JP5195555B2 - Apparatus and method for measuring liquid level of molten metal - Google Patents

Description

  The present invention relates to a molten metal liquid level height measuring apparatus and measuring method, and more particularly to a molten metal liquid level height measuring apparatus and measuring method in a float bath for forming sheet glass.

  A float bath used in the float method, which is one of the methods for producing plate glass, is formed of a predetermined refractory material, and stores a molten metal such as tin or tin alloy in the interior thereof to form a horizontal liquid surface. . On the other hand, in the float bath, the inside of the float bath is hermetically sealed for the purpose of preventing the stored high-temperature molten metal from being oxidized, and the sealed space is filled with a gas such as hydrogen or nitrogen.

  One of the methods for monitoring the state change inside the float bath is a means for measuring the liquid level of the molten metal. In this case, since the direct measurement of the liquid level by the worker is dangerous and the measurement time is limited, for example, a non-contact and automatic liquid level measuring means has been proposed as follows.

  That is, in Patent Document 1 below, as a method for measuring the molten tin liquid surface level of a float bath in a float glass plate, a laser spot light is irradiated on the molten tin liquid surface, and the scattered light of the irradiated portion is imaged. And the method of converting the displacement amount into the liquid level height of tin is disclosed. In this case, with respect to the position of the laser spot light source and the camera for imaging, the angle formed by the optical axis and the central axis of the camera is fixed at a predetermined angle, so that the amount of displacement of the captured scattered light can be reduced. The liquid level can be converted.

JP-A-6-167377

  However, molten tin has a lower viscosity than molten glass, and undulations and undulations occur as the plate glass is drawn out. Therefore, the molten tin always has various undulations in large and small directions in various directions. . In this way, when the laser surface is irradiated to the liquid surface whose liquid surface form changes every moment, the reflected light or scattered light is not constant, and this is imaged or received as disclosed in Patent Document 1 above. However, even if arithmetic processing is performed, it is difficult to accurately measure the liquid level. In addition, since the information processing apparatus with high processing performance is required for the arithmetic processing of the image data corresponding to the liquid level change, the equipment cost is also increased.

  Further, in the method disclosed in Patent Document 1, it is necessary to remove the laser spot light source and the camera at the time of maintenance such as periodic inspection, but if the position when re-installing these is slightly shifted from the intended position, the angle There was also a problem that the measurement accuracy was lowered.

  In view of the above circumstances, in the present specification, a liquid level measuring device and a measuring method that can accurately measure the liquid level of molten metal in a float bath with a relatively simple configuration and are easy to maintain. It is a technical problem to be solved by the present invention.

The present invention has been made to solve the above problems. That is, the liquid surface height according to the present invention measuring device, there is provided an apparatus for measuring the liquid level of the molten metal is reserved in the float bath for forming the sheet glass by drawing out the molten glass, the side walls of the float bath one The floating part floated from the liquid surface of the molten metal, the floating body having a specific gravity smaller than that of the molten metal, and the floating body floated on the molten metal staying in the protruding part due to inflow from the float bath A height position measuring means for measuring the height position of the part, and the space above the liquid surface of the molten metal staying in the overhanging portion is stored in the float bath by the overhanging portion and the remaining portion of the side wall continuous on the upper side. It is characterized by being isolated from the space above the liquid surface of the molten metal .

  As described above, the present invention is characterized in that, instead of measuring the liquid level of the molten metal, a portion that floats from the liquid level of the floating body arranged so as to float on the molten metal is used as a height position measurement target. Is. If it is a floating body that can float with respect to the molten metal, the portion to be measured has a certain surface shape without changing the form of the liquid level like the molten metal. Therefore, the height position can be accurately measured by using appropriate height position measuring means such as a distance sensor and displacement sensor for a part of the floating body that has floated from the liquid surface of the molten metal as described above. can do. Thereby, the liquid level height of the molten metal can be easily obtained from the height position of the floating body. In addition, since the measurement accuracy of the height position of the floating body is high, the liquid level can be obtained with high accuracy. Therefore, for example, a temporary rise in the liquid level accompanying the introduction of molten glass, or a drop in the liquid level that occurs over a long period of time due to the outflow or evaporation of the molten metal adhering to the plate glass at the time of drawing out automatically and increases. It can be detected accurately and appropriate measures can be taken for each event.

  As described above, if the liquid level is indirectly measured using a floating body, simple and highly accurate measurement is possible. However, even in this case, the floating body shaking due to the undulation of the liquid level is ignored. It is not possible. For this reason, the shaking is never small. Since the waving mainly occurs when the plate glass flows (drawn) on the liquid surface of the molten metal, it is effective to provide it as far as possible from the plate glass (molten glass) that is the main source of undulation, For example, an overhang part is provided in which a part of the side wall of the float bath is overhanged, and a part of the molten metal of the float bath flows into and stays in the overhang part, and the floating body is in the molten metal staying in the overhang part. A floating configuration may be adopted.

  Alternatively, for the purpose of reducing the influence of the waviness, for example, the floating body is floated on the molten metal of the float bath, and a liquid surface partitioning section for partitioning the liquid surface of the molten metal is provided so as to surround the floating body. You may make it take the structure which is. In view of the fact that the undulation of molten metal occurs mainly near the liquid surface of the molten metal as the molten glass is drawn, partitioning the liquid surface of the molten metal so as to surround the floating body is effective in reducing the undulation. In addition, the wave traveling on the liquid surface with the flow of the molten glass floated on the molten metal of the float bath can be blocked or attenuated at the liquid surface partitioning portion to reduce the ripples reaching the floating body. Needless to say, the liquid level partitioning section only needs to partition the vicinity of the liquid level, and may be configured to allow the molten metal to flow under the partitioned part.

In addition, by providing the liquid surface partitioning portion so as to surround the floating body, the floating body can be held in a certain region by the liquid surface partitioning portion regardless of how the flow of the liquid surface changes. Therefore, it is possible to stably carry out highly accurate liquid level height measurement in combination with the above-described wavy reduction effect. In addition, as described above, when the floating body is floated on the newly generated molten metal staying area by providing the overhanging part in the float bath, the liquid level of the molten metal staying in the overhanging part is partially or entirely The same effect as described above can also be obtained by providing a liquid surface partition section that partitions from the liquid surface of the molten metal stored in the float bath.

  As for the floating body, any material and structure can be adopted as long as the specific gravity is smaller than that of the molten metal and a part thereof floats from the liquid surface. Here, the center of gravity should be as low as possible from the viewpoint of reducing the shaking of the floating body. In other words, it is preferable to set the material, shape, etc. so that the gravity center of the floating body where the gravity acts and the gravity center where the buoyancy acts are not too far apart.

  Further, the floating body may have a flat surface that floats from the liquid surface of the molten metal in a state of floating on the molten metal, and the flat surface may be configured to follow the liquid surface of the molten metal. With this configuration, since laser light, electromagnetic waves, and the like are accurately reflected by a plane located above the liquid level, highly accurate position measurement is possible. Also, the types of height position measuring means that can be used increase.

  In addition, as an example of a floating body having both the above features, a floating body can be cited. In the case of a plate-like floating body, the upper end surface located above the liquid surface is flat, and laser light, electromagnetic waves, and the like are accurately reflected. Therefore, high-precision height position measurement can be performed by various height position measurement means. In addition, if it is plate-shaped, the upper end surface of the floating body is parallel to the liquid surface and the center of gravity is close to the liquid surface. Can do. Of course, any shape other than a plate shape, such as a block shape having a flat surface on the upper side, can be suitably used as a floating body.

  For height position measurement means, various types of detection media can be used. For example, non-contact sensors that use light (including laser light), electromagnetic waves, magnetism, and ultrasonic waves as detection media, pressure detection, etc. A contact sensor as a medium can be used without any particular limitation. This is because the portion of the floating body that has floated from the liquid surface is used as a direct measurement object, so that a shape and material suitable for the measurement means can be employed. Further, when viewed from the measurement environment, a displacement sensor or a distance sensor using a laser beam having excellent directivity and convergence compared to other detection media is preferable.

Further, the solution to the above problem is that in the method of measuring the liquid level height of the molten metal stored in the float bath for forming the plate glass by drawing the molten glass , the float bath is provided with a part of the side wall of the float bath. An overhanging part is provided, and a floating body having a specific gravity smaller than that of the molten metal is floated on the molten metal staying in the overhanging part due to inflow from the float bath, and the floating body part floating from the liquid surface of the molten metal is floated. The height position is measured , and the space above the liquid level of the molten metal staying in the overhanging part is located above the liquid level of the molten metal stored in the float bath by the remaining part of the side wall that is continuous with the overhanging part. It can also be achieved by a method for measuring the liquid level of the molten metal, characterized by being isolated from the space .

  As described above, according to the present invention, it is possible to accurately measure the liquid level of the molten metal in the float bath with a relatively simple configuration, and the liquid level measuring device and measuring method that are easy to maintain. Can be provided.

It is a principal part horizontal sectional view of the float bath for shaping | molding the plate glass which comprised the liquid level height measuring apparatus of the molten metal which concerns on 1st Embodiment of this invention. It is a principal part vertical sectional view of the float bath shown in FIG. It is a principal part horizontal sectional view of the float bath for shaping | molding the plate glass which comprised the liquid level height measuring apparatus which concerns on 2nd Embodiment of this invention. It is a principal part vertical sectional view of the float bath shown in FIG. It is a principal part vertical sectional view of the float bath for shaping | molding the plate glass which comprised the liquid level height measuring apparatus which concerns on 3rd Embodiment of this invention. It is a principal part horizontal sectional view of the float bath for shaping | molding the plate glass which comprised the liquid level height measuring apparatus which concerns on 4th Embodiment of this invention. It is a principal part vertical sectional view of the float bath shown in FIG. It is a principal part horizontal sectional view of the float bath for shaping | molding the glass plate which comprised the liquid level height measuring apparatus which concerns on 5th Embodiment of this invention. It is a principal part vertical sectional view of the float bath shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a horizontal sectional view of a plate glass forming float bath provided with a liquid level measuring device according to the first embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of the main part of the float bath shown in FIG. 1 and shows the overall configuration of the liquid level height measuring apparatus. First, as shown in FIG. 1, the float bath 1 stores molten tin 2 as molten metal, and the upper space of the molten tin 2 is reduced gas (mixed gas of hydrogen gas and nitrogen gas). be satisfied. Then, molten glass 3 melted in an unillustrated melting furnace located on the upstream side (upper side in the drawing) of the float bath 1 is supplied onto the molten tin 2 of the float bath 1. The supplied molten glass 3 is stretched in the width direction by a plurality of top rolls (not shown) disposed at predetermined intervals from the upstream side to the downstream side at both ends in the width direction of the float bath 1. However, it is drawn out to the downstream side (lower side in the figure) and formed into a strip-shaped glass ribbon 4. And after cooling this glass ribbon 4 by a slow cooling process, a glass substrate is obtained by cut | disconnecting to arbitrary magnitude | sizes. In any horizontal cross-sectional view of any float bath described later, the lower side in the drawing will be described below as the downstream side.

  As shown in FIG. 2, the liquid level height measuring device 5 for molten metal (here, molten tin 2) includes a floating body 6 having a specific gravity smaller than that of the molten tin 2 and a floating body 6 floated on the molten tin 2. The height position measuring means 7 for measuring the height position of the part which floated from the liquid level 21 of the molten tin 2 is mainly provided. In this embodiment, the calculation means 9 for calculating the height of the liquid surface 21 of the molten tin 2 based on the height position of the floating body 6 measured by the height position measurement means 7 and the calculation result by the calculation means 9 are displayed. And a monitor 10 to be further provided.

  The floating body 6 is formed in a predetermined shape with a material having a lower specific gravity and a higher melting point than tin, such as a refractory material such as brick, graphite, silicon carbide, quartz glass, etc. Is done. In this embodiment, the floating body 6 formed in a disk shape with a brick is used. Further, as shown in FIG. 1, a part of the side wall 11 of the float bath 1 is extended outward in the width direction to form an extension part 12, and a part of the molten tin 2 of the float bath 1 is formed in the extension part 12. The floating body 6 is floated on the molten tin 2 retained in the overhanging portion 12. When the shape of the float bath 1 (the shape of the entire storage space of the molten tin 2) is changed as in this embodiment, the shape may be designed to be as symmetrical as possible. Here, a pair of overhanging portions 12 are provided symmetrically in the width direction of the float bath 1, and the floating bodies 6 are floated on the molten tin 2 that flows into and stays in the pair of overhanging portions 12, respectively. Of course, the floating body 6 may be floated only on the molten tin 2 retained in one of the overhanging portions 12.

  In this embodiment, one end of a plurality of refractory ropes 13 is attached to the periphery of the floating body 6 having a disk shape, and the other end of the refractory rope 13 is connected to the side wall 11 or the overhanging portion 12 of the float bath 1. By fixing, the refractory ropes 13 function as anchoring means for the floating body 6, and the floating body 6 is stopped on the liquid surface 21 of the molten tin 2 retained in the overhanging portion 12.

  In this embodiment, the height position measuring means 7 is a laser displacement sensor using laser light as a detection medium, and this laser displacement sensor is a transmission window for laser light emitted from a built-in laser light source (light emitting unit). The housing box 8 is disposed above the floating body 6 by attaching the housing box 8 to the upper wall portion of the overhanging portion 12. As a result, the laser light emitted from the light emitting portion of the laser displacement sensor is reflected by the upper end surface of the portion floating from the liquid surface 21 of the floating body 6, and the reflected light is received by the light receiving portion of the laser displacement sensor. Thus, the distance to the upper end surface of the floating body 6, here, the amount of displacement from the reference distance is measured. The storage box 8 may be provided with a mechanism for circulating cooling nitrogen, a cooling mixed gas of nitrogen and hydrogen, or cooling water to suppress the temperature rise of the laser displacement sensor.

  A calculation means 9 is connected to the laser displacement sensor as the height position measuring means 7, and based on the height position of the floating body 6 (here, the amount of displacement from the reference height) measured by the laser displacement sensor, melting is performed. The height (or displacement amount) of the liquid surface 21 of the tin 2 is calculated by the calculation means 9. In this embodiment, since the upper end surface of the floating body 6 is at a position higher than the liquid surface 21 by a predetermined height, the amount of displacement of the height of the liquid surface 21 is calculated as a value obtained by subtracting the predetermined height, This displacement amount is displayed on the monitor 10 connected to the calculation means 9.

  In the case of the liquid level height measuring device 5 configured as described above, for example, when the molten glass 3 is charged as a reference height, the laser displacement is detected with the upper end surface of the part floating from the liquid level 21 of the floating body 6 as the detection target. The displacement of the liquid level is measured by the sensor (height position measuring means 7). Therefore, compared with the case where the liquid level 21 of the molten tin 2 is used as a direct detection target, highly accurate measurement with less fluctuation or error is possible. Of course, by calculating the absolute amount of the liquid surface height from the displacement amount of the liquid surface height by the calculating device 9 connected to the height position measuring device 7, the change in the absolute amount of the liquid surface height is automatically performed online. Can be measured at the same time, and can be constantly monitored by displaying it on the monitor 10. Furthermore, a series of operations from monitoring during operation to warning can be performed automatically, such as automatically issuing an alarm when the liquid level falls below a predetermined lower limit.

  Further, in this embodiment, the floating body 6 is floated (arranged) on the molten tin 2 retained in the overhanging portion 12 by providing the overhanging portion 12 of the float bath 1. It is possible to reduce the influence of the undulation of the liquid surface 21 caused by the drawing of the floating body 6 on the shaking of the floating body 6. Accordingly, it is possible to accurately measure the liquid level while keeping the upper end surface of the floating body 6 along the liquid level 21 as much as possible.

  In addition, when using the disk-shaped floating body 6 like this embodiment, the position where the vertical movement by the shaking of the floating body 6 is least is obtained by irradiating the center of the upper end surface with laser light. It becomes a measurement location. Therefore, it is possible to measure the liquid level with high accuracy. Further, if the floating body 6 has a disk shape, an equal fluctuation is generated with respect to waves from any direction, so that a stable floating state can be easily realized.

  As mentioned above, although one Embodiment of this invention was described, the liquid level height measuring apparatus which concerns on this invention is not limited to the form of the said illustration, It can take arbitrary forms within the scope of the present invention. Of course.

  FIG. 3: has shown the horizontal sectional view of the float bath for shaping | molding the plate glass provided with the liquid level height measuring apparatus which concerns on 2nd Embodiment of this invention. FIG. 4 is a vertical cross-sectional view of the main part of the float bath shown in FIG. 3 and shows the overall configuration of the liquid level height measuring apparatus. As can be seen from these drawings, the liquid level measuring device 5 according to the present embodiment mainly includes the liquid level 22 of the molten tin 2 retained in the overhanging portion 12 of the float bath 1 and the float bath 1 main body. The liquid level height measuring device according to the first embodiment described above in that a liquid level partitioning section 14 for partitioning the liquid level 21 of the molten tin 2 is provided between the stored liquid level 23 of the molten tin 2. Different from 5. Specifically, as shown in FIGS. 3 and 4, the long-plate-shaped liquid surface partitioning portion 14 is bridged between the side wall portions on both sides of the overhanging portion 12 along the longitudinal direction of the float bath 1. In this way, the liquid surface 22 of the molten tin 2 that stays in the overhanging portion 12 and floats the floating body 6 is partitioned from the liquid surface 23 of the molten tin 2 of the float bath 1 body. Is done. As a result, waves and undulations that occur on the liquid surface 23 of the molten tin 2 in the float bath 1 body with the molten glass 3 being drawn out are blocked or reduced by the liquid surface partitioning portion 14, so that it floats on the molten tin 2 in the overhanging portion 12. It is possible to greatly reduce the shaking of the floating body 6 that has been produced. Of course, the liquid level section 14 is disposed so as to straddle the liquid level 21 of the molten tin 2 in the vertical direction, and the molten tin 2 is stored in the float bath 1 body on the bottom side where the molten glass 3 floats. The space and the storage space for the molten tin 2 in the overhanging portion 12 on the side where the floating body 6 floats are connected. Therefore, the level of the liquid level 23 of the molten tin 2 in the float bath 1 main body and the level of the liquid level 22 of the molten tin 2 retained in the overhanging portion 12 are kept equal, and the measurement accuracy is ensured.

  In addition, when arrange | positioning so that the circumference | surroundings of the floating body 6 may be surrounded by the side wall of the overhang | projection part 12 and the liquid level division part 14 like this embodiment, on the liquid level 22 of the molten tin 2 which stays in the overhang | projection part 12 The floating body 6 will stop. Therefore, in the case of this structure, the fireproof rope 13 for anchoring mentioned above is unnecessary. Since other configurations are the same as those of the first embodiment, individual descriptions are omitted.

  FIG. 5: has shown the principal part vertical sectional view of the float bath provided with the liquid level height measuring apparatus which concerns on 3rd Embodiment of this invention. In this embodiment, the overhanging portion 12 is formed by extending a part of the side wall 11 located below the liquid surface 21 outward in the width direction, and the hole 15 communicating with the outside air is formed in the upper portion thereof. Is formed. Therefore, the laser displacement sensor and the storage box 8 as the height position measuring means 7 are attached to the lid member 16 provided so as to block the outside air by closing the hole 15, and thereby the laser displacement sensor is attached to the floating body 6. It is possible to arrange it toward the upper end surface. In this case, as shown in the figure, the floating body 6 is in the region surrounded by the hole 15 of the overhanging portion 12, and a part of the molten tin 2 of the float bath 1 main body flows into and stays in the molten tin 2. It floats and is retained on the liquid surface 22 of the molten tin 2. In addition, a portion of the side wall 11 that is above the portion that protrudes outward in the width direction and that straddles the liquid surface 21 in the vertical direction functions as the liquid surface partition 14. In this case, the upper space of the floating body 6 is isolated from the upper space of the molten glass 3 of the float bath 1 body. Therefore, the laser displacement sensor can be easily disposed above the floating body 6 simply by covering the hole 15 with the lid member 16 to which the laser displacement sensor (height position measuring means 7) is attached. Since other configurations are the same as those of the second embodiment, individual descriptions are omitted.

  FIG. 6: has shown the principal part horizontal sectional view of the float bath provided with the liquid level height measuring apparatus which concerns on 4th Embodiment of this invention. FIG. 7 is a vertical cross-sectional view of the main part of the float bath shown in FIG. 6 and shows the overall configuration of the liquid level height measuring apparatus. The liquid level height measuring device 5 according to the present embodiment is mainly provided with a liquid level partitioning portion 14 so as to surround the floating body 6 with a part of the side wall 11, thereby the liquid level of the molten tin 2. 21 is a liquid surface 23 of the molten tin 2 of the float bath 1 body on which the molten glass 3 is floated, and a liquid surface 22 of the molten tin 2 of the float bath 1 body, on which the floating body 6 is floated. It is different from the liquid level height measuring device 5 according to the second embodiment in that it is partitioned into two. Specifically, a substantially U-shaped plate-shaped liquid level partitioning portion 14 is provided integrally with the side wall 11 that is not the overhanging portion 12, and the region surrounded by the liquid level partitioning portion 14 and a part of the side wall 11 is provided. The floating body 6 is arranged. Then, as shown in FIG. 7, by using the height position measuring means 7 at the location 17 located above the floating body 6 in the upper wall portion of the float bath 1 main body, melting using the floating body 6 is performed. It becomes possible to measure the liquid level of the tin 2. As shown in the figure, the height of the upper wall portion where the displacement sensor is installed is changed in consideration of the measurement range of the height position measuring means 7 (laser displacement sensor) (for example, lowered as shown in FIG. 7). Thus, the distance between the laser displacement sensor and the upper end surface of the floating body 6 may be adjusted. Since other configurations are the same as those of the second embodiment, individual descriptions are omitted.

  FIG. 8: has shown the principal part horizontal sectional view of the float bath provided with the liquid level height measuring apparatus which concerns on 5th Embodiment of this invention. FIG. 9 is a vertical cross-sectional view of the main part of the float bath shown in FIG. 8 and shows the overall configuration of the liquid level height measuring apparatus. The liquid level measuring device 5 according to the present embodiment is the third embodiment in that the protruding portion 12 is formed by protruding a part of the side wall 11 located below the liquid level 21 outward in the width direction. Although it is the same as a form, it differs from the liquid level height measuring apparatus which concerns on 3rd Embodiment by the point which made the hole which can be connected with the external air provided in the upper part of this overhang | projection part 12 the guide surface 18 of the floating body 6. FIG. According to this configuration, regardless of the liquid level state of the liquid surface 23 of the molten tin 2 in the float bath 1 body, the molten tin 2 always staying in the region surrounded by the guide surface 18 on which the floating body 6 is floated. The liquid level 22 is stable, and the posture of the floating body 6 floated on the molten tin 2 can be kept horizontal. For this reason, it is possible to measure the liquid level very stably. Since other configurations are the same as those of the third embodiment, the description thereof is omitted.

  In addition, the arrangement position of the floating body 6 is arbitrary throughout the embodiment, and the floating position of the floating body 6 can be determined regardless of whether it is upstream or downstream of the illustrated position. In addition, any means for stopping the floating body 6 in the predetermined region is not particularly limited, and means other than the above-described means (such as the refractory rope 13, the liquid surface partition 14 and the side wall 11) may be used. it can.

  Moreover, in the said embodiment, although the part which floated from the liquid level 21 has illustrated the thing which has a flat upper end surface as the floating body 6, of course, it does not need to restrict to this. Even if the measurement location (for example, the upper end surface) is not necessarily flat, for example, in the case of a laser displacement sensor, it is sufficient to perform detection at a wavelength that does not detect surface roughness unevenness and undulation related to flatness.

  Further, the measurement location does not necessarily have to be a flat surface. For example, although not shown in the figure, a tall detected portion such as a columnar shape is erected on the upper surface side of the plate-like floating body 6, and the erected columnar shape. The tip of the part may be the measurement location. Further, depending on the type of the height position measuring means 7 to be used, for example, a multilayer board in which a measurement target layer having a good measurable surface and a floating layer having a small specific gravity are superposed can be used as the floating body 6. It is.

  In the above description, the case where one laser displacement sensor is used as the height position measuring means 7 is exemplified, but of course, a laser distance sensor or a distance sensor using another detection medium may be used. Or you may make it measure the absolute amount of the height position of the floating body 6 using two laser displacement sensors. The laser light source is not particularly limited, and a relatively small and inexpensive semiconductor laser, a gas laser such as an argon laser, or a solid laser such as a ruby laser is appropriately selected according to the wavelength of light to be used. Can be used.

  In addition, if it is light other than laser light (mainly visible light), the height position of the floating body 6 can be measured by separately providing an imaging means such as a CCD camera. It goes without saying that a detection medium such as a displacement sensor or a distance sensor using electromagnetic waves, magnetism, or ultrasonic waves can be used as the height position measuring means 7.

  Of course, other specific forms can be adopted for matters other than the above as long as the technical significance of the present invention is not lost.

DESCRIPTION OF SYMBOLS 1 Float bath 2 Molten tin 3 Molten glass 4 Glass ribbon 5 Liquid level height measuring device 6 Floating body 7 Height position measuring means 9 Calculation means 11 Side wall 12 Overhang part 13 Fireproof rope 14 Liquid level partition part 15 Hole 16 Lid member 21 Liquid level

Claims (6)

In an apparatus for measuring the liquid level of molten metal stored in a float bath for forming plate glass by drawing molten glass,
An overhang part in which a part of a side wall of the float bath is overhanged , a floating body having a specific gravity smaller than that of the molten metal, and the floating floated on the molten metal staying in the overhang part due to inflow from the float bath A height position measuring means for measuring a height position of a part of the body that has floated from the liquid surface of the molten metal ;
The space above the liquid level of the molten metal staying in the overhanging part is separated from the space above the liquid level of the molten metal stored in the float bath by the remaining part of the side wall that is continuous above the overhanging part. An apparatus for measuring the liquid level of a molten metal. The level of molten metal staying in said flared portion, at a part or the whole, of claim 1, the liquid level partitioning unit that partitions the liquid surface of the molten metal is reserved in the float bath is provided Liquid level measuring device.   The floating body has a flat surface that floats from the liquid surface of the molten metal in a state of floating on the molten metal, and the flat surface is configured to be along the liquid surface of the molten metal. An apparatus for measuring the liquid level of a molten metal according to 1. The liquid level measuring device for molten metal according to claim 3 , wherein the floating body has a plate shape. The height position measurement means, light, electromagnetic waves, magnetic, and is a non-contact type sensor using an detection medium selected from the group consisting of ultrasound according to any one of claims 1-4 Liquid level measuring device for molten metal. In the method of measuring the liquid level of the molten metal stored in the float bath for forming the sheet glass by drawing the molten glass,
The float bath is provided with an overhang portion in which a part of the side wall of the float bath is overhanged, and a floating body having a specific gravity smaller than that of the molten metal is retained in the overhang portion by inflow from the float bath. Float on metal,
Measure the height position of the part of the floating body that floated from the liquid surface of the molten metal ,
The space above the liquid surface of the molten metal staying in the overhanging portion is isolated from the space above the liquid surface of the molten metal stored in the float bath by the remaining portion of the side wall that is continuous with the overhanging portion and above. A method for measuring the liquid level of a molten metal.

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