JPS61250520A - Liquid level meter - Google Patents

Abstract

PURPOSE:To obtain the titled level meter reduced in heat loss, by mutually arranging a laser irradiation part and a laser receiving part so as to provide a definite distance therebetween and making the irradiation angle of the laser irradiation part variable to detect an angle. CONSTITUTION:The laser beam 5 of a laser irradiation part 11 is allowed to be incident to a reference surface 13 to be reflected at a point P0 and the reflected beam 16 thereof is received by a laser receiving part 12. The laser beam 17 of the laser irradiation part 11 is allowed to be incident to a falling surface 14 in the same way to be reflected at a point P1 and the reflected beam 18 thereof is received by the laser receiving part 12. Herein, the displacement (h) from the reference surface 13 to the falling surface 14 represented by formula (wherein h is the distance from the point P formed by connecting the leading end part of the laser irradiation part 11 and that of the laser receiving part 12 to the molten glass falling liquid surface 14, h0 is the distance from the point P to the reference liquid surface 13, d is each of the distances from the point P to the laser irradiation part 11 and the laser receiving part 12 and theta is the angle formed by laser beam and the falling surface). Because d and h0 are determined by a setting condition, the displacement (h) is calculated by detecting the irradiation angle theta.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a liquid level meter using laser light.

This liquid level meter is used to detect the displacement of the molten liquid level of molten glass, molten plating, etc. ) or installed in a crucible kiln, etc.

(Prior art) Generally, in the production of glass tableware such as crystal tableware,
Various manual or mechanical means are used to shape the glass substrate melted in a glass melting furnace or the like. In the case of a crucible kiln, the glass base is wound up onto the tip of a blowing rod and shaped, and the level of the molten glass gradually falls depending on the amount of gobs collected. When using a robot for this winding process, it is necessary to measure the level of the molten glass in order to set the angle at which the blowing rod is lowered. In addition, when using a continuous melting furnace for discontinuous production or production where the pulling m changes from moment to moment, such as when producing a wide variety of products with different product weights, a mechanism for temporarily storing molten glass is required. A glass storage tank is required, but at this time, it is necessary to measure the molten glass liquid level in the storage tank from the glass melting furnace, regardless of the level of the molten glass liquid level in the storage tank.

There are contact type and non-contact type liquid level gauges used in such discontinuous or irregular production and molding operations that involve large fluctuations in the glass liquid level.

A contact type liquid level meter detects the displacement of the molten glass liquid level by intermittently repeating 0N-OFF on the detection end with respect to the molten glass liquid level, but if the molten glass adheres to the detection end. There was a problem that this could cause the device to malfunction. Next, a non-contact type liquid level meter is disclosed in Japanese Patent Publication No. 55-51024. As shown in FIG. 4, a laser irradiation section 1 with a fixed irradiation angle θ is installed above the liquid surface, and the laser beam 2 irradiated from this irradiation section 1 is directed from the liquid surface 3 to the liquid surface 4. When descending, reflected light 5 reflected from each liquid level 3 and 4
and 6 are detected by the laser light receiving sections 7 and 8. However, in order to secure the optical path of the reflected lights 5 and 6, [Problem to be solved by the invention] [Means for solving the problem] The present invention has been made to achieve the above object. A laser light receiving part is installed as a laser irradiation part above the melt surface, and the laser light irradiated from this laser irradiation part is incident on the melt surface at an irradiation angle θ, and the reflected light is reflected by the laser beam. A liquid level meter that detects the displacement of the molten liquid surface from the irradiation angle θ when light is received by the light receiving part, the laser irradiation part and the laser receiving part are installed at a fixed distance from each other, and the laser irradiation part This liquid level meter is characterized in that the irradiation angle θ of the part is variable.

(Example〕 Examples of the present invention will be described in detail below.

FIG. 1 is a conceptual diagram of the present invention. The liquid level meter of the present invention includes a laser irradiation section 11 with a variable irradiation angle and a laser light receiving section 12.
is placed above the molten glass surface 13 at a distance of 2d. h from the reference surface 13 which is the initial molten glass liquid level.
An example of the descending surface 14, which is the molten glass liquid level that has descended by a certain amount, will be described. Laser irradiation unit 11 on reference plane 13
The laser beam 15 is at point P.

The reflected light 16 is received by the laser light receiving section 12. Similarly, the laser beam 17 of the laser irradiation unit 11 is reflected on the descending surface 14 at the point P1, and the reflected light 18
is received by the laser light receiving section 12.

Therefore, the displacement from the reference surface 13 to the descent surface 14 is 1
=fi1-h.

= d-tan θ-ho --- (1) Since the following relationship holds true and d and ho are determined by the installation conditions, the above displacement can be determined by detecting the irradiation angle θ. The means for detecting the irradiation angle θ may be a potentiometer using a magnetoresistive element, a shaft encoder, a rotary differential transformer, a pulse generator, an angle sensor using a strain gauge, etc., as long as it can measure the angle. , any type is fine.

FIG. 2 shows the descending surface 1 from the reference surface 13 as shown in FIG.
4 is an embodiment diagram in which the laser beam 17 from the laser irradiation section 11 is reflected by the descending surface 14 and the reflected light 18 is received by the laser light receiving section 12 when the laser beam 17 descends to 4. In this example, the cross section of the molten glass storage tank 9 is square with an internal dimension of 168°1llllIl, and the laser beam 17 is directed to the molten glass liquid surface 14.
The light is irradiated and reflected at an angle of 28°±5° approximately at the center of the area, as will be described later. The laser irradiation section 11 and the laser light receiving section 12 are located on one side of the liquid level 14 and near the outer side (50n+m) of the opening 10 on the irradiation side and the light receiving side.

FIG. 3 is a structural diagram of the laser irradiation section 11 of this embodiment. A rectangular parallelepiped block 19 made of aluminum is directly connected to a speed reducer 21 via a shaft 20.

A laser oscillator 22 using a He-Ne laser is mounted inside the block 19 parallel to the shaft mounting surface 23 and at an angle of 28 degrees to the bottom surface, as shown by arrow 3.
Laser light is irradiated in one direction. A potentiometer (angle sensor) 24 using a magnetoresistive element is connected to a block 19.
It is inserted perpendicularly to the top surface of the block 19 and is attached inside the block 19. The reversible motor 25 rotates the block 19 forward and reverse in the directions of arrows 26° and 26' via the decelerator 21. Detection end 28 of micro switch 27, 27'
．． 28' is attached so that when the block 19 rotates ±5 degrees in the direction of arrows 26 and 26', the dog 29 attached perpendicularly to the shaft 20 similarly rotates and comes into contact with this dog 29. It is being When the block 19 is thus rotated by 5 degrees in the direction of the arrow 26, the dog 29 contacts the detection end 28 of the micro switch 27,
The reversible motor 25 reverses its direction of rotation through the control circuit 30.

Block 19 begins to rotate in the direction of arrow 26' and -5
When the motor 25 rotates up to 50°, the detection end 28' of the micro switch 21' similarly contacts the dog 29, and the direction of rotation of the reversible motor 25 is reversed again. Thus block 19
constantly repeats forward and reverse rotation within a range of ±5°, and scans the laser beam within an angular range of 28° and 5° with respect to the horizontal plane. During this time, the angle sensor 24 is connected to block 19 in FIG.
An angle signal 33 corresponding to the rotation angle of is constantly sent to the angle signal transfer section 32.

In FIG. 2, the angle signal transfer unit 32 is 28°±5°.
The laser irradiation unit 11 scans the laser beam in the angular range of
An angle signal 33 from the laser and a light reception signal 34 from the laser light receiving section 12 which has a built-in photodiode are supplied, and the light reception signal 34 is triggered, the angle signal 33 is sampled, and the signal remains until the next light reception signal triggers. During this period, the angle signal 33 is held, and this device sends the held angle signal 35 to the instrumentation control system of the melting furnace.

In addition, in the instrumentation control system, the held angle signal 35 is A/D converted, and the irradiation angle θ is determined from a data table prepared in advance in the instrumentation control system, and
Calculate the displacement using the formula. By controlling a valve installed upstream of the glass storage tank based on this displacement, l of the molten glass flowing from the glass melting furnace into the glass storage tank is kept constant.

The size L of the frontage 10 on the light receiving side of the molten glass storage tank is:
For a maximum displacement of the liquid level of 200 mm, conventionally at least 400 IIllll was required, but according to this example, it can be reduced to 15 mm (calculated 12 nv).

Moreover, a liquid level meter can be realized by using only one laser light receiving section 12.

In the above embodiment, the present invention is applied to a molten glass storage tank, but it may also be applied to a glass melting tank, a glass melting furnace such as a forehearth, a molten plating tank, etc.

Furthermore, the laser oscillator may be a gas laser such as He-Cd, Ar, or Ni-R, or a solid state laser or semiconductor laser such as Nd:YAG or Nd glass. The laser light receiving section may include a built-in light receiving element such as a phototransistor, a photothyristor, or a photoconductive element.

〔Effect of the invention〕

As described above, the liquid level meter of the present invention detects the beam again by changing the irradiation angle of the laser irradiation part, so compared to the conventional liquid level meter with a fixed projection angle, the liquid level meter of the present invention has an opening on the laser beam receiving side. It is possible to significantly reduce the size of the laser receiving section, prevent heat loss, and prevent the formation of striae, improving the quality of the glass substrate. It can be realized by using this method, and its economic effects are significant.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing a liquid level meter according to the present invention, Figure 2 is a conceptual diagram showing a liquid level meter according to the present invention.
FIG. 3 is a structural diagram showing an embodiment of the present invention, FIG. 3 is a structural diagram showing a laser irradiation section, and FIG. 4 is a structural diagram showing a conventional liquid level meter. 1.11... Laser irradiation section, 7, 8.12... Laser receiving section, 3, 13... Molten glass liquid level (reference surface),
4.14... Molten glass liquid level (descending surface), 9... Molten glass storage tank, 10... Frontage section, 21... Decelerator, 22... Laser oscillator, 24... Angle sensor, 2
5...Reversible motor, 27.27'...Micro switch, 28.28'...Detection end, 29.
...Dog, 30...Control circuit, 32...
Angle signal transfer unit, 33...Angle signal, 34...Light reception signal, 35...Holded angle signal Fig. 1 Fig. 2

Claims (3)

[Claims] (1) A laser irradiation part and a laser reception part are installed above the melt surface, and the laser irradiation light emitted from the laser irradiation part is incident on the melt surface at an irradiation angle θ, and the reflected light is detected. In the liquid level meter that detects the displacement of the molten liquid surface by receiving light at the laser receiving section, the laser irradiating section and the laser receiving section are installed at a certain distance from each other, and the laser irradiating section A liquid level meter characterized by variable irradiation angle θ and angle detection. (2) The liquid level meter according to claim (1), wherein the laser irradiation part and the laser light receiving part are installed at equal distances from the melt surface. (3) A liquid level meter according to claim (1) or (2), wherein the molten liquid level is a molten glass liquid level.