WO2022002813A1

WO2022002813A1 - Method and device for gravity curving at least one glass sheet

Info

Publication number: WO2022002813A1
Application number: PCT/EP2021/067617
Authority: WO
Inventors: Edouard JACZINE; Adrien DUFFOUR; Thomas TONDU
Original assignee: Saint-Gobain Glass France
Priority date: 2020-07-01
Filing date: 2021-06-28
Publication date: 2022-01-06
Also published as: FR3112139B1; FR3112139A1

Abstract

The invention relates to a curving method and a device (10) for curving at least one glass sheet (12) by gravity, comprising at least one mould defining at least one curving shape for shaping said at least one glass sheet (12), characterised in that the device (10) comprises means (14) for supporting at least one metal sheet (16), forming said mould, that comprises cut-outs (20) configured so as confer deformability thereon, by virtue of which said deformable metal sheet (16) can be shaped so as to adopt said at least one curving shape.

Description

DESCRIPTION

TITLE: Method and device for bending by gravity of at least one sheet of glass

Technical area

The invention relates to a method and a device for bending by gravity at least one sheet of glass. The invention relates more particularly to a device for bending by gravity at least one sheet of glass comprising at least one mold defining at least one form of bending for shaping said at least one sheet of glass.

The invention also relates to a method for bending by gravity at least one sheet of glass by means of such a bending device.

Technical background

Various bending devices are known from the state of the art for bending at least one glass sheet in a bending furnace, which bending devices vary in particular depending on the bending process used.

The main methods of bending fire i glass island (s) are distinguished in particular as a function of the type of “mold” used to shape the sheet or sheets of glass, the method and the bending device used depending on the applications.

Thus, the present invention relates more particularly to a method of bending by gravity in which the bending of the glass sheet (s) is further obtained, after heating, by sagging or collapsing under the action of gravity.

Gravity bending processes are particularly but not exclusively used to manufacture glazing intended for all types of vehicle, in particular motor vehicles but also rail or aeronautical vehicles.

Bending by gravity makes it possible to shape a sheet of glass or several flat sheets of glass simultaneously, in particular for the manufacture of laminated glazing.

In the case of laminated glazing, after having simultaneously undergone bending in the oven, the glass sheets are bonded together by means of a spacer generally formed of at least one spacer sheet of polymer material such as polyvinyl butyral ( PVB).

In the case of toughened glazing, the glass sheet is then toughened on leaving the bending furnace.

Various embodiments of a gravity bending device are known, the choice of which is determined as a function of the applications and in which a distinction can also be made according to whether the bending shape is a solid surface or not.

According to a first design, the bending device used is characterized by the fact of comprising a centrally hollowed out structure which, configured for bending, is generally designated by the term “skeleton” (or “skeleton” in English).

Thus, the “skeleton” of the bending device comprises at least one metal frame (or support) on which rests only the periphery of said at least one sheet of glass. Therefore, said at least one glass sheet is not here intended to come into full cooperation with a solid surface defining the bending shape.

After heating in an oven to a high temperature, sometimes called bending, the glass sheet (s) will then, under the action of gravity, collapse to take a bending shape which is determined by the frame. , which shape of bending generally varies during the bending cycle. According to an exemplary embodiment, the skeleton of the bending device comprises at least two frames (or supports), at least one of which is mounted to move relative to the other.

The first frame of the bending device is sometimes called a "blank" (or "sketcher" in English) while the second frame is called a "finisher" (or "finisher" in English), generally the first frame is movably mounted relative to the second. frame which is fixed to it and arranged on the outside.

According to the variant embodiments, the second “finisher” frame with which the final or definitive bending is carried out may be an independent frame which is arranged inside the first “blank” frame or outside thereof, to a short distance.

Such an exemplary embodiment of the skeleton with at least two separate frames for implementing the steps of a gravity bending process is not, however, limiting.

Generally, the method of bending by gravity with a bending device according to this first design comprises at least two successive steps.

In a first step, the glass sheet or sheets are bent by gravity according to a first shape corresponding to a blank of the final shape, then in a second step (or a subsequent step) the glass sheet or sheets are bent by gravity according to the final shape.

According to another exemplary embodiment, the skeleton of the bending device comprises at least one frame comprising opposite parts which, articulated, are mounted to be movable relative to the rest of the frame in order to obtain at least two forms of bending.

Thus, the side parts are mounted to move relative to the rest of the frame, respectively between at least a first position for which the frame has a shape corresponding to the blank ("sketcher") and a second position for which the frame has another shape corresponding to the final shape (“finisher”).

In the final form ("finisher"), the frame then consists on the one hand of said lateral parts generally folded upwards to occupy the second position and, on the other hand, of the middle part which is therefore common with that used. during the first roughing step.

Such a frame provided with additional movable parts thus constitutes in its operation a skeleton equivalent to a skeleton comprising two separate frames according to the previous exemplary embodiment.

A bending device according to one or other of the exemplary embodiments corresponding to this first design is suitable in particular for bending glass sheets of complex shape and / or glass sheets having a pronounced double bending and / or for the sheets. glass subject to counter-bending in critical areas.

This first design of a bending device is used in particular to obtain a bending shape corresponding to a developable surface, that is to say a surface which can be developed without tearing on a plane (such as for example a cylindrical surface).

Therefore, a bending device according to the first design is not suitable for certain applications. In addition, it is difficult to accurately control the tolerances over the entire surface of the glass sheet (s).

According to a second design, the bending device is a mold obtained by foundry and an upper face of which is then machined in order to obtain the final bending shape for the glass sheet (s).

By comparison with a bending device according to the first design ("skeleton"), such a mold has a bending shape that is not hollowed out centrally but made up of by a solid “hollow” surface which makes it possible in particular to control the tolerances over the entire surface of the glazing.

This is one of the reasons why a mold according to this second design is more particularly used for the bending of aeronautical glazing, in particular in order to meet the tolerance requirements over the entire surface of the glazing.

If such machining of the mold makes it possible to freely obtain various forms of bending, in particular a non-developable surface (that is to say a surface which cannot be developed without tearing on a plane), this is however not without presenting some drawbacks.

First of all, such a mold requires a long manufacturing time to which is then added the costs corresponding to the machining and surfacing operations, in particular to obtain a non-developable surface.

Then, such a mold represents a relatively high mass of metal and therefore a significant thermal inertia, which negatively impacts the duration of a bending cycle during which the glass sheet (s) and the metal mold are heated simultaneously to a temperature. bending temperature.

Consequently, the time of the heating step during the bending cycle will be all the longer the greater the mass of the mold. Furthermore, the use of such a mold lends itself little to mass production, at least with high production rates. This is one of the reasons why new solutions are also sought for shaping glass sheets according to a non-developable surface. The aim of the invention is in particular to provide a new design of a bending device and a bending process making it possible to resolve all or at least part of the disadvantages of the state of the art and which is simple, reliable and economical from its manufacture to its use.

Summary of the invention

For this purpose, the invention provides a bending device of the type described above, characterized in that the device comprises means for supporting at least one sheet which, forming said mold, has cutouts configured to give it a capacity of deformation whereby said deformable sheet is able to be shaped to present said at least one form of bending.

Advantageously, the sheet is deformable, exhibiting a deformation capacity which is determined in particular by all of the cutouts which pierce it and are made over all or part of its surface.

By comparison, a sheet without cutting can have a certain flexibility depending on the material, its thickness, but which at most allows it to be bent, bent, so that the shape obtained cannot be a non-developable surface.

By virtue of said cutouts, the deformable sheet is able to conform in order to freely assume at least one bending shape corresponding in particular to a non-developable surface.

The deformable sheet according to the invention may have a bending shape which is either a developable surface or a non-developable surface then offering a new solution and an alternative to molds according to the second design described in the preamble.

Advantageously, the cutouts passing through the sheet are thin and have the overall width of the dimension of a “pen line”. Preferably, the cuts are made by laser cutting the metal sheet. Preferably, a cutout is in the form of a pattern which, single or not, is for example nested in the patterns of the adjacent cutouts.

Thus, the patterns of said adjacent cutouts in which the pattern of a cutout is nested (or juxtaposed) are either identical patterns, or different patterns when the sheet has cutouts made according to more than one pattern, for example a combination of two complementary reasons.

By way of nonlimiting examples, the cuts are made in a pattern having a general shape "cross" or "star" which respectively comprise four or six branches which are preferably arranged circumferentially in a regular manner around a central point. of the pattern.

The cuts can be made according to a wide variety of patterns, the creation of which is also a function of the deformation capacity sought for the sheet, said deformation capacity determined by the cuts being able to be in one or more directions depending on the applications. .

Indeed, the cutouts advantageously give the sheet a capacity for deformation according to several degrees of freedom, whereby the bending shape is not limited to only developable surfaces, quite the contrary.

Advantageously, the cutouts allow the introduction into the structure of the sheet of articulation points by which said sheet is made deformable.

Advantageously, the deformation capacity of the sheet is mainly determined by the cutouts, the dimensions of which can vary depending on their position on the sheet.

By way of example, cuts of smaller dimensions and therefore in greater number can be made in the central zone of the sheet to give it a deformation capacity different from that of its peripheral zone. Advantageously, the sheet is able to be shaped to take at least one given bending shape and this by corollary adjusting the height of each of the support means arranged below the sheet.

Depending on the sheet support means, the height adjustment is obtained more or less quickly and easily, for example manually with support means comprising mechanical means (of the screw / nut type) or automatically with support means comprising actuators such as jacks.

Advantageously, the deformable sheet according to the invention makes it possible to modify the geometry of the bending shape defined by its upper surface thanks to which said sheet is not limited to a single bending shape associated with a determined glazing (as are by comparison of a frame or a mold according to the prior art).

Indeed, the sheet can take a multiplicity of different bending shapes, in particular by modifying the height adjustment of the support means so that the sheet can be used for bending glazing each having different geometries, that is, ie advantageously in several applications and no longer just one.

Advantageously, the costs are therefore considerably reduced, starting with the manufacturing costs and the production time of a bending device, in particular for the production of prototypes.

Advantageously, the change of the bending shape made possible by a deformable sheet provided with cutouts, associated with adjustable support means, not only makes it possible to vary said bending shape from one application to another but also to vary said shape during a bending cycle. Advantageously, the use of a thin sheet also allows a significant weight reduction compared to a mold obtained from a foundry, by reducing the total mass of the bending device, not only a reduction in the cycle time is obtained (mainly during the step heating) but also a reduction in the energy consumption of the bending furnace.

Indeed, the use of a sheet according to the invention allows a substantial reduction in thermal inertia which has the consequence of reducing the energy consumed inside the furnace during the bending process, a greater part energy being proportionally used to heat the glass and not the metal.

Advantageously, in addition to reducing the cycle time and the energy consumed, the temperature differences existing between the metal of the bending device on the one hand and the glass on the other hand are also reduced.

The invention therefore also contributes to increasing the quality of manufacture by making it possible in particular to reduce the problems linked to the fact that, cooling less quickly than the glass, the metal continues to heat the glass after the final bending, in particular during the bending. compression and cooling step, resulting in the creation of stresses in the glass sheet (s).

Advantageously, the deformability of the sheet is adjusted according to the various parameters, in particular the material, its thickness, the size and / or the distribution of the cuts, the choice of a given pattern or a combination of several patterns for the cuts.

Preferably, the width of a cutout is between 0.1 mm and 0.8 mm, for example around 0.2 mm. The cuts in the sheet are advantageously thin, thanks in particular to the use of laser cutting. Advantageously, the lower surface of the glass sheet is not marked by a deformable sheet produced according to the invention so that the glazing obtained in particular does not exhibit any optical defects.

Depending on the applications, the sheet of the bending device is coated with at least one interlayer suitable for hot glass, which interlayer is for example a fabric of refractory fibers (stainless metal, ceramic, etc.).

According to other characteristics of the invention:

- Said bending shape of the sheet is a non-developable surface, that is to say a surface which cannot be developed without tearing on a plane, or a developable surface;

- at least part of the cuts are made in the form of at least one pattern, such as a pattern in the shape of a cross or a star, or in the form of two complementary patterns;

- the pattern of a cutout is nested in the patterns of adjacent cutouts, said patterns being or not identical or the pattern of a cutout is juxtaposed with the patterns of adjacent cutouts, said patterns being identical or not;

- The cutouts all have the same dimension or the cutouts have a dimension which varies according to their position on the sheet so as to selectively vary the deformation capacity according to the zone of the sheet;

- The sheet support means are fixed, for example the support means are formed by vertical metal plates each comprising at least one notch in order to define together a cavity which is intended to receive said sheet;

- at least part of the sheet support means is mounted movably in at least the vertical direction so as to adjust the height of said support means so that the deformable sheet conforms to said at least one form of bending; - at least part of the sheet support means is formed by mechanical means each comprising a rod which is mounted movably vertically so as to allow height adjustment of said support means;

- the rod is provided with a thread to allow height adjustment according to a screw-nut type system or the rod is slidably mounted so as to allow height adjustment, the rod being able to be immobilized by locking means ;

- the sheet support means are arranged to form a mesh of support means extending below the sheet and integral with a base of said device;

- the sheet support means each comprise at least one stud having a support surface, preferably spherical or hemispherical, intended to cooperate with a lower face of the sheet;

- at least part of the sheet support means consists of actuators, such as electromechanical jacks;

- The actuators forming the sheet support means are selectively controlled to cause a change in the shape of the bending of the sheet between at least:

• a first configuration in which the deformable sheet has a shape of bending, called a blank, and

• a second configuration in which the deformable sheet has a so-called final bending shape, corresponding to said desired bending shape for said at least one sheet of glass;

Preferably, the cutouts have one and the same pattern. As a variant, the cutouts have at least two different patterns, advantageously complementary, in particular when the two patterns are overlapping or even interact to obtain a determined deformation capacity. Advantageously, the cuts in the sheet are made by laser cutting. The sheet is made of metal, in particular of steel such as for example “304 L” type steel.

Advantageously, the sheet has a low thickness such that a thickness between 0.4 mm and 2 mm, preferably a thickness of about 0.8 mm.

With this aim, the invention also proposes a method of bending at least one glass sheet by gravity by means of a bending device according to the invention, characterized in that said bending process comprises at least the steps consisting of at :

- Adjust the sheet support means beforehand so that said deformable sheet has a bending shape, called a blank, or a final bending shape;

- heating said at least one sheet of glass placed on the sheet up to a given bending temperature for which a deformation of said at least one sheet of glass is obtained by gravity; and

- cooling said at least one glass sheet when said at least one glass sheet has the final bending shape.

Advantageously, the sheet support means are adjusted prior to the heating step so that said sheet has a surface corresponding directly to the desired final bending shape for said at least one sheet of glass.

Such an adjustment directly to the final bending shape is likely to be achieved whether the sheet support means are formed by mechanical means or by actuators.

Advantageously, the bending process comprises at least one step consisting in selectively controlling all or at least part of the support means to cause a change in the shape of the bending of the sheet between at least: - a first configuration of the support means in which the deformable sheet has the shape of a preform bending, and

a second configuration of the support means in which the deformable sheet has the desired final bending shape for said at least one sheet of glass.

Advantageously, such a change in the shape of the bending of the sheet is implemented when the means for supporting the sheet are formed by actuators, such as electromechanical jacks.

Brief description of the figures

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, for the understanding of which reference is made to the appended drawings in which:

[Fig. 1] FIG. 1 is a perspective view from above which represents a bending device with a glazing according to a first embodiment of the invention and which illustrates means for supporting a sheet comprising cutouts configured to give it a deformation capacity thanks to which the upper surface of the sheet is able to be shaped to present a bending shape, here final;

[Fig. 2] FIG. 2 is a perspective view from below which represents the bending device according to the first embodiment and which more particularly illustrates the mesh of the sheet support means which are positioned under the sheet with their stud having a surface spherical bearing in contact with its lower surface and which are each adjusted to a given height so that the sheet takes on said final bending shape;

[Fig. 3] Figure 3 is a top view which partially shows part of the upper or lower surface of the sheet and which illustrates an example of a cross-shaped pattern for the cutouts, which pattern is nested in the adjacent patterns and corresponds to that shown in Figures 1 and 2;

[Fig. 4] Figure 4 is a top view which partially shows part of the upper or lower surface of the sheet and which illustrates another example of a star-shaped pattern for the cutouts, which pattern is also nested in the adjacent patterns ;

[Fig. 5] FIG. 5 is a perspective view from above which represents a bending device with a glazing according to a second embodiment of the invention and which illustrates means for supporting a sheet which are formed by actuators such as electromechanical jacks;

[Fig. 6] FIG. 6 is a perspective view from below which represents the bending device according to the second embodiment of FIG. 5 and which more particularly illustrates the mesh of the sheet support means formed by actuators of the electromechanical jack type whereby a change in the shape of the bending is also likely to be achieved during bending; [Fig. 7] Figure 7 is a side view which shows the bending device according to Figures 5 and 6 and which illustrates said device in a first configuration corresponding to a deformable sheet having a so-called blank bending shape;

[Fig. 8] FIG. 8 is a side view which represents the bending device according to FIGS. 5 and 6 and which illustrates said device in a second configuration corresponding to a deformable sheet having the desired final bending shape for the glazing. Detailed description of the invention

In the remainder of the description, elements having similar functions or identical structures will be designated by the same reference. In the remainder of the description, the longitudinal, vertical and transverse directions will be adopted without limitation with reference to the trihedron (L, V, T) shown in the figures.

The terms “front” and “rear” will also be used with reference to the longitudinal direction, as well as “upper” and “lower” or “top” and “bottom” with reference to the vertical direction and finally “left” and “right”. »With reference to the transverse direction.

There is shown in Figures 1 to 3 a first embodiment according to the invention of a device 10 for the bending by gravity of at least one sheet 12 of glass.

By way of non-limiting example, the bending device 10 comprises at least one sheet 12 of glass generally having a "water drop" shape, in particular thinned at one of its ends.

Depending on the applications, the bending device 10 comprises one or more sheets 12 of glass which are stacked one on top of the other, in particular when said sheets 12 are intended for the manufacture of laminated glazing.

In the prior art, it is known to use a gravity bending device 10 comprising at least one "mold" defining at least one bending shape to shape said at least one sheet 12 of glass.

As explained in the preamble, said "mold" of the bending device 10 is formed by a mold machined to have a hollow shape of bending when said bending shape is a non-developable surface which in particular cannot be obtained with a device. of "skeleton" type bending.

In known manner, said at least one sheet 12 of glass is heated to a high temperature in an oven, for example of the order of 600 ° C., in order to soften the constituent material (that is to say the glass). so that the sheet or sheets 12 of glass collapses then by gravity to match the bending shape machined in the mold.

According to the invention, the bending device 10 comprises means 14 for supporting at least one sheet 16 which forms such a mold for bending said at least one sheet 12 of glass.

Thus, said sheet 16 is able to define at least one bending shape to shape said at least one sheet 12 of glass.

The bending device 10 comprises a base 18, here shown schematically, to which said means 14 for supporting the sheet 16 are integral.

The base 18 constitutes for example all or part of a frame of the bending device 10, the general structure of which will depend on the applications, in particular of the bending furnace (not shown) in which the bending device 10 is intended to be introduced for placing. carrying out the steps of the bending process.

Different designs of bending furnace are known from the prior art depending on the applications, there are also so-called "single-cell" furnaces receiving a bending device 10 and so-called "tunnel" furnaces in which the bending devices 10 are successively moved. through zones corresponding to the steps of the bending process.

According to an important characteristic of the invention, the sheet 16 has cutouts 20 which are configured to give it a capacity for deformation. Thanks to the deformation capacity conferred by these cutouts 20, said deformable sheet 16 is able to be shaped to present said at least one bending shape intended for shaping said at least one sheet 12 of glass.

Preferably, the sheet 16 is rectangular in shape, with dimensions greater than those of said at least one sheet 12 of glass. The sheet 16 has an upper face 22 and a lower face 24, the upper face 22 being intended to be shaped to present at least said desired final bending shape for said at least one sheet 12 of glass.

Advantageously, the cutouts 20 pass right through the sheet 16, said cutouts 20 opening respectively into the upper face 22 (FIG. 1) and into the lower face 24 (FIG. 2).

Thus, the sheet 16 is perforated by the cutouts 20 as illustrated respectively in Figures 1 and 2. In fact, the cutouts 20 are visible on each of said faces 22 and 24 and preferably cover the entire surface of the sheet 16.

Preferably, the sheet 16 is made of metal, in particular of steel such as for example a steel of the “304 L” type.

Advantageously, the sheet 16 is thin, that is to say formed by a plate or a thin metal sheet.

Preferably, the sheet 16 has a thickness (e) of between 0.4 mm and 2 mm, for example a thickness (e) of about 0.8 mm.

As illustrated in Figures 1 and 2, said bending shape of the sheet 16 is advantageously a non-developable surface, that is to say a surface which cannot be developed without tearing on a plane.

As a variant, said bending shape of the sheet 16 is a developable surface.

The bending device 10 according to the invention is particularly but not exclusively of interest in the case of a bending shape corresponding to such a non-developable surface. Indeed, such a non-developable surface is then advantageously obtained much more quickly and also at a lower cost compared to a mold according to the prior art.

As explained in the preamble with reference to the second design of the bending device, for a bending shape corresponding to a non-developable surface, it was previously necessary to machine a mold previously obtained by foundry which not only was expensive but also required a relatively long manufacturing time.

In addition, such a mold is machined to have one and only one given bending shape. Therefore, the use of said mold is limited to a single application associated with said bending shape. For each new application, it is thus necessary to manufacture a new mold, which is particularly long and expensive.

By comparison in particular with such a machined mold, the deformable sheet 16 according to the invention is capable of being used for multiple applications and not just one.

Unlike the machining of a mold, the shaping of the sheet 16 to make it take at least one bending shape is an operation which is advantageously reversible, said sheet 16 being elastic.

In fact, made deformable thanks to the cutouts 20, the sheet 16 can conform to a multitude of bending shapes and therefore as many applications, which further contributes to increasing the advantages thereof, in particular in terms of costs. The deformable sheet 16 is supported by the support means 14 which, in combination with the cutouts 20, each determine according in particular to their position below the sheet 16 and their height, the conformation taken by the sheet 16 in order to present said at least one form of bending. According to an exemplary embodiment (not shown), the bending device 10 comprises support means 14 which are arranged under the sheet 16 in a position determined in the longitudinal and transverse directions and which each have a given fixed height. The support means 14 then determine a set of surfaces or support points on which the sheet 16 comes to rest, then taking said desired bending shape. By way of example (not shown), the support means 14 comprise vertical metal plates each comprising at least one notch, said plates being juxtaposed parallel to each other in order to define together a cavity which is intended to receive said sheet 16 deformable.

The edge of each plate determines, at the level of the notch, a bearing surface intended to cooperate with the lower face 24 of the sheet 16 to give it the final bending shape.

According to this exemplary embodiment, the support means 14 are fixed, integral with the base 18, and therefore associated with a specific application, only the sheet 16 can be used again for other applications.

This is the reason why the means 14 for supporting the sheet 16 are advantageously adjustable in order to be able to modify the support points of the sheet 16 for each application.

According to an exemplary embodiment (not shown), the means 14 for supporting the sheet 16 are removable in order to modify its position, in particular in the longitudinal and / or transverse direction.

As a variant, the support means 14 are mounted to move relative to the base 18, for example by sliding, so as to be able to move all or part of said support means 14 depending on the application.

Advantageously, the means 14 for supporting the sheet 16 are here arranged to form a mesh of support means 14 extending below the sheet 16 and are integral with the base 18 of the bending device 10.

Advantageously, the means 14 for supporting the sheet 16 are mounted movably in at least the vertical direction so as to adjust the height of each of said means 14 for supporting.

Thus, it is further possible to use only part of the support means 14 by adjusting the height of each of appropriate manner to obtain or not a fulcrum for the sheet 16, for example by retracting the support means 14.

Preferably, all of the means 14 for supporting the sheet 16 is used and the height of each is adjusted so as to form a matrix of determined support points, for each application, as a function of the bending shape according to which the deformable sheet 16 must comply.

As will be understood, by appropriately adjusting the height of each of the support means 14 and by the fact that the sheet 16 has a capacity for deformation thanks to the cutouts 20, the sheet 16 then conforms to take said height. minus one form of crowning.

Thanks to the fact that the support means 14 are adjustable, it is possible to freely shape the sheet 16 according to different forms of bending and therefore to use the bending device 10 according to the invention for multiple applications, which advantageously gives it a "universal" character.

In this first embodiment, the deformable sheet 16 is shaped to take a so-called final bending shape, that is to say directly the desired bending shape for said at least one bending sheet 12 at the end of the process. of crowning.

Indeed, the bending shape of the sheet 16 does not change here during the bending process, said bending shape is initially determined by the height adjustment of the support means 14 in combination with the deformable sheet 16.

According to one characteristic of the means 14 for supporting the sheet 16 of this first embodiment, the shape of the bending does not vary during the bending and this unlike the second embodiment of the bending device 10 which will be described later with reference to figures 5 to 8.

In this first embodiment, the means 14 for supporting the sheet 16 are constituted by mechanical means which are configured to allow at least one height adjustment of said support means 14.

As illustrated in detail by a magnifying glass in FIG. 1, the means 14 for supporting the sheet 16 each comprise a rod 26 which is mounted movably vertically so as to allow the height of each fulcrum of the sheet to be adjusted. 16.

The rod 26 is for example received at its lower end in a foot 28 which is integral with the base 18.

Preferably, the rod 26 is here provided with an external thread 30 through which said rod 26 is mounted to move vertically in a screw-nut type system.

The foot 28 comprises for example an internal thread (not shown) intended to cooperate with the external thread 30 of the rod 26 which is locked in position by a nut 32 at the desired height.

As a variant, the rod 26 is mounted to slide vertically with respect to the foot 28 and locking means such as a notch system or the like are provided to adjust and immobilize each support means 14 at the desired height. Advantageously, the means 14 for supporting the sheet 16 each comprise at least one stud 34 having a bearing surface 36 intended to cooperate with the lower face 24 of the sheet 16. Each rod 26 of the support means 14 is provided at its upper end of such a stud 34. Preferably, the stud 34 comprises a bearing surface 36 which is spherical or hemispherical. Advantageously, such a bearing surface 36 of the stud 34 makes it possible to guarantee a good bearing of the sheet 16 whatever its conformation, that is to say the shape of the bending taken by the sheet 16. As illustrated in FIG. 2, the means 14 for supporting the sheet 16 are arranged to form a mesh (M) of support means 14 extending below the sheet 16. Advantageously, the mesh (M) of support means 14 determines a matrix of support points in which each point corresponds to one of the support means 14, here to a stud 34, and the height of which is individually adjusted as a function of the shape of the bending of the sheet 16.

Such adjustable mechanical means make it possible to adjust the height of said means 14 for supporting the sheet 16, in particular manually. The height adjustment of each of the rods 26 of the mechanical means is carried out beforehand, in particular before the heating step of the bending process.

When the rods 26 of the mechanical means have been manually adjusted to a determined height, the sheet 16 is then placed resting on the studs 34 and in doing so, due to its deformation capacity, the sheet 16 then deforms to take the form final crowning.

Advantageously, the cutouts 20 give the sheet 16 a capacity for deformation according to several degrees of freedom, that is to say several directions of the trihedron (L, V, T).

As a variant, the height adjustment of the mechanical means is automated using actuators in order in particular to reduce the duration of this adjustment step compared to manual implementation. In the case of the first embodiment, the threaded rod 26 could be connected to an actuator selectively controlled to drive it in rotation in order to adjust the height of the stud 34 comprising the support surface 36.

Such a variant will not however be described in more detail since an example of automation will be described more particularly below with reference to a second embodiment of the bending device 10. The cutouts 20 made in the sheet 16 have an essential role since it is the cutouts 20 which mainly determine the deformation capacity of the sheet 16. Of course, the deformation capacity of the sheet 16 is also determined by other characteristics such as the choice of material, the thickness of the sheet, etc. and therefore not only the cutouts 20, in particular their shape, size and / or distribution.

The deformation capacity of sheet 16 is therefore a function of all of these characteristics. Failing to exhibit this deformation capacity, the sheet 16 could not be in contact with all of the pads 34 of the support means 14 which participate in obtaining the bending shape.

As will be understood, the sheet 16 according to the invention is deformable, which in particular goes far beyond being flexible.

In fact, the sheet 16 according to the invention does not simply have a certain flexibility which would allow it to be bent or bent, the sheet 16 is made deformable by the cutouts 20 which allow it to be shaped in one or more directions, to freely take a bending shape which is a non-developable surface or else a developable surface.

Preferably, the cutouts 20 in the deformable sheet 16 are made by laser cutting.

Advantageously, the cutouts 20 in the sheet 16 are thin, having overall in width the dimension of a line, such as a "pen line", and this in particular thanks to the use of laser cutting.

Preferably, the width of a cutout 20 is between 0.1 mm and 0.8 mm, for example about 0.2 mm.

Advantageously, at least part of the cutouts 20 of the sheet 16 is made in the form of at least one pattern or in the form of two complementary patterns.

The complementarity between two patterns may for example emerge from the fact that the patterns interact in the deformation capacity conferred on the sheet 16 or else that the patterns overlap with one another. Preferably, the cutouts 20 are made according to a pattern, for example the pattern in the shape of a “cross” illustrated in FIG. 3 or that in the form of a “star” illustrated in FIG. 4.

As a variant, the cutouts 20 could combine different patterns, in particular depending on the zone of the sheet 16 in which the cutouts 20 are arranged.

Indeed, the deformation capacity or deformability of the sheet 16 is not necessarily uniform over the whole of the sheet 16, for example between the central zone and the peripheral zone of the sheet 16, that is to say in the vicinity of the edges, one may wish to vary the deformation capacity.

In this first embodiment, the cutouts 20 of the sheet 16 have one and the same pattern corresponding to the cross pattern of FIG. 3.

As a variant, the cutouts 20 have at least two different patterns, juxtaposed or not, or even overlapping.

Preferably, the pattern of a cutout 20 is nested in the patterns of the adjacent cutouts 20, said patterns being identical or not.

As a variant, the pattern of a cutout 20 is juxtaposed with the patterns of the adjacent cutouts 20, said patterns being identical or not.

Preferably, the cutouts 20 here all have the same dimension. Alternatively, the cutouts 20 have a dimension which varies depending on their position on the sheet 16 so as to selectively vary the deformation capacity according to the area of the sheet 16.

According to such a variant, the cutouts 20 have for example a dimension which is smaller in a given zone of the sheet 16, in particular decreasing from the periphery towards the center, so that said zone has a greater deformability resulting, at an equivalent surface. , a greater number of cuts 20. The cutouts 20 can be made according to a wide variety of patterns, the creation of which is also a function of the deformation capacity sought for the sheet 16.

Thus, the cutouts 20 made in a pattern having a general "cross" or "star" shape described below are given by way of nonlimiting examples.

As illustrated in Figure 3, the first example of a pattern for a cutout 20 has a general cross shape, said first pattern being referred to as "CROSS".

A pattern has been intentionally highlighted in Figure 3 with a bold line, ie a thicker line, but this only for the purpose of making it easier to visualize compared to other adjacent patterns.

Thus, the line of the cutout 20 corresponding to "void" actually has the same width here as that of all of the other patterns.

Preferably, the width of the cutout 20 (here following said first pattern) is constant over the pattern and is also the same for all the patterns cut from the sheet 16.

The first example of a cross pattern corresponds to that illustrated on the sheet 16 of the first embodiment of the bending device 10 shown in Figures 1 and 2.

This first cutting pattern 20 comprises four branches, respectively referenced b1; b2; b3 and b4.

Preferably, said branches b1; b2; b3 and b4 are arranged circumferentially in a regular manner around a central point O of the pattern.

Each of the branches b1; b2; b3 and b4 of the pattern comprises here successively four rectilinear sections, said sections succeeding each other with the particularity - going from the center O towards the free end of each branch - that from the second section, each section is orthogonal to the section which it precedes. The first sections of each of the branches b1; b2; b3 and b4 are orthogonal and together form the mathematical sign "+" (or "plus").

In this first motif, the four branches b1; b2; b3 and b4 are similar. More precisely, the branches are paired, the branches b1 and b3 being identical as are the branches b2 and b4 to each other.

Indeed, the first pattern has a symmetry with respect to the center O, respectively between the branches b1 and b3 on the one hand and the branches b2 and b4 on the other hand.

By comparison, branches b1 and b3 differ from branches b2 and b4 by the direction of their last section, located at the free end of the branch, longitudinal for some and transverse for others.

It will also be noted with regard to symmetries that a 90 ° rotation of branch b1 in the counterclockwise direction causes said branch b1 to be superimposed perfectly on branch b3 or even to be superimposed on branch b4 if the rotation is carried out inversely. clockwise, this is of course valid for each of said branches b1; b2; b3 and b4.

Each of the branches b1; b2; b3 and b4 presents, after the first section connected to the center O, three sections forming a "U", the fourth section at the free end being oriented towards the interior of the pattern so as to extend orthogonally with respect to the first section .

As indicated above, this first pattern of cutout 20 is nested in the patterns of adjacent cutouts.

Advantageously, the patterns are nested in one another, thanks to which the deformation capacity of the sheet 16 is increased, in particular by limiting the non-deformable portions between two patterns.

Indeed, as can be seen in Figure 3, the branches b1; b2; b3 and b4 each have a branch of another pattern the three sections of which, arranged to form a “U”, are housed head-to-tail, are inserted inside the three sections of the associated branch and which also form a “U”.

As illustrated in Figure 4, the second example of a pattern for a cutout 20 has a general star shape, said second pattern being referenced as "STAR".

This second “STAR” pattern is only one of the many possible variants, in particular with respect to the first “CROSS” pattern described with reference to FIG. 3. As in FIG. 3, a pattern has been deliberately highlighted by means of a bold line, ie a thicker line, but for the sole purpose of making it easier to visualize compared to the other adjacent patterns.

The line of the cutout 20 corresponding to the removal of material, to the "void", in reality here has the same width as that of all of the other patterns of the sheet 16.

Preferably, the width of the cutout 20 of said second pattern is constant over said pattern and the width of the cutout 20 is also the same for all the patterns cut from the sheet 16, here of the second pattern since the sheet 16 does not include preferably only one pattern.

This second cutting pattern 20 has six branches, respectively referenced b'1; b'2; b’3; b’4; b'5 and b'6 which are evenly distributed circumferentially around a center O 'of the pattern.

Each of the b'1 branches; b'2; b’3; b’4; b'5 and b'6 of the pattern successively comprises four rectilinear sections, said sections of a branch together forming a broken line. The sections of a branch are arranged so that the branch curves on itself, the branch having a free end forming a "U".

As for the first motif, the motifs are nested within each other, interpenetrate at the level of each of the U-shaped parts defined by the second, third and fourth sections, the fourth sections of two patterns being arranged head-to-tail and extending parallel to one another.

In the second “STAR” pattern as in the first “CROSS” pattern, the number of branches is an even number. As a variant, the number of branches of the pattern is odd, for example equal to three or to five.

Advantageously, the cutouts 20 according to the first pattern and the second pattern are configured so as not to present, when the sheet 16 is shaped, any protruding part relative to the upper face 22 so as not to mark said at least one sheet 12. of glass by which the presence of optical defects is avoided.

Depending on the applications, the sheet 16 of the bending device 10 is coated with at least one interlayer suitable for hot glass, which interlayer is for example a fabric of refractory fibers (stainless metal, ceramic, etc.).

The first “CROSS” pattern illustrated in FIG. 3 and the second “STAR” pattern illustrated in FIG. 4 only constitute examples of cutouts 20 given without limitation.

In a variant not shown, the sheet 16 comprises a combination of two patterns.

Advantageously, the two patterns are complementary, a first pattern formed for example by a star with six branches being preferably nested with a second pattern formed for example by a star with three branches.

The second pattern formed by the three-pointed star having a branch nested within one of those of the first star pattern so that the first pattern is surrounded by three star patterns according to the first pattern.

In a variant not shown, all or at least part of the cutouts 20 is formed by rectilinear slots, for example a pattern formed by several lines parallel to each other which comprises each a series of slits, in which each straight line comprises a series of slits aligned so as to form a dotted line, said slits of one line being offset with respect to the slits of each adjacent line, i.e. arranged in a staggered arrangement.

In comparison with the first "CROSS" pattern and the second "STAR" pattern, such a slit pattern induces for the sheet 16 a deformation capacity which is oriented and determined by the direction in which the slit lines extend.

There is shown in Figures 5 to 8 a second embodiment according to the invention of a device 10 for the bending by gravity of at least one sheet 12 of glass.

The bending device 10 according to this second embodiment will be described below by comparison with that of the first embodiment.

As in the first embodiment, the bending device 10 comprises means 14 for supporting a sheet 16 perforated by cutouts 20 configured to give it a capacity for deformation so that the deformable sheet 16 is able to be shaped for take at least one form of bending.

Preferably, the sheet 16 is identical to that described above for the first embodiment, said sheet 16 being metallic and comprising cutouts 20 obtained by laser cutting and having for example the first “CROSS” pattern according to FIG. 3 or the second. "STAR" pattern according to figure 4.

As illustrated in Figures 5 to 8, the support means 14 are integral with the base 18 of the bending device 10, advantageously partly integrated into said base 18.

In this second embodiment, the means 14 for supporting the sheet 16 are constituted by actuators. Preferably, the actuators forming said support means 14 are electromechanical jacks.

As illustrated in detail in Figure 5, a support means 14 formed by such a jack comprises a body 38, a rod 40 and means 42 for supplying energy, here electrical.

The rod 40 is mounted to slide vertically with respect to the body 38 which is fixed to the base 18.

Thus, the means 14 for supporting the sheet 16 are mounted so as to move in at least the vertical direction so as to adjust the height of said support means 14 so that the sheet 16 can be shaped according to said at least one form of bending.

As for the first embodiment, the means 14 for supporting the sheet 16 are preferably all vertically adjustable so that the bending device 10 is "universal", advantageously capable of being used for multiple applications in the same way as can the bending device. be the deformable sheet 16.

As illustrated in particular in Figure 6, the sheet support means 14 are arranged to form a mesh (M) of support means 14 extending below the sheet 16. The height of each of the means 14 of sheet support

16 is adjusted so as to form a matrix of determined support points, for each application, depending on the bending shape according to which the sheet 16 is to be shaped.

As explained above, by appropriately adjusting the height of each of the support means 14 and thanks to the cutouts 20 in the sheet 16, said deformable sheet 16 is able to conform to take said at least one form of bending.

Preferably, the means 14 for supporting the sheet 16 formed by the jacks each comprise a stud 34 having a bearing surface 36, each stud 34 arranged at the upper end of the rod 40 of the jack being intended to cooperate with the lower face 24 of the sheet 16. Advantageously, the bearing surface 36 is spherical or hemispherical in order to obtain a contact of the “ball joint” type between the stud 34 and the sheet 16 making it possible to have an optimal contact whatever the shape of bending presented by the sheet 16. It is possible to have optimal contact. recalls that, in the first embodiment, the support means 14 were mechanical means manually adjustable in height by a screw-nut type system.

By comparison, the use of actuators further enables the time to adjust the height of each of said support means 14 to be considerably reduced.

Advantageously, the height adjustment of the rods 40 of the actuators forming the means 14 for supporting the sheet 16 is no longer carried out manually but automatically, for example with the aid of a computer to control all of the jacks. However, this is only one of the advantages of using actuators as the means 14 for supporting the sheet 16.

Indeed, another advantage of actuators compared to mechanical means is to allow dynamic operation of the support means 14, that is to say to be able to modify the settings of the support means 14, during the bending process. , in order to vary the shape of the bending of the sheet 16.

FIGS. 7 and 8 more particularly illustrate such a dynamic operation of the means 14 for supporting the sheet 16 formed by actuators, here the electromechanical jacks.

Advantageously, the actuators forming the means 14 for supporting the sheet are selectively controlled to cause a change in the bending shape of the deformable sheet 16 during the bending process. Thus, the support means 14 are able to be controlled between at least a first configuration illustrated in FIG. 7 and a second configuration illustrated in FIG. 8. The first configuration of the actuators 14 corresponds to a configuration in which the deformable sheet 16 has a bending shape, called a blank.

In this first configuration, the actuators 14 are for example adjusted to substantially the same height, in the low position, so that the sheet 16 extends generally horizontally supported by all of the studs 34.

As illustrated in Figure 7, said at least one sheet 12 of glass extends horizontally over the upper face 22 of sheet 16.

The second configuration of the actuators 14 corresponds to a configuration in which the deformable sheet 16 has a so-called final bending shape.

In this second configuration, each of the actuators 14 is adjusted to a determined height, according to a more or less high position, so that the sheet 16 conforms to take said desired final bending shape for said at least one sheet 12 of glass.

As illustrated in FIG. 8, said at least one sheet 12 of glass is shaped along the non-developable surface presented by the upper face 22 of the sheet 16 shaped according to the final bending shape.

Advantageously, the actuators 14 are selectively controlled to gradually cause a change in the bending shape of the sheet 16, from the blank bending shape to the final bending shape.

The blank bending shape of the sheet 16 corresponds to the initial configuration of the bending device 10, particularly during the heating step, while the final bending shape of the sheet 16 corresponds to the terminal configuration of the bending device 10. before proceeding in particular to the step of cooling said at least one sheet 12 of glass according to the bending process which will be described in more detail below. Indeed, the invention also relates to a method of bending at least one sheet 12 of glass by gravity by a bending device 10, such as that described with reference to FIGS. 1 and 2 for the first embodiment or with reference to in Figures 5 and 6 for the second embodiment.

The bending process according to the invention comprises at least the steps of:

- Pre-adjust the means 14 for supporting the sheet 16 so that said sheet 16 has the shape of bending, called a blank, or the final bending shape (as desired for said at least one sheet 12 of glass);

- Heating said at least one sheet 12 of glass placed on the sheet 16 to a given bending temperature for which a deformation of said at least one sheet 12 of glass is obtained by gravity; and

- cooling said at least one sheet 12 of glass when said at least one sheet 12 of glass has the final bending shape.

According to a first possibility of implementing the bending process, the means 14 for supporting the sheet 16 are adjusted prior to the heating step so that said sheet has an upper surface corresponding directly to the final bending shape desired for said at least one sheet 12 of glass.

This will be the case in particular when the means 14 for supporting the sheet 16 are for example formed by mechanical means or even by actuators selectively controlled to directly obtain the final bending shape, in other words without dynamic use (modification of the height). during the bending process. According to a second possibility of implementing the bending process, the bending process comprises at least one step consisting in selectively controlling the support means 14. to cause a change in the shape of the bending of the sheet 16 between at least:

- a first configuration of the support means 14 in which the sheet 16 has the shape of a preform bending, and - a second configuration of the support means 14 in which the sheet 16 has the desired final bending shape for said at least one 12 sheet of glass.

Such a second implementation of the bending process will advantageously be the one chosen when the means 14 for supporting the sheet 16 are formed by actuators, such as electromechanical jacks.

Claims

1. Device (10) for bending by gravity of at least one sheet (12) of glass comprising at least one mold defining at least one form of bending for shaping said at least one sheet (12) of glass, characterized in that the device (10) comprises means (14) for supporting at least one sheet (16) which, forming said mold, comprises cutouts (20) configured to give it a deformation capacity whereby said sheet (16) deformable is able to be shaped to present said at least one shape of bending.

2. Device (10) according to claim 1, characterized in that said bending shape of the sheet (16) is a non-developable surface or a developable surface.

3. Device (10) according to claim 1 or 2, characterized in that at least part of the cutouts (20) is made in the form of at least one pattern, such as a cross-shaped pattern (CROSS) or star (STAR), or in the form of two complementary patterns.

4. Device (10) according to claim 3, characterized in that the pattern of a cutout (20) is nested in the patterns of the adjacent cutouts (20), said patterns being or not identical, or the pattern of a cutout. (20) is juxtaposed with the patterns, of the adjacent cutouts (20), said patterns being or not being identical.

5. Device (10) according to any one of the preceding claims, characterized in that the cutouts (20) all have the same dimension or the cutouts (20) have a dimension which varies according to their position on the sheet (16). ) so as to selectively vary the deformation capacity as a function of the area of the sheet (16).

6. Device (10) according to any one of the preceding claims, characterized in that at least part of the means (14) for supporting the sheet (16) is movably mounted according to the minus the vertical direction so as to adjust the height of said support means (14) so that the deformable sheet (16) conforms to said at least one form of bending.

7. Device (10) according to any one of the preceding claims, characterized in that at least part of the means (14) for supporting the sheet (16) is constituted by mechanical means each comprising a rod (26) which is mounted movably vertically so as to allow height adjustment of said support means (14).

8. Device (10) according to claim 7, characterized in that the rod (26) is provided with a thread (30) to allow height adjustment according to a system of the screw-nut type or the rod (26) is slidably mounted so as to allow height adjustment, the rod (26) being able to be immobilized by locking means.

9. Device (10) according to any one of the preceding claims, characterized in that the means (14) for supporting the sheet (16) are arranged to form a mesh (M) of support means (14) s' extending below the sheet (16) and integral with a base (18) of said device (10).

10. Device (10) according to any one of the preceding claims, characterized in that the means (14) for supporting the sheet (16) each comprise at least one stud (34) having a bearing surface (36). , preferably spherical or hemispherical, intended to cooperate with a lower face (24) of the sheet (16).

11. Device (10) according to any one of the preceding claims, characterized in that at least part of the means (14) for supporting the sheet (16) consists of actuators, such as electromechanical jacks.

12. Device according to the preceding claim, characterized in that the actuators (14) are selectively controlled for cause a change in the shape of the bending of the plate (16) between at least:

- a first configuration in which the deformable sheet (16) has a bending shape, called a blank, and

- a second configuration in which the deformable sheet (16) has a so-called final bending shape, corresponding to said desired bending shape for said at least one sheet (12) of glass.

13. A method of bending at least one sheet (12) of glass by gravity by means of a bending device (10) according to any one of claims 1 to 12, characterized in that said bending process comprises at minus the steps of:

- Pre-adjust the means (14) for supporting the sheet (16) so that said deformable sheet (16) has a bending shape, called a blank, or a final bending shape;

- heating said at least one sheet (12) of glass placed on the sheet (16) to a given bending temperature for which a deformation of said at least one sheet (12) of glass is obtained by gravity; and

- cooling said at least one sheet (12) of glass when said at least one sheet (12) of glass has the final bending shape.

14. Bending method according to claim 13, characterized in that the means (14) for supporting the sheet (16) are adjusted prior to the heating step so that said sheet (16) has a surface corresponding directly to the final bending shape desired for said at least one sheet of glass.

15. Bending method according to claim 13, characterized in that the bending method comprises at least one step of selectively controlling the support means (14) to cause a change in the shape of the bending of the sheet (16) between at least : - a first configuration of the support means (14) in which the deformable sheet (16) has the shape of a preform bending, and

- a second configuration of the support means (14) in which the deformable sheet (16) has the desired final bending shape for said at least one sheet (12) of glass.