JPH01101680A - Manufacture of magnetic layer in distortion detector - Google Patents

Abstract

PURPOSE:To get rid of anisotropy, increase magnetostrictive constant, and to improve sensitivity of magnetic layers by annealing a thin band of a high magnetostrictive material in an alternate magnetic field and then fixedly bonding it in the circumference of a receiving shaft. CONSTITUTION:In preparing magnetic layers 6, 7, a thin band of a high magnetostrictive material such as amorphous magnetic materials is annealed in a high-frequency alternate magnetic field, and such annealed thin band is then fixedly bonded to the circumference of a receiving shaft 1 in a chevron form. using a bonding agent, etc. In other words, the magnetic layers 6, 7 are finely crystallized in the alternate magnetic field, as a result, its coercive force Hc is decreased, its magnetic domain and the direction of magnetized vector being disordered. This allows the magnetic layers to be without anisotropy and their magnetostrictive constants to be increased under a low magnetic field, whereby their sensitivity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic layer in a strain detector.

[Prior Art] FIG. 2 shows the detection principle of a conventional strain detector. When a torque T is applied to the passive shaft 1, a deflection occurs in the ±45° direction with respect to the central axis 2. That is, the tensile stress σ at an angle of +45°
occurs, and a compressive stress -σ occurs at an angle of -45°. Therefore, a magnetic layer made of a highly magnetostrictive material is fixed to the outer circumference of the passive shaft 1, and when torque is applied, the magnetic permeability of the magnetic layer increases due to tensile stress, and decreases due to compressive stress, resulting in this magnetostrictive effect. Torque and strain can be detected by

When manufacturing the magnetic layer, residual thermal stresses such as dislocations, lattice defects, and lattice distortions generated during manufacturing are removed from, for example, a ribbon of amorphous magnetic alloy, and
In order to impart anisotropy and improve magnetic properties (increase magnetic permeability μ and decrease coercive force Hc), annealing in a direct current magnetic field was carried out (Japanese Patent Laid-Open No. 59-6173).
Publication No. 2).

[Problem that the invention seeks to solve]

However, when annealing is carried out in a DC magnetic field as described above, the B-H curve becomes erect as the magnetic flux density B increases in a range where the magnetic field H is small, as shown in FIG. Figure 4 shows the annealing temperature dependence of the B-H curve, where the annealing temperature is 150°C in (a) and 200°C in (b).
C) is 250°C1(d) is 300"C1(e) is 3
50'C. As the annealing temperature increases, the B-H curve gradually becomes erect and does not change much in response to changes in stress. Therefore, when the B-H curve stands, the sensitivity as a strain detector decreases.

In addition, FIG. 5 shows a rectangular magnetic layer 3 around the passive shaft 1.
The arrow A indicates the axis of easy magnetization, that is, the direction of anisotropy, and the opening indicates the axis of stress action. When the direction of anisotropy A and the axis of stress action coincide, the B-H curve This is not preferable since the two parts are in an upright position, so the positional relationship is made such that they are perpendicular to each other, but there is a problem in that it takes a lot of manufacturing time to obtain such a positional relationship.

Note that even if annealing is performed without applying a magnetic field, the result will be the same as when a DC magnetic field is applied due to earth's magnetism.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a magnetic layer in a strain detector that has good sensitivity and is easy to manufacture.

[Means for solving problems]

A method for manufacturing a magnetic layer in a strain detector according to the present invention includes:
This method includes the step of annealing a ribbon of high magnetostrictive material in an alternating magnetic field.

[For production]

The magnetic layer in this invention is annealed in an alternating magnetic field, has no anisotropy, and has a large magnetostriction constant.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of the strain detector according to the present invention, where 4.5 is a bearing that rotatably supports the passive shaft 1, and 6.7 is a first and second bearing fixed on the outer peripheral surface of the passive shaft 1. Each magnetic layer 6.7 is formed of a thin ribbon of a highly magnetostrictive material such as an amorphous alloy, and the first magnetic layer 6 is at an angle of +4 with respect to the central axis 2.
In the 5 degree direction, the second magnetic layer 7 is at an angle of 145 degrees with respect to the central axis 2.
A plurality of elongated strips are formed in the degree direction. 8 is a cylindrical coil bobbin provided coaxially with the passive shaft 1 on the outer periphery of each magnetic layer 6.7, and on the outer periphery there are first and second coil bobbins corresponding to the first and second magnetic layers 6, 7. 2 detection coil 9.1
0 is wound, and each detection coil 9.10 is connected to a detection circuit (not shown).

In the above configuration, when stress is applied to the passive shaft l from the outside, when a tensile force is generated in one of the magnetic layers 6 and 7, a compressive force is generated in the other, resulting in distortion.

When this strain occurs, the magnetic permeability changes, and the magnetic permeability changes in opposite directions depending on whether the tensile force is applied or the compressive force is applied. The detection coils 9 and 10 detect changes in magnetic permeability as changes in magnetic impedance, and a detection circuit (not shown) receives the outputs of each detection coil 9 and 10 and outputs a detection voltage V according to the amount of distortion of the passive shaft 1. do.

When manufacturing the magnetic layer 6.7, a thin ribbon of a highly magnetostrictive material such as an amorphous magnetic material is annealed in a high-frequency alternating magnetic field of 10 to 100 KHz, and the annealed ribbon is wrapped around the passive shaft 1 with an adhesive. It is fixed in the chevron shape as shown in the figure.

The magnetic layer 5.6 described above becomes microcrystalline by annealing in an alternating magnetic field, the coercive force He decreases, the directions of the magnetic domains and their magnetization vectors become disordered, they do not have anisotropy, and magnetostriction under a low magnetic field increases. The constant becomes larger.

Therefore, the B-H curve becomes flat as shown in FIG. 3, and the sensitivity increases. This becomes more noticeable when a high frequency magnetic field is applied. In addition, due to the increase in sensitivity, the application efficiency of the alternating magnetic field also increases, and the applied current to the detection coils 9 and 10 becomes smaller, which reduces heat generation in the transistors, capacitors, abrasives, etc. provided in the detection coils 9 and 10 and the detection circuit. , power-on drift, changes over time, and changes over time are reduced, and reliability is improved.

Furthermore, since each magnetic layer 6.7 does not have anisotropy, there is no need to determine the fixing direction in relation to the axis of stress action, which facilitates manufacturing.

〔Effect of the invention〕

As described above, according to the present invention, the magnetic layer of the strain detector is
A thin strip of high magnetostrictive material is annealed in an alternating magnetic field and then fixed around the passive shaft, and the magnetic layer has no anisotropy.
The magnetostriction constant increases and the sensitivity increases. In addition, since it does not have anisotropy, there is no need to consider the directional relationship with the stress acting axis, making it easy to manufacture.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a strain detector according to the present invention, Fig. 2 is a diagram of the detection principle of the strain detector, Fig. 3 is a B-H curve of a magnetic layer according to the conventional method and the present invention, and Fig. 4 is an amorphous magnetic material. FIG. 5 is an orientation diagram of a conventional magnetic layer, and FIG. 6 is an orientation diagram of a magnetic layer according to the present invention. ■... Passive axis, 6.7... Magnetic layer, 9.10...
detection coil. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 4 (e) 350'C Figure 1 9, IQ: Detection coil Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] (1) A passive shaft that is subjected to stress; a magnetic layer made of a thin ribbon of high magnetostrictive material fixed on the outer periphery of the passive shaft; In a strain detector equipped with a detection coil that detects changes in magnetic permeability due to strain according to the 1. A method for manufacturing a magnetic layer in a strain detector, comprising a step of fixing it to the periphery.