JPS6052701A - Displacement measuring device - Google Patents

Abstract

PURPOSE:To use effectively an eddy current-type sensor even in a region where its precision is low by operating an NC table on a basis of the output of the eddy-current-type sensor so that the length between an object to be measured and the eddy current-type sensor before displacement of the object to be measured is equal to that after displacement of the object to be measured. CONSTITUTION:A sensor 1 detects the extent of gap between the sensor 1 and the object to be measured in a case 9 and sends an electric output corresponding to this extent to an amplifier 7. This amplified output is stored in a holding circuit 10 as an initial gap extent by an initial data taking-in timing signal. In this state, the object to be measured is displaced by a length DELTAl. A comparator 11 discriminates whether this DELTAl is in the positive direction or the negative direction. A displacement measuring part 12 determines the moving direction of a sensor head on a basis of this output and transmits it to a driving control part 5 of the sensor head. A driving means of an NC table 2 moves a table 3 in the positive or negative direction on a basis of the command of the control part 5. When the length between the object 8 to be measured and the sensor 1 is equal to that before displacement, the NC table is stopped.

Description

[Detailed Description of the Invention] [Technical Field] The purpose of the present invention is to measure, for example, the amount of movement of a relay contact spring housed in a membrane-retaining case made of an insulating material such as acrylic resin from outside the case. This invention relates to a non-contact displacement measuring device used in

[Background technology]

To measure the amount of displacement of an object housed in a case, such as a relay contact spring, it is necessary to use a non-contact measuring device that can measure displacement without touching the object. However, many optical types have opaque cases, so they cannot be used generally and are expensive. Ultrasonic types are also expensive and unsuitable for measuring minute quantities.

If an eddy current sensor is used, the above problems do not occur. Eddy current sensors include, for example, high frequency oscillation circuits,
This is a high-wavelength sensor that includes a detection circuit consisting of a detection circuit, a waveform detection circuit, and an output circuit, and uses the oscillation coil of the oscillation circuit as a detection head. This works, for example, as follows.

When there is no conductor such as a metal body near the head, there is a constant oscillation state, but when the head approaches a conductor, eddy currents are generated inside the four electric bodies by induction due to the magnetic field lines of the oscillation coil, resulting in oscillation. The resistance of the coil increases and the output changes. By utilizing this output change, the amount of displacement of a conductor such as a relay contact spring can be measured in a non-contact manner. However, the single eddy current sensor has the following problems.

■ The distance that can be measured by an eddy current sensor is approximately the same as the sensor diameter, and the smaller the object to be measured, the greater the distance, the lower the sensitivity becomes.
/N ratio deteriorates, and measurement accuracy also deteriorates.

(2) For this reason, highly accurate measurement results can be obtained at most 1 to 2 πm, and the accuracy deteriorates when the distance is greater than that. When measuring from outside the retainer, such as measuring the displacement of a relay contact spring, an eddy current sensor is used to measure the IJ.
Since high-precision measurement must be performed at a distance several times (approximately 1 to 5 times) the distance at which a good linearity can be obtained, measuring the amount using only an eddy current sensor has poor accuracy and is not practical.

(2) Measurement using only a vortex flow sensor is inconvenient because the output value changes depending on the material, shape, and positional relationship of the object to be measured, and requires calibration and positional accuracy (alignment).

[Object of the Invention] An object of the present invention is to provide a displacement measuring device that uses an eddy current sensor and does not cause the above-mentioned problems.

[Disclosure of the invention]

In order to achieve the above object, the present invention includes an eddy current sensor, an NC table for moving the eddy current sensor in one direction, and means for measuring the amount of movement of the NC table. Based on the output of the eddy current type sensor, the measured object and the eddy current type are measured before and after the displacement of the measured object.

The gist is a displacement measuring device that operates so that the distances between the sensors are the same. One embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the displacement side measuring device for the emitted J is equipped with an eddy current sensor and an NC doublet 2. The NC table 2 includes a table 3, a wind movement 4 that moves the table in a certain direction indicated by an arrow, and a control section 5 that controls this drive section. is supported. In the figure, 7 is an amplifier that amplifies the output of the sensor l.

Although not shown, the drive unit 4 has a built-in movement measuring means for determining the linear movement amount of the table 3 in the arrow direction VC (therefore, the movement amount of the sensor 1). As the transfer amount measuring means, it is preferable to use a linear scale, a pulse motor, or one that can provide positive and negative electrical outputs in accordance with the linear movement of the transnat table 3. This is because if it is an electrical output, it becomes possible to immediately display the distance r~2') as the shipboard value. However, the present invention is not limited to means for emitting such electrical output.

A block diagram (Figure 2) showing the system configuration of the above device and a time chart (Figure 3) showing the operation over time.
Based on this displacement, the RB operation (iT) of the 11 constant device is as follows. As shown in FIG. 1, the eddy current sensor 1 and the object to be measured 8 are made to face each other. ,
Set the object to be measured. In this example, the object to be measured is a relay contact spring housed in an insulating protection case 79. It goes without saying that the relay contact spring 8 is placed within the range of the sensing capability of the sensor l. The output is sent to the amplifier 7 VC.This output, signal amplified by the amplifier circuit, is stored as an initial gap amount in the hold circuit 10 by the initial data acquisition timing signal.In this state, the object to be measured is displaced by a distance Δe. Along with this displacement, the output of sensor 1 changes as shown in Figure 3.
There is a positive displacement that moves away from the sensor l, and a negative displacement that approaches the sensor l. In FIG. 3, the displacement is in the negative direction. l- Therefore, the comparator 11 determines whether this Δl is in the positive direction or in the negative direction by comparing the memory amount of the hold circuit 10 and the output amount of the sensor amplifier 7. In FIG. 3, it is determined to be negative. Since the output of the comparator 11 is taken into the displacement measuring section 12, the displacement measuring section 12 determines the moving direction of the sensor head based on this output, and uses this determination as a Nuttat command to the oscillation control section of the sensor head, that is, the NC table 2. The information is transmitted to the control unit 5. The drive s4 of the NC table moves the table 3 in the positive direction or the negative direction based on a command from the control unit 50. In Figure @3, it is moved in the positive direction. As a result, the absolute value of the output of sensor l gradually decreases as shown in FIG. Then, when the initial value is reached and matches the output of the hold circuit IO, the output of the comparator 11 becomes zero, and the output signal causes the displacement measuring section 12 to control the control section 5 to stop. That is, when the distance between the object to be measured 8 and the sensor l becomes the same value as the distance before displacement due to the movement of the NC table, N
C table will stop.

Along with the driving of the NC table, the linear scale $NC
The movement amount measuring means of the table 2 begins to output, and the output value gradually increases as shown in FIG. Then, when the out signal is issued as described above and the movement of the NC table is stopped, the output value issued by the movement amount measuring means is taken into the displacement measuring section 12, and fi1 is set as the displacement amount Δl of the object to be measured.
It will be displayed for a fixed period of time.

Here, when the distance between the measured object and the sensor becomes the same value,
This includes the case where the output value of the sensor matches when multiplied by U.

The method of processing various signals, the mechanism of the NC table, and the configuration of the electric circuit are not limited to those of the embodiments described above.

〔Effect of the invention〕

A displacement measuring device according to the present invention includes an eddy current sensor;
An NC table for moving this eddy current sensor in one direction and a means for measuring the amount of movement of this NC table are provided, and the NC table is configured to move the eddy current sensor in one direction. The eddy current sensor operates so that the distance between the object to be measured and the eddy current sensor is the same before and after the object is displaced. Since it is only used as a sensor for controlling the NC table, it can be effectively used even in areas where the accuracy of eddy current sensors is poor. In other words, since the eddy current sensor is used as a detector in a feedback control system that operates to keep the sensor head and the constant 'IQ distance f - constant, the following effects will occur. Even if the distance exceeds twice the normal detectable distance of the eddy-electric IE sensor, it is easy to determine the displacement of a minute object.

(Compared to optical n1x1j and ultrasonic measurement, the same
It is relatively inexpensive.

■ If you try to align the origin every time, the position of the object to be measured and the sensor is incorrect! No determining consistency is required.

(Since it is a method that does not depend on the AI detection characteristic curve,
Calibration based on the interest rate, shape, etc. of the constant object becomes unnecessary.

[Brief explanation of drawings]

Figure 1 is a perspective view of one embodiment of the displacement measuring device according to the present invention, Figure 2 is a block diagram of the same device, and Figure 3 is a timing chart of the same. 1...HRB IT flow type sensor 2...NC table 8...Measurement object representative Patent attorney Medical doctor Takehiko Hiraitodaji i1'ijJ three concave: (spontaneous) 7°1. thing 1'1
Indication of Showa [1158 Patent Application No. 160955 2, name of the invention Displacement measuring device 3 The connection between the dial and the skewer 111 (Series Patent use 1 head person (J place Dai IHf 1048 Kadoma, Kadoma City) street name
Name (583) Representative of Matsushita Electric Works Co., Ltd. Representative Iku Kobayashi 4, Agent name (7346) Patent attorney Takehiko Matsumoto 5, Number of inventions increased by amendment Contents of amendment (1, 1 Seiwa Iwa No. 7 Summer lines 11, O, and 19 read "udo" and correct it to "output J and 8j.

Claims (3)

[Claims] (1) Each includes an eddy current sensor, an NC table for moving the eddy current sensor in one direction, and means for measuring the amount of movement of the NC table, and the NC table is configured to move the eddy current sensor in one direction. A displacement measuring device that operates based on the output so that the distance between the measured object and the eddy current sensor is the same before and after the measured object is displaced. (2) The displacement measuring device according to claim 1, wherein the means for measuring the amount of movement of the NC table is a linear scale. (3) The displacement device according to claim 1, wherein the means for measuring the amount of movement of the NC table is a torque motor.