JPH1177363A - Method for inspecting fillet weld part, and device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the penetration depth of the fillet welding of stainless steel by detecting the change in the quantity of the reflected beam of the projected beam in the vicinity of a welded part to measure the melting boundary height, and estimating the penetration depth front the relationship between the melting boundary height measured by changing the target position in advance and the penetration depth. SOLUTION: The point E denotes the height of the melting boundary, H denotes the melting height, and 1 denotes the penetration depth in the direction to indicate the substantial strength of a joint. The change in the intensity of the reflected beam of the spot beam perpendicular to a perpendicular plate 3 is measured by vertically moving an irradiator, and the height E of the melting boundary is obtained. The change in the quantity of the reflected beam can be sensed by the voltage or the difference in brightness of the image. The correlation between the melting height H and the penetration depth I is considered with the output of the laser beam, the focal distance and the target position as the major parameters. If the correlation diagram of the melting height H and the penetration depth I is prepared under the assumption that the output and the focal distance of the laser beam are constant, the penetration depth I can be estimated through comparison with the correlation diagram.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a fillet weld of stainless steel and an inspection apparatus used for the method.

[0002]

2. Description of the Related Art Conventionally, as a method of inspecting a fillet welded portion, as shown in FIG. 1, a welded portion 1 is cut at several places, a cut surface is polished, and a portion which is corroded and melted is confirmed. As shown in FIG. 2, a destructive inspection by a macro test method for measuring the dimensions of the penetration depths d and d 'has been frequently used.

[0003]

The method based on the above-described destructive inspection does not guarantee the penetration depth of the actual product. That is, when the welding is performed under the same welding conditions as the welded portion where the penetration depth is measured, it is estimated that the penetration will be the same, but it is currently generally used.

[0004] In order to compensate for the drawback that does not guarantee the penetration depth of the actual product, a method of measuring the amount of residual melting by ultrasonic waves has been proposed. However, since this method has an estimation accuracy of 1 mm unit, There is a problem that can be applied only when the plate thickness is as large as about 10 mm. In addition, there was a problem that stainless steel was difficult to apply due to severe attenuation of ultrasonic waves.

An object of the present invention is to solve such a problem. An inspection method and an inspection apparatus used for estimating an actual penetration depth of a stainless steel fillet weld are disclosed. The purpose is to provide.

[0006]

In order to achieve the above object, an inspection method according to the present invention projects a light beam on a weld portion and its vicinity, detects a change in the amount of reflected light, and adjusts the height of the weld boundary. It is characterized in that the penetration depth is estimated from the relationship between the welding boundary height and the penetration depth, which are measured and the target position is changed in advance.

Further, the inspection apparatus of the present invention includes means for projecting a light beam at a weld portion and its vicinity, and means for detecting a change in the amount of reflected light of the light beam. Is measured, and the penetration depth is estimated from the relationship between the welding boundary height and the penetration depth measured by changing the target position in advance.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 3, a stainless steel standing plate 3 is fillet-welded to a stainless steel lower plate 2.

A spot beam 4 perpendicular to the standing plate 3 is radiated in a spot form from an irradiator 5, and the irradiator 5 receives a reflected beam. The change in the amount of reflected light may be sensed by a voltage or a difference in brightness (luminance) of an image.

If the irradiator 5 is moved up and down while keeping the distance that the spot light beam 4 hits the standing plate 3 substantially constant, the reflected light beam becomes maximum when the weld is completely separated, and conversely, the spot is The minimum is obtained when all of them enter the weld.

FIG. 4 shows the ideal position at the time of welding. Point E represents the height of the fusion boundary, H represents the fusion height, and I represents the penetration depth. in this way,
In the present invention, the penetration depth means a penetration depth in a direction showing substantial joint strength.

FIG. 5 shows a state in which the target position is shifted downward by 0.5 mm (-0.5 mm) from the ideal target position, and FIG. 6 is shifted by 0.5 mm upward (+0.5 m).
m) Indicates the state.

As described above, the height E of the melting boundary can be known by moving the irradiator 5 up and down and measuring the change in the intensity of the reflected light beam.

The correlation between the melting height H and the penetration depth I is based on the output of the light beam (laser), the focal length, and the target position.
It is considered to be the main parameter. If the correlation between the melting height H and the penetration depth I is made with the output of the light beam and the focal length constant and the target position changed at the same target angle, the penetration depth I is estimated by comparison with this. can do.

In addition to the above, if the penetration depth I is estimated for each plate thickness from the relationship between the molten height H and the penetration depth I created for each set of the thicknesses of the lower plate 2 and the standing plate 3 , The penetration depth I can be estimated more accurately.

The method of the present invention can be applied when a weld is formed by laser welding and electron beam welding. However, particularly in the case of laser welding, the above correlation is remarkable, so that it is particularly preferable to apply the present invention to a welded portion by laser welding.

The light beam used in the present invention is not particularly limited, but usually a laser (wavelength 670 nm) used for a laser displacement meter or the like is used. The light beam is preferably applied to the standing plate 3 as a spot light beam at right angles. Standing board 3
This is because, when the vertical light is applied, the reference reflected light amount becomes clear and the melting height H is easily determined.

The distance between the standing plate 3 and the irradiator 5 is substantially constant,
The irradiator 5 is preferably moved up and down while traveling in the length direction of the bead. The stainless steel may be moved in the length direction without running the irradiator 5.

When the standing plate 3 is curved and the welding line between the standing plate 3 and the lower plate 2 is curved in the same manner, the curvature substantially matches the curvature (the distance from the standing plate is almost constant). It is preferable that the irradiator 5 travels in the length direction along such a locus.

Further, a plurality of irradiators 5 may be arranged in the vertical direction and / or the length direction so that the irradiators 5 are not moved. Further, the spot beam may be moved in an arc without moving the irradiator 5 up and down.

FIG. 7 shows a method for measuring the melt height H using a laser displacement sensor. When a laser displacement sensor is used, the laser displacement meter can measure the distance from the sensor to the standing plate 3 minutely.

The displacement sensor is brought into contact with the upright plate 3 and the state A is changed to B.
In this case, for example, an output of 1 V can be obtained by changing the distance by 1 mm by passing through an amplifier, for example.

Now, when the displacement sensor is brought into contact with the standing plate 3 to lower from the state A where the reference output is obtained to the state B,
A minute distance change can be read from the output difference compared with the reference output. This seems to read the difference in the distance between A and B at first glance, but it also includes the angle difference between the reflection surfaces. That is, a minute step at the fusion height boundary can be determined.

FIG. 8 shows a method for measuring the melt height H using a CCD camera. In order to stabilize the image on the CCD camera, laser light is used as projection light.

The welded portion is imaged by a CCD camera, and image processing such as binarization is performed to determine the fusion boundary height H. The melt boundary height H can be determined based on the brightness difference of the image, that is, the degree of black and white.

In the case where the welding heat input is small and a slight change in the heat input position affects the result, for example, in the case of laser welding of a thin plate, as shown in FIG. 9, 1 mm is shifted from the ideal target position a to the target position b. Necessary parts may not melt even if they are changed.

However, even in the above case, the surface side c
As shown in FIG. 10, it has been confirmed by an experiment that the difference between the target positions a and b clearly appears in the result, even when the difference with the naked eye is not clear, as shown in FIG.

The present invention detects a difference between target positions at the time of welding. However, a detector capable of detecting such a difference between target positions has not been known at all, and such an idea has not been known at all. Not been.

According to the present invention, a fillet weld to be measured is obtained by fixing a target angle and determining a relationship between a target position at the time of welding and an ideal state and a penetration depth I for a standard sample. The penetration depth I can be estimated from the melting height H of the portion.

In addition, in addition to the above, the relationship between the melting height H and the penetration depth I is obtained for a standard sample for each sheet thickness.
Can be estimated with higher accuracy.

The detector according to the present invention can be used as an automatic inspection device by providing a threshold value. In this way, since the actual work can be continuously inspected nondestructively, the inspection cost can be reduced.

[0032]

According to the present invention, it has been possible to solve the previously unsolved problem that the penetration depth of a stainless steel fillet weld can be estimated nondestructively with respect to the actual material. This is a periodical invention.

[0033]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a conventional destructive inspection.

FIG. 2 is a diagram showing a cut surface cut by a conventional destructive inspection.

FIG. 3 is a schematic side view showing the device of the present invention.

FIG. 4 is a diagram showing an ideal state of a target position during welding.

FIG. 5 is a diagram showing a state shifted from a target position at the time of welding by 0.5 mm downward.

FIG. 6 is a diagram showing a state shifted from a target position at the time of welding by 0.5 mm upward.

FIG. 7 is a schematic diagram showing a method for measuring a melt height using a laser displacement sensor.

FIG. 8 is a schematic diagram showing a method for measuring a melt height using a CCD camera.

FIG. 9 is a side view showing a state shifted from an ideal target position a to a target position b.

FIG. 10 is a front view of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Weld part (weld bead) 2 Lower plate 3 Standing plate 6 Target position

──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁶ Identification code FI G01N 21/88 G01N 21/88 A (72) Inventor Takanori Igarashi

Claims (10)

[Claims] 1. A light beam is projected onto a weld and its vicinity, a change in the amount of reflected light is detected, the height of the weld boundary is measured, and the difference between the weld boundary height and the penetration depth measured by changing the target position in advance is measured. A method for inspecting fillet welds of stainless steel, comprising estimating the penetration depth from the relationship. 2. The inspection method according to claim 1, wherein the welding portion is formed by laser welding. 3. The inspection method according to claim 1, wherein the light beam is projected in a length direction and a vertical direction of the welded portion. 4. The light beam according to claim 1, wherein a distance between the light beam and a standing plate welded to the lower plate is substantially constant, and the light beam is projected perpendicularly to the standing plate as a spot light beam. Inspection method. 5. The inspection method according to claim 1, wherein the change in the amount of reflected light is detected as a change in voltage or brightness of an image. 6. A means for projecting a light beam on a welded portion and its vicinity, and a means for detecting a change in the amount of reflected light of the light beam. An inspection apparatus for a stainless steel fillet weld, wherein the penetration depth is estimated from the relationship between the welding boundary height and the penetration depth measured by changing the welding depth. 7. A laser displacement meter using a laser displacement sensor, wherein the means for detecting a change in the amount of reflected light is provided.
The inspection device according to item 1. 8. An inspection apparatus according to claim 7, wherein said means for detecting a change in the amount of reflected light is a CCD camera for detecting a change in brightness of an image. 9. The inspection apparatus according to claim 6, further comprising: means for moving the means for projecting the light beam in a vertical direction and / or a length direction of the welded portion. 10. The means for moving in the length direction, when the welding line is curved in the length direction, moves in the length direction along a locus substantially matching the curvature of the welding line. The inspection device according to claim 9.