Compensation of springback error based on comprehensive displacement method in cold rotary forging for hypoid gear

Special cold rotary forging method for the fabrication of the big wheels of hypoid gears is proposed. The proposed method is established on the basis of the requirements of antifatigue manufacturing processes and the tooth profile characteristics of hypoid gears combined with the movement and forming methods of cold rotary forging. The geometric grid model is constructed on the basis of the basic theory of elastic-plastic thermo-mechanical coupling finite element for metal. Reasonable process parameters and boundary conditions are established. Thus, the cold rotary forging finite element model is built. The springback tooth surface is reconstructed through the results of finite element numerical simulation. The size and distribution of the springback error is the detected. In the springback process, a large displacement and large rotation can occur, so a comprehensive displacement compensation algorithm is adopted to modify the rotary forging die, and a springback error compensation iteration system is constructed based on the modified algorithm. In the case of a camion driving axle gear, the correction of the rotary forging die is analyzed. Results show that the error is already within the allowed range through only three iterations, which proves the efficiency of the system. The modified die is used for machining experiments. The measurement results of the experiment gear are consistent with the simulation results, which proves the reliability of the system. The LTCA of the gear further proves its reliability in compensating for springback error using numerical simulation technique.