Method and apparatus for manufacturing flat glass

Abstract

The invention relates to a method and an apparatus for manufacturing flat glass. A glass ribbon is obtained from a melt by means of a drawing process, the glass ribbon having an available region and an edge region thicker than the available region, the glass ribbon is cooled, during which a laser beam is directed to the glass ribbon by means of at least one laser such that the laser beam sweeps a line in the drawing direction of the glass ribbon moving horizontally as a result of the movement of the glass ribbon, the point of incidence of the laser beam is selected such that the line forms a preset separation line between the available region and the thickened edge region such that the point of incidence is located on the glass in such a manner that the temperature of the glass is in the range between a high viscosity of 1010 dPas and a low viscosity of 1015 dPas, the laser beam photo-thermally treats the glass ribbon in the irradiation region, the method further comprises the steps of forming a gap between the usable area and the thickened edge area along the line, obtaining a glass ribbon having a uniform glass thickness and a new edge, obtaining a separated thickened edge area, and continuing to cool the glass ribbon after the separation.

Description

TECHNICAL FIELD

[0001] The present invention generally relates to the manufacture of flat glass or of articles manufactured from flat glass and to the corresponding glass articles. The invention particularly relates to a method and an apparatus for machining the edges of a continuous, continuously manufactured glass ribbon. BACKGROUND

[0002] Various methods are known from the prior art for manufacturing glass ribbons. One approach, in particular for the manufacture of thin glass, consists in manufacturing the glass by means of a drawing process. In this process, a glass melt is provided, which is drawn thin by a subsequent drawing process. The glass melt can be provided in this case by various methods.

[0003] Thus, for example in the float process, the glass melt is laid down in a liquid tin bath and drawn into a ribbon. One particular characteristic of glass ribbons manufactured in the float process is the thickening of the edges of the ribbon, which are also referred to as "Borten". These Borten arise primarily as a result of the contraction of the soft glass at the edges of the ribbon due to surface tension.

[0004] Another method for manufacturing glass ribbons by means of a drawing process is by means of a drawing method such as a down-draw process or an up-draw process. In this case, the glass melt is provided in a drawing trough with a nozzle. In these processes, too, Borten arise at the edges of the glass ribbon.

[0005] In the further manufacturing process, the cooling process of the glass ribbon leads to temporary stresses due to the difference in thickness between the edge region (Borten) and the clear region between the Borten, since the Borten can be temporarily longer than the ribbon in the region between the Borten. These temporary stresses load the glass ribbon and thus increase the risk of breakage. In addition, if the glass in the thicker Borten passes through the range of the glass transition temperature later than the thinner glass in the clear region during cooling, permanent stresses arise. These permanent stresses increase with further cooling and also lead to an increased risk of breakage. Since the percentage difference in thickness between the thickened edge region and the thinner usable region is greater in thin glass ribbons than in thicker glass ribbons, the temperature difference between the Borten region and the usable region is particularly pronounced. Mechanical stresses in the glass ribbon thus increase with decreasing glass thickness. The manufacture of thin glass ribbons, in particular glass ribbons with a thickness < 1.3 mm, is therefore particularly susceptible to stress-induced breakage.

[0006] In addition to the glass thickness, the glass properties also influence stress accumulation. Thus, in particular, the coefficient of thermal expansion a liq is relatively large between the coefficient of thermal expansion a 20-300 above the glass transition temperature, relatively high stresses arise in the glass on cooling.

[0007] In principle, the aforementioned stresses can be minimized through a relatively slow cooling process. However, this is particularly impractical or difficult to achieve when the glass is a rapidly crystallizing type. In this case, the slow cooling of the glass ribbon leads to devitrification. Therefore, these glass types must be cooled as quickly as possible. However, the correspondingly rapid cooling process results in different rates of temperature change across different glass thicknesses during cooling, thus imposing varying degrees of temporary stress on different glass regions. These effects increase the risk of breakage and may therefore increase scrap rates during manufacturing. Furthermore, for rapidly crystallizing glasses, the slower cooling in the beaded edge regions leads to a higher degree of crystallization in these regions compared to the rest of the glass. Consequently, the linear coefficients of thermal expansion may also differ between the various glass regions, potentially introducing additional mechanical stresses into the glass ribbon during processing, or further increasing the mechanical stress within the glass. Therefore, flat glass with these properties is typically not manufactured using a stretching process, or the resulting glass has a relatively large thickness. Thin glass ribbons made from easily crystallizing or devitrifying glass are typically not manufactured using a stretching process, or not only using a stretching process, but are manufactured, for example, using a rolling process. Unlike glass ribbons manufactured using a stretching process, glass ribbons manufactured using a roll forming process have limitations on their maximum width and minimum thickness.

[0008] To reduce or avoid stress caused by temperature control even during rapid cooling steps, the thick edge region (bead edge) should be separated from the available area of ​​the thin net strip or glass strip as early as possible. This ensures that the stress generated during the cooling process does not overload the glass material and lead to potential glass breakage. Furthermore, by physically separating the different cooling areas of the glass, the glass strip can be cooled more quickly according to material-specific requirements without generating excessive temporary stress.

[0009] WO 2015 / 172957 A1 discloses a method and apparatus for manufacturing thin glass ribbons with a thickness not exceeding 300 micrometers, wherein the bead edges are separated. In this process, the thin glass ribbon is drawn from a glass melt or preform, the bead edges are separated from the thin glass ribbon by a separation device, and the resulting glass ribbon is cooled. Here, the separation occurs at a location in the direction of movement of the thin glass ribbon, or during the cooling process of the thin glass ribbon, the viscosity of the glass is 10. 7 dPas to 10 11Separation is performed within a range of dPas, resulting in rounded edges of the newly formed thin glass ribbon formed by separating the beads. However, this process is limited to very thin glass. The process described in WO 2015 / 172957 A1 can typically only separate glass with a thickness less than 0.3 mm. The manufacture of thin glass ribbons from easily crystallizing glass is not disclosed in WO 2015 / 172957 A1. Furthermore, the method described in WO 2015 / 172957 A1 is limited to a pull-down process. Summary of the Invention

[0010] The object of this invention is to avoid or at least reduce mechanical stress between the bead edge and the thinner usable area during the manufacturing process, particularly during the cooling process, especially in the manufacture of glass ribbons with a glass thickness of 0.1 to 1.3 mm in the usable area. Furthermore, a method is provided by which a stretching process can be used to manufacture easily crystallizable glass and / or glass with a coefficient of thermal expansion α... liq and α 20-300℃ Thin glass strips are made from glass with relatively large differences. Another objective is to provide glass articles made from easily crystallizing glass. This objective is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are given in the corresponding dependent claims.

[0011] This invention relates to a method for manufacturing a glass ribbon. In this method, a glass ribbon is first provided. Here, the glass ribbon is obtained by a stretching process. The molten glass can be supplied to the stretching process in different ways. According to a first variation, the glass ribbon is formed by stretching or lifting the molten glass in a float glass bath using a float glass method. A second variation specifies that the molten glass is supplied in a stretching bath with nozzles, and the glass ribbon is stretched from the nozzles. This can be achieved, for example, using a downward stretching process or an upward stretching process.

[0012] The glass ribbon has a usable area of ​​substantially uniform thickness and thickened edge areas. These edge areas are thicker than the usable area and are also called beaded edges or beaded regions. The beaded edges or edge areas extend along the edges of the glass ribbon in the stretching direction. The stretching direction refers to the direction in which the glass ribbon is stretched or conveyed.

[0013] The glass ribbon drawn from the melt is deflected at most once. If the glass ribbon is supplied using a float glass process, no deflection is required. In this embodiment, the glass ribbon is preferably fed flat throughout all process steps.

[0014] During the conveying process, the glass ribbon continues to cool. Preferably, the glass ribbon is drawn through a cooling furnace. In these process steps, the conveying is preferably carried out horizontally, i.e., orthogonally to gravity. In particular, no re-deflection of the glass ribbon occurs. This is especially advantageous when providing glass via the float glass process. One embodiment specifies that the glass ribbon is lifted from the float glass tank without deflection.

[0015] The thickness of the stretched or raised glass strip in the usable area is preferably at least 0.1 mm, more preferably at least 0.3 mm, particularly preferably at least 0.32 mm, and especially preferably at least 0.33 mm. According to one embodiment, the thickness of the glass strip in the usable area is at least 0.35 mm, greater than 0.35 mm, or even at least 0.4 mm. In one embodiment, the thickness of the glass strip in the usable area is at most 1.3 mm or even at most 0.8 mm.

[0016] A first variation of the invention specifies that the glass strip is lifted from the float glass tank, i.e., it is a float glass strip. According to one embodiment, the glass strip is lifted or stretched from the float glass tank and has a thickness of at least 0.1 mm or at least 0.15 mm in the usable area. Preferably, the thickness of the glass strip in the usable area is in the range of 0.1 to 1.3 mm.

[0017] According to a second variation of the method, the glass strip is preferably drawn from a drawing groove with a nozzle during either a down-drawing or up-drawing process. The glass strip provided in this variation is drawn glass. In this variation, a glass strip with a thickness exceeding 0.3 mm is obtained. The thickness of the glass is preferably at least 0.32 mm, particularly preferably at least 0.33 mm. According to one embodiment, the thickness in the usable area is at least 0.35 mm or even greater than 0.35 mm, preferably at least 0.4 mm. Preferably, the thickness of the glass strip in the usable area is at most 1.3 mm, more preferably at most 1.1 mm, particularly preferably at most 1 mm. Preferably, the thickness of the glass in the usable area is at least 0.33 mm.

[0018] During the cooling process of the glass ribbon, at least one laser is used to direct a laser beam onto the glass ribbon. Here, laser irradiation is performed at the following time points in the manufacturing process: when the glass temperature is between 10°C and 10°C. 10 The viscosity of dPas and 10 15 The viscosity of dPas is between, preferably, 10. 12 The viscosity of dPas and 10 13 The viscosity is within the range of dPas. Regarding the cooling section or device, the point of incidence on the glass is located at a temperature of 10... 10 The upper cooling point at viscosity dPas and at 1015 The range between the lower cooling points at dPas viscosity.

[0019] A laser beam is directed perpendicularly onto a glass ribbon, with one or more incident points of the laser beam located in the region between the usable area and the edge area of ​​the glass ribbon. Due to the relative movement between the glass ribbon and the laser beam, and especially due to the further transport of the glass ribbon along the stretching direction, the laser beam sweeps across a line in the stretching direction of the moving glass ribbon. This line forms a dividing line that spatially separates the usable area and the edge area of ​​the glass ribbon. According to one embodiment, the glass ribbon moves horizontally as the laser beam sweeps across the glass. This is particularly advantageous for glass manufactured using the float glass process. Another embodiment specifies that the glass ribbon is transported vertically during laser irradiation.

[0020] The wavelength of the laser is preferably selected such that it has a shallow penetration depth into the glass of the glass ribbon. The wavelength is preferably selected such that the glass ribbon is directly heated only in the near-surface region, specifically heated to a depth of up to 1 / 3 of the glass thickness in the usable area, as measured from the glass surface. According to one embodiment, the glass ribbon is heated to a depth of 0.1 mm, as measured from the glass surface. According to one embodiment, the laser beam is generated by a CO2 laser.

[0021] At the laser incident point, the glass undergoes localized photothermal treatment. This photothermal process causes intense localized heating of the glass in the relevant area, resulting in a decrease in the viscosity of the glass in the incident area and / or ablation. For the purposes of this disclosure, the term "photothermal process" refers to a process that includes glass melting and / or laser ablation. Melting and laser ablation can vary significantly depending on the relevant process parameters. Processes in which the material melts without ablation and processes primarily involving laser ablation both fall under the term "photothermal process" according to this disclosure.

[0022] According to one embodiment, the glass viscosity in the region of the incident point is significantly reduced through a photothermal process during laser irradiation. The glass melts over its entire thickness in the region of the incident point, thereby forming gaps in the region of the dividing line or forming a collection of gaps along the dividing line, and the usable area of ​​the glass is at least partially separated from the thickened edge region along this line. Thus, the usable area and the thickened edge region are mechanically separated from each other. A new edge is formed along this line.

[0023] The glass ribbons thus processed, that is, the glass ribbons consisting of the usable areas of the glass ribbons, are further cooled after the separation process.

[0024] In the method according to the invention, the temperature of the glass during laser irradiation is close to the transition point T. gWithin the temperature range between the second cooling point and the transition point according to the invention, the glass ribbon has a viscosity that counteracts the mechanical stress.

[0025] Preferably, laser irradiation is performed in a cooling furnace, particularly in the high-temperature region of the cooling furnace. According to one embodiment, the temperature in the cooling furnace during laser irradiation is at least 580°C. This places high demands on process control and adjustability. Therefore, it is essential to ensure that the optical structure of the laser has high thermal stability and that the individual components are not exposed to temperatures above their decomposition temperature. Therefore, according to one embodiment, the laser is purged with an inert gas or purge gas, and / or the individual components (e.g., deflection mirrors) are actively cooled.

[0026] Within this temperature range of the glass band, the glass can be locally heated in the region of the laser's incident point, reducing the local viscosity to a level sufficient to form a gap. This gap extends across the entire glass thickness and is also referred to as penetration. The formation of the gap or penetration can be achieved through glass melt and through a partial ablation process. In this process, the glass is melted or ablated not only in the near-surface region. The volume of the region forming the gap is determined here by the focal size of the incident laser beam (hereinafter also referred to as the laser spot diameter) and the glass thickness. Therefore, the glass is penetrated in the region of the laser beam's incident point.

[0027] Penetration can be achieved, in particular, through low viscosity and by utilizing the surface stress of the low-viscosity material. Surprisingly, once penetration is achieved, no further mechanical action is required on the glass strip to form a gap. Due to the surface stress of the glass, it contracts on both sides of the gap, forming new edges on both sides. The contracted material also forms new beaded edges at the newly formed edges in the usable area. However, due to the relatively small volume of the glass melt, these new beaded edges are small and therefore behave similarly to the glass in the usable area of ​​the glass strip during subsequent heat treatment. Unlike the separation process for glass breakage, the method according to the invention forms edges with high strength through melt rounding (Schmelzverrundung), which gives the glass strip high mechanical stability and strength during subsequent transport and processing. In particular, these edges are fire-polished.

[0028] Despite the melt rounding process, the newly formed edges only show a slight increase in melt edge thickness. This is achieved by keeping the melt volume relatively small.

[0029] Preferably, the edge is formed along the entire irradiation area. However, a re-closure may occasionally be formed at the edge.

[0030] Preferably, the two thickened edge regions or beaded edge regions of the glass ribbon are separated using the method described above. Therefore, the glass ribbon has two incident points for the two laser beams, and two new edges are formed in the usable area of ​​the glass ribbon. Thus, the glass ribbon thus formed preferably no longer has any beaded edge regions, and the usable area of ​​the glass ribbon is defined by the two newly formed edge boundaries. Therefore, the newly formed edge constitutes the side edges of the glass ribbon, wherein the side edges extend parallel to or at least substantially parallel to the transport direction of the glass ribbon.

[0031] According to one embodiment, the glass strip manufactured by the method can have a rounded profile at one or more newly formed edges.

[0032] In embodiments where the glass ribbon is horizontally conveyed and the laser beam is orthogonally incident, a gap is formed parallel to gravity. This causes the molten glass to also be pulled out of the gap region by gravity. Therefore, the corresponding embodiments are particularly suitable for manufacturing relatively thick glass ribbons without additional mechanical separation steps. This makes it particularly possible to manufacture glass ribbons with a thickness of at least 0.1 mm, especially from greater than 0.3 mm to 1.3 mm, in the usable area. One embodiment specifies that the glass thickness in the usable area of ​​the glass ribbon is in the range of greater than 0.3 mm to 1.3 mm, preferably in the range of 0.32 to 1.1 mm. Therefore, it is also particularly possible to manufacture glass ribbons with a thickness of 0.35 mm to 1 mm in the usable area, which can be used, for example, as cover glass.

[0033] Preferably, the device is designed such that the focal diameter or laser spot diameter is set at the level of the glass strip by changing the focal position via adaptive mirror optics, based on the glass size and the corresponding viscosity characteristics of the glass. The gap width can be set by the focal size of the laser beam. Here, the focal size or laser spot diameter is selected such that the gap width is large enough to avoid or at least reduce the re-contact of the glass in the edge region and the re-closure of the gap when the glass shrinks due to surface stress and possible gravity acting on the molten glass. At the same time, the focal size limits the gap width, thereby also limiting the molten volume. This prevents excessive accumulation of molten glass volume, thus preventing the re-formation of raised beaded edges.

[0034] Surprisingly, the use of a laser beam with a small focal size has proven particularly advantageous. This allows the gap width, and therefore the melt volume, to be kept as small as possible, thus offsetting edge thickening. Laser spot diameters of less than 4 mm, less than 2.5 mm, and particularly preferably less than 1.5 mm have proven particularly advantageous. According to one embodiment, the laser spot diameter is less than 1 mm or even less than 0.8 mm. In an advantageous embodiment, the laser power is modulated synchronously both spatially and temporally.

[0035] The incident laser power is preferably at least 750 W or even at least 900 W. Combined with a relatively small focal size, surprisingly, even with these relatively moderate laser powers, a sufficiently high power density can be achieved, allowing penetration of relatively thick glass. Simultaneously, the heat-affected zone and therefore the volume of the molten glass flow remain small, thus reducing edge thickening at newly formed edges. Another improvement specifies lateral and axial modulation of the laser focus. This is particularly advantageous for glass ribbons with relatively large glass thicknesses within the usable area, as modulation keeps the slit open across the entire width of the material while keeping the total energy input as low as possible. In an advantageous embodiment, the laser power is spatially and temporally modulated.

[0036] In the separation process, heat conduction to the heat-affected zone behind the opening gap causes viscous flow of the glass at the formed separation edges. In this case, localized solidification of the glass due to surface stress leads to bridging at the gap. With a large material thickness, this results in a beaded arrangement of the reclosed gaps. When the ratio of the gap length to the length of the reclosed area (also known as the glass agglomerate) is too small, the connecting material between the newly formed edges in the reclosed area causes an increase in local stress, leading to the rejection of the corresponding glass ribbon. However, the inventors unexpectedly discovered that the lateral oscillation of the laser beam in the transverse direction and / or the direction of glass ribbon feed (i.e., the longitudinal direction) can promote uniform solidification of the glass melt, thereby reducing the aforementioned bridging caused by reclosure. Occasional localized reclosure of the edges does not prevent beaded edge separation. Therefore, edges with only occasional, especially statistically distributed, reclosure are also included in the term "separated edges".

[0037] Relative motion occurs between the laser incident point and the glass ribbon along the stretching direction of the glass ribbon. In one embodiment, the laser incident point is stationary, and the relative motion corresponds to the stretching motion of the glass ribbon. The feed rate is preferably at least 1.5 m / min, more preferably at least 2.5 m / min, and particularly preferably at least 4 m / min. The correspondingly high feed rate is accompanied by a short duration of action of the glass at the laser incident point. Therefore, the aforementioned high feed rate reduces heat conduction in adjacent glass regions, thereby keeping the heat-affected zone small. This has an advantageous effect on material thickening. Furthermore, thickened glass melt connections between gaps can be avoided. On the other hand, the feed rate must be low enough to ensure complete penetration at the dividing line by the required heat conduction. Therefore, according to one embodiment, the feed rate is at most 16 m / min, preferably at most 10 m / min, or even at most 8 m / min. One embodiment specifies a feed rate of at most 6 m / min, preferably 5.5 m / min. Alternatively or additionally, the feed rate is at least 1.5 m / min, preferably at least 4 m / min, and particularly preferably at least 4.5 m / min. According to one embodiment, the feed rate during laser irradiation is in the range of 1.5 m / min to 6 m / min, preferably in the range of 4 m / min to 5.5 m / min.

[0038] According to one embodiment, the power of the irradiated laser is limited to minimize the ablation portion of the photothermal process, and glass separation is achieved primarily by reducing the glass viscosity. The corresponding process can also be referred to as soft separation. It has proven advantageous to select an upper limit of <2 kW or even a maximum of 1.5 kW for the laser power. This has proven particularly advantageous for glass thicknesses up to 0.6 mm and / or when the glass ribbon is conveyed at speeds up to 5 m / min.

[0039] The inventors have discovered that even for glass ribbons with significant thickness, complete separation can be achieved during the separation process by optimally adjusting the laser spot diameter, feed rate, laser power, and glass thickness, while maintaining an edge with almost no thickening. Therefore, an improved scheme specifies that the following conditions apply to the ratio of laser power, laser spot diameter, and feed rate: Laser power / (laser spot diameter × glass thickness × feed rate) > 6 × 10 8 W·s / m 3 A particularly advantageous finding is that the ratio > 1×10⁻⁶. 9 W·s / m 3 or even > 4×10 9 W·s / m 3 According to one embodiment, the ratio is 6 × 109 Up to 30×10 9 W·s / m 3 Within the range.

[0040] According to one embodiment, the intensity distribution of the laser can be a Gaussian distribution or a similar continuous distribution, or it can be top-hat shaped. It has been shown that using a laser with a top-hat shaped intensity distribution is particularly advantageous for separating glass ribbons with usable thicknesses in the mm range or at least 1 mm. Therefore, the corresponding glass thickness requires the laser source used to have a high peak power. Surprisingly, it has been found that, since the glass body is already close to the transition temperature T0... g Consequently, the reduction of thermomechanical stress at the temperature adjusted for glass is significantly faster than expected and less significant than in typical processes at room temperature. Therefore, glass materials are less prone to edge damage (e.g., shattering) or breakage due to locally introduced temporary stress.

[0041] In lasers with a Gaussian intensity distribution, the glass region located at the edge of the beam profile is irradiated with an intensity insufficient to penetrate, but only reducing the viscosity of the glass to the point of localized, limited flow or temporarily relieving thermomechanical stress without contributing to the intentional formation of a gap. This means the heat-affected zone is significantly larger than the gap width, resulting in localized melt edge rise in the usable area of ​​the glass band. In contrast, the area with an intensity above the ignition threshold for laser processing is significantly larger in a top-hat intensity distribution due to its steeper lateral transition compared to a Gaussian intensity distribution, thus significantly reducing the heat-affected zone. Therefore, undesirable effects such as melt edge rise can be reduced. Furthermore, energy is utilized more efficiently in a top-hat intensity distribution.

[0042] The aforementioned process steps for edge separation can also achieve a rapid cooling rate of the glass ribbon using the disclosed methods, without accumulating excessive stress in the glass or causing it to crack. According to one embodiment, after the edges have been separated, the glass ribbon is cooled at a cooling rate greater than 100 K / min, preferably greater than 200 K / min, or even greater than 300 K / min. The early edge separation according to the invention and the resulting high cooling rate also enable the manufacture of thin glass ribbons from highly crystallizable glass using the disclosed process.

[0043] Therefore, according to a third variation of the method, a glass is provided for which the following conditions apply: >1. Preferred > 1.1.

[0044] Here, α liq α is the linear thermal expansion coefficient of glass above its glass transition temperature. 20-300The linear thermal expansion coefficient of glass at temperatures between 20°C and 300°C. liq The liquidus viscosity of glass is given by [the value of the liquidus]. At the upper cooling point or at the viscosity of the glass 10 13 The slope of the viscosity curve at temperature T when dPas is 0. 13 Viscosity of glass 10 13 The temperature at dPas. The slope of the viscosity curve at the upper cooling point is calculated here using the Vogele-Taman-Fulcher coefficient (also known as the VTF coefficient).

[0045] Glasses meeting the above conditions exhibit a high tendency for devitrification or crystallization; therefore, in the stretching process, especially when manufacturing thin glass, preferably with a thickness of at most 1.3 mm in the usable area, a high cooling rate is required. According to one embodiment, glass suitable for the following conditions is provided: >1.2.

[0046] According to one improvement, the glass is a crystallizable glass used in the manufacture of glass-ceramics, hereinafter also referred to as a preform glass. In particular, the glass is a preform glass used in the manufacture of LAS glass-ceramics or AS glass-ceramics.

[0047] Another aspect of the invention relates to a glass ribbon that can be manufactured by the above method, the glass ribbon having two opposing surfaces and a uniform glass thickness extending between the two surfaces. The glass ribbon with uniform thickness has a thickness of d. 中心 The central region and at least two thicknesses of d 边缘 The edge region. The edge region forms the edge of the glass ribbon. A glass ribbon with uniform thickness, especially one with a thickness of d. 边缘 The edge region and thickness d 中心 The glass band in the central region, wherein the maximum thickness d in the edge region. 边缘、最大 Thickness d of the central region 中心 The thickness is at most 150%. Therefore, the glass ribbon does not have a thickened edge region in the form of glass beads. A glass ribbon with uniform thickness can also be called a glass ribbon without beads. The thickness of the glass ribbon is preferably at most 1.3 mm, and particularly preferably at most 0.8 mm.

[0048] According to the first variant, the glass ribbon with uniform thickness is float glass, and preferably has a higher tin concentration on one of its two surfaces than the matrix glass. The increase in tin concentration is attributed here to the floating of the molten glass in the tin bath. Therefore, in this embodiment, the glass ribbon is manufactured using the float process. The glass ribbon with uniform thickness preferably has a thickness d in the central region. 中心 The thickness is at least 0.1 mm, preferably greater than 0.3 mm, and particularly preferably at least 0.33 mm. In this embodiment, the thickness d 中心 Preferably, the thickness is in the range of 0.1 mm to 1.3 mm, and particularly preferably in the range of 0.1 mm to 0.8 mm.

[0049] According to the second variation, the glass strip with uniform thickness is a stretched glass strip and / or has two fire-polished surfaces. In this embodiment, the glass strip with uniform thickness preferably has a thickness d in the central region. 中心 The thickness is greater than 0.3 mm, preferably at least 0.32 mm, particularly preferably at least 0.33 mm, 0.35 mm, or even at least 0.4 mm. Alternatively or supplementarily, in this embodiment, the thickness of the central region is at most 1.3 mm, preferably at most 1.1 mm, and particularly preferably at most 1 mm. According to one embodiment, the thickness d 中心 The range is from 0.32 mm to 1.3 mm, preferably from 0.33 mm to 1.1 mm, and particularly preferably from 0.4 mm to 1 mm.

[0050] As an alternative or supplement to the two variant schemes mentioned above, according to the third variant scheme, the glass with a glass strip of uniform thickness satisfies the following condition: >1. Preferred >1.1. Especially preferred >1.2.

[0051] Here, α liq α is the linear thermal expansion coefficient of glass above its glass transition temperature. 20-300 The linear thermal expansion coefficient of glass at temperatures between 20°C and 300°C. liq The liquidus viscosity of glass is given by [the value of the liquidus]. At the upper cooling point or at the viscosity of the glass 10 13 The slope of the viscosity curve at temperature T when dPas is 0. 13 Viscosity of glass 10 13The temperature at dPas. The slope of the viscosity curve at the upper cooling point is calculated using the Vogele-Taman-Fulcher coefficient (also known as the VTF coefficient). In this embodiment, the glass thickness is preferably no more than 1.3 mm.

[0052] One improved scheme specifies that the edge region has a thickness d. 边缘 The maximum thickness d of the edge region 边缘、最大 The preferred thickness d of the central region 中心 Up to 120%, particularly preferably up to 100%. Therefore, due to localized characteristics, the newly formed edge region has very little mass and therefore requires very little material to cool. If a glass ribbon of uniform thickness is in T... g If the cooling process is repeated, permanent material stress can be minimized more quickly because the volume of the new edge portion and usable area of ​​the glass ribbon with uniform thickness (i.e., a glass ribbon without beaded edges) is relatively small. Therefore, the difference in cooling process between these two regions is minimized, resulting in a significantly higher cooling rate compared to the original glass ribbon with beaded edges, without stress being generated between the various regions of the glass ribbon.

[0053] According to another aspect, the present invention relates to a plate-shaped or sheet-shaped glass article, particularly a flat glass. The plate-shaped or sheet-shaped glass article specifically refers to a glass article having two opposing surfaces and an edge surface located between the two opposing surfaces, the two opposing surfaces having lateral extensions in the x and y directions. The extension of the edge surface in the z direction corresponds to the glass thickness d. 玻璃 The lateral dimensions of two surfaces in the x and y directions are greater than the glass thickness. This glass article is particularly suitable for use as cover glass, for example, as cover glass in displays or for use in the manufacture of displays.

[0054] Preferably, the glass article is made using the above-described method or from the above-described glass strip, or is capable of being made using the above-described method or from the above-described glass strip. According to one embodiment, the glass of the glass article is stretched glass, particularly stretched float glass. Because during the manufacturing process of the stretched glass article, its surface does not contact the surface of the forming tool, such as a roller, in a formable state, both surfaces of the glass article have low roughness. One embodiment specifies that at least one surface of the glass article is fire-polished. Conversely, for example, for glass articles obtained by a roll forming process, there may be at least one surface whose minimum roughness is limited by the roughness of the roller and / or surface structure, provided that the corresponding surface is polished after the roll forming process.

[0055] The following conditions apply to the properties of glass used in glass products: >1. Preferred > 1.1. Especially preferred > 1.2.

[0056] Here, α liq α is the linear thermal expansion coefficient of glass above its glass transition temperature. 20-300 The linear thermal expansion coefficient of glass at temperatures between 20°C and 300°C. liq The liquidus viscosity of glass is given by [the value of the liquidus]. At the upper cooling point or at the viscosity of the glass 10 13 The slope of the viscosity curve at temperature T when dPas is 0. 13 Viscosity of glass 10 13 The temperature at dPas. The slope of the viscosity curve at the upper cooling point is calculated here using the Vogele-Taman-Fulcher coefficient (also known as the VTF coefficient).

[0057] The thickness d of glass products 玻璃 The minimum side dimension l in the x and y directions of the glass article is specified in one embodiment. The dimension l is within the range of 0.1 mm to 1.3 mm, preferably within the range of 0.1 mm to 0.8 mm, and particularly preferably within the range of 0.3 mm to 0.8 mm. min(x, y) > 400 mm. Alternatively or additionally, according to another embodiment, the glass thickness d 玻璃 With the minimum side dimension l in the x and y directions min(x, y) The aspect ratio between them is: l min(x,y) / d 玻璃 > 500, preferably > 1000, particularly preferably > 4000.

[0058] Preferably, the maximum glass thickness deviation of the glass product is Δglass thickness = d 玻璃(最大) – d 玻璃(最小) <0.1 mm. Alternatively or additionally, the glass thickness variation in glass articles shall not exceed 10%.

[0059] One embodiment specifies that the glass in the glass ribbon or glass article is borosilicate glass, particularly float borosilicate glass with a thickness of at least 0.25 mm or low-loss borosilicate glass with a thickness of at least 0.1 mm. Low-loss borosilicate glass specifically refers to borosilicate glass exhibiting extremely low dielectric loss at 10 GHz. Therefore, for dielectric loss at 10 GHz, tan δ < 0.0023 can be applied.

[0060] According to one embodiment, the glass of the glass article or glass ribbon is borosilicate glass and contains the following components (in weight %). SiO2 74 to 85 B2O3 8 to 25 Al2O3 0.5 to 4 Li2O 0 to 1 K2O 0.3 to 2 MgO 0 to 3 CaO 0 to 3.

[0061] According to one embodiment, the glass of the glass article or glass ribbon comprises the following components (based on oxides, in weight %): SiO2 57 to 69, preferably 59 to 69, particularly preferably 61 to 69, wherein the upper limit is preferably 67. Al2O3 17 to 25, preferably 17 to 21, B2O3 0 to 7, preferably 0 to 5, particularly preferably 0 to 4.5, Li2O 3 to 5.5, preferably 3.5 to 5.5, Na₂O 0.8 to 7, preferably 0.8 to 6, particularly preferably 0.8 to 5.5, Preferably, the sum of the contents of Al2O3 and SiO2, in weight percent, is between at least 75 and at most 92, preferably at most 90.

[0062] According to one embodiment, the glass of the glass article or glass ribbon comprises the following components (based on oxides, in weight %): The SiO2 concentration is 57 to 69, preferably 59 to 69, and particularly preferably 61 to 69, wherein the upper limit is preferably 67. Al2O3 17 to 25, preferably 17 to 21, B2O3 0 to 7, preferably 0 to 5, particularly preferably 0 to 4.5, Li2O 3 to 5.5, preferably 3.5 to 5.5, Na₂O 0.8 to 7, preferably 0.8 to 6, particularly preferably 0.8 to 5.5, K₂O: 0 to 1, preferably 0 to 0.8, particularly preferably 0 to 0.7. MgO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1. CaO 0 to 4.5, SrO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1, ZnO 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.5, P2O5 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.7, ZrO2 0 to 3, preferably 0 to 2, It may also contain impurities and / or clarifying agents and / or coloring components in a content of up to 2% by weight.

[0063] According to one embodiment, the glass of the glass article or glass ribbon comprises the following components (based on oxides, in weight %): SiO2 62-72, preferably 65-70 Al2O3 7 – 14, preferably 8 – 12 B2O3 0.1 – 8.5, preferably < 8.5 or ≤ 8, preferably 4 – 7, particularly preferably ≥ 5, especially particularly preferably > 5.5 Li2O 5-12, preferably 7-10 Na₂O 0 – 2, preferably 0 – 1, particularly preferably ≥ 0.1 and / or < 1, especially particularly preferably ≥ 0.3 and / or < 0.8 K₂O 0 – 2, preferably 0 – 1 Among them, 0.8 < Li2O / (Li2O + K2O + Na2O) ≤ 1.

[0064] According to one embodiment, the glass of a glass article or glass strip, especially a ceramicizable glass, comprises the following components (based on oxides, in weight %): SiO2 55-75, preferably 62-72 Al2O3 18-27, preferably 18-23 Li2O 2.8-5, preferably 3-5 Na2O 0-4, preferably 0-2 K2O 0-4, preferably 0-2 MgO 0-8, preferably 0-4 CaO 0.4%, preferably 0.2% SrO 0-4, preferably 0-2 BaO 0-4, preferably 0-2 ZnO 0-6, preferably 0-2 TiO2 0-4, preferably 0-3 ZrO2 0-5, preferably 1.2-4 B2O3 0-2, preferably 0-0.1 SnO2 0-2, preferably 0.05-1.6, Preferably, for the sum of components TiO2 and ZrO2, the following conditions apply: 0 < ∑ (TiO2+ZrO2) < 9.5%, preferably 1.2% < ∑ (TiO2+ZrO2) < 9.5%. Or preferably, applicable to components SnO2, ZrO2 and TiO2: 0 ≤ SnO2 / (ZrO2+TiO2) < 0.8, preferably 0.01 ≤ SnO2 / (ZrO2+TiO2) < 0.7.

[0065] According to one embodiment, the glass of the glass article or glass ribbon is a crystallizable glass, particularly a crystallizable glass used in the manufacture of lithium aluminosilicate glass ceramics (LAS ceramics), and comprises the following components based on oxides in weight percent: SiO2 65 to 71 Al2O3 10 to 15 B2O3 0 to 6 Li2O 0 to 11 Na2O 0.5 to 13 K2O 0.1 to 3 MgO 0 to 7 CaO 0 to 3 SrO 0 to 0.5.

[0066] The present invention also relates to an apparatus for manufacturing a glass ribbon of uniform thickness from a glass ribbon having a usable area and an edge area thicker than the usable area. Here, the edge area is separated. The apparatus includes: means for providing the glass ribbon, preferably a float glass bath; a cooling furnace; and a conveying means for conveying the glass ribbon from the means for providing the glass ribbon through the cooling furnace. According to one embodiment, the glass ribbon is conveyed horizontally by the conveying means. Horizontal conveying is particularly important for float glass. At least one laser beam is introduced into the cooling furnace. One embodiment specifies that the laser beam is introduced by an optical system designed as a cantilever, wherein the laser arm extends laterally into the cooling furnace. After exiting the laser, the laser beam is orthogonally deflected by a deflecting element such that the laser beam irradiates the glass ribbon perpendicular or orthogonal to the conveying or stretching direction. In an alternative embodiment, the laser beam passes vertically through the furnace top.

[0067] The laser beam is positioned relative to the glass ribbon at an incident point such that this incident point lies on the boundary region between the usable area and the bead edge region. Inside the cooling furnace, the laser is positioned such that the incident point irradiates the glass ribbon at a location where the glass temperature is at a viscosity of 10... 10 The upper cooling point and viscosity of dPas are 10. 15 The range between the lower cooling points of dPas.

[0068] According to one embodiment, the deflection element is an imaging mirror. It has been found particularly advantageous that the device has a cooling mechanism for actively cooling the deflection element or mirror.

[0069] In one improved embodiment, the laser arm is designed to be pivotable or movable. This allows the laser arm to be removed from the cooling furnace. This provides good accessibility, for example, for maintaining the laser outside the hot zone of the cooling furnace. Alternatively or additionally, the laser arm includes means for purging with inert gas.

[0070] Rollers and / or belts have been found to be particularly advantageous as conveying devices. Attached Figure Description

[0071] The following reference Figures 1 to 9 The invention will be explained in detail below. In the accompanying drawings: Figure 1 An embodiment of the method is schematically illustrated in a cross-sectional view, wherein the glass ribbon is provided by a float glass process; Figure 2 The separation method steps according to one embodiment are schematically illustrated in a top view; Figure 3 A cross-sectional view schematically illustrates one embodiment of bead edge separation; Figure 4 It shows Figure 3 Photographs of the embodiments shown; Figure 5 Another embodiment of bead edge separation is schematically illustrated in cross-section; Figure 6 A photograph of the glass block is shown; Figure 7 The cooling furnace is shown schematically in cross-section; Figure 8 A glass article according to one embodiment is schematically shown; and Figure 9 It shows Figure 8 A schematic cross-section of the embodiment shown. Detailed Implementation

[0072] Figure 1 A schematic diagram of a first variation of the method according to an embodiment of the invention is shown. In this case, molten glass 17 flows from a molten pool into a float cell 2. In this embodiment, the float cell 2 is a tin bath in a float cell 7. A glass strip 1 is formed on the float cell 2, the glass strip having a thinner usable area and thickened edge areas at both edges. Figure 1(Not shown in the image). The glass strip 1 is lifted from the float glass tank 2 by the conveying device 80 and conveyed into the cooling furnace 6 along the conveying or stretching direction 8. In this case, the glass strip 2 lifted from the float glass tank 2 moves at a speed v in the conveying direction 80. 进给 Liegend transport. From Figure 1 As can be clearly seen, in this embodiment, the glass strip 1 is transported horizontally and orthogonally to gravity. In particular, the glass strip 1 is transported horizontally throughout the entire method.

[0073] exist Figure 1 In the illustrated embodiment, laser beams 90 and 91 are respectively irradiated onto the glass strip 1 within the cooling furnace 6. Incident points 11 and 110 are selected on the glass strip 1 such that these incident points are located in the boundary region between the usable area and the thickened edge region or beaded edge region. Because this is a three-dimensional view, Figure 1 Only one laser 90 and its corresponding incident point 11 are shown in the image.

[0074] Laser 9 is positioned such that the corresponding laser beam 90 irradiates the glass strip 1 at a location where the glass temperature is at a viscosity of 10. 10 The upper cooling point and viscosity at dPas are 10. 15 The laser 9 is positioned within the range between the cooling points at dPas. Therefore, the laser 9 is positioned within the hot zone of the cooling furnace. Depending on the corresponding design of the equipment, the laser 9 can also be positioned before the cooling furnace 6, provided that the temperature of the glass ribbon 1 at that point is within 10°C. 10 dPas's high viscosity and 10 15 The viscosity can be between dPas and low viscosity.

[0075] Therefore, adopt Figure 1 The method shown allows for the separation of thickened edge or beaded regions at an early stage of the process, enabling rapid cooling of the glass ribbon 30 with a uniform thickness at a relatively high cooling rate. This makes it possible to manufacture thin float glass ribbons made of glass with a high tendency to crystallize, which were previously impossible to produce using the float process. However, using the method according to the invention, thin glass, particularly glass with a thickness of up to 1.3 mm, can also be manufactured using the float process, provided that the following conditions apply: >1 Table 1 shows the coefficient of thermal expansion, viscosity above the glass transition temperature, slope of the temperature-viscosity curve at the upper cooling point, and characteristic values ​​obtainable using formula (1) for the three embodiments. Glasses 1 to 3 are thin glasses with a thickness not exceeding 1.3 mm. Glasses 1 to 3 represent ceramicizable glasses used for manufacturing LAS glass ceramics. Therefore, these preform glasses have high crystallinity, but should exist as glass during the manufacturing of thin glasses. Therefore, devitrification during the stretching process should be avoided. Table 1 Glass 1 is a crystallizable preform glass that can be transformed into LAS glass-ceramic through a subsequent ceramization process. Glass 1 preferably has the following composition (by weight percentage): SiO2 55-75, preferably 62-72 Al2O3 18-27, preferably 18-23 Li2O 2.8-5, preferably 3-5 Na2O 0-4, preferably 0-2 K2O 0-4, preferably 0-2 MgO 0-8, preferably 0-4 CaO 0.4%, preferably 0.2% SrO 0-4, preferably 0-2 BaO 0.4, preferably 0.2 ZnO 0-6, preferably 0-2 TiO2 0-4, preferably 0-3 ZrO2 0-5, preferably 1.2-4 B2O3 0-2, preferably 0-0.1 SnO2 0.05-1.6, preferably 0.05-1.6 Preferably, the sum of components TiO2 and ZrO2 is applicable: 0 < ∑ (TiO2+ZrO2) < 9.5%, preferably 1.2 < ∑ (TiO2+ZrO2) < 9.5%. Or preferably, the sum of components SnO2, ZrO2 and TiO2 is applicable: 0 ≤ SnO2 / (ZrO2+TiO2) < 0.8, preferably 0.01 ≤ SnO2 / (ZrO2+TiO2) < 0.7.

[0076] Glass 2 is also a type of preform glass used to manufacture LAS glass ceramics.

[0077] The crystallinity required for the manufacture of glass-ceramics in this type of preform glass is accompanied by a correspondingly high tendency for crystallization. This tendency for crystallization, and the associated relatively high tendency for devitrification, has until now been an obstacle to the manufacture of thin glass in the float process of glasses 1 and 2. However, by separating the thickened edge region or beaded edge region according to the invention and the resulting rapid cooling, the devitrification process or premature crystallization during the manufacture of thin glass can be reversed in the method according to the invention.

[0078] Glass 3 is also a preform glass used to manufacture LAS glass-ceramics, and previously, glass with a thickness of approximately 4 mm could only be manufactured using the float glass process. At a glass thickness of approximately 4 mm, the cooling rate required to suppress crystallization is still low enough to avoid introducing excessive mechanical stress without separating the bead edges. However, thinner glass requires a higher cooling rate, and therefore, until now, it has been impossible to manufacture thin float glass with a smaller thickness for Glass 3. However, by separating the bead edges and the resulting higher cooling rate, even for thin glass of Glass 3, crystallization during stretching can be prevented. Therefore, using the method according to the invention, for Glass 3, extremely thin float glass, especially float glass with a thickness in the range of 0.1 mm to 1.3 mm, can also be obtained.

[0079] Figure 2 Shown in top view Figure 1 The process flow shown is a schematic diagram after the glass strip 1 is lifted from the float glass tank 2. The glass strip 1 has a central usable area 3 and two thickened edge areas or beaded edge areas 5. After the glass strip is conveyed to the cooling furnace 6, laser beams 90 and 91 from lasers 9 and 10 irradiate the glass strip 1 at the boundary area between the usable width 3 and the beaded edge areas 5, respectively. When the laser beams 90 and 91 irradiate the glass strip 1, the temperature of the glass strip 1 is below the upper cooling point of the glass and above the lower cooling point of the glass. At the incident point, the laser beam passes through the glass strip 1. Because the glass strip 1 is simultaneously fed at a speed v... 进给 Moving along the conveying direction 8, a gap is formed between the usable area 3 and the beaded edge area 5. In this case, new edges are formed in both the usable area 3 and the beaded edge area 5. Here, thickened glass strips 50 and 51 are obtained, as well as a new glass ribbon 30 with new edge areas. Here, the edge areas of the glass ribbon 30 are only slightly thicker than the center areas. The glass ribbon 30 with uniform thickness continues to be guided through the cooling furnace. Glass strips 50 and 51 are waste and can be remelted, for example. There are various options for further processing of glass strips 50 and 51. Therefore, according to one embodiment, glass strips 50 and 51 can be continued to be conveyed through the cooling furnace 6 like the glass ribbon 30 with uniform thickness. However, since the glass ribbons are connected to each other and the glass is below T gThe glass is rigid at certain temperatures, thus posing a risk of breakage when handling the separated glass strips 50 and 51, which could affect the entire glass strip 1 and the separation zone. Therefore, in another embodiment, the glass strips 50 and 51 are immediately cut into short, easily handled segments after separation from the glass strip 30 of uniform thickness. It has proven particularly advantageous in this case to perform thermal separation on the individual sub-segments of the glass strips 50 and 51. This process thus has minimal mechanical impact on the entire glass strip 1. Furthermore, the thermal separation process of the glass strips 50 and 51 is particularly easy to perform due to the relatively high temperature of the glass, i.e., slightly below Tg. Therefore, thermal shock is easily achieved. A further improvement here is the introduction of initial defects into the glass strips 50 and 51 before thermal shock. It has proven particularly advantageous in this case to mechanically scrub the glass. Due to the high temperature of the glass, a thermally stable material, such as a highly heat-resistant metal, must be used.

[0080] Figure 3 A schematic cross-sectional view illustrating the separation of the thickened edge region 5 from the glass strip 1 is shown. Here, the incident point 11 of the laser beam 90 is located at the boundary region between the usable region 3 and the thickened edge region 5. The shaded region 12 represents the volume of glass melted by the laser beam 90. Figure 3 In the illustrated embodiment, the glass strip has a thickness d of 0.6 mm in the usable area. A CO2 laser is used as the laser source, with a radiation power of 1000 W and a focal size of 1 mm. 2 Therefore, relatively high power is radiated over a smaller area, resulting in a correspondingly higher power density. This allows gap 13 to be formed through the glass. The glass strip 1 is thus separated into a glass strip 30 and a glass bar 50 with uniform thickness, thereby forming edges 33 and 34. Due to the small focal size and the glass strip being fed at a rate of 4.3 m / min orthogonal to the laser irradiation during the process, the gap width remains small. Furthermore, the small focal size and relatively fast feed rate also result in a relatively small heat-affected zone. In particular, essentially only the glass region forming gap 13 melts.

[0081] exist Figure 3 In the illustrated embodiment, the ratio of laser power, spot size, and feed rate is adjusted so that the two glass regions 3 and 5 of the glass strip 1 are completely separated from each other by the gap 13. Simultaneously, the newly formed edges 33 and 34 have only slightly raised molten edges.

[0082] Figure 4 This is also clearly demonstrated by the photograph showing two separate glass bands, 30 and 50.

[0083] In this embodiment, the ratio of laser power to (laser spot diameter × glass thickness × feed speed) is 23 × 10. 9 W·s / m 3 .

[0084] Figure 5 and Figure 3 Similarly, a cross-sectional view shows the separation of the thickened edge region 5 from the glass strip 1 according to another embodiment. Here, 7 mm is selected. 2 The larger focal size results in a correspondingly larger melt volume 12. The glass ribbon 1 moves orthogonally to the laser radiation direction at a feed rate of 35 mm / s. Similar to the first embodiment, a gap 13 is first formed, in which a glass ribbon 30 with uniform thickness and a glass strip 50 with edges 330 and 340 are formed. Due to the larger melt volume here, and also due to the slower feed rate, it is less efficient than... Figure 4 The illustrated embodiment solidifies so rapidly that a separate region with glass clumps 14 may form between edges 330 and 340. This can occasionally cause the gap 13 to partially reclose. Since the formation of glass clumps 14 occurs only occasionally, it does not, or does not significantly, affect the separability of the bead edge 50. Therefore, in this disclosure, edges 330 and 340 with separate glass clumps 14 are also referred to as separate edges. Thus, during the process, for example due to vibration or movement of the glass edges 330 and 340, the individually formed glass clumps may spontaneously break off, thereby releasing the two glass edges 330 and 340 without further process steps.

[0085] Figure 6 It shows Figure 5 A partial photograph of the example shown. A glass block 14 is formed at the location shown in gap 13 between glass edges 330 and 340. Figure 6 The portion shown here is not typical of edges 330 and 340, but rather shows a single location forming the glass block 14. However, in most cases, edges 330 and 340 are spaced apart from each other by gap 13.

[0086] Figure 7A cross-sectional view schematically illustrates a cooling furnace 6 according to one embodiment. In this embodiment, the glass ribbon is conveyed in a horizontal plane. The glass ribbon 1, with a thickened edge region 5 and a usable region 3, is conveyed horizontally through the cooling furnace 6 by a conveying device 80. The conveying direction is located in the plane shown. Laser arms 15 and 150 of lasers 9 and 10 extend laterally into the cooling furnace 6 through lateral openings in cooling furnaces 61 and 62. Each laser arm 15 and 150 also includes an imaging mirror 16 and 160. Here, laser beams 90 and 91 emitted by lasers 9 and 10 are initially emitted parallel to the glass ribbon 1 and deflected downwards by mirrors 16 and 160, respectively. At incident points 11 and 110, the laser beams 90 and 91 are orthogonal to the feed direction of the glass ribbon and irradiate the glass. Incident points 11 and 110 are located in the boundary region between the thickened edge region 5 and the usable region 3 of the glass ribbon 1. Laser arms 15 and 150 can be removed or pivoted out of the cooling furnace 6 through the side openings 61 and 62. According to one embodiment, mirrors 16 and 160 are actively cooled. Furthermore, laser arms 15 and 150 can be equipped with a device for purging (Spülung) using purge gas. Figure 7 (not shown in the image), thereby isolating the laser arms 15 and 150 relative to the environment inside the cooling furnace 6.

[0087] Figure 8 A top view schematically illustrates a glass article according to one embodiment of the invention, while Figure 9 This shows a schematic cross-sectional view through the glass article. Figure 8 and Figure 9 The illustration shown is not to scale, and in particular, the individual dimensions of the glass article are not taken into account. The glass article has two opposing side surfaces 24, 26 and a surrounding edge surface 25. The side surfaces 24, 26 have side dimensions l in the x and y directions. x l y The side dimension of the edge surface 25 in the z-direction corresponds to the glass thickness d. 玻璃 .exist Figure 8 and Figure 9 In the embodiment shown, the minimum side dimension l of side surfaces 24 and 26 in the x and y directions is... x l y > 400 mm, and glass thickness d 玻璃 < 0.8 mm. The glass article of this embodiment is manufactured using the method of the present invention and is float glass. Here, the glass is raised from the tin bath, wherein the side surface 26 is in contact with the tin bath. Therefore, the tin concentration in the near-surface region of the side surface 26 is higher than that of the bulk glass.

[0088] The glass in this glass product corresponds to glass 3 in Table 1.

[0089] The glassware was flame-polished at 24 points on its side surface.

[0090] List of reference numerals 1. Glass ribbon 2 Float Cell 3. Available area of ​​glass strip 1 4 pools 5. Thickened edge area or beaded edge of glass strip 1 6 Cooling Furnace 7. Float cell 8. Conveying or stretching direction 9, 10 lasers 11, 110 Incident Points 12 Melt volume 13 gaps 14 Glass curds 15, 150 laser arms 16, 160 mirrors 17 Molten Glass 24, 26 Side surfaces of glass products 25. Edges and surfaces of glass products 30 Glass ribbon with uniform thickness 33, 34, 330, 340 fire polished edges 50, 51 glass strips 61, 62 Lateral openings in the cooling furnace 80 Conveying device 90 and 91 laser beams.

Claims

1. A method for manufacturing a glass ribbon (30) having a uniform glass thickness, wherein the glass ribbon (1) is obtained from a melt by a stretching process, wherein: - The glass strip (1) has a usable area (3) and an edge area (5) that is thicker than the usable area, the edge area extending along the edge stretching direction (8) of the glass strip (1), wherein: - Cool the glass ribbon (1), wherein: - During cooling, a laser beam (90, 91) is aligned with the glass strip (1) using at least one laser (9, 10), such that due to the movement of the glass strip (1), the laser beam sweeps a line along the stretching direction of the horizontally moving glass strip (1), wherein, - The incident point (11) of the laser beams (90, 91) is selected such that the line (13) forms a predetermined dividing line between the usable area (3) and the thickened edge area (5), and such that... - The incident point is located on the glass at a position where the temperature of the glass is at 10°C. 10 dPas's high viscosity and 10 15 The low viscosity range of dPas, and among which, - The laser beams (90, 91) photothermally treat the glass strip (1) in the irradiation area (12), thereby forming a gap (13) along the line between the usable area (3) and the thickened edge area (5), and obtaining a glass strip (30) with uniform glass thickness and new edges (33) parallel to the stretching direction (8), and obtaining a separated thickened edge area (50), wherein, after separation, the glass strip (30) with uniform thickness continues to be cooled, wherein, - The thickness of the usable area of ​​the glass strip (1) is greater than 0.3 mm, or wherein, - The thickness of the usable area of ​​the glass strip (1) is greater than 0.1 mm and the stretching process includes a float glass process, and the glass strip (1) is lifted from the float glass tank, or wherein, - The following conditions apply to the glass in the glass strip: ＞1， Where, α liq = The linear thermal expansion coefficient of glass above its glass transition temperature, α 20-300 = The linear thermal expansion coefficient of glass at temperatures between 20℃ and 300℃ liq = Liquidus viscosity of glass = At the upper cooling point or the viscosity of the glass 10 13 The slope of the viscosity curve at temperature dPas, T 13 = Viscosity of glass 10 13 The temperature at dPas, and the thickness of the glass strip (1) in the available area preferably does not exceed 1.3 mm.

2. The method according to the preceding claims, characterized in that, It has at least one of the following characteristics: - The laser beams (90, 91) have wavelengths at which the glass of the glass strip (1) is heated only in the near-surface region by the beams, preferably to a depth not exceeding 0.1 mm. - The laser beams (90, 91) are generated using a CO2 laser. - The glass strip (1) is conveyed flat during cooling and / or during laser irradiation.

3. The method according to any one of the preceding claims, wherein, The laser spot diameter of the laser beam (90, 91) is less than 4 mm, preferably less than 3 mm, and preferably not more than 1.5 mm.

4. The method according to any one of the preceding claims, wherein, Between the incident point of the glass strip (1) and the laser (11, 110), there is a relative movement along the stretching direction (8) of the glass strip (1), wherein the feed rate of the relative movement is at least 1.5 m / min, preferably at least 2.5 m / min and particularly preferably at least 4 m / min, and / or the feed rate is at most 6 m / min, preferably at most 5.5 m / min.

5. The method according to any one of the preceding claims, wherein, The power of the laser beams (90, 91) is at least 750 W, preferably at least 900 W.

6. The method according to any one of the preceding claims, wherein, The following conditions apply to the ratio of laser power, laser spot diameter, glass thickness, and feed rate: Laser power / (laser spot diameter × glass thickness × feed speed) > 7 × 10 8 W·s / m 3 Preferred > 1×10 9 W·s / m 3 Special preference > 4×10 9 W·s / m 3 .

7. The method according to any one of the preceding claims, wherein, The glass strip (1) is provided by stretching it on a float glass tank (2) using a float glass method.

8. The method according to any one of the preceding claims, wherein, The thickness of the glass strip (1) in the usable area (3) is at least 0.32 mm, preferably at least 0.33 mm, particularly preferably at least 0.35 mm and especially at least 0.4 mm, and / or the thickness of the glass strip (1) in the usable area (3) is in the range of 0.33 mm to 1.3 mm, preferably in the range of 0.35 mm to 1.1 mm, and particularly preferably in the range of 0.4 mm to 1 mm.

9. The method according to any one of the preceding claims, wherein, The method is carried out in a cooling furnace (6).

10. The method according to any one of the preceding claims, wherein, The newly formed edge (33) is fire polished.

11. A glass ribbon (30) having a uniform thickness, said glass ribbon being capable of being manufactured using the method according to any one of the preceding claims, wherein, A glass strip (30) of uniform thickness has a central region and at least one edge region, wherein the edge region forms an edge (33) of the glass strip (30) of uniform thickness, wherein the thickness d of the glass strip (30) in the central region is... 中心 Greater than 0.3 mm, and wherein the edge region has a thickness d. 边缘 , where d 边缘 With maximum thickness d 边缘、最大 The maximum thickness is greater than the thickness d in the central region of the glass strip (30) having a uniform thickness. 中心 Up to 120%.

12. The glass strip (30) having a uniform thickness according to the preceding claim, wherein, The edge region is rounded so that the edge (33) has a rounded profile, and / or the edge (33) is fire polished.

13. The glass strip (30) having a uniform thickness according to any one of claims 11 to 12, wherein, The tin concentration in the near-surface region of one side surface of the glass strip (30) with uniform thickness is greater than the tin concentration in the matrix material.

14. The glass strip (30) having a uniform thickness according to any one of claims 11 to 13, wherein, The following conditions apply to glass with a uniform thickness (30): >

1. Preferred > 1.

1. Especially preferred > 1.

2. Where, α liq = The linear thermal expansion coefficient of glass above its glass transition temperature, α 20-300 = The linear thermal expansion coefficient of glass at temperatures between 20℃ and 300℃ liq = Liquidus viscosity of glass = At the upper cooling point or the viscosity of the glass 10 13 The slope of the viscosity curve at temperature dPas, T 13 = Viscosity of glass 10 13 The temperature at dPas.

15. A glass article, particularly in the form of a flat glass having two opposing side surfaces (24, 26) and a glass thickness d. 玻璃 ,in, The glass thickness d 玻璃 The thickness is at most 1.3 mm, preferably at most 0.8 mm, and wherein the following conditions apply to the glass of the glass article: >

1. Preferred > 1.

1. Especially preferred > 1.

2. Where, α liq = The linear thermal expansion coefficient of glass above its glass transition temperature, α 20-300 = The linear thermal expansion coefficient of glass at temperatures between 20℃ and 300℃ liq = Liquidus viscosity of glass = At the upper cooling point or the viscosity of the glass 10 13 The slope of the viscosity curve at temperature dPas, T 13 = Viscosity of glass 10 13 The temperature at dPas.

16. The glass article according to the preceding claim, wherein, The glass article is stretched glass and preferably has both side surfaces fire-polished, or The glass product in question is float glass.

17. The glass article according to any one of claims 15 to 16, wherein, The side dimension l of the side surfaces (24, 26) x l y > 400 mm and / or the minimum side dimension l for the said side surface min(x, y) and glass thickness d 玻璃 The ratio between them applies under the following conditions: l min(x,y) / d 玻璃 > 500, preferably > 1000, particularly preferably > 4000.

18. A glass strip (30) having a uniform thickness according to any one of claims 11 to 14, or a glass article according to any one of claims 15 to 17, wherein, The glass comprises the following components based on oxides, expressed in % by weight: The SiO2 concentration is 57 to 69, preferably 59 to 69, and particularly preferably 61 to 69, wherein the upper limit is preferably 67. Al2O3 17 to 25, preferably 17 to 21, B2O3 0 to 7, preferably 0 to 5, particularly preferably 0 to 4.5, Li2O 3 to 5.5, preferably 3.5 to 5.5, Na₂O 0.8 to 7, preferably 0.8 to 6, particularly preferably 0.8 to 5.5, Preferably, the sum of the contents of Al2O3 and SiO2 is between 75% and 92% by weight, and more preferably 90%.

19. A glass strip (30) having a uniform thickness according to any one of claims 11 to 14, or a glass article according to any one of claims 15 to 17, wherein, The glass comprises the following components based on oxides, expressed in % by weight: The SiO2 concentration is 57 to 69, preferably 59 to 69, and particularly preferably 61 to 69, wherein the upper limit is preferably 67. Al2O3 17 to 25, preferably 17 to 21, B2O3 0 to 7, preferably 0 to 5, particularly preferably 0 to 4.5, Li2O 3 to 5.5, preferably 3.5 to 5.5, Na₂O 0.8 to 7, preferably 0.8 to 6, particularly preferably 0.8 to 5.5, K₂O: 0 to 1, preferably 0 to 0.8, particularly preferably 0 to 0.

7. MgO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1. CaO 0 to 4.5, SrO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1, ZnO 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.5, P2O5 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.7, ZrO2 0 to 3, preferably 0 to 2, It may also contain impurities and / or clarifying agents and / or coloring components in a content of up to 2% by weight.

20. A glass strip (30) having a uniform thickness according to any one of claims 11 to 14, or a glass article according to any one of claims 15 to 17, wherein, The glass comprises the following components based on oxides, expressed in % by weight: SiO2 62-72, preferably 65-70 Al2O3 7 – 14, preferably 8 – 12 B2O3 0.1 – 8.5, preferably < 8.5 or ≤ 8, preferably 4 – 7, particularly preferably ≥ 5, especially particularly preferably > 5.5 Li2O 5-12, preferably 7-10 Na₂O 0 – 2, preferably 0 – 1, particularly preferably ≥ 0.1 and / or < 1, especially particularly preferably ≥ 0.3 and / or < 0.8 K₂O 0 – 2, preferably 0 – 1 Among them, 0.8 < Li2O / (Li2O + K2O + Na2O) ≤ 1.

21. A glass strip (30) having a uniform thickness according to any one of claims 11 to 14, or a glass article according to any one of claims 15 to 17, wherein, The glass comprises the following components based on oxides, expressed in % by weight: SiO2 55-75, preferably 62-72 Al2O3 18-27, preferably 18-23 Li2O 2.8-5, preferably 3-5 Na2O 0-4, preferably 0-2 K2O 0-4, preferably 0-2 MgO 0-8, preferably 0-4 CaO 0.4%, preferably 0.2% SrO 0-4, preferably 0-2 BaO 0-4, preferably 0-2 ZnO 0-6, preferably 0-2 TiO2 0-4, preferably 0-3 ZrO2 0-5, preferably 1.2-4 B2O3 0-2, preferably 0-0.1 SnO2 0-2, preferably 0.05-1.6, Preferably, the following conditions apply to the sum of components TiO2 and ZrO2: 0 < ∑ (TiO2+ZrO2) < 9.5%, preferably 1.2% < ∑ (TiO2+ZrO2) < 9.5%. Or preferably, the following conditions apply to components SnO2, ZrO2, and TiO2: 0 ≤ SnO2 / (ZrO2+TiO2) < 0.8, preferably 0.01 ≤ SnO2 / (ZrO2+TiO2) < 0.

7.

22. An apparatus for producing a glass ribbon (30) of uniform thickness from a glass ribbon (1) by separating an edge region (5), wherein, The glass strip (1) has a usable area (3) and an edge area (5) thicker than the usable area (3), wherein the equipment includes: a stretching device for manufacturing the glass strip (1) from the glass melt (17); a cooling furnace (6); and a conveying device (80) for conveying the glass strip (1) from the stretching device to the cooling furnace (6), wherein a laser (9, 10) is provided in the cooling furnace (6) such that a laser beam (90, 91) is directed perpendicularly to the conveying direction (8) onto the glass strip (1), wherein the incident point (11, 110) of the laser is arranged such that the incident point is located on the glass strip (1) in the boundary region between the usable area (3) and the edge area (5).

23. The device according to the preceding claim, wherein, The lasers (9, 10) have at least one laser arm (15) arranged laterally in the cooling furnace (6), wherein the laser beams (90, 91) are deflected vertically by a deflection element (16) after being emitted from the lasers (9, 10). Preferably, the device has at least one of the following features: - The device has an imaging mirror as a deflection element (16), - The device has a cooling mechanism for actively cooling the deflection element (16), - The device has at least one means for purging the laser arm (15) with a purge gas. - The laser arm (15) is movable and configured such that it can be removed from the cooling furnace (6). - The equipment has a floatation tank (7) as a stretching device. - Use rollers as conveying devices (8).

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