Abstract: An ultrathin glass article has a thickness of less than or equal to 0.5 mm. The glass has a low TTV and a large threshold diffusivity. The glass has a working point T4 of more than 1100° C. and a linear thermal expansion coefficient CTE of more than 6*10-6/° C. in the temperature range between 25° C. and 300° C. A method for producing the article as well as the use of the article is also provided. The glass article can be chemically strengthened and forms surface compressive stress layers on surfaces and center tension layer in the center. The toughened ultrathin glass sheet is more flexible and has extraordinary thermal shock resistance which makes it easier to handle for processing.

Abstract: A method for tempering substantially flat glass sheets. A glass sheet is heated to a tempering temperature and quenching is conducted by blasting cooling air to both surfaces of the glass sheet. The quenching of a top surface and a bottom surface of the glass sheet's both side lanes is commenced earlier or is performed at the early stage of quenching more effectively than the quenching of a top surface and a bottom surface of the glass sheet's middle lane. As a result, the compressive stress required for a desired tempering degree is established on both surfaces of the side lanes earlier than on both surfaces of the middle lane. In order to achieve this, the cooling air enclosures above and below a glass sheet are provided with a subarea of weakened cooling effect.

Abstract: A kiln (10) for annealing glass slabs, which comprises a plurality of heating chambers (20) that are reciprocally superposed and independent, each heating chamber (20) being provided with: at least an access mouth (24, 25) for passage of at least a glass slab (L), a motorized roller plane (30) on which the glass slab (L) rests and moves, heating means (40) suitable for heating the glass slab (L) located in the heating chamber (20) and cooling means (50) suitable for commanding controlled cooling of the heating chamber (20).

Abstract: A method of cutting an article (172) from a chemically strengthened glass substrate (110) includes generating a pulsed laser beam (108) from a laser source (106). The pulsed laser beam (108) may have a pulse duration of less than about 1000 fs and an output wavelength such that the chemically strengthened glass substrate (110) is substantially transparent to the pulsed laser beam (108). The pulsed laser beam (108) may be focused to form a beam waist (109) that is positioned in the same horizontal plane as an inner tensile region (124) of the chemically strengthened glass substrate (110). The beam waist (109) may be translated in a first pass along a cut line (116), wherein the beam waist (109) traverses an edge (111) of the chemically strengthened glass substrate. The beam waist (113) may then be translated in a second pass along the cut line (116) such that a crack (119) propagates from the edge (113) along the cut line (116) ahead of the translated beam waist (109) during the second pass.

Abstract: The invention envisions a method for improving the thermal shock resistance of glass objects. For this a glass object is heated starting from a surface temperature under the softening point (42) on the surface of a first side (3) until the viscosity reaches or goes below a value of 10(7.65±2) poise.

Abstract: In order to permit more effective cooling in comparison to the prior art, in particular in its floor area, of a hollow glass article (1) standing upright on the base (2) of a setting plate (4) provided with transcurrent orifices (9, 9?, 9?) forming a cavity (8) between a base (2) and the facing surface of the setting plate (4) of the standing surface (2?), it is proposed to utilize a part of the orifices (9) situated inside the standing surface (2?) for the supply of cooling air into the cavity (8), and to utilize the remaining orifices (9?) inside the standing surface (2?) only for the extraction of cooling air from the cavity (8).

Abstract: A nozzle housing assembly, which is used in a convection heating furnace for a heat treatable glass sheet. The nozzle housing assembly comprises an elongated enclosure, at least one elongated heating resistance in the enclosure for heating convection air, and orifices in a bottom surface of the enclosure for blasting heated convection air against the glass sheet. The enclosure is divided with a flow-throttling partition into a top supply duct and a bottom nozzle box, the heating resistances being housed in the latter. Flow-throttling openings present in the partition are positioned to comply with the location and shape of the heating resistances.

Abstract: The present invention relates to glass tempering modules of a glass tempering apparatus capable of selectively directing a tempering medium at increased velocity in designated areas of a shaped glass sheet, by the selective arrangement and utilization of quench nozzles in the glass tempering modules, at varying distances from the surface of the shaped glass sheet. A method of tempering a glass sheet utilizing the foregoing apparatus is also provided.

Abstract: A method of manufacturing of strengthened glass containers, and more particularly a method of thermally strengthening glass containers in a glass container manufacturing line while they are on a conveyor intermediate the hot end and the cold end. Glass containers formed at an I. S. machine are conveyed through a special tempering Lehr that heats them uniformly to a high temperature that is short of temperatures at which they may become deformed. Subsequently, the glass containers while being transported on a conveyor are subjected to a unique rapid thermal strengthening cooling process in which the outer and inner surfaces including all areas of the glass containers are simultaneously cooled to a temperature below the Strain Point of the glass used in the glass containers.

Abstract: A device and a method for thermal pre-stressing lengthy hollow objects, in particular glass tubes, are disclosed. The device comprises a heating device, a fixture for receiving an object, and a coolant feed device comprising an outer coolant feed unit with a plurality of nozzles for feeding coolant against an outer surface of the object, and further comprising an inner coolant feed device for feeding coolant against an inner surface of the object.

Abstract: A system and method is provided for tempering a glass container. The method includes the steps of pre-heating the glass container to a first predetermined temperature. The method also includes the steps of applying radio-frequency energy to the pre-heated glass container to heat the glass container to a second predetermined temperature and, after a predetermined amount of time, simultaneously cooling at least one surface of the heated glass container to a third predetermined temperature to treat the glass container. The method further includes the steps of, after a predetermined amount of time, quenching the treated glass container to a fourth predetermined temperature to produce a tempered glass container.

Abstract: A glass tempering apparatus is capable of selectively delivering increased volumes of tempering medium to designated areas of a moving glass sheet to create desired stresses in such designated areas by the specific arrangement of nozzles in the glass tempering apparatus. A method of tempering glass utilizing the subject apparatus is also provided.

Abstract: The invention relates to an installation and a method for producing glass stoppers which are provided with a head portion and are used for sealing wine bottles and sparkling wine bottles. Said installation comprises a mold for producing glass stoppers, a feeder system for supplying the mold with molten glass, a multistation press, and a removing and handling system for the finished glass stoppers.

Abstract: A method of fabricating a glass sheet comprises modifying the thermal stress in the glass such that it is a tensile stress or substantially zero stress in a particular temperature zone of the glass, with that zone selected such that the glass sheet is formed substantially free of warping. In an example embodiment, the modifying of the thermal stress is effected by non-uniform cooling of the glass across the glass transition temperature range. This non-uniform cooling may be applied in cooling segments that are linear and at least two of the segments have differing slope.

Abstract: A method and apparatus for heating glass sheets in preparation of tempering. A furnace (1) is provided with upper and lower convection blasting conduits (11, 14) extending lengthwise of the furnace. The furnace is also provided with upper and lower radiation heating elements (12, 16). The convection heating air is pressurized with a compressor (3), cleaned with a filter (4). The upper convection heating air is heated with air discharged from the furnace in a plurality of separate heat exchangers (7), through which the convection heating air is passed into the upper convection blasting conduits (11). The amount of air discharged from the furnace (1) through the heat exchangers (7) is substantially equal to that blasted into the furnace for convection heating.

Abstract: A flat glass plate having a low residual stress, suitable for use in preparing a display, can be prepared without an annealing or polishing process by way of controlling the horizontal temperature gradient of a molten glass plate to a specific range during cooling.

Abstract: In a method and an apparatus for heating glass panels in a tempering furnace equipped with rollers, glass panels are carried on a conveyor defined by rollers into a tempering furnace for the duration of a heating cycle, followed by carrying the glass panels into a tempering station. The glass panels are heated in the tempering furnace by bottom- and top-heating radiation elements as well as by bottom- and top-heating convection elements through which convection air is supplied to the tempering furnace. The glass panels' bottom side is heated by the bottom-heating convection elements, which are arranged lengthwise along the furnace and define convection heating zones side by side in a lateral direction of the tempering furnace. Thus, convection heating effects of the convection heating zones can be altered relative to each other for profiling the heat transfer coefficient in a lateral direction of the furnace.

Abstract: A glass plate has a thickness of from 1.5 to 3 mm, and it has a peripheral region having a predetermined width along the edge line of the plate and having its principal stress difference of compressive properties, an intermediate region having a predetermined width adjacent to an inner periphery of the peripheral region and having its principal stress difference of tensile properties and a central region occupying an inner peripheral side of the intermediate region wherein the central region has an averaged surface compression stress of from 15 to 35 MPa, and the peripheral region has a width of from 5 to 20 mm; the maximum value of the principal stress difference averaged in a thickness direction of the plate along its center line is from 20 to 40 MPa, and the minimum value of the principal stress difference averaged in a thickness direction along the center line is from 8 to 25 MPa.

Abstract: During a process for bending and quenching a window pane, the latter is bent to the desired shape using a forming frame. Next, by means of this same forming frame, the entire surface of both sides of the bent window pane is rapidly cooled, in a quenching station which follows the bending station, by blowing cold air using blowing boxes provided with blowing nozzles. While the entire surface is being rapidly cooled, the edge regions of the window pane which rest on the forming frame are subjected to a blast of additional cold air by the suitable supply of compressed air to the openings passing through the forming frame.

Abstract: A method of thermally treating a glass or glass-like material, preferably a glass sheet, without the use of conventional tunnel-type furnaces, to effect rapid heating of glass and glass-like materials from any initial temperature to any required temperature so that the glass sheet can be processed by shaping, bending, tempering, annealing, coating and floating of the glass sheet without cracking of the glass sheet is described. In the inventive method a microwave radiation with appropriate uniformity, frequency and power density is chosen so as to accomplish glass heating from any initial temperature to any required (e.g., softened) temperature in a selected short time while ensuring that the temperature distribution on the external surfaces and in the interior of the glass sheet that arises from microwave exposure is uniform enough to prevent the exposed glass sheet's internal thermal stress from exceeding its modulus of rupture, thereby avoiding glass breakage.

Abstract: A method of heating low emissivity glass sheet for subsequent processing. The glass sheet is loaded onto a longitudinally extending conveyor and oriented such that the lengthwise edge of the sheet is parallel to the length of the conveyor and the direction of conveyance of the glass sheet. The sheet is conveyed into a heating chamber. The glass sheet is then convectively heated in a specified sequence along the entire length of the glass sheet at selected areas measured along the width by creating a downward flow of heated air proximate the selected areas.

Abstract: A glass quenching apparatus for quenching a glass sheet heated to a predetermined temperature, includes a first nozzle group for jetting blower air onto opposite surfaces of the glass sheet, and a second nozzle group for jetting compressor air onto at least one of the opposite surfaces of the glass sheet. The first nozzle group is comprised of stationary nozzles, and the second nozzle group is comprised of movable nozzles which are capable of moving parallel to a plane of the glass sheet. The glass quenching apparatus of the foregoing construction is able to quench the glass sheet uniformly over the entire area thereof without undue wastage of quenching air.

Abstract: A method of thermally treating a glass or glass-like material, preferably a glass sheet, without the use of conventional tunnel-type furnaces, to effect rapid heating of glass and glass-like materials from any initial temperature to any required temperature so that the glass sheet can be processed by shaping, bending, tempering, annealing, coating and floating of the glass sheet without cracking of the glass sheet is described. In the inventive method a microwave radiation with appropriate uniformity, frequency and power density is chosen so as to accomplish glass heating from any initial temperature to any required (e.g., softened) temperature in a selected short time while ensuring that the temperature distribution on the external surfaces and in the interior of the glass sheet that arises from microwave exposure is uniform enough to prevent the exposed glass sheet's internal thermal stress from exceeding its modulus of rupture, thereby avoiding glass breakage.

Abstract: Glass or glass ceramic plates with elevated thermal resistance and process for their production. After cooling, the glass or glass ceramic plates are subjected to zone annealing, whereby the plates are divided into two zones in which annealing is done at respectively different temperatures, and whereby the zones with the elevated temperature correspond, during annealing, to the sub-areas of the finished glass or glass ceramic plates in which compression stress builds up after uneven heating corresponding to the respective specific application of the glass or glass ceramic plates. The glass or glass ceramic plates that are obtained are thus characterized in that they are divided into two sub-areas, whereby one sub-area exhibits structural compression and the other sub-area exhibits compression stress. Glass or glass ceramic plates that are resistant to breakage that is caused by uneven heating result.

Abstract: A glass sheet quench unit (22) and method for quenching formed glass sheets by quench gas jets (40) that define a uniformly repeating gas jet impingement pattern (44) that is an equilateral triangular pattern providing uniformly repeating quench cells (46) distributed over the formed glass sheet to be quenched as equilateral hexagonal quench cells. The resultant product is a formed and quenched glass sheet (G) that has oppositely facing surfaces between which glass stresses are uniformly distributed. A method for making the quench unit (22) is performed by initially forming nozzle openings (38) in an elongated nozzle strip (36′), thereafter forming the nozzle strip with a curved cross section, thereafter forming the nozzle strip with a curved shape along its elongated length to provide a curved nozzle cap, subsequently securing the curved nozzle cap to planar sides (30) of an associated nozzle feed row (28), and securing the sides (30) of the nozzle feed row to a plenum housing (24).

Abstract: A toughened glass sheet for use as a windowpane of an automotive vehicle. The toughened glass sheet has a thickness ranging from 2.5 mm to 3.1 mm and has a first characteristic that a number of fragments is not less than 40 within an area of 50 mm.times.50 mm in a fragmentation test in which an impact is applied to a predetermined position of the glass sheet with a hammer or a punch, and a second characteristic that a specified height is not less than 2 m in an impact resistance test in which the specified height is a value at which the glass sheet is broken upon dropping a steel ball having a weight of 227 g.

Abstract: In a quenching apparatus for quenching a glass sheet that has been heated and bent in a heating furnace, a cooling gas blows onto the glass sheet to provide a distribution of a temperature and/or a distribution of a static pressure in at least one section in the quenching apparatus. The distribution of a temperature provides different temperatures between the both surfaces of the glass sheet, while the distribution of a static pressure is nonuniform in a part of at least one surface of the glass sheet. The distributions can modify a shape of the glass sheet given in the heating furnace so that a degree of freedom in shape for manufacturing a bent and tempered glass sheet by utilizing its self-weight can be improved.

Abstract: A process and apparatus (26) for quenching a heated glass sheet by directing modulated cryogenic flows (36) that is initially completely liquid (42) toward the oppositely facing surfaces (38) of the glass sheet to quench the glass sheet. The modulated cryogenic flows (36) can be started and fully stopped to provide flow pulses and can also be continuous and have periodic increased flow pulses.

Abstract: Diclosed is a plate glass wherein surfaces (3a) of plate glass (3) are formed flat and finished with a maximum surface ruggedness not exceeding 0.05 mm, and boundaries (3c) between end surfaces (3a) and front and back surfaces (3b) of the plate glass (3) are finished with a maximum surface ruggedness not exceeding 0.007 mm. Thus, though the plate glass is treated with heat reinforcement by the method simpler and more convenient than the prior art, the plate glass maintains performance as fire glass. It is now possible to provide quality improvement as plate glass, a reduction in running cost of heat reinforcing treatment equipment, and a reduction in working stress due to the weight of the plate glass itself in time of fitting the plate glass.

Abstract: A method of and apparatus for bending and tempering a sheet of glass heated to a formable state provides an improved rigid mold and pressing member for pressing the heated sheet against the rigid mold which cools and bends the sheet. The pressing member includes a conformable pressing element which permits a manifold to be positioned between the rigid mold and the pressing member to direct a gas to cool the heated sheet of glass during bending. The conformable pressing element is pressurized into a convex shape for initially pressing on a portion of the heated sheet and for rolling the heated sheet onto the rigid mold. The rigid mold and the conformable pressing element may each include a cover to increase the heat transfer from the heated sheet to the bending and tempering apparatus. Furthermore, the covers may have increased thermal conductivity in their peripheral regions for increased cooling of the edge of the sheet of glass.

Abstract: A process for quenching a heated glass sheet is performed by apparatus (26) that includes a pair of quench units (28) between which the glass sheet is located with each quench unit having nozzles (34) for directing cryogenic flows (36) including a liquid (42) toward the oppositely facing surfaces (38) of the glass sheet so that the liquid completely vaporizes before penetrating the gas boundary layer (40) on each surface of the glass sheet. The cryogenic flows (36) can be initially completely liquid (42) or can be a two phase as the liquid (42) and a gas (44) with the latter preferably being done by spraying the two phase cryogenic flows as liquid droplets and the gas.

Abstract: A process for quenching heated glass sheets is performed by locating a glass sheet between a pair of spaced quench units (28) and directing from first and second arrays of nozzles (34, 64) cryogenic flows (36) interspersed with pressurized air flows (66) so as to cooperate with each other in providing the quenching. In one practice the interspersed cryogenic flows (36) and the pressurized air flows (66) are provided at the same time as each other. In another practice, the interspersed cryogenic flows (36) and pressurized air flows (66) are provided at different times.

Abstract: A cooling ring assembly (20) and method for controlling stresses in a bent glass sheet G produce a strengthened bent glass sheet after the cooling is completed. The cooling ring assembly includes a cooling ring (22) that supports the glass sheet edge (24), an insulator (30) juxtaposed inboard of the cooling ring to reduce the cooling rate, and a cooler (34) for providing increased cooling by pressurized air to at least one localized area (36,40,58) of the glass sheet edge. The cooler (34) is preferably embodied by a pressurized air supply (42).

Abstract: Air is blowed before an annealing step to corner portions in an inner face portion of a glass panel which has been press-formed in a mold to cool that portions to be stronger than the other portion whereby a temperature difference between the corner portions and the other portion is reduced.

Abstract: A glass plate is cooled and strengthened by placing the glass plate on a cooling ring in a substantially horizontal state and jetting out cooling air at upper and lower sides of the glass plate by upper and lower cooling air jetting-out devices arranged at the upper and lower sides of glass plate. The pressure of cooling air jetting out from the lower side of the glass plate is higher than that from the upper side to thereby raise the glass plate against a contact ring located below the upper jetting out device.

Abstract: A cooling ring assembly (20) and method for controlling stresses in a bent glass sheet G produce a strengthened bent glass sheet after the cooling is completed. The cooling ring assembly includes a cooling ring (22) that supports the glass sheet edge (24), an insulator (30) juxtaposed inboard of the cooling ring to reduce the cooling rate, and a cooler (34) for providing increased cooling to at least one localized area (36,40,58) of the glass sheet edge. The cooler (34) is embodied by a pressurized air supply (42).

Abstract: Quenching apparatus (12) for use in glass heat treatment apparatus comprises a plurality of air flow amplifiers (32) carried on manifolds (26, 28) and arranged in arrays to direct cooling air onto both surfaces of glass (16) being treated. Compressed air is supplied to the manifolds (26, 28) from air receivers (22) charge by a compressor (20) the compressed air flow being controlled by a control valve (24). Air flow received by the air flow amplifiers (32) from the manifolds (26, 28) is amplified to supply a flow of cooling air directed towards the sheet of glass (16). The air flow amplifiers (32) may be air ejectors. A furnace (10) is provided to heat the glass (16) and a conveyor is provided to carry the glass (16) from the furnace (10) to the quenching apparatus.

Abstract: A glass bulb is physically reinforced to provide a tensile stress in the nearly central portion of wall thickness in the wall thickness direction and to provide a compressive stress on the surface. The physical reinforcement is specifically applied by air cooling reinforcement. The completed CRT is further shrinkage fitted so as to tighten the outer side face of a panel by a metal ring. At the time of the air cooling reinforcement, reinforcement is optimized by reinforcing the glass bulb (or the panel or a funnel) so as to be more effective by adding the stress distribution in a vacuum state of the picture tube having a rectangular screen and by the shrinkage fitting achieved by the metal ring. As a result, the problem of heavy weight, which was one of major defects of mass produced CRTs, is solved while the risk of implosion is still avoided.

Abstract: A glass sheet annealing ring includes an insulating ring juxtaposed the inboard periphery of the annealing ring for reducing the cooling rate of the glass sheet in proximity to the insulating ring thereby reducing the magnitude of net inner band tension while maintaining edge compression as the glass sheet is cooled.

Abstract: A method for the preparation of glass sheets with a view to laminating them consists of curving the glass sheets by causing them to pass one after another along a curved trajectory, then cooling them by passage between blowing chests, and of dispatching them by batches to the assembling station, and a laminated pane, the sheets of which have, in the central zone, a core compressive stress of from 1 to 50 MPa.

Abstract: A method for the preparation of glass sheets with a view to laminating them consists of curving the glass sheets by causing them to pass one after another along a curved trajectory, then cooling them by passage between blowing chests, and of dispatching them by batches to the assembling station, and a laminated pane, the sheets of which have, in the central zone, a core compressive stress of from 1 to 50 MPa.

Abstract: A glass sheet annealing ring includes an insulating ring juxtaposed the inboard periphery of the annealing ring for reducing the cooling rate of the glass sheet in proximity to the insulating ring thereby reducing the magnitude of net inner band tension while maintaining edge compression as the glass sheet is cooled.

Abstract: The invention relates to a nozzle assembly for a flat-glass tempering machine. A nozzle cover (2) includes two types of orifices side by side. A number of orifices (7, 8) are linked to the pressure of a compressor (11) and another number of orifices (6) are linked to the pressure of a blower (12). Thus, the different orifices supply air of different pressures.

Abstract: An apparatus for use in the manufacture of a color cathode ray tube that includes a faceplate with a screen embraced by which rails support a flat tension mask. The apparatus includes a radiant heat source for heating the faceplate, and shielding means including a heat shield for shielding a central area of the faceplate from the radient heat source. Stresses induced in the corners of the faceplate by the rails during thermal cycling of the tube are dispersed in the cooler central area of the faceplate.

Abstract: The invention relates to a method of toughening a glass sheet by heating it to a temperature above the strain point and quenching the heat glass sheet while it is advancing horizontally by blowing cooling gas jets onto each face of the glass sheet from an array of nozzles. In advance of such quenching, the heated glass is preliminarily cooled to some extent so as to cool the glass sheet at a relatively high rate in substantially parallel stripe-like regions, which make an angle greater than 45.degree. and not greater than 135.degree. with the direction of advance of the glass sheet, than in other regions. As a result, relatively high toughening occurs in the stripe-like regions. Preferably the preliminary cooling is made only in a central area of the glass sheet. The preliminary cooling has the effect of compensating a toughening pattern attributed to the unidirectional movement of the glass sheet under quenching, so that the toughened glass sheet is satisfactory in the manner of fragmentation.

Abstract: Glazings are preshaped before putting them through a step of tempering by contact. In a preferred variant, tempering by contact is applied only the central area of the glazing and the marginal zone thereof is tempered by blowing cold air.

Abstract: The invention relates to heat treatment of a glass plate for strengthening only a peripheral region of the glass plate while annealing the major region. The glass plate is heated to a temperature of 550.degree.-650.degree. C. and placed on a ring-like holder which is maintained at a temperature lower than the temperature of the glass plate by 100.degree. to 600.degree. C. such that the peripheral region of the glass plate makes contact with a ring-like upper surface of the holder. Then glass palte on the ring-like holder is kept in an annealing chamber maintained at a temperature in the range from 50.degree. to 500.degree. C. and not higher than the initial temperature of the ring-like holder. After that the glass plate is allowed to cool down to room temperature. This method is applicable to either flat glass plates or curved glass plates and very suitable for treating glass plates ranging from 1.5 to 3.0 mm in thickness.

Abstract: An improved glass tempering apparatus and method is disclosed. A glass sheet is quenched by heating the glass sheet and horizontally transferring the sheet on a roller conveyor into a quenching station having an upper and lower array of nozzles for directing coolant on opposite sides of the glass. A first array of points on the glass sheet are cooled, then the glass is horizontally jogged within the quenching station and a second array of points are cooled. Preferably, the jog distance is selected so that the first and second array of points are uniformly spaced relative to one another. An alternative embodiment of the invention cools a first array of points, horizontally jogs the glass within the quenching station and recools the same array of points with each point being cooled by a different nozzle pair so that the cooled points are uniformly sized and clearly defined with minimum irregularities resulting from roller shrouding and nozzle-to-nozzle variability.

Abstract: A manufacturing line for tempering glass sheets includes a furnace, an oven, a bending station, and a chilling section positioned in order along a generally horizontally extending conveyor for the glass sheets. The oven extends between the furnace and the bending station to maintain the glass sheets at a predetermined temperature. The oven has sidewalls formed of a plurality of brushes and is selectively extensible along the path of travel of the glass sheets. The oven includes controlled heating devices. The chilling section includes a plurality of tubes positioned above and below the path of travel of the glass sheets and connected to a source of air under pressure. The tubes are arranged in rows generally perpendicular to the path of travel and columns generally parallel to the path of travel in order to cause the glass sheets to meet predetermined fragmentation specifications.

Abstract: Compression stresses are formed on the periphery of a glass sheet by blowing cooling air on the periphery of the heated glass sheet. The cooling air is blown by using a pyramidal deflector to deflect air flow radially outward toward the edges of the glass sheet. By adjusting the spacing between the deflector and the glass sheet, the size of a central, relatively quiescent, zone can be adjusted. The air flow is provided by a duct which can include a pyramidal skirt which surrounds the deflector to form a gas flow path whose size controls the cooling rate. Pyramidal flaps within the gas flow path can be used for adjusting cooling gas pressures.