Continuous Control for Buffering Conveyors in Beverage Bottling Plants

In beverage bottling plants, buffering conveying systems are used to decouple the various machines. They avoid propagation of machine breakdowns along the plant by assimilating or releasing bottles or containers. Today, they are controlled in steps by mechanical jam switches. In many cases, they enable an enduring filling process, which is necessary to gain good product quality and high plant efficiency. But with longer faults, the filling process still has to stop or slow down. Additionally, today's conveyors run very noisy. This affects the operator's health and conflicts with legal regulations. This paper presents an alternative control approach for buffering conveyors. It was created to improve the buffering effect and to reduce the noise emissions of today's systems. Instead of using jam switches, it uses counting sensor systems to obtain stepless information on the bottles entering and leaving the buffering conveyor. On this basis, the first continuous control algorithm for buffering conveyors was developed. It was described mathematically for all possible buffer situations. It was programmed and implemented in an industrial scale pilot plant. Finally, experiments in comparison with the commonly used jam switch control were carried out for all relevant settings. The practical experiments showed a stable behaviour of the new control algorithm. It reacted appropriately to state changes. Readjustment times and an almost minimal dead time (shortest transportation time of bottles) proved a high buffering effect. Above all, the new control algorithm resulted in a clearly audible and measureable reduction of the noise level. Copyright © 2012 John Wiley & Sons, Ltd.