What is double two heating oven chamber glass tempering furnace and why should i choose it?

What is double two heating oven chamber glass tempering furnace?

Double heating chamber glass tempering furnace, also known as two-chambers tempering furnace, combined tempering furnace, and double chamber glass tempering equipment, etc. For this glass tempering furnace, it has two separate heating chambers.

This tempering machine consists of:

Loading table

Preheating chamber (heating temperature setting is about 450-500℃ for this chamber)

Heating chamber  (heating temperature setting is about 690-700℃ for this chamber)

Quenching section

Cooling section

Unloading table

Control system

Blower system

This glass tempering furnace machine is mainly used to temper Low-e glass, especially for off-line Low-e glass, coated glass, and the high grade normal glass.

What is the advantages of double two heating oven chamber glass tempering furnace?

This glass tempering furnace with two heating oven chambers can minimize heating time. The main problem that happens during glass being heated for a long time in the furnace is:

The possibility of scratch damage on the lower surface of the glass increases, and the waviness possibility also increase.

At the same time, the surface quality and optical properties are affected, so the quality of tempered glass will decrease to varying degrees.

And this two-heating chamber glass tempering furnace can effectively solve this problem, greatly reducing the probability of defects in the glass during the heating process. While maximizing production, the quality of tempered glass can be greatly improved.

Working principle of the glass tempering furnace with two heating oven chamber?

The tempered glass produced by normal glass tempering furnaces has serious optical deformation (wave ribs), spherical bending of thin plate glass, pitting of thick plate glass, white mist, and explosion defects. especially for tempered laminated glass and coated glass. However, these problems can be solved by two heating chamber glass tempering machine.

With this glass tempering furnace, the glass undergoes two different heating stages:

first, preheating is carried out at low temperatures in the preheating furnace. In the low-temperature environment of the preheating furnace, the temperature is uniform and easy to control, which can make the glass uniformly heated, avoid too fast heating of the glass corners, reduce the temperature difference of the glass corners, and thus solve the optical deformation of thin plate glass and the phenomenon of glass easily forming spherical surfaces; At the same time, due to the low temperature of the preheating furnace, it also effectively avoids the phenomena of pitting, white mist, and furnace explosion that are prone to occur in thick plate glass. Combination glass tempering furnaces can be divided into household appliance glass tempering furnaces, building and furniture glass tempering furnaces, solar energy glass tempering furnaces, etc. according to their product uses.

Second, After the glass is preheated in the preheating furnace, it enters the heating furnace; The heating furnace is usually set at around 700 ℃. Similarly, due to the small temperature difference, the temperature inside the furnace is relatively stable. Relatively speaking, when the glass enters a constant temperature environment, the heat absorption rate of the glass weakens relatively in this stage, stabilizing the glass shape and reducing the possibility of deformation.

Therefore, based on the heating point of the glass, the combination heating furnace enhances the heating rate of the glass at low temperatures, which is more in line with the physical properties of the glass. Completing the heating process in this favorable environment has greatly improved the yield and quality of glass.

Does the two heating chamber glass tempering furnace need force convection system for both heating ovens?

Yes, if the investment is ok, we suggest you to make both two heating chamber with force convection system. This is very good to produce the triple silver Low-E glass. Now, in the market, there are more than 60% two-heating chamber furnace has 2 force convection system. If you don’t have triple silver coated glass, you also could choose one heating chamber has force convection system, this could temper double silver coated glass.

Because:

The radiation heat transfer efficiency of glass is relatively low in the low temperature range, and LOW-E glass has strong reflection of radiation heat, which means that using radiation heating in the low temperature range will have lower efficiency. However, using forced convection system for heat transfer to solve this problem can greatly improve heat transfer efficiency and effectively shorten heating time; Due to the high furnace temperature, the radiation heat transfer effect is obvious in the high-temperature section. However, the reflection of radiation heat by LOW-E glass cannot be ignored. At the same time, in order to further improve the uniformity and effectiveness of high-temperature heating for ordinary glass, the heating system in the high-temperature section still adopts the force convection heating method, which strengthens the equipment configuration and significantly improves product quality.

What is the performance of two heating chamber glass tempering furnace?

1. This furnace can shorten the heating cycle, increase productivity and significantly save energy.

2. The preheating chamber can adopt a lower working temperature to reduce adverse reactions of glass after entering the furnace and improve the surface quality of glass.

3. Specially suitable for pattered and embossing glass, coating glass, with less damage and better tempering quality.

Precautions for operating the two heating chamber glass tempering furnace:

When operating this furnace, due to the two-stage furnace structure, it is necessary to accurately set the temperature of the preheating and heating sections when producing glass.

The preheating section is equipped with forced convection system at top oven. In order to produce high-quality glass, the temperature should be set relatively low.

The heating section is to quickly reach the soft melting point of the glass. At this time, the temperature must be set high so that the glass can quickly reach the required temperature on the glass surface. Glass does not undergo shape damage, dimensional deviation, changes in optical properties, or variations in leaving marks during the tempering process.

In order to meet the above basic requirements, the following are some basic principles that hope to assist operators in establishing basic concepts for the production of tempered glass in the early stage.

1. Heating principle

According to the standard glass heating capacity, the heating time for every 1mm thick glass is 30-45 seconds, which is 150-220 seconds for 5mm glass, 240-360 seconds for 8mm glass, and 350-450 seconds for 10mm glass.

Glass thickness standard heating time

1 mm 30-45 s

5 mm 150-220 s

8 mm 240-360 s

10 mm 350-450 s

But this is not fixed, different types of tempering furnaces will have different heating time requirements due to different designs;

In addition, the temperature setting can also change the length of heating time. Generally, a higher temperature setting can allow the same glass to reach the desired temperature in a shorter time, thereby increasing production. However, a relatively lower temperature setting requires a longer time for the same glass to reach the desired temperature, thereby reducing production.

2. The effect of heating time on glass

Usually, a longer heating time can result in a more uniform temperature distribution for glass, especially for large glass; The uneven temperature distribution of glass will prevent the formation of uniform strengthening stress after tempering, which can usually be verified by crushing tests. In addition, uneven strengthening stress distribution can also easily lead to self explosion of glass. In severe cases, glass will shatter in the strengthening zone during tempering.

Although it seems that increasing the temperature setting can achieve higher economic benefits on the surface, there are still some principles that need to be followed so as not to affect the quality of tempered glass and the success rate of glass tempering. So during production, it is important to pay attention to setting the heating time and temperature according to the specifications and thickness of the glass.