JPH0287014A - Preparation of magnetic scale - Google Patents

Abstract

PURPOSE:To enhance detection sensitivity and an S/N ratio by superposing non-magnetic austenite type stainless steel on ferromagnetic steel and heating both of them at a desired interval on the side of the austenite type stainless steel using a high energy density heat source. CONSTITUTION:A base plate 1 is constituted by superposing plate-shaped non- magnetic austenite type stainless steel 2 on plate-shaped ferromagnetic steel 1. Laser beam or electron beam 20 being a high energy density heat source is applied to the heated parts 3 of the base plate 1 so as to form a desired interval between the heated parts 3 to heat the same and at least a part of the non-magnetic steel and the ferromagnetic steel 1 is melted at the heated parts 3 to be solidified. The non-magnetic steel 2 is melted by the irradiation with laser beam to be mixed with the ferromagnetic steel 1 and subsequently solidified to form magnetic grids to the base plate 11 at a predetermined interval. By irradiating the base plate 1 with beam to arbitrarily select the interval between the magnetic grids formed on the substrate 1 and using a magnet 4 and an element for detecting the quantity of magnetic flux 30, for example, a Hall element, the relation between displacement quantity and residual magnetization quantity is obtained and displacement can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a magnetic scale that can be used in a high temperature environment.

[Prior Art] FIG. 6 is a cross-sectional view showing a conventional magnetic scale disclosed in, for example, Japanese Patent Publication No. 10655/1988 entitled "Magnetic Scale." In the figure, (6) is a rod-shaped base made of iron or an iron alloy such as Elinvar (trade name), and (7) is a rod-shaped base made of copper or aluminum plated or clad on the surface of the base (6). The non-magnetic metal layer (8) is a magnetic layer such as cobalt-nickel formed on the non-magnetic metal layer (7).

[Problem to be solved by the invention] The conventional magnetic scale as described above is configured as described above, and for example, the metal data book: edited by the Japan Institute of Metals,
As shown in Marukubi (1974), the thermal expansion coefficients of iron and Elinvar are 12.1xto-6 and 8, respectively.
-OX 10-6, and the thermal expansion coefficients of copper and aluminum are 17.0×l0-6 and 23.5×1, respectively.
0″6. Also, the coefficient of thermal expansion of cobalt and nickel is, for example, Heat-resistant Steel Data Collection: Special Steel Club (1965)
S-816 (AISI 671
) is 11.9X 10-6.

In the configuration shown in FIG. 6, when the temperature reaches 100°C or higher, the base (6), nonmagnetic metal layer (7), and magnetic layer (8)
Since the amount of thermal expansion of N is different, the non-magnetic metal N
There was a problem that (7) and magnetic N (8) were peeled off.

Furthermore, even in cases where peeling does not occur, thermal stress is applied to the substrate (6), non-magnetic metal layer (7), and magnetic layer (8), degrading the magnetic properties of the magnetic layer (8) and reducing the sensitivity of the magnetic scale. There was a problem with the decline.

This invention was made to solve the above-mentioned problems, and aims to provide a method for manufacturing a magnetic scale that does not deteriorate in characteristics even when used in a high-temperature environment, is stable, and has excellent measurement accuracy. This is the purpose.

This objective has been achieved in Japanese Patent Application No. 1982-217315 filed on August 31, 1988 by the same applicant, entitled "Method for Manufacturing Heat-Resistant Magnetic Scale" and
-217316 ``Method for manufacturing heat-resistant magnetic scale''. The former method involves placing a raw material of a different material on a heat-resistant base material, applying heat to the base material together with the raw material at desired intervals, mixing the raw material into the base material, and changing the magnetic properties of the heated part. A method for manufacturing a heat-resistant magnetic scale in which the Curie point of at least one of the base material and the heated portion is 100°C or higher. A method for producing a heat-resistant magnetic scale, wherein the Curie point of at least one of the base material and the heated portion is 100° C. or higher, the magnetic properties of which are changed. ”. However, these
For example, there still remained the problem that the amount of ferrite precipitated was not very large, the amount of residual magnetization was small, and the S/N ratio at the time of detection was not high.

Therefore, the present invention further provides a method with good detection sensitivity and high SN.
It is an object of the present invention to provide a method for manufacturing a magnetic scale that provides a ratio.

[Means for Solving the Problems] A method for manufacturing a magnetic scale of the present invention involves superimposing a non-magnetic austenitic stainless steel on a ferromagnetic steel, and heating the two at a desired distance from the austenitic stainless steel side using a high energy density heat source. At least a portion of the austenitic stainless steel and ferromagnetic steel in the heated portion is melted and solidified to precipitate magnetic ferrite to form a magnetic lattice.

[Operation] In this invention, ferromagnetic steel and non-magnetic steel are stacked on top of each other, and both are heated from the non-magnetic steel side using a high-energy density heat source.
The underlying ferromagnetic steel is also melted into the heated part to precipitate magnetic ferrite to form a magnetic lattice, and the ferromagnetic steel is used to connect magnetically, resulting in high detection sensitivity and high S/N ratio. It is possible to manufacture a magnetic scale without problems such as characteristic deterioration even when used in a wide range of areas.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a perspective view illustrating a method of manufacturing a magnetic scale according to an embodiment of the present invention. (1) is a plate-shaped ferromagnetic* (for example, ferritic or martensitic stainless steel, JIS 5US410 or 5US430, etc.), (2)
is a plate-shaped austenitic nonmagnetic stainless steel (for example, JIS 5US304), (11) is a ferromagnetic steel (1)
This is a substrate made by superimposing the magnetic material and non-magnetic steel (2). (3) is a heated portion heated by irradiating the substrate (11) from the non-magnetic steel plate (2) side with a high-energy density heat source (2o) such as a laser beam or an electron beam at a desired interval;
3) At least a portion of the non-magnetic steel (2) and the ferromagnetic steel (1) are melted and solidified. Non-magnetic @ due to beam irradiation
(2) is melted and solidified and mixed with ferromagnetic steel (1), in other words, ferromagnetic steel (1) is also melted,
Ferrite is precipitated to become a ferromagnetic material, and a magnetic lattice is formed at predetermined intervals on the substrate (11).

For example, the non-magnetic steel (2) is 5US30 with a plate thickness of 1 mm.
4. 5US410 with a plate thickness of 1 mm was used as the ferromagnetic steel (1), and CO2 was used as the high energy density heat source (20).
When the laser is irradiated and heated under conditions of an output of 14 and a beam scanning speed of about 2 m/min, a molten part with a fusion width of 1.2 mm and a fusion depth of 1.5 mm is formed in the heated part (3). That is, a magnetic grid is formed inside the non-magnetic steel (2) of the heating part (3) and is magnetically connected by the ferromagnetic steel (1).

FIG. 2 is a side view showing how displacement is detected using a magnetic scale according to an embodiment of the present invention.

In the figure, (5) is an element that detects the amount of magnetic flux, such as a Hall element, (4) is an excitation magnet, and (30) is a magnetic flux. A current is passed through the excitation magnet (4) to form a magnetic field, and the amount of magnetic flux leaking from the magnetic grid is detected using a Hall element (5) or the like.

FIG. 3 is a graph showing the detected magnetic flux amount (Hall element output), with the horizontal axis representing the displacement amount and the vertical axis representing the magnetic flux amount (Hall element output). Therefore, by arbitrarily selecting the spacing of the magnetic lattice formed on the substrate by irradiating the beam, and using an excitation magnet and an element for detecting the amount of magnetic flux, such as a Hall element, as shown in Fig. 3, The relationship between the amount of displacement and the amount of residual magnetization is changed as shown, and displacement can be detected. Further, in this method, since a magnetic layer is formed in a non-magnetic substrate, the magnetic flux is detected in a pulsed manner as shown in FIG. 3, which is more stable than the conventional method and has extremely high detection sensitivity.

In addition, the Curie point of ferrite, which exhibits magnetism, is approximately 700°C.
It has excellent heat resistance.

In addition, in the above example, a CO2 laser was used, but YA
A laser other than a G laser, an electron beam, or another high energy density heat source such as plasma may be used.

In the above embodiment, one example of the beam irradiation conditions is shown, and it goes without saying that various conditions can be selected.

Further, in the above embodiment, stainless steel 5US304 or 5US410 was used as the substrate (11), but other non-magnetic austenitic stainless steel, such as 5US31
It goes without saying that it may be made of 6.5 US 309 or other ferromagnetic steel, and that the shape may be other shapes such as a cylinder or columnar shape such as a pipe.

Furthermore, in the above embodiment, the excitation magnet (4) and an element that detects the amount of magnetic flux, such as a Hall element (5), are used for detection, but as shown in the side configuration diagram of FIG. Even if the magnetic scale is pre-magnetized by a magnetic electromagnet (15) and the amount of magnetization remaining in the magnetic scale is detected by a sensor such as a Hall element, as shown in the perspective view of FIG. A relationship between the amount of displacement and the amount of detected magnetic flux similar to that shown in FIG. 3 is obtained, making it possible to detect displacement.

[Effects of the Invention] As described above, according to the present invention, a non-magnetic austenitic stainless steel is superimposed on a ferromagnetic steel, and both are heated at a desired interval from the austenitic stainless steel side using a high energy density heat source. At least a part of the austenitic stainless steel and ferromagnetic steel in the heated part is melted and solidified to precipitate magnetic ferrite to form a magnetic lattice, so even when used in high temperature ranges, there is no problem with characteristic deterioration. This has the effect of producing a problem-free magnetic scale that has good detection sensitivity and a high signal-to-noise ratio.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a method of manufacturing a magnetic scale according to an embodiment of the present invention, and FIG. 2 is a side configuration diagram showing how a displacement amount is detected using a magnetic scale according to an embodiment of the present invention. Figure 3 shows the amount of magnetic flux (
A graph showing the relationship between the Hall element output (Hall element output) and the amount of displacement, FIG. 4 is a side configuration diagram showing how a magnetic scale according to another embodiment of the present invention is magnetized, and FIG. FIG. 6 is a perspective view showing how a displacement amount is detected using a magnetic scale according to an embodiment, and FIG. 6 is a cross-sectional view showing a conventional magnetic scale. In the figure, (1) is ferromagnetic steel, (2) is non-magnetic austenitic stainless steel, (3) is the heating part, (20
) is a high energy density heat source. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A non-magnetic austenitic stainless steel is layered on a ferromagnetic steel, and both are heated at desired intervals from the austenitic stainless steel side using a high energy density heat source, and at least one of the austenitic stainless steel and the ferromagnetic steel in the heated portion is heated. A method of manufacturing a magnetic scale in which a magnetic ferrite is precipitated by melting and solidifying the parts to form a magnetic lattice.