WO2020052890A1

WO2020052890A1 - Method for producing a bent part and bending machine for performing the method

Info

Publication number: WO2020052890A1
Application number: PCT/EP2019/071689
Authority: WO
Inventors: Julian Pandtle; Jürgen Wolf
Original assignee: Wafios Aktiengesellschaft
Priority date: 2018-09-12
Filing date: 2019-08-13
Publication date: 2020-03-19
Also published as: DE102018215501A1; EP3849723A1

Abstract

In the case of a method for producing a bent part from an elongated workpiece, a bending machine is used, comprising a bending head (100) with a bending mould (140) and comprising a bending arm (120) which can be turned about the bending mould, 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). First, a portion of the workpiece is brought into a starting position within the range of engagement of the bending head (100). The clamping device (130) is brought into contact with the end portion and clamps the end portion against a circumferential portion of the bending mould (140). A counter-holder device (150) is brought into engagement with a feed-side portion (118) of the workpiece. Then, a bend (119) is produced between the feed-side portion (118) and the end portion (115) in a bending operation by turning the bending arm (120) about the bending axis (125). The counter-holder device (150) acts on the feed-side portion (118) to introduce and/or receive a torsional moment. Before, during and/or after the turning of the bending arm (120) about the bending axis (125), the counter-holder device (150) and/or the bending head (100) is turned about an axis of rotation running parallel to the longitudinal direction of the feed-side portion (118) in such a way that a twisted portion (111) is produced in a region (170) between the counter-holder device (150) and the bending mould (140).

Description

Method for producing a bending part and bending machine for carrying out the

Procedure

APPLICATION AREA AND PRIOR ART

The invention relates to a method for producing a bent part according to the preamble of claim 1 and to a bending machine set up to carry out the method according to the preamble of claim 5. A preferred area of application is the bending of workpieces with a rectangular cross section.

In the automated production of two- or multi-dimensionally bent parts with the aid of numerically controlled bending machines, the movements of the machine axes of a bending machine are controlled in a coordinated manner with the aid of a control device in order to allow the workpiece, e.g. a rod or a tube or a wire to create one or more permanent bends by plastic forming.

In an automated bending process of the type considered in this application, the workpiece is shaped with the aid of a bending machine which has a bending head with a bending shape and with a bending arm which can be rotated about the bending shape. The bending arm has a clamping device for clamping an end section of the workpiece against a peripheral section or an outer contour of the bending mold. The bending arm can be rotated about a bending axis by means of a bending drive controlled by the control device.

The bending machine furthermore has a counter-holding device which can be brought into engagement with a feed-side section of the workpiece for the bending operation in order to stabilize the alignment of the longitudinal axis of the feed-side section during a bending operation by absorbing transverse forces.

During the bending process, a section of the workpiece to be formed is first brought into a starting position in the engagement area of the bending head. If pre-assembled, already cut individual workpieces are to be bent, they can be inserted into the bending machine. It is also possible to move a piece of suitable length from a longer supply of workpieces into the starting position by means of a feed operation.

Thereafter, the tensioner is brought into contact with the end portion to tension the end portion against a peripheral portion of the bending die and on the bending die to clamp. The end section can be fixed between a clamping jaw of the clamping device and the bending shape.

Simultaneously or at different times from this, the counter-holding 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.

Thereafter, in a bending operation, by rotating the bending arm around the bending axis, a bend is generated between the feed-side section stabilized against transverse forces by the counter-holding device and the end section. Due to the synchronous rotation of the bending mold and the clamping device around the bending axis, the workpiece is “pulled” as it were around the bending mold or a circumferential section thereof. The outer contour of the bending shape can stabilize the inner contour of the bend and precisely specify its radius. The rear, straight leg of the workpiece, that is to say the section on the feed side, is supported by the counter-holding device, which, as a counter-bearing, absorbs the transverse forces resulting from the bend and thus ideally remains aligned parallel to a feed direction. The feed direction is the direction in which material is fed or drawn in the direction of the bending shape during bending.

In the ideal case, a flat bend is produced, in which the legs in front of and behind the bend, formed by the end section which is changed in its orientation and the feed section which is not changed in its orientation, lie in a common plane. The relative orientation of the end section with respect to the feed section is usually described by the bending angle.

These characteristics are typical for the bending process "rotational tensile bending". Rotational tensile bending is a widespread 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).

TASK AND SOLUTION

It is an object of the invention to develop a generic method and a generic bending machine in such a way that bent parts with improved bending geometry can be produced. To achieve this object, the invention provides a method with the features of claim 1 and a bending machine with the features of claim 5. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated by reference into the content of the description.

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

In addition to the flat bending around the bending axis, a further shaping operation is carried out, namely a torsion of the workpiece in an area between the bending shape and the counter-holding device. The workpiece is held on one side (at the end section) by the fixation between the bending mold and the clamping device and on the other side by the counter-holding device, which acts on the feed-side section in such a way that a torsional torque can be introduced into the workpiece and / or that a torsional moment generated by rotating the bending shape about the axis of rotation can be absorbed. A permanent deformation in the form of a twisted or twisted section in the vicinity of a bend can thus be generated. The bend and the twisted section can merge directly into one another.

Decisive for the production of the twisted section is a relative rotation between the bending head and the counter-holding device about the axis of rotation, which runs parallel to the longitudinal direction of the section on the feed side. The relative rotation can be on different ways are created. It is possible that only the counter holder device is rotated, while there is no rotation around the axis of rotation on the bending head. It is also possible for the counter-holding device to stand still during the production of the twisted section and for only the bending head to be rotated about the axis of rotation. It is also possible for both the counter-holder device and the bending head to be rotated about the axis of rotation in order to generate the relative rotation. The two rotations, which usually run in opposite directions to one another, can be generated synchronously or at different times.

This new functionality can be implemented on the bending machine in accordance with the claimed invention in that the counter-holding device is designed for introducing and / or absorbing a torsional moment on the feed-side section and in that the counter-holding device and / or the bending head is rotated about an axis of rotation by means of a rotary drive that can be controlled by the control device is rotatable, which runs parallel to a feed direction of a workpiece. The control device of the bending machine is configured or configurable to rotate the counter-holding device and / or the bending head before, during and / or after a rotation of the bending arm about the bending axis at least in phases about an axis of rotation running parallel to the longitudinal direction of the feed-side section such that in a permanent deformation in the form of a twisted or twisted section can be generated in an area between the counter-holding device and the bending shape of the bending head arranged behind it in the material feed direction. The torsional moment can be transmitted from the counter-holding device to the workpiece and / or absorbed by the form-fitting and / or non-positive connection. The control device can be configured to carry out the method if it can provide an operating mode in which a simultaneous coordinated rotation of the bending arm and the counter-holding device and / or the bending head takes place at least in phases.

There are different possibilities for coordinating the rotation of the counter-holding device and / or the bending head which leads to torsion with the generation of the bending by rotating the bending mold.

In one variant, the torsional moment is first initiated by rotating the counter-holding device before the bending arm is subsequently rotated about the bending axis. The rotation of the counter-holding device can be completed before the rotation of the bending mold begins, so that these two operations take place in succession at different times. With this variant, particularly strong twists or torsions can be generated in the workpiece if required. It is also possible to coordinate the movements in such a way that the introduction of the torsional moment (by rotating the counter-holding device) takes place in phases or completely simultaneously or synchronously with the rotation of the bending arm, so that these operations overlap in time.

It is also possible to first generate the bend by rotating the bending arm or the bending shape and then to initiate the torsional moment.

Other variants are also possible. So it is e.g. It is possible to start the rotation of the counter-holding device first and to initiate the rotation of the bending arm at different times before the counter-holding device has reached its desired end rotary position. Then the introduction of the torsional moment (by rotating the counter-holding device) and the generation of the bend (by rotating the bending arm) run at least in phases synchronously. It would also be possible to start the bend first (by starting the rotation of the bending arm) and to initiate the rotation of the counter-holding device at different times before the bending arm has reached its end position. In this case too, the introduction of the torsional moment (by rotating the counter-holding device) and the generation of the bend (by rotating the bending arm) are synchronous at least in phases.

In the above variants, a rotation of the bending head around the section parallel to the feed-side section is not necessary and is also not provided. These variants can be carried out with bending machines, the bending head of which cannot be rotated about the axis of rotation mentioned.

Analog variants can be used if the bending machine has a bending head which can be rotated in a controlled manner about the axis of rotation running parallel to the section on the feed side.

In one variant, the torsional moment is first initiated by turning the bending head before the bending arm is then rotated around the bending axis. The rotation of the bending head can be completely completed before the rotation of the bending shape begins, so that these two operations take place in succession at different times. It is also possible to coordinate the movements so that the introduction of the torsional moment (by rotating the bending head) takes place in phases or completely simultaneously or synchronously with the rotation of the bending arm, so that these operations overlap in time.

It is also possible to first generate the bend by rotating the bending arm or the bending shape and then the torsional moment by rotating the bending head around the initiate axis of rotation running parallel to the section on the feed side. It is also possible to start the rotation of the bending head first and to start the rotation of the bending arm at different times before the bending head has reached its desired end rotary position.

With the aid of the method, the bending geometry of the finished bent part can be positively influenced, since an additional degree of freedom for material forming creates a bend in the immediate vicinity or overlaps with a bend. This can be used to correct the bending geometries in order to adapt the actual geometry achieved exactly to the desired target geometry. It is also possible to realize very complex, possibly completely new, bending geometries, that is, bending geometries that could not previously be produced using pure bending processes.

Round material can be processed, i.e. workpieces with a circular cross-section. There are particular advantages in the processing of profile material, including workpieces with a non-circular cross-sectional shape, e.g. Oval wire or wire or tube with a rectangular cross-section.

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 a profile material which, in the non-bent state, has four essentially flat side surfaces which extend parallel to the longitudinal direction of the workpiece, the side surfaces adjacent in the circumferential direction in each case being essentially at right angles to one another. Rounding can be provided on the edges lying between them. The workpiece can have a substantially square cross-section in which all four side surfaces are essentially of the same width. It is also possible for the workpiece to have two opposite broad sides and two narrow sides, which are arranged perpendicular to the broad sides and are opposite one another and have a smaller width. It can be flat material, for example, as is used, for example, to produce electrically conductive conductor sections with a special bending geometry.

For the processing of workpieces with a rectangular cross section, the counter-holding device is preferably designed in such a way that it has a guide for the workpiece, which 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 on at least two opposite side surfaces if the counter-holding device is in engagement with the workpiece. In some cases, an attack on only one side surface can be sufficient to initiate torsional moments.

Then, when the counter-holder device is rotated by means of the axis of rotation, the torque can be transmitted in the direction of rotation via a positive connection acting in the direction of rotation (circumferential direction) between the counter-holder device and the workpiece. 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 producing the engagement between the counter-holding device and the workpiece. It is also possible for the counter-holding device to have a through opening which is parallel to the longitudinal direction of the feed-side section and has a rectangular shape which is adapted to the rectangular cross section of the workpiece. It is also possible for the guidance to be realized in that the workpiece is passed through a gap between pairs of rollers or rollers with a cylindrical peripheral surface.

The inventors have recognized that, in particular when bending profiles, e.g. those with a rectangular cross-section can be useful during the rotation, i.e. overlapping in time with the bending operation, to initiate a plane rotation in the profile. For example, when bending essentially U-shaped bent parts, it can be such that after the bending of the two 90 ° bends spaced apart from one another, the bent part does not lie completely flat on a flat contact surface, that is to say that the legs of the U-shape are mutually intertwined are. The reason for this can be e.g. Torsion within the workpiece material. This bending error can be reduced or avoided by deliberately rotating the profile in such a way that during the bending of at least one of the bends an additional twisted section is additionally generated, so that the two legs of the U-shaped bent part are then combined with high accuracy Level. The introduction of a twisted section can also be useful if the angle of the profile position has to be influenced. Among other things, the invention in connection with the rotational tensile bending enables a targeted change in the profile position of legs with respect to a bend or an arc. For example, in the case of a rectangular profile, the wider side surfaces of the legs running parallel to one another can be aligned obliquely to one another in front of and behind a U-shaped bend.

According to another aspect, advantages of the claimed invention can also be described in this way. After a bend has been created by the bending operation, the legs stand in front of and behind the bend at an angle to one another. The front leg is formed by the end section changed in its orientation, the rear leg by the feed-side section not changed in its orientation. With the aid of the method according to the invention, in addition to the bend in the workpiece material, a twisted section can be produced in the vicinity of 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.

In other words, a flat bend of a rectangular material around one of the side surfaces can ideally be carried out in such a way that side surface sections of a side surface lie in front of and behind the bend in a common plane, just as before the generation of the bend. As a result of the additional torsion, it can be achieved that a side surface section in one leg lies in a first plane in front of the bend and a side surface section of the same side surface behind the bend defines a second plane which is oblique to the first plane. The angle included by the two planes can be determined by the amount of torsion.

The method according to the invention can be used for different types of starting workpieces. In some cases, in particular in the case of workpieces with a relatively large diameter or large cross section, the procedure is such that the workpiece is already cut to length as a pre-assembled workpiece and is inserted manually or mechanically into the bending machine in order to carry out a bending operation. A feed end can e.g. be clamped in a pipe wrench or other clamping device to allow controlled self-rotation and axial feed movements. A longer workpiece stock (coil) is often used, particularly in the case of a thinner cross section, and the finished bent part is separated from the supplied workpiece material by means of a cutting device after all the intended bending operations have been completed.

In some embodiments, the bending machine has a drawing-in device for drawing in workpiece material from a material supply in the direction of the bending head. The feed device can be rotated about a feed axis. The feed direction of the workpiece then runs parallel to the feed axis, a longitudinal central axis of the workpiece being essentially coaxial with the feed axis. This functionality is often provided if bends in different bending planes which are at an angle to one another are required on a bent part, so that the resulting bent parts are bent three-dimensionally. A separate drive, which can be controlled by means of the control device, is generally provided for the rotation of the feed device about the feed axis. If such a pull-in device is provided, it can be provided in addition to the counter-holding device. As a rule, the pull-in device is then rotated synchronously when the counter-holding device is rotated about its axis of rotation, so that there is no torsion in the workpiece between the pull-in device and the downstream counter-holding device.

In some embodiments with a rotatable feed device, on the other hand, a separate counter-holding device can be dispensed with. Instead, the feed device is used as a counter-holding device. In other words: the counter-holding device is formed by the pull-in device. In this case, the drawing-in direction can then be rotated about its drawing-in axis, while the bending around the bending axis is generated on the workpiece with the aid of the bending head in order to produce a twisted section between the bending head and the drawing-in device.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects of the invention result from the claims and from the following description of preferred exemplary embodiments of the invention, which are explained below with reference to the figures.

1 shows a schematic representation of a plan view of the bending head and the counter-holding device of a bending machine according to one embodiment before clamping the workpiece;

FIG. 2 shows the components from FIG. 1 after the workpiece has been clamped before the bending operation begins;

Figure 3 shows the components of Figures 1 and 2 during or after the bending operation;

4 and 5 show views of a further embodiment;

6 and 7 show views of an embodiment of a bending machine with a rotatable feed device which is used as a counter-holding device;

8 and 9 show views of an embodiment with a bending head rotatable about the feed axis; 10 and 11 show views of the embodiment of FIG. 8 in the direction of the feed axis before (FIG. 10) and after (FIG. 11) the generation of a torsion.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An exemplary embodiment of the invention is explained below using a computer-numerically controlled bending machine. 1 shows a schematic representation of a top 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 by cold forming with one or more bends.

In the exemplary embodiment, the bending machine has a right-angled machine coordinate system MK, identified 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 workpiece that has not yet been bent. A distinction must be made between the coordinate axes and the controlled driven machine axes, which are described later with capital letters (e.g. C, V, P and Y).

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

In the case of workpieces with a relatively large diameter or large cross-section, the workpiece is often already cut to length as a pre-assembled workpiece and is inserted into the bending machine manually or by machine. In the case of thinner cross sections, a longer workpiece supply (coil) is often used, and a separate feed device (not shown) is provided, by means of which a workpiece section to be formed is conveyed into the starting position parallel to a feed direction or feed direction. The machine axis for the feed is called the C-axis and includes a drive in the form of an electric servo motor. In the starting position shown, the workpiece axis 112 of the workpiece which has not yet been bent runs in a straight line, parallel to a feed direction.

The bending head 100 has a bending arm 120 which can be rotated or pivoted with respect 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 comprises a bending drive in the form of an electric servo motor. This is coupled to the bending arm 120 via a drive train. The bending arm includes a clamping device 130, which can be pivoted with it about 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 which can be moved linearly on the bending arm transversely to the longitudinal direction of the workpiece and which has a rectangular receiving groove 136 on the side facing the workpiece for engaging the end section which is rectangular in cross section. The associated machine axis for linear displacement of the clamping jaw is referred to as the P axis and has an electric motor as the drive.

When the end section is clamped in, the clamping jaw 135 moving in the direction of the workpiece presses the workpiece against a straight section 142 (clamping area) contoured with a rectangular groove, which can be rotated coaxially with the bending arm about the bending axis 125 and then against the clamping area over a large one Part of its circumference is circularly curved and has curved sections of the rectangular groove. The bending shape can be firmly connected to the bending arm. However, it is also possible that a drive separate from the bending drive is provided for the bending mold in order to change the rotational position of the bending mold relative to the rotational position of the bending arm. The inner contour of the bent workpiece is predetermined and stabilized in the area of the generated bend by the outer contour of the bending shape.

The section of the workpiece 110 that is located in front of the bending mold is referred to here as the “feed-side section” 118 because workpiece material is fed or moved in the direction of the bending mold in the bending process explained later. A counter-holding device 150 is provided to stabilize the feed-side section 118 during the bending operation. The counter-holding device has two machine axes, each of which has its own drive.

One of the machine axes (V axis) causes a horizontal linear movement parallel to the y axis or an infeed of the counter-holding device in the direction of the workpiece perpendicular to the workpiece axis or perpendicular to the x direction.

The other machine axis, which is referred to here as the counter-holder rotation axis or G-axis, causes the counter-holder device 150 to rotate about an axis of rotation which runs parallel to the feed direction or to the x-axis and is arranged coaxially to the workpiece longitudinal axis in the feed-side section.

On the side of the counter-holding device 150 facing the workpiece, a receiving contour in the form of a rectangular groove 152 is provided, which defines the feed-side section 1 18 in the delivered state of the counter-holding device encompasses at least up to the middle or over its entire width and stabilizes it over a relatively long length. This rectangular groove serves as a guide 152 for the workpiece.

All drives for the machine axes are electrically connected to a control device, not shown, which contains, among other things, the power supply for the drives, a central computer unit and storage units. With the help of the control software active in the control device, the movements of all machine axes are variably controlled in order to generate a coordinated movement of the elements involved in the bending process. A display and control unit connected to the control device serves as an interface to the machine operator.

Successive phases of a bending operation will now be explained with reference to FIGS. 1 to 3. First of all, that portion of the workpiece in which a bend is to be produced is brought in its starting position in the engagement area of the bending head 100 (FIG. 1).

The free end section 115 is then clamped in by means of the clamping device 130, in that the clamping jaw 135 is pushed in the direction of the workpiece by means of the P-axis and the workpiece is thereby pressed against the outer contour of the bending mold 140 (cf. FIG. 2). As a result, the end section 115 is clamped between the clamping jaw 135 and the bending mold 140, but without plastically deforming the cross-sectional shape. There is a large-area frictional connection in the direction of the workpiece axis 112, so that the workpiece is immovably fixed in its longitudinal direction. The workpiece is secured in the clamped area due to the precisely fitting engagement in the rectangular grooves on the bending shape and clamping jaw by means of positive locking against rotation around the workpiece longitudinal axis.

Then the bending operation begins, which is illustrated in FIG. 3. The bending operation begins with the bending drive (Y axis) being activated in order to pivot the bending arm 120 and the bending mold 140 in a bending movement around the bending axis 125 in the bending direction 127. A flat bend 119 is generated on the workpiece between the feed-side section 118 and the clamped end section 115, 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 shape. As a result of this bending process, the feed-side section is drawn parallel to the x-axis or the feed direction in the direction of the bending head or is fed to the bending mold 140. The counter-holding device 150 remains unchanged in its position along the x-direction during this bending process, ie it is not moved in the feed direction during the bending operation. The supplied section slides along contact surfaces (at least one) to the counter-holding device.

In one variant of the method, the counter-holding device 150 is controlled by the control device during the entire rotation of the bending mold or at least during one phase of this rotary movement in such a way that it is rotated by the associated machine axis (counter-holder rotating axis, G-axis) about an axis of rotation which is coaxial with the Workpiece axis 1 12 runs on the feed side. This rotary movement exerts a torsional moment on the section of the workpiece guided on the counter-holding device, since the counter-holding device acts on the workpiece guided in the guide groove in a manner similar to an open-ended wrench. The torque is positively transmitted from the counter-holding device to the workpiece in the direction of rotation, since the workpiece is held between mutually opposite guide surfaces of the guide groove.

In the schematic example of FIG. 3, the broad side of the workpiece 110, which is visible in plan view, runs parallel to the bending plane in the region of the bending shape (which lies parallel to the drawing plane). The feed-side section 118 is rotated out of this plane during the pulling movement in the direction of the bending shape by the rotation of the counter-holding device 150, so that the broad sides of the workpiece are inclined in the section which lies beyond the bending shape (upwards in the drawing) in front of the counter-holding device to this level. In this way, a twisted section 11 1 is generated in an intermediate section 170 between the end of the counter-holding device 150 facing the bending mold 140 and the location at which the workpiece engages in the circumferential groove on the bending mold, in which the orientation of the to the wide surfaces parallel planes changes continuously. The twisted section 11 1 represents a permanent deformation on the finished bent part.

In another variant of the method, the counter-holding device is controlled by the control device before the bending operation begins so that it is rotated about its axis of rotation by the associated machine axis (counter-holder rotation axis, G-axis) (runs coaxially with the workpiece axis 1 12 on the feed side). A torsional moment is exerted on the section of the workpiece guided on the counter-holding device via this rotary movement. The torsion is thus introduced before the bending arm 130 is pivoted about the bending axis 125. This can create particularly strong torsions. The twisting or torsion takes place over a certain length of the workpiece, which is referred to as the twisting length. Their length is essentially determined by the distance between the bending shape and the counter-holding device in the area 170. The twisting length can be, for example, in the range from 50% to 250% of the (maximum) width of the workpiece, possibly also significantly more (for example 1000% or more). Workpiece sections in front of and behind the twisted section are twisted relative to one another in relation to a neutral line of the workpiece running centrally along the tool, for example in such a way that the twist angle is between 1 ° and approximately 90 °, in particular in the range from 1 ° to 20 °. Other angles of rotation are also possible.

The geometry of the bent part shown by way of example in FIG. 3 can be described as follows. The workpiece has a single flat bend 1 19, to which a first leg (formed by the former end section 1 15) and on the other side a second leg (formed by the former feed section 11 18) adjoins. The broad side 1 17 of the workpiece on the first leg visible in the drawing runs parallel to the bending plane (parallel to the drawing plane). The part of the feed-side section rotated by rotation of the counter-holding device 150 is oriented in such a way 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 levels is continuous in the area of the twisted section 11.

There are finished bent parts that have only a single bend and an adjoining twisted section, similar to the example shown in FIG. 3. Of course, it is also possible to produce two or more bends on different sections of the workpiece with or without an associated twisted section.

4 shows some components of a bending machine according to another embodiment in an 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 FIGS. 1 to 3 are identified by the same reference numerals.

The workpiece 110 is a cut-to-length piece of wire with a square or almost square rectangular cross section. The bending mold 140, which is rotatable about the bending axis 125, has a rectangular section on the clamping jaw 135 opposite and on a cylindrical section adjoining it, into which the workpiece is relative fits a part perfectly. A corresponding rectangular groove is formed on the end face of the clamping jaw facing the bending shape.

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 shape that come into engagement with the workpiece are smooth and act on opposite side surfaces of the workpiece.

The bending mold and the clamping jaw are shown in a configuration in which the end section 115 is clamped firmly between them and a bending operation by rotating the bending mold and the clamping device acting thereon has already taken place about the bending axis 125. Correspondingly, there is a bend 119 in the region of the bending shape between the end section 115 and the feed-side section 118 lying in front of the bending shape.

The counter-holding device 150 acts on the workpiece at a distance from the bending mold. A rectangular groove is formed on the side facing the workpiece 110, so that the flat upper and lower sides of the workpiece lie between mutually parallel guide surfaces of the circumferential groove and the counter-holding device can engage the workpiece in a manner similar to an open-end wrench. During the bending operation, the counter-holder device can be rotated by means of the counter-holder axis of rotation about an axis of rotation lying coaxially to the workpiece axis in the feed-side section 118, in order to produce a twisted section.

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 on the other hand can be displaced in a controlled manner parallel to the feed direction. If, during the bending operation, that is to say while the bending mold 140 rotates around the bending axis 125 with the clamping jaw 135 adjacent to it, a twisted section is to be produced after the bending, the counter-holding device 150 is rotated about the longitudinal workpiece axis on the feed side with the aid of its own rotary drive. The pipe wrench 180 is also rotated synchronously therewith so that the section of the workpiece lying between the pipe wrench 180 and the counter-holding device 150 is not twisted.

6 and 7 show components of a bending machine according to another embodiment. For reasons of clarity, the components that are structurally and / or functionally identical or similar to corresponding components of the first embodiment are denoted by the same reference symbols. The associated bending machine is intended for processing workpiece material, which is initially available in a large material supply on the so-called coil and is drawn into the bending machine piece by piece for the successive production of bent parts. For this purpose, the bending machine has a feed device 190 for pulling in workpiece material from a material supply. The feed device can be displaced linearly parallel to the x-direction of the machine coordinate system and thereby specifies the feed direction or feed direction of the material and the orientation of the workpiece longitudinal axis in the feed-side section 118. Furthermore, the feed device can be rotated with the aid of its own rotary drive about a feed axis 192 running parallel to the x direction. The feed axis is coaxial with the workpiece longitudinal axis in the feed-side section 118 or specifies its position.

The feed device 190 has in its interior roller-like or roller-like components (feed rollers or rollers) which act in pairs on opposite flat side surfaces of the rectangular workpiece material and bring about the feed. The workpiece material is clamped against rotation between these pull rollers. Accordingly, when the feed device 190 rotates about its feed axis, a torsional moment can be exerted on the section of the workpiece passed with the aid of the feed rollers. Other types of feed devices are possible, e.g. a forceps feeder or a tape feeder.

In this configuration, the pull-in device 190 simultaneously takes over the function of the counter-holding 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 at the same time is able to rotate the counter-holding device / pull-in device before and / or after the bending operation to produce a twisted section in the area between the drawing-in device / counter-holding device and the bending mold.

In this application, the term “bending machine” denotes a computer-numerically controlled forming machine which is capable of producing one or more permanent bends on an elongated workpiece, for example on a wire or a rod or a tube made of a metallic material, in order to produce one To produce a bent part with a predefinable bending geometry. The bending machines include, for example, pipe bending machines, wire bending machines or also spring machines that are configured to produce bent parts in the form of springs (eg tension springs, compression springs, leg springs) by means of spring winches or spring coils. The combination with bending mold 140 and clamping device or clamping jaw 135 can be in the form of a separate forming tool. The counter-holding device can be integrated in the forming tool or can be formed by a unit separate from the forming tool, in particular by a rotatable drawing-in device of the bending machine.

Another embodiment will now be described with reference to FIGS. 8 to 11. For reasons of clarity, components that are structurally and / or functionally similar or identical to corresponding components of the arrangement in FIGS. 4 and 5 are identified by the same reference numerals.

8 and 9 show an oblique perspective view and a top view of some components of the bending machine similar to FIGS. 4 and 5. FIGS. 10 and 11 show views of the bending head of the bending machine from the feed direction, that is to say from that direction to which the material to be bent is fed.

In this exemplary embodiment, too, the feed-side 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 moved parallel to the feed direction by means of suitable controllable machine axes, but is fixed during the forming process. The counter-holding device 150 is also fixed.

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 around an axis of rotation 160 which runs parallel to the feed direction or to the feed-side section 118.

If, during the bending operation, i.e. while the bending mold 140 with the clamping jaw 135 is rotating about the bending axis 125, a twisted section is subsequently to be created after the bend 1 19, the bending mold 140 with the clamping jaw 135 applied is turned around with the aid of a rotary drive or rotary drive the workpiece longitudinal axis on the supply side (axis of rotation 160) is rotated. During this operation, the counter-holding devices 150 and the pipe wrench 180 are fixed so that the section of the workpiece lying between the pipe wrench 180 and the counter-holding device 150 is not twisted. The torsion or twisting can be initiated before, during and / or after the bending operation, as in the previous exemplary embodiments. An exemplary implementation of this functionality is now illustrated with reference to FIGS. 10 and 11 and a bending operation with torsion is explained. In the area of the bending head 100, an arcuately curved support 11 16 with an arc guide 113 is mounted on the machine frame. The bending head 100 is rotatably mounted in a suitable mounting in such a way that it can be pivoted in a predetermined angular range, for example + 45 °, about the axis of rotation 160, which runs parallel to the feed-side section 118 of the workpiece. A part of the bending head further away from the axis of rotation 160 is guided in the arc guide for this purpose.

FIG. 10 shows 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. With this position of the bending head, "normal" bends can be realized without torsion. If a twisted section is now to be produced, the bending head is pivoted machine-controlled before, during and / or after the rotation of the bending mold 140 about the bending axis 125, so that the plane which runs through the feed-side section 118 and the end section 115 runs increasingly obliquely to the x / y plane of the machine coordinate system and a twisted section is generated between the counter-holding device 115 and the bending head.

Claims

1. A method for producing a bent part from an elongated workpiece (110) by means of a bending machine which has a bending head (100) with a bending mold (140) and with a bending arm (120) rotatable about the bending mold, which has a clamping device (130) for Clamping an end section (115) of the workpiece against a peripheral section of the bending mold and being rotatable about a bending axis (125),

wherein a portion of the workpiece is brought into a starting position in the engagement area of the bending head (100),

the clamping device (130) is brought into contact with the end section and clamps the end section against a peripheral section of the bending mold (140),

a counter-holding device (150) is brought into engagement with a feed-side section (118) of the workpiece, and

in a bending operation, by rotating the bending arm (120) about the bending axis (125), a bend (1 19) is generated between the feed-side section (1 18) and the end section (1 15),

characterized in that

the counter-holding device (150) engages and / or absorbs a torsional moment on the feed-side section (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) the bending axis (125) is rotated about an axis of rotation running parallel to the longitudinal direction of the feed-side section (118) in such a way that a twisted section (111) is generated in a region (170) between the counter-holding device (150) and the bending mold (140) .

2. The method according to claim 1, characterized in that the bent part is produced from a workpiece with a rectangular cross section.

3. The method according to claim 2, characterized in that a bend (119) and a subsequent twisted section (1 11) are generated in such a way that a side surface section of a side surface (1 17) in one leg before the bend in a first Plane, a side surface portion of the same side surface (117) behind the bend defines a second plane that is oblique to the first plane, and an angle included by the planes is determined by the amount of torsion.

4. The method according to any one of the preceding claims, characterized in that the bending machine has a feed device (190) for drawing in workpiece material from a material supply, that the feed device (190) is rotatable about a feed axis (192) and that the feed device is used as a counter-holding device is produced in such a way that the feed direction is rotated about the feed axis, while with the help of the bending head (100) on the workpiece (1 10) the bend (1 19) is generated around the bending axis (125), so that between the bending head and the Feeder a twisted section (1 11) is generated.

5. Bending machine for producing a bent part from an elongated workpiece (1 10) with:

a control device;

a bending head (100) having a bending shape (140) and a bending arm (120) rotatable about the bending shape, which has a clamping device (130) for clamping an end portion (115) of the workpiece against a peripheral portion of the bending shape (140), wherein the bending arm can be rotated about a bending axis (125) by means of a bending drive controlled by the control device,

counter support means (150) upstream of the bending mold (140) and configured to be engaged with a feed side portion (118) of the workpiece to stabilize alignment of the longitudinal axis of the feed side portion during a bending operation,

characterized in that

the counter-holding device (150) is designed for introducing and / or absorbing a torsional moment on the feed-side section (118),

the counter-holding device (150) and / or the bending head (100) can be rotated about an axis of rotation (160), which runs parallel to a feed direction of the workpiece, by means of a rotary drive controlled by the control device; and

the control device is configured or configurable for this purpose, the counter-holding device (150) and / or the bending head (100) before, during and / or after rotation of the bending arm (120) about the bending axis (125) by a section parallel to the longitudinal direction of the feed-side section ( 118) rotating axis of rotation (160) in such a way that a twisted section (11 1) can be generated in an area (170) between the counter-holding device (150) and the bending mold (140).

6. Bending machine according to claim 5, characterized in that the bending machine is designed 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 (1 10) in such a way that the guide guides the feed-side section (1 18) of the workpiece in an engagement configuration on at least two opposite side surfaces.

8. Bending machine according to one of claims 5 to 7, characterized in that the bending machine has a drawing-in device (190) for drawing in workpiece material from a material supply and that the drawing-in device is rotatable about a drawing-in axis.

9. Bending machine according to claim 8, characterized in that the

Bracket device is formed by the feed device (190).