Basic principles of double chamber tempering furnace
In order to obtain good product quality, glass toughening process has some important basic requirements must be complied with.
In the operation of double chamber furnace, due to the two-stage furnace structure, in the production of glass, it is necessary to accurately set the temperature of the preheating section and heating section. The preheating section is forced convection up and down. In order to produce good quality glass, the temperature should be set a little lower. The heating section is to make the glass reach the soft point quickly. At this time, the temperature must be set high, so that the glass can quickly reach the required temperature on the glass surface. There are variations in shape damage, size deviation, optical property change or leaving traces.
In order to achieve the above basic requirements, the following list of some basic principles, hoping to help operators in the initial stage of tempered glass production can establish a basic concept.
According to the standard glass heating capacity, the heating time per mm thick glass is 30-45S, that is, the standard heating time of 5mm glass is 150-220S, the standard heating time of 8mm glass is 240-360S, the standard heating time of 10mm glass is 350-450S. But this is not a fixed number, different types of tempering furnaces or different manufacturers of tempering furnaces will have different heating time requirements for different designs; in addition, the setting of temperature will also change the length of heating time, usually higher temperature setting can make the same glass in a shorter time to reach the required temperature. In turn, a relatively low temperature setting allows the same glass to take a longer time to reach the desired temperature, thereby reducing production.
Although on the surface it seems that raising the temperature setting can achieve higher economic benefits, there are still some principles to be followed so as not to affect the quality of tempered glass and the success rate of glass tempering.
Effect of heating time on glass
Usually a longer heating time can result in a more uniform temperature distribution in glass, especially in large glass.
It is obvious that the uneven temperature distribution of glass will make the strengthening stress of glass unable to form evenly after toughening. Usually this can be done by crushing test. In addition, the uneven distribution of strengthening stress will easily cause the glass to spontaneously explode. When the glass is toughened, it will break in the strengthening zone. So in production, we must pay attention to setting the heating time and temperature according to the specifications and thickness of the glass.