WO2022002736A1 - Frame for bending sheets of glass with reduced tensile stress - Google Patents

Frame for bending sheets of glass with reduced tensile stress Download PDF

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Publication number
WO2022002736A1
WO2022002736A1 PCT/EP2021/067282 EP2021067282W WO2022002736A1 WO 2022002736 A1 WO2022002736 A1 WO 2022002736A1 EP 2021067282 W EP2021067282 W EP 2021067282W WO 2022002736 A1 WO2022002736 A1 WO 2022002736A1
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WO
WIPO (PCT)
Prior art keywords
glass
frame
insulating material
bending
zone
Prior art date
Application number
PCT/EP2021/067282
Other languages
French (fr)
Inventor
Léa GRANDJEAN
Philippe Frebourg
Christophe Machura
Stéphane BERARD
Original Assignee
Saint-Gobain Glass France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint-Gobain Glass France filed Critical Saint-Gobain Glass France
Priority to CN202180003876.XA priority Critical patent/CN114206462A/en
Publication of WO2022002736A1 publication Critical patent/WO2022002736A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B23/00—Re-forming shaped glass
    • C03B23/02—Re-forming glass sheets
    • C03B23/023—Re-forming glass sheets by bending
    • C03B23/025—Re-forming glass sheets by bending by gravity
    • C03B23/0258—Gravity bending involving applying local or additional heating, cooling or insulating means
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B40/00—Preventing adhesion between glass and glass or between glass and the means used to shape it, hold it or support it
    • C03B40/02—Preventing adhesion between glass and glass or between glass and the means used to shape it, hold it or support it by lubrication; Use of materials as release or lubricating compositions
    • C03B40/027—Apparatus for applying lubricants to glass shaping moulds or tools

Definitions

  • the invention relates to a frame for the gravity bending of glass providing reduced extension stresses.
  • a curved glass sheet in particular intended to equip vehicles such as road vehicles advantageously comprises a compression belt reinforcing the entire periphery of the sheet.
  • This compression belt is desired because it gives strength to the glass, necessary in particular for its mounting on a vehicle. It is generally desired that the edge of the glass have edge compressive stresses greater than 4 MPa and preferably greater than 8 MPa (in absolute value).
  • WO94 / 17997 teaches a pressing frame having convex curvatures for pressing a glass sheet against a concave forming mold.
  • the pressing of individual sheets is carried out in a workshop atmosphere (called "cold” by a person skilled in the art) after leaving an oven having brought it to a deformation temperature.
  • the glass is evacuated from its position in the form of bending and cooled on this same frame.
  • This frame includes a ring of insulating material located inside and juxtaposed with the pressing frame to reduce strain on the final glass.
  • the insulation has a square section, is very thick and comes into contact with glass. Since the glass formed is convex when viewed from above, the insulation being under the glass, it is important not to bend by gravity, since then a curvature contrary to that desired would be obtained. The adjustment of the process is therefore made extremely difficult.
  • WO2016085612 teaches forming and annealing glass sheets with edge stress control by holding a compression formed glass sheet on an annealing ring under an upper forming mold heated in a forming station.
  • WO-2019/077278 relates to a device and a method for bending by gravity a sheet of glass or a stack of sheets of glass, called glass, comprising the bending of the glass by gravity on a skeleton comprising a track of contact supporting the lens in the peripheral zone of its lower main face, said contact track comprising concave curvatures in each of the sides of said skeleton, a counter-skeleton comprising a metal bar being present during the bending at a distance "d" from the edge or peripheral area of the upper main face of the lens.
  • Such a so-called radiative counter-skeleton has the function of reducing the undulations tending to form towards the middle of the sides and is particularly useful for the bending of thin glass. Summary of the invention
  • the invention relates to a frame for bending by gravity a sheet of glass or of several superimposed sheets of glass, called the glass, comprising a support track for the peripheral zone of the lens, said track being in the form of a ring seen from above. above, and comprising an insulating material arranged to face the peripheral zone of the glass interior to the ring formed by said track.
  • a compression belt When the insulating material is placed on the outside of the ring, it faces the edge of the glass, said edge becoming in the final glass a zone in compression, called a compression belt.
  • the insulating material When the insulating material is arranged to face the peripheral zone of the glass inside the ring formed by said track as in the invention, it is placed inside the ring to face at least part of the peripheral zone.
  • glass comprising in the final glass extension constraints, in particular the maximum value (in absolute value) of extension stress.
  • the insulating material according to the invention modifies the formation of stresses in the glass during the solidification of the latter. After gravity bending at a temperature between 700 and 600 ° C, the glass is gradually cooled and stresses in the glass generally form between 480 and 450 ° C. These stresses are said to be permanent when the glass is completely set, such as at room temperature for example. Compressive and extension stresses are also qualitatively related to the temperature distribution in glass above 480 ° C.
  • the compression zone known as the “compression belt” goes all the way around the lens and generally has a width in the range from 1 to 10 mm from the edge.
  • the zone in extension is located in the direct vicinity of the zone in compression. It therefore has a ring shape like the outer edge of the lens and is located inside the compression belt. From the edge of the glass, the extended zone can extend to a distance from the edge of the glass of less than 100 mm, generally less than 80 mm, more generally less than 40 mm, which may be less than 15 mm.
  • the values of compressive stresses can be determined by the method described in standard ASTM F218-2005-01, possibly adapted in the event of bending of several superimposed sheets, in order to measure only the stress of the glass having been in the lower position on the bending frame, this sheet being that in the outer position in the laminated glazing as mounted on the vehicle.
  • the stresses can therefore be either measured on the outer glass sheet alone before laminated assembly or on the outer glass sheet after laminated assembly using, for example, Sharples S-69 or VRP-100 devices.
  • the sheet in the outer position on the vehicle corresponds to the sheet in the lower position during gravity bending by the method according to the invention.
  • the edge compressive stress values are determined between 0.1 and 2 mm from an edge and preferably between 0.1 and 1 mm from an edge.
  • the measurements in extension are carried out by the same method in a zone parallel to the edge of the glazing but located slightly more towards the inside of its main face (inside the compression belt which goes around the exterior of the glass).
  • an extension edge stress zone is generally identified which is included in a peripheral zone generally situated between 3 and 100 mm from the edge of the glass.
  • the peripheral zone of the lens is the zone between the edge of the lens and 100 mm from the edge of the lens.
  • the peripheral zone comprises an outer zone in compression (also called a compression belt) extending to the edge of the lens and an extension zone juxtaposed internally to the zone in compression which has just been described.
  • the bending frame generally comprises a skeleton.
  • a skeleton is a strip of metal with one edge facing upwards to act as a track to support the glass.
  • the bending frame is usually covered with a refractory fibrous material, so it is this fibrous material that actually comes into contact with the glass.
  • the bending frame may comprise a skeleton comprising a metal strip, one edge of which faces upward, said edge forming the support track for the glass, or a material comprising refractory fibers covering said edge of the metal strip to form the glass support track.
  • the width of the glass support track (which includes the widening provided by any refractory fibrous material) is generally in the range of 2 to 10 mm.
  • the refractory fibrous material serves to soften the contact of the skeleton with the glass and reduce the risk of hot marking of the glass.
  • the insulating material which is the subject of the present invention more particularly may be of the same nature as that covering the bending frame, but it represents a separate element.
  • the insulating material generally does not come into contact with the glass and essentially acts as a shield against thermal radiation. Seen from above, when the glass rests on the bending frame, the glass is larger than the support track and the entire perimeter of its edge protrudes from it. This overflow is generally included in the range from 1 to 12 mm. Thus, during bending and cooling, the glass protrudes from the support track by a distance in the range of 1 to 12 mm.
  • the idea was to use a gravity bending frame (the glass support track of which therefore has concave curvatures in top view) and to provide it with an insulating material (in the thermal sense) placed vis-à-vis its peripheral zone of a main face of the glass.
  • the glass has two main faces and a wafer going around the glass by its edge.
  • the presence of the insulating material delays the cooling of the glass and because of its arrangement inside the ring, opposite the underside of the glass, the insulating material helps to spread the area in extension, this which decreases the intensity of its maximum, without risking locally causing an inversion of concavity.
  • the final curved glass sheet further includes a high intensity compression belt, and the extended area within the compression belt exhibits a reduced intensity maximum.
  • the edge compressive stress is at least 4 MPa and preferably at least 8 MPa.
  • the maximum extension stress can be reduced to less than 8 MPa and even less than 5 MPa.
  • the compressive stress and extension stress values given in the present application are always absolute values in order to avoid ambiguities.
  • the compressive stress values are generally given with a negative value and the extension stress values are generally given with a positive value, but it happens that some authors do the opposite.
  • the increases or decreases mentioned in constraints are always relative to the absolute values of these constraints.
  • the insulating material generally comprises refractory fibers, in particular metallic fibers which may in particular be made of stainless steel.
  • the fibers can be glass or ceramic, but metal fibers are preferred because of their longer life.
  • the fibers can have a diameter in the range of 5 to 20 ⁇ m.
  • This insulating material can in particular be a felt or a fabric or a knit.
  • a denim type or satin stitch fabric is suitable. This material is not gas-tight and not very dense and therefore has low thermal inertia. Its density surface area is generally between 1000 and 1800 g / m 2 , in particular between 1200 and 1500 g / m 2 .
  • the insulating material is generally in the form of a strip comprising two main faces and two slices, a width equal to the distance between its two slices and a thickness equal to the distance between its two main faces.
  • One of the main faces faces the lens (that is, faces the peripheral area of a main face of the lens).
  • the thickness of the insulating material can be in the range of 0.3 to 5 mm, in particular 0.3 to 2 mm.
  • the width of a main face of the insulating material is generally in the range from 30 to 200 mm, generally 40 to 120 mm, in particular about 80 mm. In its length, this strip follows the shape of the frame.
  • the insulating material "sees" the glass directly, that is to say that no other material is interposed between it and the glass, except possibly a grid through which the insulating material sees the glass directly, but a such a grid between the insulating material and the glass is neither necessary nor desired.
  • it is useful to fix it on a support (said support of the insulating material) more rigid than itself to serve as a supporting structure.
  • the support for the insulating material is therefore placed on the back of the insulating material relative to the glass and serves to hold it in the desired position.
  • the insulating material can be fixed on a support, in particular of the grid or woven fabric type, in particular of the monofilament type, more rigid than the insulating material, said support of the insulating material being connected to the bending frame.
  • This support of insulating material is advantageously adaptable in shape.
  • This support of insulating material can in particular be a grid or woven fabric, in particular of the monofilament type made of stainless steel.
  • the insulating material and the insulating material support may be welded together by microwelds if this is possible given their nature. If they both include stainless steel, the realization of these microwelds is possible.
  • the micro-welding process has the advantage of very little heating, which reduces the risk of deformation during assembly. If one of the two materials is not metallic (eg if the insulation material is ceramic fiber) then they could be sewn together.
  • the insulating material support can for example be made of woven 304 L stainless steel monofilament with a mesh size of 1 mm and a monofilament diameter of 0.32 mm. Its width may be equal to that of the insulating material or at least sufficient to hold it correctly. Its width may be in the range from 30 to 200 mm, generally 40 to 120 mm, in particular approximately 80 mm.
  • the insulating material support can be fixed to the frame or to the frame holding the frame, in particular by means of bases.
  • the bases may for example have the shape of a square or be L-shaped, the two branches of which may in particular form an acute angle between them.
  • the insulating material is placed inside the bending frame, with one of its main faces facing upwards, said main face can be tilted away from the glass when going towards the central area of the glass.
  • the insulating material is therefore arranged so that its upper face is inclined towards the inside of the frame, the distance between the insulating material and the glass increasing with the distance towards the inside of the frame.
  • An angle of inclination is for example then given to the bases holding in position the support of the insulating material (such as a grid) and the insulating material itself so as to tilt the upper face of the insulating material towards the inside of the frame.
  • the distance between the insulating material and the glass therefore increases with the distance from the edge of the glass.
  • Such a configuration makes it possible to have a smoother transition for the glass facing the inner edge of the insulating material. This prevents too great a variation in the temperature of the glass, which makes it possible to avoid any optical trace on the final product once it has cooled and if necessary assembled in laminated glazing. It also helps prevent the insulating material from coming into contact with the glass during the bending process.
  • the curved glass and the frame supporting it are entrained in at least one cooling chamber and generally several successive cooling chambers in which the ambient temperatures are colder than the glass.
  • Each cooling chamber contains a cooler atmosphere than the previous one on the glass path.
  • the main heat transfer mechanism during cooling is radiation.
  • the cooling rate is generally in the range from 1.5 to 0.5 ° C / sec.
  • the amount of heat extracted from glass depends on the temperature difference between the glass and that of the material facing it.
  • the insulating material adopts an intermediate temperature between that of the glass and that of the wall or the bottom of the furnace against which it acts as a screen.
  • the glass On entering a cooling zone of the furnace, the glass has a temperature higher than that of the walls and the bottom of this zone.
  • the glass has in front of it the insulating material, the temperature of which is higher than that of the wall or of the bottom of the furnace. Consequently, the cooling of the glass is slower near the insulating material than elsewhere.
  • Such a difference in cooling behavior can be seen in the graph of Figure 5, where it can be seen that the temperature recorded directly below the insulating material is 30-50 ° C lower than the temperature at the same location but to the side. top of the insulating material.
  • the insulating material is placed inside the ring formed by the glass support track so that one of its main faces faces a zone of the glass between said track and a distance from said track towards the central zone of the lens of less than 200 mm.
  • the insulating material is generally placed under the glass to face the peripheral zone of its lower face, the main face of the insulating material facing the glass is therefore oriented upwards, this face possibly being horizontal or inclined.
  • the insulating material is placed outside the ring formed by the support track for the glass so that one of its main faces faces each other. the edge of the glass; the main face of the insulating material facing the glass is therefore oriented so that the normal to it is horizontal or inclined with respect to the horizontal, this face therefore being able to be vertical or inclined.
  • two possible positions for the insulating material a) inside the support track of the frame to face the peripheral zone of the lens according to the invention, and b) outside the frame support track to face the edge of the glass.
  • edge compressive stress in particular greater than 15 MPa, or even greater than 20 MPa, or even greater than 25 MPa, then, taking into account the necessary balance between compression and extension in the glass, the extension stresses must also be very high.
  • the placement of the insulating material in an external position with respect to the support track may be preferred.
  • the configuration of the bending and cooling device leads to a satisfactory absolute value of the edge compressive stress, that is to say of at least 4 MPa and preferably of at least 8MPa, without exceeding 20 MPa or even without exceeding 15 MPa, then one may wish to keep a good value of edge compressive stress but reduce the maximum absolute value of extension stress, and in this case, in accordance with the invention, the placement of the insulating material in the interior position relative to the support track (according to Figure 1) can be chosen.
  • the positioning of the insulating material in this configuration can even cause an increase (in absolute value) of the maximum value of edge compressive stress (compression belt), which is advantageous if, in the absence of the insulating material, this value is considered insufficient.
  • the invention also relates to a device for bending by gravity a glass sheet or several superimposed glass sheets, called glass, comprising a bending frame by gravity according to the invention and a furnace suitable for containing the bending frame and a glass supported by the frame, the furnace comprising a zone for heating the glass suitable for heating it up to a deformation temperature by gravity, the heating zone comprising a bending zone inside which the glass can be bent by gravity.
  • the furnace comprises, after the bending zone on the path of the glass, a cooling zone capable of providing the glass with controlled cooling leading it to freeze, the ambient temperature in the cooling zone being lower than that in the zone.
  • the device comprising means for conveying the bending frame supporting a glass suitable for conveying it from the bending zone to the cooling zone.
  • the cooling zone includes several cooling chambers through which the frame supporting a glass is conveyed, the ambient temperature of the chambers decreasing from one chamber to another along the path of the glass.
  • the glass is conveyed through the controlled cooling zone at least until it freezes, giving it permanent compressive and extension stresses, that is to say at least up to its strain point temperature.
  • the invention also relates to a method for bending and cooling a sheet of glass or of several superposed sheets of glass, called glass, comprising heating, bending by gravity and cooling of the glass on the frame according to the invention. or by the device according to the invention.
  • a deformation temperature of the glass the latter assumes, in top view, a concave shape, in particular in its central zone.
  • the presence of the insulating material reduces the maximum absolute value of extension stress in the peripheral zone compared to the identical process in the absence of insulating material.
  • the presence of the insulating material additionally increases the maximum value in absolute value of compressive stress compared to the identical method in the absence of insulating material, an observable case if the insulating material is arranged according to the invention to cope with the peripheral zone of the lens inside the ring formed by the support track for the peripheral zone of the lens.
  • FIG. 1 is a sectional view which schematically shows a bending and cooling frame supporting a glass, circulating in a cooling chamber and which illustrates, according to the invention, an insulating material disposed inside the frame for face the peripheral zone of the glass;
  • FIG. 2 is a sectional view which, similar to Figure 1, shows a bending and cooling frame supporting a glass, circulating in a cooling chamber and which illustrates, according to the prior art, an insulating material disposed outside the frame to face the edge;
  • FIG. 3 is a top view which shows a bending frame according to the invention of the skeleton type and which illustrates according to the invention an insulating material in the form of a strip arranged inside the support track that the frame comprises ;
  • FIG. 4 is a perspective view from below which shows part of the bending and cooling frame provided with support means such as a grid and which illustrates said support means forming an infrastructure suitable for carrying the insulating material positioned inside the track as in Figure 1 according to the invention;
  • FIG. 5 is a graph which represents the change in temperatures in ° C on the upper face of the insulating material and the lower face of the insulating material as a function of time (in seconds) and which illustrates the change during the entire process heating and cooling the glass, in the case of an insulating material placed inside the bending and cooling frame like that of FIG. 1;
  • FIG. 6 is a graph which represents, on two different glasses, the evolution in their peripheral zone of the edge stresses in MPa as a function of the distance in mm from the edge of the glasses and going towards their central zone in order to 'illustrate by comparison the results in the absence or presence of an insulating material within the bending and cooling frame.
  • FIG. 1 schematically shows a bending and cooling frame according to the invention supporting a glass, circulating in a cooling chamber.
  • the frame 1 supports the glass 2 by a support track 8, the glass shown being already curved. It can be seen that the glass protrudes from the support track towards the outside thereof, this protrusion generally being between 1 and 12 mm.
  • the frame circulates in the cooling chamber in a direction perpendicular to the figure.
  • This cooling chamber comprises a sole 3 and a wall 4.
  • the insulating material 5 is a strip, one main face of which has the shape of a ring, and faces part of the peripheral zone 6 of the lower main face of the glass. .
  • the insulating material 5 shields thermal radiation between the peripheral zone of the lens 6 inside the lens support track and the sole 3.
  • the insulating material is inclined when starting from the lens support track to go towards the central zone of the lens, so that its distance from the lens is substantially the same everywhere at the end of bending.
  • This inclination could be even greater, generating an extension of the distance between the insulating material and the glass when going from the support track towards the central zone of the glass, in order to cause a more progressive stress profile in the glass between the zone. above but at the end (to the right in the figure) of the insulating material and the area immediately beside which is no longer above the insulating material.
  • FIG. 2 schematically represents a bending and cooling frame according to an alternative embodiment which does not form part of the invention but which can, where appropriate, be combined with the invention in particular illustrated by FIG. 1.
  • the bending and cooling frame supports a glass, circulating in a cooling chamber.
  • the frame 1 supports the glass 2 by a support track 8, the glass shown being already curved.
  • the frame circulates in the cooling chamber in a direction perpendicular to the figure.
  • This cooling chamber comprises a sole 3 and a wall 4.
  • the insulating material 5 is a strip, a main face of which faces the edge of the glass 7. This insulating material is arranged at the outside of the glass support track and shields thermal radiation between the edge of the glass 7 and the wall 4.
  • Figure 3 shows a bending frame 30 according to the invention of the skeleton type in top view.
  • Its glass support track 31 is in the shape of a ring.
  • the insulating material 32 is here a strip disposed inside the ring formed by said track to face part of the peripheral zone of the glass comprising in the final glass extension stresses.
  • the main side of the band shown in the figure is also ring-shaped.
  • the insulating material is arranged here as in Figure 1 relative to the glass support track, that is to say on the inside.
  • the main face of the insulating material thus faces a zone of the lens between said track and a distance from said track towards the central zone of the lens (which corresponds to the central zone 33 of the frame) of less than 200 mm.
  • Figure 4 shows a view from below of a portion of the bending and cooling frame provided with the infrastructure suitable for carrying an insulating material positioned as in Figure 1 according to the invention.
  • the bending and cooling frame 10 is fixed by fixing lugs 11 on a rigid frame 12.
  • "L" -shaped bases 13 are fixed on the fixing lugs 11, branches 14 of the bases having radial directions with respect to the base. frame (i.e. from the frame to the center of the frame).
  • a grid 15 rests on the branches 14 of the "L" of the bases.
  • the insulating material according to the invention (not shown) rests on the grid 15.
  • FIG. 5 represents the change in temperatures in ° C on the upper face 16 of the insulating material and the lower face 17 of the insulating material as a function of time (in seconds) during the entire process of heating and cooling of the glass, in the case of an insulating material placed inside the bending and cooling frame like that of figure 1.
  • FIG. 6 compares, on two different glasses, the evolution in their peripheral zone of the edge stresses in MPa as a function of the distance in mm from the edge of the glasses and towards their central zone.
  • the presence of the insulating material tends here to increase the maximum value (27, 28) of compressive stress (in absolute value, since the maximum value is the most negative on the y-axis of figure 6) and to decrease the value of the maximum (29, 30) of extension constraint (in absolute value).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

Abstract

The invention relates to a frame (30) for the gravity bending of sheets of glass, comprising a support track (31) for supporting the peripheral region of the glass, said track being in the form of a ring when seen from above, and comprising an insulating material (32) disposed so as to face the peripheral region of the glass inside the ring formed by said track. The invention brings about a reduction in the maximum value of tensile stress in the peripheral region of the glass.

Description

DESCRIPTION DESCRIPTION
Titre : CADRE DE BOMBAGE DE FEUILLES DE VERRE A CONTRAINTE D’EXTENSION REDUITE Domaine technique Title: GLASS SHEET BENDING FRAME WITH REDUCED EXTENSION STRESS Technical area
L’invention concerne un cadre pour le bombage par gravité du verre procurant des contraintes d’extension réduites. The invention relates to a frame for the gravity bending of glass providing reduced extension stresses.
Arrière-plan technique Une feuille de verre bombée, notamment destinée à équiper les véhicules comme les véhicules routiers comprend avantageusement une ceinture de compression renforçant toute la périphérie de la feuille. Cette ceinture de compression est souhaitée car elle donne de la solidité au verre, nécessaire notamment pour son montage sur un véhicule. On souhaite généralement que le bord du verre ait des contraintes de compression de bord supérieures à 4 MPa et de préférence supérieures à 8 MPa (en valeur absolue). TECHNICAL BACKGROUND A curved glass sheet, in particular intended to equip vehicles such as road vehicles advantageously comprises a compression belt reinforcing the entire periphery of the sheet. This compression belt is desired because it gives strength to the glass, necessary in particular for its mounting on a vehicle. It is generally desired that the edge of the glass have edge compressive stresses greater than 4 MPa and preferably greater than 8 MPa (in absolute value).
Les contraintes de compression et les contraintes d’extension ayant nécéssairement une résultante nulle globalement dans le verre, la présence de contraintes de compression génère forcément des contraintes d’extension, lesquelles se forment en périphérie du verre juste à l’intérieur de la ceinture de compression. The compressive stresses and the extension stresses necessarily having a zero resultant overall in the lens, the presence of compressive stresses necessarily generates extension stresses, which are formed at the periphery of the lens just inside the band. compression.
Ces contraintes d’extension représentent des zones de fragilités, le verre y étant plus sensible à la casse en cas de gravillonnage ou de choc. Plus l’intensité de ces contraintes d’extension sont fortes, plus le verre est fragile en ces zones en extension, surtout au maximum de contrainte en extension. Vouloir à la fois de fortes contraintes de compression de bord et de faibles contraintes d’extension est antinomique puisque ces deux types de contraintes s’équilibrent dans le verre. De forte contraintes de compression de bord (souhaitées) tendent donc à engendrer de forte contraintes d’extension (non-souhaitées). Le US5591245 enseigne un dispositif pour développer une contrainte de bord dans un four de bombage de pare-brise. Adjacent à un moule annulaire se trouve un cadre supplémentaire plat et métallique de manière à ce que la surface inférieure d'un pare-brise reste à une petite distance du cadre supplémentaire. La contrainte de compression du bord du verre peut être ajustée en faisant varier la distance entre le cadre supplémentaire et le verre et/ou en faisant varier sa taille. These extension constraints represent areas of weakness, the glass being more sensitive to breakage in the event of chipping or impact. The greater the intensity of these extension stresses, the more fragile the glass is in these extension zones, especially at the maximum extension stress. Wanting both high edge compressive stresses and low extension stresses is contradictory since these two types of stresses balance each other out in the glass. High (desired) edge compressive stresses therefore tend to generate high (unwanted) extension stresses. US5591245 teaches a device for developing edge stress in a windshield bending furnace. Adjacent to an annular mold is an additional flat, metal frame so that the bottom surface of a windshield remains a small distance from the additional frame. The Compressive stress of the edge of the glass can be adjusted by varying the distance between the additional frame and the glass and / or by varying its size.
Le W094/17997 enseigne un cadre de pressage présentant des courbures convexes pour presser une feuille de verre contre un moule de formage concave. Selon cette technique, le pressage de feuilles individuelles est réalisé en atmosphère d’atelier (dite « froide » par l’homme du métier) après sortie d’un four l’ayant porté à une température de déformation. Après pressage, le verre est évacué de sa position sous la forme de bombage et refroidie sur ce même cadre. Ce cadre comprend un anneau en matériau isolant situé à l’intérieur du cadre de pressage et en juxtaposition avec celui-ci afin de réduire les contraintes d’extension dans le verre final. WO94 / 17997 teaches a pressing frame having convex curvatures for pressing a glass sheet against a concave forming mold. According to this technique, the pressing of individual sheets is carried out in a workshop atmosphere (called "cold" by a person skilled in the art) after leaving an oven having brought it to a deformation temperature. After pressing, the glass is evacuated from its position in the form of bending and cooled on this same frame. This frame includes a ring of insulating material located inside and juxtaposed with the pressing frame to reduce strain on the final glass.
Comme on peut le voir sur la figure 2 de ce document, l’isolant a une section carrée, est très épais et vient au contact du verre. Comme le verre formé est convexe vue de dessus, l’isolant se trouvant sous le verre, il ne faut surtout pas qu’un bombage par gravité n’intervienne puisqu’alors une courbure contraire à celle souhaitée serait obtenue. Le réglage du procédé est donc rendu extrêmement difficile. As can be seen in Figure 2 of this document, the insulation has a square section, is very thick and comes into contact with glass. Since the glass formed is convex when viewed from above, the insulation being under the glass, it is important not to bend by gravity, since then a curvature contrary to that desired would be obtained. The adjustment of the process is therefore made extremely difficult.
En effet, il faut que le verre se fige rapidement pour empêcher son effondrement, mais l’isolant tend à le garder chaud en périphérie, ces deux aspects étant contradictoires. Indeed, the glass must freeze quickly to prevent it from collapsing, but the insulation tends to keep it warm at the periphery, these two aspects being contradictory.
Le WO2016085612 enseigne le formage et le recuit de feuilles de verre avec contrôle des contraintes de bord en maintenant une feuille de verre formée par compression sur un anneau de recuit sous un moule de formage supérieur chauffé dans une station de formage. Le WO-2019/077278 concerne un dispositif et un procédé de bombage par gravité d'une feuille de verre ou d'un empilement de feuilles de verre, dit le verre, comprenant le bombage du verre par gravité sur un squelette comprenant une piste de contact supportant le verre dans la zone périphérique de sa face principale inférieure, ladite piste de contact comprenant des courbures concaves en chacun des côtés dudit squelette, un contre-squelette comprenant une barre métallique étant présent pendant le bombage à une distance « d » de la tranche ou de la zone périphérique de la face principale supérieure du verre. Un tel contre-squelette, dit radiatif, a pour fonction de réduire les ondulations ayant tendance à se former vers le milieu des côtés et est particulièrement utile pour le bombage de verre mince. Résumé de l’invention WO2016085612 teaches forming and annealing glass sheets with edge stress control by holding a compression formed glass sheet on an annealing ring under an upper forming mold heated in a forming station. WO-2019/077278 relates to a device and a method for bending by gravity a sheet of glass or a stack of sheets of glass, called glass, comprising the bending of the glass by gravity on a skeleton comprising a track of contact supporting the lens in the peripheral zone of its lower main face, said contact track comprising concave curvatures in each of the sides of said skeleton, a counter-skeleton comprising a metal bar being present during the bending at a distance "d" from the edge or peripheral area of the upper main face of the lens. Such a so-called radiative counter-skeleton has the function of reducing the undulations tending to form towards the middle of the sides and is particularly useful for the bending of thin glass. Summary of the invention
L’invention concerne un cadre de bombage par gravité d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre, comprenant une piste de support de la zone périphérique du verre, ladite piste étant en forme d’anneau vue de dessus, et comprenant un matériau isolant disposé pour faire face à la zone périphérique du verre intérieure à l’anneau formé par ladite piste. The invention relates to a frame for bending by gravity a sheet of glass or of several superimposed sheets of glass, called the glass, comprising a support track for the peripheral zone of the lens, said track being in the form of a ring seen from above. above, and comprising an insulating material arranged to face the peripheral zone of the glass interior to the ring formed by said track.
Lorsque le matériau isolant est disposé à l’extérieur de l’anneau, il fait face au bord du verre, ledit bord devenant dans le verre final une zone en compression, dite ceinture de compression. When the insulating material is placed on the outside of the ring, it faces the edge of the glass, said edge becoming in the final glass a zone in compression, called a compression belt.
Lorsque le matériau isolant est disposé pour faire face à la zone périphérique du verre intérieure à l’anneau formé par ladite piste comme dans l’invention, il est placé intérieurement à l’anneau pour faire face à au moins une partie de la zone périphérique du verre comprenant dans le verre final des contraintes d’extension, notamment la valeur maximale (en valeur absolue) de contrainte d’extension. When the insulating material is arranged to face the peripheral zone of the glass inside the ring formed by said track as in the invention, it is placed inside the ring to face at least part of the peripheral zone. glass comprising in the final glass extension constraints, in particular the maximum value (in absolute value) of extension stress.
Le matériau isolant selon l’invention modifie la formation des contraintes dans le verre au cours du figeage de celui-ci. Après le bombage par gravité à une température comprise entre 700 et 600°C, le verre est refroidi progressivement et les contraintes dans le verre se forment généralement entre 480 et 450°C. Ces contraintes sont dites permanentes lorsque le verre est complètement figé, comme à température ambiante par exemple. Les contraintes de compression et d’extension sont aussi liées qualitativement à la distribution de température dans le verre au-dessus de 480°C. The insulating material according to the invention modifies the formation of stresses in the glass during the solidification of the latter. After gravity bending at a temperature between 700 and 600 ° C, the glass is gradually cooled and stresses in the glass generally form between 480 and 450 ° C. These stresses are said to be permanent when the glass is completely set, such as at room temperature for example. Compressive and extension stresses are also qualitatively related to the temperature distribution in glass above 480 ° C.
En effet, le verre ne se fige pas instantanément partout au même moment car la répartition des températures pendant la phase de refroidissement n'est pas homogène ; les zones où le verre est plus froid se figent en premier et, en raison de la contraction thermique du verre pendant le refroidissement, ces zones concentrent la compression. En revanche, les régions qui ont tardé à se figer concentrent les contraintes d’extension. La zone en compression dite « ceinture de compression » fait tout le tour du verre et a généralement une largeur comprise dans le domaine allant de 1 à 10 mm du bord. La zone en extension est située au voisinage direct de la zone en compression. Elle a donc une forme d’anneau comme le bord extérieur du verre et est située intérieurement à la ceinture de compression. A partir du bord du verre, la zone en extension peut aller jusqu’à une distance du bord du verre inférieure à 100 mm, généralement inférieure à 80 mm, plus généralement inférieure à 40 mm, pouvant être inférieure à 15 mm. Indeed, the glass does not freeze instantly everywhere at the same time because the temperature distribution during the cooling phase is not homogeneous; the areas where the glass is colder freeze first and, due to the thermal contraction of the glass during cooling, these areas concentrate the compression. On the other hand, the regions which were slow to freeze concentrate the constraints of extension. The compression zone known as the “compression belt” goes all the way around the lens and generally has a width in the range from 1 to 10 mm from the edge. The zone in extension is located in the direct vicinity of the zone in compression. It therefore has a ring shape like the outer edge of the lens and is located inside the compression belt. From the edge of the glass, the extended zone can extend to a distance from the edge of the glass of less than 100 mm, generally less than 80 mm, more generally less than 40 mm, which may be less than 15 mm.
Les valeurs de contraintes en compression peuvent être déterminées par la méthode décrite dans la norme ASTM F218-2005-01 , éventuellement adaptée en cas de bombage de plusieurs feuilles superposées, afin de ne mesurer que la contrainte du verre ayant été en position inférieure sur le cadre de bombage, cette feuille étant celle en position extérieure dans le vitrage feuilleté tel que monté sur véhicule. Les contraintes peuvent donc être soit mesurées sur la feuille de verre extérieure seule avant assemblage en feuilleté soit sur la feuille de verre extérieure après assemblage en feuilleté à l’aide par exemple des appareils Sharples S-69 ou bien VRP-100. The values of compressive stresses can be determined by the method described in standard ASTM F218-2005-01, possibly adapted in the event of bending of several superimposed sheets, in order to measure only the stress of the glass having been in the lower position on the bending frame, this sheet being that in the outer position in the laminated glazing as mounted on the vehicle. The stresses can therefore be either measured on the outer glass sheet alone before laminated assembly or on the outer glass sheet after laminated assembly using, for example, Sharples S-69 or VRP-100 devices.
Pour que la mesure effectuée après assemblage en vitrage feuilleté soit pertinente, il est nécessaire de colorer la surface intérieure de la feuille de verre extérieure du vitrage à l’aide d’une peinture ou d’un émail noir ou métallisée. La feuille en position extérieure sur le véhicule correspond à la feuille en position inférieure lors du bombage par gravité par le procédé selon l’invention. For the measurement carried out after assembly in laminated glazing to be relevant, it is necessary to color the inner surface of the outer glass sheet of the glazing with a black or metallic paint or enamel. The sheet in the outer position on the vehicle corresponds to the sheet in the lower position during gravity bending by the method according to the invention.
Généralement les valeurs de contraintes en compression de bord sont déterminées entre 0,1 et 2 mm d’un bord et de préférence entre 0,1 et 1 mm d’un bord. Les mesures en extension sont effectuées par la même méthode dans une zone parallèle au bord du vitrage mais située légèrement plus vers l’intérieur de sa face principale (intérieurement à la ceinture de compression qui fait le tour extérieur du verre). Lorsque l’on effectue la mesure au voisinage du bord et à l’intérieur du vitrage, on identifie généralement une zone de contraintes de bord en extension qui est comprise dans une zone périphérique située généralement entre 3 et 100 mm du bord du verre. Dans le cadre de la présente demande, on considère que la zone périphérique du verre est la zone comprise entre le bord du verre et 100 mm du bord du verre. La zone périphérique comprend une zone en compression (également appelée ceinture de compression) extérieure allant jusqu’au bord du verre et une zone en extension juxtaposée intérieurement à la zone en compression venant d’être décrite. Generally the edge compressive stress values are determined between 0.1 and 2 mm from an edge and preferably between 0.1 and 1 mm from an edge. The measurements in extension are carried out by the same method in a zone parallel to the edge of the glazing but located slightly more towards the inside of its main face (inside the compression belt which goes around the exterior of the glass). When the measurement is carried out in the vicinity of the edge and inside the glazing, an extension edge stress zone is generally identified which is included in a peripheral zone generally situated between 3 and 100 mm from the edge of the glass. In the context of the present application, it is considered that the peripheral zone of the lens is the zone between the edge of the lens and 100 mm from the edge of the lens. The peripheral zone comprises an outer zone in compression (also called a compression belt) extending to the edge of the lens and an extension zone juxtaposed internally to the zone in compression which has just been described.
Le cadre de bombage comprend généralement un squelette. Un squelette est une bande de métal dont une tranche est orientée vers le haut pour faire office de piste pour supporter le verre. Le cadre de bombage est généralement recouvert d’un matériau fibreux réfractaire, de sorte que c’est en fait ce matériau fibreux qui vient au contact du verre. The bending frame generally comprises a skeleton. A skeleton is a strip of metal with one edge facing upwards to act as a track to support the glass. The bending frame is usually covered with a refractory fibrous material, so it is this fibrous material that actually comes into contact with the glass.
Ainsi, le cadre de bombage peut comprendre un squelette comprenant une bande métallique dont une tranche est orientée vers le haut, ladite tranche formant la piste de support du verre, ou un matériau comprenant des fibres réfractaires recouvrant ladite tranche de la bande métallique pour former la piste de support du verre. Thus, the bending frame may comprise a skeleton comprising a metal strip, one edge of which faces upward, said edge forming the support track for the glass, or a material comprising refractory fibers covering said edge of the metal strip to form the glass support track.
La largeur de la piste de support du verre (ce qui inclut l’élargissement procuré par l’éventuel matériau fibreux réfractaire) est généralement comprise dans le domaine allant de 2 à 10 mm. Le matériau fibreux réfractaire sert à adoucir le contact du squelette avec le verre et réduire le risque de marquage du verre à chaud. The width of the glass support track (which includes the widening provided by any refractory fibrous material) is generally in the range of 2 to 10 mm. The refractory fibrous material serves to soften the contact of the skeleton with the glass and reduce the risk of hot marking of the glass.
Le matériau isolant faisant plus particulièrement l’objet de la présente invention peut être de même nature que celui habillant le cadre de bombage, mais il représente un élément distinct. Le matériau isolant ne vient généralement pas au contact du verre et joue essentiellement un rôle d’écran aux radiations thermiques. Vu de dessus, lorsque le verre repose sur le cadre de bombage, le verre est plus grand que la piste de support et tout le pourtour de son bord en déborde. Ce débordement est généralement compris dans le domaine allant de 1 à 12 mm. Ainsi, pendant le bombage et le refroidissement, le verre déborde de la piste de support d’une distance comprise dans le domaine allant de 1 à 12 mm. The insulating material which is the subject of the present invention more particularly may be of the same nature as that covering the bending frame, but it represents a separate element. The insulating material generally does not come into contact with the glass and essentially acts as a shield against thermal radiation. Seen from above, when the glass rests on the bending frame, the glass is larger than the support track and the entire perimeter of its edge protrudes from it. This overflow is generally included in the range from 1 to 12 mm. Thus, during bending and cooling, the glass protrudes from the support track by a distance in the range of 1 to 12 mm.
Afin de produire des feuilles de verre bombées dont le maximum de contrainte d’extension est réduit, on a eu l’idée d’utiliser un cadre de bombage par gravité (dont la piste de support du verre présente donc des courbures concaves en vue de dessus) et de le munir d’un matériau isolant (au sens thermique) placé vis- à-vis de sa zone périphérique d’une face principale du verre. Le verre comprend deux faces principales et une tranche faisant le tour du verre par son bord. Quand le verre est porté par le cadre selon l’invention, la face principale supérieure du verre devient concave au bombage et la face inférieure du verre devient convexe au bombage. In order to produce curved glass sheets whose maximum extension stress is reduced, the idea was to use a gravity bending frame (the glass support track of which therefore has concave curvatures in top view) and to provide it with an insulating material (in the thermal sense) placed vis-à-vis its peripheral zone of a main face of the glass. The glass has two main faces and a wafer going around the glass by its edge. When the lens is carried by the frame according to the invention, the upper main face of the lens becomes concave on bending and the lower face of the lens becomes convex on bending.
La présence du matériau isolant retarde le refroidissement du verre et du fait de sa disposition à l’intérieur de l’anneau, en vis-à-vis de la face inférieure du verre, le matériau isolant contribue à étaler la zone en extension, ce qui fait diminuer l’intensité de son maximum, sans risquer de provoquer localement un inversement de concavité. La feuille de verre bombée finale comprend par ailleurs une ceinture de compression de forte intensité et la zone en extension à l’intérieur de la ceinture de compression présente un maximum en intensité réduit. The presence of the insulating material delays the cooling of the glass and because of its arrangement inside the ring, opposite the underside of the glass, the insulating material helps to spread the area in extension, this which decreases the intensity of its maximum, without risking locally causing an inversion of concavity. The final curved glass sheet further includes a high intensity compression belt, and the extended area within the compression belt exhibits a reduced intensity maximum.
La contrainte de compression de bord (ceinture de compression) est d’au moins 4 MPa et de préférence d’au moins 8 MPa. Le maximum de contrainte d’extension peut être réduit à moins de 8 MPa et même moins de 5 MPa. The edge compressive stress (compression belt) is at least 4 MPa and preferably at least 8 MPa. The maximum extension stress can be reduced to less than 8 MPa and even less than 5 MPa.
Les valeurs de contrainte de compression et de contrainte d’extension données dans la présente demande sont toujours des valeurs absolues afin d’éviter les ambiguïtés. Comme dans la présente demande, les valeurs de contraintes de compression sont généralement données avec une valeur négative et les valeurs de contrainte d’extension sont généralement données avec une valeur positive, mais il arrive que certains auteurs fassent l’inverse. Ainsi, dans le cadre de la présente demande, les augmentations ou baisses évoquées de contraintes sont toujours relatives aux valeurs absolues de ces contraintes. Le matériau isolant comprend généralement des fibres réfractaires, notamment métalliques pouvant notamment être en acier inoxydable. Les fibres peuvent être en verre ou céramique mais des fibres en métal sont préférées en raison de leur plus grande durée de vie. The compressive stress and extension stress values given in the present application are always absolute values in order to avoid ambiguities. As in the present application, the compressive stress values are generally given with a negative value and the extension stress values are generally given with a positive value, but it happens that some authors do the opposite. Thus, in the context of the present application, the increases or decreases mentioned in constraints are always relative to the absolute values of these constraints. The insulating material generally comprises refractory fibers, in particular metallic fibers which may in particular be made of stainless steel. The fibers can be glass or ceramic, but metal fibers are preferred because of their longer life.
Les fibres peuvent avoir un diamètre compris dans le domaine allant de 5 à 20 pm. Ce matériau isolant peut notamment être un feutre ou un tissu ou un tricot.The fibers can have a diameter in the range of 5 to 20 µm. This insulating material can in particular be a felt or a fabric or a knit.
Un tissu du type denim ou à point satin est approprié. Ce matériau est non étanche aux gaz et peu dense et présente de ce fait une faible inertie thermique. Sa densité surfacique est généralement comprise entre 1000 et 1800 g/m2, notamment entre 1200 et 1500 g/m2. A denim type or satin stitch fabric is suitable. This material is not gas-tight and not very dense and therefore has low thermal inertia. Its density surface area is generally between 1000 and 1800 g / m 2 , in particular between 1200 and 1500 g / m 2 .
Le matériau isolant a généralement la forme d’une bande comprenant deux faces principales et deux tranches, une largeur égale à la distance entre ses deux tranches et une épaisseur égale à la distance entre ses deux faces principales. Une des faces principales est orientée vers le verre (c’est-à-dire fait face à la zone périphérique d’une face principale du verre). The insulating material is generally in the form of a strip comprising two main faces and two slices, a width equal to the distance between its two slices and a thickness equal to the distance between its two main faces. One of the main faces faces the lens (that is, faces the peripheral area of a main face of the lens).
L’épaisseur du matériau isolant peut être comprise dans le domaine allant de 0,3 à 5 mm, notamment 0,3 à 2 mm. La largeur d’une face principale du matériau isolant est généralement comprise dans le domaine allant de 30 à 200 mm, généralement 40 à 120 mm, notamment environ 80 mm. Dans sa longueur, cette bande suit la forme du cadre. The thickness of the insulating material can be in the range of 0.3 to 5 mm, in particular 0.3 to 2 mm. The width of a main face of the insulating material is generally in the range from 30 to 200 mm, generally 40 to 120 mm, in particular about 80 mm. In its length, this strip follows the shape of the frame.
Le matériau isolant « voit » directement le verre, c’est-à-dire qu’aucun autre matériau n’est interposé entre lui et le verre, sauf éventuellement une grille au travers de laquelle du matériau isolant voit directement le verre, mais une telle grille entre le matériau isolant et le verre n’est ni nécessaire ni souhaitée. Par contre, compte tenu de la souplesse du matériau isolant, il est utile de le fixer sur un support (dit support du matériau isolant) plus rigide que lui pour lui servir de structure portante. Le support du matériau isolant est donc placé au dos du matériau isolant par rapport au verre et sert à le maintenir en la position souhaitée. Ainsi, le matériau isolant peut être fixé sur un support, notamment du type grille ou toile tissée, notamment du type monofil, plus rigide que le matériau isolant, ledit support du matériau isolant étant relié au cadre de bombage. The insulating material "sees" the glass directly, that is to say that no other material is interposed between it and the glass, except possibly a grid through which the insulating material sees the glass directly, but a such a grid between the insulating material and the glass is neither necessary nor desired. On the other hand, taking into account the flexibility of the insulating material, it is useful to fix it on a support (said support of the insulating material) more rigid than itself to serve as a supporting structure. The support for the insulating material is therefore placed on the back of the insulating material relative to the glass and serves to hold it in the desired position. Thus, the insulating material can be fixed on a support, in particular of the grid or woven fabric type, in particular of the monofilament type, more rigid than the insulating material, said support of the insulating material being connected to the bending frame.
Ce support de matériau isolant est avantageusement adaptable en forme. Ce support de matériau isolant peut notamment être une grille ou toile tissée, notamment du type monofil en acier inoxydable. Le matériau isolant et le support de matériau isolant peuvent être soudés ensemble par des microsoudures si c’est possible compte tenu de leur nature. S’ils comprennent tous deux de l’acier inoxydable, la réalisation de ces microsoudures est possible. Le procédé de microsoudage a l’avantage de très peu chauffer, ce qui réduit les risques de déformation lors de l’assemblage. Si l’un des deux matériaux n’est pas métallique (par exemple si le matériau isolant est en fibres céramique), alors ils pourraient être cousus ensemble. Le support de matériau isolant peut par exemple être en monofilament inox 304 L tissé avec une dimension de maille de 1 mm et un diamètre de monofilament de 0,32 mm. Sa largeur peut être égale à celle du matériau isolant ou au moins suffisante pour le maintenir correctement. Sa largeur peut être comprise dans le domaine allant de 30 à 200 mm, généralement 40 à 120 mm, notamment environ 80 mm. This support of insulating material is advantageously adaptable in shape. This support of insulating material can in particular be a grid or woven fabric, in particular of the monofilament type made of stainless steel. The insulating material and the insulating material support may be welded together by microwelds if this is possible given their nature. If they both include stainless steel, the realization of these microwelds is possible. The micro-welding process has the advantage of very little heating, which reduces the risk of deformation during assembly. If one of the two materials is not metallic (eg if the insulation material is ceramic fiber) then they could be sewn together. The insulating material support can for example be made of woven 304 L stainless steel monofilament with a mesh size of 1 mm and a monofilament diameter of 0.32 mm. Its width may be equal to that of the insulating material or at least sufficient to hold it correctly. Its width may be in the range from 30 to 200 mm, generally 40 to 120 mm, in particular approximately 80 mm.
Le support de matériau isolant peut être fixé au cadre ou au châssis tenant le cadre, notamment par le biais d’embases. Les embases peuvent par exemple avoir la forme d’équerre ou être en forme de L dont les deux branches peuvent notamment former entre elles un angle aigu. Le matériau isolant est placé intérieurement au cadre de bombage, une de ses faces principales étant tournée vers le haut, ladite face principale peut être inclinée pour s’éloigner du verre quand on va vers la zone centrale du verre. The insulating material support can be fixed to the frame or to the frame holding the frame, in particular by means of bases. The bases may for example have the shape of a square or be L-shaped, the two branches of which may in particular form an acute angle between them. The insulating material is placed inside the bending frame, with one of its main faces facing upwards, said main face can be tilted away from the glass when going towards the central area of the glass.
Avantageusement, le matériau isolant est donc disposé de manière que sa face supérieure soit inclinée vers l’intérieur du cadre, la distance entre le matériau isolant et le verre augmentant avec la distance vers l’intérieur du cadre. Advantageously, the insulating material is therefore arranged so that its upper face is inclined towards the inside of the frame, the distance between the insulating material and the glass increasing with the distance towards the inside of the frame.
Un angle d'inclinaison est par exemple alors donné aux embases tenant en position le support du matériau isolant (comme une grille) et le matériau isolant lui- même de manière à faire incliner la face supérieure du matériau isolant vers l’intérieur du cadre. La distance entre le matériau isolant et le verre augmente donc avec la distance du bord du verre. Une telle configuration permet d'avoir une transition plus douce pour le verre face au bord intérieur du matériau isolant. Cela évite une variation trop forte de température du verre ce qui permet d'éviter toute trace optique sur le produit final une fois refroidi et le cas échéant assemblé en vitrage feuilleté. Cela permet également d'éviter que le matériau isolant n’entre en contact avec le verre pendant le processus de bombage. An angle of inclination is for example then given to the bases holding in position the support of the insulating material (such as a grid) and the insulating material itself so as to tilt the upper face of the insulating material towards the inside of the frame. The distance between the insulating material and the glass therefore increases with the distance from the edge of the glass. Such a configuration makes it possible to have a smoother transition for the glass facing the inner edge of the insulating material. This prevents too great a variation in the temperature of the glass, which makes it possible to avoid any optical trace on the final product once it has cooled and if necessary assembled in laminated glazing. It also helps prevent the insulating material from coming into contact with the glass during the bending process.
Pendant la phase de refroidissement, le verre bombé et le cadre le supportant sont entraînés dans au moins une chambre de refroidissement et généralement plusieurs chambres de refroidissement successives dans lesquelles les températures ambiantes sont plus froides que le verre. Chaque chambre de refroidissement contient une atmosphère plus froide que la précédente sur le chemin du verre. Le principal mécanisme de transfert thermique pendant le refroidissement est le rayonnement. La vitesse de refroidissement est généralement comprise dans le domaine allant de 1 ,5 à 0,5°C/sec. During the cooling phase, the curved glass and the frame supporting it are entrained in at least one cooling chamber and generally several successive cooling chambers in which the ambient temperatures are colder than the glass. Each cooling chamber contains a cooler atmosphere than the previous one on the glass path. The main heat transfer mechanism during cooling is radiation. The cooling rate is generally in the range from 1.5 to 0.5 ° C / sec.
La quantité de chaleur extraite du verre dépend de la différence de température entre le verre et celui du matériau qui lui fait face. Pendant la phase de refroidissement, le matériau isolant adopte une température intermédiaire entre celle du verre et celle de la paroi ou de la sole du four vis-à-vis de laquelle il fait écran. En entrant dans une zone de refroidissement du four, le verre a une température supérieure à celle des parois et de la sole de cette zone. De même, le verre a en face de lui le matériau isolant dont la température est plus élevée que celle de la paroi ou de la sole du four. En conséquence, le refroidissement du verre est moins rapide à proximité du matériau isolant qu'ailleurs. Une telle différence de comportement de refroidissement est visible sur le graphique de la figure 5, où l’on voit que la température enregistrée directement en dessous du matériau isolant est inférieure de 30 à 50°C à la température au même endroit mais sur le côté supérieur du matériau isolant. The amount of heat extracted from glass depends on the temperature difference between the glass and that of the material facing it. During the cooling phase, the insulating material adopts an intermediate temperature between that of the glass and that of the wall or the bottom of the furnace against which it acts as a screen. On entering a cooling zone of the furnace, the glass has a temperature higher than that of the walls and the bottom of this zone. Likewise, the glass has in front of it the insulating material, the temperature of which is higher than that of the wall or of the bottom of the furnace. Consequently, the cooling of the glass is slower near the insulating material than elsewhere. Such a difference in cooling behavior can be seen in the graph of Figure 5, where it can be seen that the temperature recorded directly below the insulating material is 30-50 ° C lower than the temperature at the same location but to the side. top of the insulating material.
Dans le cadre de la présente invention, le matériau isolant est placé à l’intérieur de l’anneau formé par la piste de support du verre pour que l’une de ses faces principales soit face à une zone du verre comprise entre ladite piste et une distance de ladite piste vers la zone centrale du verre inférieure à 200 mm. Le matériau isolant est généralement disposé sous le verre pour faire face à la zone périphérique de sa face inférieure, la face principale du matériau isolant faisant face au verre est donc orientée vers le haut, cette face pouvant être horizontale ou inclinée. In the context of the present invention, the insulating material is placed inside the ring formed by the glass support track so that one of its main faces faces a zone of the glass between said track and a distance from said track towards the central zone of the lens of less than 200 mm. The insulating material is generally placed under the glass to face the peripheral zone of its lower face, the main face of the insulating material facing the glass is therefore oriented upwards, this face possibly being horizontal or inclined.
Selon une variante qui mise en oeuvre seule ne fait pas partie de la présente invention, le matériau isolant est placé à l’extérieur de l’anneau formé par la piste de support du verre pour que l’une de ses faces principales soit face à la tranche du verre ; la face principale du matériau isolant faisant face au verre est donc orientée de sorte que la normale à elle soit horizontale ou inclinée par rapport à l’horizontale, cette face pouvant donc être verticale ou inclinée. On a donc décrit, ici séparément, deux positions possibles pour le matériau isolant : a) à l’intérieur de la piste de support du cadre pour faire face à la zone périphérique du verre conformément à l’invention, et b) à l’extérieur de la piste de support du cadre pour faire face à la tranche du verre. According to a variant which implemented alone does not form part of the present invention, the insulating material is placed outside the ring formed by the support track for the glass so that one of its main faces faces each other. the edge of the glass; the main face of the insulating material facing the glass is therefore oriented so that the normal to it is horizontal or inclined with respect to the horizontal, this face therefore being able to be vertical or inclined. We have therefore described, here separately, two possible positions for the insulating material: a) inside the support track of the frame to face the peripheral zone of the lens according to the invention, and b) outside the frame support track to face the edge of the glass.
La combinaison (non représentée) sur le même cadre de bombage de deux matériaux isolants disposés en ces deux positions est possible. Le choix de l’une de ces deux positions peut être faite à partir de la détermination de la valeur de la contrainte de compression de bord en l’absence de matériau isolant. The combination (not shown) on the same bending frame of two insulating materials arranged in these two positions is possible. The choice of one of these two positions can be made from the determination of the value of the edge compressive stress in the absence of insulating material.
En effet, si en l’absence de matériau isolant la configuration du dispositif de bombage et de refroidissement mène à une valeur élevée (en valeur absolue) de contrainte de compression de bord, notamment supérieure à 15 MPa, voire même supérieure à 20 MPa, voire supérieure à 25 MPa, alors, compte tenu de l’équilibre nécessaire entre compression et extension dans le verre, les contraintes d’extension doivent également être très élevées. Indeed, if in the absence of insulating material the configuration of the bending and cooling device leads to a high value (in absolute value) of edge compressive stress, in particular greater than 15 MPa, or even greater than 20 MPa, or even greater than 25 MPa, then, taking into account the necessary balance between compression and extension in the glass, the extension stresses must also be very high.
On peut donc alors avoir intérêt à aussi faire baisser la valeur absolue de contrainte de bord en compression, laquelle est de toute façon élevée et peut donc être réduite, pour faire baisser en conséquence la valeur absolue de maximum de contrainte d’extension. Dans ce cas, le placement du matériau isolant en position extérieure par rapport à la piste de support (selon la figure 2) peut être préférée. It may therefore then be advantageous to also lower the absolute value of the edge stress in compression, which is in any case high and can therefore be reduced, in order to consequently lower the absolute value of the maximum extension stress. In this case, the placement of the insulating material in an external position with respect to the support track (according to FIG. 2) may be preferred.
Si par contre en l’absence de matériau isolant la configuration du dispositif de bombage et de refroidissement mène à une valeur absolue de contrainte de compression de bord satisfaisante, c’est-à-dire d’au moins 4 MPa et de préférence d’au moins 8MPa, sans dépasser 20 MPa voire même sans dépasser 15 MPa, alors on pourra souhaiter conserver une bonne valeur de contrainte de compression de bord mais réduire la valeur absolue maximale de contrainte d’extension, et dans ce cas, conformément à l’invention, le placement du matériau isolant en position intérieure par rapport à la piste de support (selon la figure 1) peut être choisie. If, on the other hand, in the absence of insulating material, the configuration of the bending and cooling device leads to a satisfactory absolute value of the edge compressive stress, that is to say of at least 4 MPa and preferably of at least 8MPa, without exceeding 20 MPa or even without exceeding 15 MPa, then one may wish to keep a good value of edge compressive stress but reduce the maximum absolute value of extension stress, and in this case, in accordance with the invention, the placement of the insulating material in the interior position relative to the support track (according to Figure 1) can be chosen.
Avantageusement, le positionnement du matériau isolant dans cette configuration peut même provoquer une augmentation (en valeur absolue) de la valeur maximale de contrainte de compression de bord (ceinture de compression), ce qui est intéressant si, en l’absence du matériau isolant, cette valeur est jugée insuffisante. Advantageously, the positioning of the insulating material in this configuration can even cause an increase (in absolute value) of the maximum value of edge compressive stress (compression belt), which is advantageous if, in the absence of the insulating material, this value is considered insufficient.
L’invention concerne également un dispositif de bombage par gravité d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre, comprenant un cadre de bombage par gravité selon l’invention et un four apte à contenir le cadre de bombage et un verre supporté par le cadre, le four comprenant une zone de chauffage du verre apte à le chauffer jusqu’à une température de déformation par gravité, la zone de chauffage comprenant une zone de bombage à l’intérieur de laquelle le verre peut être bombé par gravité. The invention also relates to a device for bending by gravity a glass sheet or several superimposed glass sheets, called glass, comprising a bending frame by gravity according to the invention and a furnace suitable for containing the bending frame and a glass supported by the frame, the furnace comprising a zone for heating the glass suitable for heating it up to a deformation temperature by gravity, the heating zone comprising a bending zone inside which the glass can be bent by gravity.
Notamment, le four comprend après la zone de bombage sur le chemin du verre, une zone de refroidissement apte à procurer au verre un refroidissement contrôlé l’amenant à son figeage, la température ambiante dans la zone de refroidissement étant inférieure à celle dans la zone de bombage, le dispositif comprenant un moyen de convoyage du cadre de bombage supportant un verre apte à le convoyer de la zone de bombage à la zone de refroidissement. In particular, the furnace comprises, after the bending zone on the path of the glass, a cooling zone capable of providing the glass with controlled cooling leading it to freeze, the ambient temperature in the cooling zone being lower than that in the zone. bending, the device comprising means for conveying the bending frame supporting a glass suitable for conveying it from the bending zone to the cooling zone.
Généralement, la zone de refroidissement comprend plusieurs chambres de refroidissement au travers desquelles le cadre supportant un verre est convoyé, la température ambiante des chambres diminuant d’une chambre à l’autre sur le parcours du verre. Le verre est convoyé au travers de la zone de refroidissement contrôlé au moins jusqu’à son figeage lui donnant ses contraintes permanentes de compression et d’extension, c’est-à-dire au moins jusqu’à sa température de strain point. Usually, the cooling zone includes several cooling chambers through which the frame supporting a glass is conveyed, the ambient temperature of the chambers decreasing from one chamber to another along the path of the glass. The glass is conveyed through the controlled cooling zone at least until it freezes, giving it permanent compressive and extension stresses, that is to say at least up to its strain point temperature.
L’invention concerne également un procédé de bombage et de refroidissement d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre, comprenant le chauffage, le bombage par gravité et le refroidissement du verre sur le cadre selon l’invention ou par le dispositif selon l’invention. Lors du bombage à une température de déformation du verre, celui-ci prend, en vue de dessus, une forme concave, notamment en sa zone centrale. La présence du matériau isolant réduit la valeur maximale en valeur absolue de contrainte d’extension en zone périphérique comparé au procédé identique en l’absence de matériau isolant. The invention also relates to a method for bending and cooling a sheet of glass or of several superposed sheets of glass, called glass, comprising heating, bending by gravity and cooling of the glass on the frame according to the invention. or by the device according to the invention. When bending at a deformation temperature of the glass, the latter assumes, in top view, a concave shape, in particular in its central zone. The presence of the insulating material reduces the maximum absolute value of extension stress in the peripheral zone compared to the identical process in the absence of insulating material.
Le cas échéant, la présence du matériau isolant augmente en plus la valeur maximale en valeur absolue de contrainte de compression comparé au procédé identique en l’absence de matériau isolant, cas observable si le matériau isolant est disposé selon l’invention pour faire face à la zone périphérique du verre intérieure à l’anneau formé par la piste de support de la zone périphérique du verre. Brève description des dessins Where appropriate, the presence of the insulating material additionally increases the maximum value in absolute value of compressive stress compared to the identical method in the absence of insulating material, an observable case if the insulating material is arranged according to the invention to cope with the peripheral zone of the lens inside the ring formed by the support track for the peripheral zone of the lens. Brief description of the drawings
- la figure 1 est une vue en coupe qui représente schématiquement un cadre de bombage et de refroidissement supportant un verre, en circulation dans une chambre de refroidissement et qui illustre, selon l’invention, un matériau isolant disposé à l’intérieur du cadre pour faire face à la zone périphérique du verre ; - Figure 1 is a sectional view which schematically shows a bending and cooling frame supporting a glass, circulating in a cooling chamber and which illustrates, according to the invention, an insulating material disposed inside the frame for face the peripheral zone of the glass;
- la figure 2 est une vue en coupe qui, analogue à la figure 1 , représente un cadre de bombage et de refroidissement supportant un verre, en circulation dans une chambre de refroidissement et qui illustre, selon l’art antérieur, un matériau isolant disposé à l’extérieur du cadre pour faire face à la tranche ; - Figure 2 is a sectional view which, similar to Figure 1, shows a bending and cooling frame supporting a glass, circulating in a cooling chamber and which illustrates, according to the prior art, an insulating material disposed outside the frame to face the edge;
- la figure 3 est une vue de dessus qui représente un cadre de bombage selon l’invention du type squelette et qui illustre selon l’invention un matériau isolant en forme de bande disposé à l’intérieur de la piste de support que comprend le cadre ; - Figure 3 is a top view which shows a bending frame according to the invention of the skeleton type and which illustrates according to the invention an insulating material in the form of a strip arranged inside the support track that the frame comprises ;
- la figure 4 est une vue en perspective par en dessous qui représente une partie du cadre de bombage et de refroidissement muni de moyens de support tels qu’une grille et qui illustre lesdits moyens de support formant une infrastructure apte à porter le matériau isolant positionné à l’intérieur de la piste comme sur la figure 1 selon l’invention ; - Figure 4 is a perspective view from below which shows part of the bending and cooling frame provided with support means such as a grid and which illustrates said support means forming an infrastructure suitable for carrying the insulating material positioned inside the track as in Figure 1 according to the invention;
- la figure 5 est un graphique qui représente l’évolution des températures en °C sur la face supérieure du matériau isolant et la face inférieure du matériau isolant en fonction du temps (en secondes) et qui en illustre l’évolution pendant tout le processus de chauffage et de refroidissement du verre, dans le cas d’un matériau isolant placé à l’intérieur du cadre de bombage et de refroidissement comme celui de la figure 1 ; - Figure 5 is a graph which represents the change in temperatures in ° C on the upper face of the insulating material and the lower face of the insulating material as a function of time (in seconds) and which illustrates the change during the entire process heating and cooling the glass, in the case of an insulating material placed inside the bending and cooling frame like that of FIG. 1;
- la figure 6 est un graphique qui représente, sur deux verres différents, l’évolution dans leur zone périphérique des contraintes de bord en MPa en fonction de la distance en mm à partir du bord des verres et en allant vers leur zone centrale afin d’illustrer par comparaison les résultats en l’absence ou en présence d’un matériau isolant à l’intérieur du cadre de bombage et de refroidissement. Description détaillée FIG. 6 is a graph which represents, on two different glasses, the evolution in their peripheral zone of the edge stresses in MPa as a function of the distance in mm from the edge of the glasses and going towards their central zone in order to 'illustrate by comparison the results in the absence or presence of an insulating material within the bending and cooling frame. detailed description
La figure 1 représente schématiquement un cadre de bombage et de refroidissement selon l’invention supportant un verre, en circulation dans une chambre de refroidissement. Le cadre 1 supporte le verre 2 par une piste de support 8, le verre représenté étant déjà bombé. On voit que le verre déborde de la piste de support vers l’extérieur de celle-ci, ce débordement étant généralement compris entre 1 et 12 mm. Le cadre circule dans la chambre de refroidissement selon une direction perpendiculaire à la figure. Cette chambre de refroidissement comprend une sole 3 et une paroi 4. Le matériau isolant 5 est une bande dont une face principale a la forme d’un anneau, et fait face à une partie de la zone périphérique 6 de la face principale inférieure du verre. Le matériau isolant 5 fait écran aux radiations thermiques entre la zone périphérique du verre 6 à l’intérieur de la piste de support du verre et la sole 3. Figure 1 schematically shows a bending and cooling frame according to the invention supporting a glass, circulating in a cooling chamber. The frame 1 supports the glass 2 by a support track 8, the glass shown being already curved. It can be seen that the glass protrudes from the support track towards the outside thereof, this protrusion generally being between 1 and 12 mm. The frame circulates in the cooling chamber in a direction perpendicular to the figure. This cooling chamber comprises a sole 3 and a wall 4. The insulating material 5 is a strip, one main face of which has the shape of a ring, and faces part of the peripheral zone 6 of the lower main face of the glass. . The insulating material 5 shields thermal radiation between the peripheral zone of the lens 6 inside the lens support track and the sole 3.
Avantageusement, le matériau isolant est incliné quand on part de la piste de support du verre pour aller vers la zone centrale du verre, de sorte que sa distance au verre est sensiblement partout la même en fin de bombage. Cette inclinaison pourrait être plus grande encore générant un allongement de la distance entre le matériau isolant et le verre quand on va de la piste de support vers la zone centrale du verre, afin de provoquer un profil de contraintes plus progressif dans le verre entre la zone au-dessus mais à l’extrémité (vers la droite sur la figure) du matériau isolant et la zone juste à côté qui n’est plus au-dessus du matériau isolant. Advantageously, the insulating material is inclined when starting from the lens support track to go towards the central zone of the lens, so that its distance from the lens is substantially the same everywhere at the end of bending. This inclination could be even greater, generating an extension of the distance between the insulating material and the glass when going from the support track towards the central zone of the glass, in order to cause a more progressive stress profile in the glass between the zone. above but at the end (to the right in the figure) of the insulating material and the area immediately beside which is no longer above the insulating material.
La figure 2 représente schématiquement un cadre de bombage et de refroidissement selon une variante de réalisation qui ne fait pas partie de l’invention mais et pouvant, le cas échéant, être combinée avec l’invention notamment illustrée par la figure 1. FIG. 2 schematically represents a bending and cooling frame according to an alternative embodiment which does not form part of the invention but which can, where appropriate, be combined with the invention in particular illustrated by FIG. 1.
Comme sur la figure 1 , le cadre de bombage et de refroidissement selon la figure 2 supporte un verre, en circulation dans une chambre de refroidissement. Le cadre 1 supporte le verre 2 par une piste de support 8, le verre représenté étant déjà bombé. Le cadre circule dans la chambre de refroidissement selon une direction perpendiculaire à la figure. Cette chambre de refroidissement comprend une sole 3 et une paroi 4. Le matériau isolant 5 est une bande dont une face principale fait face à la tranche du verre 7. Ce matériau isolant est disposé à l’extérieur de la piste de support du verre et fait écran aux radiations thermiques entre la tranche du verre 7 et la paroi 4. As in Figure 1, the bending and cooling frame according to Figure 2 supports a glass, circulating in a cooling chamber. The frame 1 supports the glass 2 by a support track 8, the glass shown being already curved. The frame circulates in the cooling chamber in a direction perpendicular to the figure. This cooling chamber comprises a sole 3 and a wall 4. The insulating material 5 is a strip, a main face of which faces the edge of the glass 7. This insulating material is arranged at the outside of the glass support track and shields thermal radiation between the edge of the glass 7 and the wall 4.
La figure 3 représente un cadre de bombage 30 selon l’invention du type squelette en vue de dessus. Sa piste de support 31 du verre est en forme d’anneau. Le matériau isolant 32 est ici une bande disposée à l’intérieur de l’anneau formé par ladite piste pour faire face à une partie de la zone périphérique du verre comprenant dans le verre final des contraintes d’extension. Figure 3 shows a bending frame 30 according to the invention of the skeleton type in top view. Its glass support track 31 is in the shape of a ring. The insulating material 32 is here a strip disposed inside the ring formed by said track to face part of the peripheral zone of the glass comprising in the final glass extension stresses.
La face principale de la bande que l’on voit sur la figure est également en forme d’anneau. Le matériau isolant est disposé ici comme sur la figure 1 par rapport à la piste de support du verre, c’est-à-dire à l’intérieur. La face principale du matériau isolant fait ainsi face à une zone du verre comprise entre ladite piste et une distance de ladite piste vers la zone centrale du verre (qui correspond à la zone centrale 33 du cadre) inférieure à 200 mm. The main side of the band shown in the figure is also ring-shaped. The insulating material is arranged here as in Figure 1 relative to the glass support track, that is to say on the inside. The main face of the insulating material thus faces a zone of the lens between said track and a distance from said track towards the central zone of the lens (which corresponds to the central zone 33 of the frame) of less than 200 mm.
La figure 4 représente vue par en dessous une partie du cadre de bombage et de refroidissement muni de l’infrastructure apte à porter un matériau isolant positionné comme sur la figure 1 selon l’invention. Figure 4 shows a view from below of a portion of the bending and cooling frame provided with the infrastructure suitable for carrying an insulating material positioned as in Figure 1 according to the invention.
Le cadre de bombage et de refroidissement 10 est fixé par des pattes de fixation 11 sur un châssis rigide 12. Des embases 13 en « L » sont fixées sur les pattes de fixation 11 , des branches 14 des embases ayant des directions radiales par rapport au cadre (c’est-à-dire du cadre vers le centre du cadre). Une grille 15 repose sur les branches 14 du « L » des embases. Le matériau isolant selon l’invention (non représenté) repose sur la grille 15. The bending and cooling frame 10 is fixed by fixing lugs 11 on a rigid frame 12. "L" -shaped bases 13 are fixed on the fixing lugs 11, branches 14 of the bases having radial directions with respect to the base. frame (i.e. from the frame to the center of the frame). A grid 15 rests on the branches 14 of the "L" of the bases. The insulating material according to the invention (not shown) rests on the grid 15.
La figure 5 représente l’évolution des températures en °C sur la face supérieure 16 du matériau isolant et la face inférieure 17 du matériau isolant en fonction du temps (en secondes) pendant tout le processus de chauffage et de refroidissement du verre, dans le cas d’un matériau isolant placé à l’intérieur du cadre de bombage et de refroidissement comme celui de la figure 1. FIG. 5 represents the change in temperatures in ° C on the upper face 16 of the insulating material and the lower face 17 of the insulating material as a function of time (in seconds) during the entire process of heating and cooling of the glass, in the case of an insulating material placed inside the bending and cooling frame like that of figure 1.
On remarque que les deux courbes se croisent vers le maximum de température. Lors du refroidissement, la face inférieure 17 du matériau isolant est moins chaude que la face supérieure 16 du matériau isolant. Ceci tient à ce que la face inférieure 17 du matériau isolant fait face à la sole de la chambre de refroidissement qui est plus froide que le verre. La figure 6 compare sur deux verres différents l’évolution dans leur zone périphérique des contraintes de bord en MPa en fonction de la distance en mm à partir du bord des verres et en allant vers leur zone centrale. Note that the two curves intersect towards the maximum temperature. During cooling, the lower face 17 of the insulating material is less hot than the upper face 16 of the insulating material. This is because the lower face 17 of the insulating material faces the bottom of the cooling chamber which is cooler than glass. FIG. 6 compares, on two different glasses, the evolution in their peripheral zone of the edge stresses in MPa as a function of the distance in mm from the edge of the glasses and towards their central zone.
On a représenté le cas 25 de l’absence d’un matériau isolant en tant que référence, et celui 26 pour lequel un matériau isolant a été placé intérieurement au cadre de bombage et de refroidissement comme représenté à la figure 1 , et ce, entre environ 12 mm du bord du verre et 47 mm du bord du verre. There is shown the case 25 of the absence of an insulating material as a reference, and that 26 for which an insulating material has been placed inside the bending and cooling frame as shown in Figure 1, between approximately 12mm from the edge of the glass and 47mm from the edge of the glass.
On voit que les deux verres ont tous deux à leur bord extérieur des contraintes de compression (valeurs négatives) puis, quand on va vers la zone intérieure du verre, des contraintes d’extension (valeurs positives). We see that the two glasses both have at their outer edge compressive stresses (negative values) and then, when we go towards the inner zone of the glass, extension stresses (positive values).
La présence du matériau isolant tend ici à augmenter la valeur maximale (27, 28) de contrainte de compression (en valeur absolue, puisque la valeur maximale est celle la plus négative sur l’axe des ordonnées de la figure 6) et à diminuer la valeur du maximum (29, 30) de contrainte d’extension (en valeur absolue). The presence of the insulating material tends here to increase the maximum value (27, 28) of compressive stress (in absolute value, since the maximum value is the most negative on the y-axis of figure 6) and to decrease the value of the maximum (29, 30) of extension constraint (in absolute value).

Claims

REVENDICATIONS
1. Cadre (1 , 10, 30) de bombage par gravité d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre (2), comprenant une piste de support (8, 31) de la zone périphérique (6) du verre, ladite piste (8, 31) étant en forme d’anneau vue de dessus, et comprenant un matériau isolant (5, 32) disposé pour faire face à la zone périphérique (6) du verre intérieure à l’anneau formé par ladite piste (8, 31). 1. Frame (1, 10, 30) for bending by gravity a sheet of glass or of several superimposed sheets of glass, called the glass (2), comprising a support track (8, 31) of the peripheral zone ( 6) glass, said track (8, 31) being in the form of a ring seen from above, and comprising an insulating material (5, 32) arranged to face the peripheral zone (6) of the glass inside the ring formed by said track (8, 31).
2. Cadre selon la revendication précédente, caractérisé en ce que le matériau isolant (5, 32) comprend des fibres réfractaires, notamment métalliques. 2. Frame according to the preceding claim, characterized in that the insulating material (5, 32) comprises refractory fibers, in particular metallic.
3. Cadre selon l’une des revendications précédentes, caractérisé en ce que le matériau isolant (5, 32) présente une densité surfacique comprise entre 1000 et 1800 g/m2, notamment entre 1200 et 1500 g/m2. 3. Frame according to one of the preceding claims, characterized in that the insulating material (5, 32) has a surface density of between 1000 and 1800 g / m 2 , in particular between 1200 and 1500 g / m 2 .
4. Cadre selon l’une des revendications précédentes, caractérisé en ce que le matériau isolant (5, 32) est une bande dont une face principale est orientée vers le verre (2). 4. Frame according to one of the preceding claims, characterized in that the insulating material (5, 32) is a strip, one main face of which is oriented towards the glass (2).
5. Cadre selon la revendication précédente, caractérisé en ce que le matériau isolant (5, 32) présente une épaisseur comprise dans le domaine allant de 0,3 à 5 mm, notamment de 0,3 à 2 mm. 5. Frame according to the preceding claim, characterized in that the insulating material (5, 32) has a thickness in the range from 0.3 to 5 mm, in particular from 0.3 to 2 mm.
6. Cadre selon l’une des deux revendications précédentes, caractérisé en ce que le matériau isolant (5, 32) est placé à l’intérieur de l’anneau formé par la piste de support (8, 31 ) du verre (2) pour que l’une de ses faces principales soit face à une zone du verre comprise entre ladite piste de support (8, 31) et une distance de ladite piste vers la zone centrale du verre inférieure à 200 mm. 6. Frame according to one of the two preceding claims, characterized in that the insulating material (5, 32) is placed inside the ring formed by the support track (8, 31) of the glass (2) so that one of its main faces faces a zone of the lens comprised between said support track (8, 31) and a distance from said track towards the central region of the lens of less than 200 mm.
7. Cadre selon l’une des revendications précédentes, caractérisé en ce que le matériau isolant (5, 32) est fixé sur un support (15), notamment du type grille ou toile tissée, notamment du type monofil, plus rigide que le matériau isolant, ledit support du matériau isolant (5, 32) étant relié au cadre (1, 10, 30) de bombage. 7. Frame according to one of the preceding claims, characterized in that the insulating material (5, 32) is fixed on a support (15), in particular of the grid or woven fabric type, in particular of the monofilament type, more rigid than the material. insulating, said support of the insulating material (5, 32) being connected to the bending frame (1, 10, 30).
8. Cadre selon l’une des revendications précédentes, caractérisé en ce que le matériau isolant (5, 32) est disposé de manière que sa face supérieure soit inclinée vers l’intérieur du cadre, la distance entre le matériau isolant et le verre augmentant avec la distance vers l’intérieur du cadre (1 , 10, 30). 8. Frame according to one of the preceding claims, characterized in that the insulating material (5, 32) is arranged so that its upper face is inclined towards the inside of the frame, the distance between the insulating material and the glass increasing. with the distance towards the inside of the frame (1, 10, 30).
9. Cadre selon l’une des revendications précédentes, caractérisé en ce qu’il comprend un squelette comprenant une bande métallique dont une tranche est orientée vers le haut, ladite tranche formant la piste de support (8, 31) du verre (2), ou un matériau comprenant des fibres réfractaires recouvrant ladite tranche de la bande métallique pour former la piste de support (8, 31 ) du verre (2). 9. Frame according to one of the preceding claims, characterized in that it comprises a skeleton comprising a metal strip, one edge of which is facing upwards, said wafer forming the support track (8, 31) of the glass (2), or a material comprising refractory fibers covering said wafer of the metal strip to form the support track (8, 31) of the glass (2).
10. Cadre selon l’une des revendications précédentes, caractérisé en ce que la piste de support (8, 31 ) du verre (2) a une largeur comprise dans le domaine allant de 2 à 10 mm. 10. Frame according to one of the preceding claims, characterized in that the support track (8, 31) of the glass (2) has a width in the range from 2 to 10 mm.
11. Dispositif de bombage par gravité d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre (2), comprenant un cadre (1 , 10, 30) de bombage par gravité de l’une des revendications précédentes et un four apte à contenir le cadre (1 , 10, 30) de bombage et un verre (2) supporté par le cadre (1 , 10, 30), le four comprenant une zone de chauffage du verre apte à le chauffer jusqu’à une température de déformation par gravité, la zone de chauffage comprenant une zone de bombage à l’intérieur de laquelle le verre (2) peut être bombé par gravité. 11. Device for bending by gravity of a glass sheet or of several superimposed glass sheets, called the glass (2), comprising a frame (1, 10, 30) for bending by gravity of one of the preceding claims and a furnace capable of containing the bending frame (1, 10, 30) and a glass (2) supported by the frame (1, 10, 30), the furnace comprising a heating zone of the glass capable of heating it up to a deformation temperature by gravity, the heating zone comprising a bending zone inside which the glass (2) can be bent by gravity.
12. Dispositif selon la revendication précédente, caractérisé en ce que le four comprend une zone de refroidissement apte à procurer au verre (2) un refroidissement contrôlé l’amenant à son figeage, la température ambiante dans la zone de refroidissement étant inférieure à celle dans la zone de bombage, le dispositif comprenant un moyen de convoyage du cadre (1 , 10, 30) de bombage supportant un verre (2) apte à le convoyer de la zone de bombage à la zone de refroidissement. 12. Device according to the preceding claim, characterized in that the furnace comprises a cooling zone capable of providing the glass (2) with a controlled cooling causing it to freeze, the ambient temperature in the cooling zone being lower than that in the bending zone, the device comprising means for conveying the bending frame (1, 10, 30) supporting a lens (2) capable of conveying it from the bending zone to the cooling zone.
13. Dispositif selon la revendication précédente, caractérisé en ce que la zone de refroidissement comprend plusieurs chambres de refroidissement au travers desquelles le cadre (1 , 10, 30) supportant un verre (2) peut être convoyé, la température ambiante des chambres diminuant d’une chambre à l’autre sur le parcours du verre. 13. Device according to the preceding claim, characterized in that the cooling zone comprises several cooling chambers through which the frame (1, 10, 30) supporting a glass (2) can be conveyed, the ambient temperature of the chambers decreasing d 'one room to another on the glass path.
14. Procédé de bombage par gravité et de refroidissement d’une feuille de verre ou de plusieurs feuilles de verre superposées, dit le verre, comprenant le chauffage, le bombage par gravité et le refroidissement du verre (2) sur le cadre (1 , 10, 30) ou par le dispositif de l’une des revendications précédentes. 14. Method of gravity bending and cooling of a glass sheet or of several superimposed glass sheets, called glass, comprising heating, gravity bending and cooling of the glass (2) on the frame (1, 10, 30) or by the device of one of the preceding claims.
15. Procédé selon l’une des revendications précédentes de procédé, caractérisé en ce que pendant le bombage et le refroidissement, le verre (2) déborde de la piste de support (8, 31) d’une distance comprise dans le domaine allant de 1 à 12 mm. 15. Method according to one of the preceding method claims, characterized in that during the bending and cooling, the glass (2) protrudes from the support track (8, 31) by a distance within the range of 1 to 12 mm.
PCT/EP2021/067282 2020-06-29 2021-06-24 Frame for bending sheets of glass with reduced tensile stress WO2022002736A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202180003876.XA CN114206462A (en) 2020-06-29 2021-06-24 Frame for bending glass sheets with reduced tensile stress

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FRFR2006812 2020-06-29
FR2006812A FR3111889A1 (en) 2020-06-29 2020-06-29 Bending frame of glass sheets with reduced strain

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WO2022002736A1 true WO2022002736A1 (en) 2022-01-06

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FR (1) FR3111889A1 (en)
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CN114620927A (en) * 2022-03-15 2022-06-14 福耀集团（上海）汽车玻璃有限公司 Annealing device for reducing tensile stress of glass edge

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WO1994017997A1 (en) 1993-02-09 1994-08-18 Glasstech, Inc. Apparatus and method for controlling stresses in laminated automotive glass
US5591245A (en) 1990-11-01 1997-01-07 Tamglass Engineering Oy Method and apparatus for developing and edge stress in a windshield in a windshield bending furnace
US5865866A (en) * 1995-08-02 1999-02-02 Glasstech, Inc. Method for controlling stresses in a formed glass sheet
US20130305787A1 (en) * 2011-12-22 2013-11-21 Sunpower Corporation Heat-regulating glass bending apparatus and method
WO2016085612A1 (en) 2014-11-24 2016-06-02 Glasstech, Inc. Glass sheet forming and annealing providing edge stress control
WO2019077278A1 (en) 2017-10-19 2019-04-25 Saint-Gobain Glass France Gravity-bending glass in the presence of a radiative counter-frame

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Publication number Priority date Publication date Assignee Title
US5591245A (en) 1990-11-01 1997-01-07 Tamglass Engineering Oy Method and apparatus for developing and edge stress in a windshield in a windshield bending furnace
WO1994017997A1 (en) 1993-02-09 1994-08-18 Glasstech, Inc. Apparatus and method for controlling stresses in laminated automotive glass
US5865866A (en) * 1995-08-02 1999-02-02 Glasstech, Inc. Method for controlling stresses in a formed glass sheet
US20130305787A1 (en) * 2011-12-22 2013-11-21 Sunpower Corporation Heat-regulating glass bending apparatus and method
WO2016085612A1 (en) 2014-11-24 2016-06-02 Glasstech, Inc. Glass sheet forming and annealing providing edge stress control
WO2019077278A1 (en) 2017-10-19 2019-04-25 Saint-Gobain Glass France Gravity-bending glass in the presence of a radiative counter-frame

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114620927A (en) * 2022-03-15 2022-06-14 福耀集团（上海）汽车玻璃有限公司 Annealing device for reducing tensile stress of glass edge
CN114620927B (en) * 2022-03-15 2023-09-08 福耀集团（上海）汽车玻璃有限公司 Annealing device for reducing tensile stress of glass edge

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CN114206462A (en) 2022-03-18
FR3111889A1 (en) 2021-12-31

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