JPS588442B2 - Laser displacement measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a displacement measuring device using a laser, and in particular, two gratings are provided facing each other so that their relative positions change in response to changes in the dimensions of an object to be measured. A laser device and a light receiving device are arranged so that the grating is located on the passing line of the grating. Convert the pulse to the number of occurrences of
It is a displacement measurement device using a laser that counts and displays the value using a counter.More specifically, it is used to maintain the atmosphere at an ultra-high vacuum or ultra-high pressure, or to use substances such as helium that require strict purity control. A laser that can accurately and easily measure various heat-resistant materials such as molybdenum and niobium that easily react with trace elements in the gas, or radioactive materials from a remote location in a sealed container filled with active gas. Provides a device for measuring displacement.

In general, displacement measurement devices used in material testing include measurement devices using various methods such as mechanical methods, optical force methods, and electrical methods. Most of them are in use.

For example, a dial gauge is commonly used as a mechanical measuring device, a differential transformer is an electrical measuring device, and a Martens extensometer is commonly used as an optical measuring device. This is one of the most representative devices.

However, these extensometers, such as dial gauges, differential transformers, and Martens extensometers, which attempt to continuously measure the deformation of a certain part of an object under a load, are based on their respective operating principles. Due to the constraints, the measurement conditions are severely limited, making it difficult to measure under a wide range of conditions.

In particular, it is unsuitable for measurements with high precision at high temperatures, and furthermore, when measuring radioactive materials, measurements from safe remote locations are very difficult.

If these devices are to be used, they must have a very complicated structure, be difficult to handle, have high manufacturing costs, and be very uneconomical.

Furthermore, elongation measurement using complicated equipment such as mechanical methods is
Since oil attached to these devices and components of device materials are liberated into the atmosphere, it is difficult to form a highly pure atmosphere.

Furthermore, devices using electrical methods have problems with stability over long-term measurements.

Therefore, the inventors developed a new method to measure the deformation of the object to be measured inside the heating device using a combination of a laser and Moiré interference fringes, thereby improving the optical and electrical systems of the device. The aim was to simplify and improve measurement accuracy.

However, in this case, in order to use a grating to generate moiré interference fringes, it is necessary to prevent the grating from being deformed by heat.

Further, in particular, it is difficult to use a laser by a simple method, for example, the transmitted power method, at the position of the object to be measured.

This inventor came up with this invention in view of such problems.

That is, according to the present invention, remote measurement is easy, elongation can be measured with high precision even under high temperatures, and elongation can be measured with high accuracy even when the object to be measured has radioactivity that is extremely harmful to the human body. Can be measured safely.

In addition, it has a simple structure, does not emit substances that pollute the atmosphere, and does not react with the atmosphere, can perform highly accurate measurements for a long time, is easy to handle, and is cheaper and more economical than conventional devices. This is a displacement measurement device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a displacement measuring means that has a simple structure, is easy to handle, and can perform highly accurate measurements. It is an object of the present invention to provide a displacement measuring device that can perform measurements with high accuracy and safety even if the object to be measured is contaminated with radioactivity that is extremely harmful to the human body. An object of the invention is to provide a displacement measuring device that can accurately and safely measure the displacement of a special object such as a nuclear reactor material. It is an object of the present invention to provide a method and means that can maintain a highly pure atmosphere without introducing foreign substances into the atmosphere required for the measurement target. It is an object of the present invention to provide a method and apparatus for measuring displacement using a laser, which can perform stable and precise measurements continuously over a long period of time by obtaining resolution, and which is inexpensive and economical to manufacture. The purpose of the invention is to provide a displacement measuring device using a laser that can be applied without any problems even in high temperature, high pressure systems, ultra-high vacuum systems, etc., where elongation measurement has been extremely difficult in the past. It is in.

That is, as shown in the accompanying drawings and described later in detail by way of example as preferred embodiments, the present invention is characterized in that the atmosphere is maintained at an ultra-high vacuum or ultra-high pressure, or is filled with an inert gas. In the airtight container 8, shoulders 1 are placed at certain points and other points on the object 1 to be measured.
4 and 15 are fixed, connecting members 16 and 17 are connected to each shoulder 14 and 15, respectively, and each connecting member 16 and 1
7 is configured such that the gratings 2 and 3 are fixedly connected to each other, and the gratings 2 and 3 are opposed to each other so that the relative position of the gratings 2 and 3 changes based on the displacement of the measurement object 1. The laser device 5 is placed so that the gratings 2 and 3 are located on the laser passing line 4.
On the back side of the gratings 2 and 3, a light receiving device 6 that receives the laser beam and converts the change in the relative position of the gratings 2 and 3 into a pulse is disposed. The present invention relates to a displacement determination device using a laser, which is characterized in that the lasers are connected to each other.

The following is a helium atmosphere in which a radioactive measurement object is tested in a sealed container filled with or flowing helium gas and made of a material with excellent heat resistance or radiation resistance. An embodiment of the present invention applied to a high-temperature creep tester in the interior will be described in detail.

Here, creep refers to a phenomenon in which the deformation of a material increases over time when a constant load is applied at a constant temperature, and a high-temperature creep tester measures the resistance of a material to creep in a high temperature range, or the creep A test device that measures temperatures that allow for

The principle of applying a load to the object to be measured using the tester in this embodiment is the same as that of a commonly used tensile creep tester, and the object to be measured 1 is attached to a locking tool 10 fixed to the main body 9 of the tester. One end is locked to the movable locking tool 11 and the other end is locked to the movable locking tool 11.
Further, a constant tensile load is applied by a loading device 12 via the movable locking device 11.

Furthermore, in addition to the loading device 12, a heating device 13 is provided in the vicinity of the object to be measured 1.
3, the measurement object 1 is heated and maintained at a constant temperature.

Therefore, the measurement target 1 and the locking tool 1 that holds it
A jig such as No. 0 is heated to a high temperature of about 1100°C.

However, if the object to be measured is a nuclear reactor material, it is
Under an atmosphere similar to the helium atmosphere found in nuclear reactors,
In addition, since it is held in a closed container 8 made of a material with excellent heat resistance such as quartz or radiation resistance such as alumina, it can be tested under conditions similar to those in actual use.

Under conditions similar to this ideal actual usage condition, the shoulders 14.15 are tightened and the connecting members 16.17 are tightened at a certain point and another point on the object 1, that is, at the gage position. One force connects the shoulder 14, the connecting member 16, and the grating 2, and the other force connects the silarda 15 and the connecting member 17.
and grating 3 are connected fixedly and individually.

Furthermore, both gratings 2 and 3 are configured to face each other so that their relative positions change based on changes in the elongation of the measurement object 1 due to creep.

Furthermore, both gratings 2 and 3 are configured to be located between a laser device 5 that emits a laser beam and a light receiving device 6 that receives the laser beam, and on the passing line 4 of the laser beam. .

In addition, the light receiving device 6 converts the opening and closing of the laser trajectory caused by the movement of moiré interference fringes due to changes in the relative positions of the gratings 2 and 3 into the number of electrical pulses generated and communicates this to the counter 7. The number of electrical pulses sent by I is counted and directly displayed digitally.

This display method is of course not limited to direct digital display, but may also be analog display.

This testing machine includes a loading device 11 that applies a constant load to the object to be measured 1, a heating device 12 that keeps the object to be measured 1 at a constant temperature, and a heat-resistant or radiation-resistant member. A closed container 8 filled with or made to circulate helium gas, a shoulder 14.15, and a connecting member 16,1.
7 and gratings 2 and 3, an extensometer 18 that expresses a change in the elongation of the measurement object 1 by the amount of displacement in the relative position of both gratings 2 and 3, and a laser device 5 that emits a laser;
It consists of a light receiving device 6 that receives the emitted laser beam, and a counter 7 that counts the electric pulses sent from the light receiving device 6 and directly displays them digitally.

Furthermore, the principle of determination of this tester is as follows.

Both gratings 2 and 3 are each formed with a scale 19 having the same line thickness and the same interval between lines, and a plurality of lines arranged in parallel. They are provided facing each other so that their relative positions change based on changes in elongation.

Therefore, when the measurement object 1 undergoes creep elongation, this change in elongation appears as a change in the relative position of both gratings 2 and 3, resulting in an overlap between the scales 19 and 19 formed on both gratings. The laser beam 4 is alternately shifted to block or open the laser passing line 4.

The operation of overlapping and misaligning the scales is and is cuts off and opens the laser, so the light receiving device 6 can detect the blinking of the laser, that is, the opening and closing operation on the laser passing line 4, as a pulse of light. .

Furthermore, the light receiving device 6 converts the light pulses into electrical pulses and sends the electrical pulses to the counter 7, which counts the number of pulses and directly displays them digitally to continue measurement while aiming at the elongation value. can do.

Therefore, by appropriately selecting and combining the thickness of the scale 19 and the size of the interval, the accuracy of this tester can be set arbitrarily.

For example, if the thickness and interval of the scale 19 are each 5μ, then 10
The elongation of μ can be detected.

That is, in this case, the accuracy is 10 microns.

Furthermore, the thickness and interval of the scale 19 may be finely adjusted, or the interval between overlapping gratings may be adjusted to 10%, 1%, or 1% of the above-mentioned accuracy.
By reducing it to 0.1% or the like, even more precise measurements are possible, and theoretically the precision can be increased infinitely.

Furthermore, since this tester is a closed container 8 filled with or made to flow with helium gas, view ports 20 and 20 are formed in the portion of the main body through which the laser passes.

These viewports 20, 20 must be made of quartz plates or the like that have low light diffusion and good transmittance, and the displacement of the gratings 2, 3 can be measured from these viewports 20, 20 using an optical measuring device or the like. You can also continue directly.

Figures 2 and 3 show extensometers.

Convex portions 21 and 22 each having a conical cross section are formed at a certain point and another point of the measurement object 1, that is, at a gauge point.
, 22, respectively, and tighten the shoulders 14 and 15 to the connecting member 1.
Gratings 2 and 3 are fixedly provided facing each other via 6 and 17.

More specifically, the shoulders 14 and 15 have a cross shape, and furthermore, this cross shape is made up of two T-shaped members 23, and the center point where the tops 24 of the T-shaped members 23 are butted against each other. recesses 25 respectively engaging projections 21 and 22 in the
, 26 are formed.

Furthermore, the T-shaped member 23 has connection holes 27 . 28, and when in use, the tops of the two T-shaped members 23 are butted against each other to form the convex portions 2.
1.22 and are attached, and are fixed to the connecting members 16 and 17, respectively.

Therefore, the two connecting members 16 are attached to the single shoulder 14.
, 16, and the two connecting members 1 are also connected to the shoulders of other forces.
7.17 are connected, and these connecting members 16 and 17 are arranged at appropriate angles so as not to overlap each other.

Furthermore, the connecting members 16 and 17 are disposed along the circumferential surface of the extensometer main body 29 having a cylindrical outer circumference, and one of the connecting members 1
Reference numeral 6 is fixedly connected to a grating holding member 27 with one force, and the other connecting member 17 is fixedly connected with a holding member 28 with another force, respectively, by tightening members 30 such as screws. Gratings 2 and 3 are fixedly installed facing each other.

Furthermore, these gratings 2 and 3 and the holding member 2
The gratings 7 and 2B are housed in a housing portion 31 formed in the extensometer main body 29 and are regulated by a guide member 32, so that the gratings 2 and 3 are configured to slide without separating from each other. There is.

Reference numeral 33 denotes a screw for adjusting the angle of the single force grating, and the angle of the grating 2 can be adjusted in an arc shape with the fulcrum member 34 as the center.

Although a weight type loading device is used as the loading device, it goes without saying that other loading devices may be used.

Although one embodiment has been described above in detail with reference to the accompanying drawings, various other embodiments may be adopted.

For example, in addition to helium, an inert gas such as argon, nitrogen, or the like may be used as the atmosphere that requires strict purity control.

In addition, grating scales are usually constructed in the form of a lattice stripe by overlapping vertical and horizontal stripes at an appropriate angle, but there are other ways to form lattice stripes diagonally or by adjusting the spacing between the scales proportionally. It is possible to use various forms such as increasing or decreasing the number of particles.

Furthermore, by connecting this device to a vacuum evacuation system, it goes without saying that it can be used as a high-vacuum creep tester.

As described above, according to the present invention, the structure of the device is simple and easy to handle without using a complicated optical lens system, etc., and it is possible to perform highly accurate measurements. Even if the object to be measured contains radioactivity that is extremely harmful to the human body, it can be measured with high precision and safely.

Furthermore, stable and precise measurements can be carried out continuously over a long period of time, and a highly pure atmosphere can be maintained without any influence such as the mixing of foreign substances into the atmosphere.

Furthermore, it is not only possible to accurately and safely measure objects such as special heat-resistant materials such as molybdenum and niobium, but it is also economical with low manufacturing costs, and it has been extremely difficult to measure elongation in the past. It is possible to provide a displacement measurement device using a laser that can be applied without any problems even in conventional high-temperature, high-pressure systems, ultra-high vacuum systems, and the like.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic diagram for explanatory purposes, FIG. 2 is a front view of the extensometer, and FIG.
FIG. 4 is an enlarged sectional view taken along line B-B in the figure. In the figure, 1 is an object to be measured, 2 and 3 are gratings, 4 is a laser passing line, 5 is a laser device, 6 is a light receiving device, 7 is a counter, and 8 is a sealed container.

Claims (1)

[Claims] 1. In a closed container in which the atmosphere is maintained at an excessive vacuum or ultra-high pressure, or filled with an inert gas, shoulders are fixed at one point and another point on the object to be measured, and each shoulder is The connecting members are connected to each other, and each connecting member is connected to a grating in a fixed manner, and both gratings are made to face each other so that the relative position of both gratings changes based on the displacement of the object to be measured. a laser device and a light receiving device on the back side of the grating that receives the laser and converts a change in the relative position of the grating into a pulse so that the grating is located on the laser passing line. 1. A displacement measuring device using a laser, further comprising a counter connected to a light receiving device.