DE102017006218A1 - Apparatus and method for bending sheet-like workpieces with simultaneous pressure stress superposition - Google Patents

Abstract

The invention relates to a device (1) for bending sheet - like workpieces (2) with simultaneous compressive stress superposition, in which at least one bending platen (3, 3 ') movably arranged relative to bending supports (4) plastically deforms the sheet - like workpiece (2) one or more bending abutments (4) on one or both sides of the bending line (28) abut against the sheet-like workpiece (2) and at least individual bending abutments (4) are rotatably mounted such that these bending abutment (4) in the progressive bending of the sheet-like workpiece (2 ) between bending punch (3, 3 ') and Biegeauflagern (4) with the bending line (28) arranged portions of the sheet-like workpiece (2) synchronously with pivot, said Biegeauflager (4) such a force in the region of the bending line (28) and Apply near the bending line (28) on the sheet - like workpiece (2) that at least in the area of the bending line (28) and near the bending line (28) no Rmalspannungen (14) always perpendicular to along the bending line (2) arranged portions of the bending sheet metal workpiece (2) generated and the stresses acting there are superimposed due to the bending. Also, a corresponding method is proposed.

Description

The invention relates to a device for bending sheet-like workpieces with simultaneous compression stress superposition according to the preamble of claim 1 and a corresponding method according to the preamble of claim 27.

The bending of sheet-like workpieces is a much-needed machining task in the art, to which a variety of different methods and devices are known. In addition to the so-called free bending process, methods for bending by means of compressive stress superposition have become known, by means of which the bending deformation can be carried out more accurately and with less influence on the sheet thickness in the region of the bending radius.

For example, from the DE 10 2006 014 093 A1 It is known that after reaching a set bending angle of the bending process is interrupted. Subsequently, an arbitrarily shaped roller moves from below over the bending zone. This plasticizes the bending zone of the sheet-like workpiece and the springback of the bent workpiece is reduced. The geometry of the roll specifies the location of the compressive stress superposition. By this type of superposition but the outer arc of the bent part is deformed. This device is not able to selectively apply compressive stresses in the bending process, but superimposes pressure in each case according to the bending sequences.

In the DE 404 273 2 B4 After a complete bend, a new bending process is carried out with the aim of setting the bending angle according to load. This is achieved by compressive stress superposition over a given die after the first bend.

In the EP 0 341 211 A2 is applied via a movable counter punch a compressive stress superposition. This acts vertically from below and thus flattens the bending radius. The method is used to control the bending contour curve via the setting of the vertically acting force. The bending contour curve adjusts itself due to the free bending material and load-dependent.

From the US 3,978,706 It is known that also from below vertically pressure is exerted on the sheet metal part. This in turn leads to flattened bending radii. An alternative here is that the counterpart has a curved contour. This then has the effect of pressing the final bending radius to the die. However, this possibility is only possible for a combination of bending radius and bending angle. Likewise, the force is then introduced only shortly before the end of the bending process.

From the dissertation of Schiefenbuch [1] it is known that during bending the sheet is pressed into any kind of elastomeric pad. The elastomeric pad then brings uncontrolled and undefined compressive stresses on the sheet. The compressive stress is not controllable and adjustable. Likewise, the elastomeric pad is a wearing part and plasticized upon penetration of the punch. Therefore, this method is uneconomical. However, it could be shown that the compressive stresses introduced by the elastomeric pad delay the failure time. The increase in the deformation limits is attributed to the additional compressive stresses.

Furthermore, working in a known variant of the bending deformation with relative to the sheet-like workpiece during the forming rotating dies.

From the U.S. Patent 4,434,644 This particular type of swing bending is known. The die swings around the sheet through the rotating die assembly. At no time do compressive stresses act in the bending zone (bending radius). Only bending moments are initiated. The Gesenkkontur always serves only to specify the final contour.

In the EP 0 575 393 B1 With the kinematics used, no compressive stresses can be applied in the bending zone. If an external compressive stress were applied in the kinematics, the bending moment would be increased, but no compressive stress would be achieved in the bending arc. The kinematics can not be changed constructively.

Also at the EP 0476092 B1 the kinematics described there is not able to apply compressive stresses in the bending zone. Even with a constructive change / adaptation would only result in an increased bending moment or the risk of buckling be increased (stamp release).

The EP 2 001 615 B1 does not aim at compressive stress overlay during the process. Only compressive stresses are superimposed in the vertical direction. The damage to the sheet-shaped workpiece in the bending zone during bending forming is unavoidable. This compressive stress superimposition takes place after completed free-form bending, in order then to change the state of tension with regard to springback. This also causes an unwanted flattening of the bending zone.

In the case of free bending, no further compressive stress overlays are known. On the other hand, the known methods of compressive stress superposition are not able to set up compressive stresses in the bending zone normal to the sheet surface. In addition, most processes are tool-bound. The bending radius has a flattening in the known from the prior art method for compressive stress superposition. No process can specifically control and flexibly adjust the compressive stresses in the bending zone. Likewise, the bending radius can not be built independently of the bending angle, as in the free bending process always a free education of the radius' takes place. This radius is also not arbitrarily small possible because the radius is set freely. In addition, no method in the prior art has been concerned with using a radial compression stress superposition to increase the formability and to influence the material and stress state.

Object of the present invention is therefore to provide a method and an apparatus in which the bending deformation significantly improved by targeted pressure stress superposition in the bending zone and the bending result is optimized.

The solution of the object of the invention results in terms of the device from the characterizing features of claim 1 and in terms of the method of the features of claim 27 in each case in cooperation with the features of the associated preamble. Further advantageous embodiments of the invention will become apparent from the dependent claims.

The invention in terms of the device is based on a device for bending sheet-like workpieces with simultaneous compressive stress superposition, in which at least one bending punch movably arranged relative to the bending punch plastically deforms the sheet-like workpiece. Such a generic device is further developed in an inventive manner that single or multiple bending abutment on one side or both sides of the bending line on the sheet-like workpiece and at least individual Biegeauflager are rotatably mounted such that these Biegeauflager in the progressive bending of the sheet-like workpiece between the punch and Biegeauflagern with arranged on the bending line portions of the sheet-like workpiece synchronously with pivot, said bending abutment apply such a force in the bending line and near the bending line on the sheet-like workpiece that at least in the bending line and near the bending line normal stresses always perpendicular to along the bending line arranged portions of the bending sheet metal workpiece generated and the stresses acting there are superimposed due to the bending. By designing the mitschwenkenden Biegelager compressive stresses are selectively applied to the sheet metal workpiece to be bent in the region of the bending zone in the device according to the invention approximately via a guide with a defined pivot point. The height of the compressive stress superposition is flexibly adjustable and is also possible via the process both variably and constantly. By the targeted guidance of the sheet metal workpiece to be bent in combination with the compressive stress superposition, the same bending radius can always be guaranteed even with different bending angles. The compressive stress introduction reduces the tangential stresses in the sheet metal workpiece. By reducing the tensile stresses in the outer arch, the device according to the invention is able to extend the flexibility of especially high-strength materials. Likewise, it is possible to specifically control material damage of the sheet metal workpiece in the region of the bending zone, which are induced by the deformation, and to reduce it in comparison to conventional bending processes. The compressive stress superposition influences the failure and damage behavior of the sheet metal workpiece. Thus, the strain limits can be increased by compressive stress overlays. This is especially relevant for high and ultra-hard materials. In addition, the material damage is delayed by compressive stress superimpositions, so that correspondingly produced sheet metal workpieces perform better in the performance test. In addition, the residual stresses and the springback behavior can be positively influenced by the compressive stress superpositions. In addition, small radii (inner radius in the size of the bending punch radius) can be set independent of angle and material. The common free-bending methods form the bending radius freely and these bending radii are much larger. By means of the special design of the device according to the invention, the bending radius can be adjusted independently of the bending angle. Due to the guidance of the sheet and the pressure forces acting no more free bending takes place and the bending contour is specified. It can thus be defined defined bending radii. Compared to elastomer bending, the device is wear-free and controllable.

In a first advantageous embodiment, the non-pivotally formed bending abutment may be formed as clamping elements which clampingly support portions of the bending sheet metal workpiece. This makes it possible to perform unilateral and non-symmetrical bending operations by a first sheet metal portion of the bending line held only by clamping, but not actively bent itself, whereas an opposite sheet metal section by means of the pivoting Bending support is bent according to the invention. In this case, however, the bending abutments designed as clamping elements may possibly also perform a pivoting movement.

In another advantageous embodiment, the pivotally formed Biegeauflager are mounted so that the Biegeauflager pivot due to the force of the punch with increasing bending of the sheet metal workpiece and support the bending sheet metal workpiece. The bending punch pushes in its bending movement on the sheet metal workpiece and thus also on the pivotally formed Biegeauflager, which can retreat due to their storage against this movement of the punch and thereby perform a defined pivoting movement. The pivoting movement of the Biegeauflager and thus the bending of the voltage applied to the bending metal plate workpiece takes place synchronously, whereby the bending sections of the sheet metal workpiece are permanently supported and acted upon by the counterforce of the Biegeauflager. This counterforce of the bending abutment then generates, at least in the region of the bending zone, the normal stresses which are superimposed on the stresses prevailing in the bending zone and significantly improve the forming behavior of the sheet metal workpiece in the bending zone as described above.

In a further embodiment, the pivoting of the pivotally formed bending abutment about a pivot axis can take place, which runs along or near the bending line of the sheet metal workpiece to be bent. The bending abutments are designed and mounted so that the pivot axis is collinear or parallel adjacent to the bending line of the sheet metal workpiece to be bent and therefore in the region of the bending zone. As a result, the sections to be bent of the sheet metal workpiece are supported in the region of the bending zone and guided geometrically defined and therefore form accurate and, if desired, very small bending radii.

It is particularly advantageous if at least individual bending abutments are designed as swivel jaws, which are arranged on one side or bilaterally symmetrically the bending line pivotable. Such swivel jaws can allow a full-surface or adjacent to the actual bending zone large-scale support of the sheet metal workpiece to be bent and in the unactuated state of the device support the still flat sheet metal workpiece completely. With increasing stroke of the punch, the swivel jaws back against the punch and pivot substantially around the bend line around such that they pivot synchronously to the increasing bending of the sheet metal workpiece and the sheet metal work continuously supported at least near the bending line and lead. On the one hand, the support of the sheet metal workpiece during the entire bending process is achieved, on the other hand can be applied by the force of the swing jaws against the force of the punch the already described normal forces continuously on the sheet metal workpiece that these forces perpendicular to each changing position of the bent Run sections of the sheet metal workpiece and produce the normal stresses perpendicular to the bent portions of the sheet metal workpiece.

This continuous adaptation of the position of the swivel jaws to the respective bending state of the sheet metal workpiece can be achieved in that the swivel jaws of the bending abutments protrude into a guide carriage with an end region arranged near the bend line, with swivel jaws and guide carriages having opposite and correspondingly formed guide surfaces against which move the end portions of the Biegeauflager and the guide surface of the guide carriage with the increasing bending of the sheet-like workpiece relative to each other and support each other. The guide carriage forms a kind of forced sliding bearing of the end portions of the swivel jaws, on which the swivel jaws can be supported securely guided when the swivel jaws back against the lowering punch and pivot it. The guide carriage itself is also mounted so that it can retreat from the sinking punch, but at the same time as described can apply a force against the direction of force of the sinking punch on the pivoting jaws.

For this purpose, the guide surface of the guide carriage can be formed recessed approximately semicircular and formed the guide carriage associated end portions of the pivoting jaws at least partially semicircular protruding. The respective semicircular designs of guide carriage and swivel jaws define the pivoting movement of the swivel jaws and at the same time allow the transmission of forces from the punch to the sheet metal workpiece and the opposing forces from the guide carriage on the swivel jaws and thus also on the sheet metal workpiece.

In order to apply the opposing forces from the guide carriage to the swivel jaws, in a further embodiment the guide carriage can be loaded with a compressive force directed essentially counter to the direction of force of the bending punch, which is perpendicular to the end areas of the swivel jaws and of the swiveling bending abutments at any time via the guide surface of the guide carriage Forming area of the bending sheet-like workpiece is transferred and causes a normal stress superposition in the region of the bending line and near the bending line. In this case, in a further embodiment, the force directed counter to the direction of force of the bending punch can be generated mechanically and / or pneumatically and / or hydraulically and / or electromechanically.

Furthermore, it is conceivable that the force directed against the direction of force of the bending punch is constant or dependent on the bending state of the bending sheet metal workpiece, in particular force or path-dependent, controllable. By such a control of the opposing forces of the guide carriage on the pivoting jaws, a further influence on the bending process of the sheet metal workpiece can be achieved, for example by the reaction force is controlled depending on the force of bending force or path-dependent on the way of the punch or dependent on other geometric or material-dependent bending sizes.

Another possibility for selectively influencing the bending in the region of the bending zone can be achieved by arranging recesses or shapes, in particular pockets or projections, in the region of the installation of the sheet metal workpiece to be bent on the swivel jaws, by which the force introduction of the normal stresses can be influenced influencing normal forces in the sheet metal workpiece to be bent, in particular in the area around the bending line around concentrable. For example, directly at the bend line, e.g. radius-like projections are provided, which couple the normal forces very close to the bending line in the sheet metal workpiece and thus specifically support and burden precisely this sensitive area of the bending deformation. However, further away from the bending line area of the sheet metal workpiece can by e.g. pocket-like recesses are specifically relieved.

It is particularly advantageous if the pivot axis of the bending abutment is aligned parallel to the central axis of the punch radius of the punch, preferably collinear to the central axis of the punch radius of the punch. This makes it possible to achieve a very accurate formation of the actual bending radius. However, it is also conceivable that the pivot axis of the Biegeauflager is aligned spaced from the central axis of the punch radius of the punch, approximately parallel to the movement of the punch above or below the actual bending line. As a result, the bending behavior in the actual bending zone can be further selectively influenced and controlled.

To set an offset between the pivot axis of the bending abutment and bending line, it is conceivable that spacers or intermediate plates are arranged between Biegeauflager and along the bending line extending portions of the bending sheet metal workpiece, that the pivot axis of the Biegeauflager spaced aligned with the central axis of the punch radius of the punch. In another embodiment, however, an adjustment so between bending abutment and extending along the bending line portions of the bending sheet metal workpiece are arranged so that the distance between Biegeauflager and along the bending line extending portions of the bending sheet metal workpiece is adjustable to each other, so that the Pivot axis of the bending abutment spaced from the center axis of the punch radius of the punch is aligned.

In a further embodiment, it is also conceivable that opposing and with the pivoting jaws of the Biegeauflager cooperating clamping elements are arranged, which support together with the pivoting jaws along the bending line extending portions of the bending sheet metal workpiece and / or clamp. As a result, the sheet metal workpiece to be bent during bending is not only supported over the entire surface, but can also be supported or clamped against the swivel jaws, which can be further eliminated unwanted material displacements of the sheet metal workpiece to be bent. So it is e.g. also conceivable that the clamping elements are charged tangentially with thrust forces that transmit the clamping elements on the along the bending line extending portions of the bending sheet metal workpiece. As a result, tangential stresses can be deliberately introduced into the area of the sheet metal workpiece which act in the direction of the bending zone to or away from the bending zone and additionally influence the flow of the material in the bending zone.

In a further embodiment, it is conceivable that the pivoting jaws of the Biegeauflager in a region below the bearing surfaces for the sheet metal workpiece to be bent recesses or shapes, in particular pockets or recesses, having a larger pivot angle of the Biegeauflager to each other and thus an increase in the bendable angle of allow to be bent sheet metal workpiece. In order to produce bending angles of more than 90 °, a reduction in the mutual influence of the swivel jaws of the bending abutment is to be striven for and to ensure that even with such larger bending angles the support and power transmission between guide carriage and swivel jaws is always safe possible.

For this purpose, it is also conceivable that the pivoting jaws of the Biegeauflager such are formed, that in each case opposite comb-like sections of the bending line arranged adjacent end portions alternately interlock and the pivot jaws of the Biegeauflager thereby penetrate each other. The comb-like sections virtually interlock the penetrating end portions of the swivel jaws and therefore still allow a secure support and power transmission between the guide carriage and swivel jaws, when the swivel angle is greater than 90 °.

Furthermore, it is conceivable that the comb-like end portions of the pivoting jaws of the bending abutments are loaded by parallel to the bending line forces that cause in sheet width directions stresses in the bending areas along the bending line and superimpose the prevailing voltages there. As a result, tangential forces are applied parallel to the bending line on the sheet metal workpiece to be bent, which can additionally influence the flow of the material in the bending zone.

In another embodiment, it is also conceivable that the bending punch is formed from at least two segments which abut along the bending line on the sheet-like workpiece and are rotatably mounted, and the bending punch segments in the increasing bending of the sheet-like workpiece between the punch and Biegeauflagern with the along the bending line arranged portions of the sheet-like workpiece synchronously with pivot. In this way, a further support of the punch on the bending inner arch can be achieved by reducing any notches on the bending inner arch or even eliminate. Also, the sheet-like workpiece is additionally supported flat surface opposite to the pivoting jaws, whereby a lifting of the sheet-like workpiece can be excluded from the pivoting jaws when performing the bending operation and concomitant material deformations.

It is particularly advantageous if the bending punch segments pivot in synchronism with the axis of the bending inner arc of the bending sheet-like workpiece, as this can be achieved during the entire bending process described additional counter-support of the sheet-like workpiece. The bending punch segments pivot synchronously with the pivoting movement of the swivel jaws of the bending abutment.

To realize such a pivoting movement of the bending punch segments, it is conceivable in a further embodiment that the bending punch segments are rotatably mounted to each other in a guide surface of a punch guide, wherein the bending punch segments pivot upon bending of the bending punch guide with the bending force to each other around the bending line. This arrangement corresponds essentially to the storage and management of the swivel jaws of the Biegeauflager and is structurally simple and robust executable. The guide surface of the punch guide can also be formed approximately semicircular recessed and the bending punch guide associated end portions of the punch segments are at least partially also formed semicircular protruding.

Furthermore, it is conceivable that the bending punch segments in the region of the axis of the bending inner arc are mutually comb-like and mutually interlocking with the comb-like projections formed so that just in the area of the actual bending zone, the bending punch segments are very securely fixed to each other or formed mutually guided can.

The invention further relates to a method for bending sheet-like workpieces with simultaneous compressive stress superposition, wherein at least one relative to bending supports movably arranged bending punch plastically deforms the sheet-like workpiece, in which the sheet-like workpiece is supported on one side or both sides of the bending line of single or more Biegeauflager, the abut the sheet-like workpiece and rotate at least individual bending supports rotatably synchronized with the progressive bending of the sheet-like workpiece with arranged on the bending line portions of the sheet-like workpiece with these Biegeauflager apply such a force in the bending line and near the bending line on the sheet-like workpiece, that at least in the area of the bending line and near the bending line normal stresses always perpendicular to be arranged along the bending line sections of the bending sheet metal workpiece produce t and the stresses acting there due to the bending are superimposed. The properties and advantages of the method according to the invention have already been described in detail above for the device according to the invention, so that reference is expressly made to this.

In a further embodiment, it is conceivable that the normal stress superposition in the area of the bending line and near the bending line lies in the elastic region of the material deformation of the bending sheet metal workpiece, so that the tangential stresses in the sheet metal workpiece are reduced, but hardly takes place until no additional thinning in the sheet metal workpiece. Thus, almost identical component end geometries with different load history can be produced.

In another embodiment, it is also conceivable that the normal stress superposition lies in the region of the bending line and near the bending line in the plastic region of the material deformation of the bending sheet metal workpiece. As a result, the yield strength is exceeded and specifically the component tapers in the bending radius or predetermined a sheet thickness profile.

The method further allows by the full-surface support of the sheet metal workpiece bending of soft or slippery material, preferably forming the sheet metal workpiece in the heated state of soft metals or fiber-reinforced plastics.

Also conceivable is a temperature-assisted bending by direct heating, in particular by means of current conduction, or indirect heating, in particular by heating the device, whereby the bending of brittle and hardened metals can be improved by such a temperature-assisted bending.

A particularly preferred embodiment of the device according to the invention for bending is shown in the drawing.

• 1 - prinzipielle Darstellung der Anordnung der Bestandteile der erfindungsgemäßen Vorrichtung während der Biegeumformung eines Blechwerkstücks zwischen einem Biegestempel und einem geteilten und drehbeweglich angeordneten Biegeauflager in einer dreidimensionalen Ansicht,
• 2a-2c - ein Stadienplan der erfindungsgemäßen Vorrichtung gemäß 1 während der Biegeumformung, ausgehend von der unverformten Konfiguration des Blechwerkstücks (2a), in einem Zwischenstadium (2b) und im Endzustand der Biegeumformung( 2c) in ebener Darstellung,
• 3 - Möglichkeiten zur Verschiebung des Schwenkmittelpunktes der drehbeweglich angeordneten Biegeauflager,
• 4 - Anordnung zweier in Richtung der Biegelinie versetzt zueinander angeordneter Biegeauflager mit Aufbringung einer zusätzliche Kraft in Richtung der Biegelinie auf diese Biegeauflager,
• 5 - eine Abwandlung der erfindungsgemäßen Vorrichtung gemäß 1 mit verzahnt ineinander greifenden in Richtung der Biegelinie versetzt zueinander angeordneten Biegeauflagern zur Erzielung größerer biegbarer Winkel des Blechwerkstücks,
• 6 - eine Abwandlung der erfindungsgemäßen Vorrichtung gemäß 1 zum einseitigen Biegen mit einer als Klemmlager ausgebildeten einseitigen Einspannung des Blechwerkstücks,
• 7 - eine Abwandlung der erfindungsgemäßen Vorrichtung gemäß 1 mit einem geteilten Biegestempel, dessen Einzelteile in einer offenen Lagerschale schwenkbar angeordnet sind,
• 8 - Gestaltung der biegeliniennahen Einzelteile des geteilten Biegestempels gemäß 7 zur Vergrößerung der Anlagefläche des Blechwerkstücks an dem geteilten Biegestempel,
• 9 - Gestaltung der Anlageflächen des geteilten Biegestempels gemäß 7 mit Taschen und vorspringenden Radien im Bereich der Anlagefläche des Blechwerkstücks an dem geteilten Biegestempel,
• 10 - eine Abwandlung der erfindungsgemäßen Vorrichtung gemäß 7 mit einem geteilten Biegestempel, dessen Einzelteile stirnseitig zueinander gelagert und durch zusätzlich Kräfte belastet werden können
• 11 - eine Hälfte des geteilten Biegestempels gemäß 10 mit einer vergrößerten Darstellung der Drehlagerung und der Verzahnung zum anderen Hälfte des Biegestempels.

Show it:

• 1 - a schematic representation of the arrangement of the components of the device according to the invention during the bending deformation of a sheet metal workpiece between a bending punch and a split and rotatably mounted bending abutment in a three-dimensional view,
• 2a-2c - A stadia of the device according to the invention according to 1 during bending forming, starting from the undeformed configuration of the sheet metal workpiece ( 2a) , in an intermediate stage ( 2 B) and in the final state of the bending deformation ( 2c) in a flat representation,
• 3 Possibilities for shifting the center of rotation of the rotatably arranged bending abutments,
• 4 - Arrangement of two offset in the direction of the bending line to each other arranged bending abutment with application of an additional force in the direction of the bending line on this Biegeauflager,
• 5 - A modification of the device according to the invention 1 with interlocking intermeshing in the direction of the bending line staggered bending abutments to achieve larger bendable angle of the sheet metal workpiece,
• 6 - A modification of the device according to the invention 1 for one-sided bending with a one-sided clamping of the sheet metal work piece designed as a clamping bearing,
• 7 - A modification of the device according to the invention 1 with a split punch, the individual parts of which are pivotably arranged in an open bearing shell,
• 8th - Design of the bending line near individual parts of the split punch according to 7 to increase the contact surface of the sheet metal workpiece on the split punch,
• 9 - Design of the contact surfaces of the split punch according to 7 with pockets and projecting radii in the region of the contact surface of the sheet metal workpiece on the split punch,
• 10 - A modification of the device according to the invention 7 with a split punch, the items mounted frontally to each other and can be charged by additional forces
• 11 - one half of the split punch according to 10 with an enlarged view of the pivot bearing and the toothing to the other half of the punch.

The 1 shows a schematic representation of the arrangement of the components of the device according to the invention 1 during the bending deformation of a sheet metal workpiece 2 between a bending punch 3 and a split and rotatably mounted bending abutment 4 in a three-dimensional view. The as swivel jaws 4 trained Biegelager 4 can do this around a defined pivot point 9 swing. The swivel jaws 4 can be mirror-symmetrically identical components, each pivoting jaw 4 is formed substantially plate-shaped with a support area 7 for the sheet metal workpiece 2 and a protruding portion 6 which is approximately semicircular with a guide surface 13 is arched. This guide surface 13 is down in the direction of a guide carriage 5 before and is in a recess of the guide carriage 5 added. The here about quarter-circular radius of the swivel jaws 4 and the approximately semicircular depression 12 of the guide carriage 5 are chosen so that the swivel jaws 4 in the semicircular recess 12 of the guide carriage 5 can be twisted and the fulcrum 9 the swivel jaws 4 in the center of the stamp radius of the punch 3 lies. This will ensure that the outer bending radius of the sheet metal workpiece 2 remains constant. The guide surface 13 thus gives the contour of the bent sheet metal workpiece 2 in front. In a starting position before the deformation of the Sheet metal work 2 are the swivel jaws 4 flat on a hinge bearing 8th on, during the bending deformation, they lean on the hinge bearing 8th with increasing bending of the sheet metal workpiece 2 on the hinge bearing 8th from.

Will the punch 3 now in the feed direction 10 down to the sheet metal workpiece 2 moved, so loaded the punch 3 the sheet metal workpiece 2 and thus the swivel jaws 4 , Due to the pivotable mounting of the swivel jaws 4 in the guide carriage 5 pivot the swivel jaws 4 with this load gradually more and more, the deeper the punch 3 moves. The angle α between the two swivel jaws 4 increases, as more detailed in the 2a to 2c It can be seen that a kind of stage plan of the bending deformation of the sheet metal workpiece 2 represent. The fulcrum 9 the pivoting movement of the swivel jaws 4 remains constant, here as shown in the center of the punch radius of the punch 3 ,

Due to the bearing of the swivel jaws 4 on the hinge bearing 8th must be the guide carriage 5 with increasing lowering of the punch 3 dodge down, as in the 2a to 2c easy to recognize. Will the guide slide 5 but with this movement down with one against the punching force of the punch 3 acting force 11 applied acts on the swing jaws 4 a counter force over the guide surface 12 of the guide carriage 5 on the guide surfaces 13 the swivel jaws 4 , This drag 11 is doing by the storage of the swivel jaws 4 always so in the swivel jaws 4 initiated that these force components F _res perpendicular to the sheet plane of the deforming sheet metal workpiece 2 is directed, so as with the normal force distribution 14 indicated perpendicular to the two laterally of the bending line 28 extending support areas 7 the swivel jaws 4 extend. This normal force distribution 14 acts on the acted upon sections of the sheet metal workpiece 2 as compressive stress, which is in those sections of the sheet metal workpiece 2 superimposed on the stresses acting on the bending and the advantageous effects already described in detail above on the bending deformation and the formation of the curved contour of the sheet metal workpiece 2 causes.

The guide carriage 5 can be used to apply the counterforce 11 For example, be connected to a hydraulic cylinder, not shown. By means of such a hydraulic cylinder can then exactly the desired compression stress superposition due to the normal force distribution 14 be specified during the bending process. The force to be applied 11 However, it can also be applied by electrical or mechanical forces, for example by spring systems. Because of the force 11 can also be adjustable, the height of the normal force distribution 14 and thus the compressive stress superposition in the sheet metal workpiece 2 be set. Preferably, the normal force distribution should 14 and thus the compressive stress superposition in the elastic region of the material of the sheet metal workpiece 2 lie, so that the tangential stresses in the sheet metal workpiece 2 be reduced, but little to no additional thinning in the range of the bending radius of the sheet metal workpiece 2 takes place. Thus, almost identical component end geometries of the sheet metal workpiece 2 produced with different load history. Likewise, it is conceivable the yield strength of the material of the sheet metal workpiece 2 to exceed and targeted the sheet metal workpiece 2 in the bending radius to rejuvenate or specify a Blechdickenverlauf.

From the 1 and 2 is further evident that the additional force 11 For example, from a hydraulic cylinder always acts vertically from below, since the guide carriage 5 is guided axially. The guide surfaces 13 the swivel jaws 4 directly on the recessed guide surface 12 of the guide carriage 5 abut, can assume different shapes to concentrate the compressive stress superposition. So can a radius-shaped projection 23 are arranged directly in the region of the bending zone, chamfered in the support area of the swivel jaws 4 passes to a smaller contact surface between guide carriage 5 and swivel jaws 4 to obtain. Thus, the force is perpendicular to the punch 3 guided. The same goal is achieved in which a pocket in the guide surface 13 the swivel jaws 4 is introduced, which limits the power transmission to the forming zone. A combination of both adjustments is possible and useful.

Furthermore, it is conceivable, but not explicitly shown in the figures, that a kind of counterhold the sheet metal workpiece 2 on the receding and pivoting swivel jaws 4 presses or on the swivel jaws 4 otherwise determined. Such an anvil is not necessarily necessary because it does not force the sheet metal workpiece 2 for the bending deformation, but primarily a lifting of the outer edge regions of the sheet metal workpiece 2 should prevent. The backstop could also be like a pocket in the swivel jaws 4 be executed or introduced by attached tabs. Another variant may be the anvil with the swivel jaws 4 firmly tense. Then, by additional external forces on the anvil and thereby on the sheet metal workpiece 2 In the tangential direction an upsetting or thinning in the bending zone can be achieved.

It persists according to 3a and 3b also the possibility of the fulcrum 9 the swivel jaws 4 to shift to vary the compressive stress overlay. For this purpose, according to 3a for example between swivel jaws 4 and sheet metal workpiece 2 additionally liner sheets 18 be inserted, causing the fulcrum 9 the swivel jaws 4 towards the bending punch 3 is raised. It would also be conceivable by only schematically indicated as adjusting screws adjustment 15 the sheet metal workpiece in its position relative to the support area 7 the swivel jaws 4 to adjust ( 3b) , Furthermore, it is possible, the fulcrum 9 the Auflagerradius' of the swivel jaws 4 structurally different to arrange, ie there would be no screws 15 or liner sheets 18 necessary, the fulcrum 9 is simply defined directly by the construction, for example, 1 mm below the radius center of the punch 3 , Is the fulcrum 9 for example, exactly in the upper corner of the swivel jaws 4 , would these swing jaws 4 Do not move away from each other when lowering and thus bring in an additional compressive stress in the circumferential direction. Due to the construction you can therefore the fulcrum 9 either once firmly pretend or him by the above-mentioned possibilities of adjusting screws 15 or liner sheets 18 vary.

Furthermore, it is conceivable, according to 4 the swivel jaws 4 itself each two-piece form, with the halves of the swivel jaws 4 through a gap 17 spaced apart from each other. Touch the swivel jaws 4 the sheet metal workpiece as in 4 only partially shown on projections 16 and acts on the two halves of the swivel jaws 4 an additional in the direction of the bending line 28 acting force F _add , So compressive stresses in sheet width directions can be applied and thus the flow behavior of the material of the sheet metal workpiece 2 additionally influenced in the area of the bending zone. This gap 17 is then designed according to the elastic displacements and allows a compression stress superposition in the elastic region. Due to this compressive stress superposition, the stress state can additionally be positively influenced.

The generation of the voltage superposition described by means of the guide carriage and the swivel jaws 4 can in the in the 1 and 2 described as long as forces transmitted until the radius of the swivel jaws 4 from the guide surface 12 of the guide carriage 5 turns out. To increase this maximum bending angle of about 90 °, according to 5 the swivel jaws 4 be formed changed. For this purpose, the preceding sections 6 the swivel jaws 4 in the direction of the other pivoting jaw 4 extended and arranged so folded to each other that a kind of toothing between the swivel jaws 4 forms. This will grab the extended sections 6 the swivel jaws 4 alternately in corresponding groove-like depressions of the other of the swinging jaw 4 one, so that the swinging jaws 4 so to speak, they can turn into each other a little bit. As a result, even with larger rotations of the swivel jaws 4 still a surface contact between the guide surfaces 13 the swivel jaws 4 and the guide surface 12 of the guide carriage 5 possible and bending angle significantly above 90 °, up to about 130 ° and more are achieved. As a result, even with larger bending angles α still a voltage superposition take place.

According to the 7 It is also possible, instead of a one-piece bending stamp 3 according to 1 or 2 with a multi-part bending punch 3 . 3 ' to work, its segments 3 . 3 ' to each other by a distance 22 arranged separately in sections and also pivotable in a punch guide 20 are guided. This can analogous to the leadership of the swing jaws 4 an approximately semicircular depression 29 in the stamp guide 20 be provided, in which the segments 3 . 3 ' supported with opposite surfaces and the feed movement 10 of the stamp 3 around the angle β be pivoted. This pivoting movement about the angle β takes place due to the contact conditions synchronously with the increasing bending deformation of the sheet metal workpiece 2 like this from the 8th can be seen. The use of a split punch 3 . 3 ' has the advantage that the two parts punch 3 . 3 ' the sheet metal workpiece flat on the swivel jaws 4 Press and thus lift the sheet metal workpiece 2 from the swivel jaws 4 or other impermissible deformations of the sheet metal workpiece 2 minimize. In addition, the multi-part design increases de Biegestempels 3 . 3 ' with appropriate shaping in the area of the bending inner arch as in 8th represented the bearing surface of the sheet metal workpiece 2 at the area of the bending inner arch opposite a one-piece bending punch 3 , whereby strength-related adverse indentations of Biegeinnenbogens can be reduced or completely prevented.

Another concentration of bending forces on the sheet metal workpiece 2 and thus the compressive stress superposition in or near the bending zone can be in a multi-part bending punch 3 . 3 ' Achieve that support area between swivel jaws 4 and sheet metal workpiece 2 is shaped appropriately. For this purpose, the section of the swivel jaws closest to the bending zone can be 4 with a lead 23 be formed, adjacent to a pocket-shaped recess 24 further out, in the area no direct contact between swing jaws 4 and sheet metal workpiece 2 is present. This concentrates the normal stresses 14 on the area of the projection 23 ,

The embodiment with a split bending punch can according to 6 be used to that on the sheet metal workpiece only a one-sided bending deformation is performed. This is only one side of the bend line 28 a swivel jaw 4 and a stamp segment 3 intended. On the other side of the bend line 29 becomes this section of the sheet metal workpiece 2 in a baking-like clamping device 21 merely fixed, without being symmetrical to the other side of the bend line 29 is also bent.

The 10 and 11 show an embodiment with a split punch 3 . 3 ' , as already described, the two stamp segments 3 . 3 ' by means of a punch guide 20 pivotally actuated and synchronously to the pivoting of the swivel jaws 4 move. But in addition, as in the enlarged detail of the 11 a single swing jaw 4 better to recognize the two segments 3 . 3 ' of the punch over a lateral axle bearing 26 guided to each other and additionally by means of matching toothing 27 associated with each other. This allows it, in the direction of the bending axis 29 also axial forces on the segments 3 . 3 ' apply the bending punch, here too the flow behavior of the sheet metal workpiece 2 to influence positively in the bending zone.

The invention thus ensures a defined and variable application of compressive stresses at a nearly constant bending radius and variable bending angles.

Typically, materials with limited formability are reformed at elevated temperatures to activate additional slip planes or induce recrystallization. The inventive method allows under high compressive stresses even at room temperature, the extension of process limits (martensitic steels, magnesium alloys, titanium alloys). Although the design appears structurally simple umetzbar, the pressure-voltage superposition is made possible in a previously unknown manner by the special tool design. Due to the multiple use of high-strength metal materials, the inventive method is a future-oriented method, which is particularly important for industrial applications because of the simple tool and the flexible adjustment options.

• • Keine bekannte Lösung überlagert bisher Druckspannungen radial in der Biegezone reproduzierbar und genau einstellbar während des gesamten Biegevorgangs,
• • Bei keiner bekannten Lösung ist die Höhe der radialen Druckspannungsüberlagerung beliebig hoch einstellbar (üblicherweise Begrenzung Abflachung des Biegeteils)
• • Bei keiner bekannten Methode ist eine Druckspannungsüberlagerung in Umfangsrichtung beliebig hoch möglich, da sonst ein Ausknicken am Außenbogen auftritt

The design according to the invention is distinguished, in particular, from the prior art procedure as follows:

• • No known solution superimposed until now compressive stresses in the bending zone reproducible and precisely adjustable during the entire bending process,
• • In the case of no known solution, the height of the radial compressive stress superposition is arbitrarily high (usually limiting the flattening of the bent part)
• • In no known method, a compressive stress superposition in the circumferential direction is arbitrarily high possible, otherwise a buckling occurs on the outer bow

In none of the methods known from the prior art, compressive stresses are thus predefined by a rotating and mitwanderndes die part. Likewise, with the method according to the present invention arbitrarily high tangential compressive or tensile stresses can be introduced.

Literature:

[1] Schiefenbusch, J., 1992, Investigations to improve the forming behavior of sheet metal during bending, University of Dortmund, Dr. Ing. Dissertation.

LIST OF REFERENCE NUMBERS

1 -

contraption

2 -

Sheet metal work

3 -

punch

4 -

Bend support / swivel jaw

5 -

guide carriage

6 -

protruding section swivel jaw

7 -

Supporting area swivel jaw

8th -

Swage camp

9 -

Schenk center point swivel jaws

10 -

Feed direction Bending punch

11 -

Counterforce on guide slide

12 -

Guide surface Guide carriage

13 -

Guide surface swing jaw

14 -

normal forces

15 -

adjustment

16 -

head Start

17 -

gap

18 -

Liner sheet

19 -

toothed projections

20 -

punch guide

21 -

jaws

22 -

Distance between stamp halves

23 -

radius-shaped projection

24 -

pocket-shaped recess

25 -

axial application of force

26 -

lateral axle bearing

27 -

gearing

28 -

elastic line

29 -

Recess punch guide

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006014093 A1 [0003]
• DE 4042732 B4 [0004]
• EP 0341211 A2 [0005]
• US 3978706 [0006]
• US 4434644 [0009]
• EP 0575393 B1 [0010]
• EP 0476092 B1 [0011]
• EP 2001615 B1 [0012]

Claims (35)

Device (1) for bending sheet-like workpieces (2) with simultaneous compressive stress superposition, in which at least one relative to Biegeauflagern (4) movably arranged bending punch (3, 3 ') the sheet-like workpiece (2) plastically deformed, characterized in that individual or several bending abutment (4) on one or both sides of the bending line (28) on the sheet-like workpiece (2) and at least individual Biegeauflager (4) are rotatably mounted such that these Biegeauflager (4) in the progressive bending of the sheet-like workpiece (2) between Bending punch (3, 3 ') and Biegeauflagern (4) arranged on the bending line (28) portions of the sheet-like workpiece (2) synchronously with pivot, said Biegeauflager (4) such a force in the region of the bending line (28) and close to the Apply bending line (28) to the sheet-like workpiece (2) such that, at least in the area of the bending line (28) and close to the bending line (28), normal pl (4) are always perpendicular to along the bending line (2) arranged portions of the bending sheet metal workpiece (2) generated and superimposed on the stresses acting there due to the bending. Device (1) according to Claim 1 , characterized in that non-pivotally formed Biegeauflager (4) as clamping elements (21) are formed, the portions of the bending sheet metal workpiece (2) clamped. Device (1) according to Claim 1 , characterized in that the pivotally formed Biegeauflager (4) are mounted so that the Biegeauflager (4) due to the force of the bending punch (3, 3 ') pivot with increasing bending of the sheet metal workpiece (2) and the bending sheet metal workpiece (2) support. Device (1) according to one of the Claims 2 or 3 , characterized in that the pivoting of the pivotally formed Biegeauflager (4) about a pivot axis (9) takes place, which extends along or near the bending line (28) of the sheet metal workpiece (2) to be bent. Device (1) according to one of the Claims 2 to 4 , characterized in that at least individual Biegeauflager (4) are designed as pivoting jaws (4) which are arranged on one side or on both sides symmetrically the bending line (28) pivotally. Device (1) according to Claim 5 , characterized in that the pivoting jaws (4) of the Biegeauflager (4) with a near the bending line (28) arranged end portion (6) protrude into a guide carriage (5), wherein pivoting jaws (4) and guide carriage (5) gegengleich and corresponding formed guide surfaces (12, 13) at which the end portions of the Biegeauflager (4) and the guide surface (12) of the guide carriage (5) move in the increasing bending of the sheet-like workpiece (2) relative to each other and supported each other. Device (1) according to Claim 6 , characterized in that the guide surface (12) of the guide carriage (5) is formed recessed approximately semicircular and the guide carriage (5) associated end portions (6) of the pivoting jaws (4) are at least partially formed semicircular protruding. Device (1) according to one of the Claims 2 to 7 , characterized in that the guide carriage (5) with a substantially counter to the direction of force (10) of the punch (3, 3 ') directed pressure force (11) is resilient, via the guide surface (12) of the guide carriage (5) on the End regions (6) of the pivoting jaws (4) and of the pivoting pivoting jaws (4) at any time is transmitted perpendicular to the forming of the bending sheet-like workpiece (2) and a normal stress superposition in the bending line (28) and near the bending line (28) causes. Device (1) according to Claim 8 , characterized in that against the direction of force (10) of the punch (3, 3 ') directed force (11) is mechanically and / or pneumatically and / or hydraulically and / or electromechanically generated. Device (1) according to one of the Claims 8 or 9 , characterized in that against the direction of force (10) of the punch (3, 3 ') directed force (11) is constant or dependent on the bending state of the bending sheet metal workpiece (2), in particular force or path-dependent, controllable. Device (1) according to one of the Claims 2 to 10 , characterized in that in the region of the system of sheet metal workpiece to be bent (2) on the pivoting jaws (4) the bending abutment (4) recesses (24) or shapes, in particular pockets or projections (23) are arranged, through which the introduction of force the normal stresses causing normal forces (14) in the sheet metal workpiece to be bent (2) influenced, in particular in the area around the bending line (28) around concentrable. Device (1) according to one of the Claims 2 to 11 , characterized in that the pivot axis (9) of the bending abutment (4) parallel to the central axis of the punch radius 'of the punch (3, 3'), is preferably aligned colinearly to the central axis of the punch radius of the punch (3, 3 '). Device (1) according to one of the Claims 2 to 11 , characterized in that the pivot axis (9) of the bending abutment (4) spaced from the central axis of the punch radius of the punch (3, 3 ') is aligned. Device (1) according to one of the preceding claims, characterized in that spacers or intermediate plates are arranged between bending abutment (4) and along the bending line (28) extending portions of the bending sheet metal workpiece (2), that the pivot axis (9) of the Bend support (4) spaced from the center axis of the punch radius of the punch (3, 3 ') is aligned. Device (1) according to one of the preceding claims, characterized in that an adjusting device (15) between bending abutment (4) and along the bending line (28) extending portions of the bending sheet metal workpiece (2) is arranged, that the distance between Bend support (4) and along the bending line (28) extending portions of the bending sheet metal workpiece (2) is mutually adjustable, so that the pivot axis (9) of the Biegeauflager (4) spaced from the central axis of the punch radius of the punch (3, 3 ' ) is aligned. Device (1) according to one of the preceding claims, characterized in that opposing and with the pivoting jaws (4) of the Biegeauflager (4) cooperating clamping elements are arranged, which together with the pivoting jaws (4) along the bending line (28) extending portions holding the bending sheet metal workpiece (2) and / or clamp. Device (1) according to Claim 16 , characterized in that the clamping elements are tangentially loaded with thrust forces, which transmit the clamping elements on the along the bending line (28) extending portions of the bending sheet metal workpiece (2). Device (1) according to one of the preceding claims, characterized in that the pivoting jaws (4) of the bending abutment (4) in a region below the bearing surfaces (7) for the sheet metal workpiece (2) to be bent recesses (24) or shapes, in particular pockets or recesses, which allow a greater pivot angle (α) of the Biegeauflager (4) to one another and thus an increase of the bendable angle (α) of the sheet metal workpiece to be bent (2). Device (1) according to one of the preceding claims, characterized in that the pivoting jaws (4) of the bending abutment (4) are formed such that in each case opposite comb-like portions (19) of the near the bending line (28) arranged end portions (6) alternately engage each other and the swivel jaws (4) of the Biegeauflager (4) thereby penetrate each other. Device (1) according to Claim 19 , characterized in that the comb-like end portions (19) of the pivoting jaws (4) of the Biegeauflager (4) a transmission of compressive forces from the guide carriage (5) on the along the bending line (28) extending portions of the bending sheet metal workpiece (2) also allow for larger bending angles (α) than about 90 °. Device (1) according to one of the Claims 19 or 20 , characterized in that the comb-like end portions (19) of the pivoting jaws (4) of the bending abutment (4) by parallel to the bending line (28) extending forces are loadable, which cause tensions in the sheet bending directions in the bending areas along the bending line (28) and superimpose the tensions prevailing there. Device (1) according to one of the preceding claims, characterized in that the bending punch (3, 3 ') of at least two segments (3, 3') is formed, which rest along the bending line (28) on the sheet-like workpiece (2) and rotatably mounted such, and the bending punch segments (3, 3 ') in the increasing bending of the sheet-like workpiece (2) between bending punch (3, 3') and Biegeauflagern (4) with the along the bending line (28) arranged portions of the sheet-like Workpiece (2) synchronously with pivot. Device (1) according to Claim 22 , characterized in that the bending punch segments (3, 3 ') about the axis (9) of the bending inner bend of the bending sheet-like workpiece (2) synchronously with pivot. Device (1) according to one of the Claims 22 or 23 , characterized in that the bending punch segments (3, 3 ') in a guide surface (29) of a punch guide (20) are rotatably mounted to each other, wherein the bending punch segments (3, 3') upon application of the bending punch guide (20) with the bending force to each other pivot the bend line (28) around. Device (1) according to one of the Claims 22 to 24 , characterized in that the guide surface (29) of the punch guide (20) approximately semicircular formed recessed and the bending punch guide (20) associated end portions of the bending punch segments (3, 3 ') are formed semicircular protruding. Device (1) according to one of the Claims 22 to 25 , characterized in that the bending punch segments (3, 3 ') in the region of the axis of the bending inner bow to each other comb-like gegengleich and with the comb-like projections (27) are formed alternately interlocking. Method for bending sheet-like workpieces (2) with simultaneous compressive stress superposition, wherein at least one bending punch (3, 3 ') movably arranged relative to bending supports (4) plastically deforms the sheet-like workpiece (2), characterized in that the sheet-like workpiece (2) supported on one or both sides of the bending line (28) of individual or multiple bending supports (4), which abut the sheet-like workpiece (2) and at least individual Biegeauflager (4) rotatably in the progressive bending of the sheet-like workpiece (2) with at the bending line (28) arranged portions of the sheet-like workpiece (2) synchronously with pivot, said bending abutment (4) such a force in the region of the bending line (28) and near the bending line (28) on the sheet-like workpiece (2) apply that at least in Area of the bending line (28) and near the bending line (28) Normal stresses always perpendicular to along the bending line (28) arranged portions of the bending sheet metal workpiece (2) are generated and superimposed on the stresses acting there due to the bending. Method according to Claim 27 , characterized in that the bending abutments (4) are loaded with a force (11) directed substantially counter to the direction of force (10) of the bending punch (3, 3 ') and acting on the end regions (6) of the bending abutments (4) and the pivoting Biegeauflagern (4) is transmitted at any time perpendicular to the forming region of the bending sheet-like workpiece (2) and causes a normal stress superposition in the bending line (28) and near the bending line (28). Method according to Claim 28 , characterized in that against the direction of force (10) of the punch (3, 3 ') directed force (11) constant or depending on the bending state of the bending sheet metal workpiece (2), in particular force or path-dependent, is controlled. Method according to one of Claims 27 to 29 , characterized in that the normal stress superposition in the region of the bending line (28) and near the bending line (28) in the elastic region of the material deformation of the bending sheet metal workpiece (2). Method according to one of Claims 27 to 29 , characterized in that the normal stress superposition in the region of the bending line (28) and near the bending line (28) in the plastic region of the material deformation of the bending sheet metal workpiece (2). Method according to one of Claims 27 to 31 , characterized in that the pivoting of the pivotally formed Biegeauflager (4) about a pivot axis (9) takes place, which extends along or near the bending line (28) of the sheet metal workpiece (2) to be bent. Method according to one of Claims 27 to 32 , characterized in that the full surface support of the sheet metal workpiece (2) allows bending of soft or slack materials, preferably a forming of the sheet metal workpiece (2) in the heated state of soft metals or fiber-reinforced plastics. Method according to one of Claims 27 to 33 , characterized in that a temperature-assisted bending by direct heating, in particular by means of current transmission, or indirect heating, in particular by heating the device (1) allows Method according to one of Claims 27 to 34 , characterized in that a temperature-assisted bending allows the bending of brittle and hardened metals.

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