Investigation on time-varying friction characteristics of the oil film for the closed hydrostatic bearing in inertial friction welding

Inertia friction welding faces challenges when welding large-scale GH4169 superalloy due to the conditions of an upsetting force of 1250 tons and a rotational speed of 500 rpm. Therefore, the axial loading system in the spindle needs to be enhanced. To fill this gap, a novel closed hydrostatic bearing was developed. The time-varying friction characteristics of the oil film were important for this bearing. For oil films, theoretical and simulation models were established by the hydrostatic principle and inertia friction welding (IFW) theory, and the time-varying friction characteristics were simulated using the dynamic meshing method, which was then discussed. The accuracy of the simulation was verified by theoretical calculations. The results indicated that the velocities of oil films significantly influenced the temperature and pressure fields during the IFW. The velocity and pressure of the oil film were high on the carrier side, enabling it to withstand the upsetting force while the temperature was maintained at 333 K to ensure the stability of the oil. The oil film on the back pressure side had a low velocity and was negligibly affected by temperature. The pressure was three times that of atmospheric pressure, ensuring it would not rupture. This paper provided theoretical guidance for IFW.