WO2021140037A1

WO2021140037A1 - Method for the automated beam positioning of a laser beam in relation to a nozzle of a laser processing head, and laser processing system for processing a workpiece using a laser beam

Info

Publication number: WO2021140037A1
Application number: PCT/EP2020/087810
Authority: WO
Inventors: Niklas WECKENMANN
Original assignee: Precitec Gmbh & Co. Kg
Priority date: 2020-01-08
Filing date: 2020-12-23
Publication date: 2021-07-15
Also published as: DE102020100217A1

Abstract

The invention relates to a method for the automated beam positioning of a laser beam in relation to a nozzle of s laser processing head, wherein the method comprises the following automated steps: directing an adjusting laser beam, oriented coaxially to the laser beam, onto an outlet opening of the nozzle mounted on the laser processing head; and determining whether the adjusting laser beam passes through the outlet opening; and if the adjusting laser beam passes through the outlet opening, receiving a two-dimensional image of the outlet opening and the adjusting laser beam passing through the outlet opening, as well as of a nozzle mouth surrounding the outlet opening; determining a position of the adjusting laser beam and a position of the outlet opening of the nozzle based on the captured image; determining whether a deviation of the determined position of the adjusting laser beam from a predefined position of the adjusting laser beam is greater than a predefined maximum deviation; if the deviation is greater than the predefined maximum deviation, adjusting the relative position of the adjusting laser beam and the outlet opening; and repeating the steps of receiving a two-dimensional image, determining the position of the adjusting laser beam and the outlet opening, determining the deviation and adjusting the relative position, until the deviation of the determined position of the adjusting laser beam from the predefined position of the adjusting laser beam is less than or equal to the predefined maximum deviation. The invention relates to a laser processing system for processing a workpiece using a laser beam.

Description

Method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and laser processing system for processing a workpiece with a laser beam

The present disclosure relates to a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and a Laserbear processing system for processing a workpiece, in particular a metallic workpiece, with a laser beam that is set up for automated beam positioning.

background

In a laser processing system for processing a workpiece, in particular a metallic workpiece, the laser beam exiting from a laser light source or one end of a laser guide fiber, also called a “processing laser beam”, is focused or bundled onto the workpiece to be processed with the aid of beam guidance and locating optics , which heats the workpiece locally to the melting temperature. The processing can include, for example, laser cutting, soldering or welding. The laser processing system can comprise a laser processing device, for example a laser processing head, or “processing head” for short, for example a laser cutting head or a laser welding head.

For the quality, stability and direction independence of a laser machining process, it is important for most applications that the laser beam emerges from the laser machining head in a centered manner. In particular, the laser beam should be centered or centered with respect to an exit opening of the laser processing head through which the laser beam emerges from the laser processing head. The outlet opening can be formed, for example, in a nozzle, in particular a cutting nozzle, which is mounted on the laser processing head. The central alignment of the laser beam, also called "centering of the laser beam" or "beam centering" for short, must be carried out after each change of a component of the laser processing head, for example when changing the nozzle, an optical system in the beam path of the laser beam, the laser source, or similar. In particular, the beam centering must also be carried out after a collision of the laser processing head with a workpiece or another object. In other applications, a predetermined jet position must be set relative to the outlet opening of the nozzle, for example, in the case of an oval outlet opening, a jet position offset along the long axis to the center point of the outlet opening. The beam centering is usually a lengthy and laborious manual process, which leads to a not inconsiderable process idle time. For this purpose, a transparent adhesive strip is placed on the underside of the nozzle and a short laser pulse creates a burn-in on the adhesive strip (a so-called "tape shot"). This makes the position of the laser beam visible relative to the outlet opening of the nozzle. An operator is now able to change the position of the laser beam perpendicular to the beam axis by manually moving a locating optics until a central alignment of the laser beam with respect to the outlet opening of the nozzle is established. This process can involve several iterations and take several minutes, depending on the operator's experience. Furthermore, the accuracy of the beam centering is heavily dependent on the respective operator, which in turn has a direct influence on the processing result and the processing quality.

EP 1 967 316 A1 describes a device and a method for beam centering, where a nozzle is adjusted relative to the laser beam. DE 102004005 902 B3 describes a device for adjusting a laser beam in a laser processing machine, where an alignment unit equipped with an evaluation unit with a cutting nozzle Lixierungselement is provided for adjusting the laser beam. WO 2019/009833 A2 be writes a centering device for a laser beam of a laser cutting machine, with drive and adjustment elements being provided in the centering device.

One focus of current developments, however, is increasing digitization and automation of machine components and the overall system.

Disclosure of the invention

It is an object of the present disclosure to provide a method for the automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and a laser processing system for processing a workpiece with a laser beam, which a fast, precise and simple positioning of the laser beam with respect to the nozzle, in particular a Allow beam centering and a check of the nozzle status. It is also an object of the present disclosure to increase the accuracy of the beam positioning and to reduce the non-productive process time required for the beam positioning, and thus to make a machining process, for example a cutting process, welding process or build-up welding process, more efficient. It is a further object of the present disclosure to provide a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and a laser processing system for processing a workpiece with a laser beam, which includes automated or automatic beam positioning and automated or automatic checking the state of the nozzle.

These objects are achieved by the subject matter of the independent claims. Before partial embodiments of the invention are the subject of dependent claims.

According to a first aspect of the invention, a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head is specified, the method comprising the following steps (preferably carried out automatically): Directing an alignment laser beam coaxial to the laser beam onto an exit opening of one mounted on the laser processing head Jet; Recording an image of the outlet opening and of a nozzle mouth surrounding the outlet opening; and determining whether the alignment laser beam passes through the exit opening, for example on the basis of the recorded image; and if the alignment laser beam passes through the outlet opening: determining a position of the alignment laser beam passing through the outlet opening and a position of the outlet opening of the nozzle on the basis of the recorded image; Determining whether a deviation of the determined position of the alignment laser beam from a predetermined position of the alignment laser beam is greater than a predetermined maximum deviation; if the deviation is greater than the specified maximum deviation, adjusting the relative position between the alignment laser beam and the exit opening; and repeating the steps of taking an image, determining the positions of the alignment laser beam and the exit opening, determining the deviation and adjusting the relative position until the deviation of the determined position of the alignment laser beam from the predetermined position of the alignment laser beam is less than or equal to the predetermined one maximum deviation. Here, the relative position can designate a position of the alignment laser beam relative to the exit opening. The predefined position of the alignment laser beam is preferably predefined relative to the position of the outlet opening. If the alignment laser beam passes through the exit opening, the recorded image thus includes not only an image of the exit opening and the nozzle mouth, but also of the Ju Stier laser beam.

According to a further aspect of the invention, a laser processing system for processing a workpiece with a laser beam is specified, the laser processing system comprising: a laser source which is set up, the laser beam and an alignment laser beam to generate a laser processing head with a nozzle, wherein the nozzle comprises an exit opening for the exit of the laser beam or the alignment laser beam from the laser processing head and a nozzle mouth surrounding the exit opening, an adjustment unit for adjusting the relative position of the alignment laser beam and the exit opening, an alignment unit with an optical detection unit, the optical detection unit being set up to record an image of the outlet opening and of the nozzle mouth; a control device which is set up to use the recorded image to determine a position of the alignment laser beam and a position of the outlet opening of the nozzle, to determine a deviation of the determined position of the alignment laser beam passing through the outlet opening from a predetermined position of the alignment laser beam, and by actuation the adjustment unit to adjust the relative position between the alignment laser beam and the exit opening if the deviation is greater than a predetermined maximum deviation. The control device can be set up to repeat the steps of taking an image, determining the positions of the alignment laser beam and the exit opening, determining the deviation and adjusting the relative position until the deviation of the determined position of the alignment laser beam from the predetermined position of the alignment laser beam is smaller is than or equal to the specified maximum deviation. In particular, the control device can be set up to carry out a method in accordance with one of the exemplary embodiments described herein. Here, the relative position can denote a position of the alignment laser beam relative to the exit opening. The predefined position of the alignment laser beam is preferably predefined relative to the position of the outlet opening.

In the case of a laser processing head of a laser processing system, the invention makes it possible to position the laser beam fully automatically with respect to an exit opening of a nozzle mounted on the laser processing head (so-called "adjustment of the beam guidance system"). Intervention by an operator of the laser processing head or the laser processing system is therefore no longer necessary. At the same time, the invention provides the possibility of automatically checking the state of the nozzle or the nozzle mouth (so-called “nozzle inspection”). Accordingly, the invention enables both automated beam positioning and automated nozzle inspection in a laser processing head of a laser processing system. The automated beam positioning and / or nozzle inspection can take place automatically after changing the nozzle attached to the laser processing head or after a collision of the laser processing head or the nozzle with another object, for example a workpiece to be processed. The automated beam positioning can also be started manually by an operator of the laser processing system. Lemer can do all the steps of the process can be carried out automatically and / or remotely. As a result, an operator of the laser processing system no longer has to be in the immediate vicinity of the laser processing head for beam positioning or for nozzle inspection. This can increase work safety.

In order to set the position of the alignment laser beam relative to the exit opening, either the nozzle can be moved with respect to the optical beam path of the laser processing head on the laser processing head and / or the position of the laser beam in the optical beam path of the laser processing head can be adjusted, preferably in a plane perpendicular to the optical beam path of the laser processing head or to the optical axis of the laser processing head. Since the relative position between the alignment laser beam and the exit opening is set directly based on the determined positions of the alignment laser beam of the exit opening, the accuracy can be increased.

The automated beam positioning can include an automated beam centering or an automated targeted beam decentering. The automated beam positioning thus includes every automated adjustment of the relative position of the adjustment laser beam and the exit opening. The relative position of the alignment laser beam and the exit opening can include both the position of the alignment laser beam relative to the position of the exit opening and the position of the exit opening relative to the position of the alignment laser beam. The position of the adjustment laser beam and the position of the outlet opening can correspond to a position of the center or the midpoint, in particular the center of gravity, of the adjustment laser beam and the outlet opening. The positions can be determined in a plane perpendicular to the optical propagation direction of the alignment laser beam and / or an optical axis of the laser processing head, in particular a plane in the area of the exit opening. The positions can in particular be specified with respect to two orthogonal directions in this plane.

The diameter of the alignment laser beam can be smaller than a diameter, in particular a minimum diameter, of the outlet opening. The cross-sectional area of the Justierla serstrahls can be smaller than the area of the outlet opening. The diameter and the cross-sectional area of the alignment laser beam and the diameter and the area of the exit opening can be specified in a plane that includes the exit opening and is arranged perpendicular to the optical beam path of the laser processing head and / or to the optical axis of the laser processing head. The alignment laser beam therefore preferably does not completely illuminate the exit opening. The alignment laser beam can be the laser beam that is used for laser processing by the laser processing system, or it can be different from the laser beam. The adjustment laser beam can have the same or a lower power than the laser beam and / or can have the same or a different wavelength as the laser beam. The alignment laser beam runs coaxially to the laser beam. Automated positioning of the laser beam can thus be carried out by using the adjustment laser beam.

The nozzle is mounted on the laser processing head. The nozzle has a nozzle mouth and an exit opening for the exit of the laser beam and the alignment laser beam. In other words, the outlet opening is surrounded by the nozzle mouth. An inner contour of the nozzle mouth thus delimits the outlet opening and defines the shape of the outlet opening. The nozzle mouth and the outlet opening are formed on one end of the nozzle facing the workpiece to be processed by the laser processing head. The exit opening can be viewed as a flat surface. An end face of the nozzle mouth can be coplanar with the outlet opening. The end face can be formed on an end of the nozzle mouth facing the workpiece to be machined by the laser machining head.

The plane described above in the area of the outlet opening can encompass the nozzle mouth, in particular the end face of the nozzle mouth, and / or the outlet opening itself. The plane in the area of the outlet opening can be coplanar with the face of the nozzle mouth. The plane in the area of the exit opening can be coplanar with the exit opening. The plane in the area of the exit opening can be formed perpendicular to the optical beam path of the laser processing head and / or to the optical axis of the laser processing head.

The predefined position of the alignment laser beam can be predefined relative to the position of the outlet opening. The predetermined position of the alignment laser beam can correspond to a center or a center point of the outlet opening or can correspond to a given offset from the center or center point of the outlet opening.

The determination of whether the alignment laser beam passes through the exit opening can take place with the aid of the optical detection unit. The determination can in particular include the recording of an image and / or a video by the optical detection unit and a subsequent image analysis. If it is determined that the alignment laser beam passes through the exit opening, a two-dimensional image of the exit opening and the alignment laser beam passing through the exit opening as well as of the nozzle mouth can be recorded or the previously recorded image can be used to determine the relative position.

The image can include a two-dimensional image, photo, video, or moving image. When recording moving images or a video, the position of the alignment laser beam and / or the position of the outlet opening can be detected in real time, e.g. while the relative position is being adjusted. This can be referred to as "tracking the alignment laser". Based on this, the adjustment unit of the laser processing system can be controlled in order to adjust the relative position of the adjustment laser beam and the exit opening.

The image can in particular be recorded in an image plane outside the laser processing head, e.g. in a plane below the nozzle mouth or between the nozzle mouth and the optical detection unit. The image is preferably recorded when the nozzle mouth is focused. The image plane can in particular be arranged perpendicular to the optical axis of the laser processing head and can be parallel to the plane described above in the area of the exit opening. The image plane can in particular correspond to a sensor plane or sensor surface of the optical detection unit.

Determining the position of the alignment laser beam and the position of the exit opening can include determining a centroid of the exit opening and determining a centroid of the alignment laser beam. The centroid of the exit opening can in particular be determined as the predetermined position of the adjusting laser beam for beam centering. The positions and / or the centers of gravity can be indicated in the image plane described above, e.g. in the area of the outlet opening or the nozzle mouth. The determination of the positions and the determination of the center of gravity takes place on the basis of the recorded image by means of image processing.

The determination of the centroid of the outlet opening can include determining an inner contour of the nozzle mouth by image analysis and / or image processing of the recorded image. The determination of the centroid of the alignment laser beam can include the determination of a contour of the alignment laser beam by image analysis and / or image processing of the recorded image. The image processing can include image preprocessing, image segmentation, determination of the contours and calculation include deviation of deviations. The image processing enables a direct, spatially resolved measurement of the position of the alignment laser beam with respect to the exit opening.

The deviation of the determined position of the alignment laser beam from the predetermined position of the alignment laser beam can correspond to a distance between the determined position of the alignment laser beam and the predetermined position of the alignment laser beam.

The deviation of the determined position of the adjustment laser beam from the specified position of the adjustment laser beam can be a first deviation of the determined position of the adjustment laser beam from the specified position of the adjustment laser beam in a first direction and a second deviation of the determined position of the adjustment laser beam from the specified position of the adjustment laser beam include in a second direction. The first direction and the second direction can be perpendicular to one another and extend in the plane described above in the area of the outlet opening. The first direction and / or the second direction can be defined with reference to the outlet opening and in particular run through the center point of the outlet opening. The first direction and the second direction can in particular correspond to a first axis and a second axis of a Cartesian coordinate system, the origin of the Cartesian coordinate system corresponding to the center of the outlet opening. In the case of an oval outlet opening, the first direction and the second direction can run along the long axis and the short axis.

The predefined maximum deviation can comprise a first predefined maximum deviation along the first direction and a second predefined maximum deviation along the second direction. It can be determined that the deviation is greater than the specified maximum deviation if the first deviation of the determined position of the adjustment laser beam from the specified position of the adjustment laser beam in the first direction is greater than the first specified maximum deviation and / or if the second The deviation of the determined position of the alignment laser beam from the predetermined position of the alignment laser beam in the second direction is greater than the second predetermined maximum deviation.

If the deviation is greater than the specified maximum deviation, the relative position of the alignment laser beam and the outlet opening can be adjusted. If the deviation is equal to or smaller than the specified maximum deviation, the process can be terminated. Taking a two-dimensional image, determining the positions of the alignment laser beam and the exit opening, determining the deviation and the adjustment of the relative position is preferably repeated until the deviation of the determined position of the alignment laser beam from the predetermined position of the alignment laser beam is less than or equal to the predetermined maximum deviation.

The image can be recorded by the optical detection unit. The optical cal acquisition unit is arranged outside the laser processing head or separately from it. The method can therefore include moving the laser processing head to the optical detection unit, so that the outlet opening and the nozzle mouth of the nozzle mounted on the laser processing head are in the field of view of the optical detection unit. The laser processing head is preferably aligned with the optical detection unit in such a way that an optical axis of the optical detection unit runs essentially parallel or coaxially to an optical axis of the laser processing head. In other words, the laser processing head can be moved to the optical detection unit so that the exit opening overlaps with a sensor surface of the optical detection unit in a direction perpendicular to the optical axis of the laser processing head and / or to the optical axis of the optical detection unit. It can thereby be ensured that an image recorded by the optical detection unit shows at least the exit opening completely.

The method can further include determining a nozzle state on the basis of at least one recorded image. The method can further comprise determining, on the basis of at least one recorded image, whether a nozzle state condition is met and, if the nozzle state condition is not met, outputting an error. The step of determining the nozzle state or the fulfillment of the nozzle state condition can take place simultaneously or immediately before or after the step of determining whether the alignment laser beam passes through the exit opening, and can preferably take place on the basis of the same recorded image.

Determining whether the nozzle state condition is met can include determining a value of a nozzle state parameter on the basis of the recorded image, and comparing the determined value with at least one predetermined value for the nozzle state parameter. The value of the nozzle condition parameter can be determined by image analysis and / or image processing. A possible deformation of the nozzle or the nozzle mouth and / or the outlet opening can thereby be determined. In addition, a change in the surface properties of the nozzle or the nozzle mouth can be determined. The nozzle state parameter can comprise a geometric nozzle state parameter which comprises an inner contour of the nozzle mouth, an ellipticity of the inner contour of the nozzle mouth, a diameter of the inner contour of the nozzle mouth and / or a form factor of the inner contour of the nozzle mouth. The ellipticity of the inner contour of the nozzle mouth can include a ratio between a short axis of the outlet opening and a long axis of the outlet opening. The ellipticity can assume a value between 0 and 1, where 1 corresponds to a circular outlet opening. The form factor of the inner contour of the nozzle mouth can be based on an area of the outlet opening and / or a circumference of the inner contour of the nozzle mouth.

The nozzle state parameter can comprise an optical nozzle state parameter that comprises a reflectivity of the nozzle mouth. The reflectivity of the nozzle mouth can also be referred to as the "reflection behavior of the nozzle mouth" and can be based on a gray value, i.e. a relative light intensity, of the nozzle mouth. If the determined gray value does not correspond to a predefined gray value, it can be concluded that the nozzle or nozzle mouth is damaged and / or soiled.

Determining whether a nozzle state condition is met can include determining a value of a plurality of nozzle state parameters and comparing the determined values with the respective predetermined values.

The method can furthermore include illuminating the nozzle or the nozzle mouth, in particular from an outside of the nozzle or the nozzle mouth. The illumination can take place during the determination of whether the alignment laser beam passes through the exit opening, during the recording of the image and / or during the determination of whether a nozzle state condition is met.

The control device can be set up to carry out the method described above. The control device can control the optical detection unit, the alignment unit, the laser source and the adjustment unit and / or can serve as a communication interface between these elements. The control device can be integrated into a control unit of the laser processing head and / or parts of the functionality of the control device can be taken over by the control unit of the laser processing head. The control device can be integrated into a control unit of the laser processing system, also called “CNC” or “machine control”, and / or parts of the control device can be taken over by the control unit of the laser processing system. The control device can be set up for image analysis and / or for image processing. The adjustment unit can be arranged or mounted in or on the laser processing head. The adjustment unit can be integrated into the laser processing head and / or can be controlled remotely. The adjustment unit can comprise at least one, in particular remotely controllable, movement unit arranged on or in the laser processing head. The movement unit can be set up to move at least one of the following elements in a plane perpendicular to the optical axis of the laser processing system: at least one optical element arranged in the beam path of the laser processing head, at least part of a focusing optics of the laser processing head, at least part of a collimation optics of the Laser processing head, a fiber end of an optical fiber feeding the alignment laser beam and / or the laser beam to the laser processing head, a fiber socket for coupling an optical fiber guiding the alignment laser beam and / or the laser beam to the laser processing head, and the nozzle. The focusing optics can comprise a focusing lens and / or a focusing lens package, in particular a focusing unit. The collimation optics can also include a collimation lens and / or a collimation lens package, in particular a collimation unit.

Adjusting the relative position of the alignment laser beam and the exit opening can include moving at least one of these elements in the plane perpendicular to the optical axis of the laser processing system. Moving can include moving the element in a first direction and / or in a second direction in this plane, the first direction being different from the second direction, and in particular orthogonal to the second direction. Moving the at least one element in the first direction preferably leads to a movement of the alignment laser beam in a first direction, and moving the at least one element in the second direction leads to a movement of the alignment laser beam in a second direction. In other words, the adjustment laser beam can preferably be moved independently of one another in the first and the second direction in a plane perpendicular to the optical axis of the laser processing head in the area of the exit opening by moving the at least one element.

The method can further comprise the following steps: if the alignment laser beam does not pass through the exit opening, repeating the following steps until it is determined that the alignment laser beam passes through the exit opening: moving the at least one element in the plane perpendicular to the optical axis a predetermined path and determining whether the alignment laser beam passes through the exit opening. These steps may be necessary in particular if the nozzle or the nozzle mouth shadows the alignment laser beam so that the optical detection unit does not detect the alignment laser beam. animals or can capture. In other words, the alignment laser beam would not be visible on the image recorded by the optical detection unit. This case can occur, for example, with a small diameter of the outlet opening and / or an incorrect position or alignment of the alignment laser beam. Moving the at least one element in the plane perpendicular to the optical axis along a predetermined path can also be referred to as a “reference cycle”. The predetermined path can include different movement patterns and / or directions of movement of the at least one element, for example the path can be zigzag or meandering. Moving the at least one element can result in particular in a zigzag movement or a meandering movement of the alignment laser beam in the plane perpendicular to the optical axis. The zigzag movement or the meandering movement can be carried out until the optical detection unit can detect the alignment laser beam. The predetermined path can also include moving the at least one element up to a first end position in a first direction and then moving the at least one element up to a second end position in a second direction. The at least one element is then moved to a central position in the first direction and in the second direction. The middle position can be a theoretical and / or calculated middle position.

The movement unit of the adjustment unit can comprise at least one actuator which is mounted on the laser processing head and is set up to provide a rotational movement. The rotational movement can be provided by an element of the actuator, in particular a shaft or axle. The movement unit can in particular comprise two such actuators, which can preferably be controlled independently of one another. The movement unit can furthermore comprise at least one mechanical unit. The at least one mechanical unit can be set up to convert the rotational movement provided by the at least one actuator into a translational movement in order to move the element in at least one direction along the plane perpendicular to the optical axis. In particular, the at least one mechanical unit can be set up to convert the rotational movement provided by a first actuator into a translational movement of the at least one optical element in the first direction and the rotational movement provided by a second actuator into a translational movement of the at least one optical element in the second Convert direction. As a result, the optical element can be moved independently of one another in the first direction and in the second direction. The at least one actuator can comprise an electric motor, a three-phase motor, a linear motor, an AC motor and / or a stepping motor. The motors can be mounted on or in the laser processing head or integrated into it.

The optical axis of the optical detection unit and the optical axis of the Laserbear processing head can run parallel to one another or coaxially.

The alignment unit can further comprise at least one of the following elements: a cover which can be remotely opened and closed; a lighting device configured to illuminate the nozzle mouth; imaging optics that are set up to image the nozzle mouth and the alignment laser beam on a sensor plane and / or an image plane of the optical detection unit, and / or at least one optical filter that is set up to pass a wavelength of the alignment laser beam and a wavelength of the illumination device allow. The imaging optics can comprise a fixed focal length lens and / or a zoom lens. The at least one optical filter can comprise a bandpass filter. The lighting device enables optimal illumination of the nozzle mouth under different ambient conditions and light enables optimal contrast for taking the image or for determining the inner contour of the nozzle mouth. The lighting device can be designed as a ring-shaped lighting device, and can in particular be designed as a lighting device that emits light in the red color spectrum. The lighting device can in particular be set up to illuminate the nozzle or the nozzle mouth from the side.

The optical detection unit can comprise at least one of the following: a camera system, a camera, a CCD sensor, a CMOS sensor, a photodiode array. The optical detection unit can in particular be set up to detect or detect objects, in particular nozzles, with a size of at least 5 mm × 5 mm, preferably in the range of 10 mm × 10 mm.

The laser processing system can furthermore comprise a movement unit which is set up to move the laser processing head. The control device or a higher-level control unit of the laser processing system can be set up to control the movement unit in order to move the laser processing head to the alignment unit and to align it so that the optical axis of the optical detection unit is essentially coaxial with an optical axis of the laser processing head.

Brief description of the drawings Embodiments of the disclosure are shown in the figures and are described in more detail below. Show it:

Fig. 1 is a schematic representation of a laser processing system for processing a workpiece with a laser beam according to an embodiment of the present inven tion;

2 shows a schematic representation of a laser processing system for processing a workpiece with a laser beam according to embodiments of the present invention;

3 shows a flow diagram of a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head according to embodiments of the present invention;

4A and B show a flowchart of a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head according to an embodiment of the present invention;

5 shows a schematic and exemplary illustration of an image that was recorded by an optical detection unit of a laser processing system for processing a workpiece with a laser beam according to embodiments of the present invention;

6 shows a schematic representation of an inner contour of a nozzle mouth according to embodiments of the present invention;

7 in the upper part a schematic representation of a nozzle of a laser processing head according to an embodiment of the present invention and in the lower part an exemplary gray value curve of the nozzle;

8 and 9 schematic representations of movements of a laser beam along a predetermined path according to embodiments of the present invention.

Embodiments of the disclosure Unless otherwise noted, the same reference numerals are used below for elements that are identical and have the same effect.

1 shows a schematic illustration of a laser processing system for processing a workpiece with a laser beam according to an embodiment of the present invention. Fig. 2 shows a schematic representation of a laser processing system for processing a workpiece with a laser beam according to embodiments of the present invention.

The figures show a laser processing system 10 for processing a workpiece (not shown) with a laser beam (not shown). The laser processing system 10 is set up to carry out the method for automated beam positioning of the laser beam according to embodiments of the present invention. In addition, the laser processing system 10 is preferably set up to carry out an automated nozzle inspection.

The laser processing system 10 comprises a laser source 20, a laser processing head 30, an adjustment unit 40, an alignment unit 50 and a control device 60. The laser source 20 is set up to supply the laser beam and an adjustment laser beam 21, also called “pilot laser” or “pilot laser beam” produce. The laser beam or the alignment laser beam 21 are coupled into the laser processing head via an optical fiber 22 and a fiber socket 22a. The alignment laser beam 21 runs coaxially to the laser beam. As a result, the laser beam can also be adjusted by positioning the adjusting laser beam 21. The laser beam can be a machining laser beam for machining a workpiece, in particular a metallic workpiece. Alternatively, the laser beam itself can also be used as an alignment laser beam 21, for example with a lower power than for material processing.

The laser processing head 30 has a nozzle 31. The nozzle 31, which can be a nozzle electrode, comprises a nozzle mouth 32 and an exit opening 33 for the exit of the laser beam and the alignment laser beam from the laser processing head 30. The nozzle 31 can be integrally connected to the laser processing head 30, or it can be movable on the laser processing head 30 be mounted. The laser processing head 30 can comprise a plurality of optical elements, optics and / or optical units, also called “packages”. These include, for example, lenses, lens packages, and mirrors. According to embodiments, the optical elements or the optical units comprise elements or units that transmit the laser beam and the alignment laser beam and / or elements or units th, which at least partially reflect the laser beam and the alignment laser beam. As shown in FIG. 1, the laser processing head 30 has collimation optics 35 and focusing optics 36. The collimation optics 35 and / or the focusing optics 36 can ent long an optical axis z of the laser processing head 30, which is coaxial with a beam

5 propagation direction of the alignment laser beam 21 can be shifted in order to set a focus position of the alignment laser beam 21 or the laser beam.

The alignment unit 50 comprises an optical detection unit 51 which is set up to record a two-dimensional image of the outlet opening 33 and the alignment laser beam 21 passing through the outlet opening fO as well as of the nozzle mouth 32. The control device 60 is set up to determine a position of the alignment laser beam 21 and a position of the outlet opening 33 of the nozzle 31 based on the recorded image, to determine a deviation of the determined position of the alignment laser beam 21 from a predetermined position of the alignment laser beam 21, and through Controlling the adjustment unit 40 to adjust the f5 position of the adjustment laser beam 31 relative to the position of the outlet opening 33 if the deviation is greater than a predetermined maximum deviation.

The adjustment unit 40 is set up to adjust the position of the adjustment laser beam 31 relative to the position of the outlet opening 33. The adjustment unit 40 can be in or on the laser

20 machining head 30 can be arranged or mounted. The adjustment unit 40 can also be integrated into the laser processing head 30.

The adjustment unit comprises a movement unit 4L arranged on or in the laser processing head 30. The movement unit 41 is set up to be an element, in particular a

25 optical element or an optical unit to move, move or position in a plane perpendicular to the optical axis z of the laser processing head 30. The move gene of the element has the consequence that the position of the alignment laser beam 21 relative to the position of the exit opening 33 or the position of the exit opening 33 relative to the position of the alignment laser 21 in a plane in the area of the exit opening that is perpendicular to the opti

30's axis is arranged, is adjusted.

In FIGS. 1 and 2, the plane is defined perpendicular to the beam axis z by the two directions x and y. In other words, the directions x and y are perpendicular to the optical axis z and are orthogonal to one another. Moving the element or the optical unit

35 may thus comprise moving the element along the x-direction and along the y-direction. According to the embodiments shown, the movement unit 41 is set up to move at least part of the focusing optics 36. The focusing optics 36 can comprise a focusing lens and / or a focusing lens package. According to other embodiments, the movement unit 41 can be set up, at least part of a collimation optics of the laser processing head 30, a fiber end of the optical fiber 22 feeding the alignment laser beam 21 and / or the laser beam to the laser processing head 30, a fiber socket 22a for coupling the alignment laser beam 21 and / or the Laser beam leading fiber optic 22 on the laser processing head 30 and / or the nozzle 31 to move.

The movement unit 41 comprises at least one actuator, in particular a motor unit or a motor. The at least one actuator can in particular be designed as an electric motor, e.g. three-phase, linear, step or alternating current motor. According to the embodiment shown in FIG. 1, the movement unit 41 comprises an actuator. According to the embodiment shown in FIG. 2, the movement unit 41 comprises two actuators 42a, 42b. According to the embodiments shown, the at least one actuator is attached to the laser processing head 30. As shown in FIG. 2, the actuators 42a, 42b can be integrated in the laser processing head 30.

The at least one actuator is set up to provide a rotary movement, in particular via a shaft or axis. According to the embodiment shown in FIG. 2, the movement unit 41 comprises a first actuator 42a with a rotational movement RI and a second actuator 42b with a rotational movement R2, the rotational movements RI and R2 being independent of one another. In other words, the actuators 42a, 42b can be controlled independently of one another. The movement unit 41 preferably comprises two stepper motors as actuators, one stepper motor each converting the directions of movement x and y.

The movement unit 41 furthermore comprises at least one mechanical unit (not shown), also called “mechanics”. The at least one mechanical unit is set up to convert the rotational movement provided by the at least one actuator into a translatory movement in the xy plane perpendicular to the direction of beam propagation z. As shown in FIG. 2, the mechanical unit is set up to convert the rotational movement RI provided by the first actuator 42a into a translational movement of the element along the x direction and the rotational movement R2 provided by the second actuator 42b into a translational movement along the y -To change direction. As a result, the element, here the focusing optics 36, can be moved independently of one another in the x-direction and in the y-direction. The optical detection unit 51, which can also be referred to as an “imaging detector”, can include, for example, a camera and / or a sensor, in particular an image sensor. The optical detection unit 51 preferably comprises at least one CCD sensor (CCD: “charge-coupled device”) or a CMOS sensor (CMOS: “complementary metal-oxide-semiconductor”). According to the invention, a CMOS sensor is preferably used.

The alignment unit 50 also includes imaging optics 52, also called “objective”. The imaging optics 52 images both the alignment laser beam 21 and the nozzle mouth 32, ie a certain area of the underside of the nozzle 31, onto the optical detection unit 51, in particular on a sensor surface or sensor plane of the optical detection unit 51 at least objects with a size of 5 mm x 5 mm can be detected. Objects up to a size of 10 mm × 10 mm are preferably detected. The imaging optics 52 can comprise a fixed focal length lens or a zoom lens. According to the invention, a fixed focal length lens is preferably used.

The alignment unit 50 can also include a lighting device 54 and / or an optical filter unit 53 with at least one optical filter and / or an optical filter package. Bandpass filters are preferably used which filter the ambient light and transmit the wavelength of the alignment laser beam 21 and the wavelength range of the lighting device 54. The lighting device 54 is used to optimally illuminate the nozzle mouth 32 in different ambient conditions and ensures an optimal contrast for the detection of the nozzle inner contour during image processing. Ring lighting is preferably used, which emits light in the red color spectrum. Lateral illumination of the nozzle 31 is also possible.

The alignment unit 50 further comprises a cover 55 which can be opened and closed automatically or remotely. A housing 56, also called "housing", protects the elements of the alignment unit 50 contained therein, such as the optical acquisition unit 51, the imaging optics 52, the optical filter unit 53 and the lighting device 54, from various environmental influences, such as dirt, dust and Water. According to embodiments of the present invention, the alignment unit 50 is provided as an independent station in the laser processing system, or is integrated into a nozzle changer system. The control device 60, also referred to as an “evaluation unit”, is set up to control the optical detection unit 51, the alignment unit 50, the laser source 20 and / or the adjustment unit 40. According to embodiments of the invention, the control device 60 serves as a communication interface between these elements.

According to one embodiment of the present invention, the control device 60 communicates, among other things, with a higher-level controller, for example a so-called “CNC” or a machine controller (not shown). The main task of the control device 60 is to process and transmit control and information signals between the adjustment unit 40 and the optical detection unit 51 or the alignment unit 50. The method for automated beam positioning of the laser beam according to embodiments of the present invention is started by the CNC and the CNC in turn receives the signal from the control device 50 about the end of the method.

According to a further embodiment of the present invention, the control device 60 combines the tasks of machine control and automated beam positioning of the laser beam according to embodiments of the present invention. The control device 60 communicates with the laser source 20, with the machine components (not shown), the adjustment unit 40 and the optical detection unit 51 or the alignment unit 50.

In both embodiments, the control device 60 takes on the task of image processing, the control of the lighting device 54, the control of the adjustment unit 40 and the opening and closing of the alignment unit 50.

Fig. 3 shows a flow chart of a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head according to execution forms of the present invention. The method comprises the following, preferably automated, steps.

After the start (SO) a coaxial to the laser beam adjustment laser beam 21 is directed to an exit opening 33 from a nozzle 31 mounted on the laser processing head 30 (S1). An image of the outlet opening 33 and of a nozzle mouth 32 surrounding the outlet opening is then recorded (S2). Subsequently, it is determined on the basis of the recorded image, for example, whether the alignment laser beam passes through the exit opening 33 (S3). If the alignment laser beam passes through the exit opening 33 (Y1), the following further steps are carried out: Determination of a position of the alignment laser beam 21 emerging through the exit opening 33 and a position of the exit opening 33 of the nozzle 31 on the basis of the recorded image (S4), determination, Whether a deviation of the determined position of the alignment laser beam DC, DU from a predetermined position O of the alignment laser beam 21 is greater than a predetermined maximum deviation, the predetermined position of the alignment laser beam relative to the position of the exit opening being predetermined (S5). If the deviation is greater than the specified maximum deviation (Y2), the position of the adjustment laser beam 21 is adjusted relative to the exit opening 33 (S6).

The steps of taking an image, determining the position of the alignment laser beam and the position of the exit opening, determining the deviation and adjusting the position are carried out until it is determined that the deviation of the determined position of the alignment laser beam from the specified position of the alignment laser beam is less than or the same as the predetermined maximum deviation (N2). In this case, the process can be ended (S8).

If the alignment laser beam does not pass through the exit opening (NI), a reference cycle described below can be carried out (S7).

4A and 4B show a flowchart of a method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head according to an embodiment of the present invention and Machining a workpiece with a laser beam according to embodiments of the present invention was added.

According to embodiments of the present invention, the method is automatically, for example by the control device 60, after a change of the nozzle 31 on the laser processing head 30 or after a collision of the laser processing head 30 or the nozzle 31 with an object, for example a workpiece to be processed, started. Furthermore, the method can also be started manually by an operator via a specific interface (for example a GUI) to the control device 60.

At the beginning of the method, the cover 55 of the alignment unit 50 or the nozzle changer is opened automatically. The laser processing head 30 is supported by machine axes of the laser processing system 10 to the position at which the centering process is to take place. In other words, the laser processing head 30 is moved onto the alignment unit 50, so that the optical axis of the laser processing head 30 and the optical axis of the alignment unit 50 run essentially coaxially. Thus, the nozzle mouth 32 of the nozzle 31 mounted on the laser processing head 30 is completely in the field of view of the optical detection unit 51. This ensures that an image recorded by the optical detection unit 51 shows the nozzle mouth 32 or the outlet opening 33 completely.

The control device 60 activates the lighting by the lighting device 54 and sets the optimal lighting parameters (for example the brightness). The control device 60 also checks, e.g. by means of an evaluation algorithm, whether a nozzle mouth 32 and an inner contour 34 of the nozzle mouth 32 (see FIG. 5) can be detected. If not, the operator is informed with an error message. If the detection is successful, the nozzle status is checked (described below). If the nozzle status does not correspond to the defined criteria, for example due to a defective, dirty or incorrect nozzle, an automatic error message is issued and / or a nozzle change can be started automatically. The process then starts again automatically.

After the nozzle status has been successfully checked, a target focus position is first set and the adjustment laser beam 21 is then activated. This can correspond to step S1 in FIG. 3. The control device 60 then checks, for example by means of an evaluation algorithm, whether the alignment laser beam 21 can be detected by image processing, for example in step S2. The detection can take place in particular by image processing of an image or video recorded by the optical detection unit 51. This can correspond to step S3 in FIG. 3. If the alignment laser beam 21 is not detected, then the control device 60 automatically starts a so-called “reference cycle” as in step S7 in FIG. 3 (described below).

If, on the other hand, the alignment laser beam 21 is detected, the control device 60 determines, for example by means of image processing, the centroid S of the alignment laser beam 21 and the centroid O of the exit opening 32 (see Fig. 5) in the recorded image and calculates the relative deviations DC and DU in the two Directions x and y of the centroid S from the centroid O. This can correspond to step S4 in FIG. 3. If it is determined that both relative deviations are less than or equal to a predefined maximum deviation (AX <target-pm and AY <target-pm), then beam positioning is not necessary. This can correspond to step S5 in FIG. The laser processing head 30 can thus be moved back to a starting position and the cover 55 or the nozzle changer system can be closed. The procedure is over. This can correspond to step S8 in FIG. 3.

As shown in FIG. 5, according to embodiments, the diameter of the alignment laser beam 21 in a plane in the area of the exit opening 33 and thus also in the sensor plane of the optical detection unit 51 is smaller than a diameter, in particular a minimum diameter, of the exit opening 33 in this plane. In particular, the cross-sectional area of the alignment laser beam 21 in this plane is smaller than the area of the outlet opening 33 in this plane. The alignment laser beam 21 therefore does not completely illuminate the exit opening 33 according to embodiments. According to embodiments, the plane in the area of the outlet opening 32 comprises the nozzle mouth 32, in particular an end face of the nozzle mouth 32. In other words, the plane in the area of the outlet opening 32 can be coplanar with the end face of the nozzle mouth 32 and the outlet opening 33.

If, on the other hand, one or both of the relative deviations DC, DU is or are greater than the predefined maximum deviation, ie AX> target pm and AY> target pm (corresponding to Y2 in FIG. 3), then the adjustment unit 40 is activated to move or move the element, for example an optical cal element or an optical unit of the laser processing head. This can correspond to step S6 in FIG. 3. The deviations are then determined again by image processing. These steps are repeated until both relative deviations DC, DU are smaller than the predefined maximum deviation.

Image processing, also called “image analysis”, comprises the points image acquisition, image preprocessing, image segmentation, determination of the contours and the calculation of the relative deviations.

The imaging method according to the invention, comprising the recording of an image of the nozzle 31, the nozzle mouth 32 and the adjusting laser beam 21 passing through the outlet opening 33 and the subsequent image processing, enables an immediate spatially resolved measurement of the relative position of the adjusting laser beam 21 to the center or surfaces center of gravity of the outlet opening 33.

As soon as the inner contour 34 of the nozzle mouth 33 and the contour 23 of the alignment laser beam 21 have been determined by the image processing, the two centroids S and O is calculated (see Fig. 5). The relative deviations DC and DU along the two directions x and y, which can be output as corresponding control signals from the control device 60 to the adjustment unit 40, are calculated from the two centroids S and O.

To check the nozzle status, i.e. the nozzle inspection, at least one geometric or optical parameter, which is determined by the image processing, is compared with a target parameter. The focus here is on a possible deformation of the nozzle 31 and on its surface properties.

The geometric parameters include the form factor of the inner contour 34 of the nozzle mouth 32, the ellipticity of the inner contour 34 and the inner diameter of the nozzle 31, ie the diameter of the outlet opening 33. The form factor of the inner contour 34 is dependent on the determined area and the determined circumference of the Outlet opening 33.

In the case of the ellipticity, the ratio of a minor axis to a major axis of the outlet opening 33 is formed. The minor axis is defined as the distance from the center of gravity point O to a point P2 on the inner contour 34 of the nozzle mouth 33 (see Fig. 6). The main axis is defined as the distance from the centroid O to a point PI on the inner contour 34 of the nozzle mouth 33 (see FIG. 6). If this ratio falls below a certain value, then it is determined that the nozzle inspection was not successful or the nozzle state is not satisfactory. By definition, the ellipticity can assume a value range between 0 and 1, with the value 1 corresponding to a circle.

In the case of the parameter “inside diameter of the nozzle 31”, the setpoint value, which is stored in the evaluation unit in the control device 60, is compared with the determined actual value. The inner diameter of the nozzle 31 corresponds to a diameter of the outlet opening 33 and can be determined based on the inner contour 34 of the nozzle mouth 32 by means of image processing.

An optical parameter is, for example, the reflection behavior of the nozzle mouth 32. The reflection behavior can be determined from the gray values of the pixels, ie a relative light intensity, of the image recorded by the optical detection unit 51 (FIG. 7 above). If the actual gray value curve (FIG. 7 bottom left) does not correspond to the target gray value curve (FIG. 7 bottom right) along one direction, this can indicate damage or contamination 32a of the nozzle 31 or nozzle mouth 32. The geometrical and optical parameters described can be used in any constellation for nozzle inspection.

A reference cycle is required when the nozzle 31 shades the alignment laser beam 21 and the optical detection unit 51 cannot therefore detect the alignment laser beam 21. This can be the case, for example, with a small inside diameter of the nozzle 31 and / or an incorrect position or alignment of the alignment laser beam 21.

The reference cycle can include different movement patterns of the element moved by the adjustment unit 40, which lead to a specific movement pattern or movement path of the alignment laser 21 in the plane in the area of the outlet opening 33.

8 and 9 show exemplary movement patterns of the alignment laser 21 in the area of the exit opening 33. The exit opening 33 and the nozzle mouth 32 are shown in FIGS. 8 and 9 from a point inside the laser processing head 30 and show a position of the alignment laser 21 at the beginning of the reference cycle, in which the alignment laser 21 hits an inner surface of the nozzle 31 and thus does not pass through the outlet opening 33.

The reference cycle can include a defined meandering movement of the element moved by the adjustment unit 40 (see FIG. 8). This movement is carried out until the optical detection unit 51 detects the alignment laser beam 51. The reference cycle is then ended and the beam positioning is carried out. Another embodiment of the reference cycle describes a movement of the element moved by the adjusting unit 40 up to a limit switch (see FIG. 9). For this purpose, the element is first moved in a first direction, for example the x direction, up to the corresponding limit switch in this direction. If this is reached, the element is moved up to the limit switch in the second direction, for example the y-direction. From this position of the adjustment laser beam 21 or the element moved by the adjustment unit 40 at the respective limit switches in the x and y directions, it is now possible to use the adjustment laser beam 21 to move to a position which theoretically corresponds to the center of the nozzle 31 or the outlet opening 33 corresponds. The reference cycle is then ended and the beam positioning is carried out in this embodiment as well.

The method for automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and the laser processing system for processing a workpiece with a laser beam according to embodiments of the invention make it possible to use both an automated or automated and motorized beam positioning tion, in particular a beam centering with respect to the nozzle center, as well as an automated or automated and motorized nozzle inspection.

By providing a reference cycle for the movement of an alignment laser, the method and the laser processing system enable automated or automated beam positioning and automated or automated nozzle inspection even when the alignment laser is shaded by the nozzle mounted on the laser processing head.

The adjustment unit, which is mounted on or in the laser processing head or is formed integrally with the laser processing head, provides an integrated solution for beam positioning and nozzle inspection.

Furthermore, the optical detection unit or the alignment unit enables a direct, spatially resolved measurement of the position of the alignment laser relative to the center of the nozzle or the outlet opening and is therefore not based on an indirect measurement method, for example with the aid of acoustic or thermal sensors or photodiodes.

List of reference symbols

10 laser processing system

20 laser source

21 Alignment laser beam

22 optical fiber

22a fiber socket

23 Contour of the alignment laser beam

30 laser processing head

30a optical axis of the laser processing head

31 nozzle

32 nozzle mouth

32a damage or contamination

33 outlet opening

34 Inner contour of the nozzle mouth

35 collimation optics

36 focusing optics

40 adjustment unit

41 movement unit 42a, 42b actuator

50 alignment unit

51 optical detection unit

52 imaging optics

53 optical filter unit

54 lighting equipment

55 cover

56 Conversion

60 control device

Claims

1. A method for the automated beam positioning of a laser beam with respect to a nozzle (31) of a laser processing head (30), the method comprising the steps:

Directing an adjustment laser beam (21) coaxial to the laser beam onto an exit opening (33) of the nozzle (31) mounted on the laser processing head (30);

Recording an image of the outlet opening (33) and of a nozzle mouth (32) surrounding the outlet opening;

Determining whether the alignment laser beam (21) passes through the exit opening (33); and

Carry out the following steps if the alignment laser beam (21) passes through the outlet opening (33):

Determining a position of the alignment laser beam (21) passing through the exit opening (33) and a position of the exit opening (33) of the nozzle (31) based on the image recorded;

Determining whether a deviation of the determined position of the alignment laser beam (21) from a predetermined position of the alignment laser beam (21) is greater than a predetermined maximum deviation, the predetermined position of the alignment laser beam (21) being predetermined relative to the position of the exit opening (33); if the deviation is greater than the predetermined maximum deviation, Verstel len the position of the alignment laser beam (21) relative to the outlet opening (33); and

Repeating the steps of taking an image, determining the position of the adjustment laser beam (21) and the position of the outlet opening (33), determining the deviation and adjusting the position until the deviation of the determined position of the adjustment laser beam (21) from the predetermined position of the alignment laser beam (21) is less than or equal to the specified maximum deviation.

2. The method according to claim 1, wherein the adjustment of the position of the alignment laser beam (21) relative to the exit opening (33) an adjustment of the position of the alignment laser beam (21) with respect to the exit opening (33) and / or an adjustment of the position of the exit opening ( 33) with respect to the alignment laser beam (21).

3. The method according to any one of the preceding claims, wherein determining the positions comprises:

Determination of a centroid (O) of the outlet opening (33) as the predetermined position of the alignment laser beam (21) and / or determination of a centroid (S) of the alignment laser beam (21) as the position of the alignment laser beam (21).

4. The method according to claim 3, wherein the determination of the centroid (O) of the outlet opening (33) comprises determining an inner contour (34) of the nozzle mouth (32) by image analysis of the recorded image, and / or where the determination of the centroid (S) of the alignment laser beam (21) comprises determining a contour (24) of the alignment laser beam (21) by image analysis of the recorded image.

5. The method according to any one of the preceding claims, wherein a first deviation of the determined position of the adjustment laser beam (21) from the predetermined position of the adjustment laser beam (21) in a first direction (x) and a second deviation of the determined position of the adjustment laser beam (21) from the predetermined position of the alignment laser beam (21) is determined in a second direction, the first and the second direction (y) being perpendicular to one another; wherein the predetermined maximum deviation comprises a first predetermined maximum deviation along the first direction (x) and a second predetermined maximum deviation along the second direction (y), and wherein it is determined that the deviation is greater than the predetermined maximum deviation, if the first deviation of the determined position of the adjustment laser beam (21) from the predetermined position of the adjustment laser beam (21) in the first direction (x) is greater than the first predetermined maximum deviation and / or if the second deviation of the determined position of the adjustment laser beam (21) from the predetermined position of the adjustment laser beam (21) in the second direction (y) is greater than the second predetermined maximum deviation.

6. The method according to any one of the preceding claims, wherein the recording of the image is carried out by an optical detection unit (51), and wherein the method further comprises: moving the laser processing head (30) relative to the optical detection unit (51) so that the nozzle mouth (32) the nozzle mounted on the Laserbear processing head (30) lies completely in the field of view of the optical detection unit (51).

7. The method according to any one of the preceding claims, further comprising the steps:

Using at least one recorded image, determining whether a nozzle state condition is met, and if the nozzle state condition is not met, outputting an error.

8. The method of claim 7, wherein to determine whether the nozzle state condition is met, comprises the steps of:

Determining a value of a nozzle state parameter on the basis of the recorded image, and

Comparing the determined value with at least one predetermined value for the nozzle state parameter, the nozzle state parameter comprising a geometric nozzle state parameter which includes an inner contour (34) of the nozzle mouth (32), an ellipticity of the inner contour (34) of the nozzle mouth (32), a diameter of the inner contour (34) of the nozzle mouth (32) and / or a form factor of the inner contour (34) of the nozzle mouth (32), and / or wherein the nozzle state parameter comprises an optical nozzle state parameter which comprises a reflectivity of the nozzle mouth (32).

9. The method according to any one of the preceding claims, wherein for adjusting the position of the alignment laser beam (21) relative to the outlet opening (33) at least one of the following elements in a plane (xy) perpendicular to the optical axis of the Laserbearbei processing head (30) is moved: at least an optical element arranged in the beam path of the laser processing head (30), at least part of a focusing optics of the laser processing head (30), at least part of a collimation optics of the laser processing head (30), a fiber end of the alignment laser beam (21) and / or the laser beam Optical fiber (22) feeding the laser processing head (30), a fiber socket for coupling an optical fiber (22) which carries the alignment laser beam (21) and / or the laser beam to the laser processing head (30), and the nozzle (31).

10. The method according to any one of the preceding claims, further comprising the step: if the alignment laser beam (21) does not pass through the exit opening (33), repeat the following steps until the alignment laser beam (31) passes through the exit opening (33) : Adjusting the position of the alignment laser beam (21) relative to the exit opening (33) along a predetermined path and determining whether the alignment laser beam (21) passes through the exit opening (33).

11. The method according to any one of the preceding claims, wherein a diameter of the alignment laser beam is smaller than a diameter of the exit opening, and / or wherein a cross-sectional area of the alignment laser beam is smaller than an area of the exit opening.

12. Laser processing system (10) for processing a workpiece with a laser beam, the laser processing system (10) comprising: a laser source (20) which is set up to generate the laser beam and an alignment laser beam (21) coaxial with the laser beam, a laser processing head (30) ) with a nozzle (31), the nozzle (31) comprising an exit opening (33) for the exit of the laser beam or the adjustment laser beam (21) from the laser processing head (30) and a nozzle mouth (32) surrounding the exit opening (33), and with an adjustment unit (40) for adjusting the position of the alignment laser beam (21) relative to the outlet opening (33); an alignment unit (50) with an optical detection unit (51), the optical detection unit (51) being set up to record an image of the outlet opening (33) as well as of the nozzle mouth (32); and a control device (60) configured to: determine whether the alignment laser beam (21) passes through the exit opening (33); to determine a position of the alignment laser beam (21) passing through the exit opening (33) and a position of the exit opening (33) on the basis of the recorded image; to determine a deviation of the determined position of the alignment laser beam (21) from a given position of the alignment laser beam (21), the predetermined posi tion of the alignment laser beam (21) relative to the position of the outlet opening (33) is specified; and by controlling the adjustment unit (40) to adjust the position of the adjustment laser beam (21) relative to the outlet opening (33),.

13. Laser processing system (10) according to claim 12, wherein the adjustment unit (40) comprises: at least one movement unit (41) which is arranged on or in the laser processing head (30) and is set up to move at least one of the following elements in a plane (x- y) perpendicular to the optical axis of the laser processing head (30) to move: at least one optical element arranged in the beam path of the laser processing head, at least part of a focusing optics of the laser processing head, at least a part of a collimation optics of the laser processing head, a fiber end of the alignment laser beam and / or the optical fiber feeding the laser beam to the laser machining head, a fiber socket for coupling an optical fiber guiding the alignment laser beam and / or the laser beam to the laser machining head, and the nozzle.

14. The laser processing system (10) according to claim 13, wherein the movement unit comprises: at least one actuator (42a, 42b) which is mounted on the laser processing head (30) and is configured to provide a rotational movement, and at least one mechanical unit which is configured to provide the rotational movement provided by the at least one actuator (42a, 42b) to be converted into a translational movement in order to move the element in at least one direction along the plane perpendicular to the optical axis to (xy).

15. Laser processing system (10) according to one of claims 12 to 14, wherein the optical axis of the optical detection unit (51) and the optical axis of the laser processing head (30) run parallel to one another or coaxially.

16. The laser processing system (10) according to any one of claims 12 to 15, wherein the alignment unit (50) further comprises: a cover (55) which can be remotely opened and closed; and / or - a lighting device (54) which is set up to illuminate the nozzle mouth (32); and / or imaging optics (52) which are set up to image the nozzle mouth (32) and the alignment laser beam (21) onto the optical detection unit (51), and / or an optical filter unit (53) which are set up to a To let the wavelength of the alignment laser beam (21) pass.