Machining head, laser system and method for multispot material machining

Abstract

The invention relates to a machining head (3), to a laser machining system (1) equipped with same and to a method for material processing therewith. The machining head (3) comprises an optical system (5) for simultaneously outputting a plurality of output laser beams (6, 6a, 6b) running next to one another, and further comprises a prism (9) downstream of said optical system. The prism (9) can be rotated about a rotational axis (11) which extends through two oblique side faces (20, 22) of the prism (9). The optical system (5) and the prism (9) are arranged relative to one another such that the plurality of output laser beams (6, 6a, 6b) are incident next to the rotational axis (11) on the one oblique side face (20) and exit the prism (9) next to the rotational axis (11) through the other oblique side face (22) such that when the prism (9) is rotated about the rotational axis (11) on the output side thereof an image (15a, 15b, 15c, 15d) of the output laser beams (6, 6a, 6b) rotated correspondingly about the rotational axis (11) is produced.

Description

[0001] PROCESSING HEAD, LASER SYSTEM AND METHOD FOR MULTISPOT

[0002] MATERIAL PROCESSING

[0003] The present invention relates to a processing head for a laser processing system, in particular for laser welding, and to such a laser processing system. The invention also relates to a method for processing a workpiece using such a laser processing system.

[0004] Lasers can generally be suitable for material or workpiece processing and offer advantages over other processing methods. However, they can also produce undesirable effects, such as asymmetric heat input into the material or workpiece being processed. Furthermore, increasingly stringent requirements are being placed on them, for example, for the fastest possible processing, i.e., the shortest possible process times. This may require higher laser power, which can, however, create or exacerbate disadvantages or problems of laser-based material processing.

[0005] As an approach to addressing the disadvantages of previous laser-based processing methods, which produce inhomogeneous results and can be relatively slow, complex, and costly, DE 10 2021 001 770 A1 describes a material processing device for use in laser processing. This device includes a laser beam manipulation device configured to provide a hollow-profile laser beam. Furthermore, a material feed device configured to guide a material to be processed through the hollow-profile laser beam in a feed direction along a hollow-profile axis. However, such a device is not suitable for all applications, so there is a need for further improvements in the field of laser-based material processing.

[0006] The object of the present invention is to enable particularly fast and high-quality laser-based material processing, in particular corresponding laser welding.

[0007] The problem is solved by the subject matter of the independent claims. Further possible embodiments of the invention are specified in the subclaims, the description, and the drawings. Features, advantages, and possible embodiments presented 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 any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0008] The processing head according to the invention is intended for a laser processing system, which can be configured in particular for material processing, especially for laser welding. The processing head comprises at least one optical system for guiding and / or influencing laser radiation and a prism. Both the optical system and the prism are arranged in a predetermined, intended beam path within the processing head. The optical system is arranged on the input side, and the prism of the optical system is arranged downstream of the optical system in a predetermined, intended propagation direction of the laser radiation along the beam path through the processing head.

[0009] According to the invention, the optics have at least one input or one input side for at least one input laser beam. Furthermore, the optics are configured or designed for the simultaneous output of a plurality of output laser beams running alongside one another. These multiple output laser beams can therefore, in particular, not be coaxial. For example, the multiple output laser beams can run truly parallel to one another or have beam axes arranged side by side or truly parallel to one another that extend longitudinally in the respective propagation direction of the output laser beams. In particular, the processing head or the optics or the laser processing system equipped with the processing head can be configured to generate or provide the output laser beams such that they have at least substantially the same beam properties.Such beam properties can include, for example, wavelength, intensity, power, beam shape, beam profile, beam diameter, polarization, and / or other factors. Such output laser beams with at least essentially identical or identical beam properties can ultimately achieve a particularly homogeneous and consistent processing result.

[0010] According to the invention, the machining head also has a rotation device or a

[0011] A rotation mechanism for rotating the prism, in particular continuously or continuously, around a predetermined axis of rotation. This predetermined axis of rotation runs through two inclined side surfaces of the prism. According to the invention, the optics and the prism are arranged and configured relative to one another such that the plurality of output laser beams strike one inclined side surface of the prism next to the axis of rotation in order to enter the prism there, and exit the prism next to the axis of rotation through the other inclined side surface, so that when the prism rotates around the axis of rotation and output laser beams pass through at the same time, an image or pattern of the output laser beams rotating accordingly around the axis of rotation results on the output side of the prism.In other words, by means of the processing head according to the invention, a correspondingly rotating spot or laser point pattern of the output laser beams can be generated in a processing field or on a surface irradiated with the output laser beams, for example, a material or workpiece to be processed, by rotating the prism. This rotating pattern or image of the output laser beams can be achieved in particular with a stationary or non-rotating optics relative to the processing area or the irradiated surface. In other words, no rotation of the at least one input laser beam or the multiple output laser beams is required in front of the prism or on the input side of the prism.

[0012] The rotating image or pattern of the output laser beams can be achieved by selecting the prism and the rotation axis such that the output laser beams striking the prism next to the rotation axis experience a beam offset, for example at least substantially perpendicular to the respective input-side propagation direction. For example, the output laser beams can strike the prism at least substantially true parallel to the rotation axis and leave it again at the same distance, also true parallel to the rotation axis. When the prism rotates, the output laser beams on the output side of the prism can then rotate accordingly at a constant distance around the rotation axis. A corresponding effect can also be achieved with beam axes that are oblique to the rotation axis, i.e., directions of incidence of the output laser beams onto or into the prism.

[0013] The prism can be designed and the rotation axis arranged or selected such that a laser beam propagating exactly along the rotation axis in front of the prism continues to propagate exactly along the rotation axis after passing through the prism. Since, when using the processing head according to the invention, a total available laser power is distributed across the multiple output laser beams and thus impinges on a material or workpiece to be processed at spatially spaced laser points, a higher total power can be used than, for example, when using only a single output laser beam. Likewise, the power of the individual output laser beams—with the same or greater total power—can be lower than the power of the single laser beam used in conventional approaches.As a result, for example, during laser welding using the processing head according to the invention, the tendency towards or occurrence of spattering of the welded material can be reduced. Likewise, a more uniform heat input can be achieved by the multiple rotating output laser beams. This, as well as the movement of the laser points or the output laser beams across a processing area caused by, in particular, continuous rotation of the prism, can enable a reduction in process and non-productive times. With conventional approaches, such non-productive times can arise, for example, from the acceleration and deceleration times of mirror-based scanners, for example galvo scanners or a corresponding drive unit, required to move the laser beam across the processing area. A further advantage of the present invention is that particularly symmetrical irradiation orPower is applied to a surface to be machined, which can lead to a particularly high-quality machining result.

[0014] In one possible embodiment of the present invention, the optics comprise a beam splitter for splitting an input laser beam into multiple output laser beams. For example, a single input laser beam can be used, which is then split into all ultimately output laser beams. Likewise, multiple input laser beams can be used, each split into two or more output laser beams. Such a splitting of a single laser beam into multiple output laser beams can be inherently or automatically achieved in a particularly simple and reliable manner, ensuring that the corresponding output laser beams have identical or at least nearly identical beam properties, are output in a time-synchronized manner, and hit the material or workpiece to be processed.Furthermore, the embodiment of the present invention proposed here can enable a particularly simple design of a laser processing system comprising the processing head according to the invention, for example, compared to the use of several laser radiation sources operated in parallel. This allows, for example, simplified control and beam guidance to be realized.

[0015] In a possible development of the present invention, the beam splitter is or comprises an optical wedge plate for generating a multifocus, i.e., a group or distribution of multiple focus points or focus areas. Each of these focus points or focus areas can be assigned to one of the output laser beams, i.e., a focus of precisely one of the output laser beams. The use of an optical wedge plate proposed here can enable a particularly simple, robust, reliable, and consistent generation of the multifocus or multiple output laser beams.

[0016] In a further possible embodiment of the present invention, the prism is designed as a dove prism, a double dove prism, or a roof prism. A roof prism can, for example, be an Amici prism or a more complexly shaped prism, in particular an inverted prism, with roof surfaces. Such prisms can easily enable the described rotating arrangement or distribution of the multiple output laser beams around the rotation axis provided for by the invention. The use of prism shapes known per se can also enable a particularly simple and cost-effective implementation of the processing head according to the invention.

[0017] In a further possible embodiment of the present invention, the processing head, in particular the optics of the processing head, has a collimator for parallelizing the at least one input laser beam, for example, with the rotation axis of the prism, and / or the multiple output laser beams to one another and / or to the rotation axis of the prism. The collimator can be arranged along the intended propagation direction of the laser beams in the processing head or through the processing head, in particular in front of the beam splitter of the optics mentioned elsewhere. The collimator can be or comprise, for example, a collimating lens or a multi-part collimating optics. The use of such a collimator can enable particularly simple and precise guidance and / or influencing of the parallelized laser radiation present at its output.In a further possible embodiment of the present invention, the processing head has a focusing unit arranged downstream of the prism along the intended propagation direction in the processing head or through the processing head for focusing the output laser beams into a predetermined processing area. The processing area can be extensive, so that the focused output laser beams or their focal points can also be spaced from one another, for example, evenly or symmetrically distributed around the axis of rotation. The axis of rotation can, for example, run through a center point of the processing area. This can apply at least or only to one setting or operating mode of the processing head, for example if the processing head has further adjustable devices for deflecting the output laser beams or for moving their focal points.This is described in more detail elsewhere. The focusing unit can, for example, be or comprise at least one focusing lens. Such a focusing unit, which can, for example, be arranged on the output side of the machining head or form its output toward the machining area, can enable particularly precise material processing.

[0018] In a further possible embodiment of the present invention, the processing head comprises at least one scanner or at least one scanner optics for scanningly deflecting the at least one input laser beam and / or the multiple output laser beams across a predetermined processing field. Such scanning deflection can mean that the output laser beams or their focal points, i.e., the aforementioned laser points or laser spots, can ultimately traverse or sweep across the entire processing field during operation, i.e., during a processing operation, or can be freely moved or positioned within the processing field. The processing field can therefore be a surface or spatial region within which intended material processing is possible using the multiple output laser beams. The processing field can, in particular, be much larger than the processing area mentioned elsewhere.The processing area can only comprise that surface or spatial region in which the multiple output laser beams or their focal points move in a rotating manner, i.e. along a corresponding circular or oval path, solely due to the rotation of the prism, i.e. without any further simultaneous or superimposed adjustment processes. The scanner can, for example, be combined or integrated with the beam splitter mentioned elsewhere or an optical element for multi-focus generation. For example, a so-called programmable focusing optics (PFO) can be used for this purpose. With the help of two mirrors on the scanner or the PFO, a laser beam or the bundle of output laser beams can be positioned at any specified position within the processing field and guided along any seam or line geometries or contours within the processing field.This allows material processing to be performed within the processing field without the material or a corresponding workpiece or the processing head as a whole having to move, i.e., without relative movement between the material or workpiece on the one hand and the processing head or the laser processing system on the other. In particular, a PFO can be used with an image scale between 1:1 and 5:1, particularly in the range of 1.7:1 to 2:1. This has proven to be particularly practical, for example, for laser welding of hairpin windings or hairpin contacts in electrical machines.

[0019] The present invention also relates to a laser processing system that can be configured, in particular, for laser welding. The laser processing system according to the invention has at least one laser radiation source for generating a laser beam and a processing head according to the invention arranged downstream of the laser radiation source in the intended propagation direction of the laser beam. The laser beam generated and output by the laser radiation source can therefore, in particular, form the input laser beam mentioned in connection with the processing head according to the invention. The laser processing system according to the invention can accordingly, in particular, be the laser processing system mentioned in connection with the processing head according to the invention or correspond thereto. The at least one laser radiation source or the laser processing system can, in particular, have a total laser power of at least 4 kW, at least 8 kW, or at least 24 kW.This can, for example, enable effective and efficient laser welding. Depending on the application or requirements, the laser radiation source can be configured, for example, to generate the laser beam with a wavelength in the near infrared (NIR) range or in the green or blue visible spectral range. Furthermore, the laser processing system can be configured to generate the at least one laser beam and / or the output laser beams with a beam quality or a beam parameter product of no more than 4 mm mrad.

[0020] In a possible embodiment of the present invention, the

[0021] Laser processing system at least one 2-in-1 fiber for guiding laser radiation or the at least one laser beam in front of the prism or in front of or up to the optics of the processing head. Such a 2-in-1 fiber can have an inner core and a surrounding cladding or toroidal core, which can be made of the same material, for example, and in each of which laser radiation can be guided. In addition, the fiber can have a so-called cladding arranged between the inner core and the toroidal core and / or surrounding the toroidal core on the outside, i.e. a sheath made of a different material, for example. The laser processing system is designed here to simultaneously expose the inner core and the surrounding toroidal core of the fiber to laser radiation. In this case, a proportion of no more than 10% of the total laser power guided in the fiber can be guided in the toroidal core, for example.The laser radiation source can, for example, be a fiber laser, in which case the 2-in-1 fiber can then serve as the laser medium, i.e., both for guiding and amplifying the laser radiation. The laser radiation source can also be of a different type and couple the generated laser radiation into the 2-in-1 fiber. The 2-in-1 fiber can, for example, enable a flexible arrangement of the laser radiation source relative to the processing head or a particularly simple and problem-free mobility of the processing head relative to the laser radiation source. This means that when the processing head is moved, traversed, or tilted, the laser radiation source itself does not have to be moved. The use of a 2-in-1 fiber proposed here can enable a beam profile of the output laser beams that is particularly useful for various material processing tasks.For example, a primary processing task, such as cutting or melting material, can be performed by the laser radiation guided in the inner core. Laser radiation guided in the toroidal core, on the other hand, can enable favorable shaping of cutting edges and / or a more favorable temperature profile, particularly a slower or flatter temperature drop starting from the center of the corresponding laser beam.

[0022] In a possible development of the present invention, the laser processing system comprises a control device that is configured to gradually, in particular continuously, change a power distribution of the laser radiation between the inner core and the toroidal core of the 2-in-1 fiber from a predetermined initial power distribution to a predetermined main power distribution over a predefined initial phase of a respective processing operation. The initial power distribution can therefore be used during an initial phase of the processing operation, while the main power distribution can then be used at least for the central main part of the processing operation. In the main power distribution, the power portion of the laser radiation guided in the inner core of the 2-in-1 fiber is greater than in the initial power distribution.The initial phase can be defined, for example, as an absolute duration or as a percentage of the total duration of the machining process. The transition from the initial power distribution to the main power distribution during a machining process, as proposed here, can further reduce the tendency toward or the occurrence of splashing of the machined material. At the same time, relatively short process or machining times can be achieved or maintained.

[0023] In a possible development of the present invention, the laser processing system comprises a control device or the control device mentioned elsewhere, which is configured to gradually, in particular continuously, change a power distribution of the laser radiation between the inner core and the toroidal core of the 2-in-1 fiber over a predefined final phase of a respective processing operation, starting from a predefined main power distribution or the predefined main power distribution mentioned elsewhere, to a predefined final power distribution. The main power distribution can be used at least for a main part or the central main part of the respective processing operation. In contrast to this main power distribution, with the predefined final power distribution, the power portion of the total laser power guided in the 2-in-1 fiber that is guided in the toroidal core of the 2-in-1 fiber is greater than with the main power distribution.In other words, the laser processing system or its control device is designed to gradually shift a certain proportion of the laser power from the inner core to the toroidal core towards the end of each processing operation, or to reduce the laser power in the inner core and increase the laser power in the toroidal core until the specified final power distribution is reached. The final phase can—similar to the initial phase mentioned elsewhere—be specified or defined, for example, as an absolute duration at the end of each processing operation or as a percentage of the total duration of the processing operation. The control of the temporal and spatial distribution of the laser power proposed here can further improve the quality of the processing results achievable using the laser processing system.In particular, for example, the number and / or size of unwanted pores remaining in the processed material after processing, for example in a molten bead created during laser welding, can be reduced. In a further possible embodiment of the present invention, the laser processing system has a sensor system for detecting or monitoring a workpiece to be processed. This means, for example, that a type and / or a respective position of the workpiece or material to be processed can be detected or monitored. Furthermore, the laser processing system here has a control device or the control device mentioned elsewhere. This is set up here to control the laser system depending on corresponding sensor data from the sensor system. The sensor system can, for example, be or comprise a camera or a camera-based sensor system. Likewise, the sensor system can be an interferometric sensor orinterferometry-based sensor technology. Using the sensor technology and the corresponding control system, the output laser beams or their focal points can be positioned or moved with particular precision, particularly automatically, in response to any shifts or movements of the workpiece relative to the laser processing system or the processing head. This, in turn, enables particularly high and consistent processing quality. The sensor technology can, for example, be arranged on the processing head. This enables reliable sensory observation or detection of the processing field at all times, regardless of any movement, tilting, or rotation of the processing head.

[0024] The present invention also relates to a method for processing, in particular welding, a material or workpiece. In the method according to the invention, the workpiece to be processed is positioned in a predetermined processing field of the laser processing system according to the invention. Such a workpiece can, for example, be at least one hairpin pair of an electrical machine, i.e. ends of hairpin windings or hairpin contacts to be welded together. In the method according to the invention, a rotating pattern of several laser points or laser spots is then generated on the workpiece by means of the laser processing system. These can, in particular, be the focal points of the several output laser beams mentioned elsewhere. Furthermore, in the method according to the invention, the respective workpiece is then processed, in particular welded.Further measures, sequences, processes, or controls mentioned in connection with the processing head according to the invention and / or in connection with the laser processing system according to the invention can form further, possibly optional, method steps of the method according to the invention. Further features of the invention can be derived from the following description of the figures and from the drawing. 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 alone can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0025] The drawing shows:

[0026] Fig. 1 is a schematic diagram illustrating laser-based workpiece processing using several rotating laser spots; and

[0027] Fig. 2 is a schematic representation of a prism used to generate the rotating laser spots.

[0028] Identical or functionally equivalent elements are provided with the same reference numerals in the figures.

[0029] Fig. 1 shows a partial schematic representation of a laser processing system 1, which is configured here for material processing, in particular for laser welding. The laser processing system 1 comprises a laser radiation source 2 and a processing head 3 arranged downstream of the laser radiation source 2. The laser radiation source 2 can generate laser radiation, which is indicated here as an input laser beam 4. This input laser beam 4 is so designated because it enters the processing head 3 on the input side. The laser radiation source 2 can be, for example, a disk laser, a diode laser, a fiber laser, or the like.

[0030] The input laser beam 4 can be guided from the laser radiation source 2 to the processing head 3, for example, in a waveguide fiber, in particular a 2-in-1 fiber. Such a fiber can, for example, have an inner core with a diameter of approximately 50 pm and a surrounding toroidal core with a diameter of approximately 200 pm to guide the laser radiation. Other configurations are also possible. Using such a fiber, a laser beam or intensity profile with an inner region and an annular outer region can be produced. Using such a 2-in-1 fiber, two coaxially superimposed laser beams or laser beam components of the input laser beam 4 or two corresponding focus zones, for example a point-shaped or circular inner focus zone and a surrounding annular focus zone, can be generated.This can, for example, enable faster material processing, in particular faster cutting or separating, compared to the exclusive use of a fiber core of a single-core fiber with the same laser power. At the same time, an at least essentially burr-free cutting edge can be produced in a single operation. This can, for example, enable burr-free contour cuts with a relatively slow feed rate in corner areas or radii and a higher feed rate on straight lines or contour sections. It can also be used to avoid a process window gap. The outer annular region of the laser radiation can create a radius or a phase at an inlet or upper end of a corresponding cutting gap or kerf. This allows any process or cutting gas used to be coupled into or flow into the cutting gap or kerf particularly efficiently.

[0031] For the application of the laser processing system 1 shown here as an example for laser welding or thermal conduction welding, the laser radiation source 2 can, for example, generate laser radiation in the visible spectral range, particularly in the green or blue spectral range. This can prevent spatter and / or pores in the material being processed or reduce them compared to other options.

[0032] The processing head 3 comprises a multi-part beam preparation optics unit 5. This can comprise, for example, optical elements such as mirrors and / or lenses and / or diffractive elements and / or refractive elements. For example, the beam preparation optics unit 5 here can comprise a deflection unit for deflecting or aligning the input laser beam 4 in the direction of a material to be processed. Furthermore, the beam preparation optics unit 5 can comprise at least one scanner, for example a galvo scanner, for guiding the laser radiation ultimately output from the processing head 3 over a predetermined processing field. Ultralight mirrors can be used therein to shorten idle times when switching to another processing location. Furthermore, the beam preparation optics unit 5 here comprises a collimator 7 and an optical element for generating a multifocus or a multifocus laser beam distribution or multifocus intensity distribution of the laser radiation.As such an optical element, a wedge plate 8 is provided here, for example, which is inserted into only part of a beam path within the processing head 3. Thus, a portion of the laser radiation guided in the processing head 3 can pass through the wedge plate 8, while another portion of the laser radiation can pass past the wedge plate 8 within the processing head 3. Likewise, several such optical elements or wedge plates 8 can be used.

[0033] The beam preparation optics 5 can comprise a beam splitter or function as a beam distributor. For example, the at least one wedge plate 8 can function as a beam splitter to split the input laser beam 4 into several partial beams. Likewise, the beam preparation optics 5 can comprise a separate beam splitter. At the output side of the beam preparation optics 5, several laser beams or partial beams can then be present next to one another, for example, running truly parallel to one another, which are schematically indicated here as partial beam bundles 6.

[0034] A prism 9 is also located along the beam path in the processing head 3, downstream of the wedge plate 8. This prism 9 can be penetrated by the partial beam bundle 6. The processing head 3 also has a rotation device 10, for example an electrically operated one. This allows the prism 9 to be rotated, in particular continuously or continuously in the same direction, about a rotation axis 11 indicated here during operation of the laser processing system 1. This rotation axis 11 can be located centrally in the beam path and extend in its longitudinal direction. For further illustration, a resulting rotational movement of the prism 9 about the rotation axis 11 is indicated here by an arrow. Due to the rotation of the prism 9, the individual laser beams or partial beams of the partial beam bundle 6 can rotate accordingly about the rotation axis 11 on the output side of the prism 9.

[0035] On the output side, the processing head 3 comprises a focusing unit 12 for focusing the partial beam 6 into a respective processing area 13. In the example shown here, the processing area 13 covers the adjacent end faces of a first joining partner 14a and a second joining partner 14b, which are to be welded together. The joining partners 14a, 14b can be hairpin windings, for example. However, the laser processing system 1 can also be used for other applications or processing tasks.

[0036] In the processing area 13, a first laser point 15a, a second laser point 15b, a third laser point 15c, and a fourth laser point 15d are shown by way of example. These laser points 15a, 15b, 15c, 15d represent focal points of individual partial beams of the partial beam bundle 6. It is particularly evident here that the individual laser points 15a, 15b, 15c, 15c are spatially spaced from one another. Furthermore, the movement of the laser points 15a, 15b, 15c, 15d within the processing area 13, for example, generated by the rotation of the prism 9, is indicated by corresponding arrows.

[0037] The distance between the laser points 15a, 15b, 15c, 15d, i.e., their distribution or arrangement, can be adjusted, for example, depending on the size of the workpiece(s) to be machined. This can be achieved, for example, by appropriately displacing or controlling the focusing unit 12 and / or at least part of the beam preparation optics 5. Thus, by appropriately adjusting or adapting the distances or arrangement or distribution of the laser points 15a, 15b, 15c, 15d, the extent of a weld seam created thereby can be adjusted or adjusted accordingly, depending on the component or workpiece.

[0038] In particular, a distance of the processing area 13, in which the laser points 15a, 15b, 15c, 15d move, from the edge of a surface of the workpiece to be processed that is exposed to the laser radiation, in this case for example the joining partner 14a, 14b, can be set so that it corresponds at least to the respective diameter of the laser points 15a, 15b, 15c, 15d. This can prevent or reduce the spreading of a generated melt. For example, a process or cutting gas nozzle with a Laval internal geometry can be used here. Such a process or cutting gas nozzle can be arranged, for example, on the output side of the processing head 3. The laser processing system 1 can accordingly comprise a process or cutting gas system. With the described setting, a particularly large distance between the process or cutting gas nozzle and the workpiece to be processed can be achieved.This can, for example, reduce the risk of splashes from the workpiece or material being machined settling on the process or cutting gas nozzle.

[0039] If the beam preparation optics 5 or the processing head 3 has the described scanner, a movement of the partial beam bundle 6 caused thereby and a rotational movement of the partial beam bundle 6 caused by the rotation of the prism 9 can overlap. By appropriately controlling these movements, a particularly flexible adaptation or adjustment of a processing contour or processing geometry, for example, a weld seam geometry or weld seam shape, can be achieved.

[0040] To enable or support this, the respective processing area 13 can be detected and monitored by means of a sensor system 16. In addition, the laser radiation source 2 and / or the beam preparation optics 5 and / or the rotation device 10 can be controlled as a function of corresponding observation or sensor data from the sensor system 16, in particular in a manner matched to one another, coordinated with one another, or synchronized with one another. For this purpose, the laser processing system 1 has a correspondingly configured control device 17. This comprises, schematically indicated here by way of example, a processor 18, for example a microchip, microprocessor, or microcontroller, and a computer-readable data memory 19 coupled thereto. This data memory 19 can then, for example, store a corresponding operating or control program that can be executed by the processor 18.The control device 17 can thus, for example, control the rotation speed of the prism 9 and, if necessary, synchronize the scanner, i.e. its mirror positions.

[0041] To further illustrate the beam guidance through the prism 9, Fig. 2 shows a schematic representation of the prism 9 with two partial beams of the partial beam bundle 6 passing through it. The prism 9 is designed here as a Dove prism with a first inclined side surface 20, a base or ground surface 21 and a second inclined side surface 22. The axis of rotation 11 runs parallel to the ground surface 21 and through the two inclined side surfaces 20, 22. Specifically, a first partial beam 6a and a second partial beam 6b are indicated here, which, for example, strike the first inclined side surface 20 of the prism 9 on different sides of the axis of rotation 11 and parallel to it. At this first inclined side surface 20, the partial beams 6a, 6b are refracted in the direction of the base or ground side 21 of the prism 9. There they are internally reflected towards the second inclined side surface 22 of the prism 9.At this point, the partial beams 6a, 6b will be refracted again, so that at the output side of the prism 9 they then run parallel to the beam axis 11 again. In the rotational position of the prism 9 shown here, it can already be seen that the partial beams 6a, 6b at the output side of the prism 9 run on the other side of the rotation axis 11. However, this changes with the rotation of the prism 9 about the rotation axis 11. When the prism 9 rotates, the output-side sections of the partial beams 6a, 6b rotate accordingly about the rotation axis 11, although the input-side sections of the partial beams 6a, 6b in front of the prism 9 are static, i.e. they do not change their position and orientation, and in particular they do not rotate.

[0042] In the example shown here, prism 9 is designed as a dove prism. However, other prism shapes are also possible to achieve the described effect of the laser spots 15a, 15b, 15c, 15d rotating with the rotation of prism 9 in the respective processing area 13.

[0043] Overall, the described examples show how improved laser-based material processing, in particular improved laser welding, can be realized using a multifocus and, for example, a rotating Dove prism.

[0044] LIST OF REFERENCE SYMBOLS

[0045] 1 laser processing system

[0046] 2 Laser radiation source

[0047] 3 processing head

[0048] 4 Input laser beam

[0049] 5 Beam preparation optics

[0050] 6 partial beams

[0051] 6a first partial beam

[0052] 6b second partial beam

[0053] 7 Collimator

[0054] 8 wedge plate

[0055] 9 Prism

[0056] 10 Rotation device

[0057] 11 Rotation axis

[0058] 12 Focusing unit

[0059] 13 Editing area

[0060] 14a first joining partner

[0061] 14b second joining partner

[0062] 15a first laser point

[0063] 15b second laser point

[0064] 15c third laser point

[0065] 15d fourth laser point

[0066] 16 Sensor technology

[0067] 17 Control device

[0068] 18 processor

[0069] 19 data storage

[0070] 20 first inclined side surface

[0071] 21 Base page

[0072] 22 second inclined side surface

Claims

PATENT CLAIMS 1. Processing head (3) for a laser processing system (1), in which an optical system (5) is arranged along a predetermined intended beam path and a prism (9) is arranged downstream of said optical system in the intended propagation direction of laser radiation through the processing head (3), wherein - the optics (5) has at least one input for at least one input laser beam (4) and is designed to simultaneously output several adjacent output laser beams (6, 6a, 6b), - the machining head (3) has a rotation device (10) for rotating the prism (9) about a predetermined rotation axis (11) which runs through two oblique side surfaces (20, 22) of the prism (9), - the optics (5) and the prism (9) are arranged relative to one another in such a way that the plurality of output laser beams (6, 6a, 6b) strike one oblique side surface (20) of the prism (9) next to the axis of rotation (11) and leave the prism (9) next to the axis of rotation (11) through the other oblique side surface (22), so that when the prism (9) rotates about the axis of rotation (11), an image (15a, 15b, 15c, 15d) of the output laser beams (6, 6a, 6b) correspondingly rotating about the axis of rotation (11) is produced on the output side of the prism (9).

2. Processing head (3) according to claim 1, characterized in that the optics (5) comprise a beam splitter for splitting an input laser beam (4) into a plurality of output laser beams (6, 6a, 6b).

3. Machining head (3) according to claim 2, characterized in that the beam splitter comprises an optical wedge plate (8) for generating a multifocus (15a, 15b, 15c, 15d).

4. Machining head (3) according to one of the preceding claims, characterized in that the prism (9) is designed as a dove prism (9) or as a double dove prism or as a roof prism.

5. Machining head (3) according to one of the preceding claims, characterized in that the processing head (3), in particular the optics (5), has a collimator (7) for parallelizing the at least one input laser beam (4) or the plurality of output laser beams (6, 6a, 6b) in front of the prism (9).

6. Processing head (3) according to one of the preceding claims, characterized in that the processing head (3) has a focusing unit (12) arranged downstream of the prism (9) for focusing the output laser beams (6, 6a, 6b) into a predetermined processing area (13).

7. Processing head (3) according to one of the preceding claims, characterized in that the processing head (3) comprises a scanner for scanning deflection of the at least one input laser beam (4) and / or the plurality of output laser beams (6, 6a, 6b) over a predetermined processing field.

8. Laser processing system (1), in particular for laser welding, comprising a laser radiation source (2) for generating at least one laser beam (4) and a processing head (3) according to one of the preceding claims arranged downstream of said source in the intended propagation direction of the laser beam (4).

9. Laser processing system (1) according to claim 8, characterized in that the laser processing system (1) comprises a 2-in-1 fiber for guiding laser radiation (4) in front of the prism (9) and is designed to simultaneously subject an inner core of the fiber and a ring core of the fiber surrounding it to laser radiation (4), in particular with a proportion of at most 10% of the total laser power in the ring core.

10. Laser processing system (1) according to claim 9, characterized in that the laser processing system (1) comprises a control device (17) which is designed to control, over a predefined initial phase of a processing operation, a power distribution of the laser radiation (4) between the inner core and the toroidal core of the 2-in-1 fiber starting from a to change the predetermined initial power distribution, in particular continuously, to a predetermined main power distribution which is used for the central main part of the processing operation and in which the power component guided in the inner core of the 2-in-1 fiber is greater than in the initial power distribution.

11. Laser processing system (1) according to claim 9 or 10, characterized in that the laser processing system (1) comprises a control device which is set up to change a power distribution of the laser radiation (4) between the inner core and the toroidal core of the 2-in-1 fiber, in particular continuously, over a predefined final phase of a processing process, starting from a predetermined main power distribution which is used for the central main part of the processing process, to a predetermined final power distribution in which the power component guided in the toroidal core of the 2-in-1 fiber is greater than in the main distribution.

12. Laser processing system (1) according to one of claims 8 to 11, characterized in that the laser processing system (1) has a sensor system (16) for detecting a workpiece (14a, 14b) to be processed in each case and a control device (17) for controlling the laser processing system (1) as a function of corresponding sensor data of the sensor system (16).

13. Method for machining, in particular welding, a workpiece (14a, 14b), in which - the workpiece (14a, 14b) to be machined is positioned in a predetermined machining field of a laser machining system (1) according to one of claims 8 to 10, - a rotating pattern of several laser points (15a, 15b, 15c, 15d) is generated on the workpiece (14a, 14b) by means of the laser processing system (1), and - so that the workpiece (14a, 14b) is machined, in particular welded.

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