JP2001255312A - Ultrasonic flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detector capable of simply inspecting a wide range without taking time. SOLUTION: The ultrasonic flaw detector is equipped with a water tank 10 in which a liquid 3 is stored, the transmission/reception probe 16 provided in the water tank 10 not only to transmit an ultrasonic wave but also to receive a reflected wave, a decision device 17 for deciding the quality of a part W to be inspected based on the reflected wave received by the transmission/ reception probe 16 and a moving mechanism 19 for relatively moving the part W to be inspected and the transmission/reception probe 16. The transmission/ reception probe 16 is provided at a position where an ultrasonic wave is made to be incident on the part W to be inspected put in the water tank 10 at 90 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector for detecting defects such as gaps formed during welding and blow holes in a welded portion by ultrasonic waves.

[0002]

2. Description of the Related Art If there is a gap in a welded portion, or if there is a space such as a blowhole in a welded portion, the strength of the welded portion is weakened, which causes breakage. Therefore, it is necessary to handle a work having a gap or a blow hole as described above as a defective product. However, the gap or the blow hole of the welded portion cannot be easily seen from the outside. Therefore, as an ultrasonic flaw detector for examining defects such as gaps and blowholes formed in these welded portions, a device described in JP-A-52-18388 is conventionally known.

As shown in FIG. 5, this conventional apparatus includes a transmission probe 1 and a reception probe 2, and the two probes 1 and 2 are filled in a water tank (not shown). It is provided in the liquid 3. The transmission probe 1 emits an ultrasonic wave, and applies the ultrasonic wave to a portion to be inspected. The receiving probe 2 detects a reflected wave. The transmitting probe 1 and the receiving probe 2 are connected to a not-shown determiner. In addition,
Since the ultrasonic waves are totally reflected from the air, the probes 1 and 2 are used in the liquid 3 in order to avoid the influence of the air.

[0004] A work w which is a part to be inspected is installed in the water tank. This work w is a hollow pipe 4
And the annular member 5.
And fixed by welding.
Is annular. And this welded part is a part to be inspected. The transmission probe 1, the reception probe 2, and the workpiece w are firmly fixed by fixing devices (not shown).

[0005] The conventional apparatus as described above inspects the welded portion for defects as follows. First, an ultrasonic wave is emitted from the transmission probe 1 toward the work w. The ultrasonic wave penetrates the liquid 3 and hits the surface a of the pipe 4, where it is refracted at a predetermined angle and enters the pipe 4. The ultrasonic wave entering the pipe 4 hits a boundary surface b with the hollow portion 4a of the pipe 4, and is totally reflected at the boundary surface b. Then, the totally reflected ultrasonic wave passes through the welding portion 6 and reaches the member 5, and is refracted again at the boundary surface c between the member 5 and the liquid 3. The reflected wave refracted at the boundary surface c enters the receiving probe 2 through the liquid 3.

[0006] As described above, the reflected wave is transmitted to the receiving probe 2.
Is detected by the determination unit, it is determined that the work w has no defect. However, when there is a defect in the welded portion, for example, when there is a gap in the welding surface d between the member 4 and the welding portion 6, the ultrasonic wave is reflected by the gap in the direction of the wavy line. When reflected in the dashed line direction, the reflected wave is not detected by the receiving probe 2. Further, even when there is a blow hole or the like in the welded portion 6, since the ultrasonic wave is reflected or scattered by the blow hole,
The reflected wave is not detected by the receiving probe 2. When the reflected wave is not detected by the receiving probe 2 as described above, the determiner determines that the defective product is defective.

As described above, in this conventional example, the presence or absence of a defect in the work w is determined based on whether or not a reflected wave can be detected. Therefore, the positions of the transmission probe 1, the reception probe 2, and the work w are determined. And the direction must be determined accurately. This is because if any of the transmitting probe 1, the receiving probe 2, and the work w is displaced in direction or position, the refraction angle or the reflection angle changes.
As a result, the reflected wave may not be detected, and in such a case, it may be erroneously determined as a defective product even though there is no defect. Therefore, in this conventional example, the angles at which the ultrasonic waves are refracted and the reflection angles at the boundary surfaces a to c are checked in advance, and these refraction angles and reflection angles are calculated, and the transmission probe 1 and the reception probe are calculated. The positions and directions of the tentacles 2 and the work w are determined.

[0008]

In the apparatus using ultrasonic waves as described above, the ultrasonic waves are transmitted through the part to be inspected to determine the presence or absence of a defect in the part to be inspected. It is not possible to inspect the part that is not transmitted. Therefore, when the inspection range is widened, it is necessary to change the position where the ultrasonic wave is transmitted. However, in the above-mentioned conventional example, since the transmitting position of the ultrasonic wave is determined by the position and the direction of the transmitting probe 1, the receiving probe 2, and the work w, the ultrasonic wave is transmitted to widen the investigation range. To change the transmission position, the positions and orientations of these three parts must be changed. In addition, since the positions and directions of the transmission probe 1, the reception probe 2, and the work w are accurately determined by calculating the refraction angle and the reflection angle of the ultrasonic wave, the setting is very difficult. There was a problem that it took time. An object of the present invention is to provide an ultrasonic flaw detector capable of easily inspecting a wide range without any trouble.

[0009]

According to a first aspect of the present invention, there is provided a water tank storing a liquid, a transmission / reception probe provided in the water tank, for transmitting an ultrasonic wave and receiving its reflected wave, and a transmission / reception probe. A determiner that determines the quality of the component to be inspected based on the reflected wave received by the probe, and a moving mechanism that relatively moves the component to be inspected and the transmitting / receiving probe, and the component to be inspected placed in the water tank. In contrast, a transmitting / receiving probe is provided at a position where ultrasonic waves are incident at 90 degrees.

[0010] The second invention is the above-mentioned first invention, wherein:
Equipped with a temperature sensor that detects the temperature of the liquid in the water tank, the determiner corrects the reflected wave received by the transmitting and receiving probe with the temperature of the liquid, and judges the quality of the part to be inspected based on the correction value It is characterized in that it was configured to be.

According to a third aspect, in the first or second aspect, an injection nozzle for injecting a fluid into the water tank is provided,
It is characterized in that dust on the surface of the sending and receiving probe is removed by the fluid from the injection nozzle.

In a fourth aspect based on the first to third aspects, the water tank is provided with a holding portion for holding the component to be inspected, and the holding portion is provided with a sealing member. When the component to be inspected is held by the holding portion, the gap between the component to be inspected and the holding portion is closed by the seal member.

[0013]

1 to 4 show an embodiment of the present invention. In this embodiment, a workpiece W in which a bracket 8 is fixed to one end of a rod 7 by welding is used as a member to be inspected. As shown in FIG. 1 and FIG.
0 is set. As shown in FIG. 3, the water tank 10 has a holding portion 11 on which the rod 7 is mounted on its surface 10a, and a seal member 12 is fixed to the holding portion 11.
The seal member 12 is made of an elastic material such as rubber, and when the rod 7 is held as shown in FIG.

As shown in FIG. 1, a work holding mechanism 13 for holding the rod 7
13 are installed. This work holding mechanism 13, 13
Has rollers 14 attached to its upper part, so that the rods 7 can be rotated and axially moved by these rollers 14. A rotation mechanism (not shown) is attached to the rod 7, and the rod 7 is rotated by the rotation mechanism.

A probe holding mechanism 15 is provided in the water tank 10.
And a probe 16 is provided on the probe holding mechanism 15. The transmitting / receiving probe 16 has a function of emitting an ultrasonic wave and a function of detecting a reflected wave, and is fixed so that the emitted ultrasonic wave is directed at 90 degrees to the work W. When the ultrasonic wave is applied to the work W at 90 degrees in this way, the reflected wave hitting the work W returns to the transmitting / receiving probe 16. Then, the reflected wave detected by the transmission / reception probe 16 is input to the determiner 17 connected via the probe holding mechanism 15.
Further, a temperature sensor 24 is connected to the determination device 17 as shown in FIG. Then, the temperature of the liquid detected by the temperature sensor 24 is input to the determiner 17. The operation of the determination unit 17 will be described later in detail.

As shown in FIG. 2, an injection nozzle 18 is attached to the probe holding mechanism 15 and its injection port is positioned near the surface of the transmission / reception probe 16. By ejecting the liquid from the ejection nozzle 18, dust or the like attached to the surface of the transmission / reception probe 16 is blown off. The probe holding mechanism 15 to which the transmitting / receiving probe 16 and the injection nozzle 18 are attached as described above is attached to the moving mechanism 19, and the transmitting / receiving probe 16 and the workpiece W are moved in the axial direction by the moving mechanism 19. Relative movement is enabled. If the work W is rotated by a rotation mechanism (not shown), the work W and the transmission / reception probe 16 are relatively rotated. The rotating mechanism and the moving mechanism 19 constitute the moving mechanism of the present invention.

On the other hand, reference numeral 20 shown in FIG. 1 denotes a water heater, and a liquid heated to a predetermined temperature by the water heater 20 is supplied into the water tank 10 by a supply device 21. Reference numeral 22 denotes an outer frame that covers the outer periphery of the water tank 10. Liquid spilled from the water tank 10 by the outer frame 22
To prevent it from leaking from above. The fluid accumulated in the outer frame 22 is returned to the water heater 20 by the pump 23.

Next, the operation of this embodiment will be described. First, the rod 7 is supported by the work holding mechanism 13 and the holding portion 11 of the water tank 10, and the work W is set in the apparatus. At this time, the welded portion between the rod 7 and the bracket 8, which is the inspection target portion of the work W, is located in the water tank 10. When the work W is set in the apparatus, the liquid maintained at a predetermined temperature by the water heater 20 is put into the water tank 10 by the supply device 21, and the inspection portion of the work W is immersed in the liquid as shown in FIG. . When the inspection portion of the work is immersed in the liquid in this manner, the water level becomes higher than the holding portion 11. The liquid in the water tank 10 does not leak from the space between the water tank 11 and the water tank 11.

The reason why the liquid kept at the predetermined temperature is put in the water tank 10 as described above is to avoid a sudden change in the temperature of the liquid during the inspection. That is, the work W
Since the temperature of the welded portion between the rod 7 and the bracket 8 is high, if a liquid having a lower temperature than the work W is used, the temperature of the liquid suddenly increases during the inspection. Since the reflected energy of the ultrasonic wave is affected by the temperature of the liquid, it is not preferable that the liquid temperature changes during the inspection as described above. Therefore, by putting a liquid having substantially the same temperature as the work W into the water tank 10, adverse effects due to a rapid temperature rise of the liquid are prevented.

After the liquid is injected into the water tank 10, the work W is rotated by operating a rotation mechanism (not shown).
The reason for rotating the work W in this way is to remove dust and the like attached to the surface of the work W. This is because if the inspection part has dust or the like, accurate inspection of the part cannot be performed. Further, when the dust on the work W is dropped as described above, the dust may settle on the surface of the transmitting and receiving probe 16 below the work W. Also, for some reason, the transmitting and receiving probe 16
There is a case where dust is attached to the surface of the device. Therefore, after the rotation of the work W is stopped, the liquid is ejected from the ejection nozzle 18 so that dust on the surface of the sending and receiving probe 16 is ejected.

Next, an ultrasonic wave is emitted from the transmission / reception probe 16 while rotating the work W at a predetermined rotation speed, and the welded portion is inspected as follows. When the ultrasonic wave is emitted from the transmitting / receiving probe 16, the ultrasonic wave hits the workpiece W at 90 degrees, and the reflected wave returns to the transmitting / receiving probe 16. The determiner 17 takes in the data of the reflected wave detected by the transmission / reception probe 16 and makes a graph as shown in FIG. In this graph, the vertical axis indicates the reflected energy E of the reflected wave, and the horizontal axis indicates the distance from the work surface. A1 and A2 are data of the reflected waves detected by the transmitting and receiving probe 16. .

When the ultrasonic wave is applied to the work W at 90 degrees as described above, the ultrasonic wave is reflected on the surface 25 of the work W as shown in FIG. Then, the reflection energy of the reflected wave appears as A1 shown in FIG. Also, the ultrasonic waves that have hit the surface 25 of the workpiece W
The light enters the work W through the surface 25. Then, when there is a defect such as a cavity or a gap in the welded portion of the work W, that is, when the cavity 26 is located at a distance L1 from the surface of the work W as shown in FIG. The ultrasonic wave is reflected by the cavity 26, and the reflected energy A2 appears at the position of the distance L1 as shown in FIG. Since the reflected wave energy A2 is reflected by the air in the cavity 26, its peak value P also increases to some extent.
If there is no defect in the welded portion, the above reflected energy is not detected.

When the above-described reflected energy A2 is detected due to a defect in the work W, the determiner 17 determines whether the peak value P of the reflected energy A2 is larger or smaller than a predetermined threshold B. That is, if the reflection energy A2 is equal to or smaller than the threshold value B, it is determined that the work W does not have a defect enough to affect the strength. However, as shown in FIG. 4A, when the peak value P of the reflected energy A exceeds a predetermined threshold value B, the process proceeds to the next step, and the data is corrected based on the liquid temperature at the time of inspection. The reason why the temperature of the data exceeding the threshold value B is corrected as described above is that the reflected energy of the ultrasonic wave changes depending on the temperature difference. This is because it cannot always be determined that there is a defect that has an effect on If the temperature-corrected data is equal to or less than a predetermined threshold value, the determiner 17 determines that the work W has no defect. Judge.

After the above inspection is performed on the entire circumference of the rod 7, the moving mechanism 19 is operated to move the transmitting / receiving probe 16 in the axial direction of the work W by a predetermined amount. After moving the work W by the predetermined amount in this way, the work W is rotated again, and the entire circumference of the rod 7 is inspected. By repeating the above-described inspection, the entire range of the welded portion is inspected. Also,
When inspecting while rotating the work W as described above, the work W may be moved in the axial direction by the moving mechanism 19. When the workpiece W and the transmitting / receiving probe 16 are moved in the axial direction in this way, the inspection trajectory becomes spiral,
The entire range can be inspected efficiently. When the workpiece W is moved in the axial direction as described above, the relative movement speed and the relative rotation speed between the workpiece W and the transmission / reception probe 16 are set so that an uninspected portion does not remain on the workpiece W. I am trying to set it.

According to the above embodiment, since the transmitting / receiving probe 16 and the workpiece W can be relatively rotated or relatively moved in the axial direction, the entire range of the welded portion can be inspected. Moreover, since the ultrasonic wave is applied to the work W at 90 degrees and the reflected wave that returns straight is detected, almost all of the relative position between the transmitting / receiving probe 16 and the work W is specified. It does not take time and effort. Therefore, according to this embodiment, a wide range can be easily inspected without any trouble.

[0026]

According to the first aspect, the component to be inspected and the workpiece are relatively moved by the moving mechanism, so that the entire range of the welded portion can be inspected.
Moreover, the ultrasonic wave is applied to the part to be inspected at 90 degrees,
Since the configuration is such that a reflected wave that returns straight is detected, no trouble is required when setting the relative position between the transmitting / receiving probe and the component to be inspected. That is, according to the present invention,
A wide range of inspections can be performed without any hassle.

According to the second aspect, a more accurate inspection can be performed by correcting the temperature of the liquid.
According to the third aspect, dust attached to the surface of the transmitting and receiving probe can be removed, so that the dust is not affected by the dust.
An accurate inspection can be performed. According to the fourth invention,
Since the seal member is configured to close the space between the holding unit and the component to be inspected, it is possible to prevent the liquid from leaking from the inside of the water tank.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment.

FIG. 2 is a side view of FIG.

FIG. 3 is a perspective view of the water tank 10.

FIG. 4 (a) is a diagram illustrating a reflection energy E and a work surface 2;
5 is a graph showing a relationship with distance L from No. 5;
FIG. 4 is a diagram showing a positional relationship between a transmitting / receiving probe 16 and a work W.

FIG. 5 is a plan view showing a conventional example.

[Explanation of symbols]

 W Work (part to be inspected) 3 Liquid 10 Water tank 11 Holder 12 Seal member 16 Transmitter / receiver probe 17 Judgment device 18 Injection nozzle 19 Moving mechanism 24 Temperature sensor

Claims (4)

[Claims] 1. A water tank for storing a liquid, a transmission / reception probe provided in the water tank, for transmitting an ultrasonic wave and receiving a reflected wave thereof, and receiving the ultrasonic wave based on the reflection wave received by the transmission / reception probe. A judgment device for judging the quality of the inspection component, and a moving mechanism for relatively moving the inspection target component and the transmission / reception probe, and ultrasonic waves are applied to the inspection target component placed in the water tank at 90 degrees. An ultrasonic flaw detector wherein a transmission / reception probe is provided at a position where light is incident. 2. A temperature sensor for detecting a temperature of a liquid in a water tank, wherein the determiner detects a reflected wave received by the transmitting / receiving probe,
2. The ultrasonic flaw detector according to claim 1, wherein a correction is made based on a temperature of the liquid, and the quality of the part to be inspected is determined based on the correction value. 3. The apparatus according to claim 1, further comprising an injection nozzle for injecting a fluid into the water tank, wherein dust from the surface of the transmitting and receiving probe is removed by the fluid from the injection nozzle. The ultrasonic flaw detector according to the above. 4. A holding portion for holding a component to be inspected is formed in the water tank, and a seal member is provided on the holding portion. When the component to be inspected is held by the holding portion, the sealing member is used. 4. The structure according to claim 1, wherein a gap between the component to be inspected and the holding portion is closed.
4. The ultrasonic flaw detector according to claim 1.