Application of new technology in steel structure welding
7 combined floor sill penetration welding technology
The large-scale use of steel structure composite floor slabs of high-rise buildings has made great progress in the penetration welding technology of studs that are different from ordinary stud welding. The so-called penetration welding is the welding of studs through the arc welding during welding. On the surface of the steel beam, the welding stud plays two roles at this time. One is horizontal shear resistance, which prevents the horizontal displacement of the composite floor on the steel beam; the other is vertical anti-lifting, which prevents the composite floor from separating from the steel beam surface. Therefore, it plays a very important role in the seismic damage of steel structures, especially high-rise and super high-rise steel structures. The quality of the welding is one of the keys to the quality of the entire steel structure. Because the stud penetration welding is affected by many factors, including the galvanized layer of the profiled plate, the thickness of the plate, the gap with the surface of the steel beam, and water, rust, slag, paint, etc., and at the construction site, various factors are mutually Interweaving is not certain. Therefore, in order to obtain good welding quality, the welding process and construction requirements are very high. The China National Metallurgical Group Construction Research Institute has conducted a lot of experimental research and collected several kinds of stud welding at home and abroad. The tens of thousands of welding parameters of the machine, through the analysis of wave shape analysis and actual welding quality, the first time the stud penetration welding process is divided into four stages: arcing stage, arc unstable combustion stage, arc stable combustion Stage, arc-extinguishing stage. Based on this, the energy control method is proposed. This method has been successfully used in various projects, such as Beijing LG Building. The closed-type galvanized sheet is used in the project. The coating is up to 280 g/m2 and the thickness is up to 1.5 mm, the diameter of the stud is 19 mm, and the energy control method is used to guide the construction. The pass rate is over 95%, and good results are obtained.
8 Welding technology using ceramic liner
Ceramic liners are forced to form single-sided welding, which is convenient for welding, good for back molding, stable and reliable welding quality, and has gradually replaced steel gaskets in welding production in some fields. Ceramic liners are used in double-sided welding. Due to the large root clearance and strong welding specifications, the back does not need to be cleaned, which not only greatly improves the production efficiency, but also ensures the quality of the weld root. Since the ceramic liner is not sensitive to the gap at the root of the groove, the length of the gasket can be arbitrarily lengthened and shortened, which is especially suitable for on-site installation of weld seams. Therefore, in recent years, some steel structure projects, especially bridge engineering, have been applied due to When welding, the liner also participates in the metallurgical reaction of the weld deposit metal, which will have certain influence on the chemical composition and mechanical properties of the root weld metal, especially the impact on the root impact toughness, given that there is no corresponding The standard is defined, so it should be given enough attention in practical applications.
9 Steel structure embedded parts pressure submerged arc welding technology
With the rapid increase of large-span steel structure public buildings, the application of steel structure pillars (reinforcing bars) is increasing. Therefore, the pressure submerged arc welding technology of steel structure embedded parts is continuously applied in engineering practice. Its key technical measures are:
1Select a welder or a modified stud welder with stable and safe performance;
2 Carefully carry out the welding procedure qualification test and select the corresponding welding process parameters according to the diameter of the steel bar;
3 According to the principle of strong welding joints and base metal, use flux with good performance for both AC and DC.
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