Effect of supply flow rate on performance of pneumatic non-contact gripper using vortex flow

• We measured the pressure distribution and suction force of a test vortex gripper.
• We proposed three performance indexes for evaluating a vortex gripper.
• There is a quadratic relationship between the maximum force and supply flow rate.
• We obtained a curve which reflected an inherent characteristic of the gripper.
• We proposed a simplified calculation method for the suspension stiffness.

The vortex gripper is a new kind of non-contact gripper, which generates negative pressure by blowing compressed air into a vortex cup through two tangential nozzles. It can provide an adequate suction force for handling a workpiece without contact. This gripper can avoid the disadvantages of traditional gripping devices, such as inducing mechanical scratches, local stress concentration, frictional static electricity, and blots on the workpiece. In this study, we experimentally and theoretically investigated the effect of supply flow rate on the performance of the vortex gripper. First, we proposed three performance indexes for evaluating the properties of the vortex gripper: the maximum force, suspension region, and suspension stiffness. Then, we obtained a series of F–h (i.e., the suction force against the spacing between the gripper and the workpiece) curves at different supply flow rates and the pressure distributions at the surface of the workpiece for different values of spacing h. Based on the experimental data, we analyzed the effect of the supply flow rate on the maximum force, and by nondimensionalization of the F–h curves, the changes in the suspension region were assessed. Furthermore, we proposed an additive method of pressure distribution and deduced a simplified theoretical formula for suspension stiffness. In addition, from the perspective of the suspension stability of the workpiece, we evaluated the physical significance of the slope of the F–h curves after nondimensionalization. The findings of this study could help researchers to comprehend the operation of the vortex gripper and provide guidance for implementing the vortex gripper in practical applications.