Laser processing device and method for operating

Abstract

The invention relates to a laser processing device (10) for laser processing of workpieces (12), comprising a laser head (18) with a first laser beam source (20) for generating a working laser beam (22) for processing the workpiece (12) and with a second laser beam source (24) for generating a pilot laser beam (26) for aligning the first laser beam source, as well as a method for determining the functionality of at least one deflecting mirror (42, 44).

Description

[0001] The invention relates to a laser processing device and a method for operating the laser processing device.

[0002] German patent DE 198 294 96 A1 describes a method for laser marking of objects using a high-energy working laser. Due to the high power of the working laser, a secure enclosure is required to prevent the laser beam from escaping uncontrollably into the environment. In particular, there is a risk that if a deflecting mirror malfunctions, the laser beam could be directed onto the enclosure due to an incorrect mirror position.

[0003] The current state of the art proposes reinforcing the housing to solve this problem. However, this method has several disadvantages. Firstly, in the event of a defect, the laser beam often concentrates on the same spot in the housing, meaning that a complete breach cannot be prevented. Secondly, there is a risk that the high energy of the laser beam will damage workpieces by focusing on a single point and removing material there (pitting corrosion).

[0004] German patent DE 10 2022 116 040 A1 describes a device for the dynamic positioning of multiple laser beams on a target plane, which includes a dynamic deflection device with which the laser beams in a so-called multi-beam matrix can be directed onto the target plane. Prior art provides laser positioning systems for this purpose, which enable highly dynamic positioning of laser beams within a multi-beam matrix. However, these systems only allow the positioning or guidance of the multi-beam matrix as a whole and lead to distortion of the multi-beam matrix and thus to positioning errors of the individual beams in the target plane. These positioning errors of the individual beams reduce the achievable precision of the processing process. Prior art suggests using a separate positioning system for a single beam or a single-beam system.

[0005] The invention is based on the objective of providing a laser processing device which prevents and, in particular, predicts an uncontrolled escape of the working laser, as well as enabling the determination of a positional error of a single laser beam, in particular of the working laser.

[0006] The problem underlying the invention is solved by a laser processing device with the features of claim 1. The invention relates to a laser processing device for laser processing, in particular laser marking, of workpieces, comprising a laser head. The laser head comprises a first laser beam source, in particular a working laser, for generating a working laser beam for processing the workpiece and a second laser beam source, in particular a pilot laser, for generating a pilot laser beam for aligning the first laser beam source.The laser processing device further comprises a laser deflection device with at least one movable deflection mirror for coaxially deflecting the working laser beam and the pilot laser beam, such that the working laser beam and the pilot laser beam are directed from a beam output of the laser head towards a focus area in which the workpieces are processed along a laser beam direction; a detection device for detecting the pilot laser beam; a control device for controlling the second laser beam source and the laser deflection device, wherein the control device is configured such that it checks the functionality of the at least one deflection mirror during a secondary time of the laser processing device, depending on data generated by the detection device.

[0007] For aligning and monitoring the deflecting mirrors, a second laser beam source is additionally used to generate a pilot laser beam, whereby the pilot laser beam and the working laser beam are coaxial.

[0008] The pilot laser beam is preferably a red laser (laser class 1 or 2). Accordingly, the pilot laser beam can be used for preliminary monitoring of the working laser. The second laser beam source preferably serves as a reference source. Due to its low power, the pilot laser beam is relatively safe for an operator and can therefore also be operated when an operator is working within the working area of ​​the laser processing device.

[0009] To prevent the working laser from malfunctioning and / or, for example, incorrect marking of the workpieces being processed, it is not the working laser beam but the pilot laser beam that is monitored.

[0010] During the off-peak time of the laser processing device, the movements of at least one deflecting mirror can be monitored using the pilot laser beam. Therefore, the functionality of at least one deflecting mirror can be checked without using the hazardous working laser and without interfering with the main processing time of the laser processing device.

[0011] The main processing time of a laser processing device encompasses the time during which the laser beam actively interacts with the workpiece, i.e., the actual processing takes place, such as cutting, engraving, or marking. This time is directly productive, as it is during this time that the desired material processing occurs. In contrast, the non-productive time includes all processes that do not directly contribute to the processing, such as setting up the machine, aligning the workpiece, changing tools or workpieces, or adjusting the laser. The goal is to optimize the proportion of main processing time by reducing non-productive time, either by shifting upstream or downstream processes into system-related downtimes, either in time or in parallel.

[0012] Since the laser deflection device deflects the working laser beam and the pilot laser beam coaxially, a defect in one deflection mirror affects both the working laser beam and the pilot laser beam. Therefore, a deviation in the position of the pilot laser beam indicates a defect in at least one deflection mirror.

[0013] Should the control device detect a deviation of an actual contour of the pilot laser beam from a target contour of the pilot laser beam, the control device can report a defect and preferably stop further processing.

[0014] Regular monitoring of at least one deflection mirror ensures a high level of safety and processing quality. Distorted, blurred, and ambiguous markings are prevented during laser marking.

[0015] It is advantageous if the control device is set up in such a way that it checks the functionality of the at least one deflecting mirror depending on a comparison between an actual contour and a target contour, in particular a comparison between at least one quantity characterizing the actual contour and at least one quantity characterizing the target contour.

[0016] The first laser beam source is preferably designed as a fiber laser in the infrared spectrum (laser class 4).

[0017] Preferably, the laser deflection device has two deflection mirrors, wherein a first deflection mirror facilitates movement of the laser beams along an x-axis and a second deflection mirror facilitates movement of the laser beams along a y-axis perpendicular to the x-axis. With respect to the direction of gravity, the x-axis is preferably horizontal and the y-axis vertical. For this purpose, the deflection mirrors are each pivoted about at least one pivot axis. If one of the two deflection mirrors is defective, the control device detects a lack of movement along the x-axis or the y-axis. From this, it can then be determined which of the two deflection mirrors is defective.

[0018] An advantageous aspect of the invention is that the focus area is arranged between the beam output and the detection device. Accordingly, monitoring the deflecting mirrors by means of the pilot laser has no influence on the processing process during the main processing time.

[0019] An advantageous aspect of the invention is that the detection device comprises a camera and / or a photodiode and / or a radiation-sensitive detector. Thus, a simple and reliable detection device is provided.

[0020] An advantageous aspect of the invention provides that the laser deflection device is configured such that the second laser beam, particularly during the off-peak period, is directed directly from the beam output to the detection device. Accordingly, the detection device can reliably detect the movement of the pilot laser beam.

[0021] An advantageous aspect of the invention provides that the detection device includes a projection element for imaging the second laser beam. The projection element is preferably arranged at a distance from the camera. This allows for a simple setup, whereby the movement of the pilot laser beam on the projection element can be detected by means of the camera and image recognition.

[0022] An advantageous aspect of the invention provides that, when the pilot laser beam is directed at the enclosure, the detection device, in particular the camera, recognizes the pilot laser beam and can thus detect damage to the enclosure.

[0023] The camera's exposure time is preferably in the range between 0.1 s and 1 s. This allows the actual contour of the pilot laser beam to be captured particularly well.

[0024] An advantageous aspect of the invention is that the projection element is arranged between the beam output and / or the focus area and the camera. Accordingly, the camera is located outside the processing area. Therefore, no changeover is required between the main processing time and the auxiliary processing time to assess the functionality of the at least one deflecting mirror.

[0025] An advantageous aspect of the invention is that the projection element is at least partially transparent. The projection element is preferably designed as a ground glass screen or, in particular, a white polycarbonate screen. This allows the camera to easily detect the actual contour of the pilot laser beam through the projection element. The projection element preferably has a projection thickness parallel to the beam direction, in a range between 1 mm and 5 mm.

[0026] An advantageous aspect of the invention provides that the laser deflection device is configured such that the pilot laser beam is directed directly from the beam output onto a laser side of the projection element facing the beam output. The camera is preferably configured to capture the pilot laser beam on a camera side of the projection element opposite the laser side.

[0027] An advantageous aspect of the invention is that the control device is configured such that the pilot laser beam traces a two-dimensional contour on the projection element. This two-dimensional contour can be used to determine whether the deflecting mirrors are fully functional. Preferably, the target contour runs obliquely to the x-axis and obliquely to the y-axis. The target contour can, for example, be a circle or an ellipse. Alternatively, the target contour can be a straight line running at an angle of 45° to both the x-axis and the y-axis. It is conceivable that the target contour is traced multiple times, preferably to detect hysteresis (positional deviation when changing direction).

[0028] It is conceivable that the control device detects a characteristic parameter of the actual contour. For target contours such as a circle, the diameter or circumference could be detected; for an ellipse, the height and width; and for a straight line, the length or angle. If the respective characteristic parameter of the actual contour deviates by at least 5%, in particular at least 10%, preferably at least 15%, and preferably at least 20% from the respective characteristic parameter of the target contour, then a defect in the at least one deflecting mirror is to be assumed. For example, the angle for a straight line could be 45° to both the x-axis and the y-axis. As soon as the angle is less than 40° to one of the axes or more than 50° to one of the axes, a defect is reported.

[0029] The target contour and / or at least one characteristic parameter of the target contour can preferably be stored in a database. The control device is provided with the target contour and / or at least one characteristic parameter of the target contour for comparison with the actual contour or the characteristic parameter of the actual contour.

[0030] To report a defect, for example a screen or an optical warning signal in the form of a lamp can be provided on the laser processing device and / or in its vicinity.

[0031] The projection element and the focus area are preferably spaced apart from each other. An advantageous aspect of the invention provides that the projection element is spaced a projection distance from the focus area. The projection distance is preferably in a range between 50 mm and 500 mm, particularly between 100 mm and 400 mm, and preferably between 200 mm and 300 mm. This has the advantage that the pilot laser beam spreads out from the focus area towards the projection element. Consequently, the pilot laser beam strikes the projection element over a wider cross-section. This makes it easier for the camera and / or image recognition system to detect the actual contour of the pilot laser beam. Therefore, a deviation of the actual contour from the target contour of the pilot laser beam, and thus a defect in a deflecting mirror, can be detected more reliably.The projection distance is in particular greater than 50 mm, in particular greater than 100 mm, preferably greater than 150 mm, preferably greater than 200 mm.

[0032] The camera and / or projection element can be fixedly mounted to an enclosure, in particular the floor of the working area of ​​the laser processing device. Alternatively, a handling device can carry the camera and / or projection element and position it at the test position during the off-peak time to check the functionality of the at least one deflecting mirror. During the main processing time, the camera and / or projection element can be mounted on the ceiling of the enclosure. This means that the working area at the floor of the enclosure is not occupied by the camera and / or projection element during the main processing time.

[0033] The problem underlying the invention is also solved by a method with the features of claim 11. The invention is directed to a method, in particular a computer-implemented method, for operating a laser processing device, especially according to one of the preceding claims, comprising the following steps: processing a workpiece by means of a working laser beam during a main cycle of the laser processing device; moving a pilot laser beam along an actual contour during a secondary cycle of the laser processing device; detecting the actual contour of the pilot laser beam by means of a detection device; and comparing a target contour of the pilot laser beam and the actual contour by means of a control device to determine the functionality of a laser deflection device with at least one movable deflection mirror. Preferably, the determination is repeated after each processing cycle, i.e., after each main cycle.This ensures that a defect in a deflecting mirror is detected promptly.

[0034] The method, in particular computer-implemented, is preferably implemented by the control device, which includes a programmable logic controller (computer) and a database for storing process-relevant data.

[0035] An advantageous aspect of the invention provides that the pilot laser beam is directed directly or indirectly at the detection device.

[0036] An advantageous aspect of the invention provides that the pilot laser beam is directed towards a laser side of a projection element, and wherein the detection device detects the actual contour of the pilot laser beam on a camera side of the projection element opposite the laser side, which is facing the camera.

[0037] An advantageous aspect of the invention provides that the projection element, in particular the laser side and / or the camera side, extends along an x-axis and a y-axis perpendicular to the x-axis, wherein the desired contour runs obliquely to the x-axis and obliquely to the y-axis, in particular at an angle of 45° to the x-axis and to the y-axis.

[0038] The problem underlying the invention is also solved by a monitoring device for monitoring a laser head and / or a laser deflection device. The monitoring device comprises a detection device, in particular a camera, a projection element, in particular a Makrolon disc, and a control device, which is configured to detect the actual contour of a pilot laser beam and, based on a comparison between the actual contour and a target contour, to determine the functionality of at least one deflection mirror.

[0039] Further advantages, features, and details will become apparent from the following description, in which various embodiments of the invention are illustrated with reference to the drawing. The features mentioned in the claims and the description can each be essential to the invention individually or in any combination.

[0040] They show: Fig. 1 a laser processing device in one main time; Fig. 2 a laser processing device in a secondary time; Fig. 3A a projection element with a straight line as the target contour; Fig. 3B a projection element with a circle as the target contour; Fig. 3C a projection element with a to Fig. 3A corresponding actual contour, where the deflection mirror for the movement along the y-axis is defective; Fig. 3D a projection element with a to Fig. 3B corresponding actual contour, where the deflection mirror for the movement along the y-axis is defective; Fig. 4 a laser head with two laser sources and a laser deflection device; and Fig. 5 a schematic representation of a reflected light process.

[0041] The laser processing device 10 for processing, in particular for laser marking, workpieces 12 has according to Fig. 1 and Fig. 2. A housing 14 with a working chamber 16. In the working chamber 16 is a laser head 18 with a first laser beam source 20, in particular a working laser beam source, for generating a non-visible working laser beam 22 and with a second laser beam source 24, in particular a pilot laser beam source, for generating a visible pilot laser beam 26.

[0042] The laser head 18 is in Fig. Figure 4 shows the working laser beam 22 emerging from the first laser beam source 20 along a principal axis 28. The pilot laser beam 26 emerging from the second laser beam source 24 along a secondary axis 30. The principal axis 28 and the secondary axis 30 are parallel to each other and spaced apart. The laser head 18 is preferably a component of the laser deflection device 32 for deflecting the working laser beam 22 and the pilot laser beam 26. The laser deflection device 32 has a stationary first mirror 34, in particular a deflection mirror, for deflecting the pilot laser beam 26 towards the working laser beam 22. The laser deflection device 32 further has a stationary, partially transparent second mirror 36, in particular a deflection mirror, which deflects the pilot laser beam 26 into the principal axis 28, with the working laser beam 22 passing through the second mirror 36.According to this, after the second mirror the working laser beam and the pilot laser beam preferably run coaxially.

[0043] Along a laser beam direction 38, the working laser beam 22 and the pilot laser beam 26 are further deflected by means of the laser deflection device 32, so that the working laser beam 22 can process, in particular mark, a workpiece 12 in a focus area 40. The laser deflection device 32 is preferably designed such that the working laser beam 22 and / or the pilot laser beam 26 have their focus position in the focus area 40. Accordingly, workpieces 12 can be processed with high precision in the focus area 40.

[0044] The laser deflection device 32 comprises a movable first deflection mirror 42 and a movable second deflection mirror 44. The first deflection mirror 42 is pivotable about a first pivot axis (indicated by the upper arrow) so that the working laser beam 22 can be moved along an x-axis in the focus position. The second deflection mirror 44 is pivotable about a second pivot axis (indicated by the lower arrow) so that the working laser beam 22 can be moved along a y-axis perpendicular to the x-axis in the focus position. Thus, in the focus area 40, the working laser beam 22 and the pilot laser beam 26 can be moved in a focal plane 40. Preferably, the pivot axes are perpendicular to each other. The pivot axis of the first deflection mirror 42 and the pivot axis of the second deflection mirror 44 can also be reversed.

[0045] To prevent the working laser beam 22 from escaping, the laser processing device 10 has a monitoring device 50. The monitoring device 50 has, according to Fig. 2 a detection device 52 in the form of a camera, a projection element 54 preferably in the form of a transparent Makrolon disc, and a control device 48 for controlling the first laser beam source 20 and / or the second laser beam source 24 and / or the first deflecting mirror 42 and / or the second deflecting mirror 44.

[0046] The operating time of the laser processing device 10 is divided into a main time, as in Fig. 1 shown, and a secondary time, as in Fig. Figure 2 shows a subdividable process. During the main processing time, the workpiece 12 is processed. For this purpose, the first laser beam source 20 generates the working laser beam 22, which is directed towards the focus area 40 and the workpiece 12 by means of the laser deflection device 32. The working laser beam 22 exits the laser head 18 or the laser deflection device 32 at a lens assembly, which forms the beam output 56 of the laser head 18. The working laser beam 22 projects from the beam output 56 along the laser beam direction 38 onto the workpiece 12 and introduces energy there, which processes the workpiece 12, in particular marking it. During the auxiliary processing time, the processed workpiece 12 is removed and another workpiece 12 is loaded for the next processing cycle.

[0047] The control device 48 is configured such that, during idle time, the functionality of the laser deflection device 32, in particular the first deflection mirror 42 and / or the second deflection mirror 44, is checked or a defect is detected. For this purpose, the control device 48 controls the second laser beam source 24, the first deflection mirror 42, and the second deflection mirror 44 such that a pilot laser beam 26 shines onto a laser side 58 of the projection element 54 and penetrates the projection element 54 along the laser beam direction 38. The projection element 54 can be translucent, in particular, the projection element 54 can be transparent. Accordingly, the pilot laser beam 26 is also projected onto a camera side 60 of the projection element 54 opposite the laser side 58. The projection element 54 is arranged between the detection device 52 and the beam output 56 and / or the focus area 40.Consequently, an indirect transmitted light method is used. Alternatively, direct illumination of the detection device 52 can be used, in particular with the use of an additional filter.

[0048] Alternatively, according to Fig. 5. Another reflective element 68 present in the area of ​​the pilot laser beam 26, in particular a sheet metal wall and / or the housing 14, is directly illuminated by the pilot laser beam 26 (incident light method). The pilot laser beam 26 strikes the reflective element 68 at an angle. The detection device 52, in particular the camera, detects the reflection. The detection device 52 is preferably arranged on the same side of the reflective element 68 as the laser head 18.

[0049] The movement of the pilot laser beam 26 is controlled by the control device 48 using the computer-implemented method such that it behaves as described in Fig. 3A or Fig. 3B traces a target contour 62 on the projection element 54. After each processing cycle of the working laser beam 22, an actual contour 64 is generated by the pilot laser beam 26, which becomes visible on the projection element 54. This is primarily achieved by correcting the position and angles of the deflecting mirrors 42 and 44. Due to misalignments of the first deflecting mirror 42 and / or the second deflecting mirror 44, a deviation of the actual contour 64 from the target contour 62 can occur. In the Fig. 3A and Fig. 3C as well as in the Fig. 3B and Fig. In 3D, a pair of target contour 62 and actual contour 64 is shown. Fig. 3A corresponds to the target contour 62 of a straight line, which forms an angle of 45° with the horizontal x-axis and with the vertical y-axis. In Fig. Figure 3C shows an actual contour 64, which results from the fact that the deflecting mirror generating the movement along the y-axis has a misalignment. Therefore, the actual contour 64 only exhibits movement along the x-axis.

[0050] By comparing the actual contour 64 with the target contour 62, the control device 48 determines that the associated deflecting mirror, in this case the second deflecting mirror 44, is misaligned and requires repair or replacement. The same applies to the first deflecting mirror 42 if the laser beam 26 moves along the y-axis but not along the x-axis. The control device 48 can also perform monitoring over several monitoring cycles, detecting any changes across these cycles. If the change falls below or exceeds a threshold value, a defect can be inferred and an error message can be generated.

[0051] To improve the detectability of the actual contour 64, the projection element 54 is arranged at a distance from the focus area 40. A projection distance 66 is preferably greater than 200 mm. This widens the pilot laser beam 26, as shown in Fig. As can be seen in Figure 2, the actual contour 64 is projected more broadly onto the projection element 54, thus making it easier for the detection device 52 to detect. Therefore, preferably the projection element 54, and not the detection device 52, is arranged along the laser beam direction 38 behind the focus area 40. Reference symbol list 10 Laser processing device 12 workpieces 14 Enclosure 16 workroom 18 laser heads 20 first laser beam source 22 working laser beam 24 second laser beam source 26 pilot laser beam 28 Main axis 30 secondary axle 32 Laser deflection device 34 first deflecting mirror 36 second deflecting mirror 38 Laser beam direction 40 focus area 42 first deflecting mirror 44 second deflecting mirror 46 Enclosure 48 Control device 50 monitoring device 52 Detection device 54 Projection element 56 Beam output 58 Laser side of the projection element 60 Camera side of the projection element 62 Target contour 64 Actual contour 66 projection distance 68 reflective element QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 198 294 96 A1

[0002] DE 10 2022 116 040 A1

[0004]

Claims

Laser processing device (10) for laser processing of workpieces (12), comprising: a laser head (18) with a laser beam source (20) for generating a working laser beam (22) for processing the workpiece (12) and with a second laser beam source (24) for generating a pilot laser beam (26) for aligning the first laser beam source (20), a laser deflection device (32) with at least one movable deflection mirror (42, 44) for coaxially deflecting the working laser beam (22) and the pilot laser beam (26), so that the working laser beam (22) and the pilot laser beam (26) are directed from a beam output (56) of the laser head (18) towards a focus area (40) in which processing of the workpieces (12) takes place;- a detection device (52) for detecting the pilot laser beam (26), and - a control device (48) for controlling the second laser beam source (24) and the laser deflection device (32), which is configured such that it checks the functionality of the at least one deflection mirror (42, 44) during a secondary time of the laser processing device (10) as a function of data generated by means of the detection device (52). Laser processing device (10) according to claim 1, wherein the focus area (40) is arranged between the beam output (56) and the detection device (52). Laser processing device (10) according to claim 1 or 2, wherein the detection device (52) comprises a camera, a photodiode and / or a radiation-sensitive detector. Laser processing device (10) according to one of the preceding claims, wherein the laser deflection device (32) is arranged such that the pilot laser beam (26) is directed indirectly from the beam output (56) to the detection device (52). Laser processing device (10) according to claim 3, wherein the detection device (52) has a projection element (54) for imaging the pilot laser beam (26). Laser processing device (10) according to claim 5, wherein the projection element (54) is arranged between the beam output (56) and the camera. Laser processing device (10) according to claim 5 or 6, wherein the projection element (54) is at least partially transparent. Laser processing device (10) according to one of claims 5 to 7, wherein the laser deflection device (32) is configured such that the pilot laser beam (26) is directed towards a laser side (58) of the projection element (54) facing the beam output (56), in particular wherein the camera is configured to capture the pilot laser beam (26) on a camera side (60) of the projection element (54) opposite the laser side (58). Laser processing device (10) according to one of claims 5 to 8, wherein the control device (48) is configured such that the pilot laser beam (26) traces a two-dimensional target contour (62) on the projection element (54). Laser processing device (10) according to one of claims 5 to 9, wherein the control device (48) is configured such that it determines the functionality of the at least one deflecting mirror (42, 44) depending on a comparison between a target contour (62) and an actual contour (64), in particular a comparison between at least one quantity characterizing the actual contour (64) and at least one quantity characterizing the target contour (62). Laser processing device (10) according to one of claims 5 to 10, wherein the projection element (54) is spaced apart from the focus area (40) by a projection distance (66), in particular wherein the projection distance (66) is greater than 50 mm, in particular greater than 100 mm, preferably greater than 150 mm, preferably greater than 200 mm. A computer-implemented method for operating a laser processing device (10) according to one of the preceding claims, comprising the following steps: a) processing a workpiece (12) by means of a working laser beam (22) in a main time of the laser processing device (10); b) moving a pilot laser beam (26) along an actual contour (64) in a secondary time of the laser processing device (10); c) detecting the actual contour (64) of the pilot laser beam (26) by means of a detection device (52); and d) comparing a target contour (62), in particular a characterizing parameter of the target contour (62), and the actual contour (64), in particular a characterizing parameter of the actual contour (64), by means of a control device (48) for determining the functionality of a laser head (18) with at least one movable deflecting mirror (42, 44). Method according to claim 12, wherein the pilot laser beam (26) is directed indirectly towards the detection device (52). Method according to claim 12 or 13, wherein the pilot laser beam (26) is directed towards a laser side (58) of a projection element (54), and wherein the detection device (52) detects the actual contour (64) of the pilot laser beam (26) on a camera side (60) of the projection element (54) opposite the laser side (58). Method according to one of claims 12 to 14, wherein the projection element (54), in particular the laser side (58) and / or the camera side (60), extends along an x-axis and a y-axis perpendicular to the x-axis, wherein the desired contour (62) extends obliquely to the x-axis and / or obliquely to the y-axis, in particular at an angle of 45° to the x-axis and to the y-axis.

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