JP2014202511A - Method and device for inspecting drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method capable of detecting a cross-sectional defect part of a drum in a stacked state from an external surface side.SOLUTION: A drum inspection method for allowing an SH wave to be incident on a side plate side of a drum includes: a fixing step of fixing a side plate ultrasonic probe on an upper side part and/or a lower side part of the side plate surface; a first detection step of allowing the SH wave to be incident on the side plate surface at this fixing position and detecting a cross-sectional defect part as an echo height; a second detection step of causing the probe to rotate with this fixing position as a center, causing the SH wave having an angle of a different incident direction to be incident and detecting the cross-sectional defect part as the echo height; and a first position detection step of detecting the position of the cross-sectional defect part from the direction of the cross sectional defect part estimated by a difference of a distance time to the echo of the cross-sectional defect part at the same place with the first detection step and the second detection step, and from the distance to the defect part.

Description

  The present invention relates to a drum can inspection method and apparatus for inspecting a defective portion and corrosion of a drum can.

  The drum can is used when temporarily storing and transporting a liquid such as petroleum. In addition, inspections that can detect cross-sectional defects such as corrosion or rust generated on the inner and outer surfaces of drum cans containing low-level radioactive waste from the outer surface, such as wear due to physical factors, can be identified. There has been proposed a drum inspection method and apparatus capable of establishing a technique, measuring a remaining thickness of a cross-sectional defect portion, and obtaining data on a remaining life (see, for example, Patent Document 1).

  This drum can inspection method performs a primary inspection to detect a cross-sectional defect portion generated in a drum can by a transverse wave ultrasonic wave and estimate a range, and performs a vertical flaw detection on a range obtained by the primary inspection by a longitudinal wave ultrasonic wave. This is an inspection method for performing a secondary inspection to detect the degree of thinning. In the primary inspection, transverse wave ultrasonic waves are propagated from the upper end to the lower end of the side plate of the drum can and from the lower end to the upper end, or the ultrasonic waves of the transverse wave are transmitted to the outer peripheral edges of the top and bottom plates of the drum can. It propagates from the center to the center.

  In addition, the drum can inspection apparatus includes a primary inspection ultrasonic device for performing a primary inspection for detecting and detecting a cross-sectional defect portion generated in a drum can by a transverse wave ultrasonic wave, and a primary inspection by a longitudinal wave ultrasonic wave. A drum inspection apparatus including a secondary inspection ultrasonic device for performing a secondary inspection for detecting the degree of thinning by performing a vertical flaw detection in the obtained range.

JP 2008-17596A

  However, for example, the current state of storage of drum cans containing low-level radioactive waste is a state in which a large number of drum cans are piled up, and about 1/3 of the side surface is substantially exposed. Therefore, this exposed surface is the actual work range, and the bottom surface is in a state where the work cannot be performed substantially. It is also piled up when storing specific waste.

  The present invention provides an inspection method and apparatus capable of detecting a cross-sectional defect portion of a drum can from the outer surface side even in a state of being piled up and substantially 1/3 of the side surface being exposed. The purpose is to obtain.

A drum can inspection method according to the invention described in claim 1 is an inspection method for detecting a cross-sectional defect portion generated in a drum can from the outer surface side, and the SH plate has a SH wave on the side plate surface from the ultrasonic flaw detection means. In a drum inspection method for detecting the defect by entering the
A mounting process for mounting a side plate ultrasonic probe as an ultrasonic flaw detection means on the upper side and / or lower side of the side plate surface, and SH waves are incident on the side plate surface at this mounting position, and the cross-sectional defect portion is set as the echo height. A first detection step for detecting, and a second detection for detecting the cross-sectional defect as the echo height by rotating the side plate ultrasonic probe around the mounting position and causing the SH wave having a different angle in the incident direction to enter. From the detection step, the direction of the cross-sectional defect portion inferred from the difference in distance time to the echo of the cross-sectional defect portion at the same point in the first detection step and the second detection step, and the distance to the defect portion And a first position detecting step for detecting the position of the cross-sectional defect portion.

  According to a second aspect of the present invention, there is provided a drum can inspection method comprising: a second attachment step of attaching a side plate ultrasonic probe to a side opposite to an attachment position in the attachment step according to claim 1; An anti-first detection step in which a SH wave is incident on the side plate surface in the opposite direction to the first detection step to detect the cross-sectional defect as the echo height, and the side plate ultrasonic probe is centered on the second mounting position. The anti-second detection step in which the SH wave having a different angle in the incident direction by rotating the element is made incident to detect the cross-sectional defect portion as the echo height is the same as the anti-first detection step and the anti-second detection step. A second position detecting step for detecting the position of the cross-sectional defect portion from the direction of the cross-sectional defect portion estimated from the difference in distance time to the echo of the cross-sectional defect portion at the point and the distance to the defect portion; First position detection step and second position detection It is characterized in that it comprises extent further the integration position detection step of detecting a position of the cross defect from.

  A drum can inspection method according to a third aspect of the present invention is directed to an SH wave from a bottom plate ultrasonic probe attached to a fitting edge of a bottom plate of the drum can according to claim 1 or 2 with a side plate at the periphery of the bottom plate. Further, a bottom plate inspection for detecting a cross-sectional defect portion by entering the substrate in a direction perpendicular to the bottom plate plane is further performed.

A drum can inspection device according to the invention described in claim 4 is a drum can inspection device provided with ultrasonic flaw detection means for detecting a cross-sectional defect portion generated in the drum can from the outer surface side,
As ultrasonic flaw detection means, a side plate ultrasonic probe that detects a cross-sectional defect by making SH waves incident in the circumferential direction of the side plate, and the side plate ultrasonic probe is connected to the upper side of the side plate surface of the drum can and And / or a probe mounting jig that can be attached to the lower side portion and can rotate the side-plate ultrasonic probe at least 1/4 at this mounting position.

  According to a fifth aspect of the present invention, there is provided the drum inspection apparatus according to the fourth aspect, wherein the ultrasonic flaw detection unit according to the fourth aspect is separated from the upper side and the lower side on a predetermined circumference of the side plate surface by two. 4 side plate ultrasonic probes for detecting a cross-sectional defect by making SH waves incident on the side plate in the circumferential direction, and 4 can be rotated by a quarter at each of the mounting positions of the side plate ultrasonic probes. And two probe mounting jigs.

  A drum can inspection apparatus according to the invention described in claim 6 is attached to the fitting edge of the periphery of the bottom plate of the drum can according to claim 4 or 5 at an interval, and the SH wave is incident in a direction perpendicular to the plane of the bottom plate. And a pair of bottom plate ultrasonic probes for detecting a cross-sectional defect portion.

  INDUSTRIAL APPLICABILITY The present invention provides an inspection method capable of accurately detecting a cross-sectional defect portion of a drum can from the outer surface side even when it is in a piled state and substantially 1/3 of the side surface is on the surface. There is an effect that an apparatus can be obtained.

It is a front view of a drum can. It is a top view of a drum can. It is a diagram which shows the flaw detection waveform as a result of irradiating a SH wave horizontally toward the measurement line 1 toward R1-R9. It is a diagram which shows the flaw detection waveform as a result of irradiating SH wave horizontally from the survey line 2 toward S1-S9. It is a diagram which shows the flaw detection waveform as a result of irradiating SH wave horizontally from the measurement line 3 toward S1-S9. It is a diagram which shows the flaw detection waveform as a result of irradiating a SH wave horizontally from the new measurement line 200 mm away from the welding line A. It is explanatory drawing which shows the structure of the rotation auxiliary | assistant acrylic jig created so that this ultrasonic probe and this ultrasonic probe could be rotated smoothly. It is an expanded view of the side plate model used for the flaw detection test. It is a diagram which shows the flaw detection waveform of the result of a flaw detection test, a figure shows the result of 22.5 degrees from horizontal, and b figure shows the result of 52.5 degrees from horizontal. It is the front view and side plate development view which show the attachment position of the flaw detection test using four probes. It is a diagram which shows the flaw detection waveform as a result of irradiating SH wave toward the R1-R9 from the fitting part of the baseplate with the same sensitivity (40 dB) at the time of side plate search. It is a diagram which shows the flaw detection waveform as a result of irradiating SH wave toward the R1-R9 from the fitting part of the baseplate in the case of raising sensitivity.

  In the present invention, a side plate ultrasonic probe as an ultrasonic flaw detector is attached to the upper side and / or the lower side of the side plate surface, and a SH wave is incident on the side plate at this attachment position to form a cross-sectional defect portion. A first detection step for detecting the echo height and a SH wave having a different angle in the incident direction by rotating the side-plate ultrasonic probe around the attachment position to make the cross-sectional defect portion an echo height The second detection step to detect, the direction of the cross-sectional defect portion inferred by the difference in distance to the echo of the cross-sectional defect portion at the same point in the first detection step and the second detection step, and to the defect portion And a first position detecting step for detecting the position of the cross-sectional defect portion from the distance. Thereby, even if it is in the state where it piles up and the about 1/3 of side surface has come out to the surface, the cross-sectional defect | deletion part of the side wall surface of a drum can can be detected from an outer surface side.

  Preferably, a second mounting step of attaching a side plate ultrasonic probe to a side opposite to the mounting position in the mounting step, and SH waves are incident on the side plate in the opposite direction to the first detection step at the second mounting position. Then, the anti-first detection step of detecting the cross-sectional defect portion as the echo height, and the SH wave with the angle of the incident direction different from each other by rotating the side plate ultrasonic probe around the second attachment position. The anti-second detection step of detecting the cross-sectional defect portion as the echo height and the difference in time between the anti-first detection step and the anti-second detection step to the echo of the cross-sectional defect portion at the same point The position of the cross-sectional defect portion from the second position detection step of detecting the position of the cross-sectional defect portion from the direction of the cross-sectional defect portion and the distance to the defect portion, and the first position detection step and the second position detection step. Integrated position detection process to detect By further comprising, it is possible to more accurately identify over the cross cut portion all around the drum.

  The ultrasonic flaw detection means of the present invention only needs to irradiate SH waves that are one of transverse waves. Specifically, as ultrasonic waves generally used for ultrasonic flaw detection, there are SV waves that are one type of longitudinal waves and transverse waves, and SH waves that are also one type of transverse waves. Longitudinal waves are waves that vibrate in the propagation direction, and do not vibrate in a direction perpendicular to the propagation direction. On the other hand, the SV wave is a transverse wave that vibrates in a direction perpendicular to the propagation direction, and a wave that vibrates in a direction perpendicular to the flaw detection surface. There is directionality because it is a transverse wave.

  On the other hand, the SH wave is a transverse wave having the same direction as the SV wave, but is a wave oscillating in a direction parallel to the flaw detection surface. Unlike the SV wave, the SH wave has a characteristic that allows the transverse wave to be strongly incident on the object even in a direction near a refraction angle of 90 °. Therefore, in the present invention, the SH wave is applied in consideration of the fact that the plate thickness of the target drum can is thin and that the ultrasonic wave is propagated to some extent.

  This SH wave has directionality, and the propagation angle is about 29 degrees in the ultrasonic probe. For this reason, it becomes possible to measure the position of the defect | deletion part by detecting the reflection from the defect | deletion part which exists in a side plate surface not in one place of a drum can but in a different place. In addition, it is preferable that the mounting position which becomes the center of rotation of the side plate ultrasonic probe of the present invention coincides strictly with the incident point of the SH wave from the probe to the drum can side plate. If the probe is rotated around the incident point, even if there is a defect near the incident point, it can be detected, and the distance from the incident point does not shift even for a defect that is far away. It is.

  In addition, for the bottom plate of the drum can, further bottom plate inspection is performed in which a SH wave is incident in a direction perpendicular to the bottom plate plane from the bottom plate ultrasonic probe attached to the fitting edge of the bottom plate periphery to detect a cross-sectional defect portion. Thus, even when the state is a state of being piled up and substantially 1/3 of the side surface is exposed, the cross-sectional defect portion of the bottom plate portion of the drum can can be detected from the outer surface side.

  The SH wave is incident on the side plate and the bottom plate of the drum can to detect the defect portion. The SH wave is incident on the side plate surface from the contact portion between the ultrasonic probe and the side plate surface and exists on the side plate surface. What is necessary is just to detect the reflected wave from a defect | deletion part with an ultrasonic probe.

  In the present invention, the frequency of the SH wave incident on the object is preferably selected from the range of 0.3 MHz to 0.8 MHz. When the frequency is lower than 0.3 MHz, the wavelength becomes large with respect to the scratched / defected portion of the drum can and cannot be inspected with sufficient accuracy. When the frequency is higher than 0.8 MHz, the attenuation is increased and the sufficient distance cannot be propagated. This is because the inspection cannot be performed with sufficient accuracy. A more preferable frequency is 0.4 MHz to 0.6 MHz, and a most preferable frequency is 0.5 MHz.

  The inspection object of the present invention is a drum can. This drum was originally used for transporting crude oil and kerosene, but has recently been used for transporting chemical products and paints. It is also used for storing low-level radioactive waste or storing and storing specific waste.

  This drum can has a side plate corresponding to a side wall of a cylinder, and a top plate and a bottom plate above and below the side plate. The inside and outside of each wall surface of the drum can may be plated or coated with a resin film. For example, many drums are galvanized on both sides of the side plate, top plate, and bottom plate, and a resin film is provided on the surface of the galvanized layer. More specifically, the iron plate has a thickness of 1.6 mm, the galvanized layer has a thickness of 0.02 mm, and the resin film layer has a thickness of 0.03 mm. In addition, although an epoxy resin is used for a resin film layer, for example, it is not limited to this. In drums for storing low-level radioactive waste, open-type drums that can be removed are mainly used for the top plate.

  The drum can is formed as follows. First, after bending the steel plate into a cylindrical shape and welding both ends, the side plates are squeezed out at both ends, and ring zones are formed at two locations inside the cylinder to face the force from the side of the cylinder. . The top plate and the bottom plate are subjected to a pre-curl process in which the periphery of a steel plate punched into a circular tray is bent. After the surface of the side plate, the top plate and the bottom plate is treated and painted, the lower edge of the side plate and the peripheral edge of the bottom plate are wound and processed to form a drum can. By the tightening process, the lower edge portion of the side plate and the peripheral edge portion of the bottom plate are wound twice or three times to form a fitting portion. In an open-type drum can, bending is performed so that the upper edge portion of the side plate and the peripheral portion of the top plate can be engaged with each other.

  The side plate of the drum can is formed into a cylindrical shape by welding, and the welded portion formed in the vertical direction of the top plate-bottom plate is welded as described later for ultrasonic flaw detection crossing the welded portion. Ultrasonic waves are transmitted beyond it to detect the defect.

  Furthermore, in the present invention, a bottom plate inspection is further performed in which a SH wave is incident in a direction perpendicular to the bottom plate plane from a bottom plate ultrasonic probe attached to the fitting edge of the bottom plate periphery to detect a cross-sectional defect portion. Thereby, even if it is in the state where about 1/3 of the side surface in the piled up state is appearing on the surface, it can be detected.

  Moreover, the drum inspection apparatus of the present invention includes, as ultrasonic flaw detection means, a side plate ultrasonic probe for detecting a cross-sectional defect portion by making SH waves incident in the circumferential direction of the side plate, and a side plate ultrasonic probe. A probe mounting jig that can be attached to the upper side and / or the lower side of the side surface of the drum can and at least 1/4 turn of the side surface ultrasonic probe at the mounting position; Four side plate ultrasonic probes for detecting a cross-sectional defect portion by causing SH waves to enter the circumferential direction of the side plate in two circumferential directions apart from each other on an upper side and a lower side on a predetermined circle; And four probe mounting jigs that can be rotated by 1/4 at each mounting position of the side plate ultrasonic probe.

Example 1 (Investigation of exploration of missing drum can by inputting SH wave side plate in circumferential direction)
1-1. Inspection method In the local storage state of the drum can to be surveyed, about 1/3 of the side surface is the actual work range, and the bottom surface is in a state where the work is practically impossible. For this reason, the method of inputting the SH wave from the vertical direction with respect to the side surface of the drum can cannot be searched. In order to avoid this, we devised a method in which the ultrasonic wave incident direction of the probe is horizontal along the circumference on the side plate and the bottom plate is incident from the fitting part, and an experiment to confirm the possibility of exploration was conducted. It was.

1-2. Configuration of Drum Can FIG. 1 is a front view of the drum can. FIG. 2 is a plan view of the drum. The shape, dimensions, and inner diameter of the used drum can are as follows. Drum can inner diameter (567 ± 3 mm), outer height (890 ± 5 mm), capacity (212L or more), plate thickness (1.6 mm).

1-3. Inspection device The ultrasonic flaw detector uses a low-frequency general-purpose ultrasonic probe UI-23LF manufactured by Ryoden Shonan Electronics Co., Ltd., and the frequency of the SH wave probe is 0.5 MHz.

1-4. Experimental procedure
(1) A through hole and a non-penetrating conical flaw were processed on the drum can side plate. Specifically, it is the through holes S1 to S9 indicated by black squares in the front view of the drum shown in FIG. Although not shown, non-through holes R1 to R9 are formed on the inner side of the drum can at about 700 mm away from the welding line A through the measurement line 2 on the back side of FIG.
(2) A through hole and a non-through conical flaw were processed on the drum can bottom plate. Specifically, in the plan view of the drum shown in FIG. 2, there are non-through scratches A1 to A8 indicated by black circles and through holes B1 to B8 indicated by black squares.

1-5. Measurement of side plate Drum can side plate was measured. In order to verify whether the ultrasonic wave propagates through the welded portion, two of the survey line 1 and the survey line 2 were set with the welded part A interposed therebetween. As shown in FIG. 1, the survey line 1 is formed with a through hole S1 of the drum can side plate, and is a point of about 95 mm from the weld line A on the surface. The measurement line 2 is arranged on the opposite side of the measurement line 1 with respect to the surface welding line A, and is about 410 mm from the welding line A. Moreover, the survey line 3 which was 218 mm away from S9 was set. For each survey line, the ultrasonic probe 11 as the side plate ultrasonic flaw detection means is fixed to the side plate through a contact medium exclusively for transverse waves and irradiated with SH waves at a total of three locations between the end and the rim or between the rims. did.

The conditions for ultrasonic flaw detection on the side plate were as follows.
Gain: 40.0 dB, Test frequency: 0.5 MHz
Measurement range: 1000 mm Refraction angle: 90.0 °
Speed of sound: 3.22 km / s

(5-1) Measurement at Survey Line 1 FIG. 3 is a diagram showing a flaw detection waveform as a result of irradiating SH waves from the survey line 1 toward the non-through holes R1 to R9. Fig. a shows the result of installing an ultrasonic probe between the upper end of the survey line 1 and the first rim, and Fig. b shows the result of installing the ultrasonic probe between the first rim and the second rim on the survey line 1. The figure c shows the result of installing an ultrasonic probe between the second rim on the survey line 1 and the lower end.

  As shown in FIGS. a to c, the broken line portion is displayed as a reflection echo, and the height is displayed as a reflection echo height of 0 to 100%. The number below is the distance from the probe (mm). As shown in each figure, it was shown that the ultrasonic wave of the SH wave is transmitted beyond the weld line A to detect the non-through hole.

(5-2) Measurement at Survey Line 2 FIG. 4 is a diagram showing a flaw detection waveform as a result of irradiating SH waves from the survey line 2 toward S1 to S9. The figure shows the result of installing an ultrasonic probe between the upper end on the survey line 2 and the first rim. As shown in the figure, the broken line portion is displayed as a reflection echo, and the height is displayed as a reflection echo height of 0 to 100%. The number below is the distance from the probe (mm). It was shown that SH wave ultrasonic waves are transmitted beyond the weld line A to detect non-through holes.

(5-3) Measurement at Survey Line 3 FIG. 5 is a diagram showing a flaw detection waveform as a result of irradiating SH waves from the survey line 3 toward S1 to S9. Fig. a shows the result of installing an ultrasonic probe between the upper end of the survey line 1 and the first rim, and Fig. b shows the result of installing the ultrasonic probe between the first rim and the second rim on the survey line 1. The figure c shows the result of installing an ultrasonic probe between the second rim on the survey line 1 and the lower end.

  As shown in FIGS. a to c, the broken line portion is displayed as a reflection echo, and the height is displayed as a reflection echo height of 0 to 100%. The number below is the distance from the probe (mm). As shown in each figure, it was shown that the ultrasonic wave of the SH wave is transmitted beyond the weld line A to detect the non-through hole.

(5-4) Measurement on a new survey line The reflected echo that crossed the weld line A was further verified. The ultrasonic probe 11 was fixed to the side plate via a contact medium dedicated to transverse waves on a measurement line 200 mm away from the through hole S1 with the welding line A as the center, and SH waves were irradiated. FIG. 6 is a diagram showing a flaw detection waveform as a result. As shown in the figure, the broken line portion is displayed as a reflection echo, and the height is displayed as a reflection echo height of 0 to 100%. The number below is the distance from the probe (mm).

  As shown in FIG. 6, it is shown that there are clear flaws at points of 200, 340, 380, and 635 mm. Here, the 200 mm reflection echo is from the weld. In actual measurement, if two circles with the radius of the value of the reflected echo obtained from the measurement from two places are drawn on the drum can surface, there will be a scratch at the intersection.

  It was confirmed that 340 mm was a S2 scratch and 380 mm was a S3 scratch. In addition, it was unknown whether 635 mm was an echo indicating scratch or noise, but it was confirmed that 635 mm was an unnamed scratch. As described above, it was confirmed that the horizontal exploration was sufficiently possible for the side plate.

(5-5) Confirming the propagation range on the side plate Place the probe from the survey line 2 to the non-through hole R1. In this case, since there is no sensitivity at the position where the probe 11 is attached to the upper end, since R1 is found at a position of 200 mm at a survey point 52 mm lower than the upper end, the SH wave when inputting laterally to the side plate It was confirmed that the propagation angle was about 29 degrees.

Example 2 (Examination of exploration of missing drum can by rotation of ultrasonic probe)
2-1. Inspection method In order to more accurately identify the cross-sectional defect, each echo height was measured using an acrylic jig that allows the ultrasonic probe to rotate at the mounting position. FIG. 7 is an explanatory view showing a configuration of an ultrasonic probe and a rotation auxiliary acrylic jig that is prepared so that the ultrasonic probe can be smoothly rotated.

  As shown in FIG. 7, the rotation auxiliary acrylic jig 72 includes a curved bottom surface 73 corresponding to the curved surface of the side wall of the drum can, and a circular portion that comes into contact with the flat bottom surface of the SH wave probe 71 at the center on the surface side. Three indentations 74 are provided, and three magnets 75 for fixing the drum can to a desired position on the side wall of the drum can are arranged at three locations outside the measurement range. It should be noted that even if there is a defective portion in the vicinity of the attachment position that becomes the center of rotation of the probe 71, it becomes possible to detect well, and since the deviation of the distance to the remote defective portion does not occur, SH It arrange | positions so that the incident point of the wave probe 71 and the center of rotation of the acrylic jig 72 may correspond.

  Although no fixing means for fixing the SH wave probe 71 is disclosed in FIG. 7, it is not necessary to move the probe when the ultrasonic flaw detector is driven. As with the acrylic jig 72, the SH wave probe may be fixed with an L-shaped or gate-shaped jig that is fixed to the drum can with a magnet, or the SH wave probe may be fixed to the acrylic jig itself. A control unit for controlling the rotational drive of the drive unit may be provided in the ultrasonic flaw detector by integrating the probe and the drive unit for rotating the probe.

2-2. Inspection device As the ultrasonic flaw detector, a Starmans portable phased array ultrasonic flaw detector DIO-1000 and an SH wave probe (0.5Z20 × 20HA90: manufactured by Japan Probe Co., Ltd.) were used. The inspection conditions such as frequency are as shown in Table 1 below.

2-3. Experimental Procedure FIG. 8 is a development view of the side plate model used in the flaw detection test. For the side plate model 81 of FIG. 8, a steel plate having the same thickness as a drum can of 890 mm in length and 900 mm in width is prepared, and scratches a 1, a 2, a 3 to f 1, f 2, f 3 are attached concentrically with respect to the position P. Each scratch is a direction in which the set of a is rotated 7.5 degrees from the horizontal plane, the set of b is a direction rotated by 15 degrees with respect to the set of a, and the subsequent set of c and set of d , E and f are also rotated by 15 degrees.

  As shown in FIG. 8, the ultrasonic probe 71 is attached to the position P via the rotation auxiliary acrylic jig 72 of FIG. 7, and scratches a1, a2, a3 to f1, arranged concentrically with respect to the attachment position P Reflected echoes at f2 and f3 were detected. At that time, a total of 6 times was performed so that the angle of the ultrasonic flaw detector 71 was directly opposed to each of the groups a to f. The results are shown in the following Table 2 and FIG.

  9 is a diagram showing a flaw detection waveform as a result of a part of Table 2. FIG. 9A shows the result of 22.5 degrees from the horizontal, and FIG. 9B shows the result of 52.5 degrees from the horizontal. As shown in FIGS. a and b, scratch echoes were respectively confirmed. The same applies to the case of rotating every 15 degrees other than the diagrams a and b.

  As shown in FIG. 9 and Table 2, it was also confirmed that the height and variation of the scratch echo became smaller in proportion to the distance. Even if the gain is 95 dB, if the distance to the scratch is long, the echo height may be 10% or less, so it is necessary to carefully judge the scratch. When the angle is 52.5 degrees or more, a waveform like an echo from the bottom (bottom surface) appears, so care must be taken not to misidentify it as a scratch.

2-4.4 Point Rotating Flaw Inspection Apparatus As described above, it was found that the SH wave has directivity and the propagation angle is about 29 degrees. In addition, the shorter the distance from the probe, the higher the echo height, and it is possible to detect a defect such as a scratch. Therefore, a drum can inspection method using four probes and an apparatus thereof were studied in order to detect a missing portion of the side plate of the drum can in which about 1/3 of the side surface is exposed.

  FIG. 10 is a front view and a side plate development view showing attachment positions of a flaw detection test using four probes. As shown in FIG. 10, two probes 71a and 71b for allowing SH waves to be incident in the same lateral direction on the upper side of the side surface of the drum can and the lower side opposite to the upper side, and these two probes 71a , 71b, and four probes 71c and 71d that make the SH waves in opposite directions incident on each other are fixed back to back, and each probe 71a to 71d is 90 degrees from the horizontal direction. A reflected echo is detected when the probe is rotated in the direction.

  In each probe, the distance from the probe is known from the time for detecting the reflected echo. The scratches on the side plate can be determined from the distance from each probe based on the data of the upper side and the lower side. In addition, since the echo height at the rotational position facing the scratch is high, the direction of the scratch from the probe can be determined. This makes it possible to grasp the exact position of the scratch. In addition, because the data for grasping the flaw is used on the opposite side surface of the farthest drum can by the two upper and lower probes that make the SH wave in the opposite direction incident, it is possible to grasp the exact flaw position. Become.

Example 3 Measurement of bottom plate (examination of exploration of missing drum can by fitting SH plate bottom plate)
3-1. Measurement on the bottom plate In the plan view shown in FIG. 2, the ultrasonic probe 21 as the bottom plate ultrasonic flaw detection means is fixed to the side plate via a contact medium dedicated to the transverse wave at the position corresponding to 6 o'clock and irradiated with SH waves. . The ultrasonic probe 21 was irradiated with an acrylic jig 22 fitted to the curvature of the side surface of the bottom plate and brought into contact with the fitting portion of the bottom plate.

The conditions for ultrasonic flaw detection on the bottom plate were as follows.
Gain: 40.0 dB, Test frequency: 0.5 MHz
Measurement range: 2730 mm Refraction angle: 90.0 °
Speed of sound: 3.22 km / s

  FIG. 11 is a diagram showing a flaw detection waveform as a result of irradiating SH waves from the fitting portion of the bottom plate toward R1 to R9 with the same sensitivity (40 dB) as in the side plate search. As shown in the figure, a plurality of reflected echoes and reflected echoes from the facing end were confirmed. Since the SH wave is incident at an angle, it can be appropriately brought into contact with the fitting portion by the acrylic jig 22, and the sensitivity is improved as compared with the case where the probe is used alone.

  Next, the length to the entrainment part and edge part of a fitting part was measured. The entrainment part was 40 mm, and it was 620 mm up to the end of the facing surface. In the measurement screen of FIG. 11, there was an echo at 615 mm, but it seemed to be a looseness error in the tape measure measurement. Therefore, the sensitivity was increased and the echo position was confirmed (+10 dB). FIG. 12 is a diagram showing a flaw detection waveform as a result of irradiating SH waves from the fitting portion of the bottom plate toward R1 to R9 when sensitivity is increased.

  As shown in the figure, a plurality of reflected echoes were confirmed at 145, 180, 200, 220, 240, 265, and 300 mm. Compared with the actual one, it was confirmed that 145 mm was B6 (error 5 mm), 180 mm was B5, 200 mm was B4, 220 was B3, 240 was B2, and 265 was B1. Although 300 could not be confirmed directly, it was thought to be A1. As described above, it has been confirmed that the entire surface of the bottom surface can be detected by moving the ultrasonic probe 21 about one third of the time along the fitting portion on the bottom surface.

  As described above, by inspection of the side plate, ultrasonic waves beyond the welded portion of the drum can side plate are detected by detecting the cross-sectional defect by injecting SH waves into the circumferential direction of the side plate from the ultrasonic flaw detector attached to the side plate surface. Can be detected and the chipped portion can be detected, so that the cross-sectional chipped portion of the drum can can be seen from the outer surface side even when about 1/3 of the side surface is on the surface. It was confirmed that it could be detected. By using this side plate inspection as a preliminary inspection for precise inspection, it is possible to shorten the inspection time and the inspection cost. In the conventional precise vertical flaw detection method, one inspection area is about 10 × 10 mm, and it is impossible to inspect a wide surface. Therefore, if the inspection is performed more accurately by the vertical flaw detection method by greatly narrowing the region including the problematic part in the present inspection method, the inspection time can be shortened and the inspection cost can be reduced.

  Drum cans can be detected even from the mating edge of the drum can by detecting the cross-sectional defect by injecting SH waves in the direction perpendicular to the plane of the bottom plate from ultrasonic flaw detection means attached to the mating edge on the periphery of the bottom plate. The ultrasonic wave is transmitted to the bottom plate, and the defect portion can be detected. As a result, the cross section of the drum can bottom plate is obtained even in a state where a pile is formed and substantially 1/3 of the side surface is exposed. It was confirmed that the defect portion could be detected from the outer surface side. Similar to the above-described side plate inspection, the bottom plate inspection is used as a preliminary inspection for precise inspection, thereby reducing the inspection time and the inspection cost.

Claims (6)

In the inspection method for detecting a cross-sectional defect portion generated in a drum can from the outer surface side, the drum can inspection method for detecting the defect portion by injecting an SH wave into the side plate surface from an ultrasonic flaw detector on the side plate of the drum can. ,
An attaching step of attaching the side plate ultrasonic probe as an ultrasonic flaw detector to the upper side and / or the lower side of the side plate surface;
A first detection step in which an SH wave is incident on the side plate surface at this mounting position to detect a cross-sectional defect as an echo height;
A second detection step of detecting a cross-sectional defect as an echo height by rotating a side-plate ultrasonic probe around the mounting position and causing an SH wave having a different angle in the incident direction to be incident;
From the direction of the cross-sectional defect portion estimated by the difference in distance to the echo of the cross-sectional defect portion at the same point in the first detection step and the second detection step, and the distance to the defect portion, A drum can inspection method comprising: a first position detection step of detecting a position. A second attachment step of attaching a side plate ultrasonic probe to a side portion facing the attachment position in the attachment step;
An anti-first detection step in which an SH wave is incident on the side plate surface in the opposite direction to the first detection step at this second mounting position to detect a cross-sectional defect as an echo height;
An anti-second detection step of detecting the cross-sectional defect portion as the echo height by rotating the side plate ultrasonic probe around the second attachment position and causing the SH wave having a different angle in the incident direction to be incident;
The cross-sectional defect from the direction of the cross-sectional defect portion inferred from the difference in distance time to the echo of the cross-sectional defect portion at the same point in the anti-first detection step and the anti-second detection step, and the distance to the defect portion A second position detecting step for detecting the position of the part;
The drum can inspection method according to claim 1, further comprising an integrated position detection step of detecting a position of a cross-sectional defect portion from the first position detection step and the second position detection step.   The bottom plate of the drum can is further subjected to a bottom plate inspection in which a SH wave is incident in a direction perpendicular to the bottom plate plane from a bottom plate ultrasonic probe attached to a fitting edge with a side plate on the periphery of the bottom plate to detect a cross-sectional defect portion. The drum inspection method according to claim 1 or 2, wherein A drum can inspection apparatus provided with ultrasonic flaw detection means for detecting a cross-sectional defect portion generated in a drum can from the outer surface side,
As an ultrasonic flaw detector,
A side plate ultrasonic probe for detecting a cross-sectional defect by making SH waves incident in the circumferential direction of the side plate;
The side plate ultrasonic probe is attached to the upper side and / or the lower side of the side plate surface of the drum, and a probe mounting jig capable of rotating the side plate ultrasonic probe at least 1/4 at the mounting position. A drum inspection apparatus comprising the drum can inspection apparatus. As the ultrasonic flaw detection means,
Four side plate ultrasonic probes for detecting a cross-sectional defect portion by causing SH waves to enter the circumferential direction of the side plate in two directions away from each other on the upper side and the lower side on a predetermined circumference of the side plate surface. With the child,
5. The drum can inspection apparatus according to claim 4, further comprising four probe mounting jigs that can rotate by a quarter at each mounting position of the side plate ultrasonic probe.   And a set of bottom plate ultrasonic probes for detecting a cross-sectional defect portion by attaching SH waves to the fitting edge portion of the peripheral edge of the bottom plate of the drum can at an interval and allowing SH waves to be incident in a direction perpendicular to the bottom plate plane. The drum inspection apparatus according to claim 4 or 5, characterized by the above-mentioned.

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