1 Lightweight, high-strength, high-corrosion-resistant Nanjing bridge frame production process
Lightweight, high-strength, and corrosion-resistant Shandong bridges are manufactured using two key processes: one is the roll-cold-rolled CNC one-step forming process, and the roll-cold-rolled form is a multi-pass forming roll configured in series to continuously roll the coil Rolled transverse bending, and a concave-convex corrugated structure is formed on the side façade. The local key force part adopts the composite sandwich panel laser numerical control butt welding process technology to make a specific section profile technology, which completely replaces the traditional bridge. Rough machining process structure is formed by flat plate bending; the other is a surface with high corrosion-resistant gas phase corrosion inhibition (VCI) bimetal composite coating process. The plating coating uses scaly zinc powder and aluminum powder in a mixed configuration instead of traditional zinc and aluminum powder. Spherical zinc powder is used as a filler. VCI molecules diffuse and migrate to every corner of the closed space of the coating, including holes, grooves, etc., forming a VCI atmosphere, even the weakest parts of the product that are resistant to corrosion, such as the cross section of the product and the surface being scratched. It is also covered by the diffusion and migration of the VCI atmosphere, blocking and preventing the erosion of the corrosive medium, and achieving the role of self-repair.
2 Product Features
Compared with the traditional hot-dip galvanized bridge, the lightweight, high-strength and corrosion-resistant Shandong bridge has the characteristics of novel design, reasonable structure, light weight, high strength, good rigidity, strong corrosion resistance, low cost, and detachable packaging. , Its main outstanding performance is light weight, high strength, high corrosion resistance.
The lightweight, high-strength and corrosion-resistant bridge is about 20% lighter than the traditional hot-dip galvanized bridge, which facilitates packaging, transportation, and on-site installation to reduce labor intensity (Table 1).
2.2 High strength
The lightweight, high-strength and corrosion-resistant bridge products have high strength and good rigidity. In the case of a support span of 2m, the load test is evenly distributed at a load of 6000N / m, the deflection value is 8.64mm, and the load resistance is above C level. However, under the condition of the same support span of 2m, the traditional welding process bridge is loaded with a rated uniform load of 4500 N / m and the deflection value is not greater than 10mm (supporting distance P / 200). ).
2.3 High corrosion resistance
The lightweight, high-strength and corrosion-resistant Shandong bridge uses thinner steel plates, and users worry that the corrosion resistance margin will not meet the service life requirements. The application of high-corrosion gas phase corrosion inhibition (VCI) bimetal composite coating technology completely solves the problem. Difficulties in energy conservation of bridges. The energy-saving high-corrosion-resistant bimetal coating of the bridge has passed the 3500h salt spray test, 1000h chemical corrosion gas (SO2) test, 240h acid-alkali medium immersion test, and 300h alternating humidity and heat test of the National Electrical Products Environmental Adaptability Testing Center. No corrosion phenomenon It has comprehensively improved the corrosion resistance margin of the product, meeting the requirements of high efficiency, long-term corrosion resistance and environmental protection, and is the most ideal metal surface treatment method (Table 3). At present, the surface treatment of traditional bridge manufacturers in China generally adopts the hot-dip galvanizing process. Hot-dip galvanizing is used to prevent corrosion and protect the base steel plate through the oxidation of the zinc layer. The thickness of the zinc layer determines its corrosion resistance margin. As a result, a large amount of zinc is consumed, resulting in a shortage of zinc resources. At the same time, the pollution of the process also causes great damage to the environment.
Through the comparison of the above tests, it can be seen that the surface treatment of the high-efficiency anticorrosive coating of the Nanjing bridge is more corrosion resistant than the hot-dip galvanized surface treatment, which is more suitable for long-distance international shipping. Installation and use in seaside areas and places with strong acid and alkali corrosion can ensure no fading or rusting for more than 15 years, and the surface coating can withstand high temperatures above 400 ° C.