US20060261118A1 - Method and apparatus for separating a pane of brittle material from a moving ribbon of the material - Google Patents

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.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• 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.
• 2. Description of Related Art
• 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.
• 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.
• 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×650 mm), Gen III.5 (600 mm×720 mm), and Gen IV (1,000 mm×1,000 mm) sizes and larger. As the desired size of the glass pieces increases, the difficulty of the production and handling increases.
• 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.
• 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° 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.
• 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.
• 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
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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
• FIG. 1 is a schematic view of a fusion glass fabrication apparatus.
• FIG. 2 is a front elevational schematic view of the ribbon extending from a fusion glass fabrication apparatus.
• 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.
• FIG. 4 is a side elevational schematic view of the ribbon with the upstream press bar opposite upstream backing bar in a retracted position.
• 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.
• FIGS. 6a-6dare side elevational schematic views of a first configuration for the separation of a pane from the ribbon.
• FIGS. 7a-7fare side elevational schematic views of a second configuration for the separation of a pane from the ribbon.
• FIGS. 8a-8fare side elevational schematic views of a third configuration for the separation of a pane from the ribbon.
• FIGS. 9a-9fare side elevational schematic views of a fourth configuration for the separation of a pane from the ribbon.
• FIGS. 10a-10dare side elevational schematic views of the contact surface of the bars.
DETAILED DESCRIPTION OF THE INVENTION
• 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.
• 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.
• FIG. 1 is a schematic diagram ofglass fabrication apparatus10 of the type typically used in the fusion process.Apparatus10 includes formingisopipe12, which receives molten glass (not shown) incavity11. The molten glass flows over the upper edges ofcavity11 and descends along the outer sides ofisopipe12 to root14 to form ribbon ofglass20. Ribbon ofglass20, after leavingroot14, traverses fixededge rollers16.Ribbon20 of brittle material is thus formed and has a length extending fromroot14 to terminalfree end22. Asglass ribbon20 travels down fromisopipe12, the ribbon changes from a supple 50 millimeter thick liquid form at, for example, root14 to a stiff glass ribbon of approximately 0.03 mm to 2.0 mm thickness atterminal end22.
• 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.
• For purposes of definition and as best shown inFIG. 3, asribbon20 descends fromroot14, the ribbon travels at a velocity vector V describing movement of the ribbon and forms a generally flat configuration having a generally planarfirst side32 and a generally planarsecond side34. In certain configurations,ribbon20 includes lateral beads or bulbous portions36 (shown inFIG. 2) which are sized for engagement by fixedrollers16 or control surfaces during travel of the ribbon fromisopipe12. With respect toribbon20, the terms “opposed” or “opposing” mean the contact on bothfirst side32 andsecond side34 of the ribbon.
• Depending upon the stage or operation within the sequence, the term “upstream” means between the intended location of a score line26 (or the actual location of the score line) androot14. The term “downstream” means between the intended location of score line26 (or the actual location of the score line) and theterminal end22 ofribbon20. Other uses of the terms upstream and downstream shall refer to the specific location of interest, and mean towardroot14 or towardterminal end22 ofribbon20, respectively.
• The separation of apane24 fromribbon20 occurs within a given distance range fromroot14. That is, under constant operating parameters, theglass ribbon20 reaches a generally predetermined solid state at a generally constant distance from theroot14, and is thus amenable to separation. The separation ofpane24 fromribbon20 occurs alongscore line26 formed in at least one side of the ribbon.
• As discussed above in the Summary of the Invention, the present invention is directed at reducing the levels of undesirable distortion exhibited whenpanes24 or substrates are flattened by providing for the repeatable and uniform separation of a pane of brittle material from a continuously movingribbon20 of the brittle material, while reducing the introduction of disturbances into the upstream ribbon.
• The present apparatus includes upstream press bar60 (FIG. 3) for engagingfirst side32 ofribbon20 andupstream backing bar80 for engagingsecond side34 of the ribbon. Each of theupstream press bar60 andupstream backing bar80contact ribbon20 upstream ofscore line26 to locally restrain the ribbon during and after separation ofpane24.
• As seen inFIGS. 6-9, in further configurations,downstream press bar70, secondaryupstream backing bar90 anddownstream backing bar100 can be employed.
• Press bars60,70 and backing bars80,90,100 are formed of across beam50 and acontact surface56, wherein the contact surface is usually a separate material than the cross beam.Cross beam50 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 ofcross beam50 have been found satisfactory. Aluminum or steel has been found to be a satisfactory material for cross beams50. Press bars60,70 and backing bars80,90, and100 are sized to extend substantially the entire length ofscore line26, and provide a continuous line of contact withribbon20 along the score line.
• The material formingcontact surface56 is a polymeric material such as a thermoplastic, thermoset or thermoplastic elastomer. Silicone having a hardness of approximately 60 Shore A plus orminus10, 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 andribbon20, the performance characteristics of the material formingcontact surface56 can be changed. For example,upstream backing bar80, when also functioning as the scoring bar, may be formed of a harder surface thanupstream press bar60.
• Contact surface56 can be connected to crossbeam50 by any of a variety of mechanisms including adhesives, bonding or friction fit. As shown in theFIGS. 6-9 and called out inFIGS. 10a-10d,cross beam50 includes achannel51 having a given cross section, andcontact surface56 includes acorresponding locking tab57 for engaging the channel. Althoughcontact surface56 is set forth as a member defining a surface as well as lockingtab57, 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.
• Referring toFIGS. 10a-10d,contact surface56 can define any of a variety of interfaces withribbon20. For example,contact surface56 can define an inclined plane with respect to the surface ofribbon20. In such configuration, ascontact surface56 engagesribbon20, increased force is exerted along predetermined positions of the contact surface.Contact surface56 extends along the length ofscore line26 andcontact ribbon20 along an appropriate ½″ length of the ribbon.
• Each of theupstream press bar60,upstream backing bar80,downstream press bar70, secondaryupstream backing bar90 anddownstream backing bar100 travel at a velocity vector substantially equal to the velocity vector V ofribbon20. Press bars60,70 and backing bars80,90 and100 are carried by acarriage120 for translation with the appropriate velocityvector matching ribbon20, as is known in the art.
• For purposes of description, press bars60,70 and backing bars80,90,100 are described in terms of travel oncommon carriage120.Carriage120 can be movable relative to arail124, 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 bars60,70 and backing bars80,90,100 can be moved with the same velocity vector V ofribbon20, and upon contact with the ribbon maintain contact at a specific location on the ribbon.
• In certain configurations,upstream backing bar80 also functions as a score-nosing bar, without deviating from the present apparatus. That is, as seen inFIGS. 6-9,upstream backing bar80 contactssecond side34 ofribbon20 upstream ofscore line26, as well as contacting the second side of the ribbon opposite the score line (or the intended position of the score line).
• As shown schematically inFIGS. 3-5,upstream press bar60 is connected tocarriage120 for engagingfirst side32 ofribbon20 and the upstream backing bar is connected to the carriage for engagingsecond side34 of the ribbon to restrain the ribbon.
• Upstream press bar60 andupstream backing bar80 can contact the opposing sides ofribbon20 in an opposite, an offset, or overlapping relation. In the “opposite” relation seen inFIG. 4,upstream press bar60 andupstream backing bar80 engageribbon20 at a common distance fromroot14. Forribbon20 having a vertical velocity vector V, the opposite contact occurs at a given height (vertical position along the ribbon). In the “offset” relation seen inFIG. 3,upstream press bar60 andupstream backing bar80 engageribbon20 at different distances fromroot14. That is, there is no common length of the ribbon contacted onfirst side32 byupstream press bar60 andsecond side34 byupstream backing bar80. In the “overlapping” relation seen inFIG. 5, a portion of each of theupstream press bar60 andupstream backing bar80 contact the respective side ofribbon20 along a common length of the ribbon. For example, in the overlapping relation, if each of theupstream press bar60 andupstream backing bar80 has a ½″ contact with the ribbon approximately ¼″ of the contact of each of the upstream press bar and the upstream backing bar can overlap along a common ¼″ length of the ribbon to restrain the ribbon.
• Upstream press bar60 andupstream backing bar80 can be controlled to simultaneously or sequentially contact the respective sides ofribbon20. However, it is advantageous to have bothupstream press bar60 andupstream backing bar80 contactingribbon20, during and after separation ofpane24.
• Upstream press bar60 andupstream backing bar80 can be movably connected tocarriage120 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 movingupstream press bar60 andupstream backing bar80 relative tocarriage120. For example, cams can couple bars60,80 tocarriage120. Alternatively, mechanical actuators such as rack and pinion or threaded engagements, hydraulic or pneumatic pistons or cylinders can be used.
• Thus,upstream press bar60 andupstream backing bar80 can move relative tocarriage120 between a retracted non-contacting position and an extended ribbon contacting position. Alternatively,upstream press bar60 andupstream backing bar80 can be fixed with respect tocarriage120, and the carriage can be moved relative to rail124 to selectively engage the bars withribbon20.
• In selected configurations, as seen inFIGS. 6a-6d,upstream press bar60 anddownstream press bar70 can be incorporated into asingle cross beam50, and thus move in concert. Alternatively,upstream press bar60 anddownstream press bar80 can be tied to a common carrier or yoke. Conversely,upstream press bar60 anddownstream press bar70 can be independently controlled (operated) to provide sequential or independent contact withribbon20 as seen inFIGS. 7-9.
• Similarly,upstream backing bar80, secondaryupstream backing bar90 anddownstream backing bar100 can be carried bysingle cross beam50 to move in concert between the retracted position and the extended position. Alternatively, each of theupstream backing bar80, secondaryupstream backing bar90, anddownstream backing bar100 can be carried by an independent and independently actuatedcross beam50, as desired.
• In one configuration, press bars60,70 and scoringassembly130 contactfirst side32 ofribbon20 within an approximate 3 inch length of the ribbon. Thus, for those configurations in which scoreline26 is equally spaced from the upstream press bar and downstream press bar, the bars are within approximately 1.5 inches from the score line.
• Similarly,upstream backing bar80, secondaryupstream backing bar90 anddownstream backing bar100 span approximately 3 inches or less along the length of theribbon20. In certain configurations,upstream press bar60 can be within 2 inches or less than 1 inch fromscore line26.Downstream press bar70 can be less than 3 inches to less than approximately 1 inch fromscore line26. In one configuration bars60,70 are located within a 37 mm length ofribbon20.
• Load sensors or force sensors, such as piezoelectric or spring biased sensors, can be connected betweenrespective bar60,70,80,90,100 andcarriage120 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.
• A scoringassembly130 is used to selectively formscore line26 infirst side32 ofribbon20. Scoringassembly130 can travel with one or bothupstream press bar60 andupstream backing bar80. For purposes of description, scoringassembly130 is set forth as carried bycarriage120. Thus, scoringassembly130 will travel along the direction of travel ofribbon20, at a velocity vector matching the ribbon. As scoringassembly130 translates along the same direction of travel asribbon20,score line26 can be formed to extend transverse to the direction of travel of the ribbon.
• Scoringassembly130 can be any of a variety of configurations well known in the glass scribing art, including but not limited to lasers, wheels, or points.
• For those configurations of scoringassembly130 that require contact withribbon20 to formscore line26, the scoring assembly is also movable between a retracted non-contacting position and an extended ribbon contacting position.
• Typically, scoringassembly130 cooperates withupstream backing bar80 to form thescore line26 alongfirst surface32 ofribbon20, such that the upstream backing bar also functions as a scoring bar opposite the contact of scoringassembly130 andribbon20.
• Score line26 extends across a substantial width ofribbon20. For the configuration ofribbon20 havingbeads36,score line26 extends substantially the entire distance between the beads. Thus, the score line can extend from approximately 70% of the width ofribbon20 to 100% of the width. Typically,score line26 has a depth of approximately 10% of the thickness ofribbon20. The actual depth ofscore line26 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 ofglass fabrication apparatus10. For representative ribbon thickness,score line26 can have a depth ranging from approximately 70 microns to approximately 130 microns.
• Apane engaging assembly140 is employed to captureribbon20 downstream ofscore line26 and control removal ofpane24 upon separation fromribbon20. A representative pane engaging assembly and associated transporter are described in U.S. Pat. No. 6,616,025, herein expressly incorporated by reference.
• Thepane engaging assembly140 includespane engaging members142, such as soft vacuum suction cups. It is understood other devices for engagingpane24, such as clamps or fingers that engage the lateral edge of the ribbon (pane) can be used. The number ofpane engaging members142 can be varied in response to the size, thickness and weight ofpane24.
• Pane engaging assembly140 can engageribbon20 either before or afterscore line26 has been formed. In addition,pane engaging assembly140 can include a drop cylinder for imparting a vertical movement ofpane24 from newly formedterminal end22 ofribbon20.
• With respect to separation ofpane24 fromribbon20 alongscore line26, 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 andribbon20 can be employed toseparate pane24. For example, it is contemplateddownstream press bar70 can be employed to provide a breaking function (function as a breaking bar). Alternatively, bothupstream press bar60 anddownstream press bar70 can act cooperatively againstribbon20 to induce separation alongscore line26.
• Generally,upper press bar60 andupper backing bar80 restrain a portion ofribbon20 therebetween. By restraining the portion ofribbon20, deviation of the ribbon from the gravity induced velocity vector is reduced. In addition, restraining a portion ofribbon20 upstream ofscore line26 allows the dampening characteristics of contact surfaces56 to reduce the transmission of disturbances (energy) into the ribbon.
• In contrast to prior systems, a localized bending is applied aboutscore line26, wherein the localized bending is sufficient to propagate a crack along the score line.
• The contact ofupstream press bar60, upstream backing bar80 (and secondary upstream backing bar100) during and immediately after separation ofpane24 fromribbon20, function to dampen the transmission of mechanical vibrations upstream in the ribbon. Thus, movement ofribbon20 abovescore line26 is thus reduced during the separation process. The continued contact betweenupstream backing bar80 andupstream press bar60 withribbon20 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.
• In addition, by locating continuous lines of contact from the respective bars proximal to scoreline26, such as within 3 inches (7.6 cm), a more uniform energy distribution is applied acrossribbon20 in the location of the score line, thereby improving separation characteristics ofpane24. It is believed accuracy of the separation line with respect to scoreline26 is increased asbars60,80 (and70) provide a more uniform stress along the length of the score line. This allows the position ofscore line26 to vary by as much as 1 mm without sacrificing efficiency of the separation process.
• Press bars60,70 and backing bars80,90,100 can also be employed to substantially maintain (or create) a substantially planar configuration of the ribbon in the area ofscore line26 before or after formation of the score line.
• For purposes of illustration, four different specific arrangements ofupper press bar60 andupper backing bar80 contactingribbon20 are set forth in detail.
• Referring toFIGS. 6a-6d, a first configuration of the assembly is employed toseparate pane24 fromterminal end22 ofribbon20. As seen inFIG. 6a,upstream backing bar80 is brought to contactsecond side34 ofribbon20 and scoringassembly130 is drawn across at least a portion of the width of the ribbon to formscore line26.Pane engaging assembly140 is shown engaged withribbon20, prior to formation ofscore line26. However, it is understood that the pane engaging assembly can engageribbon20 after formation ofscore line26. Referring toFIG. 6b,upstream backing bar80 functions as the score-nosing bar or anvil. Although scoringassembly130 is shown as returning to an upstream position relative toupstream press bar60, it is understood the scoring assembly can move laterally (horizontally inFIG. 6b) between a scoring position and a non scoring position. Subsequently to the formation ofscore line26,upstream press bar60 anddownstream press bar70 are brought into contact withfirst side32 ofribbon20 to locatescore line26 intermediate the upstream press bar and the downstream press bar and restrain a portion of the ribbon upstream ofscore line26 by the contact ofupstream backing bar80 and the upstream press bar with the ribbon.Upstream press bar60 andupstream backing bar80 can be sized and located to contactribbon20 and either an offset, overlapping or opposite relation. Further, althoughupstream press bar60 anddownstream press bar70 are shown as incorporated intosingle crossbeam50, each press bar is called out as an individual structure. That is, each of theupstream press bar60 anddownstream press bar70 can encompassrespective contact surface56 and a portion of thecommon crossbeam50.
• InFIG. 6c,upstream press bar60 anddownstream press bar70 are urged towardsupstream backing bar80, whilepane engaging assembly140 draws the ribbon from the vertical path andribbon20 is separated alongscore line26. It is understood,upstream press bar60 can contactribbon20 simultaneous with contact ofdownstream press bar70, or prior to contact of the downstream press bar with the ribbon. In either scenario, a portion ofribbon20 is restrained betweenupstream press bar60 and a portion ofupstream backing bar80, such that the ribbon remains restrained upstream of the separation line, after separation of the ribbon.
• InFIG. 6d,upstream press bar60,downstream press bar70,upstream backing bar80, and scoringassembly130 are realigned withribbon20 for formingsubsequent pane24.
• It is also noted that uponupstream press bar60 andupstream backing bar80 having at least a slight overlapping relation along the length ofribbon20, the application of a bending moment toupstream ribbon20 is reduced. The amount of overlap ofupstream press bar60 andupstream backing bar80 is at least partially determined by the type and thickness ofmaterial forming ribbon20.
• Referring toFIG. 7a,upstream backing bar80 and at leastupstream press bar60 are brought into contact withribbon20, prior to forming score line26 (and thus restrain the ribbon). Again,pane engaging assembly140 is engaged withribbon20 prior to formation of the score line. However, it is understood thatpane engaging assembly140 can engageribbon20 after formation ofscore line26. InFIG. 7b, scoringassembly130 is brought into contact withfirst side32 ofribbon20 and bears against a portion ofbacking bar80 to formscore line26. InFIG. 7c, scoringassembly130 is retracted. InFIG. 7d, thedownstream press bar70 is urged againstfirst side32 ofribbon20 to separatepane24 from the ribbon. InFIG. 7e,downstream press bar70 and scoringassembly130 are in the retracted position, whileupstream backing bar80 andupstream press bar60 remain in contact withribbon20, thereby dampening the transmission of any disturbance resulting from the separation ofpane24 from the ribbon. InFIG. 7f, the bars are returned to an initial position for separating asubsequent pane24 fromribbon20.
• Again, the relation ofupstream backing bar80 and upstream press bar60 (and downstream press bar70) can be offset, opposite or overlapping. Althoughupstream press bar60 anddownstream press bar70 can be simultaneously moved into contact withfirst side32 ofribbon20, and simultaneously moved after formation ofscore line26 to separatepane24, it is anticipated that independently moving the downstream press bar to initiate crack propagation along the score line is advantageous.
• Referring toFIG. 8a, secondaryupstream backing bar90 andupstream press bar80 are initially brought into contact withsecond side34 andfirst side32 ofribbon20 respectively. In addition,downstream press bar70 can optionally contact the first side ofribbon20 to further stabilize and control the ribbon. InFIG. 8b,upstream backing bar80 and scoringassembly130 are brought into contact withribbon20 to formscore line26 intermediateupstream press bar60 anddownstream press bar70. A portion ofupstream backing bar80 contactssecond side34 ofribbon20 upstream ofscore line26. Thus,ribbon20 is restrained upstream ofscore line26 by a portion ofupstream backing bar80 and secondaryupstream backing bar90 onsecond side34 of the ribbon andupstream press bar60 onfirst side32 of the ribbon.Pane engaging assembly140 engagesribbon20. InFIG. 8c, scoringassembly130 is retracted afterscore line26 is formed. InFIG. 8d,downstream press bar70 is urged further againstfirst side32 ofribbon20 causingpane24 to separate from the ribbon. InFIG. 8e, separatedpane24 is removed bypane engaging assembly140, and newly formedterminal end22 of the ribbon is restrained by a portion ofupstream backing bar80, secondaryupstream backing bar100 andupstream press bar60. InFIG. 8f, the bars are returned to a ready position to begin the sequence for separating asubsequent pane24 fromribbon20.
• With respect to the series ofFIG. 9, the configuration is selected to reduce premature unintended crack propagation alongscore line26. Generally, the configuration ofFIG. 9 induces a local compression infirst side32 ofribbon20 adjacent thescore line26. This local compressive force reduces the tendency of crack propagation alongscore line26. The bar configuration shown inFIG. 9, provides for the initial compression and a subsequent tension acrossscore line26, and hence controlled crack propagation.
• In the series ofFIG. 9,pane engaging assembly140 is employed to capturepane24 and remove the pane from descendingribbon20. As seen inFIG. 9a,upstream backing bar80, secondaryupstream backing bar90 anddownstream backing bar100 are mounted in acommon crossbeam50, wherein the secondary upstream backing bar and the downstream backing bar project a greater distance than the upstream backing bar. That is,upstream backing bar80 is recessed relative to secondaryupstream backing bar90 anddownstream backing bar100, so thatsecond side34 ofribbon20 initially contacts the secondary upstream backing bar and the downstream backing bar. Although secondaryupstream backing bar90 anddownstream backing bar100 can be of a softer, more easily compressible material thanupstream backing bar80, asupstream press bar60 contactsfirst side32 ofribbon20, a slight bow is imposed in the ribbon such that a local compressive force is created in the intended area ofscore line26.
• Althoughupstream backing bar80 can be separately controlled from secondaryupstream backing bar90 anddownstream backing bar100, the apparatus is simplified by mountingupstream backing bar80, secondaryupstream backing bar90 anddownstream backing bar100 to acommon crossbeam50, and employing different size contact surfaces56.
• Referring toFIG. 9b, scoringassembly130 then forms scoreline26 in the locally compressedfirst side32 ofribbon20. Subsequently, as seen inFIG. 9c, scoringassembly130 is retracted, anddownstream press bar70 is urged against the first side ofribbon20 with sufficient force to generate a localized tension in the first side of the ribbon in the area ofscore line26.Pane24 then separates fromribbon20 as seen inFIG. 9dwhileribbon20 remains restrained between secondaryupstream backing bar90 andupstream backing bar80 onsecond side34, andupstream press bar60 on the first side.Pane engaging assembly140 removespane24 inFIG. 9d. Referring toFIG. 9f, the bars and scoringassembly130 are returned to the ready position for separating asubsequent pane24.
• The present configurations thus provide for an opposed contact ofribbon20 upstream of score line26 (or score line location), wherein the upstream opposed contact can be in an offset, opposite or overlapping relation ofupstream press bar60 andupstream backing bar80.
• Subsequently, crack propagation is induced alongscore line26 andpane24 is separated fromribbon20.
• The upstream contact withribbon20 is maintained during and after the separation ofpane24, thereby reducing the introduction of disturbances that can migrate up the ribbon.
• In certain configurations, the upstream restraining ofribbon20 can be subsequent to formation ofscore line26 and substantially simultaneous with the separating of the ribbon along the score line. In further configurations, the upstream restraining ofribbon20 precedes the formation ofscore line26.
• 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.

Claims (20)

1. A method of separating a pane from a moving ribbon of brittle material, the method comprising:

a. contacting a first side of the moving ribbon with an upstream press bar and contacting a second side of the moving ribbon with an upstream backing bar, the upstream press bar and the upstream backing bar moving with the ribbon to restrain a portion of the ribbon portion of the ribbon; and

b. separating the pane from the ribbon along a score line downstream of the restrained portion of the ribbon.

2. The method ofclaim 1, further comprising releasing the restrained portion of the ribbon after separating the pane from the ribbon.

3. The method ofclaim 1, further comprising forming the score line prior to restraining the portion of the ribbon.

4. The method ofclaim 1, further comprising forming the score line subsequent to restraining the portion of the ribbon.

5. The method ofclaim 1, further comprising offsetting the upstream press bar and the upstream backing bar along a length of the ribbon.

6. The method ofclaim 1, further comprising locating the upstream press bar opposite the upstream backing bar.

7. The method ofclaim 1, further comprising contacting the upstream backing bar against the second side of the ribbon opposite the score line.

8. The method ofclaim 1, further comprising employing a portion of the upstream backing bar as a scoring anvil.

9. The method ofclaim 1, further comprising forming the score line in the first side of the ribbon opposite a portion of the upstream backing bar.

10. The method ofclaim 1, further comprising urging a downstream press bar against the first side of the ribbon downstream of the score line to induce separation along the score line.

11. The method ofclaim 1, further comprising contacting a secondary upstream backing bar with a second side of the ribbon prior to separating the pane from the ribbon.

12. The method ofclaim 1, further comprising contacting a secondary upstream backing bar with a second side of the ribbon prior to forming the score line.

13. The method ofclaim 1, further comprising overlapping the upstream press bar and the upstream backing bar along the ribbon.

14. The method ofclaim 1, further comprising restraining the portion of the ribbon after separating the pane along the score line.

15. The method ofclaim 1, further comprising contacting a secondary upstream backing bar with a second side of the ribbon, and contacting the upstream press bar with the first side of the ribbon prior to separating the pane.

16. The method ofclaim 1, further comprising creating a compressive stress in the first side of the ribbon transverse to the score line.

17. An apparatus for separating a pane from a moving ribbon of brittle material, the apparatus comprising:

a. a pair of opposing bars contacting opposing sides of the ribbon and moving with the ribbon, to restrain a portion of the ribbon upstream of a score line; and

b. a downstream press bar contacting the ribbon downstream of a score line to separate the pane from the ribbon along the score line.

18. The apparatus ofclaim 17 wherein the opposing bars are in an offset relation.

19. The apparatus ofclaim 17 wherein the opposing bars are in an opposite relation.

20. The apparatus ofclaim 17, wherein the opposing bars contact the ribbon along substantially an entire length of the score line.

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