JPH07103953A - Ultrasonic flaw detection and inspection apparatus for tubular object - Google Patents

Abstract

PURPOSE:To perform the ultrasonic flaw detection and inspection of a tubular object with good efficiency. CONSTITUTION:The ultrasonic flaw detection and inspection apparatus 100 of a tubular object is provided with a guide rod 30 which guides the movement of a flaw detection head 20, with a guide-rod support means 40 by which the oxial line of the guide rod 30 is made to coincide with the axial line of a tubular part by a plurality of rotating bodies turning and moving on the inner circumferential face of the tubular part and which supports the guide rod so as to be freely turned and so as to be freely displaced in the direction of the axial line and with a guide-rod rotation means 50 which turns the guide rod 30 around the axial line of the tubular part. In addition, the flaw detection and inspection apparatus is provided with a flaw-detection-head drive means 60 which moves the flaw detection head 20 to the direction of the axial line of the guide rod 30 and with a seal flange which is coupled so as to be freely tilted and moved and so as to be freely turned with reference to the guide rod 30, which is fixed to the tubular part and which hermetically seals flaw- detection water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for ultrasonic flaw detection of a tubular body, and more specifically, it fills the interior of the tubular body with flaw detection water and separates the flaw detection head from the inner peripheral surface of the tubular body. The present invention relates to an ultrasonic flaw detection inspection device of a type in which the inside of a tubular body is moved to perform flaw detection in a state.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic flaw detector for ultrasonically cracking a metallic tubular body has been used, but the inventors of the present invention previously described a tubular body as shown in FIG. A non-destructive inspection device was invented and filed as Japanese Patent Application No. 2-333744. This nondestructive inspection device is inserted into the inside of the tubular body P to detect flaws on the tube wall of the tubular body P, and is arranged at intervals in the longitudinal direction of the tubular body P. A pair of support members 2 and 3, a pair of guide rods 4 mounted between these support members, a guide rod 4 slidably mounted on the guide rods 4, and a spring 7 pressing the inner peripheral surface of the pipe wall. And a position adjusting means 8 for moving the flaw detecting head 6 in the axial direction of the guide rod 4. The position adjusting means 8 is parallel to the guide rod. And a drive mechanism 10 mounted on the support member 3 for moving the flaw detection head 6 in the longitudinal direction and the circumferential direction of the tubular body P. It is configured.
Then, after the contact medium supplied through the pipe 23 and the pipe line 21 makes the contact state between the ultrasonic probe 5 and the pipe wall of the tubular body P dense, the pulse motor 28 is operated to operate the pulse motor 28. The flaw detection head 6 is rotated 360 degrees to perform flaw detection, and the feed screw 9 is rotated by a pulse motor (not shown) to move the flaw detection head 6 a predetermined distance in the lengthwise direction of the tubular body P to perform flaw detection in the next circumferential direction. Set the position. As a result, even if the outer surface of the tubular body P has an uneven shape, the ultrasonic probe is brought into contact with the inner peripheral surface of the tubular body P that has been machined into a smooth cylindrical surface, so that the tubular wall Non-destructive inspection is possible.

[0003]

However, in the above-mentioned nondestructive inspection apparatus for a tubular body, the ultrasonic probe 5 is brought into direct contact with the inner peripheral surface of the tubular body P, so that the flaw detection head 6 is mounted. There is a problem that it cannot be moved in the circumferential direction and the axial direction of the inner peripheral surface at a high speed, and therefore the ultrasonic flaw detection cannot be efficiently performed. Also,
The support members 2 and 3 supporting the guide rods 4 are tubular bodies P.
Since the support members 2 and 3 cannot be easily attached to the tubular body P because they are fitted to the inner peripheral surface of the tubular body P, the support members 2 and 3 can be easily attached to other tubular bodies having different inner diameters. When using a non-destructive inspection device, the support member 2
There was a problem that it was necessary to replace the constituent parts of No. 3.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an ultrasonic flaw detector for efficiently performing ultrasonic flaw detection on a tubular body. To do.

[0005]

The above-mentioned object is to remove the tubular body by the flaw detection head of the present invention, which moves the inside of the tubular body filled with flaw detection water at a predetermined distance from the inner peripheral surface of the tubular body. An ultrasonic flaw detector for a tubular body for ultrasonic flaw detection, which guides the movement of the flaw detection head by engaging with the flaw detection head, and a guide rod adapted to extend along the axis of the tubular body, By the plurality of rotating bodies rolling on the inner peripheral surface of the tubular body, the axis of the guide rod is matched with the axis of the tubular body, and the guide rod is rotatable around the axis and displaced in the axial direction. A guide rod supporting means that supports the guide rod freely; a frame that rotatably fits the guide rod; a guide rod rotating means that is provided on the frame and that rotates the guide rod around the axis of the tubular body; A flaw detection head drive means for moving the flaw detection head in the axial direction of the guide rod, and a seal flange that is tiltably engaged with the frame and is fixed to the tubular body to seal the flaw detection water. This is achieved by an ultrasonic flaw detector for a tubular body. In addition, in the guide rod support means,
A rotating body contacting / separating mechanism for contacting / separating with respect to the guide rod is provided so that each of the plurality of rotating bodies is located at an equal distance from the axis of the guide rod. Further, a rotating body holding member, one end of which is rotatably supported by the guide rod and the other end of which is biased by the rotating body contacting / separating mechanism, and the other end of the rotating body holding member and the guide. A taper member interposed between the rod and the actuator, and an actuator that reciprocates the taper member to bring the rotary member holding member into contact with and separate from the guide rod are provided.

[0006]

The flaw detection head emits an ultrasonic wave and detects a reflected wave reflected from the wall surface of the tubular body. The ultrasonic wave emitted from the flaw detection head propagates through the flaw detection water to reach the tubular body, is reflected by the wall surface of the tubular body, propagates through the flaw detection water again, and reaches the flaw detection head. The guide rod engages with the flaw detection head and guides the movement of the flaw detection head. The guide rod support means supports the guide rod by a rotating body that rolls on the inner peripheral surface of the tubular body, aligns the axis of the guide rod with the axis of the tubular body, and rotates the guide rod around the axis of the tubular body. To be able to rotate and displace in the axial direction. The guide rod rotating means displaces the flaw detection head in the circumferential direction by rotating the guide rod around its axis to cause flaw detection in the circumferential direction of the tubular body. The flaw detection head driving means displaces the flaw detection head guided by the guide rod in the axial direction of the guide rod to perform flaw detection in the axial direction of the tubular body. The seal flange seals the flaw detection water inside the tubular body. The rotating body contact / separation mechanism of the guide rod support means
While keeping the distance between each rotating body and the axis of the guide rod the same, move each rotating body toward or away from the guide rod so that the axis of the guide rod coincides with the axis of the tubular body and has a different inner diameter. This ultrasonic flaw detector can be attached to a tubular body.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an ultrasonic flaw detector for a tubular body according to the present invention will be described in detail below with reference to FIGS. Here, FIG. 1 is an overall sectional view of an embodiment of an ultrasonic flaw detector for a tubular body according to the present invention, and FIG. 2 is a sectional view of a main part of the ultrasonic flaw detector for a tubular body shown in FIG. Figure 3
FIG. 4 is an explanatory view for explaining a state in which the ultrasonic inspection device for tubular body shown in FIG. 1 is attached to a tubular body for flaw inspection, and FIG. 4 is a side view of a conventional nondestructive inspection device for tubular body.

First, a tubular body for flaw detection using the ultrasonic flaw detector of this embodiment will be described. As shown in FIG. 3, in this embodiment, the base end of the rotor is inserted in this tubular body. It is said to be one of the four tubular parts formed by forging a titanium alloy into a cross shape with a bottomed hole. The outer peripheral surface 11 of the tubular portion is forged into a substantially cylindrical shape, and the inner peripheral surface 13 of the bottomed hole 12 is smoothly finished by machining. Further, the wall surface 14 on the opening side of the bottomed hole 12 is
It is a plane perpendicular to the axis of. Then, the ultrasonic flaw detector 100 of the present embodiment is fixed to the wall surface 14 by a bracket (not shown) and sequentially attached to the bottomed holes 12 at four locations, so that flaw detection inspection of each tubular portion 10 is performed. Has been done.

Next, the outline of the ultrasonic flaw detector 100 of this embodiment will be described with reference to FIG. First, the ultrasonic flaw detector 100 has a portion to be inserted into the bottomed hole 12 of the tubular portion for flaw detection and a portion to be located outside the bottomed hole 12. The former is a flaw detection head 20 for flaw detection on the tube wall of the bottomed hole 12, and the bottomed hole 12 of the flaw detection head 20.
Is a guide rod 30 for guiding the movement of the flaw detection head 20 along its axis, and a guide rod supporting means 60 for supporting the guide rod 30 so that its axis coincides with the axis of the bottomed hole 12. The flaw detection head drive means 50 for moving the guide rod 30 in the axial direction, the guide rod rotating means 40 for rotating the guide rod 30 around its axis, and the devices for supporting the guide rod 30 and these devices. A frame 70 to be attached, a seal flange 71 for fixing the frame 70 to a tubular portion via a gimbal mechanism 73, a cover 80 for covering other devices attached to the frame, and the like.

Next, each part will be described in order with reference to FIG. First, the flaw detection head 20 emits ultrasonic waves perpendicularly to the inner peripheral surface 13 of the bottomed hole 12.
The ultrasonic waves emitted from the flaw detection head 20 are
The inner peripheral surface 13 and the outer peripheral surface 11 are transmitted to the wall surface of the tubular portion 10 through flaw detection water filled in the tubular portion 10.
Is reflected by. The signal of the reflected wave detected by the flaw detection head 20 is observed by an observation device 93 provided separately from the ultrasonic flaw detection inspection device 100 to detect a flaw. The flaw detection head 20 is housed in a cylindrical case 21 slidably fitted on the inner peripheral surface of a cylindrical guide rod 30. Further, the wiring 22 connected to the flaw detection head 20 is housed in a pipe 23 having its tip attached to the case 21 and extending along the axis of the guide rod 30. This pipe 23
A connector 25 is attached to the end portion on the opposite side of the connector 25 via a slip ring 24, and the signal of the reflected wave transmitted to the wiring 22 is transmitted from the connector 25 to the observation device 92 via a signal wiring 93. Further, a flaw detection head 20 is attached to the case 21 so that a nylon brush 22 extends in a direction of emitting an ultrasonic wave, and a tip of the nylon brush 22 is brought into contact with the inner peripheral surface 13 of the bottomed hole 12 to form an inner peripheral surface. Thirteen
It is designed to remove air bubbles that adhere to the. further,
A female screw 27 is screwed on the case 21 in parallel with the axis of the guide rod 30, and is screwed to a feed screw 51 of a flaw detection head driving means 50 for moving the flaw detection head 20 in the axial direction of the guide rod 30. Has been

As shown in FIG. 2, the guide rod 30 is formed by notching a wall surface of a thick-walled pipe along its axis with a constant width over its entire length. The case 21 is slidably fitted, and from the cutout portion 32,
The head of the flaw detection head 20 is adapted to protrude in the radial direction. A protector 33, which is narrowed toward the tip side of the guide rod 30, is fitted to the tip of the guide rod 30, and when the guide rod 30 is inserted into the bottomed hole 12, flaw detection is performed. The head 20 is protected so as not to hit the inner peripheral surface 13 of the bottomed hole 12 and the like. A bearing tail 34 is externally fitted to the base end side of the guide rod 30 and is screwed and fixed integrally so as not to rotate relative to each other.

Next, the frame 70 for mounting the ultrasonic flaw detector 100 on the tubular portion 10 will be described. First, the frame 70 has a seal flange 71 that is attached so as to be in close contact with the wall surface 14 on the opening side of the bottomed hole 12. The seal flange 71 includes a disc-shaped portion 71 a that is in close contact with the wall surface 14 and the disc-shaped portion 7.
A flange 71c vertically provided around a through hole 71b provided in 1a, a through hole 71d for draining flaw detection water filling the inside of the bottomed hole 12, and a connector 72 for connecting a pipe for supplying flaw detection water are provided. Have A pair of annular seals 74 are attached to the disc-shaped portion 71a to seal the flaw detection water.

A bearing case 76 is attached to the seal flange 71 via a gimbal mechanism 73 attached to the flange 71c. A pair of bearings 77 is attached to the bearing case 76. And this pair of bearings 7
The bearing tail 34 attached to the base end of the guide rod 30 is fitted to the guide rod 7, so that the guide rod 30 is rotatably supported with respect to the bearing case 76.

Since the gimbal mechanism 73 is interposed between the seal flange 71 and the bearing case 76, the seal flange 71 can take an arbitrary inclination with respect to the bearing case 76.
Even if is a surface inclined with respect to the axis of the bottomed hole 12, the ultrasonic flaw detector 100 can be attached to the tubular portion 10. Further, a rubber boot 75 is attached between the seal flange 71 and the bearing case 76 so that the flaw detection water does not leak to the outside from the gap between the two even when both are relatively inclined by the gimbal mechanism 73. Has been done.

The guide rod rotating means 40 includes a motor 41 fixed to the bearing case 76, a pinion gear 42 attached to a rotating shaft of the motor 41,
Spur gear 4 integrally screwed to the bearing tail 32
2 and. Further, the spur gear 42 includes a pinion gear 45 of a potentiometer 44 provided on a portion of the spur gear 42 opposite to the motor 41 with respect to the axis of the guide rod 30.
Are engaged so that the rotation angle of the guide rod 30 can be measured.

The flaw detection head driving means 50 is attached to a feed screw 51 provided inside the guide rod 30 so as to extend parallel to the axis, a pinion gear 53 attached to the feed screw 51, and the bearing case 74. This feed screw 5 fixed to the base plate 78
Motor 52 for rotating 1 and these lead screws 5
1 and a motor pinion gear 53 are connected to each other by a gear or the like (not shown). Then, the tip of the feed screw 51 is screwed into the case 21 that houses the flaw detection head 20, and the feed screw 51 is rotated in the forward and reverse directions by the motor 52 to guide the flaw detection head 20 into the guide rod 30.
It is designed to reciprocate in the axial direction along the. Further, the first limit switch 55 is attached to the base plate 78. Then, the flaw detection head 20 comes closest to the base plate 78 side and pushes the piston 54 which is biased by the spring and protrudes toward the flaw detection head 20 side, whereby the first limit switch 55 operates. The rotation of the motor 52 is stopped. Further, a second limit switch 57 is attached to an operation panel 81 described later, and when the flaw detection head 20 comes closest to the bottom of the bottomed hole 12, the boss 56 attached to the tip of the wiring pipe 23 is The second limit switch 57 is actuated to drive the motor 5
The rotation of 2 is stopped.

The guide rod support means 60 has a pair of ball sets 61 attached to the tip end side and the base end side of the guide rod 30, respectively. The ball set 61 has three balls 62 arranged at equal intervals in the circumferential direction of the guide rod 30, and each of the balls 62 is supported by a ball support member 63 so as to be rotatable in any direction. There is. The ball support member 63 has one end rotatably supported by the protector 33 or the bearing tail 34 by a shaft 64 extending perpendicularly to the axis of the guide rod 30. Further, a spring 65 is interposed between the ball support member 63 and the guide rod 30 at the end 63a on the shaft 64 side, and the free end side end 63b of the ball support member 63 faces the guide rod 30. Are urged to do so. In addition, a roller 66 is attached to the free end 63b of the ball support member 63.
Are rotatably supported about an axis perpendicular to the axis of the guide rod 30. On the other hand, three pairs of air cylinders 67 that expand and contract in the axial direction of the guide rod 30 by the air pressure supplied by an air pipe (not shown) are provided on the outer periphery of the central portion of the guide rod 30 in the longitudinal direction. And
The tip of the piston of the air cylinder 67 is screwed to a pair of taper rings 68 slidably fitted on the outer peripheral surface of the guide rod 30. The taper ring 68 has a taper portion 68 a that becomes narrower toward the ball support member 63 side. It is interposed between. As a result, when the air cylinder 67 extends, the sliding taper ring 68 is displaced toward the roller 66 side so that the ball 62 is guided by the guide rod 30.
It is displaced radially outward with respect to the axis of. On the contrary, when the air cylinder 67 contracts, the ball 62 is displaced inward in the radial direction and approaches the guide rod 30. At this time, since the pair of sliding taper rings 68 are symmetrical about the axis of the guide rod 30, each of the six balls 62 in total has the same shape.
The air cylinder 67 allows the guide rod 30 to come into contact with and separate from the guide rod 30 while keeping the same distance from the 0 axis line.

A cover 80 is attached to the bearing case 76, and the flaw detection head driving means 50 is attached.
Also, the guide rod rotating means 60 and the valve mechanism for supplying air to the guide rod supporting means 40 are covered. The operation panel 81 is provided at the end of the cover 80.
Is provided with a socket 82 for attaching a wiring 92 for connecting the ultrasonic flaw detector 100 to the control device 91 shown in FIG. 3, an air operation switch 84, and the like. Further, on the cover 80, a handle 88 used for carrying the ultrasonic flaw detector 100.
Is attached.

Next, the ultrasonic flaw detector 100 of this embodiment is used.
The operation and operation of will be described. First, in order to attach the ultrasonic flaw detector 100 to the tubular portion 10 to be inspected, the handle 78 is gripped by hand and the ultrasonic flaw detector 100 is suspended, and the guide rod 30 is provided with the bottomed hole 12. And the seal flange 71 is brought into contact with the wall surface 14 of the tubular portion 10. And
Guide rod support means 6 attached to the operation panel 81
The high pressure air is supplied by operating the air control switch 84 which controls the air supplied to the 0 air cylinder. As a result, the air cylinder 67 extends and the taper ring 68
Slide, and each ball 62 moves the inner peripheral surface 13 of the bottomed hole 12.
Is pressed by. As a result, the axis of the guide rod 30 matches the axis of the bottomed hole 12, and the guide rod 30
Is supported so as to be rotatable with respect to the inner peripheral surface 13 and displaceable in the axial direction.

Next, in this state, the seal flange 71 is fixed to the tubular portion 10 on the wall surface 14 of the tubular portion 10 by a bracket (not shown). Then, the socket 82
Then, the connector 85 of the wiring 91 extending from the control device 90 is connected to the control device 90 for controlling the ultrasonic flaw detector 100. Also, the guide rod support means 40
Connect the air piping to supply to the connector (not shown). Further, a pipe (not shown) for supplying flaw detection water to fill the bottomed hole is also connected to a connector 72 provided on the seal flange 71 to inject the flaw detection water, and a through hole 71d provided in the seal flange 71 By overflowing from the above, the inside of the bottomed hole 12 is filled with flaw detection water.

To start the ultrasonic flaw detection, first, the air operation switch 84 is operated to switch the air supplied to the air cylinder 47 of the guide rod support means 40 to a low pressure. As a result, the urging force that presses the ball 42 against the inner peripheral surface 13 of the bottomed hole 12 is weakened, the rotational frictional resistance of the ball is reduced, and the guide rod 30 can rotate smoothly. Next, the controller 90 is operated to operate the flaw detection head driving means 40 to move the flaw detection head 20 to the bottomed hole 1
Position it at the deepest side of 2. Further, when the guide rod rotating means is operated, the flaw detection head 20 first rotates 360 degrees in the forward rotation direction to detect a flaw on the tube wall of the tubular body 10. After that, the flaw detection head 20 is automatically displaced along the guide rod 30 by a predetermined distance in the axial direction, and this time, in the reverse rotation direction, 360
Rotate once to detect flaws. Thereafter, this operation is automatically repeated, and when the flaw detection head 20 comes closest to the opening of the bottomed hole 12, the above-mentioned first limit switch 55 operates,
The flaw detection operation ends. During this time, the reflected wave detected by the flaw detection head 20 is the wiring 22 and the slip ring 2.
Observation device 92 through 4, socket 25, and signal wiring 93
And the presence or absence of defects in the tube wall of the tubular portion 10 is observed. When the flaw detection of the tubular portion 10 at one place is completed, the ultrasonic flaw detector 100 is removed and attached to the next tubular portion, and the same flaw detection is performed.

[0022]

In the ultrasonic flaw detector for a tubular body of the present invention, the flaw detection head is moved a predetermined distance from the wall surface of the tubular body by filling the interior of the tubular body with flaw detection water. Therefore, the moving speed of the flaw detection head can be increased. As a result, the ultrasonic flaw inspection can be efficiently performed. Further, since the guide rod that guides the movement of the flaw detection head is supported by the guide rod supporting means having a plurality of rotating bodies that roll on the inner peripheral surface of the tubular body, the guide rod does not move in the axial line of the tubular body. Since the guide rod can be rotated around and axially displaced, the guide rod can be easily inserted into the tubular body. Furthermore, by inserting this guide rod inside the tubular body, the axis of the guide rod can be easily aligned with the axis of the tubular body. As a result, the ultrasonic flaw inspection can be efficiently performed. Further, since the plurality of rotating bodies of the guide rod supporting means are brought into contact with and separated from the guide rod while maintaining the same distance with respect to the axis of the guide rod,
The guide rod is inserted into the tubular body with the rotor close to the guide rod, and then the rotor is separated from the guide rod and brought into contact with the inner peripheral surface of the tubular body to form the tubular guide rod. It has become possible to easily insert it inside the body. Further, the ultrasonic flaw detector for tubular bodies of the present invention can be easily attached to tubular bodies having different inner diameters.

[Brief description of drawings]

FIG. 1 is an ultrasonic flaw detector for a tubular body according to the present invention.
It is a whole sectional view of an example.

FIG. 2 is a cross-sectional view of a main part of the ultrasonic flaw detector for a tubular body shown in FIG.

FIG. 3 is an explanatory diagram illustrating a state in which the ultrasonic testing device for a tubular body shown in FIG. 1 is attached to the tubular body.

FIG. 4 is a side view of a conventional destructive inspection device for a tubular body.

[Explanation of symbols]

 10 tubular part 11 outer peripheral surface 12 bottomed hole 13 inner peripheral surface 14 wall surface of opening of bottomed hole 20 flaw detection head 21 case 22 wiring 23 wiring pipe 24 slip ring 25 connector 26 nylon brush 27 female screw 30 guide rod 31 of guide rod Circumferential surface 32 Cutout 33 Protector 34 Bearing tail 40 Guide rod rotating means 41 Drive motor 42 Pinion gear 43 Spur gear 44 Potentiometer 45 Pinion gear 50 Inspection head drive means 51 Feed screw 52 Pinion gear 53 Drive motor 54 Piston 55 First limit switch 56 Case 57 second limit switch 60 guide rod support means 61 ball set 62 ball support member 63 ball support member 64 shaft 65 spring 66 roller 67 air cylinder 68 taper ring 70 frame 71 seal flange 72 flaw detection water connector 73 gimbal mechanism 74 rubber seal 75 rubber boot 76 bearing case 77 bearing 78 base plate 80 cover 81 operation panel 82 wiring connector 83 air switch 84 handle 90 control device 91 control wiring 93 observation device 94 signal wiring 100 Ultrasonic flaw detector of the present invention

Claims (3)

[Claims] 1. An ultrasonic flaw detection apparatus for a tubular body, which ultrasonically flaw-detects a tubular body by a flaw detection head that moves inside the tubular body filled with flaw detection water at a predetermined distance from the inner peripheral surface of the tubular body. A guide rod extending along the axis of the tubular body for guiding the movement of the flaw detection head by engaging with the flaw detection head, and a plurality of rotations rolling on the inner peripheral surface of the tubular body A guide rod supporting means for making the axis of the guide rod coincide with the axis of the tubular body by the body, and supporting the guide rod rotatably around the axis and displaceable in the axial direction; A frame that freely fits, a guide rod rotating means provided on the frame for rotating the guide rod around the axis of the tubular body, and the flaw detection head in the axial direction of the guide rod. Ultrasonic wave of a tubular body, comprising: a flaw detection head driving means for moving the flaw detection head; and a seal flange that is tiltably engaged with the frame and is fixed to the tubular body to seal the flaw detection water. Inspection equipment. 2. A rotating body contacting / separating mechanism for contacting / separating the guide rod supporting means with respect to the guide rod while arranging each of the plurality of rotating bodies at an equal distance from the axis of the guide rod. The ultrasonic flaw detector for a tubular body according to claim 1, further comprising: 3. A rotating body holding member in which the rotating body contacting / separating mechanism is urged so that one end thereof is axially supported by the guide rod and the other end is in contact with the guide rod, and the rotating body holding member. And a taper member interposed between the guide rod and the guide rod, and an actuator for reciprocating the taper member to bring the rotary body holding member into and out of contact with the guide rod. Item 2. The ultrasonic flaw detector for a tubular body according to Item 2.