CN203247188U - Toughening furnace cooling system - Google Patents

Abstract

The utility model relates to a toughening furnace cooling system which comprises a fan, an air collection box, an air feeding channel and a liquid nitrogen container, wherein the fan feeds air into a toughening furnace; the liquid nitrogen container for accommodating liquid nitrogen is mounted on the air collection box or the air feeding channel; a valve port of the liquid nitrogen container is connected with the air collection box; and an electromagnetic valve which is in starting connection with the fan is mounted at the valve port. According to the toughening furnace cooling system, at a glass quenching stage, when the fan feeds air into the toughening furnace, the liquid nitrogen is injected into the air collection box connected with the fan in a short time, so that the air temperature of a conventional cooling medium in glass air-toughening can be substantially reduced, the installed capacity of the fan is reduced, and the toughening furnace cooling system can be used for producing float glass with the thickness of not lager than 3 mm or over-toughened glass.

Description

A tempering furnace cooling system

Technical field:

The utility model belongs to the field of tempered glass, in particular to a tempered glass cooling system. the

Background technique:

Tempered glass products have been widely used in many fields such as construction, aviation, automobiles, ships, locomotives, and electronic display devices. Since the first patent of tempered glass was obtained in France in 1870, several patents were obtained in the 19th century, and it was applied industrially in 1892. Later, a series of products such as flat tempered glass and curved tempered glass were developed. In the 1980s, with the increase of new types of glass, the tempered glass manufacturing industry carried out new product development and research. Radiation glass tempering, large-scale automotive glass and heterosexual glass tempering have made great progress. the

Physically tempered glass is to form a compressive stress layer on the surface of the glass, so that it adds a prestress to improve the strength of the glass. At present, the method of rapid air cooling tempering (referred to as wind tempering) is widely used. the

Wind tempering is to heat the glass to 80°C above the glass transition temperature (T _g ), and use air as the cooling medium to quickly take away the heat from the surface of the glass. The outer glass cools faster, and the center of the glass is conducted by the outer glass through heat conduction. Cooling, so the center of the glass cools slower than the outer layer of the glass, so through this process, internal stress is generated between the outer layer and the center of the glass, and the compressive strength of the glass is more than ten times its tensile strength. Through the internal stress The introduction of glass increases the tensile strength of the glass and improves the strength of the glass. Under normal circumstances, the strength of tempered glass is 4-6 times higher than that of ordinary annealed glass, and the thermal quenching stability can be increased from about 150°C to 280-320°C.

The strength of tempered glass mainly depends on the size of the internal stress, which is related to the tempering temperature and cooling rate of the glass. Generally, the tempering temperature is 600-680°C, and the cooling medium is air at room temperature. The air flows on the surface of the hot glass with heat and freezes the glass surface. Therefore, the cooling capacity affects the tempering degree of the tempered glass to a certain extent, and then affects The strength of tempered glass and the particle size of fragments after breaking. As the tempering degree increases, the bending strength and impact strength of the glass increase. However, in view of the fact that the cooling medium used in wind tempering is air, and the temperature and heat capacity of the air itself lead to its limited cooling capacity, even if the wind pressure is increased, it cannot be applied to tempered thin glass (such as glass with a thickness less than or equal to 3mm) and special requirements. Tempered glass. At the same time, increasing the wind pressure means increasing the capacity of the fan, increasing the power consumption rapidly, and greatly increasing the cost. the

Utility model content:

The purpose of the utility model is to provide a set of new tempering furnace cooling system. the

The tempering furnace cooling system of the utility model is used for cooling tempered glass, and includes a fan for feeding air into the tempering furnace, an air collecting box and an air supply channel, and a liquid nitrogen container is installed on the air collecting box or the air supply channel. The nitrogen tank and the liquid nitrogen tank have a valve port connected to the air collecting box, and the valve port is equipped with a solenoid valve connected with the fan startup. the

The utility model is equipped with a low-temperature liquid nitrogen input system in the air cooling system of the tempering furnace through the design of the air cooling system of the physical tempering equipment. Mixed with air, the temperature of the cooling medium is reduced. Experiments show that, in the case of obtaining the same tempering degree, the temperature of the cooling medium is lowered by 30°C, and the air pressure can be reduced by 15%. The introduction of low-temperature liquid nitrogen in the air supply system can not only reduce the installed capacity of the fan and the operating cost, but also reduce the temperature of the cooling gas and effectively increase the degree of glass tempering, which can not only significantly increase the strength of tempered glass, but also temper ordinary wind. Tempering non-tempered flat glass below 3mm and over-tempered glass for special needs. the

Description of drawings:

Fig. 1 is a structural diagram of the cooling system of the tempering furnace of the present invention. the

Detailed ways:

The utility model mainly provides a novel cooling system for a tempered glass tempering furnace. the

In a conventional tempering system, the fan 3 sends air as a cooling medium directly into the glass quenching part of the tempering furnace 2 through the air collecting box 1 and the air supply channel 4, as shown in FIG. 1 . The improvement of the present utility model is: continue to refer to shown in Fig. 1, on the wind path, a tank capable of containing liquid nitrogen is installed on the upper position of the wind collecting box 1, that is, the liquid nitrogen tank 5, and the liquid nitrogen tank 5 and the wind collecting box 1 pass through A valve port 7 is connected, the opening and closing of the valve port 7 is controlled by the solenoid valve 6, and the solenoid valve 6 and the fan 3 are started to be connected. the

In the operation, firstly, inject liquid nitrogen into the liquid nitrogen tank 5, close the liquid nitrogen tank, and when the tempering furnace 2 starts to quench the glass, the fan 3 starts to work, and the solenoid valve 6 opens the liquid nitrogen tank valve port 7 to close Liquid nitrogen is added to the air collecting box and mixed with the air sent by the fan (usually room temperature air). During the mixing, the liquid nitrogen is vaporized, and the volume expands about 1000 times in an instant. The liquid nitrogen gasifies into low-temperature nitrogen and the air provided by the fan to form a cooling medium. , into the tempering furnace 2 through the air supply channel 4 to quench the high-temperature glass (quenching process). Specifically, the electromagnetic valve can be opened 5 seconds after the start of the quenching stage, and liquid nitrogen can be added to the air intake system. After 10 seconds, all liquid nitrogen can be added to complete the quenching process. In this quenching process, the cooling capacity of the system is improved from the following aspects: 1. Mixing liquid nitrogen with air, liquid nitrogen gasifies, absorbs the latent heat of vaporization, and reduces the temperature of the cooling medium; 2. Mixing low-temperature nitrogen with air reduces the temperature of the cooling medium 3. The volume of the gas expands to work and absorb heat, reducing the temperature of the cooling medium; 4. Increasing the air inlet pressure and increasing the cooling air volume. After the quenching stage is over, close the electromagnetic valve, stop sending liquid nitrogen to the air collecting box, and at this time, the fan alone provides air for slow cooling. the

The inventor has proved through a large number of experiments that in the quenching stage, the relationship between the amount of liquid nitrogen added and the air supply during the quenching process is 100m ³ air: 10-40 liters of liquid nitrogen, correspondingly, the temperature of the cooling medium can be reduced by 30 ℃ or more (31-85 ℃), and the tempering strength can be increased by more than 30MPa (32-109MPa). When the same tempering strength is achieved, the air supply volume of the fan can be reduced by 10-30%.

Use and effect of the present utility model are illustrated below with examples. the

Example 1: Production of ordinary toughened glass

Sample: 6mm glass, the corresponding labels of the same glass are divided into 2 groups, a total of 12 pieces of glass are divided into 2 groups for testing, and the strength of ordinary air-cooled tempered glass and the strength of the utility model liquid nitrogen cooled tempered glass are tested, and the results are compared ;

Tempering conditions and operation:

In a small tempering furnace, the installed capacity of the fan is 30KW, and the temperature at the air inlet of the tempering furnace is 35°C in summer. A liquid nitrogen tank with a volume of 20 liters is installed at the upper part of the air collecting box at the back of the tempering furnace fan, and it is filled with liquid nitrogen before the air cooling is started and sealed. 5 seconds after the start of the glass quenching stage, open the solenoid valve to open the valve port of the liquid nitrogen tank, and all the liquid nitrogen will be injected into the air collection box within 10 seconds to make it match the air flowing in the air box (the air supply speed of the fan when liquid nitrogen is not injected) 10m ³ /S) mixed and gasified, as the airflow enters the air duct and is sprayed out from the nozzle into the tempering furnace, due to the volume expansion of liquid nitrogen gasification, the instantaneous mixing and cooling wind speed increases to 12m ³ /S, and the temperature of the air inlet is changed from The original 35°C drops to minus 20°C, and the quenching process of the quenching stage is completed at this time; after all the liquid nitrogen is injected, the air supply (air, air supply speed of 10m ³ /S) is continued for 40 seconds (the liquid nitrogen Liquid nitrogen in the tank is emptied), close the solenoid valve, continue to supply air for 10 seconds, turn off the quenching fan, and complete the entire quenching stage. After the quenching stage is over, at this time, the fan provides air for slow cooling for 3 minutes at the original low-power air supply speed (10m ³ /S), and the glass sample is taken out of the tempering furnace for testing.

Detection: The strength of the tempered glass under different quenching conditions was tested using a polarizer strain gauge, and the data are shown in Table 1. the

Table 1: Strength of 6mm tempered glass

sample Ordinary air-cooled tempered glass strength sample (air cooling + liquid nitrogen cooling) tempered glass strength 1 121MPa 1# 168 MPa 2 117MPa 2# 183 MPa 3 125MPa 3# 188MPa 4 130MPa 4# 190MPa 5 129MPa 5# 192 MPa 6 135MPa 6# 192 MPa

It can be seen from the data in Table 1 that the strength of tempered glass is significantly improved after adding liquid nitrogen to the cooling tempering system. the

Embodiment 2: Production of thin tempered glass

For thinner glass, such as 3mm glass, it is difficult to form an effective stress layer inside the glass due to the thinner glass. Therefore, the effect of ordinary wind tempering methods on 3mm glass is not obvious, and wind tempering is generally not used. the

In this embodiment, the corresponding 3mm glass sample is tempered by using the cooling system of the utility model and the cooling system of a common tempering furnace. the

Tempering conditions and operations are the same as those in Example 1, wherein, the air supply speed of the fan is 10m ³ /S, the liquid nitrogen injection volume is 20 liters, and the injection is completed in 10 seconds; the temperature of the mixed cooling medium at the air inlet of the tempering furnace is minus 20°C, and the mixed cooling wind speed is 12m ³ /S Second.

Detection: Same as in Example 1, the data obtained by the polarizer strain gauge are shown in Table 2. the

Table 2: Strength of 3mm tempered glass

sample Ordinary air-cooled tempered glass strength (air cooling + liquid nitrogen cooling) tempered glass strength 1 78MPa 98Mpa 2 75MPa 111MPa 3 86MPa 125MPa 4 64MPa 99MPa 5 68MPa 118MPa 6 71MPa 117MPa

Note: The strength of 3mm glass before tempering is 60MPa. the

It can be seen from Table 2 that after cooling and tempering with liquid nitrogen, 3mm flat glass can be tempered, and the glass strength meets the requirements of ordinary tempering; while the glass strength does not increase significantly after ordinary air cooling, and glass tempering cannot be achieved. the

Embodiment 3: Production of tempered glass

In this application, over-tempered glass refers to tempered glass with an additional strength exceeding 105MPa obtained through physical tempering on the basis of the strength of the original glass sheet for 12mm glass. The common air tempering method cannot produce tempered glass due to insufficient cooling capacity of the equipment. the

In this embodiment, a group of samples of 12mm glass are tempered by the method of the utility model to produce tempered glass. the

Tempering conditions and operations are the same as those in Example 1, wherein, the air supply speed of the fan is 100m ³ /S, the injection volume of liquid nitrogen is 20 liters, and the injection is completed in 10 seconds; the temperature of the mixed cooling medium at the air inlet of the tempering furnace is minus -20°C, and the mixed cooling air speed is 12m ³ /Second.

Detection: Use a polarizer stress meter to detect the surface stress of the tempered glass, and the surface stress value is the tempered strength of the glass;

Put the tempered glass at the bottom of the stainless steel tank, hit the glass with an alloy sharp-nosed hammer, and the tempered glass will be broken into fine particles, and the glass fragments will be sieved through sieves of different meshes to test the glass fragmentation index. the

The test results are listed in Table 3:

Table 312mm tempered glass index test results

The results show that for 12mm thick glass, through the liquid nitrogen assisted quenching process of the utility model, the average stress on the glass surface can reach 270MPa, which is 120MPa higher than the strength of ordinary air-cooled tempered glass; glass fragmentation particle size: 90% of glass fragmentation particle size is less than 4mm, while only 10% of ordinary air-cooled tempered glass can reach <9mm broken particles. The shape of the tempered glass produced by the utility model can visually display the glass fragmentation performance, and the glass is broken into relatively fine particles (for the convenience of observation, the tempered glass is wrapped with transparent tape before fragmentation). The comprehensive test results show that the utility model system can produce tempered glass. the

The tempered glass cooling system provided by the utility model, through the special design of the physical tempering furnace cooling system, compared with the current general wind tempering furnace, can greatly reduce the temperature of the traditional cooling medium in glass wind tempering—air, and Reduce the installed capacity of the fan, so that it can be used to temper float glass with a thickness less than 3mm or produce tempered glass. the

Claims (1)

1. annealing furnace cooling system, be used for toughened glass is cooled off, comprise blower fan from air to annealing furnace, air collecting box and the air-supply passage of sending into, it is characterized in that, at this air collecting box or air-supply passage a liquid nitrogen container that holds liquid nitrogen is installed, liquid nitrogen container has valve port to be connected with air collecting box, and this valve port is equipped with the magnetic valve online with fan starting.

Images