The Role of Preheating in Glass Tempering Furnace And The Temperature Setting Method for Glass Tempering Furnace

The key to controlling the quality of tempered glass production is to adjust and control the temperature of the tempering furnace. Experienced operators will preheat the tempering furnace during the production process. Do you know the role of preheating the glass tempering furnace? Below, we will introduce the influence of preheating process on the properties of tempered glass and how to set the specific heating temperature.

1. The role of preheating in glass tempering furnace

1.1. Improving glass flatness: The degree of curvature of tempered glass varies with temperature. It is understood that at a temperature of 465 ℃, the degree of curvature of tempered glass is less. Therefore, preheating the tempering furnace can quickly reach the surface temperature of the glass when it enters the heating section, reducing deformation caused by temperature changes.

1.2. Shortening processing time: The main function of preheating is to increase the temperature of the glass substrate, shorten the time cycle required in the processing and production process, thereby improving the product yield, increasing production capacity, and glass yield. On the other hand, it is to improve the overall economic benefits.

1.3. The influence of surface stress: Although preheating temperature is not the main factor affecting the surface stress of tempered glass, it has a certain impact on the curvature of glass. As the temperature decreases, the curvature of tempered glass increases. At the same time, temperature still has an overall impact on the surface stress of glass.

2. Temperature setting method for glass tempering furnace

The setting of the upper and lower temperatures varies due to the thickness of the glass, and the setting of the heating temperature is also different. The principle is that the thinner the glass, the higher the temperature, and the thicker the glass, the lower the temperature. The heating power of the tempering furnace is fixed, and the usually set heating time is about 35-40 seconds per millimeter of glass thickness. For example, the heating time for 6mm thick glass is about 6 * 38 seconds, which is 228 seconds. This calculation method is suitable for ordinary tempered glass with a thickness less than 12mm. When the thickness of glass is between 12mm and 19mm, the basic calculation method for heating time is about 40-45 seconds for every 1mm thickness of glass. When producing bent tempered glass, the heating time increases by 2.5 to 5 seconds per millimeter of thickness of glass. When tempered glass with holes or grooves, the heating time needs to be increased by 5% based on this calculation method. Glass with sharp angles (less than 30 ° angle) and gray glass require 2.5% more heating time in this calculation method.

Note that the heating rate of glass is slower before reaching the tempering temperature. We need to understand a basic principle: if the temperature setting of the electric furnace changes by a few degrees, we also need to make the heating temperature of the glass change by the same temperature. We need to change the heating time by ± t seconds to ensure that the temperature of the glass coming out of the electric furnace remains unchanged within ± t seconds.

The above is an introduction to the role of preheating glass tempering furnace and the temperature setting method of tempering furnace. Preheating tempered glass can improve the smoothness of the glass surface and increase the yield of finished products. Of course, not only preheating, but also correctly controlling the furnace temperature during the heating process is crucial.