Vibratory Feeding

Abstract

Feeding parts, initially oriented randomly, to a manipulator is one of the most commonly found operations in automatic production lines. This is indeed not an easy task as the work-heads are always required to be fed with parts in a specific orientation. To appreciate this, imagine the situation where screws are to be conveyed to an automatic screw-driver. The screws are furnished in open boxes and therefore have no precise orientation. The automatic screw-driver can accept screws only with their heads up. Moreover the feeding of the screw driver has to be performed at high rates, typically a few parts per second. A feeding mechanism is then constructed to decrease the configuration entropy which characterizes the random orientations the parts can assume. This is a basic example of an off-equilibrium thermodynamical system in which energy is supplied in order to reduce the entropy. The feeding devices are usually composed of two distinct parts, the conveying device and the orienting mechanism. One common solution to the conveying problem is provided by vibratory feeders. These machines belong to the level 3 of the general architecture of systems described in the last section (Figure 1.1). Basically, a vibratory feeder consists of an oscillating track on which the parts are conveyed. When the track is set vibrating, the mobile lying on it, is itself set into motion. For properly tuned vibrations, a stationary flux of parts traveling along the track is established. At the end of the track, the system is equipped with orienting and selecting devices.