WO2025088106A1 - Method for determining the welding depth in a laser welding process - Google Patents
Method for determining the welding depth in a laser welding process Download PDFInfo
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- WO2025088106A1 WO2025088106A1 PCT/EP2024/080208 EP2024080208W WO2025088106A1 WO 2025088106 A1 WO2025088106 A1 WO 2025088106A1 EP 2024080208 W EP2024080208 W EP 2024080208W WO 2025088106 A1 WO2025088106 A1 WO 2025088106A1
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- depth
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- height
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/03—Observing, e.g. monitoring, the workpiece
- B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/0209—Low-coherence interferometers
- G01B9/02091—Tomographic interferometers, e.g. based on optical coherence
Definitions
- the invention relates to a method for determining the welding depth in a laser welding process using an optical coherence tomograph.
- measuring the penetration depth is essential to ensure a high-quality weld. If the penetration depth is insufficient, the weld will not have the required strength. If the penetration depth is too great, however, penetration can occur. Therefore, various methods have already been proposed for measuring the penetration depth in laser welding processes.
- the measuring beam When using an optical coherence tomography system to measure the penetration depth, setting the correct measurement position of the measuring beam is essential.
- the measuring beam must be positioned at the deepest point of the vapor capillary created by the processing laser beam in the component to reliably measure the penetration depth. Since the deepest position of the vapor capillary can change depending on the process parameters, a setup process must be performed before the laser welding process to determine the measurement position for the measuring beam.
- the existing setup processes are complex and require a second measurement step to determine the penetration depth.
- the measuring position of the measuring beam for welding depth measurement is determined by performing several scans with the measuring beam in the feed direction of the processing laser beam and transversely to it in order to create a height profile of the component in the area of the vapor capillary generated by the processing laser beam using an optical coherence tomograph.
- the lateral position of the lowest point of the vapor capillary can be determined from the height profile.
- the measuring beam is then directed to the lowest point of the vapor capillary, and the actual measurement of the penetration depth is performed.
- a similar method for determining the measuring position of a measuring beam is also known from DE 10 2019 103 734 A1.
- DE 10 2016 005021 A1 describes a method for measuring the welding depth during a laser processing process by directing the measuring beam to the lowest point of a vapor capillary and carrying out measurements of the depth of the lowest point at several different times from the data of these different measurements when the height position of the component surface is known.
- the invention is based on the object of proposing a more efficient method for measuring the welding depth in laser processing processes.
- all parameters necessary for determining the welding depth are recorded from the measurement data of the multiple temporally and spatially spaced scans with the measuring beam. From this measurement data and the resulting height profile of the component in the area of the vapor capillary, the height of the component surface, the lateral position of the lowest point of the vapor capillary, and the depth of the vapor capillary at this point can be determined. The welding depth can then be calculated from this depth and the height of the component surface.
- two separate measurements do not have to be carried out here: a first measurement to determine the lateral position of the lowest point of the vapor capillary and, in a second measurement, after directing the measuring beam onto the lowest point of the vapor capillary, to determine the depth of the vapor capillary at this point.
- the line scans with the measuring beam can preferably be performed in the feed direction of the processing laser beam and/or perpendicular to it. This allows the entire area of the vapor capillary as well as the component surface not melted by the processing laser beam to be captured with the scans.
- the measurement data of several or all scans carried out with the measuring beam are superimposed and a height profile of the component in the area of the vapor capillary is created by forming a moving intensity-weighted average from the measurement data and the lateral position of the lowest point of the vapor capillary is determined.
- the measurement data of several or all scans performed with the measuring beam can be superimposed and, by forming a moving intensity-weighted average from the measurement data, a height profile of the component in the area of the vapor capillary can be created and the height of the component surface can be determined.
- the height of the component surface and/or the lateral position of the lowest point of the vapor capillary can be determined with sufficient accuracy.
- the measurement of the depth of the vapor capillary at its lowest point can also be read from the height profile.
- a higher accuracy of the depth measurement of the vapor capillary can be achieved if the measurement data generated by the scans with the measuring beam in the area of the deepest point of the vapor capillary are filtered using a percentile filter with a sliding temporal process window or by means of a histogram evaluation in order to determine the depth of the vapor capillary at its deepest point and from this the welding depth.
- a statistically significant histogram class in particular the one with the most measurement points below the height position of the component surface, can directly indicate the welding depth.
- the method according to the invention can be carried out for setting up a laser processing machine before a production process and/or continuously or at time intervals during the production process.
- the method is only used to set up a production process, the average welding depth is already known during setup. Subsequently, for continuous control of the welding depth after the procedure has been carried out, To set up a laser processing machine, the measuring beam is directed at the lateral position of the lowest point of the vapor capillary and the depth of the vapor capillary is continuously measured at its deepest point and the welding depth is calculated from this. In this case, the method is only used for the efficient setup of the laser processing machine before the production process. Subsequently, a continuous measurement of the welding depth is carried out by holding the measuring beam at the measuring position determined during setup of the laser processing machine above the deepest point of the vapor capillary.
- the method according to the invention is preferably carried out again during the production process, either continuously or at temporal or spatial intervals, in order to compensate for any shifts in the deepest point of the vapor capillary and still be able to correctly determine the welding depth. This is particularly important for continuous welding processes such as pipe welding.
- Fig. 1 shows a cross-section through a component in the region of a vapor capillary generated by a processing laser beam
- Fig. 2 shows a distribution of measurement data from several OCT scans over the area of the vapor capillary of the component from Fig. 1 ;
- Fig. 3a, 3b shows the creation of a height profile of two vapor capillaries from measurement data of several OCT scans;
- Fig. 4a, 4b shows histogram evaluations of measurement data of the depth of two vapor capillaries.
- Fig. 1 illustrates the production of a weld seam 14 in a component 10.
- the component 10 is irradiated by a processing laser beam 11.
- the processing laser beam 11 creates a vapor capillary 12 in the component 10, in which the material of the component 10 is in a gaseous or plasma state.
- the processing laser beam 11 moves in the x direction across the component 10. Therefore, a molten pool 13 forms behind the vapor capillary, in which the previously gaseous material of the component 10 has already transformed into a liquid state due to cooling in the vapor capillary 12. Further away from the vapor capillary 12, a weld seam 14 forms, in which the material of the component 10 has already solidified.
- a measuring beam 15 of an optical coherence tomograph (not shown) is directed at the deepest point 16 of the vapor capillary 12, and the depth of the vapor capillary 12 in the z-direction at this point 16 is determined from the reflected radiation.
- OCT optical coherence tomograph
- Fig. 2 illustrates how, according to a method according to the invention, a plurality of depth measurement points are generated in the z-direction over a measuring line extending in the feed direction x of the processing laser beam 11 by lateral scans with the measuring beam 15 over a component such as the component 10 of Fig. 1.
- the measuring points are created by reflections of the measuring beam 11 at the component surface 10.1, the vapor capillary 12, and the melt pool 13. From this multitude of measurement points, a height profile 18, 19 of the scanned component is created according to the two examples in Fig. 3a, 3b by forming a moving intensity-weighted average from the measurement data.
- a window M of length b is shifted in the x-direction along the measurement line formed by the positions of the measurement beam (OCT measurement positions), and the average is calculated from all measurement data contained in this window.
- the lateral position of the lowest point 16', 16" of the height profiles 18, 19 can be determined.
- the measurement data in the vicinity of these lowest points 16', 16" can then be evaluated using histograms to determine the depth of the vapor capillary 12', 12", as illustrated in Fig. 4a, 3b.
- the histogram class 20, 20' with the highest number of measurement points that lie below the height position of the component surface 10.T, 10.1" indicates the desired welding depth 17.
- the height position of the component surfaces 10.T, 10.1" can be determined from the height profiles 18, 19. In the examples shown, the welding depth 17 is 2.70 mm in Fig. 4a and 0.80 mm in Fig. 4b.
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
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- Mechanical Engineering (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
Verfahren zur Bestimmung der Einschweißtiefe bei einem Laserschweißprozess Method for determining the penetration depth in a laser welding process
Die Erfindung betrifft ein Verfahren zur Bestimmung der Einschweißtiefe bei einem Laserschweißprozess mittels eines optischen Kohärenztomographen. The invention relates to a method for determining the welding depth in a laser welding process using an optical coherence tomograph.
Bei Laserschweißprozessen mittels eines Bearbeitungslaserstrahls ist die Messung der Einschweißtiefe unabdingbar, um eine hochwertige Schweißnaht garantieren zu können. Ist die Einschweißtiefe nicht ausreichend tief, weist die Schweißnaht nicht die erforderliche Festigkeit auf. Bei einer zu großen Einschweißtiefe kann es dagegen zu Durchschweißungen kommen. Es sind daher bereits verschiedene Verfahren vorgeschlagen worden, die Einschweißtiefe bei Laserschweißprozessen zu messen. In laser welding processes using a laser beam, measuring the penetration depth is essential to ensure a high-quality weld. If the penetration depth is insufficient, the weld will not have the required strength. If the penetration depth is too great, however, penetration can occur. Therefore, various methods have already been proposed for measuring the penetration depth in laser welding processes.
Bei der Verwendung eines optischen Kohärenztomographen zur Einschweißtiefenmessung ist die Einstellung der richtigen Messposition des Messstrahls essenziell. Der Messstrahl muss auf den tiefsten Punkt der vom Bearbeitungslaserstrahl erzeugten Dampfkapillare im Bauteil positioniert werden, um die Einschweißtiefe zuverlässig messen zu können. Da sich die tiefste Position der Dampfkapillare je nach Prozessparametern verändern kann, muss vor dem Laserschweißprozess ein Einrichtprozess durchgeführt werden, durch den die Messposition für den Messstrahl ermittelt wird. Die bekannten Einrichtprozesse sind jedoch aufwändig und erfordern einen zweiten Messschritt zur Bestimmung der Einschweißtiefe. When using an optical coherence tomography system to measure the penetration depth, setting the correct measurement position of the measuring beam is essential. The measuring beam must be positioned at the deepest point of the vapor capillary created by the processing laser beam in the component to reliably measure the penetration depth. Since the deepest position of the vapor capillary can change depending on the process parameters, a setup process must be performed before the laser welding process to determine the measurement position for the measuring beam. However, the existing setup processes are complex and require a second measurement step to determine the penetration depth.
So wird beispielsweise bei dem aus der DE 102017 117 413 B4 bekannten Verfahren die Messposition des Messstrahls zur Einschweißtiefenmessung dadurch bestimmt, dass mehrere Scans mit dem Messstrahl in Vorschubrichtung des Bearbeitungslaserstrahls und quer dazu durchgeführt werden, um mit Hilfe eines optischen Kohärenztomographen aus diesen Scans ein Höhenprofil des Bauteils im Bereich der vom Bearbeitungslaserstrahl erzeugten Dampfkapillare erstellen zu können. Aus dem Höhenprofil lässt sich die laterale Position des tiefsten Punktes der Dampfkapillare ermitteln. Anschließend wird der Messstrahl auf den tiefsten Punkt der Dampfkapillare gerichtet und die eigentliche Messung der Einschweißtiefe vorgenommen. For example, in the method known from DE 102017 117 413 B4, the measuring position of the measuring beam for welding depth measurement is determined by performing several scans with the measuring beam in the feed direction of the processing laser beam and transversely to it in order to create a height profile of the component in the area of the vapor capillary generated by the processing laser beam using an optical coherence tomograph. The lateral position of the lowest point of the vapor capillary can be determined from the height profile. The measuring beam is then directed to the lowest point of the vapor capillary, and the actual measurement of the penetration depth is performed.
Ein ähnliches Verfahren zur Bestimmung der Messposition eines Messstrahls ist auch aus der DE 10 2019 103 734 A1 bekannt. A similar method for determining the measuring position of a measuring beam is also known from DE 10 2019 103 734 A1.
Die DE 10 2016 005021 A1 beschreibt ein Verfahren, wie durch Richten des Messstrahls auf den tiefsten Punkt einer Dampfkapillare und Durchführen von Messungen der Tiefe des tiefsten Punktes zu mehreren unterschiedlichen Zeitpunkten aus den Daten dieser verschiedenen Messungen bei bekannter Höhenposition der Bauteiloberfläche die Einschweißtiefe während eines Laserbearbeitungsprozesses gemessen werden kann. DE 10 2016 005021 A1 describes a method for measuring the welding depth during a laser processing process by directing the measuring beam to the lowest point of a vapor capillary and carrying out measurements of the depth of the lowest point at several different times from the data of these different measurements when the height position of the component surface is known.
Der Erfindung liegt die Aufgabe zugrunde, ein rationelleres Verfahren zur Messung der Einschweißtiefe bei Laserbearbeitungsprozessen vorzuschlagen. The invention is based on the object of proposing a more efficient method for measuring the welding depth in laser processing processes.
Diese Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren zur Bestimmung der Einschweißtiefe bei einem Laserschweißprozess mittels eines optischen Kohärenztomographen mit folgenden Schritten: This object is achieved according to the invention by a method for determining the welding depth in a laser welding process by means of an optical coherence tomograph with the following steps:
- Richten eines Bearbeitungslaserstrahls auf ein Bauteil, der in diesem eine Dampfkapillare erzeugt; - Directing a processing laser beam onto a component, which creates a vapor capillary in it;
- Einkoppeln eines Messstrahls in den Strahlengang des Bearbeitungslaserstrahl;- Coupling a measuring beam into the beam path of the processing laser beam;
- Durchführen mehrerer Linienscans über das Bauteil mit dem Messstrahl im Bereich der Dampfkapillare und Erfassen der vom Bauteil reflektierten Lichtanteile des Messstrahls mit dem optischen Kohärenztomographen und Generierung eines überlagerten Höhenprofils des Bauteils im Bereich der Dampfkapillare aus den Linienscans; - Performing several line scans over the component with the measuring beam in the area of the vapor capillary and recording the light components of the measuring beam reflected by the component with the optical coherence tomograph and generating a superimposed height profile of the component in the area of the vapor capillary from the line scans;
- aus dem Höhenprofil Bestimmung der Höhe der Bauteiloberfläche, der lateralen Position des tiefsten Punktes der Dampfkapillare auf dem Bauteil sowie der Tiefe des tiefsten Punkts der Dampfkapillare; - Berechnung der Dampfkapillartiefe aus der Differenz zwischen der Höhe der Bauteiloberfläche und der Tiefe des tiefsten Punktes der Dampfkapillare und daraus Ermittlung der Einschweißtiefe. - from the height profile, determination of the height of the component surface, the lateral position of the lowest point of the vapor capillary on the component and the depth of the lowest point of the vapor capillary; - Calculation of the vapor capillary depth from the difference between the height of the component surface and the depth of the lowest point of the vapor capillary and from this determination of the welding depth.
Die Unteransprüche beziehen sich auf bevorzugte Ausführungsformen. The subclaims relate to preferred embodiments.
Beim erfindungsgemäßen Verfahren werden aus den Messdaten der mehreren zeitlich und räumlich voneinander beabstandeten Scans mit dem Messstrahl alle für die Bestimmung der Einschweißtiefe notwendigen Parameter erfasst. Aus diesen Messdaten und dem daraus erstellten Höhenprofil des Bauteils im Bereich der Dampfkapillare lassen sich die Höhe der Bauteiloberfläche, die laterale Position des tiefsten Punktes der Dampfkapillare sowie die Tiefe der Dampfkapillare an diesem Punkt bestimmen. Aus dieser Tiefe und der Höhe der Bauteiloberfläche lässt sich anschließend die Einschweißtiefe berechnen. Es müssen hier also im Unterschied zu den bekannten Verfahren nicht zwei getrennte Messungen durchgeführt werden, eine erste Messung zur Bestimmung der lateralen Position des tiefsten Punktes der Dampfkapillare und in einer zweiten Messung, nach Richten des Messstrahls auf den tiefsten Punkt der Dampfkapillare, die Bestimmung der Tiefe der Dampfkapillare an diesem Punkt. In the method according to the invention, all parameters necessary for determining the welding depth are recorded from the measurement data of the multiple temporally and spatially spaced scans with the measuring beam. From this measurement data and the resulting height profile of the component in the area of the vapor capillary, the height of the component surface, the lateral position of the lowest point of the vapor capillary, and the depth of the vapor capillary at this point can be determined. The welding depth can then be calculated from this depth and the height of the component surface. In contrast to the known methods, two separate measurements do not have to be carried out here: a first measurement to determine the lateral position of the lowest point of the vapor capillary and, in a second measurement, after directing the measuring beam onto the lowest point of the vapor capillary, to determine the depth of the vapor capillary at this point.
Die Linienscans mit dem Messstrahl können vorzugsweise in Vorschubrichtung des Bearbeitungslaserstrahls und/oder quer dazu durchgeführt werden. Damit lässt sich der gesamte Bereich der Dampfkapillare sowie die vom Bearbeitungslaserstrahl nicht angeschmolzene Bauteiloberfläche mit den Scans erfassen. The line scans with the measuring beam can preferably be performed in the feed direction of the processing laser beam and/or perpendicular to it. This allows the entire area of the vapor capillary as well as the component surface not melted by the processing laser beam to be captured with the scans.
Weitere Vorteile ergeben sich, wenn die Messdaten mehrerer oder aller mit dem Messstrahl durchgeführten Scans überlagert werden und durch Bilden eines gleitenden intensitätsgewichteten Mittelwerts aus den Messdaten ein Höhenprofil des Bauteils im Bereich der Dampfkapillare erstellt und die laterale Position des tiefsten Punktes der Dampfkapillare ermittelt wird. In gleicher Weise können die Messdaten mehrerer oder aller mit dem Messstrahl durchgeführten Scans überlagert werden und durch Bilden eines gleitenden intensitätsgewichteten Mittelwerts aus den Messdaten ein Höhenprofil des Bauteils im Bereich der Dampfkapillare erstellt und die Höhe der Bauteiloberfläche ermittelt werden. Further advantages arise when the measurement data of several or all scans carried out with the measuring beam are superimposed and a height profile of the component in the area of the vapor capillary is created by forming a moving intensity-weighted average from the measurement data and the lateral position of the lowest point of the vapor capillary is determined. In the same way, the measurement data of several or all scans performed with the measuring beam can be superimposed and, by forming a moving intensity-weighted average from the measurement data, a height profile of the component in the area of the vapor capillary can be created and the height of the component surface can be determined.
Aus dem durch diese Mittelwertbildung ermittelten Höhenprofil kann somit die Höhe der Bauteiloberfläche und/oder die laterale Position des tiefsten Punktes der Dampfkapillare mit ausreichender Genauigkeit bestimmt werden. Auch die Messung der Tiefe der Dampfkapillare an ihrem tiefsten Punkt kann bereits aus dem Höhenprofil abgelesen werden. From the height profile determined by this averaging, the height of the component surface and/or the lateral position of the lowest point of the vapor capillary can be determined with sufficient accuracy. The measurement of the depth of the vapor capillary at its lowest point can also be read from the height profile.
Eine höhere Genauigkeit der Tiefenmessung der Dampfkapillare lässt sich allerdings erzielen, wenn die durch die Scans mit dem Messstrahl erzeugten Messdaten im Bereich des tiefsten Punktes der Dampfkapillare mittels Perzentilfilter mit einem gleitenden zeitlichen Prozessfenster oder mittels einer Histogrammauswertung gefiltert werden, um die Tiefe der Dampfkapillare an ihrem tiefsten Punkt und daraus die Einschweißtiefe zu bestimmen. However, a higher accuracy of the depth measurement of the vapor capillary can be achieved if the measurement data generated by the scans with the measuring beam in the area of the deepest point of the vapor capillary are filtered using a percentile filter with a sliding temporal process window or by means of a histogram evaluation in order to determine the depth of the vapor capillary at its deepest point and from this the welding depth.
Bei einer Histogrammauswertung der Messdaten kann eine statistisch signifikante Histogrammklasse, insbesondere diejenige mit den meisten unterhalb der Höhenposition der Bauteiloberfläche liegenden Messpunkten direkt die Einschweißtiefe angeben. When evaluating the measurement data histogram, a statistically significant histogram class, in particular the one with the most measurement points below the height position of the component surface, can directly indicate the welding depth.
Das erfindungsgemäße Verfahren kann zur Einrichtung einer Laserbearbeitungsmaschine vor einem Produktionsprozess und/oder kontinuierlich oder in zeitlichen Intervallen während des Produktionsprozesses durchgeführt werden. The method according to the invention can be carried out for setting up a laser processing machine before a production process and/or continuously or at time intervals during the production process.
Wird das Verfahren nur zur Einrichtung eines Produktionsprozesses eingesetzt, so ist bereits mit der Einrichtung die mittlere Einschweißtiefe bekannt. Anschließend kann zur laufenden Kontrolle der Einschweißtiefe nach Durchführung des Verfahrens zur Einrichtung einer Laserbearbeitungsmaschine der Messstrahl auf die laterale Position des tiefsten Punktes der Dampfkapillare gerichtet und fortlaufend die Tiefe der Dampfkapillare an ihrem tiefsten Punkt gemessen und daraus die Einschweißtiefe berechnet werden. In diesem Fall wird das Verfahren lediglich zur rationellen Einrichtung der Laserbearbeitungsmaschine vor dem Produktionsprozess eingesetzt. Anschließend wird eine fortlaufende Messung der Einschweißtiefe vorgenommen, indem der Messstrahl an der bei der Einrichtung der Laserbearbeitungsmaschine ermittelten Messposition über dem tiefsten Punkt der Dampfkapillare gehalten wird. Bei einer Herstellung von Schweißnähten bei gleichbleibenden Randbedingungen mag dieser Einsatz des Verfahrens ausreichend sein. Vorzugsweise wird jedoch auch während des Produktionsprozesses entweder kontinuierlich oder in zeitlichen oder räumlichen Intervallen das erfindungsgemäße Verfahren erneut ausgeführt, um eventuelle Verschiebungen des tiefsten Punktes der Dampfkapillare ausgleichen und die Einschweißtiefe dennoch korrekt bestimmen zu können. Dies ist insbesondere bei kontinuierlichen Schweißprozessen wie dem Rohrschweißen von Bedeutung. If the method is only used to set up a production process, the average welding depth is already known during setup. Subsequently, for continuous control of the welding depth after the procedure has been carried out, To set up a laser processing machine, the measuring beam is directed at the lateral position of the lowest point of the vapor capillary and the depth of the vapor capillary is continuously measured at its deepest point and the welding depth is calculated from this. In this case, the method is only used for the efficient setup of the laser processing machine before the production process. Subsequently, a continuous measurement of the welding depth is carried out by holding the measuring beam at the measuring position determined during setup of the laser processing machine above the deepest point of the vapor capillary. When producing weld seams under constant boundary conditions, this use of the method may be sufficient. However, the method according to the invention is preferably carried out again during the production process, either continuously or at temporal or spatial intervals, in order to compensate for any shifts in the deepest point of the vapor capillary and still be able to correctly determine the welding depth. This is particularly important for continuous welding processes such as pipe welding.
Weitere Merkmale und Vorteile der Erfindung ergeben sich aus der Beschreibung, den Ansprüchen und der Zeichnung. Erfindungsgemäß können die vorstehend genannten und die noch weiter ausgeführten Merkmale jeweils einzeln für sich oder zu mehreren in beliebigen zweckmäßigen Kombinationen Verwendung finden. Die gezeigten und beschriebenen Ausführungsformen sind nicht als abschließende Aufzählung zu verstehen, sondern haben vielmehr beispielhaften Charakter für die Schilderung der Erfindung. Further features and advantages of the invention will become apparent from the description, the claims, and the drawings. According to the invention, the features mentioned above and those further described can be used individually or in combination in any convenient way. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention.
Detaillierte Beschreibung der Erfindung und Zeichnung Detailed description of the invention and drawing
Fig. 1 zeigt einen Querschnitt durch ein Bauteil im Bereich einer von einem Bearbeitungslaserstrahl erzeugten Dampfkapillare; Fig. 1 shows a cross-section through a component in the region of a vapor capillary generated by a processing laser beam;
Fig. 2 zeigt eine Verteilung von Messdaten mehrerer OCT-Scans über den Bereich der Dampfkapillare des Bauteils aus Fig. 1 ; Fig. 3a, 3b zeigt die Erstellung eines Höhenprofils zweier Dampfkapillare aus Messdaten mehrerer OCT-Scans; Fig. 2 shows a distribution of measurement data from several OCT scans over the area of the vapor capillary of the component from Fig. 1 ; Fig. 3a, 3b shows the creation of a height profile of two vapor capillaries from measurement data of several OCT scans;
Fig. 4a, 4b zeigt Histogrammauswertungen von Messdaten der Tiefe zweier Dampfkapillare. Fig. 4a, 4b shows histogram evaluations of measurement data of the depth of two vapor capillaries.
Fig. 1 verdeutlicht die Herstellung einer Schweißnaht 14 in einem Bauteil 10. Das Bauteil 10 wird dazu von einem Bearbeitungslaserstrahl 11 bestrahlt. Der Bearbeitungslaserstrahl 11 erzeugt im Bauteil 10 eine Dampfkapillare 12, in der das Material des Bauteils 10 in einem gas- oder plasmaförmigen Zustand vorliegt. Der Bearbeitungslaserstrahl 11 bewegt sich dabei in Richtung x über das Bauteil 10 hinweg. Daher bildet sich hinter der Dampfkapillare ein Schmelzbad 13 aus, in dem das zuvor gasförmige Material des Bauteils 10 in der Dampfkapillare 12 durch Abkühlung bereits in einen flüssigen Zustand übergegangen ist. Weiter entfernt von der Dampfkapillare 12 bildet sich eine Schweißnaht 14 aus, in der das Material des Bauteils 10 bereits erstarrt ist. Fig. 1 illustrates the production of a weld seam 14 in a component 10. The component 10 is irradiated by a processing laser beam 11. The processing laser beam 11 creates a vapor capillary 12 in the component 10, in which the material of the component 10 is in a gaseous or plasma state. The processing laser beam 11 moves in the x direction across the component 10. Therefore, a molten pool 13 forms behind the vapor capillary, in which the previously gaseous material of the component 10 has already transformed into a liquid state due to cooling in the vapor capillary 12. Further away from the vapor capillary 12, a weld seam 14 forms, in which the material of the component 10 has already solidified.
Zur Messung der Einschweißtiefe 17 der Schweißnaht 14 wird ein Messstrahl 15 eines optischen Kohärenztomographen OCT (nicht dargestellt) auf den tiefsten Punkt 16 der Dampfkapillare 12 gerichtet und aus der reflektierten Strahlung die Tiefe der Dampfkapillare 12 in z-Richtung an diesem Punkt 16 bestimmt. Der Abstand dieser gemessenen Tiefe von der Oberfläche 10.1 des Bauteils 10 entspricht der Einschweißtiefe 17 der Schweißnaht 14. To measure the penetration depth 17 of the weld seam 14, a measuring beam 15 of an optical coherence tomograph (OCT) (not shown) is directed at the deepest point 16 of the vapor capillary 12, and the depth of the vapor capillary 12 in the z-direction at this point 16 is determined from the reflected radiation. The distance of this measured depth from the surface 10.1 of the component 10 corresponds to the penetration depth 17 of the weld seam 14.
Fig. 2 verdeutlicht, wie nach einem erfindungsgemäßen Verfahren durch laterale Scans mit dem Messstrahl 15 über ein Bauteil wie das Bauteil 10 aus Fig. 1 eine Vielzahl von Tiefenmesspunkten in z-Richtung über einer sich in Vorschubrichtung x des Bearbeitungslaserstrahls 11 erstreckenden Messlinie erzeugt werden. Die Messpunkte entstehen durch Reflexionen des Messstrahls 11 an der Bauteiloberfläche 10.1 , der Dampfkapillare 12 und dem Schmelzbad 13. Aus dieser Vielzahl von Messpunkten wird gemäß den beiden Beispielen in Fig. 3a, 3b durch ein Bilden eines gleitenden intensitätsgewichteten Mittelwerts aus den Messdaten ein Höhenprofil 18, 19 des gescannten Bauteils erstellt. Dazu wird ein Fenster M der Länge b entlang der durch die Positionen des Messstrahls (OCT- Messpositionen) gebildeten Messlinie in x-Richtung verschoben und aus allen in diesem Fenster enthaltenen Messdaten die Mittelwertbildung vorgenommen. Aus den sich ergebenden Höhenprofilen 18, 19 kann jeweils die laterale Position des tiefsten Punktes 16‘, 16“ der Höhenprofile 18, 19 bestimmt werden. Anschließend lassen sich die Messdaten in der Nähe dieser tiefsten Punkte 16‘, 16“ durch Histogramme auswerten, um die Tiefe der Dampfkapillare 12‘, 12“ zu ermitteln, wie Fig. 4a, 3b verdeutlicht. Die Histogrammklasse 20, 20' mit der höchsten Anzahl von Messpunkten, die unterhalb der Höhenposition der Bauteiloberfläche 10.T, 10.1“ liegen, gibt die gesuchte Einschweißtiefe 17 an. Die Höhenposition der Bauteiloberflächen 10.T, 10.1“ kann dabei aus den Höhenprofile 18, 19 bestimmt werden. In den dargestellten Beispielen beträgt die Einschweißtiefe 17 in Fig. 4a 2,70mm und in Fig. 4b 0,80mm. Fig. 2 illustrates how, according to a method according to the invention, a plurality of depth measurement points are generated in the z-direction over a measuring line extending in the feed direction x of the processing laser beam 11 by lateral scans with the measuring beam 15 over a component such as the component 10 of Fig. 1. The measuring points are created by reflections of the measuring beam 11 at the component surface 10.1, the vapor capillary 12, and the melt pool 13. From this multitude of measurement points, a height profile 18, 19 of the scanned component is created according to the two examples in Fig. 3a, 3b by forming a moving intensity-weighted average from the measurement data. For this purpose, a window M of length b is shifted in the x-direction along the measurement line formed by the positions of the measurement beam (OCT measurement positions), and the average is calculated from all measurement data contained in this window. From the resulting height profiles 18, 19, the lateral position of the lowest point 16', 16" of the height profiles 18, 19 can be determined. The measurement data in the vicinity of these lowest points 16', 16" can then be evaluated using histograms to determine the depth of the vapor capillary 12', 12", as illustrated in Fig. 4a, 3b. The histogram class 20, 20' with the highest number of measurement points that lie below the height position of the component surface 10.T, 10.1" indicates the desired welding depth 17. The height position of the component surfaces 10.T, 10.1" can be determined from the height profiles 18, 19. In the examples shown, the welding depth 17 is 2.70 mm in Fig. 4a and 0.80 mm in Fig. 4b.
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| US20160039045A1 (en) * | 2013-03-13 | 2016-02-11 | Queen's University At Kingston | Methods and Systems for Characterizing Laser Machining Properties by Measuring Keyhole Dynamics Using Interferometry |
| DE102016005021A1 (en) | 2016-04-22 | 2016-09-01 | Precitec Optronik Gmbh | Method and apparatus for measuring the depth of the vapor capillary during a high energy beam machining process |
| DE102017117413B4 (en) | 2017-08-01 | 2019-11-28 | Precitec Gmbh & Co. Kg | Method for optical measurement of the welding depth |
| DE102019103734A1 (en) | 2019-02-14 | 2020-08-20 | Precitec Gmbh & Co. Kg | Laser processing system for processing a workpiece by means of a laser beam and method for controlling a laser processing system |
| US20220055147A1 (en) * | 2020-08-19 | 2022-02-24 | Panasonic Intellectual Property Management Co., Ltd. | Laser processing apparatus and laser processing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20160039045A1 (en) * | 2013-03-13 | 2016-02-11 | Queen's University At Kingston | Methods and Systems for Characterizing Laser Machining Properties by Measuring Keyhole Dynamics Using Interferometry |
| DE102016005021A1 (en) | 2016-04-22 | 2016-09-01 | Precitec Optronik Gmbh | Method and apparatus for measuring the depth of the vapor capillary during a high energy beam machining process |
| DE102017117413B4 (en) | 2017-08-01 | 2019-11-28 | Precitec Gmbh & Co. Kg | Method for optical measurement of the welding depth |
| DE102019103734A1 (en) | 2019-02-14 | 2020-08-20 | Precitec Gmbh & Co. Kg | Laser processing system for processing a workpiece by means of a laser beam and method for controlling a laser processing system |
| US20220055147A1 (en) * | 2020-08-19 | 2022-02-24 | Panasonic Intellectual Property Management Co., Ltd. | Laser processing apparatus and laser processing method |
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