JP3168946U - Ultrasonic flaw detector and penetration width acceptance / rejection determination system - Google Patents

Abstract

An ultrasonic inspection apparatus and a penetration width acceptance / rejection determination system capable of measuring the penetration width of a weld between a steel slab and a U-rib with high accuracy irrespective of welding conditions and the skill of a measurer. I do. An ultrasonic flaw detector (10) for measuring a penetration width (D) of a welded portion (17) formed when a U-rib (16) is fillet-welded to a steel floor slab (15), wherein a surface SV wave for transmission is provided. A vibrator and a receiving surface SV wave vibrator are built in, and mounted on the dual vibrator surface SV wave probe 11 mounted on the steel slab 15 and mounted on the dual vibrator surface SV wave probe 11 And a contact member 12 projecting forward from the front end of the two-element transducer SV wave probe 11 and contacting the U-rib 16. [Selection diagram] Fig. 1

Description

The present invention relates to an ultrasonic flaw detector and a penetration width pass / fail judgment system for measuring the penetration width of a weld formed when a U-rib is fillet welded to a steel deck in a steel bridge structure or the like. About.

In recent years, in an existing steel bridge structure, fatigue cracks have occurred in the welded portion 17 formed when the U-rib 16 (traffic rib) is welded to the steel floor slab 15 and has become a problem (see FIG. 5). This fatigue crack is generated starting from an unwelded portion existing between the back corner of the U rib 16 and the welded portion 17. Therefore, the road bridge specifications specify that the penetration depth (penetration width) of the U rib 16 in the thickness direction is secured to 75% or more of the thickness. However, since it is difficult to confirm the penetration width in the conventional ultrasonic flaw detection test, actual welding is performed under the welding conditions in which a predetermined penetration width (75% or more of the thickness of the U rib) is confirmed in the welding construction test. It is considered that a predetermined penetration width is secured by performing.

On the other hand, the penetration width of the welded portion between the steel slab and U-rib greatly affects the fatigue strength of the relevant part, so it is extremely important to confirm the actual penetration width from the viewpoint of product quality assurance and the like. is there.
Conventionally, for measuring the penetration width of a welded portion, an edge echo method is used to detect an echo from the tip of an unwelded portion (boundary between the welded portion and the unwelded portion) using an oblique probe. Yes. However, in this method, the end echo from the tip of the unwelded portion may not be detected, and a high level of skill is required to evaluate the detected echo, so the measurement accuracy depends on the skill of the technician. The trend was strong.

Therefore, in Patent Document 1, a probe 64 that transmits an SV wave having a refraction angle set within a range of 78 to 88 ° is used as a surface on the bead 63 (welded portion) side of the main plate 61 (steel deck). An ultrasonic wave is transmitted in a state where the tip of the probe 64 is positioned on the position of the start end 63a of the bead 63 (or a position within 3 mm from the start end 63a), and the inside of the bead 63 is expanded by a diffraction phenomenon. An ultrasonic flaw detection method for obtaining a received signal including a reflected echo of a traveling diffracted wave and estimating the size of an unwelded portion 65 is disclosed (see FIG. 6). And according to this method, it is said that it can be carried out without problems even under conditions that cannot be handled by the conventional general oblique flaw detection method.

JP 2010-151501 A

In the ultrasonic flaw detection method described in Patent Document 1, the reflection echo A using the back corner 62a of the upright plate 62 (U-rib) as a reflection source and the reflection echo B using the unwelded tip 65a as a reflection source. From the difference between the distance Y1 from the ultrasonic incident point P of the probe 64 to the back corner 62a of the standing plate 62 and the distance Y2 from the ultrasonic incident point P to the unwelded portion tip 65a, The width of the welded portion 65 is obtained.

However, in the case of the above method, there is a problem that it becomes difficult to specify the reflection echo A and the reflection echo B when the U rib is thinned. For example, if the penetration width is 75% or more of the plate thickness, in the case of a 6 mm thick U-rib, the width of the unwelded portion is 1.5 mm or less, and it is very difficult to distinguish between the reflected echo A and the reflected echo B.
Further, there are cases where echoes from the back corners of the U-rib cannot be obtained, for example, when the route gap is excessive, there is a back-through, or there is a penetration failure.

The present invention has been made in view of such circumstances, and ultrasonic flaw detection capable of measuring the penetration width of the welded portion of the steel slab and the U-rib with high accuracy regardless of welding conditions and the skill of the measurer. An object is to provide an apparatus and a penetration width acceptance / rejection determination system.

In order to achieve the above object, a first device is an ultrasonic flaw detector for measuring a penetration width of a weld formed when a U rib is fillet welded to a steel deck,
A surface SV wave transducer for transmission and a surface SV wave transducer for reception are built in, a dual transducer surface SV wave probe placed on the steel floor slab, and the dual transducer surface SV wave And a contact member that protrudes forward from a front end portion of the dual transducer surface SV wave probe and contacts the U-rib.

Here, the “surface SV wave” is a shear wave (transverse wave) that propagates on the surface of the object and vibrates in a plane orthogonal to the surface. Also, in this specification, the direction in which the surface SV wave is transmitted with the dual transducer surface SV wave probe as the base point is the “front” side, and the opposite direction is the “rear” side. The exposed surface is the “front” surface, and the back side is the “back” surface.

In the first device, the distance from the front end of the dual transducer surface SV wave probe to the tip of the unwelded portion (boundary between the welded portion and the unwelded portion) measured by the dual transducer surface SV wave probe. The echo from the back corner of the U rib is specified to calculate the penetration width of the weld using W and the inclination angle θ of the U rib with respect to the steel deck, measured using an angle gauge. There is no need to do. Therefore, the penetration width of the welded portion between the steel deck and the U rib can be measured with high accuracy regardless of welding conditions and the skill of the measurer. In addition, since the distance Y from the front end of the dual transducer surface SV wave probe to the U-rib is always kept constant by the contact member, a measurement error related to the distance W does not occur.

In the ultrasonic flaw detector according to the first aspect of the invention, the ultrasonic transducer is mounted on the dual transducer surface SV wave probe and measures the distance between the dual transducer surface SV wave probe and the U-rib. A displacement meter may be provided.

In this configuration, the inclination angle θ of the U rib with respect to the steel deck can be calculated using the output of the displacement meter attached to the dual transducer surface SV wave probe. High accuracy can be ensured compared to the case of using a gauge or the like.

In addition, the second device is a system for determining whether or not the penetration width of the welded portion formed when the U rib is fillet welded to the steel deck,
An ultrasonic flaw detector according to a first device, and an ultrasonic flaw detector that determines pass / fail of the penetration width of the weld based on an output signal of the ultrasonic flaw detector,
The ultrasonic flaw detector includes a calculation unit that calculates a penetration width of the welded portion based on the output signal, and a determination unit that determines whether or not the penetration width calculated by the calculation unit is equal to or greater than a predetermined value. It is characterized by that.

In the ultrasonic flaw detector according to the first device, since it is not necessary to specify the echo from the back corner of the U rib, the welded portion of the steel slab and the U rib is welded regardless of welding conditions and the skill of the measurer. The penetration width can be measured with high accuracy.

Further, in the penetration width acceptance / rejection determination system according to the second device, since the ultrasonic flaw detector calculates the penetration width of the welded portion based on the output signal of the ultrasonic flaw detector, it is determined whether or not it is equal to or greater than the specified value. The pass / fail of the penetration width can be confirmed in real time.

1 is a schematic diagram of an ultrasonic flaw detector according to an embodiment of the present invention. The inside of a dual transducer surface SV wave probe is shown, (A) is a side view and (B) is a top view. It is a graph which shows the flaw detection test result by the same ultrasonic flaw detector. It is a block diagram of a penetration width acceptance / rejection determination system according to an embodiment of the present invention. It is a partial detailed view of a steel bridge. It is a schematic diagram for demonstrating the conventional ultrasonic flaw detection inspection method.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

[Ultrasonic flaw detector]
An ultrasonic flaw detector 10 according to an embodiment of the present invention is shown in FIG. The ultrasonic flaw detector 10 includes a two-vibrator surface SV wave probe 11 placed on a steel floor slab 15 and a contact member that protrudes forward from the front end portion of the dual-vibrator surface SV wave probe 11. 12 and a displacement meter 13 fixed on the dual transducer surface SV wave probe 11.

As shown in FIGS. 2A and 2B, the dual transducer surface SV wave probe 11 includes a reception surface SV wave transducer 20 and a transmission surface SV wave transducer 21. . The reception surface SV wave vibrator 20 and the transmission surface SV wave vibrator 21 are installed on different wedges 22, respectively. Each wedge 22 is made of acrylic resin, polyimide resin, or the like, and has a shape in which a rear end portion of a rectangular parallelepiped is cut obliquely. The surface SV wave transducer 20 for reception and the surface SV wave transducer 21 for transmission are installed on a slope 22a formed at the rear end of each wedge 22, and surface SV waves are generated in a direction perpendicular to the slope 22a. Received and sent. The vertical in-plane inclination angle α of the inclined surface 22a with respect to the bottom surface of the wedge 22 is set to about 60 to 70 degrees. Further, the inclination angle β in the horizontal plane of the inclined surface 22a with respect to the front end surface of the wedge 22 is 2 to 6 degrees so that the sound axes S of the surface SV wave transducer 20 for reception and the surface SV wave transducer 21 for transmission intersect. It is graded and is inclined inward.

In a commonly used single element probe, there is a dead zone in the vicinity of the transmission pulse. On the other hand, in the dual transducer probe, the transmission pulse does not appear on the display device, so there is almost no dead zone and the echo from the unwelded portion is easily visible. In the case of a dual transducer probe, near the intersection where the sound axes S intersect, the width of the ultrasonic beam is narrow and the energy is high, so that it is easy to detect an echo from an unwelded portion.

The contact member 12 is a member for keeping the distance Y from the front end of the dual transducer surface SV wave probe 11 to the U rib 16 constant, and a plate material made of acrylic resin or the like is a dual transducer surface SV wave probe. It extends in the horizontal direction from the front end of the touch element 11. The distance Y may be about 20 to 30 mm.

A contact-type displacement meter is used as the displacement meter 13. In the present embodiment, a differential transformer displacement meter having a bottomed cylindrical casing 13b and a rod 13a inserted into the casing 13b and moving back and forth in the axial direction of the casing 13b is used. The rod 13a is located on the front side of the ultrasonic flaw detector 10 and above the contact member 12, and measures the distance A (A> Y) from the front side of the dual transducer surface SV wave probe 11 to the U rib 16.

Next, a method for measuring the penetration width D of the welded portion 17 formed when the U-rib 16 is fillet welded to the steel deck 15 using the ultrasonic flaw detector 10 will be described with reference to FIG. To do. It is assumed that an unwelded portion 18 exists between the corners of the back surface of the U rib 16 and the welded portion 17.
(1) The ultrasonic flaw detector 10 is placed on the steel floor slab 15 with the front side of the ultrasonic flaw detector 10 facing the weld 17 at the rear of the weld portion 17 to be measured.
(2) The ultrasonic flaw detector 10 is advanced toward the welded portion 17, and the tip end portion of the abutting member 12 of the ultrasonic flaw detector 10 is brought into contact with the U rib 16.
(3) In this state, a surface SV wave is transmitted from the dual transducer surface SV wave probe 11 toward the welded portion 17. A part of the surface SV wave propagates from the toe end (rear end) of the welded portion 17 to the inside of the welded portion 17 and is reflected by the unwelded portion tip 19 (rear end of the unwelded portion 18). It becomes. By receiving this reflected echo, the distance W from the front end of the dual transducer surface SV wave probe 11 to the unwelded portion tip 19 is measured. In addition, the distance A from the front end of the dual transducer surface SV wave probe 11 to the U rib 16 is measured by the displacement meter 13.

The angle of inclination of the U rib 16 with respect to the steel deck 15 is θ, the length from the front end of the dual transducer surface SV wave probe 11 to the tip of the contact member 12 is Y, and the ultrasonic flaw detection is performed from the lower surface of the contact member 12 The distance to the bottom of the device 10 is H, and the distance from the central axis of the rod 13a to the lower surface of the contact member 12 is B. Further, the intersection of the virtual line extending the surface of the U-rib 16 and the steel deck 15 is 16a, and the distance between the intersection 16a and the unwelded portion tip 19 is D '.

At this time, the penetration width D of the welded portion 17 is expressed by the following equation.
D = D ′ · sin θ = D ′ · B / √ {(A−Y) ² + B ² } (1)
D ′ is represented by the following equation.
D ′ = W−b = W− (Y−a) = W−Y + a (2)
Here, b is a horizontal distance from the front end of the dual transducer surface SV wave probe 11 to the intersection 16a. Moreover, a is a horizontal distance from the contact point of the contact member 12 and the U rib 16 to the intersection 16a, and can be expressed by the following equation.
a = H / tan θ = H (A−Y) / B (3)

Substituting equation (3) into equation (2),
D ′ = W−Y + H (A−Y) / B (4)
When substituting equation (4) into equation (1),
D = {W−Y + H (A−Y) / B} B / √ {(A−Y) ² + B ² } (5)
It becomes. In the formula (5), W and A are measured by the ultrasonic flaw detector 10 and Y, H, and B are known. Therefore, the penetration width D of the welded portion 17 can be calculated by the equation (5).

[Ultrasonic testing]
In order to verify the effect of the ultrasonic flaw detector 10, a mock-up test body in which a U-rib was welded to a steel slab was manufactured, and an ultrasonic flaw test was conducted. The plate thickness of the U-rib of the mock-up test specimen was 6 mm and 8 mm, and an ultrasonic flaw detection test was performed on each of 40 welds. The material of the U rib was SM490YA, and the material of the steel deck was SM490YB.
The results of the ultrasonic flaw detection test are shown in FIG. The welding width calculated by the ultrasonic flaw detector 10 is shown on the horizontal axis, and the measured values are shown on the vertical axis. About 86% of all the welds are within an error range of ± 0.5 mm, and it was confirmed that the penetration width of the welds can be measured with high accuracy regardless of the thickness of the U-rib.

[Penetration width pass / fail judgment system]
Next, a system for determining whether or not the penetration width D of the welded portion 17 formed when the U-rib 16 is fillet welded to the steel deck 15 will be described.
FIG. 4 shows a block diagram of a penetration width acceptance / rejection determination system 30 according to an embodiment of the present invention. The penetration width acceptance / rejection determination system 30 includes the ultrasonic flaw detector 10 described above and an ultrasonic flaw detector 31 that determines the acceptance / rejection of the penetration width of the welded portion 17 based on an output signal of the ultrasonic flaw detector 10. (See FIG. 4).

The ultrasonic flaw detector 31 includes a transmitter 33 that transmits a pulse to the dual transducer surface SV wave probe 11 (transmission surface SV wave transducer 21), and a dual transducer surface SV wave probe 11 (reception). In addition to the receiving unit 32 that receives the output signal of the surface SV wave vibrator 20), the calculation unit 34 that calculates the penetration width D of the welded part 17 based on the output signal of the receiving unit 32 by the equation (5); And a determination unit 35 that determines whether or not the penetration width D calculated by the calculation unit 34 is equal to or greater than a specified value (for example, 75% or more of the plate thickness of the U rib 16). Further, the ultrasonic flaw detector 31 is inputted with values of Y, H, and B, the plate thickness of the U rib 16 necessary for calculating the penetration width D, and a prescribed value of the penetration width D. An input unit 37 and a display unit 36 for displaying the determination result are provided.

The embodiment of the present invention has been described above. However, the present invention is not limited to the configuration described in the above embodiment, and is within the scope of the matters described in the claims of the utility model registration. Other embodiments and modifications which can be considered in the above are also included. For example, in the above embodiment, a differential transformer type displacement meter is used as the displacement meter, but other displacement meters such as a laser displacement meter may be used.

10: Ultrasonic flaw detector, 11: Dual transducer surface SV wave probe, 12: Contact member, 13: Displacement meter, 13a: Rod, 13b: Housing, 15: Steel deck, 16: U rib, 16a: intersection point, 17: welded portion, 18: unwelded portion, 19: tip of unwelded portion, 20: surface SV wave vibrator for reception, 21: surface SV wave vibrator for transmission, 22: wedge, 22a: Slope, 30: penetration width acceptance / rejection determination system, 31: ultrasonic flaw detector, 32: reception unit, 33: transmission unit, 34: calculation unit, 35: determination unit, 36: display unit, 37: input unit, S: Sound axis

Claims (3)

An ultrasonic flaw detector for measuring a penetration width of a weld formed when a U-rib is welded to a steel slab,
A surface SV wave transducer for transmission and a surface SV wave transducer for reception are built in, a dual transducer surface SV wave probe placed on the steel floor slab, and the dual transducer surface SV wave An ultrasonic flaw detector comprising: an abutment member attached to a probe and protruding forward from a front end portion of the dual transducer surface SV wave probe and abutting on the U-rib. 2. The ultrasonic flaw detector according to claim 1, wherein a displacement meter is attached to the dual transducer surface SV wave probe and measures the distance between the dual transducer surface SV wave probe and the U-rib. An ultrasonic flaw detection apparatus comprising: It is a system for judging pass / fail of the penetration width of a weld formed when a U-rib is welded to a steel floor slab,
The ultrasonic flaw detector according to claim 1 or 2, and an ultrasonic flaw detector that determines pass / fail of the penetration width of the welded portion based on an output signal of the ultrasonic flaw detector,
The ultrasonic flaw detector includes a calculation unit that calculates a penetration width of the welded portion based on the output signal, and a determination unit that determines whether or not the penetration width calculated by the calculation unit is equal to or greater than a predetermined value. A penetration width acceptance / rejection determination system characterized by that.

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