Method for molding a glass object, in particular a flat glass object molded into a three-dimensional shape, as well as a device for carrying out the method

Abstract

The invention relates to a method for molding a glass article (10), in particular a three-dimensionally molded flat glass article, wherein the following steps are carried out: placing a glass sheet (10), for example a flat glass panel of homogeneous thickness or a flat glass panel of non-homogeneous thickness or a pre-molded flat glass panel or liquid glass distributed over an area, between a molding plunger (20) and a molten mass of liquid metal (30), in particular tin; controlling the temperature of at least a part to be molded of the glass sheet (10) to a glass forming temperature, at which the glass has a viscosity in the range of 10 Pas to 106.5 Pas, preferably in the range of 10 Pas to 104 Pas and particularly preferably in the range of 10 Pas to 103 Pas;molding the glass sheet (10) by means of the molding plunger (20) and moving one surface of the molten metal (30) towards the other, preferably by at least one linear motion, for example, by means of a linear motor or a servomotor, so that pressure is applied to the glass sheet (10) on one side by the molding plunger (20) and by the molten metal (30) on the other side, and the glass sheet is molded by applying pressure from both sides and / or by suction and forming the glass sheet (10) on the molding plunger (20); cooling the molded glass sheet (10) to a handling temperature lower than the forming temperature at which the glass has a viscosity of ≥ 107 Pa·s; and removing the cooled sheet (10) from the mold. The invention also relates to a device for carrying out the method and to the use of a molten metal for carrying out the method.

Description

[0001] The invention relates to a method for shaping a glass object, in particular a three-dimensionally shaped flat glass object, according to the preamble of claim 1, and to a device for producing such a glass object according to the preamble of claim 8.

[0002] Methods for shaping glass objects, particularly three-dimensionally shaped flat glass objects such as mobile phone or tablet covers or vehicle windshields, have been known for some time and are almost always based on pressing and / or grinding a flat glass blank into the desired shape. Pressing involves using a die tool with a die and counter-die, where the die and counter-die are complementary, i.e., concave and convex, respectively, in the shape of the three-dimensionally shaped flat glass object to be produced.

[0003] One problem with this manufacturing process is that both the die and the counter-die inevitably come into contact with the glass object being pressed during the pressing process, which is detrimental to the quality of the pressed glass surface. While the quality of the glass surface can be improved by using certain suitable glass contact materials on the contact surfaces of the pressing tools, post-processing of the glass surface is usually still necessary, especially when a high-quality pressed surface is required.

[0004] The forming and shaping of glass primarily involves the use of cast iron and steel alloys, or chromium coatings on steel alloys. However, these coatings can lead to glass adhesion when a certain temperature threshold is exceeded. Therefore, the molds are designed to maintain temperatures below 500°C, while the glass forming process takes place at viscosities of 10⁻⁶ Pa·s to 10⁻⁶ Pa·s, and thus at temperatures ranging from 800°C to 1500°C.

[0005] The resulting temperature gradient between the glass and the glass contact material also leads to a temperature gradient within the formed glass component. The forming process is therefore time-limited due to the different thermal expansion of the glass and the glass contact material in different temperature ranges. This time limitation in the forming process, according to the state of the art, is intended, among other things, to Avoid overheating of the mold, which cannot dissipate the heat introduced by the glass quickly enough and heats up above the critical bonding temperature; avoid situations where the glass cannot be separated from the tool because faster shrinkage of the glass at high temperatures causes the glass to shrink onto the mold component responsible for the inner contour of the workpiece, i.e., onto convex sections of the die; avoid situations where the glass cannot achieve sufficient homogenization of the temperature gradients within the component during the forming process, resulting in surface cracks and deformations due to stress, because the surface cannot be reheated by the infrared radiation stored inside the glass.

[0006] With current technology, this consequently leads to an extremely complex and difficult process control, which nevertheless entails disadvantages in terms of the glass quality obtained.

[0007] As mentioned above, another possibility for producing three-dimensionally shaped flat glass objects is to grind a glass blank until it has assumed the desired three-dimensional shape; however, this method is also disadvantageous and, in particular, time-consuming, and, moreover, lengthy and difficult to carry out if a high quality of the respective glass surface is required.

[0008] Another method for forming a glass gob is described in JP H 07 33 449 A, whereby, according to JP H 07 33 449 A, a glass gob is placed on a bath of molten tin, heated to a forming temperature, and then pressed into a three-dimensional shape by hydraulically lifting the tin bath on the one hand and lowering the mold on the other. After forming, the glass gob is cooled by blowing in a cooling gas and demolded. According to CN 105 366 919 A, fine ridges are formed on a glass surface in a similar manner. However, the company stamp used in both of these methods also implements the disadvantages described above of methods known from the prior art.

[0009] The invention is based on the objective of providing an alternative method for shaping, i.e. manufacturing, three-dimensionally shaped flat glass objects, which enables high-precision production of flat glass objects with simultaneously high quality of the glass surface and reduces any need for post-processing to a minimum, and furthermore to provide a device for carrying out such a method.

[0010] This task is accomplished by a method according to claim 1 and by a device according to claim 8.

[0011] In particular, this task is solved by a method for shaping a glass object, especially a three-dimensionally shaped flat glass object, wherein the following steps are carried out. a) Arranging a planar structure made of glass, for example a flat glass sheet with homogeneous thickness or a flat glass sheet with inhomogeneous thickness or a preformed flat glass sheet blank or liquid, planarly distributed glass, between a mold and a molten metal, i.e.a) a melt of liquid metal, in particular molten tin; b) tempering the sheet of glass to a forming temperature at which the glass has a viscosity in the range of 10 Pa to 10 6.5 Pa, preferably in the range of 10 Pa to 10 4 Pa ​​and particularly preferably in the range of 10 Pa to 10 3 Pa; c) forming the sheet of glass by moving the mold and a surface of the molten metal towards each other, so that the sheet of glass is pressurized on one side by the mold and on the other by the molten metal and is formed by the pressure exerted on both sides and / or by suction and conforming of the sheet of glass to the mold; d) cooling the formed sheet of glass to a handling temperature below the forming temperature at which the glass has a viscosity of ≥ 10 7 Pa; and e) demolding of the cooled flat structure, . wherein the demolded flat structure is surface-conditioned on both sides as part of a post-treatment by bringing the second surface-conditioning side, namely the side of the formed flat glass object that has not yet come into contact with a metal bath, into contact with the metal bath or a second metal bath while turning the flat structure over.

[0012] A key aspect of the invention is that the process according to the invention is carried out as a pressing process, but using only a solid, fixed die, while a molten metal die is used as the counter-die. According to the invention, liquid tin is preferably used as the liquid metal, since tin is extremely inert towards glass and enables the production of glass surfaces with very high surface quality. Furthermore, a tin bath containing liquid tin can be heated to high temperatures, which allow for the shaping of glass.

[0013] In the process according to the invention, a sheet of glass is placed in a forming chamber which is arranged between a volume or container for receiving a molten metal, such as a metal bath, and a mold die. Subsequently, the sheet of glass, i.e., the glass blank, is tempered to a forming temperature.

[0014] In this context, it should be noted that the volume or container for receiving the molten metal may already be filled with molten metal during the introduction of the glass sheet into the forming chamber.

[0015] However, according to an alternative embodiment of the invention, it is also possible that the molten metal is introduced into the volume or container provided for the molten metal only after the glass sheet has been introduced into the forming chamber.

[0016] According to a further embodiment, it is also possible that, although molten metal is already present in the volume or container for the glass melt during the introduction of the glass sheet, the level of the molten metal surface is subsequently leveled. In this process, it is possible to raise the level of the molten metal, for example by raising the metal bath and / or by adding more molten metal, or, if necessary, to lower it, for example by removing molten metal from the volume or container.

[0017] Within the scope of the invention, the forming temperature of the glass is understood to be a temperature at which the glass to be formed has a viscosity in the range of 10 Pa·s to 10⁶.5 < Pa·s, preferably in the range of 10 Pa·s to 10⁴ < Pa·s, and particularly preferably in the range of 10 Pa·s to 10⁳ < Pa·s. Advantageously, a glass blank made of flat glass with such a viscosity, which lies within the specified range, can be formed into a desired three-dimensional shape in order to produce a three-dimensionally shaped flat glass object according to the invention.

[0018] After the glass blank, i.e. the flat structure made of glass, has been brought to the forming temperature of the glass, the mold die and the molten metal are moved towards each other, so that by applying pressure to the glass blank a three-dimensional forming of the flat structure made of glass into the desired three-dimensionally shaped glass object takes place.

[0019] According to the invention, a prefabricated glass blank can be used as the starting glass body or as the starting surface structure, which is designed as a flat glass sheet with homogeneous thickness or, depending on the desired three-dimensional glass object to be formed, also of inhomogeneous thickness or already preformed flat glass sheet blank.

[0020] Furthermore, according to the invention it is also possible to use liquid glass as the starting glass, which is introduced between the mold die and the molten metal and is then shaped when the mold die and molten metal are moved towards each other.

[0021] According to one embodiment of the invention, the actual shaping of the glass blank into the desired three-dimensionally shaped flat glass object is carried out by a three-dimensional shape contour of the mold die being pressed into the softened flat glass blank during a coming together of the mold die and the molten metal, whereby the flat glass blank is in turn pressed into the molten metal serving as a counter-die with its side facing away from the mold die.

[0022] In this case, the molten metal serves as a counter-stamp to the mold die according to the invention, wherein the molten metal conforms to the softened flat glass blank and, in turn, presses the softened flat glass blank homogeneously and uniformly against the three-dimensional shape contour of the mold die through the interplay of its surface tension and its hydraulic pressure.

[0023] The movement of the mold die and the molten metal towards each other can be done in different ways.

[0024] According to one embodiment of the invention, the molten metal is preferably located below the mold die, wherein, when the molten metal and the mold die are moved towards each other, both the level of the molten metal can be raised and, if necessary simultaneously, the mold die can be lowered.

[0025] To prevent the mold, or the softened flat glass object guided by the mold, from being drawn too far into the molten metal during the process of forming the desired three-dimensional flat glass object, the pressure building up during the forming process is precisely monitored, and the movement of the molten metal bath and the mold is precisely controlled. Furthermore, the mold is moved, as desired, within a guide that precisely surrounds and guides the mold. This guide seals a volume located laterally around the mold, ensuring that the level of the molten metal can rise to a maximum of the lower surface of the guide during immersion of the flat glass object and mold.Further immersion of the mold die, or rather of the softened flat glass object guided by the mold die, into the molten metal would lead to an immediate and easily measurable pressure increase at the mold die and guide on the one hand, and in the metal bath on the other.

[0026] Similarly, a pressure increase also occurs when the softened flat glass object is pressed homogeneously against the mold contour of the die across its entire surface. Since no further deformation of the flat glass object is possible in this state, any further movement of the molten metal and the mold towards each other results in a clearly measurable pressure increase, signaling the end of the forming process.

[0027] Since the pressure that builds up in the molten metal during the pressing process is homogeneous throughout the entire molten metal, the inventive method results in a homogeneous pressing of the soft flat glass blank against the three-dimensional shape contour of the mold die over the entire surface of the flat glass blank, so that any stresses in the finished flat glass object, as occur in conventional glass presses, can be avoided in the inventive method.

[0028] According to an alternative embodiment of the invention, the mold die can have openings by means of which, depending on the desired outcome and operating condition, either an overpressure or a vacuum can be applied to the glass surface located adjacent to the mold die during a forming process.

[0029] By means of such a mold die, which has openings for applying a vacuum to the glass body, the glass body can also be formed according to the invention by bringing the metal bath on the one hand and the mold die on the other hand closer together, wherein a vacuum applied via the mold die draws in the glass body as soon as a distance of the glass body relative to the mold die, which depends on the applied vacuum, is undershot.

[0030] Once the glass body and the mold die have come sufficiently close to each other, the glass body, tempered to the forming temperature, can be formed according to the invention by the mold die sucking the tempered glass body into it, whereby the tempered glass body conforms exactly to the contour of the mold die defined by the mold die.

[0031] In such a forming process according to the invention, it is possible for the tempered glass sheet to be lifted from the surface of the metal bath by the suction exerted by the mold die. An advantage of this process, according to the invention, is that the glass sheet, which initially rests on the liquid metal surface, is removed from the hot, essentially forming-temperature liquid metal surface by this lifting action and, upon contact with the cooler mold die, cools down immediately or at least very quickly after the glass has conformed to the mold die due to the negative pressure exerted by the die, and solidifies in the predetermined shape desired by the mold die.The cooling of the glass to a viscosity at which the glass sheet is sufficiently dimensionally stable to be handled for further processing occurs through contact between the glass sheet, initially at forming temperature, and the cooler mold die. During this contact, the mold die dissipates the heat from the glass sheet. Since, according to the invention, the glass mold die is tempered to a temperature that allows the glass sheet to be formed but is sufficiently low to prevent the glass sheet from sticking to the mold die, the formed glass sheet can be detached and / or removed from the mold die, particularly immediately after forming.

[0032] According to a further alternative embodiment of the invention, the level of the liquid metal bath can be further raised during a suction process of the glass body, which has been tempered to forming temperature, by the die. This can be achieved either by raising the metal bath itself or by simply increasing the surface level of the liquid metal in the bath by adding more liquid metal. Such an increase in the liquid metal level can be continued until the glass body is in contact with the die and simultaneously pressed against it by the liquid metal.Such an embodiment has the advantage that the glass body, initially tempered to forming temperature, can be further heated or cooled in a targeted manner by controlling the temperature of the metal bath, during which the metal bath remains completely liquid according to the invention.

[0033] Further heating or sustained tempering of the glass sheet to at least the forming temperature, or the viscosity of the glass sheet depending on the type of glass, is particularly advantageous according to the invention, for example, when the glass sheet is to be formed into molds with undercuts. In such a case, a multi-part mold die is used according to the invention, which makes it possible to demold the finished, formed glass, cooled to handling temperature, without damage.

[0034] In any case, the glass body in contact with the mold can also be cooled in a targeted and temperature-controlled manner, particularly due to its contact with the liquid metal, by cooling the liquid metal itself and thereby selectively extracting heat from the glass body.

[0035] To demold the formed and cooled glass body to handling temperature, an overpressure can also be applied through the openings in the mold die, which causes and / or facilitates the detachment of the cooled glass body from the mold die.

[0036] According to the invention, the glass blank can be introduced into a forming chamber either by means of a holding device and / or a support device for the sheet structure made of glass, which is designed, for example, in the form of a gripper or a lance that holds the glass blank and moves it into the forming chamber between the molten metal and the mold die.

[0037] Alternatively, the glass blank can also be inserted into the forming chamber using the mold itself and / or an external axial guide for the mold. In the latter case, the mold is designed to be movable not only axially but also translationally at an angle to its axial direction. As mentioned above, the mold and / or its axial guide, which in this case can also move translationally along with the mold, has openings through which a vacuum can be applied to the glass blank, thus holding it against the mold and / or its guide by means of a vacuum.

[0038] Once the glass blank has been placed in the forming chamber, it can either be positioned loosely floating on the molten metal or, if desired, held and fixed with its edges on the edge of the metal bath (i.e., on the upper edge of the container holding the liquid metal) or on the guide of the mold die. This allows the precise definition and, if necessary, correction of the glass blank's position, particularly the final position intended for forming, by moving the holding and / or support device or the guide of the mold die, which is axially movable independently of the die. The glass blank is then formed as the molten metal and the mold die approach the flat glass blank from opposite sides.

[0039] According to one embodiment of the invention, it is possible to position the glass blank or the molten glass on the molten metal, which is contained in a vessel suitable for holding the molten metal, so that the glass practically floats on the molten metal. As the mold and the molten metal are moved towards each other, the mold can then be lowered onto the glass, which has been tempered to forming temperature. The mold presses the glass, which is soft at this forming temperature, into the molten metal, thereby shaping it. During this forming process, the soft glass of the glass blank conforms to the glass contact surface of the mold under the pressure of the mold and assumes the shape of this surface. Meanwhile, the molten metal acts as a counter-mold to the mold, exerting a homogeneous counter-pressure against the glass blank from the other side.

[0040] According to a further embodiment of the invention, the approach of the mold die and the molten metal can also be achieved by increasing the liquid level of the liquid metal in the molten metal, so that the mold die does not approach the molten metal from above, but rather the molten metal with the floating glass blank approaches the mold die and presses the glass blank against the mold die during this approach.

[0041] According to the invention, the liquid level of the molten metal can be increased by filling the receiving chamber for the molten metal with more molten metal, thus raising the liquid level; alternatively, the bottom of the receiving chamber for the molten metal and / or the entire container in which the metal bath is located can be made movable, so that the level of the molten metal in the metal bath can be raised and lowered to allow the molten metal and the die to approach each other for the pressing process and to allow the molten metal and the die to move away from each other for a subsequent demolding process.

[0042] The aforementioned embodiments of the invention can also be combined as desired, for example by increasing the liquid level of the molten metal while simultaneously moving the mold die closer to the surface of the molten metal. Since two movements are performed simultaneously in this case, such a combination is suitable for the production of three-dimensionally shaped flat glass objects, where, for example, a high production speed is desired.

[0043] According to a particularly preferred embodiment of the invention, the glass body to be formed is introduced into the forming chamber by means of a holding and / or support device in such a way that the glass body to be formed rests on the edge of the container containing the liquid metal in its outer edge regions.

[0044] During the forming process, the outer edge region of the glass body to be formed, located on the rim of the container, is fixed to the rim of the container for the liquid metal, i.e., to the rim of the metal bath, by applying pressure to the edge region of the glass body to be formed on the side opposite the rim of the container, so that the edge region of the glass body to be formed is clamped to the rim of the container. According to the invention, such pressure application to the edge regions of the glass body to be formed can be particularly advantageously achieved circumferentially by the guide of the mold, which is movable independently of the mold die.

[0045] In this way, the glass body to be formed is fixed on the edge of the metal bath during the forming process and simultaneously seals the metal bath against an overflow of metal when the level of the liquid metal in the metal bath is raised during the forming process and the molding die is lowered, especially simultaneously.

[0046] According to this embodiment of the invention, one or more openings can be provided both on the guide of the mold die and in an upper section of the metal bath, for example at its edge. These openings can serve for both venting and aeration of the space that, after the glass body has been fixed to the rim of the container, lies between the glass body and the surface of the liquid metal. In this way, it is possible to both lower and raise the level of the liquid metal in the metal bath without undesirable gas bubbles or a vacuum forming between the glass body and the surface of the liquid metal.

[0047] In this context, it should also be noted that, according to the invention, it is not necessary to temper the entire glass sheet to a forming temperature, but advantageously only the area that is actually to be formed three-dimensionally. This means that the respective edge areas of the glass sheet can be kept at a handling temperature at all times, at which the glass can be grasped and handled. In this way, for example, it is possible to grasp and hold these edge areas of the glass sheet even during the actual forming process using the holding and / or carrying device employed according to the invention for transporting the glass sheet into and out of the forming chamber.

[0048] Furthermore, the tempered glass blank can also be formed by placing the glass blank on a mold located below it during operation, tempering it, and then forming it by pouring liquid metal onto the glass blank. The glass blank, now at forming temperature, is pressed against the mold below by the weight of the liquid metal and, optionally, by an additional pressure force applied to the liquid metal, thus forming it. In this embodiment of the invention, the mold can also be moved, optionally simultaneously, preferably axially.

[0049] During the pressing process, the contact between the mold die and the glass surface formed by it causes the glass surface to cool and thus the flat body to solidify, so that the flat body solidifies in the shape produced by the pressing process.

[0050] After the manufactured three-dimensionally shaped flat glass object has solidified, it is cooled until it reaches a handling temperature. According to the invention, the handling temperature is defined by the fact that the shaped glass has a viscosity of ≥ 10⁷ < Pa·s. At such a viscosity of ≥ 10⁷ < Pa·s, the glass has solidified to such an extent that no further deformation occurs during handling of the flat glass object, allowing it to be handled and removed from the pressing device.

[0051] It should be noted here that, according to the invention, aluminum silicate glass is preferably used to produce the desired three-dimensionally shaped flat glass object, although other types of glass can also be used. Since these different types of glass have, in some cases, very different softening and processing temperatures, the present invention does not focus on a specific temperature during the processing process, but rather on a viscosity required for each operation. At this viscosity, the glass used has a state of matter necessary for the respective processing step, such as liquid, softened, or solid, so that the glass can be transported, shaped, or post-treated, for example, fire-polished or otherwise surface-conditioned. Fig. 9For different types of glass, exemplary correlations are given between the respective viscosity of different glasses at their respective associated temperatures.

[0052] After the three-dimensionally shaped flat glass object has cooled to the handling temperature as desired, the cooled flat object, i.e., the manufactured three-dimensionally shaped flat glass object, is demolded.

[0053] According to one embodiment of the invention, the sheet structure made of glass, or at least a part of the sheet structure made of glass to be formed, is preheated to a temperature at which the glass has a viscosity ≥ 10⁶.5 < Pas, preferably ≥ 10⁷ < Pas, before step a), i.e. before being placed in a forming chamber between molten metal and a mold die.

[0054] At such a viscosity, the glass blank is still manageable, grippable and durable, but already preheated to near its forming temperature, so that the tempering of the sheet structure, or rather its part to be formed, can take place very quickly within the press tool to the forming temperature.

[0055] In this context, it should be mentioned that the glass blank may already exhibit softening effects when it is inserted into the pressing tool, since any impurities or microstructures on the blank's surface are advantageously smoothed during the pressing process according to the invention. Therefore, a significant advantage of the inventive method is that even microstructured blanks or blanks with minor surface damage can be used without difficulty. This is particularly true if any damaged surface is located on the metal bath side of the pressing tool.

[0056] If a prefabricated glass blank is not to be used for carrying out the process according to the invention, glass in liquid form can be poured onto the molten metal or the mold die and then tempered to its forming temperature by cooling. In this way, the process according to the invention is particularly versatile and not limited to processing prefabricated glass blanks.

[0057] According to the invention, tempering of the glass sheet is carried out by means of a heater, for example an infrared (IR) heater and / or, optionally additionally, by means of at least one induction heater and / or at least one microwave heater, in the case of heating the blank or sheet. In addition, heating or cooling of the blank can also be carried out by means of heat conduction by heating or cooling the molten metal.

[0058] Furthermore, according to the invention, it is also possible for the mold die to have fluid channels through which separate temperature control of the, optionally multi-part, mold die is possible, so that the mold die can be both heated and cooled by means of a fluid in order to maintain an optimal temperature for the respective process step. A gaseous fluid can preferably be used as the cooling fluid or heating fluid.

[0059] According to one embodiment of the invention, step c), i.e., moving the die and the metal bath towards each other, is carried out by means of at least one linear motor, in particular a servo motor. The use of such a motor generating a linear motion enables very precise control of the press tool and, moreover, an immediate and direct reaction in the event of a pressure increase.

[0060] As mentioned above, the metal melt used according to the invention is a tin melt, since this material is inert to glass even at high temperatures and enables the production of a quality-optimized glass surface, while also making it possible to "heal" any defective areas on the surface of the glass blank.

[0061] According to the invention, this "healing" property of molten tin is also used for post-treatment of the finished, three-dimensionally shaped flat glass object in the form of surface conditioning. For this purpose, the shaped glass object, after cooling to handling temperature (for example, using a gripper and / or a vacuum holding device), can be turned over and the side that did not come into contact with the molten metal during the forming process brought into contact with the liquid tin. Through contact of the glass with the liquid tin, any defects in the glass surface and / or any stresses on the glass surface are "corrected" or repaired without the need for manual or machine-based post-processing of the glass surface, such as grinding or polishing.

[0062] According to a preferred embodiment, the molten metal with which the glass sheet is brought into contact during surface conditioning is subjected to a high-frequency vibration, which can be generated, for example, by ultrasound. This promotes uniform contact between the glass sheet and the liquid metal, namely liquid tin.

[0063] Furthermore, the process according to the invention is carried out under exclusion of oxygen, i.e., preferably in an atmosphere inert to the glass, the liquid metal, in particular the molten tin, and the material of the mold die, for example in a noble gas atmosphere, in particular an argon atmosphere, and / or a nitrogen atmosphere and / or in a carbon dioxide atmosphere. In this way, any oxidation of these components, and in particular of the tin bath, can be avoided.

[0064] According to a preferred embodiment of the invention, the tin bath is overlaid with the respective inert gas used, with heavy noble gases and carbon dioxide being particularly suitable due to their higher specific gravity compared to air. According to this embodiment, the container in which the liquid metal, in particular tin, is located is in fluid communication with a reservoir for the respective glass, with which the inert atmosphere above the metal bath is generated, in its area adjacent to the glass surface and / or to the guide of the mold die.

[0065] According to the invention, for the purpose of supplying inert gas, for example, one or more openings can also be used with which ventilation of the space between the metal bath and the glass body to be formed is possible.

[0066] In order to carry out the actual forming process according to the invention in an inert atmosphere, the glass blank, which is held either with a gripper, a vacuum holding device or on a support device, is moved through an airlock into a room with a controlled atmosphere, wherein this room is filled with the desired inert and / or protective gas or mixtures thereof and is preferably under a slight overpressure to prevent ambient air from entering this room with a controlled atmosphere.

[0067] Within the airlock, an evacuation takes place first, followed by flooding of the space with inert and / or protective gas. Since this process takes some time, according to the invention, preheating of the glass blank can be carried out simultaneously in order to shorten the time required for the process according to the invention.

[0068] At this point, it is also conceivable that instead of evacuating the lock chamber, the air contained therein is displaced by the inert and / or protective gas, whereby the inert and / or protective gas that flows out of the forming chamber due to the overpressure prevailing there can be used for this purpose.

[0069] According to a further alternative embodiment of the invention, it is also possible to position the entire press apparatus according to the invention under an inert and / or protective gas bell, which is open at the bottom and allows a controlled atmosphere to be maintained within the bell due to a slight overpressure. In this case, the glass blank and the finished glass product are fed into and out of the bell from below. Since the bell is open at the bottom, an inert gas with a lower specific gravity than air is preferably suitable for this embodiment of the invention.

[0070] In the case of the glass blank being placed on a support device, the heating of the glass blank, preferably by means of infrared radiation, takes place essentially from above, whereas heating of the glass blank from both above and below is possible if the glass blank is held and / or rests with its edges on the edge of the metal bath.

[0071] It should be mentioned that the use of a gripper to hold the glass blank is advantageous according to the invention, since the blank can be moved and turned together with the gripper, which is extremely advantageous, for example, for carrying out surface conditioning.

[0072] According to the invention, the formed flat glass object can be removed from the pressing tool by means of a gripper, but also by means of a vacuum holding device, which can be integrated into the mold die and / or into the preferably annular guide of the mold die that at least partially surrounds the mold die. In this case, the mold die is designed to be movable not only axially but also laterally, according to the invention. Such an embodiment of the invention is particularly advantageous because the mold die is in contact with the formed flat object during the pressing process anyway and thus also serves as protection for the pressed glass surface.

[0073] To remove the flat glass object from the pressing tool, the mold die can have micro-openings through which a vacuum can be applied, thereby holding the formed flat glass object to the mold die. In this way, according to the invention, it can be ensured that the finished flat glass object adheres securely to the mold die during the removal process and can be easily separated from the mold die after removal by releasing the vacuum.

[0074] As mentioned previously, the mold guide surrounding the mold die, which, for example, can be a ring in the case of a round mold die, also has openings through which a vacuum can be created. This guide, which can also be functionally referred to as a cover ring, can rest against the edges of the glass blank and thus hold the glass blank in place when a vacuum is created through the openings in the guide, so that the blank, or rather its edge, is drawn through the guide. In this way, the glass blank can be transported as well as lifted and picked up from the molten metal.

[0075] Furthermore, the glass blank can also be held by a gripper or a carrying device throughout the entire manufacturing process. To carry out the method according to the invention, the glass blank is first placed on the carrying device or gripped by the gripper. Using this holding and / or carrying device, which can be connected, for example, to a transport carriage or other transport device, the glass blank is then transported from the ambient atmosphere into the airlock and heated there to a temperature that still allows gripping and transport of the glass blank. Simultaneously, an atmosphere exchange takes place within the airlock, during which the ambient atmosphere is replaced by an inert and / or protective gas atmosphere.After the atmospheric exchange is complete, the glass blank is transferred to the forming chamber and positioned between the volume or container for the molten metal and the mold. The glass blank is then heated to the forming temperature. During this process, the glass blank continues to be held or carried. The forming of the glass blank then occurs through the approach of the molten metal and the mold, whereby the glass blank comes into close contact with both the molten metal and the mold. The molten metal acts as a counter-die to the mold, pressing the glass blank precisely against the mold's contour.

[0076] When the glass blank is held and fixed on the edge of the metal bath in a manner that preferably seals the metal bath, additional liquid metal, i.e. liquid tin, can be injected into the volume provided for the metal bath during the forming process, so that the level of the metal bath, in particular the tin bath, is raised to such an extent that the glass blank comes into contact with the liquid tin, while the glass blank is pressed into its desired shape from the opposite side by the molding die.

[0077] During the pressing process, or rather after its completion, the formed flat glass object simultaneously cools down, allowing the three-dimensionally shaped object to solidify in the desired form. According to the invention, this cooling is primarily initiated by the mold itself, as it reaches a slightly lower temperature than the forming temperature of the glass towards the end of the pressing process. Because the mold is in direct and immediate contact with the entire formed surface of the flat glass object, a uniform cooling of the object below the forming temperature to a handling temperature can occur. At this temperature, the viscosity of the flat glass object is so high that further forming is no longer possible.

[0078] According to one embodiment of the invention, the mold die can be equipped with a heating and a cooling device for this purpose, so that the mold die can be heated to the temperature required for each process step during the execution of the process according to the invention. Such a heating or cooling device can, for example, be designed in the form of channels or lines formed within the mold die through which a heating or cooling fluid can flow. Alternatively, the mold die can also be heated inductively, for example. The same applies to the guide of the mold die, since, according to the invention, this guide also has a heating and / or cooling device to prevent any stresses between the guide and the mold die.

[0079] Furthermore, it should be noted that the metal bath can also be heated or cooled, depending on the process step, so that the glass blank has a temperature and viscosity optimized for shaping. This means that, in addition to using induction and / or infrared heating, the glass blank can also be heated by contact with the metal bath, or cooled by cooling the metal bath.

[0080] Furthermore, it should be noted that after a completed forming process, the level of the metal bath can be lowered again. For this purpose, the metal bath is in fluid communication with a reservoir and / or expansion tank for liquid metal, from which the liquid metal required to refill the metal bath can also be drawn.

[0081] Once the shaped flat glass object has solidified sufficiently, or rather, has reached a viscosity high enough that further undesirable deformation of the flat glass object no longer occurs, the flat glass object is picked up and turned over. The side that did not come into contact with the metal bath during the forming process is then brought into contact with the metal bath as well. This ensures that the surface, which until then had only been in contact with the mold, also comes into contact with the liquid tin. Any impurities are thus "cured" by this contact with the liquid tin, resulting in a perfectly smooth and flawless surface of the flat glass object. In this way, the shaped flat glass object produced according to the invention acquires an optimized, perfect surface on both sides.

[0082] After surface conditioning has been carried out, the now fully formed and surface-treated flat glass object is transported out of the forming device and back into an ambient atmosphere using the holding and / or carrying device and its transport device through an airlock, in which an atmosphere exchange takes place.

[0083] According to a further embodiment of the invention, the demolding step can be carried out with the aid of pressurizing the formed flat object. This is particularly useful if the formed flat glass object comes into close contact with the mold or its guide, for example the ring, during cooling, for example due to shrinkage. In this case, compressed air can be used to gently push the formed flat glass object away from the mold and / or its guide.

[0084] As mentioned above, according to the invention, the demolded flat structure, or the finished shaped flat glass object, is surface-treated at least on one side, namely in particular by bringing the desired side to be treated into contact with the metal bath or a further metal bath, preferably by turning the flat structure over, wherein the further metal bath preferably has a lower temperature than the metal bath used during the forming process, i.e. in step c).

[0085] It should be noted here that the metal bath used for the post-treatment of one or more surfaces of the three-dimensionally shaped flat glass object can be the same metal bath that was used for shaping the glass blank. Alternatively, a second metal bath can be provided for carrying out the surface conditioning or treatment. According to the invention, this second metal bath is also a tin bath, wherein this second metal bath has a slightly lower temperature than the metal bath used for shaping.This is particularly advantageous because smoothing and healing the surface of the flat glass object requires only contact with liquid tin, whereby the tin does not need to be heated to such a high temperature that the glass melts; rather, for surface conditioning, it is sufficient if only a few micrometers of the surface of the flat glass object to be treated are softened to such an extent that the surface tension of the glass allows the glass to be smoothed.

[0086] Furthermore, the inventive method can be carried out both as a continuous process, i.e., a through-process, and as a so-called batch process, wherein the respective glass object is held by means of a holding device or alternatively handled by means of at least one carrying device and optionally at least one turning device.

[0087] According to a further embodiment of the invention, the glass blank can also be placed outside the forming device, i.e., in ambient atmosphere, on a support device, such as a lance, which is then used to transport it into the lock chamber by means of a transport device, such as a carriage or other sliding mechanism. In this lock chamber, an atmospheric exchange to an inert atmosphere takes place. In this lock chamber, the glass blank can be preheated to a temperature at which its viscosity is still sufficiently high for handling and transport. Subsequently, i.e., after the atmospheric exchange, the glass blank, resting on the support device, leaves the lock chamber and is moved by means of the lance or support device between the tin bath, or the volume or container for holding the tin bath, and the plunger, i.e., the molding die, and its guide.For example, a ring. There, the guide for the mold die, positioned above the glass blank, takes over the further transport of the glass blank by drawing the edges of the glass blank in via vacuum nozzles, lifting them from the support device, such as a lance, and then placing them on the tin bath or its edge. Subsequently, the mold die, initially retracted behind the guide, is moved forward towards the glass blank by the guide, while on the other side of the glass blank, the level and / or pressure of the tin bath is raised or increased to such an extent that the tin bath acts as a counter-die to the mold die, and the glass blank positioned between the mold die and the tin bath is formed.

[0088] After the glass blank has been formed, the resulting shaped flat glass object is again captured by the ring, i.e., sucked in by negative pressure and lifted off from the metal bath or the edge of the metal bath.

[0089] The formed flat glass object is then either placed on a second support device, such as a second lance, and transported out of the forming device through a sluice gate.

[0090] According to the invention, the formed flat glass object is also subjected to surface conditioning before being discharged from the forming device. In this case, the flat glass object, lifted from the metal bath by the guide of the molding die, is grasped on its side opposite the guide by a vacuum gripper and turned so that the side of the formed flat glass object that has not yet come into contact with a metal bath is brought into contact with the tin bath, so that any defects can be repaired by the contact of the glass with the tin bath. In this case, either the tin bath used for forming or a tin bath downstream of it, which may optionally have a lower temperature than the tin bath used for forming, can be used.

[0091] It should also be mentioned that the vacuum gripper, i.e. the vacuum holding device used, can either place the formed flat glass object back onto a support device after surface conditioning has been carried out or move it directly out of the forming device through the sluice.

[0092] Furthermore, it should be mentioned here that the actual forming process and, if necessary, the surface conditioning of the flat glass object can also be carried out under negative pressure, or in a largely vacuumed room.

[0093] Furthermore, the object of the invention is also achieved in particular by a device for producing a glass object, in particular a three-dimensionally shaped flat glass object, in particular by means of a method according to the preceding descriptions, wherein the device has a receiving chamber suitable for receiving molten metal, in particular tin, and a molding die opposite the receiving chamber, wherein a forming chamber is arranged in the direction of the receiving chamber and adjacent to the molding die, into which a planar structure made of glass, in particular a glass blank or liquid glass, can be placed, and wherein the molding die and the molten metal can be moved towards each other and the molding die optionally has openings for applying negative or positive pressure.so that the glass sheet can be subjected to pressure on one side by the mold and on the other side by the molten metal, and can be formed by the pressure being applied on both sides and / or by suction and conforming to the mold, and the mold is surrounded, and in particular guided, by a frame, in particular a ring, such as a cover ring, wherein the frame, in particular a ring, surrounding the mold has openings, wherein a vacuum or a positive pressure can be generated via the openings at a contact surface between the glass sheet and the mold.

[0094] According to one embodiment of the invention, the receiving chamber for liquid metal, in particular tin, is in fluid communication with a compensating reservoir suitable for receiving and releasing molten tin and which may optionally be pressurized.

[0095] In this way, according to the invention, it is possible, firstly, to increase the back pressure of the tin during a forming process, and secondly, to use tin from the expansion tank to raise the liquid metal level. Furthermore, the expansion tank can be used to regulate the level of the metal when the die presses the glass sheet, heated to the forming temperature, into the metal bath for forming.

[0096] According to the invention, the mold die is made of a high-temperature resistant material, such as a high-melting-point metal, for example steel, gold, copper, ruthenium, osmium, zirconium, hafnium, niobium, tantalum, chromium, molybdenum or tungsten, or a high-melting-point alloy, or a ceramic that is inert to glass at temperatures in the range of 700°C to 1600°C, such as a carbide or nitride, or is coated with such a high-temperature resistant material.

[0097] As mentioned above, the mold die can have at least one cavity, in particular at least one channel and / or conduit, through which a heating or cooling fluid, in particular a gaseous fluid, can flow.

[0098] This allows for separate temperature control of the mold die, so that its temperature can be adjusted to each process step. For example, the mold die can be cooled in a controlled manner to accelerate the cooling of the finished flat glass object, or kept at an elevated temperature during the pressing process, if desired.

[0099] Furthermore, the mold die and / or its guide has openings through which a vacuum or overpressure can be generated at a contact surface between the glass surface and the mold die.

[0100] In this way, it is possible to use the mold die and / or its guide itself as a transport tool for both the glass blank and the finished flat glass object, by holding and transporting the glass blank or flat glass object against the mold die using a vacuum. Positive pressure can be used if the glass blank or flat glass object does not release from the mold die on its own. If positive pressure is required to release the glass blank from the press tool, an inert gas such as nitrogen or argon can be used to generate the pressure. Compressed air can also be used. For this purpose, the gas supply to the mold die can be equipped with a diverter valve, allowing the desired gas or air to be used to release the object from the mold die, as needed.

[0101] According to a further advantageous embodiment of the invention, the device can have at least one transport carriage for introducing a flat glass object into the forming chamber through an airlock of the device, which serves to exchange the external atmosphere for an inert gas and / or protective gas atmosphere or to generate a negative pressure or vacuum within the actual forming and / or a post-treatment chamber, and / or for removing a formed flat glass object from the forming chamber. The transport carriage is movable between a position in the press tool in a pressing position and a position outside the press tool, so that both the glass blank and the finished formed flat glass object can be transported with the aid of the transport carriage.For example, either the mold die and / or its guide, or alternatively a holding device or other support device, such as a lance, can be attached to the transport carriage to convey both the glass blank into the press tool and subsequently the finished flat glass object out of the press tool. Furthermore, the transport carriage can also have several mold dies, holding devices, and / or support devices, each of which alternately or sequentially forms and conveys the glass blank and the finished flat glass object. In this way, a circular operation, preferably continuous, is possible according to the invention.

[0102] As mentioned above, the device according to the invention can be operated either in batch mode or in continuous operation, as desired. While the device according to the invention has only one gate in the case of batch operation, the device according to the invention can also have two or more gates for continuous operation, preferably arranged opposite each other, wherein a first gate serves as the inlet gate and a second, in particular opposite, gate serves as the outlet gate.

[0103] Furthermore, the device according to the invention has at least one heating element, for example an infrared (IR) heating element and / or, optionally additionally, at least one induction heating element and / or at least one microwave heating element, in order to heat in particular the glass blank and, if desired, also components of the pressing tool, in particular the metal bath.

[0104] According to a further advantageous embodiment of the invention, the mold die can be interchangeable, preferably by means of at least one coupling device. Additional couplings can be provided for components connected to the mold die, such as a fluid supply or a vacuum system.

[0105] A further important aspect of the invention is that the mold die can be designed as a single piece or as a multi-piece mold. A multi-piece mold die makes it possible, for example, to produce a flat glass object with undercuts, whereby the mold die, or rather the part of the mold die covering the respective undercut, can be retracted sufficiently to allow demolding of the formed flat glass object. According to the invention, the individual parts of a multi-piece mold die are movable independently of one another, and the individual parts of such a multi-piece mold die can be tightly joined together during or before a pressing or forming process, so that the multi-piece mold die has a smooth and homogeneous surface for forming the flat glass object during the forming process.

[0106] Thus, a molten metal, in particular a molten tin, is used, which serves as a counter-stamp to a fixed mold die and for the production of a three-dimensionally shaped flat glass object.

[0107] In summary, the inventive method and its advantages, i.e., in particular the use of liquid tin as a liquid glass contact material, can be stated as follows.

[0108] The use of liquid tin makes it possible to carry out the forming process not only during the cooling phase, but also one step earlier, i.e., during the conditioning of the glass to an optimal forming temperature and temperature homogeneity. This allows the glass to be fed into the forming process under optimal conditions.

[0109] Furthermore, the method according to the invention enables an expansion of the temperature parameters in the process, since the temperature of the tin not only allows a minimization of the temperature delta between the mold and the glass, but also a reversal of the temperature delta.

[0110] Thus, the tin bath can have a higher temperature when loaded with the glass blank than the glass itself when loaded, whereby the tin bath can transfer its temperature to the glass in this case.

[0111] Furthermore, due to the high thermal conductivity of tin, the tin bath enables very rapid temperature control during the heating process, as well as preconditioning of the glass blank by heating it to the forming temperature and maintaining the temperature during the forming process, and also control of the temperature parameters during forming, thereby advantageously increasing the forming time window.

[0112] This results in improved process control through active monitoring of time, forming pressure, holding pressure, and temperature in each process stage. This, in turn, enables glass homogenization over time, i.e., heating, reheating, and control of temperature gradients within the glass during forming and cooling.

[0113] This results in greater flexibility in temperature control through active temperature control and not, as in the prior art, through passive thermal conductivity or indirect air / water cooling of the mold tool.

[0114] The tin pressure can be regulated by means of at least one servo valve.

[0115] Process control can be minimized in the actual forming / deformation process by, for example, incorporating upstream heating of the glass blank and, if necessary, downstream processes such as dedicated cooling.

[0116] Furthermore, the use of a tin bath in the shaping process according to the invention makes it possible to improve the surface quality of the shaped three-dimensional flat glass object through contact with tin.

[0117] Thus, the formation of a thin tin oxide layer on the shaped glass surface, as an inherent component of the glass, leads to an optimized surface structure of the shaped three-dimensional flat glass object.

[0118] Furthermore, it is possible, in an intermediate process step, to bring the side of the glass component that was not in contact with the tin bath due to the three-dimensionality of the glass object into contact with warm liquid tin in a temperature range in which no geometric deformation takes place, so that a "healing" of surface defects of the glass is effected.

[0119] Further embodiments of the invention are set out in the dependent claims.

[0120] The invention is described below using an exemplary embodiment, which is explained in more detail with reference to the figures. These show: Fig. 1 a schematic representation of the device according to the invention for producing a three-dimensionally shaped flat glass object according to a first embodiment in the open position; Fig. 2 a schematic representation of the device according to the embodiment shown in Fig. 1embodiment shown with flat glass blank placed on top; Fig. 3 a schematic representation of the device according to the invention as shown in Fig. 1 The embodiment shown is in preparation for the forming process; Fig. 4 is a schematic representation of the device according to the invention as shown in Fig. 4. Fig. 1 The embodiment shown is in a further advanced stage of preparation for the forming process; Fig. 5 is a schematic representation of the device according to the invention as shown in Fig. 1 The embodiment shown during the forming process; Fig. 6 a schematic enlarged detail view of a Fig. 2 marked section Z; Fig. 7 a schematic enlarged detail view of a in Fig. 3 marked section Y; Fig. 8 a schematic enlarged detail view of a in Fig. 4marked section X; and Fig. 9 a diagram which shows, by way of example, a correlation between the respective viscosity of different glasses with their respective associated temperature.

[0121] In the following description, the same reference symbols are used for identical and equivalent parts.

[0122] Fig. 1 Figure 1 shows a schematic representation of the device 1 according to the invention for producing a three-dimensionally shaped flat glass object 10 according to a first embodiment. Fig. 1 The device 1 according to the invention is shown in an open starting position.

[0123] The device 1 according to the invention essentially comprises three subunits, namely a stamping unit 1a, a transport unit 1b for the sheet structure made of glass 10 and a counter-stamping unit 1c, which is designed as a metal bath unit.

[0124] The punch unit 1a consists of the die 20, a die holder 80 to which the die 20 is attached by means of a fastening device, preferably a quick-release clamping system 90. Furthermore, the punch unit 1a comprises a cover ring unit, which in turn includes a mounting ring 100, a hanging bolt 110 attached to the mounting ring 100 and oriented perpendicular downwards, i.e., towards the counter-punch unit 1c, in which a bolt 110' is guided axially, as well as a receptacle 120 and a cover ring 60. The receptacle 120 serves to fasten the bolt 110', which is slidably arranged in the hanging bolt 110, so that the interaction of the mounting ring 100, hanging bolt 110, bolt 110', receptacle 120, and cover ring 60 enables the guidance of the punch unit 1a and, in particular, the die 20.

[0125] The transport unit 1b essentially consists of a holding device 70, with which it is possible to hold the flat structure made of glass 10, in particular to support and transport it.

[0126] The counter-stamp unit, or metal bath unit 1c, comprises according to the invention as described in Fig. 1 In the illustrated embodiment of the invention, two heaters 40 are shown, each comprising at least one heating element 41 and a coil 42 for inductively heating the metal bath. Furthermore, the counter-stamp unit 1c comprises a trough-shaped container 50 for receiving liquid metal, in particular tin, 30, as well as an inlet and outlet 125 for the liquid metal, and also an inert gas inlet 130 and an inert gas outlet 135, through which an inert gas, for example carbon dioxide, can be supplied to and discharged from the metal bath 30.

[0127] Furthermore, the counter-punch unit 1c includes an inert gas chamber 138, which is arranged above a level 35 of the metal bath 30 and serves to cover the metal bath 30 with an inert gas that is heavier than air. The inert gas chamber 138 is itself located above a Fig. 7 The annular gap 137, shown in detail, includes an inert gas receiving chamber 139 in fluid, and in particular gas, communication. The inert gas receiving chamber 139, and optionally the annular gap 137 itself, is in turn connected to the inert gas inlet 130 and the inert gas outlet 135 in fluid, and in particular gas, communication.

[0128] Furthermore, the counter-punch unit 1c is equipped with a quick-change system 150 for connection to a press or lifting device (not shown), whereby by means of such a lifting device it is possible to raise or lower the counter-punch unit 1c as a whole and / or the container 50 relative to, among other things, the outer sleeve 140 and the sealing disc 145 in a vertical direction. Such a relative movement is evident, for example, from a comparison of the Fig. 1 and the Figs. 3 to 5 highlighting, whereby the Figs. 1 to 5 The respective operating states of the device according to the invention are shown, which are reversibly traversed by the device according to the invention for the production of the three-dimensionally shaped flat glass object 10.

[0129] According to the invention, the counter-punch unit 1c further comprises an outer sleeve 140 surrounding the metal bath 30 with a sealing disc 145.

[0130] According to Fig. 1The stamping unit 1a, the transport unit 1b and the counter-stamping unit 1c are shown in a schematic view spaced apart from each other.

[0131] Out of Fig. 2 The further course of a forming process carried out according to the invention for the production of a three-dimensionally shaped flat glass object 10 is shown, in which the flat glass object 10 is placed on the edge 55 of the tub for liquid metal 50 by means of the holding device 70.

[0132] In the further course of the forming process carried out according to the invention for the production of a three-dimensionally shaped flat glass object 10, in Fig. 3It is shown that the container 50 for the liquid metal 30 is raised relative to the outer sleeve 140 and the sealing disc 145, whereby the raising of the container 50 for the liquid metal causes the inert gas to be conveyed, in particular forced, out of the inert gas chamber 138 and into the inert gas receiving chamber 139 via the annular gap 137. In this state, the flat glass blank 10 rests on the edge 55 of the container 50 for liquid metal 30 with its edge section and is in contact with the liquid metal 30 on its underside.The contact of the edge section of the flat glass blank 10 with the rim of the tub 55 ensures that this edge section of the flat glass blank 10 remains cooler in relation to the section of the flat glass blank 10 in contact with the liquid metal 30 and, after the cover ring 60 is lowered onto the edge section of the flat glass blank 10, provides a seal such that, in the course of a subsequent and in . Fig. 5 In the depicted pressing process, no metal can escape between the rim of the tub 55 and the flat glass blank 10.

[0133] The in Fig. 5The illustrated operating state of the device according to the invention shows how the flat glass blank 10 is formed into a three-dimensionally shaped flat glass object 10 by lowering the mold die 20. Since liquid metal 30 is displaced during a forming process, depending on the desired shape of the three-dimensionally shaped flat glass object 10, the receptacle 50 for the liquid metal 30, or the trough provided for this purpose, with an inlet and outlet opening 125 for liquid metal 30, is in fluid communication with a pressurizable expansion vessel (not shown). This vessel allows the level of the metal bath to be controlled and also enables the generation of counter-pressure against the mold die 20. This counter-pressure is then applied, via the metal bath 30, to the side of the flat glass object 10 opposite the mold die 20. The further Fig. 6, Fig. 7 and Fig. 8 show respective detailed representations of the in the Figs. 2 to 4marked sections Z, Y and X.

[0134] In the further course of manufacturing the desired three-dimensionally shaped flat glass object 10, after the flat glass object 10 has been formed, the device according to the invention undergoes a process operation reversed to the forming process. In this operation, the punch unit 1a is removed from the counter-punch unit 1c, and subsequently the transport unit 1b with the flat glass object 10 is removed from the forming position. Following this, the formed flat glass object 10 can, for example, be removed from the holding device 70 by means of a vacuum holder, turned over, and placed on a further metal bath 30 for the purpose of surface conditioning. Alternatively, it is conceivable that the edge sections of the flat glass object 10 are first removed and that, after turning over, the flat glass object 10 is surface-conditioned in the same metal bath 30 that also served as the counter-punch to the forming punch 20. Reference symbol list 1 Device according to the invention 1c Counter-stamp unit, metal bath unit 1a Stamp unit 1b Transport unit 10 Flat structures made of glass 20 Mold stamp 100 Mounting ring 30 Molten metal, metal bath 110 Hanging bolts 110' bolt 35 Level of the metal bath 120 Recording 40 Heating 125 Inlet and outlet for liquid metal 41 heating element 42 Sink 130 Inert gas inlet 50 Container, receptacle, or tub for liquid metal 135 Inert gas outlet 137 annular gap 55 bathtub rim 138 Inert gas space 60 Frame, ring, cover ring 139 Inert gas collection chamber 70 Holding device 140 external socket 80 Stamp recording 145 Sealing washer 90 Quick-release system 150 Quick-change system

Claims

1. Method for molding a glass item (10), in particular a three-dimensionally molded planar glass item, characterized by the following steps: a) arranging a planar formation made of glass (10), for example, a planar glass plate having homogeneous thickness or a planar glass plate having inhomogeneous thickness or a pre-molded planar glass plate blank or liquid, flatly distributed glass, between a mold stamp (20) and a melt made of liquid metal (30), in particular tin; b) bringing the temperature of at least one part of the planar formation made of glass (10) to be molded to a forming temperature of the glass, at which the glass has a viscosity in the range of 10 Pas to 106.5 Pas, preferably in the range of 10 Pas to 104 Pas, and particularly preferably in the range of 10 Pas to 103 Pas; c) molding the planar formation made of glass (10) by moving the mold stamp (20) and a surface of the metal melt (30) toward one another, preferably by means of at least one linear movement, for example, by means of a linear motor or servo motor, so that the planar formation made of glass (10) is subjected to pressure either on one side by the mold stamp (20) and on the other side by the metal melt (30) and is molded by the two-sided pressure application and / or by suctioning and clinging of the planar formation made of glass (10) to the mold stamp (20); d) cooling the molded planar formation made of glass (10) to handling temperature below the forming temperature at which the glass has a viscosity of ≥ 107 Pas; and e) demolding the cooled planar formation (10), characterized in that the demolded planar formation (10) is surface-conditioned on both sides in the context of a posttreatment in that the second side to be surface-conditioned, namely the side of the molded planar glass item which has not yet come into contact with a metal bath up to this point, with turning of the planar formation (10), is brought into contact with the metal bath (30) or a second metal bath.

2. Method according to claim 1, characterized in that the planar formation made of glass (10) is preheated before step a) to a temperature at which the glass has a viscosity of ≥ 106.5 Pas, preferably ≥ 107 Pas.

3. Method according to claim 1, characterized in that the planar formation made of glass (10) is provided in that the glass is poured in liquid form onto the metal melt (30) or the mold stamp (20) and then cooled to the forming temperature.

4. Method according to any one of the preceding claims, characterized in that the planar formation made of glass (10) is brought to temperature by means of at least one heater (40), for example, an infrared (IR) heater and / or, possibly additionally, by means of at least one induction heater and / or at least one microwave heater, and / or by heating or cooling of the metal melt (30).

5. Method according to any one of the preceding claims, characterized in that the method is carried out under oxygen exclusion, preferably in an atmosphere inert with respect to the glass, the liquid metal, in particular the tin melt, and the material of the mold stamp, for example, in a noble gas atmosphere, in particular an argon atmosphere, and / or a nitrogen atmosphere and / or a carbon dioxide atmosphere.

6. Method according to any one of the preceding claims, characterized in that the demolding step is carried out by means of application of compressed air to the molded planar formation (10), namely the three-dimensionally molded planar glass item (10).

7. Method according to any one of the preceding claims, characterized in that the second metal bath has a lower temperature than the metal bath (30) used during molding step c).

8. Device for producing a glass item, in particular a three-dimensionally molded planar glass item (10), in particular by means of a method according to any one of preceding claims 1 to 7, wherein the device has a receptacle chamber (50) suitable for accommodating molten metal, in particular tin, and a mold stamp (20) opposite the receptacle chamber (50), wherein a molding chamber is formed between receptacle chamber (50) and mold stamp (20), into which a planar formation made of glass (10), in particular a glass blank or liquid glass, can be introduced and wherein the mold stamp (20) and the metal melt are movable toward one another and the mold stamp (20) possibly has openings for applying negative pressure or positive pressure, so that the planar formation made of glass (10) can be subjected to pressure on one side by the mold stamp (20) and on the other side by the metal melt and can be molded by the two-sided pressure application and / or by suctioning and clinging of the planar formation made of glass (10) to the mold stamp (20) and the mold stamp (20) is surrounded, in particular guided, by a frame (60), in particular a ring, such as a cover ring, wherein the frame (60), in particular the ring, surrounding the mold stamp has openings, wherein a negative pressure or a positive pressure can be generated via the openings at a contact surface between the planar formation made of glass (10) and the mold stamp (20).

9. Device according to claim 8, characterized in that the receptacle chamber (50) is in fluid communication with a container, in particular a compensation container, which is suitable for accommodating molten tin and can possibly be subjected to pressure.

10. Device according to any one of preceding claims 8 to 9, characterized in that the mold stamp (20) is produced from a high temperature resistant material, such as a high-melting-point metal, for example, steel, gold, copper, ruthenium, osmium, zirconium, hafnium, niobium, tantalum, chromium, molybdenum, or tungsten or a high-melting-point alloy or a ceramic inert to glass at temperatures in the range of 700°C to 1600°C, such as a carbide or nitride, or is coated using such a high temperature resistant material.

11. Device according to any one of preceding claims 8 to 10, characterized in that the mold stamp (20) has at least one cavity, in particular at least one channel and / or one line, through which a heating fluid or cooling fluid, which is in particular gaseous, can flow.

12. Device according to any one of preceding claims 8 to 11, characterized in that the mold stamp (20) comprises at least two stamp components, wherein preferably each stamp component is independently movable.

13. Device according to any one of preceding claims 8 to 12, characterized in that the device has at least one transport device, for example, a transport carriage, wherein the at least one transport device is used to guide a holding device (70) and / or a support device for the planar formation made of glass (10), for example, in the form of a gripper or a lance, in order to introduce the planar formation made of glass (10) into the molding chamber and / or to remove a molded planar glass item (10) from the molding chamber.

Images