Analysis of the Acceleration Transfer in the Unguided Vibratory Finishing Process

Abstract The work bowl acceleration of a vibratory finishing machine is mainly determined by the process input variables, e. g. the mass distribution between the upper and the lower imbalance weights, the offset angle between these imbalance weights and the rotational speed of the imbalance motor. The acceleration of the work bowl has a strong effect on the acceleration of the abrasive media and workpiece within the work bowl and thus on their movement. This movement indirectly determines the contact conditions, contact forces and relative velocities, between the abrasive media and the workpiece. The contact conditions have a strong effect on the material removal rate and the surface roughness of the machined workpieces in a vibratory finishing process. Due to the fact that the contact conditions can hardly be measured during the vibratory finishing process a comprehensive understanding of the transfer behavior of the work bowl acceleration on the acceleration of the abrasive media and the workpiece and thus on the prevailing contact conditions is necessary. Therefore, this publication presents an innovative approach to identify these cause-effect relationships, in order to determine the machining intensity based on the work bowl acceleration as a function of the process input variables. Hence, new measurement systems are presented which enable the determination of the acceleration of the abrasive media and the workpiece as a function of the acceleration of the work bowl of a vibratory finishing machine for the first time. Based on these investigations it is possible to identify significant areas for the work bowl acceleration, as well as for the acceleration of the abrasive media and the workpiece and thus for the contact conditions, contact forces and relative velocities, which can be used for a targeted control of the machining intensity of vibratory finishing processes.