JP5614715B2 - Glass plate manufacturing apparatus and glass plate manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a glass plate and an apparatus therefor, and more particularly, to create an atmosphere or state in which a glass ribbon can be appropriately formed on molten tin in a float bath using a top roll by a float process. Regarding technical ideas.

  As is well known, plasma display (PDP), liquid crystal display (LCD), field emission display (FED), flat panel display (FPD) typified by organic EL display (OLED), solar cell, secondary battery, etc. The actual situation is that the glass plate used in the production of the above is manufactured by various methods.

  As a kind of manufacturing method, a glass ribbon is formed by guiding the molten glass floated on the molten tin stored in the float bath to the downstream side, and the glass ribbon is solidified from the downstream end of the float bath. A float method is known which is taken out. When this float method is adopted, in the forming area in the float bath, the glass ribbon is pulled outward on both sides in the width direction by using a plurality of top rolls arranged in the vicinity of both side edges of the glass ribbon. Thus, the thickness and the plate width are set to desired values.

  The top roll has a roll portion that is engaged with a side edge portion of the glass ribbon and is usually made of metal (heat-resistant metal), and a hollow rotating shaft portion that is integrally connected to the roll portion. The hollow portion of the rotating shaft portion is an internal passage through which cooling water as a cooling medium flows through the roll portion. The main reason why the top roll has such a configuration is to prevent adhesion between the roller portion and the glass ribbon by cooling the roller portion that engages with the glass ribbon and bites.

  In such a top roll cooling system, not only the roller portion engaged with the glass ribbon but also the rotating shaft portion integrally connected to the roller portion serves as a cooling body, and therefore the roller portion and the rotating shaft portion as a whole. It becomes a cooling body. Therefore, this cooling body becomes a local disturbance factor of the temperature in the float bath, and also increases a heat loss as the float bath. In addition, since this cooling body locally produces a relatively low temperature portion in the float bath, the volatiles of tin in the float bath aggregate and adhere at the low temperature portion, and the deposit is deposited on the glass ribbon. Dropping incurs a problem that product defects occur.

  As a technique related to avoiding this type of problem, Patent Document 1 discloses a configuration in which a cover is attached to the tip surface of the roller portion of the top roll and a heat insulating material serving as a heat retaining member is filled in the cover. Also. Patent Document 2 discloses a configuration in which a portion excluding an engagement portion with a glass ribbon in a roller portion of a top roll is covered with a massive heat shield.

JP-A-8-277131 JP-A-10-212128

  However, even if the measures disclosed in Patent Documents 1 and 2 are taken, the problem of local disturbance of temperature and heat loss in the float bath described above, and the occurrence of a local low-temperature portion in the float bath Problems such as agglomeration and adhesion of tin volatiles and their falling cannot be reliably avoided.

  That is, since the countermeasure disclosed in Patent Document 1 is provided with a heat insulating material on the tip surface of the roller of the top roll only for the purpose of equalizing the temperature of the glass ribbon, it is in a wide space in the float bath. It may not have a favorable influence on the inappropriate phenomenon that occurs. Therefore, in this measure, the presence of the top roll may cause local disturbance of temperature and heat loss in the float bath, and may cause cohesion and adhesion of tin volatiles and their fall. Can still be avoided. Further, if it is intended to avoid such a problem, it becomes necessary to excessively increase the output of the heater of the heat insulating material (heat insulating material), which is not only disadvantageous in terms of cost, but also the roller portion. The original function of cooling and preventing adhesion to the glass ribbon is impaired.

  Moreover, since the countermeasure disclosed in Patent Document 2 is for the purpose of only reducing the heat dissipation loss of the top roll, substantially only the peripheral portion of the roller portion in the top roll is covered with a heat shield, Even in this case, it is difficult to appropriately influence an inappropriate phenomenon occurring in a wide space in the float bath. Moreover, the heat shield is a solid or fiber lump, and when the engaging portion of the roller portion with the glass ribbon is covered with the heat shield, proper biting into the glass ribbon is performed. Therefore, it is necessary to expose the engaging portion. In view of these circumstances, even if such measures are taken, the exposed portion on the outer surface of the top roll is inevitably widened, and the presence of the top roll is caused by local disturbance of the temperature in the float bath and heat loss. In addition, it is still impossible to avoid such factors as aggregation and adhesion of tin volatiles and their falling.

  In view of the above circumstances, the present invention maintains the function of preventing adhesion of the top roll to the glass ribbon, and locally disturbs the temperature in the float bath and heat loss due to the presence of the top roll. It is a technical problem to avoid the occurrence of problems such as cohesive adhesion and dropping.

  The apparatus according to the present invention, which was created to solve the above technical problems, is formed on the surface of the side edge of the glass ribbon when the molten glass is floated on the molten tin stored in the float bath to form the glass ribbon. A top roll having an engaging roller portion and a rotating shaft portion integrally connected to the roller portion and formed therein with a cooling medium flow path for cooling the roller portion is provided in the vicinity of both side edges of the glass ribbon. In the glass plate manufacturing apparatus that is arranged to pull the glass ribbon outward in the width direction by using the top rolls, the roller part and the rotating shaft part in the top roll Characterized by coating the outer surface with zirconia. Here, the above-mentioned “width direction” is a direction orthogonal to the traveling direction of the glass ribbon, and the “side edge portion of the glass ribbon” means an end portion in the width direction of the glass ribbon ( The same applies hereinafter).

  According to such a configuration, although the roller portion and the rotating shaft portion of the top roll can be a cooling body, a film is formed on the outer surface by the coating of zirconia. The adverse effect of presence on the atmosphere in the float bath is effectively avoided. More specifically, zirconia not only exhibits excellent heat resistance, but also has a lower thermal conductivity than metals (heat resistant metals) that are customary materials for forming roller parts and rotating shaft parts. When the zirconia coating is formed on the outer surface of the top roll at an appropriate place, absorption of heat from the atmosphere in the float bath is suppressed. Therefore, in spite of the presence of the top roll, it is possible to avoid making the local disturbance of the temperature in the float bath and the increase of the heat loss unreasonable. Moreover, in the float bath, since the occurrence of a relatively low temperature part is locally suppressed, the probability of occurrence of a situation in which the volatile matter of tin aggregates and adheres at the low temperature part and the attached substance falls on the glass ribbon. Can be reduced, and deterioration of the quality of the glass plate as the final product can be suppressed. Furthermore, even if the outer surface of the engaging portion of the roller portion of the top roll that is engaged with the glass ribbon is coated with zirconia, the roller portion and the glass ribbon are not affected by that degree because the cooling function of the roller portion is not impaired. There will be no situation of sticking. In other words, by forming a zirconia film, the cooling function by the roller part is slightly lowered, but the function is not lowered to the extent that the roller part and the glass ribbon are adhered. Therefore, the top roll can smoothly perform the original action of pulling the glass ribbon in the direction of increasing the width while rotating without any hindrance. In addition, if the float bath is small, the effect of installing the top roll coated with zirconia as described above can be obtained more remarkably, and it is also effective for glass ribbons having a high molding temperature. It is. In addition, it is preferable that zirconia is coat | covered in the whole area or substantially whole area | region of the outer surface including the front end surface of a roller part, and also coat | covers the whole area or substantially all area | region also about the outer surface of a rotating shaft part. Further, when only one coating layer (film) is formed on the outer surface of the roller part and the rotating shaft part, the layer is inevitably a coating layer of zirconia. Is formed, the outermost layer is a zirconia coating layer.

  In this case, the zirconia is preferably coated by thermal spraying.

  In this way, if the outer surface of the roller portion of the top roll and the outer surface of the rotating shaft portion are configured to be coated with zirconia by thermal spraying, the periphery of the roller portion including the outer peripheral surface (engagement portion with the glass ribbon) of the roller portion is Despite having a complicated and complicated shape, it is possible to form a zirconia sprayed film having a uniform thickness over the entire area of the outer surface without leakage. Further, a zirconia sprayed film having a uniform thickness can be formed on the entire outer surface of the rotating shaft portion without leakage. In addition, the material that can be sprayed is limited due to its characteristics. However, since zirconia is a material suitable for spraying, a high-quality sprayed coating can be appropriately formed at a desired location.

  Moreover, it is preferable that the coating thickness of the said zirconia is 1-1000 micrometers.

  If a coating of zirconia having a thickness in such a numerical range is formed on the outer surface of the roller portion and the rotating shaft portion of the top roll, the top roll can absorb heat from the atmosphere in the float bath, It is appropriately controlled without excess or deficiency.

  In addition, the method according to the present invention, which was created to solve the above technical problem, has a side edge of the glass ribbon when the molten glass is floated on the molten tin stored in the float bath to form the glass ribbon. A top roll having a roller portion that engages with the surface and a rotating shaft portion that is integrally connected to the roller portion and that has a cooling medium flow passage formed therein for cooling the roller portion. In the glass plate manufacturing method in which the glass ribbons are arranged in the vicinity of each portion and the glass ribbon is pulled outward in the width direction using the top rolls, the outer surfaces of the roller portion and the rotating shaft portion are covered with zirconia. It is characterized by pulling the said glass ribbon toward both sides of the width direction outward using the top roll formed.

  Since the configuration of this method is substantially the same as the configuration of the device according to the present invention described above, the explanation items including the operational effects are substantially the same as the explanation items already described for the device. Are identical.

  As described above, according to the present invention, since the outer surfaces of the roller portion and the rotating shaft portion of the top roll are coated with zirconia, local disturbance of temperature in the float bath and increase in heat loss are made unreasonable. In addition to avoiding the occurrence of local relative low temperature in the float bath, tin volatiles agglomerate and adhere at the low temperature and fall on the glass ribbon. The occurrence probability of the situation is reduced, and the deterioration of the quality of the glass plate is suppressed. Furthermore, even if zirconia is coated in this way, it does not lead to a situation in which the roller portion and the glass ribbon adhere to each other, so the width of the glass ribbon is reduced while the top roll rotates. The original action of pulling in the spreading direction can be performed smoothly and without hindrance.

It is a schematic plan view which shows the whole structure of the glass plate manufacturing apparatus (implementation condition of the glass plate manufacturing method) which concerns on embodiment of this invention. It is a schematic front view which shows the principal part structure of the glass plate manufacturing apparatus (implementation condition of the glass plate manufacturing method) which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view schematically showing a glass plate manufacturing apparatus (and an implementation status of the manufacturing method) employing the float method, and FIG. 2 is a characteristic configuration of the glass plate manufacturing apparatus. It is a principal part enlarged front view which shows the periphery structure of the top roll which is an element.

  As shown in FIG. 1, the glass plate manufacturing apparatus 1 according to the present embodiment has a float bath 3 in which molten tin 2 is stored, and is supplied from the downstream portion of the melting furnace (not shown) to the upstream portion of the float bath 3. The molten glass 4 is floated on the molten tin 2 and guided downstream (in the direction of arrow A). After passing through the forming zone 5, the glass ribbon 6 is formed and the downstream end of the float bath 3. It is configured to be pulled out from. In the forming area 5 of the float bath 3, a plurality of top rolls 7 are arranged in the vicinity of both side edges 6 a of the glass ribbon 6, and these top rolls 7 face the glass ribbon 6 outward in the width direction. Configured to be pulled.

  FIG. 2 illustrates in detail the structure of each top roll 7 and its peripheral structure. As shown in the figure, the top roll 7 includes a roller portion 7a having a claw portion 7ax as an engaging portion that engages (bites in) with a side edge portion of the glass ribbon 6, and a roller portion 7a. And a rotating shaft portion 7b that extends in an integrated manner and extends outward. The rotating shaft portion 7 b is loosely inserted into a through hole 3 x formed in the side wall 3 a of the float bath 3, and an outer end thereof is connected to the driving portion 8.

  Further, the rotary shaft portion 7b includes a small-diameter main shaft 7ba whose inner end is fixed to the outer end surface 7ay of the roller portion 7a and whose outer end is connected to the drive unit 8, and an axially outward direction of the main shaft 7ba. It consists of a protective sleeve 7bb that is externally fitted and fixed to the side portion. The main shaft 7ba is a hollow shaft, and the hollow portion serves as an internal passage for supplying cooling water as a cooling medium into the roller portion 7a. Accordingly, the cooling water is configured to flow through the inside of the roller portion 7a and the inside of the rotating shaft portion 7b over the entire length in the axial direction.

  Thus, the entire area of the outer surface of the roller portion 7a and the rotating shaft portion 7b of the top roll 7 is coated with zirconia, and the coating is performed by thermal spraying. Accordingly, the inner end surface (tip surface) 7az and the outer end surface 7ay of the roller portion 7a, the outer surface of the claw portion 7ax, the outer peripheral surface of the inner side portion of the main shaft 7ba (the outer peripheral surface of the exposed portion) 7bx, and further the protective sleeve A zirconia film is formed on the outer peripheral surface 7by and the inner end surface 7bz thereof over the entire length of 7bb in the axial direction. In this case, the coating thickness (film thickness) of zirconia is set to 1 to 1000 μm.

  More specifically, the roller part 7a and the rotating shaft part 7b in the top roll 7 are made of metal (heat-resistant metal), and zirconia is a material having a lower thermal conductivity than that metal and suitable for thermal spraying. Material. Therefore, on the outer surfaces of the roller portion 7a and the rotating shaft portion 7b, there are complicated and complicated portions including the periphery of the claw portion 7ax of the roller portion 7a. A film is formed. Moreover, thermal spraying of zirconia is performed using a plasma flame, a gas flame, and an explosion flame (detonation method).

  According to the configuration as described above, since the cooling water is circulated inside the top roll 7, the top roll 7 can be a cooling body in the float bath 3. However, since a film of zirconia having a lower thermal conductivity than the metal forming these 7a and 7b is formed on the entire outer surface of the roller portion 7a and the rotating shaft portion 7b in the top roll 7. The top roll 7 is prevented from absorbing heat from the atmosphere in the float bath 3. For this reason, despite the presence of the top roll 7 in the float bath 3, local disturbance of the temperature and unreasonable increase in heat loss in the float bath 3 are avoided. In addition, in the float bath 3, it is difficult to cause a local relative low temperature portion due to the presence of the top roll 7. The phenomenon that the kimono falls on the glass ribbon 6 is less likely to occur, and the deterioration of the quality of the glass plate as the final product can be suppressed.

  Further, the top roll 7 is uniformly covered with zirconia, including the outer surface around the claw portion 7ax, which is the engaging portion of the roller portion 7a with the glass ribbon 6. In this manner, the top roll As long as a zirconia film is formed on the outer surface of the roller 7, the situation where the roller portion 7a and the glass ribbon 6 adhere to each other does not occur. Therefore, the top roll 7 can smoothly perform the original operation of pulling the glass ribbon 6 in the direction of widening the width while rotating without trouble.

  Further, since the outer surfaces of the roller portion 7a and the rotating shaft portion 7b of the top roll 7 are coated with zirconia by thermal spraying, the periphery of the claw portion 7ax of the roller portion 7a and the like has a complicated and complicated shape. Therefore, a zirconia sprayed film having a uniform thickness can be formed on the entire outer surface area without leakage. Therefore, a high-quality zirconia sprayed coating is formed over the entire outer surface of the roller portion 7a and the rotating shaft portion 7b, and the adverse effect on the atmosphere in the float bath 3 is more appropriately avoided. Is done.

  In the above embodiment, only one layer of the zirconia film is formed on the outer surface of the roller portion 7a and the rotating shaft portion 7b of the top roll 7, but a plurality of different types of films are formed and the outermost layer is the zirconia film. It is good. In such a case, by interposing a film that is larger than the thermal expansion coefficient of the metal portion forming the roller part 7a and the rotating shaft part 7b and smaller than the thermal expansion coefficient of the zirconia film as an intermediate layer. The probability of the zirconia film peeling off can be effectively reduced by relieving the thermal expansion difference generated between the two. In this case, the film of the intermediate layer may be a metal film or a mixture of a metal film and ceramics.

  The present inventors tried an experiment to confirm the effect of the present invention. The details of the experiment and results are as shown below.

  Plasma spraying an alloy of Ni 80% and Cr 20% by weight on the outer surface of the roller part and the rotating shaft part in a state where the roller part and the rotating shaft part of the top roll made of SS400 are separated. Thus, an alloy sprayed film having a thickness of about 85 μm was formed. Further, a zirconia sprayed film having a thickness of about 275 μm was formed on those outer surfaces by plasma spraying zirconia. Then, the roller part and this rotating shaft part which completed this thermal spraying were joined. In this case, a pair of internal passages for supply and return are formed inside the rotating shaft portion, and cooling water is circulated through these internal passages. Furthermore, this top roll was installed in the vicinity as shown in FIG. 1 in the vicinity of both side edges of the glass ribbon in the float bath.

  In such a state, the top roll was used for 30 days, and the temperature change of the cooling water was measured. As a result, the top roll on which the metal spray film and the zirconia spray film were formed as described above was 0 on average. The top rolls on which the thermal spray film was not formed reached an average of 3.3 ° C., while the decrease was only 0.7 ° C. Therefore, the top roll with the zirconia sprayed film formed on the outermost layer has a small temperature drop, confirming the heat insulation effect due to the zirconia sprayed film, and this can also suppress the absorption of heat from the atmosphere in the float bath. confirmed.

  At the same time, it was confirmed that the claw portion and the glass ribbon in the roller portion of the top roll were not attached, and it was also confirmed by visual inspection that no peeling occurred on the zirconia sprayed film.

DESCRIPTION OF SYMBOLS 1 Glass plate manufacturing apparatus 2 Molten tin 3 Float bath 4 Molten glass 6 Glass ribbon 6a Side edge part 7 of glass ribbon Top roll 7a Roller part 7b Rotating shaft part

Claims (4)

When a molten glass is floated on molten tin stored in a float bath to form a glass ribbon, a roller portion that engages with a side edge surface of the glass ribbon, and a roller portion that is integrally connected to the roller portion and the roller portion A top roll having a rotating shaft portion formed therein with a cooling medium flow path for cooling the glass ribbon is disposed in the vicinity of both side edges of the glass ribbon, and the glass ribbon is used in the width direction by using the top rolls. In the glass plate manufacturing apparatus configured to pull outward on both sides,
The glass plate manufacturing apparatus characterized by coat | covering the outer surface of the said roller part and the said rotating shaft part in the said top roll with the zirconia.   The glass plate manufacturing apparatus according to claim 1, wherein the zirconia is coated by thermal spraying.   The glass plate manufacturing apparatus according to claim 1 or 2, wherein a coating thickness of the zirconia is 1-1000 µm. When a molten glass is floated on molten tin stored in a float bath to form a glass ribbon, a roller portion that engages with a side edge surface of the glass ribbon, and a roller portion that is integrally connected to the roller portion and the roller portion A top roll having a rotating shaft portion formed therein with a cooling medium flow path for cooling the glass ribbon is disposed in the vicinity of both side edges of the glass ribbon, and the glass ribbon is used in the width direction by using the top rolls. In the glass plate manufacturing method that pulls outward on both sides,
A method for producing a glass plate, comprising: using a top roll in which zirconia is coated on the outer surfaces of the roller portion and the rotating shaft portion, and pulling the glass ribbon outward in the width direction.

Images