WO2024161518A1 - Laser machining apparatus - Google Patents

Abstract

Provided is a technology capable of accurately measuring a keyhole depth without executing complicated control in a laser machining device which performs machining involving a cyclic operation. A laser machining device 1 includes a control device 20 (machining beam control unit) which controls a laser light deflection mechanism 13 and a laser light source 11 and an OCT system controller 31 (measurement light control unit) which controls a measurement light deflection mechanism 34. The control device 20 controls the laser light deflection mechanism 13 on the basis of a machining command for performing oscillation in a cyclic shape. The OCT system controller 31 controls the measurement light deflection mechanism 34 on the basis of a movement component to direct measurement light to a certain position relative to the machining beam, thereby acquiring a measurement value.

Description

Laser Processing Equipment

This disclosure relates to a laser processing device.

　Conventionally, there is known a technique for using an OCT system to monitor welding quality when welding is performed while oscillating. Patent Document 1 relates to this type of OCT technology.

Patent No. 6999032

In an OCT system, the deflection element may be operated in coordination with the processing beam path, which contains a periodic oscillation component, to move the measurement light of the OCT system to the keyhole generation position for measurement. However, coordinated operation requires a communication means with high time resolution and communication speed, as well as advanced synchronization control that transmits travel direction vector information from the processing head control unit to the OCT system at high frequency. If delays occur in these, it may not be possible to irradiate the measurement light to the bottom of the keyhole.

In some cases, the processing beam and the measurement light of the OCT system are incident on the same axis, and the penetration depth is calculated from the keyhole depth measurement results. However, since the keyhole generally occurs behind the processing beam, the depth of the keyhole bottom cannot be obtained directly by measuring on the same axis as the processing beam.

This disclosure has been made in consideration of the above problems, and aims to provide a technology that can accurately measure keyhole depth without complex control in a laser processing device that performs processing involving periodic operations.

The present disclosure relates to a laser processing device that includes a laser light source for generating a processing beam, a processing head that is coupled to the laser light source and includes at least one laser light deflection mechanism for irradiating the processing beam to a processing location of a workpiece, a processing beam control unit that controls the laser light deflection mechanism and the laser light source, at least one measurement light deflection mechanism optically coupled to the processing head, a measurement light control unit that controls the measurement light deflection mechanism, and an optical coherence interferometer unit that uses measurement light to obtain a measurement value related to a keyhole depth that occurs near the processing location of the workpiece during welding processing, in which the processing beam control unit controls the laser light deflection mechanism based on a processing command that performs a periodic shape oscillation in at least one direction, and the measurement light control unit controls the measurement light deflection mechanism based on a movement component in the at least one direction that does not include the oscillation, and obtains the measurement value by irradiating the measurement light at a fixed relative position with respect to the processing beam.

This disclosure provides a technology that can accurately measure keyhole depth without complex control in a laser processing device that performs processing involving periodic operations.

1 is a schematic diagram showing a configuration of a laser processing apparatus according to an embodiment of the present invention; 3 is a schematic diagram showing the positional relationship between a processing beam and a measurement light irradiated by a laser processing apparatus; FIG. 13 is a diagram showing an example in which the oscillation component of the oscillation machining is a circular motion. 11A and 11B are diagrams illustrating an example in which the oscillation component of the oscillation machining is a linear motion. FIG. 13 is a diagram showing an example in which the oscillation component of the oscillation machining is a figure-of-eight motion. FIG. 13 is a diagram showing an example in which the oscillation component of the oscillation machining is a motion that draws an infinity symbol. 1 is a schematic diagram showing the positional relationship between a processing beam and a measurement light during oscillation processing in a laser processing apparatus of the prior art; 4 is a schematic diagram showing the positional relationship between a processing beam and a measurement light during oscillation processing in the laser processing apparatus of the present embodiment. FIG. 1 is a schematic diagram showing a positional relationship between a processing beam and a measurement light on a welding locus during oscillation processing; FIG. FIG. 2 is a schematic diagram illustrating a control process of the laser processing apparatus. FIG. 2 is a schematic diagram showing the cross-section of a workpiece during laser processing. 13A and 13B are diagrams showing an example of performing measurement of a keyhole bottom based on a first measurement pattern. 13A and 13B are diagrams showing an example of performing measurement of a keyhole bottom based on a second measurement pattern. FIG. 2 is a schematic diagram of a filter used in the analysis of OCT measurements. FIG. 13 is a schematic diagram showing a part of the configuration of a laser processing apparatus according to a modified example. 13 is a schematic diagram showing a movement locus of a processing beam and a movement locus of a measurement beam in a laser processing device according to a modified example. FIG.

The embodiments of the present disclosure will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a laser processing device 1 according to one embodiment of the present invention. The laser processing device 1 shown in FIG. 1 performs welding processing by irradiating a processing beam onto a workpiece placed on a moving stage. Note that the configuration is not limited to placing the workpiece on a moving stage, and the method of placing the workpiece can be changed as appropriate.

The configuration of the laser processing device 1 of this embodiment will be described. The laser processing device 1 includes a laser light source 11, a processing head 12, a control device 20, and an OCT (Optical Coherence Tomography) system 30.

The laser light source 11 internally oscillates a laser in response to a command (such as a laser power command) from the control device 20 to generate a laser beam. The laser light source 11 may be of any type, such as a fiber laser oscillator, a pulsed laser oscillator, a direct diode laser (DDL), a _CO2 laser oscillator, or a solid-state laser (YAG laser) oscillator. The laser light source 11 supplies the generated laser beam to the processing head 12.

The processing head 12 is equipped with optical components 50, such as lenses 51-53 and mirrors 54-56. Of the optical components 50, mirror 54 is a dichroic mirror that reflects the processing beam while transmitting the measurement light.

The processing head 12 may be configured with a wobble head having a wobble function, a galvanometer scanner, or a polygon mirror. The processing head 12 may also be a device placed on a moving stage or a device connected to a robot. In this way, the configuration of the processing head 12 is not particularly limited.

The laser light deflection mechanism 13 adjusts the positions and angles of optical components such as mirrors 55-56 based on commands from the control device 20 to control the irradiation position.

The control device 20 is configured, for example, using a computer equipped with memories such as ROM (read only memory) and RAM (random access memory), a CPU (Control Processing Unit), and a communication control unit, all connected to each other via a bus. The functions and operations of each functional unit described below are achieved by the cooperation of the CPU, memory, and control programs stored in the memory mounted on the computer. The control device 20 may be configured with a CNC (Computer Numerical Controller) or a PLC (Programmable Logic Controller), or may be connected to a higher-level computer that outputs machining conditions, etc. in addition to the machining program.

The control device 20 of this embodiment has a laser controller function and a scanner controller function, and is a control unit that controls the operation of the laser light source 11 and the laser light deflection mechanism 13.

In addition, various functions may be added to the control device 20. For example, a welding monitoring system using an image sensor such as a C-MOS or CCD, or a welding monitoring system using a photodiode may be connected to the control device 20.

Hardware related to various functions to be added to the control device 20 may be installed independently, or may be optically coupled to the processing head 12 and the OCT scanner 33.

The OCT system 30 is a sensor system that determines the optical path length difference between the reflected light at the measurement point and the reference light from the interference fringes of the two lights. The OCT system 30 makes it possible to monitor the keyhole depth (≒weld depth) by measuring during welding. This makes it possible to directly determine whether the welding is good or bad.

The OCT system 30 of this embodiment is an optical coherence interferometer unit that includes an OCT system controller 31, a measurement light source 32, an OCT scanner 33, and a measurement light deflection mechanism 34.

The OCT system controller 31 is a measurement light control unit that communicates with the control device 20 and controls the operation of the measurement light source 32 and the OCT scanner 33. In addition, the OCT system controller 31 of this embodiment has a calculation unit 35 for analyzing the keyhole. The analysis process of this calculation unit 35 will be described later.

The measurement light source 32 is a light source that generates the measurement light used in the optical coherence interferometer. The OCT scanner 33 is equipped with optical components 60 such as a lens 57 and mirrors 58-59.

The measurement light deflection mechanism 34 may be a device consisting of a galvanometer scanner or a polygon mirror. In this embodiment, the measurement light deflection mechanism 34 optically couples the measurement light to the optical path formed by the optical component 50 of the processing head 12 using mirrors 58-59. The measurement light deflection mechanism 34 operates based on commands from the OCT system controller 31.

The positional relationship between the processing beam and the measurement light will be explained with reference to Figure 2. Figure 2 is a schematic diagram showing the positional relationship between the processing beam and the measurement light irradiated by the laser processing device 1. Figure 2 shows the positions of the processing beam and the measurement light when the workpiece W to be processed is viewed from directly above. During measurement, the relative position of the measurement light with respect to the processing beam is specified by the angle of mirrors 58-59 of the measurement light deflection mechanism 34. Therefore, when the angle of mirrors 58-59 is constant, the positional relationship is also constant regardless of the position of the processing beam.

Next, oscillation processing by the laser processing device 1 will be described with reference to Figures 3A to 3D. In oscillation processing, a processing beam is irradiated while accompanying a periodic motion that differs from the movement in the direction of travel. Figure 3A is a diagram showing an example in which the oscillation component of oscillation processing is a circular motion. Figure 3B is a diagram showing an example in which the oscillation component of oscillation processing is a linear motion. Figure 3C is a diagram showing an example in which the oscillation component of oscillation processing is a figure-of-eight motion. Figure 3D is a diagram showing an example in which the oscillation component of oscillation processing is a motion that draws an infinity symbol.

In the following explanation, a wobbling shape with approximately circular motion (hexagonal) will be described as an example of oscillation processing. Note that the laser processing device 1 of this embodiment can handle any shape of periodic oscillation component. Therefore, the oscillation component is not limited to approximately circular motion.

First, the conventional technology will be described with reference to Figure 4. Figure 4 is a schematic diagram showing the positional relationship between the processing beam and the measurement light during oscillating processing in a conventional laser processing device. As shown in Figure 4, in the conventional technology, the position of the measurement light was specified based on the movement trajectory of the processing beam. Therefore, every time the side of the hexagon changes with movement, the relative position of the measurement light with respect to the processing beam must be changed. For example, with a wobbling period of 100 Hz and a circle approximated to a hexagon, a position command without delay is required every 1.4 ms.

In this embodiment, laser processing is performed without changing the relative positions of the processing beam and the measurement light. FIG. 5 is a schematic diagram showing the positional relationship between the processing beam and the measurement light during oscillation processing in the laser processing device 1 of this embodiment. As shown in FIG. 5, since the relative positions of the processing beam and the measurement light do not change, after passing the first side of the hexagon, the measurement light cannot measure at the keyhole position that occurs behind the processing beam. On the other hand, at the measurement point of the first side of the hexagon in the movement trajectory of the processing beam, the measurement light can follow the rear of the processing beam and measure at the keyhole position. Generally, the keyhole occurs behind the processing beam, so in FIG. 5, when the measurement light is located behind the movement path of the processing beam, the keyhole bottom can be measured by OCT, but the keyhole may occur other than behind the movement path of the processing beam. By adjusting the relative positions of the processing beam and the measurement light so that the OCT measurement position periodically overlaps with the position where the keyhole occurs, it is possible to periodically measure the keyhole depth that occurs at any position; the position where the keyhole bottom occurs and the relative position of the OCT measurement are not limited.

FIG. 6 is a schematic diagram showing the positional relationship between the processing beam and the measurement light in the welding trajectory during oscillation processing. FIG. 6 shows the welding trajectory when oscillation processing is performed based on an arc-shaped moving component. The inclination of the moving component changes during the oscillation trajectory. The relative positional relationship between the processing beam and the measurement light corresponds to the inclination of this moving component. Since the moving trajectory at each stage of the welding trajectory in FIG. 6 is different, the relative positional relationship between the processing beam and the measurement light is different at each stage. For example, in the first part of the welding trajectory in FIG. 6, the tip side of the moving component is inclined upward on the paper in the horizontal direction, but the positional relationship between the measurement light and the processing beam is also the same. The measurement light is located at the bottom left of the paper relative to the processing beam. While maintaining this relative positional relationship, an approximately circular oscillation is performed. As the movement progresses, the moving component moves along the horizontal direction, and the measurement light becomes aligned horizontally with respect to the processing beam. As the movement continues, the tip of the movement component tilts downward on the page relative to the lateral direction, and the measurement light is positioned at the top left of the page relative to the processing beam.

In this way, the relative positional relationship between the processing beam and the measurement light also changes in response to changes in the moving component. On the other hand, if the moving component is constant, the relative positional relationship is maintained.

Next, the control process of the laser processing device 1 of this embodiment will be described with reference to FIG. 7. FIG. 7 is a schematic diagram for explaining the control process of the laser processing device 1. As shown in FIG. 7, the control device 20 acquires a movement command and a swing component from a pre-set processing program or the like. The movement command is a command that determines the movement component during welding processing. The swing component is a command that determines periodic operation.

Then, the control device 20 generates a processing beam path based on the acquired movement command and oscillation component. The processing beam path specifies the movement trajectory of the above-mentioned processing beam. The control device 20 controls the laser light source 11 and the laser light deflection mechanism 13 based on the generated processing beam path to perform oscillation processing.

In conventional technology, the movement path of the measurement light in the OCT system 30 was based on the processing beam path. In this embodiment, the movement path of the measurement light is generated without using the processing beam path.

The control device 20 outputs a movement command to the OCT system controller 31. The OCT system controller 31 controls the measurement light source 32 and the measurement light deflection mechanism 34 based on the input movement command. This makes the path of the measurement light independent of the processing beam path, and the relative positional relationship between the processing beam and the measurement light is maintained.

Next, the keyhole depth measurement process using the OCT system 30 will be described with reference to FIG. 8. FIG. 8 is a schematic diagram showing the cross-section of the workpiece W during laser processing. FIG. 8 also shows a schematic diagram of the workpiece W, which is made up of workpiece A and workpiece B stacked together, being irradiated with a processing beam.

As shown in FIG. 8, the processing beam is applied to form a welded workpiece portion where workpiece A and workpiece B are welded, and a molten pool is formed, and the metal is vaporized to form a hole-like space. This space is the keyhole. The OCT system 30 measures the depth of this keyhole.

In this embodiment, the OCT system 30 performs distance measurement at a reference point located ahead of the processing beam, and then performs distance measurement at a measurement point. The reference point is the surface of the workpiece W (workpiece A), and the measurement point is the bottom of the keyhole. Measurements are periodically repeated in the order of reference point, measurement point, reference point, and measurement point until welding is completed. Therefore, measurements of the reference point and measurement point are performed alternately, not simultaneously. Note that multiple measurements may be performed at each of the reference point and measurement point.

In the lower part of Figure 8, the range where the keyhole depth can be measured is indicated with OK, and the range where it cannot be measured is indicated with NG. This means that when measuring the reference point, OCT measurement values indicating the keyhole depth cannot be obtained.

Since the distance between the processing head 12 and the workpiece W varies depending on the processing position and angle, etc., in order to obtain an accurate keyhole depth, it is preferable to measure the reference point, for example, every 0.1 mm to 0.5 mm. Typically, the pattern can be set to repeat after measuring the reference point 20 times, and then measuring the measurement point 300 times. The timing and number of times to measure the reference point can be changed as appropriate depending on the configuration of the laser processing device 1 and the workpiece W.

A measurement pattern in which reference points and measurement points are alternately measured is described below. Figure 9 is a diagram showing an example of performing keyhole bottom measurement based on the first measurement pattern. In Figure 9, the measurement range of the movement path (the straight line portion including the first side of the hexagon) is set as the range for measuring the keyhole bottom. In this range, the relative position from the processing beam irradiation position to the point where the keyhole bottom occurs is set as the relative OCT measurement position, so that the keyhole bottom can be reliably measured. Note that at the next side where the oscillation direction changes and the relative position where the keyhole bottom occurs changes, the position of the measurement light deviates from the keyhole bottom, so that measurement results other than the keyhole bottom are obtained, and the weld depth cannot be calculated correctly.

In the first measurement pattern, the measurement of the reference point and the measurement point are repeated alternately at a predetermined timing. However, in the range where the first keyhole bottom is measured in Figure 9, the timing for measuring the reference point occurs, so it is not possible to obtain OCT measurement values in this area.

Next, we will explain the second measurement pattern, which is different from the first measurement pattern. Figure 10 is a diagram showing an example of performing a measurement of the keyhole bottom based on the second measurement pattern. The content shown in Figure 10 is basically the same as Figure 9, and only the timing at which the measurement of the reference point and the measurement of the measurement point are repeated alternately is different.

In the second measurement pattern, the period and phase are aligned between the measurement position and the OCT operation. For example, the period can be obtained from the oscillation conditions included in the oscillation command to determine the second measurement pattern. This makes it possible to measure the keyhole bottom more reliably than the first measurement pattern in Figure 9, and makes it possible to measure the keyhole bottom every period.

Next, the analysis process by the calculation unit 35 of the OCT system controller 31 will be described. The calculation unit 35 performs filter processing on the OCT measurement values calculated based on the measurement values of the reference points and the measurement values of the measurement points as described above. Note that, in the example of FIG. 1, the calculation unit 35 is a configuration that the OCT system controller 31 has, but this is not limited to this. The calculation unit 35 may be disposed in the control device 20, or may be configured as a computer independent of the control device 20 and the OCT system controller 31.

FIG. 11 is a schematic diagram of a filter used in the analysis of OCT measurement values. FIG. 11 shows a graph in which OCT measurement values are plotted with the vertical axis representing depth and the horizontal axis representing time. The filter applied by the calculation unit 35 is normally used as preprocessing for detecting welding anomalies, but it is also possible to perform only preprocessing without performing anomaly detection, or only anomaly detection without performing preprocessing. In this embodiment, the analysis process can be performed using multiple filters. For example, the filter can be set to an algorithm based on the percentile method that is applied in chronological order.

In the percentile method, an analysis process is performed using a filter that uses index N and filter width M. In the point cloud located within the width of the number of reference points defined by filter width M, the data at the depth of index N from the bottom is set as the weld depth analysis point. Index N and filter width M are set according to the processing conditions, measurement results, etc. In this example, the filter width is set to 10 and the index to 3.

In this example, the third point from the bottom ((1) in FIG. 11) of the 10 points in the range (filter width) of the dashed-dotted filter i is adopted as the "weld depth analysis point". The third point from the bottom ((2) in FIG. 11) of the 10 points in the range (filter width) of the dashed-dotted filter ii is adopted as the "weld depth analysis point". The third point from the bottom ((3) in FIG. 11) of the 10 points in the range (filter width) of the two-dot-dash filter iii is adopted as the "weld depth analysis point". Similarly, the third point from the bottom ((4) in FIG. 11) of the 10 points in the range (filter width) of the dotted-dotted filter iv is adopted as the "weld depth analysis point", and similar processing is performed in sequence. As shown in the graph in FIG. 11, the calculation unit 35 obtains the analysis value of the keyhole bottom by performing processing to sequentially connect the adopted "weld depth analysis points".

The filter algorithm is not limited to the percentile method. Analysis may be performed using RoI (range-specified trimming) or both the percentile method and RoI. Furthermore, algorithms used for time-series data such as digital filters and machine learning can be used as filters. Similarly, there are no limitations on the method for detecting welding anomalies in filtered data or unfiltered data.

Here, a modified example of the analysis process will be described. Analysis process may be performed in which only the results of the timing when the bottom of the keyhole is the measurement position are extracted from the OCT measurement values, and the rest are discarded. With the configuration of this embodiment, there is data at timings where it is clearly noise, so by discarding the noise portion, it is possible to obtain only the desired measurement values.

The measurement may also be configured to measure a specified range around the keyhole, such as a line segment with a length. When obtaining the measurement value of the keyhole bottom, the measurement is performed only at one point at a fixed relative position from the irradiation position of the processing beam, so unless the relative position is an accurate value, it is not possible to obtain accurate results for the keyhole bottom. Therefore, by trial welding and measuring in a wide area prior to installation on a processing line, etc., the optimal relative position can be found in advance.

More specifically, the periphery of the keyhole can be measured using a line segment with a certain length, a position where the point cloud of the keyhole bottom can be measured periodically can be searched for, and then measurements can be performed at the position where the point cloud of the keyhole bottom can be measured periodically. In such a case, for example, OCT measurements can be performed on a 5 mm line segment to obtain the cross-sectional shape of the keyhole. If the keyhole is deepest 1 mm backward, that point can be used as the measurement point.

The laser processing device 1 of this embodiment described above provides the following effects.

The laser processing device 1 of this embodiment includes a laser light source for generating a processing beam, a processing head 12 including at least one laser light deflection mechanism 13 coupled to the laser light source 11 to irradiate the processing beam to the processing location of the workpiece W, a control device 20 (processing beam control device) for controlling the laser light deflection mechanism 13 and the laser light source 11, at least one measurement light deflection mechanism 34 optically coupled to the processing head 12, an OCT system controller 31 (measurement light control device) for controlling the measurement light deflection mechanism 34, and an OCT scanner 33 for obtaining a measurement value related to the depth of a keyhole generated near the processing location of the workpiece W during welding processing using the measurement light. The control device 20 controls the laser light deflection mechanism 13 based on a processing command for performing a periodic shape oscillation in at least one direction, and the OCT system controller 31 controls the measurement light deflection mechanism 34 based on a movement component in at least one direction that does not include oscillation, and obtains a measurement value by irradiating the measurement light at a fixed relative position with respect to the processing beam.

As a result, the OCT system is controlled based on the moving component, so measurements can be performed without complex control that takes into account the oscillation speed and frequency. In addition, since the moving component has a smaller change over time than the oscillation component of the processing beam path, control is not hindered even in a low-speed communication environment, and it can be used with communication devices that are low cost and have low communication capabilities. In addition, since there is no need for communication in accordance with the oscillation period, oscillation processing can be performed at a faster frequency. In addition, since the non-coaxial part of the processing beam is measured and the measurement value during oscillation is not used, the measurement value at the keyhole bottom can be obtained periodically. In laser welding that involves an oscillation operation, the movement speed of the processing beam differs depending on the oscillation position. Furthermore, there is a case where the processing beam is irradiated once at the intersection of the processing beam path and then irradiated again. For this reason, the state of the processing object (workpiece) differs depending on the oscillation position, which may cause the keyhole shape to become distorted and the measurement results to fluctuate greatly. In this regard, the laser processing device 1 of this embodiment performs measurements at the same position periodically, so stable measurement results can be obtained.

In addition, the control device 20 of this embodiment generates a processing command by superimposing a movement command that commands a movement component in at least one direction and an oscillation command that performs oscillation of a periodic shape, and the OCT system controller 31 controls the measurement light deflection mechanism 34 based on the movement command received from the control device 20. In this way, the movement command for generating the processing command of the control device 20 can be used to generate the path of the measurement light, and a laser processing device 1 can be realized that can perform accurate measurements near the processing area without adding complex controls or configurations.

The laser processing device 1 of this embodiment also has a calculation unit 35 that calculates a keyhole depth analysis value from the measurement value. This makes it possible to obtain an analysis value indicating the keyhole bottom from the periodic measurement value. Also, by filtering and analyzing the measurement value, it is possible to calculate a highly accurate analysis value.

In addition, the OCT system controller 31 of this embodiment periodically executes a measurement pattern in which distance measurements are performed one or more times at a reference point located preceding the irradiation position of the processing beam, and then distance measurements are performed one or more times at a measurement point at the keyhole position, and periodically obtains measurement values based on the difference in distance between the reference point and the measurement point. This makes it possible to obtain an accurate keyhole depth even if the distance between the processing head 12 and the workpiece W varies.

In addition, the OCT system controller 31 of this embodiment can align the period and/or phase of the measurement pattern and the oscillation operation so that the timing of measuring the measurement point and the timing of measuring during the oscillation operation match. This avoids a situation in which a measurement cannot be obtained due to timing mismatch, and allows measurements to be more reliably performed at the measurement point for each cycle.

In addition, in this embodiment, the processing head 12 and the measurement light deflection mechanism 34 are optically coupled so that the measurement light passes through the laser light deflection mechanism 13, and the processing beam and measurement light are irradiated through the laser light deflection mechanism 13. This causes the processing beam and measurement light to be deflected in the same way, and the measurement position (irradiation position) of the measurement light can be made to be subordinate to the irradiation position of the processing beam. The operating range of the measurement light deflection mechanism 34 can be suppressed, and a laser processing device with a simple configuration can be realized.

The above describes the laser processing device 1 of this embodiment, but it is not limited to the configuration of the above embodiment.

Next, a modified laser processing apparatus 1A will be described with reference to FIG. 12. FIG. 12 is a schematic diagram showing a part of the configuration of the modified laser processing apparatus 1A. FIG. 12 shows a processing head 112, a collimator optical system 101, a laser light deflection mechanism 113, a coupling device 102, a measurement light source 132, a measurement light deflection mechanism 134, and a focusing optical system 103 as part of the laser processing apparatus 1A.

The processing head 112 is equipped with a laser beam deflection mechanism 113. The laser beam deflection mechanism 113 is a first deflection optical system that adjusts the irradiation position of the processing beam. The laser beam deflection mechanism 113 reflects the processing beam, which has been converted into parallel light by the collimator optical system 101, to the coupling device 102, and the processing head 112 and the measurement beam deflection mechanism 134 are optically coupled.

The measurement light deflection mechanism 134 is a second deflection optical system that adjusts the irradiation position of the measurement light. The measurement light deflection mechanism 134 reflects the measurement light irradiated from the measurement light source 132 to the coupling device 102.

The coupling device 102 is a dichroic mirror. The processing beam and measurement light that pass through the coupling device 102 are irradiated onto the workpiece W through the focusing optical system 103.

In the modified example, the optical path of the processing beam and the optical path of the measurement light are different from those of the above embodiment, and the measurement position of the measurement light is independent of the irradiation position of the processing beam. FIG. 13 is a schematic diagram showing the movement trajectory of the processing beam and the movement trajectory of the measurement light of the modified laser processing device 1A. As shown in FIG. 13, the movement trajectory of the processing beam and the movement trajectory of the measurement light are different. In the example of FIG. 13, the measurement light is irradiated in a linear path with respect to the path of the processing beam based on the wobbling operation (oscillation). In this way, according to the modified laser processing device 1A, it is possible to generate a measurement light path (movement trajectory) that is not dependent on the oscillation operation. It can also be said that the processing head 112 and the measurement light deflection mechanism 134 are optically coupled downstream of the optical path of the laser light deflection mechanism 113.

As described above, in the modified example, the path of the measurement light merges with the path of the processing beam downstream of the laser light deflection mechanism 113, and the deflection of the processing beam and the measurement light are independent. This makes the irradiation position of the measurement light independent of the irradiation position of the processing beam. Even with this configuration, it is possible to generate a path of the measurement light that is not dependent on the oscillation motion and measure the keyhole bottom.

The following configuration can also be added to the above embodiment and modified examples. The control device 20 may be configured to obtain OCT measurement values as feedback information from the OCT system controller 31, and change processing beam commands such as output commands in real time based on this feedback information. This makes it possible to adjust the processing beam based on feedback information indicating the actual keyhole depth, even if the welding quality, such as the penetration depth, varies depending on the characteristics of the laser light source, deterioration of the laser light source, the outside air temperature, etc. Therefore, by adding this function, even more stable welding quality can be ensured.

In addition, as a preliminary step to laser processing, a function can be added in which the OCT system 30 measures the shape of the workpiece W and performs position correction (seam tracking) in advance. This makes it possible to deal with steps on the surface of the workpiece W and perform laser processing based on precise position control.

In addition, in the above embodiment, the path of the processing beam is generated by superimposing the movement command and the oscillation component, and the path of the measurement light is generated based on the movement command, but this configuration is not limited to this. For example, when a processing command including an oscillation component is generated, the path of the measurement light may be generated based on the movement component extracted by removing the oscillation component from the processing command including the oscillation component using a low-pass filter or the like.

Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible to these embodiments without departing from the gist of the present disclosure, or without departing from the gist of the present disclosure derived from the contents described in the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-mentioned embodiments, the order of each operation and the order of each process are shown as examples, and are not limited to these. The same applies when numerical values or formulas are used to explain the above-mentioned embodiments.

The following supplementary notes are further disclosed regarding the above embodiment and modified examples.
(Appendix 1)
A laser light source (11) for generating a processing beam;
a processing head (12, 112) coupled to the laser light source (11) and including at least one laser light deflection mechanism (13, 113) for irradiating the processing beam onto a processing location of a workpiece (W);
a processing beam control unit (20) for controlling the laser beam deflection mechanism (13, 113) and the laser beam source (11);
At least one measurement light deflection mechanism (34, 134) optically coupled to the processing head (12, 112);
a measurement light control unit (31) for controlling the measurement light deflection mechanism (34, 134);
and an optical coherence interferometer unit (33) for obtaining a measurement value relating to a keyhole depth generated near a processing location of the workpiece (W) during welding processing by using a measurement light,
The processing beam control unit (20)
Controlling the laser beam deflection mechanism (13, 113) based on a processing command for performing periodic oscillation in at least one direction;
The measurement light control unit (31)
controlling the measurement light deflection mechanism (34, 134) based on the movement component in the at least one direction not including the oscillation;
A laser processing device (1, 1A) that obtains the measurement value by irradiating the measurement light at a fixed relative position with respect to the processing beam.

(Appendix 2)
In the above laser processing apparatus (1, 1A),
The processing beam control unit (20)
generating the machining command by superimposing a movement command for commanding a movement component in at least one direction and a swing command for performing a swing of a periodic shape;
The measurement light control unit (31)
The measuring beam deflection mechanism is controlled based on the movement command received from the processing beam control unit (20).

(Appendix 3)
In the above laser processing apparatus (1, 1A),
A calculation unit (35) is provided for calculating an analytical value of the keyhole depth from the measured value.

(Appendix 4)
In the above laser processing apparatus (1, 1A),
The measurement light control unit (31)
periodically executing a measurement pattern in which distance measurement is performed at least once at a reference point at a position preceding the irradiation position of the processing beam, and then distance measurement is performed at least once at a measurement point at a keyhole position;
The measurement value is periodically obtained based on a difference in distance between the reference point and the measurement point.

(Appendix 5)
In the above laser processing apparatus (1, 1A),
The measurement light control unit (31)
The period and/or phase of the measurement pattern and the swinging motion can be matched so that the timing of measuring the measurement points coincides with the timing of measuring during the swinging motion.

(Appendix 6)
In the above laser processing apparatus (1),
The processing head (12) and the measurement light deflection mechanism (34) are optically coupled so that the measurement light passes through the laser light deflection mechanism (13), and the processing beam and the measurement light are irradiated through the laser light deflection mechanism (13).

(Appendix 7)
In the above laser processing apparatus (1A),
The path of the measurement light merges with the path of the processing beam downstream of the laser light deflection mechanism (113), and the deflections of the processing beam and the measurement light are independent.

1, 1A Laser processing device 11 Laser light source 12, 112 Processing head 13, 113 Laser light deflection mechanism 20 Control device (processing beam control unit)
31 OCT system controller (measurement light control unit)
33 OCT scanner (optical coherence interferometer unit)
34,134 Measurement light deflection mechanism 35 Calculation section

Claims (7)

a laser light source for generating a processing beam;
a processing head coupled to the laser light source and including at least one laser light deflection mechanism for irradiating the processing beam onto a processing location of a workpiece;
a processing beam control unit for controlling the laser beam deflection mechanism and the laser beam source;
At least one measurement light deflection mechanism optically coupled to the processing head;
a measurement light control unit for controlling the measurement light deflection mechanism;
an optical coherence interferometer unit for obtaining a measurement value relating to a depth of a keyhole generated near a processing portion of the workpiece during welding processing by using a measurement light;
The processing beam control unit includes:
Controlling the laser beam deflection mechanism based on a processing command for performing periodic oscillation in at least one direction;
The measurement light control unit includes:
controlling the measurement light deflection mechanism based on a movement component in the at least one direction not including the oscillation;
A laser processing device that obtains the measurement value by irradiating the measurement light at a fixed relative position with respect to the processing beam. The processing beam control unit includes:
generating the machining command by superimposing a movement command for commanding a movement component in at least one direction and a swing command for performing a swing of a periodic shape;
The measurement light control unit includes:
The laser processing apparatus according to claim 1 , further comprising: a measuring beam deflection mechanism that controls the measuring beam deflection mechanism based on the movement command received from the processing beam control unit. The laser processing device according to claim 1 or 2, further comprising a calculation unit that calculates a keyhole depth analysis value from the measured value. The measurement light control unit includes:
periodically executing a measurement pattern in which distance measurement is performed at least once at a reference point at a position preceding the irradiation position of the processing beam, and then distance measurement is performed at least once at a measurement point at a keyhole position;
4. The laser processing apparatus according to claim 1, wherein the measurement value is periodically obtained based on a difference in distance between the reference point and the measurement point. The measurement light control unit includes:
5. The laser processing apparatus according to claim 4, wherein the period and/or phase of the measurement pattern is synchronized with the oscillation motion so that the timing of measuring the measurement point coincides with the timing of measuring the oscillation motion. The laser processing device according to any one of claims 1 to 5, wherein the processing head and the measurement light deflection mechanism are optically coupled so that the measurement light passes through the laser light deflection mechanism, and the processing beam and the measurement light are irradiated through the laser light deflection mechanism. The laser processing device according to any one of claims 1 to 5, wherein the path of the measurement light merges with the path of the processing beam downstream of the laser light deflection mechanism, and the deflection of the processing beam and the measurement light are independent.

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