EP3625180A1

EP3625180A1 - Method for breaking a glass sheet

Info

Publication number: EP3625180A1
Application number: EP18727860.1A
Authority: EP
Inventors: Axel NOGRET; Thierry Dumenil; Dominique Bureloux
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS
Priority date: 2017-05-19
Filing date: 2018-05-07
Publication date: 2020-03-25
Also published as: BR112019022886A2; FR3066487B1; RU2019139058A3; JP7208921B2; KR20200010221A; CN109287119A; RU2019139058A; MX2019013341A; WO2018211201A1; FR3066487A1; KR102552188B1; JP2020520874A; MA49134A; US20210155525A1; CA3063479A1

Abstract

The invention relates to a method for breaking a glass sheet (10), comprising: - a step of tracing a score line (12) on a first face (10a) of the glass sheet (10), the score line (12) delimiting an exterior part (16) and an interior part (14) of the glass sheet (10), - a step of positioning a support (30) facing said score line (12) on the side (10b) of the glass sheet (10) opposite said first face (10a), and - a step of breaking by simultaneous application of at least a first force (F1) on the exterior part (16) of the glass sheet (10) and of at least a second force (F2) on the interior part (14) of the glass sheet (10).

Description

METHOD FOR RAPIDING A GLASS SHEET

The present disclosure relates to the field of breakage of a glass sheet, and more particularly relates to a method of breaking.

The method according to the present disclosure is particularly - but not limitatively - suitable for breaking a glass sheet of small thickness, in particular of thickness less than or equal to 1 mm, in particular less than or equal to 0.7 mm.

It is recalled that the breaking of a glass sheet is achieved in at least two successive operations:

a preliminary operation of tracing one or more cutting lines or superficial cracks on the surface of the glass; these cracks form lines corresponding to the contours of the glazing to be cut; this operation is called the "cut" operation;

an operation for propagating the initial surface crack through the thickness of the glass sheet; this operation is called the "break" operation.

A known method of breaking glass, applied to the manufacture of automotive glazing, typically a windshield, is described below with reference to Figures 1a to 1d and 2a, 2b.

A so-called primitive glass sheet 1 10 is provided in the form of a square, a rectangle or a trapezium.

On a first face 1 10a of the glass sheet 1 10, a cutting line 1 12 corresponding to the contour of the shape (i.e. of the glazing) to be cut is drawn (FIG. The cutting line 1 12 delimits an inner portion 1 14 and an outer portion 1 16 of the glass sheet.

As illustrated in FIG. 1b, complementary cuts in the form of straight segments 1 18a, 1 18b, 1 18c, 1 18d, also called additional lines, are made in the outer part 1 16, in order to allow a good breaking of this part. This cutting operation (FIGS. 1a and 1b) is typically carried out using a glass wheel or a laser.

A break of the primitive in several steps is then performed to separate the form to be cut out 170 from the outer part 1 16.

This break is illustrated by Figures 1c, 2a and 2b. It is carried out by a technique of bending the outer portion 1 16 of the glass sheet 1 10.

As illustrated in FIG. 2a, the glass sheet 1 10 is placed cantilevered on a breaking support 130.

Then a breaking tool 140, for example a ball or a wheel, is applied - generally displaced - on the outer part 1 16 of the glass sheet, along the cutting line 1 12 but offset from this line and relative to the breaking support 130 (bold lines in Figure 1c).

As illustrated in FIG. 2b, the force applied by the breaking tool causes propagation of the crack at the cutting line over the entire thickness e of the glass sheet 1 10.

The outer part 1 16, divided into pieces called "falls" 171, 172, 173, 174 delimited by the additional lines 1 18a, 1 18b, 1 18c, 1 18d, is thus separated from the shape to be cut 170 (FIG. ).

The quality of the break obtained with this technique is not always satisfactory. In some cases, the propagation of the break along the contour of the form to be cut is incomplete or uncontrolled. If it is uncontrolled, the crack no longer follows the cutting line, generating scrap. Also, cut edges of the glass may be corrugated in the length or not perpendicular to the two faces of the glass (it is called slanting), or defects transverse to the cut line called scales may appear. It has also been found that these quality problems are more frequent when breaking thin glass, especially of thickness less than or equal to 1 mm.

An object of the invention is thus to improve the quality of the breaking of glass sheets, and in particular - but not exclusively - thin glass sheets.

For this purpose, the subject of the invention is a process for breaking a shape in a glass sheet, in particular a glass sheet having a thickness less than or equal to 1 mm, and more particularly less than or equal to 0.7 mm, said method comprising at least the following steps:

a step of tracing a cutting line on a first face of the glass sheet, the cutting line delimiting an outer portion and an inner portion of the glass sheet,

a step of placing a support opposite said cutting line, on the side of the glass sheet opposite said first face, and

- A step of breaking by simultaneous application of at least a first force on the outer portion of the glass sheet and at least a second force on the inner portion of the glass sheet.

In the present disclosure, a cutting line must be understood as a crack intended to allow the breaking along this line during the breaking step. It is therefore a partial cut, which extends over only a portion of the thickness of the glass sheet. Note that a cutting line can define a closed contour, or not (for example, the cutting line can cross the sheet of glass from side to side).

It has been found that the application of additional force on the glass sheet on the side of the cutting line opposite to the breaking force (first force) considerably improves the quality of the breakage. With the addition of the second force, the glass sheet has, in the vicinity of the cutting line, a behavior approaching that which it would have if the inner part of the glass sheet was embedded. The second force is chosen to increase the curvature of the glass surface at the cutting line. Thus, the bending moment is increased at this point, causing a sharp break in the glass.

The method according to the present disclosure is particularly - but not exclusively - suitable for breaking a complex shaped glazing into a glass sheet. By complex shape is meant here a curved line, or succession of lines, at least some of which are not rectilinear, or straight lines with changes of direction forming at least a concave portion. A glass sheet generally has two parallel main faces connected by a song having a dimension much smaller than that of the main faces. The thickness of the glass sheet is the distance between the two faces of said sheet.

The first face of the glass sheet on which the cut line is drawn is typically the upper face. The second face of the glass sheet, opposite this first face, is typically the underside. For the rest of the present description, two directions are then defined, upwards and downwards, with reference to a direction orthogonal to the upper and lower faces. This provision is however not limiting, and the first face may for example become the lower face and the second face, the upper face, the implementation of the method according to the invention remains however the same.

In one example, the support is arranged to allow the outer portion of the glass sheet to bend under the effect of the first force. Referring to the foregoing, it is noted that the first force is exerted downwards and, as a result, the outer portion bends downwards.

Generally, the medium is essentially incompressible. It is for example made of metal or polymethylmethacrylate (PMMA).

The glass sheet can be supported directly or indirectly by the support. In other words, the glass sheet may be in direct contact with the support, or more flexible protection means may be interposed between the glass sheet and the support so as to preserve the glass sheet at the time of breaking. The protection means comprise, for example, a belt, in particular a compressible belt, having in particular a shore hardness between 70 and 90. It may for example be a rubber mat reinforced with polyester fabric.

In one example, at least one useful portion of the outer portion is located cantilevered relative to the support. The first force is exerted on said useful portion.

In one example, the first force is applied in at least a first point on the outer portion and the second force is applied simultaneously in at least a second point on the inner part, the first and second points being located opposite one another on either side of the cutting line.

Advantageously, the second force is chosen so that the curvature of the glass is maximized at the cutting line. Thus, the forces to be applied to the glass to allow breakage are decreased, thereby decreasing the risk of unwanted crack propagation and scrapping.

Generally, the second force is applied to an area near the cutting line. Advantageously, it is applied to a useful area located at a distance from the cutting line (measured in a direction orthogonal to said line and parallel to the faces of the glass sheet) of between 3 and 30 millimeters, preferably between 5 and 25 millimeters. more preferably between 5 and 15 millimeters.

Advantageously, the second force is located in a restricted manner (i.e. applies exclusively) on the said useful zone.

In one example, the first and / or second force is a bearing force on the first face of the glass sheet. It may be a local support force. According to a particular embodiment of the invention, the breaking step can then be performed by moving, along the cutting line, a single breaking tool provided with a first local support head and a second local support head disposed on either side of the cutting line, the first local support head forming a means for applying the first force and the second local support head forming a means for applying the second force. . Each support head comprises for example a ball or a wheel biased elastically towards the first face of the glass sheet by a pneumatic system for managing the breaking pressure or by any other suitable system. In another example, the first and / or second force is a plane bearing force. For example, the second force is applied by means of a plate extending over substantially the entire extent of the inner portion of the glass sheet (ie over the entire extent of the inner portion or over the entire length of the the inner part except for a peripheral band along the cutting line, in particular of width less than 3 mm).

According to yet another example, the first and / or second force is a suction force. In this case, for example, the support and / or the protection means may be provided with openings for the passage of air.

Note that several types of force can also be combined, if necessary.

Typically, the first force is moved on the glass sheet along the cutting line. The superficial crack resulting from the cutting step is thus propagated along said cutting line as it travels.

The second force can be fixed: it can in particular be applied simultaneously along the entire cutting line. This is the case, for example, when this second force is applied by means of a plate or sheet forming a flat support resting on substantially the entire extent of the shape to be cut (substantially all the inner part of the glass sheet ).

It can also be moved on the glass sheet, along the cutting line, continuously or not. In this case, it is usually moved simultaneously to the first force.

As an example of discontinuous displacement, the first and second forces may be successively applied to different spaced apart locations along the cutting line.

Note however that alternatively it is the glass sheet that is moved, or the glass sheet and the forces. In general, it is a relative displacement of the forces relative to the glass sheet.

Advantageously, the support is arranged to also allow the inner portion of the glass sheet to bend under the effect of the second force. Note that the second force is applied downwards, and the inner part curves downwards. Typically, everything happens functionally as if at least a useful portion of the inner portion was located cantilevered relative to the support. The second force is then exerted on said useful portion. According to a particular arrangement, the support has an internal border and an external border located opposite the glass sheet and respectively on either side of the cutting line. Advantageously, the support has a general shape corresponding to the outline of the cutting line: its borders follow the line of the line. Advantageously, the support extends continuously over the entire length of the cutting line. For example, if a sinusoidal line is to be cut, then the support is a band forming the same sinusoid. If the cutting line defines a closed contour, then the support advantageously forms a frame defining a closed contour corresponding to the plot of the cutting line. If the shape to be cut is square, then the support is a square-shaped frame. If the shape is round or oval, then the support is a round or oval shaped frame, etc.

Alternatively, the support may also extend over a restricted portion of the cutting line. In this case, the support is for example in the form of a fixed or movable pad along the cutting line. In some embodiments, the support can be moved relative to the cutting line, continuously or not. In particular, the support can be moved together with the first and possibly the second force, to ensure the propagation of the crack along the cutting line.

Several examples are described in this presentation. However, unless otherwise stated, the features described in connection with any example may be applied to another example.

The invention will be better understood on reading the description which follows, made solely by way of non-limiting example, with reference to the following figures:

FIGS. 1 to 1 d schematically illustrate various steps of a method of breaking a sheet of glass,

FIGS. 2a and 2b are diagrams in section of the break of a glass sheet,

FIG. 3 illustrates the step of cutting a sheet of glass according to the method of the invention, FIG. 4 is a top view of the glass sheet disposed on a breaking support according to a first embodiment of the invention;

FIG. 5 is a diagrammatic sectional view along V of FIG. 4, before breaking,

FIG. 6 is a diagrammatic sectional view along line VI of FIG. 4, illustrating the step of breaking with the aid of a breaking tool according to the invention,

FIG. 7 is a top view of a glass sheet disposed on a breaking support according to a second embodiment of the invention;

FIG. 8 is a top view of a glass sheet disposed on a breaking support according to a third embodiment of the invention;

FIG. 9 is a diagrammatic sectional view along IX of FIG. 8, illustrating the step of breaking,

FIG. 10 illustrates a fourth mode of implementation of the invention,

Figure 11 illustrates a fifth embodiment of the invention.

A first embodiment of the method according to the invention is described below with reference to FIGS. 3 to 6, for breaking a complex shaped glazing unit, in particular a car glazing such as a windshield. .

A first step of the process, illustrated in FIG. 3, consists in providing a flat sheet of glass 10, here rectangular in shape, and in drawing a cutting line 12 on a first face 10a of this sheet of glass 10 (see FIG. 5, upper side of the glass sheet).

The cutting line 12 defines, in a direction orthogonal to the cutting line 12, an outer portion 16 and an inner portion 14 of the glass sheet, the inner portion 14 corresponding - in the example - to the contour of the glazing to be cut. In known manner, complementary cutouts in the form of segments-generally straight-18a, 18b, 18c, 18d are also made in the outer portion 16.

The cutting line 12 and the additional lines 18a, 18b, 18c, 18d are cracks intended to allow breaking according to this line (s) during the breaking step. It is therefore a partial cut, i.e. only on a part of the thickness of the glass sheet.

In the usual way, this step is carried out on a cutting table 20, on which the glass sheet 10 is generally brought by means of a conveyor belt 22.

In the example, the drawing of the cutting line 12 and additional lines 18a, 18b, 18c, 18d is achieved by means of a device 24 comprising a glass wheel, secured to an axis that can be displaced in translation in two directions. X, Y directions parallel to the glass sheet, and rotated about a Z axis perpendicular to it (Figure 3).

Alternatively, however, the cutting can be performed using any other suitable cutting instrument, such as for example a laser.

For breaking, the glass sheet 10 is disposed on a substantially incompressible breaking support 30 in the form of a sheet or the like, for example metal, generally supported by a breaker table. As illustrated in FIG. 5, the second face 10b of the glass sheet (lower face) is then that facing the support 30, and towards the breaker table supporting this support.

Advantageously, the glass sheet 10 is disposed on the support 30 by means of interposed protection means for preserving the glass sheet at the time of breaking.

In the example, the breaker table and the cutting table are one and the same table 20. The protection means here comprise the conveyor belt 22, for example reinforced rubber fabric polyester, ensuring the movement of the sheet the along the production line. The breaking support 30 is thus placed under the glass sheet 10 as soon as the cutting step. In other cases, however, the cutting and breaking steps are performed on different stations of the production line or the breaking support 30 is interposed between the glass sheet 10 and the table 20 after cutting and before breaking. .

In the first mode of implementation illustrated in FIG. 4, the breaking support 30 is a fixed support, extending over the entire length of the cutting line 12.

It is in the form of a frame defining a closed contour, the shape of which corresponds to the contour of the glazing to be cut. Delimited laterally by an outer rim 30a and an internal rim 30b, the support 30 is positioned facing the cutting line 12 and a portion 16b of the outer portion 16 and a portion 14b of the inner portion 14 of the sheet adjacent to the cutting line 12. It is generally recommended that the support extends on either side of the cutting line, over a distance respectively da, db typically equal to at least 3 millimeters.

The support 30 allows the curvature of the outer portion 16 of the glass sheet 10 downward (i.e. towards the breaker table).

To do this, as illustrated in Figure 5, a useful portion 16a of the outer portion 16 is located cantilever relative to the support. On the other side, a useful portion 14a of the inner portion extends beyond the support 30. Functionally, and taking into account the flexibility of the glass, everything happens as if the useful portion 14a was door-to-door. false with respect to the support 30.

The break, illustrated in FIG. 6, is carried out by a technique of bending the glass sheet 10, inducing tensile forces in the glass at the cutting line 12.

According to the invention, two forces F1 and F2 are applied simultaneously to the glass sheet 10, in a direction orthogonal to said sheet and downwards.

A first force F1 is exerted on the useful portion 16a of the outer portion 16. A second force F2 is exerted on the useful portion 14a of the inner portion 14, close to the cutting line 12, generally on an area located at a distance d from the cutting line 12 of between 3 and 30 millimeters, preferably between 5 and 30 millimeters. and 25 millimeters, even more preferably between 5 and 15 millimeters, in a direction orthogonal to said feature.

In the embodiment illustrated (non-limiting), the first and the second force F1 and F2 are applied using a single tool 40 with two support heads 41, 42. Each head 41, 42 comprises for example a ball 44 resiliently biased towards the first face 10a of the glass sheet 10 by a pneumatic system 46 for controlling the breaking pressure ensuring contact of the ball on the glass, or by any other suitable system, possibly a spring . Each ball 44 is in local support at a point respectively P1, P2 of the glass sheet. Note that in a variant, the tool may have wheels in place of the balls 44.

The tool 40 is intended to be moved continuously along the cutting line 12 so as to make the crack in the glass progressively progressively along the cutting line 12. Note that it is generally necessary for the complex shapes, that the tool can be moved in two perpendicular directions X, Y and rotated about an axis Z orthogonal to X, Y, so that the axis connecting the two heads remains substantially perpendicular to the cutting line during move.

As illustrated in Figure 6, under the effect of the first and second forces F1, F2 respectively, the outer 16 and inner 14 parts bend downwards.

The simultaneous application of the first and second forces F2 increases the bending moment exerted on the surface of the glass at the cutting line 12, ensuring a clean break (FIG. 6).

Advantageously, the point of application P2 of the second force F2 and its intensity are chosen so that the curvature of the surface of the glass is highest at the cutting line.

Figure 7 illustrates a second embodiment. Only the shape of the break support 30 differs from the first mode. The other characteristics described above are therefore not repeated again.

According to this second mode, the breaking support 30 is a local support of the pad type, which extends only over a section of the cutting line 12, in the longitudinal direction of said line. The dimensions of its surface intended to come opposite the glass sheet 10 are for example between 5 and 15 cm.

In the example, the local support 30 is movable: To propagate the crack along the cutting line 12, the support 30 is for example displaced next to the cutting line 12 at the same time and in the same way as the d application of the forces F1 and F2, in particular so that the points of application of the forces F1 and F2 and the support 30 remain aligned orthogonally to the cutting line 12.

Note that according to one variant, the local support 30 could also be fixed. In this case, it is generally necessary to set up several studs punctually, along the cutting line 12, to ensure proper propagation of the crack over the entire contour of the shape.

Figures 8 and 9 illustrate a third mode of implementation.

As illustrated in FIG. 8, the rupture support 30 has here a solid plate shape supporting the inner portion 14 of the glass sheet 10 over its entire extent, as well as a portion of the outer portion 16 contiguous to the cutting line. , only a useful portion 16a peripheral of the outer portion 16 of the glass sheet being cantilevered relative to the support 30.

According to the invention, a first force F1 is exerted on the useful portion 16a of the outer part 16, and a second force F2 is exerted on the inner part 14, close to the cutting line 12.

The deformation of the glass sheet resulting from the application of F1 and the flexibility of the glass is prevented where this second force F2 is exerted. At this point, the glass sheet 10 remains substantially parallel to the cutting table 20 and the support 30. In fact, the bending moment exerted on the surface of the glass is increased at the cutting line 12, allowing a clean break . Figure 10 illustrates a fourth embodiment. Here, the means for applying the second force F2 are support means in the form of a plate or sheet 50, applied to the first face of the glass sheet in a linear movement (vertical, see the figure) for example by means of a pneumatic system. The plate here comprises a substantially incompressible body 51, for example of metal or PMMA, and a more flexible coating 52 intended to prevent the creation of surface defects on the glass, on its side adapted to come into contact with the glass sheet. 10.

The force F2 applied to the first face 10a of the glass sheet 10 by means of the plate 50 is a support force that is plane-directed towards the support-exerting in a uniform or quasi-uniform manner over substantially the entire extent of the inner part of the glass sheet.

Advantageously, the plate 50 has dimensions slightly smaller than those of the shape to be cut and extends over the entire inner part of the glass sheet except for a peripheral band, in particular with a width of less than 3 mm. It can thus be already in place before cutting, in order to maintain the glass sheet 10.

For the rest, and according to a nonlimiting example, the breaking support 30 is identical to that of the third mode, and the first force F1 is applied by means of a single head tool comprising a ball 44 biased towards the first face of the glass sheet by means of a system for controlling the breaking pressure exerted in a tire.

Note that according to a variant (not shown), the plate forming a rupture support 30 may also have a hollow frame shape defining a closed contour, whose shape corresponds to the contour of the glazing to be cut. In this case, the contour of the plate runs along the cutting line, flush with it or at a distance from it (typically less than 3 mm). In this case, the force F2 is a plane bearing force acting in a uniform or quasi-uniform manner on an area located in the vicinity of the cutting line, all along the cutting line. FIG. 11 illustrates a fifth embodiment, using a break support 30 identical to that of the third mode. The means for applying the second force F2 here are suction means adapted to generate a depression on the second face 10b of the glass sheet 10. Advantageously, the second force F2, chosen according to the invention to increase the moment bending of the glass at cutting line level, applies exclusively to a useful area located at a distance from the cutting line of between 3 and 30 millimeters, preferably between 5 and 25 millimeters, even more preferably between 5 and 15 millimeters .

The suction means are advantageously arranged under the support, more particularly under the cutting / breaking table, and comprise a pump 60, openings 62 formed in the table 20, openings 64 in the material constituting the conveyor belt 22 and openings 66 in the support 30. The openings may be holes of greater or lesser dimensions made in the material or may be formed by the natural porosity of the material.

Claims

1. A method of breaking a glass sheet (10), comprising at least the following steps:

a step of marking a cutting line (12) on a first face (10a) of the glass sheet (10), the cutting line (12) delimiting an outer part

(16) and an inner portion (14) of the glass sheet (10),

a step of placing a support (30) facing said cutting line (12), on the side (10b) of the glass sheet (10) opposite said first face (10a), and

- a step of breaking by simultaneous application of at least a first force (F1) on the outer portion (16) of the glass sheet (10) and at least one second force (F2) on the inner portion (14); ) of the glass sheet (10).

2. The method of claim 1, wherein the support (30) is arranged to allow the outer portion (16) to bend under the effect of the first force (F1).

3. The method of claim 1 or 2, wherein at least a useful portion (16a) of the outer portion (16) is located cantilever with respect to the support (30).

A method according to any one of claims 1 to 3, wherein the first force (F1) is applied at at least one first point (P1) to the outer portion (16) and the second force (F2) is applied simultaneously in at least a second point (P2) on the inner part (14), the first and second points (P1, P2) being located opposite one another on either side of the cutting line (12). ).

5. A method according to any one of claims 1 to 4, wherein the second force (F2) is chosen so that the curvature of the glass surface is highest at the cutting line (12).

The method according to any one of claims 1 to 5, wherein the second force (F2) is applied to an area, preferably in a restricted manner, at a distance from the score line (12) between 3 and 30. millimeters, preferably between 5 and 25 millimeters, more preferably between 5 and 15 millimeters.

The method of any one of claims 1 to 6, wherein the second force (F2) is a local support force.

8. The method of claim 7, wherein the breaking step is performed by moving, along the cutting line, a single breaking tool (40) provided with a first local support head (41). and a second local support head (42) disposed on either side of the cutting line, the first local support head forming the application means of the first force and the second local support head forming means of applying the second force.

9. A method according to any of claims 1 to 8, wherein the second force (F2) is a plane bearing force.

The method of any one of claims 1 to 9, wherein the second force (F2) is a suction force.

1 1. A method according to any one of claims 1 to 10, wherein the support (30) is arranged to allow the inner portion (14) of the glass sheet (10) to bend under the effect of the second force ( F2).

The method of any one of claims 1 to 11, wherein the first force (F1) is moved on the glass sheet (10) along the cutting line.

The method of any one of claims 1 to 12, wherein the second force (F2) is moved on the glass sheet (10) along the cutting line.

The method of any one of claims 1 to 12, wherein the second force (F2) is fixed.

15. Method according to any one of claims 1 to 14, wherein the support (30) has an inner edge and an outer edge located opposite the glass sheet (10) and respectively on either side of the line. cutting (12).

16. A method according to any one of claims 1 to 15, wherein the support (30) forms a frame defining a closed contour corresponding to the plot of the dash (12).

Method according to any of claims 1 to 16, wherein the support (30) extends continuously over the entire length of the cutting line.

18. A method according to any one of claims 1 to 16, wherein the support (30) extends over a restricted portion of the cutting line.

19. Method according to any one of claims 1 to 18, wherein protection means (22) are interposed between the glass sheet (10) and the support (30), including a protective mat, and in particular a compressible protection mat.

20. A method according to any one of claims 1 to 19, wherein the glass sheet (10) has a thickness (e) less than or equal to 1 mm, preferably less than or equal to 0.7 mm.