Method and apparatus for drawing thin glass ribbons

Abstract

This invention relates to a method for drawing thin glass strips from molten glass using an apparatus having a nozzle including a protrusion that reacts to the contraction of the glass strip. The apparatus has a drawing groove for receiving the molten glass, the drawing groove having a nozzle including a through opening through which the molten glass can be discharged downwards. The through opening is configured as a nozzle slit with two ends, wherein the length of the nozzle slit is greater than its width. The nozzle slit curves downwards, particularly continuously or coherently, towards its ends in a first and second side region, such that the ends are lower than the middle region of the nozzle slit arranged between the ends, and wherein the width of the nozzle slit changes from the middle towards the ends.

Description

Technical Field

[0001] The present invention relates to an apparatus for drawing glass strips from molten glass, wherein the apparatus has a drawing groove for receiving molten glass, the drawing groove having a nozzle having a through opening through which the molten glass can flow downward, wherein the through opening is slit-shaped and forms a nozzle slit, the nozzle slit being curved in at least one direction in at least one lateral region. Background Technology

[0002] Mass production of very thin glass, such as glass with a thickness of less than 250 μm, remains a particular challenge, especially when high requirements are placed on surface quality, maximum thickness variation, and uniform width. One feasible approach to manufacturing very thin glass is, for example, the production of thin glass ribbons using a so-called down-drawing method.

[0003] The standard downdraw method uses a slit nozzle to manufacture thin, flat glass. In this process, molten glass in a melting bath is guided through a piping system and, after various process steps, is fed into a drawing trough. The lower end of the drawing trough is formed by a slit nozzle, through which the glass flows out and is drawn downwards by drawing rollers. The drawing speed is used to set the final thickness of the thin glass strip to be manufactured. The faster the glass is drawn downwards, the thinner it becomes. The slit width also affects the glass thickness.

[0004] Furthermore, a temperature gradient can be established at the drawing groove, under which the edge temperature at the slit end should be cooler than the temperature in the middle of the slit. Thus, the outer edge of the downward-drawn glass ribbon always has a higher viscosity than the middle, causing tension in the glass at the edges, or so-called boundaries, of the glass ribbon. In this way, the width of the flat glass can be controlled and determined during manufacturing. When the viscosity distribution is uniform across the width of the glass ribbon, shrinkage occurs, leading to an uncontrolled reduction in the width of the glass ribbon.

[0005] However, due to the higher viscosity in the edge region of the glass strip, the forming force is greater than that in the middle of the strip when increasing the drawing speed to achieve a thinner glass thickness. This causes a slight increase in flow rate in the edge region, resulting in more glass being drawn from the slit compared to a situation where no drawing force is applied. This uneven increase in flow rate... This alters the thickness distribution within the glass ribbon, making the edge regions thicker than the center and creating a concave thickness distribution. This unevenness is subsequently compensated for by a boundary roller located below the nozzle. However, when manufacturing extremely thin glass ribbons of approximately 250 μm or less, this boundary roller can cause the glass ribbon to break.

[0006] To address these issues, US1626382 A proposes a funnel-shaped nozzle slit where the parallel slit shape is narrower at the slit ends than in the middle slit region. The funnel shape is less pronounced at the slit ends, thus providing more hot glass bloc at the ends and ensuring the glass is cooled less rapidly and maintains a relatively consistent temperature throughout the slit length. Furthermore, the narrower slit at the ends is designed to provide increased drawing resistance. However, this slit shape is not very practical. Firstly, the mechanically predetermined ratio of two different slit widths over the same slit length is very specific and can only be used based on a very specific combination of glass composition, predetermined glass thickness, and matching drawing force. Secondly, even with minimal variation in drawing force, the drawing characteristics and thickness ratio of the glass change. Therefore, the nozzle must be replaced each time the desired glass thickness is changed or when there are process-induced fluctuations in drawing force, and only very small tolerances are allowed for optimal results. Furthermore, a combination of two different slit widths cannot compensate for the gradient, and therefore cannot reliably compensate for the non-uniform thickness distribution across the width of the glass strip caused by the temperature gradient.

[0007] A similar slit shape is described in CN 110590132 A, in which the nozzle slit is constructed parallel in the middle region and narrows non-linearly on the sides, thereby achieving a more favorable thickness distribution. However, the problem is that the nozzle must be replaced every time the glass thickness is changed, and the temperature gradient causes higher viscosity at the boundary.

[0008] US 3473911 describes a funnel-shaped nozzle whose opening width can be varied. However, this involves a significant amount of work, as the glass forming process must be interrupted to manually change the width. Moreover, the resulting viscosity gradient cannot be compensated for in this way.

[0009] A nozzle is also proposed in US2422466 A; however, this nozzle is funnel-shaped only in the central region. Similar to US1626382 A, the nozzle slit is narrower on the sides than in the central region. Furthermore, additional volume is provided on the sides, meaning the glass is cooled less rapidly at the slit ends. However, this nozzle is not funnel-shaped on the sides, but rather pocket-shaped. This means that while the glass is cooled less rapidly, it can no longer flow out of the slit and must be actively drawn. The problem with consistent tension is that a certain amount of glass remains in the pocket, resulting in an uneven temperature distribution within the pocket. Furthermore, the bends in the slit cause the tension of the drawn glass strip to be locally unevenly distributed across the width of the nozzle slit. Therefore, it is difficult or even impossible to achieve a consistent width of the glass strip. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a method and apparatus for drawing particularly thin glass ribbons, which enables the production of glass of varying thicknesses without significantly altering the temperature of the drawing bath. This also compensates for process-induced tolerances and ensures uniform thickness and a uniform and controllable width of the glass ribbon. This results in more stable process control. Furthermore, shrinkage of the glass ribbon, especially at high drawing speeds, should be suppressed as much as possible.

[0011] This objective is achieved through the solution in the independent claim. Advantageous improvements are given in the corresponding dependent claims.

[0012] Therefore, the present invention relates to an apparatus for drawing glass ribbons from molten glass. The apparatus has a drawing groove for receiving the molten glass, the drawing groove having a nozzle including a through opening through which the molten glass can be discharged downwards. The through opening is formed as a nozzle slit with two ends, wherein the length of the nozzle slit is greater than its width. The nozzle slit curves downwards, particularly continuously or coherently, i.e., in the drawing direction, towards the ends in a first and second side region, such that these ends are lower than the intermediate region between the ends of the nozzle slit, the intermediate region extending particularly in a straight line, and wherein the width of the nozzle slit changes from the middle towards the ends.

[0013] The nozzle slit extends particularly in length, width, and height, with the height extending parallel to the drawing direction of the glass ribbon. The width and length are perpendicular to each other and perpendicular to the height. Therefore, the length of the nozzle slit can also be understood as a length transverse to the width and height. In this case, the length of the nozzle slit is greater than its width and height. When the height of the nozzle or nozzle slit is mentioned below, it refers to the extension along the drawing direction, which is preferably opposite to gravity. Therefore, the height of the nozzle or nozzle slit extends from the upper surface of the upper wall of the nozzle to its lower end. Thus, the width and length of the nozzle or nozzle slit extend horizontally, i.e., particularly perpendicular to the drawing direction of the glass, and the length of the nozzle slit is preferably given by the distance between the first end and the second end.

[0014] A change in the width of the nozzle slit can be understood as the nozzle slit being configured as a continuous non-linear or preferably curved line along its length and relative to its width in the first and / or second side regions. A downward curve is understood as the nozzle slit being preferably configured as a continuous non-linear or particularly curved line along its height in the first and / or second side regions, such that the first and / or second ends are lower than the intermediate regions.

[0015] It is important to note that the through-opening has an outflow surface through which molten glass is discharged. In particular, the nozzle slit leads into a slit-shaped nozzle opening, which preferably corresponds to the outflow surface. In this case, the outflow surface is arranged at the lower end of the nozzle slit and surrounded by the lower surface of the nozzle. Similar to the nozzle slit, the length, width, and height of the outflow surface of the through-opening also extend parallel to the drawing direction of the glass ribbon, wherein the outflow surface preferably extends particularly parallel to the length and width of the nozzle slit in the intermediate region. In the first side region and / or the second side region, the outflow surface ideally extends continuously, non-linearly, or particularly curvedly, along its length and relative to its height, and preferably also continuously, non-linearly, or particularly curvedly, relative to its height. Therefore, when referring to the shape of the nozzle slit, it also means the design of the outflow surface, through which the nozzle slit is defined on the lower side of the nozzle.

[0016] By varying the width of the nozzle slit, the local flow rate of the glass melt can be affected. This allows for adjustment of the flow rate along the length of the nozzle slit, thereby reducing glass ribbon shrinkage and maximizing the useful bandwidth between the thickened boundaries. Advantageously, at least partially curved nozzle slits or at least partially curved outflow surfaces significantly suppress glass ribbon shrinkage in width. In particular, the downward curvature of the nozzle slit in height results in better force distribution during glass ribbon drawing, thereby allowing the glass ribbon to be drawn in width even with horizontal forces.

[0017] Preferably, the nozzle slit opening tapers from the middle towards the ends, such that the width of the nozzle slit is greater in the middle region than at its ends. This taper towards the ends advantageously results in a reduced glass flow rate through the nozzle slit while maintaining a constant glass viscosity along its length. However, the typically present temperature gradient causes the glass viscosity at the nozzle slit ends to increase due to the lower temperature, resulting in a higher tensile force on the glass and consequently a higher flow rate. This also means that, under the temperature gradient, the flow rate at the tapered nozzle slit ends can match the flow rate in the middle region, thereby achieving the most uniform thickness of the glass ribbon possible.

[0018] It is also advantageous that the through-hole, especially the nozzle slit, preferably tapers continuously along its length towards the side ends from the center, or is designed to monotonically increase from the side ends towards the center along its length. In this way, the flow rate can be adjusted so that the glass flow rate is uniform along the length of the nozzle slit under temperature gradients and thus, consequently, viscosity gradients. Especially consistent (einheitlich).

[0019] Therefore, it is conceivable that the through opening, especially the nozzle slit, has an oval, elliptical, concave, or lenticular shape in terms of length and width when viewed from above or along the drawing direction. This shape can be understood as the nozzle slit forming a convex shape, i.e., wider in the middle than at its ends. In this shape, the nozzle slit tapers gently, linearly, or exponentially and can thus be matched to a particular degree with temperature gradients.

[0020] In an advantageous embodiment, the nozzle slit has a continuous or preferably gentle curve relative to the height in both the first and second side regions, the curve having a radius where the height is parallel to the drawing direction. The downward curve of the nozzle slit in terms of height results in a better force distribution during the drawing of the glass ribbon, so that the glass ribbon is also drawn in width by a horizontal force. With the continuous change in the height of the nozzle slit, the outflow surface curves continuously toward the nozzle slit ends, causing the horizontal force component to rise continuously toward the slit ends. This means that the stronger the glass ribbon is forced to contract, the stronger the reaction force acting on the contraction, thereby achieving a uniform glass ribbon width. Ideally, the transition from the preferably linear and / or perpendicular to the height-extending intermediate region to the downward-curving side regions is also implemented gently or linearly, so that no bends are produced and a smooth transition or gradual change in force is ensured. In this way, variations in the thickness and width of the glass ribbon are avoided. Therefore, it is also conceivable that the intermediate region curves downward, particularly slightly, in the direction of the side regions or in the direction of the ends. Preferably, in this case, the highest point is located in the middle of the intermediate region.

[0021] In another embodiment, the nozzle slit has at least one of the following characteristics:

[0022] - The nozzle slit curves continuously to the end, particularly from the middle region to the end, and preferably extends in a straight line or only slightly curves in the middle region.

[0023] - The nozzle slit bends until the end and the bend has an inflection point.

[0024] It should be understood that the nozzle slit may also taper relative to its width and height, preferably configured as a funnel or trough. The taper of the nozzle slit width may be linear or non-linear, especially curved, to support the pulling or flowing of glass through the nozzle slit and accordingly reduce the tension that must be applied for this purpose.

[0025] The nozzle can have protrusions in the first and second side regions, respectively, for accommodating additional flow rates of molten glass, and these protrusions extend in the drawing direction, i.e., downwards, with the internal space of the protrusions defining the magnitude of the additional flow rate. The protrusions can also be considered as recesses at the nozzle slit ends, particularly at the first and second nozzle slit ends. These recesses or protrusions provide a downward curvature of the nozzle slits and preferably also provide internal space for the protrusions. This internal space is preferably defined by the wall surrounding the nozzle slits, i.e., the wall of the nozzle, particularly in the side regions of the protrusions. This internal space is preferably designed to provide additional volume for accommodating molten glass, wherein the internal space or the wall of the nozzle slits provides a higher surface area. This also accelerates the cooling of the glass melt. The glass melt can then export heat through the increased surface area. Consequently, the glass exits the nozzle slit at a lower temperature than it would without these protrusions / recesses. The lower temperature results in a higher viscosity, which inhibits severe shrinkage of the glass ribbon. By selecting appropriate additional volumes or internal spaces, the temperature gradient and viscosity of the glass melt can be specifically controlled.

[0026] This also ensures that the ratio of the height to the width of the internal space of the protrusion is greater than 0.2, preferably greater than 0.5, preferably greater than 0.8, and / or less than 2, preferably less than 1.6, preferably less than 1.2. This relationship is important because the smaller the width, the higher the pressure loss that the flowing glass must overcome. On the other hand, if the internal space is too wide, the cooling of the glass volume is worse because the heat conduction path through the glass to the nozzle slit or the cooling wall of the internal space becomes longer. Therefore, this ratio of the height to the width of the internal space is the optimal ratio between the pressure loss and cooling of the glass melt.

[0027] In an advantageous embodiment, the radius, especially the minimum radius, of the curved portion of the nozzle slit is defined by the height and length of the protrusion, thereby causing the nozzle slit, especially the outflow surface, to bend downwards.

[0028] It is also conceivable that the radius of the curved portion of the nozzle slit is greater than 100 mm, preferably greater than 130 mm, preferably greater than 160 mm and / or less than 260 mm, preferably less than 230 mm, preferably less than 200 mm. In this way, optimal force transfer can be achieved by increasing the horizontal component towards the ends. Preferably, the average radius is between 100 mm and 260 mm. According to one embodiment, the radius decreases particularly linearly or exponentially with the increase of the nozzle slit length, specifically towards its ends, to ensure a continuous increase of the horizontal force component relative to the vertical force component. In this way, severe shrinkage of the glass ribbon can be prevented, for example, at particularly high drawing speeds used for glass ribbons with a thickness of less than 100 μm, and the glass ribbon can be stretched more open, especially at the ends.

[0029] Furthermore, it is advantageous that the ratio of the length to the height of the protrusion is less than 2.8, preferably less than 2.6, and most preferably less than 2.4. This is the optimal ratio for achieving a suitable force distribution. If the horizontal component is similar in size to the vertical component, or even larger, i.e., the ratio of the length to the height of the protrusion is less than 2.4, and if the vertical line of the nozzle slit is >= 45° relative to the pulling direction, this will have an adverse effect on the width of the glass ribbon, because an excessively high proportion of the horizontal component will lead to shrinkage.

[0030] It is also conceivable that the curved sections of the protrusions in the first side region are opposite to the curved sections of the protrusions in the second side region. In particular, the nozzle slits having protrusions or recesses are configured to be mirror symmetrical in at least one direction, but preferably in length and / or width. In this way, a uniform thickness and width can be formed over the entire width of the glass strip.

[0031] The height of the internal space of the protrusion can be greater than 10mm, preferably greater than 15mm, preferably greater than 20mm and / or less than 80mm, preferably less than 60mm, preferably less than 40mm.

[0032] In an advantageous embodiment, the width of the protrusion is obtained by multiplying the width of the nozzle slit, particularly the cross-section of the through opening, by a value greater than 1 mm, preferably greater than 1.5 mm, preferably greater than 2 mm, and / or less than 15 mm, preferably less than 10 mm, preferably less than 5 mm. The height and width of the protrusion or its internal space define the available additional volume for accommodating the molten glass and thus the possibilities for the glass's temperature and viscosity. Therefore, with the previously given values, an optimal temperature or viscosity gradient of the molten glass across the width of the nozzle slit can be achieved, ensuring a uniform width and thickness of the glass strip even with uniform tension.

[0033] The protrusion may have a lower wall that closes the internal space of the protrusion in the drawing direction, wherein a through opening or outflow surface is arranged in the lower wall. Preferably, the nozzle includes an upper wall opposite to the lower wall in addition to the lower wall, and particularly includes side walls in the first and second side regions, the internal space of the protrusion being defined by the side walls. Ideally, the lower wall of the protrusion is curved particularly coherently or continuously in the drawing direction, so that an internal space is provided between the lower wall and the upper wall. The curvature of the lower wall causes the internal space to gradually narrow in the direction toward the central region of the nozzle.

[0034] This objective is also achieved by a method for drawing thin glass ribbons from molten glass, wherein glass is melted and discharged from a drawing groove and drawn downwards in the drawing direction to form a thin glass ribbon, the drawing groove carrying the molten glass and having a through opening. After exiting the through opening, the thin glass ribbon is cooled by at least one cooling device until it falls below the glass transition temperature T. g The thin glass strip is drawn out along the drawing direction through contact with drawing rollers, which transfer the tension to the thin glass strip. The drawing rollers operate when the glass temperature is below the glass transition temperature T. g The glass contacts the nozzle at a specific position. Passive cooling of the glass is also conceivable. This method uses the aforementioned apparatus, which has a nozzle including a protrusion that reacts to the contraction of the glass ribbon. The nozzle with the protrusion is characterized by two modes of action. One mode of action is that the protrusion is designed to discharge the molten glass at a lower temperature at the tip, thereby creating a viscosity gradient that results in an increase in the viscosity of the molten glass at the tip of the nozzle and thus a higher pulling force on the glass ribbon. This allows for a stronger pulling of the glass ribbon across its width. Therefore, a temperature gradient is generated across the width of the nozzle, where the temperature of the molten glass decreases towards the tip.

[0035] The glass exiting from the middle of the nozzle slit travels through a section defined by the height of the protrusion until it reaches the same height as the ends or endpoints of the nozzle slit. This means that when the glass exits from the ends of the nozzle slit at the same height, the glass from the middle has already cooled slightly. Consequently, the thinner glass in the middle acquires higher viscosity at that point, which in turn affects the contraction of the glass ribbon.

[0036] Another approach involves designing the nozzle such that the tension in the glass ribbon generated below the through-opening is divided into vertical and horizontal components at the protrusion. This creates opposing forming forces within the glass ribbon, with the proportion of the horizontal forming force increasing relative to the vertical forming force towards the first and second ends. This horizontal forming force reacts against the shrinkage of the glass ribbon at the boundary. This horizontal forming force stretches the glass ribbon horizontally, reducing shrinkage. The ratio of the horizontal to vertical forming force components is specifically controlled by the special shape or design of the nozzle slit, particularly in the side regions, for example, by the curvature of the nozzle slit relative to its height, preferably relative to the protrusion height. Ideally, the radius of this curvature decreases continuously towards the ends linearly or exponentially, but also significantly ensures a smooth transition to the nozzle, particularly the horizontal and / or straight intermediate region, to prevent unevenness in the thickness and width of the glass ribbon.

[0037] The method and, in particular, the apparatus shown can produce exceptionally thin glass ribbons. By using specially shaped nozzles with nozzle slits and protrusions, boundary rollers that could cause the glass ribbon to break can be removed. The nozzle slits and protrusions allow for targeted and, especially individually, setting of the tension applied to the glass ribbon across its width for each region.

[0038] This apparatus and method are particularly suitable for manufacturing thin and ultra-thin glass. Thus, according to one embodiment, thin glass strips with a thickness of up to 20 μm, preferably up to 100 μm, can be drawn. Significantly thinner glass strips can also be drawn, for example, glass strips with a thickness of up to 70 μm, preferably up to 50 μm, and particularly preferably up to 20 μm. Thicknesses of less than 5 μm, preferably less than 10 μm, are also conceivable. Such glass strip thickness is particularly advantageous for multi-layered, flexible, or easily bendable protective covers, such as flexible displays. This special design of the drawing nozzle particularly enables the production of glass strips with significantly different thicknesses without changing the nozzle gap. In this way, glass strips are successively drawn from the same nozzle, with a thickness difference of at least 1.5 times, preferably at least 2 times. In this manner, glass strips with different thicknesses or strengths can be manufactured. The glass ribbon can be used without changing the nozzle or interrupting the manufacturing process. Attached Figure Description

[0039] The invention will now be explained in more detail with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or corresponding elements. The drawings show:

[0040] Figure 1 A schematic diagram of an apparatus for drawing glass ribbons from molten glass is shown.

[0041] Figure 2A schematic diagram of the nozzle slit is shown in top view and along the width of the thin glass strip.

[0042] Figure 3 A schematic diagram of the nozzle slit is shown in top view and along the width of the thin glass strip.

[0043] Figure 4 A schematic cross-sectional view of the side region of the nozzle with protrusions is shown.

[0044] Figure 5 A schematic top view of the nozzle is shown.

[0045] Figure 6 A three-dimensional view shows a schematic diagram of the side region of the nozzle, which has a protrusion and a short nozzle slit.

[0046] Figure 7 A three-dimensional view shows a schematic diagram of the side region of the nozzle, which has a protrusion and a short nozzle slit.

[0047] Figure 8 A schematic cross-sectional view of the side region of the nozzle with protrusions is shown.

[0048] Figure 9 A schematic cross-sectional view of the nozzle is shown.

[0049] Figure 10 A schematic diagram of an apparatus for drawing glass ribbons from molten glass is shown.

[0050] Figure 11 A schematic diagram of an annealing furnace is shown.

[0051] Figure 12 A schematic diagram of a molding area with heating or cooling units is shown.

[0052] Figure 13 A schematic diagram of the crucible, discharge pipe, and drawing groove is shown. Detailed Implementation

[0053] Figure 1 A schematic diagram of an apparatus 1 for drawing a glass ribbon 10 from molten glass 9 is shown. The apparatus includes: a drawing groove 2, with a nozzle 4 arranged below the drawing groove 2; and a cooling device 3 in which the glass ribbon 10 is cooled. First, molten glass 9 is fed into the drawing groove 2, where temperature control is performed or the temperature of the molten glass 9 is adjusted along the length and width of the drawing groove. Then, molten glass 9 enters the nozzle 4 and flows out of the drawing groove 2 through the opening of the nozzle 4. During its passage through the nozzle, but especially upon exiting the nozzle, molten glass 9 forms its final shape, the glass ribbon 10, in a forming region 14. The glass ribbon 10 is defined at its edges by a glass ribbon edge or boundary 11.

[0054] After leaving nozzle 4, the glass ribbon 10 is cooled in or below forming zone 14 until it is below the glass transition temperature T. g Preferably, a drawing roller 15 is arranged below the cooling device 3, preferably in the cold zone, through which the pulling force is transferred to the glass strip 10. Preferably, the temperature of the glass at the point of contact with the drawing roller is at most 200°C, particularly preferably at most 100°C. In the cold zone, i.e., in T... g The contact between the glass and the drawing roller has proven advantageous, particularly at temperatures up to 200°C, to reduce the probability of breakage. At lower temperatures, greater freedom is also available in the selection of the material for the drawing roller. For example, the drawing roller can have an elastomer surface that exhibits only minimal slippage.

[0055] Preferably, at least two pairs of drawing rollers 15 are arranged transversely spaced apart in the drawing direction Z, wherein the drawing roller pairs clamp the glass strip 10 between the two drawing rollers 15 in the region of the boundary 11 on both sides. The pulling force transmitted by the drawing rollers 15 is adjusted or set according to the desired thickness of the glass strip 10. According to one embodiment, the pulling force can be set higher for a smaller thickness than for a desired larger thickness, i.e., a thicker glass strip 10. Therefore, preferably, the glass strip 10 is set to the desired thickness by the pulling force transmitted by the drawing rollers 15 and pulled out from the nozzle 4 as molten glass 9.

[0056] exist Figure 2 and Figure 3 The nozzle slit configuration and typical thickness distribution along the width of the thin glass strip are shown in top view. The nozzle 4 extends along width B, length L, and height H along the drawing direction Z, and has a preferably slit-shaped through opening, specifically configured as nozzle slit 5. The nozzle slit is surrounded by the wall 6 of the nozzle 4. Nozzle slit 5 has a first end 7a and a second end 7b, wherein the first end 7a is arranged in a first side region 8a and the second end 7b is arranged in a second side region 8b, and both side regions 8a and 8b extend substantially along the length L. An intermediate region 8c is arranged between the first side region 8a and the second side region 8b.

[0057] exist Figure 2 and Figure 3 In the lower part, the thickness distribution along the width of the thin glass strip 10 is shown in the case of a parallel configuration of the nozzle slit 5, wherein in Figure 2 The typical thickness distribution of thin glass ribbon 10 with a thickness of less than 300 μm is shown in the figure. Figure 3 The image shows the thickness distribution of thin glass ribbons with a thickness greater than 300 μm. It can be seen that the thickness is less than 300 μm (…). Figure 2The glass band 10 is thicker at boundary 11 than in the middle between boundaries. However, at thicknesses greater than 300 μm... Figure 3 The opposite effect is observed in the glass strip 10. The maximum value of this thickness distribution is located in the middle. This is mainly due to the different cooling behaviors formed by the different thicknesses of the glass strip 10 combined with the drawing speed, or the temperature gradient formed across the width of the glass strip 10. In order to make the drawing speed or the glass flow rate through the nozzle slit 5 consistent with the existing temperature gradient of the glass melt or the temperature gradient of the glass melt specifically formed in the nozzle 4, the nozzle slit 5 is constructed to be curved. However, preferably, the temperature gradient can also be specifically set such that the temperature gradient extends from the middle to the outside, i.e., increases or decreases particularly from the middle of the nozzle slit toward the ends 7a, 7b. In particular, the first side region 8a and / or the second side region 8b are constructed non-linearly or preferably curvedly along the length L of the nozzle slit 5 and relative to its height H. Therefore, ideally, the nozzle slit 5, especially for glass strips 10 with a thickness less than 300 μm, has an oval, elliptical, or prismatic, or more generally convex cross-section perpendicular to its height, to reduce the flow rate at the edge 11. This should be understood in particular as the width Bs of the nozzle slit 5 decreasing from the middle toward the ends 7a, 7b. For glass strips 10 with a thickness greater than 300 μm, a bone-shaped cross-section is preferred, thereby reducing the flow rate in the middle of the glass strip 10 relative to the boundary 11. The bone-shaped cross-section should preferably be understood as a concave cross-section, particularly causing the width Bs of the nozzle slit 5 to increase from the middle toward the ends 7a, 7b. Thus, in both cases, the flow rate can be adjusted by using the nozzle slit configuration, achieving a consistent glass strip thickness across the width of the glass strip ends 10 or along the length L of the nozzle slit 5. Preferably, the bends are continuous, even intermittent, and particularly linear or exponential, to achieve uniform shaping along the length L.

[0058] Figure 4 and Figure 5 Schematic cross-sectional views of the side region 8b are shown. Figure 4 This diagram shows a side region 8b of the nozzle 4 with a protrusion 20, wherein the protrusion 20 can be understood as a recess in the nozzle slit 5 or a recess providing additional volume for accommodating the molten glass 9. The protrusion is preferably defined by a lower wall 21, an end wall 22, and preferably also by at least one, preferably two or more side walls 25. The shape of the side walls can be linear or curved relative to the height H of the nozzle 4, the width Bv of the protrusion 20, and optionally relative to the length of the protrusion 20. The lower wall 21 preferably extends in the width Bv between the side walls 25 and is defined in particular by the end wall 22.

[0059] However, in order to influence the force acting during the drawing of the glass strip 10, the lower wall 21 is curved, particularly along the length L and with respect to the height H, preferably linearly or exponentially. In this way, a consistent curvature configuration can be achieved, wherein the lower wall 21 of the protrusion 20 ideally forms a smooth transition to the lower boundary 30 of the intermediate region 8c of the nozzle slit 5. Ideally, the lower wall 21 and the lower boundary 30 of the intermediate region 8c form a consistent surface, thereby preferably the curvature of the lower wall 21 begins in the side region 8b and extends to the lower end 23 of the protrusion. At the lower end 23, the lower wall 21 abuts the end wall 22 and can be connected to the end wall 22 in one or two pieces.

[0060] Preferably, the lower wall 21 and / or lower boundary 30 terminate the nozzle 4 or drawing groove 2 downwards, wherein the lower boundary 30 extends horizontally in particular. The nozzle slit is arranged in the lower boundary 30 and lower wall 21, in particular allowing the molten glass 9 to flow out from the lower end 23, or at least be drawn out, so that the glass strip 10 can be drawn to the width at the boundary 11 at the lower end 23. The nozzle slit 5 can therefore also extend beyond the lower end in its length L, as shown in… Figure 7 As shown in .

[0061] The radius R is determined by the height H of the nozzle 4 from its lower end 23 to its upper wall 24 and the length Lv of the protrusion 20 in the side regions 8a, 8b. To set the radius R of the bend in the nozzle slit 5 or the lower wall 21 to an ideal value that decreases towards the lower end 23, preferably between 160 mm and 200 mm, the height of the protrusion 20 is between 20 mm and 40 mm. Another important relationship is the ratio of the height H of the nozzle 4 to the width Bv of the protrusion 20, which... Figure 5 The diagram also illustrates this. The smaller the width Bv, the higher the pressure loss that the flowing glass must overcome. On the other hand, when the protrusion 20 is too wide, the cooling of the glass volume becomes worse because the heat conduction path through the glass to the cooling walls 21, 22 of the protrusion becomes longer. Therefore, the ratio of the height H of the nozzle 4 to the width Bv in the internal space of the protrusion 20 is ideally between 0.8 and 1.2. Since the shape of the nozzle slit 5 is basically oval or elliptical, the nozzle slit 5 can be defined by changing the width Bs. For example, to manufacture 50 μm thick glass, it is conceivable that the difference between the nozzle slit width Bs in the middle and the outer side is greater than 3 mm. In this case, the width of the nozzle slit can be changed in the side regions 8a, 8b, that is, in the region of the protrusion 20, and in the middle region 8c of the nozzle 4.

[0062] In order to define or provide the optimal internal space of the protrusion 20 and thereby adjust the viscosity of the glass melt 9, the width Bv of the protrusion 20 is calculated based on the nozzle slit width Bs.

[0063] Bv = 2 × Bs to 5 × Bs

[0064] The protrusion 20 preferably extends beyond the lower end 23 along its length, such that the end wall 22 may extend obliquely and / or curvedly from the upper wall 24. Preferably, the upper opening in the upper wall 24 of the nozzle 4 is wider and / or longer than the lower wall 21, but especially wider and / or longer than the width Bs of the nozzle slit.

[0065] Figure 6 and Figure 7 Two embodiments of the nozzle slit 5 of the nozzle 4 are shown in a perspective view. In one embodiment ( Figure 6 In the ), the nozzle slot is 5 times. Figure 7 The embodiment is slightly shorter, such that the nozzle slit 5 terminates in the downwardly curved region of the protrusion 20. Therefore, in this embodiment, the nozzle slit 5 curves continuously downwards until its end. Figure 7 In the illustrated embodiment, the nozzle slit is slightly longer. Therefore, the nozzle slit 5 extends from the lower wall 21 of the protrusion 20 into the lower end portion 23, or even beyond it. Preferably, the curved portion of the nozzle slit 5 has an inflection point W in the transition region from the lower wall 21 to the lower end portion 23, such that the slope decreases again, or even reverses. The nozzle slit 5 may also have a bend at the inflection point.

[0066] Figure 8 An exemplary illustration shows the force distribution at the protrusion 20. The force generated by drawing the glass strip 10 along the drawing direction is divided into a vertical force component Fv and a horizontal force component Fh at one or more protrusions 20 through the bend of the nozzle slit 5. This results in a continuous increase of the lateral pulling force component in the direction of the nozzle end in the downwardly curved section 8b or lower wall 21 of the nozzle slit 5. This means that the smaller the radius R in the direction of the lower end 23, the larger the horizontal component Uh of the forming force is when drawing the glass strip 10. This horizontal component is crucial for tensioning the glass strip 10 and maintaining its width. The reaction force in the rigid glass is used for forming, i.e., drawing the glass sheet thinner. In this horizontal component Uh, the glass being formed is drawn outward, especially at the boundary 11, i.e., in width and therefore also in the opposite direction to the shrinkage, while the vertical component Uv of the forming force draws the glass downward along the drawing direction Z. The force, derived from the sum of the horizontal and vertical force components, is given as the tension Fz and forming force Uz in the glass strip 10.

[0067] Depending on the desired width and / or tension of the glass strip 10, the radius R of the bend in the nozzle slit 5 can also be uniform, i.e., preferably without decreasing in size in the direction of the lower end. However, it is particularly important that a “bend” not be formed at the transition from the lower wall 21 to the lower boundary 30 of the intermediate region 8c, as a “bend” results in a near-quasipunktuellen non-uniformity or uneven force distribution. In particular, uneven force distribution of forming forces Uh and Uv can lead to localized changes in the thickness or width of the hard glass, thus no longer ensuring a stable forming process or consistent parameters or glass properties across the width of the glass strip 10.

[0068] Overall, wider glass ribbons can be produced from a given drawing groove width using a nozzle 4 with a nozzle slit 5 that is curved in length L, width B, and height H, compared to those achievable without the curved section. Glass thicknesses below 100 μm and even below 50 μm can be drawn. Figure 9 The diagram exemplarily illustrates the width variation of the glass strip 10 compared to the nozzle slit 5 extending parallel in all directions due to the curved slit. Here, the dashed boundary 11 shows the width Bp of the glass strip 10 produced by the parallel nozzle slit 5, and the solid boundary 11 shows the width Bk of the glass strip 10 that can be produced by means of the curved nozzle slit 5. Several typical values ​​for the boundary width of glass strips 10 of different thicknesses produced using a 700 mm long nozzle slit 5 are given below by way of example only, as well as possible width variations when using the curved nozzle slit 5.

[0069] Table 1: Variation in the width of the glass strip when using a nozzle slit with a protrusion.

[0070]

[0071] Compared to Figure 1 An embodiment of device 1 is shown. Figure 10 A schematic diagram of an apparatus 1 with a cooling device 3 and / or a drawing groove 2 is shown. According to one embodiment, the cooling device 3 has at least one annealing furnace 40 through which the glass ribbon 10 moves, particularly through the inlet and outlet of the annealing furnace 40. The annealing furnace 40 is preferably arranged below the forming region 14 of the glass ribbon 10, particularly after forming, to cool the formed glass ribbon 10, especially in a controlled and slow manner, to a desired temperature, such as room temperature, to, for example, avoid or reduce stress in the glass ribbon 10.

[0072] To achieve particularly precise cooling across the width of the glass strip 10, the cooling furnace 40 may be configured to have multiple cooling and / or heating sections 41, arranged side-by-side / above-below and preferably adjacent to each other. At least one cooling and / or heating section 41, preferably multiple, and more preferably all of the cooling and / or heating sections 41, includes a thermocouple 42 for measuring and controlling the temperature. Preferably, the cooling and / or heating sections 41 are arranged adjacent to each other in a tile shape and, in particular, in a tile-like manner. This can be understood as the cooling and / or heating sections being constructed as tiles or in a rectangular, square, or hexagonal shape, particularly allowing the cooling and / or heating sections 41 to be arranged adjacent to each other without free space between them. This embodiment is exemplarily shown in Figure 11 As shown in the diagram, the cooling and / or heating sections 41 can be configured to have different dimensions. Thus, for example, the cooling and / or heating sections 41 arranged particularly in the region of boundary 11 or the edge of the annealing furnace are constructed to be larger or smaller than those arranged in the middle of the annealing furnace 40 or the glass ribbon 10. In this way, specific areas of the glass ribbon 10 can be locally cooled and / or heated more strongly or less strongly, enabling individual cooling and / or heating options for each glass ribbon width and shape. Therefore, it is also conceivable that the cooling and / or heating sections 41 are constructed to be larger or smaller in the lower region of the annealing furnace 40 than in the upper region.

[0073] To control the temperature of the glass strip 10, the device 1 includes at least one temperature measuring device 45. The temperature measuring device 45 is specifically configured to detect or measure the temperature of the glass strip 10, preferably over its entire width. (As in...) Figure 10 As shown, the temperature measuring device 45 may be arranged in the forming area 14, particularly above the annealing furnace 40, so that the temperature of the glass ribbon 10 can be measured, for example, before the glass ribbon 10 is cooled by means of the annealing furnace 40. In this way, an optimal cooling process for the glass ribbon 10 can be achieved. Similarly, the temperature measuring device 45 or at least one or more other temperature measuring devices 45 may also be part of the annealing furnace 40 and / or arranged within the annealing furnace, for example, in the middle.

[0074] In some cases, for example, when a nozzle 4 optimized for a specific glass thickness is used to manufacture different glass thicknesses, it may be necessary to influence the temperature of the glass strip 10 in the forming region 14. Therefore, in another embodiment, the device 1 has at least one, and particularly a plurality of, spatially distributed cooling and / or heating units 50, preferably arranged in the forming region 14. In this case, the cooling and / or heating units 50 may be designed such that they can selectively heat and / or cool the glass strip 10 locally, at least in certain areas, thereby selectively adjusting the width of the glass strip 10 in the forming region 14. This is understood to mean that cooling or heating does not occur across the entire width of the glass strip 10, but rather that the temperature of the glass strip 10 can be locally changed in desired areas. Thus, non-uniform and / or uniform cooling or heating across the width of the glass strip can be achieved.

[0075] Therefore, it is particularly preferred that different cooling and / or heating units 50 are spatially distributed, especially laterally distributed, to the glass strip 10, in order to influence the local glass distribution in the glass strip 10 and also to allow for minor adjustments to the glass distribution. In this case, the cooling and / or heating units 50 are distributed, for example, across the entire surface of the forming region 14, preferably with a height greater than 5%, preferably greater than 10%, preferably greater than 15% of the length of the forming region 14, and / or with a height less than 50%, preferably less than 30%, of the length of the forming region 14, wherein the length of the forming region 14 is particularly laterally distributed to the width of the glass strip 10. Here, the length of the forming region 14 can be between 100 mm and 300 mm. In other words, the cooling and / or heating units 50 can be arranged between the nozzle 4 and the annealing furnace 40, thereby enabling, for example, fine-tuning of the thickness of the glass strip 10. This also allows for the drawing of different glass strips with different glass thicknesses through a single nozzle slit 5, having a wider area than the area where the nozzle slit 5 is actually optimized.

[0076] In this way, for example, different cooling and / or heating units 50 can be used in the middle of the glass strip 10 in a thinner glass with a concave thickness distribution to reduce the glass temperature or increase the glass viscosity. This results in early termination of the forming process and the glass is not drawn to the same thickness in that region as it would be without these cooling and / or heating units 50. To allow for individual temperature adjustment at desired locations on the glass strip 10, it is conceivable that multiple cooling and / or heating units 50 can be arranged side-by-side and / or diagonally or laterally along or relative to the width of the glass strip 10. It is also possible to arrange multiple cooling and / or heating units 50, particularly vertically, along the drawing direction. Depending on the application, for example, two to six cooling and / or heating units 50 can be arranged side-by-side, vertically, and / or diagonally relative to each other.

[0077] Advantageously, the cooling and / or heating unit 50 can be configured as an air cooler or a water cooler, and in particular generate airflow, water jets, water droplets, mist and / or aerosols, such as in, for example, Figure 12 As illustrated in the diagram. These media can be specifically and, if necessary, directly aligned with the glass strip 10.

[0078] However, it is also possible to configure the cooling and / or heating unit 50 as an indirect cooling and / or heating unit 50, for example, a closed piping system in which at least one medium circulates, such that the glass ribbon 10, in particular, does not come into contact with another medium, such as water. In this case, the cooling and / or heating unit 50 is configured such that it either outputs or absorbs heat energy, or dissipates heat energy. It is conceivable that at least one pipe of such a piping system is oriented laterally or parallel to the drawing direction. To detect the temperature of the preferred medium and / or the glass ribbon, a temperature measuring device 45 may be provided, particularly arranged on at least one, preferably each, cooling and / or heating unit 50, so that, for example, the heat energy absorbed from the glass ribbon 10 can also be measured. Not limited to the foregoing embodiments, combinations of direct and indirect cooling and / or heating units 50 may also be used. Regardless of whether the cooling and / or heating unit 50 cools or heats indirectly or directly, different cross-sectional shapes of the cooling and / or heating unit 50 are conceivable, such as circular, elliptical, or polygonal shapes, such as rectangular or hexagonal.

[0079] Here, the spacing between the cooling and / or heating unit 50 and the glass strip 10 can be changed. Therefore, cooling, for example, by air cooling, can be finely adjusted by regulating the air volume. Here, the greater the amount of air directed per unit time, the thicker the glass. Another very effective variation of air cooling is the incorporation of atomized water, forming an aerosol. Based on the water volume, this aerosol can deliver significantly more heat energy than pure dry air, wherein the aerosol, atomized water, or different atomized liquids can also be mixed with air or special gas components for effective cooling.

[0080] When using a cooling and / or heating unit 50 in the form of, for example, a water cooler and / or an air cooler, the position of the cooling and / or heating unit or its spacing relative to the glass strip 10 can be changed. In this case, the smaller the spacing between the water cooler and the glass strip 10, the thicker the glass. A heating unit that allows the glass strip 10 to be formed thinner in the desired area has the same effect only in the opposite direction. Here, the heating unit can be configured as an air-based and / or coil-based heating unit. To enable precise adjustment of the cooling and / or heating unit 50, a temperature measuring device 45 can be provided, arranged between the nozzle 4 and the cooling and / or heating unit 50.

[0081] In another embodiment, the apparatus 1 has a crucible 55 for receiving and homogenizing clarified glass, and preferably at least one discharge pipe 56 with a specially matched diameter is arranged on the crucible 55, the discharge pipe leading particularly into the drawing groove 2. Thus, glass can be conveyed from the crucible 55 to the drawing groove 2 through the discharge pipe 56. The apparatus 1 may here have at least one, preferably multiple, or even a large number of heating elements 60, wherein at least one heating element 60 is arranged at least at the drawing groove 2, at the discharge pipe 56, and / or at the crucible 55. Figure 13 In the example shown, multiple heating elements 60 may also be arranged on the drawing groove 2, on the discharge pipe 56, and / or on the crucible 55, respectively, to enable precise adjustment of the temperature and distribution of the glass in the drawing groove 2.

[0082] In the context of this invention, the heating element 60 is understood as a device suitable and intended for outputting energy to the drawing trough 2, the discharge pipe 56, and / or the crucible 55 and / or its contents. This energy may be output in the form of thermal energy, electrical energy, or, for example, magnetic energy. Here, the heating element 60 may have one or more heating coils and / or flanges that at least partially or completely surround the drawing trough 2, the discharge pipe 56, and / or the crucible 55 in at least one direction. Therefore, generally, the drawing trough 2, the discharge pipe 56, and / or the crucible 55 and / or its contents can be directly heated by means of thermal energy delivered by the heating element 60, or the drawing trough 2, the discharge pipe 56, and / or the crucible 55 can be self-heated, for example, by induction or input current, preferably through at least one or more flanges. It is conceivable that a current flowing through the drawing trough 2, the discharge pipe 56, and / or the crucible 55 can be generated by means of at least two flanges, or a magnetic field can be generated through at least one flange, the magnetic field supplying energy to the drawing trough 2, the discharge pipe 56, and / or the crucible 55 in an induced manner. Therefore, advantageously, the drawing groove 2, the discharge pipe 56, and / or the crucible 55 can be made of thermally and / or electrically conductive materials, such as metal. Generally, heating can be carried out, particularly indirectly and preferably over a large area, by means of the heating element 60, thus reducing, for example, the formation of glass defects. The temperature can also be finely adjusted, particularly locally.

[0083] Not limited to Figure 13 For example, heating elements 60 can be arranged on crucible 55 at the upper inlet and lower outlet, respectively, so that the glass enters the discharge tube 56 at the desired temperature. The discharge tube 56 has three heating elements 60, one located in the upper third, one in the middle third, and one in the lower third. Preferably, the discharge tube 56 is divided into two to four electric heating circuits 61 in this way, which in particular enables very fine temperature control and ensures uniform distribution of the glass as it enters the drawing groove.

[0084] In another embodiment, the drawing groove 2 has a plurality of, particularly at least four, heating elements 60, which preferably divides the heating of the drawing groove (2) into three electric heating circuits. The heating circuits can also be understood as different spatial arrangements or different heating zones of the drawing groove 2, which, for example, can heat defined volumetric regions of glass within the drawing groove. Here, the heating circuits 62 of the drawing groove 2 are preferably arranged in series with respect to the length L of the nozzle slit 5 to influence the glass distribution in the transverse direction or along the length L of the nozzle slit 5. Therefore, the glass distribution at the nozzle slit 5 and the flow rate (Durchsatz) of the glass stream at the nozzle 4 can be adjusted via temperature control of the discharge pipe 56 and the drawing groove 2. Preferably, the heating elements 60 are arranged such that at least two or three, particularly a plurality of, heating circuits 62 are formed. In this case, at least two of the heating circuits 62 and / or heating elements 60 may be arranged on the sides of the drawing groove 2, particularly forming at least three heating circuits 62, with at least one other heating circuit 62 arranged in the middle of the drawing groove 2. Here, each heating circuit 62 may be surrounded, limited, or closed by at least two heating elements 60.

[0085] Therefore, without being limited to the specific features of a particular embodiment, this objective is generally also achieved by an apparatus 1 for drawing glass strips 10 from molten glass 9, wherein the apparatus 1 has a crucible 55 for receiving a melt composed of clarified glass and a discharge pipe 56 for conveying the molten glass into a drawing groove 2, wherein at least the drawing groove 2 has a plurality of heating elements 60, which are preferably arranged transversely to the length L of the nozzle slit 5 of the nozzle 4 through which the molten glass 9 flows downward, wherein the apparatus 1 has at least one, and in particular a plurality of, cooling and / or heating units 50 arranged in the forming region 14. Preferably, and in this embodiment, the nozzle slit 5 is curved downward in the drawing direction Z, particularly continuously or coherently, toward the ends 7a, 7b of the nozzle slit 5 in the first side region 8a and the second side region 8b, such that the ends 7a, 7b are lower than the intermediate region 8c of the nozzle slit 5 arranged between the ends 7a, 7b. To homogenize the glass, a stirring unit can be installed in the crucible 55, and the rotation speed of the stirring unit per time unit can be adjusted.

[0086] List of reference numerals

[0087] 1. Apparatus for drawing glass ribbons

[0088] 2. Drawing groove

[0089] 3. Cooling equipment

[0090] 4 nozzles

[0091] 5. Nozzle slot

[0092] 6. The wall of the nozzle or nozzle slot

[0093] 7a First end

[0094] 7b Second end

[0095] 8a Nozzle slit first side area

[0096] The second side area of ​​the 8b nozzle slot

[0097] The middle area of ​​the 8c nozzle slot

[0098] 9. Glass melt

[0099] 10 glass ribbons

[0100] 11 boundaries

[0101] 14 forming areas

[0102] 15 drawing rollers

[0103] 20. Protrusion

[0104] 21. Lower wall of the protrusion

[0105] 22 End wall of the protrusion

[0106] 23. Lower end of the protrusion

[0107] 24 upper wall of nozzle

[0108] 25 sidewalls

[0109] 30 Lower boundary of the intermediate region

[0110] 40 Annealing Furnace

[0111] 41 Cooling and / or heating sections

[0112] 42 thermocouples

[0113] 45 Temperature measuring equipment

[0114] 50 cooling and / or heating units

[0115] 55 crucible

[0116] 56 Discharge pipe

[0117] 60 heating elements

[0118] Heating circuit for 61 discharge pipe

[0119] Heating circuit for 62 drawing groove

[0120] B width

[0121] Bk utilizes the width of the glass ribbon produced by the curved nozzle slit.

[0122] Bp utilizes the width of the glass ribbon produced by parallel nozzle slits.

[0123] Bs nozzle slit width

[0124] Bv width of the protrusion

[0125] H Nozzle height / Protrusion height

[0126] L is the length of the nozzle slit.

[0127] The length of the Lv protrusion

[0128] R is the radius of the bend.

[0129] Inflection point of the W-bend

[0130] Z-direction pulling.

Claims

1. An apparatus (1) for drawing a glass strip (10) from a glass melt (9), wherein, The device (1) has a drawing groove (2) for receiving molten glass (9), the drawing groove (2) having a nozzle (4) including a through opening through which the molten glass (9) can be discharged downward, wherein the through opening is formed as a nozzle slit (5) having two ends (7a, 7b), wherein the length L of the nozzle slit (5) is greater than its width B, wherein the nozzle slit (5) faces the ends (7a, 7b) of the nozzle slit (5) in the first side region (8a) and the second side region (8b). 7b) Bend downward along the drawing direction Z such that the ends (7a, 7b) are lower than the middle region (8c) between the ends (7a, 7b) where the nozzle slit (5) is arranged, and wherein the width of the nozzle slit (5) changes from the middle toward the ends (7a, 7b), wherein the nozzle slit (5) has a continuous bend with respect to height H in the first side region (8a) and the second side region (8b), the bend having a radius R, wherein the height H extends parallel to the drawing direction Z.

2. The apparatus (1) according to claim 1, characterized in that, The nozzle slit (5) bends downward in the pulling direction Z in the first side region (8a) and the second side region (8b) toward the ends (7a, 7b) of the nozzle slit (5).

3. The apparatus (1) according to claim 1 or 2, characterized in that, The nozzle slit (5) gradually narrows from the middle to the ends, such that the width of the nozzle slit (5) in the middle region (8c) is greater than the width at its ends (7a, 7b).

4. The apparatus (1) according to claim 1 or 2, characterized in that, The nozzle slit has at least one of the following characteristics: - The nozzle slit (5) curves continuously up to the ends (7a, 7b), - The nozzle slit (5) bends into the ends (7a, 7b) and the bend has an inflection point W.

5. The apparatus (1) according to claim 1 or 2, characterized in that, The nozzle slit (5) has an oval, elliptical, concave or lenticular shape when viewed from above, i.e., relative to the length L and width B.

6. The apparatus (1) according to claim 1 or 2, characterized in that, The nozzle (4) has protrusions (20) in the first side region (8a) and the second side region (8b) for accommodating additional flow of the glass melt (9), and the protrusions (20) extend along the drawing direction Z, wherein the internal space of the protrusions (20) defines the magnitude of the additional flow.

7. The apparatus (1) according to claim 6, characterized in that, The ratio of the height H of the internal space of the protrusion (20) to the width B of the internal space of the protrusion (20) is greater than 0.2 and / or less than 2.

8. The apparatus (1) according to claim 6, characterized in that, The ratio of the height H of the internal space of the protrusion (20) to the width B of the internal space of the protrusion (20) is greater than 0.5 and / or less than 1.

6.

9. The apparatus (1) according to claim 6, characterized in that, The ratio of the height H of the internal space of the protrusion (20) to the width B of the internal space of the protrusion (20) is greater than 0.8 and / or less than 1.

2.

10. The apparatus (1) according to claim 7, characterized in that, The radius R of the curved portion of the nozzle slit (5) is defined by the height H of the protrusion (20) and the length L of the protrusion (20).

11. The apparatus (1) according to any one of claims 7 to 10, characterized in that, The ratio of the length L of the protrusion (20) to the height H of the protrusion (20) is less than 2.

8.

12. The apparatus (1) according to any one of claims 7 to 10, characterized in that, The ratio of the length L of the protrusion (20) to the height H of the protrusion (20) is less than 2.

6.

13. The apparatus (1) according to any one of claims 7 to 10, characterized in that, The ratio of the length L of the protrusion (20) to the height H of the protrusion (20) is less than 2.

4.

14. The apparatus (1) according to claim 6, characterized in that, The curved section of the protrusion (20) in the first side region (8a) is opposite to the curved section of the protrusion (20) in the second side region (8b).

15. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The height Hv of the internal space of the protrusion (20) is greater than 10 mm and / or less than 80 mm.

16. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The height Hv of the internal space of the protrusion (20) is greater than 15 mm and / or less than 60 mm.

17. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The height Hv of the internal space of the protrusion (20) is greater than 20 mm and / or less than 40 mm.

18. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The width B of the protrusion (20) is defined as the product of the width B of the nozzle slit (5) and a value greater than 1 mm and / or less than 15 mm.

19. The apparatus (1) according to claim 18, characterized in that, The width B of the nozzle slit (5) is the width of the cross-section of the through opening.

20. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The width B of the protrusion (20) is defined as the product of the width B of the nozzle slit (5) and a value of 1.5 mm and / or less than 10 mm.

21. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The width B of the protrusion (20) is defined as the product of the width B of the nozzle slit (5) and a value greater than 2 mm and / or less than 5 mm.

22. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The radius R of the curved portion of the nozzle slit (5) is greater than 100 mm and / or less than 260 mm.

23. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The radius R of the curved portion of the nozzle slit (5) is greater than 130 mm and / or less than 230 mm.

24. The apparatus (1) according to any one of claims 7 to 10, 14, characterized in that, The radius R of the curved portion of the nozzle slit (5) is greater than 160 mm and / or less than 200 mm.

25. The apparatus (1) according to claim 6, characterized in that, The protrusion (20) has a lower wall (21) that closes the interior space of the protrusion (20) in the pulling direction Z, wherein the through opening is arranged in the lower wall (21).

26. The apparatus (1) according to claim 1 or 2, characterized in that, Multiple heating elements (60) are arranged on the drawing groove (2) so that the heating of the drawing groove (2) is divided into an electric heating circuit (62).

27. The apparatus (1) according to claim 26, characterized in that, The electric heating circuit (62) of the drawing groove (2) is arranged in series with respect to the length L of the nozzle slit (5).

28. The apparatus (1) according to claim 1 or 2, characterized in that, The device (1) has at least one spatially distributed cooling and / or heating unit (50) arranged in the molding area (14).

29. The apparatus (1) according to claim 1 or 2, characterized in that, The device (1) has a plurality of spatially distributed cooling and / or heating units (50) arranged in the molding area (14).

30. A method for drawing a thin glass strip (10) from a glass melt (9), wherein, The glass is melted and discharged from the drawing groove (2) and drawn downward in the drawing direction Z to form the thin glass strip (10). The drawing groove (2) carries the molten glass (9) and has a through opening. After leaving the through opening, the thin glass strip (10) is cooled until it is below the glass transition temperature T. g The thin glass strip (10) is pulled out along the drawing direction Z by contacting a drawing roller (15), which transmits the pulling force to the thin glass strip (10), wherein the drawing roller (15) operates when the glass temperature is below the glass transition temperature T. g When in contact with glass, the device (1) according to any one of the preceding claims is used, the device (1) comprising a nozzle (4) having a protrusion (20) that reacts to the contraction of the thin glass strip (10).

31. The method according to claim 30, characterized in that, The nozzle is designed such that the tension of the thin glass strip (10) generated below the through opening is divided at the protrusion (20) into a vertical force component Kv and a horizontal force component Kh, wherein a forming force Uz is generated in the thin glass strip (10) acting in opposite directions, and the proportion of the horizontal forming force component Uh relative to the proportion of the vertical forming force component Uv increases toward the first end (7a) and the second end (7b).

32. The method according to claim 30 or 31, characterized in that at least one of the following features: - Draw thin glass strips with a thickness of up to 70 μm (10). - The glass strips are successively pulled out from the same nozzle, and the thickness difference of the glass strips is at least 1.5 times.

33. The method according to claim 30 or 31, characterized in that at least one of the following features: - Draw thin glass strips with a thickness of up to 50 μm (10). - The glass strips are successively pulled out from the same nozzle, and the thickness difference of the glass strips is at least 2 times.

34. The method according to claim 30 or 31, characterized in that, Thin glass strips with a thickness of up to 20 μm are drawn (10).

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