JP3495212B2 - Seam detection device for ERW pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a seam portion detecting device for an electric resistance welded pipe for detecting a position of a seam portion after cutting a weld bead of the electric resistance welded pipe.

[0002]

2. Description of the Related Art Conventionally, in order to inspect the welding accuracy of an electric resistance welded pipe, ultrasonic flaw detection inspection is performed on the seam portion of the electric resistance welded pipe after cutting the welding bead. In this flaw inspection process, the work of following the seam portion of the ultrasonic flaw detector is visually performed by the operator, but automatic detection and copying technology of the seam portion are indispensable for reducing the work load and saving labor. .

Therefore, as means for accurately detecting the position of the seam portion of the electric resistance welded pipe, for example, Japanese Patent Laid-Open No. 62-1357.
The one described in Japanese Patent Publication No. 04 has been proposed.

[0004] In this publication, by irradiating a laser over light under specific conditions on the surface of the electric-resistance-welded pipe, by capturing the characteristics of the reflection pattern from the irradiation portion surface of the light, a technique for detecting the position of the seam portion It is shown.

[0005]

However, when the above-mentioned conventional technique is applied and a commercially available light-emitting body (halogen lamp or the like) or light-receiving body (photodiode or the like) is used instead of the expensive laser, Due to the output characteristics, the emission wavelength covers a wide range, and the photodetector detects all of the emitted wavelength, so defects other than the seam,
There was a problem that the accuracy of detection was poor, such as false detection of a portion where the reflected light was weaker than the reflection of the normal steel plate material surface as a seam portion due to extrusion marks during pipe forming, or that the seam portion was not detected. .

That is, the seam portion of the pipe is subjected to high heat during welding or subsequent bead grinding, and is discolored black, brown or blue due to the oxide film generated by the heat. For this reason, the reflectance is usually lower than that of the other parts of the pipe (color of the steel plate of the material). But,
In addition to the seam part, the reflection direction changes due to extrusion marks during pipe molding, etc. As a result, there is a part where the reflected light is weakly detected on the photoreceptor surface, and the difference in reflectance between the two is very subtle. Many. In particular, the longer the wavelength of light, the smaller the difference in reflectance between the seam portion and the extrusion flaw due to the light diffraction phenomenon.

FIG. 3 shows a light receiving wavelength and a light receiving amount (a light receiving amount) when a commercially available halogen lamp is used as a light emitting body and all reflected light of this light emission is received by a light receiving body (photodiode) in an irradiation experiment on an electric resistance welded pipe. == reflectance of irradiation light).

From these results, it was found that when the wavelength is 1000 nm or more, the difference in reflectance between the portion where the reflected light is weak due to the above flaws and the seam portion becomes slight, and when the wavelength is 1500 nm or more, the reflectances almost match.

However, 1000 nm, especially 800 n
It was found that when m or less, the difference in reflectance between the portion where the reflected light was weak and the seam portion was large.

In other words, it has been found that even with a commercially available luminescent material, it is possible to distinguish between a seam portion and a flaw or the like where reflected light is weak by selecting the wavelength.

The present invention has been made based on this finding.

Further, in most commercially available reflection type optical sensors, even if the threshold value is fixed or variable for detection, the threshold value is set by a trimmer before measurement. Not adjustable.

Further, since the conventional apparatus using a record over Heather light, the structure is complicated, costly, there is a problem of poor durability. The same applies when the seam portion is detected by ultrasonic waves or electromagnetic force.

The problem to be solved by the present invention is to provide a seam portion detecting device for an electric resistance welded pipe for detecting the position of the seam portion after cutting the weld bead of the electric resistance welded pipe, and the reflected light from the seam portion and other portions. It is an object of the present invention to provide a seam portion detecting device for an electric resistance welded pipe, which is capable of accurately determining the difference between the two and detecting the position of the seam portion with high accuracy, and is inexpensive and excellent in durability.

[0015]

(Means for Solving the Problem) (Means for Solving the Problem) The means for solving the above problem (claim 1) is to irradiate the surface of an electric resistance welded pipe, and a light-emitting body having a wavelength of at least 300 nm to 800 nm; Of the light from the light-emitting body reflected on the surface of the tube, a filter that transmits only light having a wavelength of 800 nm or less, a light-receiving body that receives the light that has passed through the filter, and an electric resistance welded tube that is received by the light-receiving body A seam position detecting device for an electric resistance welded pipe , comprising: seam position detecting means for detecting the position of the seam part of the electric resistance welded pipe based on reflected light.
Of the light from the luminous body is scattered and reflected on the surface of the electric resistance welded pipe.
The light emitter and the light receiver so that the incident light enters the light receiver.
In addition, the light reflectance is high so that specularly reflected light enters the photoreceptor.
It is characterized in that a light reflection plate or another light source is arranged .

The operation will be described.

On the surface of the electric resistance welded pipe which is rotated to detect the seam portion of the electric resistance welded pipe, at least three light emitting elements are provided.
Light having a wavelength of 00 nm to 800 nm is irradiated, the irradiated light is reflected on the surface of the electric resistance welded pipe, and the reflected light is passed through a filter that transmits only light having a wavelength of 800 nm or less and is received by a light receiver. Received light.

Looking at the reflectance of the light received by this light receiver, the reflected light to be detected becomes weak due to a change in the reflection direction due to a flaw, an extrusion mark, or the like, and the irradiation light is absorbed due to the seam portion. the reflected light becomes weak portion for detecting, the detected value is different, the former will be detected high reflectance after
Persons with low reflectance are detected. In other words, for light with a wavelength narrowed to this range, the exact mechanism is unknown,
The amount of reflected light decreases depending on the detection wavelength, and the amount of reflected light decreases due to the scattering of some light and the amount of reflected light decreases due to the absorption of some light. Is considered. As a result, large absorption is observed at the seam portion at the above wavelength.

Of the light from the luminous body, an electric resistance welded tube
So that the light scattered and reflected by the surface of the
Along with arranging the photoreceptor, the specularly reflected light also enters the photoreceptor.
A light reflector with a high light reflectance or another light source.
Therefore, observe the light scattered and specularly reflected by the electric resistance welded tube.
Therefore, the seam position detection means depends on flaws, extrusion marks, etc.
Highly accurate seam position without being affected by false positives
Position detection can be performed.

(Solution Means 2) A means for solving the above problems (claim 2) is the seam portion detecting device for an electric resistance welded pipe according to claim 1, wherein the luminous body is at least 300 nm to 800 nm at a wavelength of 1000 nm or less.
Is characterized by having a flat output characteristic.

The operation is as follows.
Since there is no wavelength exceeding 0 nm, there is no heating and the position of the seam can be detected with extremely high accuracy without using a filter.

(Solution means 3) The means for solving the above-mentioned problems (claim 3) is the seam portion detecting device for an electric resistance welded pipe according to claim 1 or 2, wherein light is emitted before the light emitting portion of the light emitter. A feature is that a lens that collects light from the body is provided.

The operation will be described. The light from the light emitting body is condensed by the lens and is applied to the surface of the electric resistance welded tube.

Therefore, when light is reflected on the surface of the electric resistance welded pipe having a low reflectance, the reflection sensitivity is increased, which is effective in stabilizing the position detection accuracy of the seam portion with high accuracy. .

(Solution means 4) A means for solving the above-mentioned problems (claim 4) is the seam portion detecting device for an electric resistance welded pipe according to any one of claims 1 to 3, wherein the seam position detection means is for an electric resistance welded pipe. An amplifier that amplifies the signal from the photoreceptor that senses the reflected light on the surface and the amplified signal are input, the electric resistance tube is rotated, and the point with the smallest reflected light amount is detected during the first rotation. It is characterized by having a first signal processing unit which waits for a point of an amount of reflected light which is the same as or less than a threshold value after the rotation to come and judges this point as a seam portion.

(Solution means 5) A means for solving the above-mentioned problems (claim 5) is the seam portion detecting device for an electric resistance welded pipe according to any one of claims 1 to 3, wherein the seam position detection means is for an electric resistance welded pipe. An amplifier that amplifies the signal from the photoreceptor that senses the reflected light on the surface and the amplified signal are input, the electric resistance tube is rotated, and the point with the smallest reflected light amount is detected during the first rotation. Approximately equal to or less than the threshold value of the minimum reflected light amount of the first one rotation within a predetermined time permissible range around the point where the time required for one rotation of the pipe has passed from the point of the smallest reflected light amount at the rotation Wait for the point of light intensity to come and judge this point as the seam part
And a signal processing unit.

(Means for Solving 6) The means for solving the above-mentioned problems (claim 6) is the seam portion detecting device for an electric resistance welded pipe according to claim 4 or 5, wherein each of the signal processing portions has one of the reflected light amounts. When it is detected that there are multiple reflected light intensity drop peaks when detecting the fewest points, a signal to be processed as one peak if multiple peaks are present within a fixed period of time determined by considering the width of the seam portion. It is a processing unit.

(Solution Means 7) Means for solving the above problems (Claim 7) are defined by Claims 1 to 3.
In the seam portion detecting device for electric resistance welded pipe according to claim 6,
Adjust the light-receiving field other than the seam to the position just before the photoreceptor.
A visual field adjustment slit is provided .

[0029] (SOLUTION 8) above problem solving means (claim 8), according to claim 4 or請
In the seam detection device for electric resistance welded pipe according to claim 7,
Bandpass filter on the sensor body
And a condenser lens unit, a field-of-view adjusting slit, and a light receiving element
As a reflected light amount sensor unit with an integrated amplifier
Characterized in that was.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described.

First, the structure will be described.

FIG. 1 is an overall view showing a seam portion detecting device for an electric resistance welded pipe according to a first embodiment of the present invention.

In FIG. 1, 1 is an electric resistance welded stainless steel pipe (electric resistance welded pipe), 2 is a light emitter, 3 is a lens, 4 is a low pass filter (filter), 5 is a light receiver, 6 is an amplifier (seam position detecting means). , 7 are signal processing circuits (seam position detecting means).

The electric resistance welded stainless steel pipe 1 is formed with a seam portion 1a after cutting the weld bead on the peripheral surface thereof, and when the seam portion is detected, it is slowly rotated by a rotation drive device (not shown).

The luminous body 2 has a wavelength of at least 300 n.
A light emitter having an output characteristic of m to 800 nm is used. That is, a lamp that emits visible light (400 nm to 800 nm) can be widely used, and an incandescent lamp, a mercury lamp, a sodium lamp, or the like can be used as a commercially available light emitter, but a halogen having particularly good durability is available. Lamps are preferred. Further, near-ultraviolet light having a wavelength of 300 nm to 400 nm and near-infrared light having a wavelength of 800 nm to 1000 nm can also be used, but the reflectance is low for ultraviolet light having a wavelength of 300 nm or less, and as described above for the infrared light having a wavelength of 1000 nm or more, as a seam portion. It cannot be used because the difference in parts due to flaws cannot be detected.

The lens 3 is provided in front of the light emitting portion of the light emitting body 2, and the light from the light emitting body 2 is electrically welded to the stainless steel pipe 1.
Focus towards the surface of.

The low-pass filter 4 has a wavelength of 80 out of the reflected light reflected from the surface of the electric resistance welded stainless steel pipe 1.
It is a filter that transmits only light of 0 nm or less.

The photodetector 5 receives the light transmitted through the low-pass filter 4 and converts the received light into electricity. As the light receiver 5, a light receiving element such as a photodiode or a phototransistor that receives light having a wavelength of about 1000 nm or less without unevenness is used.

The amplifier 6 amplifies a minute voltage (or minute current) generated according to the amount of light received by the light receiver 5 to a level at which signal processing can be performed. The signal processing circuit 7 has a comparator for comparing the detection signal input from the amplifier 6 with a signal corresponding to a preset seam judgment reflectance threshold value, and is input to this comparator. When the detection signal is below the threshold signal, the surface position of the electric resistance welded stainless steel pipe 1 which is irradiating light at that time is the seam portion 1
It outputs a signal that it is a.

Then, the amplifier 6 and the signal processing circuit 7
And constitute a seam position detecting means.

Next, the operation will be described.

In order to detect the seam portion of the electric resistance welded stainless steel pipe 1, first, the electric resistance welded stainless steel pipe 1 is rotated.

On the surface of the rotating electric resistance welded stainless steel pipe 1, at least a wavelength of 300 nm to 8 is emitted from the light emitting body 2.
Light having an output characteristic of 00 nm is condensed by the lens 3 and is irradiated, and this irradiated light is reflected on the surface of the electric resistance welded stainless steel pipe 1, and this reflected light transmits only light having a wavelength of 800 nm or less. The light is received by the light receiver 5 through the low-pass filter 4.

Here, the above-mentioned irradiation experiment for the electric resistance welded tube using the halogen lamp as a luminous body by the present inventor will be described in more detail. FIG. 3 is a graph showing the results, showing the reflectance characteristics with respect to wavelength.

As is clear from this measurement result, the wavelength 1
In the case of light of 000 nm or more, the reflectance (50%) is almost the same whether it is a flaw, an extrusion mark, or a seam.
% To 60%) and there is almost no difference from the reflectance with the steel plate material portion. However, when looking at the reflectance by focusing on light with a wavelength of 800 nm or less, the reflectance at the position of a flaw or an extrusion mark is high (around 40%) and the reflectance at the position of the seam portion is low (around 30%). It was found that a larger light absorption was observed at the seam portion than at the position such as a flaw or an extrusion mark.

Therefore, as described above, light having a wavelength of 800 nm or less is selected, and a minute voltage or a minute current generated according to the amount of light received by the photodetector 5 is amplified by the amplifier 6 to a level at which signal processing can be performed, and signal processing is performed. In the circuit 7, the detection signal input from the amplifier 6 is compared with a signal corresponding to a preset seam judgment reflectance threshold value (value between both reflectances, for example, 35%), When the input detection signal is less than or equal to the threshold signal, a signal indicating that the surface position of the electric resistance welded stainless steel pipe 1 which is irradiating light at that time is the seam portion 1a is output.
By utilizing the characteristics of light having a wavelength of 00 nm or less, preferably 300 nm to 800 nm, it is possible to detect the position of the seam portion 1a with extremely high accuracy without being affected by flaws, extrusion marks, and the like.

Further, the light from the light emitting body 2 is condensed by the lens 3 and is irradiated onto the surface of the electric resistance welded stainless steel pipe 1, so that the light is emitted on the surface of the electric resistance welded stainless steel pipe 1 having a low reflectance. In the case of the reflection, the reflection sensitivity can be increased even when a commercially available light emitting element is used as the light emitting body 2, and it is effective in stabilizing the position detection accuracy of the seam portion 1a with high accuracy.

Of course, this seam portion detecting device is disclosed in
As described in Japanese Patent Application Laid-Open No. 2-135704, the seam portion 1 with high accuracy is adopted by adopting the ultrasonic flaw detection device.
It is possible to achieve complete automation of ultrasonic flaw detection by detecting the position of a.

Next, the effect will be described.

(1) Of the light from the light-emitting body 2 that irradiates the surface of the electric resistance welded stainless steel pipe 1 and has an output characteristic of at least a wavelength of 300 nm to 800 nm, and the light from the light emitter 2 reflected by the surface of the electric resistance welded stainless steel pipe 1. A low-pass filter 4 that transmits only light having a wavelength of 800 nm or less, a light-receiving body 5 that receives the light that has passed through the low-pass filter 4 and that converts the received light into electricity, and an electric resistance stainless steel pipe that receives the light by the light-receiving body 5. An amplifier 6 that amplifies a voltage generated as a detection signal based on the reflected light from 1 and an amplified detection signal are compared with a seam portion determination reflectance threshold value to determine whether or not it is a seam portion, Since the signal processing circuit 7 for detecting the position of the seam portion 1a of the electric resistance welded stainless steel pipe 1 is provided, reflections other than the seam portion 1a (for flaws and pipe molding) It is possible to detect the position of the seam 1a with high accuracy without being affected by (extrusion traces, etc.), and is cheaper and more durable than other methods (laser, ultrasonic wave, electromagnetic type, etc.). A seam detection device for a sewing pipe can be provided.

(2) In front of the light emitting portion of the light emitting body 2, the light emitting body 2
Since the lens 3 that collects the light from the
The position detection accuracy of a can be stabilized with high accuracy. It should be noted that, instead of the light emitting body 2, as shown in FIG.
It is preferable that the light emitting body 2 has a flat output characteristic between 0 and 800 nm.

In this case, since the wavelength is about 1000 nm or less and near infrared light or less and does not include infrared light, heating of the device is prevented as much as possible.

Further, at 1000 nm or less, 300 to 80
Since the output characteristic is flat between 0 nm, no filter is required and the position of the seam portion can be detected with high detection accuracy. That is, the fact that there is no variation between the irradiation wavelengths means that the reflected light is leveled even if the seam portion has a characteristic of selectively selectively absorbing light of a certain wavelength. The position of the seam portion can be detected without error in combination with the characteristic that the light is easily absorbed.

The second embodiment of the present invention will be described below. (Second Embodiment) As shown in FIG. 4, a seam portion detecting device for an electric resistance welded pipe according to a second embodiment uses a CCD camera 8 as a light receiving body and a CCD
The image signal from the camera 8 is processed by the image processing circuit 9 (seam position detecting means), and the image and the reflected light of the seam portion 1a are reflected by light other than the seam portion 1a (such as a flaw or an extrusion mark at the time of pipe molding). The image is discriminated and judged, and the result is output as an output signal.

Here, the CCD camera 8 is a television camera whose photosensitive target surface is formed by a CCD array (charge coupled device array). When this CCD camera 8 is used, , Minority carriers (surface charge) of electron-hole pairs generated according to the intensity of reflected light are accumulated in the potential well of the CCD electrode, and the accumulated charge is stored in the non-photosensitive portion of CCD. It is transferred, further transferred to an output device, and converted into a video signal.

In the case of the second embodiment, although the device cost is increased to some extent, only the light having a wavelength of 800 nm or less in the reflected light is imaged by the CCD camera 8 and analyzed. Therefore, higher position detection accuracy of the seam portion 1a can be obtained as compared with the first embodiment.

In the second embodiment, the CCD camera 8 is used as the image detecting device, but a solid-state camera using an image sensor other than the CCD may be used.

The third embodiment of the present invention will be described below. Embodiment 3 In Embodiment 3, as shown in FIG. 5, the illumination unit 10 is used on the light emitting side and the reflected light amount sensor unit 11 is used on the light receiving side.
Signal processing circuit 1 in the reflected light amount sensor unit 11 using
2 is an example of a seam detection device for an electric resistance welded pipe to which 2 is connected. Here, the lighting unit 10 includes a light emitting body 2 and a lens 3.
And are integrated .

FIG. 5 shows a seam detection device of the type that observes with scattered reflected light, and illuminates the light from the illumination unit 10 scattered and reflected on the surface of the electric resistance welded stainless steel pipe 1 into the reflected light amount sensor unit 11. A unit 10 and a reflected light amount sensor unit 11 are arranged.

FIG. 6 shows a seam detection device of the type that observes with specular reflection light. Illumination is performed so that the light from the illumination unit 10 specularly reflected on the surface of the electric resistance welded stainless steel pipe 1 enters the reflected light amount sensor unit 11. A unit 10 and a reflected light amount sensor unit 11 are arranged.

FIG. 7 shows a seam detection device of a system for observing scattered reflected light and specular reflected light. Light from the illumination unit 10 scattered and reflected on the surface of the electric resistance welded stainless steel pipe 1 is reflected by the reflected light amount sensor unit 11. Lighting unit 10 to enter
And the reflected light amount sensor unit 11 are arranged,
A light reflection plate 13 (white paper, enamel plate, etc.) having a high light reflectance is arranged so that the light from the illumination unit 10 enters the reflected light amount sensor unit 11 as regular reflection light. still,
Instead of the light reflection plate 13, a light source different from the illumination unit 10 may be arranged.

FIG. 8 is a sectional view showing the reflected light amount sensor unit 11. The reflected light amount sensor unit 11 is a bandpass filter 11 arranged at the tip of the sensor body 11a.
b (filter) and a condenser lens unit 11c with a diaphragm function, which is arranged at the rear of the bandpass filter 11b.
And the visual field adjusting slit device 11d and the light receiving element 11e which are arranged close to each other on the rear part of the condenser lens unit 11c.
This is a unit in which the (light receiving body) and the amplifier 11f arranged at the rear of the light receiving element 11e are integrally provided. As the bandpass filter 11b, a filter that transmits only light of a specific wavelength of 800 nm or less, for example, light of 800 nm is used.

The visual field adjusting slit device 11d is arranged immediately in front of the light receiving element 11e and adjusts the light receiving visual field other than the seam portion 1a. That is, when the field-of-view adjusting slit device 11d is not provided, as shown in FIG. 9A, the round light-receiving field of the light-receiving element 11e includes a large area other than the seam portion 1a. Although the light receiving element 11e receives the noise in the above, when the visual field adjusting slit device 11d is provided, as shown in FIG.
Noise can be masked by largely covering the portion other than the seam portion 1a in the round light-receiving visual field of the light-receiving element 11e and adjusting only the visual-field adjustment slit so that light is transmitted.

The amplifier 11f amplifies the voltage signal from the light receiving element 11e which senses the reflected light, and the signal processing circuit 1
Send to 2.

Next, the signal processing circuit 12 will be described.

The signal processing circuit 12 is a circuit for inputting a sensor voltage corresponding to the amount of reflected light amplified from the amplifier 11f and detecting the position of the seam portion 1a of the electric resistance welded stainless steel pipe 1, and in the seam portion 1a. It is determined that there is any of the signal processing methods listed below.

(1) Rotate the electric resistance welded stainless steel pipe 1 and detect the point with the smallest amount of reflected light during the first revolution, and
After the rotation, wait for a point of the same or the reflected light quantity equal to or less than the threshold value to come, and fix this point to the seam portion 1a.
To judge.

(2) Rotate the electric resistance welded stainless steel pipe 1 and detect the point with the smallest amount of reflected light during the first revolution, and
Approximately equal to or less than the threshold value of the minimum reflected light amount of the first one rotation within a predetermined time permissible range around the point where the time required for one rotation of the pipe has passed from the point of the smallest reflected light amount at the rotation Waiting until the point of the specified light amount comes, this point is judged as the seam portion 1a.

When the signal processing circuit 12 detects that there are a plurality of reflected light amount drop peaks in detecting the point where the reflected light amount is the smallest, the plurality of peaks are determined in consideration of the width of the seam portion 1a. If it exists within a certain time Δt (see FIG. 11), it is processed as one peak.

Next, the operation will be described.

(Method of Observing with Scattered Light) As for the arrangement of the illumination unit 10 and the reflected light amount sensor unit 11, both of them are integrated in a normal reflection type sensor and the scattered reflected light has a more stable light amount. For the reason of being obtained or the like, as shown in FIG. 5, the scattered light is usually arranged so as to enter the reflected light amount sensor unit 11.

Now, description will be made of the seam portion 1a and the above-mentioned flaws such as the above-mentioned flaws which are mistakenly recognized as the seam portion 1a .

Defects such as flaws include extrusion flaws at the time of molding, friction flaws between the jig of the pipe molding machine and the conveying device and the steel plate of the pipe material, etc. Some of the flaws have different states and are easily misidentified by the detection device, while others are not worried.

That is, since these flaws are caused by friction between metals, a glossy portion whose surface is mirror-finished (hereinafter referred to as a mirror glossy portion), depending on the cause of occurrence.
A glossy portion (hereinafter referred to as a scattering glossy portion) in which scattered reflection is large due to fine scratches occurs.

In the detection device of the present invention, the seam portion 1a can be detected separately from all of these flaws.

In the case of observing with scattered light, if the specular glossy portion is present, most of the illuminating light from the illuminating unit 10 is specularly reflected on the pipe surface, and if observing with scattered reflected light, the reflectance is lowered. Therefore, the reflected light amount sensor unit 11 may erroneously determine the specular gloss portion as the seam portion 1a whose reflectance is reduced due to absorption of light.

Incidentally, FIG. 10 shows a change in the reflected light amount (sensor voltage) detected by the reflected light amount sensor unit 11 when the electric resistance welded stainless steel pipe 1 is rotated once in the sensor arrangement for observing scattered reflected light (FIG. 5). It is a characteristic diagram.

The waveforms of the portions A and G on the time axis in FIG.
This is the reflection from the steel plate of the pipe material. The waveforms of the portions B and F on the time axis are the above-mentioned scattering glossy portions, where the amount of reflected light is increased by the reflected light.

Therefore, it is possible to easily distinguish the defective portion which exhibits the scattering gloss portion and the seam portion 1a. In FIG. 10, the waveform of the portion D on the time axis is a portion where reflection is small due to the seam portion 1a.

In FIG. 10, the waveforms of C and E on the time axis are
Since the specular glossy portion is continuously formed in the vertical direction, the irradiation light is almost regularly reflected, and as a result, the scattered reflection light is reduced and the light amount is reduced.

With the characteristics shown in FIG. 10, in addition to D which is the seam portion 1a, the amount of scattered reflected light is small in the portions C and E,
If the amount of light at the C or E portion is further reduced, or conversely, the reflection at the D portion is slightly stronger, the specular glossy portion corresponding to the C or E and the seam portion 1a may not be distinguished.

However, in the present embodiment, 800
Since a bandpass filter that transmits light of wavelength nm is used, as described above, the light of wavelength 800 nm can be detected by relatively distinguishing the amount of light attenuated by absorption and the amount of light attenuated by scattering. In the case of the change characteristic shown in FIG. 10, if the seam portion judgment threshold value is S1, the seam portion 1a can be judged.

However, if the seam portion judgment threshold value is S2, there is a possibility that the portion E other than D may be erroneously detected as the seam portion 1a.

Therefore, the seam portion 1a of the scattered-reflected light can be easily distinguished by selecting the wavelength of the detection light as described above, but the seam portion 1a of the electric resistance welded stainless steel pipe 1 is detected. It will be limited to when the reflectance of is significantly lower than other parts.

(Method of Observing with Specular Reflected Light or Scattered Reflected Light and Specular Reflected Light) In order to solve the problem of the method of observing with the scattered reflected light, it is necessary to prevent the amount of scattered reflected light from decreasing in the specular gloss portion. It is necessary to devise the arrangement of the illumination unit 10 and the reflected light amount sensor unit 11 so that the specularly reflected light also enters the reflected light amount sensor unit 11.

As shown in FIG. 6, one of the methods is to arrange the pipe surface so that the incident angle from the illumination unit 10 is equal to the incident angle to the reflected light amount sensor unit 11.

As another method, as shown in FIG. 7, the arrangement of the illumination unit 10 and the reflected light amount sensor unit 11 is the same as that shown in FIG. Incident angle and reflected light amount sensor unit 11
This is a method of additionally arranging the reflection plate 13 so that the incident angle to the light is equal.

By the way, FIG. 11 shows the amount of reflected light detected by the sensor unit 11 when the electric resistance welded stainless pipe 1 is rotated once in the sensor arrangement for observing scattered reflected light + regular reflected light (FIG. 7). It is a change characteristic view of (voltage).

Comparing the change characteristics of FIG. 11 with the change characteristics of FIG. 10, in the case of FIG. 11, there is no drop in the amount of light at the specular glossy portions C and E, and the seam portion judgment threshold value is eliminated. When S is S, only the D portion has a greater degree of drop in the reflected light amount than the other portions. That is,
In the case of this method, the specularly reflected light is added to the scattered and reflected light in the C and E portions, so that the reflected light amount is extremely increased, whereas in the D portion, the reflected light amount further attenuated to a small reflected light amount. Since it is only added, the difference in the amount of reflected light between the two increases, and the seam portion 1a can be accurately detected even if the electric-resistance-welded stainless steel pipe 1 has a specular gloss portion.

Therefore, this method is effective for detecting the seam portion of the electric resistance welded tube having the specular gloss portion.

[0091]

According to the invention of claim 1, an electric resistance welded pipe
The surface of at least 300 nm to 800 nm
Before emitting light with wavelength and reflecting on the surface of the electric resistance welded tube
Of the light from the phosphor, only light with a wavelength of 800 nm or less
Filter that passes through and receives light that passes through the filter
From the ERW pipe received by the photoreceptor and the photoreceptor
A system that detects the position of the seam of the electric resistance welded pipe based on the reflected light.
And a seam portion detecting device of an electric resistance welded pipe including a seam position detecting means.
The surface of the electric resistance welded tube out of the light emitted from the luminous body.
The light emitter and the light receiver are arranged so that the scattered and reflected light enters the light receiver.
Is placed, and the specular reflection light is reflected so that it enters the photoreceptor.
A structure with a high-reflectance light reflector or another light source
Therefore, it is possible to accurately determine the difference in reflection between the seam portion and other portions, detect the position of the seam portion with high accuracy, and provide a seam portion detection device for an electric resistance welded pipe that is inexpensive and has excellent durability. can do.

According to the invention of claim 2, claim 1
In the seam detection device for the electric resistance welded pipe described above, the illuminator is
Since the device has a flat output characteristic of about 1000 nm or less and at least between 300 and 800 nm, the device is not heated as much as possible, and the seam portion can be detected with extremely high accuracy without using a filter.

According to the invention of claim 3, claim 1
Alternatively, in the seam detection device for an electric resistance welded pipe according to claim 2, since a lens for condensing light from the light emitter is provided in front of the light emitter of the light emitter, the position detection accuracy of the seam can be stabilized with high accuracy. It is possible to achieve the effect of the invention according to claim 1 or claim 2 while making it possible.

In the inventions according to claims 4 and 5, in the seam portion detecting device for an electric resistance welded pipe according to any one of claims 1 to 3, the signal from the photoreceptor is amplified when the seam portion is detected. Input the amplified signal, rotate the electric resistance welded pipe, detect the point with the smallest amount of reflected light during the first rotation, and determine the seam portion by the signal check processing after the second rotation. Since the configuration is provided, an effect that the position of the seam portion can be detected with high accuracy is obtained as compared with the case where the point having the smallest amount of reflected light during one rotation is directly determined as the seam portion.

According to the invention of claim 6, claim 4 is provided.
In the seam detection device for electric resistance welded pipe according to claim 5, each signal processing unit detects a plurality of peaks of the reflected light amount when it detects that a plurality of reflected light amount dip peaks exist. Is a signal processing unit that processes as one peak if it exists within a fixed time determined by considering the width of the seam portion, so that the seam is highly accurate even when there are multiple peaks in the seam portion area. The effect that the position of the part can be detected is obtained.

According to the invention of claim 7 , claim 1
The seam portion detecting device for an electric resistance welded pipe according to claim 6.
The position of the light-receiving field other than the seam at the position immediately in front of the photoreceptor.
A visual field adjustment slit is provided to adjust noise
A signal that makes it easy to determine the seam position
It can be obtained from the photoreceptor .

According to the invention of claim 8, claim 4 is provided.
The seam portion detecting device for an electric resistance welded pipe according to claim 7.
The sensor body with a bandpass filter.
Filter, condenser lens unit, field of view adjustment slit and receiver
Reflected light quantity sensor unit with integrated optical element and amplifier
Since it is a compact, it is suitable for the applicable production line.
And a highly durable device .

[Brief description of drawings]

FIG. 1 is an overall view showing a seam portion detection device for an electric resistance welded pipe according to a first embodiment of the present invention.

FIG. 2 is an output characteristic diagram of a preferable luminous body used in the seam detection device for electric resistance welded pipe according to the first embodiment of the present invention.

FIG. 3 is a reflectance characteristic diagram in which the reflectance of each seam portion such as a steel plate material portion of an electric resistance welded pipe and an extrusion mark is measured by changing the wavelength.

FIG. 4 is an overall view showing a seam portion detection device for an electric resistance welded pipe according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an arrangement of an illumination unit and a reflected light amount sensor unit in a method of observing with scattered light in a seam detection device for an electric resistance welded pipe according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an arrangement of an illumination unit and a reflected light amount sensor unit in a method of observing with regular reflection light in a seam detection device for electric resistance welded pipes according to a third embodiment of the present invention.

FIG. 7 is a diagram showing an arrangement of an illumination unit, a reflected light amount sensor unit, and a reflector in a method of observing scattered light + regularly reflected light in a seam detection device for an electric resistance welded pipe according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a reflected light amount sensor unit used in the seam portion detection device for electric resistance welded pipe according to the third embodiment of the present invention.

FIG. 9 is a diagram illustrating a noise masking function of the visual field adjustment slit device of the reflected light amount sensor unit.

FIG. 10 is a change characteristic diagram of the reflected light amount (sensor voltage) detected by the reflected light amount sensor unit when the electric resistance stainless steel pipe is rotated once by the arrangement of sensors for observation with scattered light.

FIG. 11 is a change characteristic diagram of the reflected light amount (sensor voltage) detected by the reflected light amount sensor unit when the electric resistance stainless steel pipe is rotated once in a sensor arrangement for observing scattered light + regular reflected light.

[Explanation of symbols]

1 ERW stainless pipe (ERW pipe) 1a seam part 2 luminous body 3 lenses 4 Low-pass filter (filter) 5 Photoreceptor 6 Amplifier (Seam position detection means) 7 Signal processing circuit (seam position detection means) 8 CCD camera (photoreceptor) 9 Image processing circuit (seam position detection means) 10 Lighting unit 11 Reflected light amount sensor unit 12 Signal processing circuit 13 Reflector

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-2-96602 (JP, A) JP-A-2-285204 (JP, A) JP-A-4-340403 (JP, A) JP-A-62-1 42004 (JP, A) JP 59-23203 (JP, A) Actual development 5-50312 (JP, U) Actual development 61-89106 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11/00 B23K 31/00

Claims (8)

(57) [Claims] 1. Irradiating the surface of the electric resistance welded pipe, at least 30
A light-emitting body having a wavelength of 0 nm to 800 nm, a filter that transmits only light having a wavelength of 800 nm or less out of the light from the light-emitting body that is reflected on the surface of the electric resistance welded tube, and a light-receiving device that receives light that has passed through the filter. and body, at the seam portion detecting device ERW tube and a seam position detection means for detecting the position of the seam portion of the electric-resistance-welded pipe based on the reflected light from the electric-resistance-welded pipe which is received by the photoreceptor, wherein Light scattered from the surface of the electric resistance welded tube
If the light emitter and the light receiver are arranged so that the light enters the light receiver,
In both cases, the specularly reflected light is also light with a high light reflectance so that it enters the photoreceptor.
A seam detection device for an electric resistance welded pipe, characterized in that a reflector or another light source is arranged . 2. The seam detection device for an electric resistance welded pipe according to claim 1, wherein the luminous body is at least 300 nm at a thickness of about 1000 nm or less.
A seam portion detection device for an electric resistance welded pipe having a flat output characteristic in the range of up to 800 nm. 3. The seam portion detection device for an electric resistance welded pipe according to claim 1, wherein a lens for condensing light from the light emitting body is provided in front of the light emitting portion of the light emitting body. A seam detection device for ERW pipe. 4. The seam portion detection device for an electric resistance welded pipe according to claim 1, wherein the seam position detection means amplifies a signal from a photodetector that senses reflected light on the surface of the electric resistance welded pipe. Input the amplifier and the amplified signal, rotate the electric resistance welded tube and detect the point with the smallest amount of reflected light during the first revolution, and after the second revolution , the point with the same amount of reflected light, or the defect or flaw. Extrusion trace reflectance
And a first signal processing unit that waits for a point having an approximate amount of reflected light equal to or less than a preset threshold value to come to an intermediate value between the reflectance of the seam portion and the seam portion, and determines this point as the seam portion. A seam detection device for ERW pipe. 5. The seam portion detecting device for an electric resistance welded pipe according to claim 1, wherein the seam position detection means amplifies a signal from a photodetector that senses reflected light on the surface of the electric resistance welded pipe. Input the amplified signal and the amplified signal, rotate the electric resistance welded pipe and detect the point with the smallest amount of reflected light during the first revolution. From the point with the smallest amount of reflected light during the second revolution, rotate the pipe once. A point with the same amount of reflected light as the minimum amount of reflected light in the first rotation , or a flaw or
To an intermediate value between the reflectance of the extruded trace and the reflectance of the seam
A seam portion detecting device for an electric resistance welded pipe, comprising: a second signal processing unit that waits for a point having an approximate light amount equal to or less than a preset threshold value to come and judges this point as a seam portion. 6. The seam portion detecting device for an electric resistance welded pipe according to claim 4 or 5, wherein each of the signal processing units has a plurality of reflected light amount drop peaks when detecting a point having the smallest reflected light amount. Then, when detected, the seam portion of the electric resistance welded pipe is characterized in that it is a signal processing unit that processes a plurality of peaks as one peak if they exist within a fixed time determined in consideration of the width of the seam portion. Detection device. 7. An electric resistance welded pipe according to any one of claims 1 to 6.
In the seam detection device, the light receiving field other than the seam is adjusted in front of the photoreceptor.
A seam detection device for an electric resistance welded pipe, which is provided with a field-of-view adjusting slit that adjusts . 8. The electric resistance welded pipe according to claim 4 or 7.
In the seam detection device, the bandpass filter is installed on the sensor
Filter, condenser lens unit, field-of-view adjustment slit, and light-receiving element
Reflected light amount sensor unit with integrated child and amplifier
A seam portion detecting device electric-resistance-welded pipe, characterized in that the.