Three Dimensional Numerical Analysis Of Inertia Radial Friction Welding Thermal Process

Radial friction welding is one of the important friction welding technologies developed in recent years. It inherits the advantages of the traditional friction welding such as high reliability, high efficiency, high precision, and environmental protection. Radial friction welding process is a quick energy transfer and metallurgical process at high temperature and high pressure, and its welding thermal porcess has important effect on the welding quality. Therefore, the study of the heat generation and thermal process during radial friction welding process is of great significance for the development and optimization of welding parameters.In this paper,37CrMnMo steel pipes were joined by inertia radial friction welding with the ring of45steel, and the welding parameters were also optimized. The proper energy input required for the welding was estimated using a layered method, which indicates the proper initial rotation speed of the flywheel is548rpm. The stable inherent resistance torque was obtained by testing the speed of flywheel without load and theoretical calculation, which is485N·m for HSMZ-130inertial axis/radial friction welding machine. The temperatures at the friction interface and different positions from the friction interface were monitored by semi-natural thermocouple and standard K-type thermocouple. The results show that the maximum temperature on the friction interface is1115℃. The temperature gradient near the friction interface is very high and is low away from the friction interface.Assuming that the friction heat is generated by a thin layer with the thickness of1mm, the heat source model for the radial friction welding process was established based on the basic theory of Coulomb friction theory, in which the effect of the heat loss by the extruded material was considered. A correction coefficient related to the average temperature of the ring was also introduced into the friction pressure in the model. The results show that the temperature on the friction interface and the rotation attenuation process are in good agreement with the experimental results. The heat source model can be used to analyze the heat generation and thermal process during inertia radial friction welding process.The studied results of heat generation show that the average energy efficiency of the flywheel is70.4%and the energy distribution ratio for both sides of the friction interface is about1:1. During the energy attenuation process of the flywheel, there appears peak power in friction phase and forging phase,respectively, and the peak power in friction phase is about3times as that in forging phase. The temperature increasing rate on the friction interface has a similar trend with the frictional heat generation, and the maximum temperature is1152℃, which accords well with the experimental results. Temperature field distribution shows concentric circles along the radial direction, and ellipse along the axial direction, and it will be lower with the increase of the distance away from friction interface. After welding, The the total amount of radial shortening is1.981mm, and1.449mm in friction phase and is0.532mm in forging phase, respectively.