Laser drilling process and laser drilling system

Abstract

Method for laser drilling with a laser drilling system 1, wherein boreholes 4 are drilled at drilling locations 3 in an area of ​​a workpiece 2 as a drilling location area, wherein the laser drilling system 1 generates a laser beam 6, wherein the laser drilling system 1 has a beam shaping system 7 for generating and / or deflecting at least one laser beam profile of the laser beam 6, wherein the beam shaping system 7 combines a plurality of coherent individual laser beams to form the laser beam 6, wherein at least one of the laser beam profiles is designed as a drilling laser beam profile 9, wherein the drilling laser beam profile 9 has a plurality of spatially separated drilling spots 11 for drilling the boreholes 4 in the drilling location area.

Description

[0001] The invention relates to a method for laser drilling, a laser drilling system for carrying out the method and a workpiece produced using the method for laser drilling. State of the art

[0002] Laser drilling machines are well known. Laser drilling machines can create holes in workpieces. The material of the workpieces is vaporized with the laser beam.

[0003] The document DE 10 2022 200 631 A1 discloses a method for producing laser-drilled microchannels in a component. The disclosed method for producing a gas diffusion layer for an electrochemical cell unit for converting electrochemical energy into electrical energy as a fuel cell unit and / or for converting electrical energy into electrochemical energy as an electrolysis cell unit consists of the following steps: providing a layered gas diffusion layer, wherein a laser beam is directed onto an outer surface of the gas diffusion layer several times at different impact positions on the outer surface of the gas diffusion layer, so that laser-drilled microchannels are machined into the gas diffusion layer by the laser beam. Disclosure of the invention

[0004] The subject matter of the invention is a method for laser drilling with the features of claim 1, a laser drilling system for carrying out the method with the features of claim 12 and a workpiece produced with the method for laser drilling with the features of claim 13. Preferred or advantageous embodiments of the invention emerge from the subclaims, the following description and the attached figures

[0005] The invention relates to a method for laser drilling using a laser drilling system. Laser drilling involves drilling holes at drilling locations in a specific area of ​​a workpiece, known as the drilling location area. The drilling locations are the positions on the workpiece where a drill hole is to be created. The drilling locations are planned drill holes. The drilling locations can be distributed across the entire workpiece. The drilling location area is a section of the workpiece with drilling locations. The drilling location area has a size that corresponds to the portion of the laser beam's cross-section to be drilled.

[0006] The laser drilling system is designed to generate a laser beam for drilling the workpiece. In other words, the laser drilling system has at least one laser source.

[0007] The laser drilling system has a beam-shaping system for generating and / or deflecting at least one laser beam profile of the laser beam. The laser source and the beam-shaping system generate the laser beam for drilling. The beam-shaping system combines several coherent individual laser beams into the laser beam. The combination of the individual laser beams into the single laser beam is called coherent beam combining (CBC). The CBC can be used to adjust the laser beam profile and / or the deflection of the laser beam. The adjustments are made without mechanical movement of components and are very fast. In the laser drilling process, the beam-shaping system combines several coherent individual laser beams into the laser beam to generate and / or deflect at least one laser beam profile of the laser beam.

[0008] The settings can be adjusted, particularly in the MHz range, and are described as highly dynamic. The MHz range is between 1 and 10 MHz. The very fast deflection makes it possible to reduce dead times when moving the laser beam along the workpiece. The multiple coherent individual laser beams can be generated by one or more laser sources. With the CBC, no diffractive optics are used for beam shaping, thus reducing laser power losses.

[0009] The laser beam for drilling is generated by the beam-shaping system, particularly as a continuous wave laser or cw laser beam. The beam-shaping system is used to set different laser beam profiles. The laser beam has a laser beam profile. The laser beam profile can be changed quickly. The rapid change in the laser beam profile causes a change in the intensity distribution for each laser beam profile. A change in the laser beam profile can act like a pulse for the workpiece. The setting of a new laser beam profile and the subsequent duration of the laser beam profile's effect on the workpiece is referred to below as the irradiation pulse. The duration of the irradiation pulse can vary. The laser beam can have different laser beam profiles in a repeating sequence. This repeating sequence is referred to as a sequence.

[0010] At least one of the laser beam profiles is designed as a drilling laser beam profile. The drilling laser beam profile has a power density that allows material from the workpiece to be vaporized. After all the material from the workpiece at the drilling location has been vaporized, a drilled hole remains in the workpiece.

[0011] The drilling laser beam profile has several spatially separated drilling spots for drilling the boreholes in the drilling site area.

[0012] The cross-section of the laser beam from the borehole laser beam profile exhibits a local intensity distribution of the laser beam intensities. The borehole laser beam profile exhibits one or more points with an increased intensity compared to the average of the intensities over the cross-sectional area of ​​the laser beam. The points with the increased intensities are called drill spots. The drill spots of the drill laser beam profile have such a high intensity that the energy introduced by a drill spot leads to vaporization of the workpiece material. The generated drill spots each have their own parameters, such as their own beam direction or alignment to a location, their own focus position, their own geometry, their own intensity, etc. The parameters of the drill spots can vary from drill spot to drill spot. The parameters of the drill spots are adjusted for each drill laser beam profile.For example, the focus position of the drilling spots is adjusted from one laser beam profile to another. With the laser drilling system, multiple drill holes can be created in the workpiece using the laser beam with the respective laser beam profile. At a reduced intensity, only a small amount of energy is introduced into the workpiece material, preventing the workpiece material from evaporating and creating a drill hole.

[0013] The advantage is that a highly dynamic laser beam guidance and / or laser beam shaping is implemented so that, depending on the processing strategy, for example, dead times can be reduced or heat input can be improved.

[0014] Dead times can be reduced through highly dynamic positioning of the drill spots. These drill spots can be used to create holes in the workpiece. Additionally, heat is introduced into the workpiece via the drill spots, causing the material to expand slightly. This expansion changes the positions of the drill holes. The change in the positions of the drill holes due to thermal expansion is referred to below as thermal distortion.

[0015] The workpiece can have a wide variety of configurations. In one possible example, the workpiece is a sheet metal to be drilled for a fuel cell. Specifically, more than 100,000 holes with a diameter of 1 to 40 µm per hole are drilled into the sheet metal for a fuel cell with a thickness of 100 to 1000 µm, at a drilling rate of several thousand holes per second. Alternatively, sheets for filter screens are produced, which also have a large number of holes in their final state. The laser drilling systems preferably have an output of several kW, e.g., between 1 and 100 kW, preferably between 6 and 30 kW.

[0016] In one embodiment, an optical phased array is used as an optical phased array for the beam shaping system to generate and / or deflect the different laser beam profiles.

[0017] In an optical phased array (OPA), individual laser beams from one or more laser sources are combined into a single laser beam. The multiple individual laser beams, e.g. more than 31 individual laser beams, are superimposed during the combination. Interference occurs during superposition. Interference can be used to increase or decrease local intensities in the intensity distribution of the cross-section of the laser beam. Interference can be used to create drill spots. Furthermore, interference can be used to adjust the number and local distribution of the drill spots in the drill laser beam profile. In addition, interference can be used to deflect the drill spots to specific positions on the workpiece. The generation of the drill spots and the local distribution of the drill spots in the drill laser beam profile, as well as the deflection of the laser beam profile, take place in the beam shaping system.

[0018] With the OPA, the laser beam can be deflected without moving elements. Setting a position on the workpiece by deflection occurs in the range of 100 to 1000 nanoseconds. Changing the deflection to another position is in the MHz range, e.g. 1 to 10 MHz. In other words, with a location-change frequency in the MHz range, e.g. 1 to 10 MHz, the laser beam can be guided to another location on the workpiece via deflection. The distance between the locations is limited by the maximum deflection. The distance between the locations can also be limited by the maximum permissible angle of the drill holes to the surface. The deflection occurs quickly. Deflection with the beam shaping system can reduce dead times when changing drilling locations. The deflection only occurs when the irradiation pulse is present, in which the individual laser beams are superimposed.

[0019] In a further embodiment, a first drilling laser beam profile is generated with a first spatial distribution of the drilling spots. In addition, a second drilling laser beam profile is generated with a second spatial distribution of the drilling spots. The spatial distribution of the drilling spots of the first drilling laser beam profile differs from the spatial distribution of the drilling spots of the second drilling laser beam profile. The first drilling laser beam profile and the second drilling laser beam profile are aligned one after the other to a common drilling location area on the workpiece during drilling.

[0020] Each drilling laser beam profile has a spatial distribution of at least one, preferably several, drilling spots. The spatial distributions can vary from drilling laser beam profile to drilling laser beam profile. The different drilling laser beam profiles can differ in the number of drilling spots, the spatial distribution of the drilling spots, the intensity of the drilling spots, the focus position of each individual drilling spot within the drilling laser beam profile, the positioning of the drilling spot on a specific location on the workpiece, etc.

[0021] The number of drilling laser beam profiles with a spatial distribution of at least one drilling spot is not limited to two. Multiple, for example, more than 30 different drilling laser beam profiles can be defined, each with a different spatial distribution of at least one drilling spot. Using multiple drilling laser beam profiles improves workpiece processing. By applying the different drilling laser beam profiles for different times at different locations, workpiece shapes, such as edges, and heating and cooling effects, can be taken into account.

[0022] The multiple, e.g., 9, drilling spots can be arranged irregularly or regularly in the laser beam profile. With an irregular arrangement, the distance between adjacent drilling spots is not equal. With a regular arrangement, the distance between adjacent drilling spots is equal.

[0023] The regular arrangement can be referred to as a grid. Preferably, several spaced, identical polygons are arranged in a grid. The grid forms a geometric arrangement of drill spots at the corners of the polygons. The polygons include triangles, squares, rectangles, parallelograms, pentagons, hexagons, polygons, etc. The polygon also includes chord polygons, whose corners are arranged on a circular path.

[0024] A matrix is ​​a grid arrangement in which the polygon of the grid is a rectangle or a square. The matrix is ​​implemented in a matrix-like arrangement. In a matrix-like arrangement, the corners of the polygon of the grid are called matrix locations. In particular, in the matrix-like arrangement of the drilling spots, the distance between neighboring matrix locations is equal. Diagonal matrix locations to neighboring matrix locations are not considered.

[0025] Preferably, the first drilling laser beam profile and the second drilling laser beam profile are aligned sequentially on the workpiece during drilling to a common drilling location. The sequential arrangement of multiple drilling laser beam profiles is referred to below as a sequence. Individual drilling beam profiles can be repeated within a sequence. Multiple sequences may be necessary to drill the holes.

[0026] The direction towards the common drilling location area means that the cross-section of the first drilling laser beam profile and the cross-section of the second drilling laser beam profile are directed towards the same drilling locations. The drilling spots of the first drilling laser beam profile can be directed towards different drilling locations than the drilling spots of the second drilling laser beam profile. When multiple drilling laser beam profiles are directed towards a common drilling location area, at least one drilling spot is directed towards each drilling location in each sequence of the multiple drilling laser beam profiles. If one of the drilling spots is directed towards a drilling location, this simultaneously means that the drilling spot acts on the drilling location and vaporizes material. In the sequence of the multiple drilling beam profiles, multiple drilling spots can also be directed towards one or more of the drilling locations. The progress of drilling through the drilling locations can vary after each sequence of the multiple drilling laser beam profiles.Drilling locations targeted by multiple drill spots in the sequence received greater progress in the sequence than drilling locations targeted by only one drill spot. Drilling locations without a drill spot in the drilling laser beam profile cooled down.

[0027] The different drilling beam profiles can minimize the effects of heat input per drilling location. This allows heating phases of drilling locations caused by the drilling spot to be alternated with cooling phases (without the drilling spot) using different drilling beam profiles. Accordingly, thermal distortion of the drilling location during drilling can be reduced. The drill holes can be drilled with greater precision.

[0028] In a further embodiment, the drilling laser beam profiles aligned to the common drilling location area on the workpiece create the drill holes in the drilling location area. In addition, the spatial distribution of the drilling spots of the drilling laser beam profiles each represents a subset of the drilling locations. The subsets of all different drilling laser beam profiles cover all drilling locations in the common drilling location area.

[0029] Each drilling laser beam profile exhibits a spatial distribution of one or more drilling spots. The number of drilling spots in the drilling laser beam profile may be smaller than the number of drilling locations in the drilling area covered by the cross-section of the drilling laser beam profile.

[0030] If the number of drilling spots in the drilling laser beam profile is smaller than the number of drilling locations in the drilling location range, then the number of drilling spots forms a subset. The subset of drilling spots can also be directed at only a portion of the drilling locations. The subsets of drilling spots of the multiple drilling profiles in the sequence are preferably selected so that exactly one drilling spot is directed at all drilling locations. If there is exactly one drilling spot per drilling location, the subsets are adjacent to each other.

[0031] In particular, the subsets of the drilling spots can be selected such that, in the sequence of multiple drilling laser beam profiles, multiple drilling spots are directed at individual drilling locations. When multiple drilling spots are directed at at least one drilling location per sequence of the multiple drilling laser beam profiles, the subsets of the drilling spots are arranged in an overlapping manner. The subset of drilling spots can comprise a selection of individual drilling spots as a true subset or all drilling spots as a false subset.

[0032] By selecting the drilling laser beam profiles and directing them to different, individual drilling locations in the drilling area, it is possible to alternate between heating by drilling and cooling individual drilling locations without energy input.

[0033] In particular, a 5x5 matrix of possible laser spots is used. Preferably, in the first drilling laser beam profile, all matrix positions can be occupied by a drilling spot. Additionally, in the second drilling laser beam profile, only a subset of the matrix can be occupied by drilling spots. Thus, within the 5x5 matrix, two 3x3 matrix positions connected at the center of the 5x5 matrix can be occupied by drilling spots. Preferably, the two 3x3 matrices are arranged diagonally in one direction within the 5x5 matrix.

[0034] In particular, a 3x3 matrix of possible drilling spots is used. In a 3x3 matrix, in the first drilling laser beam profile, only the matrix positions of the corner points are preferably occupied with a drilling spot each. The drilling spots in the corner points thus form a subset of the drilling spots in the drilling laser beam profile. The remaining matrix positions remain without a drilling spot. The first drilling laser beam profile has four drilling spots at the corner points of an imaginable square or rectangle of the 3x3 matrix. In addition, in the second drilling laser beam profile, the matrix positions of the corner points are not occupied with a drilling spot, but rather the remaining matrix positions of the 3x3 matrix. The second drilling laser beam profile has five drilling spots in the shape of the corner points of a cross. The drilling spots in the corner points of the cross thus form a subset of the drilling spots in the drilling laser beam profile.

[0035] Irradiation pulses can be generated by alternating the first drilling laser beam profile and the second drilling laser beam profile.

[0036] In particular, the different drilling laser beam profiles of a sequence are aligned several times in succession to the common drilling area of ​​the workpiece.

[0037] Multiple sequences, e.g., more than 1,000,000, with alternating, different drilling laser beam profiles can be directed onto the workpiece in a single sequence. The different drilling laser beam profiles can also be repeated. For example, a sequence can direct the first drilling laser beam profile, then the first drilling laser beam profile again, and then the second drilling laser beam profile onto the drilling area for each irradiation pulse. The order and number of drilling laser beam profiles are predetermined for each workpiece.

[0038] In a further embodiment of the method, one of the laser beam profiles is designed as a heat treatment laser beam profile. The heat treatment laser beam profile is used to reheat the workpiece after exposure to the borehole laser beam profile.

[0039] In particular, the heat treatment laser beam profile does not have any drill spots for drilling the holes. The heat treatment laser beam profile is preferably used after machining an area with several thousand drill holes. Post-heating reduces thermal distortion of the workpiece, allowing the drill holes to be created with greater precision.

[0040] In particular, the heat treatment laser beam profile is formed using the beam shaping system. The heat treatment laser beam profile preferably has a uniform or temperature profile-adapted intensity distribution across the cross-section of the laser beam. With a temperature profile-adapted distribution of intensities in the cross-section of the laser beam, the temperature increase preferably occurs due to the already existing temperature distribution. For example, laser spots can be directed at cold spots, e.g., 10°C, while no laser spots can be directed at warm spots, e.g., 300°C, and they are thus omitted. The intensity of the laser beam does not have enough energy to vaporize the material in the workpiece. The laser beam has enough energy to generate a temperature increase in the material of the workpiece. The laser beam can preferably generate a temperature increase in the range from 10 to more than 300°C.Preferably, the heat treatment laser beam profile is aligned with the drilling laser beam profile on the workpiece. If a warped area of ​​the workpiece is present, the heat treatment laser beam profile is preferably directed onto the workpiece to relieve the residual stresses. Slow cooling reduces thermal distortion.

[0041] In another embodiment, the laser beam profile is shifted with the deflection of the beam shaping system. This shift positions the laser beam from one location on the workpiece to another.

[0042] By superimposing several individual laser beams in a beam-shaping system, it is possible to deflect the laser beam through interference. The deflection allows the laser beam to be positioned from one location to another. Deflection can be performed quickly with the beam-shaping system. The laser beam is moved from one location on the workpiece to another location. The distance between the locations is limited by the maximum deflection.

[0043] The very fast deflection makes it possible to reduce the dead times when moving the laser beam along the workpiece. This reduces the dead times when changing location on the workpiece. Dead times are times when the laser beam must be repositioned to a new location and the laser beam must be deactivated during positioning to protect the workpiece. With the deflection provided by the beam-shaping system, a change in location can occur very quickly. This eliminates the need to deactivate the laser beam due to a change in position.

[0044] Furthermore, the heat input into the workpiece can be controlled. This allows a number of irradiation pulses, each with the drilling laser beam profile, to be used to heat input and create part of the hole at one of the accessible locations. To interrupt the heat input or to cool down, the laser is deflected to another accessible location, and heat input and part of the hole are created at the other location. The laser can then be switched back to the original location. This reduces thermal distortion and increases the dimensional accuracy of the hole.

[0045] In a further embodiment, the laser drilling system has a beam actuator, whereby the beam actuator implements a relative movement between the workpiece and the laser beam.

[0046] In particular, the laser drilling system can have an additional beam actuator for beam actuator deflection of the laser beam after beam shaping. Preferably, the beam actuator can deflect the laser beam in two planes. The beam actuator comprises one or more galvanometer drives with continuously rotating mirrors or mirror prisms, e.g., as polygon mirrors. The beam actuator has mechanically movable components that perform optical beam actuator deflection of the laser beam. The beam actuator moves the laser beam in the kHz range. In other words, at a frequency in the kHz range, e.g., 1 to 100 kHz, the laser beam can be guided to another location on the workpiece via the beam actuator deflection. The beam actuator is therefore slower than the deflection via the beam shaping system.

[0047] With the beam actuator, the laser beam can be guided over larger areas of the workpiece than with the deflection by the beam shaping system alone.

[0048] In a preferred embodiment, the positioning of the laser beam profile is achieved via the beam actuator deflection and simultaneously via the deflection of the beam shaping system. The combination of the beam actuator deflection and the deflection results in relative positioning between the workpiece and the laser beam.

[0049] In particular, the relative positioning of the laser beam to the workpiece is visible when the laser beam is moved. With the beam actuator deflection, the laser beam is moved largely continuously across the workpiece. Discontinuities may occur after reaching the end of the workpiece.

[0050] In particular, the rapid deflection of the beam-shaping system can simulate a pulsed process: Due to the rapid position change of the laser beam, the laser beam acts locally at the individual drilling locations like a laser pulse, henceforth referred to as the irradiation pulse. During the irradiation pulse and between irradiation pulses, the beam actuator continues to move. With the movement of the beam actuator during the irradiation pulse and between two irradiation pulses, a relative movement occurs between the workpiece and the laser beam. The beam actuator executes a slow movement. This slow movement occurs in the kHz range.

[0051] The deflection of the laser beam, and thus the laser profile, is visible during the irradiation pulse based on the location of the laser beam. The deflection is rapid and occurs in the MHz range. The relative positioning between the laser beam and the workpiece is visible during the deflection by the order of the laser beam positioning locations.

[0052] With the beam actuator deflection of the laser beam and the deflection of the laser beam through beam shaping, large areas of the workpieces can be processed by the laser beam.

[0053] In another embodiment, a repositioning of the laser beam profile is prepared. During drilling of the workpiece, the beam actuator changes the beam actuator deflection to reposition the laser beam profile.

[0054] The repositioning of the laser beam or laser beam profile is determined by the beam actuator deflection of the laser beam with the beam actuator and by the deflection of the laser beam with the beam shaping.

[0055] The beam actuator deflection results in a largely continuous, slow movement of the laser beam. In principle, this slow movement could be visible as an elliptical borehole in the drill holes. This results from the material removal per irradiation pulse and the continuous deflection movement by the beam actuator, which prevents coaxial overlap of the irradiation pulses. The beam actuator deflection of the beam actuator is a slow movement compared to the speed of the irradiation pulses, so the elliptical shape of the drill holes is not particularly pronounced.

[0056] By guiding the laser beam over large areas using the beam actuator, drill holes can be drilled largely vertically into the workpiece. Preferably, the drill holes are placed at an angle between 85° and 95°, preferably 87° to 93°, and particularly preferably 90° relative to the workpiece surface. The largely vertical placement of the drill holes increases the quality.

[0057] In another embodiment, the laser beam with the drilling laser beam profile remains at a drilling location until the holes are completely drilled through. The laser beam is then repositioned by the beam actuator to the area of ​​the next drilling location.

[0058] The laser beam with the drilling laser beam profile is directed at a drilling location. A number of irradiation pulses are required to completely drill through the holes in the drilling location. The number of irradiation pulses depends on several factors. One factor is the thickness of the workpiece. Another factor is the material removal per irradiation pulse. Another factor can be the heat distribution and thus the thermal distortion of the workpiece per irradiation pulse.

[0059] Thermal distortion can be reduced, for example, by cooling the drilling locations. Cooling can be achieved by arranging the subset of drilling spots in a drilling laser beam profile in such a way that no drilling spots are directed at the drilling locations that need to be cooled.

[0060] To minimize thermal distortion, partial sets of drilling spots are preferably used in a drilling laser beam profile. By using different partial sets of drilling spots per drilling laser beam profile, and thus per irradiation pulse, drilling spots are directed at different drilling locations. The partial sets of drilling spots per drilling laser beam profile can be selected such that, in a sequence of multiple drilling laser beam profiles, one drilling spot is directed at each drilling location in the drilling location area. Using partial sets of drilling spots in the drilling laser beam profile increases the number of irradiation pulses and thus also the time required to drill through the drilling locations.

[0061] The laser beam is positioned on the drilling site using the beam actuator's beam deflection. The beam actuator deflection occurs continuously. The speed of the beam actuator's beam deflection is adjusted to the time required for drilling.

[0062] In another version, the laser beam is moved relative to the workpiece using the beam actuator. Additionally, when moving over the drilling area, the drilling laser beam profile is adjusted and activated to the respective drilling area.

[0063] The drill spots are directed at the drilling locations within the drilling area. A defined number of drill spots are directed at the drilling locations. After the defined number of drill spots has been drilled, the drilling locations are only touched, but not fully drilled.

[0064] The beam actuator continuously guides the laser beam. The laser beam passes over the workpiece several times. With each pass, the drill holes are advanced further in the drilling locations. With each pass, the laser beam focus can be adjusted to the progress of the drill holes. With each pass, at least one drill spot is directed at each drilling location. With each pass, the drilling location can cool down after drilling. With each pass, a specific number of drill spots is preferably directed at all drilling locations. With each pass, the laser beam is thus activated in the drilling laser beam profile for each drilling location area. The pass or beam actuator deflection of the laser beam with the beam actuator over the workpiece preferably occurs at a high speed. The passes are stopped when the drill holes have been drilled through.

[0065] A further subject matter is a laser drilling system for carrying out the method described above, comprising a beam-shaping system for generating and / or deflecting at least one laser beam profile. Preferably, the laser drilling system is configured with the beam-shaping system to carry out the method described above.

[0066] The beam-shaping system combines several coherent individual laser beams into a single laser beam. The laser drilling system is also equipped with a control device for implementing the previously described method and controlling the previously described beam-shaping system.

[0067] Various optical systems can be used to deflect and shape the laser beam. These include optical phased arrays (OPAs), acousto-optic deflectors (AODs), and acousto-optic modulators (AOMs), which move very quickly and / or have a beam-shaping effect. Suitable optical systems could also include spatial light modulators (SLMs) or optical phase modulators (LCOS-SLMs).

[0068] The laser drilling system can reduce dead times for positioning the laser beam and dimensional inaccuracies caused by thermal distortion of the workpiece.

[0069] An additional subject matter of the invention is the workpiece produced using the method described above. The workpiece is designed as a filter screen or as a sheet metal part for a fuel cell.

[0070] The filter screen or sheet metal for a fuel cell has nearly vertically drilled holes. These holes have a round cross-section. The holes are preferably not elliptical. Particularly preferably, the holes do not have any steps caused by beam actuator deflection of the irradiation pulses.

[0071] The invention is based on the following findings, observations, and considerations and also includes the following preferred embodiments. These embodiments are sometimes referred to as "the invention" for simplicity. The embodiments may also contain parts or combinations of the above-mentioned embodiments or correspond to them and / or may also include previously unmentioned embodiments.

[0072] The idea behind the invention is to use a highly dynamically controllable, flexible cw laser with several kW laser power for high-speed laser drilling. This requires flexible beam shaping (using the beam shaping system), which allows for multi-spot processing (multiple drilling spots in one laser beam profile), as well as the ability to modulate the laser beam so quickly that the interaction time of a pulsed process can be achieved. This could be achieved and implemented, for example, using the coherent beam combining (CBC) approach.

[0073] There is improved compensation for distortion (heat distortion) through surface irradiation. The distortion of the sheet metal results from the inhomogeneous introduction of heat into the component. By using a CBC laser (or beam shaping system in the form of an OPA), a laser spot pattern (multiple drilling laser beam profiles with different distributions of the drilling spots, e.g., distribution as subsets) can be applied to the component (workpiece) in alternating patterns in a limited space for drilling the holes (drill hole), and a random distribution that does not drill but only heats the sheet metal (heat treatment laser beam profile). This heats the entire component (workpiece) evenly. Fewer local plasticization zones and thus stresses occur, and the overall distortion (heat distortion) is reduced.This allows the energy balance and the overall component heating (heat input) to be adjusted by controlling the time sequence accordingly, which can have advantages in terms of distortion (heat distortion) and drilling efficiency.

[0074] Faster power adjustment to compensate for distortion (thermal distortion) is achieved through local power adjustment. The individual laser spot arrangements (drilling laser beam profiles) can be used to apply different power distributions with each pass over an unfinished borehole (drilling site). This allows pulses of different intensities or laser power, pulse duration, focus diameter, focus position, etc. (parameters of the drilling laser beam profile) to be applied over time in a borehole, i.e., different laser parameters. This allows the energy input to be further optimized over time, relative to the individual hole, as drilling progresses.

[0075] A long Rayleigh length is achieved through special beam shaping. Drill holes are less sensitive to warped sheet metal. Laser drilling enables increased flexibility for adapting the hole geometry to product variants. Improved power scaling results in higher drilling rates, as no diffractive optical element limits the maximum usable laser power.

[0076] Increased productivity occurs due to reduced downtime.

[0077] CBC technology (OPA, CBC) enables high intensities and laser powers, with laser powers of several kW, on a small spot in large work spaces. Furthermore, the highly dynamic switching of the laser spot arrangement (drilling laser beam profile) in combination with a conventional beam guidance system with axes, scanners, etc. (beam actuators) enables the transfer of very high laser powers to the component (workpiece), thus increasing productivity. In conventional processes, the laser is always off during the jump time from hole to hole or has pulse pauses between the individual pulses. This is avoided here, and the laser operates up to 100% of the time in one drill hole or in several drill holes simultaneously. This ensures high utilization, with long "beam-on times" of up to 100%.

[0078] The areas of application or products include sheets for fuel cells or filter screens.

[0079] The concept of the invention is enabled by a new system technology that is a further development of the scanning strategies hole-by-hole (completely drilling one hole after the other - multiple irradiation pulses on one spot) and layer-by-layer (per scan across the entire workpiece, starting each drilling point with an irradiation pulse, continuing to drill the drilling points in the next scan, scanning until all drilling points are drilled through) and enables competitive hybrid scanning strategies in terms of drilling speed. Both strategies can be implemented, for example, by alternating between specific laser beam shapes, referred to in the laser software as sequences (sequences of drilling laser beam profiles).

[0080] The beam shape generated via coherent beam combining (CBC or OPA) is particularly characterized by the fact that the beam shape (drilling laser beam profile) has several spatially separated maxima (spatially distributed drilling spots within the drilling laser beam profile). Each maximum (drilling spot) within a specified beam shape (drilling laser beam profile) contributes to the drilling progress of a specific borehole (drilling location), so that typically more than one borehole is generated using one beam shape (drilling laser beam profile).

[0081] What is particularly advantageous when changing beam shapes with spatially differently arranged maxima (several different spatial distributions of the drilling spots per drilling laser beam profile) is that this change does not require any mechanical movements (deflection of the laser beam to different locations using the beam shaping system) and can be carried out using CBC in the ns range.

[0082] To machine a larger component, the positioning of the laser beam or its maxima cannot be achieved solely through CBC beam manipulation (deflection by the beam-shaping system), but must be combined with a fast axis or a fast scanner (beam actuators with beam actuator deflection). There are essentially two options for the resulting scanning strategy.

[0083] With the first option, "Multispot - Hybrid," the two beam shapes are alternated in a sequence to drill 4 or 5 holes at once (alternating between the first drilling laser beam profile with a 3x3 matrix and 4 drilling spots in the corners and the second drilling laser beam profile with a 3x3 matrix without the corners as 5 drilling spots in the shape of a cross). The scanner or axis (beam actuator) then moves to the next location on the component (workpiece), and the procedure is repeated. With this strategy, locally fixed processing (deflection by beam shaping system) can be achieved by an adapted temporal sequence of the laser spot arrangements (multiple drilling laser beam profiles), each with successive pulses, while the entire laser beam is moved (beam actuator deflection by beam actuator). From the perspective of the single borehole, it is a pulsed machining operation, since the pulses are actually generated from a cw beam by switching different spot arrangements.

[0084] This compensates for downtime caused by moving to the next hole, a disadvantage of the hole-by-hole strategy, and allows drilling rates to be significantly increased. The temporal sequence of the laser spot arrangements (sequence of multiple drilling laser beam profiles) and the movement of the entire laser beam (beam actuator deflection with the beam actuator, deflection with the beam shaping system) must be synchronized. Another advantage of this hybrid process is that the holes do not become elliptical, as with the layer-by-layer strategy, yet heat accumulation is reduced compared to the hole-by-hole strategy, thus reducing distortion (thermal distortion) and the resulting problems.

[0085] In the second option: multi-spot beam shape with layer-by-layer, the axis or scanner (beam actuator deflection with beam actuators) moves the defined beam shape (drilling laser beam profile, heat treatment laser beam profile) at a constant scan speed. The beam shape consists of several maxima (drilling spots in the drilling laser beam profile). The laser continuously modulates several different beam shapes (sequences of several drilling laser beam profiles) in alternation.

[0086] Multiple passes over the entire component (beam actuator deflection with the beam actuator) are required to ultimately drill through. Due to the overlap of scan speed and beam profile modulation, elliptical drill holes are to be expected in the current technology, which may be undesirable.

[0087] Thanks to highly dynamic beam shaping / modulation (beam actuator deflection by the beam actuator and deflection by the beam shaping system), both the spot geometry and the focus position can be adapted to the process flow as the drilling progresses (regardless of the scanning strategy). This can advantageously influence the hole geometry and increase drilling efficiency in terms of the drilling rate, i.e., the number of holes per second.

[0088] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments and the accompanying figures. These show: Fig. 1 a schematic representation of the machining of the workpiece with a laser drilling system, Fig. 2a schematic representation of the drilling laser beam profile with drilling spots at the corners of a 3x3 matrix as a rectangle, Fig. 2b schematic representation of the drilling laser beam profile with drilling spots without the corners of a 3x3 matrix as a cross, Fig. 3 schematic representation of the borehole development with alternating drilling laser beam profiles of the Fig. 2a and Fig. 2b, Fig. 4a schematic representation of the drilling laser beam profile with a 5x5 matrix, Fig. 4b schematic representation of the drilling laser beam profile with two connected 3x3 diagonal matrix sections in a 5x5 matrix, Fig. 5 several drilling locations with movement of the laser beam via the beam actuator deflection with the beam actuator and combined superposition of the deflection by the beam shaping system.

[0089] In the Fig. Figure 1 shows a highly schematic representation of the processing of workpiece 2 using a laser drilling system 1. Workpiece 2 is, for example, a sheet metal part for a fuel cell or a filter screen or sheet metal part for a filter screen. Workpiece 2 has drilled holes 3. Drilled holes 3 are planned drill holes 4. Drilled holes 3 do not yet have drill holes 4. Drill holes 4 are to be drilled into drill holes 3. Workpiece 2 also has a series of finished drill holes 4.

[0090] In addition to the workpiece 2, a laser drilling system 1 is schematically shown. The laser drilling system 1 has a laser beam source 5. The laser drilling system 1 has a beam shaping system 7 for shaping the laser beam 6. The beam shaping system 7 is connected downstream of the laser beam source 5. Before the laser beam 6 is guided onto the workpiece 2, the laser beam is focused with a lens 14. The laser drilling system 1 has a control device 8 for controlling the beam shaping system 7.

[0091] Optionally, the laser drilling system 1 additionally has a beam actuator (not shown). The beam actuator is connected downstream of the beam shaping system 7. The beam actuator enables the laser beam 6 to be guided over a larger area of ​​the workpiece 2. The beam actuator can, for example, have a galvanometer drive (galvo) with a rotating mirror or a rotating mirror prism, also referred to as a polygon mirror.

[0092] The control device 8 sets the parameters for the beam shaping system 7. The control device 8 sets the laser beam profile, for example a drilling laser beam profile 9 or a heat treatment laser beam profile.

[0093] The drilling laser beam profile 9 is configured for drilling boreholes 4. The heat treatment laser beam profile is configured for post-heating the workpiece 2. The drilling laser beam profile 9 or heat treatment laser beam profile have different intensity distribution settings. The intensity distribution represents the local distribution of the intensity of the laser radiation 6 in the cross-section of the laser beam 6. At certain local points of the cross-section, the intensity of the laser beam 6 can be increased or decreased compared to the average intensity value across the area of ​​the cross-section of the laser beam 6. At an increased intensity, a local laser spot 10 is formed. The local laser spots 10 in the drilling laser beam profile are referred to as drilling spots 11.Furthermore, the intensity and geometry of the laser spots 10 or drilling spots 11, the focus position of the laser spots 10 or drilling spots 11, and the deflection 17 of the individual laser spots 10 or drilling spots 11 are adjusted using the control device 8, the beam-shaping system 7, and the lens 14. The deflection 17 via the beam-shaping system 7 allows for rapid position changes.

[0094] The drilling laser beam profile is preferably aligned with multiple drilling locations 3. The area reachable by the drilling laser beam profile, including the drilling locations 3 located therein, is referred to as the drilling location area. Deflection 17 allows the laser beam to be moved in the direction of 13 drilling locations 3. Rapid position change reduces dead times for positioning laser beam 6. Rapid position change can be spatially limited. Optionally, a beam actuator deflection 18 of laser beam 6 can be achieved using a slower beam actuator (not shown). Beam actuator deflection 18 by the beam actuator overcomes the spatial limitation of deflection 17 with beam shaping system 7. Beam actuator deflection 18 by the beam actuator allows laser beam 6 to be guided over the entire workpiece 2.Furthermore, by means of a combination of beam actuator deflection 18 and deflection 17, boreholes 4 can be set which run almost perpendicular to the surface of the workpiece 2.

[0095] Only with the deflection 17 would the drill holes 4 be able to be placed in the workpiece 2 at an angle of inclination to the surface of the workpiece 2.

[0096] One or more laser spots 10 can introduce so much energy into the material of the workpiece 2 that the temperature in the material is increased. The one or more or all of the local laser spots 10 have a high power density compared to the average power density in the cross-section of the laser beam 6. Laser spots 10 with an intensity that can vaporize the material of the workpiece 2 are referred to as drilling spots 11. The drilling laser beam profile 9 has drilling spots 11. The drilling spots 11 remove a portion of the material of the workpiece 2 per irradiation pulse. The drilling spots 11 are preferably arranged regularly in the drilling laser beam profile 9. The drilling spots 11 can also be arranged irregularly, which is not shown. The drilling spots 11 are preferably arranged in a grid. The drilling spots 11 are particularly preferably arranged in a matrix.

[0097] In particular, the grid comprises a distributed, regular pattern. Preferably, the pattern comprises several spaced, identical polygons arranged in a surface. The pattern forms a geometric arrangement of the drill spots 11 at the corners of the polygons. The polygons include triangles, squares, rectangles, parallelograms, pentagons, hexagons, polygons, etc. The polygon additionally includes chord polygons, in which the corners are arranged on a circular path.

[0098] In the Fig. 1, the drilling spots 11 are arranged in a matrix 12 with a square pattern. The drilling spots 11 are arranged at matrix locations within the matrix. The spatial distribution of the drilling spots 11 in the drilling laser beam profile 9 can vary.

[0099] Different drilling laser beam profiles 9 can be set. The different drilling laser beam profiles 9 are set alternately. The different drilling beam profiles 9 with the drilling spots 11 can be directed one after the other in a sequence onto the drilling locations 3. When drilling spots 11 are directed onto drilling locations 3, the drilling spots 11 act on the drilling location 3 and the material of the workpiece 2 is locally vaporized. It is also possible to arrange individually selected drilling laser beam profiles 9 in a sequence. The individual drilling laser beam profiles 9 can also be repeated multiple times in one sequence. The order of the drilling laser beam profiles 9 can be used to control the heat accumulation and cooling at individual drilling locations 3, so that the dimensional accuracy of the cooled drill holes 4 in the finished workpiece can be increased.

[0100] The heat treatment laser beam profile (not shown) has a uniform or temperature profile-adapted distribution of the intensities in the cross-section of the laser beam 6. With the temperature profile-adapted distribution of the intensities in the cross-section of the laser beam, the temperature increase preferably occurs due to the already existing temperature distribution. For example, laser spots can be directed at cold spots, e.g., 10°C, while no laser spots can be directed at warm spots, e.g., 300°C, and they are thus omitted. However, the laser beam 6 does not have enough energy to vaporize the material in the workpiece 2. The laser beam 6 has enough energy to generate a temperature increase in the material of the workpiece 2. The laser beam 6 can preferably generate a temperature increase in the range from 10 to more than 300°C. The temperature increase makes it possible to reheat the material of the workpiece 2.

[0101] The heat treatment laser beam profile can be alternated with the drilling laser beam profile 9. After the finished drill holes 4 have been produced, reheating is preferably carried out with the heat treatment laser beam profile. This reheating reduces thermal distortion. When changing to a new drilling location, the drill holes 4 are created using the drilling laser beam profile 9. The laser beam 6 is preferably moved in the direction 13 shown. The drill holes 4 are preferably created row by row or column by column in the workpiece 2. The drill holes 4 can be completely created immediately with the laser beam 6 when guided over the workpiece 2. This often requires several, e.g. 10, irradiation pulses per drill hole 4. The immediate creation of a drill hole 4 is also referred to as the hole-by-hole process.

[0102] Alternatively, the laser beam 6 can be guided over the workpiece 2 and one to five irradiation pulses, each with a drilling laser beam profile 9, can be introduced per drilling location 3. Material is removed at the drilling location 3, but the drilling locations 3 are not yet through drill holes 4. During one of the subsequent passes of the laser beam 6 in the drilling laser beam profile 9 over the workpiece 2, the material removal per drilling location 3 or started drill hole 4 is extended until all of the material in the drilling location 3 or started drill hole 4 has evaporated. The introduction of the drill hole 4 during multiple passes of the laser beam 6 over the workpiece 2 is referred to as a layer-by-layer process.

[0103] The control device 8 adjusts the beam actuator deflection 18 of the laser beam 6 with the beam actuator system connected downstream of the beam shaping system 7. The control device 8 controls and coordinates the deflection 17 of the laser beam 6 by the beam shaping system 7 and the beam actuator deflection 18 of the laser beam 6 with the beam actuator system.

[0104] In Fig. Figure 2a schematically shows a first drilling laser beam profile 15 of a 3x3 matrix 12. In the first drilling laser beam profile 15, the corners of the 3x3 matrix 12 are formed as drilling spots 11. The drilling spots 11 are arranged at the corners of a square. In the first drilling laser beam profile 15, heat is introduced at the drilling spots 11.

[0105] In Fig. Figure 2b schematically shows a second drilling laser beam profile 16 of a 3x3 matrix 12. In the second drilling laser beam profile 16, the corner points of the 3x3 matrix 12 are not formed as drilling spots 11, but rather the remainder of the 3x3 matrix 12. The drilling spots 11 of the second drilling laser beam profile 16 of the 3x3 matrix 12 are arranged in the shape of a cross. In the second drilling laser beam profile 16, heat is introduced at the drilling spots 11.

[0106] Preferably, one of the possible sequences consists in the alternating order of the first drilling beam profile 15 after Fig. 2a and the second bore beam profile 16 according to Fig. 2b. The individual drilling beam profiles are directed onto workpiece 2 for 1 to 10 microseconds. This allows sequences in the 100 to 1000 kHz range to be repeatedly directed onto workpiece 2. This achieves the necessary intensity to vaporize the material at drilling location 3 or in the incipient drill hole 4.

[0107] In Fig. 3 is a schematic representation of the variation of the first drilling laser beam profile 15 of the Fig. 2a and the second drilling laser beam profile 16 of the Fig. 2b. The laser beam 6 is operated in continuous wave mode (CW mode). Different laser beam profiles of the laser beam 6 are set using the beam shaping system 7. The laser beam 6 has a laser beam profile. The laser beam profile can be changed quickly. The rapid change in the laser beam profile causes a change in the intensity distribution for each laser beam profile. A change in the laser beam profile can act like a pulse for the workpiece. The setting of a new laser beam profile and the subsequent duration of the laser beam profile's effect on the workpiece is referred to below as an irradiation pulse. The duration of the irradiation pulse can vary. The heat treatment laser beam profile or the drilling laser beam profile 9 can be set for each irradiation pulse. n. In the Fig. 3 is the alternating setting of the first drilling laser beam profile 15 (see Fig. 2a) at time t1 and second drilling laser beam profile 16 (see Fig. 2b) at time t2. The alternating adjustment of the first drilling laser beam profile 15 and the second drilling laser beam profile 16 can be referred to as a sequence. The sequences can be repeated several times. The alternating adjustment at times t3 to t n This continues until the drill holes 4 are completely drilled through. After the drilling is complete, the deflection 17 of the laser beam 6 is changed to the next drilling locations 3, e.g., as a 3x3 matrix 12. The deflection 17 with the beam shaping reduces dead times when positioning the laser beam 6. Subsequently, the next drill holes 4 can be drilled into the workpiece 2 using several sequences of alternating drilling laser beam profiles (15, 16).

[0108] In Fig. Figure 4a shows a schematic representation of another first drilling laser beam profile 15 in the form of a 5x5 matrix 12. In this first drilling laser beam profile 15, all locations of the 5x5 matrix 12 have a drilling spot 11.

[0109] In Fig. Figure 4b shows a schematic representation of a further second drilling laser beam profile 16 in the form of a 5x5 matrix 12. In this second drilling laser beam profile 16, only drilling spots 11 are activated, which are located in two diagonally connected 3x3 matrices. Fig. In 4b, the two 3x3 matrices with drill spots 11 are arranged on a first diagonal. Two unconnected 2x2 matrices, each perpendicular to the first diagonal on a second diagonal and located in the outer region of the 5x5 matrix 12, do not have drill spots 11.

[0110] In Fig.Figure 5 shows the combination of deflection 17 with beam-shaping system 7 and beam actuator deflection 18 by the beam actuator. Deflection 17 with beam-shaping system 7 is possible within a rather narrow spatial range. The narrow spatial range is defined by the maximum deflection capability of the laser beam 6 by the beam-shaping system 7 with the lens 14 for focusing. The narrowest spatial range is at a permissible inclination angle of 0°.

[0111] The deflection 17 is very fast and leads to a reduction in the dead times for positioning the laser beam 6. The deflections 17 can occur at frequencies from 1 MHz to 10 MHz. The beam actuator deflection 18 with the beam actuator can cover an area that exceeds the area that can be covered by the deflection 17 with the beam shaping system 7 by 10,000 times. The speed of the beam actuator deflection 18 and the speed of the deflection 17 are coordinated with one another. Preferably, at each position of the beam actuator deflection 18, the laser beam 6 is deflected by the beam actuator to different drilling locations 3 with the beam shaping system 7. The slower speed of the position change of the beam actuator deflection 18 compared to the deflection 17 allows several rapid position changes of the deflection 17 per position of the beam actuator deflection 18.The adjustment is carried out in such a way that all drill holes 4 can be made in the workpiece 2 in the shortest possible time and with acceptable quality.

[0112] The beam actuator connected downstream of the beam shaping system 7 can change the position of the laser beam 6 in the kHz range, e.g., in the range from 1 kHz to 100 kHz. The positions can be changed via the beam actuator at a speed, e.g., in the range of 0.1-30 m / s. In this frequency range, switching between different locations on the workpiece 2 is possible with the beam actuator deflection 18. With the beam actuator deflection 18 of the beam actuator, the laser beam 6 can be guided over a significantly larger area than with the deflection 17 by means of the beam shaping system 7. The beam actuator deflection 18 of the laser beam 6 with the beam actuator is slower than the deflection 17 with the beam shaping system 7.

[0113] The combination of the beam actuator deflection 18 and the deflection 17 enables the flat creation of drill holes 4 in a larger workpiece 2. The larger workpiece 2 has dimensions that cannot be fully machined with the deflection 17 of the beam shaping system 7. If the workpiece 2 has dimensions that can be fully machined with the deflection by the beam shaping system 7, a beam actuator is not necessary.

[0114] With the laser drilling system 1 described above, boreholes 4 can be made in a workpiece 2, e.g. a filter screen, sheet metal for a fuel cell.

[0115] The workpieces 2 can be made of metal, e.g., copper, aluminum, magnesium, etc., or metal alloys, e.g., steel, stainless steel. The workpiece 2 can also comprise mixtures of metal and metal alloys. The mixture of metal and metal alloys can be realized in the form of superimposed layers of metal or metal alloys. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2022 200 631 A1

[0003]

Claims

[1] Method for laser drilling with a laser drilling system (1), wherein boreholes (4) are drilled at drilling locations (3) in an area of ​​a workpiece (2) as a drilling location area, wherein the laser drilling system (1) generates a laser beam (6), wherein a beam forming system (7) combines several coherent individual laser beams to form the laser beam (6), wherein at least one of the laser beam profiles is designed as a drilling laser beam profile (9), wherein the drilling laser beam profile (9) has a plurality of spatially separated drilling spots (11) for drilling the boreholes (4) in the drilling site area. [2] Method according to claim 1, characterized by that the beam forming system (7) uses an optical phased array, which is formed from several individual beams, to generate and / or deflect the different laser beam profiles. [3] Method according to one of claims 1 and 2, characterized bythat a first drilling laser beam profile (15) is generated with a first local distribution of the drilling spots (11) and that a second drilling laser beam profile (16) is generated with a second local distribution of the drilling spots (11), wherein the local distribution of the drilling spots (11) of the first drilling laser beam profile (15) differs from the local distribution of the drilling spots (11) of the second drilling laser beam profile (16), wherein the first drilling laser beam profile (15) and the second drilling laser beam profile (16) are aligned one after the other on the workpiece (2) during processing to a common drilling location area. [4] Method according to one of the preceding claims, characterized bythat the drilling laser beam profiles (9, 15, 16) aligned with the common drilling location area (3) produce the drill holes (4) on the workpiece (2) in the drilling location area and the local distribution of the drilling spots (11) of the drilling laser beam profiles (9, 15, 16) each represents a subset of the drilling locations (3), wherein the subsets of all different drilling laser beam profiles (9, 15, 16) cover all drilling locations (3) in the common drilling location area. [5] Method according to one of the preceding claims, characterized by that one of the laser beam profiles is designed as a heat treatment laser beam profile, wherein the heat treatment laser beam profile is used for post-heating the workpiece (2) after exposure to the borehole laser beam profile (9, 15, 16). [6] Method according to one of the preceding claims, characterized by that the laser beam profile is shifted with the deflection (17) from the beam shaping system (7). [7] Method according to one of the preceding claims, characterized by that the laser drilling system (1) has a beam actuator, wherein the beam actuator implements a relative movement between the workpiece (2) and the laser beam (6). [8] Method according to claim 7, characterized by that the positioning of the laser beam profile is carried out via the beam actuator deflection of the beam actuator and simultaneously via the deflection of the beam shaping system (7), wherein a relative positioning between the workpiece (2) and the laser beam (6) is implemented from the combination of the beam actuator deflection and the deflection of the beam shaping system (7). [9] Method according to one of claims 7 to 8, characterized by that a repositioning of the laser beam profile is prepared, wherein during the drilling of the workpiece (2) the beam actuator deflection is changed by the beam actuator for the repositioning of the laser beam profile. [10] Method according to one of claims 7 to 9, characterized by that the laser beam (6) with the drilling laser beam profile (9, 15, 16) remains at a drilling site area until the drill holes (4) are completely drilled through and the laser beam (6) is repositioned by the beam actuator into the area of ​​the next drilling site area. [11] Method according to one of the preceding claims 7 to 10, characterized by that the laser beam (6) is moved relatively over the workpiece (2) with the beam actuator and when passing over the drilling point area the drilling laser beam profile (9) is adapted and controlled to the respective drilling point area. [12] Laser drilling system (1) for carrying out the method according to one of the preceding claims, with the beam-forming system (7) for generating and / or deflecting the at least one laser beam profile of the laser beam (6), wherein the beam-forming system (7) combines several coherent individual laser beams to form the laser beam (6) and is designed with a control device (8) for controlling the beam forming system. [13] Workpiece (2) produced by the method described above according to one of claims 1 to 11, wherein the workpiece (2) is designed as a filter screen and / or as a sheet metal for a fuel cell.

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