U.S. patent application number 13/623526 was filed with the patent office on 2013-09-19 for method and apparatus for separating a pane of brittle material from a moving ribbon of the material.
This patent application is currently assigned to CORNING INCORPORATED. The applicant listed for this patent is CORNING INCORPORATED. Invention is credited to Judy Kathleen Cox, Michael Albert Joseph, II, Kenneth Spencer Morgan.
Application Number | 20130240591 13/623526 |
Document ID | / |
Family ID | 37431851 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130240591 |
Kind Code |
A1 |
Cox; Judy Kathleen ; et
al. |
September 19, 2013 |
METHOD AND APPARATUS FOR SEPARATING A PANE OF BRITTLE MATERIAL FROM
A MOVING RIBBON OF THE MATERIAL
Abstract
A pane is separated from a moving ribbon of brittle material by
restraining the ribbon upstream of a score line prior to separating
the pane. The ribbon is restrained by selectively contacting a
first side and a second side of the ribbon in one of an opposite,
overlapping or offset relation. The ribbon can be restrained prior
to, substantially simultaneous with or subsequent to forming the
score line. The restrained status of the ribbon is maintained
during and immediately after separation of the pane from the
ribbon, thereby reducing the introduction of a disturbance or
bending moment into the upstream ribbon.
Inventors: |
Cox; Judy Kathleen;
(Corning, NY) ; Joseph, II; Michael Albert;
(Corning, NY) ; Morgan; Kenneth Spencer; (Painted
Post, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING INCORPORATED |
CORNING |
NY |
US |
|
|
Assignee: |
CORNING INCORPORATED
CORNING
NY
|
Family ID: |
37431851 |
Appl. No.: |
13/623526 |
Filed: |
September 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12483322 |
Jun 12, 2009 |
8292141 |
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13623526 |
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11131125 |
May 17, 2005 |
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12483322 |
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Current U.S.
Class: |
225/2 ;
225/103 |
Current CPC
Class: |
Y10T 225/16 20150401;
Y10T 225/325 20150401; Y10T 225/379 20150401; C03B 33/0215
20130101; Y10T 225/18 20150401; B65G 2249/04 20130101; Y10T 225/371
20150401; B26F 3/002 20130101; Y10T 83/0341 20150401; Y10T 225/321
20150401; Y10T 225/12 20150401 |
Class at
Publication: |
225/2 ;
225/103 |
International
Class: |
C03B 33/033 20060101
C03B033/033 |
Claims
1-16. (canceled)
17. An apparatus for separating a pane from a moving ribbon of
brittle material traveling in a moving direction with a velocity
vector V, the moving ribbon having a first side, a second side and
a width direction substantially orthogonal to the moving direction,
the apparatus comprising: a scoring assembly for forming a score
line in the first side of the moving ribbon of brittle material
along the width direction, the scoring assembly configured to move
at a velocity vector substantially matching the velocity vector V;
a first press bars extending along the width direction and
configured to contact the first sides upstream of a score line at a
velocity vector substantially matching the velocity vector V; a
first backing bar extending along the width direction and
configured to contact the second side along substantially the
entire width of the moving ribbon of brittle material at a velocity
vector substantially matching the velocity vector V; and a second
press bar extending along the width direction configured to contact
the first side downstream of the score line at a velocity vector
substantially matching the velocity vector V.
18. The apparatus of claim 17, wherein the first press bar and the
first backing bar are in an offset relation relative to the draw
direction.
19. The apparatus of claim 17, wherein each of the first press bar
and the first backing bar comprise a cross beam and a polymeric
contact surface.
20. (canceled)
21. The apparatus according to claim 19, wherein the polymeric
contact surface of the first press bar comprises silicone having a
Shore A hardness of 60.+-.10.
22. The apparatus according to claim 19, wherein a hardness of the
polymeric contact surface of the first backing bar is harder than a
hardness of the polymeric hardness of the first press bar.
22. The apparatus according to claim 17, wherein the first press
bar, the second press bar and the first backing bar are connected
to a carriage assembly.
23. The apparatus according to claim 17, wherein the first press
bar and the first backing bar are movable between a retracted
non-contacting position and an extended contacting position
relative to the moving ribbon of brittle material.
24. The apparatus according to claim 17, wherein the first press
bar and the first backing bar overlap in the width direction.
25. The apparatus according to claim 22, further comprising a load
sensor connected between the carriage and at least one of the
respective first press bar, second press bar or first backing bar.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to separating a pane of a
brittle material from a moving ribbon of the material, and in one
configuration, to separating panes of glass from a moving ribbon of
glass, while reducing the introduction of disturbances into the
upstream ribbon.
[0003] 2. Description of Related Art
[0004] Specialized glasses have found increased applicability,
including substrates, in the manufacture of display devices. For
example, liquid crystal displays (LCDs) have become increasingly
popular for displaying information in calculators, watches, video
games, audio and video equipment, portable computers and even car
dashboards. The improving quality and size of LCDs has made the
LCDs an attractive alternative to cathode ray tubes (CRTs) which
are traditionally used in television sets and desktop computer
displays. In addition, other flat panel display (FPD) types, such
as plasma displays (PDs), field emission displays (FEDs) and
organic light-emitting polymer displays (OLEDs) are being developed
as alternatives to LCDs. Thin film transistor liquid crystal
displays (TFT-LCD) are used in notebook computers, flat panel
desktop monitors, LCD televisions, and Internet and communication
devices, to name only a few. It is increasingly useful to
incorporate electronic components onto a glass sheet (glass
substrate) used in the display device. Some display devices such as
TFT-LCD panels and OLED panels are made directly on flat glass
sheets. For example, the transistors are arranged in a patterned
array and are driven by peripheral circuitry to provide (switch on)
desired voltages to orient the molecules of the LC material in the
desired manner.
[0005] In-plane stress (and resulting strain) can result in a
variation of the alignment of the transistors and the pixels. This
can result in distortion in the display panel. As such, in LCD and
other glass display applications, it is exceedingly beneficial to
provide glass (substrates) that are within acceptable tolerances
for distortion.
[0006] Flat panel display manufacturers are finding that demands
for larger display sizes and the economies of scale are driving
manufacturing processes to larger size pieces of glass. Industry
standards have evolved from Gen III (550 mm.times.650 mm), Gen
III.5 (600 mm.times.720 mm), and Gen IV (1,000 mm.times.1,000 mm)
sizes and larger. As the desired size of the glass pieces
increases, the difficulty of the production and handling
increases.
[0007] The manufacturing of the glass used as the substrate is
extremely complex. The drawdown sheet or fusion process, described
in U.S. Pat. No. 3,338,696 (Dockerty) and U.S. Pat. No. 3,682,609
(Dockerty), herein incorporated by reference, is one of the few
processes capable of delivering the glass without requiring costly
post forming finishing operations such as lapping and
polishing.
[0008] However, the fusion process requires the separation and
removal of panes from a continuously moving ribbon of glass.
Traditionally, the separation of the panes has been performed by
forming a separation line in the ribbon of glass. Then a vacuum cup
array is attached to the glass below the score line and the portion
of the ribbon below the score line is rotated less than 15.degree.
to cause the glass to break at the score line and thus form the
desired glass pane. This breaking produces a newly formed leading
edge on the moving ribbon and a newly formed trailing edge on the
glass pane.
[0009] However, this exertion of such a large bending moment on the
ribbon, imparts significant potential energy to the ribbon,
particularly upon the snapping of the pane from the ribbon.
Introduction of this energy (and mechanical disturbance) into the
upstream ribbon can lead to undesirable characteristics in
subsequent glass panes.
[0010] Therefore, there is a need to provide for the separation of
a pane from a continuously moving ribbon of brittle material, while
reducing imparted disturbances which can propagate upstream along
the ribbon. The need also exists for increasing control over the
crack propagation used to separate a pane from the ribbon.
BRIEF SUMMARY OF THE INVENTION
[0011] The present system provides for the repeatable and uniform
separation of a pane of brittle material from a continuously moving
ribbon of the brittle material, while reducing the introduction of
disturbances into the upstream ribbon.
[0012] In selected configurations, the system provides for the
separation of a pane of glass from a continuously moving ribbon of
glass. For purposes of description, the following discussion is set
forth in terms of glass manufacturing. However, it is understood
the invention as defined and set forth in the appended claims is
not so limited, except for those claims which specify the brittle
material is glass.
[0013] In the fusion glass formation process, a glass ribbon
transitions from a liquid state to a downstream solid state. The
introduction of disturbances into the glass in the visco-elastic
region of the glass can result in undesired nonuniformity or
stresses in the resulting solid state glass. Traditionally, the
separation of a pane from the ribbon introduced significant energy
in the form of a vibration, wave or distortion to the solid portion
of the ribbon. Such distortion migrates upstream into the
visco-elastic region of the ribbon. The distortion can introduce
nonuniformity and nonlinearity in an uncontrolled manner, and can
decrease the quality of the resulting panes.
[0014] In the present system, the ribbon is restrained upstream of
a score line prior to separating the pane from the ribbon. The
restraint of the ribbon can be accomplished by contacts upstream of
the score line on the first side and the second side of the ribbon,
wherein the contacts are either opposite, overlapping or offset.
The restraint can be prior to, substantially simultaneous with or
subsequent to forming the score line in the ribbon. The restraint
of the ribbon is selected to facilitate separation of a pane from
the ribbon and minimize or reduce the introduction of a disturbance
or bending moment into the upstream ribbon.
[0015] The present system separates the pane from the ribbon and
reduces the propagation of disturbances upstream in the ribbon by
contacting opposing sides of the ribbon with a pair of opposing
bars, wherein the bars move with the ribbon, thereby restraining a
portion of the ribbon upstream of a score line. A downstream press
bar contacts the ribbon downstream of a score line to separate the
pane from the ribbon along the score line, while the ribbon is
temporarily restrained upstream of the separation line.
[0016] Additional features and advantages of the invention are set
forth in the detailed description which follows, and in part will
be readily apparent to those skilled in the art from that
description or recognized by practicing the invention as described
herein.
[0017] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary of the invention, and are intended to provide an overview
or framework for understanding the nature and character of the
invention as claimed below. Also, the above listed aspects of the
invention, as well as the preferred and other embodiments of the
invention discussed and claimed below, can be used separately or in
any and all combinations.
[0018] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
various embodiments of the invention, and together with the
description serve to explain the principles and operation of the
invention. It should be noted that the various features illustrated
in the figures are not necessarily drawn to scale. In fact, the
dimensions may be arbitrarily increased or decreased for clarity of
discussion.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] FIG. 1 is a schematic view of a fusion glass fabrication
apparatus.
[0020] FIG. 2 is a front elevational schematic view of the ribbon
extending from a fusion glass fabrication apparatus.
[0021] FIG. 3 is a side elevational schematic view of the ribbon
with the upstream press bar and an offset upstream backing bar in a
retracted position.
[0022] FIG. 4 is a side elevational schematic view of the ribbon
with the upstream press bar opposite upstream backing bar in a
retracted position.
[0023] FIG. 5 is a side elevational schematic view of the ribbon
with an overlapping upstream press bar and the upstream backing bar
in a retracted position.
[0024] FIGS. 6a-6d are side elevational schematic views of a first
configuration for the separation of a pane from the ribbon.
[0025] FIGS. 7a-7f are side elevational schematic views of a second
configuration for the separation of a pane from the ribbon.
[0026] FIGS. 8a-8f are side elevational schematic views of a third
configuration for the separation of a pane from the ribbon.
[0027] FIGS. 9a-9f are side elevational schematic views of a fourth
configuration for the separation of a pane from the ribbon.
[0028] FIGS. 10a-10d are side elevational schematic views of the
contact surface of the bars.
DETAILED DESCRIPTION OF THE INVENTION
[0029] In the following detailed description, for purposes of
explanation and not limitation, example embodiments disclosing
specific details are set forth in order to provide a thorough
understanding of the present invention. However, it will be
apparent to one having ordinary skill in the art having had the
benefit of the present disclosure, that the present invention can
be practiced in other embodiments that depart from the specific
details disclosed herein. Moreover, descriptions of well-known
devices, methods and materials are omitted so as not to obscure the
description of the present invention.
[0030] The present invention relates to the separation of a pane of
brittle material from a moving ribbon of the material, wherein
selected configurations reduce separation induced upstream
disturbances to the ribbon. For purposes of description, the
present invention is set forth as separating glass panes from a
moving ribbon of glass.
[0031] FIG. 1 is a schematic diagram of glass fabrication apparatus
10 of the type typically used in the fusion process. Apparatus 10
includes forming isopipe 12, which receives molten glass (not
shown) in cavity 11. The molten glass flows over the upper edges of
cavity 11 and descends along the outer sides of isopipe 12 to root
14 to form ribbon of glass 20. Ribbon of glass 20, after leaving
root 14, traverses fixed edge rollers 16. Ribbon 20 of brittle
material is thus formed and has a length extending from root 14 to
terminal free end 22. As glass ribbon 20 travels down from isopipe
12, the ribbon changes from a supple 50 millimeter thick liquid
form at, for example, root 14 to a stiff glass ribbon of
approximately 0.03 mm to 2.0 mm thickness at terminal end 22.
[0032] Such draw down sheet or fusion processes, are described in
U.S. Pat. No. 3,338,696 (Dockerty) and U.S. Pat. No. 3,682,609
(Dockerty), herein incorporated by reference. The details are
omitted so as to not obscure the description of the example
embodiments. It is noted, however, that other types of glass
fabrication apparatus can be used in conjunction with the
invention. For those skilled in the art of glass forming, it is
known that there are multiple methods to achieve such a structure,
such as laminated down draw, slot draw and laminated fusion
processes.
[0033] For purposes of definition and as best shown in FIG. 3, as
ribbon 20 descends from root 14, the ribbon travels at a velocity
vector V describing movement of the ribbon and forms a generally
flat configuration having a generally planar first side 32 and a
generally planar second side 34. In certain configurations, ribbon
20 includes lateral beads or bulbous portions 36 (shown in FIG. 2)
which are sized for engagement by fixed rollers 16 or control
surfaces during travel of the ribbon from isopipe 12. With respect
to ribbon 20, the terms "opposed" or "opposing" mean the contact on
both first side 32 and second side 34 of the ribbon.
[0034] Depending upon the stage or operation within the sequence,
the term "upstream" means between the intended location of a score
line 26 (or the actual location of the score line) and root 14. The
term "downstream" means between the intended location of score line
26 (or the actual location of the score line) and the terminal end
22 of ribbon 20. Other uses of the terms upstream and downstream
shall refer to the specific location of interest, and mean toward
root 14 or toward terminal end 22 of ribbon 20, respectively.
[0035] The separation of a pane 24 from ribbon 20 occurs within a
given distance range from root 14. That is, under constant
operating parameters, the glass ribbon 20 reaches a generally
predetermined solid state at a generally constant distance from the
root 14, and is thus amenable to separation. The separation of pane
24 from ribbon 20 occurs along score line 26 formed in at least one
side of the ribbon.
[0036] As discussed above in the Summary of the Invention, the
present invention is directed at reducing the levels of undesirable
distortion exhibited when panes 24 or substrates are flattened by
providing for the repeatable and uniform separation of a pane of
brittle material from a continuously moving ribbon 20 of the
brittle material, while reducing the introduction of disturbances
into the upstream ribbon.
[0037] The present apparatus includes upstream press bar 60 (FIG.
3) for engaging first side 32 of ribbon 20 and upstream backing bar
80 for engaging second side 34 of the ribbon. Each of the upstream
press bar 60 and upstream backing bar 80 contact ribbon 20 upstream
of score line 26 to locally restrain the ribbon during and after
separation of pane 24.
[0038] As seen in FIGS. 6-9, in further configurations, downstream
press bar 70, secondary upstream backing bar 90 and downstream
backing bar 100 can be employed.
[0039] Press bars 60, 70 and backing bars 80, 90, 100 are formed of
a cross beam 50 and a contact surface 56, wherein the contact
surface is usually a separate material than the cross beam. Cross
beam 50 is a generally rigid member sufficient to remain
substantially undeformed (undeflected) along the operable length of
the bar during operating conditions. For example, deflections of
less than approximately 0.005 inches and typically less than 0.003
inches along a 5 foot length of cross beam 50 have been found
satisfactory. Aluminum or steel has been found to be a satisfactory
material for cross beams 50. Press bars 60, 70 and backing bars 80,
90, and 100 are sized to extend substantially the entire length of
score line 26, and provide a continuous line of contact with ribbon
20 along the score line.
[0040] The material forming contact surface 56 is a polymeric
material such as a thermoplastic, thermoset or thermoplastic
elastomer. Silicone having a hardness of approximately 60 Shore A
plus or minus 10, has been found a satisfactory material. However,
it is understood that depending upon the configuration of the
apparatus, and the desired characteristics of the interface between
the respective bar and ribbon 20, the performance characteristics
of the material forming contact surface 56 can be changed. For
example, upstream backing bar 80, when also functioning as the
scoring bar, may be formed of a harder surface than upstream press
bar 60.
[0041] Contact surface 56 can be connected to cross beam 50 by any
of a variety of mechanisms including adhesives, bonding or friction
fit. As shown in the FIGS. 6-9 and called out in FIGS. 10a-10d,
cross beam 50 includes a channel 51 having a given cross section,
and contact surface 56 includes a corresponding locking tab 57 for
engaging the channel. Although contact surface 56 is set forth as a
member defining a surface as well as locking tab 57, it is
contemplated the contact surface can be limited to a surface layer
or film disposed on a substrate, wherein the substrate performs the
function of the locking tab.
[0042] Referring to FIGS. 10a-10d, contact surface 56 can define
any of a variety of interfaces with ribbon 20. For example, contact
surface 56 can define an inclined plane with respect to the surface
of ribbon 20. In such configuration, as contact surface 56 engages
ribbon 20, increased force is exerted along predetermined positions
of the contact surface. Contact surface 56 extends along the length
of score line 26 and contact ribbon 20 along an appropriate 1/2''
length of the ribbon.
[0043] Each of the upstream press bar 60, upstream backing bar 80,
downstream press bar 70, secondary upstream backing bar 90 and
downstream backing bar 100 travel at a velocity vector
substantially equal to the velocity vector V of ribbon 20. Press
bars 60, 70 and backing bars 80, 90 and 100 are carried by a
carriage 120 for translation with the appropriate velocity vector
matching ribbon 20, as is known in the art.
[0044] For purposes of description, press bars 60, 70 and backing
bars 80, 90, 100 are described in terms of travel on common
carriage 120. Carriage 120 can be movable relative to a rail 124,
wherein the movement of the carriage can be imparted by any of a
variety of mechanisms including magnetic, mechanical, or
electromechanical, such as motors, gears, and/or rack and pinion.
Thus, press bars 60, 70 and backing bars 80, 90, 100 can be moved
with the same velocity vector V of ribbon 20, and upon contact with
the ribbon maintain contact at a specific location on the
ribbon.
[0045] In certain configurations, upstream backing bar 80 also
functions as a score-nosing bar, without deviating from the present
apparatus. That is, as seen in FIGS. 6-9, upstream backing bar 80
contacts second side 34 of ribbon 20 upstream of score line 26, as
well as contacting the second side of the ribbon opposite the score
line (or the intended position of the score line).
[0046] As shown schematically in FIGS. 3-5, upstream press bar 60
is connected to carriage 120 for engaging first side 32 of ribbon
20 and the upstream backing bar is connected to the carriage for
engaging second side 34 of the ribbon to restrain the ribbon.
[0047] Upstream press bar 60 and upstream backing bar 80 can
contact the opposing sides of ribbon 20 in an opposite, an offset,
or overlapping relation. In the "opposite" relation seen in FIG. 4,
upstream press bar 60 and upstream backing bar 80 engage ribbon 20
at a common distance from root 14. For ribbon 20 having a vertical
velocity vector V, the opposite contact occurs at a given height
(vertical position along the ribbon). In the "offset" relation seen
in FIG. 3, upstream press bar 60 and upstream backing bar 80 engage
ribbon 20 at different distances from root 14. That is, there is no
common length of the ribbon contacted on first side 32 by upstream
press bar 60 and second side 34 by upstream backing bar 80. In the
"overlapping" relation seen in FIG. 5, a portion of each of the
upstream press bar 60 and upstream backing bar 80 contact the
respective side of ribbon 20 along a common length of the ribbon.
For example, in the overlapping relation, if each of the upstream
press bar 60 and upstream backing bar 80 has a 1/2'' contact with
the ribbon approximately 1/4'' of the contact of each of the
upstream press bar and the upstream backing bar can overlap along a
common 1/4'' length of the ribbon to restrain the ribbon.
[0048] Upstream press bar 60 and upstream backing bar 80 can be
controlled to simultaneously or sequentially contact the respective
sides of ribbon 20. However, it is advantageous to have both
upstream press bar 60 and upstream backing bar 80 contacting ribbon
20, during and after separation of pane 24.
[0049] Upstream press bar 60 and upstream backing bar 80 can be
movably connected to carriage 120 for movement between a retracted
non-ribbon contacting position and an extended ribbon contacting
position. Any of a variety of mechanisms can be used for moving
upstream press bar 60 and upstream backing bar 80 relative to
carriage 120. For example, cams can couple bars 60, 80 to carriage
120. Alternatively, mechanical actuators such as rack and pinion or
threaded engagements, hydraulic or pneumatic pistons or cylinders
can be used.
[0050] Thus, upstream press bar 60 and upstream backing bar 80 can
move relative to carriage 120 between a retracted non-contacting
position and an extended ribbon contacting position. Alternatively,
upstream press bar 60 and upstream backing bar 80 can be fixed with
respect to carriage 120, and the carriage can be moved relative to
rail 124 to selectively engage the bars with ribbon 20.
[0051] In selected configurations, as seen in FIGS. 6a-6d, upstream
press bar 60 and downstream press bar 70 can be incorporated into a
single cross beam 50, and thus move in concert. Alternatively,
upstream press bar 60 and downstream press bar 80 can be tied to a
common carrier or yoke. Conversely, upstream press bar 60 and
downstream press bar 70 can be independently controlled (operated)
to provide sequential or independent contact with ribbon 20 as seen
in FIGS. 7-9.
[0052] Similarly, upstream backing bar 80, secondary upstream
backing bar 90 and downstream backing bar 100 can be carried by
single cross beam 50 to move in concert between the retracted
position and the extended position. Alternatively, each of the
upstream backing bar 80, secondary upstream backing bar 90, and
downstream backing bar 100 can be carried by an independent and
independently actuated cross beam 50, as desired.
[0053] In one configuration, press bars 60, 70 and scoring assembly
130 contact first side 32 of ribbon 20 within an approximate 3 inch
length of the ribbon. Thus, for those configurations in which score
line 26 is equally spaced from the upstream press bar and
downstream press bar, the bars are within approximately 1.5 inches
from the score line.
[0054] Similarly, upstream backing bar 80, secondary upstream
backing bar 90 and downstream backing bar 100 span approximately 3
inches or less along the length of the ribbon 20. In certain
configurations, upstream press bar 60 can be within 2 inches or
less than 1 inch from score line 26. Downstream press bar 70 can be
less than 3 inches to less than approximately 1 inch from score
line 26. In one configuration bars 60, 70 are located within a 37
mm length of ribbon 20.
[0055] Load sensors or force sensors, such as piezoelectric or
spring biased sensors, can be connected between respective bar 60,
70, 80, 90, 100 and carriage 120 to measure the load on the
respective bar. The sensors are connected to a central controller
so that the desired loads can be determined, monitored and
controlled.
[0056] A scoring assembly 130 is used to selectively form score
line 26 in first side 32 of ribbon 20. Scoring assembly 130 can
travel with one or both upstream press bar 60 and upstream backing
bar 80. For purposes of description, scoring assembly 130 is set
forth as carried by carriage 120. Thus, scoring assembly 130 will
travel along the direction of travel of ribbon 20, at a velocity
vector matching the ribbon. As scoring assembly 130 translates
along the same direction of travel as ribbon 20, score line 26 can
be formed to extend transverse to the direction of travel of the
ribbon.
[0057] Scoring assembly 130 can be any of a variety of
configurations well known in the glass scribing art, including but
not limited to lasers, wheels, or points.
[0058] For those configurations of scoring assembly 130 that
require contact with ribbon 20 to form score line 26, the scoring
assembly is also movable between a retracted non-contacting
position and an extended ribbon contacting position.
[0059] Typically, scoring assembly 130 cooperates with upstream
backing bar 80 to form the score line 26 along first surface 32 of
ribbon 20, such that the upstream backing bar also functions as a
scoring bar opposite the contact of scoring assembly 130 and ribbon
20.
[0060] Score line 26 extends across a substantial width of ribbon
20. For the configuration of ribbon 20 having beads 36, score line
26 extends substantially the entire distance between the beads.
Thus, the score line can extend from approximately 70% of the width
of ribbon 20 to 100% of the width. Typically, score line 26 has a
depth of approximately 10% of the thickness of ribbon 20. The
actual depth of score line 26 depends in part upon scoring
parameters such as scoring pressure, the geometry of the scoring
assembly, the thickness of the ribbon, the material of the ribbon,
and the characteristics of glass fabrication apparatus 10. For
representative ribbon thickness, score line 26 can have a depth
ranging from approximately 70 microns to approximately 130
microns.
[0061] A pane engaging assembly 140 is employed to capture ribbon
20 downstream of score line 26 and control removal of pane 24 upon
separation from ribbon 20. A representative pane engaging assembly
and associated transporter are described in U.S. Pat. No.
6,616,025, herein expressly incorporated by reference.
[0062] The pane engaging assembly 140 includes pane engaging
members 142, such as soft vacuum suction cups. It is understood
other devices for engaging pane 24, such as clamps or fingers that
engage the lateral edge of the ribbon (pane) can be used. The
number of pane engaging members 142 can be varied in response to
the size, thickness and weight of pane 24.
[0063] Pane engaging assembly 140 can engage ribbon 20 either
before or after score line 26 has been formed. In addition, pane
engaging assembly 140 can include a drop cylinder for imparting a
vertical movement of pane 24 from newly formed terminal end 22 of
ribbon 20.
[0064] With respect to separation of pane 24 from ribbon 20 along
score line 26, a combination of the bars contacting the ribbon is
employed to propagate a crack along the score line. Any of a
variety of combination of contacts between the bars and ribbon 20
can be employed to separate pane 24. For example, it is
contemplated downstream press bar 70 can be employed to provide a
breaking function (function as a breaking bar). Alternatively, both
upstream press bar 60 and downstream press bar 70 can act
cooperatively against ribbon 20 to induce separation along score
line 26.
[0065] Generally, upper press bar 60 and upper backing bar 80
restrain a portion of ribbon 20 therebetween. By restraining the
portion of ribbon 20, deviation of the ribbon from the gravity
induced velocity vector is reduced. In addition, restraining a
portion of ribbon 20 upstream of score line 26 allows the dampening
characteristics of contact surfaces 56 to reduce the transmission
of disturbances (energy) into the ribbon.
[0066] In contrast to prior systems, a localized bending is applied
about score line 26, wherein the localized bending is sufficient to
propagate a crack along the score line.
[0067] The contact of upstream press bar 60, upstream backing bar
80 (and secondary upstream backing bar 100) during and immediately
after separation of pane 24 from ribbon 20, function to dampen the
transmission of mechanical vibrations upstream in the ribbon. Thus,
movement of ribbon 20 above score line 26 is thus reduced during
the separation process. The continued contact between upstream
backing bar 80 and upstream press bar 60 with ribbon 20 after
separation absorbs a portion of the energy imparted by the
separation process, and thus reduces the amount of disturbance that
can migrate upstream in the ribbon.
[0068] In addition, by locating continuous lines of contact from
the respective bars proximal to score line 26, such as within 3
inches (7.6 cm), a more uniform energy distribution is applied
across ribbon 20 in the location of the score line, thereby
improving separation characteristics of pane 24. It is believed
accuracy of the separation line with respect to score line 26 is
increased as bars 60, 80 (and 70) provide a more uniform stress
along the length of the score line. This allows the position of
score line 26 to vary by as much as 1 mm without sacrificing
efficiency of the separation process.
[0069] Press bars 60, 70 and backing bars 80, 90, 100 can also be
employed to substantially maintain (or create) a substantially
planar configuration of the ribbon in the area of score line 26
before or after formation of the score line.
[0070] For purposes of illustration, four different specific
arrangements of upper press bar 60 and upper backing bar 80
contacting ribbon 20 are set forth in detail.
[0071] Referring to FIGS. 6a-6d, a first configuration of the
assembly is employed to separate pane 24 from terminal end 22 of
ribbon 20. As seen in FIG. 6a, upstream backing bar 80 is brought
to contact second side 34 of ribbon 20 and scoring assembly 130 is
drawn across at least a portion of the width of the ribbon to form
score line 26. Pane engaging assembly 140 is shown engaged with
ribbon 20, prior to formation of score line 26. However, it is
understood that the pane engaging assembly can engage ribbon 20
after formation of score line 26. Referring to FIG. 6b, upstream
backing bar 80 functions as the score-nosing bar or anvil. Although
scoring assembly 130 is shown as returning to an upstream position
relative to upstream press bar 60, it is understood the scoring
assembly can move laterally (horizontally in FIG. 6b) between a
scoring position and a non scoring position. Subsequently to the
formation of score line 26, upstream press bar 60 and downstream
press bar 70 are brought into contact with first side 32 of ribbon
20 to locate score line 26 intermediate the upstream press bar and
the downstream press bar and restrain a portion of the ribbon
upstream of score line 26 by the contact of upstream backing bar 80
and the upstream press bar with the ribbon. Upstream press bar 60
and upstream backing bar 80 can be sized and located to contact
ribbon 20 and either an offset, overlapping or opposite relation.
Further, although upstream press bar 60 and downstream press bar 70
are shown as incorporated into single crossbeam 50, each press bar
is called out as an individual structure. That is, each of the
upstream press bar 60 and downstream press bar 70 can encompass
respective contact surface 56 and a portion of the common crossbeam
50.
[0072] In FIG. 6c, upstream press bar 60 and downstream press bar
70 are urged towards upstream backing bar 80, while pane engaging
assembly 140 draws the ribbon from the vertical path and ribbon 20
is separated along score line 26. It is understood, upstream press
bar 60 can contact ribbon 20 simultaneous with contact of
downstream press bar 70, or prior to contact of the downstream
press bar with the ribbon. In either scenario, a portion of ribbon
20 is restrained between upstream press bar 60 and a portion of
upstream backing bar 80, such that the ribbon remains restrained
upstream of the separation line, after separation of the
ribbon.
[0073] In FIG. 6d, upstream press bar 60, downstream press bar 70,
upstream backing bar 80, and scoring assembly 130 are realigned
with ribbon 20 for forming subsequent pane 24.
[0074] It is also noted that upon upstream press bar 60 and
upstream backing bar 80 having at least a slight overlapping
relation along the length of ribbon 20, the application of a
bending moment to upstream ribbon 20 is reduced. The amount of
overlap of upstream press bar 60 and upstream backing bar 80 is at
least partially determined by the type and thickness of material
forming ribbon 20.
[0075] Referring to FIG. 7a, upstream backing bar 80 and at least
upstream press bar 60 are brought into contact with ribbon 20,
prior to forming score line 26 (and thus restrain the ribbon).
Again, pane engaging assembly 140 is engaged with ribbon 20 prior
to formation of the score line. However, it is understood that pane
engaging assembly 140 can engage ribbon 20 after formation of score
line 26. In FIG. 7b, scoring assembly 130 is brought into contact
with first side 32 of ribbon 20 and bears against a portion of
backing bar 80 to form score line 26. In FIG. 7c, scoring assembly
130 is retracted. In FIG. 7d, the downstream press bar 70 is urged
against first side 32 of ribbon 20 to separate pane 24 from the
ribbon. In FIG. 7e, downstream press bar 70 and scoring assembly
130 are in the retracted position, while upstream backing bar 80
and upstream press bar 60 remain in contact with ribbon 20, thereby
dampening the transmission of any disturbance resulting from the
separation of pane 24 from the ribbon. In FIG. 7f, the bars are
returned to an initial position for separating a subsequent pane 24
from ribbon 20.
[0076] Again, the relation of upstream backing bar 80 and upstream
press bar 60 (and downstream press bar 70) can be offset, opposite
or overlapping. Although upstream press bar 60 and downstream press
bar 70 can be simultaneously moved into contact with first side 32
of ribbon 20, and simultaneously moved after formation of score
line 26 to separate pane 24, it is anticipated that independently
moving the downstream press bar to initiate crack propagation along
the score line is advantageous.
[0077] Referring to FIG. 8a, secondary upstream backing bar 90 and
upstream press bar 80 are initially brought into contact with
second side 34 and first side 32 of ribbon 20 respectively. In
addition, downstream press bar 70 can optionally contact the first
side of ribbon 20 to further stabilize and control the ribbon. In
FIG. 8b, upstream backing bar 80 and scoring assembly 130 are
brought into contact with ribbon 20 to form score line 26
intermediate upstream press bar 60 and downstream press bar 70. A
portion of upstream backing bar 80 contacts second side 34 of
ribbon 20 upstream of score line 26. Thus, ribbon 20 is restrained
upstream of score line 26 by a portion of upstream backing bar 80
and secondary upstream backing bar 90 on second side 34 of the
ribbon and upstream press bar 60 on first side 32 of the ribbon.
Pane engaging assembly 140 engages ribbon 20. In FIG. 8c, scoring
assembly 130 is retracted after score line 26 is formed. In FIG.
8d, downstream press bar 70 is urged further against first side 32
of ribbon 20 causing pane 24 to separate from the ribbon. In FIG.
8e, separated pane 24 is removed by pane engaging assembly 140, and
newly formed terminal end 22 of the ribbon is restrained by a
portion of upstream backing bar 80, secondary upstream backing bar
100 and upstream press bar 60. In FIG. 8f, the bars are returned to
a ready position to begin the sequence for separating a subsequent
pane 24 from ribbon 20.
[0078] With respect to the series of FIG. 9, the configuration is
selected to reduce premature unintended crack propagation along
score line 26. Generally, the configuration of FIG. 9 induces a
local compression in first side 32 of ribbon 20 adjacent the score
line 26. This local compressive force reduces the tendency of crack
propagation along score line 26. The bar configuration shown in
FIG. 9, provides for the initial compression and a subsequent
tension across score line 26, and hence controlled crack
propagation.
[0079] In the series of FIG. 9, pane engaging assembly 140 is
employed to capture pane 24 and remove the pane from descending
ribbon 20. As seen in FIG. 9a, upstream backing bar 80, secondary
upstream backing bar 90 and downstream backing bar 100 are mounted
in a common crossbeam 50, wherein the secondary upstream backing
bar and the downstream backing bar project a greater distance than
the upstream backing bar. That is, upstream backing bar 80 is
recessed relative to secondary upstream backing bar 90 and
downstream backing bar 100, so that second side 34 of ribbon 20
initially contacts the secondary upstream backing bar and the
downstream backing bar. Although secondary upstream backing bar 90
and downstream backing bar 100 can be of a softer, more easily
compressible material than upstream backing bar 80, as upstream
press bar 60 contacts first side 32 of ribbon 20, a slight bow is
imposed in the ribbon such that a local compressive force is
created in the intended area of score line 26.
[0080] Although upstream backing bar 80 can be separately
controlled from secondary upstream backing bar 90 and downstream
backing bar 100, the apparatus is simplified by mounting upstream
backing bar 80, secondary upstream backing bar 90 and downstream
backing bar 100 to a common crossbeam 50, and employing different
size contact surfaces 56.
[0081] Referring to FIG. 9b, scoring assembly 130 then forms score
line 26 in the locally compressed first side 32 of ribbon 20.
Subsequently, as seen in FIG. 9c, scoring assembly 130 is
retracted, and downstream press bar 70 is urged against the first
side of ribbon 20 with sufficient force to generate a localized
tension in the first side of the ribbon in the area of score line
26. Pane 24 then separates from ribbon 20 as seen in FIG. 9d while
ribbon 20 remains restrained between secondary upstream backing bar
90 and upstream backing bar 80 on second side 34, and upstream
press bar 60 on the first side. Pane engaging assembly 140 removes
pane 24 in FIG. 9d. Referring to FIG. 9f, the bars and scoring
assembly 130 are returned to the ready position for separating a
subsequent pane 24.
[0082] The present configurations thus provide for an opposed
contact of ribbon 20 upstream of score line 26 (or score line
location), wherein the upstream opposed contact can be in an
offset, opposite or overlapping relation of upstream press bar 60
and upstream backing bar 80.
[0083] Subsequently, crack propagation is induced along score line
26 and pane 24 is separated from ribbon 20.
[0084] The upstream contact with ribbon 20 is maintained during and
after the separation of pane 24, thereby reducing the introduction
of disturbances that can migrate up the ribbon.
[0085] In certain configurations, the upstream restraining of
ribbon 20 can be subsequent to formation of score line 26 and
substantially simultaneous with the separating of the ribbon along
the score line. In further configurations, the upstream restraining
of ribbon 20 precedes the formation of score line 26.
[0086] While the invention has been described in conjunction with
specific exemplary embodiments thereof, it is evident that many
alternatives, modifications, and variations will be apparent to
those skilled in the art in light of the foregoing description.
Accordingly, the present invention is intended to embrace all such
alternatives, modifications, and variations as fall within the
spirit and broad scope of the appended claims.
* * * * *