction of the feed-side section before, during and / or after a rotation of the bending arm about the bending axis in such a way that a permanent deformation in the form of a twisted ortwisted section can be generated. The torsional moment can be transmitted from the counterholder device to the workpiece and / or absorbed by it through positive locking and / or frictional locking. The control device is configurable to carry out the method if it can provide an operating mode in which a simultaneous coordinated rotation of the bending arm and the counterholder device and / or the bending head takes place at least in phases.

[0018] There are different ways to coordinate the rotation of the counterholder device and / or the bending head leading to torsion with the generation of the bend by rotating the bending die.

[0019] In one variant, the torsional moment is first introduced by rotating the counterholder device, before the bending arm is subsequently rotated around the bending axis. The rotation of the counterholder device can be fully completed before the rotation of the bending die begins, so that these two operations occur staggered in time. With this variant, particularly strong twists or torsions can be generated in the workpiece if necessary.

[0020] It is also possible to coordinate the movements in such a way that the introduction of the torsional moment (by rotation of the counter-holder device) takes place in phases or completely simultaneously or synchronously with the rotation of the bending arm, so that these operations overlap in time.

[0021] It is also possible to first generate the bending by rotating the bending arm or the bending form and then introduce the torsional moment.

[0022] Other variants are also possible. For example, it is possible to start rotating the counter-holder device first and then initiate rotating the bending arm at a different time, before the counter-holder device has reached its desired final rotational position. In this case, the initiation of the torsional moment (by rotating the counter-holder device) and the generation of bending (by rotating the bending arm) are at least partially synchronous. It would also be possible to start bending first (by starting to rotate the bending arm) and then initiate rotating the counter-holder device at a different time, before the bending arm has reached its final position. In this case, too, the initiation of the torsional moment (by rotating the counter-holder device) and the generation of bending (by rotating the bending arm) are at least partially synchronous.

[0023] In the above variants, rotation of the bending head around the axis parallel to the feed-side section is neither necessary nor intended. These variants can be performed with bending machines whose bending head cannot rotate around the aforementioned axis.

[0024] Analogous variants can be used if the bending machine has a bending head that can be rotated in a controlled manner around the rotation axis running parallel to the feed-side section.

[0025] In one variant, the torsional moment is first introduced by rotating the bending head, before the bending arm is subsequently rotated around the bending axis. The rotation of the bending head can be fully completed before the rotation of the bending die begins, so that these two operations occur staggered in time. It is also possible to coordinate the movements so that the introduction of the torsional moment (by rotating the bending head) occurs in phases or completely simultaneously or synchronously with the rotation of the bending arm, so that these operations overlap in time.

[0026] It is also possible to first generate the bend by rotating the bending arm or bending die and then introduce the torsional moment by rotating the bending head around the rotation axis running parallel to the feed-side section. It is also possible to start rotating the bending head first and then initiate rotating the bending arm at a later time, before the bending head has reached its desired final rotation position.

[0027] This process can positively influence the bending geometry of the finished bent part, as an additional degree of freedom for material forming is created in the immediate vicinity of a bend or overlapping with a bend. This can be used to correct the bending geometry to precisely match the actual geometry to the desired target geometry. Even very complex, and possibly even completely new, bending geometries can be realized—i.e., bending geometries that were previously impossible to produce using pure bending processes.

[0028] Round material, i.e., workpieces with a circular cross-section, can be processed. Particular advantages arise when processing profile material, which here refers to workpieces with a non-circular cross-section, such as oval wire or wire or tube with a rectangular cross-section.

[0029] According to a further development, the bent part is produced from an elongated workpiece with a rectangular cross-section. The bending machine is accordingly designed to produce a bent part from an elongated workpiece with a rectangular cross-section. The workpiece is therefore profile material which, in the unbent state, has four essentially flat side surfaces that extend parallel to the longitudinal direction of the workpiece, with the side surfaces adjacent in the circumferential direction each being essentially at a right angle to one another. A rounding can be provided on the edges in between. The workpiece can have an essentially square cross-section in which all four side surfaces are essentially the same width.It is also possible for the workpiece to have two opposing broad sides and two opposing narrow sides of smaller width, arranged perpendicular to the broad sides. For example, it could be flat material, such as that used for the production of electrically conductive conductor sections with a special bending geometry.

[0030] For processing workpieces with a rectangular cross-section, the counterholder device is preferably designed to have a guide for the workpiece that is adapted to the rectangular cross-section of the workpiece in such a way that the guide guides the feed-side section of the workpiece along at least two opposite side surfaces when the counterholder device is engaged with the workpiece. In some cases, engagement with only one side surface may be sufficient to initiate torsional moments.

[0031] Then, when the counterholder device is rotated by means of the rotary axis, the torque can be transmitted in the direction of rotation via a positive connection between the counterholder device and the workpiece, acting in the direction of rotation (circumferential direction). The guide can be a rectangular groove that is open on one side, so that the workpiece engages in the guide groove from the open side when the counterholder device and workpiece engage. It is also possible for the counterholder device to have through-openings that run parallel to the longitudinal direction of the feed-side section and have a rectangular shape adapted to the rectangular cross-section of the workpiece. It is also possible for the guide to be implemented by passing the workpiece through a gap between pairs of rollers or cylinders with a cylindrical circumferential surface.

[0032] The inventors have recognized that it can be particularly useful when bending profiles, e.g. those with a rectangular cross-section, to introduce a plane twist into the profile during rotation, i.e. at a time that overlaps with the bending operation. For example, when bending essentially U-shaped bent parts, it may be the case that after bending the two spaced-apart 90° bends, the bent part does not lie completely flat on a flat support surface, i.e. that the legs of the U-shape are twisted against each other. The cause of this can be, for example, twisting within the workpiece material. This bending error can be reduced or avoided by targeted twisting of the profile in such a way that an additional twisted section is created during the bending of at least one of the bends, so that the two legs of the U-shaped bent part then lie in a common plane with high precision.The introduction of a twisted section can also be useful when the angle of the profile position needs to be influenced. Among other things, the invention, in conjunction with rotary draw bending, can achieve a targeted change in the profile position of legs with respect to a bend or curve. For example, in a rectangular profile, the wider side surfaces of the parallel legs can be aligned at an angle to each other before and after a U-shaped bend.

[0033] According to another aspect, advantages of the claimed invention can also be described as follows: After creating a bend by the bending operation, the legs in front of and behind the bend are at a bending angle to each other. The front leg is formed by the end section whose orientation has been changed, and the rear leg by the feed-side section whose orientation has not been changed. With the aid of the method according to the invention, in addition to the bend in the workpiece material, a twisted section can be created near the bend, so that connected side surface sections of the legs in front of and behind the bend now have different orientations or no longer lie in a common plane.

[0034] In other words, a planar bend of a rectangular material around one of its side surfaces can ideally be designed such that the side surface sections of a side surface lie in a common plane before and after the bend, just as they did before the bend was created. The additional torsion can ensure that a side surface section in a leg lies in a first plane before the bend, and a side surface section of the same side surface defines a second plane behind the bend, which is oblique to the first plane. The angle enclosed by the two planes can be determined by the degree of torsion.

[0035] The method according to the invention can be used for different types of starting workpieces. In some cases, particularly with workpieces with a relatively large diameter or large cross-section, the procedure is such that the workpiece is already cut to length as a prefabricated workpiece before bending and is placed manually or mechanically into the bending machine for a bending operation. One end on the feed side can be clamped, for example, in a pipe wrench or other clamping device in order to enable controlled rotations and axial feed movements. Particularly with thinner cross-sections, work is often carried out from a longer workpiece supply (coil), and the finished bent part is separated from the fed workpiece material by means of a cutting device after all the intended bending operations have been completed.

[0036] According to the invention, the bending machine has a feed device for drawing workpiece material from a material supply toward the bending head. The feed device is rotatable about a feed axis. The feed direction of the workpiece then runs parallel to the feed axis, with a longitudinal center axis of the workpiece being essentially coaxial with the feed axis. This functionality is often provided when bends are required on a bent part in different, angled bending planes, so that the resulting bent parts are bent three-dimensionally. A separate drive, which can be controlled by the control device, is usually provided for rotating the feed device about the feed axis.

[0037] According to the invention, however, a rotatable feed device eliminates the need for a separate counter-holder device. Instead, the feed device is used as the counter-holder device. In other words, the counter-holder device is formed by the feed device. The feed device can then be rotated about its feed axis, while the bending head creates the bend around the bending axis on the workpiece, creating a twisted section between the bending head and the feed device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further advantages and aspects of the invention emerge from the claims and from the following description of preferred embodiments of the invention and other embodiments not according to the invention which are explained below with reference to the figures. Fig. 1shows a schematic representation of a plan view of the bending head and the counterholder device of a bending machine according to an embodiment not according to the invention before clamping the workpiece; Fig. 2 shows the components from Fig. 1 after clamping the workpiece before starting the bending operation; Fig. 3 shows the components from Fig. 1 and 2 during or after the bending operation; Fig. 4 and 5 show views of a further embodiment not according to the invention; Figs. 6 and 7 show views of an embodiment of a bending machine according to the invention with a rotatable feed device used as a counter-holder device; Figs. 8 and 9 show views of an embodiment not according to the invention with a bending head rotatable about the feed axis; Figs. 10 and 11 show views of the non-inventive embodiment of Fig. 8 in the direction of the feed axis ( Fig. 10 ) and after ( Fig. 11) the generation of torsion. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] An embodiment of the invention is explained below using a computer-numerically controlled bending machine. Fig. 1 shows a schematic representation of a plan view of the bending head 100 of the bending machine, which is designed to provide an elongated workpiece 110 in the form of a flat wire with a rectangular cross-section with one or more bends by cold forming.

[0040] In the exemplary embodiment, the bending machine has a rectangular machine coordinate system MK, designated by lowercase letters x, y, and z, with a vertical z-axis and horizontal x- and y-axes. In the example shown, the x-axis runs parallel to the workpiece axis 112 of the not-yet-bent workpiece. The coordinate axes must be distinguished from the controlled-drive machine axes, which will be explained later and are each designated by capital letters (e.g., C, V, P, and Y).

[0041] To produce a bend, an initially straight workpiece section is brought into the starting position shown in the engagement area of ​​the bending head 100.

[0042] For workpieces with a relatively large diameter or large cross-section, the workpiece is often already cut to length as a prefabricated workpiece before bending and is inserted into the bending machine manually or mechanically. For thinner cross-sections, work is often carried out from a longer workpiece supply (coil), and a separate (not shown) feeding device or infeed device is provided with which a workpiece section to be formed is transported into the starting position parallel to a feeding direction or feed direction. The machine axis for the feeding is referred to as the C-axis and includes a drive in the form of an electric servomotor. In the starting position shown, the workpiece axis 112 of the not yet bent workpiece runs in a straight line, parallel to a feeding direction.

[0043] The bending head 100 has a bending arm 120, which can be rotated or pivoted relative to the machine frame about a bending axis 125 running parallel to the z-axis of the machine coordinate system. The associated machine axis is referred to here as the Y-axis and includes a bending drive in the form of an electric servomotor. This is coupled to the bending arm 120 via a drive train.

[0044] The bending arm includes a clamping device 130, which can be pivoted around the bending axis and serves to clamp an end section 115 of the workpiece for the bending operation. The clamping device includes a clamping jaw 135 that can be moved linearly on the bending arm transversely to the workpiece's longitudinal direction. On the side facing the workpiece, the clamping jaw has a rectangular receiving groove 136 for engaging the end section, which has a rectangular cross-section. The associated machine axis for linearly displacing the clamping jaw is referred to as the P-axis and is driven by an electric motor.

[0045] When the end section is clamped, the clamping jaw 135, which is moved towards the workpiece, presses the workpiece against a straight section 142 (clamping area) of a bending die 140, which is contoured with a rectangular groove and is rotatable coaxially with the bending arm about the bending axis 125 and, adjacent to the clamping area, is circularly curved over a large part of its circumference and has curved sections of the rectangular groove. The bending die can be rigidly connected to the bending arm. However, it is also possible for a drive separate from the bending drive to be provided for the bending die in order to change the rotational position of the bending die relative to the rotational position of the bending arm. The outer contour of the bending die predetermines and stabilizes the inner contour of the bent workpiece in the area of ​​the generated bend.

[0046] The section of the workpiece 110 located in front of the bending die is referred to here as the "feed-side section" 118, because during the bending process explained later, workpiece material is fed or moved toward the bending die. A counterholder device 150 is provided to stabilize the feed-side section 118 during the bending operation. The counterholder device has two machine axes, each with its own drive.

[0047] One of the machine axes (V-axis) causes a horizontal linear movement parallel to the y-axis or a feed of the counterholder device in the direction of the workpiece perpendicular to the workpiece axis or perpendicular to the x-direction.

[0048] The other machine axis, referred to here as the counterholder rotation axis or G-axis, causes the counterholder device 150 to rotate about a rotation axis running parallel to the feed direction or the x-axis, which is arranged coaxially to the workpiece longitudinal axis in the feed-side section.

[0049] On the side of the counterholder device 150 facing the workpiece, a receiving contour in the form of a rectangular groove 152 is provided, which, when the counterholder device is in the closed state, encompasses the feed-side section 118 at least to the middle or across its entire width and stabilizes it over a relatively large length. This rectangular groove serves as a guide 152 for the workpiece.

[0050] All drives for the machine axes are electrically connected to a control unit (not shown), which includes, among other things, the power supply for the drives, a central processing unit, and storage units. The control software active in the control unit variably controls the movements of all machine axes to create a coordinated movement of the elements involved in the bending process. A display and control unit connected to the control unit serves as the interface to the machine operator.

[0051] Based on the Fig. 1 to 3 The successive phases of a bending operation will now be explained. First, the section of the workpiece in which a bend is to be created is brought into its initial position in the engagement area of ​​the bending head 100 ( Fig. 1 ).

[0052] Thereafter, the free end section 115 is clamped by means of the clamping device 130 by advancing the clamping jaw 135 towards the workpiece by means of the P-axis and thereby pressing the workpiece against the outer contour of the bending mold 140 (cf. Fig. 2 ). This clamps the end section 115 between the clamping jaw 135 and the bending die 140, but without plastically deforming the cross-sectional shape. A large-area frictional connection exists in the direction of the workpiece axis 112, so that the workpiece is immovably fixed in its longitudinal direction. Due to the precise engagement in the rectangular grooves on the bending die and clamping jaw, the workpiece is also secured against rotation about the workpiece's longitudinal axis by means of a positive connection in the clamped area.

[0053] Then the bending operation begins, which is Fig. 3is illustrated. The bending operation begins with the bending drive (Y-axis) being activated to pivot the bending arm 120 and the bending die 140 in a bending movement around the bending axis 125 in the bending direction 127. In doing so, a flat bend 119 is created between the feed-side section 118 and the clamped end section 115 on the workpiece, the center of curvature of which lies at the bending axis 125 and the inner contour of which is determined by the outer contour of the bending die. Through this bending process, the feed-side section is pulled parallel to the x-axis or the feed direction in the direction of the bending head or fed to the bending die 140.

[0054] During this bending process, the counterholder device 150 remains unchanged in its position along the x-direction, i.e., it is not moved in the feed direction during the bending operation. The fed section slides along contact surfaces (at least one) to the counterholder device.

[0055] In one method variant, the counterholder device 150 is controlled by the control device during the entire rotation of the bending mold or at least during a phase of this rotational movement such that it is rotated by the associated machine axis (counterholder rotational axis, G-axis) about a rotational axis that runs coaxially with the workpiece axis 112 on the feed side. This rotational movement exerts a torsional moment on the section of the workpiece guided by the counterholder device, since the counterholder device acts on the workpiece guided in the guide groove in a similar way to an open-end wrench. The torque is transmitted in the direction of rotation from the counterholder device to the workpiece in a form-fitting manner, since the workpiece is held between opposing guide surfaces of the guide groove.

[0056] In the schematic example of Fig. 3The broad side of the workpiece 110, visible in plan view, runs parallel to the bending plane (which lies parallel to the plane of the drawing) in the area of ​​the bending die. The feed-side section 118 is rotated out of this plane by the rotation of the counter-holder device 150 during the pulling movement towards the bending die, so that the broad sides of the workpiece in the section that lies beyond the bending die (upwards in the drawing) in front of the counter-holder device are inclined to this plane. In this way, in an intermediate section 170 between the end of the counter-holder device 150 facing the bending die 140 and the location at which the workpiece engages in the circumferential groove on the bending die, a twisted section 111 is created, in which the orientation of the planes parallel to the broad surfaces changes continuously. The twisted section 111 represents a permanent deformation on the finished bent part.

[0057] In another process variant, the counterholder device is controlled by the control device before the start of the bending operation so that it is rotated about its rotational axis (running coaxially with the workpiece axis 112 on the feed side) by the associated machine axis (counterholder rotational axis, G-axis). This rotational movement exerts a torsional moment on the section of the workpiece guided by the counterholder device. The torsion is thus introduced before the bending arm 130 is pivoted about the bending axis 125. This allows particularly strong torsions to be generated.

[0058] The twisting or torsion occurs over a certain length of the workpiece, which is referred to as the twisting length. Its length is essentially determined by the distance between the bending mold and the counterholder device in the range 170. The twisting length can, for example, be in the range of 50% to 250% of the (maximum) width of the workpiece, or even significantly higher (e.g., 1000% or more). Workpiece sections in front of and behind the twisted section are twisted relative to one another with respect to a neutral line of the workpiece running centrally along the tool, for example, such that the twisting angle is between 1° and approximately 90°, in particular in the range of 1° to 20°. Other twisting angles are also possible.

[0059] The geometry of the Fig. 3The bending part shown as an example can be described as follows. The workpiece has a single flat bend 119, to which a first leg (formed by the former end section 115) and, on the other side, a second leg (formed by the former feed-side section 118) adjoin. The broad side 117 of the workpiece on the first leg, visible in the drawing, runs parallel to the bending plane (parallel to the plane of the drawing). The part of the feed-side section twisted by rotation of the counter-holder device 150 is oriented such that the broad side 117 no longer runs parallel to the bending plane, but is inclined to it. The transition between the different orientations of these planes is continuous in the region of the twisted section 111.

[0060] There are finished bent parts that have only a single bend and a subsequent twisted section, similar to the example in Fig. 3shown. Of course, it is also possible to create two or more bends at different sections of the workpiece, with or without an associated twisted section.

[0061] In Fig. 4 some components of a bending machine according to another embodiment are shown in isometric view. Fig. 5 shows the same arrangement in plan view. For reasons of clarity, components that are structurally and / or functionally similar or identical to corresponding components of the arrangement in the Fig. 1 to 3 are designated by the same reference numerals.

[0062] The workpiece 110 is a cut-to-length piece of wire with a square or nearly square rectangular cross-section. The bending die 140, which can be rotated about the bending axis 125, has a rectangular groove on the clamping section opposite the clamping jaw 135 and on an adjoining cylindrical section, into which the workpiece fits relatively precisely. A corresponding rectangular groove is formed on the end face of the clamping jaw facing the bending die.

[0063] Since the workpiece has a rectangular cross-section, the rectangular groove can also be omitted, so that those surfaces on the clamping jaw and bending form that come into engagement with the workpiece are smooth and engage opposite side surfaces of the workpiece.

[0064] The bending die and the clamping jaw are shown in a configuration in which the end section 115 is firmly clamped between them and a bending operation has already taken place by rotating the bending die and the clamping device engaging thereon around the bending axis 125. Accordingly, a bend 119 is located in the area of ​​the bending die between the end section 115 and the feed-side section 118 located in front of the bending die.

[0065] The counterholder device 150 engages the workpiece at a distance in front of the bending die. A rectangular groove is formed on the side facing the workpiece 110, so that the flat upper and lower surfaces of the workpiece lie between mutually parallel guide surfaces of the circumferential groove, and the counterholder device can engage the workpiece similar to an open-end wrench. During the bending operation, the counterholder device can be rotated by means of the counterholder rotation axis about a rotation axis located coaxially to the workpiece axis in the feed-side section 118 in order to create a twisted section.

[0066] In the example, the end of the workpiece opposite the end section 115 is clamped in a clamping device in the form of a pipe wrench 180. The pipe wrench can be rotated about the feed direction on the one hand by means of suitable controllable machine axes and can also be moved in a controlled manner parallel to the feed direction on the other. If, during the bending operation, i.e., while the bending die 140 with the clamping jaw 135 attached rotates about the bending axis 125, a twisted section is to be created subsequent to the bend, the counterholder device 150 is rotated about the feed-side longitudinal axis of the workpiece using its own rotary drive. Synchronously with this, the pipe wrench 180 is also rotated so that the section of the workpiece located between the pipe wrench 180 and the counterholder device 150 is not twisted.

[0067] The Figs. 6 and 7show components of a bending machine according to another embodiment. For clarity, components that are structurally and / or functionally identical or similar to corresponding components of the first embodiment are designated by the same reference numerals.

[0068] The associated bending machine is designed for processing workpiece material, which is initially available in a large material supply on a so-called coil and is fed into the bending machine piece by piece for the sequential production of bent parts. For this purpose, the bending machine has a feed device 190 for feeding workpiece material from a material supply. The feed device is linearly displaceable parallel to the x-direction of the machine coordinate system and thereby specifies the feed direction or advance direction of the material and the orientation of the workpiece's longitudinal axis in the feed-side section 118. Furthermore, the feed device is rotatable about a feed axis 192 running parallel to the x-direction by means of its own rotary drive. The feed axis is coaxial with the workpiece's longitudinal axis in the feed-side section 118 and specifies its position.

[0069] The feed device 190 has roller-like components (feed rollers or rollers) inside it, which engage in pairs on opposite flat side surfaces of the rectangular workpiece material and effect the feed. The workpiece material is clamped between these pull rollers in a rotationally secure manner. Accordingly, when the feed device 190 rotates about its feed axis, a torsional moment can be exerted on the section of the workpiece being fed through by means of the feed rollers. Other designs of feed devices are possible, e.g., a gripper feed or a belt feed.

[0070] In this configuration, the feed device 190 simultaneously assumes the function of the counter-holder device, which guides the feed-side section 118 of the workpiece at a distance in front of the bending mold 140 by absorbing transverse forces during bending and is simultaneously capable of producing a twisted section in the area between the feed device / counter-holder device and the bending mold by rotating the counter-holder device / feed device before, during and / or after the bending operation.

[0071] In this application, the term "bending machine" refers to a computer-numerically controlled forming machine capable of creating one or more permanent bends on an elongated workpiece, e.g., a wire, a rod, or a tube made of a metallic material, in order to produce a bent part with a predeterminable bending geometry. Bending machines include, for example, pipe bending machines, wire bending machines, or spring machines configured to produce bent parts in the form of springs (e.g., tension springs, compression springs, torsion springs) by spring coiling or spring winding.

[0072] The combination of bending die 140 and clamping device or clamping jaw 135 can be in the form of a separate forming tool. The counterholder device can be integrated into the forming tool or formed by a separate unit from the forming tool, in particular by a rotatable feed device of the bending machine.

[0073] Based on the Fig. 8 to 11 A further embodiment will now be described. For reasons of clarity, components that are structurally and / or functionally similar or identical to corresponding components of the arrangement in the Figures 4 and 5 is designated by the same reference numerals.

[0074] The Figs. 8 and 9 show an oblique perspective view or a top view of some components of the bending machine similar to the Fig. 4 and 5 . The Figs. 10 and 11 show views of the bending head of the bending machine from the feed direction, i.e. from the direction in which the material to be bent is fed.

[0075] In this embodiment, the feed-side end of the workpiece opposite the end section 115 is also clamped in a clamping device in the form of a pipe wrench 180. The pipe wrench can be moved parallel to the feed direction in a controlled manner using suitable controllable machine axes, but remains stationary during the forming process. The counterholding device 150 is also stationary.

[0076] A special feature of the bending machine is that the bending machine has a machine axis with which the bending mold 140 and the clamping jaw 135 can be rotated about a rotation axis 160 which runs parallel to the feed direction or to the feed-side section 118.

[0077] If, during the bending operation, i.e., while the bending die 140 with the clamping jaw 135 is rotating about the bending axis 125, a twisted section is to be created adjacent to the bend 119, the bending die 140 with the clamping jaw 135 is rotated about the feed-side workpiece longitudinal axis (rotation axis 160) with the aid of a pivoting drive or rotary drive. During this operation, the counterholding devices 150 and the pipe wrench 180 are stationary so that the section of the workpiece located between the pipe wrench 180 and the counterholding device 150 is not twisted. The initiation of the torsion or twisting can occur before, during, and / or after the bending operation, as in the previous embodiments.

[0078] Based on the Figures 10 and 11An exemplary implementation of this functionality will now be presented and a bending operation with torsion will be explained. In the area of ​​the bending head 100, an arcuately curved support 116 with a curved guide 113 is mounted on the machine frame. The bending head 100 is rotatably mounted in a suitable bearing such that it can be pivoted about the rotational axis 160, which runs parallel to the feed-side section 118 of the workpiece, within a predetermined angular range, for example, ± 45°. A part of the bending head remote from the rotational axis 160 is guided in the curved guide for this purpose.

[0079] Figure 10shows the bending head in its neutral position, in which the bending axis 125 of the bending head is oriented parallel to the z-axis of the machine coordinate system. In this position of the bending head, "normal" bends without torsion are possible. If a twisted section is to be created, the bending head is pivoted under machine control before, during, and / or after the rotation of the bending die 140 about the bending axis 125, so that the plane passing through the feed-side section 118 and the end section 115 becomes increasingly oblique to the x / y plane of the machine coordinate system, creating a twisted section between the counter-holding device 115 and the bending head.

Claims

1. Method for producing a bent part from an elongated workpiece (110) by means of a bending machine which has a bending head (100) having a bending mould (140) and a bending arm (120) that is rotatable about the bending mould and has a clamping device (130) for clamping an end portion (115) of the workpiece against a circumferential portion of the bending mould and is rotatable about a bending axis (125), wherein a portion of the workpiece is moved to an initial position in the engagement region of the bending head (100) ; the clamping device (130) is brought into contact with the end portion and clamps the end portion in relation to a circumferential portion of the bending mould (140); a counter-holding device (150) is brought to engage with a feed-side portion (118) of the workpiece; and in a bending operation a bend (119) between the feed-side portion (118) and the end portion (115) is generated by rotating the bending arm (120) about the bending axis (125); wherein the counter-holding device (150) for introducing and / or receiving a torque engages on the feed-side portion (118) and the counter-holding device (150) and / or the bending head (100) before, during and / or after the rotation of the bending arm (120) about the bending axis (125) is rotated about a rotation axis extending parallel to the longitudinal direction of the feed-side portion (118) in such a manner that a twisted portion (111) is generated in a region (170) between the counter-holding device (150) and the bending mould (140), characterized in that the bending machine has an infeed device (190) for infeeding workpiece material from a material supply, in that the infeed device (190) is rotatable about an infeed axis (192), and in that the infeed device is used as the counter-holding device.

2. Method according to Claim 1, characterized in that the counter-holding device is used in such a way that the infeed device is rotated about the infeed axis, while the bend (119) about the bending axis (125) is generated on the workpiece (110) with the aid of the bending head (100) so that a twisted portion (111) is generated between the bending head and the infeed device.

3. Method according to Claim 1 or 2, characterized in that the bent part is produced from a workpiece with a rectangular cross section.

4. Method according to Claim 3, characterized in that a bend (119) and a twisted portion (111) adjoining thereto are generated in such a manner that a lateral face portion of a lateral face (117) lies in a leg in front of the bend in a first plane, a lateral face portion of the same lateral face (117) behind the bend defines a second plane which is oblique in relation to the first plane, and an angle enclosed by the planes is determined by the degree of torsion.

5. Bending machine for producing a bent part from an elongate workpiece (110), having: a control device; a bending head (100) which has a bending mould (140) and a bending arm (120) that is rotatable about the bending mould and has a clamping device (130) for clamping an end portion (115) of the workpiece in relation to a circumferential portion of the bending mould (140), wherein the bending arm is rotatable about a bending axis (125) by means of a bending drive controlled by the control device; a counter-holding device (150) which is disposed upstream of the bending mould (140) and is configured to engage with a feed-side portion (118) of the workpiece in order to stabilize an alignment of the longitudinal axis of the feed-side portion during a bending operation; wherein the counter-holding device (150) is designed for introducing and / or receiving a torque on the feed-side portion (118); the counter-holding device (150) and / or the bending head (100) by means of a rotary drive controlled by the control device is rotatable about a rotation axis (160) which runs parallel to a feed direction of the workpiece; and the control device is configured, or configurable, to rotate the counter-holding device (150) and / or the bending head (100), before, during and / or after a rotation of the bending arm (120) about the bending axis (125), about a rotation axis (160) extending parallel to the longitudinal direction of the feed-side portion (118) in such a manner that a twisted portion (111) is able to be generated in a region (170) between the counter-holding device (150) and the bending mould (140), characterized in that the bending machine has an infeed device (190) for infeeding workpiece material from a material supply, in that the infeed device is rotatable about an infeed axis, and in that the counter-holding device is formed by the infeed device (190).

6. Bending machine according to Claim 5, characterized in that the bending machine is conceived for bending workpieces with a rectangular cross section.

7. Bending machine according to Claim 6, characterized in that the counter-holding device (150) has a guide (152) for the workpiece, which is adapted to the rectangular cross section of the workpiece (110) in such a manner that the guide guides the feed-side portion (118) of the workpiece in an engagement configuration at least on two opposite lateral faces.

8. Bending machine according to one of Claims 5 to 7, characterized in that no separate counter-holding device is provided in addition to the infeed device that is rotatable about the infeed axis.