JP3997183B2 - Welding condition inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welding condition inspection method relates to the welding condition inspection method capable of inspecting the welded state of the weld deposit with high precision, especially using a laser beam.
[0002]
[Prior art]
In recent years, in order to reduce weight and cost, a resin molded product obtained by converting each part in an automobile or the like into a resin is sometimes used. Further, from the viewpoint of increasing the productivity of the resin molded product, the resin molded product is divided into a plurality of pieces in advance, and these divided molded products are joined to each other.
[0003]
In general, as a method of welding resin materials, bonding with an adhesive or the like has been performed, but since the bonding may be peeled off due to heat, recently, by using a laser beam to heat and melt the resin material, A joining method is used.
[0004]
Also, as a welding method, after superposing a transparent resin material that is transparent to laser light and an absorbent resin material that is absorbing to laser light, laser light is emitted from the transparent resin material side. There is a laser welding method in which the contact surfaces of a permeable resin material and an absorptive resin material are heated and melted by irradiation to integrally bond the two (see, for example, Patent Document 1).
[0005]
In addition, when performing a weld quality judgment as to whether or not a desired weld has been made on the welded welded material, the worker has made a quality judgment by manual sampling and visual inspection. Was. In order to cope with this, there is a technique related to a welding determination device that provides a temperature sensor to obtain a temperature difference in the vicinity of an object to be welded before and after welding and makes a pass / fail judgment based on the temperature difference (see, for example, Patent Document 2). ).
[0006]
Furthermore, the light source and the image sensor are installed in association with each other, are incident on the sample at a predetermined incident angle, and based on the interference light intensity distribution on the incident surface of the reflected light from the sample, the film thickness and surface of the minute region There is a technique for measuring a shape (see, for example, Patent Document 3).
[0007]
A method of inspecting the welded state by receiving the welded state irradiated to the joint surface by the inspection light source using these techniques can be considered.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-105499
[Patent Document 2]
Japanese Patent Laid-Open No. 10-249941
[Patent Document 3]
Japanese Patent Laid-Open No. 8-82511
[Problems to be solved by the invention]
However, in patent document 2, since it is necessary to add apparatus structures, such as a temperature sensor, separately from a welding apparatus, cost will increase. In addition, it is necessary to provide at least two temperature sensors for detecting the temperature in the vicinity of the object to be welded before and after welding in the determination device, and the temperature difference is calculated from the measured temperature from the temperature sensor. Since it is determined from the temperature difference and further compared with a predetermined value set in advance from the temperature difference to determine whether the welding is good or bad, the control is complicated and it cannot be said that the determination (inspection) of the welding state is performed efficiently. .
[0012]
Furthermore, when the method of Patent Document 3 is used, it is easy to inspect the welding state of the welded surface by visual inspection or a light source for inspection when the resin on the surface side is transparent when the surface is welded by the lap joint. is there. However, when the resin on the surface side has a certain color or the inspection light source is dark, inspection by visual inspection or inspection light source is not easy. This is because the monitoring point of the light receiving unit is positioned at the irradiation point of the inspection light source, and in the inspection by the inspection light source, the reflected light can be accurately received by the influence of the reflected light from the bonding surface and the scattered light in the resin. This is because it is impossible to perform a highly accurate inspection of the welded state due to these factors.
[0013]
The present invention has been made in view of the above-described problems, and provides a welding state inspection method capable of inspecting a welding state of a welded material made of resin using a laser beam with high accuracy. Objective.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs means for solving the problems having the following characteristics.
[0015]
The invention described in claim 1 is a welding state inspection method for inspecting a welding state of a welded portion by welding a welding object with a laser beam output from a laser oscillator. Based on a laser beam irradiation stage for irradiating the welding surface with laser light for inspecting the welding state, and a preset distance from the irradiation point of the laser light irradiated in the laser beam irradiation stage for inspection The second scattered light generated by the reflected light obtained by reflecting the first scattered light generated when the laser light is incident on the object to be welded at the offset point is reflected by the welding surface. And a light receiving stage.
[0016]
According to the first aspect of the present invention, the welding state of the object to be welded can be inspected with high accuracy by offsetting the light receiving point by a predetermined distance from the irradiation point . Specifically, the scattered light (first scattered light) generated by the laser light incident on the object to be welded from the laser oscillator is irradiated onto the welding surface, and the reflected light reaches the resin surface while being scattered . By receiving the scattered light (second scattered light), highly accurate welding determination can be realized.
[0017]
According to a second aspect of the present invention, in the light receiving step, at least one of an X-axis, a Y-axis, or a Z-axis with respect to the incident surface of the inspection laser light based on a preset distance from the irradiation point. It is characterized by offsetting in one axial direction.
[0018]
According to the second aspect of the present invention, the three-dimensional movement to the X axis, the Y axis, or the Z axis is performed to cope with the influence of the scattered light on the material of the welded material, the transmittance with respect to the laser beam, and the like. Highly accurate light reception can be performed. Thereby, highly accurate welding determination is realizable.
[0019]
According to a third aspect of the present invention, the light receiving step receives light by changing the optical axis of the light source irradiated in the inspection laser light irradiation step by a predetermined angle in the horizontal direction with respect to the focal plane. Features.
[0020]
According to the third aspect of the present invention, the reflected light from the welding surface by the first scattered light is received by receiving the optical axis for irradiating the laser light at a predetermined angle in the horizontal direction with respect to the focal plane. Since it is possible to receive only the scattered light (second scattered light) in the reflected light without directly receiving light, it is possible to receive light at the light receiving point with high accuracy.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
First, an outline of the present invention will be described. FIG. 1 is an example of a state of welding of resins. In FIG. 1, welded materials 10-1 and 10-2 overlap each other, and the contact surfaces are heated and melted by being irradiated with laser light to be welded.
[0028]
Here, when the welded portion is viewed from the welded material 10-1 that is transparent to the laser beam, the color of the welded portion 11 is observed as compared with the non-welded portion. Therefore, a light source having energy that does not overheat as a measurement light source is irradiated on the contact surfaces of the welded materials 10-1 and 10-2 after welding, and the reflected light is received by the light receiving unit. Judgment is made.
[0029]
However, when the light irradiated from the light source is irradiated on the contact surface, the light incident in the welded object 10-1 is scattered. Since the light receiving portion is affected by the scattered light, it is impossible to make a highly accurate judgment based on the reflected light from the contact surface.
[0030]
Therefore, the present invention receives light at a position shifted by a predetermined interval from the irradiation point of light irradiated from the light source. Here, the outline | summary of the test | inspection method of the welding state in this invention is demonstrated using figures.
[0031]
FIG. 2 is a diagram showing an example of an overview of the welding state inspection method according to the present invention.
[0032]
As for FIG. 2, the inspection light source 21 is irradiated on the welding surfaces of the welded materials 10-1 and 10-2, and the light content on the contact surface is received by the light receiving unit 22. Further, with respect to the laser beam irradiated to the incident angle θ ₁ on the contact surface and the light receiving angle θ ₂ corresponding to the incident angle θ ₁ in the light receiving unit 22, the position corresponding to the incident point of the inspection light source is set. The light receiving unit 22 is positioned (dotted line portion in FIG. 2).
[0033]
However, when such a light receiving portion 22 is positioned, the reflected light and the scattered light interfere with each other as shown in FIG. Inability to perform inspection.
[0034]
Therefore, the light receiving unit 22 is positioned at a position offset from the irradiation point by a predetermined interval (Δd), thereby directly receiving the reflected light in the welded part 10-1 and reducing the influence of the reflected light. Light can be received with high accuracy.
[0035]
The offset shifting direction may be not only the offset in the X axis direction and the Y axis direction on the weld surface of the resin, but also the offset in the Z direction (height direction). It may be shifted to.
[0036]
As described above, the present invention enables the light receiving unit to receive the reflected light with respect to the welding surface irradiated from the light source without being affected by the scattered light (first scattered light) in the resin. The monitoring point of the unit is offset by a predetermined distance from the irradiation point . That is, since the reflected light of the scattered light (first scattered light) inside the resin irradiated to the welding surface reaches the resin surface while being scattered, by receiving this scattered light (second scattered light), As the light received by the light receiving unit, the reflected light from the surface of the irradiation point and the scattered light (first scattered light) obtained by the laser light irradiated to the irradiation point can be reduced , and a highly accurate welding state can be achieved . Inspection can be realized.
[0037]
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of a schematic configuration diagram of a welding state inspection apparatus according to the present invention. 3 includes a laser oscillator 31, a laser emitting optical system 32, a condensing optical system 33, a bandpass filter 34, a CCD camera 35, a positioning monitor 36, a light receiving sensor 37, A data measuring device 38 and a stage 39 are included. Further, weld deposit 10 is freely fixedly mounted detachably on the stage 39. Here, as an example of the weld 10, the welds 10-1 and 10-2 are both PA (polyamide), and for the color, the weld 10-1 is natural, and the weld 10-2 is Use carbon black. Incidentally, not limited to this on the material, for example, as long as it is a resin, can be used PP (polypropylene), PC (Porika volume sulfonate) or the like.
[0038]
The laser oscillator 31 irradiates an inspection laser light source having such energy that the welded material is not heated and melted. For example, a laser beam with a wavelength of 808 nm is emitted from a diode laser.
[0039]
The stage 39 is an XYZθ table, which can move in the front-rear and left-right directions (X and Y directions) and the up-down direction (Z direction) with respect to the irradiation direction of the laser beam, and the stage with respect to the irradiation axis Can be tilted by an inclination angle θ. By moving the stage 39 in this way, a desired inspection area can be inspected. Further, the irradiation angle and the light receiving angle of the inspection laser light can be changed.
[0040]
The laser light source output from the laser oscillator 31 is input to the laser emission optical system 32 via the beam transmission fiber.
[0041]
In the laser emission optical system 32, the welded material 10 to be inspected is condensed by the optical system so that the surface of the welded material 10-1 is spot-irradiated with a spot diameter of Φ0.8 mm. Further, the condensed laser light source is irradiated onto the welded material 10.
[0042]
On the light receiving side, offset by a predetermined interval is performed while referring to the image information from the CCD camera 35 provided for positioning for adjusting the position of the light receiving unit on the positioning monitor 36.
[0043]
After the monitoring point of the light receiving unit is offset by a predetermined distance from the irradiation point, the condensing optical system 33 receives the reflected light on the bonding surface irradiated to the welded material 10 directly from the reflected light in the resin. Instead, the light of only the scattered light at the set point is collected, and the bandpass filter 34 extracts only the desired laser light from the received laser light and receives it by the light receiving sensor 37. Next, the energy information received by the light receiving sensor 37 is A / D converted by the data measuring device 38 to obtain data.
A predetermined operation is performed on the stage 39 in the above flow, and the light receiving energy of the welded portion and the non-welded portion is continuously acquired. Here, the state of light reception in the above-described stage movement will be described with reference to the drawings.
[0044]
FIG. 4 is a diagram illustrating an example of an inspection of a welding state. FIG. 4 shows the laser emission optical system 32 and the condensing optical system 33 in the welding state inspection apparatus 30.
[0045]
As described above, the light receiving side has an offset of a predetermined interval Δd from the laser irradiation point, and is not directly affected by the reflected light. The welded material 10 installed on the stage 39 moves in the direction of arrow A shown in FIG. 4, that is, the X-axis direction, thereby easily receiving the reflected light on the contact surface between the welded part 11 and the non-welded part. be able to. Further, since the stage 39 can move to the XY axes, it can acquire light reception data for the points on the contact surface.
[0046]
The data measuring device 38 inspects the welded state by comparing the received light levels received at the accumulated welded part and the non-welded part. In addition, by having a monitor in the data measuring device 38, it is possible to easily perform display output of a light reception level accumulation result, an inspection result, and the like.
[0047]
The light receiving unit can receive the scattered light in which the influence of the reflected light is reduced, and can inspect the welding state with high accuracy.
[0048]
In FIG. 4, the laser emission optical system 32 and the condensing optical system 33 are positioned coaxially (on the X axis in FIG. 4). That is, the light receiving unit having the condensing optical system 33 is positioned by the reflection angle corresponding to the incident angle. This makes it easy to be affected by reflected light. However, in the present invention, the reflected light and the scattered light are received to inspect the welded state of the resin, so that the optical axis for irradiating the laser beam in the laser emission optical system 32 is other than perpendicular to the focal plane. By positioning the light receiving portion with an angle, it is possible to receive only the scattered light in the reflected light without directly receiving the reflected light, so that the light can be received at the light receiving point with high accuracy.
[0049]
Here, the above-mentioned content is demonstrated using figures. FIG. 5 is a diagram for explaining a light receiving position in the present invention. In addition, FIG. 5 has shown the figure seen from the welded material 10-1 side. Assume that the laser emission optical system 32 is positioned on the X axis shown in FIG. 5 as shown in FIG. In FIG. 4, the light receiving unit 51 is positioned at a position that is offset by a predetermined interval (Δd) from the irradiation point of the laser beam from the laser emission optical system 32.
[0050]
Here, as described above, it moves with a predetermined angle so as not to be affected by the reflected light. For example, in FIG. 5, by positioning from the position of the light receiving unit 51-1 so as to receive light from the light receiving unit 51-2 or the light receiving unit 51-3 on the Y axis, the laser beam irradiation point light is received from that position. Thus, it is possible to receive light that is not directly affected by the reflected light. By comparing the received light level of the welded portion thus received with the received light level of the non-welded portion, the welded state can be easily inspected.
[0051]
In FIG. 5, the movement is performed with a turning angle of 90 °, but in the present invention, it is not limited to this and may be changed to another angle. However, since the light received from the same direction as the direction of the incident laser light also receives the light of the incident light itself, the light receiving unit 51-1 positioned on the same axis shown in FIG. It is preferable to set in the range of 90 °. In addition, even when it is not positioned on the same axis, it has a predetermined interval offset due to the influence of the material of the welded material, the reflected light, the scattered light in the reflected light, etc., enabling more accurate light reception and the welding state This inspection can be easily realized.
[0052]
Here, an example of the received light level in the welding state inspection apparatus according to the present invention will be described with reference to the drawings. Note that the example shown in FIG. 6 is a data example of the received light level accumulated in the data measuring device 38 in the present embodiment.
[0053]
FIG. 6 is a diagram illustrating an example of inspection contents based on the light reception level. Here, FIG. 6A shows a state of the light reception level in a state where no offset is performed, and FIG. 6B shows a state of the light reception level in a state where the offset is performed in the present invention. is there. 6A and 6B, the horizontal axis indicates time (ms), and the vertical axis indicates the signal level (V) of the light receiving sensor.
[0054]
Further, as the sample to be inspected, the above-described materials (welded materials 10-1 and 10-2) are used, and the laser light source output from the laser oscillator 31 has a wavelength of 808 nm and an output of 0.8 W. Is used. Further, the incident angle from the laser emission optical system to the welded material 10 is 20 °, and the turning angle is 0 ° (that is, positioned coaxially with the incident laser optical axis).
[0055]
As shown in FIG. 6A, when the light receiving point of the light receiving unit is the same as the irradiation point, the difference in the light receiving level between the welded part and the non-welded part cannot be recognized. However, as shown in FIG. 6 (b), which is the result of receiving the light with an offset in the present invention, the light receiving level at the welded portion is changed as compared with the non-welded portion (FIG. 6 (b) Mar 1, Mull 2 and Mull 3). That is, in the welded surfaces of the welded materials 10-1 and 10-2, in the case of a non-welded portion, there is a gap between the welded materials, and thus the light from the inspection light source is reflected at the interface of the welded material 10-1. For this reason, the intensity of the light received by the light receiving unit increases. On the other hand, in the case of the welded portion, since there is no gap between the welded materials, the light from the inspection light source is absorbed by the welded material 10-2. Therefore, as shown in FIG. 6 (b) circle 1, circle 2, and circle 3, the intensity of light received by the light receiving portion is reduced. Thereby, the quality of the welding state can be determined with high accuracy.
[0056]
Further, the data measuring device 38 can inspect the welded state of the resin with higher accuracy and efficiency by performing an error display or recording data according to a predetermined light reception level. it can.
[0057]
As described above, according to the present invention, the light receiving point of the light receiving unit is offset by a predetermined distance from the irradiation point, so that the light received by the light receiving unit is reflected from the surface of the irradiation point and the irradiation point. Scattered light (first scattered light) obtained by the laser light applied to can be reduced, and the welded state can be inspected with high accuracy. Thereby, it is possible to realize a highly accurate inspection of the welding state by comparing the light receiving level of the welded portion with the light receiving level of the non-welded portion.
[0058]
In addition, by positioning the light receiving unit with the optical axis for irradiating the laser light at an angle other than perpendicular to the focal plane , light can be easily received at a position where the reflected light from the irradiation point surface is not directly received. Can do.
[0059]
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.
[0060]
【The invention's effect】
As described above, according to the present invention, it is possible to inspect the welded state of the welded material with high accuracy using laser light.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a state of welding between resins.
FIG. 2 is a diagram showing an example of an outline of a welding state inspection method according to the present invention.
FIG. 3 is a diagram showing an example of a schematic configuration diagram of a welding state inspection apparatus according to the present invention.
FIG. 4 is a diagram showing an example of a welded state inspection.
FIG. 5 is a diagram for explaining a light receiving position in the present invention.
FIG. 6 is a diagram illustrating an example of inspection contents based on a light reception level.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Welding object 11 Welding part 21 Inspection light source 22, 51 Light-receiving part 30 Welding state inspection apparatus 31 Laser oscillator 32 Laser emission optical system 33 Condensing optical system 34 Band pass filter 35 CCD camera 36 Positioning monitor 37 Light receiving sensor 38 Data measuring apparatus 39 stage

Claims (3)

In the welding state inspection method for inspecting the welded state of the welded part by welding the object to be welded by the laser light output from the laser oscillator,
A laser beam irradiation stage for inspection that irradiates a laser beam for inspecting the welding state on the welding surface of the object to be welded;
First generated by the laser light entering the welding object at a point offset based on a predetermined distance from the irradiation point of the laser light irradiated in the inspection laser light irradiation step. And a light receiving step for receiving second scattered light generated by the reflected light obtained by reflecting the scattered light on the welding surface. The light receiving step includes
2. An offset is performed in at least one axial direction of an X axis, a Y axis, or a Z axis with respect to an incident surface of the inspection laser light based on a preset distance from the irradiation point. The welding state inspection method described in 1. The light receiving step includes
The welding state inspection method according to claim 1 or 2, wherein the optical axis of the light source irradiated in the inspection laser light irradiation step is received by changing a predetermined angle in a horizontal direction with respect to a focal plane. .

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