Heat generation and control of glass tempering furnace

At present, the main heating element of the glass tempering furnace is the resistance furnace, and all of its heat comes from the electric heating element. Whether the setting of the main process parameters of the glass tempering furnace effectively affects the quality and output of the product throughout the entire production process. When setting each major parameter, it is necessary to understand its function and setting basis, as well as the interaction between each major parameter, to ensure high-quality production. Below, we will explain the heat generation and control of glass tempering furnaces.

1. Heat generation in glass tempering furnace

In the process of tempered glass production, the heating process of the glass is carried out one furnace at a time. Each time, we need to raise the glass from room temperature to about 700 ℃ and maintain it for a period of time. Then, after the glass comes out, we quickly stabilize the temperature and wait for the next furnace to start. For ease of explanation, we divide the production process into two scenarios: heating and warming up. The required heat and its impact on furnace temperature are also different for these two situations.

1.1. Insulation

The heat generated is only used to balance the heat loss caused by heat dissipation in the furnace, and its heat string remains unchanged, and this change is very slow. The PID adjustment method has a good control effect, which can control the furnace temperature at around plus or minus 1 ℃.

1.2. Heating up

After the glass enters the furnace, the original thermal temperature state is broken, and the temperature inside the furnace suddenly decreases, with a temperature drop range of 20 ℃ to 100 ℃. When the temperature of the glass rises, the furnace temperature gradually approaches the preset value. When the temperature of the glass is consistent with the furnace temperature, heating will be completed. The rapid change in furnace temperature can easily lead to excessive adjustment of the temperature control system, and the fine control required for temperature control is not reflected, which is known as temperature lag and large inertia. Although using it? PID adjustment, but the effect is not very good. When controlling temperature, this is one of the principles that needs to be avoided.

If the stored thermal energy is much greater than the heat required by the heating element (heat absorber), the sudden entry of the heat absorber will not cause a drastic change in furnace temperature. At present, in the tempering furnace, in order to improve the heat storage capacity of the furnace body, a radiation plate is used to cover the outside of the electric furnace wire of the tempering furnace. The segmented heating method can also be used to divide the heating furnace into several different furnace temperature sections from low to high, which can also reduce the sharp changes in furnace temperature for glass.

2.、 Heat Control of Glass Tempering Furnace

2.1. Resistance control strategy

Different control strategies have been adopted for different stages. If in the first half of the heating process, the glass will experience uneven temperature during heating, then opening the upper and lower heat balance can effectively solve the problem of excessive temperature changes in the upper and lower parts of the glass. In the later stage, the temperature of the upper and lower parts of the glass does not change much, and the main purpose is to increase the heating rate. The various thermal balances can be turned off, and the electric heating mainly adopts feedforward control. During the waiting period, in order to control the thermal inertia of each heater, feedforward and? PID control. During this process, the temperature setting value required by the feedforward method can be adjusted appropriately according to the actual situation, and gradually find the ideal control temperature curve based on the actual situation and continuous accumulation.

2.2. Internal forced convection

By adopting multiple built-in high-temperature hot air circulation systems arranged perpendicular to the furnace body, the high-temperature air in the furnace is forced to circulate over a large range. The variable speed regulation control of the variable frequency motor is adopted, and an airflow distribution device is added horizontally to ensure that the airflow can be evenly distributed on both sides when one side enters.

The above question about heat generation and control in glass tempering furnaces has been answered for everyone. We hope it will be helpful to you! By applying the above-mentioned airflow quantitative directional control technology, the heating path and time of the heat flow on the glass can be controlled, ensuring uniform heating and heat transfer efficiency of the glass. Our company produces various models of glass tempering furnaces, suitable for the production of tempered glass of various specifications. If you have any needs, please contact us.