Failure Analysis and Preventive Measures of Insulating Glass in Railway Train Window.
1. Structure of trough aluminum insulating glass
At present, there are two main types of insulating glass for railway train windows: one is the 5+9+5 structure, which is used in 25G, 25K, 25B, and remanufactured vehicles; the other is the 5+6+8 structure, which is used in 25T and the windows of export train vehicles. In addition, the shapes of insulating glass for railway train windows are different, including special shapes such as arcs, triangles, and parallelograms. The trough aluminum insulating glass developed by Jinan LIJIANG Glass draws on advanced foreign production experience, adopts leading butyl rubber and polysulfide double-channel sealing technology, and can automatically produce special-shaped insulating glass for railway train windows. It has the following characteristics :
1.1 Double sealing:
The first sealing adopts hot-melt butyl glue, which is mainly used for sealing, that is, preventing external water vapor from entering the air layer of the insulating glass; the second sealing adopts two-component polysulfide glue, which is mainly used for structure The function is to maintain the overall structure of the hollow glass under the external temperature changes, high humidity and ultraviolet radiation.
1.2 Using trough aluminum positioning:
It has the characteristics of reliable positioning, strong pressure bearing capacity, and convenient molecular sieve perfusion. One of the characteristics of railway passenger cars that distinguishes them from civil buildings is that the lathe glass of railway passenger cars needs to meet the applicable requirements for high-speed operation. The insulating glass should have wind pressure resistance and the ability to withstand temperature changes, but the warm edge (composite rubber strip) type Insulating glass is not suitable for railway passenger cars, which use trough aluminum hollow glass.
1.3 Molecular sieve perfusion in trough aluminum cavity:
Molecular sieve has moisture absorption performance, guarantees the requirement of hollow glass dew point, no frosting or condensation at low temperature, and has excellent performance.
Figure 1 The insulating glass processing in railway train window 1
2. The main reason for the failure of insulating glass
Combined with the structural characteristics of insulating glass, the reasons for the failure of insulating glass on railway passenger trains are generally as follows:
2.1 The hollow glass is breathable.
Water vapor directly enters the insulating glass spacer layer, causing mildew and anti-alkali on the inner surface of the glass (the entry "anti-alkali" is provided by Google), electrolytic pulverization of the aluminum in the cell, and molecular sieve failure, which directly affects the quality of the insulating glass, resulting in the hollow glass Invalidate.
2.2 The dew point rises.
The dew point of hollow glass refers to the temperature at which the humidity of the air sealed in the spacer reaches a saturated state. The relevant international industry standards stipulate that the dew point is -40ºC. When the temperature is lower than this temperature, the water vapor in the spacer layer will condense into liquid water. The higher the water vapor content, the higher the dew point temperature of the air. When the temperature of the inner surface of the glass is lower than the dew point of the air in the spacer layer, the water in the air will condense or frost on the inner surface of the glass. When the ambient temperature drops below the dew point and the surface temperature is higher than 0ºC, the water vapor in the spacer layer will condense on the inner surface of the glass; when the surface temperature is lower than 0ºC, the water vapor in the spacer layer will form frost on the inner surface of the glass.
3. The practical cases of railway trains
It is understood that the windows of the CRH380B high-cold EMU train dedicated to the Harbin-Dalian high-speed rail are made of double-layer hollow glass, and the glass is sealed with the window frame. All the gaps between the window frame and the car body are filled with high-performance colloidal seals. , The outside air cannot enter at all.
The train door is also a "plug door". This kind of door is not simply closed and opened but can be slid parallel to the side to open. When closed, it slides into the doorway like a plug, while the seams are still It uses high-strength rubber strip material to achieve a tight seam between the door and the compartment.
Figure 2 The CRH380B high-cold EMU train: Harbin-Dalian high-speed rail 1
This kind of train design allows passengers to sit on the Harbin-Dalian high-speed rail train and appreciate the beautiful scenery outside the window. Even if the train passes through caves and bridges, passengers cannot feel the air pressure changes outside the train. Taking such measures will prevent the train’s relatives from being squeezed into the carriages. When the high-speed train passes through the high-cold areas or caves, passengers will not feel the air pressure changes outside the train. It is reported that the CEH380B EMU adopted by the Harbin-Dalian High-speed Railway was designed with factors such as airtightness inside the car and isolation from the outside air pressure taken into account. The design of the train window paid attention to the choice of train materials, in addition to windows, doors, windshields, etc.
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