Apparatus for machining a workpiece by means of a laser beam and method for operating the apparatus

Abstract

The invention relates to a device (10) for deflecting a laser beam (12) at high frequency. The device (10) has an imaging element (32) which expands the beam, which is arranged in front of a displaceable imaging element (34) in such a way that a smaller displacement of the displaceable imaging element (34) already causes a larger displacement of the laser beam focus. A collimator (30) can be arranged in front of a scanner (22) for scanning the laser beam (12) in such a way that the scanner mirrors (24, 26) can be designed to be small and light and have a high dynamics.

Description

Technical Field

[0001] This invention relates to an apparatus for processing workpieces using a laser beam, wherein the apparatus has the following features:

[0002] a) A scanner having a first scannerspiegel for scanning a laser beam on the workpiece in a first direction;

[0003] b) A movable imaging element, which is arranged behind the scanner and is used to focus the laser beam.

[0004] The present invention also relates to a method for operating such a device. Background Technology

[0005] It is known that an apparatus is provided that is configured to process a workpiece using a rapidly moving laser beam.

[0006] A device having a scanner for deflecting a laser beam is known from US 2011 / 0127697 A1. A telescopic unit for shaping the beam is connected in front of the scanner.

[0007] US 2006 / 0245084 A1 also discloses a device having a telescopic unit for laser beam shaping and a scanner for deflecting the laser beam. A focusing lens is connected to the rear of the scanner.

[0008] A general device having a scanner is known from DE 102007028570 A1. At least one optical imaging element for focusing a laser beam is arranged behind the scanner and is movable by a motor.

[0009] A known drawback of the device is the large adjustment path of the optical imaging element used to focus the laser beam. Summary of the Invention

[0010] Invention Task

[0011] The objective of this invention is to further expand a universal device capable of rapidly focusing a laser beam onto a workpiece in a structurally simple manner. Furthermore, the objective of this invention is to provide a method for operating such a device.

[0012] According to the invention, this task is accomplished by an apparatus for processing workpieces using a laser beam, according to the invention, and a method for operating such an apparatus, according to the invention. Preferred extensions are given below.

[0013] Therefore, the objective according to the invention is achieved by the apparatus described at the outset, wherein an imaging element for beam extension is arranged between the scanner and the movable imaging element.

[0014] Therefore, the device according to the invention has a scanner for deflecting a laser beam. Here, the scanner is particularly understood as any device constructed for controlled deflection of a laser beam. The device has an imaging element that expands the laser beam deflected by the scanner. The expanded laser beam is then re-collimated by a movable imaging element. Thus, even with a small displacement of the movable imaging element, the focused position or diameter of the laser beam on the workpiece can be significantly changed.

[0015] Imaging elements that extend the laser beam are preferably configured as a concave lens system. A lens system is understood herein as a system having at least one lens. The lens system can be structurally very simple while simultaneously being capable of effectively shaping the laser beam. In particular, the imaging element that extends the laser beam can be configured as a single concave lens.

[0016] Displaceable imaging elements can be constructed in the form of a convex lens system, especially a single convex lens.

[0017] In a particularly preferred configuration of the invention, a collimator is disposed in front of the scanner. This allows the scanner to be constructed to be small, efficient, and highly dynamic. The collimator can be configured as a convex lens system, particularly a single convex lens.

[0018] More preferably, a lens for focusing the laser beam onto the workpiece is arranged behind the movable imaging element. The lens can be configured as a convex lens system, especially as a single convex lens.

[0019] A protective glass can be placed behind the lens to protect the equipment from workpiece splashes during processing.

[0020] The scanner may have only a single (first) scanner mirror. However, the scanner preferably has a second scanner mirror in order to deflect the laser beam in a different direction.

[0021] The device can be constructed in a particularly compact manner when the laser beam is redirected into the scanner through a mirror.

[0022] The scanner can be compactly constructed in the form of a scanner head.

[0023] When a laser beam is guided into a device via an optical fiber, the device can be constructed in a particularly flexible and rapid manner, for example, by means of a robotic arm.

[0024] In another preferred embodiment of the invention, the device has a beam splitter for connecting a sensor system. Here, the beam splitter may have a dichroic mirror.

[0025] Beam splitters can be positioned behind the movable imaging element. In particular, beam splitters can be positioned between the movable imaging element and the lens.

[0026] Particularly preferably, the device is configured as a laser welding apparatus. The advantages of the invention here allow for the expansion of the application range of laser welding in flexible sheet metal manufacturing:

[0027] -Bridge Gaps;

[0028] - Laser welding of thick plates cut by laser (without edge grinding);

[0029] - For laser welding of metal alloys that cannot be laser welded or can only be laser welded with great difficulty (e.g., AlMgSi);

[0030] - General-purpose, yet compact welding optics can be flexibly used on various welding methods on workpieces (thick / thin plates, gapped / seamless, thermally conductive / deep welding, etc.).

[0031] The equipment is equipped with a welding wire supply section.

[0032] Furthermore, the objective according to the invention is achieved by a method for operating the apparatus described herein, wherein the frequency of the laser beam movement on the workpiece is greater than 2400 Hz with an amplitude greater than 0.1 mm, greater than 1000 Hz with an amplitude greater than 1 mm, and / or greater than 500 Hz with an amplitude greater than 3 mm. Therefore, the dynamics of the scanning motion are particularly high when welding is performed using the apparatus described herein.

[0033] Other advantages of the invention become apparent from the specification and drawings. Similarly, the features described above and further embodied can be used individually or in any combination thereof according to the invention. The illustrated and described embodiments should not be construed as an exhaustive enumeration, but rather as exemplary features for the purpose of explaining the invention. Attached Figure Description

[0034] Figure 1 A schematic diagram of a first embodiment of the device according to the present invention is shown;

[0035] Figure 2 A schematic diagram of a second embodiment of the device according to the present invention is shown;

[0036] Figure 3A diagram illustrating the oscillating dynamics characteristics achieved using the device according to the invention. Detailed Implementation

[0037] Figure 1 A device 10 for guiding the laser beam 12 is shown. Device 10 is configured for processing, and particularly for welding, workpiece 14. In the present case, a first plate 16a and a second plate 16b are joined by a weld 18. The weld 18 here spans the gap 20 between the plates 16a and b. This can be achieved by a very rapid oscillating motion of the laser beam 12 on the workpiece 14.

[0038] The oscillating motion of the laser beam 12 is achieved by a scanner 22. The scanner 22 is configured in the form of a scanner head. The scanner 22 has a first scanner mirror 24 for oscillating the laser beam 12 in a first direction (here, the X direction), and optionally a second scanner mirror 26 for oscillating the laser beam 12 in a second direction (here, the Y direction). Here, these two directions are preferably perpendicular to each other.

[0039] The laser beam 12 is incident into the device 10 via the optical fiber cable 28. A collimator 30 is arranged between the scanner 22 and the optical fiber cable 28. The collimator 30 preferably has a convex lens system. More preferably, the collimator 30 is constructed in the form of a convex lens. The collimator 30 particularly preferably has a short focal length lens that collimates the laser beam 12 into a relatively small beam diameter, preferably less than 20 mm, and especially less than 15 mm. The scanner mirrors 24 and 26 can thus be constructed particularly small and lightweight, thereby allowing for highly dynamic movement of the scanner mirrors. Mirror 31 guides the laser beam 12 into the scanner 22.

[0040] An imaging element 32 for beam extension is connected to a scanner 22, which has a correspondingly compact construction with a small aperture. The imaging element 32 for beam extension can be configured as a concave lens system. In the present case, the imaging element 32 for beam extension is configured as a concave lens.

[0041] A movable imaging element 34 is arranged behind the imaging element 32 that expands the beam. This imaging element is, in particular, in the form of a convex lens system, specifically a convex lens. The laser beam 12 is collimated by the movable imaging element 34.

[0042] The movable imaging element 34 is preferably linearly displaced along the optical axis of the laser beam 12, driven by a motor. The displacement of the movable imaging element 34 achieves a change in the focused position of the laser beam 12 on the workpiece 14. Due to the beam spreading (i.e., divergence) of the imaging element 32, which expands the beam, a small displacement range 36 is sufficient to achieve a large focal position displacement or a large diameter change of the laser beam 12 on the workpiece 14.

[0043] The laser beam 12 may have a dichroic beam splitter 38 (shown in dashed lines here) for connecting to the sensor system 40. The sensor system may include a weld location identification device, a camera, and / or an optical coherence tomography (OCT) instrument.

[0044] Before exiting the device 10, the laser beam 12 can pass through the lens 42 and / or the protective glass 44. The lens 42 may have a convex lens system. Currently, the lens 42 is configured as a convex lens.

[0045] Figure 2 Another embodiment of the device 10 for guiding the laser beam 12 is shown. The device 10 includes an optical fiber cable 28, a collimator 30, a scanner 22 with scanner mirrors 24 and 26, an imaging element 32 for beam extension, a movable imaging element 34, and a lens 42. Mirror 31 guides the laser beam 12 into the scanner 22 to achieve another compact structural form of the device 10.

[0046] and Figure 1 Unlike device 10, the imaging element 32 that extends the beam has a concave lens system with two concave lenses, or negative lenses 48a and 48b.

[0047] exist Figure 2 The text indicates that the rotational movements 50a and 50b of the scanner mirrors 24 and 26 are less than 5°, especially less than 3°, and preferably less than 2°.

[0048] In addition, Figure 2 The study also shows that the displacement range 36 of the movable imaging element 34 results in a focusing range 52 that is more than twice, and especially more than three times, larger. This is achieved through the combined action of the beam-extending imaging element 32 and the movable imaging element 34.

[0049] Figure 3 The maximum frequency f obtained experimentally as amplitude A increases is shown. Here, it is shown as a solid line at scanner mirrors 24 and / or 26 (see...). Figure 1 and Figure 2The maximum frequency f is shown in the case of sinusoidal motor current control (Motorstrom-Ansteuerung), and is indicated by dashed lines in the case of triangular motor current control in scanner mirrors 24 and / or 26. From Figure 3 It can be seen that the maximum frequency f reached is significantly higher than the maximum frequency typically reached without the optical device according to the present invention.

[0050] Looking at all the figures, the present invention generally relates to an apparatus 10 for high-frequency deflection of a laser beam 12. The apparatus 10 has an imaging element 32 that expands the beam, arranged in front of a movable imaging element 34, such that a small displacement of the movable imaging element 34 achieves a large displacement of the laser beam focus. A collimator 30 can be arranged in front of a scanner 22 for scanning the laser beam 12, allowing the scanner mirrors 24, 26 to be small, lightweight, and highly dynamic.

[0051] List of reference numerals

[0052] 10 Equipment

[0053] 12 laser beams

[0054] 14 Workpieces

[0055] 16a, b sheet materials

[0056] 18 Welds

[0057] 20 gaps

[0058] 22 Scanners

[0059] 24 First Scanner Mirror

[0060] 26 Second Scanner Mirror

[0061] 28 Optical fiber cables

[0062] 30 Collimator

[0063] 31 mirrors

[0064] 32 Imaging elements that extend the beam

[0065] 34 Displaceable imaging elements

[0066] 36 Displacement range

[0067] 38 beam splitters

[0068] 40 Sensor Systems

[0069] 42 lenses

[0070] 44 Protective Glass

[0071] 48a, b Concave lenses

[0072] 50a, b movement

[0073] 52 Focusing Range

[0074] f Maximum frequency

[0075] Amplitude

Claims

1. An apparatus (10) for processing a workpiece (14) using a laser beam (12), wherein, The device (10) has the following: a) Scanner (22) having a first scanner mirror (24) for scanning the laser beam (12) on the workpiece (14) in a first direction. b) A movable imaging element (34) arranged behind the scanner (22) for focusing the laser beam (12); The device (10) is characterized in that it further comprises: c) An imaging element (32) for beam extension, the imaging element for beam extension being arranged behind the scanner (22) and in front of the movable imaging element (34). A collimator (30) of the device (10) is arranged in front of the scanner (22), and the collimator is in the form of a convex lens system. The lens (42) of the device (10) is arranged behind the movable imaging element (34), and the lens is used to focus the laser beam (12) onto the workpiece (14).

2. The device according to claim 1, wherein the imaging element (32) for beam extension has a concave lens system.

3. The device according to claim 2, wherein, The concave lens system is a concave lens.

4. The device according to any one of claims 1 to 3, wherein the movable imaging element (34) has a convex lens system.

5. The device according to claim 4, wherein, The convex lens system of the movable imaging element (34) is in the form of a convex lens.

6. The device according to any one of claims 1 to 3, wherein, The convex lens system is a convex lens.

7. The device according to any one of claims 1 to 3, wherein, The lens is in the form of a convex lens system.

8. The device according to claim 7, wherein, The lens system is in the form of a convex lens.

9. The device according to any one of claims 1 to 3, wherein, The scanner (22) has a second scanner mirror (26) for scanning the laser beam (12) on the workpiece (14) in a second direction.

10. The device according to claim 9, wherein, The second direction is perpendicular to the first direction.

11. The device according to any one of claims 1 to 3, wherein, The device (10) has an optical fiber cable (28) for directing a laser beam (12) into the device (10).

12. The device according to any one of claims 1 to 3, wherein, The device (10) has a beam splitter (38) for connecting a sensor system (40) that acts coaxially with the laser beam (12).

13. The device according to claim 12, wherein, The beam splitter (38) has a dichroic mirror.

14. The device according to any one of claims 1 to 3, wherein, The device (10) is configured as a laser welding device.

15. A method for operating the apparatus (10) according to any one of claims 1 to 14, wherein, The frequency (f) of the laser beam motion on the workpiece (14) is greater than 2400 Hz when the amplitude (A) is greater than 0.1 mm, greater than 1000 Hz when the amplitude (A) is greater than 1 mm, and / or greater than 500 Hz when the amplitude (A) is greater than 3 mm.

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