CN111562311B

CN111562311B - Ultrasonic flaw detection method, device and system

Info

Publication number: CN111562311B
Application number: CN202010415821.7A
Authority: CN
Inventors: 苗德山; 孔冠宏; 李�瑞
Original assignee: Shandong Yuanzhuo Testing Technology Co ltd
Current assignee: Shandong Yuanzhuo Testing Technology Co ltd
Priority date: 2020-05-16
Filing date: 2020-05-16
Publication date: 2023-03-24
Anticipated expiration: 2040-05-16
Also published as: CN111562311A

Abstract

The invention discloses an ultrasonic flaw detection method, a device and a system, belonging to the technical field of nondestructive detection, which mainly comprises the following steps: s1: cleaning; s2: calibrating; s3: flaw detection, namely moving an inclined probe along the length direction of a welding seam; s4: accurately positioning, namely changing the distance and the angle between the oblique probe and the welding line to find the highest point of the echo of the ultrasonic flaw detector, positioning the position and the depth of the flaw through the ultrasonic flaw detector, and recording the position and the depth of the flaw; and in S3, the oblique probe linearly moves along the length direction of the welding seam and simultaneously performs circular motion, and the circle center of the circular motion is positioned on the moving motion track of the oblique probe along the length direction of the welding seam. The invention has the effect of improving the detection efficiency.

Description

Ultrasonic flaw detection method, device and system

Technical Field

The invention relates to the technical field of nondestructive testing, in particular to an ultrasonic flaw detection method, device and system.

Background

A pressure vessel is a closed vessel that can withstand pressure. The pressure container has wide application range, and has important position and function in many departments of industry, civil use, military industry and the like and many fields of scientific research. Because the interior of the pressure vessel needs to bear increased pressure, if the welding seam of the pressure vessel has flaws, potential safety hazards can be caused, and therefore flaw detection needs to be carried out on the welding seam of the pressure vessel, and ultrasonic flaw detection is generally practical.

Ultrasonic flaw detection is a method for detecting the defect of a part by using the characteristic that ultrasonic energy penetrates into the deep part of a metal material and is reflected at the edge of an interface when the ultrasonic beam enters another section from the section.

At present, the chinese patent publication No. CN102507734A discloses a method for detecting ultrasonic time difference diffraction of a weld joint, which is to set two probes with different refraction angles as a transmitting probe and a receiving probe on the same side of the weld joint, connect with a TOFD instrument, scan the weld joint, interpret the scanned image, if no defect signal image is found, the scanning is completed, otherwise, the probe spacing PCS is changed, the rest settings and parameters are kept unchanged, and then perform scanning once again, and perform calculation according to the two scanning results, thereby realizing the positioning and quantitative detection of the weld joint defect. The detection process needs to move along the length direction of the welding seam in a zigzag manner, so that defects of different depths and different distances can be detected.

The above prior art solutions have the following drawbacks: however, when the zigzag movement is performed, omission may be generated by detecting each point along the length direction of the weld only once, so that the rechecking is required, and the detection efficiency is low.

Disclosure of Invention

In view of the defects in the prior art, one of the objects of the present invention is to provide an ultrasonic flaw detection method having an effect of improving detection efficiency.

The above object of the present invention is achieved by the following technical solutions:

an ultrasonic flaw detection method mainly comprises the following steps:

s1: cleaning, namely cleaning the surface of an object to be detected, removing sundries and dust on the surface of the object to be detected, and drying water stains;

s2: calibrating, namely calibrating the ultrasonic flaw detector by using a test block;

s3: performing flaw detection, abutting the inclined probe on the surface of the object to be detected, aligning the front part of the inclined probe with the welding line, and then moving the inclined probe along the length direction of the welding line; when detecting that the welding seam has a flaw, marking the position with the flaw, and then continuing the detection until the whole welding seam is detected;

s4: accurately positioning, namely, utilizing the inclined probe to be close to the position marked in the step S3, changing the distance and the angle between the inclined probe and the welding line to find the highest point of the echo of the ultrasonic flaw detector, positioning the position and the depth of the flaw through the ultrasonic flaw detector, and recording the position and the depth of the flaw;

and in S3, the oblique probe linearly moves along the length direction of the welding seam and simultaneously performs circular motion, and the circle center of the circular motion is positioned on the moving motion track of the oblique probe along the length direction of the welding seam.

Through adopting above-mentioned technical scheme, the oblique probe carries out circular motion when carrying out linear movement along welding seam length direction, and the oblique probe can carry out repeated detection to the welding seam, only needs once to remove along the welding seam and has become to accomplish many times and detect, can save the step of reinspection, has improved detection efficiency.

The invention in a preferred example may be further configured to: and (3) coating a couplant on the surface of the object to be detected before S3, and avoiding coating the couplant when the inclined probe is contacted with the object to be detected.

By adopting the technical scheme, the coupling agent is filled in the gap between the oblique probe and the object to be detected, so that the air between the oblique probe and the object to be detected is reduced, the interference during detection is reduced, and the detection precision is improved.

The invention in a preferred example may be further configured to: in S3, the ratio of the linear movement distance of the tilt probe to the circular movement distance of the tilt probe in unit time is 1: and pi.

By adopting the technical scheme, the motion trail of the oblique probe on the workpiece to be detected is spiral, and the points of two adjacent circular motions in the motion trail are overlapped, so that each point of the welding line is detected for three times, and the defect point of the welding line is avoided being omitted by multiple times of detection.

Another object of the present invention is to provide an ultrasonic flaw detection apparatus having an effect of improving detection efficiency.

The above object of the present invention is achieved by the following technical solutions: the utility model provides an ultrasonic flaw detection device, includes the base, the base bottom is rotated and is connected with the mounting disc parallel rather than the lower surface, the eccentric rotation of one end that the mounting disc deviates from the base has the installation gear, the one end that the installation gear deviates from the mounting disc is provided with the angle probe, base fixedly connected with fixed axle, the fixed axle is coaxial rotation with the mounting disc and is connected, the coaxial fixedly connected with fixed gear of fixed axle, the mounting disc rotates and is connected with the intermediate gear with the equal meshing of fixed gear and installation gear, the number of teeth of fixed gear and installation gear is the same, be provided with drive structure on the base, drive structure drive mounting disc rotates.

By adopting the technical scheme, the driving structure drives the mounting disc to rotate, and the mounting disc rotates to drive the mounting gear to revolve, so that the inclined probe performs circular motion; because the mounting gear is meshed with the intermediate gear, and the intermediate gear is meshed with the fixed gear, the mounting gear rotates for a circle relative to the mounting disc, and does not rotate relative to the base mounting gear, so that the mounting gear always faces to one direction.

The invention in a preferred example may be further configured to: the base is connected with the gyro wheel in a rotating way, the orientation of oblique probe is on a parallel with the axial of gyro wheel.

Through adopting above-mentioned technical scheme, utilize the gyro wheel to make things convenient for detection device to remove on the object surface that awaits measuring to detection device when removing along welding seam length direction, can play the guide effect under the effect of gyro wheel.

The present invention in a preferred example may be further configured to: the drive structure includes coaxial fixed connection in the first worm wheel of mounting disc, the coaxial fixedly connected with second worm wheel of gyro wheel, the base rotates and is connected with the worm, the worm both ends mesh with first worm wheel and second worm wheel respectively, base fixedly connected with drive worm pivoted servo motor.

By adopting the technical scheme, the servo motor drives the worm to rotate, the worm drives the first worm wheel and the second worm wheel to rotate simultaneously, and the first worm wheel rotates to drive the mounting disc to rotate, so that the circular motion of the inclined probe is realized; the second worm gear rotates to drive the roller to rotate, the detection device can move in a linear motion mode, and the detection device drives the oblique probe to move along the length direction of the welding seam.

The present invention in a preferred example may be further configured to: the ratio of the revolution perimeter of the mounting gear to the perimeter of the roller is equal to pi: 1.

The invention also aims to provide an ultrasonic flaw detection system for the pressure container, which has the effect of improving the detection efficiency.

the utility model provides a pressure vessel ultrasonic flaw detection system, includes the ultrasonic flaw detection device, the ultrasonic flaw detection device's base is provided with first U-shaped magnet, the magnetic pole of first U-shaped magnet is towards pressure vessel's one end.

Through adopting above-mentioned technical scheme, utilize the magnetic force between first U-shaped magnet and the pressure vessel, make the device of detecting a flaw conflict the pressure vessel all the time on, make nondestructive test more laborsaving.

The present invention in a preferred example may be further configured to: still include auxiliary device, auxiliary device and ultrasonic flaw detection device are located the pressure vessel inside and outside respectively, auxiliary device includes the dolly, dolly fixedly connected with second U-shaped magnet, second U-shaped magnet is towards ultrasonic flaw detection device, the S level of second U-shaped magnet is aimed at to the N level of first U-shaped magnet, and the N level of second U-shaped magnet is aimed at to the S level of first U-shaped magnet.

Through adopting above-mentioned technical scheme, auxiliary device and flaw detection device are located the pressure vessel inside and outside respectively, and the S level of second U-shaped magnet is aimed at to the N level of first U-shaped magnet, and the N level of second U-shaped magnet is aimed at to the S level of first U-shaped magnet for magnetic induction line between the two is denser, increases the magnetic force between the two, makes the device of detecting a flaw more stable must contradict in the pressure vessel surface.

In summary, the invention includes at least one of the following beneficial technical effects:

firstly, the oblique probe linearly moves along the length direction of the welding seam and simultaneously performs circular motion, the oblique probe can repeatedly detect the welding seam, and the multiple detection can be completed only by moving along the welding seam once, so that the step of repeated detection can be omitted, and the detection efficiency is improved;

secondly, the ratio of the linear moving distance of the oblique probe to the circular motion distance of the oblique probe in unit time is 1: pi, in a moving track of the inclined probe on the workpiece to be detected, the points of two adjacent circular motions are superposed, so that each point of the welding seam is detected for three times, and the defect points of the welding seam are prevented from being missed by multiple detections;

the base of the flaw detection device is rotatably connected with a mounting disc, one end, away from the base, of the mounting disc is eccentrically and rotatably provided with a mounting gear, one end, away from the mounting disc, of the mounting gear is provided with a tilt probe, the base is fixedly connected with a fixed shaft, the fixed shaft is coaxially and rotatably connected with the mounting disc, the fixed shaft is coaxially and fixedly connected with the mounting fixed gear, the rotating disc is rotatably connected with an intermediate gear which is simultaneously meshed with the fixed gear and the mounting gear, and the mounting disc rotates to drive the mounting gear to revolve, so that the tilt probe performs circular motion; because the mounting gear is meshed with the intermediate gear, and the intermediate gear is meshed with the fixed gear, the mounting gear rotates for a circle relative to the mounting disc, and does not rotate relative to the base mounting gear, so that the mounting gear always faces to one direction;

fourthly, when detecting pressure vessel, with the above-mentioned detection device that detects a flaw as to the pressure vessel surface, be provided with auxiliary device in the pressure vessel, the first U-shaped magnet of fixedly connected with in the detection device that detects a flaw, including second U-shaped magnet in the auxiliary device, the S level of second U-shaped magnet is aimed at to the N level of first U-shaped magnet, the N level of second U-shaped magnet is aimed at to the S level of first U-shaped magnet, under first U-shaped magnet and second U-shaped magnet magnetic force effect, make the device that detects a flaw conflict throughout on the pressure vessel, make nondestructive test more laborsaving.

Drawings

FIG. 1 is a schematic flow chart of example 1;

FIG. 2 is a perspective view showing an ultrasonic flaw detection apparatus according to example 2;

FIG. 3 is a schematic structural view showing a flaw detection structure according to example 2;

fig. 4 is a schematic structural diagram of an ultrasonic flaw detection system according to embodiment 3.

Reference numerals: 100. an ultrasonic flaw detection device; 101. a roller; 102. a flaw detection structure; 103. mounting a disc; 104. installing a shaft; 105. a rolling bearing; 106. mounting grooves; 107. a fixed shaft; 108. mounting a gear; 109. an intermediate gear; 110. a drive structure; 111. an inclined probe; 112. a first worm gear; 113. a second worm gear; 114. a worm; 115. a servo motor; 116. an auxiliary device; 117. a first U-shaped magnet; 118. a second U-shaped magnet; 119. fixing a gear; 120. a base; 121. a trolley is provided.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Example 1: as shown in fig. 1, the ultrasonic flaw detection method disclosed by the present invention mainly includes the following steps:

s1: cleaning, namely firstly grinding and polishing the surface of the object to be detected to ensure that the surface is smooth and flat. Then cleaning the surface of the object to be detected, removing sundries and dust on the surface of the object to be detected, and finally drying water stains. And after drying, coating a couplant on the surface of the object to be tested, wherein the couplant is engine oil. The coupling agent can also play a role in rust prevention on the surface of an object to be detected. And a coupling agent is also coated on the surface of the inclined probe 111, which is in contact with the object to be detected.

S2: and (4) calibrating, namely calibrating the ultrasonic flaw detector by using the test block. The ultrasonic flaw detector is calibrated by using a test block and a reference method recorded in JJF1487-2014 ultrasonic flaw detection test block calibration standard.

S3: and (3) flaw detection, wherein the inclined probe 111 is abutted against the surface of the object to be detected, the front of the inclined probe 111 is aligned with the weld joint, then the inclined probe 111 is moved along the length direction of the weld joint, the inclined probe 111 performs linear movement along the length direction of the weld joint and performs circular movement at the same time, and the center of the circular movement is located on the movement track of the inclined probe 111 along the length direction of the weld joint. In conclusion, the movement track of the inclined probe 111 on the workpiece to be detected is spiral, the inclined probe 111 can repeatedly detect the welding seam in the movement, the detection is completed for multiple times only by moving along the welding seam once, the step of repeated detection can be omitted, and the detection efficiency is improved.

In the present embodiment, the ratio of the linear movement distance of the tilt probe 111 per unit time to the circumferential length of the circular motion is 1: and pi. Set up like this, the point coincidence of two adjacent circular motion in probe motion trail for each point of welding seam all carries out the cubic and detects, detects many times and avoids omitting the flaw point of welding seam.

When detecting that the welding seam has defects, the positions of the defects of the cover are marked, and then the detection is continued until the whole welding seam is detected.

S4: and (3) accurate positioning, namely, the inclined probe 111 is close to the position marked in the S3, the distance and the angle between the inclined probe 111 and the welding line are changed to find the highest point of the echo of the ultrasonic flaw detector, the position and the depth of the flaw are positioned through the ultrasonic flaw detector, and the position and the depth of the flaw are recorded.

The specific working principle of this embodiment is as follows: the oblique probe 111 carries out circular motion while carrying out linear movement along the length direction of the welding seam, the circle center of the circular motion is positioned on the moving motion track of the oblique probe 111 along the length direction of the welding seam, so that the motion track of the oblique probe 111 on a workpiece to be detected is spiral, the oblique probe 111 can repeatedly detect the welding seam in the motion, the repeated detection is completed only by moving along the welding seam once, the step of repeated detection can be omitted, and the detection efficiency is improved.

Example 2: as shown in fig. 2, the ultrasonic flaw detection apparatus 100 disclosed by the present invention includes a base 120, the base 120 is rotatably connected with four rollers 101, the base 120 is mounted with a flaw detection structure 102, a detection end of the flaw detection structure 102 faces an axial direction parallel to the rollers 101, the rollers 101 are utilized to facilitate the movement of the detection apparatus on the surface of an object to be detected, and when the detection apparatus moves along the length direction of a weld joint, the detection apparatus can play a guiding role under the action of the rollers 101.

As shown in fig. 3, the flaw detection structure 102 includes a mounting plate 103, and the mounting plate 103 is parallel to the lower surface of the bottom of the base 120. The mounting plate 103 is coaxially and fixedly connected with a mounting shaft 104, and the mounting shaft 104 is rotatably connected to a base 120 through a rolling bearing 105. The lower surface of the base 120 is provided with a mounting groove 106 for interference fit with the rolling bearing 105.

As shown in fig. 3, the mounting shaft 104 is hollow, and a fixing shaft 107 is coaxially inserted therein. The upper end of the fixing shaft 107 extends into the mounting groove 106 and is screw-coupled with the base 120. A fixed gear 119 is coaxially and fixedly connected to the lower end of the fixed shaft 107. The fixed gear 119 is located below the mounting plate 103.

As shown in fig. 3, the mounting plate 103 is eccentrically and rotatably connected with a mounting gear 108, the fixed gear 119 and the mounting gear 108 have the same number of teeth, the mounting plate 103 is rotatably connected with an intermediate gear 109, and the fixed gear 119 and the mounting gear 108 are meshed with the intermediate gear 109. The base 120 is connected with a driving structure 110 for driving the mounting plate 103 to rotate. The driving structure 110 drives the mounting disc 103 to rotate, and the mounting disc 103 rotates to drive the mounting gear 108 to revolve, so that the mounting gear 108 performs circular motion; since the mounting gear 108 is engaged with the intermediate gear 109 and the intermediate gear 109 is engaged with the fixed gear 119, the mounting gear 108 rotates once with respect to the mounting plate 103, which does not rotate the mounting gear 108 with respect to the base 120. One end of the mounting gear 108, which is far away from the mounting disc 103, is connected with the angle probe 111, so that the front of the angle probe 111 always faces to one direction in the revolution process.

As shown in fig. 3, the driving structure 110 includes a first worm gear 112 coaxially and fixedly connected to the mounting shaft 104, and a second worm gear 113 coaxially and fixedly connected to the roller 101. The base 120 is rotatably connected with a worm 114, two ends of the worm 114 are respectively engaged with the first worm wheel 112 and the second worm wheel 113, and the base 120 is fixedly connected with a servo motor 115 for driving the worm 114 to rotate. The servo motor 115 drives the worm 114 to rotate, the worm 114 simultaneously drives the first worm wheel 112 and the second worm wheel 113 to rotate, and the first worm wheel 112 rotates to drive the mounting disc 103 to rotate, so that the circular motion of the inclined probe 111 is realized; the second worm wheel 113 rotates to drive the roller 101 to rotate, and the detection device can move in a linear motion, which drives the oblique probe 111 to move along the length direction of the welding seam.

As shown in fig. 3, the first worm wheel 112 and the second worm wheel 113 have the same number of teeth, and the ratio of the revolving circumference of the mounting gear 108 to the circumference of the roller 101 is equal to pi: 1. the movement track of the oblique probe 111 on the workpiece to be detected is spiral, and the points of two adjacent circular movements in the movement track are overlapped, so that each point of the welding seam is detected for three times, and the defect points of the welding seam are prevented from being missed by multiple times of detection.

The specific working principle of this embodiment is as follows: the servo motor 115 drives the roller 101 and the mounting disc 103 to synchronously rotate, and the mounting disc 103 rotates to drive the mounting gear 108 to revolve, so that the inclined probe 111 makes circular motion; since the mounting gear 108 is meshed with the intermediate gear 109 and the intermediate gear 109 is meshed with the fixed gear 119, the mounting gear 108 rotates once with respect to the mounting plate 103, which does not rotate the mounting gear 108 with respect to the base 120, thereby always orienting the probe in one direction. The rotation of the roller 101 allows the linear movement of the detection device, which drives the angle probe 111 to move along the length of the weld. Circular motion and linear motion are combined, so that the motion track of the inclined probe 111 is spiral, the weld joint can be repeatedly detected by the motion track, repeated detection can be completed only by moving along the weld joint once, the step of repeated detection can be omitted, and the detection efficiency is improved.

Example 3: as shown in fig. 4, an ultrasonic testing system for a pressure vessel disclosed in the present invention includes an ultrasonic testing apparatus 100 and an auxiliary apparatus 116 according to embodiment 2. The ultrasonic flaw detection apparatus 100 is located outside the pressure vessel, and the auxiliary apparatus 116 is located inside the pressure vessel.

As shown in fig. 4, a first U-shaped magnet 117 is fixedly connected to a base 120 of the ultrasonic flaw detection apparatus 100, a magnetic pole of the first U-shaped magnet 117 faces one end of the pressure vessel, and the first U-shaped magnet 117 is fixedly connected to a middle position of the base 120, and the magnetic poles thereof are respectively located on both sides of the flaw detection structure 102.

As shown in fig. 4, the auxiliary device 116 includes a cart 121, the cart 121 is fixedly connected with a second U-shaped magnet 118, the second U-shaped magnet 118 faces the ultrasonic flaw detection apparatus 100, the N-th order of the first U-shaped magnet 117 is aligned with the S-th order of the second U-shaped magnet 118, and the S-th order of the first U-shaped magnet 117 is aligned with the N-th order of the second U-shaped magnet 118. The magnetic induction lines between the first U-shaped magnet 117 and the second U-shaped magnet 118 are denser, the magnetic force between the first U-shaped magnet 117 and the second U-shaped magnet 118 is increased, and the ultrasonic flaw detection device 100 and the auxiliary device 116 are always abutted against the pressure container by utilizing the magnetic force between the first U-shaped magnet 117 and the second U-shaped magnet 118, so that the nondestructive testing is more labor-saving.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications without inventive contribution to the present embodiment as required after reading the present specification, but all of them are protected by patent law within the scope of the present invention.

Claims

1. An ultrasonic flaw detection method mainly comprises the following steps:

s3: performing flaw detection, namely enabling the angle probe (111) to abut against the surface of an object to be detected, aligning the front of the angle probe (111) with a welding seam, and then moving the angle probe (111) along the length direction of the welding seam; when the welding seam is detected to have defects, the positions with the defects are marked, and then the detection is continued until the whole welding seam is detected;

s4: the method comprises the steps of accurately positioning, namely, utilizing the inclined probe (111) to be close to the position marked by S3, changing the distance and the angle between the inclined probe (111) and a welding line to find the highest point of an echo of an ultrasonic flaw detector, positioning the position and the depth of a flaw through the ultrasonic flaw detector, and recording the position and the depth of the flaw;

the method is characterized in that: in S3, the inclined probe (111) linearly moves along the length direction of the welding seam and simultaneously performs circular motion, and the circle center of the circular motion is positioned on the moving motion track of the inclined probe (111) along the length direction of the welding seam; in S3, the ratio of the linear movement distance of the tilt probe (111) to the circular movement distance thereof per unit time is 1: and pi.

2. The ultrasonic flaw detection method according to claim 1, characterized in that: and (3) coating the couplant on the surface of the object to be detected before S3, and avoiding coating the couplant when the inclined probe (111) is contacted with the object to be detected.

3. An ultrasonic flaw detection apparatus using the ultrasonic flaw detection method according to any one of claims 1 to 2, characterized in that: including base (120), base (120) bottom is rotated and is connected with mounting disc (103) rather than the lower surface parallel, the eccentric rotation of one end that mounting disc (103) deviate from base (120) has installation gear (108), the one end that installation gear (108) deviate from mounting disc (103) is provided with oblique probe (111), base (120) fixedly connected with fixed axle (107), fixed axle (107) are coaxial rotation with mounting disc (103) and are connected, the coaxial fixedly connected with fixed gear (119) of fixed axle (107), mounting disc (103) rotate be connected with fixed gear (119) and installation gear (108) equal engaged with intermediate gear (109), the number of teeth of fixed gear (119) and installation gear (108) is the same, be provided with drive structure (110) on base (120), drive structure (110) drive mounting disc (103) rotate.

4. An ultrasonic flaw detection apparatus according to claim 3, characterized in that: the base (120) is rotatably connected with a roller (101), and the orientation of the inclined probe (111) is parallel to the axial direction of the roller (101).

5. The ultrasonic flaw detection apparatus according to claim 4, characterized in that: drive structure (110) include first worm wheel (112) of coaxial fixed connection in mounting disc (103), the coaxial fixedly connected with second worm wheel (113) of gyro wheel (101), base (120) rotate and are connected with worm (114), worm (114) both ends mesh with first worm wheel (112) and second worm wheel (113) respectively, base (120) fixedly connected with drive worm (114) pivoted servo motor (115).

6. The ultrasonic flaw detection apparatus according to claim 4, characterized in that: the ratio of the revolution circumference of the mounting gear (108) to the circumference of the roller (101) is equal to pi: 1.

7. the ultrasonic flaw detection system for the pressure container is characterized in that: the ultrasonic flaw detection device (100) comprises the ultrasonic flaw detection device (100) as claimed in any one of claims 3 to 6, wherein a first U-shaped magnet (117) is arranged on a base (120) of the ultrasonic flaw detection device (100), and a magnetic pole of the first U-shaped magnet (117) faces one end of the pressure container.

8. The ultrasonic inspection system of claim 7, wherein: still include auxiliary device (116), auxiliary device (116) and ultrasonic inspection detection device (100) are located inside and outside the pressure vessel respectively, auxiliary device (116) include dolly (121), dolly (121) fixedly connected with second U-shaped magnet (118), second U-shaped magnet (118) are towards ultrasonic inspection detection device (100), the S level of second U-shaped magnet (118) is aimed at to the N level of first U-shaped magnet (117), and the N level of second U-shaped magnet (118) is aimed at to the S level of first U-shaped magnet (117).