Hot rolled special-shaped steel for coal mining machinery
Hot-rolled special-shaped steel for coal mining machinery is a special-shaped hot-rolled steel product designed specifically for coal mining machinery. Its complex cross-sectional shape and excellent mechanical properties meet the high strength and reliability requirements of coal mining machinery in the harsh underground environment. This type of steel often features asymmetric cross-sections, such as channel, I-beam, and Z-shaped shapes. Some also incorporate specialized connection structures, allowing direct use in the manufacture of key components for coal mining machinery, reducing welding and machining steps and improving production efficiency. Made primarily of low-alloy, high-strength steels such as Q355 and Q460, this steel, through alloying and hot-rolling, possesses excellent wear resistance, corrosion resistance, and fatigue resistance, making it a crucial factor in the safe operation of coal mining machinery.
The production process of hot-rolled special-shaped steel for coal mining machinery is complex, placing extremely high demands on the design of rolling equipment and dies. First, the cross-sectional shape of the steel is designed based on the structural drawings of the coal mining machinery. Finite element analysis software is used to simulate the rolling process and optimize the pass design to ensure uniform stress distribution during rolling, avoiding defects such as folding and cracking. The billets, made of high-quality low-alloy steel, are heated in a furnace to 1050-1200°C before entering the hot rolling mill. They are gradually formed through multiple passes of pass rolling. The reduction and rolling speed of each pass must be precisely controlled to ensure dimensional accuracy across all cross-sectional areas. For special-shaped steel with complex cross-sections, universal rolling mills and specialized rollers are often used to ensure that the shaped sections are fully filled and clearly defined. After rolling, the steel is slowly cooled to reduce internal stresses. It is then straightened, cut, and subjected to non-destructive testing to ensure the product is free of internal defects and meets performance requirements.
In coal mining machinery, hot-rolled special-shaped steel for coal mining machinery is widely used in key equipment such as scraper conveyors, tunnel boring machines, and hydraulic supports. The center trough of a scraper conveyor is a core component for coal transportation. Using hot-rolled special-shaped steel significantly improves its wear and impact resistance. The trough sides and center plates of the center trough are typically made of high-strength special-shaped steel to withstand the long-term friction of the scraper chain and the impact loads of the coal, extending its service life. The cutting arm and shovel blade of a tunnel boring machine are welded from special-shaped steel. Their complex cross-sectional shape optimizes structural stress, reduces equipment weight, and improves tunneling efficiency. The top beam and shield beam of the hydraulic support utilize the high-strength properties of special-shaped steel to ensure support strength, prevent deformation under the pressure of the mine site, and ensure safe underground operations.
The performance of hot-rolled special-shaped steel for coal mining machinery must be adapted to the unique underground environment of coal mines. The underground environment is humid and dusty, and contains flammable and explosive gases such as gas. Therefore, the steel must possess excellent corrosion resistance to prevent rust from affecting structural strength. At the same time, it must also have excellent weldability to facilitate assembly and welding of components, and to avoid defects such as cracks after welding. In terms of mechanical properties, the yield strength must exceed 355MPa and the elongation must be no less than 15% to ensure plastic deformation under heavy loads. Special-shaped steel used in some key components also undergoes low-temperature impact testing to ensure that brittle fracture does not occur in the low-temperature environment underground. For example, the impact energy at -20°C must be greater than 34J.
With the advancement of intelligent and efficient coal mining, the demand for hot-rolled special-shaped steel for coal mining machinery continues to grow, and the requirements for product performance and specifications are also increasing. Manufacturers are collaborating with coal mining machinery manufacturers to develop customized special-shaped steel products. For example, special-shaped steel for large-scale hydraulic supports has a cross-sectional height of over 600mm to meet the needs of large-scale supports. At the same time, they are developing wear-resistant low-alloy steel special-shaped steel. By adding microalloying elements such as niobium and vanadium, the grain size is refined, the wear resistance and fatigue strength of the steel are improved, and the maintenance cycle of the equipment is extended. In terms of green manufacturing, companies are adopting short-process rolling processes to reduce energy consumption and emissions, promoting the sustainable development of coal mining machinery materials. In the future, with the development of unmanned mining technology, hot-rolled special-shaped steel for coal mining machinery will develop towards higher precision and higher reliability, providing stronger support for safe coal mine production.
