JPH04116482A - Apparatus for measuring magnetic characteristic of long magnetic member - Google Patents

Abstract

PURPOSE:To correctly measure a magnetization curve of a long magnetic member by adjusting driving current of a compensation coil by means of a compensation coil control means so that a difference between center flux density and end flux density of a steel rod is eliminated. CONSTITUTION:Flux density in a center part and at ends lengthwise of a steel material 10 is read from a center flux detecting circuit 26 and an end flux detecting circuit 32 via AD converters 23, 34 into an arithmetic controller 30. The controller 30 automatically compensates a drop in flux density in an end of the steel rod 10 due to existence of leakage flux based on the detected values by means of magnetomotive force of first and second compensation coils 16, 18 by a compensation coil driving circuit 42 so that the flux density in the steel rod 10 is uniform along lengthwise direction. The controller 30 detects the flux density in the steel rod 10 while magnetomotive force due to a magnetization coil 14 is being varied via an excitation coil driving circuit 38 and also determines the intensity of magnetic field based on excitation current of the coil 14. Thus a magnetization curve of the steel rod 10 can be correctly measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for measuring the magnetization curve of a longitudinal magnetic member.

Conventional technology In order to measure the magnetization curve of a longitudinal magnetic member, a magnetic circuit is constructed by connecting a yoke to both ends of the longitudinal magnetic member with a magnetizing coil passing through it, and the magnetomotive force caused by the magnetizing coil is measured. The magnetization curve of the longitudinal magnetic member is measured by detecting the magnetic flux density within the longitudinal magnetic member while changing the magnetic flux density and determining the strength of the magnetic field using the excitation current of the magnetizing coil or the magnetic field measuring coil. A device has been proposed.

Problems to be Solved by the Invention However, in the conventional apparatus described above, since the dimensions of the longitudinal magnetic member to be measured vary within the tolerance, fluctuations in the gap between the longitudinal magnetic member and the yoke are unavoidable. do not have. Therefore, in a magnetic circuit composed of a longitudinal magnetic member and a yoke, the magnetic resistance changes in relation to the above-mentioned gap variation, and the leakage magnetic flux of the longitudinal magnetic member also changes. It was difficult to accurately measure the magnetization curve.

The present invention has been made against the background of the following two circumstances, and its purpose is to provide a magnetic property measuring device for a longitudinal magnetic member that can accurately measure the magnetization curve of the longitudinal magnetic member. It is about providing.

Means for Solving the Problems The gist of the present invention is to connect a yoke to both ends of a longitudinal magnetic member through which a magnetizing coil is passed through, thereby forming a magnetic circuit. An apparatus for measuring a magnetization curve of a longitudinal magnetic member by detecting magnetic flux density within the longitudinal magnetic member while changing a magnetomotive force by the magnetizing coil, the apparatus comprising: (a) both ends of the longitudinal magnetic member; (b) a central magnetic flux detection coil provided at the central portion of the longitudinal magnetic member for detecting the magnetic flux density within the central portion; (C)
(d) an end magnetic flux detection coil provided at both ends of the longitudinal magnetic member for detecting the magnetic flux density within each end; (d) a central magnetic flux density detected by the central magnetic flux detection coil; Compensation coil control means for adjusting the drive current of the compensation coil so that the difference with the end magnetic flux density detected by the end magnetic flux detection coil is eliminated;
It consists in including.

Operation and Effect of the Invention With this arrangement, the difference between the central magnetic flux density detected by the central magnetic flux detection coil and the end magnetic flux density detected by the end magnetic flux detection coils does not represent leakage magnetic flux. Therefore, the driving current of the compensation coil is adjusted by the compensation coil control means so as to eliminate the difference, thereby maintaining the same magnetic flux density over the entire longitudinal direction of the elongated magnetic member. Therefore, in this state, the magnetic flux density within the longitudinal magnetic member is detected while changing the magnetomotive force by the magnetizing coil, and the strength of the magnetic field is determined by the excitation current of the magnetizing coil or by the magnetic field measuring coil. Accordingly, the magnetization curve of the longitudinal magnetic member can be accurately measured.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, the member to be measured, that is, the bar @10 which is a longitudinal magnetic member, is a rolled bar bar cut into pieces, and has a shape of, for example, 200 mm x 5 to 20 mm. Characteristics are examined. This steel bar 10 is removably supported by the yoke 12 with its both ends fitted into holes or grooves formed at both ends of the U-shaped yoke 12. The yoke 12 is made of a magnetic material with high magnetic permeability and a large cross-sectional area, such as silicon steel, and is made of a magnetic material such as silicon steel.
Together with 0, it forms a closed magnetic circuit.

The steel bar 10 is passed through a cylindrical magnetizing coil 14 for exclusively applying magnetomotive force to the magnetic circuit described in item 1. Additionally, a first compensation coil 16 and a second compensation coil 18 are provided to compensate for the magnetic flux density at both ends of the steel bar 10.
are disposed at both ends of the steel bar 10 and on the outer peripheral side of the magnetizing coil 14. A central magnetic flux detection coil 20 is disposed on the inner peripheral side of the magnetizing coil 14 so as to penetrate through the longitudinal center of the steel bar 10 in order to detect the magnetic flux density within the steel bar 10. , the first end magnetic flux detection coil 22 and the second end magnetic flux detection coil 24,
They are disposed penetratingly at both ends of the steel bar 10, respectively.

The output signal of the central magnetic flux detection coil 20 is supplied to the arithmetic and control unit 30 via the central magnetic flux detection circuit 26 and the A/D converter 28. Further, the output signals of the first end magnetic flux detection coil 22 and the second end magnetic flux detection coil 24 are supplied to the arithmetic and control unit 30 via the end magnetic flux detection circuit 32 and the A/D converter 34.

The arithmetic and control unit 30 includes a well-known CPU, ROM,
It is a so-called microcomputer including RAM. CPU
processes the input signal according to a program stored in advance in the ROM while utilizing the memory function of the RAM, drives the magnetizing coil 14 via the D/A converter 36 and the exciting coil drive circuit 38, and also drives the D/A converter 36 and the exciting coil drive circuit 38. While driving the first compensation coil 16 and the second compensation coil 18 via the converter 40 and the compensation coil drive circuit 42, the measured magnetization curve or a value indicating the magnetization curve is displayed on the display 44. Therefore, the arithmetic and control device 30 functions as a magnetization curve measuring means and a compensation coil controlling means.

The operation of the magnetic property measuring device configured as described above will be described below with reference to the flowchart of FIG. 2 showing the magnetic property measurement routine and the flowchart of FIG. 3 showing the magnetic flux density compensation control routine.

After initial processing (not shown) is executed in connection with operation of a power switch (not shown), in step S1 of FIG. 2, it is determined whether a starting operation has been performed by a starting switch (not shown). This starting operation is performed with a new steel bar 10 attached to the yoke 12. Step S1
If it is determined that a starting operation has not been performed in step 82, the system is placed on standby, but if it is determined that a starting operation has been performed, steps 82 and subsequent steps are executed, and the magnetic flux density within the steel bar 10 is kept constant in the longitudinal direction. The magnetic flux density compensation control routine shown in FIG. 3 for maintaining the same condition is repeatedly executed, for example, in interrupt processing or parallel processing in cycles of several embryos.

In step SW1 of the routine shown in FIG. 3, the steel bar 10 is
At the same time, the magnetic flux density Bs in the end of the rod 'wA10 is read based on the signal output from the end magnetic flux detection circuit 32. Next, in step SW2, the magnetic flux density Bc in the central part of the steel bar 10 and the magnetic flux density B in the end part of the steel bar 10 are determined.
The magnetic flux density difference D (-Bc - Bs) with s is calculated. In the subsequent step SW3, it is determined whether the magnetic flux density difference is smaller than a predetermined criterion value α, and in step SW4, it is determined whether the magnetic flux density difference is larger than a predetermined criterion value β. will be judged. The above judgment reference value α and judgment reference value β indicate the target range of magnetic flux density compensation control to automatically eliminate the above magnetic flux density difference, and the judgment reference value α is set to a value slightly smaller than zero.
Further, the judgment reference value β is set to a value slightly larger than zero. If the judgment in step SW3 is affirmative, the magnetic flux density Bc in the center of the steel bar 10 is lower than the steel bar 10.
Since the magnetic flux density Bs within the edge of 0 is in a small state, the excitation current Is of the first compensation coil 16 and the second compensation coil 18 is increased by a predetermined increase value Δ in step SW5.
After Is is added, the excitation coil drive circuit 38 is driven in step SW8 so that the excitation current Is is obtained. Further, if the determination in step SW3 is negative and the determination in step SW4 is affirmative, the magnetic flux density Bs in the end portion of the bar @10 is larger than the magnetic flux density Bc in the center portion of the steel bar 10. , step SW
7, the first compensation coil 16 and the second compensation coil 1
After the predetermined increase value Δ1s is subtracted from the excitation current Is of No. 8, the excitation current Is is subtracted in step SW8.
The excitation coil drive circuit 38 is driven so that .

If the judgments in steps SW3 and SW4 are both negative, the magnetic flux density B in the center of the rod @10
c and the magnetic flux density Bs in the end of the steel bar 10 are equal, so the first compensation coil 16 and the second compensation coil 1
After the excitation current Is of No. 8 is set to be the same as the previous value, the excitation coil drive circuit 38 is driven in step SW8 so that the excitation current Is is obtained. With such a magnetic flux density compensation control routine, the decrease in magnetic flux density within the end portion of the steel bar 10 due to the presence of leakage magnetic flux is automatically compensated for by the magnetomotive force of the first compensation coil 16 and the second compensation coil 18, so that The magnetic flux density within 1o is A in Figure 4.
As shown by the line, the condition is uniform in the longitudinal direction.

Note that line B in FIG. 4 shows the magnetic flux density within the steel bar 10 in a non-compensated state, that is, in a non-excited state of the first compensation coil 16 and the second compensation coil 18. Each step in FIG. 2 is performed in a state where the magnetic flux density within the steel bar 10 is uniformly compensated as described above.

In the state where the magnetic flux density within the steel bar 10 is uniformly compensated as shown in 2 below, in step s2 of FIG. 2, the excitation current Tc of the magnetizing coil 14 is increased by a predetermined increase value ΔIc. After that, in step S3, the magnetic flux density Bc in the central part of the steel bar 10 is determined based on the signal from the central magnetic flux detection circuit 26 as the excitation current IC1, that is, the strength T1 of the magnetic field formed in the borided coil 14. In step S4, it is determined whether the excitation current Ic has reached a predetermined upper limit value ICmax. This upper limit value ICmax is the intensity I of the magnetic field at which 1° of the steel bar is sufficiently magnetically saturated. The amount you get is limited. The magnetic field strength T1 can be practically determined from a predetermined relational expression under the condition that the material and shape of the steel bar 10 are constant. Initially, the above step S4
Since the judgment is negative, 1, the above steps S2 to s4
When the point E is reached from point 0 in FIG. 5 after seven repeated executions, the determination in step S4 is affirmed. In this state, data from point 0 to point F in FIG. 5 is recorded.

In the subsequent step S5, it is determined whether or not the excitation current I(, has reached the predetermined upper limit c6 for the second time. Initially, the determination in step S5 is negative, so After step s6 (here, the excitation current of the magnetizing coil 4 is reduced by a predetermined reduction value -ΔIc), in step S7, the magnetic flux of the steel bar 10 is The magnetic flux density 13c in the central part is the excitation current IC5, that is, the borated coil 1.
The strength of the magnetic field formed within /1) is read in relation to T2 and then recorded in step S8 as the magnetic current 1 c
It is determined whether or not has reached a predetermined lower limit value Icm, ゎ. This lower limit value 1c0. is set to a value that provides a magnetic field strength H0in (negative value) that satisfies the magnetic saturation of 1° of the steel bar. Initially, the above Stella '7'
Since the judgment in S8 is negative, the above steps S6 to S
When the process reaches point F from point E in FIG. 5 after 8 repetitions, the judgment in step s8 is affirmed. In this state, data from point E to point F in FIG. 5 is stored.

Next, by repeating steps S2 to S4 again, the magnetic flux density Bc from point F to point E in FIG. It is read in relation to SASH. Then, if the determination in step s4 is affirmed, the exciting current Tc
Since this is the second time that has reached the upper limit value ■c, . . . aX, the determination in step s5 is affirmed. Therefore, in step s9, after the magnetization curve of the steel bar]O is displayed on the display 44 based on the data stored up to that point,
In preparation for the next measurement, the excitation current Ic is reset to zero in step SIO.

In this example, when measuring magnetic properties, the magnetic flux density compensation control routine shown in FIG. 3 is executed, so that the magnetic flux density Bs at both ends 41 (inside Since it is automatically compensated to be the same as the magnetic flux density Bc, in this state, while changing the magnetomotive force by the magnetizing coil 14, the magnetic flux density Bc in the steel bar 10,
The magnetic field strength and magnetic field strength are detected by magnetizing coil 1.
By making the determination based on the excitation current IC of No. 4, the magnetization curve of the steel bar 10 can be accurately measured.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be applied to other aspects.

For example, in the above embodiment, the steel bar 10 was used as the magnetic member to be measured, but the steel bar 10 was used as the magnetic member to be measured.

It may also be in the shape of a letter. In short, any magnetic member with an upper arm shape is sufficient.

Further, in the above embodiment, the first compensation coil 16 and the second compensation coil 18, and the first end magnetic flux detection coil 22 and the second end magnetic flux detection coil 24 were connected in series, respectively. The first end magnetic flux detection coil 22 and the second end magnetic flux detection coil 24 independently detect each magnetic flux density in the left and right ends of the rod mlO, and each magnetic flux density in the left and right ends is calculated as the magnetic flux in the center of the rod alO. Are the first compensation coil 16 and the second compensation coil 18 independently controlled so as to match the density Bc? ff1l, a magnetic flux density compensation control routine as shown in FIG. 3 may be provided.

Further, in the above-mentioned embodiment, the magnetization curve was automatically measured according to the measurement routine shown in FIG. The magnetization curve may be determined semi-automatically, such that a portion of the magnetization curve is measured by an operator.

In addition, in the embodiment shown in FIG. 2 described above, the excitation current of the magnetizing coil 14 was configured to be changed stepwise by AIc, but the AC component is too large to easily detect the magnetic flux density and the strength of the magnetic field. may be superimposed.

Further, in the above embodiment, the strength H of the magnetic field formed by the magnetizing coil 14 was determined based on the excitation current Ic of the magnetizing coil 14, but for example, a thin copper wire is An air-core H coil for magnetic field measurement wound around a thin plate is fixed parallel to the direction of magnetic flux and as close as possible to the surface of the bar @10, and the output signal of the air-core H coil is sent to a magnetic field detection circuit and an A/D converter. By supplying the magnetic field to the arithmetic and control unit 30 via the arithmetic and control unit 30, the strength H of the magnetic field may be directly detected in the arithmetic and control unit 30.

It should be noted that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the configuration of an embodiment of the present invention. FIG. 2 is a flowchart illustrating the magnetic property measurement operation of the first embodiment. Figure 3 shows the first
3 is a flowchart illustrating the magnetic flux density compensation control operation of the illustrated embodiment. The fourth time is a diagram explaining the magnetic flux density distribution in the steel bar of the embodiment shown in FIG. 1 in relation to the operation shown in FIG. 3. FIG. 5 is a diagram showing the magnetization curve measured by the operation of FIG. 2. 10: Rod m (longitudinal magnetic member) 12: Yoke 14: Magnetizing coil 16: First compensation coil 18: Second compensation coil 20: Central magnetic flux detection coil 22: First end magnetic flux detection coil 24: Second end Part magnetic flux detection coil

Claims (1)

[Claims] A magnetic circuit is constructed by connecting a yoke to both ends of a longitudinal magnetic member through which a magnetizing coil is passed, and while changing the magnetomotive force caused by the magnetizing coil, A device for measuring the magnetization curve of the longitudinal magnetic member by detecting magnetic flux density, the device comprising: a compensation coil provided at both ends of the longitudinal magnetic member; and a compensation coil provided at the center of the longitudinal magnetic member. a central magnetic flux detection coil for detecting the magnetic flux density within the central portion; and end magnetic flux detection coils provided at both ends of the longitudinal magnetic member for detecting the magnetic flux density within the respective ends. , a compensation coil that adjusts the drive current of the compensation coil so that the difference between the central magnetic flux density detected by the central magnetic flux detection coil and the end magnetic flux density detected by the end magnetic flux detection coils is eliminated; 1. An apparatus for measuring magnetic properties of a longitudinal magnetic member, comprising a control means.