JPH0634460A - Manufacture of magnetostriction detector for magnetostriction type torque sensor - Google Patents

Abstract

PURPOSE:To improve adhesion property between a transfer shaft and a magnetic alloy layer and to stabilize output characteristics for repeated stress by performing press plastic machining to a magnetic alloy layer which is formed on the outer- periphery surface of a torque transfer shaft and forming a plurality of recessed line grooves which are inclined at a specific angle for the shaft center. CONSTITUTION:A magnetic alloy layer 4 is formed on the outer-periphery surface of a torque transfer shaft 1 by flame spraying, it is subjected to heat treatment within a non-oxidation atmosphere, press plastic machining is performed to the surface of the alloy layer 4, and a plurality of recessed lines 2 and protruding lines 3 which are inclined at an angle of 45 deg. to for the shaft center are formed at a regular spacing. Nickel, Fe-Ni alloy, Co-Fe alloy, Al-Fe alloy, etc., can be applied for the magnetic alloy. Fe-Ni alloy is suitable since it has a large magnetostriction coefficient and is inexpensive. One of the recessed lines 2 and the protruding lines 3 is formed at +45 deg. in longer direction for detecting forward/backward rotation and the other is formed at -45 deg.. Since the recessed and protruding lines are formed by performing plastic machining to the shaft member outer-periphery magnetic alloy layer, adhesion property between the shaft member and the covering can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetostrictive detector used in a magnetostrictive torque sensor capable of non-contact torque detection.

[0002]

2. Description of the Related Art In a magnetostrictive detector for a magnetostrictive torque sensor, in order to be able to detect a change in magnetic permeability, a part of the surface of the detector axis is provided with magnetic anisotropy in the spiral direction.

As a method of imparting such magnetic anisotropy, a foil of a magnetostrictive material such as an amorphous alloy is spirally adhered to the surface of the shaft material (Japanese Patent Laid-Open No. 59-166827). Magnetostrictive alloy layer is sputtered on the surface of the substrate (JP-A-60-
No. 42628), wet plating method (JP-A-62-20).
No. 6421), or plasma spraying method (JP-A-6-6
No. 3-297545), followed by grooving in a spiral shape with an angle of 45 ° by cutting or chemical etching.

On the other hand, instead of adhering the magnetostrictive material, after performing shot-peening on the shaft surface while maintaining the state in which the torsion torque is applied to the shaft of the soft magnetic material such as alloy steel, the torsion torque is applied. Method of imparting magnetic anisotropy due to residual stress by releasing (Japanese Patent Application Laid-Open No. 2-280023, etc.)
There is. This method is characterized in that it can be manufactured relatively easily without the drawbacks such as the labor of providing the magnetic alloy coating in a spiral shape and the risk of cracking or peeling as in the former method.

[0005]

However, it has been pointed out that the torque sensor of the latter method has a low output sensitivity.

Therefore, an object of the present invention is to provide a method of manufacturing a magnetostrictive detector, which has good sensitivity and reproducibility of the detector, exhibits stable output characteristics against repeated stress, and has good productivity. There is.

[0007]

In order to achieve the above-mentioned object, a method of manufacturing a magnetostrictive detector for a torque sensor according to the present invention comprises forming a magnetic alloy layer on the outer peripheral surface of a torque transmission shaft by a thermal spraying method so as to prevent oxidation. It is characterized in that it is heat-treated in an atmosphere, the surface of the sprayed layer is subjected to pressure plastic working, and a plurality of concave and convex lines inclined at an angle of 45 ° with respect to the longitudinal direction of the shaft are formed at regular intervals. .

Before the thermal spraying in the above-mentioned manufacturing method, an angle of 45 ° to the longitudinal direction of the shaft is previously formed on the outer peripheral surface of the torque transmitting shaft.
A plurality of concave lines and convex lines inclined at ° are formed at regular intervals, a magnetic alloy layer is formed by thermal spraying as described above, and heat treatment is performed in a non-oxidizing atmosphere to make the surface of the thermal sprayed layer concave. Plastic working may be performed by pressing along the ridges and ridges.

In addition, it is made by any of the above methods,
The outer peripheral surface layer of the torque transmission shaft having a magnetic alloy layer in which a plurality of concave and convex lines inclined at an angle of 45 ° with respect to the longitudinal direction of the shaft is formed at regular intervals is removed by machining,
It is characterized in that the ridge of the torque transmission shaft is exposed on the surface while leaving the magnetic alloy layer in the groove.

The magnetostriction detecting body axis can be made of either non-magnetic material such as stainless steel or non-ferrous alloy or ferromagnetic material such as alloy steel. In the case of ferromagnetic material, it is necessary to form a thick magnetic alloy film. Therefore, a material that is non-magnetic is preferable. In this case, the coefficient of thermal expansion of the material is preferably close to that of the magnetic alloy.

The magnetic alloy is known nickel, 15 to 60.
% Fe-Ni alloy, 30-60% Co-Fe alloy,
An 8 to 18% Al-Fe alloy or the like can be applied. Considering that the magnetostriction coefficient is large and the cost is low, 50% Fe-
Ni-based alloys are suitable.

The concave line and the convex line form an angle of 45 with respect to the axis.
In the case of detecting forward / reverse rotation, one is formed at + 45 ° and the other is formed at −45 ° in the longitudinal direction of the shaft as in the conventional case.

If the thickness of the magnetic alloy portion is too thin, the stress detection characteristic becomes unstable. Therefore, when the shaft material is a non-magnetic material, it is 10
It is preferably formed to a thickness of at least μm. Further, when a ferromagnetic material is used as the shaft material, it is necessary to have a thickness such that the detected magnetic flux does not reach the shaft material. Therefore, for example, when the frequency for detecting the change in permeability is 50 KHz, the film thickness Is 30
Provide at least μm. From the viewpoint of workability, rolling is suitable for forming a plurality of inclined concave lines and convex lines provided on the shaft surface in advance.

The shape of the groove may be a V shape, a sine wave shape, a gear shape, a trapezoidal shape, a fan shape or the like.

When spraying the magnetic alloy onto the shaft member, it is desirable to remove oil on the surface in advance. Further, in order to enhance the adhesion of the thermal spray coating, it is desirable that the surface to be sprayed is blasted to have a matte surface.

In the thermal spraying, plasma is generated with a gas such as Ar, He, N ₂ , H _2, etc., and a powder for forming a coating film is put into the plasma, melted and sprayed on the surface of the shaft member to form a coating film. . A high temperature flame spraying method can also be applied.

The heat treatment strengthens the adhesion between the shaft material and the sprayed coating, promotes mutual diffusion between the sprayed particles, improves defects peculiar to the sprayed coating, normalizes the layered metal structure, and improves sensitivity and linearity. In vacuum,
It is processed in a non-oxidizing atmosphere such as hydrogen gas.

The treatment temperature is 900 to 1 for Fe-Ni alloy.
100 ° C., 800-850 ° C. for Co-Fe alloy, Al
The -Fe alloy is heated at about 400 ° C and gradually cooled.

In order to make the components uniform, before heating and slow cooling, the Co--Fe alloy is heated to about 1200 ° C. and rapidly cooled, and the Al--Fe alloy is heated to about 800 ° C. and rapidly cooled. May be processed.

The heat treatment may be carried out after plastic working on the sprayed film. Grinding is suitable for removing the surface layer of the shaft provided with the magnetic alloy coating and exposing the ridges of the shaft.

Incidentally, the surface of the main part of the shaft is covered and protected with resin or the like as in the prior art.

[0022]

The magnetostrictive detector manufactured according to the present invention is provided with a magnetic alloy layer having a high magnetic permeability on the surface of the shaft, so that a high output can be obtained.

Further, since the magnetic alloy layer is formed by the thermal spraying method, the compositional variation of the alloy layer is less than that by the plating method and the stable performance can be obtained.

The formation of the spiral uneven strip imparts shape anisotropy. In this case, since the magnetic alloy layer formed by thermal spraying on the surface of the shaft member is pressed by rolling and plastically deformed, the surface of the coating film due to thermal spray becomes dense and smooth,
The output reproducibility as a detector is improved. Further, the magnetic alloy layer has a large adhesion area with the shaft material, and improves durability.

In the case of a magnetic body having a magnetic alloy layer formed on both sides of an uneven line, the magnetic alloy layer acting to detect a change in magnetic permeability due to stress is a shaft member including the top of the line and the alloy layer in the vicinity. In the case where the ridge is exposed, it is the magnetic alloy layer in the recess defined by the ridge.

The heat treatment homogenizes the metal structure and improves the linearity of output, hysteresis, sensitivity, dynamic range, reproducibility, and durability as a torque sensor.

The concavo-convex stripes on the surface of the shaft member can be formed by rolling, and since the coating film is formed by the thermal spraying method, both can be manufactured efficiently and at low cost.

[0028]

Embodiments of the method of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a detector axis for explaining the manufacturing process of the invention sample. However, the unevenness and the film thickness are exaggerated.

First, a stainless steel rod (material JIS standard SUS304) having an outer diameter of 20 mm and a length of 100 mm was prepared.

Then, a columnar shaft material sample 1 as shown in (a1) and a concave line 2 and a convex line 3 are formed on the surface of the shaft 1 as shown in (a2) by rolling by knurling, and then the convex line is formed. 3 was ground to adjust the dimensions and processed into a shaft material sample 2.

The latter concave ridges 2 and convex ridges 3 have a substantially trapezoidal shape, the depth h of the concave ridges 2 is 0.5 mm, the width W ₃ of the convex ridges ₃ is 5 mm, and 10 ridges are formed on the outer circumference. did. The concave stripes 2 and the convex stripes 3 are formed such that one is inclined at an angle of + 45 ° and the other is inclined at an angle of −45 ° in the longitudinal direction of the shaft.

The outer peripheral surface of each shaft material was blasted by blasting corundum with compressed air to form a matte surface.

Next, a magnetic alloy layer 4 having an average thickness of 0.6 mm was provided on the main part of each sample by thermal spraying as shown in (b1) and (b2) of FIG. The thermal spraying is carried out at a reduced pressure of 200 Torr in an Ar gas atmosphere with an Ar-H ₂ plasma jet at 50
% Fe-Ni alloy powder was sprayed. This composition was obtained by evaluating the magnetostrictive characteristics of the detector formed by plasma spraying the Fe—Ni alloy layer 4 having various compositions in preliminary experiments, and the characteristics were good.

Next, each sample was placed in hydrogen gas at a temperature of 1000.
After being heated to 0 °, it was gradually cooled.

Then, each sample was rolled by using a rolling roll having an outer diameter corresponding to the concave line 2 and the convex line 3, and the surface of the magnetic alloy layer 4 in Sample 1 was gradually pressed, and in Sample 2 (b2). Pressing gradually corresponding to the uneven surface of, the cross-sectional shape as shown in FIG. 1 (c), in the longitudinal direction of the shaft 1, one at an angle +45 °,
On the other hand, plastic processing is applied to the uneven line inclined at an angle of -45 °,
Samples 1 and 2 for testing were used. FIG. 2 shows an enlarged schematic view of the cross section of the main part. Magnetically processed magnetic alloy layers 4 are formed on the surfaces of the concave lines 2 and the convex lines 3.

In addition, the width W ₂ of the so-called recess 2 in which the dimensions of the recess 2 and the protrusion 3 of the above sample are opposite to each other is set to 5 mm, and the manufacturing procedure depends on (a2), (b2) and (c). A sample was prepared, the outer peripheral surface was ground by a cylindrical grinder, the surface layer portion was removed, and the ridges 3 of the shaft member were exposed, as shown in FIG. An external view of the test sample 3 is shown in FIG. 3, and a sectional structure is schematically shown in FIG.

At this time, the magnetic alloy layer 4 is defined by the exposed ridges 3 of the shaft member.

On the other hand, as described in Japanese Patent Application Laid-Open No. 2-280023, sample 4 for comparison by a method of applying a residual stress by shot peening on the shaft surface while maintaining the state in which a torsional torque is applied to the shaft. It was created. This is made of nickel molybdenum steel, and one of them is angle +4 in the longitudinal direction of the shaft.
An uneven strip inclined at an angle of 5 ° on the other side and −45 ° on the other side is formed by cutting, the middle part s of this shaft material is chucked and fixed, and one end of the shaft is clockwise and the other end is counterclockwise. In the state where the twisting torque is applied, the uneven ridges are shot-peened, and then the twisting torque is removed.

Each magnetostrictive detector thus created is
The coil is fixed to a cantilever shaft, the coils 5 and 6 are arranged as shown in FIG. 5, and a torque detection electric circuit as shown in FIG. The relationship between the output voltage and the output voltage was measured. In FIG. 6, reference numeral 7 is a transistor, 8 is an input terminal, and 9 is an output terminal. The number of turns of the coils 5 and 6 was 40, the excitation condition was a frequency of 50 KHz, the current was 100 mA, and the waveform was a sine wave.

Here, the sensitivity is the value of the output voltage when a torque of 1 N · m is applied.

The linearity means the output voltage value when a predetermined torque is equally applied in the forward and reverse directions, plotted on a graph and connected by a straight line, and the deviation amount of the output voltage due to each torque application to this straight line. Is the value expressed as a percentage of the full-scale voltage.

The hysteresis is a value indicating the deviation amount of the output voltage value at the torque amount of 0 after the torque is continuously applied in the forward and reverse directions as a percentage with respect to the full scale voltage.

The measurement results are shown in Table 1, and it can be easily understood that the samples 1, 2 and 3 of the present invention are superior to the comparative sample 4 in each characteristic.

Further, when comparing the invention samples 1 and 2, the sample 1 has a smaller plastic working amount and a larger working strain of the magnetic alloy, so that the sensitivity is lower. Further, comparing Samples 2 and 3, Sample 2 detects the stress strain of the coating on the ridge surface, whereas Sample 3 is the magnetic alloy in the groove 2 defined by the ridge 3 of the shaft member. The stress strain of the layer 4 is detected. Also, sample 2
Although the surface of the magnetic alloy layer 4 of No. 3 is still plastically worked, the surface of the magnetic alloy layer 4 of Sample 3 is a polished surface, and therefore, there is less unevenness that relaxes stress, so that Sample 3 has higher sensitivity.

On the other hand, in manufacturing, the method of the present invention is almost the same as the method of preparing the comparative sample, and it can be seen that the method can be manufactured more efficiently than the method of forming the magnetic alloy coating and selectively removing it in a spiral shape.

[0047]

[Table 1]

[0048]

As described above, the method of manufacturing a magnetostriction detecting body according to the present invention is basically constructed by providing a magnetic alloy layer on a shaft member and forming uneven ridges by plastic working. The effect that the magnetic alloy layer is dense on the member, the adhesion between the shaft member and the coating is good, the durability is excellent, and the characteristics such as sensitivity and linearity are good, so that a magnetostrictive detector with good quality performance can be provided. Have.

Further, since the method for manufacturing the magnetostrictive detector according to the present invention is based on the rolling method and the thermal spraying method, the magnetostrictive detector can be manufactured efficiently and the productivity of the magnetostrictive detector can be remarkably enhanced. It has the effect that

[Brief description of drawings]

FIG. 1 is a sectional view of a shaft member illustrating a method for manufacturing a magnetostrictive detector according to the present invention.

FIG. 2 is a sample 1 and a sample 2 of the magnetostrictive detector according to the present invention.
FIG.

FIG. 3 is an external view of Sample 3 of the magnetostrictive detector according to the present invention.

FIG. 4 is a cross-sectional view of essential parts of a sample 3 of a magnetostrictive detector according to the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a torque sensor used for measurement of the present invention.

FIG. 6 is a torque detection circuit diagram of the torque sensor shown in FIG.

[Explanation of symbols]

 1 axis 2 concave stripe 3 convex stripe 4 magnetic alloy layer 5, 6 coil 7 transistor 8 input terminal 9 output terminal

Claims (3)

[Claims] 1. A magnetostrictive detector for a torque sensor comprising a magnetic alloy layer having a magnetostrictive effect on the outer peripheral surface of a torque transmission shaft, wherein the magnetic alloy layer is formed on the outer peripheral surface of the torque transmission shaft by a thermal spraying method. A heat treatment is performed in an oxidizing atmosphere, the surface of the sprayed layer is subjected to pressure plastic working, and a plurality of concave lines and convex lines inclined at an angle of 45 ° with respect to the longitudinal direction of the shaft are formed at regular intervals. Of manufacturing magnetostrictive detector for torque sensor. 2. A magnetostrictive detector for a torque sensor comprising a magnetic alloy layer having a magnetostrictive effect on the outer peripheral surface of a torque transmitting shaft, wherein the outer peripheral surface of the torque transmitting shaft is at an angle of 45 ° with respect to the longitudinal direction of the shaft. A plurality of sloping ridges and ridges are formed at regular intervals, a magnetic alloy layer is formed on the ridges and ridges by a thermal spraying method, and heat treatment is performed in a non-oxidizing atmosphere to make the surface of the thermal spraying layer concave. A method for manufacturing a magnetostrictive detector for a torque sensor, which comprises pressing and performing plastic working following the ridges and ridges. 3. An outer peripheral surface layer of a torque transmission shaft having a magnetic alloy layer having a plurality of concave and convex lines inclined at an angle of 45 ° with respect to the longitudinal direction of the shaft and formed at regular intervals by machining. 3. The method for producing a magnetostrictive detector for a torque sensor according to claim 1, wherein the ridge of the torque transmission shaft is exposed on the surface while leaving the magnetic alloy layer in the groove.