Sequential release control for a zoned conveyor system

Abstract

An accumulating conveyor system for transporting a series of loads includes a series of conveyor zones, including at least an upstream conveyor zone and a downstream conveyor zone. Each conveyor zone includes a drive arrangement for operating the conveyor zone to advance loads therealong. A control is interconnected with each drive arrangement. The control is operable to sequentially initiate operation of adjacent conveyor zones by delaying initiation of operation of an upstream conveyor zone for a predetermined time period after initiation of operation of a downstream conveyor zone. In this manner, operation of a series of adjacent conveyor zones is initiated in a sequential or wave-type manner, which avoids thrust loading of the conveyor system and minimizes electrical surges which otherwise would occur if operation of all zones were initiated simultaneously. Each zone includes a sensor at its downstream end, and, when it is desired to stop operation of the conveyor zones to maintain loads stationary thereon, operation is suspended when the leading edge of each load reaches the downstream sensor of the conveyor zone. In this manner, the adjacent zones also stop operation in a sequential manner since the spacing between adjacent loads increases upon sequential release of the loads at start-up.