Abstract: In a method for tempering a glass sheet, based on identified glass sheet properties, a tempering furnace temperature and/or glass sheet heating time are adjusted, the blowing pressure and/or distance of cooling unit air jets are adjusted, the glass sheet is heated in a tempering furnace, the achieved temperature is thereafter measured from the glass sheet surface, and the glass sheet is cooled. The development of the thickness direction temperature profile of the sheet during the tempering cooling is calculated, the residual stress profile achieved in the glass sheet during tempering is calculated, a reference variable for the glass sheet tempering level is selected and the selected reference variable is compared to a predetermined threshold value. If the comparison between the reference variable and the threshold value fulfils a predetermined criterion, an alarm is created and/or the glass sheet is found not to qualify as safety glass.

Abstract: The invention relates to a method of heating a glass sheet for tempering. It comprises conveying the glass sheet on top of rollers in a roller-hearth furnace, heating the glass sheet in the roller-hearth furnace to a transfer temperature at which the glass sheet is transferred into an air support furnace. The glass sheet, while resting on an air cushion, is carried on an air support table and the glass sheet is heated in the air support furnace to a tempering temperature. The transfer temperature is not lower than 620° C. and not higher than 675° C. and the tempering temperature is not lower than 650° C. and not higher than 720° C.

Abstract: The invention relates to a method of heating a glass sheet for tempering. It comprises conveying the glass sheet on top of rollers in a roller-hearth furnace, heating the glass sheet in the roller-hearth furnace to a transfer temperature at which the glass sheet is transferred into an air support furnace. The glass sheet, while resting on an air cushion, is carried on an air support table and the glass sheet is heated in the air support furnace to a tempering temperature. The transfer temperature is not lower than 620° C. and not higher than 675° C. and the tempering temperature is not lower than 650° C. and not higher than 720° C.

Abstract: An apparatus for conveying glass sheets on an air support table, which is included in a heating furnace and provided with blast apertures and exhaust apertures, and in which the blast apertures are connected to a plenum chamber present underneath the air support table. The exhaust apertures are connected to exhaust passages present inside the table. The exhaust passages have at least one of their ends provided with a gate/gates capable of being opened and closed, by means of which the flow of air from the exhaust passages' ends adjacent to the gate/gates can be completely or partially blocked.

Abstract: An apparatus for conveying glass sheets on an air support table of a heating furnace, the table having blast apertures and exhaust apertures. The blast apertures are connected to a plenum chamber under the air support table. The exhaust apertures are connected to exhaust passages inside the table, the first end of the passages opening into the furnace or being provided with a closable and openable closing gate. The second end of the exhaust passages opens into a suction duct or is provided with a closable and openable barrier gate. The suction duct of the blower is on the opposite side of the air support table to the conveyor which is in contact with the glass. In the suction duct between the exhaust passages and the blower is at least one adjustable bypass gate which is used for adjusting the air support of the glass.

Abstract: An apparatus for conveying glass sheets in an air support table, which is included in a heating furnace and provided with blast apertures and exhaust apertures, and in which the blast apertures are connected to a plenum chamber present underneath the air support table. The exhaust apertures are connected to exhaust passages present inside the table. The exhaust passages have at least one of their ends provided with gate/gates capable of being opened and closed, by means of which the flow of air from the exhaust passages' ends adjacent to the gate/gates can be completely or partially blocked.

Abstract: A method and apparatus for supporting and heating glass sheets for tempering or bending on a hot gas cushion. One edge of the glass is supported on transport rollers and the rotation axes of the rollers are transverse relative to the plane of the glass. The glass sheet is supported by means of gas pressure on a planar surface which has an angle of inclination of 2-20° relative to horizontal plane. The angle of inclination is sloping towards that edge of the glass which is supported by the transport rollers. Gas is expelled through the planar surface by way of gas outlet slots or holes. As the glass is moving, a gas is drawn or blown by fans from a certain part of the glass through the planar surface more than from the rest of the area by adjusting the rotating speed of the fans or by changing the suction pressure or delivery side pressure of the fans.

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: 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: A method and apparatus for supporting and heating glass sheets for tempering or bending on a hot gas cushion. One edge of the glass is supported on transport rollers and the rotation axes of the rollers are transverse relative to the plane of the glass. The glass sheet is supported by means of gas pressure on a planar surface which has an angle of inclination of 2-20° relative to horizontal plane. The angle of inclination is sloping towards that edge of the glass which is supported by the transport rollers. Gas is expelled through the planar surface by way of gas outlet slots or holes. As the glass is moving, a gas is drawn or blown by fans from a certain part of the glass through the planar surface more than from the rest of the area by adjusting the rotating speed of the fans or by changing the suction pressure or delivery side pressure of the fans.