METHOD FOR SHAPING GLASS PANES

Abstract

The invention relates to a method for shaping a glass pane (1), wherein the glass pane (1) is first heated and then bent until it has reached a shape that corresponds to a predefined target contour (ks), wherein exterior forces act on the glass pane (1) for the purpose of bending the glass pane (1). A change in a local curvature of the glass pane (1) over time is controlled such that the surface of the glass pane (1) simultaneously achieves the target contour at all points of the surface that do not remain static, by setting a temperature, and thus a viscosity, of the glass pane (1) so as not to be constant as a function of the location during the bending operation, and/or by suitably setting forces transferred by mounts (6) and/or pressure forces transferred by one or more pressure strips (3). The application furthermore relates to multiple glazed units produced by the method.

Claims

1. A method for shaping a glass pane, the method comprising: heating the glass pane; bending the glass pane until the glass pane has reached a shape that corresponds to a predefined target contour, wherein at least one exterior force is exerted on the glass pane for the purpose of bending the glass pane, which exterior forces are limited to wherein the at least one exterior force is at least one of: a weight force caused by a weight of the glass pane, a force that is transferred by a support on which the glass pane rests to a surface region of the glass pane which rests on the support, a force that is transferred at an edge of the glass pane into the glass pane by a mount into which the edge of the glass pane is clamped a pressure force transferred by one or more pressure strips to a surface of the glass pane, wherein no more than one pressure strip is used in each concave subregion of the surface; and changing a local curvature of the glass pane over time wherein the changing of the local curvature is controlled such that the surface of the glass pane concurrently achieves the target contour at all points of the surface that do not remain static, by at least one of: setting a temperature, and thus a viscosity, of the glass pane during the bending operation so as not to be constant as a function of the location, and/or by suitably setting forces the force transferred by the mount or by suitably setting the pressure force transferred by the one or more pressure strips.

2. The method according to claim 1, wherein at least one of: the temperature of the glass pane or a deformation of the glass pane are monitored and, based on the at least one of the temperature or the deformation of the glass pane, the temperature, and thus the viscosity, of the glass pane during the bending operation is controlled as a function of the location and/or the force transferred by the mounts and/or the pressure force transferred by the one or more pressure strips are controlled.

3. The method according to claim 1, wherein the target contour is predefined by one or more a target contact area of a bending tool, and the glass pane simultaneously makes contact with the target contact area only at the end of the bending operation.

4. The method according to claim 1, wherein the force transferred by the mounts are at least one of a tensile force or torque.

5. The method according to claim 1, wherein the glass pane is heated using a laser.

6. The method according to claim 1, wherein the temperature of the glass pane is varied locally along a first extension direction of the glass pane as a function of the location, and is set so as to be constant in a second extension direction extending orthogonally with respect to the first extension direction as a function of the location.

7. The method according to claim 6, wherein the temperature of the glass pane is set so as to be constant in a section along the first extension direction, so that a strip-shaped equithermal section arise.

8. The method according to claim 1, wherein a first temperature of a first section of the glass pane to which a curvature is imparted differs from a second temperature of a second section of the glass pane to which a curvature is imparted by at least 1 kelvin to by no more than 30 kelvin during the bending operation.

9. The method according to any one of the preceding claims claim 1, wherein the temperature of the glass pane is thermographically monitored during bending in a region to which a curvature is imparted or in which a curvature is changed.

10. The method according to claim 1, wherein the target contour includes a region that has the shape of a segment of a circle or a quadratic parabolic shape.

11. The method according to claim 1, wherein at least one side length of the glass pane 1.7 m or more.

12. The method according to claim 1, wherein the glass pane is supported in such a way that a portion of the glass pane which is to be moved during the deformation process protrudes, so that the protruding section is at least also moved by the weight force.

13. The method according to claim 12, wherein a curvature is imparted to an inner section of the glass pane which is stronger than a desired curvature in an adjoining section, and the temperature of the glass pane is varied locally along a first extension direction of the glass pane as a function of the location, and is set so as to be constant in a second extension direction extending orthogonally with respect to the first extension direction as a function of the location, so that two or more regions having differing temperatures are present in the inner section.

14. The method according to claim 13, wherein the inner section is heated to a temperature that is above a deformation temperature, and the adjoining section is maintained at a temperature that is below the deformation temperature, wherein a width of the inner section in the first extension direction being at least the glass thickness or at least 3 mm or no more than 200 mm.

15. The method according to claim 13, wherein at least three, regions having differing temperatures are present in the inner region, no more than 15 regions having differing temperatures are present in the inner region.

16. The method according to claim 15, wherein each of the regions having differing temperatures in the inner section has a width, measured in the first extension direction, of a least 1.5 mm, and wherein at least one of the regions has a width of no more than 12 mm.

17. The method according to claim 13, wherein the target contour in the inner section has a constant radius of curvature.

18. A method for producing a multiple glazed unit, the method comprising: heating a first glass pane; bending the first glass pane until the first glass pane has reached a shape that corresponds to a predefined target contour, wherein at least one exterior force is exerted on the first glass pane for the purpose of bending the first glass pane, wherein the at least one exterior force is at least one of: a weight force caused by a weight of the first glass pane, a force that is transferred, by a support on which the first glass pane rests, to a surface region of the first glass pane which rests on the support, a force that is transferred at an edge of the first glass pane into the first glass pane by a mount into which the edge of the first glass pane is clamped, or a pressure force transferred by one or more pressure strips to a surface of the first glass pane, wherein no more than one pressure strip is used in each concave subregion of the surface; changing a local curvature of the first glass pane over time, wherein the changing of the local curvature is controlled such that the surface of the first glass pane concurrently achieves the target contour at all points of the surface that do not remain static, by at least one of: setting a temperature, and thus a viscosity, of the first glass pane during the bending operation so as not to be constant as a function of the location, by suitably setting the force transferred by the mount, or by suitably setting the pressure force transferred by the one or more pressure strips; and joining the first glass pane to a second glass pane, and wherein the second glass pane is bent in the same manner as the first glass pane.

19. The method according to claim 18 for producing a multiple glazed unit, wherein the first glass pane and a second glass pane are each bent separately, and the first glass pane and the second glass pane are thereafter disposed on top of one another in a planar manner.

20. The method according to claim 18, wherein at least one of: an insulating gap remains between the first glass pane and the second glass pane, a film is located between the first glass pane and the second glass pane, a spacer is located between the first glass pane and the second glass pane, or an additional material is located between the first glass pane and the second glass pane.

21. A method for producing a parabolic trough, wherein a plurality of glass panes are each bent separately into a parabolic shape, and the bent glass panes are placed against one another at their edges, wherein the plurality of glass panes are shaped by: heating the glass panes; bending the glass panes until the glass panes have reached a shape that corresponds to a predefined target contour, wherein at least one exterior force is exerted on the glass panes for the purpose of bending the glass panes, wherein the at least one exterior force is at least one of: a weight force caused by a weight of the glass panes, a force that is transferred, by a support on which the glass panes rest to a surface region of the glass panes which rests on the support, a force that is transferred at an edge of the glass panes into the glass panes by a mount into which the edge of the glass panes is clamped, or a pressure force transferred by one or more pressure strips to a surface of the glass panes, wherein no more than one pressure strip is used in each concave subregion of the surface; and changing a local curvature of the glass panes over time, wherein the changing of the local curvature is controlled such that the surface of the glass panes concurrently achieves the target contour at all points of the surface that do not remain static, by at least one of: setting a temperature, and thus a viscosity, of the glass panes during the bending operation so as not to be constant as a function of the location, by suitably setting the force transferred by the mount, or by suitably setting the pressure force transferred by the one or more pressure strips.

22. The method according to claim 21, wherein the glass panes are placed against one another in a longitudinal direction, and each of the bent glass panes extends across an entire width of the parabolic trough extending orthogonally with respect to the longitudinal direction.

23. A multiple glazed unit, comprising: a first glass pane and a second glass pane, wherein at least one of the first glass pane or the second glass pane is shaped by: heating the at least one of the first glass pane or the second glass pane; bending the at least one of first glass pane or the second glass pane until the at least one of the first glass pane or the second glass pane has reached a shape that corresponds to a predefined target contour, wherein at least one exterior force is exerted on the at least one of the first glass pane or the second glass pane for the purpose of bending the at least one of the first glass pane or the second glass pane, wherein the at least one exterior force is at least one of: a weight force caused by a weight of the at least one of the first glass pane or the second glass pane, a force that is transferred, by a support on which the at least one of the first glass pane or the second glass pane rests to a surface region of the at least one of the first glass pane or the second glass pane which rests on the support, a force that is transferred at an edge of the at least one of the first glass pane or the second glass pane into the at least one of the first glass pane or the second glass pane by a mount into which the edge of the at least one of the first glass pane or the second glass pane is clamped, or a pressure force transferred by one or more pressure strips to a surface of the at least one of the first glass pane or the second glass pane, wherein no more than one pressure strip is used in each concave subregion of the surface; and changing a local curvature of the at least one of the first glass pane or the second glass pane over time, wherein the changing of the local curvature is controlled such that the surface of the at least one of the first glass pane or the second glass pane concurrently achieves the target contour at all points of the surface that do not remain static, by at least one of: setting a temperature, and thus a viscosity, of the at least one of the first glass pane or the second glass pane during the bending operation so as not to be constant as a function of the location, by suitably setting the force transferred by the mount, or by suitably setting the pressure force transferred by the one or more pressure strips.

24. The multiple glazed unit according to claim 23, wherein the first glass pane and the second glass pane are equidistantly disposed on top of one another in a planar manner, each of the glass panes comprising at least one inner section having a radius of curvature that is smaller than the radius of curvature of adjoining sections, and the radius of curvature of the second glass pane in the inner section being smaller than the radius of curvature of the first glass pane in the inner section, the second glass pane being shaped and disposed on the concave side of the first pane in such a way that a gap remains between the first glass panes and the second glass pane.

25. The multiple glazed unit according to claim 24, wherein at least one of: a spacer or a plastic film is located in the gap.

26. The multiple glazed unit according to claim 24, wherein a smallest inner radius of curvature of the first glass pane and the second glass pane is at least 2.5 mm and no more than 300 mm.

27. A multiple glazed unit according to claim 24, wherein an angle between the two sections adjoining the inner section which is determined by the curvature is between 20° and 135°.

28. A multiple glazed unit according to claim 24, wherein a third glass pane, which is shaped in the same manner as the at least one of first glass pane or the second glass pane, is equidistantly disposed on a convex side of the first glass pane in a planar manner or is equidistantly disposed on a concave side of the second glass pane in a planar manner.

29. The multiple glazed unit according to claim 23, wherein the multiple glazed unit comprises a parabolic trough comprising: a plurality of parabolically bent glass panes, which are placed against one another in the longitudinal direction at the bent edges thereof, each of the bent glass panes extending across an entire width of the parabolic trough that extends orthogonally with respect to the longitudinal direction.

Description

[0108] In the drawings

[0109] FIGS. 1a-b show bending lines with the associated bending moment curve;

[0110] FIG. 2 shows a chronological progression of a deformation of a glass pane;

[0111] FIGS. 3a-b show a deformation of a glass pane by means of a pressure strip;

[0112] FIG. 4 shows a deformation of a glass pane by means of a pressure strip and movable guidance contact areas;

[0113] FIG. 5 shows a deformation of a glass pane by means of a pressure strip and movable starting contact areas;

[0114] FIG. 6 shows a deformation of a glass pane by means of mounts, by the introduction of a tensile load;

[0115] FIG. 7 shows a deformation of a glass pane by means of mounts, by the introduction of torque;

[0116] FIGS. 8a-b show a temperature-controlled deformation of a glass pane;

[0117] FIGS. 9a-b show a production process of parabolic troughs;

[0118] FIG. 10 shows a double glazed unit according to the present application;

[0119] FIGS. 11a-l show multiple glazed units according to the present application in different embodiments;

[0120] FIGS. 12a-c show views of a glass pane having a curved 3D structure, in different embodiments;

[0121] FIGS. 13a-d show multiple glazed units in the form of structured double glazed elements; and

[0122] FIGS. 14a-h show illustrations of different physical quantities that can be manipulated in methods according to the application.

[0123] FIG. 1a) shows possible bending lines k.sub.s1 and k.sub.s2 for glass panes supported at the ends thereof, and FIG. 1b) shows the associated bending moments M.sub.1 and M.sub.2. The bending line k.sub.s1 corresponds to a cubical parabola, and the bending line k.sub.s2corresponds to a quadratic parabola. The bending moment M.sub.1 associated with k.sub.s1 has a parabolic progression and is, for example, caused by a line load, that is, for example, by a weight force acting on the entire surface area of the glass pane. In contrast, the bending moment associated with k.sub.s2 has a progression that increases in a linear manner toward the center. This is effectuated, for example, by a force acting at the center. This means that a glass pane which is supported at the edges thereof and on which only the weight force acts, under these conditions, will settle in accordance with a cubical parabola. If different shapes are desired, this can be ensured, as in the prior art, by a corresponding mold, however, certain regions of the glass pane will then settle into the mold before other regions of the glass pane and, disadvantageously, will inadvertently be further deformed and/or become corrugated. According to the present application, for example, a pressure strip is used so as to generate the bending moment M.sub.2, for example. As an alternative or in addition, the bending behavior can be influenced by adapting the viscosity by way of a variation of the temperature. These options will be described in greater detail based on the following figures.

[0124] FIG. 2 shows a process according to the application, in which a glass pane 1, in the vicinity of the edges thereof, bears on supports 4. The glass pane 1, as is illustrated by arrows, is shaped from a starting contour k.sub.a to a target contour k.sub.s, which in the present case is defined by the supports 4 and by target contact areas 5. In the process, the glass pane 1 passes intermediate contours k.sub.z1-k.sub.z3.

[0125] The glass pane can, for example, be a soda-lime glass pane, which can be deformed at temperatures starting at approximately 600° C. A thickness of the glass pane can, for example, range between 2 mm and 10 mm.

[0126] For the shaping operation, the glass pane is initially heated and then bent in that exterior forces act on the glass pane 1 at least until it reaches a shape that corresponds to the target contour k.sub.s.

[0127] The exterior forces are limited in the process to [0128] weight forces caused by an inherent weight of the glass pane 1 (see FIG. 3b and FIG. 8) and/or [0129] forces transferred to the glass pane 1 by the supports 4 and/or [0130] forces transferred by potential mounts into which an edge of the glass pane is clamped (see FIGS. 6 and 7), and/or [0131] pressure forces transferred by one or more pressure strips into a surface of the glass pane 1, wherein no more than one pressure strip is used in each concave subregion of the surface (see FIGS. 3 to 5).

[0132] A change of a local curvature of the glass pane 1 over time identified in the figure, from the starting contour k.sub.a, via the intermediate contours k.sub.zi, k.sub.z2 and k.sub.z3, to the target contour k.sub.s, is controlled in the process in such a way that the surface of the glass pane 1 simultaneously achieves the target contour k.sub.s in all areas of the surface that do not remain static. The glass pane thus settles simultaneously onto all five shown target contact areas 5, so that the shaping process is completed at the same time throughout. This is achieved by not setting a temperature, and thus a viscosity, of the glass pane 1 so as to be constant as a function of the location during the bending operation, and/or by suitably setting forces that are transferred by potential mounts and/or the pressure forces transferred by the one or more possible pressure strips 3 for this purpose. This means that, in order to control the change of the curvature k(t) over time, the ratio of the bending moment and the viscosity η, which is proportional to the curvature due to

k(t)∝M/η

[0133] is set in a controlled manner at all times of the bending process, and in all locations of the glass pane (a denotes is “proportional to”). The bending moment M can be modified by varying the forces, and the viscosity n can be modified by varying the temperature. One of these variables can be varied in the process, or both can be varied.

[0134] Process variables such as heat input, temperature and duration of the heat input can be ascertained and optimized in simulation models.

[0135] The supports 4 can, for example, be formed as tubes or in a tubular manner and act as floating mountings for the glass pane 1. The target contact areas 5 are optional for bending tools for carrying out methods described herein, and can be formed as tubes or in a tubular manner. In the shown example, the glass pane 1 only makes contact with the target contact areas, which are formed to be immovable, after having reached the target contour k.sub.5, and at earlier points in time during the bending process is only controlled and deformed by supports 4 and, for example, by pressure strips and/or gravity.

[0136] The temperature of the glass pane 1 and the deformation of the glass pane 1 can be monitored during the bending process. This means that, at different points in time, for example when the glass pane achieves the intermediate contours k.sub.s1-k.sub.z3, the curvature and the temperature can be determined in a spatially resolved manner using optical devices, such as by means of a thermographic camera and/or by means of a laser. Based on the temperature and/or the deformation of the glass pane, the temperature, and thus the viscosity, of the glass pane 1 can be controlled during the bending operation as a function of the location, and the forces, as described above, can be controlled so as to ensure that the target contour k.sub.s is simultaneously achieved for all regions of the glass pane 1.

[0137] The heating of the glass pane 1 and the setting of the temperature of the glass pane 1 are carried out by means of a laser, for example. Other types of force transfer in methods according to the application are shown in FIGS. 3 to 8, by way of example. This means that the force transfer methods described there can be used in the method described here and can be carried out in a controlled manner in connection with the control described here.

[0138] FIG. 3 shows embodiments of processes according to the application in which a pressure force is transferred to the glass pane by means of a pressure strip 3. The glass pane rests on supports 4 in the process. The pressure strip 3 is disposed in each case centrally between the supports 4 on the side of the glass pane 1 facing away from the supports. The glass pane 1 can additionally be fixed in the starting position thereof by additional optional starting contact areas 7, which are disposed on the same side as the pressure strip 3. The pressure strip 3 pushes the heated glass pane 1 against the respective supports 4 and is moved between and through the supports 4, so as to impart a curvature to the glass pane 1. The pressure strip 3 in each case accordingly pushes centrally against the glass pane 1 on the concave side. The starting contour k.sub.a is flat in both cases, and the target contour k.sub.s is a quadratic parabola in both cases, which is predefined by the supports 4 and the target contact areas 5.

[0139] In contrast to FIG. 3b), the glass pane in FIG. 3a) is oriented in such a way that the gravity field of the Earth g acts parallel to the surface of the glass pane 1, and thereby has no influence whatsoever on the deformation of the glass pane 1. This means that only the force that is transferred by the pressure strip 3 in a spatially delimited manner along a line effectuates the deformation, so that a bending moment corresponding to the bending moment M.sub.2 from FIG. 1 is present in pure form. This can be advantageous for achieving the desired target contour. In particular in embodiments according to FIG. 3a), the bending process can be stopped at any arbitrary point in time, wherein a contour obtained as a result always represents a quadratic parabola.

[0140] In FIG. 3b), in contrast, the glass pane 1 is oriented in such a way that the gravity field of the Earth g, and thus the weight force, are directed orthogonal with respect to the surface of the glass pane 1 that is not bent. The glass pane 1 is thereby pressed onto the supports 4, or the deformation can then be supported by the force of gravity. As mentioned, the force of gravity acting in this way alone does not result in the desired target contour k.sub.s at a homogeneous temperature of the glass pane 1. This means that the temperature should be either adapted and/or the force should be transferred in such a way that the contribution of the force of gravity is compensated for or neglected. In the shown example, the force is transferred by the pressure strip 3 so quickly that contributions of the force of gravity can be neglected.

[0141] In the examples from FIGS. 3a) and b), the glass pane 1 can in each case have a spatially homogeneous temperature, which does not vary over time, but may also have a locally and/or temporally varying temperature, for example so as to effectuate corrections of the progression of the curvature over time. In the case of FIG. 3b), it is also possible, for example, for the temperature to vary spatially and temporally, so as to compensate for a possible contribution of the force of gravity to the deformation that would not bend the glass pane to the desired parabolic shape.

[0142] FIG. 4 shows a bending process according to the application for the glass pane 1, which is carried out or predefined as in FIG. 3 by means of a pressure 3 disposed between two supports 4. The force of gravity acts orthogonally with respect to the surface of the glass pane 1 in the process. In this example, the plate is supported from beneath, on the side facing away from the pressure strip 3, by movable guidance contact areas 8, which carry a portion of the load of the glass pane 1 at least prior to the start of the bending operation. The guidance contact areas 8 are lowered during the bending process and have reached a shape at the end of the shaping process that corresponds to the target contour k.sub.s. There may be overlap between shaping as a result of the individual load of the pressure strip 3 and as a result of the weight force, wherein the first usually dominates. The guidance contact areas 8 can be guided in accordance with Steiner's formula at points that form part of the desired parabolic shape. It is also possible to move the guidance contact areas 8 in such a way that the target contour s.sub.k has a different shape. The corresponding deformation can be controlled by varying the temperature of the glass pane 1. Guidance contact areas can also play a partial role in the corresponding deformation, for example in a direction opposite the deformation effectuated by the pressure strip 3. The guidance contact areas 8 can then act as additional pressure strips, of which, for example, no more than one is used in each concave subregion of the surface.

[0143] In an alternative embodiment of such a method using movable guidance contact areas 8, the force of gravity can also act parallel to the surface of the glass pane 1.

[0144] FIG. 5 shows a configuration according to the application, including movable starting contact areas 10, which, similarly to the movable contact areas 8 from

[0145] FIG. 4, carry a portion of the load of the glass pane 1, at least prior to the start of the bending operation, while the weight force acts orthogonally with respect to the surface of the glass pane 1. During the bending operation, the movable starting contact areas 10 can be moved downwardly, for example following the current contour of the glass pane 1. In contrast to the movable guidance contact areas 8, the movable starting contact area 10, however, does not serve as a target contact area. Additional target contact areas 5 are provided, which limit the movement of the glass pane 1 and define the target contour k.sub.5 of the glass pane 1 together with the bending contact areas 4.

[0146] In an alternative embodiment having the features shown in FIG. 5, the force of gravity can also act parallel to the surface of the glass pane 1.

[0147] FIG. 6 shows a method according to the application in which the glass pane 1 is clamped in mounts 6 at opposing edges. The weight force acts perpendicularly to the surface of the glass pane 1 and effectuates the deformation. The target contour skis predefined by target contact areas 5.

[0148] Tensile forces are transferred to the glass pane 1 by the mounts 6, that is, the edges of the glass pane 1 are pulled outwardly by the mounts 6, and the glass pane 1 is lowered into the mold during the bending process, while easing the tension in a controlled manner and correspondingly, moving the mounts 6 toward one another, so that all points of the surface of the glass pane 1 achieve the target contour s.sub.k at the same time. As a result of such a force transfer, the glass pane 1 can, for example, be brought into the target contour k.sub.s again, which has a quadratic parabolic shape.

[0149] FIG. 7 shows a method according to the application in which torque is introduced by the mounts 6, in which the glass pane 1 is clamped at opposing edges. The mounts 6 are rotated in opposite directions, as illustrated by arrows in the figure. The resulting bending moment M is outlined in the figure and has a discontinuity. Proceeding from the target contour k.sub.a, the glass pane is deformed in a controlled manner via the intermediate contours k.sub.z1-k.sub.z3 to the target contour k.sub.s, which represents a segment of a circle, such as a semi-circle. In particular circular segment-like target contours can advantageously be achieved by this kind of force transfer.

[0150] In such embodiments, in which the deforming forces are transferred by way of such torque, the target contact areas 5 are optional. In the shown example, the force of gravity acts orthogonally with respect to the surface of the glass pane 1, but may also act parallel to the surface of the glass pane 1.

[0151] In embodiments comprising mounts 6, the transfer of tensile forces (FIG. 6) and the application of torque (FIG. 7) can also be combined, for example so as to be able to control the deformation with even greater precision, and, for example, enable other target contours.

[0152] FIG. 8 shows a method according to the application for bending the glass pane 1 from the starting contour k.sub.a (FIG. 8a) to the target contour k.sub.s (FIG. 8b), in which the temperature of the glass pane 1 is spatially varied locally along a first extension direction of the glass pane (horizontally in FIG. 8a), and is set so as to be constant in a second extension direction extending orthogonally with respect to the first extension direction (orthogonally with respect to the drawing plane).

[0153] The glass pane is placed onto supports 4 on which it is also fixed by an optional fixation 9. A region of the glass pane 1 which is to be moved during the deformation process protrudes beyond the supports 4. The deformation is now solely effectuated by the gravity field of the Earth g, and thus the weight force, which acts downwardly, as shown by the arrow in FIG. 8, and urges the region protruding beyond the supports 4 downwardly.

[0154] In the process, the temperature of the glass pane 1 is set so as to be constant in sections along the first extension direction, so that strip-shaped equithermal sections a-e arise, of which two outer sections a and e, to which no curvature is to be imparted, are colder than inner sections b, c, d, to each of which a curvature is to be imparted. In particular, the regions a and e can be so cold that the glass cannot be deformed in these regions. The section a corresponds exactly to the region that rests on the supports. The regions b, c, d to which the curvature is to be imparted are each between 5 cm and 1 m wide. The regions a and e are wider than the regions b, c and d.

[0155] The bending moment acting on the glass pane 1, which effectuates the deformation, is dependent on the weight of regions protruding beyond the supports 4 which, at a homogeneous density and constant width of the glass pane, is linearly dependent on the length of the protruding region. The bending moment is furthermore dependent on the lever arm of the protruding regions. This means that a bending moment, which is dependent on a segment length s.sub.1 extending across the sections d and e, acts in the region d. Compared to the region d, a larger bending moment acts in the region c, which is dependent on a segment length s.sub.2 extending across the sections c, d and e. An even greater bending moment acts in the region b, which is proportional to the segment length s.sub.3 extending across the sections b, c, d and e.

[0156] So as to ensure a controlled deformation to the target contour k.sub.5, within the meaning of the present application, the magnitude of the bending moment that acts in the regions b, c, d, to which the curvature is to be imparted, is to be taken into consideration in each of these regions.

[0157] As a result of the relationship,

k(t)∝M/η

[0158] the differing bending moments acting in sections b, c, and d are compensated for in this example by varying the viscosity n by way of the temperature. In this way, the time-dependent curvature can also be controlled when a change in the bending moments by way of additional forces is not contemplated. For example, so as to obtain an identical radius of curvature r.sub.1=r.sub.2=r.sub.3 throughout in the regions b, c, and d, the regions must have differing viscosities due to the respective bending moments that act there being different in magnitude. So as to obtain a predefined curvature, a corresponding temperature adjustment thus has to be carried out. This temperature adjustment can be controlled according to a previously known pattern, or it can be controlled during the process while monitoring the actual contour and the actual temperature, based thereon. In the process, at least the temperature in the regions of the glass pane which are to be bent, that is, at least in the sections b, c, and d, is monitored during the bending operation, for example is thermographically monitored. The curvature is then also optically monitored, for example by means of a laser, at least in the same region, and the temperature is controlled and/or corrected by means of a laser.

[0159] The temperatures present in the sections b, c, and d can, for example, differ from one another in pairs by between 10 kelvin and 30 kelvin.

[0160] The radius of curvature r.sub.1=r.sub.2=r.sub.3 established in the sections b, c, and d is 5 mm or less in this example.

[0161] At the end of the shaping process, the glass pane makes contact with target contact areas 5. The target contact areas 5 are optional and can, for example, in some embodiments be disposed so as to only make contact with the relatively cold section e, which, for example, cannot be deformed at the temperature thereof.

[0162] In methods such as that shown in FIG. 8, it is not precluded that the temperature within the sections b, c, and d varies slightly within the scope of what is technically feasible. In particular, a variation of the temperature across the thickness of the glass pane, by virtue of the process, is possible. Such temperature fluctuations within individual sections are typically less than the temperature differences compared to adjoining sections.

[0163] FIG. 9a) shows a method for producing a parabolic trough according to the prior art, and FIG. 9b) shows a method for producing a parabolic trough according to the present application.

[0164] It is shown in the process in FIG. 9a) how a parabolic trough having large dimensions is produced from a plurality of glass panes 1a-1p. The glass panes 1a-1p have standard sizes of, for example, a maximum side length of 1.7 m and are present in the non-bent form in FIG. 9a) (i). From (i) to (ii), each of the glass panes 1a-1p is bent in a method according to the prior art. In the process, a respective target contour k.sub.s1 is created in glass panes 1e-1l to be disposed in an inner region of the parabolic trough, which is to correspond approximately to central segments of a quadratic parabola. Similarly, a respective target contour 1.sub.s2 is created for the glass panes 1a-1d and 1m-1p to be disposed further to the outside, which accordingly approximates segments of a quadratic parabola located further to the outside. The approximation of the quadratic parabola is typically not satisfactory for both the interior glass panes 1e-1l and for the exterior glass panes 1a-1d and 1m-1p, since, according to the prior art, as mentioned at the outset, cubical functions are to approximate the quadratic parabola. Furthermore, contour errors typically arise, by virtue of the process, in particular in the edge regions of the glass panes 1a-1p. The glass panes are joined as is shown in (iii), wherein the performance capability of the resulting parabolic trough, due to the aforementioned lack of the contours of individual glass panes 1a-1p, is not optimized.

[0165] FIG. 9b), in contrast, shows a method for producing a parabolic trough according to the present application. The parabolic trough is accordingly produced from glass panes 1a, 1r, which are bent separately in methods according to the present application. These can each be the glass pane 1 from one of FIGS. 2-6, for example.

[0166] The glass panes, which are initially present in flat form in (i), are bent from (i) to (ii) to a respective target contour k.sub.s, which is parabolic. A design that is highly true to the contour is thus achieved by the methods described in the present application. As is identified by hatching in FIGS. 9a) and 9b), in the case of FIG. 9a) approximately the progression of an outer region of the parabolic target contour k.sub.5 from FIG. 9b) is to be created for the glass panes 1a-1d and 1m-1p, and approximately the progression of an inner region of the parabolic target contour k.sub.s from FIG. 9b) is to be created for the glass panes 1e-1l. The design according to FIG. 9b) is considerably more true to the contour.

[0167] The bent glass panes 1q, 1r are placed against one another at the bent edges thereof, and are thus stringed along a longitudinal direction of the parabolic trough. Each of the bent glass panes thus extends across an entire width of the parabolic trough extending orthogonally with respect to the longitudinal direction. The parabolic trough shown in FIG. 9b) is characterized by particularly high performance capability, due to the design being highly true to the contour and being in one piece along the width.

[0168] Each of the glass panes 1q, 1r has dimensions at which at least one side length is more than 6 m, for example between 16 and 20 m.

[0169] FIG. 9b shows two glass panes 1q, 1r, however it is also possible to use more than two glass panes having the same properties. It shall be mentioned that the glass panes 1q, 1r can be disassembled after the bending operation in step (ii) for transport, and can be re-assembled at the desired location of the parabolic trough. The performance capability is only minimally impaired by the disassembly. Due to the design being true to the contour, high-performance parabolic troughs are also possible in the case of disassembled and assembled glass panes 1q, 1r. The one-piece design is typically ensured during the bending operation so as to yield the aforementioned design that is true to the contour.

[0170] FIG. 10 shows a double glazed unit, comprising a first glass pane 1s and a second glass pane 1t, which are bent separately, each according to a method as shown in the present application. Thereafter, the first glass pane 1s and the second glass pane 1t were disposed, as shown, on top of one another in a planar manner. As a result of the precision achievable by the above-described methods, the double glazed unit can reliably reproduce a desired contour, and the glass panes 1s and 1t fit precisely on top of one another. Each of the glass panes 1s, 1t is larger than 1.7 m×1.7 m.

[0171] The double glazed unit can be formed as laminated (safety) glass without a space remaining between the two panes 1s, 1t, comprising an interposed plastic film. It is also possible for an insulating gap to be present between the panes 1s, 1t, which, for example, is filled with a poorly heat-conducting gas such as argon, nitrogen or dry air, so as to provide the double glazed unit as an insulating glass pane. The glass panes 1s, 1t are then sealingly bonded around the circumference, and spacers are additionally used.

[0172] FIGS. 11a to l show different embodiments of bent multiple glazed units. They share the common trait that the panes used were each bent individually and according to the application, for example using the method described in connection with FIG. 8. In addition, the bending radii of the panes of a double glazed unit are matched particularly precisely to one another, so as to achieve, at any rate, a particularly upscale multiple glazed unit having advantageous optical properties.

[0173] FIG. 11a shows a double glazed unit in which the second pane 1t is disposed on the concave side of the first pane 1s. Spacers 12 are situated between the two panes. The bends imparted to the panes have a constant radius, and the two sections adjoining the bent regions each have an angle of 90 degrees with respect to one another. The panes are thus bent at a right angle, and the bent sections thus correspond to quadrants. The inner bending radius of the inner second pane is between 3 and 10 mm, for example. A section on which the pane assumes the quadrant shape is accordingly spatially delimited. For imparting the bend, the glass pane is thus overall only heated to above the deformation temperature in a strip-shaped inner section, wherein this strip-shaped section has a width of 30 to 50 mm. The inner bending radius of the first pane is accordingly larger than the inner bending radius of the second pane and is calculated from the inner bending radius of the second layer, plus the thickness of the second pane, plus the thickness of the spacers. The radius can be set in the process with millimeter precision. The pane thicknesses can, for example, be 3 or 4 mm in each case.

[0174] FIG. 11b shows a pane similar to FIG. 11a, this being a triple insulating glass pane, in which additionally, likewise including interposed spacers 12, a third pane 1u is disposed on the convex side of the first pane 1s. The third pane likewise has a curved quarter circle segment, having a radius that is accordingly enlarged compared to the first pane. The gaps, which are delimited by the panes and the spacers 12, can, for example, be evacuated for insulation purposes, or be filled with a gas. The gaps have the same gap width throughout. The sections adjoining the inner bent regions form straight end pieces. However, further bends can be imparted to these sections, in the same direction or in the opposite direction.

[0175] FIG. 11c shows a double laminated safety glass pane. A film having a thickness between, for example, 0.7 mm and 1.6 mm is disposed between two glass panes 1s, 1t, each having a thickness of between 4 and 8 mm, for example. The panes again have 90° bends, which are implemented in spatially drastically delimited sections by quadrants.

[0176] A refinement of the embodiment from FIG. 11c is shown in FIG. 11d, which is a triple laminated safety glass pane. The panes and films each have the same dimensions as in the case of FIG. 11c. The bending radii are precisely matched to the film thicknesses and pane thicknesses, so as to avoid irregularities or air inclusions, which could represent an optical impairment.

[0177] FIG. 11e shows a double insulating laminated safety glass pane. Two elements, which are essentially composed as the safety panes from FIG. 11c, are joined to one another, and spaces are disposed therebetween so as to create a gap that can be evacuated or filled with gas. Such panes can particularly advantageously be used in architecture, for example in high-rises or observation decks, where special requirements exist in terms of safety, thermal insulation, and optical properties.

[0178] FIG. 11f shows another double insulating laminated safety glass pane.

[0179] A respective film is laminated onto two panes, and these two panes are joined to one another with spacers. This is another way to ensure increased safety in the event of glass breakage and favorable insulating capacity.

[0180] FIGS. 11g and 11h show two possible variants of an insulating laminated pane, in which either only the concave-side or only the convex-side pane comprises a film. Depending on requirements, the film can thus also only be provided on one side. If the film, for example, is to be provided on the exterior side of a building, it can be disposed on the correspondingly exterior pane. Depending on the desired design, the concave-side or the convex-side pane can, in turn, form the exterior pane.

[0181] FIG. 11i shows an insulating laminated safety glass pane comprising bullet-proof glass. The design thereof corresponds to the principle shown in FIG. 11e. Here, however, instead of a conventional glass pane, a bullet-proof pane having a thickness of 8 to 10 mm is disposed on the convex side, serving as the outermost pane. The remaining panes have a thickness of 4 mm.

[0182] Another multiple glazed unit comprising bullet-proof glass is shown in FIG. 11j. Here, a plurality of films and panes are alternately disposed, wherein the panes are alternately conventional 4 mm panes and bullet-proof glass. Panes are located on the very outside and the very inside.

[0183] FIGS. 11k and l, finally, illustrate the option of rendering particularly well-insulating laminated panes safer, comprising two gaps according to the example of FIG. 11b, in that at least a portion of the panes from 11b is replaced with a double pane comprising a film. Specifically, it is provided to form the innermost layer and the outermost layer as a double pane comprising a film (FIG. 11l), or even all three (FIG. 11k).

[0184] FIGS. 12a-c show views of a glass pane having a curved 3D structure. FIG. 12a shows how a pane that can be produced by the shown methods can be configured. The structures producible according to the application are thus, in particular, not limited to 2D or quasi-2D structures. Rather, two or more bends can be imparted, which in particular do not have to be parallel to one another. FIGS. 12b and 12c in each case illustrate section A-A through FIG. 12a, wherein in the case of FIG. 12b two sharp bends are imparted along the lines x and y. So as to produce such a structure, for example, the center region of the glass pane may be supported, and the regions located outside of x and y can protrude. Narrow strips can then be heated along the lines x and y, so that the protruding sections sag under the influence of gravity. In the process, the sharp bends can again correspond to segments of circles having radii of a few millimeters. The two bends can in particular be imparted simultaneously. An alternative to the embodiment from FIG. 12b is shown in FIG. 12c. Section A-A is likewise shown here. Instead of sharp bends, curved shapes are involved here, which additionally have opposite bending directions. Such shapes can in particular be imparted using pressure strips and/or gravity and/or clamps (see FIGS. 1a to 7). Pressure strips can be used, for example, on opposite sides of the pane, essentially along the lines x and y. The bends here can be imparted simultaneously or consecutively.

[0185] FIGS. 16a-d show structured double glazed elements in which at least one pane is bent using a method according to the application. A second pane can have a flat shape (FIGS. 13a, b, d) or can likewise be bent (FIG. 13c). The two panes can be laminated to one another, for example using an additional film therebetween. As a result of the deformation of one of the panes, a cavity can be formed between the panes, which thanks to the method can have a complex and very precisely settable shape. It is also possible, of course, to create more than one cavity. The cavities thus created can be used, for example, to introduce additional material 13 therein. The additional material can be a functional element. For example, it may be electronic components or cables. The cavity can also form a channel for a medium or be configured as a pocket. The additional material can be liquid, solid or gaseous. The bent pane is typically limited in terms of the possible shape thereof. Only one surface or one region has to be provided, which allows it to be joined to the second pane.

[0186] FIGS. 14a-h illustrate the physical process again on which the method illustrated in FIG. 8 is based. In particular, physical variables are shown in FIGS. 14b to h, which can be varied spatially along the length of the glass pane 1 shown in FIG. 14a in the method according to the application. FIG. 14a shows the glass pane again, which rests on the supports 4, so that a portion thereof protrudes. The protruding portion is now to be bent downwardly under the influence of the plotted gravity g, wherein a curvature is to be imparted to the inner section formed of the regions b, c, and d. The regions or sections a and d adjoining the inner section are to remain non-deformed (of course, this does not preclude the regions a and e, for example, having already been shaped in preceding steps and, in turn, not being flat at all, but already having a curvature). Accordingly, only the inner regions b, d, and d are heated to above the deformation temperature for the bending operation. FIG. 14b shows the corresponding target curvature by regions. The target curvature is to vanish in the regions a and e, and is to remain constant across the regions b, c, d. The bending moment M.sub.g acting on the glass pane, which results from the force of gravity, is plotted in FIG. 14c across the length of the glass pane 1. It is already apparent here that according to the relationship k.sub.i(t)∝M.sub.i*t/(η.sub.i(T)*li) described at the outset, the desired curvature cannot be producible solely by the bending moment stemming from the force of gravity. Accordingly, the temperature, and thus the viscosity, of the glass pane are not set so as to be constant during bending operation as a function of the location, and the transferred forces are set so that the surface of the glass pane simultaneously achieves the target contour in all areas of the surface that do not remain static, that is, in the regions b, c, d, e in the present case. A contribution to the bending moment is shown in FIG. 14d, which stems from an additional moment M.sub.z introduced by clamps or pressure strips. As is apparent in FIG. 14a, this is a moment that follows, and thereby supports, the bending movement of the glass pane. It makes a constant contribution and can, for example, be used to accelerate the bending process. Another contribution to the bending moment is illustrated in FIG. 14e. This is the moment resulting from an additional force F, wherein the additional force acts directly at the boundary of the regions d and e (so that the section e not to be deformed remains unimpaired), in that additional mass or a pressure strip is provided, for example, at this very spot. The sum of the above-described bending moments is shown in FIG. 14f. As becomes apparent, the bending moments act strongly in the region to which a curvature is to be imparted, while, for example, the region e located behind there is loaded less by comparison. Nonetheless, it is apparent that the bending moment, however, is not constant in the regions b, c, d, which would have to be the case to achieve the curvature shown in 14b. As mentioned, additionally a further available parameter is therefore set, and more particularly the viscosity. In contrast to the bending moment, the viscosity is inversely proportional to the curvature, and it is thus set in such a way that the quotient of the total moment and the viscosity assumes the desired curve that advantageously results in the target curvature. In the process, as was already described, the viscosity is anticipated by accordingly controlling the temperature in the regions b, c, and d. All parameters can be monitored and adapted during the bending process.

LIST OF REFERENCE NUMERALS

[0187] 1, 1a-1u glass pane

[0188] 3 pressure strip

[0189] 4 support

[0190] 5 target contact area

[0191] 6 mount

[0192] 7 starting contact area

[0193] 8 movable guidance contact area

[0194] 9 fixation

[0195] 10 movable starting contact area

[0196] 11 film

[0197] 12 spacer

[0198] 13 additional material

[0199] k.sub.a starting contour

[0200] k.sub.z, k.sub.z1-k.sub.z3 intermediate contour

[0201] k.sub.s, k.sub.s1, k.sub.s2 target contours

[0202] r.sub.1-r.sub.3 target radii

[0203] a-e equithermal sections of the glass pane

[0204] s.sub.1-s.sub.3 segment lengths

[0205] g gravity field of the Earth

[0206] F force

[0207] M bending moment