JP2007098442A - Laser joint quality inspecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser joint quality inspecting device where the erroneous judgement of joint quality is suppressed, and quality discrimination can be correctly performed. <P>SOLUTION: The laser joint quality inspecting device 1 for inspecting the quality of the joint by laser irradiation between a weldment 3 and the object 2 to be welded comprises: a reflected light intensity calculating means where reflected light from the joint is detected, and the time-integrated intensity of the reflected light is calculated; a plasma light intensity calculating means where plasma light from the joint is detected, and the time-integrated intensity of the plasma light is calculated; an infrared light intensity calculating means where infrared light from the joint is detected, and the time-integrated intensity of the infrared light is calculated; and a calculating apparatus 16 as a joint quality discriminating means where discriminatory analysis is performed using the time-integrated intensities of the reflected light, plasma light and infrared light as variables, and the quality discrimination of the weld quality in the joint from which each time-integrated intensity is detected is performed based on the result of the discriminatory analysis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser bonding quality inspection apparatus that inspects the bonding quality of a bonded portion between a bonded object and a bonded object when the bonded object and the bonded object are bonded by laser irradiation.

When joining a joined object and an object to be joined by laser irradiation and confirming the quality of the joined part such as the joining state, the surface of the joined part is irradiated with a laser, for example, based on the reflected light of the irradiated laser. The joint quality is checked.
Specifically, for example, as shown in Patent Document 1, the determination device measures the intensity of the reflected light from the received joint, compares the measured intensity with a predetermined threshold value, and joins them. It is determined whether the state is good or bad.
Moreover, as shown in FIG. 18, the quality determination of a joining state is performed by whether the measured reflected light intensity is in the range of a preset lower limit value to an upper limit value.
JP-A-5-335735

As described above, when it is determined whether or not the joining state is good depending on whether or not the intensity of the measured reflected light is within a predetermined range, noise is added to the detected value of the reflected light as shown in FIG. Sometimes, the noise peak exceeds the set upper limit, and an original product that is an OK product may be erroneously determined as an NG product.
In particular, unlike when noise is applied during continuous welding, when noise is applied during spot welding performed in a minute time (several tens of msec order), The peak is not negligible with respect to the entire laser irradiation time, and causes erroneous determination.
Therefore, the present invention provides a laser bonding quality inspection apparatus that can suppress erroneous determination of bonding quality and can accurately perform quality determination.

The laser bonding quality inspection apparatus that solves the above problems has the following characteristics.
That is, as described in claim 1, the laser bonding quality inspection apparatus performs laser bonding for inspecting the bonding quality of the bonded portion between the bonded object and the bonded object when the bonded object and the bonded object are bonded by laser irradiation. A quality inspection device for detecting reflected light of a laser irradiated on the joint and calculating a reflected light intensity calculating means for calculating a time integral intensity of the reflected light; and plasma light of plasma generated at the joint Plasma light intensity calculating means for detecting and calculating the time integrated intensity of the plasma light;
Infrared light intensity calculating means for detecting the infrared light emitted from the joint and calculating the time integrated intensity of the infrared light, the calculated time integrated intensity of the reflected light, and the time integrated intensity of the plasma light Discriminant analysis using each of the time integral intensities of infrared light as a variable, and determining whether or not the joint quality of each joint where the time integral intensities are detected is determined based on the result of the discriminant analysis. Determination means.
Thereby, discriminant analysis can be performed using three different types of time integrated intensities such as the time integrated intensity of reflected light, the time integrated intensity of plasma light, and the time integrated intensity of infrared light as variables, A highly reliable laser bonding quality inspection apparatus can be constructed that can accurately perform the quality determination of the bonding quality of the bonded portion that detects the time integrated intensity of reflected light, plasma light, and infrared light without erroneous determination. Is possible.

According to a second aspect of the present invention, the plasma light intensity calculation means detects the plasma light from the first spectrum obtained by spectrally extracting the return light from the joint irradiated with the laser, and detects the plasma light. A time integrated intensity is calculated, and the infrared light intensity calculating means further detects the infrared light from the second spectrum obtained by further separating the return light after the first spectrum is extracted, and The time integrated intensity is calculated, and the reflected light intensity calculating means detects the reflected light from the return light remaining after taking out the second spectrum, and calculates the time integrated intensity of the reflected light.
As a result, the plasma light component having the weakest intensity is extracted from the first spectrum obtained by the first spectroscopy, and the reflected light component having the strongest intensity is extracted from the remaining return light after the first spectrum and the second spectrum are extracted. Therefore, not only the reflected light but also the plasma light with the lowest intensity and the infrared light with the next lowest intensity can be reliably detected.

  According to the present invention, it is possible to accurately determine the quality of a bonded portion of a bonded portion obtained by bonding a bonded object and an object to be bonded by laser irradiation without erroneous determination, and to provide a highly reliable laser bonding quality inspection apparatus. It can be configured.

  Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a laser joining quality inspection device 1 according to the present invention includes an irradiation nozzle 11 that irradiates a welded product 2 that is a joined product, which is joined to a workpiece 3 that is a joined product, and a laser beam. , A light guide 12 extending in the horizontal direction from the top of the irradiation nozzle 11, a plasma light sensor 13 for detecting plasma light guided to the light guide 12, and infrared light guided to the light guide 12. A temperature sensor 14 for detection and a reflected light sensor 15 for detecting reflected light guided to the light guide path 12 are provided.

In addition, a folding lens 21 composed of a half mirror is provided in the irradiation nozzle 11, and the folding lens 21 allows the laser beam to be emitted from the joint between the welded material 2 and the workpiece 3. The return light 5 is guided to the light guide path 12.
A first spectroscopic lens 22 and a second spectroscopic lens 23 are provided in the light guide path 12, and the return light 5 guided to the light guide path 12 is first spectrally separated by the first spectroscopic lens 22. The light is split by the two spectroscopic lens 23.

  The return light 5 is split by the first spectroscopic lens 22 and the extracted first spectroscope 5 a is detected by the plasma light sensor 13, and the second spectroscopic 5 b that is spectroscopically extracted by the second spectroscopic lens 23 is The remaining light 5 c detected by the temperature sensor 14 and separated by the second spectroscopic lens 23 and extracted from the second spectroscopic 5 b is detected by the reflected light sensor 15.

The plasma light sensor 13 is provided with a plasma light filter 13a through which only plasma light can pass. In the plasma light sensor 13, only the plasma light component that has passed through the plasma light filter 13a in the first spectrum 5a. Detected.
Further, the temperature sensor 14 is provided with an infrared light filter 14a through which only infrared light can pass. In the temperature sensor 14, the infrared light that has passed through the infrared light filter 14a in the second spectrum 5b. Only the light component is detected.
Further, the reflected light sensor 15 is provided with a reflected light filter 15a through which only reflected light can pass. In the reflected light sensor 15, only the reflected light component that has passed through the reflected light filter 15a out of the remaining light 5c. Is detected.

  As shown in FIG. 2, the plasma light component, the infrared light component, and the reflected light component included in the return light 5 are detected in different wavelength bands, so that the plasma light filter 13a, the infrared light filter 14a, And by using the reflected light filter 15a, it is possible to detect each of the components individually.

  The plasma light component detected by the plasma light sensor 13, the infrared light component detected by the temperature sensor 14, and the reflected light component detected by the reflected light sensor 15 are respectively input to the calculation device 16 and calculated. It is processed and the quality determination of a junction part is performed.

Here, the plasma light component is detected from the first light spectrum 5a obtained by spectrally separating the return light 5, and
The infrared light component is detected from the second light 5b obtained by further separating the return light 5 after the first light 5a is extracted, and the reflected light component is the remaining light 5c after the second light 5b is extracted. This is detected from the following reason.

That is, the components included in the return light 5 have different light intensities, and the intensities increase in the order of plasma light <infrared light <reflected light.
On the other hand, as shown in FIG. 3, when the light is split for extracting each component, the return light 5 is attenuated as the light is split, and the intensity of the return light 5 is weakened.
Accordingly, the plasma light component having the weakest intensity is extracted from the first light spectrum 5a that is first spectrally separated, and the reflected light component having the strongest intensity is extracted from the remaining light 5c after the first light spectrum 5a and the second light spectrum 5b are extracted. Thus, plasma light having a low intensity is reliably detected.

  4 is irradiated from the irradiation nozzle 11, the waveform of the plasma light detected by the plasma light sensor 13 has a shape as shown in FIG. 5, for example, and the temperature sensor The waveform of the infrared light detected at 14 has a shape as shown in FIG. 6, for example, and the waveform of the reflected light detected at the reflected light sensor 15 has a shape as shown in FIG.

Then, in the arithmetic unit 16, the intensity values of the plasma light component, the infrared light component, and the reflected light component detected as described above are integrated, and the time integrated intensity of the plasma light obtained by integration, The quality of the joint is determined based on the time integrated intensity of infrared light and the time integrated intensity of reflected light.
For example, the time integrated intensity of the reflected light is represented by the area of the hatched portion in FIG.

  In this example, the reflected light intensity calculating means for detecting the reflected light from the return light 5 of the laser irradiated on the joint and calculating the time integral intensity of the reflected light includes the reflected light sensor 15 and the calculation device. The plasma light intensity calculation means for detecting the plasma light from the return light 5 and calculating the time integrated intensity of the plasma light is constituted by the plasma light sensor 13 and the calculation device 16, and the return light The infrared light intensity calculating means for detecting the infrared light emitted from the light 5 and calculating the time integrated intensity of the infrared light is composed of an infrared light sensor 14 and a calculation device 16.

Thus, by using the value of the time integral intensity of each light to determine the quality of the joint between the welded article 3 and the workpiece 2, even when a noise component is spotted on the waveform of each light, The noise component hardly affects the quality of the joint.
That is, as shown in FIG. 8, for example, a detection waveform of reflected light without noise (left diagram in FIG. 8) is compared with a detection waveform of reflected light with noise (right diagram in FIG. 8). In this case, since the area of the hatched portion indicating the time integrated intensity hardly changes, even if the quality of the joint is determined based on the time integrated intensity value, it is hardly affected by noise.

The judgment of quality of the joint based on the time integrated intensity by the arithmetic device 16 is specifically performed by discriminant analysis.
Discriminant analysis is a method commonly used for the purpose of determining which group each data belongs to based on several variables.
In the present invention, this discriminant analysis is used to determine the quality of the joint, and the time integral intensity of the plasma light, the time integral intensity of the infrared light, and the time integral intensity of the reflected light are each used as variables. This detection data is acquired, and it is determined which of the two groups of the non-defective product group and the defective product group each of the acquired detection data belongs to.

As a procedure for performing discriminant analysis, first, detection data of time integrated intensities of plasma light, infrared light, and reflected light are respectively acquired.
After obtaining the detection data, an equidispersity test is performed, such as whether or not the variances of the detection data of each group are equal.
Next, a discriminant function is obtained. In this case, when it is determined that the dispersibility is equal by the above-described equidispersity test, a discriminant function is obtained by linear discrimination, and when it is determined that the dispersibility is not equal, the discrimination is performed by second group quadratic discrimination. Find a function.

Then, a boundary between two groups (a non-defective product group and a defective product group) is determined by the obtained discriminant function. In addition, the variance of each group is digitized using Mahalanobis's general distance, and the variance of each group and the boundary are expressed on a graph.
FIG. 9 shows the variance and the boundary B represented on the graph.
On the graph shown in FIG. 9, the detection data positioned on the right side of the boundary B is determined as a non-defective product, and the detection data positioned on the left side of the boundary B is determined as a defective product.

  In this case, all the detection data in which the joint portion is actually in a non-defective state is located on the right side of the boundary B, and all the detection data in which the joint portion is actually in a defective state is located on the left side of the boundary B. It can be seen that an accurate pass / fail judgment is made without erroneous judgment.

  In this way, by performing discriminant analysis using three types of data such as the time integrated intensity of plasma light, the time integrated intensity of infrared light, and the time integrated intensity of reflected light as variables, it is possible to perform accurate pass / fail without erroneous determination. Judgment is possible.

  On the other hand, as shown in FIG. 10, when discriminant analysis is performed using only one of the time integrated intensity of plasma light, the time integrated intensity of infrared light, and the time integrated intensity of reflected light. (FIG. 10 shows the case where only plasma light is used), not only non-defective products but also defective products are mixed on the right side of the boundary B and not only defective products but also non-defective products on the left side of the boundary B. Are mixed, and there are many misjudgments, and accurate pass / fail judgments cannot be made.

  In addition, as shown in FIG. 11, when the discriminant analysis is performed using any two of the time integrated intensity of plasma light, the time integrated intensity of infrared light, and the time integrated intensity of reflected light ( FIG. 11 shows the case where plasma light and reflected light are used), but the frequency of misjudgment is low compared to the case where only one type of detection data shown in FIG. In addition to non-defective products, not only non-defective products but also non-defective products are mixed on the left side of the boundary B, and there is a misjudgment and it cannot be said that an accurate pass / fail judgment is made. .

  As described above, in the arithmetic device 16 serving as the bonding quality determination means, three different types of time integrated intensities such as the time integrated intensity of reflected light, the time integrated intensity of plasma light, and the time integrated intensity of infrared light are respectively determined. By using discriminant analysis as a variable, it is possible to accurately determine the quality of the bonded portion of the joint that has detected the time integrated intensity of the reflected light, plasma light, and infrared light without erroneous determination, and to reliably It is possible to configure a highly reliable laser bonding quality inspection apparatus.

Note that the types of variables used for discriminant analysis are not limited to the three types as in this example, and more types of variables can be used. For example, it is possible to perform discriminant analysis by adding the laser output shown in FIG. 4 as a fourth variable.
Thus, by performing discriminant analysis by increasing the types of variables, the accuracy of the pass / fail judgment can be further improved.

In addition, in the configuration in which the light guide path 12 and the first and second spectroscopic lenses 23 are provided in the irradiation nozzle 11 as in this example, it is easy to detect three types of light outputs, but as shown in FIG. In addition, if the light output is to be detected only by the irradiation nozzle 11 without providing the light guide path 12, it is difficult to detect a plurality of types of light outputs as they are.
However, by processing the irradiation nozzle 11 as follows, a plurality of types of light outputs can be detected without providing the light guide path 12.

First, as shown in FIG. 13, by constructing a part of the tip 11a of the irradiation nozzle 11 into light transmitting parts 11b and 11b made of a light transmitting member, the return light 5 from the joint part is obtained. The light transmission parts 11b and 11b can be taken out and detected. Thereby, a plurality of types of light outputs can be detected.
The light transmission part 11b can be comprised by transparent resin members, such as PMMA, for example, and can be formed in the multiple places of the front-end | tip part 11a.

  Further, as shown in FIG. 14, in the tip end portion 11 a of the irradiation nozzle 11, a part of the side wall is cut out to form a cutout portion 11 c in which the cross-sectional shape of the tip end portion 11 a is substantially “C” shape. By doing so, it becomes possible to extract the return light 5 from the joint portion to the outside from the notch portion 11c. Thereby, a plurality of types of light outputs can be detected.

  Further, as shown in FIG. 15, at the tip 11a of the irradiation nozzle 11, openings 11d and 11d are opened on the side walls, and the return light 5 from the joint is taken out from the openings 11d and 11d. It can also be. Thereby, a plurality of types of light outputs can be detected. The opening 11d can be formed at a plurality of locations on the tip 11a.

  Also, as shown in FIG. 16, a detection sensor 19 for detecting the light output is embedded in the tip end portion 11 a of the irradiation nozzle 11, so that a plurality of types of light outputs can be obtained from the return light 5 from the joint portion. Can be detected. The detection sensor 19 can be embedded in a plurality of locations of the tip portion 11a.

Further, as described above, in the laser bonding quality inspection apparatus 1, the time of plasma light, infrared light, and reflected light is determined from the detected intensity values of the plasma light component, infrared light component, and reflected light component, respectively. The occurrence of erroneous determination is suppressed by obtaining the integrated intensity and determining the quality of the joint based on these time integrated intensity. However, the erroneous determination can also be suppressed by configuring as follows.
For example, as shown in FIG. 17, the noise peak on the detected reflected light intensity value is cut using a filter, and the determination of the joint quality is performed after the noise peak is cut, thereby making an erroneous determination. Can be prevented from occurring.

It is the schematic which shows the laser joining quality inspection apparatus concerning this invention. It is a figure which shows the emission peak of plasma light, infrared light, and reflected light. It is a figure which shows a mode that the return light from a junction part attenuate | damps by spectroscopy. It is a figure which shows the pulse shape of a laser output. It is a figure which shows the waveform of the detected plasma light intensity. It is a figure which shows the waveform of the detected infrared light intensity. It is a figure which shows the waveform of the detected reflected light intensity. It is the figure which compared the time integral intensity | strength of the reflected light in the state where noise has not carried, and the time integral intensity | strength of the reflected light in the state where noise was carried. It is a figure which shows the discrimination | determination result at the time of discriminant analysis using three types, the time integral intensity of plasma light, the time integral intensity of infrared light, and the time integral intensity of reflected light. It is a figure which shows the discrimination | determination result at the time of performing discriminant analysis using only any one among the time integration intensity of plasma light, the time integration intensity of infrared light, and the time integration intensity of reflected light. It is a figure which shows the discrimination | determination result when discriminant analysis is performed using any 2 types among the time integral intensity of plasma light, the time integral intensity of infrared light, and the time integral intensity of reflected light. When it is going to detect light output only with an irradiation nozzle, it is a figure which shows the situation where it is difficult to detect multiple types of light output as it is. It is a figure which shows the irradiation nozzle which comprised a part of front-end | tip part with the member which permeate | transmits light. It is a figure which shows the irradiation nozzle which notched a part of side wall of the front-end | tip part. It is a figure which shows the irradiation nozzle which opened the opening part in the side wall of a front-end | tip part. It is a figure which shows the irradiation nozzle which embedded the detection sensor for detecting a light output inside the front-end | tip part. It is a figure which shows a mode that the noise peak on the detected reflected light intensity value is cut using a filter. It is a figure which shows the quality determination method of the conventional junction part. It is a figure which shows a mode that a misjudgment arises in the conventional quality determination method of a junction part, when noise gets on the detected value of reflected light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser joining quality inspection apparatus 2 To-be-welded object 3 Welded object 5 Return light 5a 1st light beam 5b 2nd light beam 5c Remaining light 11 Irradiation nozzle 12 Light guide path 13 Plasma light sensor 14 Infrared light sensor 15 Reflected light sensor 16 Calculation apparatus 22 First spectroscopic lens 23 Second spectroscopic lens

Claims (2)

A laser bonding quality inspection device that inspects the bonding quality of a bonded portion between a bonded object and a bonded object when bonding the bonded object and the bonded object by laser irradiation,
Reflected light intensity calculating means for detecting the reflected light of the laser irradiated to the joint and calculating the time integrated intensity of the reflected light;
Plasma light intensity calculating means for detecting plasma light of plasma generated at the joint and calculating time integrated intensity of the plasma light;
Infrared light intensity calculating means for detecting the infrared light emitted from the joint and calculating the time integrated intensity of the infrared light;
Discriminant analysis was performed using the calculated time integral intensity of reflected light, time integral intensity of plasma light, and time integral intensity of infrared light as variables, and the joint quality of the joint where each time integral intensity was detected was detected. Having a bonding quality determination means for performing pass / fail determination based on the result of the discriminant analysis;
Laser bonding quality inspection apparatus characterized by the above. The plasma light intensity calculating means detects the plasma light from the first spectrum obtained by spectrally separating the return light from the joint irradiated with the laser, and calculates the time integrated intensity of the plasma light,
The infrared light intensity calculation means detects infrared light from the second spectrum obtained by further separating the return light after taking out the first spectrum, and calculates the time integrated intensity of the infrared light,
The reflected light intensity calculating means detects the reflected light from the return light remaining after taking out the second spectrum, and calculates the time integrated intensity of the reflected light;
The laser bonding quality inspection apparatus according to claim 1.