We study synchronization of two eccentric rotors (ERs) with common rotational axis in the vibration system of the far-resonant spatial motion. We deduce the dimensionless coupling equation of two ERs with applying the average method of small parameters. We convert the synchronization problem into the existence and stability of solving the zero solutions for the dimensionless coupling equations. By introducing the synchronization torque and the difference between the residual torques of two motors, we obtain the synchronization condition that two ERs achieve the synchronized motion. We derive the stability condition of the synchronized motion, which satisfies Routh-Hurwitz criterion. We discuss numerically the choosing motion feature of the vibration system, which indicates that the vibration system has two steady motion modes. The synchronization torque forces the phase difference to approachπwhen the structural parameters of the vibration system satisfy the condition of the spatial cone motion, and the synchronization torque drives the phase difference to approach zero when those satisfy the condition of the spatial circle motion. Finally, through the comparison and analysis of experimental data, the structural parameters of the vibration system satisfying the above two conditions can guarantee the synchronization stability for two ERs.

Vibratory feeder is known as one of major machines in various industries. The feeding parts in a vibratory feeder are experiencing repeated discontinuous friction that can be considered as a typical strong nonlinear dynamic problem. It is very significant to obtain the motion of parts under different alternating loads for the design of vibratory feeder. An analytical model of parts’ motion in sliding regime was constructed and verified with a simplified model based on discrete element method. An improved increment harmonic balance method was proposed to obtain the dynamic behaviors of vibratory feeder and the motion of feeding parts. In contrast to previous researches, we considered the interactions between vibratory feeder and parts in detail, not only containing the effects of the dynamics of vibratory feeder on the motion of parts but also the motion of parts on vibratory feeder. Finally, studying the interactions for various parts’ masses in different frequencies, the motion of parts had a significant effect on the dynamics of vibratory feeder. In reverse, the alterations of the dynamics of vibratory feeder influenced the motion of parts and conveying speed. In the design of vibratory feeder, the interactions between vibratory feeder and parts should not be neglected.