Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
  • C03B17/06—Forming glass sheets
  • C03B17/068—Means for providing the drawing force, e.g. traction or draw rollers
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B35/00—Transporting of glass products during their manufacture, e.g. hot glass lenses, prisms
  • C03B35/14—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands
  • C03B35/16—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands by roller conveyors
  • C03B35/18—Construction of the conveyor rollers ; Materials, coatings or coverings thereof
  • C03B35/181—Materials, coatings, loose coverings or sleeves thereof
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B35/00—Transporting of glass products during their manufacture, e.g. hot glass lenses, prisms
  • C03B35/14—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands
  • C03B35/16—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands by roller conveyors
  • C03B35/18—Construction of the conveyor rollers ; Materials, coatings or coverings thereof
  • C03B35/183—Construction of the conveyor rollers ; Materials, coatings or coverings thereof specially adapted for thermal adjustment of the rollers, e.g. insulating, heating, cooling thereof
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B35/00—Transporting of glass products during their manufacture, e.g. hot glass lenses, prisms
  • C03B35/14—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands
  • C03B35/16—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands by roller conveyors
  • C03B35/18—Construction of the conveyor rollers ; Materials, coatings or coverings thereof
  • C03B35/183—Construction of the conveyor rollers ; Materials, coatings or coverings thereof specially adapted for thermal adjustment of the rollers, e.g. insulating, heating, cooling thereof
  • C03B35/184—Cooling
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B35/00—Transporting of glass products during their manufacture, e.g. hot glass lenses, prisms
  • C03B35/14—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands
  • C03B35/16—Transporting hot glass sheets or ribbons, e.g. by heat-resistant conveyor belts or bands by roller conveyors
  • C03B35/18—Construction of the conveyor rollers ; Materials, coatings or coverings thereof
  • C03B35/186—End caps, end fixtures or roller end shape designs

Definitions

• the invention relates to a roll for use in the manufacture of glass and particular to pulling rolls for glass to be used in electronic applications.
• Rolls may support or convey a glass sheet through an annealing or heat treating furnace. Rolls may also flatten, lengthen or otherwise alter the dimensions of the glass. A roll may even generate a pulling force on the glass to control the glass thickness. In any application, the roll should not contaminate the useable surface of the glass or produce an excessive number of onclusions. Onclusions can occur from "dusting" of the roll, that is, when small particles erode from the roll and stick to the glass. Onclusions are more likely to form on hot glass, such as around pulling rolls right out of the furnace.
• Rolls may comprise an outer refractory body bonded to an inner metal shaft.
• the refractory body resists thermal insults and protects the metal shaft from heat.
• the metal shaft provides mechanical strength to the refractory body.
• a tubular outer refractory body is cemented to a metal shaft. This unitary structure is strong and simple to produce. Although the metal shaft is insulated from the high temperature glass, damage to any part of the roll requires replacement of the entire roll. Repair of only part of the roll is difficult or impossible. Other problems include cracking caused by mismatches in thermal expansion between the metal shaft, the cement, and the refractory body.
• the metal shaft expands more than the outer refractory body and exerts a tensile stress on the refractory body. Tensile stresses are particularly damaging because the refractory body is commonly a ceramic, and ceramics are typically weak in tension.
• Water cooling may be used to reduce the temperature of the metal shaft and therefore its expansion. Unfortunately, the fittings necessary for water cooling add additional expense and complexity to the roll.
• a popular roll for use in glass manufacture has included a plurality of asbestos fiber discs stacked over a metal shaft.
• the asbestos discs were laterally compressed to form a rigid outer surface.
• the erosion-resistance of the surface could even be improved by impregnation with chemicals such as potassium sulfate.
• damage to one or several asbestos discs could be repaired by replacing only the damaged discs.
• Asbestos fiber is resilient and a good insulator, so it both thermally shielded the metal shaft and accommodated any thermal expansion of the metal shaft that might have occurred.
• Asbestos also had little affinity for glass, so eroded particles did not stick to glass or form onclusions. Of course, the health risks of asbestos prevent its use.
• Prior art includes rolls that reduce the erodable surface of the roll. Such rolls may comprise a metal shaft having a plurality of refractory collars. This configuration may be useful in those applications, such as pulling rolls, where only a portion of the glass contacts the roll. A large fraction of the metal shaft is left uncovered by a refractory body.
• Eliminating the refractory body removes a possible source of dusting and onclusions, but the exposed metal shaft is more susceptible to corrosion and dimensional instability when exposed to elevated temperatures, which may exceed 700 C. Corrosion may cause the metal shaft to break or deposit corrosion products on the glass. Dimensional changes in the roll can cause fracture or distortion of the glass. A coating may be applied to the metal shaft to reduce corrosion but the metal shaft still may warp from the high temperatures. The use of corrosion-resistant and more heat-tolerant metals, such as stainless steel, reduces this risk. Of course, this also increases costs and the metal still is substantially less refractory than a ceramic.
• Rolls do not necessarily require a metal shaft for mechanical support.
• Prior art includes roll comprising a solid fused silica cylinder.
• Fused silica inherently has a very low coefficient of thermal expansion and has been used where thermal gradients are severe.
• Fused silica rolls do not corrode and are more dimensionally stable than rolls including metal shafts.
• Negatively, fused silica rolls do not grip glass sufficiently to function as pulling rolls, lack the strength of metal-shafted rolls, and cannot be directly connected to machinery for driving the rotation of the roll.
• Metal end caps which are fixedly secured to the roll, permit mechanical connection to the driving machinery, but are not without their problems. The metal-capped ends must engage the driving machinery and transmit torque to the roll. Problems include securing the end caps permanently to the ceramic roll and loss of torque between the end cap and the roll. Thermal expansion disparities between the ceramic roll and the metal end cap contribute to both problems.
• the roll should be substantially non-dusting and should be suitable for use so as a pulling roll.
• the roll should possess good mechanical strength and accommodate any thermal expansion disparities between the materials.
• the roll should also possess excellent dimensional stability.
• the present invention describes a roll for pulling a glass sheet particularly in draw down applications.
• the roll comprises a refractory ceramic shaft supporting a plurality of pulling flats.
• the refractory ceramic may be a non-dusting material.
• the shaft may be hollow or solid.
• the pulling flats are one or more annular discs comprising a substantially non-dusting material and are secured to the outer surface of the ceramic shaft.
• the non-dusting material may include a compressible or an incompressible material.
• the pulling flats are secured to the shaft by retainers and optionally a refractory adhesive.
• the retainer may comprise a split ring.
• the pulling roll includes a body comprising a hollow cylinder.
• the cylinder may comprise fused silica.
• the hollow cylinder permits the introduction of cooling air into the body.
• the cylinder includes a longitudinal axis, an outer surface, and opposite ends. End caps are fixedly secured to the ends and are capable of connecting with a driving mechanism that rotates the roll.
• At least two pulling flats comprise a non-dusting material that is substantially free of colloidal silica or silica fiber. The use of non-dusting material reduces the ability of convective currents to fluidize silica, which can then deposit on the glass to form undesirable onclusions.
• the pulling flats are fixed to the outer surface of the cylinder by a plurality of retainers.
• the pulling roll includes a hollow body that is substantially cylindrical.
• the body comprises fused silica or other non-dusting, rigid refractory ceramic.
• the cylinder includes a longitudinal axis, an outer surface, an inner surface, and opposite ends. End caps are fixedly secured to the ends and are capable of connecting with a driving mechanism that rotates the roll. Pulling flats are fixed on the outer surface by retainers comprising split rings.
• a metal rod extends through the hollow cylinder and is secured to the cylinder by compressible supports. The supports accommodate differences in thermal expansion between the metal rod and ceramic cylinder so that thermal expansion of the rod does not exert an undue tensile stress on the body. The rod provides a fail-safe in the event the body breaks.
• the pulling roll includes a hollow body comprising fused amorphous silica and a pair of pulling flats fixed in place by retainers.
• the retainers secure outer and inner end plates.
• Each pulling flat may be sandwiched between an outer end plate and an inner end plate; the outer end plate in this configuration is secured to the body by an outer retainer and the inner end plate is secured to the body by an inner retainer.
• Each pulling flat is near an end of the body and includes an outer circumference that extends beyond the end plates.
• the outer and inner end plates comprise a rigid, non-dusting, refractory material.
• Each inner end plate includes an outer diameter that is less than the outer diameter of the pulling flat. The inner end plate abuts an abutment of the body.
• the abutment may be molded or machined into the body or may be fixed to the body using mechanical fasteners or adhesives.
• Each outer end plate includes an outer diameter that is less than the outer diameter of the pulling flat.
• Each outer end plate also includes an inner diameter that increases towards the end of the roll.
• An outer retaining ring having a wedge-shaped cross-section that complements the increasing diameter of the outer end plate, is forced at least partially between the inner diameter of the outer end plate and the body until the outer end plate is frictionally fixed to the roll. In this manner, the pulling flat is rigidly sandwiched between the end plates and the end plates are capable of providing support for the pulling flat during service.
• the outer retaining ring comprises a plurality of portions
• the body includes recesses having discontinuities.
• the portions have a substantially wedge- shaped cross-section and a face that complements the inner diameter of the outer end plate.
• the recesses are beneath the outer end plates.
• the recesses may be continuous or discontinuous around the body. The portions are forced between the outer end plate and the body until they engage the recess. The discontinuity of the recess restricts motion of the portion.
• Materials other than silica that may be used in the body of the pulling roll of the invention include mullite, aluminum titanate, silicon carbide, or other fused or non-fused materials.
• a silicoaluminate composition having a low-shot fiber content under 3.5 wt% may be used. Such a composition may have 35-45 wt% alumina and 55-65 wt% silica, with a density in
• a low shot fiber content may be obtained by
• a silicoaluminate composition, a millboard or a silicoaluminate fiber material may be used for the pulling flats.
• Such a composition may have 35-45 wt% or 40-42 wt% alumina, 50-
• the glass- engaging portions of the pulling flat may have a Shore D hardness at room temperature in the range of 25 to 35.
• the glass-engaging portions of the pulling flat may contain mica, clay, and a heat-resistant binder, and may contain a composite of clay and mica.
• Figure 1 is a perspective view of a roll of the current invention.
• Figure 2 is a cross-section of the roll.
• Figure 3 is an enlarged cross-section of the end of the roll.
• Figure 4 is a cross-section of a second embodiment of the end of a roll.
• Figure 5 is a cross-section of the end plate, retainer, and body.
• Figure 6 is a perspective view of the metal rod, body and supports.
• the invention includes a roll for use in glass manufacturing. More particularly, the roll may be used as a pulling roll and has very little dusting and, therefore, restricts the formation of onclusions on the glass.
• FIGS 1 and 2 show a roll 1 of the present invention.
• the roll 1 includes a longitudinal axis 2 and opposite ends 3. End caps 4 cover each end 3.
• the body 5 of the roll 1 includes a cylinder comprising a substantially incompressible refractory ceramic, such as fused silica.
• the body 5 has an outer surface 22 and an inner surface 23.
• the inner surface 23 defines a cavity 24.
• the ends 3 may close the cavity 3 but, preferably, the cavity 24 remains open at either end 3.
• Open ends permit a metal rod 25 to extend through the cavity 24 between the end caps 4.
• Supports 26 hold the metal rod 25 along the longitudinal axis 2.
• An inner end plate 7 is adjacent to an inner retainer 6, in this embodiment, an abutment.
• the abutment 6 is present near each end
• the body comprises a substantially incompressible refractory ceramic material such as fused silica and, more preferably, a sintered amorphous silica.
• the fused silica may be produced by any method.
• the body should be machined to control concentricity and maintain balance. Preferably, deviation from the ideal is less than about 10 inch-pounds.
• the body preferably includes a hollow cylinder.
• the wall of the hollow cylinder will have a thickness sufficient to support the roll during operation and to accommodate the stresses at the end caps.
• a fused silica roll having a length of four meters should have a wall thickness at least about 15 mm.
• End caps fit around the end of the roll. End caps should be metallic and most commonly will be steel. Any known method, including adhesives or mechanical methods such as set screws, pins and compression fittings, may fixedly secure the end caps to the roll. US 2007/0042883 is hereby incorporated by reference.
• the end caps permit connection of the roll with a drive mechanism. Preferably, the end caps will not obstruct the cavity within the roll so that the flow of cooling air is not obstructed.
• the end caps include a metal ferule adapted to fit over the end of the body.
• the end plates are substantially discs having an inner diameter at least slightly larger than the diameter of the roll.
• the inner diameter of the end plates may vary as described below.
• the end plates should comprise a rigid, refractory, non-dusting material and preferably will also mechanically support the pulling fiat.
• the retainers should exert a force parallel to the longitudinal axis of the body sufficient to properly support the pulling fiats. This force is often at least several thousand pounds.
• the end plates may comprise fused silica or any other non- dusting refractory ceramic.
• the end plates may be secured to the body by mechanical retainers, such as abutments or retainers, or adhesives. Suitable adhesives may contain colloidal silica that bonds to both the body and the end plate. Alternatively, retainers mechanically fix the end plates to the body of the roll.
• the retainers may be, for example, compression fittings containing fused silica.
• the retainer includes a ring comprising a plurality of portions and the body of the roll under the end plate includes a recess to accept the portions thereby locking the end plate in place.
• the body 5 includes a recess 51 with a discontinuity 52.
• the retainer 21 includes an inclined surface 33 and a second surface 34. The inclined surface 33 complementarily engages an inner surface 32 of the outer end plate 8, and the second surface 34 engages the recess 51.
• the discontinuity 52 holds the retainer 21 in place, and restricts removal of the retainer from the recess.
• the pulling flat comprises a non-dusting material that is capable of pulling glass.
• the roll includes a plurality of pulling flats.
• the pulling flats produce two contact areas on either edge of the glass sheet; although, the pulling flats may have multiple contacts with the glass.
• Pulling glass requires the material to have a sufficiently high-temperature compressive strength.
• a suitable material for the pulling flats may include mica, clay such as for example kaolin, and refractory ceramics such as quartz, alumina, glass, and mullite.
• mica and clay inherently possess a high specific gravity that resists fluidization by convective currents.
• Particle size should be high enough to resist fluidization but small enough to produce a smooth pulling flat.
• Particle shapes that deviate from the spherical, such as elongated or flattened shapes, are less likely to be entrained in a fluid.
• the material may be reinforced with ceramic fiber and/or glass fiber.
• the fiber preferably comprises low shot content, where shot refers to generally non- fibrous agglomerations produced during fiber manufacture.
• the fiber reinforces the pulling flat material. Embedding the fiber reduces the likely that fiber will break free and create onclusions.
• the fiber may include silica, alumino-silicate or other suitable compound.
• the pulling flat should rotate with the roll and should not spin relative to the roll.
• a refractory adhesive such as colloidal silica or a refractory cement, may secure the pulling flat to the body. Adhesion to the body may be improved by roughening or creating grooves in the outer surface of the body.
• Figure 3 shows an enlarged cross-section of an end 3 of the roll 1.
• the inner end plate 7 and outer end plate 8 sandwich the pulling flat 9.
• the inner end plate 7 is adjacent to an abutment 6.
• the outer end plate 8 includes an inclined inner surface 32 with a diameter that increases towards the end 3.
• An outer retainer 21 includes a first surface 34 with a diameter greater than that of the body 5 and a second surface 33 complementarity engaging the inner surface 32 of the outer end plate 8.
• the outer retainer 21 defines a wedge-shaped cross-section.
• Driving the outer retainer 21 inwards from the end 3 produces a frictional fit that secures the outer end plate 8 to the roll 1.
• the outer retainer 21 may comprise a ring or may include a plurality of portions dispersed around the body.
• a ring may be a single unit; however, a split ring facilitates assembly of the roll and replacement of the pulling flat.
• the retainer ring 21 should comprise a hard refractory material and preferably should be non-dusting.
• the material may comprise fused silica.
• a refractory adhesive may also be used in conjunction with the retainer.
• the inclined surface 32 will have an angle of inclination 41 from 5-25 degrees from the outer surface 42 of the body 5 of the roll.
• a smaller angle permits finer adjustment of the retaining force but demands tighter machining tolerances or a larger retainer ring.
• a larger angle accommodates larger mismatches between components but exerts a weaker retaining force and could loosen during use.
• Use of a retainer comprising a plurality of pieces, such as a split ring facilitates assembly and permits the use of the mechanical fastening shown in Figure 5.
• the abutment is typically machined or cast into the body of the roll during is manufacture. Alternatively, the abutment may be mechanically or adhesively secured to the body. The abutment may even be replaced with a second retainer ring.
• the inner end plate would include an inner surface that increases in diameter away from the end.
• the second retainer ring includes a first surface with a diameter greater than that of the body and a second surface complementarily engaging the inner surface of the inner end plate.
• the second retainer ring has a wedge-shaped cross-section. As assembled, the inner end plate/retainer ring could be substantial mirror images of the outer end plate/retainer ring.
• the body of the roll comprises fused silica.
• a metal rod may extend through the cavity of the roll.
• the metal rod may extend from end cap to end cap.
• the metal rod does not impinge on the inner surface of the body. If the roll fractures during operation, the metal rod permits facile removal of the roll.
• a plurality of supports hold the metal rod along the longitudinal axis of the roll so that eccentricities of the roll are reduced.
• the metal rod will thermally expand more than the body of the roll. Direct contact of the metal rod on the inner surface of the body would produce a tensile stress in the body and could lead to fracture.
• the supports accommodate disparities in thermal expansion.
• the supports may comprise compressible refractory discs and may include refractory fiber.
• the discs accommodate thermal expansion of the metal rod by compressing, thereby transmitting a reduced stress to the inner surface of the body.
• the discs may include at least one passage that permits cooling air to pass through the cavity.
• the metal rod may be held in place using a plurality of collars. As shown in Figure 6, a plurality of collars 61 can be welded to the metal rod 25.
• Each collar 61 includes a plurality of leaf springs 62 that align the metal rod 25 in the middle of the hollow body 5.
• the inner surface 23 of the body 5 compresses the leaf springs 62 thereby exerting a force on the metal rod 25 that resists movement.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
• Tunnel Furnaces (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Laminated Bodies (AREA)
• Rollers For Roller Conveyors For Transfer (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

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Citations (6)

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• 2008
  • 2008-06-16 CA CA2690441A patent/CA2690441A1/en not_active Abandoned
  • 2008-06-16 BR BRPI0813371-9A2A patent/BRPI0813371A2/pt not_active IP Right Cessation
  • 2008-06-16 US US12/663,629 patent/US20100218559A1/en not_active Abandoned
  • 2008-06-16 MX MX2009013669A patent/MX2009013669A/es active IP Right Grant
  • 2008-06-16 UA UAA200913075A patent/UA100515C2/ru unknown
  • 2008-06-16 KR KR1020107000229A patent/KR101419100B1/ko not_active Expired - Fee Related
  • 2008-06-16 RU RU2010101025/03A patent/RU2464242C2/ru not_active IP Right Cessation
  • 2008-06-16 CN CN200880025013A patent/CN101754823A/zh active Pending
  • 2008-06-16 EP EP08771147A patent/EP2164653A4/en not_active Withdrawn
  • 2008-06-16 AU AU2008265902A patent/AU2008265902B2/en not_active Ceased
  • 2008-06-16 MY MYPI20095339A patent/MY154392A/en unknown
  • 2008-06-16 WO PCT/US2008/067070 patent/WO2008157464A1/en not_active Ceased
  • 2008-06-16 JP JP2010512419A patent/JP5480133B2/ja not_active Expired - Fee Related
• 2009
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• 2015
  • 2015-05-21 US US14/718,182 patent/US9695078B2/en not_active Expired - Fee Related

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