JPH08178904A - Ultrasonic flaw detector - Google Patents

Abstract

PURPOSE: To inspect the weld line of a narrow part difficult to adapt in a conventional ultrasonic flaw detector by miniaturizing an ultrasonic flaw detector. CONSTITUTION: In an ultrasonic flaw detector constituted of a track rail 11 arranged along a weld line, a main body drive part 12 running on the track, a flaw detection arm 13 attached to the main body drive part 12, a slide drive part extending and contracting the flaw detection arm 13 and a truck 16 having a probe 18 at the tip of the flaw detection arm 13, the flaw detection arm is formed into a multistage slide rail structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding line flaw detector at a narrow position, and is particularly suitable for performing ultrasonic flaw detection of a lower mirror welding line of an ABWR type reactor pressure vessel which is an improved BWR. Inspection equipment.

[0002]

2. Description of the Related Art Various structures (nozzles, pipes, etc.) are arranged near the lower mirror welding line of an ABWR-type nuclear reactor in a position closer to that of a conventional BWR-type nuclear reactor. Therefore, the ultrasonic flaw detector applied to the main welding line passes through this narrow part,
In addition, in a range where there is no interference structure, it is necessary to have a performance to secure a moving stroke of the probe for performing ultrasonic flaw detection.

Therefore, there is a report of a telescopic air cylinder system disclosed in Japanese Patent Laid-Open No. 63-40851 as a device patent for inspecting the main weld.

In this system, a flaw detection arm for moving a probe is provided with a multi-stage air cylinder, and a flaw detection stroke is secured by expanding gas by applying gas pressure into the cylinder during flaw detection.

However, the telescopic air cylinder type has a large arm diameter due to an increase in the number of stages of the cylinder and a decrease in arm rigidity when the ratio between contraction and extension is large.
Also, there are many design considerations, such as concern about the durability of the sliding surface of the cylinder and piston, and the need for an air pressure detector and controller because the cylinder volume changes according to the arm stroke. .

On the other hand, as a method for traveling the surface of an object to be inspected by using a magnet traveling roller, a trackless bogie system disclosed in JP-A-5-288736 has also been reported, but the position measurement and control of the bogie are complicated. In addition, since the drive mechanism is built in the carriage, the structure approach limit is limited.

[0007]

As described above, the ABW
An ultrasonic flaw detector for applying an R-shaped lower mirror welding line needs a device that can satisfy flaw detection strokes in a range where there is no interference structure, although it is a small device that can pass through a narrow space.

An object of the present invention is to provide an inspection mechanism which satisfies the above conditions and enables stable flaw detection.

[0009]

In order to achieve the above object, the present invention has a main body drive unit which runs on a track rail arranged along a welding line, and an ultrasonic probe, which has a flaw detection on a surface of a subject. It is composed of a slide rail type flaw detection arm that expands and contracts the trolley part that carries out the process in the direction orthogonal to the welding line.

[0010]

The main body drive unit travels on the main track by engaging the gear with the rack provided on the track rail permanently installed near the welding line and driving the gear with the motor.

A carriage having an ultrasonic probe is arranged at the tip of the main body drive unit, and a slide rail type flaw detection arm which expands and contracts in the direction orthogonal to the welding line and a slide using a motor for expanding and contracting this arm are used. It has a drive unit.

The flaw detection arm is composed of multi-stage rails that slide with each other, and racks are provided on both sides of each stage rail, and a gear for transmitting a slide driving force to the rack of the preceding rail and the rack of the next rail. By combining with, the entire rail is expanded and contracted by the slide drive of the first stage rail.

The trolley is provided with a magnet roller that attracts to the surface of the object to be assisted in flaw detection travel and a contact sensor for detecting the contact of a structure within the flaw detection range.

By constructing the drive unit with the above mechanism, it is possible to obtain a stroke satisfying the flaw detection required range by extending the slide rail, even though the drive unit is a compact drive unit that can pass through the narrow part.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a slide mechanism of the present invention.

FIG. 2 shows a cross-sectional view of the lower portion of an ABWR type reactor pressure vessel to which the apparatus of the present invention is applied, and FIG. 3 shows an inspection target range.

FIG. 4 is a device mechanism diagram and FIG. 5 is a perspective view of the device.

The lower mirror welding line 1c located in the lower part of the ABWR reactor is the circumferential welding line of the lower lens plate dome 1a and the lower lens plate petal 1b as shown in FIGS. 2 and 3, and the main welding line is sandwiched between them. Thus, a large number of CRD nozzles 22 are arranged on the center side of the reactor, and ten RIP nozzles 21 are attached on the outer peripheral side of the reactor.

For this reason, in the automatic drive system for inspecting the lower mirror welding line 1c, the range passing between the RIP nozzle 21 and the CRD nozzle 22 and passing through the squeezing portion 23 having a width of about 200 mm and excluding the main squeezing portion 23. In No. 24, a flaw detection stroke capable of moving and scanning the ultrasonic probe 18 as an inspection means is required to a position about 700 mm apart from the lower mirror welding line 1c.

In order to satisfy the requirements for the flaw detection site, FIG.
Also, the device shown in FIG. 5 was devised. The present apparatus includes a main body drive unit 12 running on a track rail 11 installed near the lower mirror welding line 1c shown in FIG. 5, a multi-stage slide rail type flaw detection arm 13, a slide drive unit 41, and a flaw detection arm 1
3 and a carriage 16 attached to the tip.

The circular track rail 11 for running this device is
It is permanently installed in the narrow part 23 between the RIP nozzle 21 and the CRD nozzle 22 by using the track stands 23 at eight locations from the lower floor surface of the lower mirror welding line 1c shown in FIG.

The main body drive unit 12 runs in the direction of the lower mirror welding line 1c by driving the X-axis gear 12a meshing with the rack 11a of the track rail 11 shown in FIG. 4 by the X-axis motor 12b.

Further, the main body drive section 12 has a vertical drive air cylinder 12c for pressing the slide drive section 41 against the surface of the subject.

The flaw detection arm 13 and the slide drive unit 41
Is composed of the following mechanism shown in FIG.

The flaw detection arm 13 is provided with a gear 41f meshed with the rack 41g of the slide mechanism 41 and the rack 42a of the slide rail 42 at the tip of the slide arm 41e which is horizontally driven by the slide drive unit 41.

The slide rail 42 is provided with a gear 42b that meshes with a rack 41h of the base of the slide drive unit 41 and a rack 43a of the slide rail 43.

The slide rail 43 includes a rack 42c for the slide rail 42 and a rack 44 for the slide rail 44.
A gear 43b meshed with a is provided.

The slide rail 44 includes a rack 43c of the slide rail 43 and a rack 45 of the slide rail 45.
A gear 44b meshed with a is provided.

A carriage 16 for ultrasonic flaw detection is attached to the slide rail 45.

Incidentally, each slide rail 42, 43, 4
The guide rollers 46, which support the sliding direction, support each other between 4 and 45.

The flaw detection arm 13 of the present device has a multi-stage slide rail structure in which the slide rail length of each stage is 150 mm or less, thereby ensuring applicability of the narrow part at the time of contraction.

The slide drive unit 41 is a Y-axis motor 41c.
The rotary drive of the above is converted into horizontal drive by the ball screw 41a and the ball nut 41b, and the slide arm 41e is slid. In addition, an encoder 41d that measures the number of rotations of the ball screw is arranged on the rotation shaft of the ball screw 41a.

The slide drive unit 41 also has a storage plate 15 for transporting the carriage 16 when the main body drive unit 12 travels on the track rail 11.

The dolly 16 is attached to a slide rail 45 at the tip of the flaw detection arm 13, and the ultrasonic probe 18 and the air cylinder 1 for pressing the probe 18 onto the surface of the object to be inspected.
9 and a sensor 20 for detecting that the dolly 16 has come into contact with the RIP 21 or the like within the traveling range.

Further, by using the traveling magnet roller 16a attracted to the surface of the subject as the carriage 16, the weight of the carriage 16 does not depend on the flaw detection arm 13 even when the flaw detection arm 13 is extended.

It should be noted that the main body drive unit 12 is the control cable 1
It is connected to a control device (not shown) via 2d, and receives the control signals of the main body drive unit 12 and the slide drive unit 41 from this control device to perform the operation.

A control cable 12e is also connected between the main body drive unit 12 and the slide drive unit 41. The operation of this device will be described below.

The main body drive unit 12 is carried by an operator and is attached so as to be held by the upper and lower running rollers 12f of the main body drive unit 12 in the permanently installed track rail guide unit 11b.

At this time, the main body drive unit 12 keeps the carriage 16 on the storage plate 15 so that the flaw detection arm 13 is contracted and the air cylinder 12c for vertically moving the slide drive unit 41 is used. Is not applied to separate the slide drive unit 41 and the subject from each other to facilitate the attachment to the track rail 11.

After the device is mounted on the track rail 11, the X-axis motor 12b is driven by the signal from the external control device using the control cable 12d to drive the gear 12a meshing with the rack 11a at the center of the track rail 11. Then, the track rail 11 is moved to a preset flaw detection start position.

At the flaw detection start position, the main body drive unit 12 puts air into the vertical drive air cylinder 12c of the slide drive unit 41 and presses the slide drive unit 41 against the surface of the subject.

Next, the main body drive unit 12 is connected to the slide drive unit 4
The Y-axis motor 41c of No. 1 is driven, the ball screw 41a is rotationally driven, and the ball nut 41b is converted into horizontal drive. A slide arm 41e is attached to the ball nut 41b to drive the flaw detection arm 13 toward the RIP nozzle 21 side.

The slide drive unit 41 is a Y-axis motor 41c.
The rotary drive of the above is converted into horizontal drive by the ball screw 41a and the ball nut 41b, and the slide arm 41e is slid.

Gear 41f at the tip of this slide arm 41e
Is the rack 41g of the slide drive unit 41 and the slide rail 4
The rack 42a is meshed with the second rack 42a and is supported on the fixed rack 41g to rotate counterclockwise, thereby slidingly driving the slide rail 42 toward the RIP nozzle 21.

Similarly, the slide rail 42 is provided with a gear 42b which meshes with the rack 41h of the slide drive portion and the rack 43a of the slide rail 43, and the gear 42b is provided.
Since 42b is also supported on the fixed rack 41h, the rack 42h is rotated counterclockwise, thereby sliding the slide rail 43 toward the RIP nozzle 21.

The slide rail 4 includes the slide rail 4
2 rack 42c and slide rail 44 rack 44a
A gear 43b meshing with the gear 43b is provided, and the drive force for the slide rail 42 to slide in the direction of the RIP nozzle 21 is obtained, and the main gear 43b is also rotated counterclockwise, whereby the slide rail 44 slides in the direction of the RIP nozzle 21. To drive.

Similarly, the slide rail 44 is provided with a gear 44b that meshes with the rack 43c of the slide rail 43 and the rack 45a of the slide rail 45 to obtain a driving force for the slide rail 43 to slide toward the RIP nozzle 21. The lever gear 44b is also rotated in the counterclockwise direction, thereby sliding the slide rail 45 toward the RIP nozzle 21.

The flaw detection arm 13 of the present apparatus is constructed by connecting multi-stage slide rails to each other with a gear and a rack.
The stroke amount of the slide rail 45 in the final stage is enlarged with respect to the movement amount of the slide arm 41e in the first stage.

The stroke of the flaw detection arm 13 is a value obtained by multiplying the amount of movement of the original slide arm 41e by the number of slide rail stages when the gear and rack ratios of the respective stages are the same.

In the sliding operation of the flaw detection arm 13, the contact sensor 20 attached to the extension side of the carriage 16 detects the RIP nozzle 21, or the end of the ball screw 41a of the slide arm 41e provided in the slide drive unit 41 is detected. The sensor 41i is detected, and the driving of the Y-axis motor 41c is stopped.

The flaw detection stroke is represented by the distance from the traveling start position of the carriage 16 to the stop position, and this distance is obtained by measuring the rotation of the ball screw 41a of the slide drive unit 41 by the encoder 41d.

When the carriage 16 is at the position where the flaw detection arm 13 is stopped, air is applied to the small air cylinder 19, the ultrasonic probe 18 is pressed against the surface of the subject, and the Y-axis motor 41c is moved while applying ultrasonic waves to the subject. The carriage 16 is rotated in the opposite direction to the slide driving direction, and the bogie 16 is returned to travel due to the contraction of the flaw detection arm 13.

When the flaw detection arm 13 contracts most, the carriage 16 moves onto the storage plate 15 of the slide drive unit 41, and this is detected by the carriage detection sensor 14 to detect the Y-axis motor.
Stop 41c.

Thereafter, the main body drive unit 12 is connected to the track rail 1
The X-axis motor 12b for one travel is rotationally driven to perform the pitch travel of this apparatus to the next flaw detection position.

The ultrasonic flaw detection operation of the lower mirror welding line 1c is performed by repeating the above-described expansion and contraction of the flaw detection arm 13 and the pitch travel of the main body drive unit 12.

At the end of the flaw detection operation, the main body drive unit 12
The air is released from the air cylinder 12c, the slide driving unit 41 is separated from the surface of the subject, and the worker removes the apparatus from the track rail 11, thus ending the work.

Further, in the embodiment, the support shaft 17 which rotates between the main body drive unit 12 and the slide drive unit 41 perpendicularly to the subject surface.
By supporting it with the
Rotate 0 ° to enable flaw detection running on the CRD22 side.

In addition to the lower mirror welding line 1c, the present apparatus can be applied not only to welding lines to which the ultrasonic flaw detection device cannot be applied due to a narrow space or the like but also to welding lines which cannot satisfy the flaw detection stroke. If the device of the present invention can be run, the inspection can be applied.

Further, by setting the expansion / contraction start position of the flaw detection arm 13 at the center of the slide stroke, it is possible to perform flaw detection on both sides of the RIP 21 and CRD 22 sides.

In this apparatus, the main body drive unit 12 on which the flaw detection arm 13 of the multi-stage slide rail is mounted is of a track running type, but as another means, the main body drive unit is of a trackless running type using a magnet or air suction. It is also possible to do so.

[0061]

According to the present invention, the flaw detection apparatus can be downsized without impairing the flaw detection stroke, which is an effective means for improving the applicability of the narrow portion.

[Brief description of drawings]

FIG. 1 is an explanatory view of a slide rail of the present invention.

FIG. 2 is a cross-sectional view of a lower mirror of an ABWR type reactor pressure vessel.

FIG. 3 is an explanatory view of a flaw detection range of an ABWR reactor pressure vessel.

FIG. 4 is a side view of the device mechanism.

FIG. 5 is a side view of the apparatus according to the embodiment.

[Explanation of reference numerals] 11 ... Track rail, 12 ... Main body drive unit, 13 ... Flaw detection arm, 16 ... Truck, 18 ... Ultrasonic probe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Akasu 3-2-1, Saicho-cho, Hitachi-shi, Ibaraki Hitachi Engineering Co., Ltd. (72) Yasunori Inada 3-1-1, Saiwai-cho, Hitachi, Ibaraki No. 1 Stock company Hitachi Ltd. Hitachi factory

Claims (3)

[Claims] 1. A device for inspecting the soundness of a welded portion such as a nuclear power pressure vessel using ultrasonic waves, in which a track rail is installed along a welding line, and a main body drive unit traveling on the track rail is probed. A carriage having an ultrasonic probe as a slave means is provided at the tip of a flaw detection arm that expands and contracts by remote control, and the flaw detection arm has a multi-stage slide structure in which slide rails are combined. , A gear that transmits the rail drive force of the previous stage to the next stage rail and a rack that slides by itself to obtain the gear drive force, and by driving the slide rail with a motor, when the slide contracts, there is a narrow gap. A flaw detection drive device characterized by having a stroke required for flaw detection at the maximum slide extension even though the flaw detection arm is shorter than the portion. 2. A storage plate for transporting the carriage in the track rail direction when the flaw detection arm is contracted is provided in the slide drive section, so that the carriage can be easily moved in a welding line direction. In addition, the drive device ensuring the workability of attaching and detaching the device to the track rail by vertically moving the main body drive part and the slide drive part with an air cylinder. 3. The drive according to claim 2, wherein a support shaft that rotates between the main body drive unit and the slide drive unit in a horizontal direction with respect to the subject surface is provided to arbitrarily change the extension / contraction direction of the flaw detection arm. apparatus.