Experimental investigation on nozzle diameter of vortex gripper

Purpose Vortex grippers use tangential nozzles to form vortex flow and are able to grip a workpiece without any physical contact, thus avoiding any unintentional workpiece damage. This study aims to use experimental and theoretical methods to investigate the effects of nozzle diameter on the performance. Design/methodology/approach First, various suction force-distance curves were developed to analyze the effects of nozzle diameter on the maximum suction force. This study determines the tangential velocity distribution on the workpiece surface by substituting the experimental pressure distribution data into simplified Navier-Stokes equations and then used these equations to analyze the effects on the flow field. Subsequent theoretical analysis of the distribution of pressure and circumferential velocity further validated the experimental results. Next, by rearranging these relationships, the study considered the effects of nozzle diameter on the inherent vortex gripper characteristics. In addition, this study developed various suction force-energy consumption curves to analyze the effects of nozzle diameter. Findings The results of this study indicated that the vortex gripper's circumferential velocity and maximum suction force decrease with increasing nozzle diameter. Nozzle diameter did not significantly affect the inherent frequency of the vortex gripper-workpiece inertial system or the corresponding suspension stability of the workpiece. However, an increase in nozzle diameter did effectively increase the vortex gripper's suspension region. Finally, as the nozzle diameter increased, the energy required to achieve the same maximum suction force decreased. Originality/value This study's findings can enable optimization of nozzle design in emerging vortex gripper designs and facilitate informed selection among existing vortex grippers.