Analysis of vortex levitation

Abstract

In this paper, a new pneumatic levitation method, called vortex levitation, is introduced. Vortex levitation can achieve non-contact handling by blowing air into a vortex cup through a tangential nozzle to generate a swirling air flow. Experiments and analysis on its basic characteristics were conducted. It was confirmed that negative pressure is caused by the centrifugal force of the swirling air flow and is distributed like a parabolic curve to apply a lifting force. Therefore, a work piece placed under the vortex cup can be picked up and held at an equilibrium position where its weight is balanced by the lifting force. It was also revealed that the pressure distribution varies as the gap thickness between the vortex cup and the work piece changes. Accordingly, the lifting force is dependent on the gap thickness when the supply flow rate is fixed. In a considerable narrow region below the vortex cup, the lifting force decreases if the work piece deviates from the equilibrium position to approach the cup and becomes big over the weight of the work piece if the work piece leaves the cup from the equilibrium position. As a result, the work piece can levitate stably at the equilibrium position. Furthermore, it was found that the gap thickness has little effect on air supply flow rate in case that the gap thickness gets beyond 0.1 mm, where lifting force can be obtained, and increasing the supply flow rate can generate a larger lifting force.