“Flat tempered glass”

Tempered glass

Tempered Glass is a safety glass. In order to increase the strength of the glass, chemical or physical methods are usually used to form compressive stress on the surface of the glass. When the glass is subjected to external force, the surface stress is first offset, thereby improving the bearing capacity and enhancing the glass self-resistance. Wind pressure, cold and heat, impact and so on.

The physical tempered glass is heated in a "tempering furnace" at about 680 ~ 750 °C to rapidly reduce the temperature, destroying the original molecules of the glass so that the compressive stress is distributed on the glass surface, and the tensile stress is in the center layer. Due to the strong equal compressive stress, the tensile stress generated by the external pressure is offset by the strong compressive stress of the glass, increasing the safety of the glass. When the external force exceeds the tension inside it, the tension will be out of balance and smashed, becoming countless fine particles.

　　Granulated glass broken particles

Flat steel furnace structure

Advantages of tempered glass

1. High strength: tempered glass of the same thickness, its strength and deflection bearing capacity is about 4 to 5 times that of ordinary glass.

2, thermal stability: tempered glass resistance to rapid cooling and hot energy is 3 to 5 times higher than ordinary glass, generally can withstand temperature changes of more than 250 degrees, has a significant effect on preventing thermal cracking (such as 5mm tempered glass, The temperature difference of about 200 degrees Celsius is changed).

3. Safety: When the glass is damaged by external force, it will break into small obtuse-angle particles, which will not cause significant harm to the human body;

Tempered glass deflection and impact test

Characteristics of tempered glass

Type tempered glass semi-tempered glass flat glass

Strength 4x2xx

Fragmented innumerable obtuse angles Small debris fragments will have at least one edge extending to the edge of irregular random fragments

Safety in accordance with EN12600, Z97.1 performance requirements does not belong to safety glass is not a safety glass

Glass type / standard GB15763.2, GB17841ASTM C1048AS 2208JIS3206

Full steel σ>=90MPaσ>=69MPaσ>=69MPa is not specified

Semi-tempered 24 Mpa <σ<=69MPa24 - 52MPa (thickness less than 6mm, greater than 6mm negotiation) 24MPa-45MPa20MPa-60MPa

Use of tempered glass

Tempered glass is a safety glass and is widely used in the following industries:

1. Construction, building formwork, and decoration industry (eg, doors and windows, curtain walls, interior decoration, etc.)

2, furniture manufacturing industry (glass coffee table, furniture package, etc.)

3, home appliance manufacturing industry (TV, oven, air conditioner, refrigerator and other products)

4, electronics, instrument industry (mobile phones, MP3, MP4, watches and other digital products)

5, the automobile manufacturing industry (car windshield, etc.)

6, daily products industry (glass cutting board, etc.)

7, special industry (military glass)

Opening principle of tempered glass

Tempered glass is a kind of pre-stressed glass. When drilling, it must pay attention to the relative position of the hole and the size of the glass, so as not to excessively damage the characteristics of the glass itself, which may affect the safety or the control of the edge caused by the drilling. Extend the damage. For glass drilling requirements, please refer to the optimum processing conditions indicated in the figure below:

For the glass that has been drilled, if it needs to be tempered, the following items should be noted:

1. The short side of the glass must be more than 8 times the thickness of the glass, and the maximum aperture must be less than 1/3 of the short side of the glass.

2. The diameter of the hole should be the thickness of the glass plus 1.6mm or more.

Test method for tempered glass

How can I know if it is tempered glass? From the principle of tempered glass manufacturing, tempered glass is obtained by first cutting the ordinary annealed glass into the required size, then heating it to a near softening point, and then performing rapid and uniform cooling. After tempering, the surface of the glass forms a uniform compressive stress, while the inside forms a tensile stress, which greatly improves the performance of the glass. The tensile strength is more than three times that of the latter, and the impact resistance is more than five times that of the latter. The stress characteristic is an important sign to distinguish true and false tempered glass. That is, tempered glass can see colored stripes on the edge of the glass through the polarizing plate, and black and white spots can be seen in the surface layer of the glass. Some specialized laboratories have a "stress meter" for detecting the stress of tempered glass. The quality of the tempered glass can be judged intuitively by detecting the stress of the tempered glass. Generally, the tempered glass is usually labeled with a 3C certification.

Silk screen 3C logo tempered glass finished product

The shortcomings of tempered glass are insufficient

1. The tempered glass can no longer be cut and processed. The glass can only be processed to the required shape before tempering, and then tempered.

2. Although the strength of tempered glass is stronger than ordinary glass, tempered glass has the possibility of self-explosion when the temperature difference changes greatly (the automatic explosion of tempered glass without direct mechanical external force is called the self-explosion of tempered glass), while ordinary glass does not. According to industry experience, the self-explosion rate of ordinary tempered glass is about 3~5‰. Self-explosion is an inherent characteristic of tempered glass. The method of reducing self-explosion is to homogenize tempered glass (also known as hot dip HST). .

3. The surface of the tempered glass will have unevenness and a slight thickness. The reason for the thinning is that after the glass is melted by hot melt, it is rapidly cooled by a strong wind force, so that the internal crystal gap of the glass becomes small and the pressure becomes large, so the glass is thinner after tempering than before tempering. Under normal circumstances, 4-6MM glass is thinned 0.2-0.8MM after tempering, and 8-20MM glass is thinned by 0.9-1.8MM after tempering. The degree of specificity depends on the equipment, which is why tempered glass cannot be mirrored.

4. The middle part of the tempered glass is the strongest, and the four corners and the edge are the weakest. It is easy to smash the whole piece of glass once the edge or corner is hit.