JPH0721472B2 - Displacement measuring device for hot ceramics - Google Patents

Description

TECHNICAL FIELD The present invention mainly relates to a laser displacement measuring device for measuring the displacement of ceramics at a high temperature (for example, the coefficient of linear thermal expansion (hereinafter referred to as thermal expansion coefficient) or the amount of creep deformation). The present invention relates to a hot-displacement measuring device for ceramics, which automatically measures with high accuracy in a non-contact manner.

Prior art The coefficient of thermal expansion of fine ceramics, refractories, ceramics, glass or ceramics such as composite materials of these and metals, especially the coefficient of thermal expansion of refractories is the expansion of refractory linings of kilns used hot It is a very important characteristic that serves as a guide for decision making.

As prior arts, the title of the invention is "thermal expansion coefficient measuring device" (JP-A-60-39540), the title of the invention is "displacement measuring device during hot of ceramics, etc." (JP-A-61-7452), The title of the invention is "a device for measuring the displacement of ceramics or the like during heat" (JP-A-61-172041).

As an example of these, the "thermal expansion coefficient measuring device" of JP-A-60-39540 is shown in FIG. This thermal expansion coefficient measuring device incorporates a solid-state scanning light-receiving element, and combines two sets of displacement measuring devices each consisting of a camera 9 combined with a lens system 8 and a camera control unit 10 and an illuminating device 4 to automatically measure the displacement of a sample. It is a measure to measure. The displacement of the sample 2 in the heating furnace 1 is illuminated by the illuminating device 4 from the direction perpendicular to the axis of the sample 2, and the dark part in which the light is blocked by the sample 2 and the bright part in which the light directly reaches reach the solid scanning light receiving element surface. Then, the image is enlarged and projected by the telephoto lens 8 and the displacement is measured from the ratio of the bright portion and the dark portion.

In this case, the outputs of the respective camera control units 10 are added and output as a digital output signal according to the displacement.

This output and the digital output signal of the digital thermometer 6 are input to the computer 13 via the interface 12,
A memory operation is performed and the relationship between the temperature and the coefficient of thermal expansion is written in a graph by the digital plotter 14.

However, in this method, the measurement range of one camera 9 is about 3 mm when the measurement resolution is 1 μm. In addition, in order to improve the measurement accuracy, two cameras 9 are used for measurement.
When arranged side by side, the center of the camera is 80 mm and the sample size is 80 mm.
Only the above can be measured.

Recently, along with the development of fine ceramics and the like, measurement with a small sample has been demanded. To cope with this, attach the prism 15 to the tip of the camera 9 as shown in FIG. 6, or
As described in "Hot Displacement Measuring Device for Ceramics and the Like" in JP-A-61-172041, the camera 9 is opposed to measure a sample of 80 mm or less. However, the resolution of the solid-state scanning light-receiving element camera 9 is limited to 1 μm, and since a small sample has a small expansion amount, a resolution on the order of submicrons has recently been required.

Further, since the measuring range of one of the cameras 9 using the solid-state scanning light receiving element is about 3 mm, there is a problem that a sample that abnormally expands or a sample that greatly contracts cannot be measured.

Means for Solving the Problems The gist of the present invention is to provide a laser scanning system in which a laser transmitting section of a laser displacement measuring device is arranged on one side of a sample heating furnace and a laser receiving section is arranged on the opposite side. , The measurement window of the sample heating furnace has a wedge-shaped cross-section glass, the wedge-shaped cross-section angle is configured symmetrically on both sides of the heating furnace, the display that digitally displays the voltage signal of the laser receiving part, the sample temperature is measured Digital thermometer, a personal computer that stores and calculates the temperature and voltage signals of the sample through an interface between the digital output signal of the display and the digital output signal of the digital thermometer, and a curve display of the relationship between the temperature and the coefficient of thermal expansion An apparatus for measuring a displacement of ceramics during hot is provided with a digital plotter.

A specific example in which the hot displacement measuring device for ceramics of the present invention is applied to a thermal expansion measuring device will be described in detail with reference to FIG.

As a method for accurately measuring the displacement of a small-sized sample with a resolution of the submicron order, a measurement window (quartz glass) 19 is provided at both ends of a furnace core tube 21 that supports the sample 2 in the heating furnace 1, and the furnace core is provided. The tube 21 is made airtight, and an exhaust port 22 and a gas inlet 23 are provided at both ends of the furnace core tube 21 so that the displacement of the sample 2 can be measured in various atmospheres.

The displacement of sample 2 is a measurement window (quartz glass) with a wedge-shaped cross section attached to the openings of both ends of the furnace core tube 21 as shown in FIG.
The laser transmitting unit 16 of the laser displacement measuring device is arranged on one side of the laser displacement measuring device 19, and the laser receiving unit 17 is disposed on the measurement window (quartz glass) 19 on the opposite side.
Is installed, and the sample 2 is moved horizontally from the laser transmitter 16 at a constant speed.
When a laser beam is emitted by scanning with a width greater than or equal to the length, when the laser beam is cut off by the sample 2, no voltage signal is generated in the laser light receiving portion 17 as shown in FIG. 2A,
When the laser beam deviates from the sample, a voltage signal is generated like B. In the displacement measurement, the time when the laser beam is blocked by the sample 2, that is, the time of the voltage signal O of the laser receiving unit 17 is electrically measured with high accuracy, and the display 18
It is digitally displayed on and digital output signal is output. This output signal and digital temperature type 6 for measuring sample temperature
The digital output signal of is input to the personal computer 13 through the interface 12 to perform a memory operation,
The digital plotter 14 is made to write the relationship between the temperature and the coefficient of thermal expansion in a curve.

In the device of the present invention, the reason why the cross-sectional structure of the measurement windows (quartz glass 19) attached to the openings at both ends of the furnace core tube 21 is wedge-shaped is that when the cross section of the quartz glass is parallel, the laser beam is applied to the quartz glass surface. When the light is incident at a right angle, a part of the laser light is reflected inside the quartz glass, and the main laser light that directly passes through the quartz glass and reaches the laser receiving section 17 and is reflected inside the quartz glass, and is later than the main laser light in time. A laser beam enters the laser receiving section 17 and the length of the sample cannot be measured accurately.

By making the cross section of the quartz glass into a wedge shape, the laser light is made incident at an angle with respect to the quartz glass surface, so that the laser light reflected in the quartz glass is emitted outside the main optical path and is not made incident on the laser receiving section 17. By doing so, the measurement accuracy is improved.

If the angle of the wedge-shaped cross section of the quartz glass is too small, the desired effect is not obtained, but if it is too large, the positional relationship between the laser light transmitting portion and the laser light receiving portion, that is, centering becomes difficult. Therefore, the angle is preferably 1 to 5 degrees.

Further, the quartz glass is arranged such that the wedge-shaped cross-section angle of the quartz glass is symmetrically arranged on both sides of the heating furnace with respect to the laser optical axis as shown in FIG.

In addition, convection occurs in the furnace core tube due to temperature rise,
Fluctuations may occur in the laser light and the measurement accuracy may decrease. It is considered that convection occurs due to the difference in density due to the partial temperature difference of the atmospheric gas due to the temperature rise in the furnace core tube. It is preferable to reduce the volume of the furnace core tube and widen the isothermal zone, but as a countermeasure against this, it is preferable to make the inside of the furnace core tube airtight so that extra air does not come in and out.

In the measurement of normal pressure, it is preferable to discharge only the gas expansion due to the temperature rise in the furnace core tube from the discharge port.

The fluctuation of the laser beam can also be suppressed by discharging the atmospheric gas from the discharge port and reducing the pressure inside the furnace core tube.

In the measurement in a specific gas atmosphere, it is preferable to reduce the supply amount of the specific gas and replace it with a small amount.

By preventing the fluctuation of the laser beam by such as the above, highly accurate measurement becomes possible.

Example A quartz glass having a wedge-shaped cross-section angle of 2 degrees is arranged in a measuring window 19 of the device of the present invention shown in FIG. 1, and a heating furnace core tube 21 is made of an alumina sample and has a width of 10 mm, a height of 10 mm and a length. Set 40 mm and reduce the pressure to 10 ^-1 mmHg with vacuum pump 20 and measure range 0.5 to 55 m
m, the distance between the light-transmitting part 16 and the light-receiving part 17 is 700mm, and the temperature rise rate is 4 ℃ / min.
Figure 4 shows the results of taking in the data every 5 ° C and writing the relationship between the temperature and the coefficient of thermal expansion.

[Brief description of drawings]

FIG. 1 schematically shows an example of the device of the present invention, FIG. 2 shows a voltage symbol of a laser receiving portion, FIG. 3 shows an example of a sectional view of wedge-shaped glass, and FIG. 4 shows the device of the present invention. 5 shows an example of the measurement result according to FIG. 5, FIG. 5 schematically shows an example of a thermal expansion measuring device using a solid-state scanning light receiving element, and FIG. 6 schematically shows an example of a thermal expansion measuring device using a prism. Show. In the figure, 1: heating furnace, 2: sample, 3: heating element, 4: lighting device, 5: thermocouple, 6: digital thermometer, 7: filter, 8: telephoto lens, 9:
Solid-state scanning light receiving device camera, 10: control unit, 11:
Oscilloscope, 12: Interface, 13: Computer, 14: Digital plotter, 15: Prism, 16: Laser dimension measuring instrument, Laser transmitter, 17: Laser dimension measuring instrument, Laser receiver, 18: Display, 18: Measuring window, 20: Vacuum pump, 21: Furnace core tube, 22:
Exhaust port, 23: Gas inlet port, 24: Laser light.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-49-70649 (JP, A) JP-A-60-39540 (JP, A) JP-A-61-7452 (JP, A) JP-A-61- 172041 (JP, A) JP 60-231146 (JP, A) JP 53-36262 (JP, A) JP 50-30469 (JP, B2)

Claims (2)

[Claims] 1. A laser scanning system in which a laser transmitting section of a laser displacement measuring device is arranged on one side of a sample heating furnace and a laser receiving section is arranged on the opposite side, and a cross section of a measurement window glass of the sample heating furnace. Is a wedge-shaped glass, the wedge-shaped cross-section angle is configured symmetrically on both sides of the heating furnace, a display that digitally displays the voltage signal of the laser receiving part, a digital thermometer that measures the temperature of the sample, a digital output of the display A digital computer that stores and calculates a temperature and voltage signal of a sample through an interface between a signal and a digital output signal of the digital thermometer and a digital plotter that displays the relationship between the temperature and the thermal expansion coefficient in a curve. Displacement Measuring Device for Hot Ceramics. 2. A hot displacement measuring device for ceramics according to claim 1, wherein a furnace core tube is arranged in the sample heating furnace so that a vacuum atmosphere can be formed in the furnace core tube.