JPH0328375Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ultrasonic flaw detection probe for inspecting specially shaped bolts assembled to a member. First, FIG. 1 shows a specially shaped bolt to be inspected and the state in which the bolt is assembled into a member.

This bolt 1 has a male thread 1a formed on the lower outer periphery, a flange 1b formed on the center outer periphery, and a slit 1c extending in the axial direction from the upper end to the center. This bolt 1 is attached to a member 2 with a washer 3.
By tightening the nut 4 through the flange 1b, the nut 4 and the flange 1b are fixed, and the head of the bolt 1 is fitted into the member 5. This bolt 1
is used to position the members 2 and 5, and the slit 1c acts as a spring to absorb "wobble" between the members 2 and 5.

In the bolt 1 assembled in this way, the soundness of the bolt 1, that is, the flange roots a and b
When examining the presence or absence of defects by ultrasonic flaw detection, since the bolt 1 is buried within the members 2 and 5, it is necessary to inject ultrasonic waves from the bolt head tip 1d or the slit surface 1e.

However, the method of injecting ultrasonic waves from the bolt head tip 1d does not have an appropriate direction of incidence. That is, it is known that the direction in which the defect occurs at the flange root portions a and b is about 45 degrees, based on stress analysis of the bolt 1 and investigation of the damaged product. Therefore, even if an ultrasonic wave hits this defect, the direction of reflection is deviated by about 90 degrees from the direction of incidence, making it difficult to receive it.

On the other hand, in the method of injecting ultrasonic waves from the slit surface 1e, as shown in FIG. The light is reflected from the bolt outer circumferential surface 1f and is received by the vibrator 8.

However, this method requires that the corner 1g of the flange has a shape that is theoretically easy to reflect, and that in this type of bolt 1, the beam path (ultrasonic propagation time) of the corner 1g of the flange is an expected defect. 6, there is a problem in that a pseudo echo U' occurs with the corner 1g of the flange as a reflection source.

In other words, the ultrasonic waves emitted from the transducer 8 are directed by the wedge 7, and are directed toward the bolt 1, which is the object to be inspected.
It bounces on the outer peripheral surface 1f of d and reaches the flange roots a and b. If there is a defect 6 here, the ultrasonic wave is reflected on the defect surface and is received by the transducer 8 as an echo through the same path. However, at this time, since the ultrasonic beam has a spread that depends on the dimensions and frequency of the transducer 8, a portion of the ultrasonic beam travels straight without bouncing on the outer peripheral surface 1f. This ultrasonic wave U' reaches the corner 1g of the flange, where a reflected wave is generated, and an echo that is confused with the reflected wave from the defect 6 is transmitted to the transducer 8.
received at

Note that even when there is a single transducer, that is, when the transducer serves as both transmitter and receiver, it is possible to set an angle and position that will not receive false echoes, but the reflectance from the defect is determined by the condition that the sound waves are perpendicular to the defect. is the maximum, and decreases as the inclination increases, resulting in a decrease in defect detection ability due to reflectance.

The present invention was made in view of the above circumstances, and its purpose is to provide an ultrasonic flaw detection probe that can reliably inject ultrasonic waves and does not receive false echoes.

That is, in the present invention, a slit is formed along the axial direction from one end to the center, a flange is formed on the outer periphery of the center, and a male thread is formed on the outer periphery of the other end, and the bolt is inserted into the slit. In the ultrasonic flaw detection probe for inspecting defects at the base of the flange of the male thread, two leaf springs protrude in a curved shape from the probe body, and the frame is connected to the frame through the rotating shaft. A rotary stopper is provided between the probes, and a probe rotatably provided in a specific range is attached to each probe, and a transmitting transducer and a receiving transducer are attached to the probes before and after the ultrasonic wave transmitting/receiving direction. This is an ultrasonic flaw detection probe in which the two transducers are arranged via wedges, and a sound-insulating partition plate is further arranged between the two transducers.

The present invention will be described below with reference to illustrative embodiments.

FIG. 3 shows a plan view of the ultrasonic flaw detection probe. This probe has a probe body 11
A frame portion 12 is formed in the frame portion 12 .
Both ends of leaf springs 13, 13 are attached to both sides of the plate springs 13, 13. The leaf spring 13 is provided so as to protrude in a curved shape from the frame portion 12, as shown in FIG. Furthermore, a probe 15 reinforced with a probe case 14 is attached within the frame portion 12 via a rotating shaft 16. A rotary stopper 14a projects from the probe case 14, as shown in FIG. 5, and is inserted into a groove 12a formed in the frame portion 12. This rotation stopper 14a is for suppressing rotation of the probe 15 in the direction of the arrow to the necessary minimum. In the figure, 17 is a probe holder, and 18 is a coaxial cable connected to an ultrasonic flaw detector.

Furthermore, as shown in FIG. 8, the probe 15 has a transmitting transducer 20 independently disposed in the transmitting wedge 19 at the front, and a receiving transducer 22 independently disposed in the receiving wedge 21 at the rear. A partition plate 23 is interposed between these wedges 19 and 21. This partition plate 23 prevents the transmitting vibrator 20 from directly propagating to the receiving vibrator 22 through the wedges 19 and 21.

The purpose of having separate transducers for transmitting and receiving is to reduce dead zones (areas near the probe that cannot be detected due to the influence of transmitted waves) when detecting flaws on thin metal plates, or to detect defects in specific areas. It is known for the purpose of increasing the intensity of sound waves. However, these methods are not intended to reduce false echoes as in the present invention.

Next, the operation of this ultrasonic flaw detection probe will be explained.

As shown in FIGS. 6 and 7, when the probe is inserted into the slit 1c of the bolt 1, the leaf spring 1
3 and 13 hit the slit surface 1e', and this reaction brings the probe 15 into close contact with the slit surface 1e on the opposite side. Further, since the probe 15 is supported by the frame portion 12 by the rotating shaft 16, the plate spring 13,
13 is applied uniformly to each surface of the probe 15. During the inspection work, it is assumed that the slit 1c is filled with water or the like as an ultrasonic propagation medium, or is coated with water or the like.

In the probe inserted into the slit 1c, when an ultrasonic wave is transmitted from the transmitting transducer 20 as shown in FIG.
, and after bouncing on the bolt outer peripheral surface 1f, it reaches the flange root b. Here, if there is a defect 6 in the flange root b, the ultrasonic wave is reflected at the defect, bounces on the bolt outer peripheral surface 1f, passes through the wedge 21, and passes through the receiving transducer 22.
is received as a defective echo.

On the other hand, some of the ultrasonic waves that travel straight without bouncing on the bolt outer peripheral surface 1f are reflected at the flange corner 1g. However, since the receiving transducer 22 is shifted toward the head side of the slit 1c, the ultrasonic wave reflected from the corner 1g of the flange is blocked by the flange 1b and disappears, so that the receiving transducer 22 cannot receive it. Prevented.

As described above, the ultrasonic flaw detection probe is inserted into the slit and the ultrasonic waves are incident obliquely from there.
Ultrasonic waves can be directed in an appropriate direction to the defect at the base of the flange and the direction of the defect.

Furthermore, by making the transmitting transducer and the receiving transducer independent and shifting their arrangement positions, pseudo echoes whose reflection sources are at the corners of the flange disappear, making it easier to detect defects at the base of the flange.

Furthermore, due to the action of the leaf spring and the rotatable support of the probe, the contactor adheres uniformly to the slit surface, and the ultrasonic waves emitted from the transducer are reliably propagated to the test object, resulting in stable inspection. It has remarkable effects, such as making it possible to

The probe according to the present invention can also be used to inspect bolts with slits formed without flanges, and can be applied even when the bolts are not buried.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the specially shaped bolt that is the object to be inspected and its installation state, Fig. 2 is an explanatory diagram of the operation of a general ultrasonic flaw detection probe inserted into a slit,
Fig. 3 is a partially cutaway plan view of an ultrasonic flaw detection probe showing an embodiment of the present invention, and Fig. 4 is a -
5 is a sectional view taken along the - line in FIG. FIG. 3 is an explanatory diagram showing a state in which the same probe is used to detect defects at the base of a flange of a bolt. 1...Bolt, 1a...Male thread, 1b...Flange, 1c...Slit, 1d...Bolt head tip, 1e...Slit surface, 1f...Bolt outer circumferential surface, 1g...Flange corner, 2,5 ...Parts, 3
... washer, 4 ... nut, 6 ... defect, 7 ... wedge, 8 ... vibrator, 11 ... probe body,
12... Frame portion, 12a... Groove, 13... Leaf spring, 14... Probe case, 14a... Rotation stopper, 15... Probe, 16... Rotating shaft, 1
7... Probe holder, 18... Coaxial cable, 19... Transmitting wedge, 21... Receiving wedge, 20... Transmitting transducer, 22... Receiving transducer, 23... Partition plate.

Claims (1)

[Scope of utility model registration request] A slit is formed along the axial direction from one end to the center, a flange is formed on the outer periphery of the center, and a male thread is formed on the outer periphery of the other end. In an ultrasonic flaw detection probe that inspects defects at the base of a part, a frame formed on the probe body has two leaf springs protruding from the body in a curved manner, and a rotating shaft is inserted between the frame and the rotating shaft. A stopper is provided and a probe rotatably provided in a specific range is attached to each probe, and a transmitting transducer and a receiving transducer are attached to the probe through wedges at the front and back of the ultrasonic transmission and reception direction. an ultrasonic flaw detection probe, further comprising a sound-insulating partition plate arranged between both the vibrators.