[China Aluminum Network] aluminum alloy hidden frame glass curtain wall is a comprehensive new technology product, the curtain wall does not have to hold the glass and bearing aluminum alloy frame, it is completely relying on the structure of plastic to hundreds of pieces The heat-reflective coated glass is adhered to the aluminum profile frame, and the gap between the glass is glued with a sealing structure to form a large-area glass mirror surface, which is decorated on the facade of the building. Make buildings look unique, bright, crisp and upright, giving people a whole new concept in terms of color and gloss compared to other decorative materials. In particular, the use of heat-reflective coated glass, the natural landscapes such as streetscapes, blue sky, and white clouds around the buildings are reflected on the outer surface of the building and change with the season, time, and intensity of light, thereby making the building The outer layers of the object are staggered. The scene melts beautifully and forms a rich variety of sights that are rich in sight, bright and radiant, and radiant. In addition, the transmittance of the heat-reflective coating glass used in the hidden glass curtain wall is less than 20, so it has a strong anti-peeping function, that is, it can not see the scenery inside the building in the outdoors, and plays the role of a tent, but the indoor can still The outdoor view is unobstructed and it is precisely because of this charm that our country has formed a hidden wall. However, it must be known that the technical requirements for the design, manufacture, installation, and construction of such curtain walls are particularly stringent, and the degree of difficulty, technical complexity, and risk are also particularly high. Because some manufacturers do not completely follow the standards and procedures, there have been many collapses of the curtain wall project in China, and the losses are disastrous. It is shocking to others and can not but arouse our great attention. In order to prevent personal injury and property damage, users and relevant departments are required to pay attention to tracking the hidden dangers of concealed frame glass curtain walls. First, the hidden dangers of hidden glass curtain wall on timber 1 Add aluminum wire and aluminum waste pot, etc. instead of aluminum metal and aluminum elements during smelting The front factor of ensuring the quality of the curtain wall is the profile. Since the coated glass of the hidden glass curtain wall is not bounded by the frame, it is completely adhered to the aluminum material by the structural adhesive. Therefore, the requirements for the aluminum material, the glass and the structural adhesive are extremely strict. The aluminum used in curtain walls should meet the requirements of GB/T5237.2-2000. The original state is composed of aluminum, magnesium, silicon and other elements. First of all, the ingredients can be guaranteed to have a qualified strength. However, in order to reduce the cost, some aluminum plants add aluminium scrap wires and aluminum waste pans instead of aluminum metal and aluminum elements during smelting. Any curtain wall made of this aluminum material is very dangerous. Because it does not meet the strength requirements, it cannot guarantee the function and service life of the curtain wall. This is one of the hidden dangers. 2 Aluminum alloy profiles not prepared according to the content of elements Aluminum alloy elements can be seen from the above table, its alloying, each element has a certain range of content, the price of magnesium is high, and some manufacturers reduce the use of magnesium to less allowable content in order to reduce costs. In some cases, the content of magnesium is lower than the allowable amount. This is not based on the content of aluminum alloy components prepared, basically not to 6063 alloy, later made the profile mechanical strength is very low, it is easy to bend, which is why some aluminum prices are cheap. Aluminium is cheap, and the entire cost is reduced. However, how to process it later, the quality will not go up. This is just like the Association of Aluminum Products of the Association of China's Costumes, former Chairman Peng Zhengguo and the Secretary-General said, “The glass curtain wall with hidden danger is in the air. "The time bomb", of course, the amount of other elements not in accordance with the content formula in the above table will also have the same consequences. 3 aluminum alloy melting furnace is also affecting the quality of its alloy How to melt the 6063 alloy and how to use the furnace is very important. Nowadays, the furnaces used by domestic and foreign manufacturers are very different. They have the level of the 1970s. There are also coal burning and oil burning in the 1990s. There are also gas-fired and electric heating furnaces, some have a chimney, some have a non-smoking tube, a square-shaped furnace (rectangular furnace) is generally used, a round furnace is also advanced, and a round furnace can be inclined to aluminum. water. On tonnage of several tons to several tens of tons of aluminum melting furnace, more advanced, below the aluminum melting furnace, plus a static furnace, 6063 alloy used for preparation, in this furnace degassing degassing, standing, and then Cast aluminum rods for extrusion. The quality of the alloy formulated in this furnace and the original coal-fired furnace is absolutely different. In general, no matter what fuel is burned in the furnace, there are chimneys. Most of the waste gas generated during the combustion of fuel can be discharged from the chimney; if there is no chimney, the exhaust gas residue will be completely melted in the aluminum water, so that the cast aluminum rod has serious internal defects. The slag inclusion bubbles, extruded profiles must have serious quality problems, which will seriously degrade its physical properties. One is that the strength is not enough, and the second is the tolerance of the surface dimensions, and the surface finish is poor, and it must not be used on hidden frame walls. 4 profile extrusion quality There are many kinds of profile extrusion presses in China, and there is a large difference in grades. The useful and simple extrusion presses can be transformed with a plastic extruder. There are a small number of domestically produced ones, followed by most of Taiwan, Japan, the United States, and West Germany. There are a wide variety of hydraulic and hydraulic pressures, and the good and bad extruders are in the same cast rod, and the quality of extruded profiles is never the same. In the quenching of aluminum, there are also water-cooled quenching and air-cooled quenching. The 6063 profile for building is quenched by air-cooling. The quenched aluminum material is aged for a certain period of time in the aging furnace. The internal crystals of aluminum are rearranged and the mechanical strength is significantly improved. Of all metal alloys, only the aluminum alloy is only in a time-limited state. However, although all manufacturers have passed the aging, the effects vary greatly. This is related to the extrusion temperature and speed of the aluminum extrusions, and the air-cooling speed of the profiles when they exit the extruder. With the amount of wind, if you can not quickly out of the extruded 500-degree profile quickly cooled to below 200 degrees, this is called quenching is not complete, aluminum strength after aging is not ideal. 5 Thickness of Aluminum Surface Oxide Film for Hidden Frame Curtain Wall According to the requirements of national standards, not less than 15μm, otherwise the firmness of bonding is significantly reduced. Now many manufacturers supply aluminum profiles for hidden frame curtain walls, the surface oxide film thickness does not meet this requirement, and some even do not reach the requirements. 12μm, this is very dangerous. Because the thickness of the oxide film increases, the cost will increase and the manufacturer will gain less profit. However, the user does not understand, and the high price is unwilling to accept it. Only by listening to it, it is more troublesome than later. 6 aluminum surface treatment In addition to the above-mentioned anodized film, there are electrophoretic paints, powder spray paints, and fluorocarbon spray paints. Electrophoretic paint has good surface gloss and strong anti-corrosion ability. However, it has poor film firmness and cannot be used on the adhesive surface of hidden glass curtain walls. It is hoped that users pay special attention. For the surface treatment of aluminum profiles used on hidden glass curtain walls, only anodized film profiles have been preferred. Second, the hidden dangers in the use of coated glass Glass is one of the main materials of aluminum alloy curtain wall, it directly restricts the performance of the curtain wall, and is also the main embodiment of the curtain wall art style. Therefore, the use of coated glass is an important part of the curtain wall design. If you choose improperly, there will be serious consequences. It is reflected in two aspects. 1 Original production method and thickness of coated glass At present, there are mainly two types of glass original films: the introduction method and the float method. The method of introduction is to slowly cool from the molten glass directly to form an ordinary glass plate with a low surface flatness. Float glass is currently a relatively advanced production process. It is based on the fact that molten glass floats on a tin bed. It forms a smooth surface by its own weight and surface tension. Its surface is smooth, smooth and of good quality, and it has no ripples or walks. Therefore, coating is used. When the glass is original, it must be float-produced first-class glass, and the quality of appearance is in line with the current national standard GB11614. The time of freshness of the coated glass original glass cannot exceed one week, otherwise the firmness of the film will affect the functional effect. At the same time, the thickness of the original film can not be selected at will, it must be calculated and checked according to the combination of the effects of wind load and effect, otherwise it will be easily broken and destroyed. For example, on the 60th floor of the John Cock Building in Boston, USA, there was severe damage caused by a gale during the summer of the 1970s, from partial crushing to 100 cracking, and 10,348 pieces of glass had to be replaced later. On January 17, 1995, a large number of curtain walls in the Kobe earthquake in Japan were damaged, and the accidental death of the glass caused by the broken glass was large. There are also similar accidents in China, such as Inner Mongolia Baotou City, Kun District, Wujinjiaodian hidden glass curtain wall finished less than two months, hundreds of broken glass. Therefore, the original production method and thickness of the coated glass must be carefully selected. 2 method of producing coated glass At present, there are many methods for producing coated glass, such as chemical method, physical deposition method, vacuum ion method, vacuum magnetron sputtering method, and online thermal spraying method. Some domestic manufacturers do not have complete formal equipment and stable process parameters, and there are also many indigenous methods to be launched. Therefore, the firmness of membranes varies. The coated glass used for the hidden frame curtain wall at home and abroad must be a coated glass produced by a vacuum magnetron sputtering method and an on-line thermal spray coating method. Vacuum magnetron cathode sputtering coating glass has the following characteristics: First, the sputtering rate is high, the size of the crucible type is large, the production volume is large, and the size is large; The second is that the film layer is uniform, the color difference is small, and the process control is stable; Thirdly, the combination of film layers is convenient, and the color variety and film type are mostly such as a solar reflective film, a low-radiation film, a conductive film, a hydraulic film, etc.; The fourth is that the sputtered film has large particle energy, various film materials have various technological measures, film adhesion, film structure is tight, and mechanical strength is good; Fifth, the magnetron film is luxurious and bright, reflecting many color varieties; Sixth, the light control is strong, and it can ideally control the amount of light flux and heat radiation entering the room, thus realizing the requirements of people for shading and cold energy conservation. Therefore, buildings and other buildings that can reflect the level of modern architecture use vacuum magnetron cathode sputtering coated glass as hidden frame curtain wall glass. On-line thermal spray coating glass is a chemical vapor deposition (CVD) process combined with float production process. When the glass is still at 600-700°C, the film formed by gas phase reaction and post-treatment has thermal stability above 700°C. , It has a unique position in the application of curtain wall glass for hot bending forming. Third, there are hidden dangers in the use of structural adhesives Silicone structural sealant is a kind of organosiloxane polymer, which is composed of more than 100,000 silicon-oxygen bond monomer molecules, and the macromolecule linear bond is the main bond, combines different organic groups and is cross-linked. Reacted polymers with different properties. Due to the need to destroy the silicon oxygen bond requires a lot of energy, it has excellent resistance to aging. Such as sunlight resistance to ultraviolet radiation and ozone resistance and heat resistance and low temperature characteristics. It is composed of silicone polymer, coupling agent, catalyst and filler, coloring ingredients and so on. The introduction of phenyl groups into the silicone molecule enables the silicone adhesive to lose its flexural properties at -40 to 60°C. In the coupling agent, the pro-substrate gene forms a similar chemical bond with the surface of the substrate, which reflects the bond strength to the substrate. The filler has an effect on the surface structure, surface activity, dispersibility, etc. tearing degree. A layer of coupling agent is coated on the surface of the filler particles, so that it can be firmly combined with the silicone polymer, and the strength of the silicone sealant is improved. For the hidden frame curtain wall, its outstanding performance characteristics are: 1 has high bond strength and cohesive strength One of the reasons is that it has good wetting properties and can penetrate between the microscopic peaks and valleys of the surface to be bonded to form intimate contact with each other, thereby creating attractive forces between the glue and the substrate molecules. The second reason is that part of the coupling agent in the colloid diffuses to the bonding interface, and its pro-substrate gene forms a bond with a substrate similar to a chemical bond polymer and is difficult to separate. However, if the surface to be adhered is incompatible with the glue, the adhesive property will not be completely lost in two weeks after bonding. The presence of residual dirt or dust on the surface to be bonded to form a weak boundary layer can also seriously affect the bonding performance. Cohesive strength is the ability of the colloid itself to resist tension, compression and shear under different conditions and to be twisted without being destroyed. Its high cohesive strength allows it to act under the combined effects of high wind loads and combined effects, and does not allow excessive bending, deflection, etc., of the edges of the hidden frame curtain wall glass to prevent glass breakage while preventing The glass of the curtain wall collapses due to excessive deformation of the structural glue layer caused by expansion and contraction due to a temperature difference. 2 has excellent electrical insulation and physiological inertia It is one of the less biologically active materials known to have no rejection reaction with the animal body. Its curing mechanism is that in the presence of a catalyst, a trace amount of water causes the reactive group to react, thereby causing a cross-linking reaction to form an elastomer. The structural glue is divided into two types, one-component and two-component. No matter which one is adopted, the compatibility and pull-out test must be performed before the material is purchased. After passing the test, there is a warranty policy that can be used. It cannot be expired during use. However, there are some manufacturers in the country that do not make compatible tests on the production, or come up with a report that is not a miscibility test or a bond test report for this project, or a follow-up report after the construction is false. It is definitely not right. It is a truly qualified report. The relevant materials purchased must also be the same as the materials in the report. Because the manufacturers of each batch of aluminum, coated glass, double-sided tape, production conditions, raw materials, production tools can not be exactly the same, there have been batches of dissolved in a few days and then a batch of materials to do compatibility experiments will not dissolve There can be no luck and jokes about science. Fourth, there are hidden dangers in the design The quality of the curtain wall is good and bad. It is design calculation based on the front lane. It is impossible to determine the section size of the aluminum section without calculation. There are currently two situations in the design calculation method: one is the allowable stress design calculation method based on experience-based constant value expression; the other is the limit state design calculation method based on probability theory. The building curtain wall is the external maintenance structure of the building. It should use the limit state design method based on the probability theory, and it is better to use the design expression of the partial coefficient to calculate. Its design calculation steps: The first is to obtain architectural design and relevant information on the proposed site; The second is to select the building profile series or section design and glass type and calculate its geometrical characteristics parameters; The third is load and role calculations; Fourth, force analysis and internal force calculation of the profile sash and glass; Fifth, effect combination and take the larger value; Sixth, the glass strength and deformation calculation must meet the requirements; Seventh, the strength and deformation calculation of the profile sash must meet the requirements; Eighth, calculate the effect of profile temperature; determine the size of the structure; Nine is the connection calculation: column, beam connection; column and connector and connector and embedded part connection; embedded part anchorage calculation; Ten is the calculation of the width and thickness of the seam. After calculation, the position of embedded parts and the series of buried plates, anchor bars, dimensions and profiles can be determined. However, some domestic manufacturers do not strictly perform this procedure. Some of the curtain walls and their height, shape, geographical location, climatic conditions, environment, and importance are all adopted in the 150 series. This is a very serious practice. When designing the curtain wall, wind load is an important design parameter. It is in a controlled position in the role of gravity, temperature and earthquake. The wind load plays a decisive role in the size of the glass, the size of the glue joint, and the section of the bar. If the value of the wind load is not appropriate, it will affect the safe use of the curtain wall. Some manufacturers depress the value of wind load and do not consider the local wind pressure value in 50 years to achieve the purpose of reducing the profile section size, glass thickness, seam width and thickness, thereby reducing costs and increasing profits illegally. In this way, a time bomb was buried in the design. Once a sudden encounter with a gale in a 50-year event, it would have to be completed and bring great losses to people's lives and property. Hidden troubles in installation and construction 1 Production of Structural Glass Assembly Components for Hidden Frame Curtain Walls The construction conditions are very strict. It is an important guarantee for the safety and reliability of hidden glass curtain walls. The destruction of hidden frame walls is mainly caused by adhesive failure. Therefore, cleaning and purifying are the key steps in the production of structural glass assembly, and they are also one of the major technical measures for safety and reliability. The following cleansing agents are generally used for cleaning and purifying substrates with adhesive surfaces: First, non-oily pollutants, using a mixture of 50% isopropyl alcohol and water; The second is oily pollutants, using xylene, methyl, and ethyl ketone. Cleaning and purifying method: two rags are performed. Both rags should be a cotton cloth that does not lose its velvet and does not fade. Pour the solvent on a rag to wipe the surface of the substrate. Before dissolving the solvent of the stain, use another clean rag to dissolve the solvent. Clean the stain with a solvent (this rag is dirty and replace it with another one). Can not wipe after solvent evaporation, because the solvent is volatilized, the stain still remains on the surface of the substrate, the rag can not wipe away. After 10 to 15 minutes of purification, glue injection should be carried out immediately. Otherwise, the surface of the substrate will be re-contaminated by pollutants such as dust in the surrounding environment. Plastic injection: Before the injection of glue, three proofreadings of structural sealants (for varieties, grades, and production dates) that do not meet the requirements and expire must not be used. In practice, it has been found that there are too many misuse accidents that must be highly valued. The one-component or two-component glue is injected into the cavity where the glass and aluminum profiles are used as side walls and the bulkhead or tape is the bottom plate. The injection of glue at a uniform and appropriate speed in sequence can cause the air in the cavity to be discharged. Prevents voids and bubbles in the adhesive gap. Ensure that the seam is full. After the injection of a component is completed, immediately squeegee the blade with a knife or empty the tail of the cartridge. The ambient temperature in the plastic injection room should not exceed 21°C and the humidity should not exceed 50%. Resting and maintaining: After the plastic injection, the plates should be put in standing and maintenance. The stacking method for curing is generally the stacking of components. Each component is covered with 4 equilateral cubic foam blocks on a layer of components. It should not be placed more than 7 layers, and the cube size deviation should be less than or equal to 0.5mm. Otherwise, it will be unsettled. The environmental temperature of curing is 18 to 28°C and the relative humidity is 65 to 75%. After two-component static curing for 3 days, after the one-component component was left to stand for 7 days, the sample was inspected and the sample was cut open. The gel was not completely cured when the notch colloid was observed to be shiny, and the surface was completely cured if it was flat or dark. If the test does not show complete cure, the incision continues the next day and the second sample is fully cured. The 14 days have not yet completely cured, indicating that there is a problem with the gum. Make a record of inclusion in the file. Before the component is completely cured, it cannot be moved to avoid the glue seam from generating activity and affect the curing of the glue. After the glue is completely cured, the component can be placed in the storage place and the curing can continue for 14 to 21 days to make it completely adhere to the hardness requirement. Can be shipped to the site now installed. The negligence of any of the above links will make the curtain wall bond failure, and must take practical technical guarantee measures. However, some domestic manufacturers have glue on the spot, the temperature, humidity, and cleanliness are not guaranteed. The bonded glass plates should be stored in 7 to 21 days after they have been fully cured to reach the hardness requirements before they can be installed and used. However, there are many manufacturers in practice. Ignore the problem by rushing the schedule, and if it does not meet the requirements, install it on the use of the wall. This will not guarantee the quality of the curtain wall. 2 bolts directly connected to steel plate embedded parts and aluminum alloy curtain wall profiles It can often be seen on the construction site that steel plate embedded parts and aluminum alloy curtain wall profiles of buildings are directly connected with general bolts. When the surface of the steel and the aluminum and steel bolt contact surface is exposed to moisture, electrochemical corrosion occurs and a small battery is formed. The aluminum material is powdered and eroded off layer by layer. Therefore, steel plates other than stainless steel plates must be preserved. Deal with the use of insulating mats (on behalf of elasticity) between the phases. 3 Curtain Wall Embedded Parts Before the concrete is poured, it must be welded to the steel bars of the wall. Some owners will pre-burie the main building of the building. This is very wrong. This forces the embedded parts to be reinforced by other methods. None of the methods is beneficial to the firmness of the curtain wall and must be avoided. To make structural glue for structural glass assembly components. The rubber-washing workers must be trained. After passing the examination, they will be certified and qualified to be skilled and of high quality. However, at present, some manufacturers do not have such workers to carry out training and find jobs outside of the contractors. As a result, they cannot control their quality. There are many prestigious manufacturers whose reputation has been greatly reduced. In order to ensure the construction quality of the aluminum frame, design, production and installation of the hidden frame curtain wall, in particular, we must meticulously implement the requirements of GB3035 "Building Curtain Wall" standard and JGJ102 "Technical Specifications of Glass Curtain Wall Engineering". On this basis, the manufacturer must also develop internal control standards higher than this standard. When producing concealed-frame curtain walls, full-time inspectors who combine project-completed technical files, technical supervision agencies, and process inspection and installation tracking should be established to conduct flow inspections. All personnel should be unified to attach great importance to quality and never give up. Hidden troubles must be satisfied with their own satisfaction and the local quality inspection department is assured of customer satisfaction. For some of the above issues, users must pay attention to on-site insights to ensure that no such problems occur.