Galvanometer cooling for laser material processing

Abstract

The present disclosure provides a system for cooling a mirror, comprising: a rotatable mirror mounted on an axis of rotation and having at least one gas channel located behind a reflective surface, the at least one gas channel having an inlet and at least one outlet; and a static supply for gas having an outlet which is connected via the gap and thus in a non-contact manner to the inlet of the gas channel of the rotatable mirror for supplying gas. Furthermore, a method for cooling a mirror, as well as the use of the system in a laser machining head, is disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of German Patent Application No. DE 10 2023 116380.9 filed on June 22, 2023. The above application is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to a cooling system for a galvanometer mirror used in laser material processing. Background Art

[0004] Laser processing systems include many optical elements. In some laser material processing applications, so-called galvanometers are successfully used to deflect the laser beam. A galvanometer is a mirror with a highly reflective coating that is connected to a galvanometer drive via a shaft so that the mirror can be moved to deflect the laser beam.

[0005] One problem with using galvanometer mirrors is their thermal insulation. An increase in the temperature of the galvanometer mirrors can lead to a limitation in the throughput of laser material processing.

[0006] Existing galvanometers are known to be made of glass, where a small portion of the laser light is transmitted, which is not reflected by the highly reflective thin film coating. In addition, galvanometers are known to be made of materials with good thermal conductivity, such as aluminum, so that the thermal gradient is flattened and the resulting deformation is minimized. Galvanometers are also known to be made of special lightweight materials, such as beryllium or silicon carbide, to reduce their moment of inertia. The moment of inertia of all these existing galvanometers can be reduced by special mechanical supports on the back side.

[0007] The amount of heat to be dissipated by the galvanometer is relatively small. For example, the reflectivity of a highly reflective coating is typically >99.5%, so that less than 50W must be dissipated at 10kW average laser power.

[0008] The shaft of the galvo cannot be considered for effective cooling, since this would cool only a small area of ​​the mirror, or the motor shaft would be in contact with the mirror only in a small area and the heat could only be dissipated to a very small extent in this area, and probably also quite locally. Using air cooling, in principle up to 100W of power could be dissipated, although cooling the back side of the galvo with just an air flow is not sufficient.

[0009] Another problem with cooling a galvanometer mirror arises from the fact that the mirror moves, so the means for cooling the mirror must accommodate the movement of the mirror.

[0010] Therefore, the technical problem to be solved by the present disclosure is to provide an efficient cooling system for a galvanometer. Summary of the invention

[0011] The present disclosure provides a system for cooling a reflector, comprising: a rotatable reflector mounted on a rotating axis and having at least one gas channel located behind the reflecting surface, the at least one gas channel having an inlet and at least one outlet; and a static supplier for gas, having an outlet, the outlet being connected to the inlet of the gas channel of the rotatable reflector via a gap and thus non-contactly for supplying gas.

[0012] In another embodiment of the system according to the present disclosure, the static feeder is arranged axially, radially or parallel to the rotation axis of the reflector.

[0013] According to another aspect of the present disclosure, the reflector has a cylindrical protrusion around the rotation axis on the side opposite to the reflective side, the cylindrical protrusion having an inlet channel, and a corresponding cylindrical recess of the feeder is arranged around the cylindrical protrusion, the cylindrical recess having an outlet channel.

[0014] Furthermore, a feeder according to the system of the present disclosure may have a hose connector on the side of the feeder opposite the cylindrical recess.

[0015] In another embodiment of the system according to the present disclosure, the inlet of the reflector may be arranged transversely to the rotation axis.

[0016] It is further provided that the reflector is made of a lightweight material, wherein the lightweight material comprises beryllium, aluminum, and silicon carbide.

[0017] Furthermore, the reflector of the system according to the present disclosure may have a support structure on a rear side facing the reflective side, the at least one outlet being arranged in the support structure.

[0018] A system according to any one of claims 5 or 6, wherein the at least one outlet is arranged laterally to the reflector surface.

[0019] In the system according to the present disclosure, the distance between the cylindrical protrusion of the reflector and the cylindrical recess of the feeder may be less than 1 mm. An embodiment is also provided, wherein the distance is less than 0.1 mm.

[0020] In another embodiment of a system according to the present disclosure, the feeder may be arranged statically and the reflector may be rotated within a cylindrical recess of the feeder.

[0021] Another aspect of the present disclosure relates to a method of cooling a reflector, comprising the steps of:

[0022] a. Arranging a static supply for gas on the rotatable reflector, wherein at least one gas channel is arranged behind the reflective surface of the reflector and the gas channel has an inlet which is connected via a gap and thus contactlessly to an inlet of the gas channel of the rotatable reflector for supplying gas;

[0023] b. introducing a gas into at least one gas channel of the reflector via the supply; and

[0024] c. Exhausting gas via at least one outlet of at least one gas channel of the reflector.

[0025] The method according to the present disclosure may further include the step of rotating the reflective mirror during the introduction and exhaust of the gas.

[0026] Furthermore, in the method according to the present disclosure, air may be used as the gas, which may be at room temperature.

[0027] In one embodiment of the method according to the present disclosure, the gas may be exhausted laterally from the mirror.

[0028] Another aspect of the present disclosure relates to a method of using a system for cooling a galvanometer in a laser processing head, comprising the steps of:

[0029] arranging a rotatable mirror in the path of the laser beam of the laser processing head, which is attached to the rotation axis and has at least one gas channel behind the reflecting surface, the at least one gas channel having an inlet and at least one outlet; and

[0030] A static supply for gas is arranged which has an outlet which is connected via a gap and thus contactlessly to an inlet of a gas channel of the rotatable mirror for supplying gas in the laser machining head.

[0031] Other aspects, features and advantages of the present disclosure will be apparent from the following detailed description, which simply describes preferred embodiments and implementations. The present disclosure may also be implemented in other and different embodiments without departing from the teachings and scope of the present disclosure, and its various details may be modified in various obvious aspects. Therefore, the drawings and description are considered to be illustrative rather than restrictive. Additional objects and advantages of the present disclosure are described in part in the following description, and will become apparent from the description in part, or may be inferred from the embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present disclosure is described in more detail below with reference to the accompanying drawings. It is obvious to those skilled in the art that these are only possible exemplary embodiments and do not limit the present disclosure to the embodiments shown, wherein:

[0033] Figure 1 A top view of a system for cooling a galvanometer according to the present disclosure is shown.

[0034] Figure 2 A perspective view of a system for cooling a galvanometer according to the present disclosure is shown.

[0035] Figure 3 A schematic diagram of a system with a static shaft for introducing gas for cooling into a rotatable mirror is shown. DETAILED DESCRIPTION

[0036] The technical problem stated above of the present disclosure is solved by the features of the independent claims. The dependent claims cover further specific embodiments of the present disclosure.

[0037] The present disclosure relates to a cooling system for a reflector, in particular a galvanometer, to remove heat from the reflector. The proposed solution includes introducing a gas into the surface behind the reflector. The gas is introduced through the axis of rotation of the reflector, or through a feeder into an opening transverse to the axis of the reflector.

[0038] The technical advantage of the proposed solution is that a static feeder is used for a movable reflector. Thus, a static component can be used to bring gas into the interior of the movable reflector without increasing the moment of inertia of the reflector. The gas can flow out laterally to the reflecting surface of the reflector or through an outlet between the feeder and the reflector. It is conceivable that the reflector has a cylindrical surface on its rear side, which surrounds the axis of rotation. The feeder has a corresponding cylindrical protrusion, in which the cylindrical surface of the reflector is spaced apart. For efficient heat dissipation, the distance between the reflector and the feeder should be as small as possible, for example less than 1 mm, so that the gas flows into the cooling channel in the reflector and does not escape through the gap between the reflector and the feeder. Therefore, the small gap between the outlet of the feeder and the inlet of the reflector efficiently introduces the gas into the channel of the reflector. In the case of an axial inlet ( Figure 3 ), small gaps are necessary for efficient heat dissipation because otherwise the gas will not flow at the hot surfaces.

[0039] The cooling is located at the axis of rotation, so adding mirror material cylindrically around the axis of rotation to improve heat transfer has no significant effect on the moment of inertia of the mirror. To improve the transition of gas from the feeder to the mirror, the gap between the feeder and the mirror can be made narrower, so that the distance is less than 0.1 mm. As long as the distance between the feeder and the mirror is less than the diameter of the radial channel, no sealing is required.

[0040] Additional radial gas channels can be arranged inside the reflector to transport gas laterally to the outside. This may be advantageous if the thermal conductivity of the reflector material is insufficient. These channels can be located inside the reflector or inside a reinforcement structure on the back side of the highly reflective surface.

[0041] In another embodiment, the gas is fed directly into the rotating shaft to enter the feed channel of the reflector.

[0042] Figure 1 A top view of a system according to the disclosure is shown with a reflector 1 which can be moved about an axis 7. On the rear side of the reflective side 2 of the reflector 1 a cylindrical projection 6 is arranged, in which the inlet channel 5 is located. The feeder 10 has a cylindrical recess 16 which surrounds the cylindrical projection 6 of the reflector 1 with a gap in between. The outlet channel 15 is arranged in the cylindrical recess. According to the disclosure, it is provided that the channel extends in the tangential direction, i.e. Figure 1 As the mirror rotates, the channels 5 and 15 must still overlap, but the inlet channel 5 must be completely covered by the supply member 10 as the mirror rotates, which is why the axial and tangential / angular extensions of the channels 5 and 15 and the supply member 10 are provided.

[0043] An attachment 13 for a hose 20 may be arranged at the rear of the feeder. The gas is supplied via the hose 20. The gas may be air, which does not need to be cooled due to the hot reflector, as using too cold air would risk condensation on the reflector. For example, the system according to the present disclosure may be used with air at room temperature.

[0044] Figure 2 A perspective view of the components of the system is shown, wherein the feeder 10 is moved away from the back side of the reflector 1 to allow the inlet 8 of the inlet channel 5 (not visible) to be seen. On the side of the reflector 1, the outlet 9 of the exhaust channel 4 can be seen, which is located inside the reflector. On the rear side of the feeder 10, an attachment 13 for a hose 20 is arranged, with which the gas is supplied.

[0045] Figure 3 An embodiment is shown, in which the mirror 1 is connected to a galvanometer 30 via a shaft 7. The mirror 1 and the shaft are rotated by the galvanometer 30. The feeder 10 is arranged statically and the gas is supplied via the inlet channel 5. The gap 12 between the feeder 10 and the inlet channel 5 provides efficient cooling, wherein the gas again leaves the base of the mirror via the outlet 9.

[0046] Other aspects, features and advantages of the present disclosure will be apparent from the following detailed description, which simply describes preferred embodiments and implementations. The present disclosure may also be implemented in other and different embodiments without departing from the teachings and scope of the present disclosure, and its various details may be modified in various obvious aspects. Therefore, the drawings and description are considered to be illustrative rather than restrictive. Additional objects and advantages of the present disclosure are described in part in the following description, and will become apparent from the description in part, or may be inferred from the embodiments of the present disclosure.

[0047] Reference numerals list

[0048] 1 Reflector

[0049] 2 Reflective side

[0050] 3 Supply channel reflector

[0051] 4 Exhaust channels

[0052] 5 Entryway

[0053] 6 cylindrical protrusions

[0054] 7 Axis

[0055] 8 Entrance

[0056] 9 Exit

[0057] 10 Feeder

[0058] 11 Exit

[0059] 12 Gap

[0060] 13 Hose holder

[0061] 15 Exit Channel

[0062] 16 cylindrical protrusion

[0063] 20 Hose

[0064] 30 Galvanometer

Claims

1. A system for cooling a reflector, comprising: a rotatable reflector attached to the axis of rotation and having at least one gas passage behind the reflective surface, the at least one gas passage having an inlet and at least one outlet; as well as A static supply for gas has an outlet which is connected via a gap and thus contactlessly to an inlet of a gas channel of the rotatable mirror for supplying gas.

2. The system according to claim 1, wherein: The static feeder is arranged axially, radially or parallel to the axis of rotation of the reflector.

3. The system according to claim 1, wherein: The reflector has, on the side opposite to the reflecting side, a cylindrical projection around the rotation axis, the cylindrical projection having an inlet channel, and a corresponding cylindrical recess of the feeder is arranged around the cylindrical projection, the cylindrical recess having an outlet channel.

4. The system according to claim 1, wherein: The feeder includes a hose connector on a side of the feeder opposite the cylindrical recess.

5. The system according to claim 1, wherein: The inlet of the reflector is arranged transversely to the rotation axis.

6. The system according to claim 1, wherein: The reflector is made of lightweight materials, including beryllium, aluminum, and silicon carbide.

7. The system according to claim 6, wherein: The reflector has a support structure on a rear side facing the reflective side, in which the at least one outlet is arranged.

8. The system according to claim 1, wherein: The at least one outlet is arranged laterally to the reflector surface.

9. The system according to claim 1, wherein: The distance between the cylindrical protrusion of the reflector and the cylindrical recess of the feeder is less than 1 mm.

10. The system according to claim 9, wherein: The distance is less than 0.1 mm.

11. The system according to claim 1, wherein: The feeder is static and the reflector rotates within a cylindrical recess of the feeder.

12. A method for cooling a reflector, comprising the steps of: Arranging a static supply for gas on the rotatable reflector, wherein at least one gas channel is arranged behind the reflective surface of the reflector and has an inlet which is connected via a gap and thus contactlessly to an inlet of the gas channel of the rotatable reflector for supplying gas; introducing a gas into at least one gas channel of the reflector via the supply; and Gas is exhausted via at least one outlet of at least one gas channel of the reflector.

13. The method according to claim 12, wherein: The mirror rotates during the introduction and exhaust of the gas.

14. The method according to claim 12, wherein: The gas is air.

15. The method according to claim 12, wherein: The gas is at room temperature.

16. The method according to claim 12, wherein: The gas is exhausted laterally from the reflector.

17. A method of using a system for cooling a galvanometer in a laser processing head, comprising the steps of: Arranging a rotatable mirror in the path of the laser beam of the laser processing head, which is attached to the rotation axis and has at least one gas channel behind the reflective surface, the at least one gas channel having an inlet and at least one outlet; as well as A static supply for gas is arranged which has an outlet which is connected via a gap and thus contactlessly to an inlet of a gas channel of the rotatable mirror for supplying gas in the laser machining head.

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