JPH04174302A - Detection of displacement of moving member - Google Patents

Abstract

PURPOSE:To correctly determine the displacement by a method wherein the intensity of signals is read simultaneously from two or more amorphous layers (reference scales), and the intensity of signals is successively changed to the displacement from a reference position. CONSTITUTION:When a laser beam is cast to a cylindrical member 1, the surface area ratio of a heating part is changed thereby to change the magnetic properties and/or the electric conductivity. A pattern of a reference scale 6 at this time is obtained. Moreover, a pattern of the reference scale 6 so formed as to monotonously increase or decrease the magnetic permeability and/or the electric conductivity of a processing part when the surface area ratio and/or the volumetric ratio of the heating part and a non-heating part is changed in the direction of the displacement of the member 1 is read by a detecting coil 7. At this time, the electromagnetic properties are read simultaneously from two or more reference scales 6. The relative displacement movement is determined from the read value of the intensity of signals and the relationship between the intensity of signals and the relative displacement movement determined in advance, so that the analog displacement of the member 1 to be detected is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detection method for detecting the position and/or moving speed of a moving member.

[Conventional technology]

In a displacement detection device that detects the position of a moving member and stops its movement when the moving member reaches a set position, the surface of a metal material is A standard is formed by heat-treating the metal material and locally creating a magnetically altered part at a predetermined position on the surface of the metal material. A device that detects relative displacement with a detector is disclosed in Japanese Patent Publication No. 62-32407.

As shown in FIG. 12, a standard scale is formed by providing several magnetically altered parts 10 at regular intervals on the surface of the piston 9, and the displacement of this standard scale is measured by the magnetic detector 11.
Detect with. That is, when the magnetically altered portion 1O comes to a position facing the magnetic detector 11, the magnetic detector 11 detects it and sends a signal to a braking device (not shown). This braking device measures how many magnetically altered portions 10 are located on the magnetic detector 1 from the reference position.
The piston 9 is stopped by detecting whether the piston 1 has passed,
Alternatively, the moving speed of the piston is controlled by the magnetic detector 11 measuring the time it takes to pass between the magnetically altered parts 10.

[Problem to be solved by the invention]

However, in the conventional method, where the position at which the moving member was displaced from the reference position was determined based on the magnetically altered parts detected by the magnetic detector, that is, the number of standards, the distance between one standard and the next standard could be reduced. Otherwise, the accurate displacement position cannot be measured.

Furthermore, if the interval between the standards is made smaller, the detection area of the detector that detects it must be made smaller. It is very difficult to reduce the detection area of the detector, and there are problems such as a decrease in the measurement accuracy of the displacement position.

An object of the present invention is to more accurately measure the displaced position of a member and the speed at which the member is displaced without complicating the device.

In the past, the signal level was read in a pulse-like (discontinuous) manner, but the present invention aims to solve the above-mentioned problems by reading the signal level continuously, that is, in an analog manner. shall be.

[Means to solve the problem]

In the present invention, the above-mentioned problem was solved using the following means. In other words, it consists of an object to be detected on which standards with varying magnetic permeability and/or conductivity are intermittently formed on the surface in the direction of displacement, and an electromagnetic sensor that detects electromagnetic characteristics facing the object to be detected. In the displacement detection method of detecting the relative displacement movement between the object to be detected and the electromagnetic sensor by detecting the reference standard with the electromagnetic sensor, the surface area ratio and/or volume ratio of the heated part and the non-heated part are determined. The magnetic permeability and/or
Or, when an electromagnetic sensor reads a pattern of standard standards made so that the conductivity monotonically increases or decreases, the electromagnetic characteristics are read simultaneously from two or more standard standards,
The displacement of the object to be detected is detected in an analog manner by determining the relative displacement movement from the relationship between the signal intensity value read at this time, the signal intensity determined in advance, and the relative displacement movement.

[Effect]

By reading the signal intensities from two or more standards at the same time, the signal intensities can be continuously changed with respect to the displacement from the reference position.

In addition, since a standard pattern is provided so that the position of the component can be determined in accordance with the signal strength value, the displacement of the component can be linearly determined simply by reading the signal strength value at that position. can be determined accurately.

Furthermore, the speed at which the member is displaced can be similarly accurately determined by measuring the time during which the member is displaced.

〔Example〕

(First Example) As shown in Fig. 3, alloy powder 2, which becomes amorphous by rapid solidification, was placed on the surface of a cylindrical member 1 made of steel (SUS304) with an outer diameter of 38 mm in a width of 5 mm and a thickness of 2 mm. . The composition of this alloy powder is Feb.

L, 8at%5i-17at%B.

Next, as shown in Fig. 3, a C02 laser 3 is applied onto the alloy powder.
was irradiated, and the laser was scanned in the length direction of the disposed powder to weld the powder onto the base material 1, thereby forming the built-up layer 4. The laser irradiation conditions at this time are as follows.

Laser beam: A laser beam was focused to a diameter of 2 mm using a condenser lens, and was shaped using a beam oscillator to have a width of 5 mm.

Laser power: 2.5 Kw Laser scanning speed: 200 mm/min The surface of the overlay layer 4 was ground to a thickness of 0.6 mm.

As shown in FIG. 3, YAG laser 5 was irradiated in a spot on the processed overlay layer 4 to form an amorphous layer 6.

The YAG laser irradiation conditions at this time are as follows.

Laser beam l: Condenses light into a size of φ2m, m using a condensing lens.

Discharge voltage: 440V Pulse width: 0.5mS As shown in Figure 5, the irradiation interval of the amorphous spot is interval a, that is, 0.1m at the pattern start position in the detection direction X.
m, 2.0 mm at the pattern end position, and increases from the start position to the end position at the middle surface.

In addition, in the interval, that is, in the direction Y perpendicular to the detection direction, the irradiation interval of the amorphous spots was set to a constant 0.3 mm.

FIG. 1 shows a schematic diagram of signal detection by a detection coil 7 from the amorphous layer/crystalline layer pattern produced by the above method. A circuit diagram illustrating the displacement detection circuit shown in FIG. 1 in more detail is shown in FIG.

The displacement detection method will be described below using the circuit diagram shown in FIG.

First, an oscillation circuit applies a 2 MHz excitation current to the coil 7.
supply to. The excitation current supplied to the coil 7 generates a magnetic field around the coil 7, and this magnetic field generates a distribution of magnetic flux density around the object to be detected.

A voltage is generated in the coil 7 due to this magnetic flux density.

The pulsating voltage generated in the coil 7 was made into a constant voltage by a smoothing circuit, and amplified by an amplifier circuit to obtain signal strength (V).

Note that since the generated magnetic flux density increases in proportion to the value of magnetic permeability of the detected object, the voltage generated in the coil also increases, and the signal strength (v) is determined.

The amount of displacement was detected from the relationship between the signal strength (V) input in advance and the amount of displacement in a comparison detection circuit.

Further, the size of the coil used for detection was 5 mm in diameter.

The detection results are shown in FIG. In the method according to the present invention, the signal intensity changes continuously according to the surface area ratio of the heated portion and the non-heated portion, and the position and speed can be detected by reading the signal intensity (voltage).

(Second Example) Steel material (SUS30
Instead of 4), a two-layer stainless steel (SUS329J1) made of ferrite austenite was used, and a YAG laser was directly irradiated under the same conditions as in the first example without forming a built-up layer on this base material to form the pattern of the standard. Created.
The metal structure of the non-laser irradiated area is a mixed structure of ferrite and austenite, but the laser irradiated area has a structure of only ferrite.

This change in structure results in a change in magnetic permeability and/or electrical conductivity. This change is detected by an electromagnetic sensor.

FIG. 7 shows the results of detecting an object with the sensor under the same conditions as in the first embodiment.

At this time, as in the first embodiment, the signal intensity monotonically decreases as the amount of displacement of the detected object from the reference position increases. Therefore, it can be detected in an analog manner.

In addition, in the case of the method of the second embodiment, the labor of forming a build-up layer is saved, and the cost is reduced when manufacturing a displacement detector, but the method using a build-up layer is better when it becomes amorphous. Since it is possible to use a material whose properties change more easily, it is easier to accurately measure the displacement of a non-detecting object.

(Third Example) In the first and second examples, a pattern of a standard in which the magnetic properties and/or conductivity are changed by changing the surface area ratio of the heated part by irradiating the member with a laser beam is created. On the other hand, in the third embodiment, the standard pattern was created by changing the volume ratio instead of the surface area ratio.

The specific method will be described below.

A built-up layer was formed on the surface of the cylindrical member in the same manner as in the first example, and after processing, the output of the YAG laser was changed to change the depth of remelting. At this time, the melting depth was processed so that it became monotonically shallow in the longitudinal direction of the built-up layer.

Moreover, at this time, the volume of the amorphous layer is proportional to the melting depth.

The detection results are shown in FIG.

In the method according to this embodiment, the signal intensity changes continuously depending on the depth of the remelted layer. As in the second embodiment, the position and velocity can be detected in an analog manner by reading the signal strength.

Further, by changing both the surface area ratio and volume ratio of the heated portion, the signal intensity can be further changed.

In addition, as a method of creating a standard pattern with changed magnetic properties and/or electrical conductivity by changing the surface area ratio and/or volume ratio of the heated part by irradiating the member with a laser beam, there is a method shown in Fig. 8. As shown in Figure 9, the pitch of the laser spot can be changed only in the Y direction, that is, the direction perpendicular to the displacement direction, or as shown in Figure 9, the pitch of the laser spot can be changed in both the X and Y directions and in the displacement direction and the displacement direction. It can also be changed in the right angle direction, as shown in Figure 10.
Various methods other than this example can be considered, such as forming the heating layer linearly in a direction perpendicular to the displacement direction.

In addition to position detection in the circumferential direction, linear position detection and other one-dimensional displacement detection are also possible.

〔Effect of the invention〕

If you set up a standard pattern so that the signal strength can be changed continuously and the position of the component can be determined in accordance with the signal strength value, you can easily locate the component simply by reading the signal strength value at that position. Since the displacement can be determined linearly, the displacement can be determined accurately.

Furthermore, the speed at which the member is displaced can be similarly accurately measured.

[Brief explanation of drawings]

Fig. 1 is an external view of the signal detection according to the first embodiment of the present invention, Fig. 2 is a block diagram of the displacement detection circuit according to the first embodiment of the present invention, and Fig. 3 is a diagram showing the structure of the member according to the first embodiment of the present invention. Fig. 4 is an external view when forming a pattern of the standard according to the first embodiment of the present invention; Fig. 5 is an external view after forming the pattern of the standard according to the first embodiment of the present invention. , FIG. 6 is a graph showing the signal detection results according to the first embodiment of the present invention, FIG. 7 is a graph showing the signal detection results according to the second embodiment of the present invention, and FIGS. 8, 9, and 10 are the reference values. FIG. 11 is a graph showing the signal detection results according to the third embodiment of the present invention, and FIG. 12 is an explanatory diagram of the operation of the prior art. 1--Cylindrical member, 2--Alloy powder, 3-C
O, Laser, 4-Build-up layer, -YAG laser,
6-Amorphous layer, 7.-=detection coil, 8-Displacement detection circuit, a-.
- Displacement direction laser irradiation interval, b - Displacement direction and perpendicular direction laser irradiation interval, 9 - Piston, 1o - Magnetic alteration part, 11... Magnetic detector. Fig. 4 Se 0 諭 Station Fire 〉 Area Atsushi End ≧ Fig. 9 13 $o-Gou Bonito ≧

Claims (1)

[Claims] Consisting of an object to be detected on whose surface a standard with varying magnetic permeability and/or conductivity is formed intermittently in the direction of displacement, and an electromagnetic sensor that detects electromagnetic characteristics facing the object to be detected, In the displacement detection method of detecting the relative displacement movement between the object to be detected and the electromagnetic sensor by detecting the standard with an electromagnetic sensor, the surface area ratio and/or volume ratio occupied by the standard in the object to be detected is determined by When an electromagnetic sensor reads the pattern of a standard that is fabricated so that the magnetic permeability and/or conductivity of the treated section monotonically increases or decreases as it changes in the displacement direction, the electromagnetic characteristics can be detected simultaneously from two or more standards. The displacement of the object to be detected is detected in an analog manner by reading and converting the read signal intensity value into a relative displacement movement based on the relationship between a predetermined signal intensity and the relative displacement movement. A method for detecting displacement of a moving member.