Manufacture of laminated glazing

Abstract

A process for manufacturing a bent laminated glazing, includes manufacturing a first bent laminated glazing including at least two glass substrates locally comprising, in each of the at least two glass substrates and facing each other in all the at least two glass substrates, a zone including compressive stresses, and cutting the first bent laminated glazing through its entire thickness along a line included in the zone in order to form local cut edges and, after cutting, a second bent laminated glazing with the local cut edges having compressive edge stresses.

Claims

1. A process for manufacturing a bent laminated glazing, comprising: manufacturing a first bent laminated glazing comprising first and second glass substrates that are laminated to each other, the first bent laminated glazing having a peripheral edge with first compressive edge stresses, each of the first and second glass substrates comprising a local zone comprising second compressive stresses and extending outside the peripheral edge with the first compressive edge stresses, the local zone of the first glass substrate facing and being superposed with the local zone of the second glass substrate, and after manufacturing said first bent laminated glazing, cutting said first bent laminated glazing through its entire thickness along a line included in said local zone of each of the first and second glass substrates in order to form local cut edges having second compressive edge stresses outside the peripheral edge with first compressive edge stresses, the cutting of said first bent laminated glazing producing a second bent laminated glazing having said peripheral edge with the first compressive edge stresses and said local cut edges having the second compressive edge stresses, wherein the local zone in each of the first and second glass substrates that comprises the second compressive stresses is formed by applying a local cooling on the first and second glass substrates to introduce the second compressive stresses in each local zone, said local cooling being a faster cooling process than a general cooling of the first and second glass substrates that introduces the first compressive edge stresses.

2. The process according to claim 1, wherein the second compressive edge stresses of the local cut edges are greater than 4 MPa.

3. The process according to claim 2, wherein the second compressive edge stresses of the local cut edges are greater than 8 MPa.

4. The process according to claim 1, wherein the local cut edges form a notch in the second bent laminated glazing.

5. The process according to claim 1, wherein the local cut edges form an orifice in the second bent laminated glazing.

6. The process according to claim 5, wherein the local cut edges form a sunroof opening.

7. The process according to claim 5, wherein the local cut edges form an opening in a rear window of a motor vehicle.

8. The process according to claim 1, wherein the local zone in the first bent laminated glazing is devoid of an orifice.

9. The process according to claim 1, wherein each local zone has an area between 0.5 cm.sup.2 and 70 cm.sup.2.

10. The process according to claim 1, wherein, in said cutting of the first laminated glazing, said line extends from one external edge to another external edge of the first laminated glazing.

11. The process according to claim 1, wherein the cutting is obtained by a hole saw, a router or a water jet.

12. The process according to claim 1, wherein the first and second glass substrates of the first bent laminated glazing are bent by pressing and/or suction applied to the glass substrates individually.

13. The process according to claim 1, wherein the local cut edges form an orifice and the second compressive edge stresses of the local cut edges are greater than 4 MPa.

14. The process according to claim 13, wherein the local zone in the first bent laminated glazing is devoid of an orifice.

15. The process according to claim 13, wherein the local zone in the first bent laminated glazing is devoid of an orifice and the local zone has an area between 0.5 cm.sup.2 and 70 cm.sup.2.

16. The process according to claim 1, wherein the local cut edges form an orifice and the second compressive edge stresses of the local cut edges are greater than 8 MPa.

17. The process according to claim 16, wherein the local zone in the first bent laminated glazing is devoid of an orifice.

18. The process according to claim 16, wherein the local zone in the first bent laminated glazing is devoid of an orifice and the local zone has an area between 0.5 cm.sup.2 and 70 cm.sup.2.

19. A process for manufacturing a bent laminated glazing, comprising: manufacturing a first bent laminated glazing comprising first and second glass substrates that are laminated to each other, the first bent laminated glazing having a peripheral edge with first compressive edge stresses, each of the first and second glass substrates comprising a local zone comprising second compressive stresses and a periphery of the local zones being entirely surrounded by the peripheral edge of the first bent laminated glazing, the local zone of the first glass substrate facing and being superposed with the local zone of the second glass substrate, and after manufacturing said first bent laminated glazing, cutting said first bent laminated glazing along a line included in said local zone and entirely surrounded by the peripheral edge of the first bent laminated glazing in order to form local cut edges having second compressive edge stresses outside the peripheral edge with first compressive edge stresses, the cutting of said first bent laminated glazing producing a second bent laminated glazing having said peripheral edge with the first compressive edge stresses and said local cut edges having the second compressive edge stresses, wherein the local zone in each of the first and second glass substrates that comprises the second compressive stresses is formed by applying a local cooling on the first and second glass substrates to introduce the second compressive stresses in each local zone, said local cooling being a faster cooling process than a general cooling of the first and second glass substrates that introduces the first compressive edge stresses.

Description

(1) The present invention is now described with the aid of purely illustrative examples that in no way limit the scope of the invention, and using the appended illustrations, in which:

(2) FIG. 1 represents a partial schematic cross-sectional view of laminated glazing obtained according to the process of the invention;

(3) FIG. 2 is a variant of FIG. 1;

(4) FIGS. 3a to 3i are various exemplary embodiments of geometric shapes of localized controlled cooling;

(5) FIG. 4 is a schematic partial cross-sectional view of a device for local controlled cooling by blowing applied to the surface of the glass;

(6) FIGS. 5a and 5b represent a motor vehicle roof panel comprising laminated glazing according to the invention in two portions acting as an opening sunroof, one portion of said glazing being fixed, the other being mobile;

(7) FIG. 6 illustrates laminated glazing comprising orifices or zones of compressive stresses enabling the drilling of orifices;

(8) FIG. 7 is a schematic partial cross-sectional view of a local controlled cooling device that comes into contact with the surface of the glass;

(9) FIG. 8 represents a motor vehicle roof seen perpendicular to one of its main faces and comprising a border of compression and four local zones of compressive stress joining the border, said local zones being ready to receive orifices.

(10) FIG. 1 illustrates a partial cross-sectional view of laminated glazing 1 comprising at least, depending on its thickness, one cut-away portion 2. The glazing comprises at least two glass sheets or substrates 10 and 12, and an interlayer or intermediate sheet 11 made of polymer material arranged between said glass substrates. After manufacture, the glazing has the cut-away portion 2 obtained by drilling of the two glass substrates and of the interlayer, after the assembly thereof. The orifice obtained in the first substrate has a contour 20 while the other orifice in the second substrate has a contour 21. According to the manufacturing process of the invention: The two contours 20 and 21 are perfectly superposed; according to the cross-sectional view, the edges of the substrates over the entire periphery of the contours are perfectly aligned; of course, if the drilling is carried out simultaneously from the two main faces of the glazing, it is advisable to ensure the alignment of the drilling tools on either side of the glazing. In particular, water-jet cutting can be carried out from a single side of the laminated glazing. The contours 20 and 21 both have compressive edge stresses of greater than 4 MPa, and preferably of greater than 8 MPa.

(11) The orifices of the substrates may be shaped depending on the application. For example, FIG. 2 shows the recess 2 with chamfers 23 and 24 on each of the outer edges of the two contours 25 and 26. The recess 2 has dimensions adapted to the application that is made thereof. This recess is used, for example, to fasten a functional or aesthetic part such as an antenna, a fan, a trim, or is used as a passage for a cable, etc. If it is of large dimensions, this recess may constitute the opening of a glass opening sunroof for a vehicle, in particular for a motor vehicle.

(12) The process for manufacturing the glazing comprises various steps which will be successively described. The individual glass substrates 10 and 12 are first cut along their outer edges by a standard method for cutting glass in order to provide substrates having the desired external peripheral shapes, according to the cutting of primitives, the cutting to shape, the break-out thereof and the optional shaping thereof. One or more optional additional steps of screen printing may be carried out, depending on the application. On the production line, many substrates are thus prepared on the run. Then, with the substrates running on the production line, a step of pairing is carried out. The substrates 10 and 12 are combined together by superposition. The superposed substrates are then bent together to the desired shape by the chosen bending process. The superposition of the glass substrates for this bending step makes it possible to obtain glasses having perfectly coincident general shapes. According to the invention, a step of general and local controlled cooling is then carried out. The local cooling is generated on at least one zone of a peripheral face of the side-by-side substrates corresponding at least to the zone which will be cut at the end of the process. The objective of the local controlled cooling is to obtain compression zones in the thickness of the glazing at the cut edges.

(13) The localization of the cooling in the zones intended to be cut targets both surfaces and contours. The localized cooling may in particular be carried out along a simple line crossing the glazing from one edge to another edge, or even from one edge to the same edge. FIGS. 3a to 3i illustrate nonlimiting exemplary embodiments of local controlled coolings over zones with various shapes.

(14) FIG. 3a presents a local compression zone in the form of a closed circular contour and having a surface (hatched surface) delimited by this circle, making it possible for example to obtain the glazing from FIG. 1.

(15) FIG. 3b shows several local surface compressive zones that are independent of one another.

(16) FIG. 3c illustrates a local compression zone that is in the form of a single closed contour, the interior of the contour not being part of said zone.

(17) FIG. 3d shows a local compression zone in the form of a curved line reaching the edge of the glazing at only one of its ends.

(18) FIG. 3e illustrates a local compression zone in the form of a closed loop and having a curved line going from this loop to the edge of the glazing.

(19) FIG. 3f shows a local compression zone in the shape of a curved line starting from one edge of the glazing and reaching the opposite edge (the line could also return to an edge adjacent to the starting edge).

(20) It is also possible to connect independent local compression zones using one or more lines that may or may not reach the edge of the glazing, as illustrated in FIG. 3g.

(21) FIGS. 3h and 3i show a compression surface beginning from one edge of the glazing forming a specific notch and reaching the same edge of the glazing.

(22) FIG. 4 illustrates a schematic device 3 suitable for blowing onto one of the sides of the side-by-side substrates. Here, air is blown at ambient temperature over a disk-shaped area as shown by FIG. 3a, with a view to subsequently producing the recess from FIGS. 1 and 2. The blowing time is between 40 and 90 seconds approximately. The blowing duration is independent of the surface area to be cooled in a differentiated manner but, on the other hand, depends on the thickness of the glass. The 40 seconds of local cooling are established for substrates each having a thickness of 2.1 mm. The blowing nozzle has an ending with a shape adapted to the geometric shape of the local zone of compressive stresses to be obtained. It may in particular have the shape of a rectangular contour for a recess of relatively large dimension such as that targeting an opening sunroof application. In FIG. 4, the nozzle 3 comprises a central air supply duct 30, an axially symmetric duct 31, around the central supply duct 30. The duct 31 opens, as ending of the nozzle, into a cylindrical bell 33, the wall of which is constituted of a flexible felt based on metal fibers. The free end 34 of the bell is put against the surface of the glass. Cold air is conveyed via the supply duct 30 to the bell 34 in order to be released against the surface of the glass to be cooled then discharged via the duct 31. After the cooling, the de-pairing (the dissociation) of the two substrates 10 and 12 is carried out. Then, the steps of assembling with the interlayer 12, of degassing the assembly and of passing into an autoclave are carried out in the standard manner. This treatment leads to bonding between the interlayer and the glass substrates on each side of the interlayer. Finally, the cutting of the glazing is carried out over the zone that has undergone local cooling in order to obtain the desired cut-away portion or portions (by diamond hole saw, diamond router, water jets, etc.).

(23) FIGS. 5a and 5b illustrate a motor vehicle roof 40 comprising laminated glazing according to the invention that acts as an opening sunroof, said glazing being in two portions 41 and 42, one portion 41 of said glazing being fixed with respect to the vehicle, the other portion 42 being mobile. In FIG. 5a), the roof is closed. In FIG. 5b), the roof is open owing to the movement of the portion 42 only (arrow) which comes above the body enclosed in the roof panel of the vehicle. According to the invention, firstly a single laminated glazing was manufactured initially comprising the two portions 41 and 42 not yet cut. According to the invention, a local zone of compressive stresses was created at the location where this glazing was to be cut in a line crossing it completely (line having given rise to the edges 44 and 45 after cutting). The cutting according to the invention was carried out on this line and led to the portions 41 and 42 that are completely independent but for which the edges 44 and 45 are perfectly coincident when the roof is closed (FIG. 5a)).

(24) FIG. 6 represents glazing 1 made of laminated glass. The four hatched disks 2 represent either orifices or local zones of compressive stresses enabling the drilling of orifices. These orifices or local zones of compressive stresses are here completely within a main face 3 of the glazing without sticking out over the outer edge of the glazing (as is the case for a notch). The orifices are placed symmetrically with respect to the plane of symmetry 4 passing through the middle 5 of the front strip 6 and the middle 7 of the rear strip 8 of the panel 1.

(25) FIG. 7 illustrates a schematic device 70 suitable for cooling, via conduction, a local zone through a main face of a stack of two side-by-side substrates 73 and 74. A metal pipe 71, closed at its lower end, has cold air running through it as indicated by the arrows. The contact with the glass between the metal pipe and the glass is softened owing to a felt 72 made of refractory fibers in order to reduce the risk of breakage by thermal shock. This thus results in the formation of a local zone of compressive stresses at the location of the contact between the felt 72 and the glass.

(26) FIG. 8 represents a motor vehicle roof comprising laminated glazing, seen perpendicular to one of the main faces 81. This laminated glazing comprises two transverse edges 87 and 88 and two longitudinal edges 89 and 90. It comprises a border 82 of compressive edge stresses going completely around the glazing. The longitudinal median plane AA′ (perpendicular to the figure) is a plane of symmetry of the glazing and is perpendicular to the transverse edges 87 and 88 which are opposite one another. Within the border of compressive edge stresses are four local zones of compressive stresses 83, 84, 85, 86. These local zones here meet the border. These compression zones are represented by hatching but in reality they are not visible to the naked eye. The local zones 83 and 84 are placed symmetrically one opposite the other with respect to the plane of symmetry AA′. The local zones 85 and 86 are placed symmetrically opposite one another with respect to the plane of symmetry AA′. These local zones offer the possibility of drilling orifices through the laminated glazing for the passage of roof bar fastening components. Two roof bars may be fastened, either parallel to the plane of symmetry AA′ between the points 83 and 85 for one and between the points 84 and 86 for the other, or perpendicular to the plane of symmetry AA′, between the points 83 and 84 for one and between the points 85 and 86 for the other.