The Consequences of Rapid Too Fast Heating Speed in Glass Tempering Furnaces And The Correct Heating Method

The temperature control of the glass tempering furnace is an important factor that directly affects the quality of tempered glass production. We not only need to control the temperature and duration of heating or cooling during the production process of the tempering furnace, but also need to control the heating rate of the tempering furnace. Below, we will talk about the consequences of rapid temperature rise in glass tempering furnaces and the correct methods for temperature rise.

1. The consequences of rapid heating in glass tempering furnaces

1.1. Impact on equipment: Excessive heating speed of the tempering furnace may have an impact on the ceramic roller conveyor. For the ceramic roller conveyor of new equipment, there is a certain moisture content. If the temperature is raised too quickly, the ceramic roller conveyor may break. The used ceramic roller conveyor will undergo deformation if rapidly heated or cooled, and it is irreversible. Once the roller conveyor deforms, it will scratch the glass during the production process, and it is difficult to find the specific location of the deformation, so the roller conveyor can only be replaced.

2.1.2. The impact on tempered glass: During the heating process of the tempering furnace, the temperature of the first 300 degrees should not rise too fast. If the heating speed is too fast, it will cause a large temperature difference between the glass and the tempering furnace. If the glass is heated too fast in the furnace, it will cause deformation inside the glass furnace, affecting the surface flatness of the glass. In severe cases, stress spots may appear, affecting the surface quality of the glass.

2. Correct heating method for glass tempering furnace

2.1. When the tempering furnace is first heated up, a heating rate of 30-50 hours can be set. Depending on the residual moisture content of the furnace body, the tempering furnace can be insulated for 2-4 hours in the temperature ranges of 200 ° C, 300-350 ° C, 400-450 ° C, and 550 ° C. Within these temperature ranges, the tempering furnace should be insulated for a total of 8-12 hours to ensure that the furnace structure will not deform due to rapid heating;

2.2. After the temperature of the tempering furnace rises to the working temperature, it must be insulated for at least 1 hour before production can begin; In theory, the slower the temperature rise of the tempering furnace, the better. The initial temperature rise of a new furnace should be at least 72 hours, and the power should not be too high. An increase of 30% and a decrease of 20% are sufficient; The normal heating time is controlled within 10-12 hours, with a power increase of 25% and a decrease of 20%.

2.3. When the temperature of the tempering furnace is below 400, the furnace body can be raised by 30-100mm, and the heat dissipation valve of the furnace body and the front and rear furnace doors of the tempering furnace can be kept open, which is conducive to the discharge of water and gas from the furnace body;

2.4. In addition, adding a preheating furnace or one furnace with two chambers can solve the problem of uneven heating temperature rise on the upper and lower surfaces of Low-E glass caused by low radiation heat transfer efficiency at 300 ℃. Adding a preheating furnace can reduce the waiting time and improve production efficiency.

The above is a specific introduction to the consequences of excessive heating in glass tempering furnaces and the correct heating methods. The correct operation of tempering furnace equipment is the key to controlling the production quality of tempered glass. Therefore, preheating and heating work should be done well, and the parameters during tempering should be adjusted according to different glass specifications.