JPH0676894B2 - Magnetic scale - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic scale.

[Prior art]

Magnetic scales are widely used in industry, but one conventional example is a ferromagnetic base material with a width of 1-2 mm and a depth of 0.2 mm.
Or, grooves of 0.3 mm were provided at equal intervals by machining, and these grooves were filled with nonmagnetic chrome or the like. Here, the plating thickness is usually about 0.02 mm, and when plating the groove, a beard is generated at the corner that is the contact point between the side surface of the groove and the outer surface of the base material, and this beard interferes with the next plating. Therefore, it was removed by a buff. If the groove depth is 0.2 mm, this complicated plating process is repeated 10 times, which requires a lot of time and raises the cost.

As another conventional example, there is a method in which a non-magnetic base material is plated with nickel containing phosphorus and the surface plated layer is irradiated with laser light at equal intervals and heated to about 300 ° C. to change nickel into ferromagnetic. With this method, the entire surface of the base material is plated, so there is no need for plating as in the first conventional example, but the thickness of the plated layer is 0.2 mm due to the adhesion of the layer and productivity.
Is the limit. On the other hand, since the electric output generated from the detector of the magnetic scale is proportional to the thickness of the plating layer, it is impossible to greatly increase the electric output. Furthermore, in these methods, part of the plating layer is heated to make it ferromagnetic, so if the magnetic scale is heated due to frictional heat or mechanical failure, the characteristics, especially the electrical output, will decrease. However, there is a drawback that it becomes unusable especially near 300 ° C. and the range of use is limited.

[Object of the Invention]

The present invention eliminates such drawbacks and its purpose is to
An object of the present invention is to provide a magnetic scale that is low in cost, has a large electric output of a detector, is more heat resistant, and has a wide range of use.

[Main points of the invention]

The magnetic scale of the present invention has a thin film formed on a surface of a base material having a magnetic permeability of about 2000 by nickel plating or chrome plating or thermal spraying of an alloy containing nickel, chrome, manganese, and carbon, and a predetermined outer periphery of the thin film. The thin film and the base material are heated and melted and solidified within a short time by irradiating a laser beam or arc discharge while maintaining the interval of the half-moon shape or U-shape which is regularly arranged on the surface layer part of the base material. It is characterized in that a non-magnetic alteration portion having a cross section of 1 is provided.

Example of Invention

1 and 2 showing one embodiment of the present invention will be described below. In FIG. 1, a thin film 12 made of nickel such as chromium or manganese or carbon is formed by plating or thermal spraying on the surface of a base material 11 having a cylindrical shape and having a ferromagnetic property (permeability of about 2000). This thin film 12 is laser beam from the outside.
When the base material 11 and a part of the thin film 12 are heated and melted by irradiating 13, the metal forming the thin film 12 and the metal forming the base material 11 are fused to form a half-moon shape or a U shape. A non-magnetic (permeability of about 2) altered portion 14A having a V-shaped cross section is formed. At this time, when the base material 11 is rotated, the altered portion 14A becomes a ring-shaped altered portion 14, and if the laser beam 13 is further irradiated at predetermined intervals in the axial direction, the base material 11 has a plurality of ring-like altered portions. 14 are formed.

In order to form the non-magnetic altered portion 14 in this manner, the metal contained in the altered portion 14 may be made to be a region component of a stable austenite structure as shown in the diagram of the structure of the Jeefler. Therefore, when the base material 11 contains a large amount of nickel, chromium, manganese, or the like, it is preferable to select the metal component of the thin film 12 corresponding to the component of the base material 11.

Next, the shape in which the thin film 12 on the outer periphery of the base material 11 is removed by grinding or the like is shown in FIG.
The surface layer portions 11A and the non-magnetic alteration portions 14 are arranged alternately with the same width and pitch. When the detector 21 is installed close to the magnetic scale 16 and moved in the horizontal direction in the figure, the detector 21 detects the ferromagnetism of the surface layer 11A and the non-magnetism of the altered layer 14, and The displacement amount is measured by emitting an electric signal corresponding to the portion 11A and the altered portion 14, that is, an electric signal corresponding to the displacement amount in the left-right direction.

An example of the details of the detector 21 will be described with reference to FIGS. Inside the main body 22 of the detector 21, a U-shaped permanent magnet is arranged at the same intervals with respect to the pitch between the surface layer 11A and the altered portion 14.
23 is inserted, and two magnetoresistive elements (hereinafter simply referred to as elements) 24 having a slight length are provided between both end surfaces of the permanent magnet 23 and the surface of the main body 22. This element 24 is a kind of electric resistor and has a property that the electric resistance increases in proportion to the number of magnetic lines of force passing through the element.

Therefore, as shown in FIG. 3, when there is a surface layer portion 11A that is ferromagnetic and has a high magnetic permeability immediately before both elements 24, many magnetic force lines of the permanent magnet 23 pass through the course 26 and both element 24 pass. Therefore, the resistance value increases. On the other hand, as shown in FIG. 4, if there is a non-magnetic and low-permeability altered portion 14 immediately in front of both elements 24, the magnetic lines of force of the permanent magnet 23 pass through the course 27 and almost no magnetic lines of force pass through both elements 24. The resistance value is small.

As shown in FIG. 5, when the two elements 24 are connected in series with the resistor 28 to the power supply 29, the voltage E between the two elements 24 is
When 24 resistance is high, it is high, and when resistance is low, it is low. Therefore, the output voltage E of the detector 21 changes corresponding to the relative displacement amount between the magnetic scale 16 and the detector 21, and if this is converted by an electric calculator (not shown), the relative displacement amount, relative velocity and relative Acceleration is measured.

Example 1. After forming a thin film 12 by plating 0.03 mm of nickel on the surface of a steel material (SUS420J2) as a base material 11, an output of 1.6 kW and a beam diameter of 1.3 while rotating the base material 11 at a speed of 2 m / min. The thin film 12 was irradiated with a carbon dioxide laser of mm, and the thin film 12 was removed to obtain the magnetic scale 16 shown in FIG. In this case steel (SU
Since S420J2) contains a large amount of chrome (13 ωt%), the thin film 12 was achieved by simple nickel plating.

Example 2 In the magnetic scale 31, as a base material 32, a thin film 33 was formed on the surface of a steel material (S48C) by multi-layer plating of 0.03 mm thick nickel plating and 0.02 mm thick chrome plating. /
While rotating at a speed of a minute, a carbon dioxide gas laser with an output of 2 kW and a beam diameter of 1.3 mm was irradiated to further remove the thin film 33. Alteration part
The dimensions of 34 were 1 mm and 0.3 mm as in Example 1.

Example 3 In this example, the magnetic scale itself is a mechanical part, which requires high wear resistance on the surface.
As shown in FIG. 6, in the magnetic scale 36, as the base material 32, 65 ωt %% of nickel and 20 ω of chrome was formed on the surface of steel (S48C).
A self-fluxing alloy of t%, silicon 10ωt% and boron 5ωt% is baked by thermal spraying to a thickness of 0.2 mm to form a thin film 37, and then the base material 32 is rotated at a speed of 15 m / min and an output of 2 kW beam diameter of 1.3 mm After irradiating with carbon dioxide laser, thin film 37 on the outer periphery
Grind with leaving 0.01 mm. In this case, the dimensions X and Y of the altered portion 38 were 1 mm and 0.5 mm, respectively.

Example 4 In this example, the magnetic scale 31 shown in Example 2 was used in a die casting machine, and one example thereof is shown in FIGS. 7 and 8. A cavity 44 is formed on the facing surface of the fixed die 42 fixed to the fixed die plate 41 and the movable die 43 fixed to the moving die plate (not shown), and the fixed die plate 41 and the fixed die 42 are formed. Barrel 45 is attached to and.
The molten metal 46 injected into the barrel 45 is pressed into the cavity 44 by the forward movement (leftward movement) of the plunger 47 to become a molded product.

Here, in order to obtain a high-quality molded product, it is necessary to control the press-fitting state of the molten metal 46 into the cavity 44, that is, the movement of the plunger 47. Therefore, the piston rod 49 of the hydraulic cylinder 48 for moving the plunger 47 is provided with the magnetic scale 31 integral with the piston rod 49. Reference numeral 51 is a frame for fixing the hydraulic cylinder 48 to the fixed die plate 41, and 52 is a plunger 47.
Is a coupling for connecting the piston rod 49 with the piston rod 49, and 53 is a lid on one side of the hydraulic cylinder 48.

In such a configuration, the movement of the plunger 47, that is, the piston rod 49 is detected via the detector 21, and the output signal thereof is sent to a control device (not shown) to control the movement of the plunger 47. In this case, the moving speed of the plunger 47 is as high as 2 to 3 m / sec, and when the molten metal 46 is completely pressed into the cavity 44, the plunger 47 is rapidly stopped and the deceleration at that time reaches 50 G.

In the above description, the altered portion has a ring shape, but it is possible to form the base material into a flat surface such as a plate to form a linear altered portion on the surface. Further, in the above description, the width of the altered portion was 1 mm in each case, but it can be increased or decreased according to the purpose of use by changing the beam diameter of the laser beam. Further, although the altered portion and the surface layer portion are described as being arranged at a constant interval, the position can be detected by forming the altered portion and the surface layer portion into a bar code shape.

Embodiment 5 In the first to third embodiments described above, the heat source for the altered portion was a laser beam, but in this example, a positive inert gas tungsten arc welding device (hereinafter TIG) having a particularly large weld penetration depth. Is used). 9th
As shown in the figure, when the ferromagnetic base material 61 and the thin film 62 such as nickel plating are used as an anode and the electrode 64 of the torch 63 is used as a cathode to perform arc discharge between the two electrodes, the thin film 62 and a part of the base material 61 are formed. Is dissolved to form a non-magnetic altered portion 65 as in the other embodiments described above. In this case, since the TIG supplies a large amount of heat energy in a concentrated manner, the dimensions W and G of the altered portion 65 are large values of 2 to 3 mm and 1.5 to 2 mm, respectively. The base material 61 and the altered portion 65 become a magnetic scale (not shown) by grinding the outer periphery and removing the thin film 62.

The fifth embodiment described above is suitable for a large magnetic scale or the positioning device shown in FIG. In FIG. 9, a detector 72 such as a reed switch, which detects non-magnetism in the vicinity of the magnetic scale 71, is attached to the support body 73.
When either 71 or the detector 72 is moved in the direction of the arrow 74, relative displacement occurs between the two, and when the altered portion 65 faces the detector 72, an electric signal is emitted from the detector 72 to measure the position. It Thus, in this example, the magnetic scale 71
Can be easily provided on a flat surface or a cylindrical surface of a machine device component, and the positioning device can be downsized as compared with the conventional method using a limit switch and a dog.

〔The invention's effect〕

As described above, the magnetic scale of the present invention is conventionally provided with a large number of grooves or the like by machining a ferromagnetic base material and non-magnetic plating is applied to the grooves or the like to remove a beard generated during plating. The cost was high due to the large number of platings. On the other hand, in the present invention, the entire surface of the ferromagnetic base material is subjected to plating and heat treatment is performed with a laser beam or the like to form the non-magnetic altered portion, so that the cost is drastically reduced.

Further, in the conventional example, when the temperature rises, the characteristics such as electric output and heat resistance are remarkably deteriorated, but since the non-magnetic alteration portion of the present invention has a stable austenite structure, the electric output and heat resistance are high even if the temperature rises. Does not deteriorate the characteristics. Furthermore, in the conventional scale, the arm is attached to the moving body by attaching it to the moving body, so it easily breaks down when a large acceleration is applied, resulting in a powerful mechanism that increases the cost and deteriorates the operability. According to the invention, since the moving body itself can be a magnetic scale, it has many advantages such as no failure even with a large acceleration. In addition to these, in the present invention, the thickness of the non-magnetic alteration portion can be increased by using arc discharge or the like, and there is an advantage that the detector output is increased and the SN ratio is improved.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a sectional view during processing, FIG. 2 is a sectional view at the end of processing, and FIGS. 3 and 4 are different time points of a detector. 5 is a sectional view of the detector, FIG. 5 is a sectional view of the detector, FIG. 6 is a sectional view of another embodiment of the present invention, and FIGS. 7 and 8 are examples of using the magnetic scale of the present invention in a die casting machine. 7 is a longitudinal sectional view, FIG. 8 is a sectional view taken along line 8-8 of FIG. 7, FIG. 9 is a sectional view during processing in another embodiment of the present invention, and FIG. 10 is a sectional view of the present invention. It is sectional drawing of an example which used the magnetic scale for the positioning device. 11 ・ 32 ・ 61 …… Base material, 12 ・ 32 ・ 62 …… Thin film, 13 …… Laser beam,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-51-99557 (JP, A) “NIKKEI MECHANICAL (1985.20.1985)” P. 53 “Steel Materials Handbook” (published by Maruzen, June 30, 1942) 636-P. 638 Edited by C.I. R. Clay tom, C.I. M. Prece "Corrion of Metals Precessed by Directed Energy Beams" (1982) Heat treatment. 17 [3] (Showa 52-6) Corporate Law Association Japan Heat Treatment Technology Association P. 131 Figure 2

Claims (1)

[Claims] 1. A thin film is formed on the surface of a base material made of steel having a magnetic permeability of about 2000 by nickel plating or chrome plating or thermal spraying of an alloy containing nickel, chrome, manganese, and carbon, and a predetermined interval is provided on the outer periphery of the thin film. The thin film and the base material are heated by being irradiated with a laser beam or arc discharge to melt and solidify within a short time, and a half-moon or U-shaped cross section is regularly arranged on the surface layer of the base material. A magnetic scale characterized in that a non-magnetic alteration portion having a magnetic field is provided.