Optimization of outer diameter of Bernoulli gripper

• We measure the pressure distribution and suction force of Bernoulli gripper.
• We model the radial flow with consideration of the inertia and viscous effects.
• We propose a method for determining the optimal outer diameter.
• The optimal outer diameter varies markedly as the supply flow rate is changed.

A Bernoulli gripper is a pneumatic manipulator, capable of sucking and gripping. It is widely employed in automated production lines. It uses an axisymmetric radial airflow to create negative pressure that produces suction force. In this study, an important design parameter, namely, the outer diameter, is addressed both theoretically and experimentally. First, a theoretical model of the air flow between the gripper and the workpiece is created, based on which the theoretical formulas for calculating the pressure distribution and suction force are derived. It is found that the outer diameter of the gripper has a major impact on the suction force, and its design is closely related to the gap height and the supply mass flow rate. Then, the relationship between the outer diameter and the suction force and that between the gap height and the suction force are discussed, based on which a method for finding the optimal outer diameter is presented. Meanwhile, the pressure distribution is investigated in an attempt to explain the impact of the variation in the outer diameter on the flow phenomenon. Finally, the values of the optimal outer diameter for a range of supply mass flow rates are calculated and the tendency of the optimal outer diameter to change with the supply mass flow rate is revealed, which is of great importance to the design of a Bernoulli gripper.