Tempering glass sheets by cooling comprising subli

专利名称：Tempering glass sheets by cooling

comprising sublimation quenching

发明人：Terry A. Bennett,Herbert W. Eilenfeld,Dewitt

W. Lampman

申请号：US06/460322申请日：19830124公开号：US04445921A公开日：19840501

摘要：In tempering a glass sheet to a high temper by heating the sheet toapproximately its softening point followed by rapid chilling using a quenchingcomposition that comprises a tempering medium having high heat transfer

characterisitcs, the heat-softened glass sheets are protected from breakage duringfabrication and resulting optical distortion by applying the tempering medium throughexit orifices of a delivery system toward the heated glass in a novel cycle. The initiallyapplied tempering medium has a low heat transfer rate and is mixed with a secondtempering medium having a higher heat transfer rate to gradually increase the heattransfer rate of the mixed tempering medium. In a specific embodiment, dry air is the firsttempering medium and a sublimable material, such as carbon dioxide, is the secondtempering medium. The delivery system has an uninsulated portion that assures thatinitially the sublimable material is applied as a gas. Dry air which has a lesser heat transfercoefficient than the sublimable material in its gaseous state, may be supplied to theuninsulated portion if humidity conditions require so that dry air having a lesser heattransfer coefficient is initially directed through the exit orifices followed by mixtures of

dry air with increasing concentrations of said sublimable material in the gaseous statefollowed by increasing concentrations of solid particles of said sublimable material.Movement of the glass sheet is coordinated with movement of the delivery system forsaid quenching composition to avoid \"batter\".

申请人：PPG INDUSTRIES, INC.

代理人：Edward I. Mates

更多信息请下载全文后查看