JPS6150079A - Coersive force measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the measurement of coersive force of a ferromagnetic body simply and quickly with a small unit, by arranging a test piece and a sensor in a fine clearance between cores arranged in magnetizing the demagnetizing coils to rotate them relatively. CONSTITUTION:A test piece holder 42 is set in a fine clearance between cores 14 and DC excitation current is allowed to flow to a magnetizing coil 11 from a DC voltage varying circuit 21 to magnetically saturate a test piece 43 by magnetization. Then, a motor is made to run to turn the test piece holder 42 while excitation current from a DC voltage varying circuit 22 applied to a demagnetizing coil 12 is increased sequentially to generate a magnetic field in the direction opposite to that of a magnetic field of the magnetizing coil 11. Then, the difference in the electromotive forces between detection coil 52 and 53 is supplied to an X-Y recorder through the charging of a capacitor so that the residual magnetization of the test piece 43 is offset by the magnetic field of the demagnetization coil 12. Thus, the coersive force of the test piece 43 is calculated from the value of excitation current of the demagnetization coil 12 when the outputs of the detection coils 52 and 53 equal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coercive force measuring device for a ferromagnetic test piece, and particularly to a compact coercive force measuring device.

[Prior art] Iron and other metal materials exhibiting ferromagnetic properties are
In order to examine the magnetic properties of TAi as a magnetic material prior to factory shipment, it is common practice to extract a sample of the metal moon and measure its magnetic properties. As shown in Fig. 5, when the horizontal axis in the magnetic material represents the magnetic field strength 14, and the vertical axis represents the magnetic flux density B, the magnetic field strength is O→a-+b→ After changing like C, 0
It is shown as a magnetization curve that magnetically saturates at a point. In addition, when the magnetic field is strengthened in the opposite direction from the magnetic saturation point C,
The strength of magnetization follows the path c-+d-+e → f and becomes saturated again at point f. Then, when the magnetic field is strengthened again in the original direction, the magnetization changes to f-+q-1 → path C It changes in a circular pattern, creating a so-called hysteresis loop. At this time, the magnitude of O-d is called the residual v11 East density [3r, and Q
The large serration of -e is called coercive force Hc.

Generally, the measurement of magnetization characteristics such as magnetic flux density and coercive force of metal materials shipped from factories has conventionally been carried out by the membrane core method using a ring-shaped sample, or by using a self-recording magnetometer or NS permeability meter. was. Among these methods for measuring MA magnetization characteristics, especially the coercivity of a bar-shaped specimen using an NS permeability meter)
The measurement procedure is complicated and requires a long time even for an experienced person. In addition, in those that magnetize a test piece until it reaches magnetic saturation, an air-core coil is used to magnetize the test piece, which has the problem of requiring a large coercive force measuring device.

Therefore, in order to solve the above-mentioned problem, the present invention is a compact method for measuring the vitreous force of a strong vitreous body, which can be measured in a short time without the need of an expert. The object of the present invention is to provide a coercive force measuring device that can be used to measure coercive force.

[Means for Solving the Problems] ゛The present invention includes a magnetizing and demagnetizing coil, an iron core disposed in the coil having a minute gap, and a test specimen holder inserted into the minute gap. The present invention has a configuration in which a test piece and a sensor are arranged, and by rotating them relative to each other, the sensor outputs a change in the magnetic field.

Also, the rotation axis that provides relative rotation between the test piece holder and the sensor is relative to the magnetic field! I! This refers to a straight or parallel configuration.

[Operation] According to the configuration means, a current is passed through the magnetizing coil to generate a magnetic field in the coil, and a test piece placed in a minute gap is magnetized via an iron core disposed in the coil. and magnetically saturate it. Then, when the current in the magnetizing coil is cut off, a magnetic field opposite to the direction of the magnetic field is generated in the demagnetizing coil. The strength of this magnetic field is increased sequentially, and a sensor detects when there is no longer a difference in magnetic field strength between the magnetic field passing through the test piece and the magnetic field in the minute gap between the iron cores, and the test is performed at that point. The coercive force of the test piece can be stopped based on the magnetic field of the microgap as the point at which the residual magnetism of the test piece is lost.

[Example] Next, regarding the first example of the coercive force measuring device of the present invention,
This will be explained using figures.

FIG. 1 is a schematic diagram showing the main parts of the entire Yasuda force measuring device of the present invention. In the figure, 11 is a magnetizing coil wound to a predetermined diameter and length, and 12 is a demagnetizing coil wound to a predetermined diameter and length. These magnetizing coils 11 and demagnetizing coils 12 are formed by winding copper wire around a bobbin a predetermined number of times, and the winding density is uniform and dense, so they are the same as what is generally called a solenoid. be.

Ideally, the winding wire should be wound uniformly and densely, but since it is not always necessary to do so, it will be referred to as a general concept coil below. However, the magnetic fields formed by the two coils are such that the current is distributed substantially uniformly over the entire cross section of the coils, and an equal or substantially equal magnetic field is formed inside the coils. A magnetic shield tube (not shown) made of a ferromagnetic material is closely disposed around the outer periphery of the magnetizing coil 11, so that the magnetic field formed by the magnetizing coil 11 and the demagnetizing coil 12 is transmitted to the magnetizing coil 11. and is prevented from being formed outside the demagnetizing coil 12.

The magnetizing coil 11 and the demagnetizing coil 12 are connected to a DC voltage variable circuit 21 and a DC voltage variable circuit 22, respectively, and are connected to the DC voltage variable circuit 21 and the DC voltage variable circuit 22, respectively. A≧ Since the variable air pressure circuit 21 is for supplying an excitation current sufficient to magnetically saturate the test piece, it may be a constant voltage (constant current) power supply that supplies an output sufficient to magnetically saturate the test piece material. However, as in this embodiment, it is preferable to use a variable DC voltage circuit 21 to vary the output current continuously or in several steps to check the magnetic saturation of the test piece. Excite the demagnetizing coil 12! DC voltage variable circuit 2 that supplies l current
2 is to adjust the excitation current to cancel the residual magnetism of the test piece, and its output j changes continuously.

In addition, the DC voltage variable circuit 21 and the DC voltage variable
゛The circuit 22 supplies power to the magnetizing coil 11 and the '6AIa coil 12, respectively, but it uses them as a common power supply,
The direction of both excitation currents may be reversed by a changeover switch.

Similarly, the magnetizing coil 11 and the demagnetizing coil 12 can be used in common by switching their power supply circuits. That is, the magnetizing coil 11 and the demagnetizing coil 12 can be made into one coil, and the test piece can be magnetized or demagnetized depending on the direction of the excitation current. By sharing both coils, the device can be made smaller and cheaper! 8! Can be built. Further, the common use of the DC voltage variable circuit 21 and the DC voltage variable circuit 22 has similar characteristics.

The excitation current output from the variable DC voltage circuit 22 is taken out as a voltage proportional to the excitation current by a low resistance R, and becomes the X terminal input of the XY recorder 30.

Further, an iron core 14 is disposed within the magnetizing coil 11 and the reducing coil 12 to form a minute gap.

The minute gap has the minimum width that allows a fast-moving sensor, a test piece holder, etc. to be disposed therein, and the bottom of the gap is designed so that the magnetic field in the gap is uniformly distributed. In this embodiment, the diameter near the sensor and test strip holder is further made smaller than the diameter of the iron core in the coil so that the magnetic field increases the magnetic flux density near the sensor and test strip holder. Said iron core 1
A non-magnetic sensor mounting plate 51 is fixed to the end of the minute gap 4, and a sensor fixed to the sensor mounting plate 51 is mounted to the end of the iron core. In the illustrated embodiment, the sensor is formed by detection coils 52 and 53.

The test piece boulder 42 disposed in the minute gap is used to insert the test piece 43, and is fixed with screws or the like so that the test piece 43 does not move when the test piece holder 42 rotates.

The test piece holder 42 is fixed to one end of the connection 11+ 48, and a gear 45 is attached to the other end, and the contact vc shaft 48 between the test piece holder 42 and the gear 45 allows them to be freely connected. the support member 44
It is rotatably attached to. The gear 45 includes
It meshes with one wheel 46 of a rotating shaft 47 that is perpendicular to the direction of the magnetic field rotated by the electric motor, and in this embodiment, the gear 45 and the gear 46 are required to transmit rotation at right angles.
Although bevel gears are used, gears such as C-form gears or hypoid gears can also be used. These, the test piece holder 42 and the support member 44, the gears 45 and 46, the rotating shaft 47
, the connection shaft 48 etc. are made of non-magnetic material, and the detection coil 5
2 and 53 and the test piece 43 so that there is no disturbance of the U force lines.

The test piece 43 is mounted eccentrically with respect to the axis of the rotating test piece holder 42. A detection coil 52 for detecting a test piece magnetic field is disposed at a position opposite to the eccentrically mounted test piece 43. Further, a detection coil 53 for detecting the gap magnetic field is arranged at a position not affected by the magnetic field of the test piece 43. Therefore, the test piece 43 is attached to the test piece holder 42.
Even if it is rotated by , it has no effect on the detection coil 53 side.

The detection coil 52 for detecting the test piece magnetic field and the detection coil 53 for detecting the gap magnetic field are connected as in the detection signal processing circuit shown in FIG. 2.

That is, the rain detection coils 52 and 53 are connected in a differential state, and their output power is input to the differential amplifier 0'P. Therefore, when the test piece 43 is not inserted into the test piece holder 42, the outputs of the rain detection coils 52 and 53 are canceled by each other even if there is a change in the magnetic field in the gap, and the output of the differential amplifier OP is becomes zero, and the construction cost of the magnetic field created by the iron core is l:(((). Therefore, when the test piece 43 is inserted into the gap and a magnetic field is applied, the magnetization of the test piece 43 will change to the detection coil 52 for detecting the test piece magnetic field. , the output of the difference ωJ amplifier OP becomes high, which charges the capacitor C through the diode D, and the potential of the capacitor C changes through the resistor R2 to the Y terminal input of the At this time, the discharge resistance R1 is preferably set to a time constant determined by the rotation speed of the test piece holder 42 and the rate of change of the excitation current of the demagnetizing coil 12.

The coercive force measuring device of this embodiment configured as described above operates as follows, and can measure the coercive force of a test piece.

First, the test piece 43 is mounted on the test piece holder 42, fixed with screws, etc., and set at an arbitrary position facing the detection coil 52 for detecting the test piece material l field.

Next, a DC excitation current is applied to the magnetization coil 11 from the DC voltage variable circuit 21 to magnetize the test piece 43 and reduce magnetic saturation.

Thereafter, the output of the DC voltage variable circuit 21 is cut off. By cutting off the output of the DC voltage variable circuit 21, the test piece 43 maintains its magnetized state.

Next, the electric kettle is rotated, and the rotating shaft 47, gears 46 and 4 are rotated.
5. Rotate the test piece holder 42 via the connecting shaft 48.

Then, by sequentially increasing the excitation current from the DC voltage variable circuit 22 to the demagnetizing coil 12, the magnetizing coil 1
A magnetic field is generated in a direction opposite to the direction of the magnetic field in step 1. At this time, the excitation current is expressed as a voltage from both ends of the low resistance R
guided by the recorder.

At the same time, the outputs of the detection coil 52 for detecting the test piece magnetic field and the detection coil 53 for detecting the gap magnetic field are, for example,
When a change in magnetic flux occurs in the rain detection coils 52 and 53 due to a change in the excitation current of The output is made not to be the output of the differential amplifier OP.

However, the remaining rt of test piece 43! i magnetization is demagnetized coil 12
Before being wetted by the demagnetizing field, the output of the detection coil 52 becomes a pulse every time the test piece 43 passes near the detection coil 52. The polarity of the pulse is inverted and amplified by the differential amplifier OP, and the capacitor C is charged via the diode D. The charging voltage of capacitor C is
- Yll large input of Y recorder is led.

When the residual magnetization of the test piece 43 is canceled by the magnetic field of the demagnetizing coil 12, the outputs of the detection coils 52 and 53 become equal, and the output of the differential amplifier OP becomes zero. From the value of the excitation current of the demagnetizing coil 12 at this time, the coercive force of the test piece 43 can be calculated. Note that even if you do not use the X-Y recorder and measure the current value of the demagnetizing coil with a voltmeter when the charging voltage of capacitor C becomes zero, the coercive force of test piece 43 can be calculated in the same way. can do.

In this type of embodiment of the coercive force J111 constant device of the present invention shown in FIG. 1, the strength of the magnetic field near the test piece 43 can be increased by the iron core 14 compared to an air core. Furthermore, by making the support member 44 rotatable around its fulcrum (not shown), the test specimen boulder 42 can be tested while being rotated and the test piece boulder 42 is taken out from the minute gap in the iron core 14. Since the test piece 43 can be inserted and removed, the test piece 43 can be easily inserted and removed.

FIG. 3 shows a second embodiment of the coercive force measuring device of the present invention.

In particular, only the differences from the first embodiment of the present invention shown in FIG. 1 will be described.

In the first embodiment, the rotation of the motor was applied to the test piece holder 42 by the rotating shaft 47 in a direction perpendicular to the direction of the magnetic field in the minute gap in the iron core, but in this embodiment, the rotating shaft 47 penetrates through the iron core 14. 41 is inserted, and a test piece holder 42 is fixed to the end of the rotating shaft 41. Therefore, the rotation from the movement is directly transmitted to the rotating shaft 41, and the rotation 'I'Jl
The rotation of 41 is caused by the test piece holder 42 fixed to the rotating side 141.
is rotated directly without using gears or the like.

According to the second embodiment, the connecting shaft 4 required in the first embodiment
8. The support member 44 and gears 45 and 46 are no longer required, and the minute gap between the iron cores can be narrowed, and the magnetic resistance is reduced accordingly, making the magnetic field in the gap the same in the first and second embodiments. Therefore, the excitation current of the second embodiment can be reduced. Conversely, if the excitation v11 current is constant, the magnetic field of the second embodiment can be increased in strength. In addition, test piece 4
3 is a structure in which the test piece holder 42 can be taken out by moving the rotating shaft 41 to the left, because narrowing the minute gap between the iron cores 14 makes it difficult to insert and remove them, that is, at the right end of rotation @ h41. It is preferable to attach the test piece holder 42 by screwing or the like.

As a result, the second embodiment allows the entire coercive force measuring device to be made most compact.

Detection coil 5 as a sensor of the first embodiment and the second embodiment
2 and 53 have been described, but the detection coil can also be a Hall element (including a Hall IC).

The signal processing circuit 60 in this case may be configured as the detection signal processing circuit shown in FIG. Note that the signal processing circuit 6
0 is composed of a constant current power supply circuit and a detection signal processing circuit shown in FIG.

First, a constant current 1 is applied to the Hall elements 65 and 66 from a constant current source.
1 and ■2 are supplied. The outputs of the Hall element 65 for detecting the magnetic field of the test piece and the Hall probe 66 for detecting the magnetic field in the gap are outputs proportional to the strength of the magnetic field of each Hall element, and are outputted to the operational amplifiers OP1 and OR via amplifiers A1 and A2.
3 inputs. Subtraction circuit OP3 uses an operational amplifier as a cotton reduction circuit, and both operational amplifiers OPI and OR
3 outputs, operational amplifier OP1 and operational amplifier OP2
The output is the difference between the two. That is, the reduced rAl coil 1
As long as the excitation current of 2 is increased, the output becomes a positive output in a magnetic field of less than 1 force when the test piece 43 is placed on the floor. As the excitation current increases, when the test piece 43 loses residual magnetization in terms of coercive force, the outputs of both Hall elements 65 and 66 are canceled and the output of the subtraction circuit OP3 becomes zero. By monitoring the X-Y recorder, 1) the point at which the output of the subtraction circuit OP3 described in 1j becomes zero can be determined, and the coercive force of the test piece 43 can be calculated from the excitation current at that time.

Although an example has been described in which the circuit and Hall element used in the first embodiment are used as the signal processing circuit 6o, the circuit is not necessarily limited to that type of circuit, and a peak value detection circuit, a wave voltmeter, etc. , peak-t
o-peak), and (1 round of excitation current of the demagnetizing coil when the film width is at its minimum value).

Then, the coercive force of the test piece can be calculated in the same way as the former.

Particularly in this case, since it is not necessary to use an X-Y recorder with a high capacity, it becomes an inexpensive coercive force determining device.

Of course, i! Even if the circuit in Figure 4 has d, it is a reduction circuit.

By measuring the output of P3 with a DC voltmeter and measuring the excitation current (1, etc.) of the demagnetizing coil when the voltage becomes zero, the coercive force of the test piece can be calculated from the excitation current value.

Although the conditions within the microgap are not specifically mentioned in the first and second embodiments, in each of the above embodiments, the atmospheric temperature within the microgap is controlled by a temperature control device (not shown). By setting it to a specific temperature, you can measure the coercive force at that specific temperature. In particular, in this case, if the temperature is specified, what is the temperature of the Hall element, etc.? It becomes easy to design i0 compensation.

Conversely, when changing the temperature of the test piece 43 and measuring its temperature characteristics, it is desirable to measure the temperature characteristics with only the test piece 43 and the test piece holder 42 at upper limits.

[Effects of the Invention] As described above, the coercive force measuring method of the present invention includes arranging an In-coated coil and a demagnetizing coil concentrically, disposing an iron core with a predetermined minute gap between the two coils, and Since the test piece and sensor are placed in a minute gap, the work procedure is simple and even non-skilled workers can measure the ferromagnetic material in a short time by simply attaching the test piece to the specified position. The coercive force can be measured, and since it has an iron core in the magnetizing coil and demagnetizing coil, the strength of the magnetic field in a minute gap can be made stronger than in the case of an air-core coil. The coercive force measuring device can be made smaller than that using a coil.

Furthermore, in the coercive force measuring device of the present invention in which the test piece holder and the sensor are rotated relative to each other by a rotating shaft arranged perpendicular to the magnetic field generated by the iron core, the test piece is placed in the test piece holder. Easy to put on and take off.

Furthermore, in the coercive force measuring device of the present invention in which the test piece holder and the sensor are rotated relative to each other by a rotating shaft arranged in a direction parallel to the magnetic field generated by the iron core, the minute gap can be made the narrowest, and , the strength of the magnetic field can be increased, and the coercive force measuring device can be downsized.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a configuration diagram showing the overall main parts of a coercive force measuring device according to a first embodiment of the present invention, Fig. 2 is a signal processing circuit diagram for processing a detection signal of a detection coil, FIG. 3 is a configuration diagram showing the entire main part of the coercive force measuring device according to the second embodiment of the present invention, FIG. 4 is a detection signal processing circuit diagram for processing ball element detection (IM Knee+), and FIG. is a magnetization characteristic diagram of a magnetic material. In the figure, 11... Magnetizing coil, 12... Demagnetizing coil, 42... Test piece holder, 43... Test piece, 52. 53... Detection Coil, 65.66...Hall element. In the drawings, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (9)

[Claims] (1) A magnetizing coil and a demagnetizing coil are arranged concentrically, and an iron core having a predetermined minute gap in the axial direction of the coil is placed in both coils, and a test piece placed in the minute gap is inserted. a sensor for detecting a change in a magnetic field due to a test piece inserted into the test piece holder, the sensor being arranged facing the test piece holder at a predetermined distance from the test piece holder; A coercive force measuring device characterized by rotating a sensor relative to the other. (2) A magnetizing coil and a demagnetizing coil are arranged concentrically, and an iron core having a predetermined minute gap in the axial direction of the coil is placed in both coils, and a test piece placed in the minute gap is inserted. a test piece holder, and a sensor arranged oppositely to the test piece holder at a predetermined distance to detect a change in the magnetic field due to the test piece inserted into the test piece holder, A coercive force measuring device characterized in that the test piece holder and the sensor are relatively rotated by a rotating shaft disposed perpendicularly to the test piece holder. (3) A magnetizing coil and a demagnetizing coil are arranged concentrically, and an iron core having a predetermined minute gap in the axial direction of the coil is placed in both coils, and a test piece placed in the minute gap is inserted. a test piece holder, and a sensor arranged oppositely to the test piece holder at a predetermined distance to detect a change in the magnetic field due to the test piece inserted into the test piece holder, A coercive force measuring device characterized in that the test piece holder and the sensor are relatively rotated by a rotating shaft arranged parallel to the test piece holder. (4) The coercive force measuring device according to any one of claims 1 to 3, wherein the sensor is a detection coil. (5) The coercive force measuring device according to any one of claims 1 to 3, wherein the sensor is a Hall element. (6) The coercive force measuring device according to any one of claims 1 to 3, wherein the sensor has a detection coil connected in a differential state. (7) The coercive force measuring device according to any one of claims 1 to 3, wherein the sensor has a Hall element connected in a differential state. (8) The coercive force measuring device according to any one of claims 1 to 3, wherein the magnetizing coil and the demagnetizing coil are shared by one coil. (9) Coercive force measurement according to any one of claims 1 to 8, wherein the relative rotation between the test piece holder and the sensor is performed by rotating the test piece. Device.