EP3253507B1 - Bending apparatus with measuring device - Google Patents

Description

The invention relates to a manufacturing device, in particular a press brake, and a method for forming workpieces made of sheet metal according to the preambles of claims 1 and 17.

When forming tabular workpieces or workpieces having relatively large dimensions in bending presses or pressbrakes, high forming forces naturally result in high forming forces. In reaction to this, however, the forming forces acting on the workpiece to be reshaped also lead to a deflection of the press beams of the press table or of the movable press stamp carrying the bending tools. As a result, this causes an uneven formation of the bending angle on the workpiece to be deformed. That is, over the longitudinal course of the edge produced, the bending angle is not the same at all points. In order to prevent such quality reductions of the workpieces, various measures have already been proposed in the prior art in order to achieve a compensation of a deformation occurring under load of the table beam and the movable press beam. For example, it is known to provide for the movement of the press beam over the length of the press beam away a plurality of independently controllable drive units. The expected deformation of the press beam is calculated on the basis of corresponding workpiece parameters and counteracted this deformation by different application of force to the press beam with the independently controllable drive units. On the other hand, it is also known to determine the respective deformation state of the press beam, for example by means of strain gauges. On the other hand, it is possible to determine the current forming force, for example, by measuring the hydraulic pressure or the drive current of the drive means to thereby calculate the currently occurring deflection of the press bar. A disadvantage of the known methods is that it is only an indirect determination of the deflection of the press beams. The known measures are usually not without previous series of experiments in which the dependence or the relationship between the forming force and the resulting Pressbalkendurchbiegung is found.

The invention has for its object to provide a bending method or a bending device with which even at comparatively large bending lengths a deflection of the press bars can be compensated with a higher reliability.

The object of the invention is achieved by a production device, in particular a press brake, for forming a workpiece from sheet metal with a press table and a press table opposite and parallel to the press bar. The pressing beam is adjustable relative to the press table by means of a drive device in a direction perpendicular to a longitudinal extension of the press beam, wherein the drive device comprises at least three drive units, which are distributed over the longitudinal extent of the press beam. For this purpose, a measuring device for measuring the instantaneous position of individual points on the pressing beam and a control device for adapting a deformation of the pressing beam is formed, wherein the measuring device comprises a laser transmitter for generating a aligned in the longitudinal extent of the press beam laser beam. This has the advantage that the laser beam provides a high-precision reference line for measuring the deflection or monitoring of the straightness of the press beam.

Advantageously, the measuring device comprises a plurality of sensor arrangements for detecting the laser beam, wherein the sensor arrangements are fastened to the pressing beam.

Preferably, the sensor arrangements each comprise a spatially resolving sensor for detecting the laser beam. For this purpose, it can be provided that the sensor arrangements each comprise a CCD sensor. This has the advantage of a high accuracy of the position measurement, since no moving parts are required or available in the measuring device.

It is also advantageous that the sensors are arranged laterally offset with respect to the propagation direction of the laser beam and perpendicular to the direction of movement of the press beam to each other. Furthermore, that the laser transmitter comprises an optical element for forming a plurality of parallel laser beams or for forming a flat laser light band.

Preferably, the sensor arrangements each comprise a line sensor according to the principle of a CCD sensor.

In a development of the production device, it is provided that the sensor arrangements each comprise an optical element for deflecting the laser beam in a direction parallel to the direction of movement of the pressing beam or that the sensor arrangements each have a mirror. This is advantageous because it allows the laser light beam path to be designed to save space with a narrow or small cross-section.

It is preferably provided that the mirror is designed as a plane mirror and this is aligned inclined with respect to the propagation direction of the laser beam by 45 °.

According to a further preferred embodiment, the sensor arrangements are each formed with a beam splitter element. This has the advantage that only one laser beam must be provided and the cross section of the beam path can be kept correspondingly small.

According to an alternative embodiment, the sensors of the sensor arrangements are each attached to a mechanical guide. This also has the advantage that only one laser beam must be provided, in the course of which the sensors can be moved alternately into it.

In a further alternative embodiment of the production device, it is provided that the measuring device comprises a spatially resolving sensor and a plurality of convex mirrors or concave mirrors for reflecting the laser beam toward the spatially resolving sensor, wherein the convex or concave mirrors are attached to the pressing beam. This also allows a space-saving design of the measuring device.

It is also advantageous that a control arrangement is arranged and the control device is designed to calculate a change in position at the location of the respective sensor from measurement signals transmitted by the sensor. This has the advantage that thus in the manufacturing facility the formation of a control loop is possible through which the straightness of the press bar can be monitored and maintained.

According to a development of the production device is provided that the laser transmitter is attached to a guide element, wherein the guide element is guided on a part of the machine frame and is adjustable together with the pressing beam. This has the advantage that not only the straightness of the press beam as such but also its parallelism with respect to the press table or the overall arrangement of the machine frame can be monitored.

The object of the invention is solved independently by a method for forming a workpiece from sheet metal with a manufacturing device, in particular a press brake, with a press table and the press table opposite and aligned parallel to the press bars. In this case, the pressing beam is adjustable relative to the press table by means of a drive device in a direction perpendicular to a longitudinal extension of the press beam direction, wherein the drive device is formed with at least three drive units and these drive units are distributed over the longitudinal extent of the press beam. Furthermore, a measuring device for measuring the instantaneous position of individual points is arranged on the pressing beam, wherein the measuring device is formed with a laser transmitter for generating a laser beam aligned in the longitudinal extent of the pressing beam. This has the advantage of directly measuring the deformation of the press beam relative to the line defined by the light beam.

It is also advantageous that a position change relative to the laser beam is detected at a plurality of locations of the press beam with spatially resolving sensors arranged at the locations and further that values of the position change are calculated in a control device from measurement signals transmitted by the sensors.

It is also advantageous that forces to be generated in the control device based on the values of the change in position by the drive units are calculated to compensate for the changes in position measured by the measuring device on the pressing beam, and furthermore that the state of deformation of the pressing beam is determined continuously by determining the position change during the entire process Machining process of the workpiece measured becomes. This has the advantage that a control loop is thus present, by means of which the press beam can be kept as straight as possible during the entire load condition during the machining process.

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

Fig. 1

eine Abkantpresse für das Umformen eines tafelförmigen Werkstücks in Frontalansicht;

Fig. 2

die Abkantpresse gemäß Fig. 1 in einem Belastungszustand;

Fig. 3

einen Pressbalken der Abkantpresse gemäß Fig. 1 mit einer Messeinrichtung zur Messung des Verformungszustandes;

Fig. 4

den Pressbalken mit der daran angeordneten Messeinrichtung gemäß Fig. 3;

Fig. 5

die Messeinrichtung gemäß Fig. 3 in Draufsicht;

Fig. 6

eine alternative Ausführungsvariante der Messeinrichtung der Abkantpresse in Draufsicht;

Fig. 7

ein Ausführungsbeispiel der Messeinrichtung der Abkantpresse mit Spiegel umfassenden Sensoranordnungen;

Fig. 8

ein Ausführungsbeispiel der Messeinrichtung mit Strahlenteiler umfassenden Sensoranordnungen;

Fig. 9

ein Ausführungsbeispiel der Messeinrichtung mit gekrümmte Spiegel umfassenden Sensoranordnungen;

Fig. 10

ein Ausführungsbeispiel der Messeinrichtung mit einem an einer Ständer-Seitenwange der Abkantpresse angeordneten Lasersender.

In each case, in a highly simplified, schematic representation:

Fig. 1

a press brake for forming a tabular workpiece in a front view;

Fig. 2

the press brake according to Fig. 1 in a loaded state;

Fig. 3

a press beam of the press brake according to Fig. 1 with a measuring device for measuring the deformation state;

Fig. 4

the press beam with the measuring device arranged thereon according to Fig. 3 ;

Fig. 5

the measuring device according to Fig. 3 in plan view;

Fig. 6

an alternative embodiment of the measuring device of the press brake in plan view;

Fig. 7

an embodiment of the measuring device of the press brake with mirror comprehensive sensor arrangements;

Fig. 8

an embodiment of the measuring device with beam splitter sensor arrangements comprising;

Fig. 9

an embodiment of the measuring device with curved mirror comprehensive sensor arrangements;

Fig. 10

An embodiment of the measuring device with a arranged on a stator side cheek of the press brake laser transmitter.

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 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 these position information in a change in position mutatis mutandis to transfer to the new location.

The Fig. 1 shows a press brake in frontal view. The press brake 1 serves as a manufacturing device for the forming of a tabular workpiece 2, for example, to a housing part or a profile part.

The press brake 1 comprises as a machine frame 3, a frame-shaped arrangement of a bottom plate 4, a left and a right upright sidewall 5, 6 and a two side bolsters 5, 6 in their upper end region supporting cross-dressing 7. In a lower end of the machine frame 3, a fixed press table 8 is arranged. On the press table 8 is a die 9 as a lower bending tool, which is attached to a support surface 10 of the press table 8. About the press table 8 whose support surface 10 is disposed opposite an adjustable pressing beam 11. For this purpose, a guide assembly 12 is connected to one of the two stator side walls 5, 6 respectively. The pressing beam 11 carries on a press table 8 opposite support surface 13 a male part 14 as the upper bending tool. For adjusting the press beam 11 in the vertical direction relative to the press table 8, a drive arrangement is provided, which comprises four drive units 15 according to this embodiment. The drive units 15 may be formed for example by hydraulic cylinders or servomotors with adjusting spindles. With the help of the drive units 15, the pressing beam 11 is moved against the press table 8, whereby in the sequence lying between the die 9 and the male part 14 workpiece 2 is bent.

The action of the deformation forces on the workpiece 2 is accompanied in response to the formation of an internal stress state of both the press table 8, the press beam 11 and the components of the machine frame 3. It can therefore lead to a more or less large deformation of the parts of the machine frame. 3 and in particular of the press bar 11 and the press table 8 come. For the quality of the machining of the workpiece 2 is a possibly occurring deformation of the support surface 13 of the press bar 11 and the support surface 10 of the press table 8 is important. In order to keep the support surfaces 10, 13 of the press table 8 and the press bar 11 as straight as possible and parallel to each other during the forming process of the workpiece 2, it is therefore provided to drive the drive units 15 of the drive assembly independently of one another. Preferably, two drive units 16 are also arranged on the press table 8. These drive units 16 are supported on the bottom plate 4 and it is thus possible to act on two support points a force on the press table 8. This should also in the press table 8 as far as possible compensation of the deformation of its support surface 10 can be achieved.

To control the operation of the press brake 1, that is, in particular the control of the drive units 15, 16, this includes a control device 17. In addition to this control device 17, a measuring device 18 for measuring the deflection of the press bar 11 is provided.

The Fig. 2 shows the press brake 1 during the Umbiegevorgangs of the workpiece 2. In the illustrated relative position of the press beam 11, the male part 14 is in an already partially penetrated into the die 9 position and therefore appears after the workpiece 2 in its front, the viewer facing area after bent upside down. On the pressing beam 11, a bending line 19 is also shown in dotted line, as in approximately a deformation of the support surface 13 of the press bar 11 - when applying equally large forces by the drive units 15 of the drive assembly of the press bar 11 - corresponds. In an analogous manner, a bending line 20 of the press table 8 is located on the press table 8.

The press brake 1 according to this embodiment is designed so that with the aid of the measuring device 18, the deflection or the curvature of the bending line 19 of the press bar 11 is measured and based on the extent of the deflection of the bending line 19, the drive units 15 of the press bar 11 are driven so differently that the curved bending line 19 is compensated or reset to a straight line.

Based on Fig. 3 to 5 a first embodiment of the press brake 1 according to the invention will be described. The Fig. 3 shows the press bar 11 with the measuring device 18 according to a first embodiment. The measuring device 18 comprises a laser transmitter 21 and five sensors 22. The laser transmitter is arranged and aligned such that it can generate a laser beam 23 or a laser beam which is aligned substantially parallel to a longitudinal extent 24 of the press beam 11. The sensors 22 are arranged laterally offset with respect to the propagation direction of the laser beams 23 ( Fig. 5 ), and thus each of the sensors 22 can receive light from the laser transmitter 21.

The Fig. 5 shows a top view of the measuring device 18 according to Fig. 3 , According to this embodiment, a laser beam 23 is directed by the laser transmitter 21 to each of the five sensors 22. Alternatively, it would also be possible to fan out a single laser beam 23 generated by the laser transmitter 21, for example, through a cylindrical lens into a flat laser light band and to direct this to the sensors 22. According to another alternative, however, the laser beam 23 could also be cyclically directed from one sensor 22 to the next sensor 22 in a temporally rapid succession.

The Fig. 4 shows a frontal view of the arranged on the pressing beam 11 measuring device 18 according to Fig. 3 , The state of the press bar 11 and the measuring device 18 corresponds to the loading situation when performing a bending operation. This is indicated by the deformation of the support surface 13 to the bending line 19. According to this embodiment, both the laser transmitter 21 and the sensors 22 are connected to the pressing beam 11 and secured thereto. The sensors 22 thus experience a change in position 25 relative to the laser beam 23 as a result of the general deformation of the press beam 11. As a result, the sensors 22 will detect a point of incidence of the laser beam 23 which is changed with respect to the unloaded state.

The position change 25 respectively detected by the sensors 22 has the dimension of a length and for detecting these position changes 25 are spatially resolving sensors 22, for example, in the manner of a CCD sensor (charge-coupled device) suitable. According to this embodiment with laterally offset sensors 22 (FIG. Fig. 5 ), line sensors according to the principle of a CCD sensor are preferably provided as sensors 22. Measurement signals of the individual sensors 22 detected by the measuring device 18 are transmitted to the control device 17 and can be used to evaluate the position changes 25 in this device. Based on the results of this evaluation of the control device 17, the press brake 1 can individually drive the drive units 15 of the drive arrangement of the press beam 11 in such a way that the extent of the position changes 25 at the points of the sensors 22 is reduced and finally fully compensated. In this way it can be achieved that the support surface 13 of the press bar 11 is largely returned to a re-deformed, straight state.

The measurement of the deformation state of the press beam 11 is preferably carried out continuously with the aid of the measuring device 18 during the entire machining or forming process of the workpiece 2. In the same manner taking into account the measurement results of the measuring device 18, an individual control of the drive units 15 of the drive assembly of the press bar 11 is performed, in the press brake 1 a total of a control circuit is formed by the as a result throughout the processing process a largely straight state of the press beam 11 can be maintained at least at its support surface 13.

It is preferably provided that also the press table 8 is equipped in an analogous manner with a measuring device 26 for measuring the instantaneous state of deformation of the press table 8. With the help of this measuring device 26 can thus also be measured and monitored the deformation state of the press table 8 and in particular the straightness of the support surface 10 of the press table 8. For this purpose, in turn, after evaluation of the measuring signals of the measuring device 26 of the press table 8, a corresponding control of the drive units 16 can be carried out by the control device 17.

In the Fig. 6 is a further and possibly independent embodiment of the press brake 1 is shown, again for like parts, the same reference numerals or component names as in the preceding Fig. 1 to 5 be used. To unnecessary To avoid repetition, the detailed description in the previous Fig. 1 to 5 referred or referred.

The Fig. 6 shows an alternative embodiment of the measuring device 18 of the press brake 1 in plan view, that is with a line of sight parallel to the direction of movement of the press beam 11. In this form of the measuring device 18 is provided that only a single laser beam 23 is emitted by the laser transmitter 21, which is used as a reference for measuring the deformation state of the press beam 11 is used. For measuring position changes 25 ( Fig. 4 ), the sensors 22 are moved alternately successively in the lateral direction 30 in the region of the laser 23. For this purpose, the sensors 22 can be arranged, for example, on a straight guide or on a support pivotable about an axis. It can thus be detected a position change 25 which is directed perpendicular to the lateral direction 30. That is, the direction of the position change 25 corresponds to Fig. 6 the viewing direction of the viewer on the drawing plane.

The Fig. 7 shows a further alternative embodiment of the measuring device 18 of the press brake 1 with five sensor arrangements 27. According to this embodiment, the sensor assemblies 27 comprise a mirror 22 in addition to a sensor 22. These mirrors 28 are preferably formed as a plane mirror and at an angle of 45 ° relative to the propagation direction of the laser beam 23 is arranged on the pressing beam 11. Thus, the laser beam 23 is deflected by the reflection on the mirror 28 in a direction parallel to the direction of movement of the press beam (11). In a similar way as in Fig. 5 for the sensors 22, the mirrors 28 are arranged laterally offset with respect to the propagation direction of the laser beam 23. The mirrors 28 of the sensor arrangements 27 cause a deflection of the propagation direction of the laser beam 23 by 90 ° and the change in position can be detected by the deformation of the press beam 11 as a change in position 25 as compared to the unloaded state modified impact point of the laser beam 23 on the sensor 22.

The Fig. 8 shows a further alternative embodiment of the measuring device 18 of the press brake 1. In addition to the laser transmitter 21 for generating the laser beam 23, the sensor assemblies 27 are now formed by a respective sensor 22 and a beam splitter element 29. As shown in Fig. 8 are formed by prisms in this embodiment Beam splitter cube provided. With a suitable choice of the beam splitter elements 29, it is possible to arrange the sensors directly behind one another in the course of a single laser beam 23, wherein only a fraction of the light intensity is coupled out at each of the two beam splitter elements 29. The position change 25 can in turn be detected by the degree of displacement of the point of impingement of the laser beam 23 on the sensor 22.

The Fig. 9 shows an embodiment of a measuring device 18 of the press brake 1 with position detecting devices, the Konkavspiegel 31 include. The change in position 25 due to the deflection of the press beam 11 on which the concave mirrors 31 are arranged now leads by deflection of the impact point on the mirrors 31 to a deflection of the laser light beam 23 in a different deflection angle 32. The measuring device 18 comprises in this embodiment single arranged in the region of the laser transmitter 21 sensor 22, to which the reflected from the concave mirror 31 laser beam 23 is reflected back. By the sensor 22, the impact point of the laser beam 23 is detected as the center distance 33. Starting from this center distance 33, which is detected by the sensor 22, together with a vertex distance 34 of the concave mirror 31 in the control device 17, the position change 25 can be calculated. As an alternative to the described concave mirrors 31, differently curved mirrors, such as convex mirrors, can also be used.

The Fig. 10 shows a further alternative embodiment of the measuring device 18 of the press brake 1. In this embodiment of the measuring device 18, the laser transmitter 21 is mounted separately from the pressing beam 11 on a guide member 35. This guide element 35 is moved together with the pressing beam 11 in the vertical direction up and down. However, the guide element 35 is performed on the stator side cheek 5. It can thereby be achieved that the laser transmitter 21, without being influenced by the deformation state of the press beam 11, is continuously guided in parallel in each phase of its up or down movement. This makes it possible to measure and thus to control both its deformation state or the straightness from the measurement of the different position changes 25 at the corresponding points of the sensor arrangement 27 of the press beam 11, as well as the parallelism of the press beam 11 or its support surface 13 in relation to the press table 8 and its support surface 10 to measure or monitor.

Although in the described embodiment according to the Fig. 1 and 2 however, the arrangement of four drive units 15 for the press beam 11 and two drive units 16 for the press table 8 is provided, but this is not a necessary condition for the described invention. It is therefore also possible to provide more or fewer than four drive units 15 or more or fewer than two drive units 16 for the press table 8. Likewise, the arrangement of five sensors or of five sensor arrangements 27 is not a restriction for the design of the measuring device 18 or 26. Thus, fewer than five such sensor arrangements 27 may be sufficient. However, it is advantageous if more than five sensors 22 or sensor arrangements 27 are provided, since this allows the loading or deformation state of the press bar 11 or of the press table 8 to be measured correspondingly more accurately.

The embodiments show possible embodiments of the manufacturing device or the press brake, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof.

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

All information on ranges of values in objective description should be understood to include these arbitrary and all sub-ranges thereof, eg the indication 1 to 10 should be understood to encompass all sub-ranges, starting from the lower limit 1 and the upper limit 10 that is, all portions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, eg, 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of order, it should finally be pointed out that, for better understanding of the construction of the production device, these or their components have been shown partly unevenly and / or enlarged and / or reduced in size. <B> Reference Numbers </ b> 1 press brake 31 concave mirror 2 workpiece 32 angle 3 machine frame 33 center distance 4 baseplate 34 Scheitelbstand 5 Stand-side cheek 35 guide element 6 Stand-side cheek 7 cross-dressing 8th press table 9 die 10 support surface 11 pressing bars 12 guide assembly 13 support surface 14 punch 15 drive unit 16 drive unit 17 control device 18 measuring device 19 elastic line 20 elastic line 21 laser transmitter 22 sensor 23 laser beam 24 longitudinal extension 25 position change 26 measuring device 27 sensor arrangement 28 mirror 29 Beam splitter element 30 direction

Claims (21)

1. A production device, in particular a mechanical press brake (1), for forming a workpiece (2) made of sheet metal

   - having a press table (8) and a press beam (11) opposite the press table (8) and oriented parallel thereto,

   - which is adjustable relative to the press table (8) by means of a drive device in a direction oriented perpendi-cularly to a longitudinal extent (24) of the press beam (11),

   - wherein the drive device comprises at least three drive units (15, 16) which are arranged distributed over the longitudinal extent (24) of the press beam (11)

   - and having a measuring device (18) for measuring the current position of individual points on the press beam (11)

   - and having a control device (17) for adjusting a deformation of the press beam (11), characterized in that

   - the measuring device (18) comprises a laser transmitter (21) for generating a laser beam (23) oriented in the longitudinal extent (24) of the press beam (11).
2. The production device according to claim 1, characterized in that the measuring device (18) comprises a plurality of sensor assemblies (27) for detecting the laser beam (23), wherein the sensor assemblies (27) are secured to the press beam (11).
3. The production device according to claim 1 or 2, characterized in that the sensor assemblies (27) each comprise a spatially resolving sensor (22) for detecting the laser beam (23).
4. The production device according to one of the preceding claims, characterized in that the sensor assemblies (27) each comprise a CCD sensor.
5. The production device according to one of the preceding claims, characterized in that the sensors (22) are arranged laterally in relation to the propagation direction of the laser beam (23) and offset in respect of one another perpendicularly to the movement direction of the press beam (11).
6. The production device according to one of the preceding claims, characterized in that the sensor assemblies (27) each comprise a line sensor according to the principle of a CCD sensor.
7. The production device according to one of the preceding claims, characterized in that the laser transmitter (21) comprises an optical element for configuring a plurality of laser beams (23) parallel to one another or for configuring a planar strip of laser light.
8. The production device according to one of the preceding claims, characterized in that the sensor assemblies (27) each comprise an optical element for deflecting the laser beam (23) in a direction parallel to the movement direction of the press beam (11).
9. The production device according to one of the preceding claims, characterized in that the sensor assemblies (27) each comprise a mirror (28).
10. The production device according to one of the preceding claims, characterized in that the mirror (28) is configured a plane mirror which is oriented on a 45° incline in relation to the propagation direction of the laser beam (23).
11. The production device according to one of the preceding claims, characterized in that the sensor assemblies (27) each comprise a beam-splitter element (29).
12. The production device according to claim 3, characterized in that each sensor (22) of the sensor assemblies (27) is fastened to a mechanical guide.
13. The production device according to one of the preceding claims, characterized in that the measuring device (18) comprises a spatially resolving sensor (22) and a plurality of convex mirrors (31) or concave mirrors for reflecting the laser beam (23) to the spatially resolving sensor (22), wherein the convex mirrors (31) or the concave mirrors are fastened to the press beam (11).
14. The production device according to one of the preceding claims, characterized in that a control device (17) is arranged and the control device (17) is designed for calculating a positional change (25) at the site of the sensor (22) from measuring signals transmitted by the sensor (22).
15. The production device according to one of the preceding claims, characterized in that the control device (17) is configured to calculate forces to be generated by the drive units (15, 16) and an actuation of the drive units (15, 16) corresponding to these forces for balancing the positional changes (25) on the press beam (11) measured by the measuring device (18).
16. The production device according to one of the preceding claims, characterized in that the laser transmitter (21) is fastened to a guide element (35), wherein the guide element (35) is guided on a part of the machine frame (3) and is adjustable along with the press beam (11).
17. A method for forming a workpiece (2) made of sheet metal using a production device, in particular a mechanical press brake (1), having a press table (8) and a press beam (11) opposite the press table (8) and oriented parallel thereto, which press beam is adjustable relative to the press table (8) by means of a drive device in a direction oriented perpendicularly to a longitudinal extent (24) of the press beam (11), wherein the drive device is configured with at least three drive units (15, 16) and these drive units (15, 16) are arranged distributed over the longitudinal extent (24) of the press beam (11) and wherein a measuring device (18) for measuring the current position of individual points is arranged on the press beam (11), characterized in that the measuring device (18) is configured with a laser transmitter (21) for generating a laser beam (23) oriented in the longitudinal extent (24) of the press beam (11).
18. The method according to claim 17, characterized in that at multiple points on the press beam (11) a positional change (25) relative to the laser beam (23) with spatially resolving sensors (22) arranged at the points is detected.
19. The method according to claim 18, characterized in that values of the positional change (25) are calculated from the measuring signals transmitted by the sensors (22) in a control device (17).
20. The method according to claim 19, characterized in that in the control device (17) forces to be generated by the drive units (15, 16) in order to balance the positional changes (25) on the press beam (11) measured by the measuring device (18) are calculated based on the values of the positional change (25).
21. The method according to claim 20, characterized in that the deformation state of the press beam (11) is measured by determining the positional changes (25) continuously throughout the entire machining action of the workpiece (2).

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