JP6452507B2 - Laser welding equipment - Google Patents

Description

  The present invention relates to a laser welding apparatus.

  Laser welding uses a laser beam as a heat source, and thus has various advantages such as high-speed deep penetration compared to other types of welding. On the other hand, a delicate optical system component for a laser beam is necessary for laser welding. As a component member of such an optical system, there are a condensing lens for condensing a laser beam and a protective cover for protecting the condensing lens. The protective cover is disposed between the condensing lens and the portion where laser welding is performed, thereby preventing spatter scattered by laser welding from adhering to the condensing lens. Moreover, since the protective cover is disposed between the condensing lens and the portion where laser welding is performed, the protective cover is made of a light-transmitting material such as glass in order to transmit the laser beam. For this reason, when a certain amount or more of spatter adheres to the protective cover, the sputter heated by the laser beam melts the protective cover, resulting in damage to the protective cover.

  As a laser welding apparatus for appropriately monitoring such a protective cover, there is one in which a monitoring camera for monitoring the protective cover (protective glass) is separately provided (see, for example, Patent Document 1). Since this surveillance camera is dedicated for imaging the protective cover, it naturally focuses on the protective cover. The laser welding apparatus described in Patent Document 1 detects damage to the protective cover by comparing an image captured by the monitoring camera with a reference image.

Japanese Patent No. 5504679

  However, in the laser welding apparatus described in Patent Document 1, since the image of the protective cover captured by the monitoring camera is compared with the reference image, spatters that do not affect laser welding adhere to the protective cover. Even in this case, it will be detected as damage to the protective cover. In order to prevent this, if the reference for comparison in the laser welding apparatus is loosened, it may happen that even if the protective cover is damaged, this cannot be detected. In any case, the laser welding apparatus requires a separate monitoring camera, which complicates the apparatus configuration.

  Then, an object of this invention is to provide the laser welding apparatus which can detect the damage of a protective cover with high precision.

In order to solve the above-mentioned problems, a laser welding apparatus according to claim 1 of the present invention includes a laser oscillator that outputs a laser beam for laser welding to a groove formed on a workpiece, and a laser oscillator A laser welding apparatus comprising: a laser head that irradiates the laser beam while oscillating the laser beam to the groove; and a control unit that controls the laser oscillator and the laser head,
The laser head has a condenser lens that condenses the laser beam, a protective cover that protects the condenser lens, and an imaging unit that focuses and images the workpiece.
It said control means state, and are not to detect damage to the protective cover from the image captured in the imaging unit,
The control means is
A mesh setting unit that divides an image captured by the imaging unit into meshes of an i-axis direction that is the width direction of the groove and a j-axis direction that is the length direction of the groove;
A j-axis integrating unit that calculates a function of the luminance in the i-axis direction by integrating the luminance of the mesh divided by the mesh setting unit in the j-axis direction for each mesh in the i-axis direction;
A groove detecting unit that detects an end of the groove based on the function calculated by the j-axis integrating unit;
An i-axis integrating unit that calculates the sum of the luminances of all meshes by integrating the functions calculated by the j-axis integrating unit in the i-axis direction;
If the sum calculated by the i-axis integrating unit is equal to or greater than a threshold value, an abnormality determining unit that detects that the protective cover is damaged is provided.

According to a second aspect of the present invention, there is provided a laser welding apparatus for outputting a laser beam for laser welding to a groove formed in a workpiece, and a laser beam from the laser oscillator. A laser welding apparatus comprising: a laser head that irradiates while oscillating the groove; and a control means for controlling the laser oscillator and the laser head,
The laser head has a condenser lens that condenses the laser beam, a protective cover that protects the condenser lens, and an imaging unit that focuses and images the workpiece.
The control means detects damage of the protective cover from the image captured by the imaging unit;
The control means is
A mesh setting unit that divides an image captured by the imaging unit into meshes of an i-axis direction that is the width direction of the groove and a j-axis direction that is the length direction of the groove;
A j-axis integrating unit that calculates a function of the luminance in the i-axis direction by integrating the luminance of the mesh divided by the mesh setting unit in the j-axis direction for each mesh in the i-axis direction;
A groove detecting unit that detects an end of the groove based on the function calculated by the j-axis integrating unit;
An i-axis integrating unit that calculates the sum of the luminances of all meshes by integrating the functions calculated by the j-axis integrating unit in the i-axis direction;
A storage unit that stores the total calculated by the i-axis integrating unit at predetermined time intervals;
A difference unit that calculates a difference of the total in a predetermined time from the i-axis integrating unit and the storage unit;
If the difference calculated by the difference unit is equal to or greater than the threshold value, the protective cover includes a damage detection unit that detects that the protective cover is damaged.

Furthermore, in the laser welding apparatus according to claim 3 of the present invention, the control means in the laser welding apparatus according to claim 1 or 2 is used to divide the image into the mesh by the mesh setting unit from the image captured by the imaging unit. An image extraction unit for extracting an image;
The image extracted by the image extraction unit is an area that always includes / does not always include a laser spot in which the laser beam from the laser head is focused on the condenser lens.

Furthermore, the laser welding apparatus according to a fourth aspect of the present invention is the laser welding apparatus according to the third aspect , wherein a plurality of images are extracted by the image extraction unit.

According to the laser welding apparatus of the first aspect, since damage to the protective cover is detected from an image captured without being focused on the protective cover, damage to the protective cover can be detected with high accuracy. In addition, the image captured without being focused on the protective cover is divided into meshes, and damage to the protective cover is detected based on the sum calculated from the brightness of all meshes. can do. In addition, since an image for detecting the edge of the groove and an image for detecting damage to the protective cover are captured by one imaging unit, the apparatus configuration can be simplified.

According to the laser welding apparatus of the second aspect, since the damage of the protective cover is detected from the image captured without being focused on the protective cover, the damage of the protective cover can be detected with high accuracy. Furthermore , the image captured without focusing on the protective cover is divided into meshes, and the protective cover damage is detected based on the difference in the total time calculated from the brightness of all meshes at a given time. Can be detected with high accuracy. In addition, since an image for detecting the edge of the groove and an image for detecting damage to the protective cover are captured by one imaging unit, the apparatus configuration can be simplified.

It is a lineblock diagram showing a laser welding apparatus concerning an embodiment of the invention. It is a block diagram which shows the image process judgment part of the laser welding apparatus. It is a figure which shows the object imaged by the imaging part of the laser welding apparatus. It is a figure which shows the image extracted by the image extraction part of the image processing judgment part, the mesh corresponding to this, and function f (i). It is the image imaged by the imaging part before melting | fusing of a protective cover begins. It is the image imaged by the imaging part 150 msec after melting | fusing of a protective cover started. It is the image imaged by the imaging part 300 msec after melting | fusing of a protective cover started. It is the image imaged by the imaging part 450 msec after melting | fusing of a protective cover started. It is the image imaged by the image pick-up part 600 msec after melting | fusing of a protective cover started. It is the image imaged by the imaging part 750 msec after melting | fusing of a protective cover started. It is the image imaged by the imaging part after 1500 msec from the start of melting of the protective cover. It is a block diagram which shows the other example of the image processing judgment part. It is a block diagram which shows the further another example of the image processing judgment part. It is a figure which shows the other example regarding the area | region of the image extracted by the image extraction part.

Hereinafter, a laser welding apparatus according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the laser welding apparatus outputs a laser beam (CO ₂ laser or YAG laser) 20 for laser welding to a groove 9 formed in a base material (workpiece) 1. An oscillator 11 and a laser head 12 that irradiates the laser beam 20 from the laser oscillator 11 while oscillating the groove 9 are provided. The laser welding apparatus 10 also includes control means 14 for controlling the laser oscillator 11 and the laser head 12. In the laser welding apparatus 10, in order to perform appropriate laser welding, it is necessary to monitor a portion where the laser welding is performed and to detect a defect occurring in the laser head 12. For this reason, the laser welding apparatus 10 also includes a display alarm device 13 for displaying an image of the portion where the laser welding is performed and for issuing an alarm when a problem occurs in the laser head 12. The malfunction of the laser head 12 is, as will be described in detail later, damage to the protective cover 26 constituting the laser head 12. This damage is mainly caused by spatter scattered by laser welding adhering to the protective cover 26. The control means 14 not only controls the laser oscillator 11 and the laser head 12 but also controls a welding robot control device that cooperates with the laser welding device 10. The welding robot apparatus moves the laser welding apparatus 10 and / or the base material 1 at an appropriate direction and speed so that the laser beam 20 travels in the length direction L of the groove 9.

Hereinafter, a detailed configuration of the laser welding apparatus 10 will be described.
[Laser head 12]
As shown in FIG. 1, the laser head 12 includes a fiber cable 21 and a collimation lens 22 for introducing the laser beam 20 into the laser beam 20 in the order from the oscillation source to the oscillation destination of the laser beam 20, and the laser beam 20 into the laser beam 20. A reflection mirror (weaving mirror) 23 that reflects in the direction of the groove 9; a weaving drive 24 that drives the reflection mirror 23 so that the laser beam 20 swings in the width direction W of the groove 9; A condensing lens 25 that condenses the laser beam 20 and a protective cover (protective glass or the like) 26 that protects the condensing lens 25 are provided. The laser head 12 includes an illumination light source and an illumination dichroic mirror (not shown) in order to illuminate the laser welded portion as necessary.

  As shown in FIG. 1, the laser head 12 includes an imaging unit (for example, a camera) 27, an imaging dichroic mirror 28 that reflects the laser welded portion of the imaging unit 27, and the imaging unit. The filter 29 is disposed between the dichroic mirror 28 and the imaging unit 27 and blocks light having an unnecessary wavelength in the imaging unit 27. The imaging dichroic mirror 28 is disposed between the reflection mirror 23 and the condenser lens 25, and transmits the laser beam 20 without reflecting it. Although not shown, the laser head 12 has an air nozzle that ejects air between the laser welded portion and the protective cover 26 as necessary. This air nozzle prevents spatter scattered by laser welding from adhering to the protective cover 26 by the air to be ejected.

  The imaging unit 27 focuses on the portion where the laser welding is performed instead of the protective cover 26. For this reason, the focused portion in the captured image, that is, the portion where the laser welding is performed is clear, and is suitable for monitoring the welding state. On the other hand, when a portion that is not focused in the captured image, that is, a portion of the protective cover 26 is damaged, the image capturing unit emits light from the laser beam 20 due to the damage in a wide range. 27. As a result, even if the damage is minute, which is caused by the adhesion of spatter, is captured by the imaging unit 27, it is suitable for the detection of the damage by the control means 14.

[Display alarm 13]
As shown in FIG. 1, the display alarm device 13 includes an image output unit 31 that displays an image captured by the imaging unit 27, and an alarm unit that issues an alarm when the control unit 14 detects damage to the protective cover 26. 38. The image output unit 31 not only displays the image as shown in FIG. 3 but also transmits the image data to the control means 14. As shown in FIG. 3, the object to be imaged includes a laser spot 2 that is a focused laser beam 20, a filler wire 3 that is fed into the groove 9, and a molten portion 4 at the groove 9. It is.

[Control means 14]
As shown in FIG. 1, the control unit 14 receives an image data from the image output unit 31, processes and determines the image processing determination unit 45, and the processing and determination result of the image processing determination unit 45 An operation output unit 41 for operating the laser oscillator 11 and the welding robot control device based on the above, and a weaving control unit 44 for controlling the weaving drive unit 24 by an operation signal from the operation output unit 41. The operation output unit 41 appropriately operates the laser oscillator 11 and the welding robot control device according to the signal of the result from the image processing determination unit 45 and performs weaving with an amplitude corresponding to the width of the groove 9. The laser beam 20 is swung by the drive unit 24.

Hereinafter, a more detailed configuration of the image processing determination unit 45, which is the gist of the present invention, will be described with reference to FIG.
As shown in FIG. 2, the image processing determination unit 45 extracts an image extraction unit 51 that extracts a necessary image from the image data received from the image output unit 31, and the image extracted by the image extraction unit 51. and an ij mesh setting unit 52 for dividing into i-axis and j-axis meshes. As shown in FIG. 3, the image 5 extracted by the image extraction unit 51 always includes the laser spot 2 in the image captured by the imaging unit 27 regardless of the oscillation of the laser beam 20. There is no area. As shown in FIG. 4, in the mesh classified by the ij mesh setting unit 52, the i axis is the width direction W of the groove 9 (the direction in which the laser beam 20 swings), and the j axis is the groove 9. The length direction is L (the direction in which the laser beam 20 travels).

  As shown in FIG. 2, the image processing determination unit 45 includes a j-axis integration unit 53 that receives data of luminance p (i, j) of each mesh divided from the ij mesh setting unit 52. As shown in FIG. 4, the j-axis integrating unit 53 calculates a function f (i) of luminance in the i-axis direction by integrating the luminance p (i, j) of each mesh in the j-axis direction. It is. Here, in the divided mesh, if the minimum value of j is 1 and the maximum value of j is J, the function f (i) is expressed by the following equation (1).

As shown in FIG. 2, the image processing determination unit 45 includes a groove detection unit 54 and an i-axis integration unit 55 that receive data of the function f (i) from the j-axis integration unit 53. The groove detecting unit 54 detects, as the two end portions 9E of the groove 9 shown in FIGS. 1 and 3, a point where the inclination of the function f (i) in the i-axis direction is maximum and minimum, respectively. Is. The i-axis integrating unit 55 calculates the sum of the luminances p (i, j) of all meshes in the extracted image 5 by integrating the function f (i) in the i-axis direction. Since this sum is a value depending on the time t, the sum is hereinafter referred to as a sum value F (t). Here, in the divided mesh, if the minimum value of i is 1 and the maximum value of i is I, the total value F (t) is expressed by the following equation (2).

As shown in FIG. 2, the image processing determination unit 45 includes an abnormality determination unit 56 that receives data of the total value F (t) from the i-axis integration unit 55. The abnormality determination unit 56 detects that the protective cover 26 is damaged if the total value F (t) obtained by the i-axis integration unit 55 is equal to or greater than a threshold value. Further, when the abnormality determination unit 56 detects that the protective cover 26 is damaged, the abnormality determination unit 56 transmits a signal for emergency stop to the operation output unit 41 and transmits a signal for issuing an alarm to the alarm unit 38. To do.

Hereinafter, a laser welding method using the laser welding apparatus 10 will be described.
As shown in FIG. 1, as this laser welding method, a laser beam 20 output from a laser oscillator 11 is irradiated to the groove 9 while being swung in the width direction W of the groove 9 by a laser head 12. . The laser welded portion is imaged by the imaging unit 27, and the captured image is displayed on the display alarm device 13.

  The necessary image 5 is extracted by the image extraction unit 51 from the captured image shown in FIG. The extracted image 5 is divided into meshes by the ij mesh setting unit 52 as shown in FIG. A function f (i) is calculated by the j-axis integrating unit 53 from the brightness p (i, j) of the divided mesh, and the two ends of the groove 9 are calculated by the groove detecting unit 54 from the function f (i). 9E is detected. On the other hand, the total value F (t) is calculated by the i-axis integrating unit 55 from the function f (i). Whether or not the protective cover 26 is damaged is determined by the abnormality determination unit 56 from the total value F (t). Specifically, if the total value F (t) calculated by the i-axis integrating unit 55 is equal to or greater than a threshold value, the abnormality determining unit 56 detects that the protective cover 26 is damaged. When detected in this way, the operation output unit 41 causes the laser oscillator 11 and the welding robot control device to stop emergency, and the weaving drive unit 24 stops emergency via the weaving control unit 44. On the other hand, the alarm detector 38 of the display alarm device 13 issues an alarm by the damage detector 58.

Here, the damage of the protective cover 26 detected by the damage detection unit 58 will be described.
Spatter is scattered at the portion where the laser welding is performed. Most of these spatters do not adhere to the protective cover 26 due to the air ejected from the air nozzle, but some may adhere to the protective cover 26. The spatter adhering to the protective cover 26 is heated by the laser beam 20 passing through the protective cover 26. For this reason, when the amount of spatter adhering to the protective cover 26 exceeds a certain amount, the sputter heated by the laser beam 20 melts the protective cover 26, and as a result, the protective cover 26 is damaged.

  FIGS. 5 to 11 show an actual image captured by the imaging unit 27 until the protective cover 26 is damaged. 5 to 11 show images in a state in which 0 msec, 150 msec, 300 msec, 450 msec, 600 msec, 750 msec, and 1500 msec have elapsed since the melting of the protective cover 26 started by heated sputtering, respectively. As described above, since the focus of the imaging unit 27 is not focused on the protective cover 26, the portions that appear white in FIG. 6 to FIG. 11 spread light emission of the protective cover 26 generated from the laser beam 20 due to damage of the protective cover 26. Part. An image including this portion is more suitable for the detection of the damage by the abnormality determination unit 56 than an image captured with the protective cover 26 in focus.

  As described above, according to the laser welding apparatus 10, an image captured without the focus of the imaging unit 27 being focused on the protective cover 26 is divided into meshes, and the protective cover is based on the total value calculated from the luminance of all the meshes. Since the damage of 26 is detected, the damage of the protective cover 26 can be detected with high accuracy. Further, since the image 5 for detecting the end portion 9E of the groove 9 and the image 5 for detecting damage to the protective cover 26 are imaged by one imaging unit 27, the apparatus configuration is simplified. Can do.

  In the above embodiment, the image extraction unit 51 has been described. However, this is not an essential configuration, and the image extraction unit 51 is not necessary if only the image 5 to be extracted is captured.

  In the above embodiment, the ij mesh setting unit 52 and the j-axis integrating unit 53 are used both for detecting the end 9E of the groove 9 and for detecting damage to the protective cover 26. Although described, the present invention is not limited to this. Specifically, as shown in FIG. 12, the image processing determination unit 45 includes a first ij mesh setting unit 52a and a first j-axis integrating unit 53a to detect the end 9E of the groove 9, and includes a protective cover. In order to detect 26 damage, a second ij mesh setting unit 52b and a second j-axis integrating unit 53b may be provided.

  Furthermore, in the above-described embodiment, the abnormality determination unit 56 has been described as detecting damage to the protective cover 26 based on the total value F (t), but based on the difference of the total value in the predetermined time Δt, It may be one that detects damage. Specifically, as shown in FIG. 13, the image processing determination unit 45 receives the data of the total value F (t) from the i-axis integration unit 55 instead of the abnormality determination unit 56. 59, the difference part 57, and the damage detection part 58 are comprised. The storage unit 59 stores the total value F (t) obtained by the i-axis integrating unit 55 every predetermined time Δt. The difference unit 57 includes the total value F (t) at the current time t calculated by the i-axis integration unit 55 and the total value F (t) a predetermined time Δt before the current time t stored in the storage unit 59. Difference ΔF with respect to (t−Δt) is calculated. The damage detection unit 58 detects that the protective cover 26 is damaged if the difference ΔF calculated by the difference unit 57 is greater than or equal to a threshold value. Further, when the damage detection unit 58 detects that the protective cover 26 is damaged, the damage detection unit 58 transmits a signal for emergency stop to the operation output unit 41 and a signal for generating an alarm to the alarm unit 38. To do.

  In addition, in the above embodiment, the image 5 extracted by the image extraction unit 51 has been described as an area that does not always include the laser spot 2, but may be an area that always includes the laser spot 2. Since the image 5 extracted by the image extraction unit 51 always includes or does not include the laser spot 2, the total value is less likely to change over a predetermined time in a state where the protective cover 26 is not damaged. Because, on the contrary, when the image 5 extracted by the image extraction unit 51 may include the laser spot 2 depending on the time, the total value in the image 5 at the time including the laser spot 2 is high and does not include the laser spot 2. The total value of the image 5 in time becomes low. Therefore, in this case, if the image 5 at the current time t includes the laser spot 2 and the image 5 before the predetermined time Δt from the current time t does not include the laser spot 2, the protective cover 26 is not damaged. This is because it is possible to detect that the protective cover 26 is damaged by increasing the difference ΔF of the total value at the predetermined time Δt. Therefore, since the image 5 extracted by the image extraction unit 51 always includes or does not include the laser spot 2, the total value is less likely to change over a predetermined time in a state where the protective cover 26 is not damaged. Damage to the cover 26 can be detected with higher accuracy.

  Moreover, although the said embodiment demonstrated on the assumption that the image 5 extracted by the image extraction part 51 was one area | region, as shown in FIG. 14, multiple 5A-5E may be sufficient. Thereby, the reliability which detects the damage of the protective cover 26 improves. Moreover, the image 5 extracted by the image extraction part 51 is not limited to what is shown in FIG. 3 and FIG. In this case, the position and number of the images 5 to be extracted are appropriately selected according to the laser welding conditions such as the shape of the groove 9, the thickness of the base material 1, and the arrangement of the air nozzles.

DESCRIPTION OF SYMBOLS 1 Base material 9 Groove 10 Laser welding apparatus 11 Laser oscillator 12 Laser head 14 Control means 20 Laser beam 23 Reflection mirror 24 Weaving drive machine 25 Condensing lens 26 Protective cover 27 Imaging part 52 ij mesh setting part 54 Groove detection part 55 i-axis integration unit 57 difference unit 58 damage detection unit 59 storage unit

Claims (4)

A laser oscillator that outputs a laser beam for laser welding to a groove formed on a workpiece, a laser head that irradiates the laser beam from the laser oscillator while oscillating the groove, and the laser A laser welding apparatus comprising a control means for controlling an oscillator and a laser head,
The laser head has a condenser lens that condenses the laser beam, a protective cover that protects the condenser lens, and an imaging unit that focuses and images the workpiece.
It said control means state, and are not to detect damage to the protective cover from the image captured in the imaging unit,
The control means is
A mesh setting unit that divides an image captured by the imaging unit into meshes of an i-axis direction that is the width direction of the groove and a j-axis direction that is the length direction of the groove;
A j-axis integrating unit that calculates a function of the luminance in the i-axis direction by integrating the luminance of the mesh divided by the mesh setting unit in the j-axis direction for each mesh in the i-axis direction;
A groove detecting unit that detects an end of the groove based on the function calculated by the j-axis integrating unit;
An i-axis integrating unit that calculates the sum of the luminances of all meshes by integrating the functions calculated by the j-axis integrating unit in the i-axis direction;
A laser welding apparatus comprising: an abnormality determining unit that detects that the protective cover is damaged if the total calculated by the i-axis integrating unit is equal to or greater than a threshold value . A laser oscillator that outputs a laser beam for laser welding to a groove formed on a workpiece, a laser head that irradiates the laser beam from the laser oscillator while oscillating the groove, and the laser A laser welding apparatus comprising a control means for controlling an oscillator and a laser head,
The laser head has a condenser lens that condenses the laser beam, a protective cover that protects the condenser lens, and an imaging unit that focuses and images the workpiece.
It said control means state, and are not to detect damage to the protective cover from the image captured in the imaging unit,
The control means is
A mesh setting unit that divides an image captured by the imaging unit into meshes of an i-axis direction that is the width direction of the groove and a j-axis direction that is the length direction of the groove;
A j-axis integrating unit that calculates a function of the luminance in the i-axis direction by integrating the luminance of the mesh divided by the mesh setting unit in the j-axis direction for each mesh in the i-axis direction;
A groove detecting unit that detects an end of the groove based on the function calculated by the j-axis integrating unit;
An i-axis integrating unit that calculates the sum of the luminances of all meshes by integrating the functions calculated by the j-axis integrating unit in the i-axis direction;
A storage unit that stores the total calculated by the i-axis integrating unit at predetermined time intervals;
A difference unit that calculates a difference of the total in a predetermined time from the i-axis integrating unit and the storage unit;
A laser welding apparatus , comprising: a damage detection unit that detects that the protective cover is damaged if the difference calculated by the difference unit is equal to or greater than a threshold value . The control means has an image extraction unit that extracts an image to be divided into meshes by the mesh setting unit from the image captured by the imaging unit,
Image extracted by the image extracting unit, according to claim 1 laser beam from the laser head, characterized in that a region not including always includes a region that / always focused laser spot to the condensing lens or 2. The laser welding apparatus according to 2. The laser welding apparatus according to claim 3 , wherein a plurality of images are extracted by the image extraction unit.