JPS6118402Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic inner diameter sorting device for glass tubes, particularly thick-walled glass tubes used in the oscillation section of a He--Ne laser oscillator.

The inner diameter of the glass tube used for the above purpose, which is manufactured from components with the same outer diameter and the same refractive index, greatly affects the performance such as the output power of the oscillator body, so the inner diameter of the sample is ranked in units of 10 μm. It is necessary to distinguish the applicable oscillator model for each rank. For this reason, the conventional method has been to prepare a group of metal pin gauges whose outer diameter values are rank classification values, and to set the upper and lower limits of the inner diameter value of the sample glass tube based on whether each pin gauge can be inserted into the sample. However, the above measurement method using a pin gauge has disadvantages in that the measurement work must be done entirely by the operator, resulting in poor working efficiency and large artificial differences in measurement values, resulting in a decrease in accuracy. Additionally, there was a problem in that the production and maintenance of pin gauges used as measurement standards required extreme care.

In view of the drawbacks of conventional measuring methods, the apparatus according to the present invention aims to perform automatic inner diameter measurement and sorting using a method that enables high-accuracy and high-speed measurement.

This device uses a laser oscillator, a tuning fork deflector, and an optical system to scan a micro-diameter laser spot, and a position where the laser beam is focused by the lens effect of the thick part of the sample glass tube placed within the scanning range. Processing of a light receiving element arranged in the sample glass tube rotation drive mechanism, the rotation drive motor, a microprocessor that adjusts the rotation speed of the motor, and performs A/D conversion of the output of the laser scanning system, etc. A glass tube inner diameter sorting device is characterized in that it comprises a control means.

Next, we will explain the measurement principle used in this device in the first place.
This will be explained using FIGS. 2, 3, and 4.

FIG. 1 is a diagram showing the principle of a laser scanning system conventionally used for measuring the outer diameter of an opaque cylindrical object. When the laser spot emitted from the laser oscillator 1 and scanned at high speed by the tuning fork deflector 2 is cut off by an opaque object, the output level of the photoelectric element 3 decreases.

Therefore, when the output level of the photoelectric element is observed on the time axis as shown in FIG. 2, the time difference T between the output change points can be calculated backward. However, this principle cannot be directly applied to the glass tube that is the object of measurement in the present invention. This is because the sample itself is translucent.
This is because a lens effect is exerted on the laser beam, causing it to deviate completely from the optical path as shown in FIG. Here, a more detailed study of the optical path of the scanning beam after it enters the sample glass tube results in the following.

In Fig. 3, first, for the group of rays A11 that exit the sample without hitting the inner wall after entering the sample, the glass tube exerts the effect of a spherical lens with radius r, so that one point S on the optical axis Focus the light on ₁ . next,
After entering the sample, the group of rays B12 passes through the air layer in the tube, enters the sample again, and exits, and is focused at a point _S2 different from _S1 by refraction on the four spherical surfaces.
Finally, among the light rays that hit the inner wall after entering the sample, the C group 13 whose incident angle θ is greater than or equal to the critical angle θc is focused on a point S ₃ that is far away from S ₁ and S ₂ .
Therefore, if a minute photoelectric element is placed at the position shown by _S1 in Figure 3, the output waveform of the photoelectric element during laser scanning will be as shown in Figure 4, and the waveform between the level change points _P1 and _P2 will be From the time difference t, the outer diameter value D ₀ , and the refractive index n, the inner diameter value when viewed from the laser traveling direction can be calculated. However, although the above explanation assumes that the centers of the outer diameter and inner diameter of the sample are coincident, in actual samples, there is often an amount of eccentricity. Therefore, in the device according to the present invention, the measurement error due to the amount of eccentricity is corrected by taking the average value of the data measured from the opposite side.

Next, an embodiment of the present invention will be described using FIGS. 5 and 6.

FIG. 5 is an external perspective view of one embodiment of the present invention, which includes a mechanism section 20 consisting of a laser scanning system and a sample rotation drive mechanism section, processing means such as an electric circuit and a microprocessor, and an operation display panel. It is composed of a control section 21. The sample 22 is placed between rubber-lined rollers 23 and 24, and when the operator presses the start switch 25, the pulse motor rotates at a constant speed.

FIG. 6 shows a cross-sectional view of the sample rotation drive mechanism,
The pulse motor rotates through each shaft 26, 27, 2.
The rollers 23, 24 are transmitted to rotate in opposite directions through gears 30, 31, 32 attached to the rollers 8. Therefore, the sample 22 placed between the rollers 23 and 24 rotates due to friction with the rollers. Here, the output of one scan of the laser scanning system is input into the microprocessor every time t ₀ required for the sample to rotate 45 degrees, and the inner diameter value d ₀ is calculated from the time difference t shown in FIG. After performing the above measurement a total of 8 times and obtaining d ₀ , d ₁ , ... d ₇ , a processing means such as a microprocessor generates eccentricity-corrected inner diameter value data D ₀ , D ₁ , D ₂ , Calculate _D3 .

Di = di + di + 4/2 (i = _{0, 1, 2, 3) The sample inner diameter value is the maximum value or minimum value among D 0} , D ₁ , D ₂ , D ₃ or the 4th value from D ₀ to D ₃
It is decided in advance which one of the average values of the above data is to be used, and the representative value D of the inner diameter is determined by a processing means such as a microprocessor and displayed numerically on a 7-segment LED. Determine and display whether it is ranked. After the measurement is completed, the motor is stopped, the operator replaces the sample, and then performs the measurement again.

As described above, in the glass tube inner diameter sorting apparatus according to the present invention, the only thing the operator has to do is to load and unload the sample onto and from the roller, which greatly reduces the work effort. In addition, the measurement was performed using approximately 1 sample.
Measurement time can be shortened because only the time required for rotation is required.

Furthermore, regarding the accuracy and reliability of the data, in the explanation of the above example, it was assumed that the representative value was calculated from four sets of data with measurement directions separated by 45 degrees, but the scanning speed of the laser scanning system can be up to about 500Hz. Therefore, data can be taken in at very small angles, and highly accurate and reliable measurement and selection can be performed without a significant increase in measurement time.

[Brief explanation of the drawing]

Figure 1 is a principle diagram of a conventional laser scanning system for outer diameter measurement, Figure 2 is a diagram of the output waveform of the photoelectric element, Figure 3 is a diagram explaining the principle of the present invention, and Figure 4 is the output during measurement in the present invention. FIG. 5 is a perspective view of an embodiment of the present invention, and FIG. 6 is an explanatory diagram of the rotational drive mechanism. Each symbol in the figure indicates the following. 1... Laser oscillator, 2... Tuning fork deflector, 3...
...Photoelectric element, 4...Object to be measured, 11, 12, 13
...Light ray trajectory, 20...Mechanism section, 21...Control section, 22...Sample glass tube, 23, 24...Rubber lining, 25...Start switch, 26,
27, 28...shaft, 30, 31, 32...
gear.

Claims (1)

[Scope of utility model registration request] a micro-diameter laser spot scanning section, a light receiving element arranged at a position where the laser beam is focused by the lens effect of the thick part of the sample glass tube placed within the scanning range, a sample glass tube rotation drive mechanism, and the above-mentioned rotation. The device includes a drive motor, an electric circuit that adjusts the rotational speed of the motor and A/D converts the output of the laser scanning system, and means that processes data output from the circuit. A glass tube inner diameter sorting device characterized by: