In recent years, with the development of China's steel structure application technology, economical profiles such as cold-formed thin-walled steel have developed rapidly. Compared with traditional rolled profiles, cold-formed thin-walled steel has reasonable cross-section material distribution, large radius of gyration and resistance to bending. And the characteristics of good torsion resistance. It is not like hot-rolled steel to increase the material area to increase its bearing capacity, but to improve the bearing capacity and save steel by changing the section shape of the steel.
Economic cross-sectional characteristics. The working state of the web in the iron tower is mostly the instability of the large and thin ratio of the pressing rod. The profile such as angle steel has no obvious advantages in section characteristics, and the available specifications are limited. Cold-formed steel can select the appropriate cross-section according to the force characteristics of the member, and make full use of its cross-section interface characteristics to make it more economical and reasonable.
Random product specifications. A 10 ton conventional iron tower requires up to 25 types of angle steels of different specifications. It is conceivable to purchase a variety of profiles with a large number of specifications and small batch sizes. Therefore, the processing of iron towers often appears to replace the size of the tower material with a small substitute. In the iron tower processing enterprise, it is normal to cause 5% waste due to the substitute material of the tower material, and the number is up to 10%. The production equipment of cold-formed thin-walled steel is simple, and a cold rolling mill can produce various specifications of steel. The quantity and specifications of the production are not limited, which provides a strong guarantee for the supply of iron tower materials.
Variable product size. A 10-ton iron tower usually consists of nearly 2,000 components, and the length of the components of the tower varies. At present, hot-rolled steel is a fixed-size product. Therefore, when hot-rolled steel is used for material blanking, there is often a material surplus, and the material loss due to the material length is up to 5%. Cold-formed steel products can be supplied in various sizes of steel according to the needs of users. The finished product rate is high (up to 99%), and the remaining material is less, which can effectively reduce the material loss in the processing of iron towers.
Diverse shapes. The diversity of the cross-section shape of the cold-formed thin-walled steel can avoid the disadvantage that the 90-degree angle steel can only design the tower into a square or rectangular shape and the tower body is inclined to cause the joint members to be non-coplanar. It designs a new and reasonable iron tower for the designer. Flexible conditions. If a three-column iron tower can be built, the iron tower web system can also be optimized, and a more reasonable iron tower web arrangement can be designed. This is a new type of iron tower system, which further reduces the weight of the tower, saves materials and reduces the number of components. way.
High-strength profiles. For the high-strength material steel used in the iron tower, if the cold-formed steel product is used, the defects of the hot-rolled steel supply volume limitation and the rolling process difficulty can be effectively avoided.
Anti-corrosion problem. Since the transmission line is operated in the field for a long time, in order to ensure the safety of the tower, the transmission tower is usually protected by hot-dip galvanizing. Cold-formed thin-walled steels are not suitable for hot-dip galvanizing due to the variety of cross-sectional shapes and thin steel profiles. At present, some advanced anti-corrosion technologies and processes are constantly appearing, such as the use of weather-resistant materials and new plating processes, providing a good solution for the anti-corrosion of cold-formed thin steel.
The production process of high-strength weathering steel has become increasingly mature and has been widely used in railway systems. The high-strength weather-resistant cold-formed steel material is used on the transmission tower. Compared with the traditional production method of manufacturing the iron tower, although the one-time investment of the material is slightly higher, the economic and social benefits are significant due to the removal of the anti-corrosion process. The cost per ton can be reduced by about 20%.
In the late 1980s, the relevant scientific research units began to study the feasibility of cold-formed thin-walled steel for transmission towers, but because of the high price and technical means of cold-formed steel at that time, plus the scale of the early towers Smaller, the existing hot-rolled steel can meet the requirements of use, and the project has not been approved. In recent years. With the development of China's steel structure application technology, economical profiles such as cold-formed thin-walled steels have developed rapidly. The consumption of these economical profiles is increasing year by year, the processing cost is decreasing, and the excellent performance of its own cross-section is more significant. This opens up the possibility for the application of cold-formed thin-walled steel on transmission towers.
The use of cold-formed thin-walled steel saves resources and energy. The promotion of high-strength weather-resistant cold-formed steel on transmission towers can not only reduce iron tower consumption, but also reduce processing costs and avoid environmental pollution. It is a work with significant economic benefits and environmental protection significance. Therefore, it is necessary to carry out high-strength cold-formed steel in time, especially the application research of high-strength weather-resistant cold-formed thin-walled steel on transmission towers.
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