The Armys Rotorcraft Force Modernization Fleet requires a substantial increase in main gearbox power density, with minimal impact on the gearbox interface. Instead of increasing gearbox size and transmission weight, this project seeks to accommodate the higher power density requirements through designed material processing techniques, integrating several state-of-the-art manufacturing processes to specifically improve the gear material contact and bending fatigue strengths. In Phase I, a novel heat treating method called "Intensive Quenching", as well as superfinishing will be investigated to determine the feasibility of improving the bending fatigue life of the Pyrowear 53 steel by at least 25% over conventional processing.
Benefits: The project will benefit the Army's commercial Original Equipment Manufacturers (OEM's) and the Army itself by achieving improved rotorcraft transmission power density while not increasing gearbox weight. In place of conventional oil quenching, the intensive quenching process will provide an environmental safety benefit by substitution of water for oil. Free quenching proposed in the innovation, as opposed to press quenching, will reduce heat treatment cost by at least 50%. While superfinishing may add to the existing machining cost, the increase will more be more than offset by the improved part life. Overall, the use of a low-cost, environmentally friendly heat treatment in combination with superfinishing of the gear tooth will increase transmission component life by at least 25%. The added use of Pyrowear 53 will provide helicopter safety and allow damaged transmissions to function for a longer time period.
Keywords: Pyrowear 53, Fatigue Life, Helicopter Gear Material Performance Improvement, Heat Treatment, Superfinishing, Intensive Quenching, Residual Stress
