JPH05223526A - Plate thickness measuring device - Google Patents

Abstract

PURPOSE:To eliminate the influence of a temperature and to measure a plate thickness with high accuracy by a method wherein the temperature is measured and calibrated in a noncontact-system plate thickness measuring apparatus. CONSTITUTION:In a measuring apparatus, both sides of a plate material 1 are irradiated with a light beam and a plate thickness is measured by using reflected light. In the measuring apparatus, the temperature of members 3, 4, 10 which support a measuring instrument, that of a specimen stand 5 and that of the outside air are measured, the deformation due to thermal expansion of each part is estimated, and its accurate plate thickness is presumed. Thereby, the plate thickness can be measured with high accuracy irrespective of a change in the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate material thickness measuring device, and more particularly to a measuring device suitable for measuring the thickness of a material of a plate spring used as a support spring of a magnetic head or the like.

[0002]

2. Description of the Related Art In bending a sheet metal such as a support spring of a magnetic head, which requires precision on the order of microns, an error in the thickness of a material has a great influence on the processing precision. for that reason,
As shown in U.S. Pat. No. 4,603,567, it is effective to measure the plate thickness of the material and control the forming conditions such as the bending angle according to the result in order to improve the processing accuracy.

A conventional plate thickness measuring device is disclosed in Japanese Patent Laid-Open No. Sho 62-62.
Some Japanese Patent Publication No. 245110 uses a combination of two displacement measuring devices. This displacement measuring device measures the position of a measurement object by irradiating a non-measurement object with laser light and observing the position of reflected light. Although the patent does not describe a method for measuring the plate thickness, in order to measure the plate thickness, such displacement measuring devices are installed on both sides of the plate material, and the plate material has a known plate thickness, A method of calculating the plate thickness of the non-measurement object based on the difference in displacement of the non-measurement object is generally used. Since this method can perform the measurement without contacting the sample, the plate thickness can be measured with high accuracy without an error due to the fluctuation of the contact pressure.

[0004]

In the plate thickness measuring device according to the above-mentioned prior art, when the thickness of the plate material is measured, if there is a temperature change, the frame or the sample table to which the measuring device is fixed is thermally expanded. Then, there was a change in the measured value. Therefore, in order to measure with high accuracy, the measurement had to be performed in a special room in which the temperature was controlled to be constant.

Therefore, the installation location of the measuring device is limited, for example, it cannot be installed on the production line, and it is used with low accuracy or is measured outside the line and the result is used as a control device for the production line. I had to do the complicated operation of inputting.

Further, in the spring forming device according to the US patent, the plate thickness measuring device is installed on the line, but the plate thickness measuring method and device are not described in detail. With this molding device, the molding conditions are changed according to the measurement results of the plate thickness, so although the molding accuracy has been improved to some extent, the required accuracy cannot be satisfied with one molding, and the molding accuracy cannot be met twice. Adjustments such as bending and unbending had to be made.

Therefore, an object of the present invention is to provide a plate thickness measuring instrument which can reduce deterioration of accuracy due to temperature change and can be used even in a place where temperature control is not carried out such as a production line.

Another object of the present invention is to install the above-mentioned plate thickness measuring instrument on a production line and measure the plate thickness on the line with high accuracy to perform highly accurate spring forming in a short time. It is to provide a molding device capable of performing the above.

[0009]

[Means for Solving the Problems] In order to prevent deterioration of accuracy due to temperature changes, the temperature of each part of the measuring instrument is measured, and the output value obtained from the plate thickness measuring instrument is corrected based on the result, Eliminates changes in measured values due to changes.

Further, in order to perform the spring forming with high accuracy in a short time, the plate thickness of the material is measured on the line by the plate thickness measuring device before the forming.

[0011]

By measuring the temperature and using the result to calibrate the plate thickness output, it is possible to eliminate the influence of expansion due to temperature changes and to perform highly accurate plate thickness measurement.

Further, a plate thickness measuring device capable of performing temperature correction can be provided on the plate spring forming line, and by changing the forming conditions according to the result, highly accurate spring forming can be performed in a short time. ..

[0013]

EXAMPLE An example of the present invention will be described with reference to FIG. 2 is a laser displacement meter for measuring the position of the plate 1,
Two are mounted on the frame 3 one above the other. Frame 3
Is attached to the base 10 by the stand 4.
Reference numeral 5 is a sample table on which the sample 1 is placed. 41 is a temperature sensor for measuring the temperature of each part of the measuring device.

Each laser displacement meter 2 can measure the distance between the displacement meter 2 and the sample 1. The method will be described with reference to FIG. Laser beam 21 from displacement meter 2 to sample 1
The reflected light 22a is received by irradiating the light with a certain angle. If the distance between the sample 1 and the displacement meter 2 is different, the reflected light will be 2
2b and the light receiving position changes. Therefore, the distance between the displacement meter 2 and the sample 1 can be known by measuring this light receiving position. In order to measure the plate thickness, the laser displacement meter 2 measures from both sides of the plate material 1. At this time, the plate thickness of the sample 1 can be calculated by the difference between the total value of the distances between the displacement meters 2 and the sample 1 and the case of the plate material for calibrating with a known plate thickness. The above calculation is performed by the dedicated arithmetic unit 31 shown in FIG.

According to this method, it is possible to perform the measurement with high accuracy when the temperature at which the plate material for calibration is measured is equal to that at the time when the sample is measured, but when the temperature is different, an error is generated as follows. Occurs.

First, when the temperature rises, the frame 3 expands as shown in FIG. 3, so that the laser displacement meters 2 are separated from each other, and the plate thickness apparently becomes small. The change is

[0017]

## EQU1 ## δ1 = αL (K−K0) α: coefficient of thermal expansion L: distance between sensor mounting positions K: temperature K0: temperature during calibration

There are also the following problems with the sample. The temperature is not constant in the measurement environment, and the laser displacement meter generates heat with respect to the outside air temperature, so the temperature is increased by 1 to several degrees. As a result, a temperature difference occurs on the frame and the stand. As for the temperature distribution, the portion in contact with the heat source of the displacement gauge has the highest temperature, and the temperature becomes lower as it approaches the base. Therefore, the expansion is large in the high temperature part and small in the low temperature part. For example, as shown in FIG. 4, when the stand 4 is deformed, the displacement gauge 2 is lifted and the frame 3 is tilted. In addition, at the tip of the frame, the position of each displacement meter moves or tilts depending on whether the position of the heat source is close to the outside or the inside. Further, depending on the surrounding environment, the sample table may be tilted, such as when the sample table is continuous with another device having a heat source. Or, if members with different thermal expansion coefficients are sandwiched in a continuous system consisting of a displacement meter, base, and sample stage,
Even if there is no temperature difference, the magnitude of expansion is different, so that the inclination and the relative position change. When the relative position changes, there is no problem if the distance between the displacement gauges does not change,
When the relative positions of the displacement gauges change, an error occurs due to the same principle as when the frame expands.

When the relative angle between the measuring instrument and the sample changes, the apparent plate thickness changes according to the following principle.

As shown in FIG. 5, when the sample 1 is tilted, the measurement is performed in a direction oblique to the plate thickness direction, so that the plate thickness is apparently increased. The error is

[0021]

## EQU00002 ## .delta.2 = T (1 / COS .theta.-1) T: true value of plate thickness .theta .: inclination.

Further, as shown in FIG. 6, if the laser beam and the bisecting axis of the reflected light pass through the optical axis 23 of the measuring device, that is, the measuring point, the upper measuring point and the lower measuring point are tilted. Since the vertical displacement differs, an error occurs. The error is

[0023]

## EQU00003 ## .delta.3 = DSIN (.theta.) D: deviation of the optical axis.

Therefore, the error of the output value due to the temperature change is
It is expressed as follows.

[0025]

Δ = δ1 + δ2 + δ3 = T (1 / COSθ-1) + DSIN (θ) + αL (K-K0) where θ is a function of temperature, the heat source is only a laser displacement meter, and the same material is used for each member. If you are using

[0026]

(5) θ = a (K−K0) a: can be approximated to a constant.

Therefore, using the measured value and the temperature, the plate thickness is expressed as follows.

[0028]

[Equation 6] T = Tm-δ (K, K0) Tm: Thickness output by calculator δ (K, K0): Function peculiar to the measurement system due to temperature When multiple heat sources are used or different materials are used In this case, the expression should be polynomial accordingly.

As shown in FIG. 1, the output of the laser displacement meter 2 is taken into the calculator 31 at one end, and the plate thickness is calculated from the light receiving position. This value includes an error due to temperature. On the other hand, the output of the temperature sensor is captured by the temperature measuring device 42. The output of the plate thickness calculator 31 and the output of the temperature measuring device 42 are transferred to the personal computer 32, and the correction value by the temperature of the plate thickness is calculated by the above formula.

According to this embodiment, by correcting the change in the output of the plate thickness measuring device due to the temperature change, it is possible to measure the plate thickness with high accuracy without being affected by the temperature.

Next, another embodiment of the present invention will be described. In the above example, the temperature was measured at all points where the temperature could be different. The number of measurement points can be reduced by estimating the temperature at other positions by measuring the temperature at two locations. For example, the temperature distribution of the frame or the stand is estimated by measuring the temperature near the light source which is a heat source and the outside air temperature. This temperature distribution can be theoretically obtained if the heat transfer coefficient of each member and the exact position of the heat source are known, but if the shape is complicated, it is obtained by experiment, and at the time of use, prediction is made based on the experimental results. To do.

According to this embodiment, it is possible to reduce the number of temperature measurement points, and at a minimum, it is sufficient to measure the temperature of the heat source or its vicinity and the temperature of the base or the outside air. Therefore, it is possible to predict the deformation due to temperature by estimating the temperature even in a place where it is difficult to attach the temperature sensor.

In yet another embodiment according to the present invention,
The temperature of either the outside air or the heat source is measured, and the temperature of the other is predicted by the change of the temperature with time. In this case, if the temperature change of the heat source causes the change of the outside temperature,
If changes in the outside air temperature cause changes in the temperature of the heat source, measure the outside air temperature. If the heat source is only a displacement gauge, the temperature difference between the displacement gauge and the outside air is at most several degrees, and there is no temperature change due to the displacement gauge itself except when the equipment is started up. Good. Since the time for heat transfer is required for the measured temperature, the other temperature changes with a delay. This delay is predicted by the degree of temperature change over time. In this embodiment, the number of measuring points can be further reduced.

The above embodiments are shown for a single measuring instrument. The measuring instrument according to the above-described embodiment can perform plate thickness measurement with high accuracy without being affected by temperature changes, and thus can be used on a production line where temperature control is not performed.

When high precision is required for the bending work such as the support spring of the magnetic head, the variation of the plate thickness greatly affects the working precision. Therefore, by measuring the plate thickness and changing the molding conditions such as the bending angle, the bending start position, and the pressing force based on the measured value, it is possible to reduce the variation of the molded product due to the variation of the plate thickness.

In such a production facility, the lead time can be shortened by allowing the front and rear processes to flow on the same line and concentrate them in a close place. However, if various processes are concentrated in one place, temperature control becomes difficult. According to the invention. With a temperature-compensated thickness gauge,
Even under such an environment, the plate thickness can be measured with high accuracy.

In order to use the plate thickness measuring device in the spring forming line, as shown in FIG. 7, a sample stand is provided on the conveying line 51 in front of the forming machine, and the measuring device is inserted in the conveying line. Install. In this case, since the air layers are blocked above and below the transport line 51, the outside air temperature is measured above and below. Also, on both sides of the frame 3 of the measuring instrument, air
Since it is difficult to flow, it is preferable to install the temperature sensors 41 at a total of four places on both sides of the frame 3. However, if there is no difference in the temperature of the outside air at these four locations, it may be two or one. By changing the forming conditions such as the bending angle in the spring forming using the plate thickness measured by this measuring device, it is possible to eliminate the dispersion of the molded product due to the dispersion of the plate thickness and perform highly accurate spring forming.

According to this embodiment, it is possible to measure the plate thickness with high accuracy on a line where the temperature is not controlled,
Spring molding can be performed with high precision in a short time.

[0039]

According to the present invention, the temperature is measured, and the plate thickness is calculated based on the result of the measurement, so that the plate thickness can be measured with high accuracy by eliminating the influence of the expansion of the measuring instrument due to the temperature change. You can

Further, by providing the plate thickness measuring device according to the present invention on the plate spring forming line, it becomes possible to change the forming conditions based on the plate thickness measured with high accuracy, and to shorten the time. With this, it becomes possible to perform highly accurate spring forming.

[Brief description of drawings]

FIG. 1 is a view showing a plate thickness measuring device according to the present invention.

FIG. 2 is a diagram showing a displacement measuring method of a plate thickness measuring instrument according to the present invention.

FIG. 3 is an explanatory diagram of a measurement error due to expansion of a frame.

FIG. 4 is a diagram showing a tilt due to thermal deformation of a measuring instrument.

FIG. 5 is an explanatory diagram of a measurement error due to a change in relative angle between the measuring device and the sample.

FIG. 6 is an explanatory diagram of a measurement error due to a change in relative angle between the measuring device and the sample.

FIG. 7 is a schematic diagram when the measuring instrument is used on a production line.

[Explanation of symbols]

1 ... Sample, 2 ... Displacement meter, 3 ... Frame, 23 ... Optical axis, 4
1 ... Temperature sensor.

Continuation of the front page (72) Inventor Yasuyuki Nakajima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd.

Claims (5)

[Claims] 1. In a measuring device for detecting the thickness of a plate material by shining light from both sides of the plate material, the temperature is measured at at least two positions of a member supporting the measuring device, and the result is the result of the measured plate thickness. A plate thickness measuring device characterized in that 2. The plate thickness measuring device according to claim 1, wherein the temperature of at least two places is measured and the temperature of other parts is measured. 3. A measuring device for detecting the thickness of a plate material by shining light from both sides of the plate material, by measuring the temperature at at least one position of a member supporting the measuring device and predicting the temperature of other parts. A plate thickness measuring device characterized by changing the result of the plate thickness measured according to the result. 4. The plate thickness measuring device according to claim 1, wherein the plate thickness measuring device has a portion continuous with the plastic working device for sheet metal. 5. A plastic working apparatus for sheet metal, which has a portion continuous with the sheet thickness measuring apparatus according to claim 1, and changes the working conditions based on a result of measuring the sheet thickness.