When the glass enters the tempering furnace, its shape will change significantly. Tempering is a heat treatment process, which makes the glass stronger and more impact-resistant through rapid heating and rapid cooling. The high temperature in the tempering furnace will change the molecular structure of glass, which will lead to the change of its shape.
First of all, when the glass enters the tempering furnace, the temperature rises rapidly. This kind of high temperature will make the surface layer of glass expand first, while the internal temperature remains relatively low. This temperature gradient will cause the outside of the glass to be in compression while the inside is in tension.
Next, when the glass is quenched from the tempering furnace, it will quickly transition from high temperature to low temperature. Quenching treatment will make the surface layer of glass shrink rapidly, while the internal temperature remains relatively high. This temperature gradient will lead to further compression of the surface layer and internal tension. Because the outer surface is in compression and the inner part is in tension, the glass will become stronger and more impact-resistant.
Finally, this temperature gradient in the tempering process will also cause the shape of glass to change. Because the surface layer is in compression and the inside is in tension, the shape of the glass will become smoother and more curved. This change makes the glass better resistant to external impact and reduces the risk of breakage.
1. Due to the contact between the glass and the roller table of the tempering furnace, the expansion speed of the lower surface of the glass is higher than that of the upper surface after entering the furnace, and the glass will bend upward and the glass plate will be suspended around, and only the middle part will contact the roller table of the tempering furnace;
2. In this case, the temperature of the glass contacting the roller table will rise faster than that of the surrounding suspended parts (due to heat conduction), and the suspended parts will not contact the roller table to absorb heat until the glass plate is completely softened.
At this time, the temperature of the middle part of the glass plate is much higher than that of the edge part of the glass, which will cause the deformation of the middle part of the glass plate due to too high temperature, thus easily forming the optical distortion phenomenon of the glass after tempering is completed;
3. In view of this situation, we should properly turn up the speed of convection fan at the upper part of tempering furnace or adjust the upper and lower furnace temperatures so that the glass can be quickly flattened in tempering furnace to correct this problem;
Generally speaking, when the glass enters the tempering furnace, it goes through the process of high-temperature heating and rapid cooling, which leads to its shape change. Through tempering, the glass becomes stronger and more impact-resistant, and its shape becomes smoother and more curved, thus providing better safety performance and use experience.
