How to heat glass in tempering furnace
When the glass is heated in the tempering furnace, if the electromagnetic wave radiated by the heat of the tempering furnace passes through the object and is not absorbed, the object is called transparent. If the electromagnetic wave radiated by the heat can pass through completely, part of it is absorbed and part of it is reflected back, the object is called semi transparent to this light. If the heat radiation electromagnetic wave of the tempering furnace is absorbed by the object, the object is opaque to the heat radiation electromagnetic wave. Therefore, when setting the heating temperature, choose the range where the radiation wavelength of the heating element can be fully absorbed by the glass under the temperature, which can shorten the heating time and improve the efficiency. The process of heat transfer from glass surface to center and from ceramic roller surface to glass surface.
The heating furnace of the tempering furnace shall reach the appropriate heating temperature; the heating shall be rapid; the temperature distribution in the furnace shall be balanced and symmetrical, and the temperature difference on the glass surface shall be less than 5 ℃.
A suitable temperature region for glass toughening is a temperature region where glass changes from brittle state to plastic state, i.e. near the softening temperature of glass. In this region, the residual stress of glass can be relaxed and eliminated rapidly and completely, and the glass can obtain temperature gradient, toughening degree and toughening stress.
When the glass just enters the furnace, the heating speed is quite fast. This is because the temperature difference between the glass and the furnace is very large, and the heating speed is very fast. With the decrease of the temperature difference between the glass and the furnace, the heating speed slows down. When the temperature difference between the inner and outer layers of the glass tends to zero, the heat transfer is very slow, and the heating should be stopped at this time.