JPH0134328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic scale and a method for manufacturing the same. Conventional magnetic scales have been formed by depositing a magnetic layer on a non-magnetic substrate by plating, vapor deposition, sputtering, etc., by coating magnetic powder, or by depositing a plate-shaped magnetic material. Then, the detector was moved along the flat surface of the magnetic material to detect the position or measure the length. However, in order to improve the detection accuracy, it is necessary to precisely process the flat part of the magnetic material, and if precision polishing is performed for this purpose, the manufacturing cost increases. In addition, when grinding with a grinder to reduce manufacturing costs, the thin plate-shaped magnetic material deposited on the non-magnetic substrate is thermally affected and is separated from the non-magnetic substrate.
It was impossible to grind with high precision.

On the other hand, if a thick round bar or square bar of magnetic material is used to enable grinding, Fe-Cr-Cc or Fe-Co-Mn-C alloys with good magnetic properties using the expensive Co element can be used. In such cases, the material cost becomes high, which is not desirable.

The present invention provides a magnetic scale that can be ground at low cost and that can also serve as an axis for moving a detector, and a method for manufacturing the same.

The magnetic scale according to the present invention has Fe in a groove formed along the longitudinal direction of one surface parallel to the longitudinal direction of a rectangular parallelepiped made of austenitic stainless steel.
It is characterized by a structure in which a magnetically hard magnetic metal wire of the -Co-Mn-C system is fixed.

Furthermore, the manufacturing method is Fe-Co-Mn
- Magnetism characterized in that a C-based magnetically hard magnetic metal wire is embedded in a groove formed in the longitudinal direction of a rectangular body made of austenitic stainless steel, fixed by welding or brazing, and then surface ground. It is manufactured using a scale manufacturing method.

The substrate in which the magnetic metal wire is embedded is preferably austenitic stainless steel, for example, with a thermal expansion coefficient of 14 ppm/°C or more and 18 ppm/°C or less. The reason is that the thermal expansion coefficient of the Fe-Co-Mn-C magnetic alloy wire proposed by the present inventors closely matches that of austenitic stainless steel.
This is because the magnetic recording medium and the substrate are not well compatible with each other due to temperature changes and are not separated.

The width of the groove pre-drilled in the non-magnetic substrate is preferably about the diameter of the magnetic metal wire to be embedded, and it is undesirable from the viewpoint of workability if the width of the groove is too wide and the magnetic metal wire can be easily removed. Furthermore, it is not desirable to obtain a good magnetic scale if the width of the groove is so narrow that the magnetic metal wire or nonmagnetic substrate is deformed during embedding. If the depth of the groove is less than half the diameter of the embedded magnetic metal wire, the embedded magnetic metal wire will come off without effort, which is undesirable from the viewpoint of work. It is clear that if the diameter is longer than the diameter of the magnetic metal wire to be embedded, the amount of grinding required to obtain a flat surface of the magnetic material increases, resulting in an expensive magnetic scale. Therefore, it is sufficient that the depth of the groove is more than half the diameter of the magnetic metal wire to be embedded, but not more than that diameter. The bottom surface of the groove may be a flat surface as shown in FIG.

The magnetic metal wire used in the present invention preferably has a coercive force of 300 oersted or more so as not to be affected by external magnetic fields, and is preferably made of a material with a high residual magnetic flux density. When a magnetic head is used for detection, detection is possible even if the residual magnetic flux density is low to some extent, but in that case, a great deal of effort is expended in positioning the magnetic scale and the magnetic head. Further, when using a magnetoresistive element, a somewhat high residual magnetic flux density is required. Moving the detector especially at high speeds,
When performing position detection, it is desirable that the magnetic scale and the detector do not come into contact with each other, and in that case, the residual magnetic flux density of the magnetic metal material needs to be high. Also,
In order to fabricate a high-resolution magnetic scale, the magnetic recording medium must be formed with a dense N-S pole pattern, and the Cu-Ni-Fe alloy has a dense N-S pole pattern.
This is not desirable for forming an S-pole pattern.
Therefore, the Fe-Co-Mn proposed by the present inventors
-C system or the alloy including Mo, W, Si, B, V,
An alloy magnetic material containing one or more of Cr and Ti is desirable.

In order to fix the magnetic metal wire installed in the groove, it is desirable to fix it by welding or brazing. In the case of welding, it is necessary to adjust the amount of electric power so that the melted area does not become large due to the heat generated during welding.

In the case of brazing, it is necessary to select a brazing material depending on whether brazing is to be performed before or after final heat treatment. That is, when brazing is performed before the final heat treatment, it is necessary to use a brazing material with a melting point higher than the heat treatment temperature, and when brazing is performed after the final heat treatment, it is necessary to use a brazing material with a melting point lower than the heat treatment temperature. If the magnetic metal wire is not fixed in the groove by welding or brazing as described above, but is simply embedded in the groove, the magnetic metal wire will break away from the base when subjected to temperature cycles. It jumped out of the groove of the magnetic scale and stopped playing its role as a rod for the magnetic scale. However, when the magnetic metal wire was fixed by welding or brazing, the magnetic metal wire did not jump out of the groove even if the temperature history of the cycle was applied.

The purpose of the final heat treatment described above is to optimize the magnetic properties of the magnetic metal wire as a magnetic scale, but the final heat treatment may be performed either before or after embedding it in the groove of the non-magnetic substrate. is obvious.

When the magnetic scale obtained as described above is used as a guide shaft for moving the detector using a non-magnetic substrate, it can function as both a magnetic scale and a guide shaft in one piece, thereby saving parts and simplifying the structure. It is also clear that this method is useful in reducing the cost of the device.

When using a general detection head or magnetoresistive element, the diameter of the Fe-Co-Mn-C magnetic metal wire used is sufficient if it is 0.5 mm or more, and if it is too thick, the expensive Co element Magnetic metal wires using these materials are expensive, and magnetic metal wires with a diameter not exceeding 3 mmφ are appropriate.

Next, the magnetic scale of the present invention and its manufacturing method will be explained by way of examples.

Example A groove as shown in Fig. 1a, 0.5 mm wide and 0.5 mm deep, was dug in a straight line on one side of a rectangular SUS303 material measuring 6 mm square and 1000 mm long. At a weight ratio of 0.5 mm in diameter to that groove
38.025%Co-19.512%Mn-0.585%C-1.366%Si
-0.488%V - A cold-drawn alloy wire made of residual Fe is embedded in a groove of SUS303 material in which a brazing filler metal with a melting point of 470°C is molten, and the wire is quickly cooled and fixed to form a composite. And so. 450 that complex
Heat treatment was performed at °C for 30 minutes in a hydrogen atmosphere. The heat-treated composite was fixed with the groove portion facing upward, and while being cooled with liquid, the wire embedded surface was ground into a flat surface with a precision grinder so that H = 5.83 mm as shown in Figure 2. The embedded magnetic metal wire did not come loose from the groove, and a good flat surface of the magnetic material was obtained. Moreover, by producing a composite body by welding using this magnetic metal wire and grinding it, a good flat surface was obtained in which the wire did not come loose from the groove.

When magnetic writing was performed on the magnetic scale manufactured in the example at regular intervals and read using a detection magnetic head or a magnetoresistive element, detection signals were obtained at the same intervals as the writing intervals.

Note that the heat treatment conditions shown in the examples are not limited to these, and may be changed as appropriate depending on the materials used and other various conditions.

[Brief explanation of drawings]

Figures 1a and 1b show the shapes of grooves dug in the stainless steel non-magnetic substrate of the present invention, where W indicates the width of the groove and h indicates the depth. FIG. 2 shows a cross section of the magnetic scale manufactured in Examples 1 to 3. H indicates the dimensions of the nonmagnetic substrate. In the figure, 1 is a groove formed in a non-magnetic substrate, 2
is the magnetic metal wire fixed in the groove, and W and h are the width and depth of the groove.

Claims (1)

[Claims] 1. A magnetic device characterized by a structure in which a Fe-Co-Mn-C-based magnetically hard magnetic metal wire is embedded in a groove formed along a rectangular parallelepiped made of austenitic stainless steel. scale. 2. Embed a Fe-Co-Mn-C magnetically hard magnetic metal wire in a groove formed along the longitudinal direction of a rectangular body made of austenitic stainless steel, and lengthen the magnetic metal wire by welding or brazing. 1. A method for manufacturing a magnetic scale, which comprises fixing it in a groove of a rectangular shape and grinding the surface of the magnetic metal wire embedded therein.