A multiple stage process for tempering a glass sheet in which a glass sheet, heated to the vicinity of its softening point, is cooled sufficiently rapidly to impart a temper in multiple stages of cooling without marring its softened surfaces to an extent sufficient to impart annoying optical properties.
Electric Glass Sheet Heating Furnace And Method Of Using
Eugene W. Starr - Allison Park PA George W. Misson - Franklin Township, Butler County PA
Assignee:
PPG Industries, Inc. - Pittsburgh PA
International Classification:
C03B 2900
US Classification:
65 25A
Abstract:
In a furnace for electrically heating sheets of glass wherein the glass is supported on a layer of gas, hot furnace gases are internally recirculated by gas flow entrainment means, preferably an air flow amplifier utilizing the Coanda effect. Air supply tubes are electrically heated and arranged over the glass to provide the furnace with thermal energy.
Combination Radiation And Convection Heater With Convection Current Directing Means
A heating system comprising one or more heaters capable of heating by radiation as well as convection incorporating nozzle means extending from an electrically heated gas glow pipe to direct the flow of hot gas providing said convection heating to a region where pressure flow and heat are desired.
Method And Apparatus For Heating Glass Sheets With Recirculated Gas
In a furnace for heating sheets of glass wherein the glass is supported on a layer of gas, hot furnace gases are internally recirculated by means of an air flow amplifier utilizing the Coanda effect. A portion or all of the thermal energy may be efficiently supplied by electric heating.
Method And Apparatus For Producing Heat-Strengthened Glass Sheets Having Improved Break Patterns
Heat strengthened glass is treated to have a break pattern that permits the fractured glass sheet to be retained within an installation frame by moving a glass sheet through a heating area, force cooling the side portions of the moving sheet while cooling the intermediate portions of the sheet at a lesser rate to establish a temperature gradient between the side portions and the intermediate portion, and subsequently applying quenching medium to the entire moving sheet. The temperature gradient in the sheet is achieved by a plurality of baffles, e. g. plates having an imperforate center portion and apertured or slotted end portions and facilities movable relative to quenching nozzles to control passage of quenching medium through the slotted end portions of the baffles to control the temperature gradient imparted to the glass sheet. The movable facilities also permit tempering of glass sheets of varying transverse dimensions.
Special Entrance Slit Module And Method For Quenching Glass Sheets
Eugene W. Starr - Allison Park PA George B. Shields - Lower Burrell PA
Assignee:
PPG Industries, Inc. - Pittsburgh PA
International Classification:
C03B 2704
US Classification:
65114
Abstract:
The present invention relates to a special module for the entrance to a cooling station of a glass sheet tempering apparatus and particularly relates to the construction of a pair of upstream modules at the upstream end of the cooling station immediately beyond the exit of a furnace through which glass sheets are transported for heating for subsequent quenching and rapid cooling in order to impart a temper. The special entrance modules of the present invention are cooled by providing a baffle wall spaced upstream of the upstream wall of each upstream module that faces the furnace exit to provide an open ended air chamber between each upstream module and the furnace. In addition, optionally, coolant may be passed through pipe means provided between the furnace and the upstream modules. These changes in upstream module construction result in producing tempered glass with less kink than prior art apparatus having upstream modules not so modified. Preferably, the baffle walls and the optional pipe means are composed of stainless steel.
Method Of Heat Treating Moving Glass Sheets On Modified Gas Bed
George B. Shields - Lower Burrell PA Eugene W. Starr - Allison Park PA
Assignee:
PPG Industries, Inc. - Pittsburgh PA
International Classification:
C03B 2700
US Classification:
65 25A
Abstract:
This invention relates to the tempering of glass sheets, and particularly concerns cooling heat-softened glass sheets sufficiently rapidly to induce a stress pattern through the thickness of the glass of sufficient magnitude to temper the glass sheets with minimum surface deformation in a process where flat glass sheets are conveyed while supported on a modified gaseous bed that comprises an upstream portion having opposed modules with thin slotted openings that provide thin, discrete, laminar streams of tempering medium against the opposite major surfaces of said glass sheets and a downstream portion having opposed modules that provide a smoother support bed than said discrete streams through a more diffuse pattern of tempering medium.
Kiln And Method For Heating And Bending Glass Sheets
Apparatus for thermally treating glass sheets comprising a combustion chamber, a kiln and a hot gas delivery system for delivering a mixture comprising combustion products into the kiln in such a manner as to avoid deviations from a substantially uniform temperature pattern across the kiln suitable for sag bending and annealing glass sheets. The delivery system comprises a delivery pipe, means for dividing said mixture into two approximately equal flows of said mixture for supplying said flows through a pair of branch pipes, then through the length of a pair of manifolds, each comprising an open ended inner pipe, and a concentric apertured outer pipe. The outer pipes have upwardly directed nozzles of substantially equal cross-section located at approximately uniformly spaced intervals along their length. The mixture flows into the kiln upwardly from said nozzles at a substantially uniform temperature along the length of the outer pipes and blends with the kiln atmosphere to provide a more uniform temperature pattern than is obtained from prior art kiln temperature control systems.