Development of a Pneumatic Sucker for Gripping Workpieces With Rough Surface

In this study, we developed a new pneumatic sucker for handling workpieces with rough surfaces. We blow jet flow into a cylindrical cavity via tangential nozzles to form a rotating air flow that generates a cupped negative pressure distribution and creates suction force. Subsequently, air is exhausted through an annular gap passage at the bottom of the sucker. The cupped pressure distribution and exhausting air flow, which can inhibit the effect of air leakage caused by the rough surfaces of workpieces, are the key technical features that distinguish the new sucker from currently available pneumatic suckers. In this paper, we present the design and study the characteristics of the new sucker via experiments that measure the suction force and pressure distribution. The results reveal that the height of the annular gap passage is a key design parameter that affects the negative pressure and suction force and that an optimal value for the height exists. In addition, we investigate the influence of the roughness of the workpiece surface. The observed pressure distributions suggest that rough surfaces slow down the rotating air flow such that the suction force decreases as the roughness of the workpiece surface increases, which, however, only causes a small extent of decline in the suction force. Furthermore, we compare the new sucker with two existing suckers: a traditional rubber sucker and a Bernoulli sucker. The comparison reveals that the new sucker is superior in handling rough workpieces and saving energy. Finally, we use the new sucker to pick up several types of workpieces to confirm its applicability. This research of developing a new pneumatic sucker was motivated by the problem of gripping of workpieces with rough surface. Traditional rubber suckers are invalid due to the air leakage caused by the rough surfaces of workpieces, and the existing Bernoulli sucker has the shortcoming of consuming a large amount of air. In this paper, we propose a pneumatic sucker forming rotating air flow in an upside-down cup-like cavity to generate suction force. We present the design and investigate a key design parameter (i.e., the height of the gap passage) via experiments. It is found that an optimal value for the height exists, and it is independent of the air consumption and roughness of workpieces. We then verify the merit in gripping rough-surface workpieces and saving air consumption via comparison with a rubber sucker and a Bernoulli sucker. At the end of the paper, we use the new sucker to pick up several types of workpieces to confirm its applicability. These examples show that the new sucker could replace manual work to complete sorting and packing operations and play an important role in fully automatic production lines.