JPS6257929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic scale for measuring length, angle, etc., which is the basis of positioning in machining, for example, and in particular, detection of a magnetic grating by a magnetic head reduces the S/N ratio. Desired magnetism that has a high magnetic flux density in the recording magnetic grating, for example, has a residual magnetic flux density of around 30 to 50 G or more, and has characteristics that allow the recording density of the magnetic grating to be high and have high detection resolution. This relates to a method for manufacturing a scale magnetic material having the dimensions and shape for a scale, and for a magnetic scale, a ring-shaped recording or detection head such as a U-shape on the scale surface moves relatively in the measurement direction. A conventional type in which a magnetic lattice is arranged and recorded in parallel with the north and south poles in the direction,
For example, a multi-gap magnetic head described in Japanese Patent Publication No. 40-467 can be used, but the magnetic scale magnet or magnetic material plate or film may be used in a direction perpendicular to the direction of scale measurement relative movement of the magnetic material plate or film. Magnetization recording (perpendicular magnetization) of the magnetic lattice is performed so as to penetrate in the front and back directions of the film.Therefore, as a magnetic head for detecting or recording the magnetic lattice, the magnetic material is placed between the magnetic gaps of the ring-shaped head. For example, the method described in JP-A-49-65852, in which a plate or membrane is inserted and relatively moved, can be suitably applied, but according to the present invention, as described above, the magnetic scale From the place where the magnetic flux density of the magnetic lattice recorded in is large,
For example, a known magnetic detection head using a magnetoelectric transducer as described in Japanese Patent Application Laid-open No. 50-91348 can also be used.

Instead of residual magnetic recording in the measurement longitudinal direction or in the measurement longitudinal plane of the magnetic medium for magnetic scales as described above, magnetic recording is performed in the front and back directions of the magnetic medium, that is, perpendicular magnetization, and the recording medium is used as a measurement scale. For example, it can be used as
This is already known from the publication No. 1 and others.

Therefore, in this type of perpendicular magnetization magnetic scale, the focus is usually on increasing the residual magnetic flux density to increase the S/N ratio so that the recorded magnetic grating can be detected.

Therefore, it is possible to use a magnet material with a high residual magnetic flux density, apply a magnet manufacturing method that increases the residual magnetic flux density, or further improve the thickness of the plate or film in the direction of through magnetization of the magnetic recording medium, and other dimensions and shapes. etc., but the high density of the magnetic grid (e.g. 50
(within around 100 μm) There are problems with recording and detection resolution, not only because it is difficult to record at a sufficiently high density with magnetic gratings, but also because the resolution is not good when detecting from a magnetic scale. This resulted in the inability to perform magnetic lattice recording with a desired sufficiently large residual magnetic flux density. That is,
Conventionally, there are no good magnetic materials or magnetic scale materials for perpendicular magnetization as described above, and therefore, for example, as described in the above-mentioned Japanese Patent Application Laid-Open No. 49-65852,
A magnetic structure in which a plurality of magnets 2 that can be magnetized or demagnetized are implanted or interposed, regularly arranged at equal intervals along the periphery of the disk 2 or along the length of the flat plate 8. Although a scale was devised, the recording density of the magnetic grating (magnet 2) was obviously extremely low, the resolution was low, the precision was low, and its manufacture was extremely difficult.

The magnetic scale of the present invention made of a magnetic recording medium in the form of a ribbon, a thin plate, a film, or a thin disk has the following characteristics:
Due to its purpose, usage, size, shape, etc., the thickness of several mm or less is 0.3 mm or less due to hot or cold rolling.
Since it is necessary to form a thin plate or film with a thickness of approximately mm or more, the magnet material or magnetic material used as the magnetic recording medium must preferably have better rolling workability.

There are two types of magnet materials: magnetically isotropic and anisotropic.The former isotropic has an easy magnetization direction or a difficult magnetization direction in the magnet material itself (e.g. [100], [010], [001]…
...direction), and therefore, no matter which direction it is magnetized, it has almost the same magnetic properties in the magnetization direction, except for the shape effect.
Magnet materials clearly have an easy magnetization direction and a difficult magnetization direction, and when magnetized in the easy magnetization direction versus the difficult magnetization direction, there is a marked difference in magnetic properties, and the latter is much better.

In addition, isotropic materials can be subjected to magnetic field treatment (heat treatment in a magnetic field) or plastic machining such as rolling in the manufacturing process such as heat treatment machining, that is, magnetic anisotropy processing, or if processing is performed, the latter will change. There are objects that become anisotropic and objects that remain isotropic regardless of the magnetic anisotropy process, whereas magnetically anisotropic objects become anisotropic due to the magnetic anisotropy process. It has come to have a sexual nature.

In the case of heat treatment in a magnetic field, the magnetic anisotropy is such that the direction of the magnetic field applied during the heat treatment in the magnetic field or a direction parallel to the same is the direction of easy magnetization, and the direction perpendicular thereto is the direction of difficult magnetization. In addition, when mechanical plastic processing such as rolling is applied, the direction of the rolling process or a direction parallel to this is the direction of easy magnetization,
Normally, the direction perpendicular to this direction is the direction in which magnetization is difficult.

Therefore, if a magnetic scale is manufactured by selecting a magnet material simply from the viewpoint of having mechanical plastic workability and rolling it into a thin plate, it is possible to produce a magnetic scale that is magnetically isotropic and an anisotropic magnetic scale due to rolling. However, with the former isotropic magnetic scale, it is difficult to obtain the perpendicular magnetization magnetic scale with the characteristics targeted by the present invention, and with the latter anisotropic magnetic scale, it is difficult to obtain the perpendicular magnetization magnetic scale with the characteristics aimed at by the present invention. Anisotropy is formed in the direction parallel to the surface of the manufactured magnetic scale thin plate, and the direction perpendicular to the plate surface where the magnetic lattice is recorded is the direction in which magnetization is difficult, so depending on perpendicular magnetization, high residual magnetic flux may occur. It goes without saying that it is not possible to form a high-density magnetic grating, and it is not possible to record magnetization on the magnetic grating at high density and narrow intervals, and the detection resolution is also inevitably low.

The present invention is directed to a method of manufacturing a magnetic scale suitable for perpendicular magnetization, which was invented with such a point in mind. are arranged facing each other, and the strip-shaped body and the magnetic head are moved relative to each other in the longitudinal axis direction of the strip-shaped body, or the disc-shaped body is rotated around the axis, or the magnetic head is moved along the outer periphery. In the manufacturing method of a magnetic scale in the form of a strip or disk that moves and rotates along the A cast molded body of a permanent magnet material is rolled into a thin plate shape of approximately 1 mm in thickness by cold rolling or hot rolling at an appropriate temperature, and from the rolled thin plate, a belt-shaped body of a desired length and width or a desired width is formed. A disc-shaped body of the same diameter is cut out by press cutting, and after the cutting or the roll-forming, a heating solution treatment is performed, and then a magnetic field is applied in a direction perpendicular to the plate surface direction of the roll-formed thin plate, band-shaped, or disc-shaped body. A magnetic anisotropy treatment is carried out by heat treatment in a state in which the magnetic anisotropy is applied, and after the magnetic field treatment, aging is performed, preferably multi-stage aging, and then the magnetic anisotropy treatment is carried out in the longitudinal axis direction of the band-shaped body or the outer periphery of the disk-shaped body. It is characterized by sequentially magnetizing a magnetic grating that penetrates the front and back sides of the plate in the thickness direction, intermittently at a predetermined pitch in the direction of the plate.

That is, the present invention provides a permanent magnet that is used when a strip or disc-shaped body made of a permanent magnet material that records and forms a magnetic grating by perpendicular magnetization has magnetic anisotropy in the perpendicular magnetization direction (front and back of the plate surface). Although it depends on the type and composition of the magnet material, it is possible to form a magnetic lattice having a residual magnetic flux density of preferably about 30 to 50 G or more, and the formed magnetic lattice has a magnetic lattice in a direction other than the perpendicular magnetization direction. The residual magnetic flux density is almost nonexistent or extremely small, and the width of the formed magnetic grating in the pitch direction is compared to conventional magnetic scales of this type, although it depends on the dimensions, shape, and magnetization method of the magnetized magnetic head. For example, it can be easily narrowed to about 50 μm to 100 μm or less, which increases the recording density of the magnetic grating, and on the other hand, as is clear from the above, the detection resolution of the magnetic head is high. It will become.

The magnetic scale for such perpendicular magnetization strips and discs has different shapes, dimensions, weight, price,
For other reasons such as recording and detection accuracy (for example, it is difficult to keep the width of the magnetic grid narrow depending on the plate thickness, which may reduce the detection accuracy), the plate thickness may be reduced to a certain level, for example, approximately 1. ~3mm thickness around 0.3mm or less
Although it is almost an essential condition to manufacture it to a thickness, etc., to form it into a thin plate shape as mentioned above, it must have sufficiently good mechanical plastic workability, i.e., cold work or appropriate hot work. It is necessary to have rollability.

In addition, in order for a plate made thin by rolling as described above to have magnetic anisotropy in the front and back directions of the plate, it must be subjected to heat treatment in a magnetic field, except in the case of a special manufacturing method described below. It is.

Therefore, in manufacturing the magnetic scale of the present invention, a magnetic material (preferably one with excellent magnetic properties, particularly one with a large residual magnetic flux density, a large coercive force, and excellent aging resistance) is used as the material. (Therefore, it is usually a permanent, i.e., hard magnetic material, but in some cases, a semi-hard magnetic material may be sufficient.) has good mechanical plastic workability as described above and can be used in a magnetic field. This is limited to magnetic materials that have greater magnetic anisotropy through heat treatment, such as Cunife, Cunico, etc., which have good rolling workability but generate magnetic anisotropy only through such machining. On the other hand, materials such as so-called Alnico magnet materials and rare earth-cobalt alloy magnet materials, which generate sufficient magnetic anisotropy by heat treatment in a magnetic field, but have almost no machinability such as rolling, etc. It is clear that this is not the case.

In addition, Pt-Co magnet materials that produce magnetic anisotropy through ordinary heat treatment without heat treatment in a magnetic field have excellent plastic workability. Since such alloys are unique to magnetic materials, it is difficult to immediately consider such alloys as magnetic materials subject to the present invention.

However, the Fe-Cr-Co-based material, which the present inventors have previously proposed as a hard or semi-hard magnetic material, is suitable as a magnetic material to be used in manufacturing the magnetic scale of the present invention. There are many types of magnetic alloys in this series that have a wide range of compositions and one or more various additive elements, as shown below. It is suitable for use as a magnetic material.

Special Publication No. 49-20451 states that the weight percentage is 15.
The alloy composition consists of ~35% Co, 3~50% Cr, and Fe excluding the remaining impurities, and has good mechanical plastic workability and magnetic anisotropy due to heat treatment in a magnetic field.Fe-Cr-
Co-based alloys have been described, and subsequent studies have shown that the essential minimum amount of Co can be reduced by 3-5% with or without the addition of other elements.
It can be expanded to the low Co region.

And, in Special Publication No. 50-23649, the above-mentioned Fe
- As improvements to Cr-Co alloys, alloys with 1 to 20% W, or 1 to 10% W and 0.5 to 50% Mo added are described in Japanese Patent Publication No. 10570/1986 as Fe-Cr-Co alloys.
Alloys with 1 to 12% Si added to the system alloys were
Publication No. 37011 describes a manufacturing method for imparting magnetic anisotropy through a combination of heat treatment in a magnetic field and cold working to improve the magnetic properties of the various Fe-Cr-Co alloys mentioned above. Publication No. 101218 describes the above Fe―
3 to 15% Co to reduce Co in Cr-Co alloy, 15
~40%Cr, 0.2~5%Cu, 0.2~12%Si, and balance
An alloy consisting of Fe is disclosed in JP-A No. 142416/1983, in which a low Co ternary alloy of Fe-Cr-Co is combined with 0.2 to 5% Nb.
Also, alloys with one or both of Ta added, and alloys with 0.5 to 5% Al added are disclosed in JP-A-52
- Publication No. 98613 describes 3 to 30 containing V as an active ingredient.
%Co, 10~40%Cr, 0.1~15%V, and the balance is Fe
In Japanese Patent Publication No. 51-5612, an alloy consisting of 0.1 to 2% Co is added to the above 15 to 35% Co Fe-Cr-Co alloy.
In Japanese Patent Publication No. 51-5613, alloys containing Al contain one or more of Mn, Ni, and Cu.
JP-A No. 51-32416 discloses an alloy in which 0.1-6% of one or more of La, Ce, Sm, and cerium metal is added in an amount of 0.1-3%. Publication No. 29859 describes 10 to 20% Co, 20 to 35% Cr, and 0.3 to 3% Ti as an active ingredient.
A semi-hard magnetic alloy consisting of Ti and the balance Fe,
In addition, 0.05 to 1.5
Fe-Cr-Co alloys containing % Zr as an active ingredient have been described, and various methods for producing alloys with the various compositions mentioned above have already been proposed. The characteristics of the series alloy depend on its alloy composition, but for example, it has good magnetic properties comparable to AlnicoV, and as mentioned above, it has extremely good mechanical plastic workability. Therefore, processing for imparting magnetic anisotropy by heat treatment in a magnetic field is effective.

To explain the manufacturing method of the present invention with examples, the weight percentage is 2% Ti - 3% V - 15% Co - 21% Cr -
An alloy having a composition with the balance consisting of Fe is melted in a high frequency furnace in an inert atmosphere such as argon gas or a weakly reducing atmosphere containing hydrogen, etc., and then cast into an appropriate shape and size.

Next, the cast molded body is heated to about 1000 to 1300° for about 30 minutes for tempering and solution treatment.

This heating temperature changes approximately proportionally depending on the Co, Cr, especially Co content of the alloy; for example, 10% Co
It is possible to lower the temperature to below 1000℃ at around 35
%Co, it is necessary to set the temperature to about 1350°C.

After this tempering solution treatment, it is desirable to once quench the material by water cooling or oil cooling, but it may also be allowed to cool naturally to the next rolling temperature.

Next, rolling is performed, and the final finishing process of rolling is preferably cold working with a working rate of 20% within 60 to 80%, but the rolling process before that is cold working. If only partial working is used, annealing will be required every time a working rate of 60 to 80% or higher is reached, so rough rolling is performed at a temperature of around 300°C or higher, for example, to simplify and improve the efficiency of rolling. It is better to measure

When rolling to a predetermined thickness, for example 1 mm, is completed, the plate is cut or press punched into a predetermined scale size and shape, or the above-mentioned tempering and solution treatment are performed before that.

In other words, magnetic anisotropy is formed in the plate surface (rolling) direction due to rolling, and this magnetic anisotropy is erased by tempering and solution treatment. Water-cooling or oil-cooling quenching is preferably performed, but natural or forced cooling may be performed to the temperature of the subsequent heat treatment in a magnetic field for imparting magnetic anisotropy.

Then, in the magnetic field heat treatment, a magnetic field of about 3000 to 4000 Oe is applied to apply magnetic flux perpendicular to the plate surface, for example by sandwiching the plate between magnetic yokes, and the temperature is heated to 630 to 690°C for 30 to 60 minutes. The heating temperature and time depend on the alloy composition, and in the case of the above composition, 670° C. for about 30 minutes is preferable.

Then, multi-stage or continuous aging is performed at least once at a predetermined temperature, or preferably by gradually decreasing the temperature. In the solution treatment and each subsequent heat treatment process, instead of handling and processing the thin plates one by one, a large number of thin plates of appropriate or predetermined dimensions and shapes are stacked closely together, and the thin plates are placed between the thick plates. It is preferable to hold the sheets fixed by appropriate mechanical means such as clamping or other means in order to prevent various deformations such as warping and curving.Also, cutting into a predetermined size and shape is done mechanically while the sheets are stacked as described above. or wire cut electrical discharge machining or other electrical machining such as electron beam machining, laser,
It may also be cut and formed by beam machining or the like.

Therefore, as a preferable example of the multi-stage aging for the above-mentioned composition alloy, after the heat treatment in the magnetic field, the temperature is transferred to the first stage aging temperature by cooling to room temperature or cooling in a furnace, and the multi-stage aging is performed at 620°C.
× 1 hour → 600℃ × 1 hour → 580℃ × 1 hour → 560
℃×1 hour→540℃×4 hours→cooling, and these temperature and time conditions also need to be changed to some extent depending on the alloy composition.

According to this manufacturing method, when the plate is magnetized in the direction perpendicular to the plate surface, the residual magnetic flux density Br≒14500G,
Coercive force Hc≒520Oe, maximum energy product (B・H)
max≒5.8×10 ⁶ G・Oe, squareness of about 0.9 or more, which indicates magnetic performance, and the magnetic properties in the direction parallel to the plate surface of the plate are magnetic anisotropy due to the manufacturing method described above. Since the chemical processing was almost 100%, it only exhibited ferromagnetic properties with high magnetic permeability (μ), and its magnetic properties were almost zero.

And such magnetic anisotropy and magnetic properties are
The same applies to the other Fe-Cr-Co alloys mentioned above, and they are suitable for achieving the objectives, effects, and effects of the present invention in combination with perpendicular magnetization recording and detection/reading configurations. I understand.

When magnetic gratings with perpendicular magnetization in the plate thickness direction were applied to a scale material finished in the shape of a band or disk with a thickness of about 1 mm at a pitch of 50 to 100 μm, the direction of magnetization was changed every other time. The magnetic flux density was sufficiently greater than 30 to 50 G, the S/N ratio was kept high, and the detection resolution was sufficiently good.

It is clear that this magnetic material has sufficient aging resistance in terms of magnetic properties and magnetic anisotropy, and depending on the application and usage, it can be used for wear resistance, lubrication, and/or Alternatively, it may be coated with synthetic resin or other surface treatments for rust prevention.

The magnetic head for perpendicular magnetization recording or detection readout of magnetic gratings is a magnetic yoke that short-circuits a pair of magnetic gratings adjacent to each other or separated by a plurality of pitches with a minute gap between them on one side of the scale. and a magnetic yoke having a magnetized record or a detection readout coil arranged to short-circuit the pair of magnetic gratings with a small gap on the other surface. .

It would be effective if the magnetic anisotropy formed by mechanical rolling could be added to the magnetic anisotropy produced by the above-mentioned heat treatment in a magnetic field, since the coercive force would increase and the demagnetization resistance over time would increase. A piece of a predetermined thickness is cut out from the end of the rolled plate perpendicular to the rolling direction, heat treated in a magnetic field in the direction of the cut thickness, and the thickness direction is perpendicular to the magnetic grid. This manufacturing method seems to have a problem that needs to be solved, as it is necessary to set the magnetization direction in the direction of magnetization, and depending on the machine and other processing methods such as cutting, there is a possibility that the percentage of processing losses will increase.

As described in detail above, the present invention proposes a method for manufacturing a magnetic scale for perpendicular magnetization, particularly a band-like or disk-like body having magnetic anisotropy in the perpendicular magnetization recording direction. It has a sufficiently large magnetic flux density and a high S/N ratio, enabling high-density recording of magnetic gratings, while also providing a magnetic scale that can perform perpendicular magnetization recording and detection readout with high resolution. In addition to alloys, the present invention can also be applied to magnetic alloys having similar properties to produce excellent magnetic scales.

Claims (1)

[Scope of Claims] 1. A band-shaped magnetic scale in which a detection magnetic head is disposed in opposition to the plate surface of the band-shaped body, and the band-shaped body and the magnetic head are moved relative to each other in the longitudinal axis direction of the band-shaped body. In the manufacturing method, a permanent magnet material that can be mechanically plasticized and subjected to magnetic anisotropy processing is used, and a cast molded body of the permanent magnet material is subjected to rolling processing such as cold rolling. The rolled thin plate is rolled and formed into a thin plate shape, and a strip having a desired length and width is cut out from the rolled thin plate by pressing and cut. After the cutting out or after the rolling forming, a heating solution treatment is performed, and then the thin plate or strip is cut out. A magnetic anisotropy treatment is performed in which a magnetic field is applied in a direction perpendicular to the direction of the plate surface of the body, and further, after the magnetic field treatment, the material is aged and then intermittently at a predetermined pitch in the longitudinal axis direction of the strip body. 1. A method for manufacturing a magnetic scale, characterized by sequentially magnetizing a magnetic lattice in the plate thickness direction. 2 Layering a desired number of the rolled thin plates or cut out strips, subjecting the stacked body to heat solution treatment, and then applying a magnetic field in the stacking direction of the stacked body, 2. The method of manufacturing a magnetic scale according to claim 1, further comprising performing a magnetic anisotropy treatment by heat treatment. 3. The method of manufacturing a magnetic scale according to claim 1, wherein the permanent magnet material is made of an Fe-Cr-Co spinodal decomposition type magnet alloy. 4. A disc-shaped body in which a detection magnetic head is disposed in opposition to the outer peripheral edge surface of the disc-shaped body, and the disc-shaped body is rotated around an axis or the magnetic head is moved and rotated along the outer peripheral edge. In the manufacturing method of the body magnetic scale, a permanent magnet material that can be mechanically plasticized and subjected to magnetic anisotropy processing is used, and a cast molded body of the permanent magnet material is processed by cold rolling, etc. A desired disc-shaped body is cut out by pressing and cutting from the rolled thin plate, and a heating solution treatment is performed after the cutting or after the rolling forming, and then the thin plate or A magnetic anisotropy treatment is performed in which a magnetic field is applied in a direction perpendicular to the plate surface direction of the disc-shaped body, and then the outer periphery of the disc-shaped body is aged in the circumferential direction after the magnetic field treatment. 1. A method of manufacturing a magnetic scale, characterized by sequentially magnetizing a magnetic grid in the thickness direction intermittently at a predetermined pitch. 5. A desired number of disk-shaped bodies cut out after the above-mentioned rolling forming are stacked together, the stacked body is heated and solution-treated, and then a magnetic field is applied in the stacking direction of the stacked bodies, and the above-mentioned 5. The method of manufacturing a magnetic scale according to claim 4, further comprising performing a magnetic anisotropy treatment by heat treatment. 6. The method of manufacturing a magnetic scale according to claim 4, wherein the permanent magnet material is made of an Fe-Cr-Co spinodal decomposition type magnet alloy.