Improving the load-bearing capacity of double gears under heavy-load conditions requires coordinated improvements across multiple dimensions, including material selection, heat treatment processes, structural optimization, surface strengthening, lubrication design, load balancing control, and manufacturing processes. This comprehensive approach aims to enhance the gear's strength, toughness, wear resistance, and stability.
Material selection is fundamental to improving the load-bearing capacity of double gears. Heavy-duty gears require high-strength, high-toughness, and excellent wear-resistance materials, such as low-carbon alloy steel. After carburizing and quenching, these materials develop a high-hardness, high-wear-resistant high-carbon martensite structure on the surface, while the core retains sufficient toughness to withstand the impact and alternating stress under heavy loads. Furthermore, novel materials such as functionally graded ceramic materials and bulk metal-glass composites are under development. These materials combine the comprehensive mechanical properties of metals and ceramics, potentially further enhancing the load-bearing capacity of double gears.
Heat treatment processes have a decisive impact on the performance of double gears. Carburizing and quenching is the most commonly used heat treatment process for heavy-duty gears. Carburizing enriches the gear surface with carbon, followed by quenching and low-temperature tempering to obtain a surface layer with high hardness and wear resistance, and a core with good toughness. In addition, nitriding and carbonitriding processes can also be used to strengthen gears under specific working conditions. For example, nitriding significantly improves the surface hardness and wear resistance of gears, but the nitrided layer produced by ordinary nitriding is relatively thin and difficult to meet heavy-duty requirements. Therefore, rapid nitriding technology or composite strengthening methods, such as rare earth catalytic infiltration and surface pre-oxidation, are needed to increase the depth of the nitrided layer and load-bearing capacity.
Structural optimization is another key measure to improve the load-bearing capacity of double gears. By increasing the gear module, optimizing tooth profile parameters (such as using edge-modified tooth profiles), and increasing the face width coefficient, the bending strength and contact fatigue strength of the gears can be significantly improved. Meanwhile, helical gear transmissions have significant advantages under heavy-duty conditions due to their high overlap ratio and smooth transmission. However, helical gears generate axial forces, requiring carefully designed thrust bearings to withstand these forces and prevent poor meshing due to axial movement. Furthermore, parallel double-gear transmission systems can utilize load balancing control to ensure even load distribution between the two gears, avoiding localized failures caused by concentrated loads.
Surface strengthening technologies can further enhance the surface properties of double gears. Shot peening introduces a residual compressive stress layer by impacting the gear surface with high-speed shot, improving fatigue strength and resistance to spalling. Ultrasonic surface strengthening combines ultrasonic vibration and mechanical extrusion to induce plastic deformation on the gear surface, thereby refining grains and increasing hardness. These surface strengthening technologies can significantly extend the service life of double gears under heavy-load conditions.
Lubrication design is equally crucial to the load-bearing capacity of double gears. Good lubrication reduces friction and wear during gear meshing, lowers tooth surface temperature, and prevents tooth surface scuffing and pitting. For heavy-load conditions, lubricating greases with excellent extreme pressure anti-wear properties, high-temperature stability, and oxidation stability must be selected. A reasonable lubrication system structure, such as oil passages, oil grooves, and oil sumps, must be designed to ensure that the lubricating grease is evenly and fully coated on the gear surface. Furthermore, adopting novel lubrication methods such as oil mist lubrication or oil-air lubrication can further improve lubrication efficiency and reduce energy consumption.
Load balancing control is a key technology in double-gear parallel transmission systems. Under heavy-load conditions, uneven load distribution between the two gears can lead to localized overload and failure. By establishing a virtual prototype model of the double-gear parallel transmission system, the influence of factors such as rotational eccentricity, forging eccentricity, meshing stiffness, damping, and center distance installation error on load balancing is analyzed. A corresponding load balancing control system is then designed to ensure that the two gears evenly distribute the load under heavy loads, improving the system's reliability and stability.
The manufacturing process directly affects the precision and performance of the double gear. High-precision gear machining equipment (such as five-axis linkage gear grinding machines) and advanced manufacturing processes (such as gear grinding processes) can ensure the accuracy of gear tooth profile and tooth direction, reduce meshing errors, and improve transmission efficiency and load-bearing capacity. At the same time, strict control of heat treatment processes (such as carburized layer depth, quenching temperature, tempering temperature, etc.) is also crucial to ensuring stable gear performance.
