Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B33/00—Severing cooled glass
  • C03B33/02—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor
  • C03B33/0215—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor the ribbon being in a substantially vertical plane
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G49/00—Conveying systems characterised by their application for specified purposes not otherwise provided for
  • B65G49/05—Conveying systems characterised by their application for specified purposes not otherwise provided for for fragile or damageable materials or articles
  • B65G49/06—Conveying systems characterised by their application for specified purposes not otherwise provided for for fragile or damageable materials or articles for fragile sheets, e.g. glass
  • B65G49/061—Lifting, gripping, or carrying means, for one or more sheets forming independent means of transport, e.g. suction cups, transport frames
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B33/00—Severing cooled glass
  • C03B33/09—Severing cooled glass by thermal shock
  • C03B33/091—Severing cooled glass by thermal shock using at least one focussed radiation beam, e.g. laser beam
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G2249/00—Aspects relating to conveying systems for the manufacture of fragile sheets
  • B65G2249/04—Arrangements of vacuum systems or suction cups
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
  • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

• This disclosure relates to methods and apparatus for separating glass sheets from a laser-scored curved glass ribbon.
• Scoring of glass is conventionally accomplished using mechanical tools.
• laser radiation e.g., CO 2 laser radiation at a wavelength of 10.6 ⁇
• CO 2 laser radiation at a wavelength of 10.6 ⁇
• the use of a laser for glass scoring is discussed in commonly-assigned U.S. Patent No. 5,776,220 entitled “Method and apparatus for breaking brittle materials” and U.S. Patent No. 6,327,875 entitled “Control of median crack depth in laser scoring.”
• a vent is created in a major surface 1 14 of glass 1 12 along line 1 15.
• a small initiation flaw 11 1 is formed on the glass surface near one of its edges, which is then transformed into the vent by propagating a laser light beam 121 produced by laser 141 and having a footprint 1 13 across the surface of the glass followed by a cooling area produced by a cooling nozzle 1 19.
• Heating of the glass with a laser light beam and quenching it immediately thereafter with a coolant creates a thermal gradient and a corresponding stress field, which is responsible for the propagation of the initiation flaw to form the vent.
• FIGS. 2 and 3 of the present application schematically illustrate the system of the '994 publication.
• the glass ribbon is identified by the reference number 33, the traveling carriage by the number 14, the linear track by the number 15, the support structure (support frame) for the track by the number 11 , and the equipment which produces the ribbon, e.g., a fusion draw machine, by the number 9.
• a fixed reference frame e.g., the xyz reference frame in FIG.
• the carriage keeps pace with the ribbon, or, more precisely, the magnitude of the component of the carriage's velocity that is parallel to the direction of motion of the ribbon equals Sribbon. Consequently, as seen from the ribbon, the carriage simply moves in the direction of vector 18, i.e., across the ribbon along score line 7 perpendicular to the ribbon's direction of motion, at a speed S scor e given by:
• a light-emitting device that provides a laser light beam and a nozzle that provides a stream of a cooling fluid (e.g., water) are coupled to the carriage and together form a vent across the width of the ribbon as the carriage moves along the linear track.
• a mechanical scoring head e.g., a scoring wheel
• a mechanical scoring head is also coupled to the carriage for forming an initiation flaw in the glass ribbon.
• the initiation flaw can be formed by equipment separate from the carriage.
• FIG. 4 schematically illustrates these aspects of the '994 publication, where reference numbers 21, 22, and 23 represent the locations at the beginning of the scoring process of (1) the footprint of the cooling fluid, (2) the footprint of the laser light beam, and (3) the initiation flaw, and reference numbers 31 and 32 represent the locations of the footprint of the cooling fluid and the footprint of the laser light beam at a later point in time, after initiation has been completed.
• the '994 publication refers to the use of a conventional bending technique in which a robot with suction cups grabs the glass ribbon below the score line and bends the ribbon such that it separates at the score line.
• the score line produced by a laser has different characteristics than the score line produced by a mechanical scoring device.
• bending techniques that have historically worked successfully for a mechanically-scored ribbon have been found to result in poor edge quality for a laser-scored ribbon, e.g., a ragged, hackle-containing edge.
• the present disclosure addresses this problem and provides methods and apparatus for separating glass sheets from a laser-scored ribbon using bending techniques wherein the edge is at least substantially of the same quality as that achieved with mechanical scoring.
• a method of making glass sheets (13) includes:
• each glass sheet (13) being produced by a process which includes:
• the sheet-engaging assembly (530) including a frame (520) and a plurality of ribbon/sheet holding devices (e.g., suction cups (510)) carried by the frame (520), the ribbon/sheet holding devices being in engagement with at least the second side (502) of the glass ribbon (33), the distance between the score line (7) and the ribbon/sheet holding device that is closest to the score line (7) being L;
• the sheet-engaging assembly (530) including a frame (520) and a plurality of ribbon/sheet holding devices (e.g., suction cups (510)) carried by the frame (520), the ribbon/sheet holding devices being in engagement with at least the second side (502) of the glass ribbon (33), the distance between the score line (7) and the ribbon/sheet holding device that is closest to the score line (7) being L;
• a nosing (540) is in engagement with the second side (502) of the ribbon (33) at the score line (7), the nosing (540) being flat in the across-the-ribbon direction;
• each glass sheet (13) being produced by a process which includes:
• the sheet-engaging assembly (540) including a frame (520) and a plurality of ribbon/sheet holding devices (e.g., suction cups (510)) carried by the frame (520), the ribbon/sheet holding devices being in engagement with at least the second side (502) of the glass ribbon (33) during the rotation, the distance between the score line (7) and the ribbon/sheet holding device that is closest to the score line being L; the method including increasing L from a baseline value suitable for mechanical scoring so as to improve the edge quality of the glass sheets (13) separated from the ribbon (33).
• ribbon/sheet holding devices e.g., suction cups (510)
• a method of making glass sheets (13) includes:
• each glass sheet (13) being produced by a process which includes:
• the sheet-engaging assembly (530) including a frame (520) and a plurality of ribbon/sheet holding devices (e.g., suction cups (510)) carried by the frame (520), the ribbon/sheet holding devices being in engagement with at least the second side (502) of the glass ribbon (33);
• the sheet-engaging assembly (530) including a frame (520) and a plurality of ribbon/sheet holding devices (e.g., suction cups (510)) carried by the frame (520), the ribbon/sheet holding devices being in engagement with at least the second side (502) of the glass ribbon (33);
• a nosing (540) carried by the frame (520) is in engagement with the second side (502) of the ribbon (33) at the score line (7),
• the method includes moving the nosing (540) away from the separated glass sheet (13) to expose the upper edge (690) of the sheet (13).
• the method of any one of the first through fourth aspects wherein the nosing has a curved transverse cross section.
• the method of any one of the first through sixth aspects wherein the nosing is rotatable about an axis parallel to the score line.
• the method of any one of the first through seventh aspects wherein the glass ribbon is formed by a downdraw process.
• the method of any one of the first through eighth aspects wherein the glass sheets are substrates for display devices.
• the method of any one of aspects 1-11 wherein the ribbon/sheet holding devices comprise pads for engagement with the first side of the ribbon and suctions cups for engagement with the second side, and the method comprises using the pads to move the ribbon into engagement with the suction cups.
• FIG. 1 is a schematic diagram illustrating a laser scoring process.
• FIG. 2 is a schematic diagram illustrating a laser scoring system according to the
• FIG. 3 is a schematic diagram illustrating the motions of the carriage of FIG. 2 in more detail.
• FIG. 4 is a schematic diagram illustrating locations of the cooling fluid, laser light beam, and initiation flaw at the beginning of the scoring process and at a later point in time.
• FIG. 5 is a schematic drawing illustrating a sheet-engaging assembly and a nosing in engagement with a curved ribbon.
• FIG. 6 is a schematic drawing of the sheet-engaging assembly, nosing, and curved ribbon of FIG. 5 as seen from above.
• FIG. 7 is a schematic drawing illustrating rotation of a glass ribbon to produce a bending moment at a score line.
• FIG. 8 is a plot of calculated data showing the effect of changes in the distance between a score line and the closest ribbon/sheet holding device (specifically, in this case, the closest suction cup) of a sheet-engaging assembly.
• FIG. 9 is a schematic drawing of the sheet-engaging assembly, nosing, and curved ribbon of FIG. 5 as seen from above after the ribbon has been rotated as shown in FIG. 7.
• FIG. 10 is a schematic drawing illustrating a nosing having a curved cross section.
• FIG. 11 is a perspective view of an integrated nosing/sheet handling assembly prior to engagement with a glass ribbon.
• FIG. 12 is a perspective view of an integrated nosing/sheet handling assembly after engagement with a glass ribbon.
• FIG. 13 is a perspective view of an integrated nosing/sheet handling assembly just after separation of a glass sheet from a glass ribbon.
• FIG. 14 is a perspective view of an integrated nosing/sheet handling assembly after a robot has moved the assembly and its attached separated glass sheet away from a glass ribbon.
• FIG. 15 is a perspective view of an integrated nosing/sheet handling assembly after a robot has moved the assembly and its attached separated glass sheet away from a glass ribbon and has moved the assembly's nosing away from the top edge of the sheet so that handling equipment can engage the sheet from above.
• FIG. 16 is a side view showing the nosing of FIGS. 11-15 in more detail.
• this disclosure relates to the discovery that the score line produced by laser scoring has different separation characteristics than the score line produced by a mechanical scoring device.
• a mechanical scoring device produces a score line it physically moves the glass which is at and below the glass surface at the score line. This process generates numerous glass particles many of which can be found embedded in the glass in and near the score line.
• mechanically-scored glass is simply allowed to sit undisturbed, it will often spontaneously separate at the mechanical score line even without the application of any bending forces, i.e., it will spontaneously separate as a result of the physical damage which the glass has undergone and the stress induced by particles which have been forced into the glass at the score line by the mechanical scoring device.
• a score line formed by a laser is very different.
• the laser does not normally move glass material away from the score line and does not generate particles which become embedded in the glass at and near the score line. Rather, the laser operates by weakening chemical bonds at the locations where the laser and the coolant fluid have acted. If allowed to sit undisturbed, rather than spontaneously separating, a laser-scored score line can actually heal, especially in a humid atmosphere where water is available to participate in the reformation of chemical bonds. Consequently, it has been found that separating glass sheets from a glass ribbon at a laser-scored score line is substantially different from separating sheets at a mechanically-scored score line.
• glass ribbons have non-flat across-the-draw shapes, especially for ribbons composed of thin glass, e.g., glass having a thickness of 0.7 millimeters and below, and large widths, e.g., 0.5 meters and above.
• the ribbon can be in the form of a bow whose concavity can be on either side of the ribbon. More complex shapes are also possible, such as, M or W shapes.
• FIGS. 5 and 6 illustrate the case of a bowed ribbon 33 where the ribbon's concavity faces suction cups 510 and frame 520 of sheet-engaging assembly 530. As shown in these figures, suction cups 510 engage the second side 502 of ribbon 33, as does nosing 540.
• the holding devices can have a variety of other configurations now known or subsequently developed in the art.
• the holding devices can include pads which engage the first side 501 of the ribbon and suctions cups which engage the second side.
• the suctions cups in FIGS. 11-15 which engage the ribbon's second side can be replaced with pads, so that the ribbon is clamped between sets of pads which engage its opposing sides.
• sheet-engaging assembly 530 is rotated by, for example, industrial robot 700, about an axis through the score line with the nosing 540 serving as a stop or fulcrum for the rotation.
• the laser-scored score line is on the first side 501 of the ribbon, i.e., the side which faces away from nosing 540, and the rotation of the frame and ribbon/sheet holding devices (suction cups in this embodiment) is clockwise.
• the frame and ribbon/sheet holding devices suction cups in this embodiment
• the non-flatness of the ribbon at the nosing was not believed to be associated with the poor edge quality seen with laser scoring.
• the relatively-easy-to- separate score line limits the amount of stress, including the amount of shear stress, that can be generated before separation, thus leading to acceptable edge qualities even for non-flat ribbons.
• the relatively-hard-to-separate score line allows the amount of stress, including shear stress, to grow and thus reach a level where it is sufficient to produce a ragged edge.
• Curve 800 shows the baseline calculated stress distribution for an L value suitable for mechanical scoring, while curves 801 and 802 respectively show the effect of reducing and increasing L by approximately 25%. As can be seen, increasing L decreases the stress at the score line (curve 802), while decreasing L increases the stress (curve 801).
• FIG. 9 This flattening effect associated with rotation of the sheet-engaging assembly is illustrated in FIG. 9, where, compared to FIG. 6, gap 560 has been substantially reduced as a result of rotation. Further rotation will bring the glass into contact with the nosing thus giving it the desired substantially completely flattened configuration. In this way, i.e., by increasing L, when the stress caused by the rotation finally exceeds the failure stress of the glass, the ribbon will already be flat against the nosing and thus will not experience substantial amounts of shear stress. Without substantial amounts of shear stress, the edge on the glass sheet is not ragged, the desired result.
• FIG. 10 shows the edge quality of glass sheets produced from laser- scored glass ribbons.
• reference number 570 shows the direction of rotation of sheet- engaging assembly 530.
• the curved nosing can be fixed or can be rotatable about an axis parallel to the score line.
• Various materials can be used for the nosing, a suitable material being a silicone rubber.
• the curved nosing can have a variety of curvatures.
• a diameter of 50 millimeters has been found suitable for a nosing having a circular transverse cross section.
• a nosing having a curved transverse cross section improves edge quality
• the flattening aspects of the disclosure can be practiced with nosings having other cross sectional shapes, e.g., rectangular shapes, if desired.
• the distance L between the score line and the nearest ribbon/sheet holding device which results in acceptable edge quality can be determined by observing gap 560 and increasing L until separation is retarded by a sufficient amount so that the gap is closed and side 502 of the glass ribbon is in contact with the nosing prior to the
• edge quality itself can be used as the parameter for determining when L is sufficiently large, with L being increased until the occurrence of jagged edges has been reduced to a desired level, e.g., until there are essentially no jagged edges.
• adjustment of L is straightforward, especially when the sheet-engaging assembly is manipulated by an industrial robot where the change in L can be accomplished by changing one or more operating parameters of the robot.
• the rate of motion of ribbon 33 places an upper limit on how much L can be increased since a longer L means that sheet-engaging assembly 530 must rotate farther about the score line before separation occurs.
• a rate of rotation e.g., a rate of rotation compatible with the elastic properties of the glass
• rotating sheet-engaging assembly 530 farther takes longer and thus at some point, the separation process will fall behind the rate of production of the ribbon.
• L can be increased to a level which substantially eliminates the ragged edge problem while still easily keeping up with the rate of motion of the ribbon.
• FIGS. 1 1-16 illustrate an embodiment of apparatus for practicing the above methods for improving the edge quality of glass sheets separated from a glass ribbon at a laser-scored score line.
• This apparatus also illustrates further aspects of this disclosure in which a nosing is integrated with sheet handling equipment which: (1) applies the bending moment which separates the glass sheet from the glass ribbon, (2) moves the separated glass sheet away from the glass ribbon, and (3) transfers the separated sheet to transport equipment which engages the top of the sheet.
• a nosing is integrated with sheet handling equipment which: (1) applies the bending moment which separates the glass sheet from the glass ribbon, (2) moves the separated glass sheet away from the glass ribbon, and (3) transfers the separated sheet to transport equipment which engages the top of the sheet.
• Such an integrated nosing/sheet handling assembly reduces costs and simplifies the deployment of equipment at the bottom of the draw.
• the nosing of the integrated assembly can also be used as a backing for the formation of initiation flaw (see reference number 23 in FIG. 4) or as a backing for the entire scoring processes in cases where mechanical scoring, rather than laser scoring, is performed.
• the nosing of the assembly need not extend across the full width of the ribbon but only needs to be long enough to produce the initiation flaw.
• the integrated assembly of FIGS. 1 1-16 can be manipulated by an industrial robot, with the attachment of the assembly to the robot occurring at, for example, the apparatus' nominal center 670.
• the assembly can include a vacuum port 620 above and below the nosing as shown on Fig. 15 to collect glass fragments generated when a glass sheet separates from the glass ribbon.
• the vacuum port can be connected to a vacuum system (not shown) through vacuum plenum 630.
• the integrated assembly can also include a connector assembly 650 of the type described in U.S. Patent No. 6,616,025 referred to above for allowing the separated sheet to automatically drop away from the moving ribbon once separation occurs.
• the assembly can use sheet clamping units 660 which employ both suction cups, which engage the second side 502 of the glass ribbon, and clamping pads which engage the first side 501.
• the clamping pads are moved against the ribbon using pneumatic cylinders 680.
• the suction cups can be brought into proximity with the second side of the ribbon and then the clamping pads can be used to press the sheet against the suction cups.
• This combination of suction cups and clamping pads can increase holding capacity, widen the process window, e.g., allow the equipment to be used with ribbons which exhibit large and skewed bow at the bottom of the draw, and reduce suction cup consumption.
• the pads and suction cups can be composed of a variety of materials, including, for example, a silicone rubber.
• the integrated nosing/sheet handling assembly also includes air cylinders 640 for moving the nosing into and out of the plane defined by the sheet clamping units, i.e., the nominal plane of the second side of the glass ribbon when the ribbon has been engaged by the sheet clamping units.
• the nosing needs to be in this plane when supporting the ribbon during mechanical scoring and sheet separation, but needs to be out of the plane to expose the sheet's top edge during transfer of the sheet to subsequent handling equipment.
• the air cylinders move the nosing into the plane, while in their retracted configuration (see FIG. 15), they move it out of the plane to expose top edge 690.
• Linkages other than those shown in FIGS. 11 -15 can, of course, be used to move the nosing between its two positions, e.g., servomotors can be used for this purpose.
• FIGS. 11 -15 Representative motions of the integrated nosing/sheet handling assembly during the separation of a sheet from a moving ribbon is shown in FIGS. 11 -15.
• FIG. 1 1 shows the assembly prior to engagement with the ribbon and FIG. 12 shows it just after engagement.
• the robot moves the assembly downward in pace with the ribbon as the initiation flaw is formed and the laser scoring performed. Thereafter, the robot rotates the assembly about the score line (or equivalently about the leading edge of the nosing) to first flatten the ribbon against the nosing and then separate the sheet from the ribbon.
• FIG. 13 shows the resulting configuration of the system just after separation of a glass sheet from the ribbon.
• FIG. 14 the robot moves the assembly and the separated glass sheet away from the glass ribbon.
• pneumatic cylinders 640 move the nosing away from the top edge of the sheet so that subsequent handling equipment can engage the sheet from above. The robot then returns the assembly to its position in FIG. 1 1 and the process is repeated for the next glass sheet.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Optics & Photonics (AREA)
• Toxicology (AREA)
• Thermal Sciences (AREA)
• Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
• Processing Of Stones Or Stones Resemblance Materials (AREA)
• Laser Beam Processing (AREA)

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Cited By (8)

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Citations (8)

• 2010
  • 2010-12-13 TW TW099143502A patent/TWI524962B/zh not_active IP Right Cessation
  • 2010-12-16 JP JP2012544811A patent/JP5715645B2/ja not_active Expired - Fee Related
  • 2010-12-16 CN CN201410627583.0A patent/CN104496405B/zh not_active Expired - Fee Related
  • 2010-12-16 CN CN201080056355.2A patent/CN102656105B/zh not_active Expired - Fee Related
  • 2010-12-16 KR KR1020127017949A patent/KR101577857B1/ko not_active IP Right Cessation
  • 2010-12-16 WO PCT/US2010/060674 patent/WO2011084561A1/en active Application Filing

Patent Citations (8)

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