JP7568522B2 - Laser Processing Equipment - Google Patents

Description

The present invention relates to a laser processing device, and in particular to a laser processing device equipped with a processing head that irradiates a processing laser beam and a length measurement laser beam onto a workpiece from the same optical system.

Laser processing devices such as laser cutting machines, laser welding machines, and laser marking devices transmit laser light output from a laser oscillator, irradiate the workpiece, and perform a specified processing by moving the laser light and the workpiece relatively. One example of the relative movement between the laser light and the workpiece in such a laser processing device is a known device that scans the workpiece with the laser light using a galvanometer scanner equipped with a galvanometer mirror and a drive device that rotates the galvanometer mirror around a specified axis at the emission section (e.g., processing head, etc.) of the laser processing device.

When processing is performed using such a galvanometer scanner, the scanning area of the laser light (i.e. the irradiation range of the laser light) by the galvanometer scanner is limited, so a laser processing device is known in which a processing head including a galvanometer scanner is attached to a transport means such as a robot arm to broaden the irradiation range of the laser light. With such a laser processing device, the processing head can be easily handled even when the shape of the workpiece is complex, but there is a problem in that the irradiation point of the laser light may deviate from the target position depending on the movement accuracy of the transport means.

As an example of a laser processing device intended to solve such problems, for example, Patent Document 1 discloses a laser welding device having a laser irradiation device that irradiates a laser beam onto an object to be welded, and a moving device that can move the laser irradiation device relative to the object to be welded, and while the moving device moves the laser irradiation device relative to the object to be welded, the object to be welded is welded with the laser beam irradiated onto the object from the laser irradiation device. The moving device has a moving device control means that controls the laser irradiation device to move along a preset weld line of the object to be welded, and the laser irradiation device has an irradiation means that focuses the laser beam and irradiates it toward the object to be welded. A known laser welding device includes a moving means for moving the irradiation point of the laser light irradiated from the irradiation means on the welding object, and a laser irradiation device control means for controlling the movement of the irradiation point by the moving means, and the laser irradiation device control means includes a judgment means for judging whether there is a deviation between the irradiation point of the laser light irradiated on the welding object and the welding line, a first movement control means for controlling the movement means so that the irradiation point moves to the welding line when the judgment means judges that there is a deviation, and a second movement control means for controlling the movement means so that the irradiation point moves within a predetermined range from the welding line when the judgment means does not judge that there is a deviation. According to this laser welding device, when welding is performed by attaching a galvano scanner to the tip of a multi-axis robot, the laser light is always irradiated within a predetermined range from the welding line, and if a deviation occurs between the irradiation point of the laser light and the welding line, the irradiation point of the laser light can be returned to the welding line without stopping the irradiation of the laser light.

JP 2018-176164 A

In the technology for processing while tracking the irradiation point of the laser light along the processing path (weld line), as described above, many techniques are known that determine whether the irradiation point of the laser light is deviated from the expected processing path (for example, the processing path set in the processing program) by analyzing an image of the vicinity of the irradiation point acquired by an imaging means such as a camera. For example, in the laser processing device shown in the above-mentioned Patent Document 1, as a "determination means for determining whether there is a deviation between the irradiation point of the laser light irradiated to the welding object and the weld line", a seam tracking head is applied that arranges the field of view of a camera (for example, a CCD camera) including an imaging element coaxially with the laser light for processing, acquires the reflected light from the irradiation point of the laser light as a two-dimensional image with the imaging element, and determines the deviation of the workpiece or the irradiation point of the laser light based on the two-dimensional image.

When using such a judgment means, the two-dimensional image data is processed to extract "feature points" such as unevenness and edges of the workpiece, and the positional relationship between the workpiece and the irradiation point of the laser light is understood based on these feature points. At this time, since the acquired two-dimensional image is a collection of pixel data, image processing of the two-dimensional image data requires complex calculations. In particular, if the number of pixels in the two-dimensional image is increased with the intention of making a more precise judgment, the load on the image processing increases and the processing time related to the calculations also increases, which is a major problem when making a real-time judgment during processing.

Given these circumstances, there is a demand for laser processing equipment that can accurately extract feature points of a workpiece while reducing the burden on data processing.

A laser processing apparatus according to one aspect of the present invention includes a processing head that irradiates a processing laser beam and a length measurement laser beam onto a workpiece from the same optical system, a processing head transport mechanism that moves the processing head relative to the workpiece, and a control mechanism that controls the operation of irradiating the processing laser beam and the length measurement laser beam onto the workpiece. The processing head includes a sub-laser scanning mechanism that scans the optical axis of the length measurement laser beam, a superposition optical unit that is provided on the exit side of the sub-laser scanning mechanism and superimposes the processing laser beam and the length measurement laser beam, and a main laser scanning mechanism that is provided on the exit side of the superposition optical unit and scans the optical axis of the processing laser beam and the optical axis of the length measurement laser beam within a predetermined scanning area. The control mechanism is configured to include a main control unit that controls the operation of irradiating the processing laser beam to a processing point on a processing path based on a processing program, a feature point detection unit that detects feature points on the workpiece by scanning the length measurement laser beam on a predetermined scanning line within the scanning area, and a path correction unit that performs position correction of the processing path on the workpiece based on a difference between a virtual feature point based on the processing program and the detected feature point.

According to one aspect of the present invention, the control mechanism detects feature points on the workpiece by scanning the length measurement laser light on a predetermined scanning line within the scanning area of the main laser scanning mechanism, and performs position correction of the machining path on the workpiece based on the detected feature points, thereby reducing the data processing load and accurately extracting the feature points of the workpiece.

1 is a schematic diagram showing a configuration of a laser processing apparatus according to a first embodiment, which is a representative example of the present invention. 3A to 3C are schematic diagrams showing an example of a configuration of a machining head and a machining path setting operation according to the first embodiment. 5A to 5C are schematic diagrams illustrating an example of a feature point detection operation according to the first embodiment. 2 is a block diagram showing the relationship between a control mechanism and other components of the laser processing apparatus according to the first embodiment. FIG. 5A to 5C are schematic diagrams illustrating an example of feature point detection and path correction operations according to the first embodiment. 10A to 10C are schematic diagrams illustrating an example of detection of feature points and path correction operation according to a modified example of the first embodiment. 10A and 10B are schematic diagrams illustrating an example of feature point detection and path correction operations according to the second embodiment of the present invention. 13A and 13B are schematic diagrams illustrating an example of a feature point detection and path correction operation according to a modified example of the second embodiment. 13A to 13C are schematic diagrams illustrating an example of feature point detection and path correction operations according to the third embodiment of the present invention. 13A and 13B are schematic diagrams illustrating an example of feature point detection and path correction operations according to the fourth embodiment of the present invention. 13A to 13C are schematic diagrams showing an example of a surface shape detection and path correction operation in a machined area according to a modified example of the fourth embodiment.

Below, an embodiment of a laser processing device according to a representative example of the present invention will be described with reference to the drawings.

First Embodiment
Fig. 1 is a schematic diagram showing the configuration of a laser processing apparatus according to a first embodiment, which is a typical example of the present invention. Fig. 2 is a schematic diagram showing an example of the configuration of a processing head and a processing path setting operation according to the first embodiment. Fig. 3 is a schematic diagram showing an example of a feature point detection operation according to the first embodiment. Fig. 4 is a block diagram showing the relationship between a control mechanism and other components of the laser processing apparatus according to the first embodiment.

As shown in FIG. 1, the laser processing device 1 according to the first embodiment includes, as an example, a processing laser light source (oscillator) 10 that oscillates a processing laser light LP, a laser length measuring device 20 that oscillates a length measuring laser light LM and calculates the distance to the workpiece using the return light, a processing head 30 that irradiates the processing laser light LP and the length measuring laser light LM toward the workpiece W while scanning, a processing head transport mechanism 40 that moves the processing head 30 relative to the workpiece W, a workpiece holding mechanism 50 that holds the workpiece W, and a control mechanism 100 that is connected to these components and controls the operation of each of them. The laser processing device 1 performs a predetermined processing (remote processing) such as welding, cutting, drilling, marking, etc., by concentrating and scanning the processing laser light LP on the processing point FP of the workpiece W held on the workpiece holding mechanism 50.

The processing laser light source 10 oscillates a processing laser light LP for processing a workpiece W, and outputs the processing laser light LP to a processing head 30 via a transmission path 12 such as an optical fiber and an optical connector 14. The wavelength and output of the processing laser light source 10 are determined in consideration of the absorption rate of the workpiece W. Examples of such an oscillator include a YAG laser, a _YVO4 laser, a fiber laser, a disk laser, and the like that are capable of fiber transmission.

The laser length measuring device 20 oscillates a length measuring laser light LM that is irradiated onto the surface of the workpiece W and calculates the distance to the workpiece W using the return light reflected by the workpiece W. For example, the length measuring laser light LM is output to the processing head 30 via a transmission path 22 such as an optical fiber and an optical connector 24. Examples of such a laser length measuring device 20 include one that calculates the distance to the workpiece W based on the interference when a reference light oscillated from an oscillator is superimposed on the return light reflected from the workpiece W, and one that calculates the distance to the workpiece W based on the time from the emission time of the length measuring laser light LM to the return time. Examples of the length measuring laser light LM include visible light that can be transmitted through fiber, such as a semiconductor laser (LD).

As shown in FIG. 2(a), the processing head 30 includes a sub-laser scanning mechanism 32 that scans the optical axis of the length measurement laser light LM, a superimposing optical unit 34 provided on the exit side of the sub-laser scanning mechanism 32 that superimposes the processing laser light LP and the length measurement laser light LM, a main laser scanning mechanism 36 provided on the exit side of the superimposing optical unit 34 that scans the optical axis of the processing laser light LP and the length measurement laser light LM within a predetermined main scanning region SR, and an irradiation unit 38 arranged on the exit side of the main laser scanning mechanism 36 that irradiates the processing laser light LP and the length measurement laser light LM onto the workpiece W. With this configuration, the laser processing device 1 can move the irradiation point (focus point) FP of the processing laser light LP to any position within a predetermined main scanning region SR, as shown in FIG. 2(b), and can also move the length measurement laser light LM independently of the processing laser light LP within a length measurement scanning region MR set near the irradiation point FP of the processing laser light LP. The processing head 30 may also be equipped with a known configuration such as a cooling mechanism for cooling various built-in optical systems.

The secondary laser scanning mechanism 32 and the primary laser scanning mechanism 36 include a mirror that totally reflects the incident processing laser light LP or length measurement laser light LM, and have the function of moving (scanning) the optical axis of the processing laser light LP and/or length measurement laser light LM by swinging the mirror at a small angle. Examples of such laser scanning mechanisms include a galvanometer scanner as shown in FIG. 2(a), which rotates a total reflection mirror around a specified galvanometer motor axis to swing it to any angle, or a piezoelectric scanner, which attaches a total reflection mirror to an actuator that uses a piezoelectric film and finely adjusts the angle of the total reflection mirror by passing electricity through it.

2(a), the superimposing optical unit 34 is composed of a superimposing optical system 34a that totally reflects the processing laser light LP while transmitting the length measurement laser light LM, and a focusing optical system 34b that is arranged downstream and focuses the superimposed processing laser light LP and length measurement laser light LM to a predetermined beam diameter. Here, examples of the superimposing optical system 34a include a half mirror or a beam splitter that has the function of reflecting or transmitting the incident light depending on the wavelength of the light.

The irradiation unit 38 is an optical system that focuses the processing laser light LP and length measurement laser light LM deflected by the main laser scanning mechanism 36 to a predetermined position on the workpiece W, and is configured as a combination of, for example, a focusing lens and an fθ lens. The irradiation unit 38 also functions as a lid that seals the inside of the processing head 30. Alternatively, the irradiation unit 38 may be configured as a flat window, and focused on the workpiece W only by the focusing optical system 34b.

In such a processing head 30, the processing laser light LP enters from the transmission path 12 via the optical connector 14, is totally reflected by the superposition optical system 34a of the superposition optical unit 34, and is then focused by the focusing optical system 34b. The optical axis is then deflected to an arbitrary angle (position) by the main laser scanning mechanism 36, and is emitted via the irradiation unit 38. As a result, the processing laser light LP is irradiated so as to be focused on an arbitrary processing point FP in the two-dimensional main scanning region SR of the main laser scanning mechanism 36, as shown in FIG. 2(b).

Meanwhile, the measurement laser light LM enters through the optical connector 24 from the transmission path 22, and after the optical axis is deflected to an arbitrary angle (position) by the secondary laser scanning mechanism 32, it passes through the superposition optical system 34a and is focused by the focusing optical system 34b, and then the optical axis is further deflected to an arbitrary angle (position) by the main laser scanning mechanism 36 and is emitted through the irradiation unit 38. As a result, the measurement laser light LM is irradiated so as to focus on an arbitrary measurement point (see FM1 or FM2 in FIG. 2(a)) in the two-dimensional measurement scanning region MR set near the irradiation point FP of the processing laser light LP, as shown in FIG. 2(b).

The measurement laser light LM irradiated to the workpiece W is reflected by the surface of the workpiece W toward the processing head 30, and passes from the irradiation unit 38 through the main laser scanning mechanism 36, the superimposition optical unit 34, and the sub-laser scanning mechanism 32, and returns from the processing head 30 to the laser length measuring device 20. The laser length measuring device 20 then calculates the distance to the workpiece W using the return light of the measurement laser light LM, as described above. This allows the laser processing device 1 to obtain the distance to the surface of the workpiece W (the irradiation point of the measurement laser light LM) at any position within the measurement scanning region MR located near the irradiation point FP of the processing laser light LP.

The machining head transport mechanism 40 is, for example, configured as a 6-axis or 7-axis industrial robot equipped with a robot arm 42 at at least its tip. The machining head 30 is attached to the tip of the robot arm 42, and the machining head 30 is moved to any position and angle within the rotation range.

As an example, the workpiece holding mechanism 50 includes a chuck mechanism (not shown) for mounting the workpiece W, and grips and fixes the workpiece W. The workpiece holding mechanism 50 may also include a rotation mechanism in addition to a mechanism for moving the workpiece W in three axial directions of X, Y, and Z.

The control mechanism 100 for controlling the operation of the laser processing device 1 according to the first embodiment includes a main control unit 110 for controlling the operation of irradiating the processing laser light LP to the processing point FP on the processing path based on the processing program, a feature point detection unit 120 for detecting the feature point SP (see FIG. 5, etc.) on the workpiece W by scanning the measurement laser light LM within the measurement scanning region MR, and a path correction unit 130 for correcting the position of the processing path PR (see FIG. 5, etc.) on the workpiece W based on the detected feature point SP, as shown in FIG. 4. The control mechanism 100 is connected by wire or wirelessly to the processing laser light source 10, laser length measurement device 20, processing head 30, processing head transport mechanism 40, and workpiece holding mechanism 50 shown in FIG. 1, and controls the operation of the laser processing device 1 by exchanging signals with these peripheral devices.

As an example, the main control unit 110 extracts information on the processing path from the processing program, and transmits a scanning command signal to the processing head 30 and the processing head transport mechanism 40 to instruct the position of the irradiation point FP of the processing laser light LP, and also extracts processing conditions from the processing program and transmits an output command signal to the processing laser light source 10 to instruct the output of the processing laser light LP, etc. The main control unit 110 also instructs the feature point detection unit 120 to execute a measurement program (which may be a subprogram included in the processing program) that scans the measurement laser light LM within the measurement scanning region MR located near the irradiation point FP of the processing laser light LP. Furthermore, the main control unit 110 also has a function of changing the above-mentioned scanning command signal based on path correction information from the path correction unit 130 described later.

Based on the distance data to the workpiece W acquired by the laser length measuring device 20, the feature point detection unit 120 detects feature points SP (e.g., welding grooves, ends of ridges and valleys of the workpiece, convex parts formed on the workpiece, etc.) due to the geometric factors of the workpiece W on a predetermined scanning line L. Specifically, as shown in FIG. 3, within the length measurement scanning region MR, the irradiation point FM of the length measurement laser light LM is scanned on a predetermined scanning line, and the position where a large change occurs in the continuous distance data to the workpiece W along the scanning line is detected as the feature point SP (i.e., the position of the processing line ML). In this case, if the irradiation point FP of the processing laser light LP is set to be located at the center of the scanning direction of the length measurement scanning region MR, for example, when the characteristic point SP is detected at approximately the center of the position within MR as in FIG. 3(b), it can be determined that the processing laser light LP is at approximately the same position as the processing line ML. For example, when the characteristic point SP is detected at a position shifted from the center on the scanning line as in FIG. 3(a) or FIG. 3(c), it can be determined that the amount of shift corresponds to the distance between the processing line ML and the processing laser light LP.

The path correction unit 130 corrects the position (e.g., the start and end points) of the processing path PR of the laser processing to be performed on the workpiece W based on multiple feature points (e.g., SP1, SP2) detected by the feature point detection unit 120. Specifically, for example, for a processing path PR' assumed within the main scanning region SR, the line passing through feature points SP1 and SP2 indicating the position of the processing line WL of the workpiece W detected on the two scanning lines L1 and L2 is determined to be the actual processing path PR. The path correction unit 130 then sends information about the processing path PR determined based on the above feature points to the main control unit 110.

The detection operation of the feature point detection unit 120 for detecting the feature point SP is performed by moving the measurement scanning region MR on the scanning line L1 based on the processing program, as shown in FIG. 3. At this time, the irradiation point FM of the measurement laser light LM is scanned along the scanning line L1 within the measurement scanning region MR.

As an example of measurement using the length measurement laser light LM, when the length measurement scanning area MR is moved at 100 mm/s, the irradiation point FM of the length measurement laser light LM is scanned back and forth at a high speed of 5000 mm/s. If the length of the scanning line of the length measurement laser light LM is, for example, 5 mm, data can be obtained once every 2 ms. Therefore, in terms of the scanning speed of the length measurement scanning area MR, i.e., the irradiation point FP of the processing laser light LP, data of the length measurement laser light LM can be obtained once every 0.2 mm.

Figure 3 (a) shows the case where the processing line ML is detected in the first half of the scanning direction of the measurement scanning region MR. In this case, the feature point SP is detected as a change point of the detection position (height) in the first half of the scanning direction position (horizontal direction in Figure 3 (a)) of the measurement scanning region MR.

Figure 3 (b) shows a case where the processing line ML is detected in the middle of the scanning direction of the length measurement scanning region MR. In this case, the feature point SP is detected as a change point of the detection position (height) in the center part of the scanning direction position of the length measurement scanning region MR.

Figure 3 (c) shows the case where the processing line ML is detected in the latter half of the scanning direction of the measurement scanning region MR. In this case, the feature point SP is detected as a change point of the detection position (height) in the latter half of the scanning direction position of the measurement scanning region MR.

For these reasons, the position of the processing line ML can be determined with high precision from the positional relationship between the measurement scanning region MR and the characteristic point SP of the measurement laser light LM detected within it. If multiple measurement data such as those shown in Figures 3(a) to 3(c) are used, the position of the processing line ML can be detected with even higher precision.

Next, a specific example of the path correction operation by the control mechanism 100 in the laser processing device 1 according to the first embodiment will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram showing an example of the detection of characteristic points and the path correction operation according to the first embodiment. Also, Figure 6 is a schematic diagram showing an example of the detection of characteristic points and the path correction operation according to a modified example of the first embodiment.

The laser processing device 1 according to the first embodiment can detect and correct the position of the groove (weld line) when two plate-shaped workpieces W1 and W2 are butt-welded. For example, as shown in FIG. 5(a), when the actual positions of the workpieces W1 and W2 are shifted from the positions of the workpieces W1' and W2' assumed in the processing program, the main control unit 110 issues a command to scan the length measurement laser light LM along two scanning lines L1 and L2 that cross the groove, and detects the distance to the workpiece W based on the return light on each scanning line.

As an example, the measured distance data to the workpiece W is measured in the manner shown in FIG. 5(b). Here, the horizontal axis indicates the position on the scanning lines L1 and L2, and the vertical axis indicates the measured distance to the workpiece W. For example, when scanning a flat plate material with the length measurement laser light LM, the same distance is measured.

In other words, in the feature point detection unit 120, the position of the processing line (groove) WL of the workpieces W1 and W2 is detected by changing the detection value (distance from the top in the figure) from the surrounding positions. As a result, the feature point detection unit 120 also has the function of detecting the surface shape of the workpieces W1 and W2 based on the measurement data continuously acquired on the scanning line L1 or L2.

Then, the feature point detection unit 120 detects, as feature points SP1 and SP2, points of change in distance from the actually measured workpiece W to virtual feature points SP1' and SP2' (i.e., two points on the groove) assumed based on the assumed positions of the workpieces W1' and W2' on the scanning lines L1 and L2, respectively. This allows the feature points SP1 and SP2 to be identified as positions shifted by D1 and D2, respectively, from the virtual feature points SP1' and SP2' assumed on the scanning lines L1 and L2.

Then, as shown in FIG. 5(c), the path correction unit 130 performs path correction based on the deviation amounts D1 and D2 on the scanning lines L1 and L2 described above, assuming that the actual workpieces W1 and W2 are positioned at the solid line positions shown in the figure, with the line segment connecting the two characteristic points SP1 and SP2 as the groove. Note that FIG. 5 illustrates an example in which the measurement laser light LM is scanned on the two scanning lines L1 and L2 to detect the two characteristic points SP1 and SP2, but if it is sufficient to extract only the deviation of the representative point of the workpiece W, it is also possible to detect one characteristic point on one scanning line and correct the machining path based on the deviation amount.

In addition, the path correction operation of the laser processing device 1 according to the first embodiment can also be applied, as a modified example, to the control operation in stitch welding (partial welding) of the overlapped fillet along the processing line (overlapped portion) WL of two plate-shaped workpieces W1 and W2. For example, as shown in FIG. 6(a), the main control unit 110 first acquires data of the virtual processing line WL' and the virtual processing path PR' along it based on the processing program, and sets the main scanning area SR so that the virtual processing line WL' is approximately in the center. Next, the main control unit 110 issues a command to scan the length measurement scanning area MR along two scanning lines L1 and L2 that cross the virtual processing line WL', and measures the distance data to the workpiece W based on the return light on each scanning line.

The measured distance data to the workpiece W is measured, for example, in the manner shown in FIG. 6(b) and sent to the feature point detection unit 120. The feature point detection unit 120 then detects the points of change in the actually measured distance to the workpiece W on each of the scanning lines L1 and L2 as feature points SP1 and SP2, and sends the detection results to the path correction unit 130.

The path correction unit 130 receives data of the virtual processing line WL' from the main control unit 110 in advance, and sets virtual feature points SP1', SP2' as the intersections of the virtual processing line WL' and the scanning lines L1, L2. The path correction unit 130 then calculates the differences D1, D2 on the scanning lines L1, L2 between the feature points SP1, SP2 detected by the feature point detection unit 120 and the virtual feature points SP1', SP2'. As a result, the feature points SP1, SP2 can be identified as positions shifted by D1, D2, respectively, from the virtual processing line WL' on the scanning lines L1 and L2.

Next, as shown in FIG. 6(c), the path correction unit 130 determines that the actual processing line WL is a line segment connecting the two characteristic points SP1, SP2 based on the deviation amounts D1 and D2 on the scanning lines L1 and L2. Then, the path correction unit 130 performs path correction to set the previously assumed virtual processing path (weld line) PR' of the lap fillet weld to the processing path PR along the actually detected processing line WL.

In this case, as an example, the angle or rotation angle between the line segment connecting the virtual feature points SP1' and SP2' and the line segment connecting the detected feature points SP1 and SP2 is calculated, and the machining path PR rotated from the virtual machining path PR' can be obtained based on the angle. In the specific example shown in FIG. 6, the case where two feature points SP1 and SP2 are detected along two parallel scanning lines L1 and L2 and the path is corrected is illustrated, but if it is sufficient to extract only one point such as the start point or end point of the machining path PR and perform a rough correction, a method of detecting the feature point SP1 on the scanning line L1 passing through the start point or end point of the machining path PR and correcting the position of the start point or end point may be used.

By using such control operations, the laser processing device 1 according to the first embodiment of the present invention can easily and accurately detect the characteristic points SP1, SP2 of the workpiece W by scanning the length measurement scanning region MR, where the length measurement laser light LM is irradiated, on predetermined scanning lines L1, L2 within the main scanning region SR of the main laser scanning mechanism 36 and acquiring distance data from the workpiece W based on the returned light. This makes it possible to handle a smaller amount of data than in conventional operations for detecting the characteristic points of the workpiece using two-dimensional images.

With the above-mentioned configuration, the laser processing device according to the first embodiment has a control mechanism that detects feature points on the workpiece by scanning the length measurement laser light within the scanning area of the main laser scanning mechanism, and corrects the position of the processing path on the workpiece based on the detected feature points, thereby reducing the data processing load and accurately extracting the feature points of the workpiece.

Second Embodiment
Fig. 7 is a schematic diagram showing an example of the detection of feature points and the path correction operation according to the second embodiment of the present invention. Fig. 8 is a schematic diagram showing an example of the detection of feature points and the path correction operation according to the second embodiment of the present invention. In the second embodiment, in the schematic diagrams shown in Figs. 1 to 6, the same reference numerals are used for those components that may be the same as or in common with the first embodiment, and repeated description of these components will be omitted.

The path correction operation of the laser processing device 1 according to the second embodiment is, for example, applied to a case where the position of the processing path is corrected based on multiple feature points detected on multiple scanning lines that intersect with each other. For example, FIG. 7 shows a case where processing paths PR1 and PR2 are set on each side near the end of a rectangular workpiece W1.

At this time, as shown in FIG. 7(a), for example, by scanning the length measurement scanning region MR on the scanning line L1 that passes through the start point of the virtual machining path PR' and performing measurements, the positions of the virtual feature point SP1' and the feature point SP1 can be identified on the scanning line L1, as in the first embodiment. Then, by calculating the difference D1 between these virtual feature points SP1' and SP1, the position of the virtual machining path PR' is corrected to the machining path PR that has been moved parallel along the scanning line L1.

As shown in FIG. 7(b), for example, by scanning the measurement scanning area MR on two scanning lines L1 and L2 that pass through the start point and end point of the virtual machining path PR', the positions of the virtual feature points SP1' and SP2' and the feature points SP1 and SP2 can be identified on the scanning lines L1 and L2, respectively. Then, by calculating the differences D1 and D2 between these virtual feature points SP1', SP2' and the feature points SP1 and SP2, respectively, the virtual machining path PR' is corrected to the machining path PR whose start point and end point have moved along the outer edge of the workpiece W1, and machining can be performed with higher accuracy.

On the other hand, as shown in FIG. 7(c), for example, by scanning the measurement scanning region MR on the above-mentioned scanning lines L1, L2 and the scanning line L3 perpendicular thereto, the positions of the virtual feature points SP1'-SP3' and the feature points SP1-SP3 are identified on the scanning lines L1-L3, respectively. At this time, since the scanning line L3 is perpendicular to L1 or L2, the rotation angle of the workpiece W1 can be calculated based on the differences D1-D3 on these scanning lines. Then, the path correction unit 130 can perform position correction not only for the machining path PR1 but also for the machining path PR2 that does not contact the scanning lines based on the calculated rotation angle of the workpiece W1.

As a modified example of the laser processing device 1 according to the second embodiment, the present invention can also be applied to the control operation of multiple processing positions (processing paths) on a workpiece having a curved surface. For example, as shown in FIG. 8(a), when marking processing is performed at two processing positions on the top surface of a workpiece W1 that is circular when viewed from above, the main control unit 110 sets the main scanning region SR so that the center of the workpiece W1 is approximately at the center, issues a command to scan the length measurement scanning region MR along three scanning lines L1 to L3 that cross the outer periphery of the workpiece W1, and continuously measures the distance to the workpiece W based on the return light on each scanning line.

The measured distance data from the workpiece W1 is measured, as an example, in the manner shown in FIG. 8(b), and based on this measurement data, the feature point detection unit 120 detects the points of change in the actually measured distance from the workpiece W on each of the scanning lines L1 and L2 as feature points SP1 to SP3. As a result, since the position of the outer periphery of the workpiece W1 is set by the machining program, the feature points SP1 to SP3 can be identified as positions shifted by D1 to D3, respectively, from the virtual feature points SP1' to SP3' on the virtual workpiece W1' assumed on the scanning lines L1 to L3.

In this case, since the circle passing through the three different points can be determined to be one, the path correction unit 130 determines that the actual outer periphery of the workpiece W1 is a circle passing through the three characteristic points SP1 to SP3, based on the deviation amounts D1 to D3 on the scanning lines L1 to L3, as shown in FIG. 8(c). Then, the path correction unit 130 performs path correction to set a processing path for marking processing using the processing laser light LP at each of the multiple processing positions PR1 and PR2 on the identified top surface of the workpiece W1.

By performing the above-described control operation, the laser processing device according to the second embodiment, in addition to the effects described in the first embodiment, can accurately grasp the actual work position relative to the virtual work position by correcting the processing path based on feature points detected on multiple intersecting scanning lines, making it possible to perform path correction on the processing path even for a workpiece having a shape with a curved surface, for example. Path correction can also be performed for multiple processing positions on the workpiece.

Third Embodiment
9 is a schematic diagram showing an example of the detection of feature points and the path correction operation according to the third embodiment. In the third embodiment, in the schematic diagrams shown in FIGS. 1 to 6, the same or common configurations as those in the first embodiment are denoted by the same reference numerals and the repeated description thereof will be omitted.

In the laser processing device 1 according to the third embodiment, a function can be added that allows the feature point detection unit to perform path correction even when the feature point cannot be detected due to some abnormality on the surface of the workpiece being processed. For example, as shown in FIG. 9(a), the main control unit 110 sets the main scanning region SR so that the processing line (overlapped portion) WL of two overlapping plate-shaped workpieces W1 and W2 is located approximately in the center, issues a command to scan the length measurement scanning region MR along two scanning lines L1 and L2 that cross the processing line WL, and continuously measures the distance to the workpiece W based on the return light on each scanning line.

At this time, if there is an abnormal area AR due to some abnormality (such as surface dirt or large deformation) on the surface of the workpieces W1 and W2 located on the scanning line L2, the measured distance data to the workpiece W is measured in the manner shown in Figure 9 (b). That is, although the characteristic point SP1 can be detected normally on the scanning line L1, on the scanning line L2, the measurement laser light LM cannot be reflected normally in the measurement scanning area MR due to some abnormality on the surface of the workpieces W1 and W2, so the distance data to the workpieces W1 and W2 becomes discontinuous (or becomes zero) in the range corresponding to the abnormal area AR.

In the laser processing device 1 according to the third embodiment, when the measurement data of the workpieces W1 and W2 based on the return light of the length measurement laser light LM includes an abnormal area AR, the characteristic point detection unit 120 sends only information on the characteristic point SP1 on the scanning line L1 that was detected normally to the path correction unit 130. Then, as shown in FIG. 9(c), the path correction unit 130 determines that the actual processing line WL passes through at least the characteristic point SP1 based on the deviation amount D1 on the detected scanning line L1, and performs path correction to set the processing path PR to one that changes only the scanning line L1 side of the assumed processing path (weld line) PR' of the lap fillet welding assumed in the processing program. This path correction operation is also the same when the characteristic point can be detected only on the scanning line L2 side.

By performing the above-described control operation, the laser processing device according to the third embodiment, in addition to the effects described in the first embodiment, is able to perform path correction that reflects only the measurement data that was successfully acquired when it is determined that the measurement data obtained using the measurement laser light was not successfully acquired.

Fourth Embodiment
Fig. 10 is a schematic diagram showing an example of the detection of feature points and the path correction operation according to the fourth embodiment of the present invention. Fig. 11 is a schematic diagram showing an example of the detection of the surface shape in the processed area and the path correction operation according to a modified example of the fourth embodiment. In the fourth embodiment, in the schematic diagrams shown in Figs. 1 to 6, the same reference numerals are used for those components that can be the same as or in common with the first embodiment, and the repeated description of these components is omitted.

In the first embodiment described above, the laser processing device 1 performs a processing path correction operation before irradiation of the processing laser light LP (i.e., before laser processing), but in the path correction operation of the laser processing device 1 according to the fourth embodiment, as an example, it can also be applied to a control operation that corrects the command position of the irradiation point of the processing laser light LP during irradiation by detecting a feature point using the length measurement laser light LM within the length measurement scanning region MR during irradiation of the processing laser light LP (i.e., during laser processing). In other words, the path correction operation by the laser processing device 1 of the present invention can be performed as feedback control during laser processing.

For example, as shown in FIG. 10(a), the main control unit 110 sets the main scanning area SR so that the processing line (overlapped portion) WL of two overlapping plate-shaped workpieces W1 and W2 is located approximately in the center, and issues a command to scan the irradiation point FP of the processing laser light LP along the processing path PR based on the processing program. At the same time, the main control unit 110 issues a command to scan the irradiation point FM of the measurement laser light LM in a direction intersecting the processing path PR within the measurement scanning area MR set near the irradiation point FP of the processing laser light LP, and continuously measures the distance to the workpieces W1 and W2 based on the return light on each scanning line.

At this time, the distance measurement data by the measurement laser light LM at a predetermined position on the processing path PR is acquired, for example, in the manner shown on the right side of Figures 10(b) to 10(d). That is, the horizontal axis of the graph indicates the left-right position that intersects with the traveling direction of the processing laser light LP (measurement scanning region MR), and the vertical axis indicates the work surface height in the left-right direction.

With this configuration, in the laser processing device 1 according to the fourth embodiment, when the actual processing line ML crosses the virtual processing path PR' diagonally upwards to the right as shown in FIG. 10(b), for example, the position of the processing line ML (the point of change in detected height) is detected on the left side of the figure in the distance measurement data by the length measurement laser light LM. Therefore, the course of the actual processing path PR is changed to the direction (leftward from the current movement direction) corresponding to the detected position of the processing line ML (the difference in the scanning direction of the length measurement laser light LM).

Also, for example, as in FIG. 10(c), when the actual processing line ML is in approximately the same direction (coincides) with the virtual processing path PR', the position of the processing line ML (point of change in detected height) is detected in approximately the center of the figure in the distance measurement data by the length measurement laser light LM. Therefore, the processing direction of the current virtual processing path PR' is deemed to coincide with the direction of the detected processing line ML, and the course of the actual processing path PR is maintained as it is to continue processing.

Furthermore, for example, as shown in FIG. 10(d), when the actual processing line ML crosses the virtual processing path PR' diagonally downward to the right on the illustration, the position of the processing line ML (the point of change in detected height) is detected on the right side of the illustration in the distance measurement data by the length measurement laser light LM. Therefore, the course of the actual processing path PR is changed to the direction (to the right of the current movement direction) corresponding to the detected position of the processing line ML (the difference in the scanning direction of the length measurement laser light LM).

By repeatedly performing the above-mentioned operations during laser processing, a path correction operation can be performed as feedback control so that the irradiation point FP of the current processing laser light LP follows the processing line WL.

In addition, in the laser processing device 1 according to the modified example of the fourth embodiment, a function can be added in which the feature point detection unit detects the surface shape of the already processed area located within the main scanning region SR, where processing has already been completed, while changing the processing conditions. For example, as shown in FIG. 11(a), the main control unit 110 issues a command to perform a predetermined processing by irradiating the processing laser light LP to the irradiation point FP based on the processing program while moving in the processing direction PD within the main scanning region SR, which is set so that the processing line (overlapped portion) WL of two overlapping plate-shaped workpieces W1 and W2 is approximately in the center.

At the same time, the main control unit 110 issues a command to scan the irradiation point FM of the measurement laser light LM in a direction intersecting the processing path PR within the measurement scanning region MR set near the irradiation point FP of the processing laser light LP, and continuously measures the distance to the workpieces W1 and W2 based on the return light on each scanning line. Then, the control mechanism 100 executes processing control similar to the operation shown in FIG. 10 above.

The distance measurement data obtained by the measurement laser light LM at a predetermined position on the processing path PR in this configuration is acquired, for example, in the manner shown in FIG. 11(b). That is, the horizontal direction in the figure indicates the left-right position intersecting the traveling direction of the processing laser light LP (measurement scanning region MR), and the vertical direction indicates the work surface height across the left-right direction. According to this measurement data, it is possible to grasp the surface shape (or surface properties) of the workpieces W1, W2 including the processed region WB along the scanning line of the measurement laser light LM.

Then, based on the surface shape of the already-processed area grasped using the distance data from the workpiece W acquired as shown in Fig. 11(b), the main control unit 110 changes the processing conditions such as the output of the processing laser light LP and the processing speed. That is, the distance data (surface shape) from the workpieces W1 and W2 based on the return light of the length measurement laser light LM under normal conditions as shown in the upper part of Fig. 11(b) is acquired in advance, and this is compared with the actually measured distance data from the workpieces W1 and W2.

For example, when distance data such as that shown in the second row of FIG. 11(b) is acquired, it can be determined that excessive heat was input during welding because the processed area WB is wider than in the normal state. In such a case, the main control unit 110 can correct the processing path and change the processing conditions, for example, by reducing the output of the processing laser light LP, increasing the welding speed, or increasing the amount of filler material (welding wire) added, to ensure that an appropriate weld is made.

In contrast, when distance data such as that shown in the third row of FIG. 11(b) is acquired, it can be determined that the heat input during welding was insufficient because the processed area WB is narrower than in the normal state. In such a case, the main control unit 110 can correct the processing path and change the processing conditions, for example, by increasing the output of the processing laser light LP or slowing down the welding speed. Also, as in the case of FIG. 9, if the surface shape of the processed area WB is significantly disturbed or the surface shape cannot be measured normally, the path correction or processing itself may be stopped.

Furthermore, when processing the workpieces W1 and W2 while melting them, such as in laser welding, the measurement laser light LM is scanned in the area (the so-called molten pool) immediately after the passage of the processing laser light LP, to obtain distance data as shown in the fourth row (bottom row) of FIG. 11(b). At this time, when processing is performed by keyhole welding, for example, a keyhole (recess in the figure) KH can be obtained as the surface shape in the processed area WB. Therefore, the main control unit 110 can correct the processing path and change processing conditions such as the output of the processing laser light LP and the welding speed according to the shape and size of the keyhole KH.

By the above-mentioned control operation, the laser processing device according to the fourth embodiment can perform a correction operation of the processing path while the laser processing is in progress by performing a detection operation using the length measurement laser light during irradiation of the processing laser light (i.e., during processing), in addition to the effects described in the first embodiment. In addition, since it is possible to grasp the condition of the work surface during processing and the surface shape of the already processed area, it is possible to correct the path even if there is some abnormality on the work surface, and it is also possible to perform feedback control of the processing conditions.

The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the invention. Any of the components of the embodiment can be modified or omitted within the scope of the invention.

For example, in Figures 1 and 2, a case is illustrated in which the laser length measuring device is configured separately from the processing head and the measuring laser light is transmitted to the processing head via a transmission path, but a configuration in which the laser length measuring device is attached directly to the processing head using, for example, a known small laser sensor, etc. may also be adopted.

The specific examples shown in the first to fourth embodiments may be applied by combining their respective features. For example, it is possible to combine the path correction operation for a workpiece having a curved surface shown in the second embodiment with the feedback technology during irradiation of the processing laser light shown in the fourth embodiment.

Furthermore, the irradiation and detection operations of the measurement laser light LM described in the first to fourth embodiments can be executed simultaneously depending on the settings of the measurement program that causes the measurement laser light LM to scan within the measurement scanning region MR by the main control unit 110. As an example, if the measurement laser light LM is scanned at a scanning speed of about 5000 mm/s, measurements on two or more scanning lines can be completed within about 10 ms.

REFERENCE SIGNS LIST 1 Laser processing device 10 Processing laser light source 12 Transmission path 14 Optical connector 20 Laser length measuring device 22 Transmission path 24 Optical connector 30 Processing head 32 Sub-laser scanning mechanism 34 Superimposition optical unit 34a Superimposition optical system 34b Condensing optical system 36 Main laser scanning mechanism 38 Irradiation unit 40 Processing head transport mechanism 42 Robot arm 50 Workpiece holding mechanism 100 Control mechanism 110 Main control unit 120 Feature point detection unit 130 Path correction unit

Claims (8)

A laser processing apparatus including a processing head that irradiates a processing laser beam and a length measurement laser beam from a same optical system onto a workpiece, a processing head transport mechanism that moves the processing head relative to the workpiece, and a control mechanism that controls an operation of irradiating the processing laser beam and the length measurement laser beam onto the workpiece,
the processing head includes: a sub-laser scanning mechanism that scans the optical axis of the length measurement laser light; a superimposing optical unit that is provided on the emission side of the sub-laser scanning mechanism and that superimposes the processing laser light and the length measurement laser light; and a main laser scanning mechanism that is provided on the emission side of the superimposing optical unit and that scans the optical axis of the processing laser light and the optical axis of the length measurement laser light within a predetermined scanning area;
The control mechanism of the laser processing apparatus includes a main control unit that controls the operation of irradiating the processing laser light to a processing point on a processing path based on a processing program, a feature point detection unit that detects feature points on the workpiece by scanning the length measurement laser light on a predetermined scanning line within the scanning area, and a path correction unit that corrects the position of the processing path on the workpiece based on a difference between a virtual feature point based on the processing program and the detected feature point. The laser processing apparatus according to claim 1 , wherein the feature point detection unit further has a function of detecting a surface shape of the workpiece based on measurement data continuously acquired on the scanning line. The laser processing device according to claim 1 or 2 , wherein the path correction unit corrects the position of the processing path based on the feature points detected on a plurality of scanning lines. the feature point detection unit detects the feature points on a plurality of scanning lines and further has a function of sending only information on the feature points that have been normally detected to the path correction unit;
The laser processing device according to claim 3 , wherein the path correction unit further has a function of performing position correction of the processing path based on the normally detected feature points. the feature point detection unit detects the feature points during irradiation of the processing laser light,
The laser processing apparatus according to claim 1 or 2, wherein the path correction unit corrects the position of the processing path during irradiation of the processing laser light. The laser processing apparatus according to claim 5, wherein the feature point detection unit further has a function of detecting a surface shape of an already-processed area by scanning the length measurement laser light in an already-processed area that has already been processed by the processing laser light. 7. The laser processing apparatus according to claim 6 , wherein the main control unit further has a function of changing processing conditions for the processing laser light based on the surface shape of the already-processed area detected by the feature point detection unit. the feature point detection unit further has a function of sending information to the main control unit, when the feature point cannot be detected normally, that the feature point cannot be detected normally;
7. The laser processing apparatus according to claim 5 , wherein the main control unit further has a function of stopping irradiation of the processing laser light.

Images