JP2012159382A - Method for measuring weld bead cutting width - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring a weld bead cutting width capable of clearly detecting a boundary of a cutting part.SOLUTION: In a method for measuring a weld bead cutting width, a weld bead cutting part 11 is irradiated with a lighting system, the irradiated area is photographed by a camera 3, the photographed image is processed by an image processor 4, and then a weld bead cutting width is measured. The lighting system comprises a left illuminating device 1 for irradiating the weld bead cutting part from the left and a right illuminating device 2 for irradiating the part from the right, so that the irradiation is alternately performed from the left and right by using the both illuminating devices.

Description

  The present invention relates to a weld bead cutting width measuring method, and more particularly to a weld bead cutting width measuring method that effectively improves the measurement performance of the welding bead cutting width after outer bead cutting of an electric resistance welded steel pipe.

  Patent Document 1 discloses a cross section of a weld bead cutting shape measuring method that captures an image of a steel pipe bead cutting portion with a slit light and an optical cutting method using an ITV camera when measuring the shape of the ERW pipe after welding bead cutting. The shape image is thinned and the cross-sectional shape is calculated. The brightness of the cross-sectional shape is used to distinguish between the base material that is the cutting part and the non-cutting part. Based on these three measurement values, the cutting depth is calculated from the left and right measurement values and the base material median value, and the cutting inclination amount is calculated from the left and right measurement values. A method for measuring the shape of an electric-welded pipe weld bead cut is described.

  The method of Patent Document 1 uses a photographed image by slit light, but when only the weld bead cutting width is a measurement target, a photographed image by area (surface) light is used instead of slit (line) light. There is also. In any case, the principle is that the outer bead cutting part to be measured is irradiated with light by an illumination device, the irradiated part is photographed with a camera, and the cutting part and the non-cutting part are taken based on the photographed image. By utilizing the fact that there is a difference in the reflectance of light, the boundary of the cutting part is detected by the difference in the light reception level (luminance).

Japanese Patent No. 2618303

  The flaw detection performance of the ERW welded portion of the ERW steel pipe is greatly influenced by the measurement accuracy of the weld bead cutting width, and if this measurement accuracy is poor, improvement in the flaw detection performance of the ERW weld cannot be expected. When measuring the bead cutting width, whether the slit light or the area light is used, the boundary of the cutting part is detected by brightness. At that time, the surface property of the weld bead cutting part is a fluctuation of the tube material plate width. Since it changes depending on the properties in the vicinity of the boundary of the cutting part, environmental conditions such as water riding, twisting in the pipe circumferential direction, etc., there are not a few cases where the photographed image of the cutting part becomes unclear. Therefore, many arithmetic processes such as moving average of measured values and elimination of abnormal data are required as signal processing. However, it is difficult to accurately measure fine fluctuations in the weld bead cutting width by performing the averaging process by calculation, and therefore there is a problem that there is a limit to improving the flaw detection performance of the ERW weld.

The inventor diligently studied to solve the above-mentioned problems, and as a result, found an irradiation method in which the contrast between the bead cutting part and the non-cutting part of the photographed image is strong, and made the present invention.
That is, the present invention provides a welding bead cutting width measuring method for irradiating a weld bead cutting portion with an illuminating device, photographing the irradiated region with a camera, and processing the photographed image to measure the weld bead cutting width. Two illumination devices, a left illumination device and a right illumination device that irradiate the weld bead cutting part from either the left side at one end of the cutting width direction or the right side at the other end, respectively, are used from the left side. The welding bead cutting width measurement method is characterized in that irradiation with the right side and irradiation from the right side are performed alternately.

  According to the present invention, the contrast between the cutting part and the non-cutting part in the photographed image is increased, the boundary between the cutting parts can be detected more accurately, and the measurement accuracy of the weld bead cutting width is improved. Therefore, when the present invention is applied to the ERW welded portion of the ERW steel pipe, it contributes to the improvement of the flaw detection performance of the ERW welded portion.

It is a schematic diagram which shows one example of embodiment of this invention. It is a figure which shows the area light picked-up image of an Example and a comparative example, (a) (b) is an Example, (c) is a comparative example.

The present invention is the same as the prior art in that the weld bead cutting part is irradiated with an illumination device, the irradiated region is photographed with a camera, and the photographed image is processed to measure the weld bead cutting width. .
However, in the prior art, for example, as illustrated in Patent Document 1, only one illumination device is used, or even if a plurality of illumination devices are used, simultaneous irradiation is performed. On the other hand, in the present invention, the cutting width direction with respect to the weld bead cutting portion is used. Using the left illuminator and the right illuminator that irradiate from the left side that is one end of the both ends and the right side that is the other end, respectively, and performing irradiation from the left side and irradiation from the right side alternately Thus, the present invention is different from the prior art, and by adopting this point, the effect of the present invention is realized.

  FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention. This example is an application example of the ERW steel pipe 10 to the ERW weld. As shown in the drawing, in the present invention, the left illuminating device 1 that irradiates the weld bead cutting part 11 from the left side that is one of the ends in the cutting width direction and the right illuminator that irradiates from the right side that is the opposite side of the left side. 2 was used, and irradiation from the left side and irradiation from the right side were alternately performed.

Then, the irradiated region is photographed by the camera 3 from the front of the weld bead cutting unit 11, and the photographed image (image signal) is sent to the image processing device 4 to perform image processing (signal processing) to measure the weld bead cutting width. To do. In this example, the irradiation light is area light, but slit light may be used instead of area light.
FIG. 2A is an image obtained by photographing an area including a weld bead cutting portion when irradiation is performed only with the left side illumination device 1, and FIG. 2B is when irradiation is performed only with the right side illumination device 2. FIG. 2C is an image obtained by photographing the region including the weld bead cutting portion when the left illumination device 1 and the right illumination device 2 are simultaneously irradiated. is there. When these are compared, when an image irradiated with only the left side lighting device 1 is photographed, a large contrast appears at the boundary between the left weld bead cutting portion and the non-cutting portion, and only from the right side lighting device 2. It can be seen that a large contrast is developed at the boundary between the weld bead cutting part on the right side and the non-cutting part when the irradiated object is photographed. It can also be seen that when the left side illumination device 1 and the right side illumination device 2 are simultaneously illuminated, the contrast between the cut portion and the non-cut portion is reduced. Therefore, the position of the left end of the weld bead cutting part is obtained from the image data photographed when the left illumination device 1 performs irradiation, and the image data photographed when the right illumination device 2 performs irradiation. Can accurately determine the positions of both ends of the weld bead cutting portion by determining the right end position of the weld bead cutting portion.

  The image processing device 4 calculates the luminance distribution in the cutting width direction based on the captured image that has been sent, and in the luminance distribution, the two positions where the luminance change rate is first and second respectively from the maximum side are calculated. Detected as both ends in the width direction of the cutting part (boundary of the non-cutting part). The image processing device 4 further uses the image when the left illumination device 1 emits the image data transmitted from the camera 3 to set the left width direction position of the two positions to the left end of the cutting unit. Of the image data transmitted from the camera 3 and using the two images when illuminated by the right illumination device 2, the right width direction position of the right side of the two positions is used as the right end of the cutting unit. The length between the position of the left end of the cutting part and the position of the left end of the cutting part is calculated, and the result is output as weld bead cutting width data. The details of the signal processing or calculation function are matters within the scope of ordinary technology, and thus detailed description thereof is omitted.

  In addition, the ERW steel pipe 10 which is a material to be measured is often measured while being transferred in the material advancing direction 12 as in this example. In this case, from the viewpoint of improving measurement accuracy, It is preferable to control the irradiation timing and the imaging timing when alternately irradiating the right side and the right side one by one. Therefore, in this example, a timing control means (not shown) is provided inside the image processing apparatus 4 and from there. The irradiation timing and the imaging timing are controlled by the control signal. Since such timing control means is also within the scope of ordinary technology, detailed description thereof is omitted. Note that the timing control means may be provided outside the image processing apparatus 4.

  The present invention was implemented in the same embodiment as the example shown in FIG. FIGS. 2A and 2B show an example of a photographed image when the left and right sides are alternately irradiated as an example. FIG. 2C shows an example of a photographed image when the left and right sides are irradiated simultaneously as a comparative example. In the comparative example, the contrast of the photographed image is weak and the cutting part boundary is unclear, whereas in the example, the contrast of the photographed image is strengthened and the cutting part boundary becomes clear. Thereby, the brightness | luminance change of a cutting part boundary can be caught more correctly, the measurement precision of a weld bead cutting width improves, and it contributes to the improvement of the flaw detection performance of an electric-welding welding part.

  Further, the conventional example is the same as FIG. 1 except that the left side illumination device 1 and the right side illumination device 2 are removed in FIG. 1 and the central portion in the width direction of the cutting portion is irradiated using one illumination device instead. In the embodiment, the weld bead cutting width was measured. In this conventional example, in the continuous measurement for about 20 minutes, nearly half of the measured values are abnormal, and in fact, it should not be so many, so the reliability of the measurement is insufficient. Note that this measurement abnormality detection method is a method in which a measurement abnormality is determined when a measurement value is outside the range of the visual direct measurement result data accumulated in the past. On the other hand, in the example of the present invention, the measurement abnormality was eliminated by 95% or more (reduced to less than 5% of the total number of measured values) in the continuous measurement for about 20 minutes.

DESCRIPTION OF SYMBOLS 1 Left side irradiation apparatus 2 Right side irradiation apparatus 3 Camera 4 Image processing apparatus 10 ERW steel pipe 11 Weld bead cutting part 12 Material advancing direction

Claims (1)

  In the welding bead cutting width measuring method of irradiating the weld bead cutting portion with an illuminating device, photographing the irradiated region with a camera, and processing the photographed image to measure the weld bead cutting width, welding is performed as the illuminating device. Using a left side illumination device and a right side illumination device that irradiate the bead cutting part from either the left side at one end or the right side at the other end of the cutting width direction, respectively. The welding bead cutting width measuring method characterized by alternately performing irradiation.