Method of predicting glass fracture during tempering

A computational method of predicting fracture in sheet glass during tempering was investigated. It was assumed that fracture may be due to two factors: sudden cooling, and a longitudinal temperature gradient. An isothermal state exists prior to cooling. An expression was obtained which is believed to more accurately reflect glass fracture during tempering compared with a previous model, since it incorporates nearly all the parameters that affect fracture: product length and thickness; rate of heat exchange during cooling; tempering temperature; glass strength; and the principal physical constants of the glass. An algorithm and a computer program were developed in order to determine these parameters during the tempering process. 4 refs.