Laser processing device for processing a workpiece and method

Abstract

The invention relates to a laser processing device (1) for processing a workpiece (7), comprising a laser beam supply device (2) which is configured to provide a laser beam for processing the workpiece (7), a cross-beam device (9) which is configured to provide a gas stream (10) which covers the laser beam supply device (2) at least partially towards the workpiece (7) and flows obliquely or perpendicularly to the laser beam, and an overpressure device (13) which is configured to generate an overpressure on a side of the laser beam supply device (2) facing the gas stream (10).

Description

[0001] The invention relates to a laser processing device for processing a workpiece and a method for processing a workpiece using a laser processing device.

[0002] From EP 1 607 167 A1, a device for a laser-hybrid welding process is known, in which components such as a laser or laser optics or an optical focusing unit and elements of a welding torch for an arc welding process and / or a feed device for a welding wire, as well as a device for forming a crossjet, are arranged on at least one mounting element. The crossjet is connected to a compressed air supply system via at least one supply line and one outlet. The supply line and the outlet of the compressed air for the crossjet are arranged between the two components, in particular the laser or the laser optics or the optical focusing unit and the elements of the welding torch or the feed device for the welding wire.

[0003] Furthermore, DE 102 26 359 A1 discloses a laser processing head for processing, in particular cutting, a workpiece using a laser beam. The laser processing head comprises a housing, a laser nozzle arranged on the housing in the region of an outlet opening, and a focusing mirror optic provided in the housing. This focusing mirror optic defines a working beam path in a passage for the laser beam within the housing, leading from an inlet opening to an open outlet opening of the housing, and focuses the laser beam through the laser nozzle into a working focus. In addition, the laser processing head includes a transverse beam device provided in the region of the outlet opening between the housing and the laser nozzle for generating a gas flow perpendicular to the laser beam. This device has a gas inlet opening and an outlet opening opposite this gas inlet opening with respect to the working beam path.

[0004] The object of the present invention is to provide a solution by which a laser beam supply device can be particularly well protected against damage resulting from contact with molten splashes when processing a workpiece using a laser beam.

[0005] This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0006] The invention relates to a laser processing device for processing a workpiece. The laser processing device comprises a laser beam delivery unit, which is configured to provide a laser beam for processing the workpiece. The laser beam delivery unit is configured to direct the laser beam onto a workpiece surface, thereby enabling the workpiece to be processed by means of the laser beam. During the processing of the workpiece by means of the laser beam, the workpiece can be melted, at least in certain areas, thereby forming a molten material.To prevent splashes of this molten metal from reaching and damaging the laser beam delivery unit, the laser processing device is designed to include a crossjet device. This crossjet device is configured to provide a gas stream that at least partially overlaps the laser beam delivery unit towards the workpiece and flows obliquely or perpendicularly to the laser beam. The gas stream flows obliquely or perpendicularly to the direction of the laser beam, deflecting molten metal splashes from the workpiece towards the laser beam delivery unit. This significantly reduces the risk of molten metal splashes adhering to the laser beam delivery unit.Because the gas flow passes the laser beam delivery unit perpendicular or at an angle to the laser beam, turbulence in the surrounding air can create a negative pressure in the area of ​​the laser beam delivery unit, which in turn can draw molten metal splashes into the laser beam delivery unit. To prevent this, the laser processing device is equipped with a positive pressure device designed to generate positive pressure on the side of the laser beam delivery unit facing the gas flow. This positive pressure effectively prevents the drawing of molten metal splashes into the laser beam delivery unit, thereby minimizing the risk of damage to the laser beam delivery unit from contact with molten metal splashes.

[0007] In a first alternative, a single compressed air source is provided, which is configured to supply both the overpressure device and the cross-jet device with compressed air. In this case, the overpressure device includes a throttle for throttling the compressed air used to set the overpressure. Compressed air at different pressures is required for setting the overpressure and for supplying the gas flow. If both the compressed air for supplying the gas flow and the compressed air for setting the overpressure are supplied by the same compressed air source, then the overpressure device includes the throttle to adjust, in particular to reduce, the pressure of the portion of the compressed air supplied by the compressed air device that is intended for setting the overpressure.

[0008] Alternatively, the laser processing device can be configured to include two separate compressed air sources: a first and a second compressed air source. The first compressed air source has a first compressed air level, and the second compressed air source has a second compressed air level that is lower than the first. The first compressed air source is configured to supply the cross-jet device for generating the gas flow. The second compressed air source is configured to supply the overpressure device for setting the overpressure. By providing the compressed air for the cross-jet device and the overpressure device using separate compressed air sources, the pressures required for each function can be set independently and with particular ease.If the compressed air for generating the gas flow and the compressed air for adjusting the vacuum are supplied from the same compressed air source, then the laser processing device can be manufactured with very few components and in a particularly compact form.

[0009] In a possible further development of the invention, the cross-beam device is configured to provide the gas flow that is directed past a protective glass of an optical system of the laser beam delivery device, thereby covering the protective glass at least partially towards the workpiece. The overpressure device is configured to adjust the overpressure in the area of ​​the protective glass. This effectively protects the protective glass from molten splashes. As a result, the risk of contamination of the optical system, and especially the protective glass, can be kept to a minimum.

[0010] In another possible embodiment of the invention, the protective glass is held by a holder, with the protective glass and the holder together forming a pot whose opening faces the workpiece. The protective glass forms the bottom of the pot, while the holder forms the respective side walls. The overpressure device is designed to regulate the overpressure within the pot. This prevents air from being drawn out of the pot due to turbulence in the ambient air caused by the gas flow, thus preventing a vacuum from forming within the pot. By adjusting the overpressure, this air intake caused by ambient air turbulence can be compensated for.This is particularly effective in preventing molten metal splashes from being sucked into the pot due to a vacuum inside the pot, adhering to the protective glass and thus contaminating it.

[0011] In this context, it may be particularly suitable for the holder to have at least one pressure relief opening leading into the pot, through which compressed air can be introduced for adjusting the overpressure. This at least one pressure relief opening allows compressed air to be introduced directly into the pot particularly easily and precisely, thus enabling particularly easy and precise adjustment of the overpressure within the pot.

[0012] In a further possible embodiment of the invention, the overpressure device is configured to provide at least one airflow for adjusting the overpressure, which flows at least partially away from the laser beam processing device. This airflow can be generated by passing compressed air through the at least one overpressure opening of the holder into the pot. The at least partial flow of the airflow away from the laser supply device means that the airflow flows at least partially in the direction of the laser beam towards the workpiece. In this context, the at least one airflow can also flow partially in at least one other direction. For example, the at least one airflow can flow from the holder towards the center of the pot, flowing not obliquely towards the protective glass but obliquely away from it.This allows any molten metal splashes entering the pot via at least one air jet to be deflected or carried away by the airflow, thus preventing them from adhering to the protective glass. This significantly reduces the risk of molten metal splashes sticking to the protective glass.

[0013] In a further possible embodiment of the invention, the laser processing device is configured to weld the workpiece. Welding is the joining or fusion of workpieces using heat and / or pressure, so that the workpieces form a single unit. Welding creates a material bond between the workpieces. It is a joining process for permanently joining two or more workpieces. Using the laser processing device, the workpiece can thus be joined to at least one other workpiece particularly securely and permanently by welding, while minimizing the risk of damage to or contamination of the laser beam delivery device.

[0014] The invention further relates to a method for processing a workpiece using a laser processing device, as already described in connection with the laser processing device according to the invention. In this method, a laser beam is provided for processing the workpiece by means of the laser beam supply device, and in particular, directed onto the workpiece. Furthermore, the method provides a gas stream that at least partially overlaps the laser beam supply device towards the workpiece and flows obliquely or perpendicularly to the laser beam by means of the cross-beam device. Finally, the method provides that an overpressure is set on a side of the laser beam supply device facing the gas stream by means of the overpressure device.In this arrangement, either the overpressure is provided by a compressed air source configured to supply the overpressure device and the cross-jet device with compressed air, wherein the overpressure device includes a throttle for throttling the compressed air intended for setting the overpressure, or a first compressed air source with a first compressed air level and a second compressed air source with a second compressed air level lower than the first compressed air level are provided, wherein the first compressed air source supplies the cross-jet device with compressed air and the second compressed air source supplies the overpressure device with compressed air. The first and second compressed air sources are designed separately from each other, independently of each other, and thus can be operated separately.In particular, it is provided that the gas flow supplied by the transverse beam device completely covers the protective glass of the laser processing device, especially the opening of the pot, towards the workpiece in a plane perpendicular to a beam direction of the laser beam.

[0015] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0016] The drawing shows in: Fig. 1 A schematic side view of components of a laser processing device for processing a workpiece.

[0017] In Fig. Figure 1 shows a partial schematic sectional view of a laser processing device 1 for processing a workpiece 7. The laser processing device 1 is configured to weld the workpiece 7, in particular to weld it to another workpiece 7. The laser processing device 1 comprises a laser beam delivery unit 2, of which only a protective glass 3 of an optical system of the laser beam delivery unit 2 and a holder 4 for the protective glass 3 are shown. The protective glass 3 is held by the holder 4. The protective glass 3 and the holder 4 together form a pot 5, the opening 6 of which faces the workpiece 7. The bottom of the pot 5 is formed by the protective glass 3.

[0018] The laser beam delivery device 2 is configured to provide a laser beam and direct it towards the workpiece 7. During the processing of the workpiece 7, particularly during welding, molten metal spatter 8 can be generated and propelled towards the laser beam delivery device 2. The laser beam is designed to pass through the protective glass 3, the cup 5, and the opening 6 before being directed towards the workpiece 7. If a molten metal spatter 8 enters the cup 5, it can adhere to the protective glass 3 and contaminate it. This can negatively affect a property of the laser beam provided by the laser beam delivery device 2.To prevent the molten splash 8 from entering the pot 5 and thus from reaching the protective glass 3, the laser processing device 1 comprises a cross-beam device 9. The cross-beam device 9 is configured to provide a gas stream 10 that at least partially overlaps the laser beam supply device 2 towards the workpiece 7 and flows obliquely or perpendicularly to the direction of the laser beam. Fig. Figure 1 clearly shows how the molten splash 8 flying towards the protective glass 3 is deflected by the gas flow 10. As in Fig. 1 can be recognized particularly well, the gas flow 10 provided by the cross-jet device 9 is directed past the protective glass 3 or the opening 6 of the pot 5 and thereby covers the protective glass 3 or the opening 6 of the pot 5 at least partially towards the workpiece 7.

[0019] The gas flow 10 can cause turbulence 11 in the ambient air, which, if it flows past the opening 6 of the pot 5, can draw air 12 out of the pot 5. To prevent a negative pressure from forming in the pot 5 as a result of the air 12 drawn out of the pot 5, and thus prevent molten splashes 8 from being drawn into the pot 5, the laser processing device 1 includes a Fig. 1. Overpressure device 13, shown only schematically with a box. The overpressure device 13 is designed to generate overpressure on the side of the laser beam delivery device 2 facing the gas flow 10, in particular on the protective glass 3, in this case within the pot 5. This reliably prevents molten splashes 8 from being drawn into the pot 5. The overpressure device 13 is thus designed to adjust the overpressure in the area of ​​the protective glass 3, in particular in the pot 5.

[0020] The present design provides that the holder 4 has at least one, and in this case several, overpressure openings 14 through which compressed air can be introduced into the pot 5 for adjusting the overpressure. The overpressure openings 14 are designed such that, as a result of introducing the compressed air into the pot 5, respective air streams 15 result, which flow at least partially away from the laser beam delivery device 2, in particular from the protective glass 3. The air streams 15 are thus directed obliquely away from the protective glass 3 in the direction of the workpiece 7. The overpressure device 13 is thus configured to provide the at least one air stream 15 for adjusting the overpressure.

[0021] The laser processing device 1 is designed to have a first compressed air source with a first compressed air level and a second compressed air source, distinct from the first and with a second compressed air level lower than the first. The first compressed air source is configured to supply the cross-jet device 9 with compressed air, which in turn generates the gas stream 10 using the compressed air received from the first compressed air source. The second compressed air source is configured to supply the overpressure device 13 with compressed air, which in turn generates at least one air stream 15 using the compressed air received from the second compressed air source.

[0022] Alternatively, it is possible that only one compressed air source is provided in the laser processing device 1, which supplies compressed air for both the cross-jet device 9 and the overpressure device 13. In order to be able to adjust the pressure level of the compressed air required for generating the air streams 15, the overpressure device 13 in this embodiment includes at least one throttle.

[0023] The overpressure in the area of ​​the optical system of the laser beam supply device 2, in particular in the area of ​​the protective glass 3, prevents a suction effect of particles and melt splashes 8, which would cause contamination of the protective glass 3.

[0024] During laser welding processes, molten metal spatter 8 inevitably forms due to the instability of vapor capillaries, also known as keyholes. This molten metal spatter 8 can reach the protective glass 3 of the optical system. This affects the welding process and, in the worst case, damages the optical system. The gas stream 10, which is a so-called crossjet, is used to deflect the molten metal spatter 8 away from the optical system. Due to the high volume flow of the gas stream 10, a negative pressure can develop below the protective glass 3 in the pot 5 without the air streams 15. This negative pressure can attract molten metal spatter 8. To prevent this negative pressure, at least one air stream 15 is generated between the gas stream 10 and the protective glass 3. This positive pressure compensates for the negative pressure and thus reduces contamination of the optical system, especially the protective glass 3.

[0025] Overall, the invention demonstrates how optimized splash protection for welding optics can be implemented. Reference symbol list 1 laser processing device 2 Laser beam delivery device 3 protective glass 4 brackets 5 pots 6 Opening 7 workpiece 8 molten splashes 9 Crossbeam device 10 Gas flow 11. Vortexing 12 Air 13 Overpressure device 14 Overpressure opening 15 Airflow 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] EP 1 607 167 A1

[0002] DE 102 26 359 A1

[0003]

Claims

[1] Laser processing device (1) for processing a workpiece (7), comprising a laser beam supply device (2) which is configured to supply a laser beam for processing the workpiece (7), a cross-beam device (9) which is configured to supply a gas stream (10) which at least partially covers the laser beam supply device (2) towards the workpiece (7) and flows obliquely or perpendicularly to the laser beam, and an overpressure device (13) which is configured to generate an overpressure on a side of the laser beam supply device (2) facing the gas stream (10), wherein - a compressed air source is provided which is designed to supply the overpressure device (13) and the cross-jet device (9) with compressed air, wherein the overpressure device (13) comprises a throttle for throttling the compressed air provided for setting the overpressure, or - a first compressed air source with a first compressed air level and a second compressed air source with a second compressed air level lower than the first compressed air level are provided, wherein the first compressed air source is configured to supply the cross jet device (9) with compressed air and the second compressed air source is configured to supply the overpressure device (13) with compressed air. [2] Laser processing device (1) according to claim 1, characterized by, that the cross-beam device (9) is configured to provide the gas flow (10) which is directed past a protective glass (3) of an optical system of the laser beam provision device (2) and thereby covers the protective glass (3) at least partially towards the workpiece (7), and the overpressure device (13) is configured to adjust the overpressure in the area of ​​the protective glass (3). [3] Laser processing device (1) according to claim 2, characterized by , wherein the protective glass (3) is held by means of a holder (4) which together form a pot (5) with its opening (6) facing the workpiece (7), wherein a bottom of the pot (5) is formed by the protective glass (3), and wherein the overpressure device (13) is configured to adjust the overpressure in the pot (5). [4] Laser processing device (1) according to claim 3, characterized by, that the holder (4) has at least one overpressure opening (14) opening into the pot (5), through which compressed air can be introduced into the pot (5) for adjusting the overpressure. [5] Laser processing device (1) according to one of the preceding claims, characterized by , that the overpressure device (13) is configured to provide at least one airflow for setting the overpressure, which flows at least partially away from the laser beam processing device (2). [6] Laser processing device (1) according to one of the preceding claims, characterized by , that the laser processing device (1) is set up to weld the workpiece (7). [7] Method for processing a workpiece (7) using a laser processing device (1) according to one of the preceding claims, in which a laser beam is provided for processing the workpiece (7) by means of the laser beam supply device (2), a gas stream (10) is provided by means of the cross-beam device (9) which at least partially covers the laser beam supply device (2) towards the workpiece (7) and flows obliquely or perpendicularly to the laser beam, and an overpressure is set on a side of the laser beam supply device (2) facing the gas stream (10) by means of the overpressure device (13), wherein - the overpressure is provided by means of a compressed air source which is designed to supply the overpressure device (13) and the cross-jet device (9) with compressed air, wherein the overpressure device (13) comprises a throttle for throttling the compressed air provided for setting the overpressure, or - a first compressed air source with a first compressed air level and a second compressed air source with a second compressed air level lower than the first compressed air level are provided, wherein the first compressed air source supplies the cross jet device (9) with compressed air and the second compressed air source supplies the overpressure device (13) with compressed air.

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