JP2010115676A - Method and apparatus for picking up image of welding state of yag laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently pick up an image of a welding state of the YAG (Yttrium Aluminum Garnet) laser welding. <P>SOLUTION: Images of a weld part 30 and its peripheral part are picked up through an optical band-pass filter 26 capable of transmitting the light in the wavelength band on the wavelength side shorter than the oscillation wavelength of the YAG laser beam while applying the light to the weld part 30 and its peripheral part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for photographing a welding state.

  As a technique for photographing the welding state of the welded portion, for example, there is one disclosed in Patent Document 1. Patent Document 1 monitors the welding state of a welded part such as arc welding or gas welding, and irradiates the welded part with a light source part and only infrared light out of light coming from the welded part through an infrared light transmitting filter. A technique for transmitting and photographing a welded portion with infrared light using a surveillance camera is disclosed.

Japanese Patent Laid-Open No. 8-25040

  Incidentally, there is a welding method using a YAG laser as a welding technique for performing terminal connection. However, the YAG laser has a very strong illuminance at its oscillation wavelength of 1064 nm, and the illuminance by the reflected light is also very strong. Therefore, when the technique of Patent Document 1 is applied to YAG laser welding, light with a very strong wavelength component of the YAG laser passes through the infrared light transmission filter and enters the surveillance camera. And the illuminance difference from the above becomes large, and there is a risk that halation or the like may occur in the video taken by the surveillance camera. Therefore, it is difficult to photograph the welding state of YAG laser welding.

  In view of this, an object of the present invention is to satisfactorily photograph the welding state of YAG laser welding.

  In order to solve the above-mentioned problem, the welding state imaging method of YAG laser welding according to the first aspect is a welding state imaging method of YAG laser welding for imaging the welding state of the welded part and its peripheral part in YAG laser welding. Then, the welded part and the peripheral part are photographed through an optical bandpass filter capable of transmitting a wavelength band shorter than the oscillation wavelength of the YAG laser while irradiating the welded part and the peripheral part with light.

  The welding state imaging method of YAG laser welding according to the second aspect is a welding state imaging method of YAG laser welding according to the first aspect, wherein the welding part and the peripheral part are irradiated with infrared light, The wavelength band of the optical bandpass filter is set so as to be able to transmit a shorter wavelength than the oscillation wavelength of the YAG laser and to transmit at least a part of the wavelength of the infrared light irradiated to the welded part and the peripheral part. ing.

  The welding state imaging method of YAG laser welding according to the third aspect is a welding state imaging method of YAG laser welding according to the second aspect, wherein the lower limit value of the wavelength band of the optical bandpass filter is 700 nm to 750 nm. Is set.

  A welding state imaging method of YAG laser welding according to a fourth aspect is a welding state imaging method of YAG laser welding according to the second aspect, wherein the oscillation wavelength of the YAG laser is 1064 nm, and the optical bandpass filter The wavelength band has a lower limit of 700 nm to 750 nm and an upper limit of 810 nm.

  A welding state photographing device for YAG laser welding according to a fifth aspect is a welding state photographing device for YAG laser welding for photographing a welding portion in YAG laser welding and a welding state of the periphery thereof. A light source unit capable of irradiating light to the peripheral part, a photographing part capable of photographing the welded part and the peripheral part, and disposed between the photographing part and the welded part and the peripheral part; An optical bandpass filter capable of transmitting a wavelength band shorter than the oscillation wavelength.

  According to the welding state photographing method of YAG laser welding according to the first aspect, welding is performed through an optical bandpass filter capable of irradiating the welded part and the peripheral part with light and transmitting a wavelength band shorter than the oscillation wavelength of the YAG laser. Since the portion and the peripheral portion are photographed, it is possible to cut the oscillation wavelength component of the YAG laser having a very strong illuminance and to photograph through the wavelength band necessary for photographing. Therefore, the welding state of YAG laser welding can be photographed satisfactorily.

  Further, according to the welding state photographing method of YAG laser welding according to the second aspect, the optical bandpass filter can transmit the shorter wavelength side than the oscillation wavelength of the YAG laser, and the red light irradiated to the welded portion and the peripheral portion. Since the transmission wavelength band is set so that a part of the wavelength of the external light can be transmitted, the oscillation wavelength component of the YAG laser having a very strong illuminance can be cut and the part irradiated with infrared light In this way, it is possible to transmit a wavelength component necessary for imaging. Therefore, the welding state of YAG laser welding can be photographed satisfactorily.

  Moreover, according to the welding state imaging | photography method of YAG laser welding which concerns on a 3rd aspect, since the lower limit of an optical bandpass filter is set to 700 nm-750 nm, it becomes the hindrance of imaging | photography on the short wavelength side from the said lower limit. A wavelength region including the wavelength can be cut. Therefore, it is possible to photograph the welding state of YAG laser welding better.

  Further, according to the welding state photographing method of YAG laser welding according to the fourth aspect, since the lower limit value of the optical bandpass filter is set to 700 nm to 750 nm and the upper limit value is set to 810 nm, the oscillation of the YAG laser is performed. A wavelength component having strong illuminance near the wavelength can be cut, and a wavelength component that hinders photographing on the shorter wavelength side than the lower limit value can be cut. Therefore, it is possible to photograph the welding state of YAG laser welding better.

  According to the welding state imaging device of the YAG laser welding according to the fifth aspect, through the optical bandpass filter capable of irradiating the welded part and the peripheral part with light and transmitting the wavelength band shorter than the oscillation wavelength of the YAG laser, Since the welding part and the peripheral part are photographed by the photographing part, it is possible to cut the oscillation wavelength component of the YAG laser having a very strong illuminance and to transmit the wavelength necessary for photographing. Therefore, the welding state of YAG laser welding can be photographed satisfactorily.

{First embodiment}
The YAG laser welding welding state imaging method and YAG laser welding welding state imaging device according to the first embodiment will be described below. In the following description, the vertical direction of the drawing may be expressed by the vertical direction, but this direction is used for convenience of description and does not limit the direction in the YAG laser welding welding state imaging apparatus.

  YAG laser light is light generated by a YAG laser device using a laser medium in which a part of yttrium in YAG (Yttrium Aluminum Garnet) is replaced with another rare earth element. Laser light generated by a laser medium in which a part of yttrium in YAG is replaced with neodymium ions is called an Nd-YAG laser. The oscillation wavelength of this Nd-YAG laser beam is 1064 nm near infrared light. Here, an example will be described in which the welding state is photographed when welding is performed using Nd-YAG laser light.

<1. YAG laser welding welding state imaging device>
First, the welding state imaging device 20 of YAG laser welding will be described. FIG. 1 is a schematic perspective view showing a welding state imaging device 20 of YAG laser welding according to the first embodiment, and FIG. 2 is a side view showing the positional relationship between the YAG laser beam 12, the first welding workpiece 14 and the second welding workpiece 15. FIG.

  A YAG laser welding apparatus 10 shown in FIG. 1 is configured to be able to weld a joint portion 32 of welding workpieces 14 and 15 by irradiating YAG laser light 12. The YAG laser welding apparatus 10 has a joint portion 32 (here, the contact between the welded workpieces 14 and 15) between the elongated first welded workpiece 14 and the elongated second welded workpiece 15 crossed substantially vertically. The YAG laser beam 12 is arranged so as to be able to irradiate just above the portion. Here, the YAG laser beam 12 is emitted from the first welded work 14 and the second welded work 15 in a direction along an angle of 45 degrees with respect to the plane including the first welded work 14 and the second welded work 15 in FIG. It is set so that it may irradiate to the junction part 32.

  Moreover, in this embodiment, the copper alloy (square material) terminal by which the plating process was performed is used for the 1st welding workpiece | work 14, and the enameled wire (single core wire) is used for the 2nd welding workpiece | work 15. FIG. Hereinafter, the welding workpieces 14 and 15 will be described as an example to be welded. However, the object to be welded is not limited to this example, and may be various shapes such as a plate-shaped member and a block-shaped member, and various materials that can be laser-welded.

  The welding state imaging device 20 of YAG laser welding includes a light source unit 22 that irradiates light to the welded part and its peripheral part, an imaging part 24 that images the welded part and the peripheral part, and a wavelength in the transmission wavelength band to the imaging part 24. And an optical bandpass filter 26 for entering light.

  The light source unit 22 is disposed so as to be able to irradiate light to a welded part and a peripheral part in YAG laser welding. In other words, the light source unit 22 is disposed at a position where light can be irradiated to the joint portion 32 of the first welding workpiece 14 and the second welding workpiece 15 irradiated with the YAG laser beam 12 and its peripheral portion. Here, a light source unit 22 that can irradiate light including infrared light is used. Here, the infrared light is described as light having a wavelength of 700 nm to 1 mm. The wavelength band of the light emitted from the light source unit 22 only needs to include a wavelength band smaller than the oscillation wavelength of the YAG laser light 12, and does not have to be the entire infrared wavelength region. An area may be included. As the light source unit 22, a halogen lamp capable of irradiating infrared light or the like can be used.

  The imaging unit 24 is disposed so as to be capable of imaging a welded part and its peripheral part in YAG laser welding. In other words, the photographing unit 24 is disposed at a position where the joint portion 32 between the first welding workpiece 14 and the second welding workpiece 15 irradiated with the infrared light and the YAG laser beam 12 can be photographed. The photographing unit 24 is capable of photographing infrared light irradiated to the welded part and the peripheral part by the light source part 22 (sensitive to infrared light), and shows the welding state of YAG laser welding that changes at high speed. It is configured to be able to shoot. Here, the photographing unit 24 is a high-speed video camera capable of photographing infrared light, for example, a high-speed video camera using a CCD image sensor.

  The photographing unit 24 is connected to a display unit (not shown). The display unit is configured to display the welding state of YAG laser welding photographed by the photographing unit 24. And since the quality of a welding state can be determined by the image | video displayed on the display part, it can utilize as a quality assurance means of a laser welding method. Moreover, since it becomes possible to confirm the difference of a welding transient phenomenon for every welding condition, a required energy can be reduced and it can originate in more efficient welding. However, the display unit is not essential, and the captured image may be stored as moving image data or still image data.

  The optical bandpass filter 26 is disposed between the welded portion and the peripheral portion and the photographing unit 24, and here is disposed immediately before the lens barrel in the photographing direction of the photographing unit 24. The optical bandpass filter 26 may be fixed to the lens barrel or may be fixed by another fixing member. The photographing unit 24 can photograph the welded part and the peripheral part through the optical bandpass filter 26. The optical bandpass filter 26 is configured to transmit a wavelength band shorter than the oscillation wavelength (1064 nm) of the YAG laser. The optical bandpass filter 26 is set so as to limit the oscillation wavelength component of the YAG laser having a very strong illuminance among the light irradiated from the welded portion and the peripheral portion. The optical bandpass filter 26 is more preferably set so as to be able to transmit a part of the wavelength of the infrared light irradiated to the welded part and the peripheral part by the light source part 22. And it sets so that a part of wavelength which the infrared light irradiated to the welding part and the peripheral part by the light source part 22 has can be permeate | transmitted.

  Here, the optical bandpass filter 26 may set a wavelength band that can be transmitted by combining a high-pass filter and a low-pass filter. That is, the optical bandpass filter 26 transmits light of a predetermined band wavelength and transmits light of other wavelengths. Anything can be used.

  The YAG laser welding apparatus 10, the light source unit 22, the imaging unit 24, and the optical bandpass filter 26 are configured to move in the welding direction together with the progress of welding by the YAG laser welding apparatus 10. Also good.

<2. YAG laser welding welding state imaging method>
Next, a YAG laser welding welding state imaging method using the YAG laser welding welding state imaging device 20 will be described. FIG. 3 is a conceptual diagram showing the wavelength region of the reflected light at the welded part and the peripheral part when the welding state photographing device 20 of YAG laser welding according to the first embodiment is used.

  First, before starting welding, the light source 22 irradiates the periphery of the joint portion 32 between the first welded workpiece 14 and the second welded workpiece 15, that is, the welded portion and its peripheral portion with infrared light. At this time, the infrared light emitted from the light source unit 22 is reflected by the welded portion and its peripheral portion, and the reflected light enters the imaging unit 24 through the optical bandpass filter 26.

  In a state in which infrared light is irradiated from the light source unit 22, the YAG laser welding apparatus 10 irradiates the joint portion 32 between the first welding workpiece 14 and the second welding workpiece 15 with the YAG laser beam 12, and starts welding. At this time, the YAG laser beam 12 is reflected by the welded portion, and the reflected light enters the imaging unit 24 through the optical bandpass filter 26.

  Along with the start of welding, the welded portion 32 of the first welded work 14 that is a copper alloy terminal and the second welded work 15 that is an enameled wire is irradiated with the YAG laser light 12 to melt and emit light. At the same time, the plating of the copper alloy terminal (first welding workpiece 14) burns and emits light by the irradiation of the YAG laser light 12 and the heat of fusion of the joining portion 32 (plating combustion portion 34 in FIG. 4) and enamel. The coating of the wire (second welding workpiece 15) burns and emits light (enamel coating combustion section 36 in FIG. 4).

  That is, at the time of welding, the reflected light from the infrared light welded portion and its peripheral portion irradiated from the light source unit 22, the reflected light from the YAG laser light 12, and the surrounding environment of the welding state photographing device 20 of YAG laser welding. The reflected light of the light and the light generated in the molten joining portion 32, the plating combustion portion 34 and the enamel coating combustion portion 36 enter the imaging portion 24 through the optical bandpass filter 26.

  Of the light that has passed through the optical bandpass filter 26 during welding, light having a wavelength component within the transmission wavelength band is transmitted, and light having wavelengths before and after the light is limited and enters the imaging unit 24. That is, the photographing unit 24 photographs the welded part and its peripheral part mainly in the transmission wavelength band of the optical bandpass filter 26.

  In FIG. 3, the main wavelength range of the reflected light by the YAG laser beam 12 is W1, and the main part exhibited by the welded part due to other factors (those caused by infrared light emitted from the light source part 22, light emitted from the welded part itself, etc.). The wavelength region is indicated by W2, and the main wavelength region exhibited by the peripheral portion of the welded portion by the infrared light irradiated from the light source unit 22 is indicated by W3.

  As shown in FIG. 3, the optical bandpass filter 26 is set so as to be able to transmit a wavelength band shorter than the oscillation wavelength of the YAG laser, and therefore is included in at least the YAG laser light 12 reflected by the welded portion. The oscillation wavelength component to be cut is cut. The optical bandpass filter 26 transmits a wavelength band necessary for photographing mainly including a part of the wavelength of the infrared light irradiated by the light source unit 22, and enters the wavelength component of the wavelength band into the photographing unit 24. Light up.

  Preferably, the lower limit value of the transmission wavelength band of the optical bandpass filter 26 is 700 nm to 750 nm. This is because the visible light component is cut as much as possible, and imaging with infrared light mainly by the light source unit 22 is performed. More preferably, the lower limit value of the transmission wavelength band of the optical bandpass filter 26 is 700 nm to 750 nm, and the upper limit value thereof is 810 nm. An example of a captured image in this case will be described later in Example 1.

  According to the welding state imaging device and imaging method of YAG laser welding as described above, the light source unit 22 irradiates the welded part and its peripheral part with infrared light and transmits the wavelength band shorter than the oscillation wavelength of the YAG laser. Since the welded part and the peripheral part are photographed by the photographing part 24 through the possible optical bandpass filter 26, the oscillation wavelength component of the YAG laser having a very strong illuminance can be cut and photographed in the wavelength band necessary for photographing. it can. That is, it is possible to solve the problem that halation or the like is generated in a photographed image due to a difference in illuminance between the oscillation wavelength component of the YAG laser and other wavelength components. Therefore, the welding state of YAG laser welding can be photographed satisfactorily.

  Then, by observing an image obtained by imaging the welding state of YAG laser welding, it is possible to determine whether the welding is good or not and to guarantee the quality of the welded portion. In addition, it is possible to perform welding more efficiently by observing differences in transient phenomena during welding for each welding condition and performing optimization of welding conditions such as adjustment of necessary welding energy.

  In addition, the transmission wavelength band of the optical bandpass filter 26 is set so that it can transmit a shorter wavelength than the oscillation wavelength of the YAG laser and can transmit a part of the wavelength of the infrared light irradiated to the welded part and the peripheral part. Therefore, it is possible to cut the oscillation wavelength component of the YAG laser having a very strong illuminance, cut the visible light component as much as possible, and mainly cut the welded part and its peripheral part by reflected light by infrared light irradiation. Images can be taken and the welding state of YAG laser welding can be taken well.

  Here, an example in which welding is performed using Nd-YAG laser light having an oscillation wavelength of 1064 nm has been described, but the present invention can also be applied to welding using YAG laser light having other oscillation wavelengths. In this case, the characteristics of the optical bandpass filter may be set in the same manner as described above with reference to the oscillation wavelength.

  The light source unit 22 may mainly emit visible light. In this case, the transmission band of the optical bandpass filter 26 is preferably set so that at least part of the visible light can be transmitted.

  Next, an example of a captured image to which a welding state imaging device 20 of YAG laser welding and an imaging method using the same are applied will be described. FIG. 4 is a schematic perspective view showing the outline of the light emitting portion of the welded portion 30 photographed by the welding state photographing device 20 of YAG laser welding, and FIG. It is a figure which shows the temporal relationship with the picked-up image at the time of replacement | exchange.

  In Example 1, in the welding state imaging device 20 of the YAG laser welding, imaging of the welding state is performed using a halogen lamp capable of irradiating light having a wavelength of 300 nm to 2000 nm as the light source unit 22.

  The graph of FIG. 5 shows the relationship between the time transition of the main reflected light component and the captured image regarding the YAG laser welding of the welded part 30 and its peripheral part from the start to the end of YAG laser welding. During the irradiation with the YAG laser beam 12 (during the YAG laser welding), the welded portion 30 mainly reflects the wavelength component of the YAG laser beam 12 applied to the joint portion 32, and after the irradiation of the YAG laser beam 12 is stopped. The wavelength component of the light irradiated by the light source unit 22 is mainly reflected. Further, in the peripheral portion, the wavelength component of the light irradiated mainly by the light source unit 22 is reflected during the irradiation with the YAG laser light 12 and after the irradiation is stopped.

  Further, in the captured images represented by the rows (a) to (f) in FIG. 5, when the lower limit value L of the transmission wavelength band of the optical bandpass filter 26 is set to the following (a) to (f), the YAG laser The images of the welding state after the start of welding to the end of welding are arranged in chronological order from the left side to the right side. Here, the lower limit L of the transmission wavelength band of the optical bandpass filter 26 is (a) 750 nm, (b) 700 nm, (c) 600 nm, (d) 500 nm, (e) 400 nm, and (f) 0 nm.

  Further, here, the upper limit value of the optical bandpass filter 26 is set to a value closer to the shorter wavelength than the oscillation wavelength component so that a wavelength component having a strong illuminance near the oscillation wavelength 1064 nm of the YAG laser can be cut. Here, it is set to 810 nm. This upper limit is a value set for cutting a wavelength component having strong illuminance near the oscillation wavelength of 1064 nm of the YAG laser, and it is estimated that the upper limit may not be 810 nm.

  As shown in FIG. 5, during irradiation with the YAG laser beam 12 (during YAG laser welding), the joint portion 32 between the first welding workpiece 14 and the second welding workpiece 15 is melted, and irradiation of the YAG laser beam 12 is stopped. Thereafter, solidification of the melted joint portion 32 starts and finally solidifies completely.

  Further, as shown in the image of FIG. 5, in the welded portion 30 that is being irradiated with the YAG laser light 12, the joint portion 32 irradiated with the YAG laser light 12 is melted and emits light, and the YAG laser light 12 is irradiated. 4 and the coating of the copper alloy terminal (first welded work 14) and the coating of the enameled wire (second welded work 15) are burned by the melting heat of the joining part 32 to emit light (the plating burning part 34 in FIG. 4). Enamel-coated combustion part 36). And in the welding part 30 after irradiation stop of the YAG laser beam 12, the emitted light illuminance of the said joining part 32, the plating combustion part 34, and the enamel coating combustion part 36 becomes weak gradually, and finally it is in the state which is not light-emitting. Become.

  Next, in FIG. 5, an image obtained by photographing the welding state of YAG laser welding under the conditions where the lower limit value L of the transmission wavelength band of the optical bandpass filter 26 is (a) to (f) is compared. The difference in image quality between the welded portion 32 and its peripheral portion is greatly shown in FIG. More specifically, in the images of (a) and (b), the outlines of the peripheral portions of the joint portion 32, the plating combustion portion 34, and the enamel-covered combustion portion 36 are clearly shown. In addition, a difference in illuminance between the joint portion 32, the plating combustion portion 34, and the enamel-covered combustion portion 36 is also shown. Moreover, the light / dark difference appears in the junction part 32, and the state of the junction part 32 can also be observed. On the other hand, in the images (c) to (f), the peripheral portion is blurred in white, and the outlines of the joint portion 32 of the welded portion 30, the plating combustion portion 34, and the enamel-covered combustion portion 36 are ambiguous. And the difference in illuminance between the plating combustion part 34 and the enamel-coated combustion part 36 does not appear. Further, the joint portion 32 and its peripheral portion are whiteout. From this result, it was found that when the lower limit value L of the transmission wavelength band of the optical bandpass filter 26 is set to the conditions (a) and (b), the welding state of YAG laser welding can be favorably photographed.

  Therefore, in the welding state imaging device of YAG laser welding, when the lower limit value of the transmission wavelength band of the optical bandpass filter 26 is set to 700 nm to 750 nm, the welding state of YAG laser welding can be well imaged, and the upper limit value is set to 810 nm. Then, it is presumed that the welding state of YAG laser welding can be photographed more reliably.

It is a schematic perspective view which shows the welding condition imaging device of YAG laser welding concerning a 1st embodiment. It is a side view which shows the positional relationship of a YAG laser beam, a 1st welding workpiece, and a 2nd welding workpiece. It is a conceptual diagram which shows the wavelength range of the reflected light of a welding part and a peripheral part when the welding state imaging device of YAG laser welding which concerns on 1st Embodiment is used. It is a schematic perspective view which shows the outline of the light emission part of the welding part image | photographed with the welding condition imaging device of YAG laser welding. It is a figure which shows the time relationship between the wavelength range of the reflected light in a welding part and a peripheral part, and the picked-up image at the time of optical band pass filter replacement | exchange.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 YAG laser welding apparatus 20 Welding state imaging device of YAG laser welding 22 Light source part 24 Imaging part 26 Optical band pass filter 30 Welding part

Claims (5)

A method for photographing a welding state of YAG laser welding for photographing a welding state in a YAG laser welding and its peripheral portion,
In YAG laser welding, the welded part and the peripheral part are photographed through an optical bandpass filter capable of transmitting a wavelength band shorter than the oscillation wavelength of the YAG laser while irradiating the welded part and the peripheral part with light. Welding state imaging method. A welding state photographing method of YAG laser welding according to claim 1,
Irradiate infrared light to the welded part and the peripheral part,
The wavelength band of the optical bandpass filter is set so as to be able to transmit a shorter wavelength side than the oscillation wavelength of the YAG laser and to transmit at least a part of the wavelength of infrared light irradiated to the welded part and the peripheral part. YAG laser welding welding state imaging method. A welding state imaging method of YAG laser welding according to claim 2,
A welding state photographing method of YAG laser welding, wherein a lower limit value of a wavelength band of the optical bandpass filter is set to 700 nm to 750 nm. A welding state imaging method of YAG laser welding according to claim 2,
The oscillation wavelength of the YAG laser is 1064 nm,
The optical bandpass filter is a welding state photographing method of YAG laser welding in which a lower limit value of a wavelength band is set to 700 nm to 750 nm and an upper limit value is set to 810 nm. A welding state imaging device for YAG laser welding for imaging a welding state of a welded portion and its peripheral portion in YAG laser welding,
A light source unit capable of irradiating light to the welded part and the peripheral part;
A photographing part capable of photographing the welded part and the peripheral part;
An optical bandpass filter disposed between the imaging unit and the welded part and the peripheral part, and capable of transmitting a wavelength band shorter than the oscillation wavelength of the YAG laser;
YAG laser welding welding state imaging device.