JPS5826550B2 - Ultrasonic flaw detection method and device using two probes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to nondestructive testing of welded parts of steel structures, etc., and more particularly to an ultrasonic flaw detection method using two probes and an apparatus therefor.

Recently, with the increase in the number of steel frame buildings, welding construction has been widely adopted, and the quality of the construction, that is, the quality of welding, is required to be strictly controlled.

Various types of flaw detection equipment are used for non-destructive testing to find defects in welded parts, but flaw detection equipment that uses ultrasonic waves is particularly excellent, and is especially useful for welding thick steel materials and welding work on site. It is demonstrating its power.

As a flaw detection device that uses ultrasonic waves, a device known as a single probe that both transmits and receives ultrasonic waves has been known for a long time, but this requires advanced techniques and is more prone to defects in welds. There was a drawback that it was not possible to measure the cross-sectional area (the height of the defect in the thickness direction).

Therefore, it is an object of the present invention to provide a flaw detection method and apparatus that can easily and accurately measure flaws in welds without requiring particularly sophisticated techniques, and that can also measure the cross-sectional area of defects in welds. It is something that

EMBODIMENT OF THE INVENTION Hereinafter, an embodiment will be described with reference to the drawings, taking as an example a case where a welded portion between a pillar and a beam is inspected using an ultrasonic flaw detection apparatus using two probes according to the present invention.

In Figure 1 A, 2 ports, A is the column flange (see Figure 2),
B shows the beam 7 flange (base metal), and C shows the welded part.

An ultrasonic flaw detection device (hereinafter referred to as “
It's called a flaw detection device.

) can be roughly divided into the interface T with the beam flange Bq and the welded part C.
A transmitting probe that emits an ultrasonic beam toward the boundary surface T, a receiving probe that receives the ultrasonic beam reflected by the boundary surface T, and each side of the flange B that holds the transmitting and receiving probes. It consists of a jig that moves equidistant distances in opposite directions along the

First, the jig will be explained.

In the figure, reference numeral 1 denotes a surface plate, and the surface plate 1 has a central axis 2 and a beam flange B, that is, a magnet for removably fixing it on the base material.

3a. 3b is a first link having a hole in the center through which the central axis 2 of the surface plate 1 passes; 3c, 3d, 3e, and 3f are second links pivotally connected to the tips of the first links 3a, 3b by a shaft. The tips of the second links 3 c t 3 d, 3 e, and 3 f have holes through which fixed shafts of a transmitting probe and a receiving probe, which will be described later, pass.

4at4d are springs that act to press each probe against each side of the beam flange B when the probe is attached to the jig.

Next, the probe will be explained.

Reference numeral 5 indicates a transmitting probe which has a width approximately equal to the thickness of the beam flange B and is placed on one side of the beam flange B and generates an ultrasonic beam toward the boundary surface T. Similarly, 7 indicates the beam flange. The receiving probe has a width approximately equal to the thickness of beam B, is placed on the other side of the beam flange B, and receives the ultrasonic beam reflected by the boundary surface T, and each probe 5, 7
Both have a normal refraction angle of 45°.

Further, each probe 5, 7 is covered with a fixed shaft 6.8, and these shafts 6, 8 are connected to the second link 3c of the aforementioned jig.
, 3d and 3e.

Each probe 5, 7 is attached to a jig by passing it through the hole at the tip of 3f.

With each probe 5, 7 attached to the jig, each probe 5, 7 is connected to the beam flange,
are moved equidistantly along each side of the diagonal B in opposite directions.

Next, a method for detecting flaws in the weld C between the column A and the beam B using the apparatus having the above-mentioned configuration will be described.

It is assumed that both the transmitting probe and the receiving probe have a refraction angle of 45°.

First, as shown in Figure 2 A, the center point is a point that is half the width of the beam flange B and corresponds to the distance of half the width of the beam flange B from the welding part C, and the center of the jig is set at this point. Fix shaft 2.

In addition, in order to set the flaw detection sensitivity and the beam path for detecting defect echoes, as shown in FIG. Set the sensitivity of the ultrasonic flaw detector and mark the detection position of defect echoes.

Next, attach the transmitting probe 5 and the receiving probe 7 to the jig (the fixed shafts 6, 8 of each probe 5, 7 are connected to the second link 3c of the jig).
, 3d, 3e, and 3f.

), the ultrasonic waves are propagated into the steel material through a couplant such as glycerin.

In order to detect flaws on the entire surface of the welded part C, a jig is used to connect the transmitting and receiving probes 5,
7 is scanned backwards and forwards between ■→■→■.

Note that t indicates a welding defect.

The detected defect echo height is measured, and the probe 5,
Measure and record the change in defect echo height due to the movement of 7.

Then, the heights of defect echoes detected from the entire area of the weld are integrated.

On the other hand, create a comparison specimen with a known defect cross-sectional area, clarify the relationship between the defect cross-sectional area and the defect echo height, and compare the integrated value of the defect echo height of the measured weld with a known defect cross-sectional area. The defect cross-sectional area of the weld is estimated by comparing the integrated value of the defect echo height of the test piece.

An experiment was conducted to detect defects in welded parts using the flaw detection method and apparatus according to the present invention, and the results are shown in FIG.

(1) For the purpose of the experiment, the cross-sectional defect rate (defect height/plate thickness) of the groove welded joint is estimated by comparing it with the measured value of a control specimen.

(2) Shape of comparative test piece Figure 4 A 2nd street.

(3) Shape of K groove weld joint Figure 5 A 2nd street.

(4) Experimental Results In FIG. 6, the vertical axis shows the reflected echo height, and the horizontal axis shows the cross-sectional defect rate in logarithm.

The reflected echo when the transmitting and receiving probes face each other from the side of the comparison test piece is defined as OdB, and the height of the reflected echo of each comparison test piece is compared with that and plotted with ■ in the figure.

Since there is a correlation between this reflected echo and the cross-sectional defect rate, this is shown by a linear relationship in the figure based on actual measurements.

Next, the height of the defect reflection echo of the welded joint test piece was measured in the same manner and indicated by an x mark on the above-mentioned straight line.

By drawing a perpendicular line from this intersection, the cross-sectional defect rate can be estimated.

The following table shows a comparison between the actual measured value of the cross-sectional defect rate and the amount estimated by this flaw detection device.

(5) Conclusion The cross-sectional defect rate can be evaluated with high accuracy using this flaw detection method and device.

Furthermore, by scanning back and forth to cover the entire weld line and integrating the results, the defect cross-sectional area of the weld joint can be estimated.

Furthermore, it is not necessary to produce a comparison test piece for each inspection.

Figure 7 A2 shows another embodiment of the present invention; the previous embodiment used a link mechanism as the jig, but the jig of this embodiment uses a slide mechanism. .

That is, 9 is an outer frame that is fitted into the center shaft 2 of the surface plate 1 and rotates, and 10a and 10b are slide rods that have a long hole through which the center shaft 2 passes, and that slide inside the outer frame 9. It is supposed to be done.

Therefore, like a jig using a link mechanism, the transmitting probe 5 and the receiving probe 7 can be moved equidistantly in opposite directions along each side of the beam flange B.

The advantages of the flaw detection method and apparatus of the present invention are listed below.

(1) Since the defect cross-sectional area can be measured with high precision, the influence of welding defects on joint performance can be accurately grasped.

(2) Since the entire welded joint can be detected by one back-and-forth scan, inspection time can be significantly shortened.

(3) Since it is very easy to distinguish defective echoes, inspectors do not need special skills, and the inspection method is simple, making automatic flaw detection possible.

(4) As for the probes and the like used, those generally sold can be used as they are, and the jig can be easily manufactured.

(5) Since steel materials used for construction steel frames usually have a certain width and the flaw detection surface is the side surface, it is possible to inspect many welded parts.

(6) Since the flaw detection surface is the side surface, flaw detection is not affected by spatter on the upper surface of the flange or the cover plate.

[Brief explanation of drawings]

FIG. 1A shows a flaw detection apparatus according to the present invention, with A being a plan view and A being a side view. FIGS. 2A and 2B show a method of detecting flaws at a welded portion between a column flange' and a reflange using the flaw detection apparatus according to the present invention, where A is a plan view and FIG. 2A is a side view. FIG. 3 is a diagram in which a transmitting probe and a receiving probe are set so as to face each other on the sides of the beam flange in order to set the flaw detection sensitivity and the beam path length for detecting defect echoes. FIG. 4A2 is a diagram showing the shape of a comparison test piece used in an experiment using the flaw detection method according to the present invention. Figure 5A2 is a diagram similarly showing the shape of the groove weld joint. FIG. 6 is a graph showing the experimental results. FIG. 7A shows another embodiment of the flaw detection apparatus according to the present invention, where A is a plan view and FIG. 7A is a side view. A: Column flange, B: Beam flange, C: Welded part, T: Boundary surface, t
...Defect, 1...Surface plate, 2...
・Central axis, 3a to 3f...Link, 4at4b
... Spring, 5 ... Transmission probe, 6 ...
...Transmission probe fixed axis, 7...Reception probe, 8...Reception probe fixed axis, 9...Outer frame, 10a, 10b ...Sliding rod.

Claims (1)

[Claims] 1. A transmitting probe that transmits an ultrasonic beam and a receiving probe that receives the ultrasonic beam are arranged on each side of a welded base material, and the transmitting probe is attached to the base material. The ultrasonic beam is transmitted at a fixed angle toward the interface with the weld, the receiving probe receives the ultrasonic beam reflected by the weld, and the transmitting probe is moved to reflect the ultrasonic beam. The two-probe probe is characterized in that the receiving probe moves the side surface an equal distance in the opposite direction to the transmitting probe and receives data, thereby measuring the defect cross-sectional area of the weld. Ultrasonic flaw detection method used. 2. A transmitting probe that has a width approximately equal to the thickness of the base material and is placed on one side of the base material and transmits an ultrasonic beam toward the interface between the base metal and the weld, and a A receiving probe, which has a width approximately equal to the thickness and is placed on the other side of the base material and receives the ultrasonic beam reflected by the boundary surface, and a transmitting probe and a receiving probe are placed on the other side of the base material. It consists of a jig that moves equidistantly in opposite directions along each side, and the central axis of the jig is fixed on the surface at the center of the width of the flange. Ultrasonic flaw detection equipment.