JP2007298292A - Method of measuring eddy-current type nonmagnetic metal film thickness, and apparatus for measuring eddy-current type nonmagnetic metal film thickness for performing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring an eddy-current type nonmagnetic metal film thickness which can improve the accuracy of measuring a plate thickness in the case of lift-off, and to provide an apparatus for measuring the same for performing the method. <P>SOLUTION: The method includes a step of installing an eddy-current measuring sensor 4 on a calibration test piece having the same specifications as those of nonmagnetic metal and selecting the frequency of an exciting current to be supplied to the eddy-current measuring sensor 4 to be a value suitable for each calibration test piece, a step of adjusting the phase angle of the exciting current on the basis of the selected frequency and selecting a phase angle providing smaller rate of fluctuation in the imaginary part output from the eddy-current measuring sensor 4 installed on the calibration test piece, and a step of measuring the film thickness of the nonmagnetic metal on the basis of the frequency and phase angle determined by these steps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an eddy current type nonmagnetic metal film thickness measuring method and an eddy current type nonmagnetic metal film thickness measuring apparatus for carrying out the method, and particularly suitable for measuring the film thickness of a nonmagnetic metal on a magnetic metal. The present invention relates to an eddy current type nonmagnetic metal film thickness measuring method and an eddy current type nonmagnetic metal film thickness measuring apparatus for carrying out the method.

  For example, a turbine blade (magnetic metal) of a gas turbine is used by coating the surface of the blade with a high-hardness stellite plate (non-magnetic metal) in order to reduce metal corrosion on the blade surface that develops during operation. is doing. Then, when the stellite plate becomes 0.3 mm or less in thickness, a new stellite plate is covered again.

  Therefore, in order to measure the thickness of the stellite plate, an excitation coil installed on the metal plate is excited, and a change in the induced magnetic field due to the eddy current generated in the metal plate is detected by the detection coil to measure the plate thickness. For example, a metal film thickness measuring apparatus as described in Patent Document 1 is used.

  However, in such a measuring apparatus, if the excitation coil and the detection coil are lifted from the metal plate (hereinafter referred to as lift-off), the measurement value changes, so that there is a problem that an error occurs in the measurement of the plate thickness. In order to reduce these measurement errors, out of the X output (for the real number of the resistance of the detection coil) and the Y output (for the imaginary number of the resistance of the detection coil) detected by the detection coil by adjusting the phase angle, the Y output As shown in Patent Document 2, for example, it has already been proposed to select a phase angle that minimizes the variation rate and use a Y output with a small variation rate as a thickness measurement signal.

JP 2003-270214 A Japanese Patent Laid-Open No. 2003-232776

  According to the above-described conventional technique, the detection error at the time of lift-off can be reduced to some extent, but it is not sufficient, and further improvement in the measurement accuracy of the plate thickness at the time of lift-off is desired.

  An object of the present invention is to provide an eddy current type nonmagnetic metal film thickness measuring method and an eddy current type nonmagnetic metal film thickness measuring apparatus capable of further improving the plate thickness measurement accuracy at lift-off. There is to do.

  In order to achieve the above object, the present invention provides an eddy current type in which an excitation coil is excited and an induced magnetic field caused by an eddy current generated in a nonmagnetic metal on a magnetic metal is detected by a detection coil to measure the film thickness of the nonmagnetic metal. In the eddy current type nonmagnetic metal film thickness measuring method using film thickness measuring means, the excitation coil and the detection coil are installed on a calibration specimen having the same specifications as the nonmagnetic metal and supplied to the excitation coil. The imaginary number output from the detection coil installed on the calibration specimen by adjusting the phase angle of the excitation current based on the selected frequency and adjusting the phase angle of the excitation current based on the selected frequency The step of selecting the phase angle at which the variation rate of the portion (Y output) becomes small, and the film thickness of the nonmagnetic metal is measured by the eddy current film thickness measuring means based on the frequency and phase angle determined by these steps. It is characterized in that a that step.

  That is, the phase angle is controlled to reduce the fluctuation rate of the Y output. Even if the phase angle is controlled in this way, the frequency of the excitation current supplied to the excitation coil is the non-magnetic metal material that is the measurement object. If it does not match, it has been confirmed by experiments that the fluctuation rate of the Y output cannot always be reduced. Therefore, the frequency of the excitation current supplied to the excitation coil is selected to a value suitable for a calibration test body having the same specifications as the non-magnetic metal, and the calibration test is performed by adjusting the phase angle of the excitation current based on the selected frequency. By selecting the phase angle at which the fluctuation rate of the Y output outputted from the detection coil installed on the body is small, the film thickness of the nonmagnetic metal is measured, so that the fluctuation rate of the Y output is reduced. By further reducing, the measurement accuracy was improved.

  As described above, according to the present invention, the eddy current type nonmagnetic metal film thickness measuring method capable of further improving the plate thickness measurement accuracy at the lift-off and the eddy current type nonmagnetic metal film for implementing the method. A thickness measuring device can be obtained.

  A first embodiment of an eddy current type nonmagnetic metal film thickness measuring method according to the present invention will be described below based on an eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIGS.

  The eddy current type nonmagnetic metal film thickness measuring apparatus 1 is roughly divided into a personal computer (hereinafter referred to as a personal computer) 2 and an eddy current type film thickness measuring means 3 for transmitting and receiving signals by the personal computer 2 and a signal line S1. An eddy current measurement sensor 4 that transmits and receives signals by the eddy current film thickness measuring means 3 and the signal line S2, an actuator 5 that drives the eddy current measurement sensor 4, and a signal line S3 connected to the actuator 5 via the signal line S3. The actuator driver 6 transmits and receives drive signals, and the signal line S4 transmits and receives signals between the actuator driver 6 and the personal computer 2.

  The eddy current measuring sensor 4 includes a core 7 made of ferrite, a coil 8 wound around the core 7 to draw out a signal line S2, and one of copper, silver, aluminum, and permalloy covering the outer periphery of the coil 8. The shield material 9 is made of the above material, and the whole is fixed with a non-conductive adhesive. The coil 8 serves as both an excitation coil and a detection coil. However, the coil 8 may include an excitation coil and a detection coil separately.

  The actuator 5 includes a base 10A, a first moving base 10B driven by the base 10A, and a second moving base 10C driven by the first moving base 10B. The base 10A includes a motor 11A, and includes a screw rod 12A driven by the motor 11A and a moving piece 13A screwed into the screw rod 12A so as to be movable. The first moving base 10B is connected to the moving piece 13A, a screw bar 12B extending in a direction perpendicular to the screw rod 12A of the base 10A, a motor 11B for driving the screw rod 12B, and the screw And a moving piece 13B screwed to the rod 12B so as to be movable. Furthermore, the second moving table 10C is connected to the moving piece 13B, and the screw rod 12C extending in the direction orthogonal to the screw rod 12A of the base 10A and the screw rod 12B of the second moving table 10B, A motor 11C that drives the screw rod 12C and a moving piece 13C that is movably screwed into the screw rod 12C are provided. The eddy current measuring sensor 4 is fixed to the moving piece 13C of the second moving table 10C, and this eddy current measuring sensor 4 drives the motors 11A to 11C, so that X, Y with reference to the base 10A. , Z direction.

  The personal computer 2 includes a calculation unit 21, an HDD 22, a RAM 23, a ROM 24, an I / O port 25, a keyboard 26, a recording medium 27, and a monitor 28.

  The eddy current film thickness measuring means 3 includes a calculation unit 31, a hard disk (HDD) 32, a random access memory (RAM) 33, a read-on memory (ROM) 34, an I / O port 35, a D / O An A converter 36 and an A / D converter 37 are provided.

  Similar to the eddy current film thickness measuring means 3, the actuator driver 6 includes a calculation unit 61, HDD 62, RAM 63, ROM 64, I / O port 65, D / A converter 66, A / D Converter 67.

  The signal line S1 connects the I / O port 25 of the personal computer 2 and the I / O port 35 of the eddy current film thickness measuring means 3, and the signal line S2 is connected to the eddy current measurement sensor 4 and the eddy current film. The D / A converter 36 and the A / D converter 37 of the thickness measuring means 3 are connected, and the signal line S3 is connected to the motors 11A to 11C of the actuator 5 and the D / A converter 66 and the A / D converter 67 of the actuator driver 6. Is connected.

  In the above configuration, the personal computer 2, the eddy current type film thickness measuring means 3, the eddy current measurement sensor 4, the actuator 5, and the actuator driver 6 constitute the eddy current type non-magnetic metal film thickness measuring device 1. These are the frequency selecting means and the phase angle selecting means and the film thickness measuring means.

Next, a procedure for measuring the film thickness of the nonmagnetic metal on the magnetic metal using the eddy current type nonmagnetic metal film thickness measuring apparatus 1 having the above configuration will be described.
[Step 1]
The eddy current measurement sensor 4 is placed on the calibration specimen.
[Step 2]
The same conductivity and permeability as the measurement object that is a non-magnetic metal on the magnetic metal using one or more data input means such as the keyboard 26 of the personal computer 2 and the recording medium 27, the thickness of the calibration specimen, and the eddy current The relative position between the measurement sensor 4 and the calibration specimen is input to the I / O port 25. The input data is transmitted to the calculation unit 21, and the frequency at which the thickness measurement error of the calibration specimen approximated by Equation 1 shown in FIG. 5 and stored in any of the HDD 22, RAM 23, and ROM 24 is reduced by the calculation unit 21. The initial frequency f (Hz) is calculated using the evaluation result of the nonmagnetic metal thickness dependency.
f = t ² ÷ (2πσμ) Equation 1
Here, t represents the thickness (m) of the calibration specimen (nonmagnetic metal), σ represents the conductivity (Ω / m), and μ represents the permeability (H / m).
[Step 3]
The initial frequency f (Hz) calculated in step 2 is calculated through the I / O port 25 and the I / O port 35 of the eddy current film thickness measuring means 3 and the calculation unit 31 of the eddy current film thickness measuring means 3. Is transmitted to. The arithmetic unit 31 applies an AC voltage to the eddy current measurement sensor 4 via the I / O port 35 and the D / A converter 36 at a frequency f (Hz) and a phase angle of 0 degree. The X output and Y output detected by the eddy current measuring sensor 4 are sent to the HDD 32, RAM 33, ROM 34, etc. via the A / D converter 37 and I / O port 35 of the eddy current film thickness measuring means 3, and the arithmetic unit 31. Are recorded in one or more data input means. At the same time, the measurement value of the eddy current measurement sensor 4 is transmitted to the computing unit 21 of the personal computer 2 via the I / O port 35.

  The personal computer 2 records the measurement value of the eddy current measurement sensor 4 and instructs the actuator driver 6 to change the lift-off amount of the eddy current measurement sensor 4 via the I / O port 25.

  The actuator driver 6 transmits the lift-off amount to the calculation unit 61 via the I / O port 65, and the calculation unit 61 is recorded in any one or more data input means such as the HDD 62, RAM 63, ROM 64 and the like. The power supply condition to each of the motors 11A to 11C is determined from the relationship between the movement amount of the first and second moving bases 10B and 10C, the supply voltage value, the supply current value, and the applied voltage time. Based on the power supply conditions, power is supplied to the motors 11A to 11C via the I / O port 65 and the D / A converter 66.

  During power supply, the applied voltage value, application time, and current value are transmitted to the calculation unit 61 via the A / D converter 67 and the I / O port 65, and the calculation unit 61 calculates the actual movement amount. The rotational speed of each of the motors 11A to 11C is adjusted, and the eddy current measurement sensor 4 is moved to the target lift-off amount.

The completion of the movement of the eddy current measuring sensor 4 is transmitted to the computing unit 21 of the personal computer 2 via the I / O port 65 and recorded in any one or more data input means such as the HDD 22, RAM 23, ROM 24, etc. It is displayed on the monitor 28.
[Step 4]
Evaluate the XY output curves when the frequency is 2f (Hz) and the phase angle is 0 degrees, the frequency is f / 2 (Hz) and the phase angle is 0 degrees, and lifted off in the same flow as step 3. To do.
[Step 5]
Each frequency f / 2 (Hz), using a program for analyzing Formula 2 and Formula 3 recorded in any one or more data input means such as HDD 22, RAM 23, ROM 24, etc. in the computing unit 21 of the personal computer 2 The deviation of the Y output when the phase angle is changed at f (Hz) and 2 f (Hz) is calculated.
dy (θ) = dx0 | sin θ | + dy0 | cos θ |
Deviation = [(Y output at phase angle θ degree) − (Y output at phase angle 0 degree)] ÷ [(Y output at phase angle 0 degree) × 100 (%)]
Here, θ is the phase angle, dx0 is the deviation of the X output at the phase angle of 0 °, dy0 is the deviation of the Y output at the phase angle of 0 °, and dy (θ) is the deviation of the Y output at the phase angle of θ °. To express.
[Step 6]
Based on the phase angle dependency of the deviation shown in FIG. 6 obtained in step 5 by the computing unit 21 of the personal computer 2, the minimum deviation of each frequency f / 2 (Hz), f (Hz), 2f (Hz) is obtained. Find the phase angle. In FIG. 6, the solid line indicates the frequency f (Hz), the one-dot chain line indicates the frequency f / 2 (Hz), and the broken line indicates the frequency 2f (Hz).
[Step 7]
When the frequency dependence of the minimum deviation shown in FIG. 7 obtained in step 6 has a minimum point, the calculation unit 21 of the personal computer 2 determines the frequency, for example, 280 k (Hz) as the measurement frequency.

However, when the frequency that does not have the minimum point and gives the minimum deviation is 2f (Hz), the estimated thickness of the calibration specimen is multiplied by 0.7, and the procedures of steps 2 to 6 are repeated. Here, when the estimated thickness is set to 0.7 times, the frequency change range is 2f to 4f (Hz), so that the minimum point can be evaluated in the continuous frequency range. On the other hand, when the frequency that does not have the minimum point and gives the minimum deviation is f / 2 (Hz), the estimated thickness is increased by 1.4 times and the procedures of steps 2 to 6 are repeated. Since the frequency range is f / 2 to f / 4 (Hz) by increasing the estimated thickness by 1.4 times, the minimum point can be evaluated in the continuous frequency range.
[Step 8]
From the keyboard 26 of the personal computer 2 or the recording medium 27, the shape of the nonmagnetic metal M2 that is the object to be measured on the magnetic metal M1 and the position information of the eddy current measuring sensor 4 are input, and the film thickness measurement of the nonmagnetic metal is started. Instruct.

  The shape of the nonmagnetic metal M2 is recorded in any one or more data input means such as the HDD 22, RAM 23, ROM 24, etc. via the I / O port 25 of the personal computer 2. After the input of the shape of the nonmagnetic metal M2, the frequency and phase angle at which the deviation of the Y output determined in step 7 is reduced are transmitted from the calculation unit 21 to the calculation unit 31 of the eddy current film thickness measuring means 3, and this calculation unit An AC voltage is applied from 31 to the eddy current measurement sensor 4 via the I / O port 35 and the D / A converter 36.

  The X output and Y output measured by the eddy current measurement sensor 4 are sent to the HDD 32, RAM 33, ROM 34, etc. via the A / D converter 37, the I / O port 35, and the arithmetic unit 31 of the eddy current film thickness measuring means 3. Record in any one or more data input means. Simultaneously with these recordings, the measurement value of the eddy current film thickness measurement means 3 is transmitted to the computing unit 21 of the personal computer 2 via the I / O port 35, and any one or more of the HDD 22, RAM 23, ROM 24, etc. Record the measurement results in the data input means.

  Further, the eddy current film thickness measuring means 3 transmits the shape data of the nonmagnetic metal M2 input together with the measured value to the calculation unit 61 of the actuator driver 6 via the I / O port 35. In the calculation unit 61 of the actuator driver 6, the base 10 </ b> A recorded in one or more data input means such as the HDD 62, the RAM 63, the ROM 64, and the like so that the eddy current measurement sensor 4 follows the shape of the nonmagnetic metal M <b> 2. The power supply condition to each of the motors 11A to 11C is determined from the relationship between the moving amount of the first moving table 10B and the second moving table 10C, the supply voltage value, the supply current value, and the voltage application time. Based on this power supply condition, the actuator driver 6 supplies power to the actuator 5 via the I / O port 65 and the D / A converter 67. During the power supply to the actuator 5, the applied voltage value, the application time, and the flowing current value are transmitted to the computing unit 61 via the A / D converter 66 and the I / O port 65, and the computing unit 61 performs actual movement. The amount is calculated to adjust the rotation speed of the motors 11A to 11C of the actuator 5, and the eddy current measurement sensor 4 is moved on the nonmagnetic metal M2. The amount of movement of the eddy current measuring sensor 4 is transmitted to the computing unit 21 of the personal computer 2 via the A / D converter 66 and the I / O port 65 of the actuator driver 6, and any one of the HDD 22, RAM 23, ROM 24, etc. It is recorded in the above data input means.

  As described above, according to the present embodiment, by controlling both the frequency and the phase angle, it is possible to minimize the measurement error at the time of lift-off in the nonmagnetic metal to be measured, and to improve the measurement accuracy. Can be improved.

  By the way, the above explanation is to obtain the optimum frequency and phase angle by controlling the frequency and phase angle using a calibration test specimen having the same specifications as the non-magnetic metal. If the optimum frequency and phase angle are determined in advance for each calibration specimen, an appropriate frequency and phase angle can be immediately determined for any nonmagnetic metal.

  Further, in the above embodiment, one sensor is used as the eddy current measuring sensor 4, but as a modification thereof, as shown in FIGS. 8 and 9, a plurality of sensors 4a, 4b,. It is also possible to provide an eddy current measuring multi-sensor 4A arranged side by side. In this way, if the eddy current measuring multisensor 4A is used, the driving direction of the actuator can be reduced as compared with the above embodiment, and accordingly, the configuration of the actuator can be simplified and the inspection time can be shortened. Is possible.

  Next, a second embodiment of the eddy current type nonmagnetic metal film thickness measuring method according to the present invention will be described based on the eddy current type nonmagnetic metal film thickness measuring apparatus 1A shown in FIGS. The same reference numerals as those in FIGS. 1 to 4 denote the same components, and thus detailed description thereof is omitted.

  The present embodiment shows a method for determining whether the film thickness of the nonmagnetic metal is thicker or thinner than the reference film thickness on the basis of the film thickness at the time of replacement of the nonmagnetic metal.

  10 differs from FIG. 1 in that an encoder 14 is provided in place of the actuator driver 6 in FIG. 1, and the tip of the winding cord 15 of the encoder 14 is connected to the eddy current measuring sensor 4 so that the eddy current measuring sensor 4 is connected. This is the point that is moved manually. 4 differs from FIG. 11 in that the A / D converter 29 is provided in the personal computer 2 in FIG. 11 and the eddy current film thickness measuring means 3A in FIG. 11 measures the eddy current film thickness in FIG. The operation part 31, HDD 32, RAM 33, and ROM 34 of the means 3 are removed.

Next, a procedure for measuring the film thickness of the nonmagnetic metal on the magnetic metal using the eddy current type nonmagnetic metal film thickness measuring apparatus 1A having the above configuration will be described.
[Step 21]
Using the one or more input devices of the keyboard 26 or the recording medium 27 of the personal computer 2, the dielectric constant and permeability of the nonmagnetic metal M2, which is the measurement object on the magnetic metal M1, and the nonmagnetic metal M2 are exchanged. A reference film thickness is input and transmitted to the calculation unit 21 via the I / O port 25. The computing unit 21 computes the frequency using a program for calculating Equation 1 stored in any one or more data input means such as the HDD 22, RAM 23, ROM 24, and the like.
[Step 22]
The calculation result of step 21 is transmitted to the I / O port 35 of the eddy current film thickness measuring means 3A via the I / O port 25, and from there to the eddy current measuring sensor 4 via the D / A converter 36. Apply voltage. The X and Y outputs of the induced magnetic field measured by the eddy current measuring sensor 4 are sent to the I / O port of the personal computer 2 via the A / D converter 37 and the I / O port 35 of the eddy current film thickness measuring means 3A. 25, and is recorded in any one or more data input means such as HDD 22, RAM 23, ROM 24, etc. via the arithmetic unit 21.

During the measurement by the eddy current measurement sensor 4, the eddy current measurement sensor 4 is lifted off by hand, and the detection signal from the eddy current measurement sensor 4 at that time is acquired.
[Step 23]
The calculation unit 21 of the personal computer 2 calculates the phase angle dependency of the deviation of the Y output using a program for calculating Equations 2 and 3 recorded in any one or more data input means such as the HDD 22, RAM 23, ROM 24, etc. Then, the phase angle that minimizes the deviation of the Y output is obtained.
[Step 24]
The calculation result in step 23 is transmitted to the eddy current type film thickness measurement means 3A via the I / O port 25, and the D / A converter uses the frequency as the calculation value in step 21 and the phase angle as the evaluation result in step 23. An AC voltage is applied to the eddy current measurement sensor 4 via 36.

  The X output and Y output measured by the eddy current measurement sensor 4 are transmitted to the I / O port 25 of the personal computer 2 via the A / D converter 37 and the I / O port 35, and the HDD 22, The data is recorded in any one or more data input means such as the RAM 23 and the ROM 24.

Then, the encoder 14 is fixed on the nonmagnetic metal M2 that is the measurement object, and the eddy current measurement sensor 4 is manually moved along the nonmagnetic metal M2, so that the take-up cord 15 of the encoder 14 is moved to a moving amount. The position of the eddy current measuring sensor 4 is measured by drawing out the winding cord 15 with the encoder 14. The measurement result is transmitted to the calculation unit 21 via the A / D converter 29 and the I / O port 25 of the personal computer 2, and the position information of the eddy current measurement sensor 4 is stored in one or more of the HDD 22, RAM 23, ROM 24, etc. While recording in the data input means, the output and position information of the eddy current measurement sensor 4 are displayed on the monitor 28.
[Step 25]
The output of the eddy current measurement sensor 4 displayed on the monitor 28 is compared with the film thickness reference at the time of replacement of the nonmagnetic metal, and it is determined whether or not the nonmagnetic metal M2 as the measurement object has reached the replacement time. .

  As described above, according to the present embodiment, since the frequency and the phase angle can be set within a certain range, the measurement of the film pressure of the nonmagnetic metal is simplified as compared with the first embodiment, and the measurement time is reduced. Shortening can be achieved.

The block diagram which shows the eddy current type nonmagnetic metal film thickness measuring apparatus for enforcing 1st Embodiment of the eddy current type nonmagnetic metal film thickness measuring method by this invention. The perspective view which shows the eddy current measurement sensor used for the eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIG. The perspective view which shows the actuator used for the eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIG. The signal transmission figure of the eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIG. The graph which shows the nonmagnetic metal thickness dependence of a frequency. Graph showing the dependence of Y output fluctuation rate and phase angle. A graph showing the dependence of Y output fluctuation rate and frequency. The schematic side view which shows the modification of the eddy current measurement sensor used for the eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIG. FIG. 9 is a cross-sectional plan view taken along line AA in FIG. 8. The block diagram which shows the eddy current type nonmagnetic metal film thickness measuring apparatus for enforcing 2nd Embodiment of the eddy current type nonmagnetic metal film thickness measuring method by this invention. The signal transmission figure of the eddy current type nonmagnetic metal film thickness measuring apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Eddy current type nonmagnetic metal film thickness measuring apparatus, 2 ... Personal computer, 3 ... Eddy current type film thickness measuring means, 4 ... Eddy current measuring sensor, 4A ... Eddy current measuring multi-sensor, 5 ... Actuator, 6 ... Actuator Driver, 7 ... Core, 8 ... Coil, 9 ... Shield material, 10A ... Base, 10B ... First moving table, 10C ... Second moving table 10C, 11A-11C ... Motor, 12A-12C ... Screw rod, 13A- 13C: moving piece, 14 ... encoder, 15 ... winding code.

Claims (6)

  An eddy current type non-magnetic eddy using a eddy current type film thickness measuring means for detecting the induced magnetic field caused by the eddy current generated in the non-magnetic metal on the magnetic metal by the exciting coil and measuring the film thickness of the non-magnetic metal. In the magnetic metal film thickness measurement method, the excitation coil and the detection coil are installed on a calibration test specimen having the same specifications as the non-magnetic metal, and the frequency of the excitation current supplied to the excitation coil is set to a value suitable for each calibration test specimen. The phase angle of the excitation current is adjusted based on the selected frequency and the phase angle of the excitation current that is output from the detection coil installed on the calibration specimen is selected to reduce the variation rate of the imaginary part. And measuring the film thickness of the non-magnetic metal by the eddy current film thickness measuring means based on the frequency and phase angle determined by these processes. Gender metal film thickness measurement method.   An eddy current type non-magnetic eddy using a eddy current type film thickness measuring means for detecting the induced magnetic field caused by the eddy current generated in the non-magnetic metal on the magnetic metal by the exciting coil and measuring the film thickness of the non-magnetic metal. In the magnetic metal film thickness measurement method, the frequency of the excitation current to be supplied to the excitation coil by installing the excitation coil and the detection coil on a plurality of calibration test bodies formed in advance in a plurality of specifications is specified for each calibration test specimen. And adjusting the phase angle of the excitation current based on the selected frequency to reduce the variation rate of the imaginary part output from the detection coil in accordance with each calibration specimen. A step of selecting a phase angle, and a step of selecting a frequency and a phase angle determined by these steps according to the nonmagnetic metal and measuring the film thickness of the nonmagnetic metal by the eddy current film thickness measuring means. Eddy current type magnetic metal film thickness measuring method characterized by comprising and.   An eddy current type non-magnetic eddy using a eddy current type film thickness measuring means for detecting the induced magnetic field caused by the eddy current generated in the non-magnetic metal on the magnetic metal by the exciting coil and measuring the film thickness of the non-magnetic metal. In the magnetic metal film thickness measurement method, the excitation coil and the detection coil are installed on a calibration specimen formed to have the same conductivity, permeability and non-magnetic metal film thickness as the non-magnetic metal, and the excitation The step of selecting the frequency of the excitation current to be supplied to the coil to a value suitable for each calibration specimen, and the detection that is installed on the calibration specimen by adjusting the phase angle of the excitation current based on the selected frequency The step of selecting a phase angle at which the fluctuation rate of the imaginary part output from the coil is small, and the film thickness of the nonmagnetic metal by the eddy current film thickness measuring means based on the frequency and phase angle determined by these steps Eddy current type magnetic metal film thickness measuring method characterized by comprising the step of measuring.   Install the eddy current measurement sensor on a calibration specimen with the same specifications as the non-magnetic metal, select the frequency of the excitation current supplied to the eddy current measurement sensor to a value suitable for each calibration specimen, and based on the selected frequency Adjusting the phase angle of the excitation current to select the phase angle at which the fluctuation rate of the imaginary part output from the eddy current measurement sensor installed on the calibration specimen is reduced, and the frequency determined by these steps An eddy current type nonmagnetic metal film thickness measuring method including a step of measuring a film thickness of a nonmagnetic metal based on a phase angle. The step of selecting the frequency of the excitation current includes:
(Frequency) = (Thickness) ² ÷ (2 × π × Conductivity × Permeability)
A step of calculating a reference frequency by the formula of, and the step of selecting the phase angle,
Deviation = [(output of imaginary part of eddy current type film thickness measuring means when detection coil is lifted) − (output of imaginary part of eddy current type film thickness measuring means when detection coil is not lifted)] ÷ ( The output of the imaginary part of the eddy current film thickness measuring means when the detection coil is not lifted)
The phase angle dependence of the deviation defined by
(Deviation of imaginary part of eddy current film thickness measuring means output at phase angle 0 degree) × sin (phase angle) + (deviation of real part of eddy current film thickness measuring means output at phase angle 0) × cos (phase angle)
5. The eddy current type nonmagnetic metal film thickness measuring method according to claim 1, further comprising a step of determining a phase angle in which an error is reduced by calculating the following equation.   An eddy current type non-magnetic eddy using a eddy current type film thickness measuring means for detecting the induced magnetic field caused by the eddy current generated in the non-magnetic metal on the magnetic metal by the exciting coil and measuring the film thickness of the non-magnetic metal. In the magnetic metal film thickness measuring device, the excitation coil and the detection coil are installed on a calibration test specimen having the same specifications as the non-magnetic metal, and the frequency of the excitation current supplied to the excitation coil is set to a value suitable for each calibration test specimen. A frequency selection means to select, and a phase angle that adjusts the phase angle of the excitation current based on the selected frequency and reduces the variation rate of the imaginary part output from the detection coil installed on the calibration specimen. The non-magnetic metal film thickness is measured by the eddy current film thickness measuring means based on the phase angle selecting means for selecting the frequency and the frequency and phase angle determined by the frequency selecting means and the phase angle selecting means. Thickness measuring means and the eddy current type magnetic metal film thickness measuring apparatus comprising the.

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