KR100923313B1 - Bubbler for ultrasonic inspection - Google Patents

Abstract

The present invention relates to a bubbler for ultrasonic inspection by applying a local immersion method to a product that is impossible or ineffective in the ultrasonic inspection of the composite material, the hollow body having an opening and an inlet; One side is coupled to the body along the circumference of the opening, and the other side in contact with the ultrasonic flaw body first brush formed with a plurality of slot-shaped first gap from the end to the adjacent surface; It provides an ultrasonic flaw bubbler comprising a; ultrasonic probe installed to contact the water supplied into the body.

Ultrasonic Examination, Bubbler, Local Immersion, Composites, Delamination, Unbonded

Description

Ultrasonic Bubbler {BUBBLER FOR ULTRASONIC INSPECTION}

The present invention relates to a bubbler for ultrasonic flaw detection by applying a local immersion method to a product that is impossible or ineffective for total immersion during the ultrasonic flaw detection of the composite material.

For the inspection of composites, X-ray imaging has been mainly used. However, the X-ray imaging method has a weak point in that it is difficult to detect when the gap of defects is not large or close in detecting the separation between layers and non-adhesion.

In order to solve this problem, ultrasonic inspection is applied. In ultrasonic examination of the composite, the pulse echo method was applied, and the contact A-scan examination was mainly performed. However, the composite material has irregular signals due to micropores or microlayer separation inside the fabric and the characteristics of the material, A-scan inspection method is not suitable for a large area inspection.

Therefore, there is a need for a C-scan inspection method that automatically scans the entire area of the EUT based on the pulse echo method. C-scan inspection makes it easy to determine the location and size of the defects, and also provides A-scan signal information for specific defects, so that the depth and type of defects can be determined. However, the surface of the composite material is not only smoother than the metal material, but also has a severe shape error. Therefore, C-scan testing of composites using contact transducers is not easy.

Therefore, it is more effective to apply the immersion method in which the specimen and the probe are submerged in water. However, in the case of the total immersion method, the composite material is immersed in water during the inspection time, so that moisture may penetrate into the material and adversely affect the physical properties or performance.

Therefore, a test method that has the same degree of total immersion and inspection effect and suppresses or minimizes the penetration of water is required, and it is a local immersion method using a bubbler that satisfies this. The local immersion method is a method of forming and inspecting a local water curtain between an ultrasonic probe and a test article, and water is supplied to the site to be examined. The bubbler is inspected while moving at a constant speed, so there is little opportunity for water to penetrate into and out of the EUT.

In 2004, "Testing Device for the Ultrasonic Inspection of Barstock," registered in US Patent (US-6,739, 188) by Reinhard Prause, produced a bubbler using a local immersion method for testing pipes. The bubbler used was formed in the form of a pipe wrapped, the outer diameter of the pipe is larger than the pipe, the water is continuously supplied into the bubbler, and the continuous scanning method by local immersion method in the longitudinal direction of the pipe. And, the pipe is continuously inspected while being inserted and moved into the bubbler. However, the above case is not suitable for the application of large diameter test specimens.

In addition, the 1994 "Ultrasonic Booted Head Probe for Rotor Bore Inspection", a European patent (EP 0 622 629), issued by Quinn, James R., describes the entrance of a bubbler filled with the transducer and the inside to inspect the rotor bore. It was tested by making a bubbler in the form of a rubber bag attached to the site in contact with the test body. In addition, the liquid supplied into the bubbler maintains a constant pressure so that the rubber bag is kept in a constant shape. However, this bubbler is concerned about the ultrasonic attenuation loss due to the rubber membrane, and is disadvantageous for the inspection of test specimens with large self-damping of materials such as composite materials. In particular, the composite material is somewhat rougher than the metal material, and the surface of the material is somewhat rough, there is a gap between the test specimen and the rubber film is expected to be less effective inspection.

The present invention has been made to solve these conventional problems, the object of the present invention,

1) Provides a bubbler capable of ultrasonic flaw detection even in the case of a composite material having a rougher surface and a curved surface than a metal material,

2) provides a bubbler capable of ultrasonic flaw detection even in the case of a large diameter test specimen (hereinafter referred to as a "probe"),

3) In the ultrasonic examination of the test specimen, a small local water curtain is formed between the ultrasonic probe and the test specimen, and the water curtain is well maintained during the test due to good contact and sealing property with the test specimen, and the rotation or axial direction of the test specimen during the inspection scan. Due to the movement, it provides a bubbler that actively maintains good adhesion even in the case of small-scale shape changes (diameter error, surface smoothness difference, etc.) of the test body,

4) Do not generate bubbles or bubbles that interfere with the inspection while conducting a moving test along the test specimen or supplying water into the bubbler.

5) It provides a bubbler that can prevent the performance degradation of the material due to moisture penetration generated when the test specimen is immersed in water and reduce the amount of water required.

6) It is to provide a bubbler that can obtain a test effect comparable to the immersion method.

In order to achieve these objects, the present invention is a hollow body formed with an opening and an inlet; One side is coupled to the body along the circumference of the opening, and the other side in contact with the ultrasonic flaw body first brush formed with a plurality of slot-shaped first gap from the end to the adjacent surface; It provides an ultrasonic flaw bubbler comprising a; ultrasonic probe installed to contact the water supplied into the body.

In addition, the ultrasonic flaw bubbler of the present invention is installed to overlap along the inner circumference of the first brush, one side is coupled to the one side of the first brush, the other end in contact with the ultrasonic flaw end In addition, may further include a second brush formed with a plurality of slot-shaped second gaps to reach the adjacent surface.

In addition, the ultrasonic flaw bubbler of the present invention may further include a support for supporting the body through a plurality of buffer springs.

In addition, the ultrasonic flaw detection bubbler of the present invention, the water supply unit for supplying water into the body through the water inlet, the water receiving unit receiving the water drained through the first gap, and the water receiving unit It may also include a circulation pump for supplying water to the water supply.

According to the invention,

First, a specially designed brush can be applied to the ultrasonic flaw bubbler used in the local immersion method to improve the contact and sealability of the specimen.

Second, it is possible to improve the active adhesion of the bubbler according to the shape change of the test body by connecting between the body of the bubbler and the support with a buffer spring.

Third, compared to the test of the composite by the total immersion method to minimize the water penetration that adversely affects the material, and significantly reduce the amount of water supplied and at the same time the inspection effect can be obtained almost the same effect as the total immersion method.

Fourth, by forming a slot-like gap in the brush to form a veil of water between the test body and the bubbler while allowing some to be naturally drained, the water drainage can be further reduced by receiving the natural drained water and refueling it with a circulation pump. have.

Fifth, the inlet of the water supplied into the bubbler, the gap of the brush in which drainage occurs, and the position of the air outlet for discharging the air in the bubbler can be properly disposed to minimize the formation of vortices and bubbles that hinder flaw detection.

Sixth, by using the ultrasonic flaw bubbler of the present invention, it is possible to increase the quality assurance effect on the ultrasonic flaw detection of the composite material, it is expected to contribute to the improvement of the quality of the test body.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode of carrying out the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, the ultrasonic flaw bubbler according to an embodiment of the present invention includes a hollow body 10, a first brush 20, and an ultrasonic probe 40.

The hollow body 10 may be manufactured in various shapes, in this embodiment it is made of a hollow cylinder. The body 10 is preferably made of acrylic so that the inside looks transparent. An opening is formed at an upper portion of the body 10, and an inlet 12 for water inflow is formed at one side thereof to receive water from an external water supply unit (not shown). At this time, the water supply line from the water supply to the body 10 is provided with a flow rate control valve to adjust the amount of water. Drained water can be stored and stored in the bottom of the water support (70 in Fig. 3) installed in the bottom, it can be re-supplied by supplying the water stored in the water support to the water supply through a circulation pump (not shown) have. On the other hand, it is preferable to form an air outlet 13 in the upper portion of the body 10 so that the air flowing in the water supply can be discharged well.

One side (lower portion of the drawing) of the first brush 20 is coupled to the body by an adhesive or the like along the opening circumference of the body 10 and the other side (upper portion of the drawing) in contact with the ultrasonic flaw S As shown in Fig. 2, a plurality of slot-shaped first gaps 21 are formed so as to reach adjacent surfaces at their ends. Accordingly, the first brush 20 has a brush shape, and when the first brush 20 is in contact with the ultrasonic flaw (S), the first brush 20 is in close contact with each other, and even if the ultrasonic flaw (S) is bent, deformation without great resistance is possible. The first gap 21 may be formed in the width direction (vertically in the drawing) of the first brush 20 or may be formed in the diagonal direction. As such, the first gap 21 in the form of a slot is formed in the first brush 20 to form a membrane of water between the ultrasonic flaw S and the bubbler while allowing some of the water to be naturally drained. The first brush 20 preferably has an annular cross-sectional shape, and may be made of a rubber material.

Although the effect of the present invention can be achieved to some extent with the first brush 20 alone, as a more preferred embodiment, the ultrasonic flaw bubbler of the present invention has a second brush 30 as shown in FIGS. 1 and 2. ) Is better to include. The second brush 30 is installed to overlap along the inner circumference of the first brush 20, one side (lower in the drawing) is coupled to the one side of the first brush 20 by an adhesive or the like. On the other side (upper part in the drawing) in contact with the ultrasonic flaw detection body, a plurality of slot-shaped second gaps 31 are formed so as to reach an adjacent surface from an end thereof. The first and second brushes 20 and 30 are freely in contact with each other except for the coupling portion, and are installed to naturally have a gap when an external force is applied. The second brush 30 also preferably has an annular cross-sectional shape, and may be made of a rubber material.

In the present embodiment, the first and second brushes 20 and 30 of rubber material having a thickness of 1.5 mm are overlapped each other, and each of the brushes 20 and 30 has a slot shape of 7 mm in length. The gaps 21, 31 were made to allow some of the water supplied into the body 10 to drain naturally.

As shown in FIG. 2, the first gap 21 and the second gap 31 are formed to be offset from each other so as not to coincide with each other at a specific position, so that the ultrasonic flaw S and / or the bubbler move. It is preferable to prevent water from flowing out to the outside through the first and second gaps 21 and 31.

Looking at the discharge path of the water with reference to Figure 2, the water filled in the body 10 exits the second gap 31 of the second brush (30) between the first and second brushes (20, 30) Flows in the circumferential direction, and this water is discharged out through the first gap 21 of the first brush 20.

On the other hand, the ultrasonic transducer 40 is installed to contact the water supplied into the body (10). In the present embodiment, the ultrasonic transducer 40 is inserted into the through hole formed in the body 10 with the rubber ring 41 fitted on its outer surface. The rubber ring 41 prevents water inside the body 10 from leaking into a gap between the ultrasonic transducer 40 and the body 10.

In addition, as shown in Figure 1, the ultrasonic flaw bubbler of the present invention preferably further includes a support 60 for supporting the body 10 through a plurality of buffer spring (50). Specifically, one end of the sliding bar 55 is fixedly coupled to the body 10, the other end is penetrated through a through hole formed in the support 60, the end is coupled with a nut or the like having a larger diameter than the through hole. The buffer spring 50 surrounds the outer circumferential surface of the sliding bar 55. Accordingly, it is possible to actively maintain adhesion to the shape change of the ultrasonic flaw (S) during scanning.

3 is a schematic diagram showing a method of ultrasonically inspecting a composite specimen (S) using the ultrasonic flaw bubbler of the present invention. The bubbler is brought into close contact with the test object S so that the end of the first brush 20 is slightly bent outward. In this case, when the above-described second brush is used, the tip of the second brush is also slightly bent outward. A veil of water is formed between the ultrasonic transducer 40 and the test specimen S, and the veil of water can be maintained even when there is motion during the scan. At the time of inspection, the test object (S) mounted on the roller moves in the circumferential direction, and the bubbler moves in the axial direction (the direction perpendicular to the ground). If the test site is narrow and it is difficult to install the transfer bridge 80, the bubbler may be tested by installing an axial transfer rail and a transfer device under the test object S (indicated by the dotted line in the drawing). The frequency of the ultrasonic transducer 40 to be applied uses a range of 1.0 to 3.5 MHz depending on the thickness of the composite.

Figure 4 is a graph showing the A-scan signal detected at the top of the FRP (Fiber glass Reinforced Plastic) of the composite by a local immersion method using the bubbler of the present invention. The horizontal axis is the composite thickness or time axis, and the vertical axis is the relative sound pressure intensity axis of the signal. Below the composite surface signal 101 is a fine noise signal 102, which is a signal exhibited by the fine pores and fine interlayer separation inherent in the composite fabrication. These signals are meaningless from the structural point of view of the material. Then, the signal 103 reflected at the interface at the position where the FRP / rubber is interfaced appears. This is the signal magnitude at normal adhesion.

Figure 5 is a graph showing the A-scan signal detected at the FRP interlayer separation site of the composite by a local immersion method using the bubbler of the present invention. Between the composite surface signal 104 and the FRP / rubber interface signal is shown a signal 105 indicating interlayer separation in the FRP layer. At this time, the interlayer separation represents a signal size of about 100%, and when the gate height 106 for the C-scan is set to 50%, effective defects excluding the fine interlayer separation and pore signal noise inherent in the composite fabrication A signal for may be obtained.

Figure 6 is a graph showing the A-scan signal observed at the FRP / rubber non-bonded portion of the composite by a local immersion method using a bubbler of the present invention. Under the composite surface signal 107 there is no distinct signal corresponding to the FRP interlayer separation, and the unbonded signal 108 reflecting at the interfacial location of the FRP / rubber appears. This is a signal value of about 2.3 ± 0.3 times higher than the signal magnitude at normal adhesion. This signal difference is used to determine whether there is any adhesion. At this time, the gate height 109 for the C-scan is set to a height above the normal adhesion signal.

7 is a diagram showing an ultrasound C-scan image of the local immersion method using a bubbler of the present invention. The upper C-scan image shows the interlayer separation defect 110 existing inside the composite, and the lower C-scan image shows the non-adhesive defect 111 between FRP / rubber.

8 is a graph comparing the A-scan signal detected at the FRP interlayer separation site of the composite material by the local immersion method and the total immersion method using the bubbler of the present invention. The magnitude of the interlayer separation signal 112 of the local immersion method using the bubbler and the interlayer separation signal 113 of the total immersion method are almost the same. Therefore, it can be seen that the signal sensitivity of the detected defect is almost equivalent.

9 is a diagram comparing the C-scan composites by the local immersion method and the total immersion method using the bubbler of the present invention. It can be seen that the C-scan image 114 of the local immersion method using the bubbler and the C-scan image 115 of the total immersion method are almost the same, and the detection sensitivity of the defect is almost equal.

In the above experiments, the ultrasonic flaw detection method of the composite material using the bubbler of the present invention showed a similar effect to the defect detection sensitivity in the total immersion method, and the adverse effect of the water penetration into the test specimen in the total immersion method problem. It can be removed, and the amount of water supplied can be significantly reduced, resulting in an economic effect.

In the above, the present invention has been described with reference to the illustrated examples, which are merely examples, and the present invention may be embodied in various modifications and other embodiments that are obvious to those skilled in the art. Understand that you can.

1 is a cross-sectional view (top) and a plan view (bottom) of the ultrasonic flaw bubbler according to an embodiment of the present invention,

2 is a perspective view of the first and second brushes constituting the bubbler shown in FIG. 1, FIG.

3 is a schematic view showing a method of ultrasonically inspecting a composite specimen using the ultrasonic flaw bubbler of the present invention;

4 is a graph showing the A-scan signal observed at the FRP normal region of the composite by a local immersion method using the bubbler of the present invention,

5 is a graph showing the A-scan signal detected at the FRP interlayer separation site of the composite material by the local immersion method using the bubbler of the present invention,

6 is a graph showing the A-scan signal observed at the FRP / rubber non-bonded site of the composite material by the local immersion method using the bubbler of the present invention,

7 is a diagram showing an ultrasound C-scan image of the local immersion method using a bubbler of the present invention,

8 is a graph comparing the A-scan signal observed at the FRP interlayer separation site of the composite material by the local immersion method and the total immersion method using the bubbler of the present invention,

9 is a diagram comparing the C-scan composites by the local immersion method and the total immersion method using the bubbler of the present invention.

Claims (8)

A hollow body formed with an opening and an inlet; One side is coupled to the body along the circumference of the opening, and the other side in contact with the ultrasonic flaw body first brush formed with a plurality of slot-shaped first gap from the end to the adjacent surface; It is installed so as to overlap along the inner circumference of the first brush, one side is coupled to the one side of the first brush, the other side in contact with the ultrasonic flaw body in the slot-like second gap so as to reach the adjacent surface A plurality of second brushes formed; An ultrasonic probe installed in contact with the water supplied into the body; And a support for supporting the body through a plurality of shock absorbing springs. The first brush and the second brush is made of a rubber material having an annular cross-sectional shape, The first gap and the second gap are formed to be offset from each other so as not to coincide with each other at a specific position,  Ultrasonic flaw bubbler, characterized in that the body is formed with an air outlet for discharging the air inside the body. delete delete delete The ultrasonic flaw bubbler according to claim 1, wherein the ultrasonic probe is inserted into a through hole formed in the body while a rubber ring is fitted on an outer surface thereof. delete delete The water supply unit of claim 1, wherein the water supply unit supplies water into the body through the water inlet, the water support unit receiving the water drained through the first gap, and the water stored in the water support unit to the water supply unit. Ultrasonic flaw bubbler comprising a circulation pump for supplying.

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