JPH09210622A - Method and device for measuring distance to high-temperature object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain even distance to a measurement object even if the measurement object emits light by increasing its temperature. SOLUTION: In a distance measurement method for measuring distance to a measurement object 7 by the triangulation method by projecting light to the measurement object 7 and receiving light reflected from the above measurement object 7, light projected to the measurement object 7 is light with a shorter wavelength than that of light emitted by the measurement object 7 whose temperature is increased to the extent for emitting light and light reflected from the measurement object 7 is passed through a filter for passing only the light with the above short wavelength and is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring method and apparatus for obtaining a distance to a high temperature object by a triangulation method.

[0002]

2. Description of the Related Art The inner wall of a vacuum chamber of an industrial furnace, for example, an RH degassing facility is covered with refractory material (brick), and this refractory material is directly exposed to molten steel and thus melts. If this amount of melting damage exceeds the limit, the iron shell, which is the outer wall of the vacuum chamber, becomes red-heated, and the iron shell also melts, which prevents stable operation.

Therefore, if the inside of the furnace is frequently monitored to detect the melting loss of the refractory material at an early stage, the temperature of the furnace is drastically lowered. Therefore, measurement in a high temperature state is required. Therefore, conventionally, a water-cooled observation tube has a built-in distance measuring device for measuring the distance to the refractory by a triangulation method, and the observation tube is inserted into a high-temperature vacuum chamber to move up and down in the furnace. A technique has been proposed in which the inner wall of the furnace is observed in a wide range by swirling and it is confirmed that there is no abnormality (see JP-A-1-145511).

The measurement principle of the triangulation method is as shown in FIG. The distance measuring device 30 includes a laser light source 31.
And a camera 32. Laser light is projected from the laser light source 31 to the refractory 33 that is the object to be measured, the reflected image from the refractory 33 is captured by the camera 32, and the refractory 33 is detected from the position 34 of the spot of the laser light reflected on the refractory 33. Find the distance to.

That is, the distance L to the refractory 33, which is the object to be measured, is calculated based on the following equation (1). L = (H + H0) tan θ (Equation 1) where H is the distance between the laser spot light 34 and the image center 36 in the image 35 captured by the camera 32, and H0 is the distance from the laser light source 31 to the camera 32. , Θ is the angle of the laser light projected from the laser light source 31 onto the refractory 33.

As the laser light source, generally,
He-Ne laser (red), laser diode (red)
Is used. Since these red laser light sources are small in size, they are suitable for being incorporated in the observation tube.

[0007]

However, the refractory, which is the object of measurement, glows red when it reaches a high temperature, and finally,
It emits visible light (red is dominant). Therefore,
In the above-mentioned conventional one, when the refractory material is at a high temperature, it becomes impossible to distinguish between the irradiated laser light and the light emitted by the measurement object.

That is, when the surface temperature of the refractory material 33 is relatively low (1100 ° C.), the scanning output waveform signal of the camera 32 becomes as shown in FIG. The intensity difference between the spontaneous emission light from the refractory 33 and the portion 38 is large, and the laser spot light can be easily identified. On the other hand, the surface temperature of the refractory 33 is 1200 ° C.
Then, the scanning output waveform signal of the camera 32 is as shown in FIG.
As shown in (b), the intensity of the portion 38 of the spontaneous emission light from the refractory 33 or the like is increased, and the portion 37 of the laser spot light is increased.
Is difficult to identify.

If the surface temperature distribution of the refractory material 33 is not uniform, it is difficult to identify whether the high light intensity portion is the high temperature portion or the laser spot light portion. Therefore, in view of such a situation, the present invention provides a distance measuring method and device capable of obtaining a distance to a measurement target even if the measurement target is heated and emits light. To aim.

The present invention also simplifies such a device.
The purpose is to enable miniaturization.

[0011]

According to the present invention, light is projected onto an object to be measured and light reflected from the object is received,
In the distance measuring method for measuring the distance to the object to be measured by the triangulation method, the following technical measures were taken to solve the above problems. That is, the light projected onto the measurement object is light having a shorter wavelength than the light emitted from the measurement object that has been heated to such a degree that it emits light, and the light reflected from the measurement object is the short wavelength light only. It is characterized in that the light is passed through a filter for passing light.

In this case, even if the object to be measured emits light due to high temperature, light having a shorter wavelength than that light is projected and only light having the shorter wavelength is received through the filter, so that it is projected onto the object to be measured. The emitted light is reliably discriminated without being buried in the light emitted from the measurement object. Further, the present invention, a hollow container having a cooling mechanism for keeping the inside at a low temperature is movably inserted into the furnace in the axial direction, and inside the container,
A light projecting system for projecting light on the inner wall of the furnace, and a light receiving unit provided at a position apart from the light projecting system in the axial direction of the container to receive reflected light reflected from the inner wall. Of a high-temperature object that is configured to obtain a vertical distance from the storage body to the inner wall based on a distance between the light projecting system and the light receiving unit and an inclination angle of light projected from the light projecting system. In the distance measuring device, the following technical measures have been taken to solve the above problems.

That is, the light projecting system is connected to a light source having a shorter wavelength than the light emitted from the inner wall, which has been heated to a temperature high enough to emit light, and only the light having the short wavelength is received from the light received by the light receiving section. It is characterized in that a filter for passing the light is provided. Further, according to the present invention, the light source of the light projecting system may be a laser light emitter which is connected to the light projecting system by an optical fiber and is provided outside the housing.

That is, in order to obtain the distance to the inner wall of the furnace by the triangulation method, it is necessary to insert the measuring unit into the furnace in a high temperature state. Therefore, the measuring unit is placed inside the container having the cooling mechanism. It is provided so that the inside of the container can be kept at a low temperature and measurement can be performed even at a high temperature. However, the red light is dominant in the light emitted from the inner wall of the furnace whose temperature has risen, and the light source that emits light of a shorter wavelength than that is large in size at present.

Therefore, it is difficult to incorporate such a light source in the container inserted into the furnace, which causes an increase in the size of the apparatus. According to the present invention, a laser light emitter is provided outside the housing so that even such a light source can be used as a light source for the measuring unit, and the light source and the measuring unit are connected by an optical fiber.

Still further, according to the present invention, the light receiving section includes:
A two-dimensional position detection sensor that detects the position of the received reflected light may be provided. In this case, since the position of the received light can be directly obtained by the two-dimensional position detecting sensor, it is not necessary to perform special processing for obtaining the position.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a distance measuring device 1 adopting the present invention. This distance measuring device 1 is for remotely observing a furnace 2 (a vacuum tank of an RH degassing facility, etc.), and a traveling carriage 4 traveling on a rail 3.
And a lifting and turning device 5 supported by the traveling carriage 4.
And a container 6 that is vertically rotated by an up-and-down rotating device 5. Inside the container 6, a measuring unit 8 for determining the distance to the refractory 7 which is the inner wall of the furnace 2 is provided.

The housing 6 (hereinafter referred to as an observation tube) has a cylindrical shape, and is inserted into the furnace 2 by the lifting / lowering and turning device 5.
This is for observing the melting state of the refractory 7 by measuring the shape of the furnace inner surface by obtaining the distance to the refractory 7 by the measuring unit 8 inside the observation tube 6. Although not shown, the observation tube 6 has a hollow inside and has a triple wall structure, and cooling water circulates inside the triple wall. Therefore, the furnace 2 in the high temperature state
Even in the inside, the inside of the observation tube 6 is at a low temperature, and the measurement unit 8 can stably perform the measurement.

The measuring unit 8 is a refractory 7 by a triangulation method.
The distance between and is calculated as shown in FIG.
An optical fiber 10 that guides a laser beam from the laser emitter 9 outside the observation tube 6 to the inside of the observation tube 6, and a projection system (lens) that narrows the laser light and irradiates the refractory 7 at an angle.
11, a mirror 13 is provided as a light receiving portion for receiving a laser beam (spot light) 14 that hits the refractory 7, and a camera 15 that captures an image reflected on the mirror 13 is provided. .

The laser light emitting device 9, the optical fiber 10, and the light projecting system 11 are respectively provided in three systems. This is to widen the measurable distance range. In other words, the distance from the measurement unit 8 to the refractory 7 changes like 7A, 7B, 7C, 7D depending on the melting damage state of the refractory 7, and the laser spot light reflected on the refractory 7 is changed by the change. The position of 14 moves up and down. If the position of the laser spot light 14 exceeds the range that can be captured by the camera 15 (the range captured by the mirror 11) due to the change, the image cannot be captured and the distance cannot be obtained. If the light sources 12 of three systems are prepared and the angles of projection on the refractory 7 are made different, the laser spot light 14 from any one of the light sources 12 falls within the image capturing range of the camera 15, so It becomes possible to cope with changes in the distance up to 7.

The laser emitter 9 and the optical fiber 1
0, the projection system 11 may be any system, and
Since the measurement distance range only changes, it can be changed appropriately. The laser emitter 9 is a YA that emits a green laser beam.
This is a G laser, and this YAG laser and other light sources of laser light having a wavelength shorter than red light have a larger device than a He-Ne laser or the like and cannot be incorporated in the observation cylinder 6, so the observation cylinder 6 It is provided outside.

In this case, the laser light has a wavelength of 550 n in order to be surely distinguished from the light emitted from the refractory 7 of the furnace 2.
Light of m or less is desirable. Moreover, as long as it is visible light, it is not necessary to use a special camera (for example, for ultraviolet light) as the camera 15, which is preferable. The green laser light is projected toward the refractory material 7. In this case, refractory 7
The light emitted when the temperature rises and becomes red hot is red, but the laser light is green (wavelength is shorter than red).
Therefore, it can be projected as spot light 14 on the surface of the refractory material 7.

Since the spot light 14 projected on the surface of the refractory 7 has a different color from the light emitted by the refractory 7,
This is also suitable for a case where a clear visual observation is made, and a television camera (not shown) for visual observation is separately provided in the observation cylinder 6 for visual observation. The camera 15 photographs the condition of the surface of the refractory 7 on which the laser spot light 14 is projected via the mirror 13. The camera 15 is connected to the information processing device 17 via a camera controller 16 for focusing the camera 15.

The information processing device 17 obtains the distance to the refractory 7 based on the signal processing unit 18 which processes the signal of the photographed image to find the position of the laser spot light in the image and the triangulation method. The processing unit 19 for measuring the shape of the furnace 2 and the display unit 20 for displaying the measured shape of the furnace 2. The distance L to the refractory 7 is equal to the projection system 11
The distance between the laser 13 and the mirror 13 is H0, the distance between the laser spot light in the image captured by the camera 15 and the image center is H, and the laser light projected from the light projecting system 11 onto the refractory 7 is shown. The angle may be θ, and the angle may be calculated by the triangulation method based on the above equation (1).

On the front of the camera 15, the interference filter 2
1 is provided. The interference filter 21 allows light having a wavelength of 532 nm (green) to pass therethrough, and can block other light, for example, light emitted by the refractory 7 that interferes with distance measurement. Therefore, the camera 15 can grasp only the light that has passed through the interference filter 21, and the scanning output waveform signal of the camera 15 is as shown in FIG.
As shown in, the light intensity of the portion 25 of the laser spot light is slightly attenuated as compared with the case where the interference filter 21 is not used, but the light intensity of the portion 26 of the spontaneous emission light from the refractory 7 or the like is drastically reduced. ing.

Therefore, as shown in FIG. 3, almost nothing except the laser spot light 14 is captured in the image 27 taken by the camera 15, and this image signal is processed to obtain the distance to the refractory 7. It is extremely convenient for That is, in the scanning output waveform signal of the camera 15, it is only the portion 25 of the laser spot light whose intensity exceeds a certain level, and only by detecting the portion having a certain level or more, the laser spot is detected. Light 14
The position of can be known and complicated image processing need not be performed.

Further, as a means for grasping the laser spot light 14 reflected on the refractory 7, the camera 15 as described above is used.
Instead, a two-dimensional position detection sensor 28 as shown in FIG. 5 can be used. The two-dimensional position detection sensor 28 is called a PSD element, and when the laser spot light 14 hits the surface of the sensor 28, the light 1
4 position, that is, the two-dimensional position of the brightest point on the surface of the sensor 28 is output as an analog signal.

More specifically, when the laser spot light 14 strikes the surface of the sensor 28, the photocurrent X1, whose value depends on the position of the laser spot light 14 in the X direction.
X2 and the photocurrents Y1 and Y2 whose values depend on the position in the Y direction
Occurs. These X1, X2 and Y1. The positions in the X direction and the Y direction are calculated from Y2 by the calculation units 29a and 29b.

Since the positions are calculated by the calculation units 29a and 29b in the X and Y directions, only the case where the position in the X direction is calculated by the calculation unit 29a will be described here. The photocurrents X1 and X2 generated by the sensor 14 are
When the position of the laser spot light 14 is one side of the X direction, the value of X1 increases and X2 decreases, and when the position of the laser spot light 14 is the other side, the value of X2 increases and X1 Will decrease.

Therefore, the difference between X1 and X2 represents the position of the laser spot light 14 in the X direction, the difference between X1 and X2 is calculated in the arithmetic unit 29a, and the difference is divided by the sum of X1 and X2. As a result, the magnitude of the output of the calculation unit 29a represents the position of the laser spot light 14 in the X direction regardless of the light intensity of the laser spot light 14 (if the light intensity changes, the generated photocurrent also changes). It will be.

The position of the laser spot light 14 in the Y direction is also X.
It is obtained in the same manner as the direction, and the outputs of the arithmetic units 29a and 29b are given to the information processing device 17. In this case, the position of the laser spot light 14 can be directly obtained by the two-dimensional position detection sensor 28 and the calculation units 29a and 29b, and the camera 15
Since it is not necessary to perform image processing on the image captured by the camera 15 by the signal processing unit 18 as in the case where the light is received by, the processing in the information processing device 17 is facilitated.

The above-described embodiment is merely an example and not a limitation. That is, the scope of the present invention is defined by the appended claims, and all modifications that fall within the meaning of the claims are included in the present invention. That is, for example, even if the light is not a green laser light, any color of light may be used as long as the light has a wavelength shorter than the light emitted from the measurement target that has been heated to a temperature sufficient to emit light, and need not be visible light.

[0033]

As described above, according to the present invention,
Even if the measurement object becomes hot and emits light, it projects light of a shorter wavelength than that light and receives only light of that short wavelength through the filter, so the light projected onto the measurement object is measured. It is possible to reliably determine the distance to the object to be measured without being buried in the light emitted from the object.

Since the light source of the measuring unit is provided outside the housing, a large light source device can be adopted without enlarging the housing. Further, since the light reflected from the inner wall of the furnace is received by the two-dimensional position detecting sensor, the position of the received light can be directly obtained by the two-dimensional position detecting sensor, and special processing for obtaining the position is performed. There is no need, and the device can be simplified.

[Brief description of drawings]

FIG. 1 is a perspective view showing a distance measuring device according to the present invention.

FIG. 2 is a block diagram similarly.

FIG. 3 is a scan output waveform signal diagram of a camera.

FIG. 4 is an image view taken by a camera.

FIG. 5 is a conceptual diagram of a two-dimensional position detection sensor.

FIG. 6 is a principle diagram of a triangulation method.

FIG. 7 is a scan output signal of a camera in a conventional distance measuring device.

[Explanation of symbols]

 1 distance measuring device 2 furnace 6 observation tube 7 refractory 8 measuring unit 9 laser light emitter 10 optical fiber 11 light projecting system 12 light source unit 13 mirror 14 camera 21 interference filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000004123 Nippon Steel Tube Co., Ltd. 1-2-1, Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Toshiya Kosato 1 Kanazawa-machi, Kakogawa-shi, Hyogo Kamido Steel Works, Ltd. Kakogawa Steel Works (72) Inventor Ikuo Hoshikawa 1 Kanazawa-machi, Kakogawa City, Hyogo Prefecture Kamido Steel Works Co., Ltd.Kakogawa Steel Works (72) Inventor Toko, Kanazawa-machi, Kakogawa City, Hyogo Prefecture Kakogawa Steel Works Co., Ltd. (72) Inventor Shigenobu Takada 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Mizushima Steel Works, Ltd. (72) In-house Takao Yamazaki 4-53, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Shuji Kobayashi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd.

Claims (4)

[Claims] 1. The light is projected onto the measuring object (7), the light reflected from the measuring object (7) is received, and the distance to the measuring object (7) is measured by a triangulation method. In the distance measuring method, the light projected onto the measurement object (7) has a shorter wavelength than the light emitted by the measurement object (7) that has been heated to a temperature that emits light, and the measurement object (7) A method for measuring a distance to a high-temperature object, characterized in that the light reflected from is passed through a filter (21) that passes only the light of the short wavelength and is received. 2. A hollow container (6) having a cooling mechanism for keeping the inside at a low temperature is inserted into the furnace (2) so as to be movable in the axial direction, and the furnace is placed inside the container (6). A light projecting system (11) for projecting light onto the inner wall (7) of (2) and the light projecting system (1) for receiving the reflected light reflected from the inner wall (7).
A light receiving part (13) provided at a position apart from the container (6) in the axial direction of the storage body (6) by a certain distance, and the distance from the light projecting system (11) to the light receiving part (13). And a distance measuring device for a high temperature object, wherein a vertical distance from the housing (6) to the inner wall (7) is obtained based on the inclination angle of the projection light from the light projecting system (11), The light projecting system (11) is connected to a light source having a wavelength shorter than that of the light emitted from the inner wall (7) that has been heated to a temperature high enough to emit light, and the short wavelength of the light received by the light receiving unit (13) is used. A distance measuring device for a high-temperature object, which is provided with a filter (21) which allows only the light of (1) to pass therethrough. 3. A laser which is connected to the light projecting system (11) by an optical fiber (10) and which is provided outside the housing (6). The distance measuring device for a high-temperature object according to claim 2, comprising a light emitter. 4. The two-dimensional position detection sensor (2) for detecting the position of the received reflected light in the light receiving section (13).
8) The distance measuring device for a high temperature object according to claim 2 or 3, further comprising: