PURPOSE: To prepare high-quality tempered glass having high tempering degree free from cloudiness on the surface, by bubbling a molten salt containing a large amount of inorganic potassium salt, having a specific viscosity, followed by immersing plate glass heated at ≤ a strain point in it.
CONSTITUTION: The immersing tank 1 is charged with the molten inorganic salt 2 having ≥70wt% inorganic potassium salt, having a viscosity of 2W30 centipoises, air is fed from the bottom of the tank 1 through the valve 6 and the pressure gauge 5 to the pipe 3, and it is bubbled through the molten salt. In the operation, when the gauge pressure of the pressure gauge 5 is represented by hg, and the liquid pressure of the pipe 3 is represented by ha, the pressure is made to satisfy the relationship shown by the formula hg-ha=10W50mmH2O. The plate glass 4 heated at ≥ a strain point is immersed in this quenching device so that it is tempered by quenching.
ARAYA SHINICHI
MURAMOTO TADASHI
SATOU KIYOUZOU
SATO KIYOUZOU
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