JPH032638A - Strain detector - Google Patents

Abstract

PURPOSE:To enhance the corrosion resistance and the moisture resistance of a magnetic layer and a magnetic shielding layer, to reduce time change and to improve reliability by providing the magnetic layer and the magnetic shielding layer on the surface of a passive member, and forming a protecting layer on the surfaces thereof. CONSTITUTION:A passive member 1 is formed of a high permeability soft magnetic material. A magnetic shielding layer 3 comprising nonmagnetic or diamagnetic highly conductive metal is formed on the surface of the member 1. A part of the layer 3 is removed, and a plurality of strip shaped magnetic layers 2 are provided. A protecting layer 4 is further formed on the surfaces of the layers 2 and 3. When external force is applied on the member 1, strain is generated, and permeability is changed. Detecting coils 5 detect said change as the change in magnetic impedance. The amount of the strain is detected from said output. The corrosion resistance and the moisture resistance of the layers 2 and 3 are improved by forming the protecting layer 4 on the surfaces of the layer 2 and the layer 3. Thus, time change can be reduced, and the reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a strain detector that detects strain in a passive member such as a rotating shaft.

[Conventional technology]

Generally, when the passive member to which an external force is applied is a magnetic material, the external force causes distortion in the passive member, and its magnetic permeability changes in accordance with this distortion. Therefore, by passing magnetic flux through the passive member, the degree of distortion can be reduced to i! It can be detected as a change in the 1iff rate. Therefore, in the past, a non-magnetic, high-conductivity magnetic shielding layer was formed on the surface of a passive member made of a soft magnetic material with high magnetic permeability, and a magnetic layer was formed in the non-formed part, and the magnetic permeability of the n-type layer changed. was used to detect distortion.

[Problems to be Solved by the Invention] However, in the conventional strain detector described above, since the magnetic layer and the magnetic shielding layer are exposed, changes over time due to corrosion etc. are large (and it is difficult to maintain the initial sensitivity). I can't do it,
It had low reliability.

This invention was made to solve the above-mentioned problems, and aims to obtain a strain detector that can improve corrosion resistance and moisture resistance and improve reliability.

[Means for Solving the Problems] A strain detector according to the present invention has a protective layer formed on the surfaces of a magnetic layer and a magnetic shielding layer.

[For production]

The surfaces of the magnetic layer and the magnetic shielding layer in this invention are covered with a protective layer to suppress corrosion and moisture absorption.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Second
Figures (a) to (C) show the manufacturing process of the strain detector according to this embodiment, in which the passive member 1 is made of a soft magnetic material with high magnetic permeability such as permalloy. After selectively printing the resist using a screen printing method, chemical etching is performed using an etching solution such as a cupric chloride solution, and parts other than the etching resist are selectively removed to form a plurality of strips tilted at ±45°. The magnetic layer 2 is formed to protrude. Next, using the etching resist as a plating resist, a magnetic shielding layer 3 made of a non-magnetic or diamagnetic highly conductive material such as Cu is formed on the selectively removed portions of the passive member 1 by high-speed plating.

In order to perform high-speed plating, it is necessary to increase the metal ion concentration of the plating solution, increase the temperature of the plating solution, and vigorously stir the plating solution. The plating conditions are, for example, copper sulfate l, 5 mol/l, sulfuric acid 0.6 m
Passive member l is immersed in a plating solution of OL/FFI, and high-speed electroplating is performed for 23 minutes at a temperature of 60°C and a current density of 50 A/dm while stirring the plating solution with high-speed rotation of the shaft.Next, as a plating resist. The etching resist is removed to expose the magnetic layer 2.

This state is shown in Figs. 2(a) and (b), and
As shown in FIG. 1C and FIG. 1, an organic material such as plastic, for example, epoxy ink is printed on the surfaces of the magnetic layer 2 and the magnetic shielding layer 3 by screen printing and hardened to form the protective layer 4. Next, a detection coil 5 is provided corresponding to the outer periphery of the magnetic layer 2.

In the above configuration, the magnetic shielding layer 3 is for preventing the magnetic flux generated from the detection coil 5 from penetrating into the passive member l by the magnetic skin effect, and the magnetic shielding layer 3 has a large σ and a large ω. Since it is large, the skin depth δ becomes small.

In the case of Cu, δ=25 at 50 Hz as shown in Figure 3.
The thickness of the magnetic shielding layer 3 is approximately 0n, and by setting the thickness of the magnetic shielding layer 3 to 250 μm or more, penetration of magnetic flux can be prevented.

When an external force is applied to the passive member 1, strain is generated in the magnetic layer 2 through the passive member 1, and its magnetic permeability changes.

The detection coil 5 detects this change in magnetic permeability as a change in magnetic impedance, and can detect the amount of strain from its output. In this case, ±45 to the axis of the passive component machining
The output of the detection coil 5 corresponding to the magnetic layer 2 formed at an angle of 145 degrees and the output of the detection coil 5 corresponding to the magnetic layer 2 formed at an angle of 145 degrees have opposite polarities, and their differential output is obtained. In addition, the protective layer 4 improves the corrosion resistance and moisture resistance of the magnetic layer 2 and the magnetic shielding layer 3 to reduce their aging deterioration, thereby ensuring high reliability. I can do it.

In the above embodiment, the protective layer 5 was formed by printing an organic material, but it may also be formed by plasma spraying of an organic material. In plasma spraying, thermal spray material powder is heated and accelerated by a plasma jet to coat the surface of the material. The film is formed by colliding with the metal, and the film can be formed at a rate of about 100 nm per minute, which is fast.

Next, a second embodiment will be described with reference to FIGS. 4(a) to 4(C). First, the passive member 1 is formed of a soft magnetic material with high magnetic permeability, and the magnetic shielding layer 3 made of a nonmagnetic or diamagnetic highly conductive metal, such as Cu, is formed on the surface of the passive member 1 by high-speed plating. Next, chemical etching is performed using an etching solution using 2W4 chloride solution.
A part of the magnetic shielding layer 3 is removed to expose the surface of the passive member 1, and a magnetic layer 2 having a plurality of strip shapes is formed. This state is shown in FIG. 4(a), [with It is formed on the surface of the shielding layer 3. Of course, a detection coil 5 is also provided.

The operation and effects of the above configuration are similar to those of the first embodiment. Although the ceramic protective layer 4 was formed by plasma spraying, T! It may be formed by one piece. In this case, ceramics are deposited on the surfaces of the magnetic layer 2 and magnetic shielding layer 3 at room temperature by an electrolytic method similar to plating, and the protective film 4 has excellent corrosion resistance.

Next, a third embodiment of the present invention is also shown in FIGS. 4(a) to 4(a).
This will be explained with reference to (C). In this embodiment, a plating resist is formed in a plurality of short shapes on the surface of the passive member 1, and a magnetic shielding layer 3 is formed on a portion other than the plating resist by high-speed plating.

Next, the plating resist is removed to expose the passive member 1, and the magnetic layer 2 is formed. This state is shown in Figures 4(a) and (b).
Next, as shown in FIG. 4C, a nonmagnetic metal material is deposited on the surfaces of the magnetic layer 2 and the magnetic shielding layer 3 by electroplating to form the protective layer 4.

For example, in the case of nickel, the thickness is about 2 pm, and in the case of gold, the thickness is about 1 ga. The operation and effects are similar to those of the above embodiment. Note that the protective layer 4 may be formed by electroless plating, electrodeposition, plasma spraying, printing, etc. instead of electroplating.

〔Effect of the invention〕

As described above, according to the present invention, the protective layer is formed on the surfaces of the magnetic layer and the magnetic shielding layer, and it is possible to improve the corrosion resistance and moisture resistance of the IF layer, the magnetic shielding layer, and the layer.

Therefore, changes over time are small, the initial sensitivity can be maintained, and reliability can be improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a strain detector according to a first embodiment of the present invention, FIGS. 2(a) to (C) are process explanatory diagrams of a strain detector according to a first embodiment of this invention, The figure is a skin depth characteristic diagram of Cu, and Figures 4 (a) to (C) are the second and third characteristics of this invention.
It is a process explanatory diagram of the distortion detector by the Example. 1... Passive member, 2... Magnetic layer, 3... Magnetic shielding layer, 4... Protective layer, 5... Detection coil. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa 1st 3rd Z 5: Detection coil frequency (KHz) Figure 2, Figure 47

Claims (1)

[Claims] A passive member made of a high magnetic permeability soft magnetic material and subjected to external force;
A magnetic shielding layer made of a non-magnetic or diamagnetic highly conductive metal and selectively formed on the surface of the passive member, a magnetic layer formed on the surface of the passive member where the magnetic shielding layer is not formed, and a magnetic layer. and a protective layer formed on the surface of the magnetic shielding layer, and a detection coil provided corresponding to the magnetic layer to detect changes in permeability of the magnetic layer in response to strain caused by the external force. Detector.