JPH11326288A - Probe hold mechanism for use in tube inner face - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently bring ultrasonic waves into a tube by enhancing contact properties between an ultrasonic probe and an inner face of the tube. SOLUTION: This probe hold mechanism has one short arm 11 and two long arms 12 set at a driving shaft 10. These short arm 11 and long arms 12 are arranged within the same plane perpendicular to the driving shaft 10 at equal intervals (interval of 120 deg.) in a circumferential direction. The short arm 11 is provided with an ultrasonic probe 13 via a sliding member 14, a yoke 15, etc. A spring 21 is set in the short arm 11. The ultrasonic probe 13 is always pressed by the spring 21 towards an inner face of a CRD (control rod drive mechanism) housing 4. A contact element 25 is mounted to the long arm 12. A spring is set also inside the long arm 12, so that the contact element 25 is always pressed to the inner face of the CRD housing 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe holding mechanism for a tube inner surface, and more particularly to an ultrasonic probe inserted into a tube when performing an ultrasonic inspection test on the tube inner surface. The present invention relates to a probe holding mechanism for a tube inner surface.

[0002]

2. Description of the Related Art In a nuclear power plant or the like, an ultrasonic inspection test is used for inspection of a reactor pressure vessel. For example, as shown in FIG. 8, the reactor pressure vessel 1 includes an upper mirror 2 and a body 3, and a flange 2 </ b> A of the upper mirror 2 and a flange 3 </ b> A of the body 3 are joined and integrated. Also,
A lower mirror 3B is attached to a lower portion of the body 3 by welding, and a housing (hereinafter, referred to as a CRD housing) 4 of a control rod driving mechanism is provided on the lower mirror 3B.

FIG. 9 is an enlarged view of a portion A where the CRD housing 4 is provided. As shown in FIG. 9, a stub (hereinafter, CRD stub) 5 of a control rod drive mechanism is attached to the lower mirror 3B by welding 6 in parallel to the axial direction of the reactor pressure vessel, and the inside of the CRD stub 5 is provided. The CRD housing 4 is inserted through and fixed.

Conventionally, an ultrasonic test for such an inner surface of a CRD housing has been performed by holding an ultrasonic probe in a hand and pressing it against the inner surface of the CRD housing. However, when performing the operation while holding the ultrasonic probe in hand, C
The ultrasonic flaw detection test can be performed only up to the point where the inside of the RD housing can be reached, and there is a disadvantage that the flaw detection range is narrowed. In addition, since it is limited to a case where a person can approach, it becomes impossible to perform an ultrasonic inspection test on the inner surface of the CRD housing at the time of maintenance after operation of the plant in a nuclear power plant.

Therefore, there is known a method of performing an ultrasonic flaw detection test by attaching an ultrasonic probe to the tip of a drive shaft of a jig and remotely controlling rotation and axial movement of the drive shaft. ing. According to this, by extending the drive shaft, it is possible to detect a flaw in a wide area in the CRD housing, and since it is not necessary for a person to approach the subject, even when performing maintenance after operation of the plant, the inner surface of the CRD housing can be superposed. An ultrasonic test can be performed.

[0006]

However, in the above-mentioned prior art, since the ultrasonic probe is simply attached directly to the tip of the drive shaft, if the drive shaft is lengthened, the center of the drive shaft tends to shift. If the center is shifted, there is a problem that the contact between the ultrasonic probe and the inner surface of the CRD housing is deteriorated.

When the inner surface of the CRD housing is rough, a gap is easily formed between the ultrasonic probe and the inner surface of the CRD housing when the ultrasonic probe is moved.
When such a gap occurs, there is also a problem that it is difficult for the ultrasonic waves to enter the CRD housing body.

An object of the present invention is to provide a tube inner surface probe holding mechanism capable of efficiently causing ultrasonic waves to enter a tube main body by enhancing the contact between the ultrasonic probe and the tube inner surface. That is.

[0009]

In order to achieve the above object, an invention according to claim 1 is provided with a drive shaft inserted into a pipe along an axial direction, and attached to a tip end of the drive shaft, At least three arms provided at equal intervals in the circumferential direction in the same plane perpendicular to the axial direction, and one end of one of the arms is provided with an ultrasonic probe for ultrasonically flaw detecting the inner surface of the tube. An ultrasonic probe is attached, and a contact for contacting the inner surface of the tube is provided at the end of each arm other than the ultrasonic probe is attached, and the ultrasonic probe and each of the contacts Is provided on the inner surface of the tube with the same force.

According to the above arrangement, since the ultrasonic probe and the respective contacts are pressed against the inner surface of the tube with the same force by the pressing means, the drive shaft is always located substantially at the center of the tube. In addition, the contact between the ultrasonic probe and the inner surface of the tube can be improved. Also, since the ultrasonic probe is always pressed against the inner surface of the tube by the pressing means, even if the inner surface shape of the tube is rough, the ultrasonic probe can be moved following the inner surface shape, The generation of a gap between the ultrasonic probe and the inner surface of the tube can be prevented.

According to a second aspect of the present invention, in the first aspect, the pressing means is provided with an adjusting mechanism for adjusting a pressing force. If such an adjusting mechanism is provided, the adjusting means adjusts the pressing force of the pressing means even if the driving shaft is displaced from the center of the pipe due to an imbalance in the pressing force of the pressing means. Thereby, the drive shaft can be easily positioned substantially at the center of the tube. Incidentally, a spring can be used as the pressing means.

According to a fourth aspect of the present invention, in the first aspect, the ultrasonic probe is provided at a tip end of the arm provided with the ultrasonic probe along a circumferential direction of the inner surface of the tube. It is characterized in that a support mechanism for swingably supporting in a plane and a plane including the drive shaft is provided. If such a support mechanism is provided, the ultrasonic probe can be moved when moving the ultrasonic probe in the circumferential direction along the inner surface of the tube or in the axial direction of the tube. The movement between the pipe and the inner surface of the pipe is smoothed out.

According to a fifth aspect of the present invention, in the first aspect, a water layer holding means for forming a gap between the ultrasonic probe and the inner surface of the tube and holding a water layer in the gap is provided. It is characterized by being provided. According to such a configuration, since the ultrasonic waves from the ultrasonic probe enter the tube main body via the water layer, the incident efficiency of the ultrasonic waves can be improved.

According to a sixth aspect of the present invention, in the fifth aspect, the water layer holding means is detachably provided on the ultrasonic probe. According to such a configuration, since the water layer holding means can be easily removed from the ultrasonic probe, by attaching another type of water layer holding means to the ultrasonic probe, the ultrasonic probe The gap between the tube and the inner surface of the tube can be changed.

According to a seventh aspect of the present invention, in the first aspect, a proximity sensor for detecting a distance between the ultrasonic probe and the inner surface of the tube is provided, and a pressing force of the pressing means is determined by the proximity sensor. Is controlled on the basis of the above signal. According to this configuration, when the balance of the pressing force of the pressing means is disturbed and the drive shaft is displaced from the center of the tube, the fact is detected by the proximity sensor, and the pressing means detects the proximity sensor. The pressing force is automatically controlled based on the signal from the controller.
As a result, the drive shaft can always be located substantially at the center of the tube. In this case, it is convenient to use an air cylinder as the pressing means.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a state in which an ultrasonic flaw detector equipped with a tube inner surface probe holding mechanism according to the present invention detects the inner surface of a CRD housing. In FIG. 1, 3A is a lower mirror, 4 is a CRD housing, 5 is a CRD stub, and 6 is a weld. The drive shaft 10 is inserted into the CRD housing 4. The drive shaft 10 is driven by a drive device (not shown) to rotate around the axis as shown by an arrow B, and reciprocate along the axial direction as shown by an arrow C. One short arm 1 is provided at the tip of the drive shaft 10.
One and two long arms 12 are provided, and an ultrasonic probe 13 is attached to the tip of the short arm 11. This will be described with reference to FIGS.

FIG. 2 is a sectional view taken along the line DD in FIG. 1 (the CRD stub 5 and the like are omitted), and FIG. 3 is an enlarged side view of the vicinity where the ultrasonic probe 13 is attached. The one short arm 11 and the two long arms 12 are provided at equal intervals in the circumferential direction (120 ° intervals) in the same plane perpendicular to the drive shaft 10. The short arm 11 has a rectangular cylindrical shape, and a rectangular sliding member 14 is fitted on the open end side. The sliding member 14 is slidable in the direction of arrow E with respect to the short arm 11.

A flat plate 16 to which a yoke 15 is attached is fixed to the sliding member 14. The yoke 15 is formed in a U-shape, and a probe support frame 18 is swingably attached to both ends thereof via pins 17. The probe support frame 18 has a shape in which a belt-like member is bent into a substantially quadrangular shape, and the ultrasonic probe 13 disposed therein is provided.
Are swingably supported by pins 19 provided above and below. Thus, the ultrasonic probe 13 can swing in a plane along the circumferential direction of the inner surface of the CRD housing 4 and in a plane including the drive shaft 10. Further, the ultrasonic probe 1
A plate spring 20 is provided between the plate 3 and the flat plate 16, and the ultrasonic probe 13 is CR
It is urged toward the inside of the D housing 4.

A spring 21 is provided inside the short arm 11 (see FIG. 2, FIG. 3 omits the spring 21). The spring 21 is a compression spring, and
To the inner surface of the CRD housing 4. Spring 21
Is transmitted to the ultrasonic probe 13 via the yoke 15 and the probe support frame 18, whereby the ultrasonic probe 13 is constantly pressed against the inner surface of the CRD housing 4.

A spring 21 is provided inside the short arm 11.
The movable plate 22 is provided on the opposite side of the sliding member 14 with the. The movable plate 21 is movable in the direction of arrow E similarly to the sliding member 14, and has a screw hole 22A formed in the center thereof. On the other hand, a hole 14A is formed in the center of the sliding member 14, and an adjustment shaft 23 is provided in the hole 14A.
One side (the left side in FIG. 3) of the adjustment shaft 23 is supported by a bearing (not shown) fixed to the sliding member 14.
Is rotatable. A screw 23A is formed on the other side (the right side in FIG. 3) of the adjustment shaft 23, and the screw 23A is screwed with a screw in a screw hole 22A formed in the movable plate 22. Further, an operation shaft 24 is provided directly on the adjustment shaft 23, and an operation knob 24A is fixed to one end of the operation shaft 24, and a bevel gear 24B is fixed to the other end. A bevel gear 23B is fixed to an intermediate portion of the adjustment shaft 23.
Is engaged with the bevel gear 24B of the operation shaft 24.

The two long arms 12 have a rectangular cylindrical shape as shown in FIG. 2, and the contacts 25 are respectively fitted to the open ends thereof. The contact 25 is slidable in the directions of arrows F and G. The contact 25 has a rectangular shape at the part fitted to the long arm 12, but has a spherical tip at the tip, and the spherical part is in contact with the inner surface of the CRD housing 4. Inside the long arm 12, the short arm 11
As in the case of (1), the spring 21, the movable plate 22, the adjustment shaft 23, the operation shaft 24, and the like are provided, and the contact 25 is constantly pressed against the inner surface of the CRD housing 4. In FIG. 2, only the operation knob 24A of the operation shaft 24 is shown.

The long arm 12 has a long hole 12A. A stopper 25A provided integrally with the contact 25 is engaged with the elongated hole 12A, thereby restricting the sliding range of the contact 25. Since the stopper 25A is engaged with the elongated hole 12A,
Even when the drive shaft 10 is pulled out of the CRD housing 4, the contact 25 does not come off the long arm 12.
Although not shown in the figure, such a long hole and a stopper are also provided on the short arm 11 side, the sliding range of the sliding member 14 is restricted, and when the drive shaft 10 is pulled out from the CRD housing 4, The ultrasonic probe 13 does not come off the short arm 11.

In the present embodiment, the spring 21 serves as a pressing means, the movable plate 22, the adjusting shaft 23 and the operating shaft 24 and the like serve as an adjusting mechanism, and the yoke 15 and the probe support frame 18 and the like serve as a supporting mechanism. Make up.

Next, the operation of the tube inner surface probe holding mechanism having the above structure will be described.

First, when performing an ultrasonic inspection test on the inner surface of the CRD housing 4, the short arm 11 and the long arm 12 are inserted into the CRD housing 4 by inserting the tip of the drive shaft 10 into the CRD housing 4. . At this time, the tip of the long arm 12 is formed in a spherical shape, and the ultrasonic probe 13 at the tip of the short arm 11 can swing about the pin 17 at the tip of the yoke 15.
The first and long arms 12 can be easily inserted into the CRD housing 4.

When inserting the short arm 11 and the long arm 12 into the CRD housing 4, if the center of the drive shaft 10 is displaced from the CRD housing 4, the operation knob 24
A is rotated. This rotation operation can be performed directly by hand, or can be performed by remote control using a robot. By rotating the operation knob 24A, the bevel gear 24B,
The adjustment shaft 23 rotates via 23B, whereby the movable plate 22 screwed to the screw 23A of the adjustment shaft 23 moves. When the movable plate 22 moves, the gap between the movable plate 22 and the sliding member 14 changes, so that the urging force of the spring 21 disposed in the gap changes.

In practice, the operation knob on the short arm 11 and the two operation knobs 24A on the long arm 12 are rotated so that the drive shaft 10 is located substantially at the center of the CRD housing 4. When the drive shaft 10 is located substantially at the center of the CRD housing 4, the urging force of the spring 21 on the short arm 11 and the urging force of the springs 21 on the two long arms 12 are the same and balanced. It is.

If the drive shaft 10 can be positioned substantially at the center of the CRD housing 4 in this manner, the ultrasonic wave can be obtained regardless of whether the drive shaft 10 is rotated in the direction B in FIG. There is no gap between the probe 13 and the inner surface of the CRD housing 4, and the ultrasonic waves from the ultrasonic probe 13 can be efficiently incident on the main body of the CRD housing 4.

Since the ultrasonic probe 13 is always urged toward the inner surface of the CRD housing 4, even if the inner surface of the CRD housing 4 is rough, the ultrasonic probe 13 follows the inner surface shape. Can be moved, and the generation of a gap between the ultrasonic probe 13 and the inner surface of the CRD housing 4 can be prevented.

(Embodiment 2) FIGS. 4 and 5 show a tube inner surface probe holding mechanism according to Embodiment 2 of the present invention. FIG. 4 is a plan view and FIG. 5 is a side view. I have. A feature of the present embodiment is that a probe shoe 31 having wheels 30 is detachably attached to the tip of the ultrasonic probe 13. The periphery of the probe shoe 31 is C
The RD housing 4 is formed in a cylindrical surface along the inner surface, and a water hose connector 32 is provided at an upper portion. The probe shoe 31 is attached so that its periphery slightly protrudes from the surface of the ultrasonic probe 13,
When inserted into the RD housing 4, a slight gap is formed between the inner surface of the CRD housing 4 and the surface of the ultrasonic probe 13.

The configuration is the same as that of the first embodiment except that the probe 31 is attached. In the present embodiment, the probe shoe 31 constitutes a water layer holding unit.

According to the present embodiment, when an ultrasonic test is performed on the inner surface of the CRD housing 4, the water hose connector 32 is inserted into a small gap between the inner surface of the CRD housing 4 and the ultrasonic probe 13. Supply more water. Since the periphery of the probe shoe 31 slightly protrudes from the surface of the ultrasonic probe 13, if the probe shoe 31 is in close contact with the inner surface of the CRD housing 4, the ultrasonic probe will A water layer is formed in the gap between the surfaces of the child 13. When such a water layer is formed, the ultrasonic probe 13 is in a state of being immersed in water, so that the ultrasonic waves from the ultrasonic probe 13 can be efficiently incident on the main body of the CRD housing 4. it can.

In the present embodiment, the probe shoe 31
Has the wheels 30, the probe shoe 31 does not get caught when the drive shaft 10 is moved in the axial direction along the CRD housing 4, and the movement of the ultrasonic probe 13 is controlled. Can be smooth. Further, since the probe shoe 31 is detachable, it is possible to remove it and attach another type of probe shoe. For example, if probe shoes having different protrusion amounts from the surface of the ultrasonic probe 13 are attached, the ultrasonic probe 13
The gap between the CRD housing 4 and the inner surface of the CRD housing 4 can be changed.

4 and 5, reference numeral 11A denotes a long hole formed in the short arm 11, and 14B denotes a stopper engaged with the long hole 11A. The stopper 14B is formed integrally with the sliding member 14.

(Embodiment 3) FIGS. 6 and 7 show a tube inner surface probe holding mechanism according to Embodiment 3 of the present invention. FIG. 4 is a plan view, and FIG. 5 is a side view. I have. The feature of this embodiment is that the short arm 11 and the long arm 1
2 and an air cylinder 40 inside the CR
A proximity sensor 41 that detects the distance between the inner surface of the D housing 4 and the ultrasonic probe 13 and a proximity sensor 42 that detects the distance between the inner surface of the CRD housing 4 and the contact 25 are provided. In the present embodiment, the air cylinder 40 constitutes a pressing unit.

In the short arm 11, the air cylinder 40 presses the sliding member 14 against the inner surface of the CRD housing 4, and presses the ultrasonic probe 13 against the inner surface of the CRD housing 4. In the long arm 12, the air cylinder 40 presses the contact 25 against the inner surface of the CRD housing 4 and presses the contact 25 against the inner surface of the CRD housing 4. The proximity sensors 41 are attached to both sides of the yoke 15, and the proximity sensors 42 are attached to the distal end of the long arm 12.

The detection signals from the proximity sensors 41 and 42 are
It is taken in by a control device (not shown). Then, the control device calculates the distance between the ultrasonic probe 13 and the inner surface of the CRD housing 4 and the distance between the contact 25 and the inner surface of the CRD housing 4 based on the detection signals from the proximity sensors 41 and 42. Based on the calculation result, the amount of air supplied to each air cylinder 40 is adjusted so that the drive shaft 10 is controlled to be located substantially at the center of the CRD housing 4.

According to the present embodiment, the proximity sensor 41,
Since the position of the drive shaft 10 is automatically controlled to the substantially center position of the CRD housing 4 based on the detection signal from the control signal 42, the trouble for position control can be saved.

In this embodiment, a water layer is formed between the inner surface of the CRD housing 4 and the ultrasonic probe 13 by providing a probe shoe as in the second embodiment. Alternatively, ultrasonic waves may be incident on the CRD housing 4 main body through the water layer.

Further, in the above-described first to third embodiments, the case where the number of the short arms 11 is one and the number of the long arms 12 is two has been described as an example. However, the present invention is not limited to this. 12 may be three or more. Further, the tube inner surface probe holding mechanism of the present invention can be applied not only to an ultrasonic inspection test but also to an element for inspecting a state of a tube inner surface.

[0041]

As described above, according to the present invention,
When performing an ultrasonic inspection test from the inner surface of the tube, the ultrasonic probe is always in close contact with the inner surface of the tube, so the incidence of ultrasonic waves on the tube body is constant, and the accuracy and reproducibility of the ultrasonic inspection test are improved. Can be improved.

Further, since the water layer holding means for holding the water layer is provided in the gap between the ultrasonic probe and the inner surface of the tube, the ultrasonic probe is locally immersed in water. Therefore, even if the inner surface of the tube is rough, an ultrasonic inspection test can be performed with high accuracy.

Further, conventionally, it has been confirmed that the ultrasonic probe has come into contact with the inner surface of the tube only by the reflected echo of the ultrasonic wave. However, by providing a proximity sensor, the ultrasonic probe and the inner surface of the tube can be connected to each other. The distance can be easily sensed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state where an inner surface of a CRD housing is flaw-detected by an ultrasonic flaw detector equipped with a tube inner surface probe holding mechanism according to a first embodiment of the present invention.

FIG. 2 is an arrow view along the line DD in FIG. 1;

FIG. 3 is an enlarged side view of the vicinity of FIG. 2 where an ultrasonic probe is attached.

FIG. 4 is a main part plan view of a tube inner surface probe holding mechanism according to a second embodiment of the present invention.

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a plan view of a tube inner surface probe holding mechanism according to a third embodiment of the present invention.

FIG. 7 is an enlarged side view of the vicinity of FIG. 6 where an ultrasonic probe is attached.

FIG. 8 is a schematic configuration diagram of a reactor pressure vessel.

FIG. 9 is an enlarged sectional view of a part A in FIG. 8;

[Explanation of symbols]

 Reference Signs List 4 CRD housing 10 Drive shaft 11 Short arm 12 Long arm 13 Ultrasonic probe 14 Sliding member 15 Yoke 18 Probe support frame 21 Spring 22 Movable plate 23 Adjusting shaft 24 Operating shaft 25 Contact 30 Wheel 31 Probe Shoe 32 Connector for water hose 40 Air cylinder 41, 42 Proximity sensor

Claims (8)

[Claims] 1. A drive shaft inserted into a pipe along an axial direction, and at least three drive shafts attached to the distal end of the drive shaft and provided at equal intervals in a circumferential direction on the same plane perpendicular to the axial direction.
And an ultrasonic probe for ultrasonically flaw-detecting the inner surface of the tube is attached to the tip of one of the arms, and other than the ultrasonic probe attached. Each arm tip is provided with a contact for contacting the inner surface of the tube, and a pressing means for pressing the ultrasonic probe and each contact against the inner surface of the tube with an equal force is provided. Characteristic probe holding mechanism for tube inner surface. 2. The probe inner tube holding mechanism according to claim 1, wherein the pressing means is provided with an adjusting mechanism for adjusting a pressing force. Holding mechanism. 3. The tube inner surface probe holding mechanism according to claim 1, wherein said pressing means is a spring. 4. The probe holding mechanism for a tube inner surface according to claim 1, wherein the ultrasonic probe is provided at an end of an arm on which the ultrasonic probe is provided with a circumference of the tube inner surface. A tube inner surface probe holding mechanism, comprising: a support mechanism for swingably supporting a plane along a direction and a plane including the drive shaft. 5. The probe holding mechanism for a tube inner surface according to claim 1, wherein a gap is formed between the ultrasonic probe and the tube inner surface, and the gap holds a water layer. A tube inner surface probe holding mechanism, wherein a layer holding means is provided. 6. The tube inner surface holding mechanism according to claim 5, wherein said water layer holding means is detachably provided on said ultrasonic probe. Probe holding mechanism. 7. The probe holding mechanism for a tube inner surface according to claim 1, further comprising a proximity sensor for detecting a distance between the ultrasonic probe and the tube inner surface, wherein a pressing force of the pressing means is smaller. A tube inner surface probe holding mechanism, which is controlled based on a signal from the proximity sensor. 8. The probe holding mechanism for a tube inner surface according to claim 1, wherein the pressing means is an air cylinder.