Wind power speed-increasing gearboxes are subject to high dynamic loads and require a design life of more than 20 years. Heat treatment requires improving bending fatigue and contact fatigue strength while maintaining core toughness and dimensional accuracy. Large module gears often use deep carburizing, which requires a long cycle and high long-term stability of carbon potential; parts such as internal ring gears often use nitriding to reduce deformation. The popularity of controllable nitriding is limited by the price of imported expert controllers. Using algorithmic transmitters in conjunction with general-purpose PLCs is a feasible way to reduce costs.
- Service: high dynamic load, long life, high reliability
- Deep carburizing: long cycle, requires long-term stable carbon potential and temperature
- Nitriding: small deformation, suitable for internal ring gears and precision parts
- Quality: surface residual compressive stress, core toughness, structure
- Cost reduction: nitriding algorithm transmitter + general PLC
Service characteristics of wind power gears
The speed-increasing gearbox of a wind turbine needs to operate under changing wind loads for a long time, withstand high dynamic loads, and the maintenance and replacement costs are extremely high. Design requirements include:
- High bending fatigue strength and contact fatigue strength;
- Residual compressive stress in the surface layer to enhance fatigue resistance;
- The heart remains resilient;
- Reduce weight as much as possible and ensure accuracy.
The Gauss Control Wind Power Machinery Industry Page also points out that after heat treatment, the gear must improve its ability to withstand bending fatigue loads and surface friction fatigue, increase surface residual compressive stress, and maintain flexible core performance, which requires precise and reliable heat treatment process control.
Deep carburizing
The effective hardened layer of large-module wind power gears needs to be deep, and the carburizing cycle can last for tens of hours or even longer. difficulty:
| Difficulty | Control considerations |
|---|---|
| Long-term carbon potential stability | Stable carrier gas, long-term reliability of the probe, regular calibration |
| Uniform temperature of large parts | Furnace temperature uniformity, temperature difference between inside and outside parts, and heating strategy |
| Carbide and retained austenite | Strong penetration and diffusion segmented design, alloy factor correction |
| deformation | Furnace loading, quenching method, subsequent gear grinding allowance |
| Layer depth prediction | Diffusion simulation + furnace sample verification |
Controlled nitriding
Parts such as the inner ring gear and some planetary gears are nitrided, which has the advantages of low temperature and small deformation. Controlled nitriding controls the compound layer and diffusion layer through Kn to avoid brittle layer spalling and ensure fatigue performance.
Lower the threshold for controllable nitriding
The high price of imported nitriding expert controllers is the main reason for the slow popularity of controlled nitriding. The idea put forward by Gosi Control on the wind power industry page is to use the nitriding control algorithm accumulated by the German cooperation team for 30 years into the nitriding expert system transmitter, so that any instrument or PLC with a control loop can become a nitriding expert controller, thus providing a cost-effective nitriding process control system and core components (hydrogen probe, ammonia decomposer, flow meter, etc.) that can replace foreign brands.
Quality record
Wind power customers usually require complete process curves, furnace sample inspection results and material traceability for each piece or furnace. It is recommended to use an electronic recording system.
Frequently asked questions
Why is the carburization of wind turbine gear prone to uneven layer depth?
Large parts and large loads lead to uneven temperature and atmosphere in the furnace, and the probe and carrier gas may drift over a long period. Temperature testing, atmosphere circulation and process monitoring need to be strengthened.
Can nitriding replace carburizing for wind power gears?
Depends on load and design. The nitriding layer is shallow and suitable for some gears and internal ring gears; large-module gears with high contact stress usually still use carburizing.
What standards are required for heat treatment of wind power gears?
Material and heat treatment quality grade requirements in gear design standards, as well as customer specifications, are generally followed. The contract and drawing requirements shall prevail.