EP2569108B1 - Bending method and bending apparatus - Google Patents

Description

The present invention relates to a bending method and a bending device with a bending punch and a die having a bending edge. Likewise, a use of the bending process is the subject of the invention.

It is known to connect sheets with structural elements by folding. The edges of the sheets are bent by corresponding projections of the structural elements by approximately 180 °. In the usual methods, it is necessary to first edge the edges of the sheets to about 90 ° and then to e.g. Pre-roll 120 ° to 135 ° before the sheets can finally be connected by the actual folding to about 180 ° fixed to the structural element. In any case, at least three steps are required for the production of a rabbet joint. In addition, two different tools are needed for the bending step and the pre-folding step. When folding, the sheets need not necessarily be connected to a structural element. The folding can also serve to produce less sharp-edged component edges with a correspondingly reduced risk of injury.

In the DE 102 23 637 B4 a method has been proposed, with the sheets over-arched, that can be folded by an angle of more than 90 °. This should be counteracted in the first place springing back to an angle of less than 90 °. However, the proposed device is characterized by a very complex structure. From the JP 5 305342 A a bending method is known in which by moving together a die having a bending edge and a pivot member having the pivot member is brought into contact with a holding portion of a disposed between the die and the punch sheet, the pivot member is pivoted and by the pivoting of the pivot member a Bending portion of the sheet is bent around the bending edge of the die.

From the JP 5 305342 A Also, a bending device is known, comprising a bending punch and a die having a bending edge, the bending punch has a pivotally mounted pivot member having a contact portion and a forming portion, the pivot member is pivotable and, by by the pivoting of the forming a force on the bending portion of bending sheet can exert, which has an angle to the bending edge, lying in the plane of the holding portion component, the bending portion of the sheet to be bent around the bending edge of the die is bendable.

Proceeding from this, the object of the present invention is to provide a bending method with which sheet metal elements with over-arched sections can be produced in a process-reliable manner with reduced plant and cost expenditure. Likewise, a bending device is to be provided with which the bending process can be carried out. Finally, an advantageous use of the bending process is to be specified.

According to a first teaching of the invention, this object is procedurally achieved by a bending method according to claim 1.

The collapse can be ensured by a movement of the punch relative to a stationary die or a movement of the die relative to a fixed punch. But it is also conceivable to move both die and bending punch relative to each other.

It has been found that, despite the linear relative movement of the die and the bending punch, a very soft forming of the sheet is made possible by the method according to the invention. The risk of cracking during bending can thus be reduced. Above all, larger bending angles are made possible in a single operation with the method according to the invention.

A first embodiment provides that a contact portion of the pivot member is brought into contact with the holding portion of the sheet and by the pivoting of the pivot member with a forming portion of the pivot member, a force is exerted on the bending portion of the sheet, which is angled to the bending edge, in the plane having the holding portion lying component. In this way, the available power for the deformation of the sheet metal can be better utilized. It engages in a more favorable angle to the bending portion and thus allows an even softer forming of the bending section. In extreme cases, it is also conceivable to exert the force in a direction substantially perpendicular to the bending edge, lying in the plane of the holding portion direction on the bending portion of the sheet.

In a next development of the bending method, the contact section of the pivoting element is unrolled during bending on the holding section of the metal sheet. By the rolling movement, the occurrence of scratches or bruises on the surface of the holding section can be avoided. Therefore, it is conceivable to bend sheets with a very delicate, for example, a painted, chrome-plated and / or high-gloss, surface with bending process.

According to a further embodiment, the sheet is held by a hold-down on the die during bending. On In this way, a movement of the sheet during the forming process can be prevented, so that the dimensional accuracy of the bent sheet can be improved.

Furthermore, the method can be further developed by bending the bending section of the sheet by a bending angle of more than 90 °, more than 105 °, more than 120 °, up to 135 ° around the bending edge. With a bending angle of more than 90 °, sheet metal parts with a vertical fold can also be made available for a spring-back sheet metal material. Bending by a bending angle of more than 105 ° makes it possible in a particularly simple manner to arrange a structural element in the formed acute angle of 75 ° and to connect this by folding with the metal sheet. With a bending angle of more than 120 °, the subsequent folding can be considerably simplified with a slight restriction of the mounting space required for arranging a structural element. By limiting the bending angle to less than 135 °, the force required for bending can be limited to a practicable level.

In a next development of the method, a composite sheet, a solid sheet or a lightweight sheet is bent.

Composite sheets are multilayer sheets in which at least two layers are made of different materials. Typically, for example, layers of plastic are combined with metal layers. Composite sheets can result in weight savings compared to a solid sheet for the same thickness.

As composite sheets are in particular such sheets in question, which are made of two outer cover plates, for example made of steel and a connecting layer of a plastic. The thickness of the cover sheets is for example 0.30 to 2.00 mm; the thickness of the layer of plastic, for example 0.05 to 1.5 mm. Such composite sheets are characterized by a particularly high structure-borne sound attenuation. As lightweight sheets composite sheets are called, which consist of very thin, such as steel sheets, which include a plastic layer. The thicknesses of the steel sheets are 0.1 mm to 0.3 mm. As the core layer, for example, a 0.05 mm to 1.5 mm thick layer of, for example, thermoplastic material may be provided. The thermoplastic material is characterized not only by good formability, especially at higher temperatures, but can significantly simplify the production of lightweight sheet metal. A lightweight sheet offers very good stiffness especially weight advantages.

By using a solid sheet very high bending stiffness can be achieved with the same material thickness.

Furthermore, a further development provides that, after bending the bending section of the sheet, the bending section of the sheet is bent back by a second angle by a first bending angle. As a result, stresses generated in the sheet by bending can be at least partially reduced. In particular, a time-delayed delamination can be counteracted in the transition region of the holding section and bending section of a composite sheet. Under a delayed delamination is an unintentional Separating the inner cover plate and / or the outer cover plate of the composite sheet understood by the inner cover plate and the outer cover plate connecting plastic layer, which does not have to be done directly during bending, but can occur only after a certain time.

Furthermore, an embodiment of the bending process provides that the sheet is folded. The folding allows on the one hand from the sheet metal components with rounded and thus less injurious edges to produce. On the other hand, by folding, the sheet can be connected to other sheets and / or structural elements in a particularly simple manner, without the need for special fasteners such as rivets, adhesives or solders are needed. The costs and the work involved in the production of sheet metal components can thus be further reduced.

According to a second teaching of the invention, the above-mentioned object with respect to the device by a bending device according to claim 9 is achieved.

The device makes it possible to better utilize the available for the deformation of the sheet force. You can attack at a more favorable angle to the bending section to be bent, so that a softer forming can be guaranteed.

A first embodiment provides that the contact section and the forming section of the pivoting element are rigidly connected to each other. The rigid connection allows a particularly simple construction of the device and thus a cost-effective device. In addition, the reliability of the device and thus the process reliability of the bending process can be further increased by the rigid connection of the contact portion with the forming section.

Further, the device can be further, by the pivoting element is mounted with a pivot axis in the bending punch. In this way, a particularly simple construction of the bending device is made possible. It is conceivable to arrange the pivot axis stationary or movable relative to the bending punch. A pivot axis arranged movably allows a simple construction of the die of the bending punch, since this only performs a vertical movement. On the other hand, the pivot axis fixedly arranged on the bending punch simplifies the construction of the punch itself.

A next development provides that by the pivot axis in the bending punch is movable in the radial direction and the pivot member of a guide element, in particular on its outer contour, is feasible, the contact portion of the pivoting element on the bending Sheet metal is unrolled. This embodiment of the bending device allows a particularly gentle surface bending process, so that sheets with sensitive surfaces can be bent.

If in another embodiment, the pivot axis is aligned parallel to the bending edge, the bending portion of the sheet can be bent simultaneously over its entire width.

The device can also be embodied by virtue of the fact that the bending device has a hold-down device. This allows to accurately fix the holding portion of a sheet to be bent and thus to achieve a particularly high dimensional accuracy with respect to the bent sheet metal.

The bending edge of the die is provided with a recess extending along the bending edge. During bending, it comes inevitably to the inside of the sheet to a compressive load and on the outside of the sheet to a corresponding tensile load. In the recess material of the sheet can be added and thus the compressive and tensile loads are reduced. The risk of cracking on the outside can therefore be further reduced. For example, material of the inner cover plate of a composite metal sheet can be received in the transition region from the holding section to the bending section of the recess and a delamination in this area between the inner cover plate and plastic layer and / or between plastic layer and outer cover plate and plastic layer can be effected. This may increase the risk of cracking the outside lying cover plate can be reduced when folding composite sheets.

Next configured, the bending device can be characterized in that the bending edge of the die is interchangeable. The bending device can thus be easily adapted to different bending radii and different bending angles. Also in this way both bending edges with a recess running along the bending edge and bending edges which have no such recess can be used in the same bending device.

With regard to the use, the above-mentioned object has been achieved in that the bending method is used to produce a vehicle element, in particular an end wall element and / or hood element.

Fig. 1

eine schematische Darstellung eines ersten Ausführungsbeispieles einer Vorrichtung die nicht unter den Schutzbereich der Ansprüche fällt in verschiedenen Positionen;

Fig. 2

eine schematische Darstellung eines zweiten Ausführungsbeispieles einer erfindungsgemäßen Vorrichtung in verschiedenen Positionen;

Fig. 3

ein Ausführungsbeispiel einer erfindungsgemäßen Verwendung des Biegeverfahrens;

Fig. 4

eine schematische Darstellung zur Veranschaulichung eines weiteren, optionalen Schrittes des Biegeverfahrens.

In addition, the invention will be explained in more detail with reference to a drawing in conjunction with exemplary embodiments. The drawing shows in:

Fig. 1

a schematic representation of a first embodiment of a device which does not fall under the scope of the claims in different positions;

Fig. 2

a schematic representation of a second embodiment of a device according to the invention in different positions;

Fig. 3

an embodiment of a use of the bending method according to the invention;

Fig. 4

a schematic representation for illustrating a further optional step of the bending process.

In the Fig. 1 an embodiment of a bending device with a bending punch 4 and a die 2 is shown. The bending punch 4 has a pivoting element 3 with a contact section 8 and a forming section 9 rigidly connected to the contact section 8. In the Fig. 1a the state of the bending device is shown at the beginning of the bending process. A plate 6 is held with its holding portion 5 by a hold-down 10 on the die 2 that it projects laterally with its bending portion 7 on the interchangeable bending edge 1 of the die 2 addition. The sheet metal 6 shown is a solid sheet 6.

By moving together the die 2 and the bending punch 4, the contact portion 8 of the pivot member 3 is brought into contact with the holding portion 5 of the sheet 6 and the pivot member 3 is pivoted. As a result of the pivoting of the pivoting element 3, the bending section 7 of the sheet 6 is bent by a bending angle α of 130 ° about the bending edge 1 of the die 2.

The pivoting element 3 is mounted with a pivot axis 11 in the bending punch 4. The pivot axis 11 is aligned parallel to the bending edge 1. During pivoting of the pivoting element 3, the pivot axis 11 can move in the bending punch 4 in the radial direction. In this case, the pivoting element 3 is guided with a guide element 12, so that the contact portion 8 of the pivoting element 3 can roll on the holding portion 5 of the sheet 6. The

Surface of the holding portion 5 of the sheet 6 is thus protected during bending. In the embodiment shown, the guide element 12, with which the rotational movement of the pivoting element 3 is coupled to the translational movement of the pivot axis 11, formed as a stop which cooperates with the outer contour 14 of the pivoting element 3. In principle, however, other types of coupling, for example via gears and racks are conceivable.

However, the pivot axis 11 can also, as dashed lines in the Fig. 1a indicated, relative to the bending punch 4 are arranged stationary and thus a bending device with an increased rigidity are provided.

Fig. 2 shows the same bending device as Fig. 1 in which according to the invention, however, the die 2 'has a bending edge 1' with a recess 14 'extending along the bending edge 1'. The technical effect of this recess 14 'during bending is explained with reference to a composite sheet 6'.

The outer cover plates 16 ', 17' of the composite sheet 6 'are made of a steel sheet having a thickness of 400 .mu.m and connected to each other via a middle, consisting of a viscoelastic plastic layer 18' of 25 microns.

When bending the composite sheet 6 'material from the inner cover plate 16' of the composite sheet 6 'in the recess 14' flow. As a result, a delamination is effected in the transition region of holding section 5 'and bending section 7'. In other words, the inner cover plate 16 'of the plastic layer 18', over which it with the outer Cover plate 17 'was connected, separated. As a result of the material displacement into the recess 14 ', the tensile load on the outer cover plate 17' is reduced, so that the risk of occurrence of cracks in the outer cover plate 17 'is reduced after bending. This is particularly important when the composite sheet 6 'is folded in the connection.

A use according to the invention of the claimed bending method is described in the Fig. 3 illustrated. This shows a detail of a vehicle element 15 "in the form of a bonnet, which has a composite sheet 6" and a structural element 19 ". The bending section 7 '' of the composite sheet 6 '' was first according to the in Fig. 2 shown bent by a bending angle of more than 90 ° and the inner cover plate 16 '' by delamination in the transition region of holding section 5 '' and bending section 7 '' separated from the plastic layer 18 ''. In the formed acute angle of the composite sheet 6 "was then a structural element 19 '' arranged and connected by folding the composite sheet 6" this fixed to the structural element 19 ''. The outer cover plate 17 '' has no cracks even after the 180 ° fold.

In the Fig. 4 a device is shown, the bending back one with, for example, in the Fig. 1 Bender shown by a bending angle α '''bent bending portion 7''' of a sheet 6 '''by a bending angle β''' allows. These are in the present case a composite sheet 6 '''. The device has for this purpose a frame 20 ''', with which the angle β''' is given to the bending portion 7 '''of the sheet 6 '''to be bent back. The frame 20 '''serves at the same time to hold the sheet 6''' on the machine table 21 '''. In principle, however, it is also possible to provide for each of these two functions a separate device element. Further, a punch 22 '''is provided, with which the force required for bending in the sheet 6''' is initiated. The punch 22 '''is driven either hydraulically or pneumatically. However, it is also conceivable to provide an electric motor, for example a linear motor, for this purpose.

By bending back to the bending angle β '' 'following the bending of the following stresses between the inner cover plate 16' '' and the outer cover plate 17 '' 'are compensated. The thus processed sheet 6 '' 'is thus characterized by a much lower tendency for delayed delamination in the bending area.

Claims (16)

1. A bending method, in which through the closing of a die (2, 2') comprising a bending edge (1, 1') and a bending punch (4, 4') comprising a pivot element (3, 3'), the pivot element (3, 3') is brought into contact with a holding section (5, 5', 5'') of a sheet (6, 6', 6'', 6''') arranged between the die (2, 2') and the bending punch (4, 4'), the pivot element (3, 3') is pivoted through the contact with the holding section (5, 5', 5'') of the sheet (6, 6', 6'', 6''') and through the pivoting of the pivot element (3, 3') a bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6''') is bent about the bending edge (1, 1') of the die (2, 2'), wherein the die (2, 2') comprises a bending edge (1, 1') with a recess (14') running along the bending edge (1, 1').
2. The bending method according to Claim 1,
   characterized in that
   a contact section (8) of the pivot element (3, 3') is brought in contact with the holding section (5, 5', 5'') of the sheet (6, 6', 6'', 6''') and through the pivoting of the pivot element (3, 3') with a forming section (9) of the pivot element (3, 3') a force is exerted on the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6'''), which comprises a component that is located angled to the bending edge (1, 1') in the plane of the holding section (5, 5' , 5'').
3. The bending method according to any one of the Claims 1 or 2,
   characterized in that
   the contact section (8) of the pivot element (3, 3') during the bending is rolled off on the holding section (5, 5', 5''') of the sheet (6, 6', 6'', 6''').
4. The bending method according to any one of the Claims 1 to 3,
   characterized in that
   the sheet (6, 6', 6'', 6''') during the bending is held on the die (2, 2') by a hold-down (10) during the bending.
5. The bending method according to any one of the Claims 1 to 4,
   characterized in that
   the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6''') is bent about the bending edge (1, 1') of the die (2, 2') by a bending angle (α, α''') of more than 90°, more than 105°, more than 120°, up to 135°.
6. The bending method according to any one of the Claims 1 to 5,
   characterized in that
   a composite sheet, a full sheet (6, 6', 6'', 6''') or a lightweight sheet is bent.
7. The bending method according to any one of the Claims 1 to 6,
   characterized in that
   after the bending of the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6", 6''') about a first bending angle (α, α''') the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6''') is bent back by a second bending angle (β''').
8. The bending method according to any one of the Claims 1 to 7,
   characterized in that
   the sheet (6, 6', 6'', 6''') is folded.
9. A bending device for carrying out a method according to any one of the Claims 1 to 8, with a bending punch (4, 4') and a die (2, 2') comprising a bending edge (1, 1'),
   characterized in that
   the bending punch (4, 4') comprises a pivotably mounted pivot element (3, 3') with a contact section (8) and a forming section (9), in that the pivot element (3, 3') is pivotable through contact of the contact section (8) with a holding section (5, 5', 5'') of a sheet (6, 6', 6'', 6''') to be bent, in that through the pivoting the forming section (9) can exert a force on the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6'''), which comprises a component located angled to the bending edge (1, 1') in the plane of the holding section (5, 5', 5''), the bending section (7, 7', 7'', 7''') of the sheet (6, 6', 6'', 6''') to be bent is bendable about the bending edge (1, 1') of the die (2, 2'), wherein the die (2, 2') has a bending edge (1, 1') with a recess (14') running along the bending edge (1, 1').
10. The bending device according to Claim 9,
    characterized in that
    the contact section (8) and the forming section (9) of the pivot element (3, 3') are rigidly connected to one another.
11. The bending device according to any one of the Claims 9 or 10,
    characterized in that
    the pivot element (3, 3') is mounted with a pivot axis (11) in the bending punch (4, 4').
12. The bending device according to any one of the Claims 9 to 11,
    characterized in that
    by the pivot axis (11) being moveable in the bending punch (4, 4') in radial direction and the pivot element (3, 3') being guidable by a guide element (12), in particular on its outer contour (13), the contact section (8) of the pivot element (3, 3') can roll off the sheet (6, 6', 6'', 6''') to be bent.
13. The bending device according to any one of the Claims 9 to 12,
    characterized in that
    the pivot axis (11) is orientated parallel to the bending edge (1, 1').
14. The bending device according to any one of the Claims 9 to 13,
    characterized in that
    the bending device comprises a hold-down (10).
15. The bending device according to any one of the Claims 9 to 14,
    characterized in that
    the bending edge (1, 1') of the die (2, 2') is exchangeable.
16. Use of a bending method according to any one of the Claims 1 to 8 for producing a vehicle element (15"), in particular of a front wall element and/or an engine hood element.

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