BENDING TOOL HAVING A LONGITUDINAL-OFFSET MEASURING DEVICE

Abstract

The invention relates to a lower tool (1) having a longitudinal-offset measuring device (2), which lower tool (1) is part of a bending tool arrangement for use in a bending press. The lower tool (1) has a tool body (3) having a longitudinal extension (4), in which longitudinal extension (4) a bending recess (5) is provided. The bending recess (5) extends from an upper flat side (6) of the tool body (3) into the latter and is formed at least by two contact surfaces (7). The transition from the upper flat side (6) into the bending recess (5) forms a contact edge (8), which contact edge (8) forms a contact line (9) in the longitudinal extension (4). A sensor (10) for determining a longitudinal offset (18) is arranged in the region of the contact line (9), wherein a sensing portion (11) of the sensor (10) is oriented in the direction of a metal sheet (16) to be bent.

Claims

1. Bending tool (1) having a longitudinal-offset measuring device (2), which bending tool (1) is part of a bending tool arrangement for use in a bending machine, a sheet (16) to be bent being placed in the bending tool arrangement, and the bending tool (1) has a tool body (3) having a longitudinal extension (4), which longitudinal extension (4) is aligned parallel with a bending line, and two contact surfaces (7) or at least one contact edge (8) are disposed parallel with this longitudinal extension (4) and oriented in the direction of the sheet (16) to be bent, wherein a sensor (10) for determining a longitudinal offset (18) is disposed in the region of the contact edge (8) or in a contact surface (7), and a sensing portion (11) of the sensor (10) is oriented in the direction of a metal sheet (16) to be bent.

2. Bending tool according to claim 1, wherein the sensor (10) is disposed without an offset in relation to the contact edge (8) or contact line (9).

3. Bending tool according to claim 1, wherein the sensor (10) is configured so that it can be pivoted about the contact line (9).

4. Bending tool according to claim 1 where the bending tool is the lower tool of a bending press, wherein the contact surfaces (7) are formed by pivoting jaws (13), which pivoting jaws (13) are pivotable about a pivot axis (14) parallel with the contact line (9).

5. Bending tool according to claim 1 where the bending tool is the lower tool of a bending press, wherein the contact surfaces (7) form a bending recess (5) of a V-shaped bending die, which bending recess extends from an upper flat side (6) of the tool body (3) and in the direction away from the sheet (16) to be formed into the tool body (3).

6. Bending tool according to claim 1, wherein the sensor (10) is provided in the form of an illuminating (21) and image capturing device (22).

7. Bending tool according to claim 1, wherein the sensor (10) is provided in the form of a transmitter and receiver for electromagnetic radiation.

8. Bending tool according to claim 4, wherein the sensor (10) is disposed in a recess of at least one of the contact surfaces (7).

9. Bending tool according to claim 4, wherein a sensing flat face of the sensor (10) is disposed in the tool body (3) spaced apart from the contact surface (7) by an offset (15).

10. Bending tool according to claim 1, wherein the bending tool is a bending beam (23) of a panel bender.

11. Bending tool according to claim 10, wherein the sensor (10) is disposed in a section of a front end (25) of the bending beam (23), which front end (25) is in contact with the sheet (16) whilst the bend is being produced.

12. Bending tool according to claim 11, wherein a contact element (26) is disposed in the region of the front end (25), which contact element (26) is mounted so as to be pivotable relative to the bending beam (23) about the contact edge (8) or rotatable about an axis parallel with the contact edge (8).

13. Bending tool according to claim 12, wherein the contact element (26) has a flat side in which the sensor (10) is disposed and this flat side lies on the sheet (16) during the bending operation.

14. Bending tool according to claim 12, wherein the contact element (26) is provided in the form of a sensor disk, which sensor disk rolls on the sheet (16) as the bend is being formed.

15. Bending tool according to claim 1, wherein the sensor (10) is provided in the form of an insert.

16. Bending tool according to claim 1, wherein the sensor (10) is connected to an evaluation circuit (12) which is in turn connected to a machine controller or is integrated therein.

17. Bending tool according to claim 5, wherein the evaluation circuit (12) has an image analysis and comparison module.

18. Bending tool according to claim 17, wherein the image analysis and comparison module is configured to determine a one-dimensional or two-dimensional motion vector for the longitudinal offset (18).

19. Bending tool according to claim 1, wherein the sensor (10) is provided in the form of a rolling device.

20. Method for determining bending geometry during air bending, implemented on a bending press having a bending tool arrangement, which bending tool arrangement comprises a lower and an upper tool, the lower tool being of the type according to claim 1, and a sheet metal part to be bent is placed in the bending tool arrangement and the air bending operation is implemented such that the upper tool is moved down and the sheet metal part is pressed into a bending recess of the lower tool upper tool, wherein prior to the start of the bending operation, a surface of the sheet metal part to be bent is placed in contact with a sensor for determining a longitudinal offset; and reference co-ordinates of the sheet surface for this contact point are determined by reference to the bending machine or bending tool arrangement; and as the bend is being formed, a longitudinal offset of the sheet surface relative to the sensor is determined; and the current bending geometry is determined by an evaluation circuit on the basis of the determined longitudinal offset using a mathematical model of the bending operation.

21. Method for determining bending geometry during a panel bending operation implemented on a panel bender having a bending tool arrangement, which bending tool arrangement comprises a clamping tool (24) and at least one bending beam, a sheet metal part to be bent being placed in the bending tool arrangement, and the air bending operation is implemented such that the sheet metal part is clamped by the clamping tool (24) and the bending beam (23) is placed on the sheet metal part and moved along or pivoted about a trajectory, and the bending beam (23) is of the type according to claim 1, wherein prior to the start of the bending operation, a surface of the sheet metal part to be bent is placed in contact with a sensor for determining a longitudinal offset; and reference co-ordinates of the sheet surface for this contact point are determined by reference to the panel bender or bending tool arrangement; and as the bend is being formed, a longitudinal offset of the sheet surface relative to the sensor is determined; and the current bending geometry is determined by an evaluation circuit on the basis of the determined longitudinal offset using a mathematical model of the bending operation.

22. Method according to claim 20, wherein the sensor is held in a stationary arrangement relative to the reference co-ordinates whilst the longitudinal offset is being determined.

23. Method according to claim 20, wherein the longitudinal offset of the sheet relative to the contact edge of the lower tool is determined by the sensor.

24. Method according to claim 20, wherein the sensor is mounted by means of a pivoting device in the region of the upper tool or on a press table of the bending press and whilst the bend is being produced, the pivoting device follows the sheet as it is bent up.

Description

[0037] To provide a clearer understanding, the invention.will be described in more detail below with reference to the appended drawings.

[0038] These are highly simplified, schematic diagrams illustrating the following:

[0039] FIG. 1 one possible embodiment of the bending tool proposed by the invention;

[0040] FIG. 2 another possible embodiment of the bending tool proposed by the invention;

[0041] FIGS. 3a) and b) illustrate the conditions during the bending operation based on one possible embodiment of the bending tool;

[0042] FIG. 4 a detail of the sensor;

[0043] FIG. 5 an embodiment of the bending tool proposed by the invention for panel bending.

[0044] FIG. 1 illustrates one embodiment of a bending tool 1 proposed by the invention having a longitudinal-offset measuring device 2, the bending tool 1 being the lower tool for air bending. The bending tool 1 has a tool body 3 with a longitudinal extension 4, in the direction of which longitudinal extension 4 a bending recess 5 is provided. The bending recess 5 extends from an upper flat side 6 of the tool body 3 into the latter and is formed by two contact surfaces 7. The transition region from the upper flat side 6 to the bending recess 5 forms a contact edge 8. Disposed in the region of the contact edge 8 is a sensor 10, which sensor 10 is configured to determine a longitudinal offset of the sheet to be bent in relation to the sensor. To this end, a sensing portion 11 of the sensor 10 is oriented in the direction of the sheet to be bent.

[0045] In FIG. 1, the sensor 10 is disposed solely in the region of a contact edge 8 but it would likewise be possible for a sensor to be provided on the second, oppositely lying contact edge 8 as well.

[0046] The sensor 10 is also connected to an evaluation circuit 12, which evaluation circuit 12 is connected to a machine controller, not illustrated, or is integrated in the latter. Furthermore, the evaluation circuit 12 may have an image analysis and comparison module.

[0047] In the description of FIG. 1, contact surfaces 7 are mentioned and it should be pointed out that the bending operation is not complete until the sheet is lying on the contact surfaces 7—in which case this would be a bottom bending operation. In the case of air bending, the sheet is pressed into the bending recess 5 but is so only until the desired bending geometry is obtained.

[0048] FIG. 2 illustrates another possible embodiment of the bending tool 1 proposed by the invention. In the case of this embodiment, the contact surfaces 7 are provided in the form of pivoting jaws 13, which pivoting jaws 13 can be pivoted about an axis 14 parallel with the contact line 9. In this embodiment, the contact surface 7 simultaneously also constitutes the upper flat side 6 of the tool body 3.

[0049] The advantage of a bending tool 1 having pivoting jaws 13 is that the sheet to be bent is placed on the upper flat side 6 or contact surfaces,7 and is supported by the latter across a large surface area. By contrast with the arrangement illustrated in FIG. 1, no linear force is applied along the contact line 9 during the bending operation in this instance. As soon as the sheet being bent is no longer being pressed into the bending recess 5 by the bending punch, the pivoting jaws 13 are pivoted about the pivot axis 14 so that the sheet being bent is always supported by the entire flat side of the contact surface 7 of each pivoting jaw 13. On completion of the bending operation, the pivoting jaws 13 are pivoted completely upwards to form a bending recess 5 with continuous contact surfaces—indicated by broken lines in the drawing.

[0050] Disposed in the region of the contact line 9 is a sensor 10 for determining a longitudinal offset and a sensing portion 11 of the sensor is oriented in the direction of the sheet to be bent.

[0051] In order to keep the drawings simple, the sheet to be bent is not illustrated in either FIG. 1 or FIG. 2. To the skilled person, however, it will be totally clear that the sheet to be bent is laid on the upper flat side 6 of the tool body 3. When the sheet metal part is being bent by the downwardly moving punch, the sheet is pressed into the bending recess 5, as a result of which the sheet is moved relative to the contact line 9. In particular, it is moved normally with respect to the contact line 9 in the direction of the bottom low point of the bending recess 5 and it is this longitudinal offset that is detected. To ensure that the sensor 10 cannot be damaged due to this longitudinal offset of the sheet as it is pushed against the contact surface 7 by the bending force, the sensor 10 may be mounted so that it is set back from the contact surface 7 by an offset 15.

[0052] Again in FIG. 2, only one sensor 10 is illustrated in one contact surface 7 but it would be equally possible to provide one sensor 10 each in both contact surfaces 7.

[0053] FIGS. 3a and 3b illustrate how the bending geometry is determined, in particular the side length, by determining the longitudinal offset of the sheet to be bent in the case of an embodiment of the bending tool 1 having pivoting jaws 13.

[0054] FIG. 3a illustrates the situation in the initial state when a sheet 16 to be bent has been placed on the contact surface 7 of the pivoting jaw 13. The pivoting jaws 13 are pivotable about a pivot axis 14 parallel with the contact line 9. The sensor 10 is mounted in the region of the contact edge or contact line 9 in such a way that when the pivoting jaws 13 are pivoted, no offset of the sensor occurs in relation to the contact line 9 and it is therefore exclusively a relative movement of the sheet 16 sliding relative to the sensor 10 that is detected.

[0055] The bending punch, not illustrated, transmits a force 17 onto the sheet 16 during the bending operation so that the latter is pressed into the bending recess 5. To this end, the pivoting jaws 13 are pivoted about the axis 14 so that the contact surfaces 7 of the pivoting jaws 13 always lie on the sheet 16.

[0056] Since the sheet 16 is pressed into the bending recess 5 during the bending operation, a relative movement occurs between the sheet 16 and contact surface 7. A surface point 19 will therefore move relative to the sensor 10. This situation is illustrated in FIG. 3b.

[0057] FIG. 3b illustrates the situation in which the desired bend has been obtained, when in particular the two pivoting jaws 13 have been fully pivoted, pressing the sheet 16 into the bending recess 5.

[0058] As may also be seen from FIG. 3, the bending operation results in a longitudinal offset 18 of a surface point 19 between the initial position (FIG. 3a) and the final position (FIG. 3b). In order to highlight the situation, the longitudinal offset has been very much exaggerated in the drawing. This longitudinal offset 18 has a direct influence in particular on the side length of the bent sheet metal part 16 that is obtained. As mentioned above, the pressing force and/or pressing depth for an air bending. operation is determined on the basis of a mathematical model of the bending operation. In particular, the set-point sheet thickness and set-point strength of the sheet have a major bearing on the determined parameters. In the event of any deviations from these set-point values, the bending angle obtained will also deviate and/or the side length will deviate so that the bending geometry obtained overall will deviate from what was intended. When it comes to bending complex sheet metal parts, however, the side length to be obtained is of particular importance because deviations in this respect can very rapidly accumulate to a degree beyond predefined tolerances.

[0059] By determining the current longitudinal offset 18 and comparing it with a set-point longitudinal offset determined using a bending model enables a conclusion to be drawn directly about the current actual side length.

[0060] In addition to the current side length obtained, it is also possible to use the longitudinal offset 18 to gain conclusive information about the bending angle obtained. The pressing depth being known, this value is determined by the machine controller of the bending press and the currently obtained bending angle can be determined from the longitudinal offset 18 via the mathematical model of the bending operation. Based on the set-point values of the bending parameters, a specific path of the material deformation between the contact line 9 or contact edge 8 and the contact point of the bending punch will occur in keeping with the model. This deformation path will also result in a specific longitudinal offset 18. If the material characteristic values are at variance with the set-point values, this will result in particular in a deviation of the determined longitudinal offset from the anticipated longitudinal offset. The currently obtained bending geometry and in particular a variance from the anticipated value can therefore be determined.

[0061] FIG. 4 is a diagram illustrating a detail of the sensor 10 for determining a longitudinal offset based on an example of a bending tool having pivoting jaws. The conditions described can also be directly applied to a lower tool for air bending. The sensor 10 is disposed in the tool body 3 of the bending tool 1 in such a way that no offset of the sensor 10 in relation to the contact line 9 or contact edge occurs during the bending operation. The sheet 16 to be bent lies on the contact surface 7 and is therefore pressed by the downwardly moving bending punch about the contact line 9 or contact edge against the contact surfaces 7 and thus bent.

[0062] Due to the bending operation, the sheet 16 is pressed in the direction of the bending recess so that a virtual surface point 19 of the sheet surface is moved relative to the sensor 10.

[0063] Based on one possible embodiment, the sensor 10 is provided in the form of an illuminating 21 and image capturing device 22. A portion on the sheet surface 20 is illuminated by the illuminating device 21, which illuminated portion is cyclically detected by the image capturing device 22. Due to the constant presence of the surface structure of the sheet surface 20, a constantly changing surface pattern is detected by the image capturing device 22 during the relative movement of the sheet 16 by reference to the sensor 10. The detected images are processed and analyzed by an evaluation circuit, not illustrated, in order to determine a motion vector from the successive images of the illuminated surface portion. Since the image detection frequency and determined motion vector are known, the real longitudinal offset can be determined. On the basis of this longitudinal offset and with a knowledge of the geometry of the bending tool 1, in particular the bending recess, the current bending angle and the currently obtained side length can be determined.

[0064] Such a design of sensor 10 having an illuminating 21 and image capturing device 22 is known from the field of optical computer mice, for example. In this instance, from the movement of the sensor in relation to a surface, in particular a desk surface, the movement of the computer mouse is detected and converted into the movement of a cursor on the monitor screen.

[0065] To protect the sensor 10 from the sheet 16 as it moves past the contact surface 7 or contact line 9, the sensing portion 11 of the sensor 10 is disposed at a distance from the contact surface 7 by an offset 15. This ensures that the sheet 16 pressed against the contact surface 7 or contact edge at a high pressure does not damage the sensing portion 11 during the relative movement.

[0066] The advantage of the lower tool proposed by the invention resides in the fact that essentially every bending machine can be equipped with a function for monitoring bending geometry without the need for physical modifications to the bending machine. An existing set of lower tools can be extended to incorporate a lower tool such as that proposed by the invention, thereby enabling the bending path to be monitored and the desired bending geometry to be adhered to during the course of a bending operation. The function proposed by the invention can also be used in a panel bender, in which case the aspects described in connection with the lower tool may be applied to the bending beam.

[0067] FIG. 5 illustrates a bending tool arrangement for use in a panel bending application where the bending tool 1 is a bending beam 23. The bending tool arrangement further comprises another clamping tool 24 and the sheet 16 to be formed is clamped between the upper and lower clamping tool. The sensor 10 is disposed in a front end 25 of the bending beam 23 and the light-emitting direction of the illuminating device 21 and the detecting area of the image capturing device 22 are oriented in the direction of the surface 20 of the sheet 16 to be formed.

[0068] FIG. 5a illustrates the situation prior to the start of the bending operation in which the bending beam 23 lies against or along the contact edge 8 on the surface 20 of the sheet 16. For this contact point, the co-ordinates of a surface point 19 are determined by reference to the bending tool arrangement or by reference to the bending machine. The other details as to how the surface point 19 is referenced were explained above.

[0069] FIG. 5b illustrates the situation after the bending operation has been completed, when the bending beam 23 has been moved by a drive means of the bending machine along a path and the bending beam 23 is now in a final position. Due to the pivoting movement of the bending beam 23, the surface point 19 has also shifted by the longitudinal offset 18 relative to the front end 25 of the bending beam 21 From this longitudinal offset 18 and the knowledge of the trajectory of the bending beam 23, information can be gleaned about the path of the bend between the front end 25 of the bending beam and the clamping tool 24 via the mathematical model of the bending operation.

[0070] Compared with a bending press, a panel bender offers more options for influencing the trajectory of the bending beam 23. This being the.case, corrective action can be taken on detection of a deviation in the path of the longitudinal offset 18 and the trajectory adapted accordingly so that the desired bending geometry can be obtained nevertheless.

[0071] FIG. 5 illustrates another possible embodiment in which a contact element 26 is disposed in the region of the front end 25 of the bending beam 23. Due to the very complex path of the trajectory along which the bending beam 23 can be pivoted, it may be that the contact edge 8 does not remain stationary relative to the bending beam 23. This situation may be seen in FIG. 5. Allowance can be made for this offset because the geometry of the bending beam 23 in the region of the contact edge 8 is known and therefore has only a minimal effect when determining the longitudinal offset 18. Under certain circumstances, however, there is a requirement for accuracy of the bending geometry, which makes it necessary to take account of this shifting of the contact edge 8. The advantage of the embodiment having a contact element 26 is that the force introduced by, the drive means of the bending machine into/onto the sheet can be uncoupled from the process of detecting the longitudinal offset 18.

[0072] This contact element 26 is provided in the form of a sensor disk and preferably also has a flat side which lies against the sheet 16 and therefore follows the pivoting movement of the sheet 16 relative to the bending beam 23. Since the contact element 26 is not subjected to force and therefore does not have to be involved in any forming work, the pivotable mounting may be based on a design that moves very easily. This makes it possible to adapt particularly effectively to the sheet as it is bent up, thereby ensuring accurate detection of the longitudinal offset 18.

[0073] It is also preferable if the sensor 10 follows the pivoting movement of the contact element 26 in terms of its orientation by providing a positive or non-positive connection between the sensor and the contact element. This ensures that the sensor always has the same orientation relative to the sheet and the measurement result for the longitudinal offset cannot be impaired due to a varying orientation between the sensor and sheet.

[0074] Finally, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc., relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described.

[0075] FIGS. 2 and 5 illustrate other and optionally independent embodiments of the bending tool proposed by the invention in their own right, the same reference numbers and component names being used to denote parts that are the same as those described in connection with the other drawings above. To avoid unnecessary repetition, reference may be made to the more detailed description of these drawings given above.

[0076] The embodiments illustrated as examples represent possible variants of the bending tool, and it should be pointed out at this stage that the invention is not specifically limited to the variants specifically illustrated, and instead the individual variants may be used in different combinations with one another and these possible variations lie within the reach of the person skilled in this technical field given the disclosed technical teaching.

[0077] Furthermore, individual features or combinations of features from the different embodiments illustrated and described may be construed as independent inventive solutions or solutions proposed by the invention in their own right.

[0078] The objective underlying the independent inventive solutions may be found in the description.

[0079] All the figures relating to ranges of values in the description should be construed as meaning that they include any and all part-ranges, in which case, for example, the range of 1 to 10 should be understood as including all part-ranges starting from the lower limit of 1 to the upper limit of 10, i.e. all part-ranges starting with a lower limit of 1 or more and ending with an upper limit of 10 or less, e.g. 1 to 1.7, or 12 to 8.1 or 5.5 to 10.

[0080] Above all, the individual embodiments of the subject matter illustrated in FIGS. 1 to 5 constitute independent solutions proposed by the invention in their own right. The objectives and associated solutions proposed by the invention may be found in the detailed descriptions of these drawings.

[0081] For the sake of good order, finally, it should be pointed out that, in order to provide a clearer understanding of the structure of the bending tool, it and its constituent parts are illustrated to a certain extent out of scale and/or on an enlarged scale and/or on a reduced scale.

LIST OF REFERENCE NUMBERS

[0082] 1 Bending tool

[0083] 2 Longitudinal offset measuring device

[0084] 3 Tool body

[0085] 4 Longitudinal extension

[0086] 5 Bending recess

[0087] 6 Flat side

[0088] 7 Contact surface

[0089] 8 Contact edge

[0090] 9 Contact line

[0091] 10 Sensor

[0092] 11 Sensing portion

[0093] 12 Evaluation circuit

[0094] 13 Pivoting jaw

[0095] 14 Pivot axis

[0096] 15 Offset

[0097] 16 Sheet, sheet metal part

[0098] 17 Force

[0099] 18 Longitudinal offset

[0100] 19 Surface point

[0101] 20 Sheet surface

[0102] 21 Illuminating device

[0103] 22 Image capturing device

[0104] 23 Bending beam

[0105] 24 Clamping tool

[0106] 25 Front end

[0107] 26 Contact element