EP1309414B1 - Method for operating a bending press and bending press, especially a folding bending press - Google Patents

Abstract

A method of operating a bending press, in particular an edging press, and a bending press for carrying out this method. For each drive of a drive arrangement, the actual pressing force is detected for the displaceable press beam during a bending process for the workpiece and a relative position of the pressing tool or tools by reference to the longitudinal extension of the press beams is determined on the basis of a force ratio. Different displacement paths of the drives and the displaceable press beam at the respective force-application point of the drive are then determined in an evaluation and/or computer unit, which is provided with a data memory for production and machine data, and corresponding control signals for the drive system are generated in the control unit and actuator elements of the drives are displaced by the displacement paths determined for each drive.

Description

The invention relates to a method for operating a bending press, as described in the preamble of claim 1, but also a bending press for performing the method, as described in the preamble of claim 12.

From the document JP 06-328137 A, a press brake with a fixed and an over at least two especially formed by hydraulic cylinder drives adjustable equipped with bending tools press bar is known. Furthermore, the known press brake on a control and regulating device and detection means, by means of which an eccentric load, which causes an asymmetrical deformation of the bending beam, is determined and from this load according to the control and regulating device or stored in a memory machine-related data, the Determining the extent of deformation by means of these data and the adjustment process taking into account the deviation calculated by the deformation to a given to achieve a predetermined bending angle on the workpiece, ie a theoretically predetermined immersion depth of the bending tools, with corrective measures in the adjustment of the adjustable bending beam during the forming process, So in real time, be made by the control and regulating device and the accordingly driven drives. According to this known embodiment of the adjustable bending beam is adjusted with the bending tools with respect to the fitted with the bending tools fixed bending beam to a theoretical immersion depth.

From DE 693 09 610 T2 a method and an apparatus for measuring and adjusting the pressing forces on a press are known. According to this method and apparatus, pressing force values are measured and adjusted to achieve a predetermined local load distribution to set the desired local load distribution regardless of the specific characteristics of the press.

In order to achieve exact forming angles on a work piece produced on a bending press, in particular on a press brake, the work piece is to measure the bending angle, in particular, by means of measuring methods after the forming has been completed, and after the insertion depth of the pressing tools detected by a distance measuring system, a necessary correction of the Bending angle by changing the immersion depth in order to allow for subsequent forming operations the predetermined bending angle to reach. After such an approach, in which the Wegemeßsystem is arranged to take into account the force-dependent springing of the C-shaped machine side stand on its own subframe, fall production defects due to the force-related and dependent on the position of the working area on the press bar bending behavior of the press bars.

From DE 39 21 034 A1 discloses a device for preventing inaccuracies in the production, due to the bending behavior of the press beams, known by the occurring bending lines of the cooperating press bars approximately at the time of maximum, required for the bending angle of the workpiece submergence depth of Tools in approximately parallel or concentric to each other. However, this can not take into account unbalanced bending stress due to an eccentric load, which can lead to production losses due to rejects or to eliminate advantageous production possibilities which are often given in the case of off-center use of the pressing tools.

The object of the method according to the invention is to control adjustment paths of a drive arrangement having at least two drives as a function of deformations of both the machine frame and the interacting press beams caused by the pressing forces.

This object of the invention is solved by the features of claim 1. The surprising advantage is that regardless of the relative position of the working or forming area with respect to the longitudinal extent of the press beams and the resulting uneven distribution of the compressive forces on the drives the asymmetric bending lines of the press bars, but also different suspensions of each distanced and have the drives having side stand result, these production quality affecting factors are compensated by regulating the adjustment for the respective drive in response to this load-specific deformation behavior and the decisive for the quality of deformation, uniform over a whole forming range immersion depth of the dies is achieved.

In this case, an embodiment according to claim 2 is advantageous, because a rapid adaptation of adjustment paths in the drives for correcting an angular position that occurs is advantageous Bending tools is achieved to each other.

But also advantageous is an embodiment according to claim 3, because thereby the effective load conditions are implemented in a real calculation in measures for adjusting the drives and inaccuracies resulting from a gradation in a matrix are turned off.

Also possible is a measure as described in claim 4, because this material-specific data are available and thus an adaptation of the manufacturing parameters to the respective materials to be processed quickly.

Also advantageous are measures according to claims 5 and 6, which machine-specific data received directly into the determination of the adjustment of the drives and thus takes place a compensation of the machine deformation.

Further measures are advantageous, as described in claims 7 and 8, whereby the determination of the adjustment paths per drive via instantaneous value calculation, whereby extensive files, the time-consuming searches entail, be avoided and the results beyond the effectively occurring loads and thus associated deformations of the machine stand, press beams, so correspond to the force-related effects on the bending press.

According to the advantageous measure described in claim 9, the possibility is created, based on the results of the deformation measurements on essential machine parts, such as the stator side walls, to determine the distribution of forces on the drives and thus the resulting and expected deformations and the stored machine data or by computational methods with the given algorithms, the required control functions, such. B. to determine the different adjustment paths per drive.

According to the further advantageous measures, as described in the claims 10 and 11, a permanent monitoring with counter-control of the entire manufacturing process by the actual / target comparison of the most essential, decisive for the manufacturing quality influences is achieved.

The object of the invention is also to provide a bending press, are compensated by suitable countermeasures in the machine deformation, as they occur due to the force in a forming process to increase the quality of manufacture.

This object of the invention is solved by the features of claim 12. The surprising advantage of this is that depending on the position of the forming tools and thus different load distribution of the machine frame adjustment paths of the drives are moved independently of each other and thus the adjustable press bar during the working stroke compensates for deviations in the position of the cooperating press tools, which results from a machine deformation ,

Finally, embodiments as described in claims 13 and 14 are advantageous, whereby a monitoring of the actual values of the adjustment paths to target values from the specification is achieved and set corrective action and present in subsequent operations to optimize the manufacturing process.

For a better understanding of the invention, this will be explained in more detail with reference to the embodiments shown in FIGS.

Fig. 1

eine erfindungsgemäße Biegepresse in Ansicht;

Fig. 2

die Biegepresse in Seitenansicht;

Fig. 3

eine schematische Darstellung der Verformungsverhältnisse an einer Biegepresse.

Show it:

Fig. 1

a bending press according to the invention in view;

Fig. 2

the bending press in side view;

Fig. 3

a schematic representation of the deformation conditions on a bending press.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals and component names. Also, the position information selected in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to a new position analogous to the new situation. Furthermore you can Also represent individual features or combinations of features from the illustrated and described different embodiments of their own, inventive or inventive solutions.

1 and 2 is a manufacturing device 1, in particular press brake 2, for the forming of sheet metal parts 3, for example, to housing parts 4, profiles, etc., shown. To achieve the highest possible product quality, a number of factors dependent on the production device 1 are to be taken into account. The quality of the forming depends decisively from a over the entire Umformlänge or a tool length uniformly extending immersion depth of the cooperating tools, which is influenced by force-induced deformation of the manufacturing device 1, such as a springing or bending deformation of essential parts of the press brake 2.

A machine frame 5 of the production device 1 consists essentially of two parallel and spaced apart, C-shaped stator side cheeks 6, 7, which are e.g. in particular installation conditions for vibration damping via damping elements or predominantly supported directly on a footprint 9 or, as possible, attached to a common base plate 10, in particular welded to this. Furthermore, the stator side walls 6, 7 are connected to one another at a distance 11 by wall parts 13 running perpendicular to a center plane 12.

With respect to a working plane 14 extending parallel to the footprint 9, the manufacturing device 1 comprises two opposing press beams 15, 16 which extend over a length 17, generally of the intended machine size or working length for bending the sheet metal parts 3 , eg to the housing parts 4, is fixed.

The contact surface 9 facing the press beam 15 is attached via a support and / or mounting assembly 19 on the machine frame 5, preferably directly to end faces 20 of the bottom plate 10 associated legs 21 of the C-shaped stator side walls 6, 7 by bolts or welding. At the end faces 22 of the spaced apart from the footprint 9 legs 23 shield plates 24 are optionally arranged to the footprint 9 in a vertical plane, which are preferably connected by welds with the stator side walls 6, 7. These shield plates 24 and the stator side walls 6, 7 are provided with guide assemblies 25, via which the other, the press beam 15 with respect to the working plane 14 opposite press beams 16 - according to a double arrow 26 - is mounted adjustable by means of a drive assembly 27. The drive assembly 27 consists in the illustrated embodiment of two in each case in end regions 28, 29 of the press bar 16 acting actuators 30, for example with a pressure medium, in particular a hydraulic oil, acted upon, double-acting cylinder, on the one hand mounted on the shield plates 24 and adjusting elements 31, eg piston rods , are connected to the press bar 16 in a drive connection, in particular via spherical plain bearings 32, for movement. However, the invention is not limited to the drive arrangement described in detail herein 27 restricted with the drives 30 formed by cylinders. Of course, instead of the two drives 30 shown, a plurality of such drives 30 can be used for adjusting the press bar 16, as well as the drives 30 by other types of linear drives, for example by means of electrically or hydraulically driven spindle drives, be formed, as well as eccentric are possible.

Facing one another and extending parallel to the working plane 14 end faces 33, 34 of the press beams 15, 16 have tool holders 35 for supporting and releasable attachment of bending tools 36, 37. As is known from the prior art, these bending tools 36, 37 generally form a bending die 39 and a bending punch 40. From the prior art, it is also known to divide the bending tools 36, 37 into sections, resulting in an easy variability for a tool length 41, in order to adapt to the respective requirements can or to the conversion of the manufacturing device 1 or the exchange of bending tools 36, 37 easier to make.

The tool holders 35 in the press beams 15, 16 are on the one hand designed for releasably securing the bending tools 36, 37, on the other hand they form support surfaces 42 for transmitting the bending forces - according to arrows 43 - from.

The arranged below the working plane 14 press beam 15 is attached directly to the end faces 20 of the bottom plate 10 associated leg 21, whereby with respect to the center plane 12, a symmetrical anchoring of the press beam 15 on the machine frame 5 forms and results in a structurally simple and material-saving construction , In the exemplary embodiment of forming a releasable attachment of the stationary press beam 15, the support and / or mounting assembly 19 is e.g. formed by solid, bolted to the stator side walls 6, 7 bolt 44, on which the press beam 15 is pushed with arranged in this holes and, for. is tightened by means of threaded nuts 45. However, as a support and / or mounting arrangement 19, a welded connection is also to be considered, via which the press beam 15 can be connected inseparably to the stator side cheeks 6, 7.

As already mentioned, in the exemplary embodiment described, the drive arrangement is formed by a hydraulic energy supply system 46 and the drives 30 by double-acting hydraulic cylinders 47. Furthermore, the manufacturing plant 1 with a Power source 48, such as a power grid, line-connected control device 49 and a line connected to this measuring device 50, to the external detection means 51, eg Kraftmeß-, Druckmeß-, Energiemeß-, Dehnungsmeß sensors, etc., are connected. For the supply of a pressure medium, the production device 1, as shown schematically, a hydraulic unit 52 consisting of a tank 53 for the pressure medium, a hydraulic pump 54 and required control and switching devices 55 on. The control device 49 further includes an evaluation and / or arithmetic unit 57 equipped with a data memory 56. Of course, a control terminal 58, preferably externally equipped with input and / or signaling and / or monitoring means, is further provided with the control device 49.

The method according to the invention for operating the production device 1, in particular the press brake 2, will be described below as a preferred method with reference to the production device 1 according to the invention described by way of example in FIGS. 1 and 2.

For the optimization of a manufacturing process for the transformation of the sheet metal part 3 to a housing part 4, it is often useful, the bending tools 36, 37, provided that the tool length 41 is smaller than the length 17 of the press beams 15, 16, off-center, so laterally offset to the center plane 12 to arrange. This is often easier usability and thus faster handling in production achieved.

As a result, occur during the deformation of the sheet metal part 3 off-center loads on the manufacturing facility 1, which by differently sized pressing forces - according to arrows 59,60 - arise. According to the force-moment calculation, the pressing forces - according to arrows 59, 60 - calculated from a required forming force - according to arrow 61 - for the deformation of the sheet metal part 3 and the ratio of the distances of the lines of action of the pressing forces to the line of action of the forming force.

The forming force to be used for forming the sheet-metal part 3 -according to arrow 61 -can on the one hand be determined empirically or mathematically and thus predetermined or, as in the case of the inventive construction of the production device 1 and of the method according to the invention during the transformation by the detection means 51 in the described embodiment, in the power supply system 46 and concretely in supply lines 62 for the pressure medium to the hydraulic cylinders 47 provided as detection means 51 pressure sensors 63 are determined. This makes it possible, the effectively occurring pressing forces - according to Arrows 59, 60 - determine immediately when the forming process and digitizing them in the evaluation and / or arithmetic unit 57 and thus in a stored in the data memory 56 load-deformation matrix, the load-dependent effects on the machine frame 5, in particular the springing of the stator side walls 6, 7 and the deformation of the press beams 15, 16 to assign.

This load-deformation matrix can be created both mathematically and empirically for the respective type of production device 1 as a machine-dependent file and contains the respective deformation values or direct correction factors for the adjustment paths of the drives to compensate for and achieve a parallel position of the bending tools. These correction factors are created according to the load-dependent deformations and take into account substantially the respective relative position of the bending tools 36, 37 with respect to the longitudinal extent of the press beams 15, 16, which is determined from the ratio of the pressing forces - according to arrows 59, 60 - and a effective tool length or a known for forming the sheet metal part 3 forming length 64. These correction factors generate control signals for one of the control and switching device 55 encompassed way control and regulating device 65, eg a proportional path control, which assigns each of the drives 30 the corresponding adjustment path to compensate for the deformations and achieving a uniform over the entire forming length 64 immersion depth of the bending tools 36, 37.

According to a further variant of the method according to the invention, instead of the load-deformation matrix stored in the data memory according to algorithms stored in the evaluation and / or arithmetic unit 57, the force-induced deformations, such as springing of the stator side cheeks 6, 7 and bending of the press beams 15, 16 for the respective compressive forces occurring - according to arrows 59, 60 - and to determine the position of the bending tools and to determine the adjustment path per drive 30 to compensate for the load-related deformations, after which via the Wegesteuer- and control device 65, the adjustment of the drives 30 is caused.

Of course, there is also the possibility of equipping the manufacturing device 1 with a Wegemeßsystem 66, including various known from the prior art options, such as electro-optical Wegemeßeinrichtungen, Laser Wegemeßeinrichtungen, etc., can be applied to order the predetermined or determined Adjust adjustment paths, if necessary in a control loop readjustments to induce. Important in such Wegemeßeinrichtungen 66 is the elimination of measurement errors due to the deformation, ie, that such Wegemeßeinrichtung 66 determines the real values.

A further embodiment or additional possibilities for detecting the pressing forces - according to arrows 59, 60 - consists in the arrangement of strain gauges 67, e.g. on the stator side walls 6, 7.

In Fig. 3 is schematically and oversubscribed the situation as it results due to the force-induced deflection of the press beams 15, 16 at eccentric arrangement of the bending tools 36, 37 in a press brake 2, shown. In such an arrangement, starting from the required forming force - according to arrow 61 - the pressing forces to be calculated according to the torque set - according to arrows 59, 60 - in different sizes, which are applied by the drives 30. On the one hand, this results in a different springing of the C-shaped stator side cheeks 6, 7, to which the drives 30 are fastened. Furthermore, this results in an asymmetrical deflection of the press beams 15, 16, as shown in Fig. 3 are very overdrawn. According to the respective bending line, which in addition to the dimensions and material characteristics of the press beams 15, 16 is dependent on the forming force and position of the bending tools and the tool length, the position of the bending tools 36, 37 to each other and thus the position of mutually aligned working edges or work surfaces 68, 69 of the bending tools 36, 37 changed so that they are at an angle to each other. However, the minimal deviation in the parallelism causes immediately an unsatisfactory manufacturing result.

In order to prevent this, the method according to the invention and the press brake 2 designed for carrying out the method provide, in a first method step, based on the pressing forces applied by the drives 30 and their adjusting elements 31, as shown in arrows 59, 60, the position e.g. a distance 70 of the resulting forming force - as indicated by arrow 61 - to be determined by the center plane 12 and determine their magnitude. In addition to the magnitude of the applied forming force and the position of the bending tools 36, 37 on the press beams 15, 16, the effective tool length or the forming length 64 for the sheet metal part 3 to be formed is decisive for the forming at the end faces 33, 34 bending lines of the press beams 15, 16th

The inventive method and the device according to the invention now wiewie already described above, on the one hand, the possibility that these dependencies are stored in the data memory 56 of the control and switching device 55 (see FIG. 1) assigned to the evaluation and / or arithmetic unit in the form of a load-deformation matrix and corresponding to this data Drives 30 a corresponding adjustment - according to arrows 71, 72 - is assigned to compensate for the resulting due to the deformation angular position of the work surfaces 68, 69 and to achieve over the entire Umformlänge same immersion depth 73 of the bending tools 36, 37.

Instead of the data stored in the data memory 56 (see FIG. 1) load deformation file, it is of course also possible, with appropriate computer capacity, the effects of the load distribution and thus the incoming deformations, just as the springing of the stator side walls 6, 7 and bending of the press bars 15th , 16 to determine mathematically and to compensate for angular positions of the bending tools 36, 37 by assigning corresponding adjustment paths - according to arrows 71, 72 - perform.

The determination of the pressing forces - according to arrows 59, 60 - and choice of the corresponding detection means 51 (see FIG. 1) of course depends on the type of the selected drives 30, which, as already mentioned, by hydraulic cylinders 47, but also by electric drives, Linear drives, etc. may be formed. On the other hand, however, the strains causing deformation can also be achieved by variously attached strain gauges 67, e.g. be determined on the stator side walls 6, 7 and press beams 15,16.

For the sake of order, it should finally be pointed out that, for a better understanding of the production device 1, this or its components have been shown partially unevenly and / or enlarged and / or reduced in size.

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

REFERENCE NUMBERS

1

manufacturing facility

2

press brake

3

sheet metal part

4

housing part

5

machine frame

6

Stand-side cheek

7

Stand-side cheek

8th

footprint

9

10

baseplate

11

distance

12

midplane

13

wall part

14

working level

15

press beams

16

press beams

17

length

18

Support and / or fastening arrangement

19

20

face

21

leg

22

face

23

leg

24

shield plate

25

guide assembly

26

double arrow

27

drive arrangement

28

end

29

end

30

drive

31

actuator

32

Spherical plain bearings

33

face

34

face

35

tool holder

36

bending tool

37

bending tool

38

bending die

39

40

punch

41

tool length

42

support surface

43

arrow

44

bolt

45

threaded nut

46

Power system

47

hydraulic cylinders

48

energy

49

control device

50

measuring device

51

detection means

52

hydraulic power unit

53

tank

54

hydraulic pump

55

Control and switching device

56

data storage

57

Evaluation and / or arithmetic unit

58

control terminal

59

arrow

60

arrow

61

arrow

62

supply

63

pressure sensor

64

forming length

65

Route control and regulating device

66

Wegemeßeinrichtung

67

Strain gauge sensor

68

working surface

69

working surface

70

distance

71

arrow

72

arrow

73

Immersion depth

Claims (14)

1. Method of operating a bending press, in particular an edging press (2), with a machine frame (5), preferably consisting of two stand sides (6, 7) spaced at a distance apart from one another, and a stationary press beam (15) and a press beam (16) displaceable in guide arrangements (25) by means of a drive system (27) incorporating at least two drives (30), and having tool clamping devices for holding pressing tools (36, 37) on mutually facing end faces (33, 34) of the press beams (15, 16), and having a control unit (49) connected by lines to the drive system (27) and a measuring device (50) and detection means (51) for detecting machine data and optionally workpiece data during production of workpieces, and the actual pressing force is detected for the displaceable press beam (16) for each drive (30) of the drive system (27) during a bending process for the workpiece and a relative position of the pressing tool or tools by reference to a length (17) of the press beams (15, 16) is determined by computation on the basis of a force ratio, and different displacement paths of the drives (30) and the displaceable press beam (16) at the respective attacking point of the drive (30) as well as a resultant bending line of the press beams (15, 16) are determined in an evaluation and/or computer unit (57) provided with a data memory (56) for production and machine data, characterised in that corresponding control signals for the drive system (27) are generated in the control unit (49), and actuator elements (31) of the drives (30) are displaced by the displacement paths determined for each drive (30), and the displaceable press beam (16) can be displaced relative to the stationary press beam (15) into a parallel position or into a position in which end faces (33, 34) of the press beams (15, 16) subtend an acute angle, and the bending tools (36, 37) have a uniform plunge depth across an entire forming length (64).
2. Method as claimed in claim 1, characterised in that the pressing force applied by each of the drives (30) is determined and the values corresponding to these values ascertained from deformation data of the bending press, in particular flexing and/or bending data, stored in the data memory (56) and the displacement paths of each drive (30) and actuator element (31) are set.
3. Method as claimed in claim 1 or 2, characterised in that the pressing force applied by each drive (30) is determined and the load-dependent deformations of the bending press, in particular flexing in the stand sides (6, 7) and/or bending in the press beams (15, 16), are computed from these values in conjunction on the basis of algorithms stored in the evaluation and/or computer unit (57), and displacement paths of the drives (30) and the actuator elements (31) are set.
4. Method as claimed in one or more of the preceding claims, characterised in that the displacement path of each drive (30) is determined in the evaluation and/or computer unit (57) on the basis of material data for the workpiece to be shaped, the effective tool length (41) or the bending angle stored in the data memory (56).
5. Method as claimed in one or more of the preceding claims, characterised in that the displacement path of each drive (30) is determined in the evaluation and/or computer unit (57) on the basis of machine data of the bending press stored in the data memory (56) for the load-dependent flexing behaviour of the stand sides (6, 7).
6. Method as claimed in one or more of the preceding claims, characterised in that the displacement path of each drive (30) is determined in the evaluation and/or computer unit (57) on the basis of machine data of the bending press stored in the data memory (56) for the force-dependent bending behaviour of the press beams (15, 16).
7. Method as claimed in one or more of the preceding claims, characterised in that the displacement path of each drive (30) is determined in the evaluation and/or computer unit (57) on the basis of algorithms stored in the data memory (56) for the force-dependent flexing behaviour of the stand sides (6, 7).
8. Method as claimed in one or more of the preceding claims, characterised in that the displacement path of each drive (30) is determined in the evaluation and/or computer unit (57) on the basis of algorithms stored in the data memory (56) for the force-dependent bending behaviour of the press beams (15, 16).
9. Method as claimed in one or more of the preceding claims, characterised in that the flexing and/or bending behaviour of the stand sides (6, 7) and the press beams (15, 16) is determined by stress and/or strain measuring methods and/or pressure sensing methods, and control signals for the drive system (27) are generated from measurement data in the evaluation and/or computer unit (57).
10. Method as claimed in one or more of the preceding claims, characterised in that the detected actual pressing forces are compared in a control circuit of the evaluation and/or computer unit (57) with production data, in particular desired pressing forces, stored in the data memory (56), and control signals for the drive system (27) are forwarded to the control unit (49) accordingly.
11. Method as claimed in one or more of the preceding claims, characterised in that actual displacement paths detected by a displacement-measuring system (66) are compared in a control circuit of the evaluation and/or computer unit (57) with desired displacement paths stored in the data memory (56) and control signals for the drive system (27) are forwarded to the control unit (49) accordingly.
12. Bending press, in particular an edging press (2), with a machine frame (5), preferably consisting of two stand sides (6, 7) spaced at a distance apart from one another, and a stationary press beam (15) and a press beam (16) displaceable in guide arrangements (25) by means of a drive system incorporating at least two drives (30), and having tool clamping devices for holding bending tools (36, 37) on mutually facing end faces (33, 34) of the press beams (15, 16), and having a control unit (49) connected by lines to the drive system (27), and with a measuring device (50) and detection means (51) for detecting machine data, such as pressing forces or load data appearing during production of workpieces, and the control unit (49) is an evaluation and/or computer unit (57) provided with a data memory (56) and has a displacement control and regulating device (65) for the drives (30), characterised in that, during the forming process, the displaceable press beam (16) can be displaced relative to the stationary press beam (15) into a parallel position or into a position in which end faces (33, 34) of the press beams (15, 16) subtend an acute angle, and the bending tools (36, 37) have a uniform plunge depth across an entire forming length (64).
13. Bending press as claimed in claim 12, characterised in that a displacement-measuring device (66) is provided between the machine frame (5) and the displaceable press beam (16).
14. Bending press as claimed in claim 12 or 16, characterised in that the displacement-measuring device (66) is disposed between the stationary and the displaceable press beam (15, 16).

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