DE102020100217A1 - 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 - Google Patents

Abstract

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 automatically performed steps: directing an alignment laser beam coaxial to the laser beam onto an exit opening of the nozzle mounted on the laser processing head; and determining whether the alignment laser beam passes through the exit aperture; and if the alignment laser beam passes through the exit opening: recording a two-dimensional image of the exit opening and the alignment laser beam emerging through the exit opening as well as of a nozzle mouth surrounding the exit opening; Determining a position of the alignment laser beam 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 predefined position of the alignment laser beam is greater than a predefined maximum deviation; if the deviation is greater than the predetermined maximum deviation, adjusting the relative position of the alignment laser beam and the exit opening; and repeating the steps of taking a two-dimensional 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. Furthermore, a laser processing system for processing a workpiece with a laser beam is specified.

Description

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 laser processing system for processing a workpiece, in particular a metallic workpiece, with a laser beam which 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 focusing optics Workpiece locally heated to melting temperature. The processing can include, for example, laser cutting, soldering or welding. The laser processing system can include 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 processing process, it is important for most applications that the laser beam emerges from the laser processing head in a centered manner. In particular, the laser beam should be aligned centrally or centered with respect to an exit opening of the laser processing head through which the laser beam exits 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 every 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 the like. 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, e.g. in the case of an oval outlet opening a jet position offset along the long axis to the center 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 focusing 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, wherein a nozzle is adjusted relative to the laser beam. DE 10 2004 005 902 B3 describes a device for adjusting a laser beam in a laser processing machine, an alignment unit equipped with an evaluation unit with a cutting nozzle fixing element being provided for adjusting the laser beam. WO 2019/009833 A2 describes a centering device for a laser beam of a laser cutting machine, 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 automated beam positioning of a laser beam with respect to a nozzle of a laser processing head and a Specify laser processing system for processing a workpiece with a laser beam, which allow a fast, precise and simple positioning of the laser beam with respect to the nozzle, in particular a beam centering, as well as a check of the nozzle state. 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.

Another object of the present disclosure is 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 of the state enable the nozzle.

These objects are achieved by the subject matter of the independent claims. Advantageous refinements of the invention are the subject matter of the 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 (preferably automated) steps: directing an alignment laser beam coaxial to the laser beam onto an exit opening of a nozzle mounted on the laser processing head; 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 exit opening: determining a position of the alignment laser beam passing through the exit opening and a position of the exit 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 predefined position of the alignment laser beam is greater than a predefined maximum deviation; if the deviation is greater than the predetermined 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 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 alignment 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 to generate the laser beam and an alignment laser beam, a laser processing head with a nozzle, the nozzle having 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 capture an image of the exit opening as well as from the nozzle mouth; a control device which is set up to determine a position of the alignment laser beam and a position of the outlet opening of the nozzle based on the recorded image, to determine a deviation of the ascertained position of the alignment laser beam emerging through the outlet opening from a predetermined position of the alignment laser beam, and by controlling 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 less than or is the same as 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 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 exit 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 condition 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 done manually an operator of the laser processing system can be started. Furthermore, all steps of the method can be carried out in an automated and / or remote-controlled manner. 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 each automated adjustment of the relative position of the alignment 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 alignment laser beam and the position of the exit opening can correspond to a position of the center or the midpoint, in particular of the centroid, of the alignment laser beam and the exit 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 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 alignment 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 alignment 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 at an end of the nozzle facing the workpiece to be processed by the laser processing head.

The predefined position of the alignment laser beam can be predefined relative to the position of the exit opening. The predefined position of the adjustment laser beam can correspond to a center or a midpoint of the exit opening or can correspond to a predefined offset from the center or midpoint of the exit 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 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 outlet opening can in particular be determined as the predefined position of the adjusting laser beam for beam centering. The positions and / or the centers of area can be indicated in the image plane described above, for example in the area of the outlet opening or the nozzle mouth. The determination of the positions and the determination of the centroids 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 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 ascertained position of the alignment laser beam from the predetermined position of the alignment laser beam can correspond to a distance between the ascertained 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 in a second Embrace direction. The first direction and the second direction can be perpendicular to one another and run 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 point 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 include 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 deviation 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 exit opening can be adjusted. If the deviation is equal to or smaller than the predefined maximum deviation, the method can be ended. The recording of a two-dimensional image, the determination of the positions of the alignment laser beam and the exit opening, the determination of the deviation and the adjustment of the relative position are 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 than the specified maximum deviation.

The image can be recorded by the optical detection unit. The optical detection unit is arranged outside the laser processing head or separately therefrom. 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 lie 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 include determining, using 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 predefined 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 carrying 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 alignment 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 can be necessary in particular if the nozzle or the nozzle mouth shadows the alignment laser beam so that the optical detection unit cannot detect or record the alignment laser beam. 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 exit 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 laser 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 that can be remotely opened and closed; a lighting device configured to illuminate the nozzle mouth; an imaging optical system that is set up to image the nozzle mouth and the alignment laser beam onto 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 detect a wavelength of the alignment laser beam and a To let the wavelength of the lighting device pass. The imaging optics can include 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 enables optimal contrast for recording 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 configured to control the movement unit in order to move the laser processing head to the alignment unit and to align it such that the optical axis of the optical detection unit is essentially coaxial with an optical axis of the laser processing head.

Figure list

• 1 eine schematische Darstellung eines Laserbearbeitungssystems zum Bearbeiten eines Werkstücks mit einem Laserstrahl gemäß einer Ausführungsform der vorliegenden Erfindung;
• 2 eine schematische Darstellung eines Laserbearbeitungssystems zum Bearbeiten eines Werkstücks mit einem Laserstrahl gemäß Ausführungsformen der vorliegenden Erfindung;
• 3 zeigt ein Flussdiagramm eines Verfahrens zur automatisierten Strahlpositionierung eines Laserstrahls bezüglich einer Düse eines Laserbearbeitungskopfes gemäß Ausführungsformen der vorliegenden Erfindung;
• 4A und B ein Flussdiagramm eines Verfahrens zur automatisierten Strahlpositionierung eines Laserstrahls bezüglich einer Düse eines Laserbearbeitungskopfes gemäß einer Ausführungsform der vorliegenden Erfindung;
• 5 eine schematische und beispielhafte Darstellung eines Bildes, das von einer optischen Erfassungseinheit eines Laserbearbeitungssystems zum Bearbeiten eines Werkstücks mit einem Laserstrahl gemäß Ausführungsformen der vorliegenden Erfindung aufgenommenen wurde;
• 6 eine schematische Darstellung einer Innenkontur eines Düsenmundes gemäß Ausführungsformen der vorliegenden Erfindung;
• 7 im oberen Teil eine schematische Darstellung einer Düse eines Laserbearbeitungskopfes gemäß einer Ausführungsform der vorliegenden Erfindung und im unteren Teil einen beispielhaften Grauwertverlauf der Düse;
• 8 und 9 schematische Darstellungen von Bewegungen eines Laserstrahls entlang eines vorgegebenen Pfades gemäß Ausführungsformen der vorliegenden Erfindung.

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

• 1 a schematic representation of a laser processing system for processing a workpiece with a laser beam according to an embodiment of the present invention;
• 2 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 flowchart 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 shows 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 a schematic and exemplary representation 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;
• 6th a schematic representation of an inner contour of a nozzle mouth according to embodiments of the present invention;
• 7th 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;
• 8th 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 symbols are used below for elements that are identical and have the same effect.

1 shows a schematic representation of a laser processing system for processing a workpiece with a laser beam according to an embodiment of the present invention. 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 machining 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. Besides, the laser processing system is 10 preferably set up to carry out an automated nozzle inspection.

The laser processing system 10 includes a laser source 20th , a laser processing head 30th , an adjustment unit 40 , an alignment unit 50 and a control device 60 . The laser source 20th is set up, the laser beam and an alignment laser beam 21 , also called “pilot laser” or “pilot laser beam”. The laser beam or the alignment laser beam 21 are via an optical fiber 22nd and a fiber socket 22a coupled into the laser processing head. The alignment laser beam 21 runs coaxial to the laser beam. This allows the positioning of the alignment laser beam 21 the laser beam can also be adjusted. 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 be used, for example with a lower power than for material processing.

The laser processing head 30th has a nozzle 31 on. The nozzle 31 which may be a nozzle electrode, comprises a nozzle mouth 32 and an exit port 33 for the exit of the laser beam and the alignment laser beam from the laser processing head 30th . The nozzle 31 can be integral with the laser processing head 30th be connected, or can be on the laser processing head 30th be movably mounted. The laser processing head 30th can comprise several 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 that at least partially reflect the laser beam and the alignment laser beam. As in 1 shown has the laser processing head 30th a collimation optics 35 and focusing optics 36 on. The collimation optics 35 and / or the focusing optics 36 can along an optical axis z of the laser processing head 30th that are coaxial to a beam propagation direction of the alignment laser beam 21 can run, be shifted to a focus position of the alignment laser beam 21 or the laser beam.

The alignment unit 50 comprises an optical detection unit 51 that is set up to take a two-dimensional image of the outlet opening 33 and the alignment laser beam passing through the exit opening 21 as well as from the nozzle mouth 32 to record. The control device 60 is set up to use the recorded image to determine a position of the alignment laser beam 21 and a position of the exit port 33 the nozzle 31 to determine a deviation of the determined position of the alignment laser beam 21 from a predetermined position of the alignment laser beam 21 to be determined, and by controlling the adjustment unit 40 the position of the alignment laser beam 31 relative to the position of the outlet opening 33 to be adjusted if the deviation is greater than a specified maximum deviation.

The adjustment unit 40 is set up, the position of the alignment laser beam 31 relative to the position of the outlet opening 33 to adjust. The adjustment unit 40 can be in or on the laser processing head 30th be arranged or mounted. The adjustment unit 40 can also be used in the laser processing head 30th be integrated.

The adjustment unit comprises one on or in the laser processing head 30th arranged movement unit 41 . The movement unit 41 is set up, an element, in particular an optical element or an optical unit, in a plane perpendicular to the optical axis z of the laser processing head 30th to move, move or position. Moving the element has the consequence that the position of the alignment laser beam 21 relative to the position of the outlet opening 33 or the position of the outlet opening 33 relative to the position of the alignment laser 21 is adjusted in a plane in the area of the exit opening, which is arranged perpendicular to the optical axis.

In 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 each other. Moving the element or the optical unit can thus include moving the element along the x-direction and along the y-direction.

According to the embodiments shown, the movement unit is 41 set up at least part of the focusing optics 36 to move. The focusing optics 36 may comprise a focusing lens and / or a focusing lens package. According to other embodiments, the movement unit 41 be set up, at least a part of a collimation optics of the laser processing head 30th , one fiber end of the alignment laser beam 21 and / or the laser beam to the laser processing head 30th feeding optical fiber 22nd , a fiber socket 22a for coupling the alignment laser beam 21 and / or the optical fiber guiding the laser beam 22nd on the laser processing head 30th 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, for example a three-phase, linear, step or alternating current motor. According to the in 1 The embodiment shown comprises the movement unit 41 an actuator. According to the in 2 The embodiment shown comprises the movement unit 41 two actuators 42a , 42b . According to the embodiments shown, the at least one actuator is on the laser processing head 30th appropriate. As in 2 the actuators can be shown 42a , 42b in the laser processing head 30th be integrated.

The at least one actuator is set up to provide a rotary movement, in particular via a shaft or axis. According to the in 2 The embodiment shown comprises the movement unit 41 a first actuator 42a with a rotational movement R1 and a second actuator 42b with a rotational movement R2, the rotational movements R1 and R2 being independent of one another. In other words, the actuators 42a , 42b can be controlled independently of each other. The movement unit preferably comprises 41 two stepper motors as actuators, with 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 translational movement in the xy plane perpendicular to the direction of beam propagation z. As in 2 shown is the mechanical unit set up by the first actuator 42a provided rotational movement R1 into a translational movement of the element along the x-direction and that of the second actuator 42b to convert provided rotational movement R2 into a translational movement along the y-direction. This allows the element, here the focusing optics 36 , are moved independently of each other 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 for example comprise 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 further includes imaging optics 52 , also called "lens". The imaging optics 52 forms both the alignment laser beam 21 as well as the nozzle mouth 32 that is, some area of the bottom of the nozzle 31 , onto the optical detection unit 51 from, in particular on a sensor surface or sensor plane of the optical detection unit 51 . According to embodiments of the present invention, at least objects with a size of 5 mm × 5 mm can be detected. Objects up to a size of 10 mm × 10 mm are preferably detected. The imaging optics 52 may include a prime lens or a zoom lens. According to the invention, a fixed focal length lens is preferably used.

The alignment unit 50 can also have 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 the wavelength of the alignment laser beam 21 and the wavelength range of the lighting device 54 transmit. The lighting device 54 serves for optimal illumination of the nozzle mouth 32 in different environmental 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. There is also side lighting for the nozzle 31 possible.

The alignment unit also includes 50 a cover 55 that can be opened and closed automatically or remotely. An enclosure 56 , also known as the "housing", protects the elements of the alignment unit contained therein 50 , such as the optical detection 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 is 50 Intended as an independent station in the laser processing system, or integrated into a nozzle changer system.

The control device 60 , also referred to as “evaluation unit”, is set up, the optical detection unit 51 , the alignment unit 50 , the laser source 20th and / or the adjustment unit 40 to control. According to embodiments of the invention, the control device is used 60 as a communication interface between these elements.

According to one embodiment of the present invention, the control device communicates 60 inter alia with a higher-level control, for example a so-called “CNC” or a machine control (not shown). The main task of the control device 60 lies in the control and information signals between the adjustment unit 40 and the optical detection unit 51 or the alignment unit 50 to process and transmit. 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 procedure.

According to a further embodiment of the present invention, the control device unites 60 the tasks for machine control and for automated beam positioning of the laser beam according to embodiments of the present invention. The control device communicates 60 both with the laser source 20th , 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 takes over 60 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 .

3 shows 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 embodiments of the present invention. The method comprises the following, preferably automated, steps.

After the start (S0), an alignment laser beam coaxial with the laser beam is generated 21 to an outlet opening 33 one on the laser processing head 30th mounted nozzle 31 directed (S1). Then a picture is taken of the exit opening 33 as well as from a nozzle mouth surrounding the outlet opening 32 recorded (S2). It is then determined, for example on the basis of the recorded image, whether the alignment laser beam is through the exit opening 33 occurs (S3).

If the alignment laser beam passes through the exit opening 33 occurs (Y1), the following further steps are carried out: Determining a position of the through the outlet opening 33 emerging alignment laser beam 21 and a position of the outlet opening 33 the nozzle 31 on the basis of the recorded image (S4), determining whether there is a discrepancy between the determined position of the alignment laser beam .DELTA.X, .DELTA.Y from a predetermined position O of the alignment laser beam 21 is greater than a specified maximum deviation, the specified position of the alignment laser beam being specified relative to the position of the outlet opening (S5). If the deviation is greater than the specified maximum deviation (Y2), the position of the alignment laser beam becomes 21 relative to the outlet opening 33 adjusted (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 predetermined position of the alignment laser beam is less than or is the same as the specified maximum deviation (N2). In this case, the process can be ended (S8).

If the alignment laser beam does not pass through the exit opening (N1), 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 5 is a schematic, exemplary representation of an image that is generated by an optical detection unit 51 a laser machining system for machining a workpiece with a laser beam according to embodiments of the present invention.

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

At the beginning of the procedure is the cover 55 the alignment unit 50 or the nozzle changer opens automatically. The laser processing head 30th is made by machine axes of the laser processing system 10 Move to the position at which the centering process is to take place. In other words, it becomes the laser processing head 30th on the alignment unit 50 move so that the optical axis of the laser processing head 30th and the optical axis of the alignment unit 50 run essentially coaxially. Thus is the nozzle mouth 32 the one on the laser processing head 30th mounted nozzle 31 completely in the field of view of the optical detection unit 51 . This can ensure that one of the optical detection unit 51 recorded image the nozzle mouth 32 or the outlet opening 33 shows completely.

The control device 60 activates the lighting through the lighting device 54 and sets the optimal lighting parameters (e.g. brightness). The control device 60 also checks, for example by means of an evaluation algorithm, whether a nozzle mouth 32 and an inner contour 34 of the nozzle mouth 32 (please refer 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 then the alignment laser beam is activated. This can be done in step S1 3 correspond. 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 in particular by image processing of one of the optical detection unit 51 recorded image or video. This can be done in step S3 3 correspond. When the alignment laser beam 21 is not detected, the control device starts 60 automatically a so-called "reference cycle" as in step S7 in 3 (described below).

If, however, the alignment laser beam 21 detected, the control device determines 60 , for example, the center of gravity S of the alignment laser beam by means of image processing 21 and the centroid O of the outlet opening 32 (please refer 5 ) in the recorded image and calculates the relative deviations ΔX and ΔY in the two directions x and y of the centroid S from the centroid O. This can be done in step S4 in 3 correspond. If it is determined that both relative deviations are less than or equal to a predefined maximum deviation (ΔX <target µm and ΔY <target µm), then beam positioning is not required. This can be done in step S5 3 correspond. Thus, the laser processing head 30th 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 be done in step S8 3 correspond.

If, on the other hand, one or both of the relative deviations ΔX, ΔY is or are greater than the predefined maximum deviation, ie ΔX> target µm and ΔY> target µm, (corresponding to Y2 in 3 ), then the adjustment unit 40 controlled in order to move or move the element, for example an optical element or an optical unit of the laser processing head. This can be done in step S6 3 correspond. The deviations are then determined again by image processing. These steps are repeated until both relative deviations ΔX, ΔY 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 of the invention comprising taking an image of the nozzle 31 , the nozzle mouth 32 and that through the outlet opening 33 stepping alignment laser beam 21 and the subsequent image processing enables immediate, spatially resolved measurement of the relative position of the alignment laser beam 21 to the center or center of gravity of the outlet opening 33 .

Once the inside contour 34 of the nozzle mouth 33 and the contour 23 of the alignment laser beam 21 were determined by the image processing, the two centroids S and O are calculated (cf. 5 ). The relative deviations .DELTA.X and .DELTA.Y along the two directions x and y are calculated from the two centroids S and O, and are used as corresponding control signals by the control device 60 to the adjustment unit 40 can be issued.

To check the nozzle state, ie 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 geometrical parameters include the form factor of the inner contour 34 of the nozzle mouth 32 , the ellipticity of the inner contour 34 and the inside diameter of the nozzle 31 , ie the diameter of the outlet opening 33 . The form factor of the inner contour 34 depends on the determined area and the determined circumference of the outlet opening 33 .

The ellipticity is the ratio of a minor axis to a major axis of the outlet opening 33 educated. The minor axis is defined as the distance from the centroid O to a point P2 on the inner contour 34 of the nozzle mouth 33 (please refer 6th ). The main axis is defined as the distance from the centroid O to a point P1 on the inner contour 34 of the nozzle mouth 33 (please refer 6th ). If this ratio falls below a certain value, it is determined that the nozzle inspection was unsuccessful or that the nozzle state is unsatisfactory. By definition, the ellipticity can assume a value range between 0 and 1, with the value 1 corresponding to a circle.

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

An optical parameter is, for example, the reflection behavior of the nozzle mouth 32 . The The reflection behavior can be determined by the gray values of the pixels, ie a relative light intensity of the optical detection unit 51 captured image ( 7th above) can be determined. Corresponds to the actual gray value curve ( 7th bottom left) along one direction not the target gray value curve ( 7th below right), this may indicate damage or contamination 32a the nozzle 31 or nozzle mouth 32 indicate.

The geometrical and optical parameters described can be used in any constellation for nozzle inspection.

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

The reference cycle can have different movement patterns created by the adjustment unit 40 include moving element that 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 leads.

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

The reference cycle can be a defined meandering movement by the adjustment unit 40 moving element (see 8th ). This movement is carried out until the optical detection unit 51 the alignment laser beam 51 detected. The reference cycle is then ended and the beam positioning is carried out. Another embodiment of the reference cycle describes a movement of the by the adjustment unit 40 moving element up to a limit switch (see 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 alignment laser beam 21 or by the adjustment unit 40 moving element at the respective limit switches in the x- and y-direction, it is now possible with the adjustment laser beam 21 move to a position that is theoretically the center of the nozzle 31 or the outlet opening 33 corresponds to. In this embodiment too, the reference cycle is then ended and the beam positioning is carried out.

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 carry out both automated or automated and motorized beam positioning, in particular beam centering with respect to the center of the nozzle, as well as to carry out 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

20th

Laser source

21

Alignment laser beam

22nd

Optical fiber

22a

Fiber bushing

23

Contour of the alignment laser beam

30th

Laser processing head

30a

optical axis of the laser processing head

31

jet

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

Motion unit

42a, 42b

Actuator

50

Alignment unit

51

optical detection unit

52

Imaging optics

53

optical filter unit

54

Lighting device

55

cover

56

Enclosure

60

Control device

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 1967316 A1 [0005]
• DE 102004005902 B3 [0005]
• WO 2019/009833 A2 [0005]

Claims (15)

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 exit 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) on the basis of the recorded image; - 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) relative to the position of the exit opening (33) being predetermined ; - If the deviation is greater than the predetermined maximum deviation, adjusting the position of the adjustment laser beam (21) relative to the outlet opening (33); and - Repeating the steps of taking an image, determining the position of the alignment 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 alignment laser beam (21) from the predetermined position of the Adjusting laser beam (21) is less than or equal to the specified maximum deviation. Procedure 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) includes. Method according to one of the preceding claims, wherein determining the positions comprises: - Determining a centroid (O) of the outlet opening (33) as the predetermined position of the adjusting laser beam (21) and / or determining a centroid (S) of the adjusting laser beam (21) as the position of the adjusting laser beam (21). Procedure 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 wherein the determination of the centroid (S) of the alignment laser beam (21) comprises Comprises determining a contour (24) of the alignment laser beam (21) by image analysis of the recorded image. Method according to 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 adjustment laser beam (21) in a second direction is determined, the first and second directions (y) being perpendicular to each other; 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 alignment laser beam (21) from the predetermined position of the alignment 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 adjusting laser beam (21) from the predetermined position of the adjusting laser beam (21) in the second direction (y) is greater than the second predetermined maximum deviation. Method according to 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) is the Laser processing head (30) mounted nozzle lies completely in the field of view of the optical detection unit (51). Method according to one of the preceding claims, further comprising the steps: - Using at least one recorded image to determine whether a nozzle state condition is met, and - if the nozzle state condition is not met, an error is output. Procedure according to Claim 7 , wherein for determining 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 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). Method according to one of the preceding claims, wherein at least one of the following elements is moved in a plane (xy) perpendicular to the optical axis of the laser processing head (30) to adjust the position of the alignment laser beam (21) relative to the exit opening (33): at least one in the beam path of the laser processing head (30) arranged optical element, 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 a laser beam (21) and / or the laser beam feeding the laser processing head (30) Optical fiber (22), a fiber socket for coupling an optical fiber (22) guiding the alignment laser beam (21) and / or the laser beam to the laser processing head (30), and the nozzle (31). Method according to 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): Adjustment of 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). 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) having 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 surrounding the exit opening (33) ( 32), and with an adjusting 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) and of the nozzle mouth (32); and - a control device (60) which is set up: - 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 predetermined position of the alignment laser beam (21), the predetermined position of the alignment laser beam (21) being predetermined relative to the position of the outlet opening (33); and - To adjust the position of the adjustment laser beam (21) relative to the outlet opening (33) by controlling the adjustment unit (40),. Laser processing system (10) according to Claim 11 , wherein the adjustment unit (40) comprises: - at least one movement unit (41) arranged on or in the laser processing head (30), which is set up to move at least one of the following elements in a plane (xy) 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 part of a collimation optics of the laser processing head, a fiber end of an optical fiber that feeds the alignment laser beam and / or the laser beam to the laser processing head, a fiber socket for coupling a Alignment laser beam and / or the optical fiber guiding the laser beam on the laser processing head, and the nozzle. Laser processing system (10) according to Claim 12 , wherein the movement unit comprises: - at least one actuator (42a, 42b) which is mounted on the laser processing head (30), and is set up to provide a rotational movement, and - at least one mechanical unit, which is set up by the at least one To convert the rotary movement provided to the actuator (42a, 42b) 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). Laser processing system (10) according to one of the Claims 11 to 13th 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. Laser processing system (10) according to one of the Claims 11 to 14th 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 arranged 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 allow a wavelength of the alignment laser beam (21) to pass.

Images