Hollow glass is composed of two (or more than two) glasses, separated by a spacer frame with a desiccant, and sealed at the periphery. As insulating glass has good thermal insulation properties, it has been widely used in new construction in China in recent years.
Insulating glass is subject to external environmental corrosion and external forces throughout the life cycle of use. Some quality problems occur in some insulating glass after a certain period of use. There are two main types: First, the sealing performance of insulating glass fails (gas leakage ), The dew point of the hollow glass is generated, and the thermal insulation function is lost; Second, the hollow glass bursts and the whole sheet falls off, which may easily cause serious safety hazards. In particular, the failure of the sealing performance of the insulating glass will lead to a decrease in its carrying capacity. Under the action of the external force, the outer sheet is more likely to fall off as a whole. Therefore, to study the basic theory of hollow glass load carrying capacity, to understand the strength characteristics and deformation characteristics of hollow glass under external load, to reasonably design the size of hollow glass structure, and to propose a set of failure detection methods for the hollow glass hollow layer sealing performance. The application of glass engineering to reduce the failure probability of hollow glass and ensure the safe and reliable use of hollow glass is of great significance. For this reason, according to the characteristics of hollow glass structure, this paper analyzes various factors affecting the load-bearing performance of hollow glass, and puts forward the application of concentrated load in the center of hollow glass panel, through observation of the amount of deformation of hollow glass inner and outer sheets or hollow layers. The change in thickness was used to evaluate the sealing performance of hollow glass hollow glass, and a set of matching test equipment was designed.
Hollow glass bearing performance analysis
The main factors affecting the bearing performance of hollow glass are the strength of hollow glass, the stiffness of hollow glass and the sealing performance of hollow glass hollow glass.
1. Strength and rigidity of insulating glass
Hollow glass strength refers to the ability of hollow glass to resist external load, and stiffness refers to the ability of hollow glass to carry deformation. Obviously, after the glass material is given, such as ordinary flat glass or tempered glass, according to the glass strength design theory, the breaking strength of the original glass sheet is determined. Therefore, in order to increase the load-bearing capacity of the hollow glass, it is necessary to make the bending stress of the glass surface smaller under the same load, which is related to the size of the original hollow glass sheet (length, width, aspect ratio and thickness of each original sheet) and The thickness of the hollow layer is relevant. The load that is directly distributed to each piece of glass under external load determines the load-bearing capacity of the hollow glass.
Since the hollow glass is composed of two (or more than two) glasses, the surrounding seal forms a sealed air layer. When the hollow glass is subjected to a load on one side of the glass, the stressed surface glass deforms to compress the hollow layer gas, and the gas pressure increases. Part of the load is transmitted to the other side of the glass, so in the gas-sealed state, the two glass sheets are collectively subjected to the load and the two glass sheets are deformed at the same time.
2.Hollow glass bearing properties in hollow layer failure
In the case of a gas seal in the hollow layer, the gas transfer function can transfer part of the external load to another piece of glass, but when the gas layer leaks, the hollow layer gas completely loses the effect of transmitting the load. In this case, the hollow glass receives the load. It is completely covered by the piece of glass that is directly under pressure.
Obviously, the load capacity of hollow glass at this time will be significantly reduced.
Fig. 1 is the value of the deflection of the inner glass (non-bearing side) along the centerline of the hollow glass under the conditions of sealing and leakage under the uniform load of 6kPa under the test of hollow glass (6mm+12mm+6mm, size 1000mmx1000mm). This figure shows that the deflection of the inner sheet glass is significantly greater than the deflection in the leak state under the condition that the hollow layer gas is sealed. After the leak, the hollow gas layer loses its carrying capacity, the inner sheet is not subjected to force, and there is almost no deformation.
3. The effect of environmental temperature and pressure difference on the load-bearing performance of hollow glass
Even if it is not affected by the external load, due to the difference between the production environment of the insulating glass and the use of the regional environment, the hollow glass of the hollow glass may expand or contract (see Fig. 2), which directly results in deformation and attachment of the two glass sheets. Stress, when severe, can cause two pieces of glass to bump into each other and even cause the glass to break.
Hollow layer failure online detection method and device
From the analysis, it can be known that the hollow glass changes its load-bearing performance after the sealing performance of the hollow layer fails. For this purpose, a hollow layer is identified by applying a method of concentrating on the center of the glass plate and observing the deformation of the inner and outer sheets of the hollow glass or the change of the thickness of the hollow layer. Is it sealed?
In order to achieve on-line detection of the hollow glass hollow-layer sealing performance, the detection device mainly includes a force applying device and an insulating glass deformation observation device.
(a) is a schematic diagram of the construction of a concentrated force device for the insulating glass of a curtain wall or door and window on the spot, in which the force applying device adopts a spiral force method. The detection device is provided with a guide bar for mounting across the frame of the curtain wall with sufficient rigidity. Each end of the guide bar is provided with a hook. The hook can be freely moved on the guide bar. The suckers are arranged on the hooks, the middle section of the guide rod is provided with a spiral force booster, the threaded rod on the spiral booster is perpendicular to the guide rod, a flexible gasket is arranged at the front end of the threaded rod, and the tail end is connected with a force spiral handle, and the force is applied through rotation. The handle pushes the threaded rod forward; the middle of the threaded rod places a force sensor to obtain the magnitude of the applied force.
(b) is a schematic diagram of another kind of on-site application of a concentrated force device to the hollow glass of a curtain wall, in which the force-increasing device adopts a weight-increasing method. The detection device is provided with a connecting rod, and the connecting rod is composed of two parts, namely a pulling rod and a pressing rod. One end of the pulling rod and the pressing rod is connected with a hinge so that the two rods can rotate with each other and obtain different angles. The other end of the pull rod is provided with a hook and a vacuum sucker connected to suck on the glass. A hook is arranged at the hinge of the connecting rod, the hook is connected with one end of the hanging rope, and a hook is arranged on the other end of the hanging rope. The hook can be placed on the hook. Weights. The angle of the tension bar is adjusted so that the pressure bar is perpendicular to the plane of the detection glass. Different concentration forces applied to the glass can be obtained by increasing or decreasing the weight.
By applying a concentrated force to the hollow glass in use and recording the deflection (maximum deflection) or the thickness of the hollow layer in the center of the hollow glass, the deformation of the hollow glass can be observed by a displacement sensor, and the thickness of the hollow layer can be used to measure the thickness of the air layer. measuring.