Analysis of optical problems in tempered glass

1) The center part is gray

After some glass is tempered, the surface contacting the roller table will appear gray. This situation makes the glass's see-through performance worse, and it often occurs in the middle of the glass. There are two main reasons for this to happen:

① The roller temperature in the heating furnace is too high. This situation often occurs in the first two furnace glasses of the tempering furnace. In this case, you can appropriately increase the pressure of the thermal equilibrium blower or reduce the empty furnace time to ensure continuous glass production;

② The amount of SO gas used is too large. If SO is used as a protective gas for glass, if it is used too much, or it is used too frequently, it will cause a gray phenomenon on the glass surface.


2) The problem of excessive stress spots

The tempered glass produced by the physical tempering method will have stress spots, which is determined by the production principle of physical tempering, and it is also unavoidable. Sometimes this phenomenon is also used to identify whether the glass is tempered glass, but when the stress spot is too heavy, especially when observed under specific light conditions, this phenomenon becomes a problem of appearance quality defects.

The problem of excessive stress spots is usually caused by the following three reasons:

① The wind pressure is too large during the rapid cooling process. This high-pressure, high-speed airflow blows to the softened hot glass, which will increase the stress spots of the tempered glass. This situation can be avoided by adjusting the parameters of the wind pressure;

② When the glass has just entered the cooling chamber from the heating chamber and has started to blow and quench, the swing of the wind grid or the rotation of the roller table is stopped, causing the wind of the wind grid Mouth blows only one part of the glass. When this happens, the wind grid swing or the rotation of the roller table should be synchronized with the air blowing in time;

③ When the air cooling is started in the cooling room, the air nozzle of the air grid is too close to the glass. When this happens, the height of the wind grille can be appropriately increased by adjusting the parameters without affecting the particle size and other quality requirements of the glass.


3) Iridescence of tempered glass

的 The iridescence of tempered glass is an optical phenomenon. During the forming process of the float glass, harmful substances such as oxygen and water enter into the tin bath. Oxidation reaction with tin at high temperature produces SnO and SnO, among which Sn and Sn penetrate into the lower surface of the float glass through the tin solution, and An extremely thin Sn- and Sn-containing layer is formed. When this float glass with high tin penetration is tempered, after the glass is heated in the tempering furnace, the SnO on its surface is oxidized to SnO, and its volume increases, causing tiny wrinkles on the glass surface. Under the irradiation of light, the interference phenomenon of light occurs.

Therefore, the iridescence of tempered glass is related to the quality of the float glass as the original glass, and it is also related to the tempering process. In the tempering production of glass, in addition to selecting high-quality float glass as the original sheet, the heating temperature and heating time parameters of the tempering furnace must be adjusted to adapt to the actual conditions of different original sheet glass.

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