Heating glass sheets in tempering furnace
AssigneeUniglass Engineering Oy
InventorJukka Vehmas
Life of this patent
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Abstract
A method and an apparatus for heating glass sheets in a tempering furnace. The tempering furnace (1) includes rollers (3) for conveying and oscillating the glass sheets (4) during heating, and resistors (5, 6) for heating the glass sheets (4) from above and from below. The lower part of the tempering furnace (1) is cooled at the initial stage of the heating period, and the lower surfaces of the glass sheets (4) are heated at the final stage of the heating period by forced convection. This ensures good control over heat equalization in the tempering furnace (1), increases furnace power, prevents curving of the glass sheets (4), and also reduces heat shock from ceramic rollers at the initial heating stage.
Claims18
A method of heating a glass sheet in a tempering furnace, to temper the glass sheet, said method comprising conveying a glass sheet into the tempering furnace on spaced rollers, heating the glass sheet from above and below during a heating period, oscillating the glass sheet in a reciprocating manner during said heating period, cooling a lower part of the tempering furnace below the glass sheet during the heating period, and heating the glass sheet from below by forced convection during a final stage of the heating period of the glass sheet.
Apparatus for tempering a glass sheet, said apparatus comprising a tempering furnace, a plurality of horizontal, spaced rollers in said furnace for supporting a glass sheet horizontally in the furnace and form a conveyor for the glass sheet, means in the furnace for heating the glass sheet from above and below, said rollers being adapted to oscillate the sheet in a reciprocal manner during a heating period in the furnace, means for cooling a lower part of the furnace below the glass sheet during said heating period and means for heating a lower surface of the glass sheet by forced convection during the heating period.
Dependencies are inferred from the claim text.