METHOD FOR BREAKING OUT A SHEET OF GLASS

Abstract

A method for breaking out a sheet of glass includes tracing a score line on a first face of the sheet of glass, the score line delimiting an exterior part and an interior part of the sheet of glass, positioning a support facing the score line on the side of the sheet of glass opposite to the first face, and breaking out by simultaneous application of at least a first force on the exterior part of the sheet of glass and of at least a second force on the interior part of the sheet of glass.

Claims

1. A method for breaking out a sheet of glass, comprising: tracing a score line on a first face of the sheet of glass, the score line delimiting an exterior part and an interior part of the sheet of glass, positioning a support facing said score line on the side of the sheet of glass opposite to said first face, and breaking out by simultaneous application of at least a first force on the exterior part of the sheet of glass and of at least a second force on the interior part of the sheet of glass.

2. The method as claimed in claim 1, wherein the support is designed to allow the exterior part to bend under the effect of the first force.

3. The method as claimed in claim 1, wherein at least a useful portion of the exterior part is situated with an overhang with respect to the support.

4. The method as claimed in claim 1, wherein the first force is applied to the exterior part at least at one first point and the second force is simultaneously applied to the interior part at least at one second point, the first and second points being situated facing one another on either side of the score line.

5. The method as claimed in claim 1, wherein the second force is chosen so that a curvature of the surface of the glass is highest at the score line.

6. The method as claimed in claim 1, wherein the second force is applied to a zone situated at a distance from the score line comprised between 3 and 30 millimeters.

7. The method as claimed in claim 1, wherein the second force is a local pressure force.

8. The method as claimed in claim 7, wherein the breaking-out is performed by moving, along the score line, a single breaking-out tool equipped with a first local pressure head and with a second local pressure head, the first and second local pressure heads being arranged on either side of the score line, the first local pressure head forming a means for applying the first force and the second local pressure head forming a means for applying the second force.

9. The method as claimed in claim 1, wherein the second force is a planar pressure force.

10. The method as claimed in claim 1, wherein the second force is a suction force.

11. The method as claimed in claim 1, wherein the support is arranged to allow the interior part of the sheet of glass to bend under the effect of the second force.

12. The method as claimed in claim 1, wherein the first force is moved over the sheet of glass, along the score line.

13. The method as claimed in claim 1, wherein the second force is moved over the sheet of glass, along the score line.

14. The method as claimed in claim 1, wherein the second force is fixed.

15. The method as claimed in claim 1, wherein the support has an internal edge and an external edge which are situated facing the sheet of glass and respectively on either side of the score line.

16. The method as claimed in claim 1, wherein the support forms a frame defining a closed contour corresponding to the trace of the score line.

17. The method as claimed in claim 1, wherein the support extends continuously over the entire length of the score line.

18. The method as claimed in claim 1, wherein the support extends over a restricted portion of the score line.

19. The method as claimed in claim 1, wherein protection means are interposed between the sheet of glass and the support.

20. The method as claimed in claim 1, wherein the sheet of glass has a thickness less than or equal to 1 mm.

Description

[0048] The invention will be better understood from reading the following description given solely by way of nonlimiting example and with reference to the attached figures:

[0049] FIGS. 1a to 1d schematically illustrate various steps in a method for breaking out a sheet of glass,

[0050] FIGS. 2a and 2b are cross-sectional diagrams of the breaking-out of a sheet of glass,

[0051] FIG. 3 illustrates the step of breaking out a sheet of glass according to the method of the invention,

[0052] FIG. 4 illustrates a plan view of the sheet of glass placed on a breaking-out support according to a first embodiment of the invention,

[0053] FIG. 5 is a schematic view in section on V of FIG. 4, prior to breakout,

[0054] FIG. 6 is a schematic view on section on VI of FIG. 4, illustrating the breaking-out step using a breaking-out tool according to the invention,

[0055] FIG. 7 illustrates a plan view of a sheet of glass arranged on a break-out support according to a second embodiment of the invention,

[0056] FIG. 8 illustrates a plan view of a sheet of glass arranged on a breaking-out support according to a third embodiment of the invention,

[0057] FIG. 9 is a schematic view in cross section on IX of FIG. 8, illustrating the breaking-out step,

[0058] FIG. 10 illustrates a fourth embodiment of the invention,

[0059] FIG. 11 illustrates a fifth embodiment of the invention.

[0060] A first embodiment of the method according to the invention is described hereinbelow in connection with FIGS. 3 to 6, for breaking out glazing of complex shape, particularly automotive glazing such as a windshield.

[0061] A first step in the method, which step is illustrated in FIG. 3, is to provide a planar sheet of glass 10, in this instance of rectangular shape, and to trace a score line 12 on a first face 10a of this sheet of glass 10 (see FIG. 5, upper face of the sheet of glass).

[0062] The score line 12 delimits, in a direction orthogonal to the score line 12, an exterior part 16 and an interior part 14 of the sheet of glass, the interior part 14 corresponding—in this example—to the contour of the glazing that is to be cut out.

[0063] In the known way, additional scores in the form of—generally straight-line —segments 18a, 18b, 18c, 18d are also made in the exterior part 16.

[0064] The score line 12 and the additional lines 18a, 18b, 18c, 18d are fissures intended to allow breaking out along this (these) line(s) during the breaking-out step. They are therefore partial cuts, i.e. through only part of the thickness of the sheet of glass.

[0065] In the usual way, this step is performed on a scoring table 20 to which the sheet of glass 10 is generally conveyed using a conveyor belt 22.

[0066] In the example, the score line 12 and the additional lines 18a, 18b, 18c, 18d are traced by means of a device 24 comprising a glass-cutting wheel, secured to an axle able to be moved translationally in two directions X, Y which are parallel to the sheet of glass, and pivoted about an axis Z perpendicular thereto (FIG. 3).

[0067] However, as an alternative, the scoring may be performed using any other suitable scoring instrument, such as, for example, a laser.

[0068] For breaking out, the sheet of glass 10 is placed on an essentially incompressible breaking-out support 30 in the form of a sheet or equivalent, for example made of metal, generally supported by a breaking-out table. As illustrated in FIG. 5, the second face 10b of the sheet of glass (the lower face) is then the one facing toward the support 30 and toward the breaking-out table supporting this support.

[0069] Advantageously, the sheet of glass 10 is placed on the support 30 via interposed protective means intended to preserve the sheet of glass at the time of breakout.

[0070] In the example, the breaking-out table and the scoring table are the one same table 20. The protective means here comprise the conveyor belt 22, for example made of polyester fabric reinforced rubber, which moves the sheet along the production line. The breaking-out support 30 is therefore placed underneath the sheet of glass 10 right from the scoring step. However, in other instances, the scoring and breaking-out steps are performed at different workstations of the production line or the breaking-out support 30 is interposed between the sheet of glass 10 and the table 20 after scoring and before breaking-out.

[0071] In the first embodiment illustrated in FIG. 4, the breaking-out support 30 is a fixed support extending over the entire length of the score line 12.

[0072] It takes the form of a frame defining a closed contour, the shape of which is corresponds to the contour of the glazing to be cut out. Bounded laterally by an external edge 30a and an internal edge 30b, the support 30 is positioned facing the score line 12 and facing a portion 16b of the exterior part 16 and facing a portion 14b of the interior part 14 of the sheet of glass, which portions are contiguous with the score line 12. It is generally recommended for the support to extent on either side of the score line over a distance da, db respectively, typically equal to at least 3 millimeters.

[0073] The support 30 allows the exterior part 16 of the sheet of glass 10 to bend downward (i.e. toward the breaking-out table).

[0074] In order to do this, as illustrated in FIG. 5, a useful portion 16a of the exterior part 16 is situated at an overhang with respect to the support. On the other side, a useful portion 14a of the interior part extends beyond the support 30. Functionally, and taking the flexibility of glass into account, everything happens as if the useful portion 14a were at an overhang with respect to the support 30.

[0075] The breaking-out, illustrated in FIG. 6, is performed by a technique of subjecting the sheet of glass 10 to bending, inducing tensile load in the glass at the score line 12.

[0076] According to the invention, two forces F1 and F2 are applied simultaneously to the sheet of glass 10 in a direction orthogonal to said sheet and downward.

[0077] A first force F1 is applied to the useful portion 16a of the exterior part 16.

[0078] A second force F2 is applied to the useful portion 14a of the interior part 14, near the score line 12, generally to a zone situated at a distance d from the score line 12 comprised between 3 and 30 millimeters, preferably between 5 and 25 millimeters, more preferably still, between 5 and 15 millimeters, in a direction orthogonal to said line.

[0079] In the (nonlimiting) embodiment illustrated, the first and second forces F1 and F2 are applied using a single tool 40 having two pressure heads 41, 42. Each head 41, 42 for example comprises a ball 44 urged elastically toward the first face 10a of the sheet of glass 10 by a pneumatic system 46 that manages the breaking-out pressure ensuring contact between the ball and the glass, or by any other suitable system, possibly a spring. Each ball 44 presses locally at a point P1, P2 of the sheet of glass respectively. Note that, as an alternative, the tool may have wheels in place of the balls 44.

[0080] The tool 40 is intended to be moved continuously along the score line 12 so as to cause the fissure in the glass to spread progressively along the entire score line 12. Note that it is generally necessary, for complex shapes, for the tool to be able to be moved in two perpendicular directions X, Y and in rotation about an axis Z orthogonal to X, Y, so that the axis connecting the two heads remains substantially perpendicular to the score line throughout the movement.

[0081] As illustrated in FIG. 6, under the effect of the first and second forces F1, F2 respectively, the exterior 16 and interior 14 parts bend downward.

[0082] The simultaneous application of the first and second force F2 increases the bending moment applied to the surface of the glass at the score line 12, ensuring a clean break (FIG. 6).

[0083] Advantageously, the point P2 of application of the second force F2 and the intensity of this force are chosen so that the curvature of the surface of the glass is highest at the score line.

[0084] FIG. 7 illustrates a second embodiment.

[0085] Only the form of the break-out support 30 differs from the first embodiment. The other features described hereinabove are therefore not repeated a further time.

[0086] According to this second embodiment, the break-out support 30 is a local support of the block type, which extends over only a section of the score line 12, in the longitudinal direction of said line. The dimensions of its surface intended to face the sheet of glass 10 are for example comprised between 5 and 15 cm.

[0087] In the example, the local support 30 is mobile: in order to spread the fissure along the score line 12, the support 30 is for example moved opposite the score line 12 at the same time and in the same way as the means for applying the forces F1 and F2, notably so that the points of application of the forces F1 and F2 and the support 30 remain aligned orthogonally to the score line 12.

[0088] Note that according to an alternative form, the local support 30 could also be fixed. In that case, it is generally necessary to fit several blocks individually along the score line 12 in order to ensure that the fissure spreads correctly all around the contour of the shape.

[0089] FIGS. 8 and 9 illustrate a third embodiment.

[0090] As illustrated in FIG. 8, the break-out support 30 here has the form of a solid plate supporting the interior part 14 of the sheet of glass 10 over its entire extent, as well as a portion of the exterior part 16 which is contiguous with the score line, only a peripheral useful portion 16a of the exterior part 16 of the sheet of glass finding itself overhanging relative to the support 30.

[0091] According to the invention, a first force F1 is applied to the useful portion 16a of the exterior part 16, and a second force F2 is applied to the interior part 14, near the score line 12.

[0092] The deformation of the sheet of glass as a result of the application of F1 and of the flexibility of the glass is prevented in places at which this second force F2 is applied. In these places, the sheet of glass 10 remains substantially parallel to the scoring table 20 and to the support 30. In fact, the bending moment applied to the surface of the glass is increased at the score line 12, allowing a clean break.

[0093] FIG. 10 illustrates a fourth embodiment. Here, the means of applying the second force F2 are pressure means in the form of a plate or sheet 50, applied to the first face of the sheet of glass in a linear movement (vertical, see figure) for example by means of a pneumatic system. The plate here comprises an essentially incompressible body 51, for example made of metal or PMMA, and a more flexible covering 52 intended to avoid the creation of surface defects on the glass, on its side designed to come into contact with the sheet of glass 10.

[0094] The force F2 applied to the first face 10a of the sheet of glass 10 using the plate 50 is a planar pressure force—directed toward the support—uniformly or near-uniformly applied to practically the entire extent of the interior part of the sheet of glass.

[0095] Advantageously, the plate 50 has dimensions slightly smaller than those of the shape to be cut out and extends over all of the interior part of the sheet of glass except for a peripheral strip, notably of width less than 3 mm. It may thus already be in place prior to scoring, in order to hold the sheet of glass 10.

[0096] For the remainder, and according to one nonlimiting example, the break-out support 30 is identical to that of the third embodiment and the first force F1 is applied by means of a tool having a single pressure head comprising a ball 44 urged toward the first face of the sheet of glass by means of a system that manages the breaking-out pressure applied pneumatically.

[0097] Note that according to an alternative form (not depicted), the plate forming the break-out support 30 may also take the form of a hollow frame defining a closed contour, the shape of which corresponds to the contour of the glazing to be cut out. In that case, the contour of the plate runs alongside the score line, either flush therewith or some distance therefrom (typically less than 3 mm therefrom). In that case, the force F2 is a planar pressure force applied uniformly or near-uniformly to a zone situated near the score line, or along the score line.

[0098] FIG. 11 illustrates a fifth embodiment, using a breaking-out support 30 identical to that of the third embodiment. The means of applying the second force F2 here are suction means designed to generate a vacuum on the second face 10b of the sheet of glass 10. Advantageously, the second force F2, chosen according to the invention to increase the bending moment of the glass at the score line, is applied exclusively to a useful zone situated a distance away from the score line comprised between 3 and 30 millimeters, preferably between 5 and 25 millimeters, more preferably still, between 5 and 15 millimeters.

[0099] The suction means are advantageously arranged under the support, more particularly under the scoring/breaking-out table, and comprise a pump 60, openings 62 made in the table 20, openings 64 in the material of which the conveyor belt 22 is made and openings 66 in the support 30. The openings may be holes of greater or lesser size made in the material or may be formed as a result of the natural porosity of the material.