JP2006010342A - Ultrasonic flaw detecting method and ultrasonic flaw detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To well keep flaw detection precision even if the quality of water in a water tank is deteriorated and dust, air bubbles and the like in water are present. <P>SOLUTION: Ultrasonic waves 6 are entered into the matter 3 wholly or partially immersed in water in the water tank to detect the flaw of the matter 3 in a non-contact state and clean water W1 is ejected in the propagation route of ultrasonic waves 6 to exclude the water in the water tank in the propagation route by the ejected water and ultrasonic waves 6 are entered into the matter 3 while isolating the matter 3 from the water in the water tank. By this method, ultrasonic flaw detection can be performed with high reliability and the replacing frequency of the whole of flaw detection water in the water tank to enhance work efficiency. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for flawlessly detecting a defect inside an object using ultrasonic waves, and an apparatus therefor, and more particularly, in water immersion type ultrasonic flaw detection using water as a propagation medium. The present invention relates to an ultrasonic flaw detection method capable of preventing erroneous detection and sensitivity reduction due to poor water quality such as dust and bubbles present therein, and an apparatus for performing the ultrasonic flaw detection method.

  A method for detecting defects existing inside a round bar, square bar, plate, pipe or the like using a non-contact ultrasonic sensor is known. At this time, the ultrasonic sensor is not only fixed at one place on the surface of the object for flaw detection, but it is also moved continuously to automate the inspection or improve the reliability of the collected data. In addition, internal defects that have a serious influence on an object are also diagnosed.

  By the way, when an air layer exists in the propagation path, the ultrasonic wave is reflected by the air layer and hardly passes. Therefore, normally, grease or machine oil is applied to the surface of the object to be flawed, and While the sound wave oscillator is pressed against the air, the air is excluded and ultrasonic waves are incident on the inside of the object.

  However, such a contact method does not cause any problem when the entire inside of the object can be diagnosed from the reflected waveform obtained by the ultrasonic sensor fixed at one place on the object surface, but the flaw detection is performed while scanning the ultrasonic sensor. If it does, it cannot be adopted.

In contrast, in a state where the ultrasonic sensor and the surface of the object are kept at a constant interval, the ultrasonic sensor and the whole or a part of the object are immersed in water in the water tank, and the water in the water tank is used as a propagation medium. Flaw detection methods are also known. In this non-contact method, the inspection is automated or the reliability of collected data is improved by moving an ultrasonic sensor or rotating an object in a spiral shape.
Japanese Utility Model Publication No. 5-4010

  However, in such a non-contact method, when performing defect inspection of an object, there should be no ultrasonic reflection from dust, bubbles, or the like in the propagation medium, water. That is, as shown in FIG. 6, if dust or bubbles 2 are present in the water 1, the dust or bubbles 2 or the like are reflected by the surface of the object 3 after being reflected on the surface of the object 3 as in the flaw detection A scope shown in FIG. 7. This is because, when the sound wave 6 is reflected, the reflected echo G ′ appears in the inspection range and is erroneously determined as a defect existing in the substance 3. In FIG. 7, T represents a transmission pulse, S represents a surface echo, B represents a bottom echo, and G represents a reflected echo directly reflected by dust or bubbles 2.

In addition, refraction of sound waves generated by changes in water temperature is also harmful.
As described above, in ultrasonic flaw detection using water as a propagation medium, it is necessary to maintain good water quality.To that end, a large water tank that can be applied to objects of different shapes and lengths is used. The quality of the water becomes more difficult to manage, causing problems such as misjudging internal defects.

  If an internal defect is erroneously determined due to bubbles contained in the supplied water or dust attached to an object or water tank, reinspection or the like must be performed, and the flaw detection efficiency is significantly reduced. Therefore, especially when performing ultrasonic flaw detection by submerging an object in a large aquarium, from a practical point of view, even if the water quality in the aquarium changes, it maintains a high quality water quality that does not affect the propagation path. There is a demand for technology that can be used.

  Further, in the non-contact method, as described in Patent Document 1, the nozzle 4 as shown in FIG. 8 is often used. However, when the nozzle 4 is used, there is a problem that the reflected echoes Na and Nb generated at the portions indicated by 4a and 4b of the nozzle 4 appear within the inspection range as in the flaw detection A scope shown in FIG. . In addition, 5a in FIG. 8 is a transducer of the ultrasonic probe 5.

  The problem to be solved by the present invention is that when non-contact ultrasonic flaw detection is performed using water as a propagation medium, the quality of the water in the water tank deteriorates. The ultrasonic reflection is affected, and the flaw detection accuracy is deteriorated.

  The inventor has conducted extensive research on methods for performing normal ultrasonic flaw detection even in water of harmful water quality that affects flaw detection when ultrasonic flaw detection is performed using water as a propagation medium. Clean water that does not affect flaw detection by blocking the path from water filled in the aquarium and forming a clean water propagation path that does not adversely affect flaw detection. And found that the object can be achieved, and the following present invention was established.

The ultrasonic flaw detection method of the present invention comprises:
In order to cut off the propagation path of ultrasonic waves from the water filled in the aquarium and to perform normal ultrasonic flaw detection even in harmful water quality that affects flaw detection,
In a method for non-contact flaw detection by making ultrasonic waves incident on an object immersed in water in the water tank in whole or in part,
By ejecting clean water to the ultrasonic wave propagation path, the most important thing is to eliminate the aquarium water in the propagation path by this jet water and to make the ultrasonic wave incident on the object while being isolated from the aquarium water. It is a feature.

  In the ultrasonic flaw detection method of the present invention, if the clean water is ejected at the same temperature as the temperature of the aquarium water, refraction of ultrasonic waves harmful to flaw detection can be eliminated. .

The ultrasonic flaw detector of the present invention is
In order to carry out the ultrasonic flaw detection method of the present invention,
A water tank capable of immersing all or part of the object to be flawed in water;
An ultrasonic sensor that emits ultrasonic waves toward the object that has been immersed in water in the water tank in its entirety or in part;
It has a cylindrical nozzle with this ultrasonic sensor arranged on the proximal side,
The most important feature is that the nozzle is provided with a water channel for ejecting clean water into the nozzle from the base end side of the vibration surface of the ultrasonic sensor.

  In the ultrasonic flaw detection apparatus according to the present invention, if the nozzle has a multilayer structure in which an ultrasonic absorption layer is interposed on the inner surface side, reflected waves from the inner surface of the nozzle that adversely affect flaw detection are removed. Can do. Further, when the tip shape is formed in an acute angle shape with a sharp inner peripheral side, a reflected wave from the nozzle tip portion that adversely affects flaw detection can be removed.

  Further, in the ultrasonic flaw detector of the present invention, when an auxiliary outer cylinder is provided on the outer periphery of the nozzle, harmful water quality intrusion into the nozzle that is the ultrasonic propagation path is more effectively performed. It becomes possible to suppress.

  Further, in the ultrasonic flaw detector of the present invention, when a heat exchanger is used in the middle of the supply water piping system to the nozzle, the temperature of the supply water is the same as the water temperature in the water tank. The method of the present invention can be carried out.

  In the present invention, ultrasonic flaw detection can be performed with high reliability by using clean water as an ultrasonic wave propagation medium and preventing water from entering the water tank harmful to flaw detection. In addition, the frequency of exchanging flaw detection water in the entire aquarium can be reduced, and work efficiency can be improved.

Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.
FIG. 1 is a side view showing a cross section of an essential part of an example of the ultrasonic flaw detector of the present invention, FIG. 2 is a cross section showing the tip of the nozzle of FIG. 1, and FIG. The figure explaining an example of the water supply part of an apparatus, FIG.4 and FIG.5 is a figure explaining the effect of this invention.

  In FIG. 1, reference numeral 11 denotes an ultrasonic sensor that radiates ultrasonic waves 6 to the surface of the object 3 to be flaw-detected. It comes to oppose.

  In the present invention, the water channel 12a is provided so that clean water W1 that is a propagation medium of the ultrasonic wave 6 is ejected into the nozzle 12 from the base end side further than the vibration surface 11a of the nozzle 12.

  In this example, this water channel 12a branches two water channels 12aa and 12ab from the water storage part 12c connected to the water supply port 12b, and one water channel 12aa is sprayed toward the tip of the nozzle 12, for example, spirally, The other water channel 12ab is jetted in the horizontal direction so as to go around the ultrasonic sensor 11, and an air reservoir is prevented from being formed at the rear end on the proximal end side inside the nozzle 12.

  Clean water W1 sprayed into the nozzle 12 from the two water channels 12aa and 12ab fills the nozzle 12 and serves as a propagation medium for the ultrasonic wave 6, while the tip of the nozzle 12 and the object 3 It sprays into a water tank (not shown) from a minute gap of 0.5 to 1.0 mm with the surface 3a, and prevents water W2 in the water tank harmful to flaw detection from entering the nozzle 12.

  In the example shown in FIG. 1, an auxiliary outer cylinder 13 made of, for example, flexible silicon is provided on the outer periphery of the nozzle 12 so that the gap between the surface 3 a of the object 3 and the surface 3 a is 0.5 to 1.0 mm, like the nozzle 12. It is arranged in such a way as to serve as a primary prevention of the entry of the harmful water W2 into the nozzle 12.

  In the example shown in FIG. 1, as shown in the enlarged view of FIG. 2, the nozzle 12 is arranged from its inner peripheral side, for example, an ultrasonic transmission layer 12 d such as acrylic resin, an ultrasonic absorption layer 12 e such as cork, stainless steel, and the like. 3 shows a three-layer structure of a guide layer 12f made of steel or the like that removes harmful ultrasonic reflection from the inner surface of the nozzle 12. Further, it shows a configuration in which the tip shape of the nozzle 12 is formed into an acute angle with a sharp inner peripheral side, thereby removing reflection of ultrasonic waves harmful to flaw detection from the tip of the nozzle 12.

  FIG. 3 shows an example of a water supply unit for supplying clean water W1 to the water supply port 12b of the nozzle 12. Of these, the example shown in (a) shows that the water W2 in the water tank pumped up by the pump 14 is purified to clean water W1 with a filter 10 of 100 to 10μ and then sent to the water supply port 12b of the nozzle 12. Is shown. In this case, needless to say, the temperature of the clean water W1 sent to the water supply port 12b is the same as the temperature of the water W2 in the water tank.

  In the example shown in FIG. 5B, clean water (for example, tap water) W1 from the outside is supplied to the heat exchanger 16 submerged in the water W2 in the aquarium, and the temperature of the water W2 in the aquarium After the temperature is set to be the same as that shown in FIG.

  As described above, when clean water W1 having the same temperature as the water W2 in the water tank is sent to the water supply port 12b of the nozzle 12, a change in water temperature harmful to the ultrasonic wave 6 is effectively suppressed. be able to.

  By the way, by using the ultrasonic flaw detector of the present invention described above, clean water W1 is jetted to the ultrasonic wave propagation path, so that the ultrasonic wave 6 is applied to the object 3 while being isolated from the water W2 in the water tank by this jet water. In the case of flaw detection with incidence, as shown in FIG. 4, there is no dust or bubbles in the ultrasonic propagation path, and as shown in the flaw detection A scope of FIG. No harmful echoes occurred.

  The present invention is not limited to the above example, and it goes without saying that the embodiment may be appropriately changed within the scope of the technical idea described in each claim. For example, in FIG. 3, the nozzle 12 is formed in three layers and the ultrasonic transmission layer 12d is arranged on the innermost surface, but the ultrasonic transmission layer 12d is not always necessary.

  The present invention as described above is not limited to water immersion type ultrasonic flaw detection provided with a large water tank that can be applied to objects of different shapes and lengths, but also water immersion type ultrasonic inspections for objects of substantially the same shape and length. It can also be applied to acoustic flaw detection.

It is a side view which cuts and shows the principal part of an example of the ultrasonic flaw detector of this invention. It is the figure which showed the front-end | tip part of the nozzle of FIG. 1 in cross section. It is a figure explaining an example of the water supply part of the ultrasonic flaw detector of the present invention. It is a figure explaining the effect of this invention. It is the figure which showed the flaw detection A scope in the case of FIG. It is a figure explaining the problem when garbage, a bubble, etc. exist in the middle of an ultrasonic propagation path. It is the figure which showed the flaw detection A scope in the case of FIG. It is a figure explaining a general nozzle. It is the figure which showed the flaw detection A scope at the time of using the nozzle of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Object 3a Surface 6 Ultrasonic 11 Ultrasonic sensor 12 Nozzle 12a Water channel 12e Ultrasonic absorption layer 13 Auxiliary outer cylinder 16 Heat exchanger

Claims (7)

In a method for non-contact flaw detection by making ultrasonic waves incident on an object immersed in water in the water tank in whole or in part,
By ejecting clean water into the ultrasonic wave propagation path, the jet water removes aquarium water in the propagation path, and ultrasonic waves are incident on the object while being isolated from the aquarium water. Ultrasonic flaw detection method.   2. The ultrasonic flaw detection method according to claim 1, wherein the clean water is ejected at a temperature equal to that of the aquarium water. An apparatus for carrying out the ultrasonic flaw detection method according to claim 1,
A water tank capable of immersing all or part of the object to be flawed in water;
An ultrasonic sensor that emits ultrasonic waves toward the object that has been immersed in water in the water tank in its entirety or in part;
It has a cylindrical nozzle with this ultrasonic sensor arranged on the proximal side,
The ultrasonic flaw detection apparatus according to claim 1, wherein the nozzle is provided with a water channel for ejecting clean water into the nozzle from the base end side of the vibration surface of the ultrasonic sensor.   The ultrasonic flaw detector according to claim 3, wherein the nozzle has a multilayer structure in which an ultrasonic absorption layer is interposed on the inner surface side.   The ultrasonic flaw detector according to claim 3 or 4, wherein the nozzle has a tip shape formed into an acute angle with a sharp inner peripheral side.   The ultrasonic flaw detector according to any one of claims 3 to 5, wherein an auxiliary outer cylinder is provided on an outer periphery of the nozzle. The method according to claim 2, wherein a heat exchanger is provided in the middle of the supply water piping system to the nozzle to make the temperature of the supply water the same as the water temperature in the water tank. The ultrasonic flaw detector according to any one of 3 to 6.

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