To design the tempering apparatus of glasses, it is important to assess the cooling condition of the given glass. As many authors indicated, residual stresses of the tempered glasses are conducted to the physical properties and behaviors of glasses at high temperatures, its preheating temperatures and its cooling conditions.
In this paper, visco-elastic behaviors of glasses at high temperatures were approximated by Maxwell model, and the analytical solutions of the residual stresses in glasses having various simple shapes were given. The results computed were expressed some simple equations and some figures.
Deformation of glass is easily occurred at high temperature, thence maximum preheating temperature is determined experimentally. Using these results, the cooling condition-that is to assess Biot's number-can be easily decided.