JP4483391B2 - Method and apparatus for ultrasonic inspection of fillet welds - Google Patents

Description

  The present invention relates to a fillet welded portion ultrasonic inspection method and apparatus for performing a nondestructive inspection of a fillet welded portion in which a fillet weld of the other base material is obliquely welded to one of the base materials.

  For example, an impeller of a large fan used in a plant such as a power plant is configured by welding a blade plate between a main plate and a side plate. FIG. 4 is a block diagram of a large fan impeller, FIG. 4 (a) is a side view, and FIG. 4 (b) is a front view. The impeller 11 is configured by welding a blade plate 14 between a main plate 12 formed in a circular shape and side plates 13a and 13b formed on the inner surface with a special curved surface, and providing a shaft 15 in the center.

  FIG. 5 is an explanatory view of a fillet welded portion of the blade 14 between the main plate 12 and the side plate 13a, FIG. 5 (a) is a partially cutaway partial perspective view of the impeller 1, and FIG. 2 is a cross-sectional view of a blade plate 14. FIG. The blade 14 is fillet welded to the side plate 13a and is also welded to the flat main plate 12 to form fillet welds 16a and 16b, respectively. Further, as shown in FIG. 5B, the vane plate 14 is formed in a hollow shape and is formed in a streamline shape from the blade head 14a to the blade tail 14b.

  In such an impeller 11, the vane plate 14 has a hollow inside, and is thus joined from the outside of the vane plate 14 to the main plate 12 and the side plates 13 a and 13 b by one side fillet welding. Therefore, there are many cases where cracks are prone to occur due to the lack of penetration during construction and the tip becomes a stress-concentrated portion and a crack progresses. Therefore, it is required to detect a crack at the insufficiently melted tip by nondestructive inspection.

  In general, ultrasonic inspection is applied to nondestructive inspection for detecting internal defects in fillet welds. Vertical inspection using a vertical probe, oblique inspection using an oblique probe, or oblique inspection. Detection of a defective part is performed by a flaw detection method using a child and a vertical probe in combination.

In the vertical flaw detection method, ultrasonic waves are sent and received from a vertical probe perpendicular to the flaw detection surface to detect flaws, and the presence of a defective part is examined by looking for a reflected echo that appears before the bottom echo of the object to be inspected. . The bevel flaw detection method uses a bevel probe to send and receive ultrasonic waves in an oblique direction with respect to the flaw detection surface, and the reflected echo returns when it hits a reflection source such as a defective part. The reflected echo is searched for the presence or absence of a defective part (for example, see Non-Patent Document 1).
New Nondestructive Inspection Handbook, Editor: Japan Nondestructive Inspection Association, Publisher: Toshio Fujiyoshi, Publisher: Nikkan Kogyo Shimbun, October 15, 1992, P297-P299

However, since the vertical flaw detection method and the oblique flaw detection method detect the presence / absence of a defect in the object to be inspected, it is difficult to detect the size of the insufficient penetration of the fillet weld. FIG. 6 is an explanatory diagram in a case where the size of the insufficient penetration of the fillet welded portion 16a between the side plate 13a and the blade plate 14 is detected by the vertical flaw detection method using the vertical probe 17. FIG. Since the wing plate 14 has a hollow inside, one side fillet welding is performed from the outside, and the fillet welded portions 16a and 16a ′ are formed, and the insufficiently melted portions 18a and 18a ′ are formed. Now, the case of detecting the size of the insufficiently melted portion 18a will be described. The vertical probe 17 searches for a reflection echo appearing in front of the bottom surface echo of the side plate 13a as an object to be inspected, and checks the presence or absence of a defective portion. For this reason, it is not possible to detect the insufficiently melted starting point portion 19 before the bottom echo. The position of the missing tip 20 penetration because bottom echo on the left side than the missing tip 20 penetration changes can be detected.

FIG. 7 is an explanatory diagram in the case of detecting the degree of insufficient penetration of the fillet welded portion 16a between the side plate 13a and the blade plate 14 by the oblique flaw detection method using the oblique probe 21. FIG. Now, the description will be given of a case where detecting the magnitude of the penetration shortage portion 18a, since the angle probe 21 is used for determining presence or absence of a defect site looking for echoes reflected from the defect site, the penetration shortage tip 20 When there is a reflection echo, the under- melting tip 20 can be detected. However, since the reflected echo does not return on the right side of the insufficiently meltable tip portion 20, the poorly melted start point portion 19 cannot be detected.

As described above, in the vertical flaw detection method using the vertical probe 17, the waveform of the reflected echo does not change depending on whether or not the melting is insufficient, so that the size of the insufficient melting cannot be detected. In addition, in the oblique flaw detection method using the oblique probe 21, even if there is an insufficiently melted portion 18a, the reflected echo from the poorly melted tip portion 20 is difficult to detect because the reflection source is small and the insufficiently melted surface or the poorly melted starting point portion. In 19, since there is no reflection source and the reflected echo does not return, it is not possible to detect the size of the insufficient melting.

  Further, the shape of the fillet welded portion 16a of the impeller 11 is such that the side plate 13a has the blade plate 14 formed with a special curved surface, and therefore the angle formed between the side plate 13a and the blade plate 14 varies along the curved surface. . That is, the weld line of the fillet weld portion 16a is not a straight line, and the weld bead shape is not uniform. This limits the surfaces that can be flaw-detected.

  An object of the present invention is to provide a method and apparatus for ultrasonic inspection of a fillet weld that can detect the size of the lack of penetration of the fillet weld.

The ultrasonic inspection method for a fillet welded portion according to the invention of claim 1 is a method for focusing a point in a direction orthogonal to a weld line of a fillet welded portion in which the other preform is welded in a diagonal direction with respect to one base metal. Operate the bevel angle probe and the distance sensor back and forth to detect reflected echoes at the insufficiently welded tip of the fillet weld and distance from the two different base materials to the point focusing angle probe , And the position of the insufficiently melted tip with respect to the position of the point focusing oblique probe is obtained from the ultrasonic beam path of the detected reflected echo, and the point focusing oblique probe is obtained from two different parts of the other base material. An angle formed by the one base material and the other base material is obtained based on the distance to the child, and a point focusing oblique angle probe is obtained based on the obtained angle formed by the one base material and the other base material. non penetration position of the intersection between one of the base metals and other base material with respect to the position Determined as the position of the starting portion, and obtains the magnitude of the lack penetration from the position of the missing starting portion penetration and position of penetration shortage tip.

The ultrasonic inspection apparatus for a fillet welded portion according to the invention of claim 2 scans back and forth in a direction orthogonal to the weld line of the fillet welded portion in which the other preform is welded in a slanting direction with respect to one base metal. A point-focusing oblique angle probe that detects a reflection echo at the tip of the welded portion that is insufficiently melted, and a fillet welded in an oblique direction with respect to one base material in conjunction with the point-focusing oblique angle probe. A distance sensor for measuring the distance from two different points of the other base material to the point-focusing oblique angle probe, and the ultrasonic beam path of the reflected echo detected by the point-focusing oblique angle probe The position of the insufficiently melted tip with respect to the position of the focusing angle probe is obtained, and the point focusing is performed based on the distance from the two different locations of the other base material to the point focusing angle probe measured by the distance sensor. exchange with one of the base metals and other base metal relative to the position of the angle probe Determined as the position of the missing starting portion penetration position of, characterized in that an arithmetic unit for determining the magnitude of the lack penetration from the position of the missing starting portion penetration and position of penetration shortage tip.

  According to the present invention, the point focusing oblique probe is positioned in a direction orthogonal to the weld line of the fillet welded portion in which the other base material is welded in the oblique direction to the one base material, This is the case where the weld line of the fillet weld is changing in a curved line because the position of the insufficiently welded start point relative to the position of the point focusing oblique angle probe is obtained from the angle formed by the base material and the other base material. However, it is possible to obtain the position of the insufficiently melted start point portion with respect to the position of the point focusing oblique angle probe. On the other hand, the position of the insufficiently welded tip is detected by a point focusing oblique angle probe, and the size of the insufficiently melted point is determined from the position of the poorly melted starting point and the position of the poorly melted tip. Even when the line is changing in a curved line, it is possible to accurately detect the size of the insufficient penetration of the fillet weld.

  FIG. 1 is a configuration diagram of a fillet weld ultrasonic inspection apparatus according to an embodiment of the present invention. In FIG. 1, the case where the magnitude | size of the insufficient penetration of the fillet weld part 16a of the side plate 13a of the impeller 11 of a large fan and the blade plate 14 is shown is shown. The vane plate 14 has a hollow inside, and the side plate 13a is formed with the fillet welded portions 16a and 16a ′ and the underfilled portions 18a and 18a ′ by one-sided fillet welding from the outside. . Hereinafter, a case where the size of the insufficiently melted portion 18a is detected will be described.

  The point-focusing oblique angle probe 22 transmits an ultrasonic wave obtained by narrowing the ultrasonic beam at a predetermined refraction angle θ2 and receives a reflected echo. Scanning back and forth is performed in the direction orthogonal to the weld line, and the reflection echo of the tip portion 20 with insufficient penetration of the fillet weld portion 16 is detected. A distance sensor 23 is attached to the point-focusing oblique probe 22, and the distance sensor 23 is formed of a cylinder linear gauge having two measuring elements 24 a and 24 b, and is connected to a side plate 13 a that is a member to be inspected. Then, two different portions of the blade 14 welded in the diagonal direction are contacted, and the distance from the two locations to the point focusing oblique probe 22 is measured.

  The reflection echo detected by the point-focusing oblique probe 22 and the distance from the two different positions of the blade 14 detected by the distance sensor 23 to the point-focusing oblique probe 22 are input to the arithmetic unit 24. . The arithmetic unit 24 obtains the magnitude F of the lack of penetration based on the reflected echo detected by the point focusing oblique probe 22 and the distance detected by the distance sensor 23, and the obtained lack of penetration F and other necessary values. Information is displayed on the display device 25.

  FIG. 2 is an explanatory diagram of various physical quantities and calculated values that are required when the computing device 24 determines the size F of the lack of penetration. The arithmetic unit 24 detects the position of the insufficiently melted tip 20 from the ultrasonic beam path W of the reflected echo detected by the point focusing oblique probe 22 to the position of the point focusing oblique probe 22, that is, the point focusing oblique angle. The distance Y from the probe 22 to the insufficiently melted tip 20 is obtained by the following equation (1). Note that t2 is the thickness of the side plate 13a, which is a member to be inspected, and θ2 is the refraction angle of the point focusing oblique angle probe 22.

Y = 2 · t2 · tan θ2 (1)
Next, based on the distances a and b from two different positions of the blade 14 measured by the distance sensor 23 to the point-focusing oblique probe 22 , the angle formed between the side plate 13 a and the blade 14 that is a member to be inspected. Obtain θ1. Here, hb is the distance between the two measuring elements 24a and 24b of the distance sensor 23.

θ1 = tan−1 (ba) / hb (2)
Then, using the angle θ1 formed between the side plate 13a and the blade 14 which is a member to be inspected, the position of the insufficiently melted starting point portion 19 with respect to the position of the point focusing oblique probe 22 according to the following equation (3), that is, the point A distance X from the converging oblique angle probe 22 to the insufficient melting start point 19 is obtained. Here, ha is the distance between the side plate 13a, which is a member to be inspected, and the measuring element 24a of the distance sensor 23 of the point focusing oblique probe 22, and t1 is the thickness of the blade plate 14.

X = a−ha · tan θ1 + t1 / cos θ1 (3)
Here, in equation (3), ha · tan θ1 in the second term corresponds to the distance c in FIG. 2, and t1 / cos θ1 in the third term corresponds to the distance d in FIG. The angle formed between the side plate 13a, which is the target member, and the blade plate 14 is θ1 ′. Since the distance ha between the side plate 13a, which is the inspection target member, and the measuring element 24a of the distance sensor 23 of the point focusing oblique probe 22 is smaller than the size of the blade 14, θ1 ′ can be approximated to θ1. When the curvatures of the side plate 13a and the blade plate 14 that are inspection target members are known, θ1 is corrected in advance by the curvature, and a value close to the true value of θ1 ′ is used.

  Then, the distance Y from the point-focusing oblique angle probe 22 determined by the equation (1) to the insufficiently melted tip 20 and the insufficiently-melting starting point portion 19 from the point-focusing oblique angle probe 22 determined by the equation (3). From the distance X up to this point, the size F of the lack of penetration is obtained by the following equation (4).

F = X−Y (4)
Next, the ultrasonic inspection method for a fillet weld according to the embodiment of the present invention will be described. FIG. 3 is a process diagram of the fillet weld ultrasonic inspection method according to the embodiment of the present invention. The point-focusing oblique probe 22 and the distance on the surface of the side plate 13a to be inspected are perpendicular to the weld line of the fillet welded portion 16a in which the side plate 13a to be inspected and the blade plate 14 are welded to the fillet. The sensor 23 is operated back and forth (S1).

  Then, the reflected echo from the point-focusing oblique probe 22 is detected, and the distance from the two different locations of the blade 14 to the point-focusing oblique probe 22 is measured by the distance sensor 23 (S2). In this case, the point-focusing oblique angle probe 22 detects the reflection echo of the tip portion 20 with insufficient penetration of the fillet weld portion 16.

  Next, based on the reflected echo from the point-focusing oblique angle probe 22, the position of the poorly melted tip 20 is obtained (S3). The position of the poorly melted tip 20 is obtained using the above-described equation (1).

  On the other hand, the angle formed between the side plate 13a and the blade plate 14 is obtained based on the distance from the two different locations of the blade plate 14 detected by the distance sensor 23 to the point focusing oblique angle probe 22 (S4), and the side plate 13a. Based on the angle formed between the blade 14 and the blade 14, the position of the melting start point 19 is determined (S 5). The angle formed by the side plate 13a and the blade plate 14 is obtained using the above-described equation (2), and the position of the insufficiently melted starting point portion 19 is obtained using the above-described equation (3).

  And the size F of the lack of penetration is calculated | required from the position of the poorly melt | dissolving front-end | tip part 20 and the position of the poorly melt | dissolved start part 19 (S6).

  In this way, the point focusing oblique probe 22 is positioned in the direction orthogonal to the weld line of the fillet welded portion 16a in which the blade plate 14 is welded in the oblique direction to the side plate 13a, and the side plate 13a and the blade plate 14 is obtained from the angle θ1 formed by 14 with respect to the position of the point-focusing oblique probe 22, even if the weld line of the fillet weld 16 changes in a curved line. The position of the start point 19 with insufficient melting relative to the position of the point focusing oblique probe 22 can be obtained.

  Then, the position of the insufficiently melted tip 20 is detected by the point focusing oblique probe 22 and the insufficiently melted magnitude F is obtained from the position of the poorly melted start point 19 and the position of the poorly melted tip 20. Even when the weld line of the meat weld portion 16a changes in a curved shape, the size of the insufficient penetration of the fillet weld portion 16a can be accurately detected.

The block diagram of the fillet weld ultrasonic inspection apparatus concerning embodiment of this invention. Explanatory drawing of the various physical quantities and calculation value which are needed when calculating | requiring the magnitude | size of the lack of penetration with the arithmetic unit in embodiment of this invention. The process figure of the fillet weld part ultrasonic inspection method concerning embodiment of this invention. The block diagram of the impeller of a large fan. Explanatory drawing of the fillet weld part of the blade plate between the main plate and side plate of the impeller of a large fan. Explanatory drawing in the case of detecting the magnitude | size of the lack of penetration of the fillet weld part of the side plate and blade plate of the impeller of a large fan by the vertical flaw detection method by a vertical probe. Explanatory drawing in the case of detecting the lack of penetration of the fillet welded portion between the side plate and the blade plate of the impeller of a large fan by the oblique flaw detection method using the oblique probe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Impeller, 12 ... Main plate, 13 ... Side plate, 14 ... Blade plate, 15 ... Shaft, 16 ... Fillet welded part, 17 ... Vertical probe, 18 ... Poor penetration part, 19 ... Poor penetration start part , 20 DESCRIPTION OF REFERENCE SYMBOLS : Poor penetration tip , 21 ... Bevel probe, 22 ... Point focusing bevel probe, 23 ... Distance sensor, 24 ... Measuring element, 25 ... Display device

Claims (2)

Operate the point focusing oblique angle probe and the distance sensor back and forth in the direction orthogonal to the weld line of the fillet welded part where the fillet of the other base material is welded in the diagonal direction with respect to one base metal, Detects the reflection echo at the tip of the part where the penetration is insufficient and measures the distance from the two different points of the other base material to the point focusing oblique probe, and the point focusing from the ultrasonic beam path of the detected reflection echo Finding the position of the insufficiently melted tip with respect to the position of the oblique probe, based on the distance from the two different locations of the other base material to the point focusing oblique probe, the one base material and the other base material The position of the intersection of one base material and the other base material with respect to the position of the point focusing oblique probe based on the angle formed by the one base material and the other base material determined as the position of the missing starting portion penetration and a position of penetration shortage tip Fillet welds ultrasonic inspection method characterized by determining the magnitude of the lack penetration from the position of the missing start part riser. Scanning back and forth in the direction perpendicular to the weld line of the fillet welded portion where the other base material is welded in the oblique direction to one base metal, and detects the reflection echo of the insufficiently welded tip of the fillet welded portion The point-focusing oblique angle probe and the point-focusing oblique angle probe from two different locations of the other base material, which is interlocked with the point-focusing oblique angle probe and welded in the oblique direction to the one base material. Determine the position of the insufficiently melted tip with respect to the position of the point focusing oblique probe from the distance sensor for measuring the distance to the probe and the ultrasonic beam path of the reflected echo detected by the point focusing oblique probe. The one base material and the other base material with respect to the position of the point focusing oblique probe based on the distance from the two different places of the other base material measured by the distance sensor to the point focusing oblique probe determined as the position of the lack of a starting point unit penetration of the position of intersection of the, melt write Fillet welds ultrasonic inspection apparatus characterized by comprising an arithmetic unit for determining the magnitude of the lack penetration from the position of the missing starting portion penetration and location of the missing tip.

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