JP2522193Y2 - Tightening bolt inspection probe - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe for checking a fastening bolt which is used as a sensor part of a device for checking and checking a fastening bolt of a reactor internal structure of a pressurized water reactor.

[0002]

2. Description of the Related Art Conventionally, in a reactor internal structure of a pressurized water reactor, as means for connecting members for connecting plate-shaped members,
Fastening bolts are used. FIG. 3 shows a typical shape and a fastening state of this type of bolt. In the figure, 6 is a fastening bolt, 7 is one fastening member, 8 is the other fastening member,
Reference numeral 9 denotes a detent pin. This type of structure is an important member that forms the boundary of the core adjacent to the combustion assembly, and maintains the bolt fastening function even after long-term use.
That is, the bolt must be sound.

As a method for confirming the soundness of the fastening bolt, there is an ultrasonic flaw detection test method, and a flaw detection probe as shown in FIGS. 4 and 5 has been conventionally applied. FIG. 4 shows a direct contact-type flaw detection probe, which diagnoses the soundness of a bolt by vertically incident ultrasonic waves from the bolt head and detecting the reflected wave. FIG. 5 shows a water immersion-type flaw detection probe. Similarly, ultrasonic waves are vertically incident from a bolt head, but are different from the direct contact type in that diagnosis can be performed in a non-contact manner through water.

In FIGS. 4 and 5, 5 is a probe main body, 13 is a coil spring, and 14a and 14b are ultrasonic sensors. The arrangement of the ultrasonic sensors 14a and 14b on the bolt head is as shown in FIG.

[0005] In these methods, the ultrasonic wave in the fastening bolt propagates along its axis. Therefore, in a sound bolt, the ultrasonic wave reaches the bottom of the bolt, and only the reflected wave on the bottom (hereinafter referred to as bottom echo) is detected. On the other hand, as shown in FIG. 5, when a defect such as a crack Fs is present in the bolt, the path of the ultrasonic wave is interrupted by the defect Fs, the bottom echo is reduced, and the reflected wave of the defect (hereinafter referred to as the defect echo). ) Is detected.

[0006]

However, the above-mentioned conventional method has the following problems.

(1) Since the ultrasonic wave propagates along the axis in the bolt, a defect echo can be easily detected in the defect Fs propagating in the direction perpendicular to the axis as shown in FIG. For a defect that grows obliquely, the reflected wave changes its direction and does not return toward the ultrasonic sensor, and it is difficult to detect a defect echo.

(2) Defects can be detected irrespective of the growth direction of the defect by monitoring the decrease of the bottom echo. However, in this method, it is difficult to detect a small defect in principle. There is a high risk of erroneous diagnosis because it is also reduced by the ultrasonic wave incident loss due to the part shape or the setting error of the probe or the attenuation of the ultrasonic wave in the bolt. (3) Since ultrasonic waves are incident from two points with the rotation-stop pin interposed therebetween, the defect detection capability immediately below the incident point is high, but the defect detection capability immediately below the pin is extremely poor.

As described above, the conventional inspection method has various problems and cannot be said to be a sufficiently reliable method. As a place of occurrence of damage that may be a concern with this type of fastening bolt, firstly, the lower part of the bolt neck is cited, and it is expected that the direction of the defect will grow obliquely due to the acting stress. For this reason, there has been a strong demand for a fastening bolt inspection probe that has a sufficient detection capability for obliquely growing defects generated in the lower part of the neck.

The present invention has been made in view of such circumstances, and the purpose thereof is not only to prevent defects propagating in the direction perpendicular to the axis of the fastening bolt, but also to extend obliquely to the axis. It is an object of the present invention to provide a fastening bolt inspection probe which can reliably detect a defect which occurs and which has sufficient detection ability particularly for an obliquely developing defect generated in the lower part of the neck.

[0011]

The present invention employs the following configuration in order to solve the above-mentioned problems.

That is, the present invention relates to a fastening bolt inspection probe for detecting a defect of a fastening bolt by ultrasonic waves, so that the axis of the fastening bolt is parallel to the bolt axis with respect to the head of the fastening bolt. A plurality of first ultrasonic sensors disposed on the circumference and a first ultrasonic wave on the same circumference by inclining the axis toward the bolt axis with respect to the flange surface of the fastening bolt. A plurality of second ultrasonic sensors arranged in the same direction as the sensor, and connected to the first and second ultrasonic sensors;
An ultrasonic flaw detector that drives each sensor and detects a flaw in the fastening bolt based on a reception signal of each sensor, and is disposed between the ultrasonic flaw detector and the first and second ultrasonic sensors,
Either the first ultrasonic sensor functions as a transmitter / receiver, or the second ultrasonic sensor functions as a transmitter / receiver, or one of the first and second ultrasonic sensors is used for transmission and the other is used for transmission. A changeover switch for switching whether to function as reception.

[0013]

According to the present invention, an ultrasonic beam propagating in parallel from the bolt head along the bolt axis by the first ultrasonic sensor is transmitted by the second ultrasonic sensor obliquely from the flange. A plurality of sound beams can be generated.

By operating the changeover switch, the first ultrasonic sensor and the second ultrasonic sensor can be used independently for both transmission and reception, or the first ultrasonic sensor can be used for reception and the second ultrasonic sensor can be used for reception. Can be used in combination for transmission. As a result, three types of ultrasonic waves having different paths can be transmitted and received, which is effective for detecting a scratch inside the bolt.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a probe for checking a fastening bolt according to the present invention will be described below with reference to FIGS. FIG. 1 shows the arrangement and fastening state of the ultrasonic sensor at the head of the fastening bolt 6 to be inspected, and FIG. 2 shows a cross section of the probe.

In FIG. 1, reference numerals 1a, 1b,..., 1f denote vertical ultrasonic sensors (hereinafter referred to as vertical sensors), which are vertically held at the heads of bolts 6 and arranged on the same circumference. Set up. Reference numerals 2a, 2b, to 2f denote oblique ultrasonic sensors (hereinafter referred to as oblique angle sensors), in which the sensor axis is inclined toward the inside of the bolt 6, and a plurality of the vertical sensors 1a are arranged on the same circumference. , 1b, to 1f.

Reference numeral 4 denotes an ultrasonic flaw detector which drives each sensor and detects a flaw of the bolt 6 based on a signal received from each sensor. A changeover switch 3 is provided between the ultrasonic flaw detector 4 and each sensor to select a sensor to be operated. The following (Table 1) shows the switching pattern of the changeover switch 3.

[0018]

[Table 1]

By switching the changeover switch 3, the vertical sensors 1a, 1b,..., 1f are respectively used for transmission and reception, the oblique angle sensors 2a, 2b,. ,..., 1f for transmission and vertical sensors 2a, 2b,. Therefore, if six vertical sensors and six oblique angle sensors are provided, as in this embodiment, there are 18 (6 × 3) switching patterns.

FIG. 2 illustrates the cross section of the probe and the path of the ultrasonic wave. Reference numeral 5 denotes a probe main body, 1b and 1e denote vertical sensors, and 2b and 2e denote oblique angle sensors. Also, 6
Is a fastening bolt to be inspected, 7 and 8 are fastening members, 9 is a detent pin, and 10 is water filled between the bolt head and the sensor. The arrow (-→) in the figure indicates the path of the ultrasonic wave. In the figure, the vertical sensor 1e is used for both sending and receiving, the oblique angle sensor 2e is used for both transmitting and receiving, and the oblique angle sensor 2b is used for transmitting. And the path of ultrasonic waves when the vertical sensor 1b is operated for reception.

As shown in FIG. 2, the vertical sensor 1e is used for both transmission and reception (switching pattern: 5 in Table 1).
This makes it possible to detect a defect Fs that extends perpendicular to the bolt axis. Further, by using the oblique angle sensor 2e for both transmission and reception (switching pattern: 11 in Table 1), it is possible to detect a defect Fa that extends obliquely. Further, the oblique angle sensor 2b is used for transmission, and the vertical sensor 1
b for reception (switching pattern: 1 in Table 1)
4) By doing so, it is possible to detect a defect Fa having a gradient between Fs and Fb.

As described above, according to the present embodiment, the vertical sensor 1 and the oblique angle sensor 2 are set on the fastening bolt 6 to be inspected, and the changeover switch 3 is operated, so that several points on the circumference of the fastening bolt 6 are obtained. More ultrasonic waves can be incident. Then, by changing the switching pattern of the changeover switch 3, the vertical sensor 1 and the oblique angle sensor 2 are individually operated for both transmission and reception, or the two sensors 1 and 2 are operated in combination for transmission and reception.
It is possible to transmit and receive ultrasonic waves having three different routes.

By the above operation, the ability to detect a defect immediately below the pin is improved, the ability to detect a diagonally growing defect that is expected to be generated immediately below the bolt is improved, and the entire bolt is rotated without rotating the probe itself. The circumference can be inspected uniformly, and an efficient and reliable inspection of the fastening bolt can be realized.

[0024]

As described in detail above, according to the present invention, the first and second ultrasonic sensors having different inclinations with respect to the bolt axis are arranged on the head of the fastening bolt, and these sensors are transmitted by the changeover switch.・ By properly switching between reception and transmission, or reception, it is possible to reliably detect not only defects that propagate in the direction perpendicular to the axis of the fastening bolt, but also defects that extend obliquely with the axis. In particular, it is possible to realize a probe for checking a fastening bolt, which has a sufficient detection capability for an obliquely developing defect generated in the lower part of the neck.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fastening bolt inspection probe according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a probe structure and a propagation state of an ultrasonic wave in the embodiment.

FIG. 3 is a perspective view showing a typical bolt shape of a fastening bolt and a fastening environment;

FIG. 4 is a cross-sectional view showing a conventional direct contact type flaw detection probe.

FIG. 5 is a sectional view showing a conventional water immersion type flaw detection probe.

FIG. 6 is a plan view showing an arrangement of an ultrasonic sensor on a conventional bolt head.

[Explanation of symbols]

1a, 1b, ..., 1f ... vertical ultrasonic sensor (first ultrasonic sensor), 2a, 2b, ..., 2f ... oblique ultrasonic sensor (second ultrasonic sensor), 3 ... changeover switch, 4 ... Ultrasonic flaw detector, 5: Probe body, 6: Fastening bolt, 7, 8: Fastening member, 9: Detent pin, 10: Water.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takanori Yamashita 1-1 1-1 Wadazakicho, Hyogo-ku, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Kenji Nishikawa Hyogo-ku, Hyogo 1-1 1-1 Wadazakicho Inside Kobe Shipyard, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-62-110150 (JP, A) JP-A-63-18263 (JP, A) JP-A-55-87038 ( JP, A) JP-A-61-217757 (JP, A) JP-A-62-161058 (JP, A) JP-A-62-291560 (JP, A) JP-A-2-78949 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A plurality of first ultrasonic sensors arranged on the same circumference so that the axis is parallel to the bolt axis with respect to the head of the fastening bolt; A plurality of second ultrasonic sensors arranged on the same circumference with the axis inclined toward the bolt axis with respect to the flange surface and arranged in the same direction as the first ultrasonic sensor; An ultrasonic flaw detector which is connected to the first and second ultrasonic sensors, drives each sensor, and detects a flaw of the bolt based on a reception signal of each sensor; and the ultrasonic flaw detector, the first and second ultrasonic sensors. The first ultrasonic sensor is used for both transmission and reception, the second ultrasonic sensor is used for both transmission and reception, or the first and second ultrasonic sensors are disposed between the first and second ultrasonic sensors. A switch for switching whether one of the ultrasonic sensors functions as a transmitter and the other functions as a receiver. Fastening bolt inspection probe, characterized by comprising comprises a pitch, a.