JP4329773B2 - Ultrasonic inspection method for fluororesin inspection object - Google Patents

Description

The present invention relates to an ultrasonic inspection method for a fluororesin inspection object .

  In the ultrasonic flaw detection method, ultrasonic waves are incident on an inspection object (hereinafter referred to as an inspection object) to inspect for the presence or absence of defects inside the inspection object. As this method, two main methods are known, and one is a vertical method in which ultrasonic waves are vertically incident into an inspection object. The other is an oblique angle method for oblique incidence, and this oblique angle method is often used.

  In the oblique angle method, an ultrasonic wave is incident obliquely into the inspection object by using a shoe (or a wedge) between the ultrasonic wave transmitting transducer and the inspection object as an ultrasonic probe. is doing. A vibrator that generates ultrasonic waves is attached to the shoe, and target ultrasonic waves (longitudinal waves, transverse waves, etc.) are incident on the object to be inspected. Such a technique is known, for example, as described in JP-A-11-14607.

Japanese Patent Laid-Open No. 11-14607

  Acrylic material or the like is practically used as the shoe material, while a material different from this is often used as the inspection object. Therefore, when the temperature changes, a difference appears in the fluctuation of the acoustic characteristics (sound speed etc.) of both.

  By the way, the ultrasonic sound velocity in the shoe is C1, the angle between the normal of the surface of the inspection object (contact surface with the shoe) and the ultrasonic wave is θ1, the ultrasonic sound velocity in the inspection object is C2, and the inspection object is in the inspection object. These relations are known as Snell's law shown in Equation (1) where θ2 is the incident angle of the ultrasonic wave.

C1 / sinθ1 = C2 / sinθ2 (Formula 1)
Under such conditions, when the ultrasonic sound velocity of the shoe and the object to be inspected changes with temperature, the sound velocity (C1, C2) changes accordingly. As shown in the equation (1), the ultrasonic incident angle (θ2) into the inspection object depends on the sound speed (C1) in the shoe and the sound speed (C2) in the inspection object. When C1 and C2) change, the ultrasonic incident angle (θ2) changes.

  When there is a temperature change, the shoe material and the object to be inspected vary in acoustic characteristics (such as the speed of sound), so the ultrasonic incident angle (θ2) changes, and the ultrasonic wave is detected at a specific position in the target object to be inspected. It becomes difficult to inject, and it becomes impossible to inspect a portion to be ultrasonically inspected.

The present invention has been made in view of the above, and an object thereof is a fluororesin that can inject an ultrasonic wave at a position in a target object to be inspected and can inspect the inside of the object to be inspected regardless of a temperature change. An object of the present invention is to provide an ultrasonic inspection method for an object to be manufactured .

  In order to achieve the above object, the present invention has a vibrator for generating ultrasonic waves and a shoe for injecting ultrasonic waves generated by the vibrator into an inspection object made of fluororesin, and returns from the inspection object. In the case of detecting ultrasonic waves, the acoustic characteristics of the shoe are set almost equal to the acoustic characteristics of the object to be inspected with respect to the temperature.

  Preferably, the sound velocity value is used as the acoustic characteristic with respect to the temperature of the object to be inspected, and the sound velocity value is used as the acoustic characteristic of the shoe.

  Preferably, the shoe is a polymer material. More preferably, the shoe is a fluororesin material. More preferably, ultrasonic waves are propagated through the ultrasonic wave propagation assisting member to the shoe and the object to be inspected. More preferably, the shoe and the vibrator are stored in a case.

  In order to achieve the above object, or a vibrator that generates an ultrasonic wave, a transmission unit that applies a voltage to the vibrator, a shoe that makes the ultrasonic wave generated by the vibrator incident on the inspection object, and an inspection object Having a receiving means for receiving the ultrasonic wave returned from and a display means for displaying information on the internal state of the inspected object based on the received signal of the receiving means. It was configured to set the acoustic characteristics of the shoe.

  Preferably, the sound velocity value is used as the acoustic characteristic with respect to the temperature of the object to be inspected, and the sound velocity value is used as the acoustic characteristic of the shoe.

  Preferably, the transmission unit or the reception unit is separate from the shoe and the vibrator. More preferably, the display means displays the received waveform.

  In order to achieve the above-mentioned purpose, or by generating ultrasonic waves, the acoustic characteristics of the shoe are set substantially equal to the acoustic characteristics with respect to the temperature of the inspection object, and the generated ultrasonic waves are incident on the inspection object through the shoe. Then, the ultrasonic wave returned from the inspection object is detected.

  Alternatively, an ultrasonic wave is generated, the angle of the ultrasonic wave before being incident on the object to be inspected is set to be substantially equal to the angle after the ultrasonic wave, and the generated ultrasonic wave is incident on the object to be inspected through the shoe. The ultrasonic wave returned from the inspection object is detected.

  Preferably, the inside of the inspection object is drained and evacuated. More preferably, a change in acoustic characteristics is examined by applying a stress load to the object to be inspected.

  As described above, according to the present invention, it is possible to inject an ultrasonic wave at a specific position in an object to be inspected regardless of a temperature change, thereby enabling the inside of the object to be inspected.

  Specifically, in an ultrasonic probe for ultrasonic inspection, an ultrasonic inspection device, and an ultrasonic inspection method, the object to be inspected and the shoe (wedge) are made of the same material such as a polymer material or a fluororesin material, so that the temperature changes. Regardless of this, the inside of the inspection object can be inspected by making the ultrasonic incident angle to the shoe equal to the ultrasonic incident angle to the inside of the inspection object. In addition, by performing drainage and evacuation of the inside of the test object in the ultrasonic inspection, it is possible to remove the factor that affects the reflection of the ultrasonic wave and to perform the ultrasonic inspection of the inspection object. Furthermore, ultrasonic inspection can be performed by applying internal pressure.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

  FIG. 1 shows an example of a schematic diagram of an ultrasonic probe used when inspecting an inspection object having a large temperature change in the present invention. The ultrasonic probe 0 has a structure in which a vibrator 1 that generates ultrasonic waves is attached to a shoe 2 and is housed in a case 3. In the present invention, case 3 is not a requirement.

  Conventionally, acrylic or the like having good acoustic characteristics has been used as the material of the shoe 2. However, in the present invention, in order to perform ultrasonic inspection of an inspection object having a large temperature change, it has a high acoustic characteristic that is the same as that of the inspection object. Molecular or fluororesin materials were used.

  FIG. 2 schematically shows an ultrasonic inspection apparatus in order to explain the situation in which ultrasonic waves are transmitted and received in the present invention. 1 to 3 are the same as in FIG. 1, 4 is an inspection object, 5 is a reflection source such as a defect, 6 is an ultrasonic wave emitted from the vibrator 1 and incident on the shoe 2, and 7 is into the inspection object 4. Incident ultrasonic waves, 8 is a probe cable, and 9 is an ultrasonic transceiver. In this case, an ultrasonic inspection method in which the reflection source 5 in the inspection object 4 is detected will be described with reference to the flowchart of FIG.

As shown in step 101, the ultrasonic probe 0 shown in FIG. 1 is a member for assisting the propagation of ultrasonic waves, that is, a liquid (contact medium; not shown) for efficiently transmitting ultrasonic waves. Then, as shown in step 102, the ultrasonic wave 6 generated in the vibrator 1 by the applied voltage from the ultrasonic transmitter / receiver 9 enters the shoe 2 and enters the shoe 2 at an incident angle θ1. And reaches the boundary surface of the inspection object 4. Note that the vibrator to be used may be a vibrator that generates an ultrasonic wave to be incident on the inspection object 4. That is, when a transverse wave is desired to be incident, a transverse wave vibrator is used, and when a longitudinal wave is desired to be incident, a longitudinal wave oscillator may be used. At this time, a part of the ultrasonic wave 6 is reflected, and the remaining part becomes the ultrasonic wave 7 passing into the inspection object 4. Here, as shown in step 103, if the sound speed of the ultrasonic wave 6 incident on the shoe 2 is C1, the sound speed of the ultrasonic wave 7 incident on the inspection object 4 is C2, the incident angle of the ultrasonic wave 7 is θ2, There is a relationship such as Equation (1) known as Snell's Law.

C1 / sinθ1 = C2 / sinθ2 (Formula 1)
By the way, in the present invention, the shoe 2 and the object 4 to be inspected are made of the same material with the acoustic characteristics depending on the temperature as in step 104, so that C1 = C2 in the above equation, and as a result, θ1 = θ2 as in step 105. Become.

  Therefore, regardless of the temperature change, the incident angle of the ultrasonic wave on the shoe 2 and the incident angle on the inspection object 4 become equal, and the ultrasonic wave 6 goes straight through the inspection object 4 as in step 106 and the ultrasonic wave 7. And hits the reflection source 5. This process is ultrasonic transmission. Next, as in step 107, the ultrasonic wave reflected by the defect 5 goes straight in the direction opposite to that at the time of incidence and reaches the vibrator 1. This process is reception of ultrasonic waves. Finally, as in step 108, an ultrasonic signal is transmitted to the ultrasonic transmitter / receiver 9 through the probe cable 8, and a received waveform is displayed. In the above aspect of the invention, C1 = C2 holds regardless of the temperature, so that it is not necessary to calculate the incident angle based on Snell's law in Equation (1), and the probe design can be simplified. can get.

  In the present invention, when the sound speed of the object to be inspected 4 is the sound speed C2 (T) that varies with the temperature T, the sound speed C1 (T) that satisfies the relationship of the expression (2) obtained by modifying the expression (1) is obtained. A material having or a material that can approximate the material may be used as the shoe 2.

C1 (T) = C2 (T) * sinθ1 / sinθ2 (Formula 2)
At this time, the modes of the ultrasonic wave 6 propagating through the shoe 2 include a longitudinal wave and a transverse wave. It is desirable to select an ultrasonic mode that can approximate Equation (2) with higher accuracy.

  There is a polymer material as an example of an object to be inspected whose acoustic characteristics such as sound velocity and attenuation rate greatly change due to temperature change. Polymer materials exhibit complex behavior such as acoustic characteristics exhibiting non-linear fluctuations, extreme values, inflection points, etc. in the temperature range where testing may be performed, for example, 0 ° C. to 40 ° C. Sometimes. Furthermore, there are many types of materials depending on the component ratio and the molecular bonding state, and the tendency of the acoustic characteristics to vary with temperature differs for each material. Therefore, especially when the inspection object is made of a polymer material, the use of the same material or almost the same material as the inspection object as the shoe material of the probe keeps the incident angle constant. A great effect can be obtained. Further, it is desirable that the probe shoe material is cut and manufactured from a material manufactured in the same manufacturing process as the inspection object itself. Further, when the shoe material is installed on the inspection object, it is desirable to select the direction of cutting or processing from the material so that the directionality of the material of the shoe material and the inspection object matches.

  Among polymer materials, a fluororesin material has a very large variation in sound speed due to temperature in addition to complicated variation in acoustic characteristics due to temperature. Therefore, when the object to be inspected is a fluororesin material, making the shoe material of the probe the same material or almost the same material as the object to be inspected is more remarkable in that the incident angle is kept constant. Is obtained.

  In addition, even when the object to be inspected is a polymer material or a fluororesin material as described above, a different material that can approximate Equation (2) with high accuracy can be selected. As a material of the shoe 2 at this time, for example, there is polystyrene.

  When the ultrasonic probe 0 is brought into contact with the inspection object 4, there may be a temperature difference between the ultrasonic probe 0 and the inspection object 4. At this time, if the time is taken until the temperatures of the ultrasonic probe 0 and the inspection object 4 become substantially the same, an inspection that is less susceptible to fluctuations due to temperature can be performed.

  Finally, an embodiment in which the inspection object is a pipe for flowing a liquid such as water and inspects a defect generated in this member will be described. When liquid is present in the tube, there is a concern that the ultrasonic wave is transmitted to the liquid side on the tube inner surface side and the intensity of the received ultrasonic wave is reduced. In order to avoid this, a method of naturally draining water from the object to be inspected, a method of injecting compressed gas into the object to be inspected, draining water by applying pressure, or a pressure inside the object to be inspected is reduced. Thus, by using a method of draining in a vacuum state, an effect of suppressing a decrease in the intensity of the ultrasonic wave can be obtained. Further, by applying the internal pressure, the opening width of the defect opening inside the tube can be widened, and an effect of suppressing a reduction in the intensity of ultrasonic waves caused by the narrow opening width can be obtained.

It is a schematic diagram of the bevel ultrasonic probe of the insulation hose in this invention. It is a schematic diagram of the bevel ultrasonic inspection apparatus of the insulation hose in this invention. It is a flowchart which shows the other oblique angle ultrasonic inspection method of the insulation hose in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 0 ... Ultrasonic probe, 1 ... Vibrator, 2 ... Shoe (wedge), 3 ... Case, 4 ... Inspected object, 5 ... Reflection source, 6 ... Ultrasonic wave incident on shoe, 7 ... To inspected object Incident ultrasound, 8 ... probe cable, 9 ... ultrasonic transceiver.

Claims (2)

The ultrasonic wave generated by the vibrator is incident on the fluororesin inspection object through a shoe made of the same material as the fluororesin inspection object , and the ultrasonic wave returned from the fluororesin inspection object is returned. An ultrasonic inspection method for a fluororesin inspection object characterized by detecting. When the fluororesin inspection object is a pipe for flowing a liquid and the liquid exists in the pipe, the compressed gas is injected into the pipe and drained by applying pressure, or the inside of the pipe is depressurized. ultrasonic inspection method fluororesin inspection object and detecting an ultrasonic wave in a method according to claim 1 after抜水in the vacuum state by.

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