EP2329895B1 - Press brake and bending tool with holding device for a workpiece - Google Patents

Description

The invention relates to a bending press, comprising a first tool and a second tool, which are displaceable from one rest position into a pressing position against each other to apply in the pressing position a pressing force on a arranged between the first tool and the second tool workpiece, wherein at least the first tool at least a first part and a second part. Furthermore, the invention relates to a tool for a bending press comprising at least a first part and a second part (see eg EP-A-1 658 908 ).

Presses are common in modern manufacturing processes. For example, presses are used for joining (e.g., press-fitting bushings), severing (e.g., cutting sheet metal strips), master forming (e.g., pressing powders into bodies), and forming (e.g., bending or deep-drawing sheets). Even these few examples show how versatile presses are used in technology.

Because of highly automated manufacturing processes and ever increasing quality demands, high demands are placed on a press, in particular with regard to the reproducibility of the finished workpieces. Unfortunately, fluctuations in the raw material mean that this reproducibility can not always be guaranteed, even if the parameters of the press (for example, the pressing pressure or the path of the tools) are followed with a high degree of accuracy. For example, the properties of a steel sheet depend significantly on the structure, the rolling direction and the thickness of the sheet, which can unfortunately vary from sheet to sheet or within the sheet.

Due to the system, the mere control of the pressing parameters does not necessarily lead to a satisfactory result, which is especially true for bending presses, in which varying properties of the sheet can lead to large variations in the bending angle. For high quality requirements, therefore, the result, ie the finished workpiece, must be checked and, if necessary, reworked. In order not to falsify the measurement result, the workpiece must be relieved, which then springs back by a certain angle.

If, for example, a right angle is to be bent, then the workpiece must be slightly more bent because of its elasticity during the bending process.
If it now turns out that the bending angle is a little too flat, then the workpiece can be bent. Often, however, the workpiece slips when unloading in the tool or even falls out of it, so this must again be laboriously positioned before the bending process can be repeated. On the one hand, this is very time-consuming, but also prone to errors, since the workpiece can not be brought back into its original position with high probability, which significantly increases the risk of a new faulty bending.

The object of the invention is therefore to provide an improved bending press, in particular one in which a workpiece is held securely in a tool even when the pressing operation is interrupted.

According to the invention the object is achieved in a bending press according to the prior art in that the second part is movable relative to the first part in a bending press of the type mentioned above, that it remains in the pressing position, there to exert a reduced holding force against the pressing force on the workpiece, if the first part is a) in the rest position or b) in an intermediate position between rest position and pressing position.

The object of the invention is also achieved by a tool for a Biesepresse of the type mentioned, in which the second part is resiliently mounted in the first part and slidably provided in a direction of movement provided for a bending movement.

According to the invention it is achieved that a workpiece still remains in its intended for a bending operation position when this is relieved. Thus, the result of the bending operation can be easily controlled and optionally repeated if the result is unsatisfactory. The invention is suitable for bending presses, in which a discharge of the workpiece leads to a spring back of the same. Thus, on the one hand the correct bending angle can be measured on the finished unloaded workpiece, on the other hand, the bending process can be repeated or continued quickly from the same position of the workpiece, if there is a deviation of the measured bending angle of a target value.

Advantageous embodiments and developments of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.

It is advantageous if the second part is movable independently of the first part. In this way, the bending process can be made very flexible. For example, the first parts can be reduced to an arbitrary height, in order to ensure the best possible access to the workpiece, for example, when the first parts have moved far back, or to enable a quick resumption of the bending process with only a slight retraction of the first parts.

But it is also advantageous if the second part is mounted on the first part. In this way, the second part is automatically moved with the first part, which is particularly advantageous if a driver for the second part is designed such that the first and the second part are automatically aligned during the bending process. For example, a stop for the second part can be provided which is adjusted so that the first and the second part are aligned during the bending operation.

It when the second part is resiliently mounted is particularly advantageous. In this embodiment variant, the second part is still pressed against the workpiece when the first part is moved back to an intermediate position. The applied holding force decreases with increasing distance between the first and second part. The said distance is thus a measure of the applied holding force. An operator of the press can thus "visually see" the holding force. With a little practice, a certain holding power can be set specifically, if this is not already taken over by a control of the press.

It is advantageous if a coil spring, a plate spring, a leaf spring, a pneumatic suspension or a hydropneumatic suspension is provided for the suspension. These are proven and reliable means for applying a spring force and are therefore particularly suitable for the harsh operating environment of a press.

In a preferred embodiment of the bending press, the holding force of the second part is controlled such that it decreases with increasing distance between the first part and the second part.

In this way, even if the second part is driven directly, that is without the interposition of a suspension, a "virtual suspension" can be realized with the aid of a controller. In this case, the force is reduced to the second part with increasing distance between the first part and the workpiece, for example by corresponding lowering of the pressure in the relevant hydraulic cylinder, so that said distance is again an optical indicator of the holding force.

It is advantageous if the first part and the second part have the same profile. In this way, the risk can be reduced that form on the workpiece unsightly imprints or marks.

But it is also advantageous if the first part and the second part have a different profile. In this way, the second part can be produced particularly easily. Conceivable is a cylindrical pin with a hemispherical tip.

It should be noted at this point that the variants explained for the bending press according to the invention and the advantages resulting therefrom also apply mutatis mutandis to the tool according to the invention.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Fig. 1

eine Biegepresse nach dem Stand der Technik in Schrägansicht;

Fig. 2a

eine erfindungsgemäße Biegepresse, bei der sich alle Teile eines ersten Werkzeugs in einer Ruhestellung befinden;

Fig. 2b

eine erfindungsgemäße Biegepresse, bei der sich alle Teile eines ersten Werkzeugs in einer Pressstellung befinden;

Fig. 2c

eine erfindungsgemäße Biegepresse, bei der sich Teile eines ersten Werkzeugs in einer Zwischenstellung, andere in einer Haltestellung befinden;

Fig. 2d

eine erfindungsgemäße Biegepresse, bei der sich Teile eines ersten Werkzeugs in einer Ruhestellung, andere in einer Haltestellung befinden;

Fig. 3

eine Variante eines ersten Werkzeugs. bei dem die Teile unabhängig voneinander bewegbar sind;

Fig. 4

eine Variante eines ersten Werkzeugs bei dem ein zweiter Teil des Werkzeugs auf einem ersten Teil des Werkzeugs gelagert ist;

Fig. 5

eine Federung für ein erstes Werkzeug mit Hilfe von Tellerfedern;

Fig. 6

eine Federung für ein erstes Werkzeug mit Hilfe von Zugfedern;

Fig. 7

eine Federung für ein erstes Werkzeug mit Hilfe einer Blattfeder;

Fig. 8

eine pneumatische Federung für ein erstes Werkzeug;

Fig. 9

eine hydro-pneumatische Federung für ein erstes Werkzeug;

Fig. 10a

eine Seitenansicht einer ersten konkreten Ausführungsform eines erfindungsgemäßen Werkzeugs;

Fig. 10b

eine Vorderansicht einer ersten konkreten Ausführungsform eines erfindungsgemäßen Werkzeugs;

Fig. 11a

eine Vorderansicht einer zweiten konkreten Ausführungsform eines erfindungsgemäßen Werkzeugs;

Fig. 11b

eine Seitenansicht einer zweiten konkreten Ausführungsform eines erfindungsgemäßen Werkzeugs.

Each shows in a highly schematically simplified representation:

Fig. 1

a bending press according to the prior art in an oblique view;

Fig. 2a

a bending press according to the invention, in which all parts of a first tool are in a rest position;

Fig. 2b

a bending press according to the invention, in which all parts of a first tool are in a pressing position;

Fig. 2c

a bending press according to the invention, in which parts of a first tool in an intermediate position, others are in a holding position;

Fig. 2d

a bending press according to the invention, in which parts of a first tool in a rest position, others are in a holding position;

Fig. 3

a variant of a first tool. in which the parts are movable independently of each other;

Fig. 4

a variant of a first tool in which a second part of the tool is mounted on a first part of the tool;

Fig. 5

a suspension for a first tool using disc springs;

Fig. 6

a suspension for a first tool by means of tension springs;

Fig. 7

a suspension for a first tool by means of a leaf spring;

Fig. 8

a pneumatic suspension for a first tool;

Fig. 9

a hydro-pneumatic suspension for a first tool;

Fig. 10a

a side view of a first specific embodiment of a tool according to the invention;

Fig. 10b

a front view of a first concrete embodiment of a tool according to the invention;

Fig. 11a

a front view of a second concrete embodiment of a tool according to the invention;

Fig. 11b

a side view of a second concrete embodiment of a tool according to the invention.

By way of introduction, it is stated that in the differently described embodiments, identical parts are provided with the same reference numerals or identical component designations, optionally with different indices, wherein the disclosures contained in the entire description can be transferred mutatis mutandis to the same parts with the same reference numerals or component names , Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position.

The embodiments show possible embodiments of a bending press according to the invention and an inventive.

Fig. 1 shows a schematically illustrated bending press 1 'in an oblique view according to the prior art with a first, upper tool 2' and a second, lower tool 3 '. The first tool 2 'is attached to an upper pressing bar 4, the second tool 3' to a lower pressing bar 5. Both the first tool 2 ', and the second tool 3' each consist of several parts which are inserted in the respective pressing bars 4 and 5. The tools 2 'and 3' are executed divided according to the prior art, especially because individual parts are easier and thus cheaper to produce on the one hand, but also because the bending press 1 'can be optimally adjusted to a certain workpiece length. Also, the bending press 1 'equipped for various bending operations be when different tools 2 'and 3' are inserted into the press beams 4 and 5.

In this example, the upper press bar 4 by means of a drive, not shown (eg hydraulic cylinder, spindle drive, etc.) are moved vertically, in this way, the two tools 2 'and 3' from a rest position into a pressing position against each other. However, this arrangement is not absolutely necessary for the invention; on the contrary, it is also conceivable that the lower pressing beam 5 or also both pressing beams 4 and 5 are displaceable. The two pressing beams 4 and 5 are in turn connected to two C-shaped frame parts 6 and 7. In Fig. 1 is still the first tool 2 'as a stamp, the second tool 3' as a die (die) executed. Of course, it is also conceivable that the tools 2 'and 3' are mounted in reverse.

The FIGS. 2a to 2d now show a bending press 1 according to the invention with a first tool 2a, which consists of several parts 2a ₁ , 2a ₂ and 2a ₃ , and with a one-piece second tool 3. In the second tool 3, a still unshaped workpiece 8 is inserted. For a better understanding, the press 1 in the FIGS. 2a to 2d shown greatly simplified. For example, there is no pressing beam, frame and drive.

In Fig. 2a are all parts of the first tool 2a ₁ ..2a ₃ in the rest position. In Fig. 2b are all parts of the tool 2a ₁ ..2a ₃ in the pressing position. Good to see that the workpiece 8 has already been deformed here. In the Fig. 2c are the first parts 2a ₁ and 2a ₃ in an intermediate position provided between pressing position and rest position. The second part 2a ₂ is still in the pressing position, but presses with a relation to the pressing force reduced holding force on the workpiece 8. Alternatively, the first parts 2a ₁ and 2a _{3 can} also be moved to its rest position. This condition is in Fig. 2d shown.

In the in the Figures 2c and 2d As shown, the workpiece 8 is thus held in the lower tool 3, so that it can be controlled. For example, it can be checked whether the required bending angle has been achieved. In spite of accurate measurement of the pressing pressure, it is not possible or only with difficulty possible to achieve a desired bending angle, because inhomogeneities in the workpiece, for example, caused by a Rolling, or thickness differences always lead to deviations. If the bending angle is not correct, the workpiece 8, which is still held in the die, can be bent. In the Fig. 2c illustrated variant offers the advantage that the bend can be repeated relatively quickly, since the two parts 2a ₁ and 2a _{3 are} only slightly raised. In the Fig. 2d illustrated variant, however, offers the advantage of better accessibility to the workpiece. 8

Fig. 3 now shows a first variant of a first tool 2b, which in turn consists of three parts 2b ₁ ..2b ₃ . The two first, outer parts 2b ₁ and 2b ₃ correspond essentially to the prior art, the middle, second part 2b ₂ is particularly constructed. In this example, the actual punch (below) by means of a compression spring 9 is resiliently mounted on a linearly driven bar (top). The second part 2b ₂ can thus be moved independently of the other parts 2b ₁ and 2b ₃ . As soon as the punch comes into contact with a workpiece, the pressing force increases with the feed path. Of course, the spring can also be omitted and a desired pressing force on the pressure on the part 2b _{2 are} set. In the Fig. 3 the second part 2b _{2 is shown} in the pressing position. It is good to see that all three parts 2b ₁ ..2b _{3 are} aligned here.

Fig. 4 shows a further variant in which a tool 2c consists of a first part 2c ₁ , in which two second parts 2c ₂ and 2c ₃ are resiliently mounted by means of a compression spring 9. In this variant, only the first part 2c _{1 is} driven. The second parts 2c ₂ and 2c ₃ are again shown in the pressing position. Advantageously, it is structurally provided that the pressing force in the press position is transmitted from the first part 2c ₁ to the second parts 2c ₂ and 2c ₃ , for example via a stop for the parts 2c ₂ and 2c ₃ . It should be ensured that the parts 2c ₁ ..2c _{3 are} aligned, so that an optimal bending result can be achieved. If parts 2c ₁ .. 2c _{3 are} not in alignment, unsightly marks or marks may be created in the workpiece. Of course, the second parts 2c ₂ and 2c _{3 should} also be secured against falling out, so that they can not be detached from the first part 2c ₁ even in the rest position.

Fig. 5 shows a first specific embodiment of a suspension for a first tool 2d, in which a punch (below) by means of disc springs 10 resiliently on an abutment (top) is sprung. For the Fig. 5 and the following FIGS. 6 to 9 that applies the abutment as in Fig. 3 can be driven, but also as in Fig. 4 can be formed by the first part of the first tool.

Fig. 6 shows a further variant of a suspension in which the punch is mounted with tension springs 11 on an abutment.

Fig. 7 shows a further variant of a suspension in which the stamp is supported by means of a leaf spring 12 on an abutment.

Fig. 8 shows a further variant of a suspension in which the stamp is pneumatically mounted on the abutment. Here is air in a cylinder 13 a, which is compressed by a piston 13 b. By appropriate pressurization, a desired spring characteristic can be easily adjusted. Fig. 8 but can also be understood as a possible variant of a hydraulic drive. In any case, supply and discharge lines for the hydraulic oil are to be provided here, since they can not be compressed or only minimally compressed.

Fig. 9 shows a variant of a suspension in which the stamp is hydro-pneumatic mounted on the abutment. Here is hydraulic oil in a cylinder 13 a, which is displaced by a piston 13 b in a surge tank 14. There it compresses an air cushion. By appropriate pressurization, a desired spring characteristic can again be set. This variant is particularly suitable when a pneumatic suspension is desired, the space in the first tool 2h but not allow the installation of a relatively bulky pneumatic cylinder.

In the FIGS. 10a (Side view) and 10b (front view) is now a concrete embodiment of the invention shown. The Figures 10a and 10b show a first tool 2i, which in turn consists of a first part 2i ₁ and a spring-mounted therein second part 2i ₂ . For this purpose, a compression spring 9 is arranged between the first part 2i ₁ and second part 2i ₂ . The storage is accomplished by means of bolts 15, which are pushed through the first part 2i ₁ and the second part 2i ₂ . In this example, the power transmission takes place during the bending process via the bolts 15. Equally, however, it is conceivable that the upper surface of the second part 2i ₂ in the bending process on the lower surface of the first part 2i ₁ strikes and so the pressing force is transmitted. The bolts 15 would then form only for the guidance of the second part 2i ₂ , or the safeguard against falling out. In the Figures 10a and 10b is the first tool 2i inserted into a guide in the upper beam 4 and is secured there with screws 16. Furthermore, the second tool 3 is inserted into a guide in the lower pressing bar 5. Finally, between the tools 2i and 3 there is a (already bent) workpiece 8. The parts 2i ₁ and 2i _{2 of} the tool 2i are in the representation in the pressing position. If the upper pressing bar 4 is now raised, the second part 2i ₂ remains in the pressing position, while the first part 2i _{1 is} raised. Of the compression spring 9 but a decreasing holding force is exerted on the workpiece 8 until finally abut the bolt 15 at the upper end of the slots in the second part 2i ₂ and take this upwards. Advantageously, the distance of the first part 2i ₁ to the workpiece 8 is also a measure of the holding force. An operator of the press can thus "visually see" the holding force. With a little practice, a certain holding power can be set specifically, if this is not already taken over by a control of the press.

At this point it is also pointed out that even with a second part, which is driven directly (ie without suspension) can be realized by means of a controller, a "virtual suspension". The force is reduced to the second part with increasing distance between the first part and the workpiece, so that said distance is again an optical indicator of the holding force.

The FIGS. 11a (Front view) and 11b (side view) show now a final specific embodiment of the invention. Here, the second part 2j _{2 of} a first tool 2j is formed by a pin having a hemispherical tip and a thickening at the other end. In a hole 17 in the first part 2j ₁ , first a compression spring 9 and then the second part 2j _{2 is} used. Finally, a nut 18 is used as a safeguard against falling out, which has at the lower end, for example, holes or a slot for tightening. In the Figures 11a and 11b the second part 2j _{2 is shown} in the extended position. In Fig. 11b this is additionally shown in dashed lines in the retracted position. The compression spring 9 was in Fig. 11b omitted for better representation sake.

The Figures 11a and 11b show that the second part 2j ₂ does not necessarily have to have the same profile as the first part 2j ₁ . Although the second part 2j _{2 is} very easy to produce, but must be expected if necessary with impressions in the workpiece. We used the same profile for the first and second part (as in the Figures 10a and 10b ), then there is less risk, but the production of the parts may be more complex.

At this point, it should be noted that, for example, in the Figures 10a and 10b or in the Figures 11a and 11b shown tools can be combined as desired with tools of the prior art. For example, the relatively narrow tools 2i, 2j can each be arranged to the left and to the right of a longer bending tool according to the prior art, ie inserted into a guide in the upper pressing beam. Of course, several such tools 2i and 2j can be provided, for example every 50 cm.

For the sake of order, it should further be pointed out that for a better understanding of the construction of the arrangement according to the invention, these or their components have been shown partly unevenly and / or enlarged and / or reduced in size.

Of course, the above explanations for the upper tool also apply mutatis mutandis to the lower tool, i. the holding device can also be arranged below, although the better accessibility to the workpiece because of the arrangement shown should be given preference. It would also be possible to provide holding devices at the top and bottom, so that the workpiece would, as it were, "float" between the two tools.

Finally, it is noted that the invention relates to a bending press, even if the term press is used in the text. The pressing or testing process can take place both manually and automatically. For example, the bending angle of a workpiece with the help of a video camera and a corresponding image processing can be evaluated automatically.

Of course, the invention of course relates not only to presses with the illustrated C-shaped frame, but also to presses with, for example, O-shaped frame. After all the invention is independent of the nature of the drive of the press and therefore relates equally to eccentric presses, toggle presses, crank presses, screw presses, hydraulic presses, etc.

The task underlying the independent inventive solutions can be taken from the description.

REFERENCE NUMBERS

1,1 '

bending press

2a..2j, 2`

first tool

2a ₁ .. 2j ₁ , 2a ₃ , 2b ₃

first part of the first tool

2a ₂ ..2j ₂ , 2c ₃

second part of the first tool

3, 3 '

second tool

4

upper press beam

5

lower press beams

6

first frame part

7

second frame part

8th

workpiece

9

compression spring

10

Belleville spring

11

mainspring

12

leaf spring

13a

cylinder

13b

piston

14

surge tank

15

bolt

16

screw

17

blind

18

mother

Claims (9)

1. A press brake (1), comprising a first tool (2a..2j) and a second tool (3), which can be displaced relative to one another out of an inoperative position into a pressing position, so as in the pressing position to apply a pressing force onto a workpiece (8) arranged between the first tool (2a..2j) and the second tool (3), wherein at least the first tool (2a..2j) consists of at least one first part (2a₁..2j₁, 2a₃, 2b₃) and one second part (2a₂..2j₂, 2c₃),
   characterised in that
   the second part (2a₂..2j₂, 2c₃) can be moved relative to the first part (2a₁..2j₁, 2a₃, 2b₃) such that the second part (2a₂..2j₂, 2c₃) remains in the pressing position, there in order to exert a holding force, reduced relative to the pressing force, on the workpiece (8), if the first part (2a₁..2j₁, 2a₃, 2b₃) is located a) in the inoperative position, or b) in an intermediate position provided between the inoperative position and the pressing position.
2. The press brake (1) in accordance with claim 1, characterised in that the second part (2b₂) can be moved independently of the first part (2b₁, 2b₃).
3. The press brake (1) in accordance with claim 1, characterised in that the second part (2c₂, 2c₃, 2i₂, 2j₂) is mounted on the first part (2c₁, 2i₁, 2j₁).
4. The press brake (1) in accordance with one of the claims 1 to 3, characterised in that the second part (2b₂, 2j₂, 2c₃) is mounted in a sprung manner.
5. The press brake (1) in accordance with claim 4, characterised in that a coil spring (9, 11), a plate spring (10), a leaf spring (12), a pneumatic spring system, or a hydropneumatic spring system, is provided for the spring system.
6. The press brake (1) in accordance with one of the claims 1 to 5, characterised in that the holding force of the second part (2b₂) is controlled such that it reduces with increasing distance between the first part (2b₁, 2b₃) and the second part (2b₂).
7. The press brake (1) in accordance with one of the claims 1 to 6, characterised in that the first part (2a₁..2j₁, 2a₃, 2b₃) and the second part (2a₂..2j₂, 2c₃) have the same profile.
8. The press brake (1) in accordance with one of the claims 1 to 6, characterised in that the first part (2j₁) and the second part (2j₂) have different profiles.
9. A tool (2a..2j) for a press brake (1), comprising at least one first part (2a₁..2j₁, 2a₃, 2b₃) and one second part (2a₂..2j₂, 2c₃),
   characterised in that
   the second part (2a₂..2j₂, 2c₃) is mounted in the first part (2a₁..2j₁, 2a₃, 2b₃) in a sprung manner, and such that it can be displaced in a direction of movement provided for a bending process.

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