JP2002286441A - Thickness measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide which of layers of a body to be measured composed of the layers having different magnetic characteristics the result of thickness measurement corresponds to. SOLUTION: The thickness measuring instrument having an ultrasonic wave measurement part 2 which irradiates the body 7 to be measured composed of an intermediate layer 15 and the surface layer 16 on a base material 14 with an ultraviolet wave and measures the thickness of the body to be measured from the time from the transmission and reception is further equipped with a magnetic induction sensor part 5 which applies an alternating magnetic field to the body to be measured and detects the magnetic variation at this time and a magnetic induction measurement part 3 which specifies the kinds of the layers according to the magnetic variation from the magnetic induction sensor part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness measuring device for measuring the thickness of double welded clad layers having different magnetic properties.

[0002]

2. Description of the Related Art For example, business boilers, industrial boilers,
Chemical plants and nuclear-related equipment are thoroughly maintained and extended in their useful lives from the viewpoint of environmental protection, improvement of economic efficiency, and coexistence with local communities. If it is necessary to measure the thickness of the weld clad layer at the welding point in the maintenance and inspection work for a large metal structure as described above, use a thickness measuring device that uses ultrasonic waves to The thickness of the weld clad layer has been measured. Conventional thickness measuring devices use a supersonic oscillator that is in close contact with the surface of a metal workpiece to transmit pulsed ultrasonic waves through the workpiece. Since the propagation speed of the sound wave changes discontinuously, the ultrasonic wave propagating in the object to be measured is reflected between the layers. This reflected wave is detected on the surface, and from the time from the start of ultrasonic wave propagation to the detection of the reflected wave and the propagation speed of the ultrasonic wave in the object to be measured, which is separately obtained, the interlayer between the weld clad layer and the base material is measured from the surface. , That is, the thickness of the weld clad layer.

[0003]

When the weld clad layer to be measured is not a single layer but is composed of a plurality of layers having different characteristics, the reflected waves from the layers of the different weld clad layers, the weld clad layer and the base material Reflected waves from between layers are detected together, but due to aging due to corrosion and wear, when the weld clad layer that should be near the surface has disappeared,
Due to the uncertain structure between the weld clad layers, the ultrasonic reflection from the clad layers may be particularly strong or particularly weak. In such a case, a weld clad layer close to the surface (hereinafter, referred to as a surface layer), a boundary portion between the surface layer and the base material of the weld clad layer (hereinafter, referred to as an intermediate layer), and the intermediate layer and the base material. However, there is a problem that it is not possible to determine which one of the boundary portions is the reflected wave, and it is not possible to accurately measure the thickness between the layers.

The present invention has been made in view of such a demand, and an object of the present invention is to determine in which layer the thickness measurement result of an object to be measured composed of a plurality of layers having different magnetic properties by ultrasonic measurement is determined. It is an object of the present invention to provide a thickness measuring device capable of determining the presence.

[0005]

In order to achieve the above object, the present invention is directed to applying an ultrasonic wave to an object to be measured constituted by layers having different magnetic properties and measuring the time of the measurement from the time from transmission to reception. In a thickness measuring apparatus having an ultrasonic measuring means for measuring the thickness of an object, a magnetic induction detecting means for applying an alternating magnetic field to the object to be measured and detecting a magnetic change at that time, Magnetic induction measuring means for specifying the type of the plurality of layers based on a magnetic change from the means.

In this case, the magnetic induction detecting means is disposed integrally with the ultrasonic measuring means, and the first coil to which an alternating current is applied, and the measured current by the alternating current from the first coil. And a second coil for detecting impedance generated in the object.

The magnetic induction detecting means can vary the frequency of the alternating current for generating the alternating magnetic field, and the frequency can be varied in a range from 100 Hz to 10 Hz.
MHz.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First, the structure will be described with reference to FIGS. FIG. 1 is a block diagram showing an overall configuration according to an embodiment of the present invention, FIG. 2 is a diagram showing a structure of an ultrasonic sensor unit constituting the sensor of FIG. 1, and FIG. 3 is a magnetic induction constituting a sensor means of FIG. It is a figure showing the structure of a sensor part.

As shown in FIG. 1, a thickness measuring device includes a sensor 1 positioned on a surface 8 of a measured object 7, an ultrasonic measuring unit 2 for measuring the thickness of the measured object 7 by ultrasonic waves, and And a magnetic induction measuring section 3 for measuring the material and thickness of the DUT 7 by magnetic induction. Sensor part 1
Is composed of an ultrasonic sensor unit 4 shown in FIG. 2 and a magnetic induction sensor unit 5 shown in FIG. Ultrasonic sensor unit 4
Is provided with a magnetostrictive element 6 for both oscillating and receiving an ultrasonic wave, oscillating the ultrasonic wave by applying a high frequency voltage, and transmitting the ultrasonic wave from the surface 8 which is a contact surface with the measured object 7 into the measured object 7. Propagate. The ultrasonic reflected wave from the device under test 7 is detected by the magnetostrictive element 6 as an electric signal, and the electric signal is sent to the ultrasonic measuring unit 2. On the other hand, the magnetic induction sensor unit 5 is configured by winding an excitation coil 10 and a detection coil 11 around an iron core 9. Although not shown, the iron core 9 is appropriately supported so that the distance between the lower end thereof and the surface 8 of the DUT 7 is constant. The AC power source 1 is connected to the exciting coil 10.
0a and ammeter 11a are connected to detection coil 11, respectively.

In this embodiment, as shown in FIG. 1, the ultrasonic sensor unit 4 and the magnetic induction sensor unit 5 are housed in a single housing. The site may be measured alternately.
Further, in the ultrasonic sensor unit 4, the same magnetostrictive element 6 is used for both the oscillation and the reception of the ultrasonic wave. However, a separate receiving element may be provided to separate the oscillating element and the receiving element. Further, the magnetic induction sensor unit 5 may detect a change in coil impedance by a separate impedance bridge in a single coil structure.

The ultrasonic sensor section 4 oscillates ultrasonic waves in a pulsed manner by the pulsed excitation high-frequency voltage supplied from the ultrasonic measuring section 2, and the ultrasonic waves propagate into the measured object 7. If there is a discontinuous surface of the ultrasonic wave propagation velocity in the measured object 7, for example, a layer between the weld clad layers or a layer between the weld clad layer and the base material, the ultrasonic waves are reflected there. The reflected wave propagates in the opposite direction from the surface 8 of the device under test 7 to the magnetostrictive element 6 to generate a signal voltage. When the signal voltage is amplified by the ultrasonic measurement unit 2 and the change in the signal intensity of the reflected wave with respect to the elapsed time from the oscillation of the ultrasonic wave is displayed, an example of the result of the measurement of the thickness of the welding clad layer by the ultrasonic wave is shown. As shown in FIG. 4, the situation in the device under test can be indicated by a waveform. The relationship between the ultrasonic oscillation time and the layer thickness is as shown in FIG. 5, which shows an example of a calibration standard sample for performing the layer thickness measurement of the weld clad layer by ultrasonic waves. Therefore, if a known calibration sample as shown in FIG. 5 is measured for the layer thickness and the thicknesses of the welding clad layers A, B, C, and D are obtained in advance, the ultrasonic wave can be obtained from the measurement results shown in FIG. After the oscillation, the time when the first reflected wave A appears, the thickness A of the weld clad, the time when the second reflected wave B appears, the thickness B of the weld clad layer, and the time when the third reflected wave C appears And the thickness C of the welding clad layer, for each different thickness of the clad layer, it is associated with the time at which the reflected wave appears. Thereby, as shown in FIG. 6, the thickness between the respective layers can be obtained from the calibration result of the standard sample.

In the magnetic induction measurement, an alternating current is supplied to the excitation coil 10 of the magnetic induction sensor unit 5, and the frequency thereof can be changed by the magnetic induction measurement unit 3. When a current flows through the exciting coil 10, an induced voltage is generated in the detection coil 11 by an electromagnetic induction action.
The voltage is affected by the magnetic permeability of the iron core and the DUT 7 in the alternating magnetic field generated by the exciting coil 10, and the higher the magnetic permeability, the higher the induced voltage. Since the land coverage of the DUT 7 is correlated with the amount of ferrite in the material, the ferrite amount of the DUT 7 can be measured by the induced voltage.

In particular, if the frequency of the alternating current supplied to the exciting coil 10 is at least 10 KHz or more,
As shown in FIG. 7, which is a schematic diagram for explaining a situation when an alternating magnetic field is generated from the magnetic induction sensor unit 5 at a frequency of not less than Hz, the alternating magnetic field 12 generated by the surface effect of the DUT 7 Since the influence of the material near the surface of the DUT 7 is greatly affected and the influence of the magnetic permeability is increased, if the induced voltage generated in the detection coil 11 is calibrated with a known material, Can be determined. However, if the frequency of the alternating current supplied to the excitation coil 10 exceeds 10 MHz, the measurement becomes unstable due to the influence of the surface state of the DUT 7. Therefore, the frequency of the alternating current supplied is between 10 KHz and 10 MHz. Is appropriate, and it is desirable to obtain an appropriate frequency using a calibration material under the same conditions as the DUT 7.

FIG. 3 is a schematic diagram for explaining a situation when an alternating magnetic field is generated from the magnetic induction sensor unit 5 at a frequency of 10 KHz or less when the frequency of the alternating current supplied to the excitation coil 10 is changed from 10 Hz to 10 KHz. As shown in FIG. 8, since the surface effect of the DUT 7 is reduced, the alternating magnetic field 12 generated by the magnetic induction sensor unit 5
It can penetrate from the surface to the inside. Therefore, if the intensity of the alternating magnetic field generated by the magnetic induction sensor unit 5 is kept constant, the induced AC voltage detected by the detection coil 11 is determined by the surface layer and the intermediate layer, the magnetic permeability and the surface layer thickness of each. For example, if the permeability of the intermediate layer is higher than that of the surface layer,
The higher the proportion of the surface layer in the alternating magnetic field in the device under test, that is, the thicker the surface layer, the lower the induced AC voltage.

Therefore, as shown in FIG. 9, which is an example of a calibration standard sample for measuring the surface layer thickness by the magnetic induction sensor unit 5, the base material 14 is made of the same material and the same construction method as the object to be measured. A standard sample in which the thicknesses of the welded clad layer 16 (hereinafter, referred to as a surface layer 16) serving as a surface layer located above and the welded clad layer 15 (hereinafter, referred to as an intermediate layer 15) serving as an intermediate layer are known. 13 and the surface layer and the detection coil 1
If the relationship with the induced AC voltage detected in step 1 is obtained in advance, the thickness of the surface layer can be obtained from the induced AC current when the object to be measured is measured. These numerical values are stored in the magnetic induction measurement unit 3. At this time, as the frequency of the alternating current supplied to the exciting coil 10 is lower, the alternating magnetic field in the object to be measured penetrates deeper than the surface and the surface layer thickness can be measured deeper. Therefore, the frequency of the alternating current is set to 10 KHz or less. It is preferable that the lower the frequency is, the less sensitive the magnetic permeability of the DUT 7 is, and the lower the measurement accuracy is. Therefore, it is necessary to set the measurement accuracy to 10 KHz or more. In actual use, it is desirable to set the frequency to the highest value in the frequency range in which the thickness of the surface layer to be measured can be obtained with high accuracy, and to use the frequency in a preliminary calibration test.

The result of the measurement of the thickness of the weld clad layer by the above-described magnetic induction indicates that the alternating magnetic field generated by the magnetic induction sensor unit 5 is magnetically affected by the base material 14 below the intermediate layer. A change in the thickness of the surface layer 16 tends to cause an error in the measured value of the thickness of the surface layer 16. For this reason, the exact value of the thickness of each layer is determined by reflected wave measurement using ultrasonic waves, and the measurement result of the thickness of the surface layer 16 by magnetic induction is used as a reference value.

Here, an example of measurement of an object to be measured will be described with reference to FIGS. FIG. 10 is a schematic diagram illustrating an example of a layer structure of an object to be measured having a double weld clad layer, FIG. 11 is a waveform diagram illustrating a result of measuring the thickness of the weld clad layer at a portion A in FIG. 10 by ultrasonic waves, FIG. 12 is a waveform diagram showing the results of measuring the thickness of the welding clad layer at the portion B in FIG. 10 by ultrasonic waves, and FIG. 13 is a graph showing the results of measuring the layer thickness of the welding clad layer at the portion C of FIG. 10 by ultrasonic waves. FIG. 14 is a waveform diagram showing the results of measuring the thickness of the weld clad layer at the portion D in FIG. 10 by ultrasonic waves.

An intermediate layer 15 is formed on the workpiece 14 by arc welding an Inconel 182 on a base material 14 made of SQV2A, and an Inconel 82 is formed on the surface of the intermediate layer 15.
Is formed into a three-layer structure by MIG welding. Surface layer 1 which is a weld clad layer by Inconel 82
Although the thickness of the layer 5 is about 5.0 mm, the layer disappears due to abrasion and the intermediate layer 15 which is the weld clad layer of the Inconel 182 is exposed, as in the part B.
The intermediate layer 15, which is the weld clad layer of Inconel 182, has a thickness of 3.0 mm to 8.0 mm.

FIG. 11 shows the result of measuring the thickness of the welding clad layer at the portion A of the object by ultrasonic waves. In the figure, the leftmost peak 17 is the ultrasonic sensor 4
From the surface layer 16 and the intermediate layer 1
The reflected wave from the interlayer of No. 5 and the peak 19 indicate the reflected wave from the interlayer of the intermediate layer 15 and the base material 14. In this case, the thickness of the surface layer 16 is 4.2 mm, and the thickness of the intermediate layer 15 is 4.5 mm from the relationship between the propagation time of the ultrasonic wave in the object to be measured and the layer thickness, which are separately calibrated. .

FIG. 12 shows the result of measuring the thickness of the weld clad layer at the portion B. This part B is directly
Is measured, so that only one reflected wave peak 19 between the intermediate layer 15 and the base material 14 located at 4 mm or less from the surface is displayed.

FIG. 13 shows the result of measuring the thickness of the weld clad layer at the portion C. In this part C, the reflection peak 18 between the surface layer 16 and the intermediate layer 15 is strong,
Since the reflected wave peak 19 between the layers of the base material 5 and the base material 14 is weak, it appears that only one reflected wave peak between the layers of the surface layer 16 and the intermediate layer 15 located 5.2 mm below the surface is displayed.

FIG. 14 shows the result of measuring the thickness of the weld clad layer at the portion D. This portion D has a peak 1 reflected from the surface layer 16 and the intermediate layer 15 opposite to the portion C.
8 is weak and the reflected wave peak 19 between the layers of the intermediate layer 15 and the base material 14 is strong, so that there is only one reflected wave peak 19 between the layers of the intermediate layer 15 and the base material 14 located 6.0 mm below the surface. Looks like it was displayed.

As described above, the thickness of each weld clad layer can be measured from the state of the reflected wave, but when only one reflected wave peak can be clearly discriminated as in the parts B, C and D, Since it is not known which layer the reflected wave is from, it is impossible to accurately measure the thickness of each welding clad layer.

Therefore, the induced voltage is measured by the magnetic induction sensor unit 5, and the thickness of the weld clad layer is measured based on the result as shown in FIG. FIG. 15 is a table summarizing the results obtained by measuring the thickness of the weld clad layer in each part of the measured object in FIG. 10 by the measuring apparatus of the present invention.
At site A, site B, site C and site D, 2MH
When the frequency of z is determined for the surface material by magnetic induction,
Since the magnetic permeability of the Inconel 182 of the intermediate layer 15 is higher than that of the Inconel 82 of the surface layer 16, the portion B where the Inconel 182 of the intermediate layer 15 is exposed is located in the magnetic induction sensor 5.
Of the detection coil 11 becomes higher. On the other hand, 3KH
When the measurement is performed at a low frequency of z, the approximate value of the thickness of the surface layer 16 can be measured.
82 can be determined. In the example of the part C, the layer on the surface is Inconel 82, and the measurement result of the thickness of the weld clad layer of only the surface layer 16 is detected. In the example of the part D, the layer on the surface is Inconel 82, It is clear that the thickness of the surface layer 16 was not measured while the thickness of the weld clad layer was measured.

In the case of the portions C and D, the measurement position is slightly moved, and as in the portion A, the reflected wave peak 18 between the surface layer 16 and the intermediate layer 15 and the intermediate layer 15
Either search for a position where the reflected wave peak 19 between the layers of the base material 14 and the base material 14 can be measured clearly, or slightly reduce the accuracy of thickness measurement, but make the ultrasonic wave irradiation angle oblique to facilitate ultrasonic reflection between the layers. Then, the thicknesses of the two weld clad layers of the surface layer 16 and the intermediate layer 15 can be measured.

[0026]

As is apparent from the above description, according to the present invention, an alternating magnetic field is applied to an object to be measured, and a magnetic change at that time is detected by magnetic induction detecting means. Since the type of the plurality of layers is specified by the magnetic induction measuring means based on the magnetic change from the means, it becomes possible to accurately measure the remaining thickness of the two-layer weld clad layer having different magnetic properties for each weld clad layer. . This makes it possible to accurately and quickly grasp the state of deterioration when repairing a clad or clad-welded structure.

Further, according to the present invention, since the guidance detecting means and the ultrasonic measuring means are arranged integrally, it is possible to apply ultrasonic waves and an alternating magnetic field to substantially the same location on the object to be measured. It is possible to accurately select a layer and measure its thickness.

Further, according to the present invention, the first coil to which the alternating current is applied and the second coil for detecting the impedance generated in the DUT by the alternating current from the first coil.
The coil and the coil constitute magnetic induction detecting means. When an alternating current is applied to the coil, an impedance corresponding to the magnetic permeability of each layer can be detected, and the layer can be accurately identified with a simple structure.

Further, according to the present invention, since the frequency of the alternating current for generating the alternating magnetic field by the magnetic induction detecting means can be changed, the depth of the alternating magnetic field can be reduced by changing the frequency of the alternating current. It can be adjusted and the approximate thickness of the layer by magnetic induction can be measured.

Further, according to the present invention, the frequency of the alternating current is set in the range of 100 Hz to 10 MHz, and if the frequency of the alternating current is changed from 100 Hz to 10 kHz, the alternating magnetic field penetrates deeply and the frequency of the alternating current changes from 10 kHz to 10 MHz.
z, the alternating magnetic field penetrates shallowly, so that a layer near the surface is measured at 10 KHz or more, and a layer deep from the surface is 10 KHz.
By measuring at or below Hz, accurate measurement is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of an ultrasonic sensor unit forming a part of the sensor of FIG.

FIG. 3 is a diagram showing a structure of a magnetic induction sensor unit forming a part of the sensor of FIG. 1;

FIG. 4 is a waveform chart showing an example of a result of measuring a thickness of a weld clad layer by ultrasonic waves.

FIG. 5 is a diagram showing an example of a calibration standard sample for performing a thickness measurement of a weld clad layer by ultrasonic waves.

6 is a waveform chart showing an example of a calibration result with the standard sample of FIG.

FIG. 7 is a schematic diagram for explaining a situation when an alternating magnetic field is generated from the magnetic induction sensor unit of FIG. 3 at a frequency of 10 KHz or more.

FIG. 8 is a schematic diagram for explaining a situation when an alternating magnetic field is generated from the magnetic induction sensor unit of FIG. 3 at a frequency of 10 KHz or less.

9 is a diagram showing an example of a calibration standard sample for measuring the surface layer thickness by the magnetic induction sensor of FIG. 3;

FIG. 10 is a schematic diagram showing an example of a layer structure of a device under test having a double weld clad layer.

FIG. 11 is a waveform diagram showing the results of ultrasonic measurement of the thickness of the weld clad layer at site A in FIG.

FIG. 12 is a waveform chart showing the result of measuring the thickness of the weld clad layer at the portion B in FIG. 10 by ultrasonic waves.

FIG. 13 is a waveform diagram showing the results of measuring the thickness of the weld clad layer at the site C in FIG. 10 by ultrasonic waves.

FIG. 14 is a waveform chart showing the result of measuring the thickness of the weld clad layer at a portion D in FIG. 10 by ultrasonic waves.

FIG. 15 is a table summarizing the results of measuring the thickness of the weld clad layer in each part of the measured object in FIG. 10 by the measuring apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor 2 Ultrasonic measurement part 3 Magnetic induction measurement part 4 Ultrasonic sensor part 5 Magnetic induction sensor part 6 Magnetostrictive element 7 DUT 9 Iron core 10 Excitation coil 11 Detection coil 14 Base material 15 Intermediate layer 16 Surface layer

Continued on the front page F term (reference) 2F063 AA16 BA30 BB02 BB03 BB05 BC02 BD20 CA09 CA40 DA01 DA02 DD08 GA03 GA29 JA01 2F068 AA28 BB14 CC09 DD11 EE07 FF12 GG02 LL02 2F069 AA16 AA46 BB19 BB40 GG31 GG31 GG30 GG30 GG71 HH09 HH30 NN02 NN10 RR03 2G047 AA06 AB07 BA03 BB01 BB04 BC11 BC18 CA02 EA10 EA11 GA20 GC04 2G053 AA00 AB07 BA02 BC02 CA03 CA17 CA18 CB05 CC03 CC04 DB05

Claims (5)

[Claims] An ultrasonic measuring means for irradiating an object to be measured composed of layers having different magnetic properties with each other and measuring the thickness of the object from the time from transmission to reception. In the measuring apparatus, an alternating magnetic field is applied to the object to be measured, and magnetic induction detecting means for detecting a magnetic change at that time; and a type of the plurality of layers is specified based on the magnetic change from the magnetic induction detecting means. And a magnetic induction measuring means. 2. The thickness measuring apparatus according to claim 1, wherein said magnetic induction detecting means is arranged integrally with said ultrasonic measuring means. 3. The magnetic induction detecting means includes a first coil to which an alternating current is applied, and a second coil for detecting an impedance generated in the device under test by the alternating current from the first coil. The thickness measuring device according to claim 1, wherein the thickness is measured. 4. The thickness measuring apparatus according to claim 1, wherein said magnetic induction detecting means changes the frequency of an alternating current for generating said alternating magnetic field. . 5. The variable frequency range according to claim 4, wherein the variable range is 100 Hz to 10 MHz.
The thickness measuring device according to the above.