Optimizing glass block annealing

Analysis has shown that the margin of performance in furnaces used for annealing complicated glass components, including blocks, at various plants is not exhausted. The annealing of glass blocks and other massive items in convective ovens was studied. Ways of accelerating the process were considered. Annealing ovens work less stably in the Summer than in the Winter and the yield of satisfactory product is much lower. Increasing the oven length was shown to be an effective means of reducing scrap at the No.1 oven at Grodnyy Glass Plant, but lack of space for the No.2 oven meant that an alternative solution had to be found. Modification to the No.2 oven made it readily controllable and allowed the temperature and times to be adjusted within the required ranges. Optimisation of the annealing conditions ensured that residual stresses in the glass blocks did not exceed 100 nm/cm. This is the GOST 9272-81 permissible level. The scrap rate was reduced by 80%. 4 refs.