JPH0372946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for non-destructively measuring the mechanical properties of a ferromagnetic material by measuring the magnetic properties of the mechanical properties.

In the present invention, "mechanical properties" refer to hardness, strength, etc. of ferromagnetic materials such as steel materials and nickel alloy materials,
It refers to four types of stress states: toughness and external loading or internal residual stress.

Therefore, the present invention is mainly utilized in the steel product related industry.

[Conventional technology]

Generally, it is well known that if the mechanical properties of a ferromagnetic material such as steel or nickel alloy change, the magnetization properties of the ferromagnetic material - coercive force, magnetic permeability, and remanence - also change. Various methods have been proposed for a long time to utilize this phenomenon to non-destructively measure changes in the mechanical properties of ferromagnetic materials by measuring changes in their magnetization properties.

For example, a method that has been in practical use for a long time is the relationship between coercive force and mechanical properties (hardness) by quasi-static magnetization of ferromagnetic materials (steel materials), as shown in Japanese Patent Publication No. 41-2435. There are some that take advantage of correspondence.

In addition, as stated in "Basic Magnetic Engineering: Gakkensha Co., Ltd.: Published in 1975," there is also a method that utilizes the correspondence between average magnetic permeability and mechanical properties by alternating magnetization, as represented by the eddy current method. There is.

The device used for the former requires a demagnetizing device, so it must be large, and the shape of the electromagnet used for magnetization and demagnetization must be changed to match the shape of the object to be measured. Moreover, the magnetization and demagnetization operations are extremely complicated.

Although the device used for the latter is smaller than the former, the impedance of the excitation (primary) coil corresponds to the "slope" of the well-known hysteresis loop (see Figure 3 below). Or, since the voltage of the detection (secondary) coil is detected and the difference with the comparison sample is measured by the bridge method, the measured value is easily affected by fluctuations in the strength of the magnetic field and the strength of magnetization, and the measured value tends to vary depending on the shape of the detection end, the contact nature, and the shape of the object to be measured.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems found in devices that utilize the correspondence between average permeability and mechanical properties due to alternating magnetization, typified by the conventional eddy current method, and
To provide a measuring device in which measured values are not affected by fluctuations in magnetic field strength and magnetization strength, and in which fluctuations in measured values due to the shape and contact of a detection end and the shape of an object to be measured are as small as possible. The main purpose is to

Furthermore, another object of the present invention is to provide a measuring device that can use a detection end with a relatively simple structure.

Furthermore, another object of the present invention is to provide a small and lightweight portable measuring device.

[Means for Solving the Problems] The present inventor took the following measures to solve the above problems.

That is, FIG. 1 is a block explanatory diagram (partially shown as a circuit diagram and a model diagram) showing the configuration of the measuring device according to the present invention. The detection end 2 is composed of an excitation coil 21, a magnetic core 22, and a detection coil 23, which are excited by the alternating current output from the oscillator 1, and a voltage proportional to the magnetization speed of the object to be measured is induced in the detection coil 23. an integrator 3 that converts the wave into a voltage wave proportional to the magnetization strength; a resistor 4 that converts the excitation current proportional to the change in the magnetic field of the object to be measured generated in the excitation coil 21 into a voltage wave; and an output of the integrator 3. A first comparator 5 that converts a voltage wave into a square wave, a second comparator 6 that converts the voltage wave output from the resistor 4 into a square wave, and a comparison that adjusts the phase of the square wave output from the second comparator 6. The voltage variable device 7 converts a positive/negative pulse train into a positive pulse train proportional to the phase difference between the two waveforms obtained by adding the square wave output from the first comparator 5 and the square wave output from the second comparator 6 in reverse phase. A negative pulse inverter 8 that aligns the pulse height values of the positive pulse train output from the negative pulse inverter 8, a third comparator 9 that smooths the pulse voltage output from the third comparator 9, and generates a voltage proportional to the pulse width or A ferromagnetic material comprising a smoothing circuit 10 that outputs a current, and a display 11 that displays the smoothed voltage or current output from the smoothing circuit 10, and that displays a delay in magnetization of the object to be measured with respect to changes in the magnetic field on the display 11. (hereinafter referred to as the present specified invention).

Furthermore, the present inventor also took the following measures to solve the above-mentioned problems. That is, FIG. 2 is a block explanatory diagram (partially shown as a circuit diagram and a model diagram) showing the configuration of the measuring device according to the present invention. a detection end 2 composed of an excitation coil 21 excited by the alternating current output from the oscillator 1, a magnetic core 22, and a detection coil 23; an excitation coil excited by the alternating current output from the alternating current oscillator 1; 21', a magnetic core 22', and a detection coil 23'. a first integrator 3 for converting the voltage wave into a voltage wave proportional to the magnetization speed of the comparative sample induced in the detection coil 23' into a voltage wave proportional to the magnetization strength; A first comparator 5 converts the voltage wave output from the integrator 3 into a square wave, and a fourth comparator 5 converts the voltage wave output from the second integrator 3' into a square wave.
The comparator 6' generates a positive and negative pulse train proportional to the phase difference between the square waves output from the first comparator 5 and the square wave output from the fourth comparator 6'. A negative pulse inverter 8 to equalize the pulse peak values of the positive pulse train output from the negative pulse inverter 8, a third comparator 9 to smooth the pulse voltage output from the third comparator 9, and generate a voltage proportional to the pulse width. or a smoothing circuit 10 for displaying the smoothed voltage or current output from the smoothing circuit 10; This is a non-destructive measuring device for measuring the mechanical properties of ferromagnetic materials (hereinafter referred to as the dependent invention).

[Effect]

The effects of the present specific invention and the present dependent invention are as follows.

First, the measurement principle on which each device according to both inventions is based will be explained.

Figure 3 is a well-known magnetization hysteresis loop diagram, and if the hardness or strength of steel materials with the same composition changes, the "inclination" of the hysteresis loop will change between the magnetic field (H) and the magnetization strength (M). It is well known that there is a difference in width.

Although both inventions are based on alternating magnetization, they focus on the "width" of the hysteresis loop, and this "width"
The main point of this method is to capture this as a delay in magnetization, and in this respect it is completely different from the conventional eddy current method, which utilizes the correspondence between the average magnetic permeability and mechanical properties due to alternating magnetization.

That is, when a steel material is AC magnetized using a well-known probe equipped with a primary (excitation) coil and a secondary (detection coil), the magnetic field (H) is proportional to the primary current, so the current wave is plotted on the horizontal axis. , if we integrate the secondary electrode, we can obtain a wave proportional to the magnetization strength (M),
If a hysteresis loop is drawn with this on the vertical axis, the hysteresis loop shown in FIG. 3 can be obtained. The loops shown by solid lines in the figure are annealed ones, and the loops shown by dotted lines are hardened ones (for example, work hardened or quenched).

When the magnetic field (H) changes, the magnetization (M) changes with a slight delay, and the delay time (phase difference φ between the two waves) is 1/2 of the "width" of the hysteresis loop (quasi-static magnetization). (corresponding to the holding force Hc). To be more specific, if the primary (excitation) current i is given by the following equation (1), then i = i ₀ sin wt ...... (1) Let n ₁ be the number of turns per unit length of the primary coil. Then, the magnetic field H is given by the following equation (2), so H=n ₁ i ......(2) The output voltage v ₂ of the secondary coil is given by the following equation (3), but if the magnetic flux is If Φ, v ₂ = −N ₂ dΦ/dt = −N ₂ Sμn ₁ ioωcosωt ………(3) The “slope” of the hysteresis loop is related to μ,
Since the magnetization delay time is related to the phase difference φ, the output voltage of the secondary coil that is actually obtained is expressed by the following equation (4).

v′ ₂ = n ₁ N ₂ Sμ′ioω (cosωt−φ) ………(4) In equations (3) and (4), N ₂ is the total number of turns of the secondary coil, μ and μ′ are the transparent The magnetic coefficient, S, represents the cross-sectional area of the magnetic path.

Also, as shown in equation (4), the output voltage of the secondary coil v′ ₂
is shifted by about 90° from the current (magnetic field) wave, so
If we integrate and move back 90 degrees, the integrated voltage is given by the following equation (5).

v _M = −n ₁ N ₂ Sμ′i ₀ sin (ωt−φ) ………(5) Although the output voltage v _M of the secondary coil after integration is inverted in phase with respect to the exciting current wave, After reversal correction, the magnetic field H - proportional to the excitation current - and the magnetization M -
The relationship between v _M after integration and proportional to - is as shown in the waveform diagram in Figure 4, and the magnetization delay time is the relationship between the excitation current wave (proportional to the magnetic field change wave and in phase with this) and the secondary coil. It can be shown by the phase difference φ with the wave v _M (proportional to the magnetization change wave and in the same phase as this) which is an integral of the output voltage.

The measurement principle as described above is demonstrated by an experimental example as follows.

Experimental example 1 The sample to be measured is 40 mm in diameter and 75 mm in length.
Eight S55C cylindrical rods are induction hardened under different conditions for each rod to achieve a surface hardness of Bitkers 600~.
The hardening depth (the depth at which the hardness decreases to 500) was set in the range of 1.0 to 3.5 mm with a hardness of about 850.

As the detection end (detection probe), we used an E-type ferrite core (28 x 17 x 11 mm) wound 500 times on the center pole and 100 times on each side.The coil on the center pole was used for detection. Each coil on both sides was used for excitation.

In addition, as a comparison sample, an SCM3 block-like material with a Vickers hardness of approximately 600 (quenched at 850°C in water) was used. A detection end with the same structure as above was also used for the comparison sample.

Each of the detection ends described above is used so that the open part of the magnetic path is brought into contact with the cylindrical side surface of the sample to close the magnetic path.

The excitation current is approximately 70 mA of 900 Hz alternating current in the form of a sine wave, and both detection voltages from the measurement detection terminal and the comparison detection terminal are connected to each other through a well-known integrating circuit with equal circuit constants and a well-known amplifier. Signal output. The penetration depth of the magnetic flux when excited at 900 Hz is approximately 0.5 mm below the sample surface.

The detection signal output and comparison output signal are simultaneously output using a universal counter (manufactured by Takeda Riken).
TR5821 model) was input to two channels, and the difference in voltage zero level passage time between the two was measured in microseconds.

On the other hand, change the frequency of the excitation current to the above universal
It was measured with a counter (measured before and after the time difference measurement), and its reciprocal (period) T was determined.

The measured time difference Δt was divided by T/2 and multiplied by π to obtain the phase difference φ (radians).

The measurement operation as described above was performed for each round bar (for one or two locations), and the phase difference φ was determined for each round bar. The results are shown in FIG. Figure 5 shows the phase difference (pair/comparison sample) on the vertical axis, and the surface hardness of each round bar (cylindrical end surface) measured using a micro-Vickers hardness meter (manufactured by Akashi Seisakusho) on the horizontal axis. (Hv), and it can be confirmed from the figure that there is an extremely good correlation between the phase difference φ (magnetization delay time) and the surface hardness.

Therefore, by precisely measuring the voltage or current proportional to the phase difference φ, changes in the magnetization characteristics can be detected. That is, for example, if the value of the phase difference φ is measured in advance for materials with various hardnesses due to differences in the quenching conditions of the steel material to be measured, and the relationship between the hardness and the phase difference φ is determined, unknown It is possible to measure the hardness of steel materials of the same type.

Each device according to both inventions measures the "width" of the hysteresis loop as a delay in magnetization with respect to changes in the magnetic field, in other words, as a phase difference φ, based on the measurement principle described above. When the mechanical properties of the ferromagnetic material change due to the addition of various causes, the measured value of the voltage or current proportional to the phase difference φ of the ferromagnetic material before the addition of the various causes and after the addition of the various causes It is also possible to measure changes in mechanical properties in comparison with measured voltages or currents proportional to the phase difference φ of the ferromagnetic material in question.

When measuring the "width" of the hysteresis loop as the magnetization delay (phase difference φ), the actual measurement involves measuring the difference in the timing of the zero point passage of both voltage waves. , is not affected by variations in the strength of magnetization, and as is clear from equation (4) above, the magnetic permeability μ' and the cross-sectional area S of the magnetic path depend on the contactability of the sensing end, the shape of the object to be measured, etc. Therefore, the phase difference φ varies, but once the frequency to be used is determined, the phase difference φ is determined only by the material of the object to be measured, making it possible to perform accurate and stable measurements.

The explanation will be as follows based on FIGS. 1 and 2.

That is, the phase difference of the magnetization delay is determined by the first comparator 5.
A positive/negative pulse train proportional to the phase difference between the two waves obtained by adding a square wave outputting a square wave and a square wave outputting from the second comparator 6 in reverse phase, or a square wave outputting from the first comparator 5. and the square wave output from the fourth comparator 6' are processed as a positive/negative pulse train proportional to the phase difference of both waves, and the negative pulses are processed by the negative pulse inverter 8. By making all the pulses positive, fluctuations such as when the positive pulse width increases and the negative pulse width decreases due to the zero point movement of the circuit system are averaged out and canceled, and the pulse height is changed to the third comparator 9. Therefore, by holding it constant, the value proportional to the magnetization delay is stabilized as a voltage or current on the indicator 11.
is displayed. Incidentally, with such a configuration, the influence of fluctuations in the oscillation frequency is extremely reduced.

〔Example〕

Next, the functions and effects of each device according to both inventions will be explained by giving examples.

Embodiments of the Specific Invention In the apparatus shown in FIG. (200mA current, 3V maximum output voltage amplifier) is used, and at the detection end 2, a 200mA ferrite core (28 x 17 x 11 mm) is connected to the center pole of the E-type ferrite core.
The central pole coil was used as the excitation coil 21, and the coils on both sides were used as the detection coil 23.

As shown in FIG. 1, the current output from the AC oscillator 1 is applied to the excitation coil 21 of the detection end 2, and the excitation current is applied to a resistor (commercially available 10Ω) 4 connected in series to the excitation coil 21. Grounded through. The voltage on the coil side of this resistor 4 is input to the inverting input side of a second comparator (well-known comparator) 6, and the non-inverting input side of the second comparator 6 is connected to the comparison voltage between the output and ground. It is connected to a variable device (well-known potentiometer) 7. By changing the non-inverting input level from this comparison voltage variable device 7, the phase of the square wave output generated by the excitation current wave is adjusted.

On the other hand, the magnetic core 22 of the detection end 2 contacts the ferromagnetic material that is the object to be measured, indicated by the symbol A in the figure, to form a magnetic closed circuit, and the voltage induced in the detection coil 23 is well-known. integrator (100KΩ resistor,
The signal is applied to a first comparator (a well-known comparator) 5 through a 0.1 μF capacitor and a field effect transistor amplifier) 3, where it is converted into a square wave.

Since the phases of the two square waves correspond to the voltage wave proportional to the excitation magnetic field and the voltage wave proportional to magnetization, respectively, the phase difference between these voltage waves corresponds to the phase difference between the square waves. Therefore, the positive and negative pulse trains (pulses at point a in the figure: see a in FIG. 6) obtained by adding these square wave voltages in opposite phases are proportional to the phase difference between the two waveforms. Note that the first comparator 5 and the second
The polarity of the detection terminal 2 is set so that both waveforms from the comparator 6 have opposite phases.

Next, the positive and negative pulse trains at point a are applied to a negative pulse inverter 8 (a bipolar transistor in which a 10KΩ resistor is connected to the collector side and the emitter side, respectively: see the circuit diagram at 8 in the same figure), The negative pulse train is inverted to a positive pulse and all pulses are changed to a positive pulse train (pulse at point b in the figure: b in Figure 6).
).

Next, the positive pulse train at point b is applied to a third comparator (a well-known comparator) 9, and the positive pulses exceeding the comparison voltage are treated as positive pulse trains with uniform wave heights, and the pulse voltage output from the third comparator 9 is Smoothing circuit (a well-known circuit with a sufficient time constant consisting of a resistor and a capacitor: see circuit diagram 10 in the same figure) 1
0, smoothed (averaged) to a voltage proportional to the width and height of the pulse (voltage at point c in the figure: see c in Figure 6), and the output of the smoothing circuit 10 is displayed on the display ( It is displayed by a well-known analog ammeter) 11.

The display 11 displays the delay in magnetization of the object A to be measured relative to changes in the magnetic field.

Figure 7 shows how mild steel materials with different yield strengths (general structural steel SS41 (tensile strength 41 kgf/
A total of 10 types, 5 types with different rods (mm ² or more) and 5 types with different rods of structural steel SM50 (tensile strength 50Kgf/mm ² or more) strengthened with the addition of molybdenum, were made with a thickness of 16 mm. and 25 mm thick JIS No. 1 tensile test specimens and surface ground, total 20
This figure shows the results of measuring the yield strength of each mild steel material at an excitation current of 150 Hz, using Object A to be measured.

That is, in FIG. 7, the reading value of the indicator 11: μA (measured at 10 points on the surface of each of the 20 mild steel materials mentioned above, and the average value is shown) is plotted on the horizontal axis. , actually measured in advance on the vertical axis (Using an Amsler type tensile tester, a tensile test was performed on each of the 20 mild steel materials mentioned above to determine the yield strength.)
The yield strength of each mild steel material: Kgf/ ^mm2 . In the figure, the □ mark indicates the case where the plate thickness is 16 mm, and the ○ mark indicates the case where the plate thickness is 25 mm.

Embodiment of the present dependent invention In the apparatus shown in FIG. 2' had the same configuration as the detection end 2.

As shown in FIG.
A part of the current is applied to the excitation coil 21' of the comparison detection end 2'.

The magnetic core 22 of the detection end 2 contacts the ferromagnetic material that is the object to be measured, indicated by the symbol A in the figure, to form a magnetic closed circuit, and the voltage induced in the detection coil 23 is The signal is applied to a first comparator 5 (having the same structure as the first comparator used in the above example) through a comparator (having the same structure as the integrator used in the above example) 3, and converting it into a square wave. converted.

On the other hand, the magnetic core 22' of the comparison detection end 2' is made of a ferromagnetic material (a material similar to the ferromagnetic material of the object to be measured A), which is a comparison sample indicated by the symbol A' in the figure.
to form a magnetic closed circuit, and the detection coil 2
3' is applied to the fourth comparator 6' (same configuration as the first comparator) through the second integrator 3' (same configuration as the first integrator). converted into waves.

The phases of the above two square waves match the voltage wave proportional to the magnetization of the object to be measured A and the voltage wave proportional to the magnetization of the comparative sample A', respectively, so the phase difference between these voltage waves is the difference between the square waves. Matches the phase difference. Therefore, the positive and negative pulse trains obtained by adding these square wave voltages in opposite phases are proportional to the phase difference between the two waveforms, as in the above embodiment.

Next, the positive/negative pulse train at point a in the figure is applied to a negative pulse inverter 8 (having the same configuration as the negative pulse inverter used in the previous embodiment), and the subsequent steps are as in the case of the previous embodiment. In exactly the same way, display device (same as the analog ammeter used in the previous example) 1
1 displays the difference in magnetization delay between the object to be measured A and the comparison sample A'. FIG. 8 shows that a mild steel material (the same material as used in the above example) with different yield strengths is measured by this device as an object A, and a mild steel material (general structural steel SS41 is measured in a 50×50 This figure shows the results of measurement using a comparative sample A', which was cut out to 3 mm x 3 mm and surface-ground, and the frequency of the excitation current was 150 Hz.

That is, in FIG. 8, the horizontal axis is the reading value of the display 11: μA (measured at 10 points on the surface of each of the 20 mild steel materials, and the average value is shown). The yield strength of each mild steel material measured in advance in the above example is plotted on the vertical axis: Kgf/mm ² .
In the figure, the □ mark indicates the case where the plate thickness is 16 mm, and the ○ mark indicates the case where the plate thickness is 25 mm.

In manufacturing each of the devices shown in the above two embodiments, a well-known changeover switch is used to change the output of the second comparator 6 in the former device and the output of the fourth comparator 6' in the latter device. If it is possible to switch between
It is possible to manufacture a device that can be used for both devices (hereinafter referred to as the second dependent invention). A block explanatory diagram (partly shown as a circuit diagram and a model diagram) showing the configuration of the second dependent invention is shown as FIG. 9. Each number in Figure 9 indicates the same thing as in Figures 1 and 2, and 12
is a first-time switch.

〔effect〕

From FIG. 7 and FIG. 8, it is clear that by using the devices according to both inventions, mild steel material can be easily yielded with sufficient accuracy for practical use (accuracy comparable to or higher than the accuracy measured by the Amsler type tensile tester). It will be appreciated that strength can be measured. Of course, mechanical properties such as surface hardness of steel materials can be similarly easily measured with sufficient accuracy for practical use.

As is clear from the detailed explanation of the measurement principle on which the devices according to both inventions are based, since they measure the difference in the timing of passing the zero point, the measured values include fluctuations in the strength of the magnetic field and the strength of magnetization. It is hardly affected by.

In addition, as already mentioned, the magnetic permeability (μ') and the cross-sectional area of the magnetic path (S) vary depending on the contactability of the sensing end, the shape of the object to be measured, etc., but the phase difference (φ) Once the frequency is determined, it is determined only by the material of the object to be measured, so even if the shape of the sensing end is set to the required shape according to the shape of the object to be measured, it will be affected by the shape of the sensing end. Therefore, it is possible to use detection ends of various shapes. Moreover, as shown in the experimental example above, the structure of the detection end itself is
Since the structure can be relatively simple, it is easy to make the shape into a desired shape.

Furthermore, as is clear from FIGS. 1, 2, and 9, the configurations of the devices according to both inventions are relatively simple, so when designing them, miniaturization,
It is easy to reduce the weight, and a compact and portable measuring device can be manufactured.

Furthermore, during measurement, the measured values related to the mechanical properties of ferromagnetic materials can be directly read with a display meter, so it is possible to perform various non-destructive tests on materials and products, quality control, and mechanical parts in use. It is extremely versatile and allows for easy deterioration testing.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 9 are all block explanatory diagrams (partially shown as circuit diagrams and model diagrams) showing the configuration of the apparatus according to the present invention. In Figures 1, 2 and 9: 1 is an AC oscillator, 2 is a detection end, 21 is an excitation coil, 22 is a magnetic core, 23 is a detection coil, 3 is an integrator, 4 is a resistor, 5 is a 1 is a first comparator, 6 is a second comparator, 7 is a comparison voltage variable device, 8 is a negative pulse inverter, 9 is a third comparator, 10 is a smoothing circuit, 11 is a display device, 2'
is a detection end for comparison, 21' is an excitation coil, 22' is a magnetic core, 23' is a detection coil, 3' is a second integrator, 6'
is the fourth comparator. Further, 12 is a changeover switch. A is the test object, A' is the comparison sample,
All are ferromagnetic materials. In addition, the symbols a,
b and c match the symbols given to each waveform in FIG. 6, which will be described later. FIG. 3 is a hysteresis loop diagram of steel material. FIG. 4 is a waveform diagram showing the relationship between the excitation current wave and the magnetization detection voltage wave, in which φ indicates the phase difference (delay in magnetization). FIG. 5 is a graph showing the relationship between the phase difference value (radians) and surface hardness (Hv) in experimental examples. FIG. 6 is a waveform diagram showing the conversion process of each waveform in the apparatus according to the present invention. Figure 7 shows the reading value (μA) of the indicator (analog ammeter) 11 obtained with the device according to the present invention (the device shown in Figure 1) and the yield strength (Kgf) of the mild steel material to be measured. /mm ² ). Figure 8 shows the reading value (μA) of the indicator (analog voltmeter) 11 obtained with the device according to the present invention (the device shown in Figure 2) and the yield strength (Kgf) of the mild steel material to be measured. /mm ² ).

Claims (1)

[Claims] 1. An AC oscillator 1, an excitation coil 21 and a magnetic core 2 excited by the AC current output from the AC oscillator 1.
2 and a detection coil 23;
an integrator 3 that converts a voltage wave proportional to the magnetization speed of the object to be measured induced in the detection coil 23 into a voltage wave proportional to the magnetization strength; A resistor 4 that converts current into a voltage wave, a first comparator 5 that converts the voltage wave output from the integrator 3 into a square wave, and a second comparator 6 that converts the voltage wave output from the resistor 4 into a square wave. ,
A comparison voltage variable device 7 that adjusts the phase of the square wave output from the second comparator 6, and a dual type in which the square wave output from the first comparator 5 and the square wave output from the second comparator 6 are added in reverse phase. a negative pulse inverter 8 that converts positive and negative pulse trains proportional to the phase difference of the waves into a positive pulse train; a third comparator 9 that aligns the pulse peak values of the positive pulse trains output from the negative pulse inverter 8; A smoothing circuit 10 that smoothes the pulse voltage outputted by the smoothing circuit 10 into a voltage or current proportional to the pulse width, and an indicator 11 that displays the smoothed voltage or current outputted by the smoothing circuit 10.
A nondestructive measuring device for mechanical properties of a ferromagnetic material, characterized in that the display device 11 displays a delay in magnetization of the object to be measured relative to changes in the magnetic field. 2 AC oscillator 1, excitation coil 21 and magnetic core 2 excited by the AC current output from the AC oscillator 1
2 and a detection coil 23;
Comparative detection end 2' is composed of an excitation coil 21' excited by the alternating current output from the alternating current oscillator 1, a magnetic core 22', and a detection coil 23'; The first integrator 3 converts a voltage wave proportional to the magnetization speed of the object into a voltage wave proportional to the magnetization strength, which converts the voltage wave proportional to the magnetization speed of the comparison sample induced in the detection coil 23' into the magnetization strength. a second integrator 3' for converting into a proportional voltage wave;
The first comparator 5 converts the voltage wave output from the first integrator 3 into a square wave, the fourth comparator 6' converts the voltage wave output from the second integrator 3' into a square wave, and the first comparator A negative pulse inverter 8, which converts a positive and negative pulse train into a positive pulse train, which is proportional to the phase difference between the two waveforms obtained by adding the square wave outputted by the fourth comparator 5 and the square wave outputted from the fourth comparator 6' in reverse phase; A third comparator 9 that aligns the pulse peak values of the positive pulse train output from the pulse inverter 8, and a smoothing circuit 1 that smoothes the pulse voltage output from the third comparator 9 into a voltage or current proportional to the pulse width.
0, comprising a display 11 that displays the smoothed voltage or current output from the smoothing circuit 10, and displaying the difference in magnetization delay between the object to be measured and the comparison sample on the display 11. A non-destructive measuring device for the mechanical properties of ferromagnetic materials. 3 AC oscillator 1, excitation coil 21 and magnetic core 2 excited by the AC voltage output from AC oscillator 1
2 and a detection coil 23;
A first integrator 3 converts a voltage wave proportional to the magnetization speed of the object to be measured induced in the detection coil 23 into a voltage wave proportional to the magnetization strength, which is proportional to the change in the magnetic field of the object to be measured generated in the excitation coil 21. a resistor 4 that converts the excited current into a voltage wave, a first comparator 5 that converts the voltage wave output from the integrator 3 into a square wave, and a resistor 4.
It is composed of a second comparator 6 which converts the voltage wave outputted by the AC oscillator 1 into a square wave, an excitation coil 21' excited by the AC current outputted from the AC oscillator 1, a magnetic core 22', and a detection coil 23'. comparison detection end 2',
A second integrator 3' converts a voltage wave proportional to the magnetization speed of the comparison sample induced in the detection coil 23' into a voltage wave proportional to the magnetization strength, and the voltage wave output from the second integrator 3' is square. a changeover switch 1 that includes a fourth comparator 6' for converting the output into a waveform and switches between the output of the second comparator 6 and the output of the fourth comparator 6';
2, and further includes a square wave output from the first comparator 5 and a square wave output from the second comparator 5 switched by the changeover switch 12, or a square wave output from the fourth comparator 6'. Negative pulse inverter 8 that converts positive and negative pulse trains proportional to the phase difference between both square waves, which are obtained by adding one of the square waves in reverse phase to a positive pulse train, and a positive pulse train output from the negative pulse inverter 8. a third comparator 9 for aligning the pulse height values of
It comprises a smoothing circuit 10 that smoothes the pulse voltage output from the third comparator 9 into a voltage or current proportional to the pulse width, and a display 11 that displays the smoothed voltage or current output from the smoothing circuit 10. A ferromagnetic material characterized in that the indicator 11 displays either a delay in magnetization of the object to be measured relative to a change in magnetic field or a difference in delay in magnetization between the object to be measured and the comparative sample. A non-destructive measuring device for the mechanical properties of.