Theoretical Modeling and Efficiency Improvement of Electrically Activated Rotation-Flow Gripper

An electrically activated rotation-flow gripper uses rotating airflow to generate negative pressure and suction force on a workpiece. The rotational flow is directly driven by a fan connected to an electrical motor, so the gripper only consumes electrical power. Because the centrifugal force generated by the rotating flow helps prevent vacuum leakage, the gripper can handle workpieces with rough and uneven surfaces. In this study, the torque to drive the rotational flow in the rotating chamber and the suction force generated by the gripper are modeled, based on which the efficiency of the gripper can be obtained. The theoretical model shows efficiency could be improved by decreasing the suction force and increasing the size of the gripper. It is also found that adding a disc at the top end of the fan can improve the efficiency of the gripper by 35%. The disc could transform the flow between the fan and the upper shell wall into a turbulent plane Couette flow, thus reducing the driving torque by 24%. In addition, the disc isolated the insufficiently rotating flow near the upper shell wall from the sufficiently rotating flow below it, thereby further increasing the efficiency by increasing the suction force. The theoretical model and the efficiency improvement are verified by experiments.