Device and method for stabilizing discs of a brittle material

Abstract

Method for stabilizing the position of a disk-shaped element (1) made of brittle-hard material during transport along a transport path, in particular made of glass, with an upper side surface (10) and a lower side surface (11), as well as two outer edges, comprising the following steps - Providing a disk-shaped element (1) of a given material type and thickness, - Providing a deflection arrangement comprising at least three deflection elements, with which the disc-shaped element (1) made of brittle material is deflected in its transport path with a directional component perpendicular to the surface by bending the disc-shaped element (1), wherein the first deflection element is arranged at a distance from the third deflection element and the second deflection element is arranged between the first and the third deflection element, and wherein at least one of the deflection elements is movably mounted via a tilting bearing, so that the movably mounted deflection element is pivotable about a pivot axis perpendicular to its axis of rotation,so that the position of the surface of the disk-shaped element (1) can be changed by a movement of the deflecting element, and wherein the method further comprises the following step of guiding the disk-shaped element along the transport path with its upper or lower side surface at least once over at least one deflecting element.

Description

[0001] The invention relates generally to the stabilization of the position of disc-shaped material. More specifically, the invention relates to the stabilization of the position of discs of a brittle, hard material, in particular glass.

[0002] In the production of thin glass, glass sheets or ribbons are drawn from a melt. Such a ribbon can be deflected, with or without a border, into a horizontal transport direction and wound onto a reel.

[0003] In further process steps, the glass can be rewound from one roll to another with or without a border, or unwound from the roll and separated into strip cuts or freely formed sheets.

[0004] Rolls can be formed from at least two tape sections or a plurality of sheets. The sections or sheets are usually joined together using a connecting element.

[0005] When rolling up a continuous glass ribbon, one or more layers of a non-abrasive plastic film can be provided between the individual layers of the glass ribbon in order to protect the surface of the glass ribbon against contamination and / or mechanical damage.

[0006] During transport, individual sheets can be arranged, for example, on an adhesive film serving as a carrier tape, which is then rolled up. Rolls can also be formed from at least two tape cuts or a plurality of sheets.

[0007] Furthermore, the sheets can also be sandwiched between two carriers. The carrier(s) can also be functionalized, for example, with functional coatings such as optical, electronic, or optoelectronic layers.

[0008] Instead of rolling up, a meandering layering of the glass ribbon or adhesive film with individual sheets on it can also be used.

[0009] For the transport of the glass ribbon, transport devices with rollers are used. US 7 461 564 B2 shows various arrangements of rollers, in Fig. 6 for example a chicane consisting of three rollers.

[0010] During transport of the glass ribbon, wave movements in or across the transport direction can cause instabilities in the guidance of the glass ribbon. These instabilities can lead to deviations in the winding plane during subsequent winding and damage to the glass, even leading to ribbon breakage.

[0011] A wound mirror refers to the structure of the end faces of the rolled-up glass ribbon. The end faces of the cylinder formed by rolling the glass ribbon are formed by the overlapping edges of the glass ribbon. Ideally, the edges of the rolled-up glass ribbon are flush with each other, so that the end and bottom surfaces are completely flat.

[0012] However, wave movements perpendicular to the transport direction of the glass ribbon lead to movements of the glass ribbon transverse to the transport direction, or rather, to the longitudinal direction of the ribbon. Due to these movements, the edges of the rolled-up glass ribbon are no longer flush with each other. Both the front and bottom surfaces of the rolled-up glass ribbon are then no longer flat, as the individual layers of the glass ribbon are offset from one another.

[0013] If, for example, there is an adhesive film between the individual layers of the glass ribbon, this may extend beyond the edges of the glass layers. In this case, the quality of the wrapped mirror is determined by the offset of the individual glass layers relative to each other.

[0014] The lower the quality of the wound mirror, i.e. the higher the offset of the individual glass layers against each other, the more tension occurs in the rolled-up glass ribbon.

[0015] This can lead to problems, particularly during further processing steps, including glass breakage and the associated tearing of the band.

[0016] Therefore, the highest possible quality of the wound mirror is desirable, with the quality of the wound mirror being measured in multiples of the glass thickness. This is done against the background that thin glass, i.e., glass with a maximum thickness of 300 µm, in particular, is to be transported and processed.

[0017] Therefore, it is an object of the invention to provide a device and a method which stabilizes the transport and alignment of the glass ribbon with regard to its position and thus leads to an increased quality of the winding mirror.

[0018] These objects are specified by the subject matter of the independent claims. Advantageous developments of the invention are specified in the respective dependent claims.

[0019] Accordingly, the invention provides a method for stabilizing the position of a disc-shaped element made of brittle material during transport along a transport path, in particular made of glass, having an upper side surface and a lower side surface, as well as two outer edges, which comprises the following steps: - Providing a disc-shaped element of a given material type and thickness, - Providing a deflection arrangement with at least one deflection element with which the disc-shaped element made of brittle material is deflected in its transport path with a directional component perpendicular to the surface with bending of the disc-shaped element.

[0020] The deflection element is mounted so as to be pivotable or movable in a direction perpendicular to the surface of the element, so that the position of the surface of the disc-shaped element can be changed by a movement of the deflection element.

[0021] The deflection arrangement comprises a plurality of deflection elements, wherein the deflection arrangement comprises at least three such elements. In particular, the deflection arrangement comprises a first mechanically active element with a first surface, a second mechanically active element with a second element surface, and a third mechanically active element with a third element surface.

[0022] The first element is located at a distance from the third element and the second element is arranged between the first element and the third element, wherein at least one of the elements, preferably the second element, is movably mounted via a tilting bearing, so that the movably mounted element can pivot about a pivot axis lying perpendicular to its axis of rotation.

[0023] Furthermore, the method according to the invention can comprise guiding the disc-shaped element along the transport path with its upper or lower side surface at least once over the at least one deflection element.

[0024] If there are several deflection elements, the disc-shaped element is bent in a wave-like manner over the three elements and each of the side surfaces is in contact with the element surfaces.

[0025] The deflection elements represent mechanically acting elements and impose forces or moments on the disc-shaped element.

[0026] In a particularly preferred embodiment of the invention, these mechanically active elements are formed by rollers. Therefore, without limiting the generality, the term "rollers" will be used throughout the following.

[0027] These rollers can be one-piece rollers, but can also consist of several spaced-apart elements.

[0028] However, the mechanically acting elements can also be other forms of deflection elements, such as levitation or vacuum elements.

[0029] If sheets arranged on supports are processed, the elements can be designed in such a way that they only come into contact with the support, ie only between the individual sheets.

[0030] The second roller can in particular be located at a height below a connecting line from the first roller to the third roller in order to achieve a wave-shaped or undulating guidance of the element over the rollers.

[0031] Crucial to reducing the risk of breakage of the disc-shaped element is the geometry of the roller chicane formed by the three rollers. This geometry is described by the distance between the two outer rollers and the position of the surface of the middle roller relative to the connecting line between the two outer rollers.

[0032] In a preferred embodiment of the method according to the invention, the distance between the first and third rollers is therefore selected depending on the thickness of the disc-shaped element.

[0033] The disc-shaped element to be transported may have irregularities on its surface. These may be due to production-related reasons or may only appear as a wavy structure upon impact with the rollers.

[0034] Therefore, in a further embodiment of the method according to the invention, the second roller is moved in the vertical direction in order to compensate for irregularities in the surface profile, in particular waves.

[0035] The method according to the invention is preferably used for transporting a glass ribbon. Therefore, a further development of the method according to the invention comprises, after guiding the disc-shaped element, the step of rolling up the disc-shaped element, wherein the disc-shaped element lies in layers one above the other after rolling up.

[0036] The quality of the winding mirror is of particular importance as a target parameter for winding up.

[0037] The embodiments of the method according to the invention described so far do not include any measures that allow an actively controlled improvement of the quality of the winding mirror.

[0038] Therefore, a particularly preferred embodiment of the method according to the invention further comprises the following steps - monitoring the course of the outer edges of the disc-shaped element with regard to a deviation from a straight course during the guidance of the disc-shaped element by means of a sensor or a monitoring device, and - Correcting the deviation of the course of the outer edges of the disc-shaped element from a straight course during the guidance of the disc-shaped element by pivoting the second roller and / or adjusting the position in the vertical direction of at least one of the first, second and third rollers.

[0039] The method according to the invention is preferably used in an environment in which the disc-shaped element is a glass ribbon with a predetermined thickness, which is guided in its longitudinal direction over the rollers.

[0040] When using the method according to the invention for a glass ribbon, this is particularly preferably wound into a roll after it has been guided over the rollers, wherein the quality of the winding mirror in the form of the average deviation of the position of the outer edges from the mean value of the position of the outer edges is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm.

[0041] The invention also includes a device for stabilizing the position of a brittle material during transport along a transport path, in particular a glass ribbon. This device comprises - a deflection arrangement with at least one deflection element, with which the disc-shaped element made of brittle material is deflected in its transport path with a directional component perpendicular to the surface with bending of the disc-shaped element, wherein the deflection element is pivotally mounted or movable in the direction perpendicular to the surface of the element, so that the position of the surface of the disc-shaped element can be changed by a movement of the deflection element.

[0042] The deflection arrangement comprises three deflection elements, in particular a first mechanically acting element with a first element surface, a second mechanically acting element with a second element surface and a third mechanically acting element with a third element surface, wherein - the first element is at a distance from the third element and - the second element is arranged between the first element and the third element, and wherein - at least one of the elements, preferably the second element, is movably mounted via a tilting bearing, so that this element can pivot about a pivot axis perpendicular to the axis of rotation, - wherein the disc-shaped element is guided along the transport path with its upper and lower side surfaces at least once over one of the elements, wherein the disc-shaped element is bent in the process so that each of the side surfaces is in contact with the element surfaces and is bent in a wave-like manner.

[0043] In a particularly preferred embodiment of the device according to the invention, the mechanically acting elements are rollers. These can be cylindrical in shape, one piece, but can also consist of several spaced-apart elements.

[0044] Furthermore, the mechanically acting elements can also be deflection elements of the type of levitation or vacuum elements.

[0045] In a preferred embodiment, the device comprises a fourth roller on which the disc-shaped element is rolled up after passing through the roller chicane.

[0046] Furthermore, a further development of the device according to the invention is provided, which comprises a sensor designed to detect deviations of the strip path of the disc-shaped element from a straight path. Furthermore, this further development of the device according to the invention comprises a monitoring device designed to correct detected deviations of the strip path of the disc-shaped element from a straight path by adjusting at least one of the rollers, so that the quality of the winding mirror in the form of the average deviation of the position of the outer edges from the mean value of the position of the outer edges is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm.

[0047] The invention also includes a glass production plant comprising a hot-forming device for forming a disc-shaped glass article, in particular a glass ribbon, and a device according to the invention for stabilizing the position of a disc-shaped element during transport along a transport path.

[0048] The invention also provides a glass roll having a thickness of less than 300 µm and which can be produced using the method according to the invention for stabilizing the position of a disc-shaped element. Due to the inventive stabilization of the strip position transverse to the transport direction, a particularly flat winding pattern can be achieved. According to a preferred embodiment of the invention, the average deviation of the position of the edges of superimposed layers of the glass strip is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm.

[0049] A further development of the invention provides that the glass ribbon is chemically hardened during the process according to the invention. The chemical hardening takes place through ion exchange. The chemical hardening process comprises at least the following process steps a) to c): (a) Preheating the glass ribbon to a temperature in the range of 300 to 550°C, (b) chemically hardening the glass ribbon by ion exchange in the surface areas at a hardening temperature in the range of 300 to 550°C, (c) Cooling the tempered glass ribbon to a temperature < 150°C.

[0050] After the chemical hardening process, the glass ribbon is rolled up using the method according to the invention.

[0051] According to one embodiment of the hardening process, the glass ribbon has a thickness of <300 µm, preferably in the range of 30 to 144 µm. The glass ribbon is chemically hardened by ion exchange. In particular, sodium and / or lithium ions in near-surface areas of the glass ribbon are at least partially replaced by potassium ions. For this purpose, potassium ions are applied to the glass ribbon before step a) and / or in step b).

[0052] First, in step a), the glass ribbon is heated to a temperature in the range of 300 to 550°C. The thin glass is preheated to the temperature at which the chemical hardening takes place in step b). Preheating to the hardening temperature prevents stresses from forming in the thin glass due to an excessive temperature difference during chemical hardening or due to the glass heating up too quickly, which could cause the thin glass to break during hardening. Preheating can take place, for example, in a continuous furnace. This variant is particularly suitable when the glass ribbon is already in the form of a glass roll, is to be unwound and then rewound into a glass roll. In this way, the hardening process can be integrated into a roll-to-roll process.

[0053] In another variant, the glass ribbon is already at a temperature close to the tempering temperature, for example, due to a drawing process. Thus, active heating of the glass ribbon in step a) is not necessary.

[0054] After the thin glass has been preheated to the hardening temperature in step a), the thin glass is chemically hardened in step b) by ion exchange on the glass surface. This involves an ion exchange process in which lithium and / or sodium ions in the near-surface areas of the glass are partially exchanged for potassium ions that were previously applied to the glass surface.

[0055] In the subsequent step c), the tempered glass ribbon is cooled to a temperature of < 150°C. Process steps a) to c) are carried out in continuous furnaces.

[0056] According to one embodiment of the tempering process, the glass ribbon is heated in step a) in a continuous furnace with temperature gradients. This allows the glass ribbon to be heated particularly gently, thus avoiding stresses in the glass. The furnace used in step a), also referred to below as the preheating furnace, has a temperature gradient that increases from one end of the furnace to the other. Thus, the furnace has a lower temperature T at one end. u and at the other end an upper temperature T o where T u < T o . The temperature of the furnace rises relative to the transport direction of the glass ribbon, ie the glass ribbon exits the end of the furnace at the temperature T u into the furnace. A temperature gradient between a lower temperature T u < 150°C and an upper temperature T oIn the range of 350 to 500°C, it has proven particularly advantageous in terms of stress relief in the glass ribbon and process times. Preferably, the upper temperature T o the curing temperature T H .

[0057] In step b), the glass ribbon is chemically hardened by at least partially replacing sodium and / or lithium ions in near-surface areas of the glass ribbon with potassium ions. The potassium ions are applied to the surface of the glass ribbon prior to the hardening process. The desired penetration depth of the potassium ions (depth of layer, DOL) and the degree of strength increase Cs can be adjusted via the process parameters of hardening temperature T H and curing time t H The curing time t H, i.e., the residence time in the tempering furnace can be adjusted by the feed rate of the glass ribbon as well as the length of the tempering furnace or the length of the transport path the glass ribbon travels within the tempering furnace. Suitable materials for the roller in the tempering furnace include, in particular, glass, ceramic, metal, or composites made of these materials.

[0058] After the hardening step b), the tempered glass ribbon is cooled in step c). To avoid stresses in the tempered glass, it is advantageous to use a furnace with a temperature gradient. The furnace is preferably designed as a continuous furnace and has an upper temperature T at one end. o and at the other end a lower temperature T u The tempered glass ribbon is guided through the furnace, where it reaches the upper temperature T o enters the furnace, cools down in the furnace and leaves the furnace at temperature T uleaves. A lower temperature T u of < 150°C has proven advantageous. The upper temperature T o of the furnace 350 to 550°C. In particular, an upper temperature T o , which corresponds to the curing temperature T H in the following step b) has proven to be particularly advantageous.

[0059] A further development of the curing process involves using the same continuous furnace with a temperature gradient in both steps a) and c). Since only one furnace is required, the device can be made more compact and energy can be saved.

[0060] The tempering process during the transport according to the invention can take place after the drawing process, before winding into a glass roll. The drawn glass ribbon is cleaned, dried, and tempered. Since the glass is drawn at high temperatures and thus has a correspondingly high temperature before the tempering process, the duration of the preheating can be reduced, or this process step can even be omitted entirely. This is especially true if the glass ribbon, after the drawing process, has a temperature in the range of the tempering temperature T H has.

[0061] According to one variant, the potassium ions can be applied to the surface of the glass ribbon by passing the glass ribbon through a potassium-containing melt in step b). The melt can contain, for example, KN03.

[0062] Alternatively or additionally, a potassium-containing salt solution can be applied to the top and bottom surfaces of the glass ribbon, i.e., to the upper and lower side surfaces of the glass ribbon. In this case, the potassium ions are applied before the glass ribbon is passed through the tempering furnace. Preferably, the potassium-containing salt solution is applied before preheating the glass ribbon (step a). In addition to preheating the glass ribbon, the solvent is also evaporated in step a).

[0063] The potassium-containing salt solution can be applied to the surface of the glass ribbon by spraying. The potassium-containing salt solution is preferably an aqueous solution of the salts KNO3, K3PO4, KCl, KOH, and / or K2CO3.

[0064] This makes it possible to produce a glass roll comprising alkali-containing, chemically toughened thin glass with a thickness of < 300 µm. Glass rolls with chemically toughened thin glass with a glass thickness in the range of only 30 to 145 µm can also be produced in this way.

[0065] In particular, the glass ribbon is enriched with potassium ions in the areas close to the surface. The penetration depth DOL is up to 30 µm in one embodiment. The glasses of the glass roll preferably have a penetration depth DOL in the range of 2 to 8 µm, particularly preferably in the range of 3 to 5 µm. Glasses with these penetration depths have sufficiently high strength to be used, for example, as cover glasses for touch displays in mobile electronic devices. At the same time, only short curing times are required for these relatively low exchange depths, which is advantageous from a process engineering perspective. Thus, the curing times t Hto a duration of less than one hour or even < 30 minutes. Even curing times t H in the range of 10 to 20 minutes are possible.

[0066] The aspect of the shortest possible curing time t H is of greater relevance in the tempering process integrated into the transport of the glass ribbon than in the conventional process, in which the glass remains stationary in a molten salt during ion exchange. Thus, the integrated tempering process allows for long tempering times t H slow down the entire transport process and require very low feed rates and / or a long transport distance within the curing oven. Detailed description:

[0067] The invention will be explained in more detail below with reference to further embodiments and the accompanying drawings. In the drawings, like reference numerals designate like or corresponding elements. They show: Fig. 1 the basic structure of a device for transporting a disc-shaped element made of brittle material, Fig. 2 a side view of a roller chicane, Fig. 3 another side view of a roller chicane. Fig. 4a a rigidly mounted roll with glass ribbon to be transported in side view, Fig. 4b a roller with tilting bearing with glass ribbon to be transported in side view, Fig. 5 a roller according to the invention with tilting bearing in plan view, Fig. 6 a device for transporting a disc-shaped element with a storage container for the element in the raw state and the element in the wound state, Fig. 7 the device from Fig. 6, additionally equipped with a cutting device Fig. 8 the device from Fig. 7 with take-up reel removed, Fig. 9 the device from Fig. 6 with a reel from which the disc-shaped element is unwound, as well as the element in the wound state, Fig. 10 a schematic representation of the hardening process in which the glass ribbon to be hardened is passed through a molten salt, Fig. 11 is a schematic representation of a further development of the invention, in which the hardening process follows directly after the drawing process for producing a thin glass ribbon, Fig. 12 is a schematic representation of another embodiment of the hardening process in which the potassium ions are applied to the glass ribbon in the form of an aqueous solution, Fig. 13 a schematic representation of a hardening process in which process steps a) and c) are carried out in the same oven, Fig. 14 three diagrams with cubic spline functions describing the course of a glass ribbon over three rollers.

[0068] Fig. Figure 1 shows basic elements of a device for transporting a disc-shaped element 1 made of brittle material. Due to its disc shape, the element 1 has an upper side surface 10 and a lower side surface 11 that face each other. Typically, these side surfaces 10, 11 also run parallel to each other. According to a particularly preferred embodiment, the brittle material is glass. The element 1 is also a glass ribbon 100. The glass ribbon 100 is moved along its longitudinal direction 101 by means of a transport device 7. The element 1, or specifically the glass ribbon 100, passes through an arrangement consisting of a first roller 4, a second roller 5, and a third roller 6, which together form a device 2 for stabilizing the element 1 or the glass ribbon 100. This device 2 represents a roller chicane.

[0069] The use of rollers represents a particularly preferred embodiment of the invention. As already explained, various other forms of mechanically acting elements can be used instead of the rollers.

[0070] Element 1 is bent over rollers 4, 5, and 6. The guidance of the glass ribbon 100 is such that each of the element's side surfaces 10, 11 is guided at least once over each of the three rollers 4, 5, and 6. Specifically, the glass ribbon 100 is guided with its side surface 11 over rollers 4 and 6, and with its opposite side surface 10 over the central roller 5. Because element 1 is guided with both side surfaces over rollers 4, 5, and 6 at least once, a wave-like, or undulating, path of the ribbon is created in the roller chicane.

[0071] The first roller 4 has a surface 40, the second roller 5 has a surface 50 and the third roller has a surface 60.

[0072] Specifically, the glass ribbon 100 first runs with its lower side surface 11 over the first roller 4, then with its upper side surface 10 over the second roller 5, and finally with its lower side surface 11 over the third roller 6. In the process, the glass ribbon 100 is bent. The curvature of the side surfaces 10, 11 that run over the rollers 4, 5, and 6 is concave, while that of the opposite side surface is convex. A tensile stress determined by the radius of curvature then develops at the convex curvature, while the side surface running on the roller surfaces 40, 50, and 60 experiences compressive stress in the region of the concave curvature. The latter is non-critical and does not lead to fracture.

[0073] A transport device 7 is provided to move the glass ribbon 100 over the rollers 4, 5, and 6. The transport device 7 moves the element 1, in this case the glass ribbon 100, on the one hand, and also exerts a tensile force on the element 1 in the direction of movement, so that both side surfaces 10, 11 are subjected to a tensile stress of at least 2 MPa. This tensile stress is added to the tensile stress due to the bending above the respective roller on the upper or lower side surface 10, 11 facing away from the roller, resulting in a tensile stress.

[0074] According to one embodiment of the invention, the tensile force on the element 1 is exerted by the pull of a conveyor belt 8, which is arranged downstream of the rollers 4, 5, 6 in the transport direction and adheres to the element 1. The element 1 can be adhered to the conveyor belt 8, in particular, by suction. According to this embodiment of the invention, the conveyor belt 8 is therefore a vacuum conveyor belt. In order to build up a tensile force by driving the conveyor belt 8, a device is used to hold the element 1 in place. A simple possibility for this is to provide an additional conveyor belt 9 that adheres the element 1. In particular, this additional conveyor belt 9 can also be a vacuum conveyor belt.

[0075] As already explained, the three rollers 4, 5, 6, in the form of a roller baffle, form a device 2 for stabilizing the element 1 or the glass ribbon 100. The axes of all three rollers 4, 5, 6 can be manually adjusted both horizontally and vertically using a spindle. According to the invention, the roller axis must not tilt during the adjustment process.

[0076] The rollers 4 and 6 are at a horizontal distance d ( Fig. 3, Fig. 4). This distance d is, according to the invention, between 50 and 500 mm.

[0077] Rollers 4, 5, and 6 with a width of 1,000 mm are used. The radius of rollers 4, 5, and 6 is between 10 and 200 mm, and the rollers can be changed.

[0078] EUROTEC-AS 84656 EPOM, 70 Shore A is chosen as the material for the surface of rollers 4, 5, 6.

[0079] The second or middle roller 5 can be lowered to a height h ( Fig. 3, Fig. 4) be arranged below the level at which the element 1, or the glass ribbon 100, is transported. According to the invention, this height is 0 to 300 mm. Due to the lowering of the second roller 5 relative to the rollers 4 and 6, the three rollers 4, 5, 6 of the device 2 form a roller chicane. This lowering, as shown, relates to the position of the rotation axis.

[0080] The Fig. 2 and Fig. 3 each show such a roller chicane, in which the disc-shaped element 1 or a glass ribbon 100 is guided over three rollers 4, 5, 6 in such a way that the glass ribbon 100 runs above the rollers 4 and 6 and below the roller 5. The wrap angle is shown for each of the three rollers 4, 5, 6. This is determined by drawing a straight line from the first and last point of contact of the ribbon 100 with the respective roller to the center of the roller. The angle enclosed by these two straight lines is the wrap angle. The wrap angle α1 occurs at the first roller 4, the wrap angle α2 at the second roller 5, and the wrap angle α3 at the third roller 6.

[0081] In Fig. 3 is compared to Fig. 2 the distance between the rollers 4 and 6 is reduced, which leads to a larger wrap angle α3 on the second roller 5.

[0082] The height above ground at which the glass ribbon 100 is transported is 900 to 1000 mm.

[0083] The transport speed of the glass ribbon 100 is 3 to 30 m / min.

[0084] If the disc-shaped element 1 hits one of the rollers 4, 5, 6, the element may be compressed. This is described in Fig. 4a shows the case of a rigidly mounted second roller 5. The second roller 5 is mounted by means of a rigid bearing 51. The glass ribbon 100 is transported in its longitudinal direction 101 and encounters the second roller 5. A wave-shaped compression 110 forms in front of the second roller 5. In the case of a rigidly mounted second roller 5, this compression is severe, which is associated with a high risk of breakage.

[0085] Therefore, according to the invention, at least one of the rollers 4, 5, 6, preferably the second roller 5, is movably mounted so that this roller can react to changes in the alignment of the glass ribbon 100, thus allowing a controlled alignment of the glass ribbon. Such a movable mounting of a roller is described in Fig. 4b. The second roller 5 is movably mounted by means of a tilting bearing 52. The glass ribbon 100 is transported in its longitudinal direction 101 and strikes the second roller 5. A compression 111 is again formed. However, this compression is less severe, since the second roller 5 expands upward due to its movable mounting. Due to the less severe compression, the risk of breakage for the glass ribbon 100 is significantly lower.

[0086] The movable bearing of the second roller 5 can be passive. This means that the bearing merely reacts to unevenness of the glass ribbon 100 by allowing the roller to deflect.

[0087] The movable mounting of the second roller 5 can also be actively designed. In this case, a sensor or a monitoring device is additionally provided, which detects any unevenness of the glass ribbon 100 before it hits the second roller 5 and, by means of a control device, causes the second roller 5 to change position. The change in position of the second roller 5 imparts corresponding forces or moments to the glass ribbon 100. The lateral position of the edge of the glass ribbon running out of the chicane can be adjusted by tilting the roller 5. The tilt also results in an angle between the edge of the incoming ribbon section and the section of the ribbon that has passed through.

[0088] The sensor can also be configured to detect irregular edges of the glass ribbon perpendicular to the transport direction. Such wavy edges are referred to as sabre-like edges. Depending on detected deviations of the edges from a straight line, a control device can be used to change the spatial position of one or more of the rollers 4, 5, 6 in order to correct the edge line and stabilize the ribbon line by applying forces or moments to the glass ribbon. If the glass ribbon 100 is wound onto a roll in a later process step, these corrective measures increase the quality of the winding mirror of the glass ribbon in the wound state.

[0089] Irregularities in the belt travel are detected by means of the method disclosed in DE 10 2015 108 553 of the applicant.

[0090] This method detects a process error during the production of a material strip, preferably formed as a thin glass strip, that is moved in a longitudinal direction. The process error causes a particular geometric defect in the material strip. A profile of a characteristic imprinted on the material strip, dependent on a longitudinal coordinate and influenced by the defect, is recorded, with the profile extending in a direction lateral to the longitudinal direction. The process error is then determined based on the profile of the characteristic.

[0091] Fig. 5 shows a top view of a second roller 5 with a tilting bearing 52. The second roller 5 rotates about a roller axis 53. A glass ribbon 100 is transported in its longitudinal direction 101 beneath the second roller 5. The tilting bearing 53 allows the second roller 5 to move perpendicular to the glass ribbon, i.e., perpendicular to the plane of the drawing, and thereby avoid unevenness in the surface of the glass ribbon 100, which reduces the risk of breakage of the glass ribbon 100.

[0092] The mounting of the central roller 5 can also be configured such that the roller 5 rotates around an axis that runs parallel to the transport direction. Rotations around such an axis can compensate for irregularities in the strip path, where the outer edges run obliquely to the transport direction, which would lead to a poor quality of the wound surface during subsequent winding. With the invention, however, the average deviation in the position of the edges of superimposed layers of the glass strip can be limited to less than three times the thickness of the glass strip.

[0093] Fig. Figure 6 shows the device according to the invention with the roller chicane consisting of rollers 4, 5, 6. The disc-shaped element 1 or the glass ribbon 100 is transported from left to right in the drawing by two transport devices 7 and 70. The disc-shaped element 1 or the glass ribbon 100 is drawn from a storage container 17. In the case of the glass ribbon 100, the storage container 17 contains viscous, heated glass 19, which leaves the storage container 17 as a glass ribbon due to gravity at its bottom. After leaving the storage container 17, the glass ribbon 100 is moved forward by the transport devices 7, 70 and guided over the roller chicane consisting of rollers 4, 5, 6. Upon leaving the transport device, the glass ribbon 100 is wound up so that the ribbon is ultimately in a rolled-up state 103.

[0094] In Fig. 6, the vertical position of the middle or second roller 5 is adjusted by means of a positioning device 22. This can be operated both actively and passively, as will be described in more detail later.

[0095] Fig. 7, Fig. 8 and Fig. 9 show further possible applications of the device 2 according to the invention.

[0096] Fig. 7 shows the device from Fig. 6, supplemented by a cutting device 30. The latter cuts the glass ribbon 100, for example, when the glass ribbon 100 has reached a predetermined diameter in the rolled-up state 103. Then, the roll on which the glass ribbon 100 is rolled must be replaced.

[0097] To prevent the glass ribbon 100 from moving downwards to the floor after leaving the transport device 7 during the replacement of the roll on which the glass ribbon 100 is wound, the middle roll 5 is moved downwards, i.e., lowered, by means of the positioning device 22. This results in the path along which the glass ribbon 100 is moved becoming longer. At a constant transport speed, this results in no part of the glass ribbon 100 falling downwards and being lost for further processing. This state after cutting the glass ribbon 100, during the replacement of the roll for winding the glass ribbon 100, is shown in Fig. 8.

[0098] Fig. 9 shows the device from Fig. 6, wherein instead of the storage container 17, the glass ribbon 100 is in a rolled-up state 104. Before passing the transport device 70, 7 and the chicane of the rollers 4, 5, 6, the glass ribbon 100 is unwound. The device according to the invention is in Fig. 9 is thus used for a roll-to-roll process. In such a process, the glass ribbon is unwound from the first roll, processed, and rewound. In a very simple case, the processing can also consist of producing an improved wound mirror using the device according to the invention.

[0099] The tensile stress distribution for a disc-shaped element 1, which is in the form of a glass ribbon 100, was calculated using simulations. Two different glass types were used for these calculations: AF32 and D263. The material data for these two types are as follows: AF32 Elastic modulus E = 74.8 GPa Poisson's ratio v = 0.238 Density ρ = 2430 kg / m 3 D263 Elastic modulus E = 72.9 GPa Poisson's ratio v = 0.208 Density ρ = 2510 kg / m 3

[0100] The calculations considered nine variants, each differing in terms of glass type, glass thickness, roller spacing, roller drop, and wrap angle. These variants are summarized in the table below. Nr. Glastyp Glasdicke [µm] RollenAbstand [mm] Rollen-absenkung [mm] Umschlin-gungswinkel [°] 1 AF32 50 500 100 21 2 AF32 50 500 200 40 3 AF32 50 500 300 66 4 AF32 50 250 100 49 5 AF32 50 250 200 95 6 AF32 50 250 300 125 7 AF32 100 500 100 6 8 AF32 100 500 300 62 9 D263 50 500 100 66

[0101] The roller spacing is the distance between the axes of symmetry of the two outer rollers 4 and 6.

[0102] The roller lowering describes the position of the middle roller 5 as the height of the symmetry axis of the second roller 5 below the plane in which the disc-shaped element 1 or the glass ribbon 100 is transported.

[0103] The wrap angle specified in the table above is the wrap angle α2 of the glass ribbon 100 on the middle roller 5. The wrap angle increases with decreasing roller spacing and increasing lowering of the second roller 5.

[0104] For all variants 1 to 9 shown in the table above, the following procedure was assumed for the calculation.

[0105] In a first step, the middle roller 5 is lowered by the specified value. During the lowering of the roller 5, two tensile stress maxima arise on the upper side surface 10 and one tensile stress maximum on the lower side surface 11 of the glass ribbon 100. These maxima amount to a maximum of 26.6 MPa.

[0106] Then, in a second step, the glass ribbon or rollers are accelerated to the feed speed. During this acceleration process, high temporary tensile stresses exceeding 200 MPa are created in the glass ribbon.

[0107] The third step describes the transport of the glass ribbon at a constant transport speed. The temporary tensile stresses disappear after approximately 3 to 5 seconds. A steady state is then reached in which the tensile stress in the glass ribbon 100 reaches a maximum of 27.8 MPa.

[0108] The stress distributions in the moving belt, i.e. during the transport process, were calculated compared with the stress distribution in the resting, i.e. unmoved belt.

[0109] The calculations performed showed that the tensile stress distribution in the stationary belt corresponds to the distribution in the moving belt. Only the maximum tensile stress differs between the stationary and moving belt by approximately 1 MPa, which corresponds to an increase in tensile stress of less than 5%.

[0110] A comparison of variants 1 to 6 shows that for a glass thickness of 50 µm, the level of tensile stress of approximately 26 MPa depends only on the roll diameter.

[0111] The size of the zone in which the tensile stress occurs increases with decreasing roller spacing.

[0112] The size of the zone in which the tensile stress occurs also increases with increasing roller lowering.

[0113] A comparison of variants 1 to 3 with variants 7 and 8 shows that in the case of a higher glass thickness (100 µm for variants 7 and 8) the level of the tensile stress also depends on the geometry of the roller chicane, ie on the selected combination of roller spacing and roller lowering.

[0114] No significant effect of changing the glass type used (D263 instead of AF32) could be determined. This is due to the almost identical elastic modulus of the two glass types.

[0115] The glass ribbon 100 is deflected by rollers 4, 5, and 6, resulting in bending forces within the glass ribbon 100. The extent of the deflection and thus the magnitude of the additional tensile forces occurring within the glass ribbon 100 is determined by the size of the wrap angle. The higher the wrap angle, the greater the deflection of the glass ribbon 100 and thus the bending forces occurring within the glass ribbon 100.

[0116] Assuming that the glass ribbon 100 remains in contact with a roller even between the first and last contact points, the glass ribbon is bent along a distance L equal to the length of an arc of a circular sector whose central angle is equal to the wrap angle and whose radius is equal to the roller radius. Over the distance L, the glass ribbon is then bent with a bending radius equal to the roller radius. The bending radius is correlated with the tensile force such that the tensile force increases with decreasing bending radius.

[0117] Brittle materials behave differently than, for example, ductile materials with regard to failure under load. Ductile materials, especially many metals, stretch to their yield point under bending or tensile stress and then fracture under a comparatively well-defined load. In contrast, the fracture of brittle materials does not occur at a strength limit in the sense of a material property, but rather statistically with a probability dependent on the applied tensile stress. The parameters of the fracture probability (e.g., normal or Weibull distribution) depend primarily on the processing of the respective specimen, but, in contrast to ductile materials, are only slightly dependent on the material.

[0118] Using the method described in DE 10 2014 110 856 A1 by the applicant, a bending radius can be determined for a given glass type and thickness, depending on an applied tensile stress, at which the glass is highly unlikely to break. In this method, a strip-shaped sample of the material to be tested is attached to a holder at both ends. The two holders are then pulled apart, subjecting the sample to tensile stress. The tensile force at which the sample tears apart is recorded. This is performed for several samples. From the recorded tensile forces, the mean of the bending radii corresponding to these tensile forces and their variance are calculated.

[0119] To determine the minimum bending radius, the tensile stress is taken from the simulation described above, which then in turn determines the geometry to be selected for the chicane formed by the three rollers 4, 5, 6.

[0120] Alternatively, the minimum bending radius can also be determined as a function of the applied tensile stress using the method described in DE 10 2013 110 803 A1 of the applicant.

[0121] In this process, a thin glass is subjected to a tensile force that is less than 1.15⋅min(σ¯a−Δa0.4(1−ln(ArefAappΦ)),σ¯e−Δe0.4⋅(1−lnLrefLAppΦ)), , where σ̅ a the mean value of the tensile stress at fracture in the area of ​​the sample and σ̅ e is the mean value of the tensile stress at a fracture originating from the edge of a reference specimen, and where Δ a and Δ e are the corresponding standard deviations of these means. L refdenotes the edge length of the reference sample, and A ref their area. A App denotes the area of ​​the thin glass and L App the added edge length of opposite edges of the thin glass. Φ denotes a specified maximum breakage rate within a period of at least half a year.

[0122] In a further process step, the thin glass is bent, whereby the minimum bending radius R is determined by the tensile stress σ App is in the following relationship: σApp=E1−v2t2R, where E is the elastic modulus, t is the thickness of the thin glass and v is the Poisson's ratio of the glass.

[0123] Even when choosing this method to determine the minimum bending radius, the tensile stress is taken from the simulation described above, which then in turn determines the geometry to be selected for the chicane formed by the three rollers 4, 5, 6.

[0124] Based on the minimum bending radius thus determined, the minimum roll radius is determined since, as already explained, the roll radius is equal to the bending radius of the glass ribbon 100.

[0125] A wrap angle greater than 0° is advantageous to ensure a defined minimum bending radius, which is determined by the roll diameter. To ensure reliable guidance of the glass ribbon, it is also advantageous if the ribbon does not rest solely along a line parallel to the roll axis. The wrap angles of the examples in the table above were determined using a finite element calculation.

[0126] According to another embodiment, the path of the glass ribbon, or more generally of the disk-shaped element, over the at least one deflection element of the deflection arrangement can be determined using a spline function. For this purpose, at least one support point of the spline function is provided on each of the deflection elements. A cubic spline is particularly suitable. The spline function is created with the constraint that the surface of element 1, made of brittle material, runs tangentially to the surface of the deflection element at the support points.

[0127] In the Fig. Figures 10 to 13 schematically illustrate individual steps of the curing process. The curing process shown can be integrated into the method according to the invention.

[0128] In the Fig. In the embodiment of the tempering process schematically illustrated in Figure 10, the thin glass has a thickness in the range of 30 to 144 µm. The arrows symbolize the direction of movement of the glass ribbon 100 transported by rollers 131, 132, 133.

[0129] The glass ribbon 100 is first cleaned and dried. This process step is schematically represented by the rectangle 140. The glass ribbon 100 is then passed through a continuous furnace 150. In the continuous furnace 150, the glass ribbon 100 is heated to a temperature in the range of 300 to 550°C and leaves the continuous furnace 150 at a temperature in the range of the hardening temperature T H. This avoids stresses in the glass ribbon induced by a temperature difference in the subsequent step c). Heating the glass ribbon 100 in a continuous furnace 150 with temperature gradients has proven particularly advantageous. The temperature gradient of the furnace 150 is schematically represented by the arrow 220. The temperature gradient of the furnace is determined by the lower temperature Tu and the upper temperature T o of the furnace. The opening of the furnace 150, through which the glass ribbon 100 enters the furnace, has the temperature T u Inside the furnace, the temperature rises to temperature T o so that the glass ribbon 100 has a temperature T o or close to To. Preferably, the temperature T u in the range of 20 to 150°C and / or the upper temperature T oin the range of 350 to 550°C. By heating the glass ribbon 100 with an appropriate temperature gradient, stress buildup in the glass is avoided. Heating the glass ribbon to a temperature that corresponds to the tempering temperature T has proven particularly advantageous. H in step b).

[0130] In addition, heating using a temperature gradient can reduce any existing stresses in the glass induced by the manufacturing process.

[0131] The glass ribbon 100 preheated in step a) is passed through the tempering furnace 160 in step b). The tempering furnace has a tempering temperature T H in the range of 300 to 550°C. The curing temperature T H, i.e. the temperature at which the ion exchange takes place, depends on the respective glass composition of the glass ribbon as well as on the exchange depth DOL to be achieved and the desired compressive stress Cs.

[0132] The hardening furnace 160 contains a molten salt bath 170 through which the glass ribbon 100 is drawn. The molten salt bath 170 contains potassium ions, so that an ion exchange takes place in the near-surface regions of the glass ribbon, in which sodium and / or lithium ions are exchanged for potassium ions.

[0133] In this embodiment, the roller 132 of the curing furnace 160 is located entirely or partially in the molten salt bath 170, so the material of the roller 132 should be inert or at least largely inert to the molten salt bath. Glass, metals, and ceramics have proven suitable materials for the roller 132. Composite materials made of glass, metal, and / or ceramic can also be used.

[0134] The feed speed of the glass ribbon is adjusted so that the glass ribbon moves for the required hardening time t H within the glass melt. The curing time t H depends on the curing temperature T H and the desired replacement depth (DOL). For example, penetration depths in the range of 3 to 5 µm can be achieved with curing times of between 10 and 20 minutes.

[0135] After the tempering process, the tempered glass ribbon is cooled in step c) in another continuous furnace 180. The continuous furnace 180 ensures slow cooling of the glass ribbon 100, thus avoiding stresses in the glass. In the embodiment shown, the furnace 180 also has a temperature gradient. This is represented by the arrow 221. The furnace 180 has a temperature T at the opening through which the glass ribbon 100 enters the furnace 180. o With the direction of movement of the glass ribbon 100, the temperature in the furnace 180 decreases, so that the furnace at the opening through which the glass ribbon 100 leaves the furnace has a temperature T u where T o > T u . The temperature T is preferably o in the range of the curing temperature T H .

[0136] Cooling to temperatures < 150°C has proven to be particularly advantageous.

[0137] Fig. 2 shows a variant of the hardening process, in which the hardening process is carried out after the drawing process (not shown) for producing a thin glass ribbon 101. Since the glass ribbon 101 after the drawing process has a temperature in the range of the hardening temperature TH or even higher, Fig. 2, preheating of the glass ribbon 100 (step a) is omitted. The glass ribbon 101 is merely cleaned and dried and then undergoes process steps b) and c) analogously to the process described in Fig. 1 shown variant of the curing process.

[0138] This variant is therefore particularly advantageous from an energy point of view.

[0139] The potassium ions required for ion exchange can also be applied in the form of a solution to the surfaces of the glass ribbon 100. This is Fig. 12 schematically shows a process. The glass ribbon 100 is first cleaned and dried. In a subsequent step, the glass ribbon 100 passes through the device 210, with which the solution 211 of a potassium salt is applied to the top and bottom sides of the glass ribbon 100.

[0140] This is preferably an aqueous solution. In the embodiment shown, the solution 211 is sprayed onto the surfaces of the glass ribbon.

[0141] Subsequently, the glass ribbon 100 treated in this way passes through the furnace 150 in step b), in which it is heated to a temperature in the range of the hardening temperature T H The solvent evaporates. The glass ribbon 110 then passes through the tempering furnace 160, which has a temperature T Hin the range of 300 to 550°C. In this step b), the ion exchange takes place, in which sodium and / or lithium ions in the near-surface areas of the glass ribbon are exchanged for the potassium ions previously applied to the glass surface. The selected throughput time t H depends on the desired exchange depth DOL.

[0142] In Fig. Figure 13 shows a further variant of the method according to the invention, in which the glass ribbon 100 is passed through the same continuous furnace 230 with a temperature gradient in step a) and step b). The furnace 230 has a temperature gradient, represented by the arrow 220, with a lower temperature T u and an upper temperature T o The glass ribbon 100 is drawn into and out of the furnace 230 through the two opposite openings 231 and 232. The furnace has a lower temperature T at the opening 231. uand at the opening 232 an upper temperature T o where: T o > T u

[0143] According to this variant, the glass ribbon 100 is guided through the opening 231 into the furnace 230 in step a). While the glass ribbon 100 passes through the furnace 230 in step a), it is heated and leaves the furnace 230 through the opening 232 at the temperature T o In the subsequent step b), the ion exchange takes place in the furnace 160. According to this variant of the invention, the hardening furnace 160 has only one opening 161. In this variant of the invention, the hardening roller 131 is designed as a deflection roller, so that the glass ribbon 100 undergoes a change in direction of movement due to the hardening roller.

[0144] After the glass ribbon 100 for the hardening time t Hhas been heated to the hardening temperature TH within the furnace 160, the glass ribbon 100 leaves the furnace 160 through the opening 161. To cool the thus hardened glass ribbon 100, it is pulled through the opening 232 into the furnace 230 in step c). In this case, the glass ribbon cools slowly to the lower temperature T due to the temperature gradient of the furnace. u from the opening 231 from the furnace 230.

[0145] The following describes in more detail how the course of the disc-shaped element over one or more deflection elements can be determined using a spline function and how parameters for the occurring tensile stress load can be determined from this. One embodiment of the invention with regard to a description of the course of the disc-shaped element generally consists in determining the actual minimum bending radius from the calculated course, i.e. from the spline function. This embodiment can be implemented in the inventive arrangement for belt stabilization or carried out with this arrangement in order to determine the instantaneous tensile stress determined by the position of the deflection element(s). The method of determining the minimum bending radius using spline interpolation can, however, also be used more generally as a proof test.The proof test documents and verifies that the disc-shaped element withstands the tensile stress exerted on the surface in the proof test, which is defined by the minimum bending radius.

[0146] Accordingly, a method is provided for testing the strength of a disc-shaped element 1 made of brittle material with two opposite side surfaces 10, 11, in particular made of glass, in which - the element 1 is guided with each of its side surfaces over one or more deflection elements, preferably a total of at least three deflection elements and is bent in the process, so that the side surfaces 10, 11 are subjected to tensile stress in the region in which the element 1 made of brittle-hard material, or its opposite side surface 10, 11, is in contact with the deflection element, and it is monitored and determined whether the element 1 has a defined breaking strength equal to the tensile stress applied, or whether the element 1 breaks under the applied tensile stress, the tensile stress being determined from the minimum radius of curvature of a spline function, in particular a cubic spline between support points defined on the surface of the deflection elements. Fig. Figure 14 shows three examples. Three diagrams with spline functions are shown, each of which shows the course of a disc-shaped element 1, in particular a glass ribbon, over an arrangement with three deflection elements in the form of rollers 4, 5, 6, i.e., corresponding to the examples of Fig. Describe 1-3, 6-9. The roles are described in the diagrams by corresponding functions. Due to the different scales of the abscissa and ordinate, roles 4, 5, and 6 appear oval rather than circular.

[0147] The spline function is defined by support points 41, 51, 61 on the rollers. Depending on the position of the middle roller 5, the cases shown in diagrams (a), (b), (c) result. In diagram (a), the deflection is so small that the radius of curvature at roller 5 is larger than the roller radius. In diagram (b), the roller radius of roller 5 and the radius of curvature at support point 51 are equal to one another. Finally, in diagram (c), for a single support point 51, the radius of curvature of element 1 at support point 51 is smaller than the roller radius due to the large deflection of roller 5 relative to rollers 4, 6. In this case, the course of element 1 can no longer be described by the three support points 41, 51, 61 shown. Rather, a certain wrap angle results here. The element lies along the corresponding circular arc on the roller surface, as in Fig. 2 and Fig.3. Here, the minimum radius of curvature of element 1 is then determined by the roller radius. In this case, in which the radius of curvature R E of element 1 at a support point is smaller than the radius of curvature R U of the deflection element, R E <R U , a spline function that correctly represents the course of element 1 over the deflection element with the relevant support point (and also overall) can be determined as follows: At least two support points are then provided, the position of which on the surface of the deflection element is changed until the radii of curvature of element 1 sufficiently match the radius of curvature of the surface of the deflection element. The term "sufficiently good" again refers to a deviation smaller than a specified limit. The position of the support points can be quickly found using an interpolation method. For example, the bisection method is suitable. Using bisection, the zero of a suitable function is searched for by gradually halving the interval. In particular, the zero of the difference between the radii of curvature R E - R U be searched.

[0148] However, the case where the minimum radius of curvature is determined by the curvature of the deflection element's surface does not apply to rollers 4 and 6 in diagram (c). The radius of curvature may be smaller here, even with a linear contact, than at the middle roller 5. This then leads to the side surfaces 10 and 11 being subjected to different tensile stresses. Therefore, the proof test performed may not be equally meaningful for both side surfaces.In general, without limitation to the specific examples presented, a further development of the invention provides that the disc-shaped element 1 is guided with each side surface 10, 11 over a deflection element at least once, thus subjecting the opposite side surface to tensile stress. A spline function with support points on the deflection elements is used to verify that the tensile stresses on both side surfaces 10, 11 are equal or at least differ by less than a predetermined limit. In simple terms, the spline test is used to verify that the proof test is symmetrical for given positions of the deflection elements.

[0149] In a further development of this embodiment of the invention, the position of the deflection elements can now be changed using the knowledge of the course of element 1 obtained with the spline function, such that the radii of curvature and thus the tensile stresses exerted by the bending across the deflection elements are equalized. First, a spline function with support points on the deflection elements is used to check whether the tensile stresses on both side surfaces (10, 11) are the same or at least differ by less than a predetermined limit value. If the limit value is exceeded, the position of at least one of the deflection elements is changed such that the difference in the tensile stresses on the two side surfaces 10, 11 is reduced. In this case, it is particularly suitable to reduce the distance between the deflection elements 4 and 6. List of reference symbols 1 disc-shaped element 2 Device for stabilizing 1 4 First role 5 Second role 6 Third role 7 Transport device 8 Conveyor belt 9 Conveyor belt 10 Upper side surface of 1 11 Lower side surface of 1 13 Sensor 17 storage containers 19 1, 100 in raw state 22 Positioning device for 5 24 monitoring device 30 Cutting device 40 surface of 4 41, 51, 61 support point 50 surface of 5 51 Rigid bearing of 5 52 tilting bearings of 5 53 axis of 5 60 surface of 6 70 Transport device 100 glass ribbon 101 longitudinal direction of 100 103 1, 100 in rolled up state after passing through 2 104 1, 100 in rolled up state before passing through 2 110 compression of 100 111 compression of 100 131, 132, 133 roles 140 cleaning / drying step 150, 180 continuous furnace 160 curing oven 161, 162 Openings in the curing oven 160 170 molten salt 210 Device for applying saline solution 211 211 Potassium salt solution 220 Arrow 230 oven 231, 232 Openings in the furnace 230

Claims

[1] Method for stabilizing the position of a disc-shaped element (1) made of brittle material during transport along a transport path, in particular made of glass, with an upper side surface (10) and a lower side surface (11), as well as two outer edges, comprising the following steps - Providing a disc-shaped element (1) of a given material type and thickness, - Providing a deflection arrangement comprising at least three deflection elements, with which the disc-shaped element (1) made of brittle material is deflected in its transport path with a directional component perpendicular to the surface with bending of the disc-shaped element (1), wherein the first deflection element is arranged at a distance from the third deflection element and the second deflection element is arranged between the first and the third deflection element, and wherein at least one of the deflection elements is movably mounted via a tilting bearing, so that the movably mounted deflection element can pivot about a pivot axis lying perpendicular to its axis of rotation,so that the position of the surface of the disc-shaped element (1) can be changed by a movement of the deflection element, and wherein the method further comprises the following step of guiding the disc-shaped element along the transport path with its upper or lower side surface at least once over at least one deflection element. [2] Method according to claim 1, characterized by that the deflection arrangement comprises the first mechanically active element with a first element surface, the second mechanically active element with a second element surface and the third mechanically active element with a third element surface. [3] Method according to claim 1, characterized by that the second element is movably mounted via a tilting bearing. [4] Method according to claim 1, characterized bythat the first mechanically acting element is a first roller (4) with a first roller surface (40), the second mechanically acting element is a second roller (5) with a second roller surface (50) and the third mechanically acting element is a third roller (6) with a third roller surface (60). [5] Method according to claim 1, characterized by that the distance between the first (4) and the third roller (6) is selected depending on the thickness of the disc-shaped element (1). [6] Method according to one of the preceding claims characterized by that the second roller (5) is moved in the vertical direction in order to compensate for irregularities in the surface profile, in particular waves, of the disc-shaped element (1). [7] Method according to claim 1, after guiding the disc-shaped element (1), further comprising the step of rolling up the disc-shaped element (1), wherein the disc-shaped element (1) lies in layers one above the other after the rolling up. [8] Method according to claim 1, further comprising the step of unrolling the disc-shaped element from a roller (104) prior to guiding the disc-shaped element (1). [9] Method according to one of claims 1 to 8, further comprising the steps - monitoring the course of the outer edges of the disc-shaped element (1) with regard to a deviation from a straight course during the guidance of the disc-shaped element (1) by means of a monitoring device (24), - Correcting the deviation of the course of the outer edges of the disc-shaped element (1) from a straight course during the guidance of the disc-shaped element (1) by pivoting the second roller (5) and / or adjusting the position in the vertical direction of at least one of the first (4), the second (5) and the third roller (6). [10] Method according to one of the preceding claims, wherein the disc-shaped element (1) is a glass ribbon (100) with a thickness (D) which is guided in its longitudinal direction (101) over the rollers (4, 5, 6). [11] Method according to claim 10, characterized by that the glass ribbon (100), after it has been guided over the rollers (4, 5, 6), is wound up into a roll, wherein the quality of the wound mirror in the form of the average deviation of the position of the outer edges from the mean value of the position of the outer edges is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm. [12] Method according to one of claims 6 to 11, characterized by that, when rolling up, layers of a second material, preferably a non-abrasive film and / or adhesive film, are arranged between the layers of the disc-shaped element (1) or the glass ribbon (100). [13] Method according to one of claims 1 to 12, wherein the brittle-hard material is an alkali-containing glass and the glass ribbon (100) is chemically hardened during transport along the transport path, wherein the glass ribbon has a thickness < 300 µm and the process of chemical hardening comprises at least the following steps: (a) optionally preheating the glass ribbon (100) to a temperature in the range of 300 to 550°C, (b) chemically hardening the glass ribbon (100) by ion exchange in the surface areas at a hardening temperature TH in the range of 350 to 550°C and (c) cooling the glass ribbon (100) to a temperature < 150°C, wherein before step (a) and / or in step (b) potassium ions are applied to the upper side surface (10) and the lower side surface (11) of the glass ribbon (100), the glass ribbon (100) is heated to the hardening temperature TH in step (b) and steps (a) to (c) are carried out in continuous furnaces (150, 160, 180, 230). [14] Method according to claim 13, wherein prior to step a) a solution of a potassium salt (211) is applied, preferably sprayed, to the upper side surface (10) and the lower side surface (11) of the glass ribbon (100). [15] Method according to claim 14, wherein the potassium-containing salt solution (211) is an aqueous solution and contains salts selected from the group formed by KNO3, K3PO4, KCl, KOH, K2CO3 and / or mixtures thereof. [16] Method according to claim 15, wherein the glass ribbon (100) is passed through a potassium-containing molten salt (170) in step b). [17] Method according to one of claims 14 to 16, wherein the glass ribbon (100) passes through a continuous furnace (150, 230) with temperature gradients in step (a). [18] Method according to claim 17, wherein the temperature of the continuous furnace (150) increases relative to the transport direction of the glass ribbon (100) and / or the lower temperature of the furnace T u < 150 °C and the upper temperature of the furnace To is in the range of 350 to 550 °C. [19] Method according to one of the preceding claims 14 to 18, wherein in step (c) the glass ribbon (100) is cooled in a furnace (180, 230) with temperature gradients, wherein the temperature of the furnace (180) decreases relative to the transport direction of the glass ribbon and / or the lower temperature of the furnace Tu is < 150 °C and the upper temperature of the furnace To is in the range of 350 to 550 °C. [20] A method according to any one of claims 14 to 19, wherein in step (c) the same furnace (230) is used as in step (a). [21] A method according to any one of claims 14 to 20, wherein the roller of the curing furnace (132) is made of glass, ceramic, metal or a composite material of glass, ceramic and / or metal. [22] Method according to one of claims 14 to 21, wherein the curing time tH is selected such that an exchange depth DOL in the range of 1 to 10 µm, preferably 3 to 5 µm, is achieved. [23] Method according to one of claims 14 to 22, wherein the glass ribbon (100) has a thickness of < 145 µm, preferably a thickness in the range 30 to < 144 µm. [24] Method according to one of claims 14 to 23, wherein the method comprises the step of unrolling the disc-shaped element from a roll (104) before guiding the disc-shaped element (1) and / or the glass ribbon (100) is rolled up after chemical hardening, the glass ribbon (100) being arranged in layers one above the other after rolling up. [25] Method according to one of the preceding claims, wherein the course of the disc-shaped element (1) over the deflection elements of the deflection arrangement is determined by means of a spline function, in particular a cubic spline, wherein at least one support point of the spline function is provided on each deflection element. [26] Method according to the preceding claim, characterized by that the minimum bending radius of the disc-shaped element is determined from the spline function. [27] Method according to one of the two preceding claims, characterized by that in case the radius of curvature RE of the element (1) at a support point is smaller than the radius of curvature R U of the deflection element, a spline function which correctly reproduces the course of the element (1) over the deflection element is determined by providing at least two support points whose position on the surface of the deflection element is changed until the radii of curvature of the element (1) correspond sufficiently well to the radius of curvature of the surface of the deflection element. [28] Method for testing the strength of the disc-shaped element (1) in a method for stabilising the position of the disc-shaped element (1) during transport along a transport path according to one of the three preceding claims, wherein in the method for testing the strength the element (1) is held with each of its side surfaces (10.11) is guided over one or more deflection elements, preferably a total of at least three deflection elements and is bent in the process, so that one of the side surfaces (10, 11) is subjected to tensile stress in the region in which the element (1) is in contact with the deflection element, and wherein it is monitored and determined whether the element (1) has a defined breaking strength equal to the applied tensile stress, or whether the element (1) breaks under the applied tensile stress, wherein the tensile stress is determined from the minimum radius of curvature of a spline function, in particular a cubic spline between support points defined on the surface of the deflection elements. [29] Method according to the preceding claim, characterized bythat the disc-shaped element (1) is guided with each side surface (10, 11) at least once over a deflection element and thus the opposite side surface (10, 11) is subjected to a tensile stress, wherein a spline function with support points on the deflection elements is used to verify that the tensile stresses on both side surfaces (10, 11) are the same or differ at least by less than a predetermined limit value. [30] Method according to the preceding claim, characterized by that a spline function with support points on the deflection elements is used to check whether the tensile stresses on both side surfaces (10, 11) are the same or differ at least by less than the predetermined limit value, wherein in the event that the limit value is exceeded, the position of at least one of the deflection elements is changed such that the difference in the tensile stresses on the two side surfaces (10, 11) is reduced. [31] Use of a glass roll produced according to one of claims 14 to 30 in a roll-to-roll process, wherein the roll-to-roll process comprises a coating step and / or a process step for assembling components. [32] Device for stabilising the position of a disc-shaped element (1) made of brittle material during transport along a transport path, in particular made of glass, having an upper side surface (10) and a lower side surface (11), as well as two outer edges, comprising - a deflection arrangement with at least three deflection elements, with which the disc-shaped element made of brittle material is deflected in its transport path with a directional component perpendicular to the surface with bending of the disc-shaped element, wherein the first element is located at a distance (d) from the third element and the second element is arranged between the first element and the third element, and wherein at least one deflection element is movably mounted via a tilting bearing, so that the movably mounted deflection element can be pivoted about a pivot axis lying perpendicular to its axis of rotation, so that the position of the surface of the disc-shaped element can be changed by a movement of the deflection element. [33] Device according to claim 32, characterized bythat the deflection arrangement comprises the first mechanically acting element with a first element surface, the second mechanically acting element with a second element surface and the third mechanically acting element with a third element surface. [34] Device according to claim 32, characterized by that the first mechanically acting element is a first roller (4) with a first roller surface (40), the second mechanically acting element is a second roller (5) with a second roller surface (50) and the third mechanically acting element is a third roller (6) with a third roller surface (60). [35] Device according to claim 34, characterized by a fourth roller on which the disc-shaped element (1) is rolled up after passing through the roller chicane or unwound from a roll before passing through the roller chicane. [36] Device according to one of claims 31 to 35, further comprising - a sensor (13) designed to detect deviations of the strip path of the disc-shaped element (1) from a straight path, and - a monitoring device (24) which is designed to correct detected deviations of the strip path of the disc-shaped element (1) from a straight path by adjusting at least one of the rollers (4, 5, 6) so that the quality of the winding mirror in the form of the average deviation of the position of the outer edges from the mean value of the position of the outer edges is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm. [37] Glass manufacturing plant, comprising a hot-forming device for forming a disc-shaped glass article, in particular a glass ribbon (100), and a device according to one of claims 32 to 36. [38] A roll of glass having a thickness (D) of less than 300 µm, which can be produced by the method according to one of claims 1 to 27, in which the quality of the winding mirror in the form of the average deviation of the position of the outer edges from the mean value of the position of the outer edges is less than 2.0 mm, preferably less than 0.5 mm, particularly preferably less than 0.2 mm.

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