JP2023108706A - Laser welding device and laser welding method - Google Patents

Abstract

To enable a weld-penetration depth of a deepest portion of a weld part to be accurately grasped, while laser-welding a work-piece.SOLUTION: An image fiber 30 has a plurality of cores 31 arranged with an interval from each other. The plurality of cores 31 are connected with a plurality of laser modules 15a respectively. First measurement light S1 is transmitted through the image fiber 30. Laser light L and the first measurement light S1 are concentrically superposed and then are emitted toward a work-piece 60. A light interferometer device 20 receives the first measurement light S1 reflected on the work-piece 60 to measure a weld-penetration depth of a weld part 65 of the work-piece 60. A control part 26 controls motion of the plurality of laser modules 15a so that the core 31 which emits the first measurement light S1 of the plurality of cores 31 is selectively switched, during laser welding of the work-piece 60.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laser welding device and a laser welding method.

In Patent Document 1, the object light can be applied to the bottom of the keyhole by making the spot diameter of the object light at the welded portion larger than the spot diameter of the laser light and irradiating the object light to substantially the entire area of the keyhole. A laser welding apparatus is disclosed.

Patent Document 2 discloses a laser device that measures the penetration depth in a wide range of the keyhole by changing the angle of a dichroic mirror provided in the laser head and scanning the inside of the keyhole with measurement light. is disclosed.

Japanese Patent No. 5252026 U.S. Patent No. 10413995

Here, in the invention of Patent Document 1, the resolution and the measurement area when measuring the penetration depth of the weld are determined according to the spot diameter of the object light. Therefore, it is difficult to further increase the resolution and expand the measurement area.

Moreover, in the invention of Patent Document 2, since the configuration for scanning the measurement light is mounted on the laser head, there is a problem that the size of the laser head and the robot increases.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and its object is to accurately grasp the penetration depth of the deepest portion of a welded portion during laser welding of a work.

A first invention is a laser welding apparatus for welding workpieces while emitting a laser beam along a predetermined welding direction, comprising: a laser oscillator for generating the laser beam; and a measuring beam having a wavelength different from that of the laser beam. and a plurality of cores respectively connected to the laser modules corresponding to the plurality of laser modules, wherein the measurement generated by the measurement light oscillator an image fiber that transmits light; a laser head that coaxially superimposes the laser light and the measurement light transmitted through the image fiber and emits the light toward the work; An optical interferometer device that receives measurement light and measures the penetration depth of a welded portion of the work, and selectively selects the core from among the plurality of cores that emits the measurement light during laser welding of the work. and a controller for controlling the operations of the plurality of laser modules so as to switch between them.

In the first invention, the image fiber has a plurality of cores spaced apart from each other. A plurality of laser modules are connected to each of the plurality of cores. Measurement light is transmitted through the image fiber. The laser light and the measurement light are coaxially superimposed and emitted toward the workpiece. The optical interferometer device receives the measurement light reflected by the work and measures the penetration depth of the welded portion of the work. The controller controls operations of the plurality of laser modules so as to selectively switch the core from which the measurement light is emitted out of the plurality of cores during laser welding of the workpiece.

In this way, by measuring the penetration depth of the welded part at multiple different positions during laser welding of the workpiece, the penetration depth of the deepest part of the welded part can be accurately grasped based on the results of multiple measurements. be able to.

In a second aspect based on the first aspect, the optical interferometer device has a detection section including an optical interference optical section and a differential signal generation section, and the control section, and the optical interference optical section includes: a beam splitter that splits the measurement light emitted from the laser module of the measurement light oscillator into a first measurement light and a second measurement light; and a mirror that reflects the second measurement light. The splitter and the mirrors are provided so as to correspond to the plurality of laser modules, and the differential signal generator divides the first measurement light reflected by the workpiece and the second measurement light reflected by the mirror into the received via a beam splitter to generate a difference signal indicating the phase difference between the optical path lengths of the first measurement light and the second measurement light; and a calculation unit for calculating the penetration depth of the welded portion of the workpiece based on the above.

In the second invention, by calculating the penetration depth of the welded portion of the workpiece based on the phase difference between the optical path lengths of the first measurement light and the second measurement light, the penetration depth can be measured with high accuracy. can.

In a third aspect based on the first or second aspect, the plurality of cores are radially arranged with intervals from the center of the image fiber toward the outer periphery, and the controller controls the measurement light. It is characterized in that the emission position is controlled to move along a spiral trajectory from the center of the image fiber toward the core on the outer periphery.

In the third invention, even when the welding direction is changed with the movement of the laser head, the measurement light can be continuously emitted over a wide range without switching the emission pattern of the measurement light.

In a fourth aspect based on the third aspect, the control unit changes the emission position of the measurement light from the center of the image fiber to the core of the outer peripheral portion in a spiral shape at the welding start position of the workpiece. While performing control to move along the trajectory, at the welding end position of the work, the emission position of the measurement light is moved along the spiral trajectory from the outer peripheral portion of the image fiber to the core at the center. It is characterized by performing control.

In the fourth invention, the deepest part of the penetration depth of the weld can be accurately grasped at the welding start position and the welding end position of the work.

Specifically, at the welding start position, the central part of the welded part of the workpiece melts first. can be accurately grasped.

In addition, at the welding end position, by moving the emission position of the measurement light from the outer periphery toward the center of the welded part of the workpiece and emitting the measurement light to the center of the welding end position, the deepest part of the penetration depth can be accurately grasped.

In a fifth invention based on the first or second invention, the plurality of cores are arranged at intervals in a direction intersecting the welding direction, and the controller controls the emission position of the measurement light to the welding direction. It is characterized by performing control to move along a direction intersecting with the direction.

In the fifth invention, the penetration depth of the welded portion can be measured while expanding the emission range of the measurement light by emitting the measurement light along the direction intersecting the welding direction.

In a sixth aspect based on the fifth aspect, the plurality of cores are arranged at intervals along the welding direction, and the control section adjusts the emission position of the measurement light along the welding direction to It is characterized by performing control to move.

In the sixth invention, the measurement light is emitted in a zigzag pattern not only in the direction intersecting the welding direction but also in the welding direction, so that the penetration depth of the weld can be measured while further expanding the emission range of the measurement light. can.

A seventh invention is characterized in that, in the sixth invention, the control section performs control to move the emission position of the measurement light from the downstream side toward the upstream side in the welding direction.

In the seventh invention, the weld penetration depth tends to be measured shallower on the upstream side in the welding direction than on the downstream side. Therefore, by measuring from the downstream side to the upstream side in the welding direction, the deepest portion of the penetration depth can be accurately measured.

In an eighth invention based on any one of the first to seventh inventions, the plurality of laser modules emit the measurement light of the same wavelength, and the control section directs the measurement light to the plurality of cores. It is characterized by performing control to emit from from at different timings.

In the eighth invention, the penetration depth of the weld zone can be measured while the measurement light emission range is gradually expanded by emitting the measurement light from the plurality of cores at different timings.

In a ninth aspect based on the first or second aspect, the plurality of laser modules emit the measurement light beams having wavelengths different from each other, and the controller simultaneously emits the plurality of measurement light beams from the plurality of cores. It is characterized by performing control to make

In the ninth invention, by simultaneously emitting a plurality of measurement lights having different wavelengths from a plurality of cores, the penetration depth of the welded portion at a plurality of different positions can be measured simultaneously.

In a tenth aspect based on any one of the first to ninth aspects, the control unit further includes a plurality of penetrations measured at mutually different positions in the welded portion of the workpiece by the optical interferometer device. The method is characterized in that three-dimensional data representing the shape of penetration in the weld is acquired based on the depth.

In the tenth invention, by acquiring three-dimensional data indicating the penetration shape of the welded portion, it becomes easier to grasp the penetration shape.

According to an eleventh invention, in the tenth invention, a display section for displaying the three-dimensional data acquired by the control section is provided.

In the eleventh invention, by displaying three-dimensional data representing the penetration shape of the weld on a monitor or the like, it becomes easier to visually grasp the penetration shape.

According to a twelfth invention, in the tenth or eleventh invention, the controller measures the bead width of the weld based on the acquired three-dimensional data.

In the twelfth invention, the bead width of the welded portion can be grasped based on the three-dimensional data indicating the penetration shape of the welded portion.

A thirteenth invention is a laser welding method for welding workpieces while emitting a laser beam along a predetermined welding direction, wherein the laser beam and a measuring beam having a different wavelength from the laser beam are generated by a plurality of laser modules. and coaxially transmitting the laser light and the measurement light transmitted through an image fiber having a plurality of cores respectively connected to the laser modules corresponding to the plurality of laser modules. A step of superimposing them in a shape and emitting them toward the work, a step of measuring the penetration depth of the welded portion of the work based on the measurement light reflected by the work, and during laser welding of the work, and a step of controlling operations of the plurality of laser modules so as to selectively switch the core from which the measurement light is emitted among the plurality of cores.

In the thirteenth invention, by measuring the penetration depth of the welded portion at a plurality of different positions during laser welding of the workpiece, the penetration depth of the deepest part of the welded portion can be accurately determined based on the plurality of measurement results. can grasp.

ADVANTAGE OF THE INVENTION According to this invention, the penetration depth of the deepest part of a welded part can be accurately grasped|ascertained during laser welding of a workpiece|work.

It is a figure which shows the structure of the laser welding apparatus which concerns on this Embodiment 1. FIG. FIG. 10 is a graph showing a state in which a penetration depth is calculated by performing fast Fourier transform processing on a detection signal of measurement light; It is a figure when an image fiber is seen from the incident end side. FIG. 4 is a diagram showing the relationship between the order of incidence of first measurement light on a plurality of cores and the welding direction; It is a figure which shows the state of the penetration depth measured by the 1st core to the 9th core. FIG. 4 is a diagram schematically showing three-dimensional data obtained by synthesizing penetration depths measured at a plurality of different positions; It is a figure which shows the three-dimensional data displayed on a display part. FIG. 9 is a diagram showing the relationship between the order of incidence of the first measurement light beams on a plurality of cores and the welding direction in a modification of Embodiment 1; It is a figure when the image fiber which concerns on this Embodiment 2 is seen from the incident end side. FIG. 4 is a diagram showing an emission pattern of measurement light at a welding end position; It is a figure when the image fiber which concerns on the modification of this Embodiment 2 is seen from the incident end side. FIG. 4 is a diagram showing an emission pattern of measurement light at a welding end position;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the following description of preferred embodiments is essentially merely an example, and is not intended to limit the present invention, its applications, or its uses.

<<Embodiment 1>>
As shown in FIG. 1, the laser welding device 1 includes a laser beam oscillator 10, a measurement beam oscillator 15, an optical interferometer device 20, an image fiber 30, a laser head 50, a robot 2, and a robot controller 16. and

A laser beam oscillator 10 generates a laser beam L. As shown in FIG. The laser light oscillator 10 is connected with the laser head 50 by the transmission fiber 11 . A laser beam L is transmitted from the laser beam oscillator 10 to the laser head 50 via the transmission fiber 11 .

The measurement light oscillator 15 has a plurality of laser modules 15a. A plurality of laser modules 15a generate measurement light S having a wavelength different from that of laser light L, respectively. A plurality of laser modules 15a emit measurement light S of the same wavelength. Note that the plurality of laser modules 15a may emit measurement light beams S having different wavelengths.

The measurement light S generated by the laser module 15 a of the measurement light oscillator 15 enters the optical interferometer device 20 . The wavelength difference between the laser light L and the measurement light S is preferably 100 nm or more.

The measurement light oscillator 15 continuously emits measurement light S having a wavelength different from that of the laser light L and having a short wavelength width, and periodically changes the center wavelength of the emitted measurement light S. The operation of periodically changing the central wavelength of the measurement light S in this way is called wavelength scanning.

The optical interferometer device 20 measures the penetration depth of the welded portion 65 of the workpiece 60 using the technique of Swept Source Optical Coherence Tomography (SS-OCT: wavelength scanning optical coherence tomography).

The optical interferometer device 20 has a detector 21 and a controller 26 . The detector 21 includes a light interference optical unit 22 and a differential signal generator 25 .

The light interference optical section 22 has multiple beam splitters 23 and multiple reference mirrors 24 . A plurality of beam splitters 23 and a plurality of reference mirrors 24 are provided so as to correspond to the plurality of laser modules 15a. The beam splitter 23 splits the measurement light S emitted from the laser module 15a of the measurement light oscillator 15 into a first measurement light S1 and a second measurement light S2.

The first measurement light S1 means the measurement light emitted to the welded portion 65 to be measured, and the second measurement light S2 means the measurement light emitted to the reference mirror 24 which is the reference plane. do.

The reference mirror 24 reflects the second measurement light S2. The second measurement light S<b>2 reflected by the reference mirror 24 is guided to the differential signal generator 25 . The first measurement light S1 enters the image fiber 30 via the coupler 20a. A plurality of couplers 20 a are provided corresponding to each of the plurality of beam splitters 23 . The first measurement light S is emitted to the welded portion 65 of the work 60 via the image fiber 30 and the laser head 50 . At this time, the first measurement light S1 is coaxially superimposed on the laser light L by the optical system in the laser head 50 .

A portion of the first measurement light S1 emitted to the welded portion 65 of the workpiece 60 is reflected by the welded portion 65 and enters the optical interferometer device 20 via the image fiber 30 . The first measurement light S1 that has entered the optical interferometer device 20 is reflected by the beam splitter 23 and enters the differential signal generator 25 .

Here, the optical path length of the first measurement light S1 is defined as the optical path length of the first measurement light S1 after passing through the beam splitter 23 and entering the differential signal generator 25 .

The second measurement light S2 is reflected by the beam splitter 23 and guided to the reference mirror 24 . The second measurement light S<b>2 guided to the reference mirror 24 is reflected by the reference mirror 24 and then enters the differential signal generator 25 .

Here, the length of the optical path through which the second measurement light S2 passes from being reflected by the beam splitter 23 to being incident on the difference signal generator 25 is defined as the optical path length of the second measurement light S2. The optical path length of the second measurement light S2 is measured in advance as a reference value.

Normally, the optical path length of the first measurement light S1 and the optical path length of the second measurement light S2 are adjusted in advance so as to be the same. For example, when the workpiece 60 does not melt, the reference mirror 24 is adjusted so that the two optical path lengths are the same.

At this time, the first measurement light S<b>1 and the second measurement light S<b>2 are combined into one light beam to form interference light, and a detection signal indicating the interference light is incident on the differential signal generation section 25 .

The difference signal generator 25 receives the first measurement light S1 reflected by the workpiece 60 and the second measurement light S2 reflected by the reference mirror 24, and calculates the phase difference between the optical path lengths of the first measurement light S1 and the second measurement light S2. to generate a differential signal indicative of

Specifically, the differential signal generator 25 has a differential detector 25a and an A/D converter 25b. The differential detector 25a removes the influence of noise contained in the interference light of the first measurement light S1 and the second measurement light S2. The differential detector 25a converts the noise-removed interference light into an electrical signal according to its intensity, and generates a differential signal indicating the phase difference between the optical path lengths of the first measurement light S1 and the second measurement light S2. (See Figure 2). The differential detector 25a outputs the generated differential signal to the A/D converter 25b.

A trigger output synchronized with the repetition frequency of wavelength scanning is input from the measurement light oscillator 15 to the A/D converter 25b. Based on the input trigger output, the A/D converter 25b synchronizes with the repetition period of the measurement light oscillator 15 and acquires the differential signal output from the differential detector 25a.

Interference occurs in the interference light according to the optical path length difference between the first measurement light S1 and the second measurement light S2. A difference signal indicating the phase difference between the optical path lengths of the first measurement light S1 and the second measurement light S2 is output to the calculation section 27 of the control section 26 . The calculation unit 27 calculates the penetration depth of the welded portion 65 of the workpiece 60 based on the input difference signal.

Specifically, the calculation unit 27 performs fast Fourier transform (FFT) processing on the input difference signal, and calculates the penetration depth of the welded portion 65 based on the processing result (see FIG. 2). ).

As shown in FIG. 3, the image fiber 30 has a plurality of cores 31, clads 32, and protective coatings 33. As shown in FIG. The image fiber 30 transmits the first measurement light S1 to the laser head 50. As shown in FIG.

The multiple cores 31 are arranged at intervals from each other. The example shown in FIG. 3 has a total of nine cores 31 arranged in 3 rows×3 columns. The core 31 is made of quartz glass, for example. In this embodiment, the diameter of the core 31 is set to 10 μm to 100 μm. The plurality of cores 31 are arranged corresponding to the plurality of laser modules 15a. The plurality of cores 31 are directly or indirectly connected to the plurality of laser modules 15a.

The clad 32 is made of, for example, fluorine-doped quartz glass. The clad 32 has a lower refractive index than the core 31 .

A protective coating 33 is provided on the outer periphery of the clad 32 . The protective film 33 is made of synthetic resin, for example. The protective film 33 mechanically protects the core 31 and the clad 32 made of quartz glass. The protective coating 33 prevents the first measurement light S1 from leaking from the image fiber 30 and light from the outside to the image fiber 30 from leaking.

The control unit 26 controls operations of the plurality of laser modules 15a. Specifically, the control unit 26 controls the operation of the plurality of laser modules 15a so as to selectively switch the core 31 that emits the first measurement light S among the plurality of cores 31 during laser welding of the workpiece 60. do. In this embodiment, the laser welding speed is 5 m/min.

The workpiece 60 has an upper plate 61 and a lower plate 62 which are vertically superimposed. The laser welding device 1 welds the upper plate 61 and the lower plate 62 by emitting a laser beam L to the upper surface of the upper plate 61 .

The laser head 50 has a first collimator lens 51 , a second collimator lens 52 , a dichroic mirror 53 , a condenser lens 54 and an XYZ stage 55 .

The first collimator lens 51 collimates the laser light L emitted from the emission end of the transmission fiber 11 . The second collimator lens 52 collimates the first measurement light S1 emitted from the emission end of the image fiber 30. As shown in FIG.

The XYZ stage 55 is arranged on the incident side of the second collimating lens 52 . The output end of the image fiber 30 is connected to the XYZ stage 55 . The XYZ stage 55 adjusts the incident position of the first measurement light S1 with respect to the dichroic mirror 53 .

The dichroic mirror 53 transmits the laser light L and reflects the first measurement light S1. The dichroic mirror 53 coaxially superimposes the laser light L and the first measurement light S1 and guides them to the condenser lens 54 .

The condensing lens 54 converges the laser light L and the first measurement light S1. The laser light L and the first measurement light S1 condensed by the condensing lens 54 are emitted to the workpiece 60 .

The condenser lens 54 also has a function of causing the first measurement light S<b>1 reflected from the welded portion 65 of the work 60 to enter the optical interferometer device 20 again via the dichroic mirror 53 .

The robot 2 has a robot arm 3 . A laser head 50 is attached to the tip of the robot arm 3 . The robot arm 3 has multiple joints 4 .

The robot 2 moves the laser head 50 along a predetermined welding direction and changes the position of the laser head 50 with respect to the workpiece 60 based on a command from the robot control unit 16 . As a result, the positions of the laser beam L and the first measurement beam S1 with respect to the workpiece 60 are moved to perform laser welding.

The robot controller 16 is connected to the laser beam oscillator 10 , the laser head 50 and the robot 2 . The robot control unit 16 controls operations of the laser beam oscillator 10 , the laser head 50 and the robot 2 . The robot control unit 16 has a function of controlling the movement speed of the laser head 50 as well as the start and stop of the output of the laser light L, the output intensity of the laser light L, and the like.

In the laser welding apparatus 1 , a laser beam L is emitted from above the work 60 to the upper surface of the upper plate 61 when welding the welded portion 65 of the work 60 having the upper plate 61 and the lower plate 62 .

The welded portion 65 irradiated with the laser beam L melts from its upper portion to form a molten pool. As the weld 65 melts, the molten metal evaporates from the molten pool, and the vapor pressure generated during evaporation forms the keyhole 66 . Here, the molten pool and the keyhole 66 are collectively treated as the welded portion 65 . A weld bead is formed behind the molten pool in the welding direction by solidification of the molten pool.

At this time, the first measuring beam S1 emitted from one of the plurality of laser modules 15a is coaxially superimposed on the laser beam L emitted from the laser beam oscillator 10 by the dichroic mirror 53. The laser light L and the first measurement light S1 are emitted inside the keyhole 66 . The emitted first measurement light S<b>1 is reflected at the bottom of the keyhole 66 and enters the optical interferometer device 20 via the dichroic mirror 53 .

The difference signal generator 25 of the optical interferometer device 20 generates a difference signal indicating the phase difference between the optical path lengths of the first measurement light S1 and the second measurement light S2. The calculation unit 27 of the control unit 26 calculates the depth of the keyhole 66 as the penetration depth of the welded portion 65 based on the difference signal. In the laser welding device 1, the quality of the welded portion 65 is determined based on the identified penetration depth.

By the way, the keyhole 66 is formed by the pressure of the vapor when the metal melted at the welded portion 65 evaporates. The shape of the keyhole 66 to be formed changes depending on the emission time of the laser light L and the state of the molten pool.

Specifically, the front inner wall portion of the keyhole 66 in the welding direction tends to curve toward the rear of the keyhole 66 as the moving speed (welding speed) of the laser head 50 increases. Therefore, the front inner wall portion of the keyhole 66 in the welding direction has a curved shape with shallow penetration.

Therefore, in this embodiment, the penetration depth of the welded portion 65 is measured at a plurality of different positions in order to accurately grasp the penetration depth of the deepest portion of the welded portion 65 .

Specifically, as shown in FIG. 4, the image fiber 30 has a total of nine cores 31 arranged in three rows and three columns. Here, the upper cores 31 in FIG. 4 are called "core 1", "core 2", and "core 3" in order from the left. The middle cores 31 in FIG. 4 are called "core 4", "core 5", and "core 6" in order from the left. The cores 31 in the lower row in FIG. 4 are called "core 7", "core 8", and "core 9" in order from the left.

The control unit 26 controls the operation of the plurality of laser modules 15a during laser welding of the work 60. As shown in FIG. The control unit 26 changes the emission timings of the plurality of laser modules 15a so as to selectively switch the core 31 that emits the first measurement light S1 among the plurality of cores 31 .

When the laser head 50 is moving to the right in FIG. 4, that is, when the welding direction is rightward, "core 1", "core 4", and "core 7" positioned downstream in the welding direction are The first measurement light S1 is made incident. After the first measurement light S1 is made incident on the "core 7", the first measurement light S1 is caused to be made incident on the "core 2", the "core 5", and the "core 8" in this order. After the first measurement light S1 is made incident on the "core 8", the first measurement light S1 is caused to be made incident on the "core 3", the "core 6", and the "core 9" in this order. After that, it returns to "core 1" and repeats the same operation.

As a result, by moving the emission position of the first measurement light S1 in a zigzag manner in a direction intersecting the welding direction and in a direction along the welding direction, the emission range of the first measurement light S1 is widened while 65 penetration depth can be measured.

Further, the penetration depth of the welded portion 65 tends to be measured shallower on the upstream side in the welding direction than on the downstream side. Therefore, by moving the emission position of the first measurement light S1 from the downstream side toward the upstream side in the welding direction, the deepest penetration depth of the welded portion 65 can be accurately measured.

Note that the emission position of the first measurement light S1 may be moved from the upstream side toward the downstream side in the welding direction.

When the laser head 50 changes from rightward to forward in FIG. 4, that is, when the welding direction is upward, "core 7," "core 8," and "core 9" positioned downstream in the welding direction , the first measurement light S1 is made incident. After the first measurement light S1 is made incident on the "core 9", the first measurement light S1 is caused to be made incident on the "core 4", the "core 5", and the "core 6" in this order. After the first measurement light S1 is made incident on the "core 6", the first measurement light S1 is caused to be made incident on the "core 1", the "core 2", and the "core 3" in this order. After that, it returns to "core 7" and repeats the same operation.

Similarly, when the laser head 50 changes from forward to left or from left to backward, the core 31, into which the first measurement beam S1 is incident, is moved from the downstream side to the upstream side in the welding direction. The explanation is omitted because it is only necessary to switch in the opposite direction.

As shown in FIG. 5, the penetration depths of the welded portion 65 at a plurality of locations are measured by emitting the first measurement beams S1 from the plurality of cores 31, respectively. Here, the depth (frequency), which is the horizontal axis of the graph in FIG. is a deep value.

In this embodiment, it is assumed that the opening diameter of the keyhole 66 is φ0.5 mm and the depth of the deepest part of the keyhole 66 is 2 to 3 mm. For example, when the depth of the deepest part of the keyhole 66 is 3 mm, the depth (frequency) "4" in the graph of FIG. 5 corresponds to 3 mm.

The control unit 26 acquires three-dimensional data representing the shape of penetration in the welded portion 65 based on a plurality of penetration depths measured at different positions in the welded portion 65 of the workpiece 60 .

Specifically, as shown in FIG. 6, three-dimensional data obtained by synthesizing the positions of the cores 31 and the measured values of each core 31 schematically expresses the shape of the keyhole 66 of the welded portion 65. be able to. In the example shown in FIG. 6, it can be seen that the penetration depth measured with the first measurement light S1 emitted from the “core 5” among the plurality of cores 31 is the deepest portion of the welded portion 65. As shown in FIG.

As shown in FIG. 7, the three-dimensional data acquired by the control unit 26 may be displayed on the display unit 28. FIG. By displaying the three-dimensional data representing the penetration shape of the welded portion 65 on the display unit 28 in this manner, the penetration shape of the welded portion 65 can be visually grasped easily.

Also, the control unit 26 may measure the bead width W of the welded portion 65 based on the acquired three-dimensional data. For example, between the emission position of the first measurement light S1 emitted from the upper "core 1" in FIG. 6 and the emission position of the first measurement light S1 emitted from the lower "core 7" in FIG. By measuring the distance, the bead width W of the welded portion 65 can be grasped (see FIG. 7).

In this embodiment, the configuration using the image fiber 30 having a total of nine cores 31 of 3 rows×3 columns has been described, but the configuration is not limited to this configuration. For example, an image fiber 30 having a total of 25 cores 31 of 5 rows×5 columns may be used. In this case, since the number of measurement points can be increased compared to the image fiber 30 having nine cores 31, the penetration depth of the welded portion 65 can be grasped more accurately. Moreover, since the resolution of the three-dimensional data representing the penetration shape of the welded portion 65 is enhanced, the shape of the keyhole 66 of the welded portion 65 can be expressed more smoothly.

-Modification of Embodiment 1-
In the following, the same reference numerals are given to the same parts as in the first embodiment, and only the points of difference will be described.

In this modified example, the order of incidence of the first measurement light S1 on the plurality of cores 31 is different from that in the first embodiment.

Specifically, when the laser head 50 is moving to the right in FIG. , the first measurement light S1 is made incident. After the first measurement light S1 is made incident on the "core 7", the first measurement light S1 is made incident on the "core 8", the "core 5", and the "core 2" in this order. After the first measurement light S1 is made incident on the "core 2", the first measurement light S1 is caused to be made incident on the "core 3", the "core 6", and the "core 9" in this order. After that, it returns to "core 1" and repeats the same operation.

When the laser head 50 changes from rightward to forward in FIG. 8, that is, when the welding direction is upward, "core 7," "core 8," and "core 9" positioned downstream in the welding direction , the first measurement light S1 is made incident. After the first measurement light S1 is made incident on the "core 9", the first measurement light S1 is made incident on the "core 6", the "core 5", and the "core 4" in this order. After the first measurement light S1 is made incident on the "core 4", the first measurement light S1 is caused to be made incident on the "core 1", the "core 2", and the "core 3" in this order. After that, it returns to "core 7" and repeats the same operation.

Similarly, when the laser head 50 changes from forward to left or from left to backward, the core 31, into which the first measurement beam S1 is incident, is moved from the downstream side to the upstream side in the welding direction. The explanation is omitted because it is only necessary to switch in the opposite direction.

Note that the emission position of the first measurement light S1 may be moved from the upstream side toward the downstream side in the welding direction.

<<Embodiment 2>>
As shown in FIG. 9, the image fiber 30 has multiple cores 31 and a clad 32 . Illustration of the protective film is omitted.

The plurality of cores 31 are radially arranged at intervals from the central portion of the image fiber 30 toward the outer peripheral portion. In the example shown in FIG. 9, six cores 31 are arranged at intervals along the circumference of the central core 31 .

The control unit 26 performs control to move the emission position of the first measurement light S1 along a spiral trajectory from the central portion of the image fiber 30 toward the core 31 at the outer peripheral portion. In the example shown in FIG. 9, after the first measurement light S1 is made incident on the central core 31 of the image fiber 30, the first measurement light S1 is made incident on the upper right core 31 in FIG. After that, along the core 31 of the outer peripheral portion of the image fiber 30, the incident position of the first measurement light S1 is sequentially moved in the clockwise direction.

Then, after the first measurement light S1 is made incident up to the upper left core 31 in FIG. 9, the first measurement light S1 is caused to be made incident on the central core 31 of the image fiber 30, and the same operation is repeated. It should be noted that the incident position of the first measurement light S1 may be circulated along the core 31 in the outer peripheral portion without returning to the core 31 in the central portion.

In this way, even when the welding direction is changed with the movement of the laser head 50, it is not necessary to switch the emission pattern of the first measurement light S1, and the first measurement light S1 can be continuously emitted over a wide range. be able to.

Further, in this embodiment, the emission pattern of the first measurement light S1 is changed between the welding start position and the welding end position of the workpiece 60. As shown in FIG.

Specifically, at the welding start position of the workpiece 60, as shown in FIG. move.

Specifically, at the welding start position, the central portion of the welded portion 65 of the workpiece 60 melts first, so the emission position of the first measurement light S1 should be moved from the central portion of the welded portion 65 toward the outer peripheral portion. , the deepest part of the penetration depth can be accurately grasped.

On the other hand, at the welding end position of the workpiece 60, as shown in FIG. 9, the emission position of the first measurement light S1 is moved along a spiral trajectory from the outer peripheral portion of the image fiber 30 toward the central core 31. .

Specifically, at the welding end position, the emission position of the first measurement light S1 is moved from the outer periphery toward the center of the welded portion 65 of the workpiece 60, and the first measurement light S1 is emitted to the center of the welding end position. By doing so, the deepest part of the penetration depth can be accurately grasped.

-Modification of Embodiment 2-
As shown in FIG. 10, the image fiber 30 has multiple cores 31 and a clad 32 . Illustration of the protective film is omitted.

The plurality of cores 31 are arranged at intervals so as to form a spiral shape extending from the central portion of the image fiber 30 toward the outer peripheral portion.

The control unit 26 performs control to move the emission position of the first measurement light S1 along a spiral trajectory from the central portion of the image fiber 30 toward the core 31 at the outer peripheral portion.

In this way, even when the welding direction is changed with the movement of the laser head 50, it is not necessary to switch the emission pattern of the first measurement light S1, and the first measurement light S1 can be continuously emitted over a wide range. be able to.

Further, in this modification, the emission pattern of the first measurement light S1 is changed between the welding start position and the welding end position of the workpiece 60. FIG.

Specifically, at the welding start position of the workpiece 60, as shown in FIG. move.

On the other hand, at the welding end position of the workpiece 60, as shown in FIG. 11, the emission position of the first measurement light S1 is moved along a spiral trajectory from the outer peripheral portion of the image fiber 30 toward the central core 31. .

<<Other embodiments>>
The above embodiment may be configured as follows.

In this embodiment, the plurality of laser modules 15a emit the first measurement light beams S1 of the same wavelength, and the control unit 26 controls the plurality of cores 31 to emit the first measurement light beams S at different timings. However, it is not limited to this form.

For example, the plurality of laser modules 15a may emit first measurement light beams S1 having different wavelengths, and the control unit 26 may perform control to simultaneously emit the plurality of first measurement light beams S1 from the plurality of cores 31. good.

Specifically, when the wavelength of the first measurement light S1 emitted from one of the plurality of laser modules 15a is set to 1300 nm, the wavelengths of the first measurement light S1 emitted from the other laser modules 15a are set to 1350 nm, 1400 nm, . . .

In this manner, by simultaneously emitting a plurality of first measurement beams S1 having different wavelengths from a plurality of cores 31, it is possible to simultaneously measure the penetration depth of welded portion 65 at a plurality of different positions.

Further, in the present embodiment, the calculation unit 27 of the control unit 26 receives the difference signal from the difference signal generation unit 25 of the optical interferometer device 20 and calculates the penetration depth of the welded portion 65 of the workpiece 60. However, the optical interferometer device 20 itself may be provided with another calculation unit (not shown) to calculate the penetration depth of the welded portion 65 of the workpiece 60 .

In the present embodiment, the optical interferometer device 20 is configured to have the detection section 21 including the optical interference optical section 22 and the differential signal generation section 25. However, the differential signal generation section 25 is provided separately. may

Further, in the present embodiment, the robot control unit 16 and the control unit 26 of the optical interferometer device 20 are configured separately. You may make it contain a function.

INDUSTRIAL APPLICABILITY As described above, the present invention is extremely useful and industrial because it provides a highly practical effect that the penetration depth of the deepest part of the welded portion can be accurately grasped during laser welding of the workpiece. availability is high.

Reference Signs List 1 laser welding device 10 laser beam oscillator 15 measurement beam oscillator 15a laser module 20 optical interferometer device 21 detector 22 optical interference optical unit 23 beam splitter 24 reference mirror (mirror)
25 differential signal generation section 26 control section 27 calculation section 28 display section 30 image fiber 31 core 50 laser head 60 workpiece 65 welding section L laser light S measurement light S1 first measurement light S2 second measurement light

Claims (13)

A laser welding device that welds a workpiece while emitting a laser beam along a predetermined welding direction,
a laser oscillator that generates the laser light;
a measurement light oscillator having a plurality of laser modules each generating measurement light having a wavelength different from that of the laser light;
an image fiber having a plurality of cores corresponding to the plurality of laser modules and connected to each of the laser modules, the image fiber transmitting the measurement light generated by the measurement light oscillator;
a laser head that coaxially superimposes the laser light and the measurement light transmitted through the image fiber and emits the laser light toward the workpiece;
an optical interferometer device that receives the measurement light reflected by the work and measures the penetration depth of the welded portion of the work;
and a controller for controlling the operation of the plurality of laser modules so as to selectively switch between the plurality of cores that emit the measurement light during laser welding of the workpiece. laser welding equipment. In claim 1,
The optical interferometer device has a detection unit including an optical interference optical unit and a differential signal generation unit, and the control unit,
The optical interference optical unit includes
a beam splitter that splits the measurement light emitted from the laser module of the measurement light oscillator into a first measurement light and a second measurement light;
and a mirror that reflects the second measurement light,
the beam splitter and the mirror are provided to correspond to the plurality of laser modules;
The differential signal generator receives the first measurement light reflected by the workpiece and the second measurement light reflected by the mirror via the beam splitter, and outputs the first measurement light and the second measurement light generating a differential signal indicative of the phase difference of the optical path lengths of
The laser welding device, wherein the control unit has a calculation unit that calculates a penetration depth of the welded portion of the workpiece based on the difference signal generated by the difference signal generation unit. In claim 1 or 2,
The plurality of cores are radially arranged at intervals from the center of the image fiber toward the outer periphery,
The laser welding device, wherein the control unit controls the emission position of the measurement light to move along a spiral trajectory from the central portion of the image fiber toward the core at the outer peripheral portion. In claim 3,
The control unit
At the welding start position of the workpiece, control is performed to move the emission position of the measurement light along a spiral trajectory from the center of the image fiber toward the core on the outer periphery,
A laser welding apparatus characterized in that, at the welding end position of the workpiece, control is performed such that the emission position of the measurement light is moved along a spiral trajectory from the outer periphery of the image fiber toward the core at the center. . In claim 1 or 2,
The plurality of cores are spaced apart in a direction intersecting the welding direction,
The laser welding device, wherein the control section performs control to move the emission position of the measurement light along a direction intersecting with the welding direction. In claim 5,
The plurality of cores are spaced apart along the welding direction,
The laser welding device, wherein the control section performs control to move the emission position of the measurement light along the welding direction. In claim 6,
The laser welding apparatus, wherein the control section performs control to move the emission position of the measurement light from the downstream side toward the upstream side in the welding direction. In any one of claims 1 to 7,
The plurality of laser modules emit the measurement light of the same wavelength,
The laser welding device, wherein the control section controls the measurement beams to be emitted from the plurality of cores at different timings. In claim 1 or 2,
the plurality of laser modules emit the measurement light beams having wavelengths different from each other;
The laser welding device, wherein the control section controls the simultaneous emission of the plurality of measurement beams from the plurality of cores. In any one of claims 1 to 9,
The control unit further acquires three-dimensional data indicating a penetration shape in the weld based on a plurality of penetration depths measured at mutually different positions in the weld of the work by the optical interferometer device. A laser welding device characterized by: In claim 10,
A laser welding apparatus comprising a display section for displaying the three-dimensional data acquired by the control section. In claim 10 or 11,
The laser welding device, wherein the control unit measures a bead width of the welded portion based on the acquired three-dimensional data. A laser welding method for welding a workpiece while emitting a laser beam along a predetermined welding direction,
a step of generating the laser light and measurement light having a wavelength different from that of the laser light using a plurality of laser modules;
The laser light and the measurement light transmitted through image fibers having a plurality of cores respectively connected to the laser modules corresponding to the plurality of laser modules are coaxially overlapped to form the workpiece. emitting toward
measuring the penetration depth of the welded portion of the workpiece based on the measurement light reflected by the workpiece;
and a step of controlling operations of the plurality of laser modules so as to selectively switch between the plurality of cores that emit the measurement light during laser welding of the workpiece. laser welding method.