DE102008003067B4 - Method and bending tool for bending a workpiece - Google Patents

Abstract

Method for bending a workpiece, in which (a) the workpiece (1) is held in a holding engagement by means of a holding device (7, 8), (b) in a bending section (3, 4) protruding in the longitudinal direction from the holding device (7, 8) ) by means of frictional engagement between bending cheeks (11, 12) clamped (c) and formed by bending, by the bending cheeks (11, 12) with the clamped bending portion (3, 4) relative to the holding means (7, 8) by means of a rotational movement a first bending cheek position are moved to a second bending cheek position, characterized in that (d) at least a predominant part of the bending force causing bending by means of a frictionally acting frictional force in the bending portion (3, 4) is introduced.

Description

The invention relates to a method for bending a workpiece according to the preamble of claim 1 and a bending tool according to the preamble of claim 13. Such a method or bending tool is made JP 2007-050 429 A known.

Automotive bodies are joined by a variety of structural elements. By reducing the joining operations costs can be saved. A reduction in the number of joined components also has a positive effect on the tolerance chain. With regard to the cost also plays a role that changes in the geometry of the structural elements, for example, from vehicle model to vehicle model, associated with costly adjustments of the production tools, especially when using complex forming processes such as deep drawing.

A cheaper compared to thermoforming forming process is the bending, but along with a limitation of the manufacturable by bending operations geometries. From the US 4,712,406 For example, there is known a bending method for producing tubular structural members that are formed into a non-circular shape by pressing straight pieces of pipe to an arcuate shape and thereby bending the contour of the mold accordingly. If structural elements are to be bent in a circle, the profile pivot bending offers itself as an inexpensive bending method. However, in relation to flat sheets, for example, the profile pivot bending and bending method of US 4,712,406 are limited to bending about an axis parallel to the plane of the sheet.

It is an object of the invention to provide a method for forming a workpiece, with which in particular a flat metal sheet or open sheet metal profile can be provided in an inexpensive manner with a running in the plane of the sheet or a leg of the sheet metal profile curvature. Furthermore, a forming tool is to be created, which is suitable for carrying out the method.

This object is achieved by a method for bending a workpiece with the features of claim 1 and a bending tool according to claim 13. Advantageous embodiments are specified in the respective dependent claims.

According to the invention, the bending force causing the bending or at least a predominant part of the bending force is introduced into the bending section by means of a frictional force acting in the frictional engagement of the bending cheeks and the bending section. In this way, workpieces whose thickness is several times smaller than their width and length can be bent about an axis orthogonal to the longitudinal direction and the width direction, that is, parallel to the direction in which the thickness of the workpiece is measured. The invention enables a bending deformation, for example, of a flat sheet around the "high edge", ie about an axis extending in the thickness direction of the sheet. Likewise, open profiles, preferably sheet-metal profiles, can be bent about an axis which is orthogonal to a leg of the profile which is flat in cross-section, by frictionally clamping the leg in question between the bending cheeks. Thus, the method is particularly suitable for bending angle profiles, such as L, T, U or double-T profiles, wherein preferably a long leg of the profile is clamped and deformed according to the invention in the plane of the respective leg by bending. Although the invention is particularly advantageous for the transformation of flat sheets and open sheet metal profiles with at least one flat leg, it is not limited thereto, but for example also suitable for round curved, preferably flat sheets or profiles with corresponding profile legs.

In preferred embodiments of the workpiece in the bending or in the case of a preferably incremental bending at each bending step, a portion of the bending section remains free of clamping forces. The workpiece has in the bending or each bending step respectively in a holding engagement with the holding device holding portion, in the bending section clamped between the bending cheeks section and between this section and the holding section on the free portion which is attributed to the bending section. The bending deformation caused by the movement of the bending cheeks into the second bending cheek position takes place at least for the most part in the free part section. Theoretically, it is conceivable that the free section in the bending forming the entire forming area of the workpiece. The workpiece, however, is stretched and thus thinned out in the tensile stress region during bending transformations in which it experiences tensile stresses in the deformation region, so that in the thinned region the frictional engagement becomes weaker and accordingly the clamping force is reduced. In bending transformations where compressive stresses occur in the forming area, it is compressed in the compressive stress area and thickened, so that the frictional connection is increased in the thickened area and accordingly the clamping force is increased. The workpiece can be claimed in the bending deformation at its outer edge on train and at the same time on its inside sheet on pressure, if indeed a neutral fiber runs inside the workpiece. Due to the differences in tension occurring in the bending region, the workpiece can also be stretched or compressed in the clamping region of the bending cheeks and in frictionally engaged holding engagement in the clamping region of the holding device. The expansion of the deformation region into the clamping region can be counteracted, for example, by an increase in the clamping force in the respective clamping region or by an increased flexibility of the clamping surfaces of the bending cheeks or the holding device. The word "or" is understood here as everywhere else in the usual logical sense, thus encompassing both the meaning of "either ... or" as well as the meaning of "and", as far as nothing else can only result from the context ,

The bending cheeks are rotationally in the bending deformation from the first bending cheek position, for example, only rotated or moved along a curved path in the second bending position. The curved path may in principle have an arbitrarily curved course, preferably the curved path is a circular arc. The curved path can, for example, by means of a cam gear, d. H. However, the bending cheeks are preferably arranged rotatable or pivotable, that is rotatable about a real and not only virtual axis of rotation rotatably, expediently with a single degree of freedom of the rotational movement in the engagement of a guideway and a guideway departing engagement member. The axis of rotation about which the bending portion of the workpiece is formed, is preferably a stationary tool axis, but in principle can also be changed in the course of the bending deformation of the place.

The bending method according to the invention is assigned to the class of the swivel bending method, but with respect to the alignment of the frictionally acting frictional force and the resulting clamping force on the one hand and the orientation of the curved path of the bending cheeks, in preferred simple embodiments of the orientation of the axis of rotation, on the other hand.

The workpiece is preferably a metal sheet and may in particular be a steel sheet or else a metal sheet of another metal alloy, for example a light metal sheet. It has a thickness of preferably at most 5 mm and preferably at least 0.5 mm, wherein the thickness can vary over the width of the workpiece in adaptation to the tensile or compressive forces occurring during the bending deformation. The width measured transversely to the thickness and the tensile or compressive forces occurring during the bending deformation is preferably not more than 20 cm, but in principle is not limited. Widths between 5 and 15 cm are particularly preferred. The length of the workpiece to be formed is arbitrary, as long as a holding by the holding device and a clamping is ensured by the bending cheeks.

The holding device holds the workpiece in a holding section with sufficient holding force so that the forming forces in the workpiece depending on the location of the axis of rotation act as tensile or compressive forces, the workpiece is thus stretched or compressed. If the axis of rotation extends through the workpiece, the workpiece undergoes tensile stress on one side of the neutral fiber and on the other side compressive stress as seen in bending over its width. The holding device holds the holding portion of the workpiece preferably by friction only by clamping. Although less preferred, it is also conceivable, in principle, for the holding device to hold the holding section in a form-fitting or both positive and frictionally engaged manner in order to absorb the tensile or compressive forces occurring during the bending deformation. The holding device can advantageously also form a side guide for the workpiece.

The bending method according to the invention is particularly suitable for the incremental bending of workpieces, in which the workpiece is bent stepwise to further bend it after performing a first bending step in at least one further bending step, preferably in several other small bending steps. The arc created by the bending deformation is thus composed of several arc increments, which are generated one after the other. After execution of a first bending deformation according to the inventive method located at this time in the second bending cheek position bending cheeks are opened and thus solved the frictional engagement with the workpiece. The bending cheeks can now be moved back to the first bending cheek position. Further, after execution of the bending step of the holding engagement of the holding device is released, preferably after the release of the frictional engagement of the bending cheeks and preferably only when the bending cheeks again occupy the first bending cheek position. In principle, the frictional engagement of the bending cheeks and the holding engagement of the holding device can also be achieved simultaneously. After the holding engagement is released, the workpiece is moved forward to a new workpiece position relative to the holding device in the direction in which the bending section protrudes from the holding device. In the new workpiece position, the holding engagement is restored, and the workpiece is now in its further from the holding device projecting bending section of the bending cheeks clamped again in frictional engagement. Then the next bending step is carried out. The successive executed bending steps can be identical to each other. In principle, however, it is also conceivable that the bending cheeks with the clamped bending section cover a longer or a shorter path than in the case of a previously performed bending step or the axis of rotation of the bending deformation is changed in place. The method according to the invention provides such flexibility, at least in principle, since it is possible to dispense with an edge to be bent or another type of installation to which the workpiece is applied during bending deformation.

In preferred simple embodiments, as already mentioned, the movement of the bending cheeks is a simple turning or pivoting movement about a rotational axis fixed for the bending tool. The turning or swiveling angle may be the same at each bending step or may be changed, for example, in adaptation to a varying thickness or material strength or a varying width in the longitudinal direction of the workpiece, which also includes the case of a variation in several of these parameters.

A bending tool suitable for carrying out the bending process has the holding device and the bending cheeks, namely a first bending cheek and at least one further, second bending cheek, between which the workpiece can be clamped in the bending section with a clamping force. The bending cheeks are rotationally movable relative to the holding device about the said axis of rotation for the bending deformation. The rotational axis may be variable in an incremental bending between successive bending steps, for example, be displaced parallel, but in preferred simple embodiments, it is stationary with respect to the bending tool. According to the invention, the axis of rotation relative to the clamping force exerted by the bending cheeks on the workpiece is parallel or at least substantially parallel, whereby a rotation axis which has an inclination of at most 30 ° to the clamping force is also considered substantially parallel.

The bending cheeks have mutually facing clamping surfaces, which are pressed for clamping against the bending portion of the workpiece in order to clamp this frictionally. The clamping engagement with the workpiece may be purely frictional, but may alternatively include a positive connection. It may be one of the bending cheeks or it may have both bending cheeks raised in their respective clamping surface upstanding embossing surfaces to stamp the workpiece in clamping engagement.

If the workpiece has in cross-section an open profile with a first leg to be clamped between the bending cheeks and a second leg, preferably a shorter leg, which has an inclination to the first leg, it is advantageous if the second leg is laterally supported during the bending deformation in order to counteract a change in the inclination, preferably to prevent a change entirely. The bending cheek in question forms in such embodiments a contact surface for the second leg. Tensile stress tends to pull the second leg toward the clamped first leg and thereby reduce the incline. A lateral support and guidance in this sense is advantageous not only for a bending with respect to the outer second leg, but also for a bending in the inner edge of the clamped first leg extending second leg. For bending, for example, a U-shaped or double-T profile in which two or four second legs extend along the middle first leg, lateral support of each of the second legs is advantageous. If a stamp of a bending cheek serving as a side guide is made in one piece, the length of the punch measured along the bending line of the workpiece and accordingly the length of the side guide is limited. To extend the side guide, segmentation of the punch is advantageous in order to extend the lateral support in the bending section.

Regardless of the question of lateral support, the clamping surface can be lengthened and thereby increased for bending open profiles by segmenting the bending cheeks. As in the case of only lateral support, the individual segments are movably connected to each other so that together they form a clamping surface following the bending contour of the workpiece. In a segmented bending cheek, all segments can form clamping surfaces for clamping the workpiece. In the case of more than two segments, alternatively, a further, third segment may have an open position on its side facing the workpiece and accordingly form no clamping surface for the workpiece, but merely serve as a lateral support. Basically, this also applies vice versa, ie one or more of the segments can also serve only as clamping segments, but not at the same time as a lateral support. When segmenting into, for example, exactly two segments, one, preferably the segment arranged nearer to the holding device, can serve as a clamping and support segment and the other segment only as a support segment or only as a clamping segment or, preferably, also as a clamping and support segment Clamping surface to the workpiece and during the Biegeumformung at any time up to the second leg of the workpiece extends. The same applies to a segmentation in more than two segments with respect to each of the segments, wherein preferably at least that of the holding device next segment is designed as a clamping segment and preferably also as a support segment.

A drive means, by means of which the rotational movement of the bending cheeks can be effected, is preferably part of the bending tool, by being supported on a base of the tool and coupled to the bending cheeks. In this way, the power flow for driving the bending cheeks is closed within the bending tool. The base on which the drive device is supported, for example, be a base plate of the bending tool, via which the tool is supported on a press. The press advantageously provides a delivery device by means of which the bending cheeks for generating the clamping force are movable toward one another and can be pressed against the bending section of the workpiece. The press can also get the parking. In one modification, the bending tool as such can be equipped with a stop device, so that a supply and Abstellinrichtung is realized either from the press or from the press in combination with the bending tool. The supply and Abstelleinrichtung preferably also worried the manufacture and release of the retaining engagement of the holding device. Further, a feed device may be provided, which moves the workpiece between the individual bending steps in each case a bit forward, preferably pushes forward on a lower part of the holding device forward. The feed device can also be supported within the bending tool or on a superordinate frame supporting the bending tool, for example the press mentioned. Finally, in preferred embodiments, in particular in embodiments for incremental bending, a control device is provided which controls the drive means of the bending cheeks, the feed device and the supply and Abstellinrichtung so that the movements are coordinated with each other by the respective institutions.

In addition to the bending method and the bending tool, the invention also relates to a component which has been shaped from the workpiece by the bending deformation according to the invention. The component is preferably used as a structural element of a vehicle, preferably in or for a motor vehicle, trucks as well as passenger cars. Instead, it can also form a structural element of a rail vehicle or an aircraft or watercraft, preferably a frame structure, or be provided for installation in such a vehicle. It may in particular be provided or installed as a body structure of a motor vehicle, for example as a longitudinal member in a motor vehicle body. Side members of motor vehicle bodies are often not only bent around one or more axes parallel to the width direction of the side member, but may also have a curved course with one or more arc portions extending around one or more axes extend, which is or are parallel to the direction in which the material thickness of the structural element is measured in each case. The bending deformation according to the invention is particularly suitable for shaping such sheets.

Further preferred features are also described in the subclaims and in the combinations of the subclaims.

Hereinafter, embodiments of the invention will be explained with reference to figures. The features disclosed in the exemplary embodiments form each individually and in each combination of features the subject-matter of the claims and also the embodiments described above. Show it:

1 a plan view of a workpiece that is formed by bending,

2 a bending tool for the bending deformation with the tensioned workpiece in a side view,

3 the bending tool with the workpiece positioned for the bending deformation in a plan view of a lower part of the bending tool,

4 the bending tool in a perspective view,

5 the bending tool in a longitudinal section,

6 a first modification of the bending tool and

7 a second modification of the bending tool.

1 shows a bending deformation, by means of a workpiece 1 by bending in several bending steps about a vertical axis Z of the workpiece 1 and thus bent around a "high edge". The workpiece 1 may in particular be a flat sheet or an open sheet metal profile, for example a U or double T-profile. For simplification purposes, it is assumed that it is a simply flat sheet. The workpiece 1 is an elongated strip in the X direction, preferably straighter Strip of arbitrary length, with a smaller width on the other hand, which is measured at right angles to the longitudinal direction X in the Y direction, and a thickness which is significantly smaller than the width which is parallel in the Z direction perpendicular to the longitudinal direction X and the transverse direction Y to the vertical axis, is measured. In bending, the workpiece becomes 1 bent about a rotation axis R, which is parallel to the vertical axis Z. One in the workpiece 1 The sheet to be formed is produced by incrementally bending in a sequence of successively executed bending steps. The workpiece 1 is moved between the bending in each case by an incremental length l in a feed direction V forward.

2 shows a bending tool in a side view with the workpiece clamped 1 , The bending tool has a base plate 6 , a cover plate 9 and between the plates 6 and 9 a holding device with a lower part 7 and a top 8th and further a rotation part 10 , In the embodiment, a pivoting part, with a first bending cheek 11 and a second bending cheek 12 on. The tool is arranged in a press, of which a press table 5 is shown and the on the cover plate 9 one towards the base plate 6 directed pressing force P exerts to the workpiece 1 both in the holding device 7 . 8th as well as in the rotation part 10 each to be clamped in a frictional engagement. In the rotation part 1 is generated by the pressing force P, a clamping force K, with the bending cheeks 11 and 12 the workpiece 1 terminals. This clamping engagement is purely frictional or based at least for the most part on frictional engagement. The frictionally acting frictional force is orthogonal to the clamping force K. The rotation part 10 is in the tensioned state relative to the base and the ceiling plate 6 and 9 and in particular to the holding device 7 . 8th pivotable about the rotation axis R. The axis of rotation R is with respect to the tool, in particular the holding device 7 . 8th stationary.

In 1 is the rotation part 10 shown in two end positions of the bending deformation, namely a first bending cheek position, the rotation part 10 takes before the bending deformation, and a second bending cheek position, in which the rotary member with 10 ' is designated and in which it is moved in the bending deformation. The workpiece 1 is for the bending forming in a holding section 2 by means of the holding device 7 . 8th curious; excited. A bending section of the workpiece 1 protrudes over the holding device 7 . 8th out in the direction of the bending cheeks located in the first bending cheek position 11 and 12 in front and is between the bending cheeks 11 and 12 clamped in frictional engagement. Between the clamping surfaces of the holding device 7 . 8th and the clamping surfaces of the rotary member 10 ie between the clamping surfaces of the bending cheeks 11 and 12 , remains in the longitudinal direction X, a free gap of length l and, accordingly, a free, unclamped section 3 , For forming the rotating part 10 by a swivel angle α of the holding device 7 . 8th Went away to the with 10 ' designated second bending cheek position. In this movement, the free section 3 over the entire clamped width of the subsection 4 the pivoting movement according to a circular arc about the rotation axis R stretched. The axis of rotation R is within the inner radius of the clamped portion 4 so that the workpiece 1 in the forming area, primarily the free section 3 forms, is claimed over the entire width only to train. The of the holding device 7 . 8th and the rotary part 10 to be absorbed tensile stresses are in 1 denoted by F.

The workpiece 1 In a sequence of incremental bending steps, which are executed one after the other, successive bending of the axis of rotation R one step at a time is performed. After each bending step, in which the rotary part 10 from the first bending cheek position in the with 10 ' designated second bending cheek position has been moved, the clamping engagement of the bending cheeks 11 . 12 solved, and the rotation part 10 with the dissolved bending cheeks 11 and 12 is placed in the first bending cheek position in 1 With 10 is designated, moved back. When the rotation part 10 again assumes the first bending cheek position, possibly even earlier, but in any case only after execution of the previous bending step, the holding engagement of the holding device 7 . 8th solved. After releasing the holding engagement, the workpiece becomes 1 moved by means of a feed device in the feed direction V to a new workpiece position. The feed corresponds to the length l of the free section 3 , The holding device 7 . 8th forms at the feed a side guide for the workpiece 1 , If the workpiece 1 takes the new workpiece position, it is by means of the holding device 7 . 8th in the on the lower part 7 now lying holding section 2 clamped in the holding engagement again, also also the clamping engagement of the bending cheeks 11 and 12 with the bending section 3 . 4 , namely in the tracked by the advancing movement section 4 , produced. Subsequently, the rotation part 10 again from the first bending cheek position to the second bending cheek position 10 ' pivoted. The sequence is repeated until in the workpiece 1 the desired arc is formed.

With the incremental swivel bending especially flat sheets and open sheet metal profiles can be formed into structural elements with a curved in the plane of the flat plate or a main leg of the profile profile, which previously had to be joined from several parts. The main leg forms in the to be formed Structural element preferably a main harness. With the method, flexibly different radii can be formed because the position of the rotation axis R in the X, Y plane relative to the workpiece 1 can be offset with little effort. Thus, as in the exemplary embodiment, the axis of rotation R may still be within the inner edge of the bending section 3 . 4 are arranged so that in the forming area everywhere only tensile stresses occur. Instead, the axis of rotation R can also run through the forming area, so that in the forming area or bending section 3 . 4 a neutral fiber is obtained outside of the primary tensile stresses during forming and within the primary compressive stresses on the workpiece 1 Act. In extreme cases, the axis of rotation R can also be displaced further outwards, so that primarily only compressive stresses occur in the forming area and the workpiece 1 over a majority of the width or over the entire width is compressed.

A practically reasonable limit for the tensile stress case is the uniform strain, which is in the most stressed on fiber stress of the workpiece 1 advantageously not exceeded. Buckling is critical for the compressive stress case. The bending deformation is preferably carried out so that these limits are not achieved and in the case of an incremental bending deformation in any of the bending steps. In most applications, it will be beneficial if the axis of rotation intersects a line representing the swivel radius in a section extending in the width direction Y from the center of the workpiece 1 to the short inner edge of the bending section 3 . 4 or, as in 1 , extending a little way inward beyond the short inner edge. The flexibility of the method is not least in the variability of the position of the axis of rotation R, so the variability of the location of the axis of rotation R both in the Y direction and transverse thereto, in the X direction, justified. A change of the location of the rotation axis R can be achieved by exchanging the rotation part 10 be realized with relatively little effort to other bending process. If necessary, the holding device 7 . 8th be repositioned in an adapted way. In the geometrical boundaries defined by the clamping surfaces of the holding device 7 . 8th and the rotary part 10 are predetermined, a variation can also be achieved by a corresponding positioning of the workpiece 1 be made relative to the bending tool. If the holding device 7 . 8th As preferred forms a side guide, this is adjusted accordingly. Also forms one of the bending cheeks 11 and 12 or form both bending cheeks 11 and 12 a side guide or on both sides of the workpiece 1 In each case a side guide, it is also possible in principle to make this side guide or side guides in an adapted manner adjustable. Other tool parameters that can be varied are the swivel angle α and the gap length l.

3 shows the workpiece 1 on the lower part 7 the holding device 7 . 8th and the first bending cheek 11 lying. The pivoting movement about the axis of rotation R is indicated by a double arrow. The bending cheek 11 indicates at its the holding device 7 . 8th facing side on an exemption, so that they despite the only small gap length l by a pivot angle α of several angular degrees, preferably at least 5 ° and preferably at most 20 °, can be pivoted. The bending cheek 12 also has such an exemption. To shear stress in the forming area of the workpiece 1 To avoid as good as possible, the axis of rotation R is in the holding device 7 . 8th facing rear portion of the rotating part 10 , arranged in the embodiment exactly on the rear edge. With such an arrangement, the rotation axis R can be avoided while avoiding the deformation area of the workpiece 1 occurring shear stresses to the workpiece 1 down to the inner edge of the workpiece 1 be moved.

4 shows the bending tool in a perspective view and in comparison with 2 greater level of detail. The cover plate 9 is along several guide columns 20 together with the top part arranged thereon 8th and the second bending cheek also disposed thereon 12 towards the base plate 6 moved back and forth. Shown is also a drive device 22 , by means of the rotational movement of the rotating part 10 about the rotation axis R is effected. The drive device 22 is formed in the embodiment as a fluidic piston / cylinder unit. A cylinder of the drive device 22 is articulated via a joint element 23 at the base plate 6 supported, and the piston is articulated via a joint element 24 with the rotation part 10 connected so that retraction and extension movements of the drive device 22 in the reciprocating rotational movement of the rotating part 10 being transformed. It is advantageous that the drive device 22 on the tool, in the embodiment of the base plate 6 supported and therefore the power flow is closed within the tool. The joint element 23 is absolutely firm with the base plate 6 connected while connecting the joint element 24 with the rotation part 10 designed so that the bending cheeks 11 and 12 relative to the hinge element 24 each on and off from each other, to the clamping engagement with the bending section 3 . 4 of the workpiece 1 to produce and solve. Apart from this flexibility are the bending cheeks 11 and 12 firmly with the joint element 24 connected.

5 shows the bending tool in the in 4 drawn section AA. As well as in 4 registered, includes the first bending cheek 11 a press plate 11a and a lower plate 11b , The press plate 11a forms the clamping surface of the bending cheek 11 and rests on the lower plate 11b on a sliding plate 14 from. The second bending cheek 12 also has a press plate 12a on which the clamping surface of the bending cheek 12 forms. The press plate 12a is on a top plate 12b arranged over feathers 13 on another top plate 12c is supported. The top plate 12c is in sliding contact with an upper slide plate 15 , The sliding plate 14 is fixed to the base plate 6 and the sliding plate 15 is fixed to the cover plate 9 connected. The division of the two with the cover plate 9 moveable bending beam 12 and the coupling of the two parts by means of the springs 13 ensures a homogenization of the over the cover plate 9 initiated pressing force P and in consequence also the frictional engagement and the distribution of the clamping force K in the rotary part 10 ( 2 ). The conditions in the holding device 7 . 8th are comparable, but it eliminates the sliding plates, since the lower part 7 firmly with the base plate 6 and the likewise split upper part 8th apart from the also between the two structural parts of the shell 8th given spring mobility fixed to the cover plate 9 connected is.

For the flexibility of the bending tool with respect to the geometry of the producible sheet is advantageous that the rotational mobility of the bending cheeks 11 and 12 is created with joints that extend at most to the clamping surface of the bending cheek 11 or 12 extend, which is supported by the respective joint, so the clamping surfaces are not broken by a hinge element of the joints. The bending cheek 11 is by means of its own swivel joint with joint elements 16 and 17 with the base plate 6 and the bending cheek 12 is by means of its own swivel joint with joint elements 18 and 19 with the cover plate 9 connected to the rotational axis R rotatably movable. The joint elements are in the case of the bending cheek 11 one at the base plate 6 supported pivot pin 16 and one with the bending cheek 11 connected rotary socket 17 , and at the joint elements 18 and 19 it is one on the cover plate 9 supported pivot pin 18 and one with the bending cheek 12 connected rotary socket 19 , The press plates 11a and 12a extend over the respective hinge connection 16 . 17 and 18 . 19 time.

The 6 and 7 show two modified embodiments for the rotary part 10 , Shown is in each case a modified bending cheek 12 , The modification consists in that in the embodiment of the 4 and 5 simply plane press plate 12a is replaced by a segmented stamp. The segmentation is advantageous for the bending deformation of a profiled workpiece 1 , The profiled workpiece 1 has a wide first leg 1a and a comparatively narrower second leg 1b on, along the outer edge of the workpiece 1 from the first stamp 1a rises at right angles. The workpiece 1 is in 8th shown in profile. By segmenting a larger clamping surface can be created. Furthermore, the second leg 1b be supported laterally inwardly during bending deformation and thus a reduction in the inclination due to the tensile stress occurring during the bending deformation can be prevented.

6 shows schematically in plan view a second bending cheek 12 with one of sliding segments 25a - 25d composite stamp. The sliding segments 25a - 25d are connected to each other so that they relative to each other, the bending contour of the bending section 4 following are mobile. That of the holding device 7 . 8th next arranged stamp segment 25a is with the shell 12b . 12c the bending cheek 12 firmly connected. The other segments 25b -D are over the segment 25a with the shell 12b . 12c slidingly connected. The segments 25a -D are in 6 schematically represented as rectangles, in the real tool, however, they are to the bending contour in the bending section 3 . 4 adapted shaped, leaving a flat bearing and side guide for the second leg 1b is obtained. If the workpiece 1 a U- or double-T-profile and accordingly has at its inner edge a further second leg, this also applies to the inner sides of the segments accordingly 25a d.

In the modification of 7 has the second bending cheek 12 a segmented punch with punch segments 26a -F, which are each pivotally connected to each other. That of the holding device 7 . 8th next adjacent stamp segment 26a is again stuck to the top 12b . 12c the bending cheek 12 connected, and the other stamp segments 26b -F are above the stamp segment 26a movable with the shell 12b . 12c connected. The moving segments 26b -F are supported by a sliding plate on the upper part of the bending cheek 12 from. Incidentally, this applies to the sliding segments of the 6 Said.

LIST OF REFERENCE NUMBERS

1

workpiece

1a

long thigh

1b

short thigh

2

holding section

3

bending section

4

bending section

5

press table

6

baseplate

7

Holding device, lower part

8th

Holding device, upper part

9

cover plate

10

rotating part

11

first bending cheek

12

second bending cheek

12a

Press plate, stamp

12b

top

12c

top

13

feather

14

sliding plate

15

sliding plate

16

joint element

17

joint element

18

joint element

19

joint element

20

guide column

21

22

driving means

23

joint element

24

joint element

25a-d

segments

26a-f

segments

F

traction

K

clamping force

P

Press force

R

axis of rotation

V

feed direction

r _a

outer radius

X, Y, Z

Workpiece axes

α

swivel angle

β

Tilt

Claims (22)

Method for bending a workpiece, in which (a) the workpiece ( 1 ) by means of a holding device ( 7 . 8th ) held in a holding engagement, (b) in one of the holding device ( 7 . 8th ) projecting in the longitudinal direction bending section ( 3 . 4 ) by means of frictional engagement between bending cheeks ( 11 . 12 ) is clamped (c) and formed by bending by the bending cheeks ( 11 . 12 ) with the clamped bending section ( 3 . 4 ) relative to the holding device ( 7 . 8th ) are moved by means of a rotational movement from a first bending cheek position to a second bending cheek position, characterized in that (d) at least a predominant part of the bending force causing bending by means of a frictionally acting frictional force in the bending portion ( 3 . 4 ) is initiated. Method according to the preceding claim, in which the workpiece ( 1 ) after bending relative to the holding device ( 7 . 8th ) in the direction in which the bending section ( 3 . 4 ) of the holding device ( 7 . 8th ) protrudes forward to a new workpiece position and is further bent by repeating steps (a) to (d). Method according to one of the preceding claims, in which (e) the frictional engagement of the bending cheeks ( 11 . 12 ) is released in the second bending cheek position, (f) the bending cheeks ( 11 . 12 ) are moved back into the first bending cheek position, (g) the holding engagement of the holding device ( 7 . 8th ) (h) and the workpiece ( 1 ) relative to the holding device ( 7 . 8th ) in the direction in which the bending section ( 3 . 4 ) of the holding device ( 7 . 8th ) is moved forward to a new workpiece position (i) and wherein steps (a) to (d) for incremental bending at the workpiece in the new workpiece position (FIG. 1 ) be repeated. Method according to one of the preceding claims, in which between a retaining portion ( 2 ) of the workpiece ( 1 ) and one between the bending cheeks ( 11 . 12 ) clamped subsection ( 4 ) of the bending section ( 3 . 4 ) a free section ( 3 ) of the bending section ( 3 . 4 ) remains, in which at least a majority of the bending deformation takes place when the bending cheeks ( 11 . 12 ) are moved to the second bending cheek position. Method according to one of the preceding claims, in which the bending section ( 3 . 4 ) in the bending deformation about an axis of rotation (R), preferably a relative to the holding device ( 7 . 8th ) Fixed axis of rotation (R), stretched or compressed. Method according to one of the preceding claims, in which the bending section ( 3 . 4 ) is stretched or compressed during bending about an axis of rotation (R) which is at least substantially orthogonal to that in the frictional engagement with the bending section (R). 3 . 4 ) acting frictional force extends. Method according to one of the preceding claims, in which as the workpiece ( 1 ) uses a flat sheet or open sheet profile, the flat sheet or a leg ( 1a ) of the sheet metal profile flat between the bending cheeks ( 11 . 12 ) and about a in the thickness direction of the flat sheet or the clamped leg ( 1a ) extended axis of rotation (R) is bent. Method according to one of the preceding claims, in which the workpiece ( 1 ) of at least one of the bending cheeks ( 11 . 12 ) is coined in the frictional connection. Method according to one of the preceding claims, wherein at least one of the bending cheeks ( 11 . 12 ) along a bending line of the workpiece ( 1 ) into segments ( 25a -d; 26a -F) which is adapted in adaptation to a bending of the bending section ( 3 . 4 ) are movably connected to each other, and in which at least two of the segments in bending against the workpiece ( 1 ) to clamp this. Method according to one of the preceding claims, in which the workpiece ( 1 ) is profiled with a first leg ( 1a ), in the frictional connection of the bending cheeks ( 11 . 12 ) and one along the first leg ( 1a ) with a slope (β) projecting second leg ( 1b ) for preventing a change in the inclination (β) in the bending of one of the bending cheeks ( 11 . 12 ). Component, preferably an open sheet-metal profile, which in a method according to one of the preceding claims consists of the workpiece ( 1 ) was bent. Component according to the preceding claim, characterized by the use as a structural element of a vehicle, preferably as a body structure of a motor vehicle or frame structure of an aircraft or watercraft. Bending tool, comprising: (a) a holding device ( 7 . 8th ) for holding a workpiece ( 1 ), (b) a first bending beam ( 11 ) and a second bending cheek ( 12 ) between which one of the holding device ( 7 . 8th ) projecting bending section ( 3 . 4 ) of the workpiece ( 1 ) is clamped with a clamping force (K), characterized in that (c) the bending cheeks ( 11 . 12 ) for bending relative to the holding device ( 7 . 8th ) are rotationally movable about an axis of rotation (R) having an inclination of at most 30 ° to the clamping force (K). Bending tool according to the preceding claim, characterized in that the second bending beam ( 12 ) in the direction of the clamping force (K) on the first bending cheek ( 11 ) and against the bending section ( 3 . 4 ) is pressable. Bending tool according to one of the preceding claims, characterized in that at least a predominant part of the bending force causing bending by means of one of the clamping force (K) generated frictional engagement in the bending section ( 3 . 4 ) is initiated. Bending tool according to the preceding claim, characterized in that the axis of rotation (R) at least substantially orthogonal to one in the frictional engagement with the bending section (FIG. 3 . 4 ) acting frictional force extends. Bending tool according to one of the preceding claims, characterized in that at least one of the bending cheeks ( 11 . 12 ) along a bending line of the workpiece ( 1 ) into segments ( 25a -d; 26a -F) is segmented, which in adaptation to a bendable by the bending of the bending section ( 3 . 4 ) are movably connected to each other, wherein at least one of the segments for clamping and introducing the bending force against the bending portion ( 3 . 4 ) is pressable. Bending tool according to one of the preceding claims, characterized in that the workpiece ( 1 ) is profiled with a first leg ( 1a ) and one along the first leg ( 1a ) with a slope (β) projecting second leg ( 1b ), the first leg ( 1a ) flat between the bending cheeks ( 11 . 12 ) lying by means of bending cheeks ( 11 . 12 ) is clamped and the second leg ( 1b ) of one of the bending cheeks ( 11 . 12 ) is laterally sustainable, to counteract a change in the inclination (β). Bending tool according to one of the preceding claims, comprising a feed device, by means of which the workpiece ( 1 ) relative to the holding device ( 7 . 8th ) in the direction in which the bending section ( 3 . 4 ) of the holding device ( 7 . 8th ) protrudes, can be moved on. Bending tool according to one of the preceding claims, comprising a drive device ( 22 ) for a reciprocating drive of the bending cheeks ( 11 . 12 ) about the axis of rotation (R). Bending tool according to a combination of the two preceding claims, characterized in that a supply and Abstelleinrichtung for releasing and producing a retaining engagement of the holding device ( 7 . 8th ) and a clamping engagement of the bending cheeks ( 11 . 12 ) and a control device for a coordinated control of the feed device, the drive device ( 22 ) and the supply and Abstelleinrichtung are provided, wherein the control device is adapted to the feed device, the drive means ( 22 ) and the supply and Abstelleinrichtung for carrying out the method according to claim 2 or 3 coordinated to control. Bending tool according to one of the preceding claims, comprising a lower part ( 6 . 14 ), on which the first bending cheek ( 11 ) and an upper part ( 9 . 15 ), on which the second bending cheek ( 12 ) is arranged, further a rotary joint ( 16 . 17 ) for a hinged connection of the first bending cheek ( 11 ) with the lower part and a rotary joint ( 18 . 19 ) for a hinged connection of the second bending beam ( 12 ) with the upper part, whereby the rotational joints in each case of joint elements ( 16 . 17 . 18 . 19 ) are formed, which extend from the lower part or the upper part to at most one of the respective associated bending cheek ( 11 . 12 ), so that none of the hinge elements projects beyond one of the clamping surfaces in the direction of the respective other clamping surface.

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