JPS586883B2 - How to make a magnetic scale - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A conventional magnetic scale has a magnetic tape-like magnetic layer coated on a predetermined band-shaped or rod-shaped substrate, and a rectangular wave or sine wave signal of a certain wavelength is magnetically recorded on the magnetic layer. A known device is one in which a magnetic head is opposed to the magnetic layer and moved relative to the magnetic layer, and the relative position is detected by the magnetic head.

However, since the magnetic layer and the base of such a magnetic scale are made of different materials, they are easily affected by heat due to the difference in thermal expansion coefficients, and distortion due to thermal expansion occurs between the two, causing a difference in detection. Since the scale is magnetically recorded on a planar magnetic layer at a constant wavelength, the detection output of the magnetic-to-electrical conversion by the head cannot be large, which has the disadvantage of lowering detection accuracy.

The present invention provides a magnetic scale that eliminates such drawbacks.The scale uses an integrated magnet as a base material, which is magnetized with equidistant graduations, and the magnetized magnetic pole portion and other In this case, unevenness is formed by electrolytic or chemical polishing on the part of the magnet, thereby forming an uneven magnetization scale.

During chemical polishing or electrolytic polishing (processing), if a non-processed layer is formed by adhering ferrite etc. to the magnetized scale using magnetization and then processed, it is possible to form a precisely uneven scale, and the magnetized magnetic pole scale It is possible to form a magnetized scale that is convex and stands out from the others, which allows extremely large detection output and highly sensitive detection.

The following description will be given with reference to one embodiment. FIG. 1 shows an example in which a magnetized uneven scale 2 is formed on one side of a long base material 1, such as a bar or strip.

Reference numeral 3 denotes a magnetic head which moves relatively to face the concavo-convex scale 2 with a minute gap, and this read detection is performed by converting magnetic changes into electrical signals by appropriate methods and means.

FIG. 2 shows a case where magnetized concave and convex scales 21 and 22 are formed on both sides or the entire surface of a long base material 1. In this case, the detection head can be provided with a head facing both scales 21 and 22 for detection. can.

FIG. 3 shows another embodiment in which a magnetized concavo-convex scale is inclined at a predetermined pitch at a predetermined angle, or a scale 4 in the shape of a screw shaft is formed.

As for the magnetization method, magnet 1 may be magnetized with a predetermined wavelength in the length direction as shown in Fig. 1. Alternatively, as shown in Fig. 2, a strip magnet, a square bar magnet, or a base material magnet may be used to magnetize both the upper and lower sides. When forming uneven scales 21 and 22 symmetrically,
It can be magnetized in the vertical direction as shown in the figure.

In this case, the magnetic pole detection results in more than twice the detection output.

Next, the production of such a magnetic scale will be explained.

For the base magnet 1, it is necessary to select a magnet material that can be easily machined by rolling, wire drawing, cutting, grinding, etc. so that scale shapes such as linear, strip, and rod shapes can be easily obtained.

An Or-Fe spinodal decomposition type magnet alloy is suitable for such a magnet material.

Of course, Fe-Ni-A is a magnet material that can be processed and is easy to process.
7 system, Fe-Ni-Ti system, Fe-Al-Ni-Co system, Fe-Mo-Co system, Fe-Pt, C
o -P t, Fe-Mn system, Mn-Al system F
Conventionally known materials such as e-Mn-Al series and Mn-Al2-Ti series can be used.

Therefore, a Cr--Fe--Co based magnet alloy is used, and a base material that is machined into a desired shape such as a bar or a band is manufactured using this alloy material.

Next, a magnetic head for magnetization is provided opposite to this base material, and a first
Magnetization is performed in the length direction in the figure and in the thickness direction in FIG.

Since this magnetization determines the precision of the scale, it is carried out precisely and magnetized at predetermined equidistant graduations.

In the one in Figure 1, for example, the distance between the N and S poles is set to 1 mm,
In addition, the one in Figure 2 has a thickness of 2 mm, with N on one side and S on the other.
magnetize.

Of course, the magnetization interval and the like can be selected and controlled as desired.

On the base material magnetized in this way, a 100oA Fe
304 magnetic powder, and 10μ2 plastic particles approximately 1
: A mixture of 0.5 parts water and 1 part glycerin
Disperse and mix in a 5% solution and apply.

The coating is performed accurately on the magnetized scale by utilizing magnetization, and the coating layer is fixed by sintering at 120° C. for 10 minutes.

Next, chemical etching (polishing) or electrolytic processing is performed, but the Fe304 coating layer fixed on the magnetized scale becomes an unprocessed layer, and this portion remains unprocessed and protrudes.

For example, when electrolytically processed with a 15% NaN03 solution for 5 minutes, the magnetized pole part is about 0.0% larger than the other parts. The width of the convex portion and the width of the concave portion were approximately 40μ and 50μ, respectively, which were embossed with a difference in depth of 1 mm.

Normally, convex portions of about 10 μm and concave portions of about 20 μm can be easily formed.

By flowing the chemical polishing liquid and electrolyte during processing, processing speed is improved and processing accuracy is also improved.

The detection test of the magnetic scale processed in this way will be explained with reference to Figure 4.
A magnetic head 6 comprising 0 magnetic poles (permalloy) 5 is placed opposite the head 6, and the head 6 is excited by a 50 KHz power source 7.
It was possible to obtain an output of about 55 mV from the magnetic-electrical conversion detection circuit 8.

This is because the magnetizing force is strong, the magnetic gradient between the protruding magnetic pole and the concave part is high, and the sensitivity is high.This makes it possible to detect extremely strong changing magnetic flux at the scale part of the convex magnetic pole. is about 100 of the conventional scale with a flat magnetic scale.
It is possible to obtain twice as high output power.

Furthermore, as shown in the figure, when the magnetized scale on the lower surface and the upper surface of the scale were simultaneously detected in parallel, the output was about three times the above (150 mV), which was about 300 times higher than the conventional one.

The magnetic scale can be read with high precision using the normal interpolation method, and for the scale of wavelength λ (1
+7) When installing multiple heads offset by λ and detecting the phase of N-multiplied phase modulation (or amplitude modulation) output, the carrier frequency increases N times and the carrier phase becomes 2π.
If one pulse is output every time the value changes and the counter is counted, N interpolation is possible, and accurate readout of 10μ units from λ=100μ can be easily performed.

Furthermore, in the case of the inclined graduation scale shown in FIG. 3, if a plurality of n magnetic detection heads are arranged on a line perpendicular to the movement direction (up and down) for detection, λ/n becomes the minimum unit of detection, and for example, λ =100μ and n=10, reading with 10μ precision is possible, and by further interpolating corners using the interpolation method described above, reading with 1μ precision is possible.

In this way, the magnetic scale of the present invention has a magnetized concavo-convex scale, and has high sensitivity and can detect with high precision.Also, since the scale is composed of an integral base magnet, it does not suffer from thermal distortion. It can be used without any problem, and can be used for positioning and detection of machine tools, etc., making it possible to perform highly accurate readings.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of one embodiment of the present invention, FIGS. 2 and 3 are structural diagrams of other embodiments, and FIG. 4 is a diagram of one embodiment of magnetic detection. 1 is a base magnet, 2 is a magnetized uneven scale, 3 is a magnetic head, 2
Reference numerals 1 and 22 denote magnetization uneven scales, 4 an inclined magnetization uneven scale, 5 a magnetic pole, 6 a magnetic head, 7 an excitation power source, and 8 a detection circuit.

Claims (1)

[Claims] 1. Magnetize a base magnet at equal intervals, form an unprocessed material layer on the magnetized portion by magnetic adsorption, and then make the magnetized portion protrude by chemical or electrochemical processing. A method for manufacturing a magnetic scale, characterized by forming an uneven magnetized scale using a magnet.