METHOD FOR OFFSET MEASURE COMPENSATION

Abstract

A method for recognition and compensation of an offset measure between stamping coordinates of a stamping device and laser coordinates of a laser device in a combined stamping-laser machine for processing a plate-shaped workpiece, particularly a metal sheet, includes introducing a structure into the plate-shaped workpiece by respectively using the stamping device or the laser device. A measurement variable of the introduced structure is determined respectively by the laser device or the stamping device. The measurement variable is compared with an expected variable, and a deviation of the measurement variable from the expected variable corresponds to an offset measure. The offset measure is balanced with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system in order to compensate for the offset measure between the stamping coordinates and the laser coordinates.

Claims

1-21. (canceled)

22. A method for recognition and compensation of an offset measure between stamping coordinates of a stamping device and laser coordinates of a laser device in a combined stamping-laser machine for processing a plate-shaped workpiece or metal sheet, the method comprising: a. using the stamping device or the laser device to introduce a structure into the plate-shaped workpiece; b. using the laser device or the stamping device to determine a measurement variable of the introduced structure; c. comparing the measurement variable with an expected variable to obtain a deviation of the measurement variable from the expected variable corresponding to an offset measure; and d. balancing the offset measure with the coordinates of the laser device in a laser coordinate system or with the coordinates of the stamping device in a stamping coordinate system to compensate for the offset measure between the stamping coordinates and the laser coordinates.

23. The method according to claim 22, which further comprises: in step a. introducing a perforation into the workpiece by using the stamping device or the laser device; in step b. determining a point unambiguously describing the perforation or a center point of the perforation, by using the laser device or the stamping device; in step c. carrying out a process of determining whether a position of the determined center point corresponds to an expected position of the center point, and obtaining a deviation of the determined position from the expected position corresponding to an offset measure; and in step d., upon a determined deviation of the actual center point from the expected center point, carrying out a compensation of the offset measure by balancing the offset measure with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system to compensate for the offset measure between the stamping coordinates and the laser coordinates.

24. The method according to claim 23, which further comprises determining the center point by emission of a detection light beam and by detection of transmitted, emitted or reflected light based on the detection light beam.

25. The method according to claim 24, which further comprises forming the perforation in circular fashion, determining the center point by crosswise displacement of the workpiece relative to the laser device or to the stamping device, and emitting the detection light beam by using the laser device or the stamping device.

26. The method according to claim 22, which further comprises carrying out steps a. to d. in a plurality of workpiece sections of the workpiece, determining the offset measure for each workpiece section, and balancing the offset measure with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system in each workpiece section to compensate for the offset measure between the stamping coordinates and the laser coordinates in respective workpiece sections.

27. A method for recognition and compensation of an offset measure between stamping coordinates of a stamping device and laser coordinates of a laser device in a combined stamping-laser machine for processing a plate-shaped workpiece or metal sheet, the method comprising: a. introducing a respective structure into the plate-shaped workpiece by using the stamping device and by using the laser device; b. determining measurement variables of the introduced structures by using the stamping device or by using the laser device; c. comparing the measurement variables with an expected variable to obtain a deviation of the measurement variables from the expected variables corresponding to an offset measure; and d. balancing the offset measure with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system to compensate for the offset measure between the stamping coordinates and the laser coordinates.

28. The method according to claim 27, which further comprises: in step a. introducing a respective perforation into the workpiece by using the stamping device and the laser device; in step b. determining a point each unambiguously describing the perforations or a respective center point of the respective perforation, by using the laser device or the stamping device; in step c. carrying out a process of determining whether the position of the determined center points with respect to one another corresponds to an expected position of the center points with respect to one another, to obtain a deviation of the determined position of the center points with respect to one another corresponding to an offset measure; and in step d., upon a determined deviation of the actual position of the determined center points with respect to one another from the expected position of the center points with respect to one another, carrying out compensation of the offset measure by balancing the offset measure with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system to compensate for the offset measure between the stamping coordinates and the laser coordinates.

29. The method according to claim 28, which further comprises determining the respective center point by emission of a detection light beam and by detection of transmitted, emitted or respectively reflected light based on the detection light beam.

30. The method according to claim 29, which further comprises forming the perforations in circular fashion, determining the respective center point by crosswise displacement of the workpiece relative to the laser device or to the stamping device, and emitting the detection light beam by using the laser device or the stamping device.

31. The method according to claim 27, which further comprises carrying out steps a. to d. in a plurality of workpiece sections of the workpiece, determining the offset measure for each workpiece section, and balancing the offset measure with the coordinates of the laser device in the laser coordinate system or with the coordinates of the stamping device in the stamping coordinate system in each workpiece section to compensate for the offset measure between the stamping coordinates and the laser coordinates in respective workpiece sections.

32. A method for recognition and compensation of an offset measure of a coordinate system of a processing machine for processing a workpiece or a plate-shaped workpiece or a metal sheet, the method comprising: a. introducing a structure into the workpiece by using the processing machine; b. processing the workpiece by using the processing machine and, after processing progress, determining a position of the introduced structure in the coordinate system of the processing machine by using the processing machine; c. comparing the determined position with an expected position to obtain a deviation of the determined position from the expected position corresponding to an offset measure; and d. balancing the offset measure with coordinates in the coordinate system of the processing machine to compensate for the offset measure.

33. The method according to claim 32, which further comprises providing the processing machine as a stamping or laser processing machine.

34. The method according to claim 32, which further comprises providing the processing machine as a combined stamping-laser machine, and balancing at least one of the coordinates of the laser device in the laser coordinate system or the coordinates of the stamping device in the stamping coordinate system with the determined offset measure to compensate for the offset measure.

35. A method for recognition and compensation of an offset measure of a coordinate system of a processing machine for processing a workpiece, a plate-shaped workpiece or metal sheet, the method comprising: a. measuring at least one of a length or a width of the workpiece; b. processing the workpiece by using the processing machine and, after processing progress, once again determining at least one of the length or the width of the workpiece by using the processing machine; c. determining a deviation of at least one of a determined length or a determined width from at least one of an expected length or an expected width to obtain a deviation of at least one of the determined length or the determined width from at least one of the expected length or the expected width corresponding to an offset measure; and d. balancing the offset measure with coordinates in the coordinate system of the processing machine to compensate for the offset measure.

36. The method according to claim 35, which further comprises determining at least one of only a partial length or only a partial width in step b., and determining a deviation of at least one of the determined partial length or the determined partial width from at least one of the expected partial length or the expected partial width in step c.

37. The method according to claim 35, which further comprises providing the processing machine as a stamping or laser processing machine.

38. The method according to claim 35, which further comprises providing the processing machine as a combined stamping-laser machine, and balancing at least one of the coordinates of the laser device in the laser coordinate system or the coordinates of the stamping device in the stamping coordinate system with the determined offset measure to compensate for the offset measure.

39. A control device embodied and configured for carrying out the method according to claim 22.

40. A control device embodied and configured for carrying out the method according to claim 27.

41. A control device embodied and configured for carrying out the method according to claim 32.

42. A control device embodied and configured for carrying out the method according to claim 35.

43. A processing machine or a combined stamping-laser machine, laser machine or stamping machine, comprising a control device according to claim 39.

44. A processing machine or a combined stamping-laser machine, laser machine or stamping machine, comprising a control device according to claim 40.

45. A processing machine or a combined stamping-laser machine, laser machine or stamping machine, comprising a control device according to claim 41.

46. A processing machine or a combined stamping-laser machine, laser machine or stamping machine, comprising a control device according to claim 42.

Description

[0082] In the figures:

[0083] FIG. 1 shows a perspective illustration of a combined stamping-laser machine;

[0084] FIG. 2 shows a schematic illustration of a method for recognition and compensation of a stamping-laser offset measure in accordance with a first embodiment;

[0085] FIG. 3 shows a schematic illustration of a method for recognition and compensation of a stamping-laser offset measure in accordance with a second embodiment; and

[0086] FIGS. 4 a) to e) show a schematic illustration of a method for recognition and compensation of a stamping-laser offset measure in accordance with a third embodiment.

[0087] FIG. 1 schematically shows one embodiment of a combined stamping-laser machine 1 with which a workpiece 14, for example in the form of a metal sheet, can both be stamped by means of stamping processing and be processed, in particular cut, by means of laser processing. One part of the processing machine 1 is a C-frame 2. The C-frame 2 consists of a torsionally rigid welded structure made of steel. However, the C-frame 2 can also be embodied in a different form. A control device 3 for controlling the functions of the processing machine 1 is provided at the rear end of the C-frame 2.

[0088] The processing machine 1 comprises, at the front inner end of the upper limb of the C-frame 2, a stamping device 17 with an upper tool receptacle 4 and with a lower tool receptacle 5 at the front inner end of the lower limb of the C-frame 2. The upper tool receptacle 4 can receive a tool upper part of a stamping tool 7 and the lower tool receptacle 5 can receive a tool lower part of the stamping tool 7.

[0089] The upper tool receptacle 4 is movable in an axial direction (Z-direction) by means of a plunger (not shown) and is controlled with the aid of the control device 3 in such a way that it can both perform a complete stroke and stop in any desired position within its axial stroke path. Furthermore, the upper tool receptacle 4 is optionally rotatable about an axial rotation axis 6, in a manner controlled by the control device 3.

[0090] The lower tool receptacle 5 is optionally likewise rotatable about its rotation axis 6. Furthermore, the lower tool receptacle 5 is nonmovable in its axial direction (Z-direction), but can optionally also be embodied as a so-called active die. It can then likewise move in its axial direction and, in a manner controlled by the control device 3, stop in any desired position of its axial stroke path.

[0091] Besides the upper tool receptacle 4 and the lower tool receptacle 5, the processing machine 1 also comprises a laser processing device 8 having a laser processing head 16, with which for example the workpiece 14 can be processed, in particular cut. A circular opening 10 is provided in a workpiece table 9 on the inner side of the lower limb of the C-frame 2. The laser processing head 16 is movable in an X-direction and in a Y-direction and also, in order to set a suitable focus position, in the Z-direction by means of a movement unit (not shown). The circular opening 10 substantially defines a processing region 11 of the laser processing head 16.

[0092] The workpiece table 9 has a transverse rail 12 with a tool magazine. Clamping jaws 13 for fixedly holding the workpiece 14, which can be present in particular in the form of a sheet-metal plate, are arranged on the transverse rail 12. The clamping jaws 13 can be secured at suitable locations on the transverse rail 12, and can be offset in such a way that the sheet-metal plate 14 is held securely, but the sheet-metal plate 14 is not gripped at an area to be processed. A plurality of, here three, tool receptacles 15 for a plurality of, here two, stamping tools 7 are shown in the tool magazine.

[0093] During operation, the workpiece table 9 can be moved into a programmed position for the purpose of stamping in a Y-direction together with the transverse rail 12, to which are secured the clamping jaws 13 used to hold the workpiece 14. The transverse rail 12 can equally be moved into the programmed position in the X-direction, the workpiece 14 sliding over the workpiece table 9. A stamping stroke can then be carried out by the upper tool receptacle 4. After that, the next stamping position can be moved to according to the same principle. The workpiece 14 can be moved to a programmed position according to the same principle in order to carry out laser processing by means of the laser processing machine 8.

[0094] In order then to process a workpiece, the following procedure is regularly adapted: Firstly, stamping processings are introduced at programmed positions on the workpiece 14 by means of the stamping device 17. In this case, the positions for the stamping processings are stored as coordinates in a stamping coordinate system. Laser processings can subsequently be carried out by means of the laser processing device 8. In this case, individual parts having a stamping processing are regularly cut out from the workpiece 14 by means of laser cuts. In this case, the laser processings are likewise carried out at programmed positions of the workpiece that are stored in a laser coordinate system.

[0095] If there is no offset measure present between the stamping coordinate system and the laser coordinate system, then a point on the workpiece 14 has the same coordinates in both coordinate systems. However, an offset measure regularly occurs between the two coordinate systems. In this case, said offset measure may be different depending on the machine and may vary in particular over the period of use of the combined stamping-laser machine 1. This is owing for example to manufacturing tolerances of the machine elements, thermal expansion of the mechanisms, collisions, manufacturing tolerances for different cutting heads, ageing and heat-dictated expansion of the workpiece 14 during processing, in particular during the laser processings. The stamping-laser offset measure occurring in this way can be stored as an offset measure, wherein the coordinates in the laser coordinate system are balanced with the offset measure, such that the laser processings are also actually carried out at the desired location in the workpiece 14.

[0096] Three embodiments of a method for automatic recognition and compensation of an offset measure between the stamping coordinates of the stamping device 17 and the laser coordinates of the laser device 8 are set out below:

[0097] FIG. 2 shows a first embodiment of the method. If it has been decided that the offset measure is intended to be determined, or whether an offset measure already stored is still correct, then a circular perforation 19, i.e. a hole, is stamped at a defined location on the workpiece 14. As an alternative thereto, such a hole that is already present in the workpiece 14 as stamping processing could be used. The laser processing head 16 is then moved over the hole 19 produced in the workpiece 14. A laser beam 18 is subsequently generated by the laser device 8. If the laser beam 18 directs laser radiation at the workpiece 14, then the workpiece 14 becomes hot, and so the latter emits process light 24. Said process light 24 can be detected. It is thus possible to determine whether the laser radiation 18 is incident on the workpiece 14. Specifically, if the laser beam 18 radiates onto the hole 19, then at least virtually no process light 24 arises and the signal of the process light 24 collapses. A laser processing device 8 with a detection unit for determining the intensity of the process light 24 is previously known from DE 10 2010 028 179 A1, the disclosure content of which in this regard is concomitantly incorporated in the disclosure content of the present application. The laser processing device 8 accordingly comprises such an evaluation unit.

[0098] The laser beam 18 is then moved firstly in an X-direction 35, specifically until the signal intensity 37 of the detected process light increases and exceeds a defined threshold value. It is subsequently moved in the opposite direction, once again until the light intensity increases. In this case, an increase in the light intensity indicates that the edge 20, 21 of the hole 19 has been reached. The laser beam 18 is then moved in the Y-direction 39 until the edge 22 of the hole 19 is reached, and it is finally moved in the opposite direction once again until the edge 23 of the hole 19 is reached. Overall, the center point m of the hole 19 can be determined from the coordinates of the edges 20, 21, 22, 23 that have been determined in this way.

[0099] The center point m determined in this way has, in the laser coordinate system, the actual coordinates of the center point m on the workpiece 14. Said center point m is then compared with the expected coordinates of the expected center point m*. Said expected center point m* has coordinates in the laser coordinate system which represent the expected position of the center point without (correct) offset measure compensation. In the case shown in FIG. 2, there is an offset measure—not yet corrected—between the stamping coordinates and the laser coordinates by an offset measure ΔX in the X-direction and by an offset measure ΔY in the Y-direction. The programmed coordinates in the laser coordinate system are then (re)corrected in the X- and Y-directions by said offset measure, such that the laser processing by means of the laser beam 18 is carried out exactly at the actually desired location on the workpiece 14.

[0100] FIG. 3 shows a second embodiment for determining the stamping-laser offset measure. In this case, firstly a hole 25 is stamped into the workpiece 14 by means of the stamping device 17. In addition, a hole 26 is cut by the laser processing device 8. The offset measure between the two holes can then be determined by means of a detection unit (not shown) arranged at the stamping device 17. Such a detection unit is previously known for example from EP 2 878 393 A1, the disclosure content of which in this regard is fully concomitantly incorporated in the disclosure content of the present patent application.

[0101] The method then proceeds as follows: The detection unit in the stamping device 17 comprises means for directing a laser beam at the workpiece 14, and means for detecting the emitted process light of the workpiece or reflected laser light. The actual position of the respective center point is determined, as explained above with regard to FIG. 2, by crosswise displacement of the laser beam and determination of the signal intensity. In this case, the detected radiation intensity collapses when the laser beam is in the region of the hole 25 or respectively the hole 26. A deviation of the position of the actual center points from the expected position of the center points in the stamping coordinate system is determined overall. In the embodiment shown in FIG. 3, in this case the determination is carried out by means of the detection unit of the stamping device 17. Consequently, the center point m1 of the hole 25 is actually where it is expected. However, the center point m2 of the hole 26 is at different coordinates than expected. The center point would have been expected at the coordinates of the position m*. There is thus an offset measure ΔX in the X-direction and respectively ΔY in the Y-direction, which offset measure has not yet been corrected. The coordinates in the laser coordinate system can be (re)corrected by said offset measure in order to compensate for the offset measure.

[0102] FIG. 4a shows a workpiece 14 arranged at clamping jaws 13, as described above. Along the length 27 of the workpiece 14 in the X-direction, by means of the laser radiation 18 of the laser processing device 8, the length l.sub.1 of the workpiece 14 in the X-direction is then determined by once again analyzing when the intensity of the reflected radiation or of the detected process light collapses.

[0103] In a next step, as indicated in FIG. 4b, stamping processings in the form of holes 28, 29 situated next to one another, which are introduced repeatedly into the workpiece 14, are introduced into the workpiece 14. A laser processing of the workpiece 14 then takes place, as is shown in FIG. 4c, wherein a laser cut 30 is carried out in each case around a pair of the holes 28, 29, such that a workpiece part 31 is detached from the workpiece 14. A heat input into the workpiece 14, which can be embodied as a metal sheet, in particular, takes place in the course of this processing. The workpiece 14 expands as a result. This in turn results in an offset measure—not yet corrected—between the stamping coordinates and the laser coordinates, which offset measure is determined and corrected by means of the following method:

[0104] As is shown in FIG. 4d, the last section of the workpiece 14 has not yet been processed by means of laser processing. By means of the laser cutting machine 8, the last part of the workpiece 14 is traversed starting from the starting point 32 until the edge 33 is reached, at which the detected light signal collapses, a laser beam being directed at the workpiece 14. On the basis of the previous measurement, a length l.sub.2* between the starting point 32 and the expected end point 33* of the workpiece 14 was expected for this. Owing to the thermal expansion, however, the actual end point is at the position 33, such that an actual length 12 is measured. In this respect, there is a difference between the position 33 and the position 33* in the X-direction. Said difference represents an offset measure ΔX that has not yet been corrected. The coordinates in the laser coordinate system can then be (re)corrected by said offset measure ΔX. As a result, as is shown in FIG. 4e, the laser cut 30 can be carried out at coordinates in the laser coordinate system which have been (re)corrected by the offset measure ΔX, thus resulting in a sufficient production accuracy of the workpiece parts 31 even toward the end of the cutting process.

[0105] The embodiment in accordance with FIG. 4 can be used in other processing machines as well. By way of example, offset compensation in pure stamping machines or laser machines would be conceivable. In such processing machines, over the processing duration of a workpiece, owing to thermal expansion, particularly in the case of laser machines, and/or mechanical deformation, particularly in the case of stamping machines, an offset measure (not yet corrected) can occur which can be detected and can be compensated for by way of the procedure shown in FIG. 4. In the case of stamping machines, a detection unit comprising a laser beam source can be provided for determining the offset.

[0106] Overall, automatic recognition and compensation of the stamping-laser offset measure in a combined stamping-laser machine 1 can be carried out according to the invention.

[0107] This obviates the error-susceptible and complicated manual determination and compensation of the offset measure. It goes without saying, however, that a manual measurement and correction could be carried out as redundancy with respect to the automatic measurement and correction according to the invention.

[0108] In accordance with the embodiment according to FIG. 4, it is possible to compensate for a, for example heat- or deformation-dictated, change in constitution of a workpiece during the processing thereof in other processing machines as well, such as pure stamping machines or laser machines, for example.