KR20100015548A - Float bath device and method for producing flat glass - Google Patents

Abstract

The invention relates to a float bath device with a cover having at least one cover element (30, 32). A float bath (16) comprising liquid metal is present in a float bath tub (12) with a bottom wall (13) and side walls (14). The float bath device is used for the production of a glass sheet (28) floating on the float bath (16). The cover element (30, 32) is arranged in at least one partial region of the open float bath surface and has an intermediate space (36) spaced from the float bath level (17). The partial region is located between the glass sheet (28) and the side wall (14). Furthermore, a method for producing flat glass is proposed. The device (10) comprises a suction device with a suction line (40), wherein the suction opening (41) of the suction line (40) ends in the intermediate space (36).

Description

FLOAT BATH DEVICE AND METHOD FOR PRODUCING FLAT GLASS}

The present invention relates to a float bath device according to the preamble of claim 1 and a method for producing a pane according to the preamble of claim 46.

The production of sheet glass, the so-called float glass by the float process, has been known since the last century and is based on the protection rights which are substantially the basis of Pilkington (US Pat. No. 3,083,551, German Patent No. 147 19 50).

In the float process, the liquid glass taken from the working tank by the channel is poured onto a bath of molten metal, usually tin. The flow rate of the glass is regulated via the movable gate, and the setting of the movable gate also in particular controls the glass thickness. As can be seen in the flow direction of the glass, the gate is followed by a pouring spout in which the glass melt continues to flow over the metal bath, and the glass melt is molded and solidified to form a dimensionally stable glass ribbon. The solidified glass ribbon is then removed from the metal bath.

Float glass manufactured in this manner and generally less than 1.5 mm thick is used as a thin glass substrate, in particular flat screen displays such as plasma display panels (PDP), field emission displays (FED), TFT liquid crystal display screens (TFT = thin). film transistor), STN liquid crystal display screen (STN = super-twisted nematic), plasma enhanced liquid crystal (PALC) display, electroluminescent (EL) display, or the like, or a thin film solar cell.

In flat screen displays, depending on the type of display, a thin layer of liquid crystal compound is introduced between two glass sheets or a dielectric layer is attached on the front side of the back sheet and the back side of the front sheet, respectively. Form.

Here, it is important to precisely maintain the layer thickness of the liquid crystal layer or the thickness of the dielectric layer so that color perturbation defects or similar deflections do not occur, especially when the display screen has large dimensions. As the layer thickness (now about 30 μm) becomes smaller and the display screen becomes larger, this condition becomes increasingly important.

Float glass is well suited for display applications for today's larger substrate formats where edge lengths exceed 1800 mm due to its sparkle polished surface, but the production of display glass with a thickness difference of less than 50 μm by the float process is currently impossible.

One interpretation of the occurrence of thickness deviations in float glass is the presence of flow in the float bath. This very complex flow is the result of mutually inductive mechanical and thermally induced flows. As such, temperature management inside the float bath becomes very important.

The surface quality of the float glass is called the top flaw and is damaged by surface defects created by the attachment of tin containing particles such as tin or tin oxide particles on the glass ribbon when using a tin bath. Despite the fact that the forming gas (typically 12% H ₂ , 88% N ₂ ) is ejected inside, the atmosphere above the float bath contains the residual amount of oxygen entering the tin bath to form tin oxide particles. do. When the bath temperature increases, tin oxide or tin evaporates to enrich the atmosphere, with the result that particles containing tin can precipitate on the glass ribbon.

In order to avoid this surface defect, various measures must be taken to prevent a contaminated atmosphere on the glass ribbon. On the one hand, in particular, oxygen must not enter the inside of the float bath housing from the outside and on the other hand any existing oxygen must not contact the tin bath surface.

In order to prevent tin oxidation, Japanese Patent No. 11-278856 proposes to cover the open surface of the float bath with a plate, which is impermeable to O ₂ and withstands temperatures above 1300 ° C. Carbide, such as silicon carbide, has been proposed as the material.

The plate is placed directly on the tin bath surface such that there is no atmosphere under the lid. Since it is necessary to maintain a distance from the glass bath edge in the case of such a floating lid, there is an open surface area of the float bath next to the glass ribbon laterally where tin oxidation can occur as before.

From WO 2005-09792 it is known to inhale dust and thus tin oxide particles by means of suction tubes arranged on the sidewalls. The disadvantage of these suction tubes is that their range of action is extremely limited. In general, a significant suction effect is achieved at most at a circle of about 20 cm around the inlet of the suction tube. Thus, substantial portions of tin oxide or other contaminants in the atmosphere are not picked up.

U. S. Patent No. 3,494, 755 and German Patent No. 40 21 223 C2 describe a cover element disposed on the glass ribbon at a distance from the glass ribbon. In general, the width of the glass ribbon is larger than the width of the open surface of the tin bath in the left and right widths of the glass ribbon. Thus, the constructional outlay accompanying US Pat. No. 3,494,755 and German Patent No. 40 21 223 C2 is relatively large.

According to British Patent No. 1 217 047 a suction opening is arranged over the glass ribbon edge. In this structure, the flow towards the glass ribbon is set up in the shaping gas in the area directly above the open surface of the float bath. Thereby, the molding gas with the largest concentration of the evaporated gas containing metal is sucked toward the glass ribbon. In this known embodiment the risk of surface defects on the glass ribbon is thus relatively high.

It is therefore an object of the present invention to provide a float bath device in which the number and / or size of surface defects on the glass ribbon produced by the float process can be reduced. It is also an object of the present invention to provide a corresponding method for producing float glass.

The object is that the cover element is disposed in at least one subzone of the open surface of the float bath, is separated by a gap from the float bath surface while being located between the edge and sidewall of the glass ribbon, and is floated by at least one suction line. An apparatus is provided for sucking in the atmosphere contained in the bath apparatus, and the suction port of the suction line is achieved by the float bath apparatus that opens to the gap.

The term cover element is preferably intended to mean all elements that separate the float bath surface vertically from the space above it.

The separate structure of the cover element for forming a gap between the cover element and the float bath surface offers the possibility of setting the atmospheric flow as described in detail with respect to the pane manufacturing method.

Another advantage is that the atmosphere space contaminated with metal oxides, in particular, is limited to the gaps and therefore kept small.

Moreover, the flow rate under the lid element can be set much higher than is possible, for example when arranging the partition within the interior of the float bath housing. Due to the considerably high flow rate in the direction of the inlet, unwanted development of the contaminated atmosphere into the area above the glass ribbon can be better prevented than when using partitions.

Another advantage is that the lid does not interfere with the preview of the edge of the glass ribbon, in particular of the glass ribbon, during manufacture.

Another advantage of the lid according to the invention is that the contaminated atmosphere is prevented from rising from the open surface of the float bath and reaching the space above the glass ribbon. Thus, compared to patent 3,494,755 or German patent 40 21 223 C2, the associated construction outlay is much less.

By the suction device, the atmosphere substantially consisting of the molding gas is sucked into the gap from the inside of the float bath housing. Thereby, due to the flow generated in the gap, the particles in the entire area between the glass ribbon and the sidewalls are sucked up. Depending on how far the cover extends to the edge or even over the edge of the glass ribbon, horizontal flow also occurs at least over the subregions of the glass ribbon and in this way contaminated gas contained in the atmosphere above the glass ribbon. , Droplets and particles are also inhaled.

Another advantage is the improved suction effect and flow management, which requires less molding gas as a whole to prevent metal oxide formation or to remove contaminating gases, droplets and particles.

Preferably, the inlet is at a horizontal distance A ₇ of at least 100 mm from the glass ribbon edge in the direction of the nearest side wall. In particular, the distance A ₇ is at least 120 mm and particularly preferably at least 150 mm.

Preferably, the suction line is arranged on the side wall and / or the cover element.

Preferably, the covering element is made of quartz. Quartz has the advantage that it can be installed during operation, ie in a high temperature atmosphere, because of its good thermal cycle stability. An additional advantage lies in the mechanical stability and the properties that quartz is not thermally insulated and therefore does not cause any temperature difference inside the float bath housing.

Other materials suitable for the cover ceramics are, for example, mullite, silimite, SiC, Si ₃ N ₄ , AlTi, C, Al ₂ O ₃ or SiC coated graphite. An advantage that may be mentioned for the cover proposed here over the cover proposed in US Pat. No. 3,494,755 is that, with regard to wettability, the limitation with condensates of evaporated metals or metal oxides does not need to be considered here for material selection. .

According to a first embodiment, the cover element has at least one support seated on the bottom wall. The length of the support is chosen such that a desired gap is maintained between the float bath surface and the bottom surface of the lid element.

According to a second embodiment, the cover element has at least one float, which floats away from the float bath while the cover element floats on the float bath. The size of the float and its buoyancy are selected to maintain the desired distance of the cover element from the float bath surface.

It is preferable that both the support part and the floating body consist of mullite. Other preferred materials are SiC coated graphite, quartz, chamotte, Al ₂ O ₃ or ceramics that can be used for the covering.

In particular, the lid element provided with the float is preferably fixed by a holding device. Otherwise, displacement of the lid element may occur due to the inevitable flow in the float bath.

Preferably, the cover element extends as far as the side wall. This prevents the return flow of the atmospheric gas, in particular in the direction of the float bath top and the glass ribbon.

Preferably, the lid element is supported on the side wall to create a seal. This embodiment effectively prevents oxygen penetrating through the sidewalls and penetrating into the sidewalls in contact with the metal bath to generate metal oxide particles.

According to another embodiment, the cover element is held between the side wall casing and the side wall of the float bath tank. The lid element can be clamped, for example, between the side wall casing and the side wall.

In another embodiment, the cover element is suspended from the top wall of the float bath housing.

Preferably, the distance (A ₁₎ between the edge of the edge and the cover factor of the glass ribbon is 0≤A ₁ ≤500 mm.

Particular preference is given to a distance A ₁ which results in 150 mm ≦ A ₁ ≦ 300 mm, in particular 200 mm ≦ A ₁ ≦ 300 mm.

Preferred embodiments of the cover element are cover plates and cover screens. The distance A ₂ between the bottom face of the cover plate and the float bath surface is preferably 25 to 100 mm, particularly preferably 50 mm to 100 mm. Through the distance from the cover plate to the float bath surface, in the case of the desired suction output of the suction device to be described in connection with the float bath device, it is possible to adjust the flow rate in this gap.

According to another embodiment, it is possible to arrange the cover element at a distance A ₅ from the side wall. However, distance A ₅ avoids the evaporation of the metal or metal oxide evaporated from the open surface of the float bath into the area above the cover element and finally into the area above the glass ribbon in the area between the side wall and the cover element. Should not be chosen to be larger than distance A ₁ . In this embodiment, the inlet of the suction line opens into the gap between the float bath surface and the cover element.

In all embodiments of the cover element, it should be noted that the relevant intake is at a horizontal distance A ₇ from the edge of the glass ribbon, which is preferably at least 100 mm. Horizontal distance A ₇ represents the distance of the inlet from the glass ribbon edge in the direction of the nearest sidewall.

The cover shade can be configured in the form of a house roof or half pyramid, and can be used as a cover, especially where the suction tube of the suction device is open into the inside of the float bath housing. The gap under the cover shade is much larger than the gap under the cover plate.

Preferably, the distance between at least two adjacent cover elements disposed along the side wall is 0 ≦ A ₆ ≦ 500 mm.

At least two adjacent cover elements disposed along the side wall may directly contact each other.

The cover element covers at least 50% of the open surface of the float bath in the float bath section.

The cover element is preferably arranged in at least one float bath section in the hot zone of the float bath.

The covering element is preferably arranged over at least 50% of the length of the float bath in the hot zone of the float bath.

The distance between two adjacent cover elements, ie cover elements arranged along the same side wall, should be as small as possible. Preferably, the cover elements should be hermetically connected to one another. In embodiments where the cover elements are apart, the distance A ₆ between adjacent cover elements should not be greater than the distance A ₁ between the edge of the glass ribbon and the cover element.

Preferably, at least 50% of the open surface of the metal in the float bath section is covered by the cover element. The covering element preferably covers at least 75%, in particular all of the open surface of the metal in the float bath section.

The term "covered" surface is preferably intended to mean the surface area provided by the vertical protrusion of the covering element surface on the open surface of the metal.

In this structure of the inlet, the shaping gas atmosphere is sucked over the entire metal bath surface such that no contaminating particles can accumulate and possibly no upward space can be formed inside the float bath housing. From there, the particles generally descend back in the middle of the housing and accumulate on the glass ribbon. Preferably the installation of the cover element in the hot front zone of the float bath and the suction of a large area at least in the hot zone, optionally the installation of the cover element along the entire length of the side wall, in particular over both side walls, prevent this harmful action, The so-called top flaw is thus significantly reduced.

Preferably, at least one suction line is arranged in the side wall casing which can be fitted to the side wall. Placing the suction tube (s) on the sidewalls allows for quick replacement of the suction tube, for example if a small or large tube cross section or a large or small number of suction tubes is required. Such adaptation may be necessary where it is convenient to change the temperature condition in the float bath housing in certain circumstances.

Preferably, the inlet is a slit opening extending in the horizontal direction.

The advantage of the slit opening is that the shaping gas atmosphere is drawn from a large continuous zone above the float bath. In the shaping gas atmosphere contaminant gases, droplets and particles are more completely removed from the shaping gas atmosphere more effectively than in the case of a round suction tube which is disposed and distributed over a significant distance along the sidewall of the float bath housing.

Such a slit type inlet is provided above the float bath surface to provide the possibility of directly sucking the atmosphere from the gap between the float bath surface and the bottom surface of the cover element without providing the necessary cover shade for round suction tubes with relatively large cross sections. It can be placed at short distances.

Another advantage is that the slit nozzle produces a uniform flow over the entire length of the slit opening, from the gap between the cover element and the float bath surface to other areas of the float bath atmosphere, thus potentially into the area above the glass ribbon. Local return flow is prevented.

Preferably, at least one slit opening is arranged in each of the two opposing side walls in the at least one float bath section. Preferably this is at least one float bath zone in the zone of the float bath where the highest temperature occurs. Preferably, at least one slit opening is present in each of the two related opposing side walls. The effect achieved thereby is that the flow is established just above both sides of the glass ribbon starting from the middle of the glass ribbon and in each case to the gap below the cover element closest to and to the open surface of the float bath. In particular, in the area immediately above the glass ribbon edge and in the open surface of the metal, the flow is directed to the gap below the lid element, respectively, away from the glass ribbon. According to that purpose, this substantially prevents the evaporated metal containing gas and contaminating particles from being transferred from the forming gas zone with the high concentration of evaporating gas into the zone above the glass ribbon.

Preferably, the cover element and / or the slit openings are arranged in at least the first two float bath sections. In the float bath section where the hot forming takes place (ie in particular float bath sections 1, 2, and optionally float bath section 3), the temperature of the float bath is such that the floating of the atmosphere with contaminating particles is the largest therein. To be the highest. By suction through the slit openings in these float bath sections, the decontamination effect of the atmosphere can be significantly increased.

Preferably, at least two slit openings are arranged side by side in the horizontal direction.

The distance between the two slit openings should be minimized as much as possible and smaller than 10 cm so as not to allow dead space that contaminants cannot be affected by suction.

Preferably, the slit opening extends over at least 50% of the length of the float bath section in its entirety. Preferably, the slit opening extends over at least 70%, particularly preferably at least 80% of the length of the float bath section.

Preferably, the slit opening extends over at least 30% of the length of the float bath in its entirety. Preferably the slit opening extends over at least 50%, in particular 80% of the length of the entire float bath.

Preferably, the horizontal length of the slit opening is between 30 cm and 150 cm.

The cross-sectional area of the slit openings is advantageously 20 to 40 cm ² . This means that in the case of the length of the claimed slit opening, the vertical width of the slit opening may be in the range of 2 to 10 mm. When following this value, a uniform flow is maintained inside the slit opening over the entire length of the slit opening.

The slit openings should be placed as close as possible on the surface of the metal bath to inhale all the particles as much as possible.

The lower edge of the slit opening is disposed 4 cm to 8 cm above the surface of the float bath.

Preferably, the suction line in the side wall has an inclination from inside to outside. This has the advantage that particles condensed in the suction line flow outwards and thus do not contaminate the metal bath.

Preferably, the suction line has a slit nozzle. The slit nozzle is substantially triangular in plan view. In the outward direction, the cross section is tapered and merged into the cross section of the connected suction line. In the side view, the cross section widens starting from the slit opening at the transition point to the cross section of the connected suction line. The slit nozzle may be a separate component or integrally formed in the suction tube forming the suction line.

Slitted nozzles can be placed at a small distance above the float bath surface, which offers the possibility of drawing gas atmosphere just above the float bath.

In the case of slit nozzles, the pressure loss can be kept as small as possible and 14 ° to 40 degrees for taper to ensure uniform flow inside the slit nozzle over the slit length to avoid dead space where there is a risk of condensation accumulation. °, preferably a hole angle α of 18 ° to 35 °, particularly preferably 20 ° to 30 °, and 2 ° to 10 °, preferably 3 ° to 8 °, particularly preferably 5 to widen It is preferable to merge the hole angle β of ° to 7 °. Here, the angle α is the angle between the conically converging sidewalls of the slit nozzle in the plan view, and the angle β is the angle between the sidewalls of the slit nozzle in the side view.

Preferably, the slit nozzle is disposed in the side wall casing.

The side wall casing has at least two molded bricks, which are at least defining the slit nozzle, made of a fire resistant material. In this case, the slit nozzle is formed integrally with the forming brick, and the separating line between the two forming bricks preferably extends through the slit nozzle.

Preferably, the plurality of suction lines are batch distributed along the two side walls. The suction output through the suction line can preferably be individually adjusted via the corresponding suction means. This embodiment provides the advantage that different temperature conditions inside the float bath housing can be adapted in an easy manner. For example, a larger gas volume per unit time may be sucked in the hot zone than is required in the cold section.

The placement of a suction line or a plurality of suction lines in the side wall casing allows for rapid replacement of the suction line, for example if a small or large cross section or a large or small number of suction lines are required in the associated side wall area. Such adaptation may be necessary when it is convenient to change the temperature state in the float bath housing, and hence the concentration of particles, in certain circumstances.

Preferably, the suction means comprises at least one injector pump for generating a reduced pressure at the output of the suction line.

The injector pump consists of two tubes with two inputs and one output and fitted substantially together, which are called inner and outer tubes. The inner tube terminates in the outer tube and has a discharge nozzle. The suction fluid enters from the discharge nozzle at the line maximum pressure from the second input, with the fluid to be sucked, ie the forming gas atmosphere. This is done based on the generated pressure reduction. For example, a water pump functions according to this principle.

The suction output of the injector pump can be easily adjusted with high accuracy via the pressure of the suction fluid, allowing the desired adaptation to particles of different concentrations inside the float bath housing. Precision is ± 5 m ³ (stp) / h. The term m ³ (stp) is intended to mean standard cubic meters as defined in DIN 1343. A standard cubic meter is the amount corresponding to a cubic meter of gas at a pressure of 1.01325 bar (absolute value), 0% air humidity (dry) and at a temperature of 0 ° C.

Preferably, the injector pump is operated by compressed air as intake fluid. Thus, the injector pump is preferably connected to at least one compressed air generator.

Moreover, the compressed air generator is connected to a control device that controls the pressure of the compressed air, or the compressed air generator includes such a control device.

It is also possible for a control device to control the pressure of the compressed air to be arranged between the injector pump and the compressed air generator. Such a control device may for example be a compressed air valve. Preferably, such a compressed air valve is arranged before every injector pump so that each injector pump can be adjusted individually.

One or more suction lines may be connected to the injector pump. If the suction output of each float bath section is intended to be adjusted individually, a grouped structure of suction lines may be recommended. If a plurality of suction lines are provided in the float bath section, through which a individually regulated amount of gas is intended to be sucked in per unit time, each suction line is preferably connected to its own injector pump.

The control device is preferably connected to at least one temperature sensor disposed inside the float bath housing. Accordingly, the corresponding temperature change can be switched directly by the control device to the relevant suction output necessary to ensure optimal particle intake.

Preferably, the cover shade is arranged in the region of the inlet of the suction tube, which is particularly advantageous when the opening diameter of the suction tube is larger than the distance of the cover plate from the float bath surface.

The panes produced in the float bath apparatus according to the invention have a much smaller number of surface defects. the number of surface defects per m ² Average 50 - 100 at the upper inclusions / m ² was reduced to 0-20 upper inclusions / m ^2. Moreover, it was found that the size distribution of the surface defects changed to a small diameter.

In such float bath apparatus a method for producing panes, in particular TFT glass, covers at least a part of the open surface of the bath located between the edges of the glass ribbon and adjacent sidewalls by means of a lid to form a gap, and the flow of atmosphere within the gap. It characterized in that to generate.

This flow has at least a possible return flow from the gap back to the other zones of the float bath atmosphere.

The flow is directed away from the glass ribbon such that droplets or particles formed from these gases by vaporization of the metal or metal oxide and condensation, solidification, sublimation, or by chemical action with other contaminants are sucked from the glass ribbon surface. desirable.

The atmosphere is sucked out of the gap so that it cannot flow back inside.

Preferably, the average speed of the flow at the entry edge into the gap between the cover element and the open surface of the float bath is set between 0.1 m / s and 10 m / s.

Preferably, the atmosphere is sucked through the slit in the horizontal direction.

Preferably, the atmosphere is sucked at a plurality of locations along the sidewalls.

It is preferable to perform the suction at a plurality of positions along the float bath apparatus, and the shaping gas atmosphere is sucked through the slit in at least two float bath sections (compartments) of the float bath tank.

Preferably, the shaping gas atmosphere is preferably sucked over at least 50%, in particular at least 70%, particularly preferably at least 80% of the float bath length at both sidewalls of the float bath housing.

Moreover, the amount of gas sucked per unit time in each float bath section is advantageously adjusted as a function of the temperature of the float bath section.

The method is for example for fireproof applications (all data below are based on oxides by weight) SiO ₂ 70-85, B ₂ O ₃ 7-13, Na ₂ O + K ₂ O + Li ₂ O 3-8 To prepare a borosilicate glass having a composition of MgO + CaO + SrO 0-3, Al ₂ O ₃ 2-7,

SiO ₂ 50-70, B ₂ O ₃ ≤ 15, Al ₂ O ₃ 10-25, MgO 0-10, CaO 0-12, SrO 0-12, BaO 0-15, MgO + CaO + SiO + BaO 8- 26, ZnO 0-10, ZrO ₂ 0-5, TiO ₂ 0-5, to prepare an alkali-glass alumino (boro) silicate glass having a composition of SnO ₂ 0-2,

For example, SiO ₂ > 55-65, B ₂ O ₃ 5-11, Al ₂ O ₃ > 14-25, MgO 0-8, CaO 0-8, SrO 0-8, BaO≤10, MgO + CaO + Composition of SrO + BaO 8-21, ZnO 0-5, ZrO ₂ 0-2, TiO ₂ 0-3, SnO ₂ 0-2,

Especially SiO ₂ > 58-65, B ₂ O ₃ > 6-10.5, Al ₂ O ₃ > 14-25, MgO 0- <3, CaO 0-9, BaO> 3-8, MgO + CaO + BaO 8- 18, ZnO 0- <2, As ₂ O ₃ -glass, Sb ₂ O ₃ -glass (preferably free of Zn oxide, Ce oxide, Zr oxide and Ti oxide) to prepare a display glass Particularly suitable for

The method also includes, for example, SiO ₂ 55-69, Al ₂ O ₃ 19-25, Li ₂ O 3-5, Na ₂ O 0-1.5, K ₂ O 0-1.5, ∑Na ₂ O + K ₂ O 0.2 -2, MgO 0.1-2.2, CaO 0-15, SrO 0-1.5, BaO 0-2.5, ∑MgO + CaO + SrO + BaO, ZnO 0-1.5, TiO ₂ 1-5, ZrO ₂ 1- 2.5, SnO ₂ 0- <1, ∑TiO ₂ + SrO ₂ + SnO ₂ 2.5-5, to produce a variety of green glass for glass ceramic having a composition of P ₂ O ₅ 0-3,

Or SiO ₂ 55-75, Al ₂ O ₃ 15-30, Li ₂ O 2.5-6, ∑Na ₂ O + K ₂ O less than 6, ∑MgO + CaO + SrO + BaO less than 6, B ₂ O ₃ To prepare a glass-ceramic precursor glass having a composition of ∑TiO ₂ + ZrO ₂ of 0- <4, 2,

Or SiO ₂ 60-72, Al ₂ O ₃ 18-28, Li ₂ O 3-6, ∑Na ₂ O + K ₂ O 0.2-2, ∑MgO + CaO + Sro + BaO, ZnO 0-1.5 , B ₂ O ₃ 0- <4, SnO 0.1-1.5, to prepare a glass-ceramic precursor glass having a composition of ∑TiO ₂ + ZrO ₂ , P ₂ O ₅ 0-3, F 0-2 of less than ₂ Especially suitable.

Exemplary embodiments of the invention are described in more detail below with reference to the drawings.

1 is a plan view of a float bath with glass ribbon and lid.

FIG. 2A shows a cross section along line A-A of the float bath tank shown in FIG. 1, with the roof of the float bath also shown.

FIG. 2 shows a cross section along line B-B of the float bath tank shown in FIG. 1, with the roof of the float bath also shown.

3 shows an enlarged cross-sectional view of the lid.

4 is an enlarged cross-sectional view of a lid according to another embodiment.

5 shows a part of the lid according to the invention in a perspective view.

FIG. 6 shows a cross section along line C-C of the lid shown in FIG. 5.

7 shows a top view of a float bath with a glass ribbon and suction device.

8 shows a side view of a detail portion of the side wall of the float bath housing.

FIG. 9 shows a cross section along line D-D in FIG. 8.

9A illustrates a cross section corresponding to FIG. 9, according to another embodiment.

10 illustrates a cross section corresponding to FIG. 9, according to another embodiment.

11 shows a perspective view of the side wall casing.

FIG. 12 shows a cross-sectional view of the slit nozzle shown in FIG. 11.

FIG. 13 shows a partial vertical cross section through the edge of a float bath apparatus with an injector pump.

14 illustrates a top view of a detail portion of the float bath of FIG. 1, according to another embodiment.

15 is an enlarged cross-sectional view of a lid according to another embodiment.

1 shows a plan view of a float bath tank 12 divided into float bath sections provided with so-called partition numbers 1 to 8. The float bath tank 12 is filled with a float bath 16 of liquid metal, in particular tin. The glass ribbon 28 extracted in the direction of the arrow floats on the float bath 16. The area between the edge 29 of the glass ribbon 28 and the side wall 14 of the float bath tank 12 is covered by a cover. This cover consists of a cover element in the form of a cover plate 30. A suction line 40 of the suction device is also provided on the side wall 14.

FIG. 2A is shown through a cross section along line AA of the float bath tank 12 of the float bath device 10 shown in FIG. 1 and through a float bath roof 18 having an upper wall 19 and a side wall 20. Showing the cross section. The upper wall 19 is provided with a molding gas supply part 22 through which molding gas is introduced into the float bath apparatus 10.

In addition to the illustration of FIG. 1, the upper roller 26 required to pull the glass ribbon 28 in the direction perpendicular to the moving direction of the glass ribbon 28 is indicated. It can be seen that the cover plate 30 is disposed below the upper roller axis. Furthermore, it can be seen that the edge of the lid element 30 is arranged at a distance from the edge 29 of the glass ribbon 28.

The cover plate 30 is disposed at a distance from the float bath surface 17 such that a gap 36 is formed between the float bath surface 17 and the bottom surface of the cover plate 30.

FIG. 2B shows a cross section along line BB of the float bath tank 12 shown in FIG. 1, which extends through a suction tube disposed in the side wall casing 24 to form a suction line 40. . Since the suction tube is located at a greater distance from the float bath surface than the gap 36 allows, a special cover element is provided in the form of a cover shade 32 that allows the suction tube to connect to the gap 36. .

3 shows an enlarged view of the cover plate 30. Also shown is the distance A ₁ between the edge 34 of the cover plate 30 and the edge 29 of the glass ribbon 28. The distance between the float bath surface 17 and the bottom face of the lid element 30 is indicated as A ₂ . Due to the distance A ₁ , the edge 29 of the glass ribbon 28 can be observed during manufacture, for example by a camera, which is sometimes important for the manufacturing process.

However, if the particular flow indicated by the arrow is also intended to be set in the gap or gap 36, the cover plate 30 may extend to or above the glass ribbon 28. In the embodiment shown in FIG. 3, the cover plate 30 has a support 38 seated on the bottom wall 13 of the float bath tank 12. The length of this support 38 is chosen to maintain the desired distance A ₂ .

4 shows another embodiment, wherein the cover plate 30 is provided with a float 39 so that the cover plate floats at a predetermined distance A ₂ on the tin bath 16. For fixing, a holding device 31 for pressing the cover plate 30 from above is provided and fixed to the side wall 14.

5 shows a perspective view of a detail portion of the lid. In addition to the cover plate 30 held between the side wall 14 and the side wall casing 24, a cover shade 32 is shown which consists of some form of a pyramid and consists essentially of two upright triangular plates. This allows the suction line 40 disposed in the sidewall casing 24 to be positioned at a greater distance from the float bath surface 17 but still maintains the connection between the gap 36 and the cover plate 30, thereby providing a gap 36. ) You can inhale the atmosphere out.

6 shows a cross section along line C-C of the apparatus shown in FIG. 5. A gap 36 under the cover plate 30 continues into a gap 36 'under the cover shade 32, from the gap 36 to the gap 36' and through the inlet 41 therein. Allow flow to 40.

7 again shows a top view of the float bath tank 12 in order to illustrate the suction device 50. The suction line 40 of the suction device 50 in the form of a suction tube is arranged in the side wall of the float bath device 10, only a portion of the suction line 40 is shown for clarity. In general, a suction line 40 is indicated on the right side wall of compartment number 2 for another suction line, which is an injector pump supplied by the compressed air generator 80 via the compressed air line 69. 60). In order to control the compressed air, a control valve 84 is provided as a control device before the injector pump 60. The control valve 84 can be controlled manually or electrically.

Suction line 40 is likewise indicated in compartment number 3 and two suction lines 40 are indicated in compartment number 4. Two suction lines 40 of the compartment 4 are connected to a common injector pump 60. Two injector pumps 60 for the compartment 3 and the compartment 4 are connected to the compressed air generator 80 via a common compressed air line 69, which is the control device 82. Is electrically connected to the This control device 82 is connected to a temperature measuring sensor 70 via an electrical connection line 72, which is arranged inside the side wall 14 of the float bath housing 11. The embodiment shown in FIG. 1 merely illustrates the application of the control valve 84 and the control device 82 as well as the suction line 40 and the injector pump 60.

8 shows a detail of the side wall 20 of the float bath housing 11. This figure is a side view of the inner surface of the side wall 20 consisting of side wall casing 24 disposed on the side wall 14 of the float bath tank in the region shown. Each side wall casing 24 has a slit inlet 41. The suction inlets 41 of the suction type are arranged close together with a spacing of less than 10 cm and placed close to the surface 17 of the metal bath 16 at a distance of about 5 cm. The intake port 41 is arranged in the lower region of the side wall casing. The compact structure of the inlet 41 in the form of a slit has the advantage that the molded air atmosphere can be sucked over substantially the entire area of the side wall without creating dead spaces where contaminating particles can accumulate.

FIG. 9 shows a cross section along line D-D of the side wall 20 shown in FIG. 8. The slit type suction port 41 belongs to the suction line 40 which tapers the cross section of the outer suction tube 53 with respect to the cross section.

FIG. 9A shows another embodiment with respect to the cross section, widening in the vertical direction at an angle β with respect to the cross section of the outer suction tube 53.

10 shows another embodiment in which the suction line 40 has an outward slope inside the sidewall casing 24. The sucked particles may condense inside the sidewall casing 24, thereby forming droplets inside the suction line 40. Due to the gradient, these condensed particles cannot again migrate into the float bath housing 11 and hence the metal bath 16. Rather, this condensed droplet flows outward into the outer suction tube 53.

11 shows a perspective view of the side wall casing 24, in which the side wall casing is formed by two fire resistant molded bricks 123, 124. In these bricks 123 and 124, the slit nozzle 42 is integrally formed. The dividing line 125 on the two forming bricks 123, 124 extends through the slit nozzle, which provides a corresponding advantageous manufacturing technique. 12 is a cross sectional view of the slit nozzle 42. It can be seen that the hole angle α of the slit nozzle 42 is formed by two boundary walls of the slit nozzle 42. In the embodiment shown here, this angle is α = 20 °.

FIG. 13 shows a partial longitudinal section of a float bath tank 12 having a bottom wall 13 and a side wall 14. Side wall casing 24 with suction line 40 is shown on side wall 14 of float bath tank 12.

The suction line 40 is opened from the inside of the float bath 16 to the inside of the float bath housing 11. In the outward direction, the suction line 40 opens to the injector pump 60, which consists of an outer tube 62 and an inner tube 64, with a nozzle 66 arranged on the upper end of the inner tube. The inner tube 64 is connected to the compressed air generator 80, which in turn is electrically connected to the control device 82. Via the electrical connection line 72, the control device 82 is connected to a temperature measuring sensor 70 arranged inside the wall 20. Compressed air generated in the compressed air generator 80 flows into the inner tube 64 and then flows out of the nozzle 66 into the outer tube 62. As a result, pressure is generated in the outer tube 62 in the region in which the suction line 40 is opened, whereby the forming gas atmosphere is sucked from the inside of the float bath housing 11. Compressed air and gaseous atmosphere are extracted upward together through the outflow tube 68 from the inside of the float bath housing 11.

14 shows a plan view of a detail of the float bath according to FIG. 1 in another embodiment. Here, adjacent cover elements 30 are arranged at a distance A ₆ from each other.

15 shows a cross section through the cover element 30. The cover element 30 is arranged at a distance A ₂ from the float bath surface 17. The lid element 30 is also fitted at a distance A5 from the side wall casing 24. The inlet opening 41 opening into the gap between the lid element 30 and the float bath surface 17 is at a distance A ₇ from the glass ribbon edge 29.

Reference number

1 to 8: compartment number

10: float bath device

11: float bathtub housing

12: float bath tank

13: floor wall

14: sidewall

16: float bathtub

17: float bath surface

18: float bath roof

19: upper wall

20: sidewall

22: forming gas supply unit

26: upper roller

28: glass ribbon

29: glass ribbon edge

30: cover plate

31: retaining device

32: Cover shade

34: Edge of cover plate

36, 36 ': clearance

38: support

39: floating body

40: suction line

41: inlet

42: slit nozzle

50: suction device

53: outer suction tube

60: injector pump

62: outer tube

64: inner tube

66: nozzle

68: outflow tube

69: compressed air line

70: temperature measuring sensor

72: electrical connection line

80: compressed air generator

82: control unit

84: control valve

123, 124: forming brick

125: dividing line

A ₁ : Distance between glass ribbon edge and cover plate edge

A ₂ : Distance between float bath surface and bottom surface

A ₅ : distance between cover element and sidewall

A ₆ : Distance between cover element and cover element

A ₇ : Distance between cover element and inlet

Claims (54)

Float bath apparatus 10, comprising a float bath tank 12, a float bath roof 18, and sidewalls 14, 20, the float bath tank 12 having a glass ribbon floating on the float bath 16. Float bath apparatus 10 for receiving a float bath 16 of liquid metal to produce 28 and having at least one lid of a float bath 16 having at least one lid element 30, 32. To The cover element 30, 32 is disposed in at least one subzone of the open surface of the float bath and is located between the edge 29 and the sidewall 14 of the glass ribbon 28 and the float bath surface 17. Separated by a gap 36 from A device is provided for sucking in the atmosphere contained in the float bath device 10 by at least one suction line 40, and the suction port 41 of the suction line 40 is opened to the gap 36. Float bath device. The float bath device according to claim 1, wherein the inlet is at a horizontal distance A ₇ of at least 100 mm from the glass ribbon edge in the direction of the nearest side wall. 3. Float bath device according to claim 1 or 2, characterized in that the suction line (40) is arranged on at least one of the side walls (14) and the cover elements (30, 32). 4. Float bath device according to any of the preceding claims, characterized in that the covering elements (30, 32) are made of quartz. 5. The float bath device as claimed in claim 1, wherein the cover element comprises at least one support 38 seated on a bottom wall. 6. 6. The float bath device according to claim 5, wherein said support portion (38) is made of mullite. The cover element (30, 32) according to any one of the preceding claims, wherein the cover elements (30, 32) have at least one float (39), by which the cover elements (30, 32) are floated. Float tub device, floating on (16), away from the float bath. 8. Float bath device according to claim 7, characterized in that the float (39) is made of mullite. 9. Float bath apparatus according to any of the preceding claims, characterized in that the cover element (30, 32) is fixed by a retaining device (31). 10. Float bath device according to any of the preceding claims, characterized in that the covering element (30, 32) extends as far as the side wall (14). The float bath device according to claim 10, wherein the cover element (30, 32) is supported on the side wall (14) to create a seal. 5. The float bath according to claim 1, wherein the cover elements 30, 32 are held between the side wall casing 24 and the side wall 14 of the float bath tank 12. 6. Device. 5. The float bath device as claimed in claim 1, wherein the cover element is suspended from the top wall of the float bath housing. 6. Claim 1 to claim 13 according to any one of, wherein the glass ribbon (28) the distance (A ₁₎ between the edge 29 and the cover element (30, 32) edge 34 of the 0≤A ₁ ≤500 It is mm, The float bathtub apparatus characterized by the above-mentioned. The float bath device according to claim 1, wherein the cover element is a cover plate. The float bath device according to claim 1, wherein the distance A ₂ between the bottom surface of the cover plate and the float bath surface 17 is between 25 and 100 mm. Claim 1 to claim 16, wherein according to any one of, wherein the side wall 14 and the cover element float bath apparatus of the distance (A ₅₎ is characterized in that the 0≤A ₅ ≤500 mm between 30,32. 18. Float bath device according to any of the preceding claims, characterized in that the cover element is a cover shade (32). The float bath apparatus according to claim 1, wherein the distance between at least two adjacent covering elements 30, 32 arranged along the side wall 14 is 0 ≦ A ₆ ≦ 500 mm. . 20. The float bath device according to claim 1, wherein at least two adjacent covering elements (30, 32) arranged along the side wall (14) are in direct contact with one another. The float bath according to claim 1, wherein the cover elements 30, 32 cover at least 50% of the open surface of the float bath in the float bath sections 1 to 8. Device. 22. The cover element according to claim 1, characterized in that the cover elements 30, 32 are arranged in at least one float bath section 1 to 8 in the hot zone of the float bath 16. Float bath device. 23. The cover element according to claim 1, wherein the cover elements 30, 32 are arranged over at least 50% of the length of the float bath 16 in the hot zone of the float bath 16. Float bathtub device characterized by the above-mentioned. 24. The float bath apparatus according to any one of the preceding claims, characterized in that at least one suction line (40) is arranged in the side wall casing (24) which can be fitted to the side wall (14). The float bath device according to claim 1, wherein the suction port is a slit opening extending in the horizontal direction. 26. The at least one slit opening 41 is arranged in each of the two opposing side walls 14, 20 in at least one float bath section 1 to 8. Float bathtub device. The float bath device according to claim 26, wherein at least one of the cover element (30, 32) and the slit opening (41) is arranged in at least the first two float bath sections (1, 2). 28. The float bath apparatus according to any of claims 25 to 27, wherein at least two slit openings (41) are arranged side by side in the horizontal direction. 29. The float bath device according to claim 25, wherein the slit opening (41) extends over at least 50% of the length of the float bath section (1-8). 30. The float bath device according to any one of claims 25 to 29, wherein the slit opening (41) extends over at least 30% of the length of the float bath (16). 31. The float bath apparatus according to any one of claims 25 to 30, wherein the horizontal length of the slit opening (41) is 30 cm to 150 cm. 32. The float bath apparatus according to any one of claims 25 to 31, wherein the slit opening (41) has a cross-sectional area of 20 to 40 cm ² . 33. The float bath apparatus according to any one of claims 25 to 32, wherein the lower edge of the slit opening 34 is disposed 4 cm to 8 cm above the surface 17 of the float bath 16. . 34. The float bath apparatus according to any one of claims 1 to 33, wherein the suction line (40) in the side wall (20) has an inclination from the inside to the outside. 35. A float bath apparatus according to any one of claims 25 to 34, wherein said suction line (40) has a slit nozzle (42) with a slit opening (34). 36. The slit nozzle (42) according to claim 35, wherein the slit nozzle (42) has an angle (alpha) between 14 and 40 degrees between the conically converging side walls of the slit nozzle in plan view, and 2 degrees between the side walls of the slit nozzle in side view. Float bath device, characterized in that it has an angle (β) of 10 to 10 degrees. 37. The float bath apparatus according to claim 35 or 36, wherein the slit nozzle (42) is disposed in a side wall casing (24). 38. The float bath apparatus of claim 37, wherein the side wall casing (24) comprises at least two forming bricks (123, 124) defining at least a slit nozzle (42). 39. The float bath according to any one of the preceding claims, characterized in that the suction means (50) comprises at least one injector pump (60) for generating a reduced pressure at the output of the suction line (40). Device. 40. The float bath device according to claim 39, wherein the injector pump (60) is connected to at least one compressed air generator (80). 41. The float according to claim 40, wherein said compressed air generator (80) has at least one control device (82) or is connected to at least one such control device (82) for controlling the pressure of the compressed air. Bathtub device. 42. The apparatus according to any one of claims 39 to 41, wherein at least one control device (82) is arranged between the injector pump (60) and the compressed air generator (80) for controlling the pressure of the compressed air. Float bathtub device. 43. The float bath device according to claim 42, wherein the control device (82) is a control valve (84). 44. The float bath device according to claim 42 or 43, characterized in that the control device (82) is connected to at least one temperature sensor (70) disposed inside the float bath housing (11). 45. The float bath device according to any one of the preceding claims, characterized in that the cover shade (32) is arranged in the region of the inlet (41) of the suction tube (40). A method of manufacturing a plate glass, in particular a TFT glass, wherein the plate glass manufacturing method of pouring a liquid glass onto a float bath with a liquid metal in a float bath device having side walls in a molding gas atmosphere, At least a part of the open surface of the bath located between the edge of the glass ribbon and the adjacent sidewall by a lid to form a gap, and generate a flow of atmosphere in the gap. 47. The method of claim 46, wherein the flow is directed away from the glass ribbon. 48. The method of claim 46 or 47, wherein the atmosphere is sucked from the gap. 49. The method of claim 46, wherein the average velocity of flow at the entry edge into the gap between the lid element and the open surface of the float bath is set between 0.1 m / s and 10 m / s. Plate glass manufacturing method made with. The method according to any one of claims 46 to 49, wherein the atmosphere is sucked through the slit in the horizontal direction. 51. The method of any of claims 46-50, wherein the atmosphere is sucked at a plurality of locations along the sidewalls. 52. A method according to any one of claims 46 to 51, wherein the atmosphere is sucked through the slit in at least two float bath sections (compartments) of the float bath housing. 53. The method of any of claims 46-52, wherein the atmosphere is sucked over at least 50% of the float bath length. 55. The method of claim 46, wherein the amount of gas sucked per unit time in each float bath section is controlled as a function of temperature of the float bath section.

Images