U.S. patent application number 15/328170 was filed with the patent office on 2017-08-03 for method for breaking out a sheet of glass.
The applicant listed for this patent is SAINT-GOBAIN GLASS FRANCE. Invention is credited to Dominique BURELOUX, Thierry DUMENIL.
Application Number | 20170217818 15/328170 |
Document ID | / |
Family ID | 51830498 |
Filed Date | 2017-08-03 |
United States Patent
Application |
20170217818 |
Kind Code |
A1 |
DUMENIL; Thierry ; et
al. |
August 3, 2017 |
METHOD FOR BREAKING OUT A SHEET OF GLASS
Abstract
The method includes tracing a score line on the surface of the
glass, using a scoring tool, and breaking out using a local
pressure system applied on the opposite face and opposite the score
line, the local pressure system being moved and pressed along the
score line on the opposite face.
Inventors: |
DUMENIL; Thierry; (Margny
Les Compiegne, FR) ; BURELOUX; Dominique; (Ognes,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAINT-GOBAIN GLASS FRANCE |
Courbevoie |
|
FR |
|
|
Family ID: |
51830498 |
Appl. No.: |
15/328170 |
Filed: |
July 23, 2015 |
PCT Filed: |
July 23, 2015 |
PCT NO: |
PCT/FR2015/052043 |
371 Date: |
January 23, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03B 33/033 20130101;
C03B 33/0235 20130101; C03B 33/04 20130101 |
International
Class: |
C03B 33/04 20060101
C03B033/04; C03B 33/023 20060101 C03B033/023; C03B 33/033 20060101
C03B033/033 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2014 |
FR |
1457171 |
Claims
1. A method for breaking out a complex shape from a sheet of glass,
comprising: tracing a score line on a surface of the glass, using a
scoring tool, and breaking out the glass using a local pressure
means applied on an opposite face and opposite the score line, the
local pressure means being moved and pressed along the score line
on said opposite face.
2. The method as claimed in claim 1, further comprising
planar-support means on the side of the score line, facing the
local pressure means during the breaking-out.
3. The method as claimed in claim 2, wherein a suction table is
utilized as the planar-support means, the suction table supporting
the sheet of glass by suction on a top face of the sheet of glass
during the breaking-out or scoring.
4. The method as claimed in claim 1, wherein the tracing and the
breaking-out are performed without turning the sheet of glass
over.
5. The method as claimed in claim 1, wherein the local pressure
means is mounted so that the local pressure means is rollable so as
to roll along the sheet of glass.
6. The method as claimed in claim 1, wherein the local pressure
means is a ball or a roller.
7. The method as claimed claim 1, wherein the local pressure means
is applied with a pressing force that is chosen according to a
local radius of curvature of the shape that is to be cut out.
8. The method as claimed in claim 1, wherein the local pressure
means is pressed continuously along the score line.
9. The method as claimed in claim 1, wherein the local pressure
means is pressed with a force that has at least one periodic
component.
10. The method as claimed in claim 1, wherein the method is used to
cut at least two imbricated and/or tangential complex shapes from
the same sheet of glass.
11. A method for manufacturing a plurality of glazings of complex
shape from a large-sized rectangular sheet of float glass having at
least one dimension corresponding to a width of a ribbon of float
glass from which it large-sized rectangular sheet of float glass is
produced, the method comprising performing the method as claimed in
claim 1 to cut out at least part of said glazings.
12. The method as claimed in claim 11, comprising: on a first
workstation for scoring said sheet of glass, tracing at least one
score line corresponding to at least one ready to shape edge of the
glazings, a first breaking-out step, on a second scoring
workstation, tracing at least one score line corresponding to at
least one other ready to shape edge of the glazings; a second
breaking-out step.
13. The method as claimed in claim 11, comprising: on a first
scoring workstation, tracing score lines corresponding to all of
the ready to shape edges of the glazings, breaking out said ready
to shape edges.
14. A machine for breaking out a complex shape from a sheet of
glass, comprising: a scoring tool and means for automatically
moving said scoring tool in such a way as to create a score line
perpendicular to a surface of the glass on a first face of the
sheet of glass; a local pressure means and means for automatically
moving the local pressure means and/or the sheet of glass relative
to the other, the machine being configured to press the local
pressure means against an opposite face to the first face of the
sheet of glass and move the local pressure means opposite and along
the score line so as to break out the complex shape.
15. The breaking-out machine as claimed in claim 14, further
comprising a planar-support means against said first face of the
sheet of glass, opposite the local pressure means.
16. The method as claimed in claim 6, wherein the ball or roller is
rounded.
Description
[0001] The present invention relates to the field of breaking out a
sheet of glass, more particularly of breaking out a complex shape
from a sheet of glass.
[0002] To achieve such a break-out, there are two successive
operations: [0003] a preliminary operation of tracing one or more
surface fissures on the surface of the glass using, for example, a
glass-cutting wheel or a laser; these fissures form lines at the
contours of the shape; this operation is known as the "scoring"
operation; [0004] an operation of spreading the initial surface
fissure through the thickness of the sheet of glass; this operation
is known as the "breaking out" operation and allows the shape that
is to be cut out to be separated from the initial specimen of glass
known as the primitive.
[0005] At the present time there are two techniques for breaking
out glass, used according to the complexity of the volume that is
to be cut out:
[0006] For simple shapes with straight edges that do not penetrate
inside the shape (no concavity on the shape), it is possible to use
a rectilinear reverse breakout technique illustrated in FIGS. 1a
and 1b. This involves making a rectilinear cross score, which means
to say scoring from one edge to the other (FIG. 1a), then placing
the entire fissure in extension by lifting the sheet of glass along
the entire length of the fissure, using a bar (FIG. 1b) or one or
more point contacts.
[0007] Nevertheless, this method cannot be used for cutting out
complex shapes. For shapes with non-rectilinear contours, the
starting point is a sheet of glass of dimensions greater than the
shape that is to be cut out. This sheet is known as the primitive
and is generally in the shape of a trapezium. The various stages of
cutting out are illustrated in FIGS. 2a-2d.
[0008] The starting point is a primitive in the shape of a square
(FIG. 2a), a rectangle or a trapezium.
[0009] The contour of the shape that is to be cut out is traced
(FIG. 2b) for example using a glass-cutting wheel. Additional
scores in the form of straight segments are positioned around the
periphery of the shape that is to be cut out. These segments are
referred to as the relief cuts and allow that part of the primitive
that is situated outside of the shape that is to be cut out to be
broken out correctly.
[0010] Using a number of steps to break out that part of the
primitive that is situated outside of the shape that is to be cut
out causes various pieces referred to as "offcuts" being obtained
around the complex shape that is to be cut out (FIG. 2c).
[0011] The shape that is to be cut out is then isolated from the
offcuts of the primitive (FIG. 2d).
[0012] When cutting out complex shapes as described here, the
breaking out is performed using a technique of locally bending the
initial fissure by applying pressure to the offcut or alternatively
by taking hold of the offcut. The bending is applied by a lever-arm
mechanism pressing against the sheet of glass, on the outside of
the shape and at a limited number of points, on a hard or soft
covering.
[0013] FIGS. 3a to 3d are diagrams in cross section of the breaking
out of a sheet of glass by applying bending to an initial fissure
of complex shape by bending the part external to the shape that is
to be cut out.
[0014] FIGS. 3a and 3b relate to the circumstance in which breaking
out is performed on a soft belt. Force is applied to the offcut by
pressing on it until it breaks and the offcut is separated.
[0015] FIGS. 3c and 3d relate to an example of breaking out on a
hard belt. The sheet of glass is positioned with an overhang so
that a force applied to the offcut by pressure or by gripping
allows the sheet of glass to be deformed until it breaks.
[0016] Nevertheless, these techniques have a number of
disadvantages.
[0017] In the case of FIGS. 3c and 3d there is a sacrificial area
of glass lost through the need to create the overhang for breaking
out.
[0018] Furthermore, there may be problems with the quality of the
cutting-out of the complex shapes because when pressure is applied
to the offcut it is not generally possible to create a bending
stress at every point on the score line. This is notably the case
with re-entrant shapes (concave portions on the shape that is to be
cut out). In such cases it is possible to introduce bending into
the glass at the entrance to the concave part, but as soon as the
fissure has spread a little, and before the tool applying the
pressure can be removed, the field of stresses at the head of the
fissure is modified by the geometry of the score line. The pure
bending that was applied at the start of the concave part quickly
becomes a shear stress and causes chipping. In the case of shapes
with a small radius, the fissure may spread beyond the initial
score line and generate scrap. Such a situation is indicated
schematically in FIGS. 4 and 5.
[0019] Adjusting the pressure points may solve this problem but
this remains a difficulty.
[0020] What is more, this limits the complex shapes that can be
achieved, particularly in the case of geometries with small concave
radii of curvature (deeply curved regions) where it is difficult to
site a pressure point appropriately.
[0021] These difficulties make breaking out concave shapes
particularly tricky. If the radius of curvature is small, adjusting
the positions of and loads at the pressure points becomes a lengthy
and tricky operation. In production, the breaking out of these
geometries is often sensitive to the slightest variation in working
parameters and may give rise to a great deal of scrap. Moreover,
the propensity of the stress field at the head of the fissure to
transform from a pure bending mode to a shear mode is exacerbated
as the thickness of the glass increases. Re-entrant shapes are thus
reputed to be very difficult to achieve with glass 3.85 or 5 mm
thick.
[0022] It is an object of the invention to make cutting complex
shapes from sheets of glass easier. To this end, one subject of the
invention is a method for breaking out a complex shape from a sheet
of glass, comprising: [0023] a step of tracing a score line on the
surface of the glass, using a scoring tool; [0024] a step of
breaking out using a local pressure means applied on the opposite
face and opposite the score line, the local pressure means being
moved and pressed along the score line on said opposite face.
[0025] This method makes it possible to reduce the sacrificial area
of glass between two volumes. It is even conceivable for several
components to be cut from the same large-sized sheet of glass, with
components which may touch at certain points. It then becomes
conceivable to cut with maximum imbrication of shapes and a very
substantial reduction in offcuts.
[0026] This is because there is no need to create a square,
rectangular or trapezoidal primitive similar to the complex shape
that is to be obtained. It is possible to cut the complex shape
directly from the large-format sheet from which several complex
shapes may be cut. This means that the positions of the complex
shapes in the sheet of glass can be optimized thereby reducing the
cost of the "glass" raw material.
[0027] It is also possible to create primitives of which certain
edges are ready to shape and of complex shape while the shaping of
the other edges is performed during the second step of scoring. In
general, this means making all or part of the edges of complex
shape right from the first step of scoring on the production
line.
[0028] It is also possible to shape all the edges during the second
step of scoring, which means to say to continue to score in a first
phase primitives the edges of which are not ready to shape, but
providing widths of "trim" that are not as great as they were
before.
[0029] More complex cutouts may also be achieved, particularly
"re-entrant" cutouts, and cutouts for thick glass, and with good
yield.
[0030] Because the adjusting of the position is connected with the
contour, adjusting the position of the pressure points is also
simpler.
[0031] Furthermore, this breaking out technique can be incorporated
into an existing line.
[0032] Provision may be made for a counter-force to oppose the
force with which the local pressure means is pressed during the
breaking-out step.
[0033] According to one embodiment, a planar-support means is
positioned on the score line side, facing the local pressure means
during the breaking-out step.
[0034] In this case, the planar-support means forms a counter
support generating a counter force that opposes the force with
which the local pressure means is pressed during the breaking-out
step.
[0035] According to an alternative form, the counter force may
result from the weight of the sheet of glass itself, when this
weight is sufficiently great.
[0036] According to one embodiment, the tracing step and the
breaking-out step are performed without turning the sheet of glass
over in between. In other words, according to one example, the
score line is produced from the top at the surface of the glass and
the local pressure means is applied from the bottom to the opposite
face of the glass, or vice-versa. The sheet of glass is not turned
over between the two steps.
[0037] According to other particular embodiments, the method also
has one or more of the following features considered alone or in
any technically feasible combination: [0038] the local pressure
means is mounted so that it can roll so as to roll along the sheet
of glass; [0039] the local pressure means is a ball or a roller,
preferably rounded; [0040] the local pressure means is applied with
a pressing force that is chosen according to the local radius of
curvature of the shape that is to be cut out; [0041] the local
pressure means is pressed continuously along the score line; [0042]
the local pressure means is pressed with a force that has at least
one periodic component; [0043] the method uses a suction table as a
planar-support means, the suction table supporting the sheet of
glass by suction on the top face of the sheet of glass during the
breaking-out or scoring step; [0044] the method is used to cut at
least two imbricated and/or tangential complex shapes from the same
sheet of glass.
[0045] Another subject of the invention is a method for
manufacturing a plurality of glazings of complex shape from a
large-sized rectangular sheet of float glass having at least one
dimension corresponding to the width of the ribbon of float glass
from which it is produced, using the method as claimed in any one
of the preceding claims to cut out at least part of said
glazings.
[0046] According to one particular embodiment, the method of
manufacture comprises: [0047] on a first workstation for scoring
said sheet of glass, a step of tracing at least one score line
corresponding to at least one ready to shape edge of the glazings,
[0048] a first breaking-out step, [0049] on a second scoring
workstation, a step of tracing at least one score line
corresponding to at least one other ready to shape edge of the
glazings; [0050] a second breaking-out step.
[0051] According to another particular embodiment, the method
comprises: [0052] on a first workstation for scoring said sheet of
glass, tracing score lines corresponding to all of the ready to
shape edges of the glazings, [0053] a step of breaking out said
ready to shape edges.
[0054] According to some particular embodiments, the method of
manufacture also has one or more of the following features
considered alone or in any technically feasible combination: [0055]
the precision with which the score lines are traced on the first
scoring workstation is +/-0.2 mm; [0056] the second scoring
workstation incorporates a focusing step accurate to +/-0.1 mm;
[0057] at the first scoring workstation, the score line is a
straight score line running across the sheet of glass from one edge
to the other; [0058] at the first scoring workstation, the score
line forms a ready to shape edge of several glazings on one same
side of the score line; [0059] at the first scoring workstation,
the score line also forms a ready to shape edge of several glazings
on the other side of the score line; [0060] on each side of the
score line, the ready to shape edges are the same edge of the
glazings; [0061] on each side of the score line, the ready to shape
edges are the opposite edges of the glazings; [0062] the first
breaking-out step forms a primitive for each glazing that is to be
manufactured, the second breaking-out step forming the glazing
which is ready for edging; [0063] the method comprises at least one
additional scoring workstation, with at least one additional
breaking-out step; [0064] the method comprises a step of edging the
glazing after the second breaking-out step; [0065] the edging is
grinding; [0066] two grinding steps are performed; [0067] the
large-format sheet of glass has at least one dimension of at least
2.9 m.
[0068] Another subject of the invention is a machine for breaking
out a complex shape from a sheet of glass, comprising: [0069] a
scoring tool and means for automatically moving said tool in such a
way as to create a score line perpendicular to the surface of the
glass on a first face of a sheet of glass; [0070] a local pressure
means and means for automatically moving the local pressure means
and/or the sheet of glass relative to the other, the machine being
configured to press the local pressure means against the opposite
face to the first face of the sheet of glass and move it opposite
and along the score line so as to break out the complex shape.
[0071] According to one particular embodiment, the breaking-out
machine further comprises a planar-support means against said first
face of the sheet of glass, opposite the local pressure means.
[0072] The invention will be better understood from reading the
following description, given solely by way of nonlimiting example,
with reference to the following figures: [0073] FIGS. 6a-6c are
schematic views in vertical section of various steps of a method
according to one particular embodiment of the invention; [0074]
FIGS. 7a-7c, 8a-8c, 9a-9c and 10a-10c are also schematic views in
vertical section of the steps performed by four different
breaking-out machines; [0075] FIGS. 11a and 11b illustrate one
example of a design of cutout permitted by the invention according
to a first example of a production line, the white lines
representing the edges along their ready to shape contour and the
dotted lines representing the tracing of the score lines during the
first step of scoring on the line; [0076] FIGS. 12a and 12b are
views similar to FIGS. 11a and 11b for another example of a
production line.
[0077] FIGS. 6a-6c schematically illustrate a method according to
one particular embodiment of the invention, consisting first of all
of a step of tracing a score line 2, which means to say of creating
a fissure on a first face 4A of the sheet of glass 4, followed by a
step of turning the sheet of glass over for the purposes of a
subsequent step of applying local pressure opposite the fissure, on
the opposite face 4B to the first face. The traced score line
corresponds for example to the contour of the complex shape that is
to be cut out, without relief cuts.
[0078] Note that throughout the text a "complex shape" is intended
to mean a curved line, or a succession of lines at least some of
which are non-rectilinear, or rectilinear lines with changes in
direction forming at least one concave part.
[0079] Two shapes that are imbricated means that a convex part of
one encroaches into a concave part of the other, i.e. the contour
of the two shapes cannot be separated by a straight line.
[0080] Two shapes are understood to be tangential when they have a
part of their contour in common.
[0081] Note too that the sheet of glass to be cut is planar.
[0082] The score line is traced for example using a glass-cutting
wheel 6 or any other suitable scoring tool such as a laser for
example. The score line 2 is a fissure intended to allow breaking
out along this line during the breaking-out step. This then is a
partial cut, i.e. a cut through just part of the thickness of the
sheet of glass. This is what is meant by a "score line" throughout
this text.
[0083] With this method, as explained above, it is possible to
eliminate all or some of the relief cuts used in the method of the
prior art. This is because the relief cuts will potentially be
needed only to open the contour in order to extract the shape
rather than being needed to facilitate the breaking out of the
complex shapes.
[0084] As illustrated in FIG. 6c, the first face 4A of the sheet of
glass 4, on which face the score line 2 has been made, is pressed
against a planar-support surface 8. This for example is a soft
belt. The deformability of the planar-support surface 8 is chosen
in such a way as to control the field of stresses applied by the
local pressure means. Controlling the field of stresses allows
control over the length over which the fissure spreads. The
objective is for the fissure to spread to a predetermined length
according to the shape that is to be cut out. The smaller the local
radius of curvature, the smaller will be the chosen length for the
fissure. If the fissure spreads too rapidly, the surface will need
to be chosen to be less deformable or the pressure applied will
need to be lower. If the fissure spreads too slowly, a more
deformable surface or higher pressure will need to be chosen.
[0085] For a sheet of standard soda-lime-silica glass of the
"Planilux" type 3.15 mm thick, the parameters were as follows:
[0086] Scoring parameters:
[0087] Cutter wheel: angle 150.degree., width=1 mm, diameter: 5
mm
[0088] Cutter wheel speed: 100 m/min
[0089] Force applied to the glass=50N
[0090] Wheel penetration into the glass: 4/100 mm
[0091] Glass thickness: 3.15 mm
[0092] Reverse breakout parameters:
[0093] Breakout tool: wheel type, diameter: 5 mm, width: 1 mm
[0094] Tool speed: 30 m/min
[0095] Force applied to the glass=70N
[0096] Hardness of the covering of the planar-support means:
[0097] felt belt hardness: 45-52 shore.
[0098] The local pressure means 10 is, for example, a ball of any
suitable type, or another local pressure means of any suitable
type, for example a roller, preferably a roller of toric shape. The
ball for example has a diameter of 1 mm. As an alternative, the
diameter is chosen of any suitable type, notably up to 10 or even
20 mm.
[0099] The local pressure means 10 is preferably chosen to be
rigid, for example made of steel or a suitable plastic.
[0100] The local pressure means 10 is moved along the score line,
along the entire length of the score line, preferably with pressure
being continuously applied, for example of constant intensity.
However, as an alternative, pressure is applied continuously but
with varying intensity, the intensity for example being chosen
according to the local radius of curvature of the shape to be cut
out and, for example, supplemented by a periodic variation in
intensity, namely vibrating pressure. As a further alternative,
pressure is applied discontinuously to the sheet of glass.
[0101] The local pressure means is moved relative to the sheet of
glass. Note, however, that, as an alternative, it is the sheet of
glass that is moved, or both. In general, there is a relative
movement of the local pressure means 10 with respect to the sheet
of glass 4.
[0102] The planar-support surface 8 is, for example, formed by a
table and therefore by a continuous planar surface. However, as an
alternative, the planar-support surface 8 could be not continuous.
It could for example consist of a number of planar-supports
obtained for example using pieces of table. What is important is
that a planar support 8, namely a support at least twice as wide as
the pressure applied by the local pressure means, be provided
opposite the local pressure means 10, the reason for this being in
order to obtain a clean break.
[0103] Note too that the turning-over step is optional. It is
possible for example to use a suction table to lift up the sheet of
glass 4 and thus press the local pressure means 10 against it from
underneath, the first face 4A of the sheet of glass then lying
against the suction table. This is explained in greater detail
hereinbelow.
[0104] FIGS. 7a-7c, 8a-8c, 9a-9c and 10a-10c schematically
illustrate four different types of machines for implementing the
method.
[0105] The machine of FIGS. 7a-7c uses a suction table 12.
[0106] A sheet of glass 4 is conveyed as far as a cutting table 14
(FIG. 7a). A standard cutting machine 16 can therefore be used for
creating a score line 2 along the contour of the complex shape that
is to be obtained.
[0107] The suction table 12 is, for example, brought in over the
cutting table 14 as illustrated in FIG. 7b, so as to apply suction
to the sheet of glass 4 via the first face 4A thereof.
[0108] In a third step (FIG. 7c), the local pressure means 10 is
brought against the opposite face 4B of the sheet of glass 4,
opposite the score line 2.
[0109] The suction table 12 may also be configured so that the
offcuts fall off under gravity whereas the complex shape or shapes
that have been cut out remain attached by suction to the suction
table 12 and are carried further thereby, as illustrated by the
right-hand diagram in FIG. 7c.
[0110] However, it will be appreciated that this is simply an
example of a machine and that alternative forms of any suitable
type are conceivable.
[0111] The machine has at least one computer and one memory in
which machine control programs are stored. The programs are able to
control the machine of FIGS. 7a-7c and more particularly to control
the scoring tool 6, the suction table 12 and the local pressure
means 8. The same is true of the other machines in FIGS. 8a-8c,
9a-9c and 10a-10c.
[0112] The machine of FIGS. 7a-7c has the advantage of not
requiring the sheet of glass 4 to be transferred on a conveyor
prior to breaking out and of thus avoiding a geometric readjustment
in order to determine the position of the score line 2, as well as
saving space.
[0113] FIGS. 8a-8c illustrate a machine which itself comprises a
conveyor 18 for transferring the sheet of glass from the location
at which it is scored to the location at which it is broken
out.
[0114] The scoring step in FIG. 8a is similar to that of FIG. 7a.
FIG. 8b illustrates the transfer using the conveyor 18 to the
breaking-out location.
[0115] FIG. 8c illustrates the breaking-out step. In order to avoid
turning the sheet of glass 4 over, a planar-support surface 8 is
applied against the first face 4A. The opposite face 4B against
which the local pressure means 10 is pressed is itself overhanging
so that the region corresponding to the score line 2 is clear of
the support table 20 bearing the sheet of glass 4 by what is said
to be its opposite face 4B.
[0116] As an alternative, it is of course possible to plan to turn
the sheet of glass 4 over as explained hereinabove in relation to
the method. However, a machine according to FIG. 8c also allows the
rigidity and hardness of the planar-support material 8 to be chosen
and adapted more easily.
[0117] FIGS. 9a-9c illustrate an alternative form of the example of
FIGS. 8a-8c, in which alternative form breaking out is performed
through a soft conveyor belt 22 that conveys the sheet of glass. It
should indeed be noted that the local pressure means 10 does not
necessarily need to be in direct contact with the glass.
[0118] Note too that, as an alternative to FIGS. 8a-8c and 9a-9c,
transfer may be performed by a suction table 24.
[0119] This incidentally is what FIG. 10a illustrates.
[0120] However, the machine of FIGS. 10a-10c also differs from the
preceding ones for other reasons. The main difference is that the
sheet of glass is turned during the breaking-out step, while
remaining in its plane, as illustrated by FIG. 10b. This is a
rotation about a normal to the overall plane of the sheet of
glass.
[0121] Furthermore, in FIG. 10b, the support plate 26 supporting
the sheet of glass 4 is flexible enough that the local pressure
means 10 can press against the opposite face 4B through the support
plate 26 and thus break the complex sheet of glass along the
contour of the complex shape. A planar-support means 8 is pressed
firmly against the first face 4A of the sheet of glass, in a
similar way to FIG. 8c.
[0122] The local pressure means 10 is, for example, mounted with
the ability to move in just two dimensions, thanks to the rotation
of the sheet of glass 4.
[0123] FIG. 10c illustrates the separation of the complex shape by
means of a suction table 28. As an alternative, it could use
another means of any suitable type.
[0124] The remainder of the description seeks to explain the
advantages of the invention in terms of the possible configurations
of the production line.
[0125] Before that, the following should be borne in mind.
[0126] The cutting out of glazings of complex shape, i.e. for
example automotive vehicle glazing, is generally performed in two
stages starting from a "large-format" sheet of glass also known as
"PLF" (which stands for "Plateau Large Format") or DLF glass.
[0127] These are sheets of glass of which at least one dimension
corresponds to the width of the ribbon of float glass from which
they are derived. "PLFs" are obtained directly by cross-cutting the
ribbon of float glass. The width of the PLFs corresponds to the
width of the ribbon of float glass. Their length corresponds to the
length of ribbon cut. DLFs are smaller sheets of glass, of which
the length itself corresponds to the width of the ribbon of float
glass. DLFs are obtained directly by cutting the ribbon of float
glass but with a cut length of ribbon that is shorter than the
width of the ribbon of float glass, or alternatively are obtained
by cutting the PLF transversely to the length thereof. Thus, in
practice, PLFs have minimal dimensions of at least 2.9 m by at
least 4.7 m and DLFs have dimensions of at least 2.9 m by at least
1.3 m.
[0128] To manufacture glazing of complex shape, subsequent scoring
steps are needed. Generally sheets of glass 30 of rectangular or
trapezoidal shape and known as "primitives" are first of all cut
from the PLFs or DLFs. These are sheets of glass of which the shape
is a polygon containing the definitive glazing of complex shape 32
that is to be produced, leaving all around the periphery a "trim"
34 that is sufficient for breaking out. This is what is illustrated
in FIG. 11.
[0129] In a second stage, the glazing that is to be edged is cut to
shape at a second scoring workstation which means to say that the
"trims" 34 are cut off over the entire perimeter of the primitive
30 so that the edges of the glazing 32 are now ready for edging.
For that, a number of score lines are, for example, created as
illustrated in FIGS. 2a-2d for an example of a square primitive.
Edging consisting in grinding is then performed later. The
primitives 30 are cut from the PLFs or DLFs at a first scoring
workstation while the ready-to-shape glazings 34 are shaped at a
second scoring workstation. At each scoring workstation: [0130] the
score lines are traced; and [0131] the glass is broken out along
the score lines.
[0132] FIGS. 12a-12b illustrate examples of designs of cutout in
which the continuous lines represent the shape to be cut out which
is ready for shaping while the broken lines represent the score
lines made at the first scoring workstation.
[0133] As illustrated by FIGS. 12a-12b, one advantage of the
invention is that it allows at least some edges of complex shape to
be cut at the first scoring workstation, i.e. at the workstation
that cuts out the primitive 30. Cutting edges that are ready to
shape at the first scoring workstation allows the amount of offcut
to be reduced by avoiding the need to provide "trims" along these
edges.
[0134] In the case of FIG. 12a, certain edges 36 of complex shape
only are cut to their complex shape while others 38 will not be cut
to shape until the second scoring step at the second scoring
workstation.
[0135] In the example of FIG. 12b, the cutting to the shape which
is ready for edging of all the contour of the glazing is carried
out at the first scoring workstation (the entire contour is in a
broken line 36).
[0136] FIGS. 13a-13b illustrate another advantage of the invention,
namely that it allows complex shapes that are to be cut out to be
imbricated. Such a configuration will also reduce offcuts, as will
be appreciated by studying FIGS. 13a and 13b.
[0137] Furthermore, cutting to the shape which is ready for edging
may, as explained hereinabove in respect of FIGS. 12a and 12b,
begin right from the first scoring step at the first scoring
workstation. In FIG. 13a, two of the edges 36 are cut at the first
scoring workstation, known as the "primitives" scoring workstation
even though these are no longer primitives in the strict sense of
the word.
[0138] In FIG. 13b, the cutting to the shape which is ready for
edging on the entire contour of the glazing is performed entirely
at the first scoring workstation, without passing via the step of
scoring "primitives" in a similar way to FIG. 12b.
* * * * *