Allows you to load tall products (up to 300 mm). Acts as a large ventilation window, which can dramatically speed up the cooling process. This is especially important when bending small products. Bending time for float glass in specialized furnaces is about an hour.
The figure shows the temperature graph of the bending process. The blue color indicates the set temperature profile. Red - a real schedule. The main problems are the cooling rate of the furnace. Without special measures, the oven cools very slowly.
In non-specialized furnaces, after going through the stress-relieving stage (stage number 3 in the figure), you can open the furnace lid by 2-3 cm. If you are sure of the quality of the glass (all stresses removed), you can open the lid more. After 250°C, you can open up to 5 cm. If the oven is equipped with a top cover, the cooling process will go faster and be safer. You should pay attention to stage three - with a more thorough passage of the stage; you can further cool the glass in the future.
Tags: fusing oven