JP2020173230A - Permeability measuring device - Google Patents

Abstract

To solve the problem in which: there is an increasing demand for non-magnetic guarantees for non-magnetic steel materials such as the construction of the Linear Shinkansen, and along with it, there is a need to develop a pencil-type permeability measuring instrument capable of an easy non-magnetic inspection; since miniaturization, low power consumption, and high sensitivity are contradictory characteristics, it has been difficult to solve them by conventional techniques.SOLUTION: The present invention develops a differential micro-coil driven by a high frequency current of 100 kHz to 10 MHz, uses the micro-coil to combine a high frequency, a large number of coil turns per unit length, and high effective magnetic permeability of an elongated magnetic core rod (magnetic wire), enables ultra-miniaturization of current detectors, significant reduction in power consumption, and miniaturization of batteries, and produces a pencil-type wearable permeability measuring device while maintaining the excellent magnetic permeability detection performance of current high-sensitivity permeability meters.SELECTED DRAWING: Figure 4

Description

The present invention relates to an apparatus for measuring the magnetic permeability of a non-magnetic metal material such as stainless steel or manganese steel.

With the construction of the linear Shinkansen, superconducting magnets, structural members of the vehicle body (pedestals, columns, beams, covers, rods, shafts, bolts, nuts, washer, flanges, pipes, bearings, motors, pump molds, bearings, etc.) and rails Non-magnetic steel is used for the steel frame and equipment of the surrounding structures, and a reliable guarantee of its non-magnetism is required. For that purpose, shipping inspection and acceptance inspection and inspection of each part of superconducting magnets, vehicle body and building structure at each stage from refining non-magnetic steel to rolling, refining, secondary processing, and parts processing. Is needed. In order to smoothly process a huge amount of inspection work, it is necessary to develop a wearable magnetic permeability measuring device, that is, a pencil-type magnetic permeability measuring device, which can be worn and inspected by the persons concerned.

Non-magnetic steel has been developed and used as a structural material for generators, motors, transformers, etc. that need to prevent power loss and heat generation. In addition, the disturbance of the magnetic field causes the disturbance of information equipment such as electronic devices such as VTRs, copiers, electron microscopes, and televisions, which were invented with the expansion of the electronics industry, and mobile information devices such as smartphones, robots, and drones with built-in magnetic sensors. Its use is expanding for applications that lead to. Furthermore, with the full-scale spread of MRIs that use strong superconducting magnets, linear motors, and magnetic sensors that detect micromagnetic fields based on the principle of superconductivity, the non-magnetic guarantee of special parts and the non-magnetism of all parts including peripheral members We are in an era where guarantees are strongly required.

Standards for magnetic steel include the US federal standard and the MIL standard, which stipulate standards with a magnetic permeability of 1.2 or less. Standards with a magnetic permeability of 1.02 or less are used in advanced industrial fields such as electronic devices, mobile information devices, and super electric magnets. As a magnetic permeability measuring device, a magnet type was developed corresponding to a standard with a magnetic permeability of 1.2 or less, and then a device applying the eddy current flaw detection principle was developed to comply with a standard with a magnetic permeability of 1.02 or less. , Mainly used for magnetic permeability inspection of non-magnetic steel materials.

In 1991, it was possible to measure the magnetic permeability of small parts and welded materials of various shapes from a minute value of magnetic permeability of 1.002, and it was a portable device with sufficient functions as an inspection device for standard products with magnetic permeability of 1.02 or less. A type of device is disclosed by the present inventor (Patent Document 1, Non-Patent Document 1).
This device (hereinafter referred to as the current product) has a differential transformer configuration consisting of one exciting coil wound around one magnetic wire and two detection coils arranged differentially so as to sandwich the exciting coil. Difference between a transmitter circuit that transmits an AC signal that excites a probe-type detector and an exciting coil, and an electrical signal that detects the effects of magnetic permeability and conductivity of the material to be measured by bringing one end of the detector into contact with the sample to be measured. It consists of a phase detection circuit that analyzes the phase of a dynamic signal processing circuit and its output signal, extracts only an electric signal based on the magnetic permeability of the sample to be measured, and converts it into DC, and a reference signal generation circuit. The reference signal generation circuit includes a single exciting AC signal that excites the exciting coil of the detector, and a phase circuit that adjusts the phase of the AC signal and supplies the reference signal to the phase detection circuit. The output voltage E from the differential detection coil is composed of two components, an output voltage Ec due to the influence of the eddy current of the non-magnetic sample and a voltage Em due to the influence of the magnetic component of the sample. Focusing on the difference in phase between the two, the reference voltage of the phase detection circuit is applied so as to be perpendicular to the voltage Ec due to the influence of the eddy current, and the voltage component is removed, so that the magnetic permeability of the sample to be measured is proportional. It is possible to output an electric signal.
Among these, the number of turns N1 of the exciting coil, the number of turns N2 of the detection coil, and the strength I (A) of the exciting current are N1.
It is clarified that when the value of × N2 × I is 1000 or more, the detecting force can detect the magnetic permeability of 1.002. Moreover, it has been clarified that the magnetic permeability of a small sample having a diameter of 2 mm or less can be measured by reducing the distance between the two detection coils to about 3.5 mm.

The present invention aims to develop a pencil-type magnetic permeability measuring device capable of measuring the magnetic permeability of 1.002 and measuring the magnetic permeability of small parts of various shapes and welded materials from steel materials.

Japanese Unexamined Patent Publication No. 3-255380

Honzo et al .; Journal of the Japan Society of Applied Magnetics 15, 469-474 (1991)

In order to improve the portable type to the pencil type, the size of the detector should be reduced from 5 mm to 1 mm or less in diameter and 8 mm in length to 6 mm or less, that is, 30 to 100 times smaller, and magnetic for that purpose. The diameter of the core rod should be 1 mm to 0.2 mm or less, the board size of the electronic circuit should be 50 mm wide x 50 mm long, 10 mm wide or 40 mm long, and the power supply should be 100 V or two alkaline batteries. It is necessary to change from to a small battery with a diameter of 5 mm or less to realize a significant miniaturization of the device.

Patent Document 1 discloses that the detection sensitivity of the magnetic permeability measuring device is proportional to the number of turns N1 of the exciting coil, the number of turns N2 of the detection coil, and the strength I of the exciting current. Moreover, since it is expected to be proportional to the cross-sectional area of the detector, it is expected that the detection sensitivity will be significantly reduced just by reducing the size. Further, if the exciting current is reduced to reduce the power consumption, it is expected that the detection sensitivity will be significantly reduced. In other words, performance such as detection sensitivity and power consumption of magnetic permeability measuring device and miniaturization tend to be contradictory, and it is a difficult task to develop a small magnetic permeability measuring device with high detection sensitivity and excellent power consumption characteristics. is there.

In order to solve the above-mentioned contradictory problem, the inventors came up with the idea of increasing the exciting current from the current product of 1 kHz to 100 kHz to 10 MHz, and worked on miniaturization of the detector and reduction of current consumption. In order to suppress the eddy current associated with high frequency, we decided to use a Co-based amorphous wire with a diameter of 5 μm to 100 μm for the magnetic mandrel, and the reduction in the number of turns of the exciting coil and the detection coil due to the miniaturization of the detector is due to the coil pitch. By adopting a microcoil with an inner diameter of 10 μm to 120 μm of 10 μm or less, the number of exciting coil turns N1, the number of detected coil turns N2, the exciting current strength I, the cross-sectional area S of the magnetic core rod, and the frequency f of the exciting current , The effect of sensitivity such as the length of the magnetic core rod, the effective magnetic permeability μ of the magnetic core rod, and the resistance ρ of the magnetic core rod was studied diligently.

As a result, the detection sensitivity is not only proportional to the number of excitation coil turns N1 (times), the number of detection coil turns N2 (times), and the exciting current strength I (mA), but also the effective magnetic permeability μ of the magnetic core rod and its diameter. It was found that it is proportional to d ^1.5, which is proportional to d (mm), and is almost proportional to f ^1.5, which is the frequency f (kHz) of the exciting current. That is, the detection sensitivity K is necessary to secure a K ≧ 3 × 10 ⁷ in order to detect that it is manifested by K = N1 × N2 × I × μ × d 1.5 × f 1.5, and permeability 1.002 It turned out that there is.

Assuming that the coil turns N1 and N2 of the detector are almost the same as those of the current product by utilizing the microcoil, if the diameter of the magnetic core rod is changed from 1 mm to 0.01 mm, the sensitivity will be significantly reduced. The decrease is due to the increase in the effective magnetic permeability of the magnetic core rod from 800 to 10,000 of the current product, and the increase in the exciting current frequency from 1 kHz to 1 MHz, which is 1,000 times stronger. It was confirmed that the detection sensitivity of magnetic permeability of 1.002 can be obtained even if the current product is reduced from 33 mA to 3 mA to 1/10 or less. Based on these new findings, it was found that a small magnetic permeability measuring device having high detection sensitivity and excellent power consumption characteristics can be invented.

The present invention enables a pencil-type magnetic permeability measuring device, which enables a significant reduction in size and power consumption as compared with the current magnetic permeability measuring device, and is a non-magnetic inspection that increases with the linear Shinkansen. It meets the needs.

It is a figure which shows the detection principle. It is a figure which shows the basic circuit. It is a figure which shows the phase detection function. It is a figure which shows the appearance of the pencil type ultra-compact magnetic permeability measuring apparatus of Example 1. FIG. It is a figure which shows the relationship between the magnetic permeability of the sample to be measured, and the output voltage. It is a figure which shows the relationship between the detection force of magnetic permeability 1.002, the diameter of a magnetic mandrel, and the excitation frequency. It is a figure which shows the measurement mode and sleep mode of Example 2.

<First Embodiment>
The ultra-compact magnetic permeability measuring device (hereinafter referred to as a measuring device) of the first embodiment includes a detector, an electronic circuit, and a display.
The detector has a differential transformer configuration having a diameter of 1 mm or less, which includes one exciting coil wound around one magnetic wire and two detection coils arranged differentially so as to sandwich the exciting coil. It is a probe type detector and has a function of detecting the influence of magnetic permeability and conductivity of the sample to be measured as an electric signal by bringing one end of the detector into contact with the sample to be measured.
The diameter of the magnetic wire is 5 μm to 100 μm, the exciting coil and the detection coil consist of microcoils with a coil pitch of 10 μm or less and an inner diameter of 10 μm to 120 μm, the number of turns of which is 100 to 1000 times, and the distance between the two detection coils. Is 3.5 mm or less.

The electronic circuit includes a transmission circuit, a signal processing circuit, and a reference signal generation circuit.
The transmission circuit transmits an AC signal having a current strength of 10 mA or less at a frequency of 100 kHz to 10 MHz that excites the exciting coil.
The signal processing circuit is a differential amplification circuit having a zero point correction function that adjusts the output signal to 0V when one end of the detector is not in contact with the sample to be measured, and the output of the corrected differential amplification circuit. For the magnetic permeability of the sample to be measured after detection by a phase detection circuit and a phase detection circuit that have a phase angle adjustment function that can perform phase analysis of the signal and extract only the electrical signal based on the magnetic permeability of the sample to be measured and convert it to DC. It consists of an output circuit that outputs a proportional voltage.
The reference generation signal circuit includes a sine wave generation circuit that generates a sine wave that excites the exciting coil of the detector, and a phase circuit that generates a reference vector signal whose phase of the sine wave is adjusted.
The display displays a DC signal based on the magnetic permeability of the material to be measured.

Hereinafter, each configuration will be described with reference to FIGS. 1 to 3.
The configuration of the detector and the detection principle will be described with reference to the detection principle of FIG.
The detector 1 is composed of one exciting coil 12 wound around a magnetic wire 11 which is one magnetic core rod, and two detection coils 13 (13a) differentially arranged so as to sandwich the exciting coil 12. It is a probe type detector having a differential transformer configuration consisting of and 13b).

Next, the detection principle of the detector 1 is that an alternating current is passed through the exciting coil 12 to bring one end of the magnetic wire 11 into contact with the sample 20 to be measured, and the sample 20 is subjected to alternating magnetization and eddy current (shown in FIG. 1). ) Is generated to detect the influence of the magnetic permeability and the conductivity of the sample 20 to be measured as an electric signal.

The size of the probe type detector 1 is a small size having a diameter of 1 mm or less and a length of 6 mm or less. This enables a pencil-sized ultra-compact magnetic permeability measuring device.
The parts constituting the small-sized detector 1 are made of Co-based amorphous magnetic wire 11 and its diameter (d) is miniaturized to 5 μm to 100 μm, while its specific magnetic permeability (μ) is 5,000 to 50. Increase it to 000 and set the resistivity to 50 μΩcm to 150 μΩcm.

The exciting coil 12 is a microcoil having a diameter of 10 μm to 20 μm, and is arranged at the center of the magnetic wire 11 with a length of 1 mm to 3 mm. Next, the detection coil 13 is a microcoil having a diameter of 10 μm to 120 μm, and is arranged differentially on both sides of the exciting coil 12 with a length of 1 mm to 3 mm (13a and 13b).
The number of coil turns per unit length of the exciting coil 12 and the detection coil 13 can be increased to 50 times / mm to 500 times / mm by micronizing both coils. Further, the number of coil turns (N1) of the exciting coil 12 and the number of coil turns (N2) of the detection coil 13 are increased to 100 to 1000 times. Further, the distance between the two detection coils 12 is reduced to 3.5 mm or less to enable measurement of the magnetic permeability of a small sample having a diameter of 2 mm or less.

The electronic circuit will be described with reference to the basic circuit of FIG.
The electronic circuit includes a transmission circuit (not shown), a signal processing circuit 30, and a reference signal generation circuit 40, and includes a display 50 that displays an output result.
The transmission circuit transmits an AC signal that excites the exciting coil 12, that is, an AC signal whose frequency (f) is increased to 100 kHz to 10 MHz and whose current strength (I) is 2 mA to 10 mA.

The signal processing circuit 30 includes a differential amplifier circuit 31, a phase detection circuit 32, and an output circuit 33.
The differential amplifier circuit 31 detects the influence of the magnetic permeability and conductivity of the material to be measured 2 as an electric signal by contacting one end of the detector with the sample to be measured, and at the same time, contacts one end of the detector with the sample to be measured. It has a zero point correction function that adjusts the output signal to 0V when it is not allowed to move.
The phase detection circuit 32 has a phase angle adjustment function at the same time as performing phase analysis of the output signal corrected by the differential amplification circuit 31 and extracting only an electric signal based on the magnetic permeability of the sample to be measured and converting it into DC.
FIG. 3 shows the function of the phase detection circuit 32. In FIG. 3, I indicates the intensity of the exciting current. Hereinafter, E is the output voltage, Ec is the voltage generated by the eddy current of the non-magnetic sample, Em is the voltage generated by the magnetism of the magnetic sample, E is the reference signal, and φ is the reference signal. The phase angles of are shown respectively. The phase detection circuit outputs the projection component EmcosΦ of the output signal E to the reference signal Ey as a voltage, and the output voltage is proportional to the magnetic strength of the material, that is, the magnetic permeability.
The output circuit 33 outputs a voltage proportional to the magnetic permeability of the sample 2 to be measured after being detected by the phase detection circuit 32 and the detection circuit.

The reference generation signal circuit 40 is a sine wave generation circuit 41 that excites the excitation coil 11 of the detector 1 and a phase shift circuit 42 that generates a reference signal of the phase detection circuit.
The above-mentioned basic circuit and detection principle are as described in detail in Patent Document 1 (Japanese Patent Laid-Open No. 3-255380) and Non-Patent Document 1 previously disclosed by the present inventor.

The power supply circuit (not shown) supplies the exciting coil 12 of the detector 10 with electric power having a current strength of 10 mA or less and electric power necessary for operating the measurement circuit.

The power supply may be of any size, weight, output voltage and capacity as long as a pencil-type measuring device can be configured. As an example, one small lithium battery having a diameter of 4.7 mm, a length of 25 mm, a weight of 1 g, an output voltage of 3.8 V, and a capacity of 32 mAh is used.

The adjustment of the measuring device is that the output voltage difference from the two detection coils (12a, 12b) is 100 μV or less when the full scale is ± 1000 mV when the detector is not in contact with the sample to be measured, that is, 0. The symmetry of the two detection coils (12a, 12b) is ensured so that the error is 01% or less. This error can be removed by installing a zero point correction circuit. Next, when the detector 1 is in contact with the non-magnetic sample 2 to be measured, the phase angle of the reference vector signal of the phase detection circuit 3 is adjusted by the phase angle adjustment circuit so that the signal voltage after the phase detection becomes 0V. To do.

The detection sensitivity K is expressed by K = N1 × N2 × I × μ × d ^1.5 × f ^1.5 . As the K ≧ 3 × 10 ⁷ in order to detect the magnetic permeability 1.002, adjusted N1, N2, I, mu, d, and f in the above range. Further, in order to avoid affecting the size of the sample to be measured, the distance between the two detection coils (12a, 12b) is 3.5 mm or less.

The measurement is performed by bringing the detector 10 into contact with the micromagnetic sample 20 to be measured, and the output voltage has a linear relationship with the magnetic permeability. In addition, the output circuit can be used for analog output, digital output, and even display on a personal computer screen in real time. In the case of digital output, the measurement interval is 20 ms, that is, 50 Hz. The performance of the measuring device can measure a wide range of magnetic permeability from 1.00 to 2.00, and even a minute magnetic permeability of 1.002 can be detected.

<Second Embodiment>
In the second embodiment, in the digital output type of the first embodiment, the output interval time of the measurement data is divided into the measurement mode time and the sleep mode time, the measurement time is set to 1/10 or less of the measurement interval, and the signal voltage is digitally set. It is an output, and is a preferred embodiment in which the power consumption required for measurement is reduced to at least 1/10 or less.

In order to divide into the measurement mode time and the sleep mode time, a control circuit (not shown) that turns ON and OFF is attached to the electronic circuit, and a hold circuit (not shown) that holds the output after phase detection in synchronization with it is installed. It is provided, measured in the ON state, the signal voltage is held and output, and the same signal voltage is output even in the OFF state. As a result, the same signal voltage is output during the measurement interval of 50 Hz. Output.

<Third Embodiment>
In the third embodiment, the measuring devices of the first embodiment and the second embodiment are built in a pencil-shaped case. This will be described with reference to FIG.
A detector 61 is attached to the tip, an electronic circuit 65 and a battery 66 are built in, and a display 67, a power switch 62 of the measuring instrument, a zero point adjustment knob 63, and a phase angle adjustment knob 64 are attached to the exterior. The size of the tip portion is a spindle shape with a diameter of 0.5 mm to 1 mm and a length of 4 mm to 6 mm. The total length of the main body of the measuring device 6 is 10 cm to 16 cm, and the diameter is 8 mm to 14 mm.

[Example 1]
The first embodiment of the present invention is a combination of the first embodiment and the third embodiment, and as shown in FIG. 4, the detector 10, the electronic circuit, the power supply, and all of them are built in a pencil-shaped case. The magnetic coefficient measuring device 60. A detector 61 was attached to the tip of the measuring device 60, an electronic circuit 65 and a battery 66 were built in, and a display 67, a power switch 62 zero point adjustment knob 63, and a phase angle adjustment knob 64 were attached to the exterior part. The size of the tip is a spindle shape with a diameter of 1 mm and a length of 6 mm. The main body of the measuring device 60 has a total length of 14 cm and a diameter of 10 mm.

The detector 61 (1) is a differential transformer composed of one exciting coil 12 wound around one magnetic wire 11 and two detection coils (13a, 13b) arranged differentially so as to sandwich the exciting coil 12. It is a probe type of configuration.
First, the size of the detector 61 is 0.5 mm in diameter and 6 mm in length. This enables a pencil-sized ultra-compact magnetic permeability measuring device. First, the components of the detector 61 (1) have a magnetic wire 10 having a diameter of 10 μm, a relative magnetic permeability of 8,000, and a resistivity of 130 μΩcm. The exciting coil 11 is a microcoil having a diameter of 18 μm and a length of 2 mm, and is arranged at the center of the magnetic wire 10 having a diameter of 10 μm. The detection coil 12 is a microcoil having an inner diameter of 18 μm, a coil pitch of 5 μm, and a length of 2 mm, and is arranged differentially on both sides of the exciting coil 11. The number of coil turns per unit length is 200 times / mm. The number of coil turns of the exciting coil 11 (N1) and the detection coil 12 (N2) is 300. Further, the distance L between the two detection coils (12a and 12b) is reduced to 3.5 mm (FIG. 2) to enable measurement of the magnetic permeability of a small sample having a diameter of 2 mm or less.

The electronic circuit is an AC signal that excites the exciting coil 12, that is, a transmission circuit that transmits an AC signal whose frequency (f) is 1 MHz and whose current strength (I) is 3 mA, and one end of the detector 61 is a sample to be measured. The output signal is adjusted to 0V without contacting one end of the differential amplification circuit 31 and the detector 61, which detects the influence of the magnetic permeability and conductivity of the material to be measured as an electric signal by contacting the sample to be measured. The zero point correction circuit, the phase detection circuit 32 (including the phase angle adjustment circuit) that performs phase analysis of the corrected output signal and extracts only the electrical signal based on the magnetic permeability of the sample to be measured and converts it to DC. An output circuit 32 that outputs a voltage proportional to the magnetic permeability of the sample to be detected after detection, and a reference signal generation circuit that generates a single excitation signal that excites the excitation coil of the detector and a reference vector signal of the phase detector. It consists of 4 and a power supply circuit that supplies power to the measuring device.

The power source is a small lithium battery having a diameter of 4.7 mm, a length of 25 mm, a weight of 1 g, an output voltage of 3.8 V, and a capacity of 32 mAh.

The adjustment of the measuring device is that the output voltage difference from the two detection coils (13a and 13b) is ± 1000 mV when the full scale is ± 1000 mV when the detector 61 (1) is not in contact with the sample 2 to be measured. The symmetry of the two detection coils (12a and 12b) is ensured so that the error is 100 μV or less, that is, 0.01% or less. This error can be removed by installing a zero point correction circuit. Next, when the detector is in contact with the non-magnetic sample to be measured, the phase angle of the reference signal of the phase detection circuit 32 is adjusted by the phase angle adjustment circuit so that the signal voltage after the phase detection becomes 0V.

The detection sensitivity K is expressed by K = N1 × N2 × I × μ × d ^1.5 × f ^1.5 . To detect magnetic permeability 1.002, like a K ≧ 3 × 10 ^7, adjusted N1, N2, I, mu, d, and f in the above range. Specifically, N1, N2 = 300 times, I = 3mA, μ = 8000, d = 10μm, f = 1MHz. At this time it becomes K = 8.5 × 10 ^7, the conditions for the sensitivity secure, which satisfies the K ≧ 3 × 10 ^7.
Further, in order to avoid affecting the size of the sample 2 to be measured, the distance between the two detection coils (13a and 13b) is 3.5 mm or less.

Regarding the results of measurement using this measuring device 60, FIG. 5 shows the relationship between the magnetic permeability of the sample to be measured and the output voltage, and FIG. 6 shows the diameter (d) of the magnetic core rod and the excitation frequency (which affect the detection sensitivity). The influence of f) is shown. The measurement is performed by bringing the detector 61 into contact with the sample 20 to be measured having a diameter of 2 mm. The output circuit is digitally output and displayed on the personal computer screen in real time. In the case of the digital output, the measurement interval is 20 ms, that is, 50 Hz.

First, from FIG. 5, it is obtained that there is a linear relationship with the output voltage when the magnetic permeability (μ) of the sample 20 to be measured is changed. From this, the performance of the measuring device can measure a wide range of magnetic permeability from 1.000 to 2.000, and can also detect a minute magnetic permeability of 1.002.
Next, FIG. 6 shows the result of measuring the magnetic permeability of the sample 2 to be measured having a magnetic permeability of 1.005, and "measurable" means that the value of the magnetic permeability appearing on the display 67 of the measuring device 60 can be measured. The case where "measurement is impossible" means that the measurement error is about the same as 1.005. 6, when satisfying K ≧ 3 × 10 ⁷ show that measuring device 6 is capable to accurately measure the permeability of the sample to be measured.

[Example 2]
In Example 2, based on Example 1, as shown in FIG. 7, the measurement interval time of 20 msec of the measurement data is divided into a measurement mode time of 0.2 msec and a sleep mode time of 19.8 msec for measurement. The time is set to 1/100 of the measurement interval, and the power consumption required for the measurement is reduced to about 1/100. For that purpose, a control circuit that turns on and off the electronic circuit is attached, and a hold circuit that holds the output after phase detection in synchronization with it is provided, and the measurement is performed in the ON state, the signal voltage is held and output, and the signal voltage is turned off. Even in the state, the same signal voltage is output. As a result, the same signal voltage is output during the measurement interval of 50 Hz.

The present invention has realized a pencil-type magnetic permeability measuring device, which enables a significant reduction in size and power consumption as compared with the current product magnetic permeability measuring device. Taking the opportunity of the Linear Shinkansen, non-magnetic steel is used for the steel frames and equipment of superconducting magnets, structural members of the vehicle body, and structures around rails, and rolling from the stage of refining non-magnetic steel with a reliable guarantee of non-magnetism. It meets the increasing non-magnetic guarantee needs at each stage from precision, secondary processing, parts processing and assembled structures.

10: Detector 11: Magnetic core rod (magnetic wire), 12: Excitation coil, 13a: Detection coil: 13b: Detection coil, 13: Detector tip 20: Sample to be measured 30: Signal processing circuit 31: Differential amplification Circuit (with zero point adjuster), 32: Phase detection circuit (with phase angle adjuster), 33: Output circuit (digital conversion, etc.)
40: Reference signal generation circuit 41: Sine wave generation circuit, 42: Phase circuit 50: Display 60: Ultra-compact magnetic permeability measuring device (measuring device)
61: Detector, 62: Power switch, 63: Zero point correction knob, 64: Phase angle correction knob,
65: Electronic circuit (built-in), 66: Battery (built-in), 67: Display

The present invention relates to an apparatus for measuring the magnetic permeability of a non-magnetic metal material such as stainless steel or manganese steel.

With the construction of the linear Shinkansen, superconducting magnets, structural members of the vehicle body (pedestals, columns, beams, covers, rods, shafts, bolts, nuts, washer, flanges, pipes, bearings, motors, pump molds, bearings, etc.) and rails Non-magnetic steel is used for the steel frame and equipment of the surrounding structures, and a reliable guarantee of its non-magnetism is required. For that purpose, shipping inspection and acceptance inspection and inspection of each part of superconducting magnets, vehicle body and building structure at each stage from refining non-magnetic steel to rolling, refining, secondary processing, and parts processing. Is needed. In order to smoothly process a huge amount of inspection work, it is necessary to develop a wearable magnetic permeability measuring device, that is, a pencil-type magnetic permeability measuring device, which can be worn and inspected by the persons concerned.

Non-magnetic steel has been developed and used as a structural material for generators, motors, transformers, etc. that need to prevent power loss and heat generation. In addition, the disturbance of the magnetic field causes the disturbance of information equipment such as electronic devices such as VTRs, copiers, electron microscopes, and televisions, which were invented with the expansion of the electronics industry, and mobile information devices such as smartphones, robots, and drones with built-in magnetic sensors. Its use is expanding for applications that lead to. Furthermore, with the full-scale spread of MRIs that use strong superconducting magnets, linear motors, and magnetic sensors that detect micromagnetic fields based on the principle of superconductivity, the non-magnetic guarantee of special parts and the non-magnetism of all parts including peripheral members We are in an era where guarantees are strongly required.

Standards for magnetic steel include the US federal standard and the MIL standard, which stipulate standards with a magnetic permeability of 1.2 or less. Standards with a magnetic permeability of 1.02 or less are used in advanced industrial fields such as electronic devices, mobile information devices, and super electric magnets. As a magnetic permeability measuring device, a magnet type was developed corresponding to a standard with a magnetic permeability of 1.2 or less, and then a device applying the eddy current flaw detection principle was developed to comply with a standard with a magnetic permeability of 1.02 or less. , Mainly used for magnetic permeability inspection of non-magnetic steel materials.

In 1991, it was possible to measure the magnetic permeability of small parts and welded materials of various shapes from a minute value of magnetic permeability of 1.002, and it was a portable device with sufficient functions as an inspection device for standard products with magnetic permeability of 1.02 or less. A type of device is disclosed by the present inventor (Patent Document 1, Non-Patent Document 1).
This device (hereinafter referred to as the current product) has a differential transformer configuration consisting of one exciting coil wound around one magnetic wire and two detection coils arranged differentially so as to sandwich the exciting coil. Difference between a transmitter circuit that transmits an AC signal that excites a probe-type detector and an exciting coil, and an output signal that detects the effects of magnetic permeability and conductivity of the sample under test by bringing one end of the detector into contact with the sample under test. It consists of a phase detection circuit that analyzes the phase of a dynamic signal processing circuit and its output signal, extracts only the output signal based on the magnetic permeability of the sample to be measured, and converts it into DC, and a reference signal generation circuit. The reference signal generation circuit includes a single exciting AC signal that excites the exciting coil of the detector, and a phase circuit that adjusts the phase of the AC signal and supplies the reference signal to the phase detection circuit. The output voltage E from the differential detection coil is composed of two components, an output voltage Ec due to the influence of the eddy current of the non-magnetic sample and a voltage Em due to the influence of the magnetic component of the sample. Paying attention to the difference in phase between the two, the reference voltage of the phase detection circuit is applied so as to be perpendicular to the voltage Ec due to the influence of the eddy current, and the voltage component is removed, so that the magnetic permeability of the sample to be measured is proportional. Output signal can be output.
Among these, when the number of turns N1 of the exciting coil, the number of turns N2 of the detection coil, and the strength I (A) of the exciting current are set to 1000 or more, the detection force detects magnetic permeability 1.002. It is clear that it can be done. Moreover, it has been clarified that the magnetic permeability of a small sample having a diameter of 2 mm or less can be measured by reducing the distance between the two detection coils to about 3.5 mm.

The present invention aims to develop a pencil-type magnetic permeability measuring device capable of measuring the magnetic permeability of 1.002 and measuring the magnetic permeability of small parts of various shapes and welded materials from steel materials.

Japanese Unexamined Patent Publication No. 3-255380

Honzo et al .; Journal of the Japan Society of Applied Magnetics 15, 469-474 (1991)

In order to improve the portable type to the pencil type, the size of the detector should be reduced from 5 mm to 1 mm or less in diameter and 8 mm in length to 6 mm or less, that is, 30 to 100 times smaller, and magnetic for that purpose. The diameter of the core rod should be 1 mm to 0.2 mm or less, the board size of the electronic circuit should be 50 mm wide x 50 mm long, 10 mm wide or 40 mm long, and the power supply should be 100 V or two alkaline batteries. It is necessary to change from to a small battery with a diameter of 5 mm or less to realize a significant miniaturization of the device.

Patent Document 1 discloses that the detection sensitivity of the magnetic permeability measuring device is proportional to the number of turns N1 of the exciting coil, the number of turns N2 of the detection coil, and the strength I of the exciting current. Moreover, since it is expected to be proportional to the cross-sectional area of the detector, it is expected that the detection sensitivity will be significantly reduced just by reducing the size. Further, if the exciting current is reduced to reduce the power consumption, it is expected that the detection sensitivity will be significantly reduced. In other words, performance such as detection sensitivity and power consumption of magnetic permeability measuring device and miniaturization tend to be contradictory, and it is a difficult task to develop a small magnetic permeability measuring device with high detection sensitivity and excellent power consumption characteristics. is there.

In order to solve the above-mentioned contradictory problem, the inventors came up with the idea of increasing the exciting current from the current product of 1 kHz to 100 kHz to 10 MHz, and worked on miniaturization of the detector and reduction of current consumption. In order to suppress the eddy current associated with high frequency, we decided to use a Co-based amorphous wire with a diameter of 5 μm to 100 μm for the magnetic mandrel, and the reduction in the number of turns of the exciting coil and the detection coil due to the miniaturization of the detector is due to the coil pitch. By adopting a microcoil with an inner diameter of 10 μm to 120 μm of 10 μm or less, the number of exciting coil turns N1, the number of detected coil turns N2, the exciting current strength I, the cross-sectional area S of the magnetic core rod, and the frequency f of the exciting current , The effect of sensitivity such as the length of the magnetic core rod, the effective magnetic permeability μ of the magnetic core rod, and the resistance ρ of the magnetic core rod was studied diligently.

As a result, the detection sensitivity is not only proportional to the number of excitation coil turns N1 (times), the number of detection coil turns N2 (times), and the exciting current strength I (mA), but also the effective magnetic permeability μ of the magnetic core rod and its diameter. It was found that it is proportional to d ^1.5, which is proportional to d (mm), and is almost proportional to f ^1.5, which is the frequency f (kHz) of the exciting current. That is, the detection sensitivity K is necessary to secure a K ≧ 3 × 10 ⁷ in order to detect that it is manifested by K = N1 × N2 × I × μ × d 1.5 × f 1.5, and permeability 1.002 It turned out that there is.

Assuming that the coil turns N1 and N2 of the detector are almost the same as those of the current product by utilizing the microcoil, if the diameter of the magnetic core rod is changed from 1 mm to 0.01 mm, the sensitivity will be significantly reduced. The decrease is due to the increase in the effective magnetic permeability of the magnetic core rod from 800 to 10,000 of the current product, and the increase in the exciting current frequency from 1 kHz to 1 MHz, which is 1,000 times stronger. It was confirmed that the detection sensitivity of magnetic permeability of 1.002 can be obtained even if the current product is reduced from 33 mA to 3 mA to 1/10 or less. Based on these new findings, it was found that a small magnetic permeability measuring device having high detection sensitivity and excellent power consumption characteristics can be invented.

The present invention enables a pencil-type magnetic permeability measuring device, which enables a significant reduction in size and power consumption as compared with the current magnetic permeability measuring device, and is a non-magnetic inspection that increases with the linear Shinkansen. It meets the needs.

It is a figure which shows the detection principle. It is a figure which shows the basic circuit. It is a figure which shows the phase detection function. It is a figure which shows the appearance of the pencil type ultra-compact magnetic permeability measuring apparatus of Example 1. FIG. It is a figure which shows the relationship between the magnetic permeability of the sample to be measured, and the output voltage. It is a figure which shows the relationship between the detection force of magnetic permeability 1.002, the diameter of a magnetic mandrel, and the excitation frequency. It is a figure which shows the measurement mode and sleep mode of Example 2.

<First Embodiment>
The magnetic permeability measuring device (hereinafter, referred to as a measuring device) of the first embodiment includes a detector, an electronic circuit, and a display.
The detector has a differential transformer configuration having a diameter of 1 mm or less, which includes one exciting coil wound around one magnetic wire and two detection coils arranged differentially so as to sandwich the exciting coil. It is a probe type detector, and has a function of detecting the influence of magnetic permeability and conductivity of the sample to be measured as an output signal by bringing one end of the detector into contact with the sample to be measured.
The diameter of the magnetic wire is 5 μm to 100 μm, the exciting coil and the detection coil consist of microcoils with a coil pitch of 10 μm or less and an inner diameter of 10 μm to 120 μm, the number of turns of which is 100 to 1000 times, and the distance between the two detection coils. Is 3.5 mm or less.

The electronic circuit includes a transmission circuit, a signal processing circuit, and a reference signal generation circuit.
The transmission circuit transmits an AC signal having a current strength of 10 mA or less at a frequency of 100 kHz to 10 MHz that excites the exciting coil.
The signal processing circuit is a differential amplifier circuit having a zero point correction function that adjusts the output signal to 0V when one end of the detector is not in contact with the sample to be measured, and the output of the corrected differential amplifier circuit. For the magnetic permeability of the sample to be measured after detection by a phase detection circuit and a phase detection circuit that has a phase angle adjustment function that can perform phase analysis of the signal and extract only the output signal based on the magnetic permeability of the sample to be measured and convert it to DC. It consists of an output circuit that outputs a proportional voltage.
The reference signal generation circuit includes a sine wave generation circuit that generates a sine wave that excites the exciting coil of the detector, and a phase circuit that generates a reference vector signal whose phase of the sine wave is adjusted.
The display displays a DC signal based on the magnetic permeability of the material to be measured.

Hereinafter, each configuration will be described with reference to FIGS. 1 to 3.
The configuration of the detector and the detection principle will be described with reference to the detection principle of FIG.
The detector 1 is composed of one exciting coil 12 wound around a magnetic wire 11 which is one magnetic core rod, and two detection coils 13 (13a) differentially arranged so as to sandwich the exciting coil 12. It is a probe type detector having a differential transformer configuration consisting of and 13b).

Next, the detection principle of the detector 1 is that an alternating current is passed through the exciting coil 12 to bring one end of the magnetic wire 11 into contact with the sample 20 to be measured, and the sample 20 is subjected to alternating magnetization and eddy current (shown in FIG. 1). ) Is generated to detect the influence of the magnetic permeability and conductivity of the sample 20 to be measured as an output signal .

The size of the probe type detector 1 is a small size having a diameter of 1 mm or less and a length of 6 mm or less. This enables a pencil-sized ultra-compact magnetic permeability measuring device.
The parts constituting the small-sized detector 1 are made of Co-based amorphous magnetic wire 11 and its diameter (d) is miniaturized to 5 μm to 100 μm, while its specific magnetic permeability (μ) is 5,000 to 50. Increase it to 000 and set the resistivity to 50 μΩcm to 150 μΩcm.

The exciting coil 12 is a microcoil having a diameter of 10 μm to 20 μm, and is arranged at the center of the magnetic wire 11 with a length of 1 mm to 3 mm. Next, the detection coil 13 is a microcoil having a diameter of 10 μm to 120 μm, and is arranged differentially on both sides of the exciting coil 12 with a length of 1 mm to 3 mm (13a and 13b).
The number of coil turns per unit length of the exciting coil 12 and the detection coil 13 can be increased to 50 times / mm to 500 times / mm by micronizing both coils. Further, the number of coil turns (N1) of the exciting coil 12 and the number of coil turns (N2) of the detection coil 13 are increased to 100 to 1000 times. Further, the distance between the two detection coils 12 is reduced to 3.5 mm or less to enable measurement of the magnetic permeability of a small sample having a diameter of 2 mm or less.

The electronic circuit will be described with reference to the basic circuit of FIG.
The electronic circuit includes a transmission circuit (not shown), a signal processing circuit 30, and a reference signal generation circuit 40, and includes a display 50 that displays an output result.
The transmission circuit transmits an AC signal that excites the exciting coil 12, that is, an AC signal whose frequency (f) is increased to 100 kHz to 10 MHz and whose current strength (I) is 2 mA to 10 mA.

The signal processing circuit 30 includes a differential amplifier circuit 31, a phase detection circuit 32, and an output circuit 33.
The differential amplifier circuit 31 detects the influence of the magnetic permeability and conductivity of the sample to be measured 20 as an output signal by contacting one end of the detector with the sample to be measured 20 , and at the same time, makes one end of the detector to be the sample to be measured. It has a zero point correction function that adjusts the output signal to be output to 0V when they are not in contact with each other.
The phase detection circuit 32 has a phase angle adjusting function at the same time as performing phase analysis of the output signal corrected by the differential amplification circuit 31 and extracting only the output signal based on the magnetic permeability of the sample to be measured and converting it into DC.
FIG. 3 shows the function of the phase detection circuit 32. In FIG. 3, I indicates the intensity of the exciting current. Hereinafter, E is the output voltage, Ec is the voltage generated by the eddy current of the non-magnetic sample, Em is the voltage generated by the magnetism of the magnetic sample, E is the reference signal, and φ is the reference signal. The phase angles of are shown respectively. The phase detection circuit outputs the projection component EmcosΦ of the output signal E to the reference signal Ey as a voltage, and the output voltage is proportional to the magnetic strength of the material, that is, the magnetic permeability.
The output circuit 33 outputs a voltage proportional to the magnetic permeability of the sample 2 to be measured after being detected by the phase detection circuit 32 and the detection circuit.

The reference signal generation circuit 40 is a sine wave generation circuit 41 that excites the excitation coil 11 of the detector 1 and a phase circuit 42 that generates a reference signal of the phase detection circuit.
The above-mentioned basic circuit and detection principle are as described in detail in Patent Document 1 (Japanese Patent Laid-Open No. 3-255380) and Non-Patent Document 1 previously disclosed by the present inventor.

The power supply circuit (not shown) supplies the exciting coil 12 of the detector 10 with electric power having a current strength of 10 mA or less and electric power necessary for operating the measurement circuit.

The power supply may be of any size, weight, output voltage and capacity as long as a pencil-type measuring device can be configured. As an example, one small lithium battery having a diameter of 4.7 mm, a length of 25 mm, a weight of 1 g, an output voltage of 3.8 V, and a capacity of 32 mAh is used.

The adjustment of the measuring device is that the output voltage difference from the two detection coils (12a, 12b) is 100 μV or less when the full scale is ± 1000 mV when the detector is not in contact with the sample to be measured, that is, 0. The symmetry of the two detection coils (12a, 12b) is ensured so that the error is 01% or less. This error can be removed by installing a zero point correction circuit. Next, when the detector 1 is in contact with the non-magnetic sample 2 to be measured, the phase angle of the reference vector signal of the phase detection circuit 3 is adjusted by the phase angle adjustment circuit so that the signal voltage after the phase detection becomes 0V. To do.

The detection sensitivity K is expressed by K = N1 × N2 × I × μ × d ^1.5 × f ^1.5 . As the K ≧ 3 × 10 ⁷ in order to detect the magnetic permeability 1.002, adjusted N1, N2, I, mu, d, and f in the above range. Further, in order to avoid affecting the size of the sample to be measured, the distance between the two detection coils (12a, 12b) is 3.5 mm or less.

The measurement is performed by bringing the detector 10 into contact with the micromagnetic sample 20 to be measured, and the output voltage has a linear relationship with the magnetic permeability. In addition, the output circuit can be used for analog output, digital output, and even display on a personal computer screen in real time. In the case of digital output, the measurement interval is 20 ms, that is, 50 Hz. The performance of the measuring device can measure a wide range of magnetic permeability from 1.00 to 2.00, and even a minute magnetic permeability of 1.002 can be detected.

<Second Embodiment>
In the second embodiment, in the digital output type of the first embodiment, the output interval time of the measurement data is divided into the measurement mode time and the sleep mode time, the measurement time is set to 1/10 or less of the measurement interval, and the signal voltage is digitally set. It is an output, and is a preferred embodiment in which the power consumption required for measurement is reduced to at least 1/10 or less.

In order to divide into the measurement mode time and the sleep mode time, a control circuit (not shown) that turns ON and OFF is attached to the electronic circuit, and a hold circuit (not shown) that holds the output after phase detection in synchronization with it is installed. It is provided, measured in the ON state, the signal voltage is held and output, and the same signal voltage is output even in the OFF state. As a result, the same signal voltage is output during the measurement interval of 50 Hz. Output.

<Third Embodiment>
In the third embodiment, the measuring devices of the first embodiment and the second embodiment are built in a pencil-shaped case. This will be described with reference to FIG.
A detector 61 is attached to the tip, an electronic circuit 65 and a battery 66 are built in, and a display 67, a power switch 62 of the measuring instrument, a zero point adjustment knob 63, and a phase angle adjustment knob 64 are attached to the exterior. The size of the tip portion is a spindle shape with a diameter of 0.5 mm to 1 mm and a length of 4 mm to 6 mm. The total length of the main body of the measuring device 6 is 10 cm to 16 cm, and the diameter is 8 mm to 14 mm.

[Example 1]
The first embodiment of the present invention is a combination of the first embodiment and the third embodiment, and as shown in FIG. 4, the detector 10, the electronic circuit, the power supply, and all of them are built in a pencil-shaped case. The magnetic coefficient measuring device 60. A detector 61 was attached to the tip of the measuring device 60, an electronic circuit 65 and a battery 66 were built in, and a display 67, a power switch 62 zero point adjustment knob 63, and a phase angle adjustment knob 64 were attached to the exterior part. The size of the tip is a spindle shape with a diameter of 1 mm and a length of 6 mm. The main body of the measuring device 60 has a total length of 14 cm and a diameter of 10 mm.

The detector 61 (1) is a differential transformer composed of one exciting coil 12 wound around one magnetic wire 11 and two detection coils (13a, 13b) arranged differentially so as to sandwich the exciting coil 12. It is a probe type of configuration.
First, the size of the detector 61 is 0.5 mm in diameter and 6 mm in length. This enables a pencil-sized ultra-compact magnetic permeability measuring device. First, the components of the detector 61 (1) have a magnetic wire 10 having a diameter of 10 μm, a relative magnetic permeability of 8,000, and a resistivity of 130 μΩcm. The exciting coil 11 is a microcoil having a diameter of 18 μm and a length of 2 mm, and is arranged at the center of the magnetic wire 10 having a diameter of 10 μm. The detection coil 12 is a microcoil having an inner diameter of 18 μm, a coil pitch of 5 μm, and a length of 2 mm, and is arranged differentially on both sides of the exciting coil 11. The number of coil turns per unit length is 200 times / mm. The number of coil turns of the exciting coil 11 (N1) and the detection coil 12 (N2) is 300. Further, the distance L between the two detection coils (12a and 12b) is reduced to 3.5 mm (FIG. 2) to enable measurement of the magnetic permeability of a small sample having a diameter of 2 mm or less.

The electronic circuit is an AC signal that excites the exciting coil 12, that is, a transmission circuit that transmits an AC signal whose frequency (f) is 1 MHz and whose current strength (I) is 3 mA, and one end of the detector 61 is a sample to be measured. in a state not contacted with the differential amplifier circuit 31 is detected as an output signal the influence of the magnetic permeability and conductivity of the sample at one end of the detector 61 to the measurement sample by contacting, adjust its output signal to 0V The zero point correction circuit, the phase detection circuit 32 (including the phase angle adjustment circuit) that performs phase analysis of the corrected output signal and extracts only the output signal based on the magnetic permeability of the sample to be measured and converts it to DC. An output circuit 32 that outputs a voltage proportional to the magnetic permeability of the sample to be detected after detection, and a reference signal generation circuit that generates a single excitation signal that excites the excitation coil of the detector and a reference vector signal of the phase detector. It consists of 4 and a power supply circuit that supplies power to the measuring device.

The power source is a small lithium battery having a diameter of 4.7 mm, a length of 25 mm, a weight of 1 g, an output voltage of 3.8 V, and a capacity of 32 mAh.

The adjustment of the measuring device is that the output voltage difference from the two detection coils (13a and 13b) is ± 1000 mV when the full scale is ± 1000 mV when the detector 61 (1) is not in contact with the sample 2 to be measured. The symmetry of the two detection coils (12a and 12b) is ensured so that the error is 100 μV or less, that is, 0.01% or less. This error can be removed by installing a zero point correction circuit. Next, when the detector is in contact with the non-magnetic sample to be measured, the phase angle of the reference signal of the phase detection circuit 32 is adjusted by the phase angle adjustment circuit so that the signal voltage after the phase detection becomes 0V.

The detection sensitivity K is expressed by K = N1 × N2 × I × μ × d ^1.5 × f ^1.5 . To detect magnetic permeability 1.002, like a K ≧ 3 × 10 ^7, adjusted N1, N2, I, mu, d, and f in the above range. Specifically, N1, N2 = 300 times, I = 3mA, μ = 8000, d = 10μm, f = 1MHz. At this time it becomes K = 8.5 × 10 ^7, the conditions for the sensitivity secure, which satisfies the K ≧ 3 × 10 ^7.
Further, in order to avoid affecting the size of the sample 2 to be measured, the distance between the two detection coils (13a and 13b) is 3.5 mm or less.

Regarding the results of measurement using this measuring device 60, FIG. 5 shows the relationship between the magnetic permeability of the sample to be measured and the output voltage, and FIG. 6 shows the diameter (d) of the magnetic core rod and the excitation frequency (which affect the detection sensitivity). The influence of f) is shown. The measurement is performed by bringing the detector 61 into contact with the sample 20 to be measured having a diameter of 2 mm. The output circuit is digitally output and displayed on the personal computer screen in real time. In the case of the digital output, the measurement interval is 20 ms, that is, 50 Hz.

First, from FIG. 5, it is obtained that there is a linear relationship with the output voltage when the magnetic permeability (μ) of the sample 20 to be measured is changed. From this, the performance of the measuring device can measure a wide range of magnetic permeability from 1.000 to 2.000, and can also detect a minute magnetic permeability of 1.002.
Next, FIG. 6 shows the result of measuring the magnetic permeability of the sample 2 to be measured having a magnetic permeability of 1.005, and "measurable" means that the value of the magnetic permeability appearing on the display 67 of the measuring device 60 can be measured. The case where "measurement is impossible" means that the measurement error is about the same as 1.005. 6, when satisfying K ≧ 3 × 10 ⁷ show that measuring device 6 is capable to accurately measure the permeability of the sample to be measured.

[Example 2]
In Example 2, based on Example 1, as shown in FIG. 7, the measurement interval time of 20 msec of the measurement data is divided into a measurement mode time of 0.2 msec and a sleep mode time of 19.8 msec for measurement. The time is set to 1/100 of the measurement interval, and the power consumption required for the measurement is reduced to about 1/100. For that purpose, a control circuit that turns on and off the electronic circuit is attached, and a hold circuit that holds the output after phase detection in synchronization with it is provided, and the measurement is performed in the ON state, the signal voltage is held and output, and then turned off. Even in the state, the same signal voltage is output. As a result, the same signal voltage is output during the measurement interval of 50 Hz.

The present invention has realized a pencil-type magnetic permeability measuring device, which enables a significant reduction in size and power consumption as compared with the current product magnetic permeability measuring device. Taking the opportunity of the Linear Shinkansen, non-magnetic steel is used for the steel frames and equipment of superconducting magnets, structural members of the vehicle body, and structures around rails, and rolling from the stage of refining non-magnetic steel with a reliable guarantee of non-magnetism. It meets the increasing non-magnetic guarantee needs at each stage from precision, secondary processing, parts processing and assembled structures.

10: Detector 11: Magnetic core rod (magnetic wire), 12: Excitation coil, 13a: Detection coil: 13b: Detection coil, 14: Detector tip 20: Sample to be measured 30: Signal processing circuit 31: Differential amplification Circuit (with zero point adjuster), 32: Phase detection circuit (with phase angle adjuster), 33: Output circuit (digital conversion, etc.)
40: Reference signal generation circuit 41: Sine wave generation circuit, 42: Phase circuit 50: Display 60: Ultra-compact magnetic permeability measuring device (measuring device)
61: Detector, 62: Power switch, 63: Zero point correction knob, 64: Phase angle correction knob,
65: Electronic circuit (built-in), 66: Battery (built-in), 67: Display

Claims (3)

The detector has a differential transformer configuration having a diameter of 1 mm or less, which includes one exciting coil wound around one magnetic wire and two detection coils arranged differentially so as to sandwich the exciting coil. It is a probe type detector and has a function of detecting the influence of magnetic permeability and conductivity of the material to be measured as an electric signal by bringing one end of the detector into contact with the sample to be measured.
The diameter of the magnetic wire is 5 μm to 100 μm.
The exciting coil and the detection coil are composed of microcoils having an inner diameter of 10 μm to 120 μm, and the number of turns thereof is 100 to 1000 times.
The distance between the two detection coils is 3.5 mm or less.
The electronic circuit comprises a transmission circuit, a signal processing circuit and a reference signal generation circuit.
The transmission circuit transmits an AC signal having a current strength of 10 mA or less at a frequency of 100 kHz to 10 MHz that excites the exciting coil.
The signal processing circuit includes a differential amplification circuit having a zero point correction function for adjusting the output signal to 0V when the detector is not in contact with the sample to be measured, and the corrected differential amplification circuit. A phase detection circuit having a phase angle adjustment function capable of phase-analyzing the output signal of the above to extract only an electric signal based on the magnetic permeability of the sample to be measured and converting it to DC, and the measurement to be performed after detection by the phase detection circuit. It consists of an output circuit that outputs a voltage proportional to the magnetic permeability of the sample.
The reference generation signal circuit includes a sine wave generation circuit that generates a sine wave that excites the excitation coil of the detector, and a phase circuit that generates a reference vector signal whose phase of the sine wave is adjusted.
The display is an ultra-compact magnetic permeability measuring device characterized by displaying a DC signal based on the magnetic permeability of the material to be measured. In claim 1,
An ultra-compact magnetic permeability measuring device characterized in that the measurement interval time of measurement data is divided into a measurement mode time and a sleep mode time, the measurement mode time is set to 1/10 or less of the measurement interval, and the signal voltage is digitally output. In claim 1 or 2,
An ultra-compact magnetic permeability measuring device characterized in that the size of the detector is 1 mm or less in diameter and 6 mm or less in length, the size of the electronic circuit is 10 mm or less in width, and the shape of the measuring device is a pencil type.

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