JP2001191186A - Quality evaluation system for weld zone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relatively inexpensive quality evaluation system for a weld zone capable of preventing complexity of process control by indirectly evaluating the propriety of welding immediately after welding. SOLUTION: A ultraviolet ray sensor 17 which detects a plasma generating quantity in a ultraviolet ray zone and an infrared ray sensor 18 which detects the temperature of the laser weld zone 14 are provided in the laser beam irradiating side of the laser weld zone 14 in the vicinity of a section where two connecting terminal parts 10, 11 being an object to be electrically connected are welded by a YAG laser beam machine 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quality evaluation for evaluating a quality of a welded portion when a tab terminal portion accommodated in an electric connection box and a terminal portion at an end of a bus bar are electrically connected by welding. About the system.

[0002]

2. Description of the Related Art The electrical connection between the tab terminal portion and the bus bar terminal portion housed in the above-described electrical connection box is performed by welding with a YAG laser. Since the welded portion formed by this welding is an important part for determining the quality of the electrical connection, quality inspection is performed.

[0003] In the quality inspection of a welded portion, conventionally, the following method has been adopted after welding.

[0004] One of the methods is to observe a welded portion by image processing and inspect for the presence or absence of welding marks. The other one is
This is a sampling inspection, which is a nondestructive inspection in which a weld is captured as an image using X-rays or ultrasonic waves, or a destructive inspection by measuring strength.

[0005]

However, in the conventional inspection method, it is necessary to provide a step different from the welding step, and there is a disadvantage that the step management becomes complicated. In addition, in the case of nondestructive inspection, there is a problem that the cost of inspection equipment and the like is expensive, which leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems of the prior art, and the success or failure of welding can be indirectly evaluated at the same time as welding, so that complicated process control can be prevented, and at a relatively low cost. An object of the present invention is to provide a quality evaluation system for a welded part.

[0007]

SUMMARY OF THE INVENTION A system for evaluating the quality of a welded portion of the present invention indirectly controls the quality of a laser welded portion when two metal members to be electrically connected are welded by a YAG laser. A quality evaluation system for performing a dynamic evaluation, wherein on the laser irradiation side of the laser weld, an ultraviolet sensor that detects an amount of plasma generated from the laser weld in an ultraviolet region, and an infrared sensor that detects the temperature of the laser weld Are provided.

In the system of the present invention, the ultraviolet sensor detects the amount of plasma generated, and the infrared sensor detects the temperature of the laser weld.

At this time, the plasma (wavelength in the ultraviolet region) detected by the ultraviolet sensor is the plasma generated from the laser welded portion by the laser irradiation and the foreign matter typified by oil adhered to the laser welded portion. Is the sum of the plasmas of the foreign substances. For the former plasma generation amount, see FIG.
As shown in the figure, the amount of plasma generated when the laser welded portion penetrates (shown by a solid line) becomes smaller than the amount of plasma generated when welding is normal (shown by a broken line), while the latter plasma generation For example, as shown in FIG. 4 as an example, the amount of plasma generation (shown by a solid line) is larger than the amount of plasma generated during normal welding (shown by a broken line) by the amount of plasma generated by foreign matter.

Therefore, based on the amount of plasma detected by the ultraviolet sensor, it is possible to evaluate a welding defect caused by penetration of the laser welding portion and a welding defect caused by foreign matter adhering to the laser welding portion.

[0011] In addition, based on the temperature of the laser weld detected by the infrared sensor, it is possible to evaluate poor welding that occurs when a foreign substance typified by oil adheres to the laser weld.

That is, as shown in FIG. 5, when the welding is performed normally, the temperature of the laser welded portion has a characteristic of being attenuated by about the same as the welding time (shown by a broken line). This is because, when foreign matters adhere to the portion, the attenuation of the temperature of the laser welded portion (shown by the solid line) becomes longer.

Further, when welding failure due to penetration of the laser welding portion and welding failure due to adhesion of foreign matter occur simultaneously, an erroneous evaluation that the welding is apparently completed successfully is made only by information from the ultraviolet sensor. Will be. Also in this case, by referring to the information from the infrared sensor, it is possible to evaluate the presence / absence of foreign matter adhesion, that is, the quality of welding, from the attenuation of the temperature of the welded portion.

By thus providing an ultraviolet sensor for detecting the amount of plasma and an infrared sensor for detecting the temperature of the laser welded portion on the laser irradiation side of the laser welded portion indirectly, the indirect welding of the welded portion is provided. Because you can evaluate the quality
There is no need to separately provide an inspection process, so that it is possible to prevent the process management from becoming complicated, and it is possible to automate and online the weld quality evaluation system.

[0015] In the quality evaluation system for a welded portion of the present invention, the laser irradiation side of the laser welded portion may be further provided with a laser detecting means for detecting an amount of reflected laser reflected from the laser welded portion. it can.

In this configuration, the laser detecting means can detect a phenomenon that the amount of reflected laser is significantly reduced as compared with the amount of reflected laser when welding is normal as a result of penetration of the laser weld. Welding defects due to penetration can be evaluated.

In the quality evaluation system for a welded portion of the present invention, a second ultraviolet sensor for detecting plasma passing through the laser welded portion in an ultraviolet region and a laser welded portion on a side opposite to the laser irradiation side of the laser welded portion. And at least one of the second laser detecting means for detecting the laser light passing through the light emitting device.

With this configuration, the second ultraviolet sensor or the second laser detecting means detects that the laser welding portion has penetrated and the plasma or laser light has penetrated to the side opposite to the laser irradiation side. Therefore, it can be evaluated that the laser welded portion penetrates to cause welding failure.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.

FIG. 1 is a schematic view (perspective view) for explaining the basic principle of the present invention.

A metal material 1 to be welded is provided with Y
When welding is performed by irradiating the AG laser light 2, a reflected laser light 4 is generated from the welded part 3 irradiated with the laser light 2, and a plasma generating part 5 is generated near the welded part 3. Further, the spatter 6 is scattered from the welded portion 3 to the laser irradiation side, and heat radiation 7 is generated.

In the case where the welding such that the welded portion 3 penetrates to the lower surface is defective, the plasma generating portion 8 and the transmitted laser light 9 on the side opposite to the laser irradiation side (lower side in the illustrated example) are significantly. More. Here, the state where the welded portion 3 has penetrated includes the state shown in FIG. 6A or 6B. FIG.
The state shown in (a) is a good case with no welding defects,
The amount of plasma or laser light penetrating below the weld 3 is not so large. On the other hand, the state shown in FIG. 6B is a defect in which a welding defect has occurred, and the amount of plasma or laser light penetrating below the weld 3 is extremely large.

Therefore, by arranging various sensors near the weld for quality evaluation, it is possible to indirectly grasp the welding state having a correlation with the quality of the weld, and A quality evaluation system for the department can be constructed.

FIG. 2 is a perspective view showing a quality evaluation system for a welded portion according to one embodiment of the present invention.

In the quality evaluation system of the present embodiment, two metal members to be electrically connected, for example, a place where the tab terminal 10 and the terminal 11 at the end of the bus bar are arranged in an overlapping manner. On the other hand, a laser emission lens 12 of the YAG laser welding device is provided above the laser irradiation lens. The laser emitting lens 12 is arranged so that the laser light 13 emitted from the laser emitting lens 12 is directed to the welding portion 14 of the terminal portions 10 and 11. In addition, the welding part 14 becomes a laser welding part after welding.

In addition, a sensor box 15 is provided diagonally above the welding point 14 near the welding point 14, and a sensor box 16 is also provided diagonally below the welding point 14. The sensor box 15 includes an ultraviolet sensor 17 for detecting the amount of plasma in an ultraviolet region, an infrared sensor 18 for detecting the temperature of the laser welding portion 14,
Laser detecting means 19 for detecting the amount of reflected laser light reflected from the laser welded portion 14 is incorporated. These ultraviolet sensor 17, infrared sensor 18, and laser detecting means 1
Numeral 9 is arranged such that each detection direction faces the welding point 14.

The sensor box 16 has a second portion for detecting the amount of plasma that has passed through the laser welding portion 14 in the ultraviolet region.
An ultraviolet sensor 20 and a second laser detecting unit 21 for detecting the amount of laser beam that has passed through the laser welding part 14 are built in. The second ultraviolet sensor 20 and the second laser detecting means 21 are arranged such that their respective detection directions face the welding location 14.

As the ultraviolet sensor 17, infrared sensor 18, laser detecting means 19, second ultraviolet sensor 20, and second laser detecting means 21, any sensors can be used as long as they can perform predetermined detection. Good.

Next, a description will be given of the content of the quality evaluation in the thus configured quality evaluation system of the present embodiment.

When the laser beam 13 is emitted from the laser emitting lens 12 of the YAG laser welding apparatus toward the welding portion 14 and welding is started, an ultraviolet sensor 17 having an ultraviolet region as a detection region detects the amount of plasma generation, The infrared sensor 18 detects the temperature of the laser weld 14, and the laser detecting means 19 detects the amount of laser light reflected from the laser weld 14.

As described above, the plasma detected by the ultraviolet sensor 17 is applied to the laser welding portion 14 by laser irradiation.
And a plasma of a foreign substance when a foreign substance typified by oil adheres to the laser welded portion 14.

Regarding the former plasma generation amount, when the laser welding portion 14 penetrates, the plasma generation amount (shown by a solid line) as shown in FIG. (Indicated by a broken line). Therefore, based on FIG. 3, it can be detected that laser welding portion 14 penetrates and that laser welding portion 14 has a welding defect.

On the other hand, as for the latter plasma generation amount, for example, as shown in FIG. 4 (when the foreign matter is oil), the plasma generation amount of oil is larger than the plasma generation amount in normal welding (shown by a broken line). The plasma generation amount (shown by the solid line) is larger by the amount.

The amount of plasma in FIG. 4 is the sum of the plasma generated from the laser welded portion 14 by the laser irradiation and the oil plasma when the oil has adhered to the laser welded portion 14. This is because the detection wavelength region of the ultraviolet sensor 17 is, for example, 400 to 65 which is the wavelength of oil plasma.
This is a wavelength region included in 0 nm (estimated value), and metal plasma (having a wavelength close to the wavelength region of oil) from the laser welded portion 14 is also detected by the ultraviolet sensor 17 at the same time. The detected plasma amount is 2 when welding is normal.
It ranges from double to quadruple.

Therefore, as shown in FIG. 4, based on the plasma generation amount increased from the normal welding state, the laser
It is possible to detect a welding defect occurring in the laser welded portion 14 due to an excessive amount of heat due to the combustion of the oil attached to the surface.

When an ultraviolet sensor 17 having a detection wavelength region wider than the wavelength of the oil plasma is used, it is possible to detect the adhesion of foreign matter other than oil, and when the attached foreign matter has a correlation with a welding defect. In addition, the welding defect can be evaluated.

Therefore, when the laser welded portion 14 penetrates and is defective, or when the laser welded portion 14
In the case where there is a foreign matter attached to the surface, the evaluation can be performed based on the amount of plasma detected by the ultraviolet sensor 17.

In addition, the poor welding that occurs when foreign matter adheres to the laser weld can also be evaluated based on the temperature of the laser weld 14 detected by the infrared sensor 18. That is, as shown in FIG. 5, when the welding is performed normally with a welding time of 20 ms, the temperature of the laser welded portion 14 also has a characteristic of being attenuated by the same degree as the welding time (indicated by a broken line). When oil adheres to the laser welded portion 14, the attenuation of the temperature of the laser welded portion 14 (shown by a solid line) is usually 30 ms or more. Further, the characteristic shown in FIG. 5 also occurs when foreign matter other than oil adheres to the laser welded portion 14.

If a welding defect due to the penetration of the laser welded portion 14 and a welding defect due to the adhesion of foreign matter occur simultaneously, an erroneous evaluation that the welding is apparently completed successfully only with the information from the ultraviolet sensor 17 alone. Will do. Also in this case, by referring to the information from the infrared sensor 18 (the characteristic shown in FIG. 5), it is possible to evaluate the presence or absence of foreign matter adhesion, that is, the quality of welding, from the attenuation of the temperature of the laser welded portion 14.

Therefore, even if welding failure due to penetration of the laser welding portion 14 and welding failure due to foreign matter adhesion occur at the same time, welding failure due to foreign matter adhesion can be detected based on information from the infrared sensor 18, and either one of them can be detected. Can be detected based on the information from the ultraviolet sensor 17, even if a welding defect occurs, the infrared sensor 18 and the ultraviolet sensor 17 can be used together to accurately and reliably detect one of the welding defects. It can be detected. Accordingly, there is no need to separately provide an inspection process in addition to the welding process, so that it is possible to prevent the process management from being complicated, and it is possible to automate and online the quality evaluation system of the welded portion.

Further, since the laser detecting means 19 detects the amount of reflected laser reflected from the laser welded portion 14, the amount of reflected laser when the laser welded portion 14 penetrates is significantly larger than the amount of reflected laser when welding is normal. The phenomenon of decrease can be grasped, whereby the welding defect accompanying the penetration of the laser welded portion 14 can be determined.

A second ultraviolet sensor 20 provided on the side opposite to the laser irradiation side of the laser welding part 14 detects the plasma passing through the laser welding part 14 and the second ultraviolet sensor 20 provided similarly.
The laser detecting means 21 detects a laser beam that has passed through the laser welding portion 14. When the second ultraviolet sensor 20 detects the plasma or the second laser detecting means 21 detects the laser light in this manner, the plasma or the laser light penetrates to the side opposite to the laser irradiation side, and the laser welding is performed. It can be determined that the portion 14 has penetrated both terminal portions 10 and 11.

At this time, the laser welding portion 14 is
As described above, FIG.
There is a state of (a) or (b), but the state shown in FIG. 6 (a) is a good case with no welding defect, and the plasma or laser detected by the second ultraviolet sensor 20 and the second laser detecting means 21. The amount of light is not very large. At this time, the amount of plasma generation detected by the ultraviolet sensor 17 and the amount of laser detected by the laser detector 19 are not significantly reduced. On the other hand, the state shown in FIG. 6B is a case where a welding defect has occurred, and the second ultraviolet sensor 20 and the second
The amount of plasma or laser light detected by the laser detecting means 21 is extremely large.

Therefore, the amount of plasma detected by the second ultraviolet sensor 20 becomes equal to or larger than a predetermined amount which is much larger than the case where there is no welding defect shown in FIG. If the amount of the detected laser beam is equal to or larger than a predetermined amount which is significantly larger than the case where there is no welding defect shown in FIG. Can be evaluated.

Therefore, according to the present embodiment,
By placing various sensors near the laser weld,
Since the quality of welds can be evaluated automatically and indirectly, online inspection is possible, so there is no need to provide an inspection process separately from the welding process as in the conventional inspection method. Can be prevented from becoming complicated, and moreover, only a sensor needs to be installed, so that a relatively inexpensive quality evaluation system can be provided.

In evaluating the welding failure due to the penetration of the laser weld, both the second ultraviolet sensor 20 and the second laser detecting means 21 may be provided. Is larger than the amount of transmission of the laser light, and it is preferable to provide the second ultraviolet sensor 20 when at least one is provided.

Further, in the above-described embodiment, it is possible to determine whether or not the laser welding portion 14 has penetrated, based on the variation of the plasma generation amount shown in FIG. Second UV sensor 20
The second laser detecting means 21 need not always be provided. However, if the laser detecting means 19, the second ultraviolet sensor 20, and the second laser detecting means 21 are used in combination, the accuracy of detection can be improved.

In the above-described embodiment, the tab terminals 10 housed in the electric connection box and the terminal portions 1 at the ends of the bus bars are provided.
1 and the case of electrical connection by welding, but the present invention is not limited to this, and the connection of the other two connection terminal portions housed in the electric connection box and the connection other than the electric connection box It is needless to say that the present invention can also be applied to the connection between two metal members, such as the connection between the electric component or the electronic component and the wiring.

[0049]

As described above in detail, in the case of the quality evaluation system for a welded part according to the first aspect of the present invention, an ultraviolet sensor for detecting the amount of plasma generated in the ultraviolet region is provided on the laser irradiation side of the laser welded part. And an infrared sensor for detecting the ambient temperature near the laser welded part, automatically and indirectly distinguishing between weld defects penetrated by the laser welded part and weld defects caused by oil adhesion at the laser welded part. Since the welded portion can be inspected, it is not necessary to separately provide an inspection process, so that the process management can be prevented from being complicated, and the quality evaluation system for the welded portion can be provided with relatively low equipment cost.

Further, in the case of the quality evaluation system for a welded portion according to the second aspect of the present invention, a laser detecting means for detecting the amount of reflected laser reflected from the laser welded portion is further provided on the laser irradiation side of the laser welded portion. Since the laser detection means detects the decrease in the amount of reflected laser due to the penetration of the laser weld, the laser detection means can more accurately and indirectly determine a welding defect due to the penetration of the laser weld.

In the case of the quality evaluation system for a welded portion according to the third aspect of the present invention, the second side for detecting the plasma passing through the laser welded portion in the ultraviolet region on the side opposite to the laser irradiation side of the laser welded portion. Since at least one of the ultraviolet sensor and the second laser detecting means for detecting the laser that has passed through the laser welding portion is further provided, the plasma or laser penetrated by the laser welding portion and penetrated to the side opposite to the laser irradiation side is provided. By detecting the light with the second ultraviolet sensor or the second laser detecting means, it is possible to more accurately and indirectly evaluate that the laser welding portion has penetrated and the welding is poor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram (perspective view) for explaining a basic principle of the present invention.

FIG. 2 is a perspective view showing a quality evaluation system for a welded portion according to an embodiment of the present invention.

FIG. 3 is a diagram showing a detection result of a plasma generation amount by an ultraviolet sensor provided in the weld quality evaluation system according to the embodiment of the present invention.

FIG. 4 is a diagram showing a detection result of a plasma generation amount by an ultraviolet sensor provided in the weld quality evaluation system according to the embodiment of the present invention.

FIG. 5 is a diagram showing a result of detecting a temperature of a laser welded part by an infrared sensor provided in the welded part quality evaluation system according to one embodiment of the present invention.

FIG. 6 (a) is a view showing a good case where there is no welding defect even when the laser welding portion penetrates, and FIG. 6 (b) is a case where a welding defect occurs when the laser welding portion penetrates; FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tab terminal part 11 Terminal part of the end part of a bus bar 12 Laser emission lens 13 Laser light 14 Welding point (laser welding part) 17 Ultraviolet sensor 18 Infrared sensor 19 Laser detecting means 20 Second ultraviolet sensor 21 Second laser detecting means

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshifumi Saka 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi F-term in Harness Research Institute, Ltd. 4E068 CA17 CC00 CC01 CC03

Claims (3)

[Claims] 1. A quality evaluation system for indirectly evaluating the quality of a laser welded part when two metallic members to be electrically connected to each other are welded by a YAG laser, the quality evaluation system comprising: The laser irradiation side is provided with an ultraviolet sensor that detects the amount of plasma generated from the laser weld in the ultraviolet region and an infrared sensor that detects the temperature of the laser weld. Evaluation system. 2. The welding part according to claim 1, further comprising a laser detecting means for detecting an amount of reflected laser reflected from the laser welding part on a laser irradiation side of the laser welding part. Quality evaluation system. 3. A second ultraviolet sensor for detecting, in an ultraviolet region, a plasma that has passed through the laser weld, on a side opposite to the laser irradiation side of the laser weld, and a second ultraviolet sensor that detects laser light that has passed through the laser weld. 3. The quality evaluation system for a welded part according to claim 1, wherein at least one of the two laser detecting means is further provided.