Resonance-Induced Failure of Entrapment: Application to Industrial Parts Feeding

Parts feeders are devices used in automated assembly lines to present component parts to the assembly machinery in a consistent and predetermined orientation. The process of converting a randomly oriented set of parts (as obtained from a vendor) into an ordered array is called parts feeding. There are many different types of feeders and feeding techniques used in the industry. This paper deals with a particular feeding process referred to here as vibratory entrapment. It describes a particular cause of failure of vibratory entrapment, namely, resonance. Failure due to resonance was first observed in high-speed video images of the entrapment phenomenon. This paper provides a description of the mechanics of failure of entrapment due to resonance. The mechanics is introduced with the simple example of a ping-pong ball in a cup and extended to real parts in a parts feeder. Conditions for resonance are derived and experimentally verified for a simple part shape and vibration pattern. KEY WORDS—parts feeder, entrapment resonance, vibration