APPLICATIONS OVERVIEW 21 22 APPLICATIONS OVERVIEW
Figures 10 and 11 show an application where fork lift trucks are used to place and remove palletised loads from the infeed or outfeed conveyor manufacturer of a potentially dangerous machine. The application shows light curtains operating in conjunction with a control system and strategically positioned under-floor inductive loops, that enable continuous but industrial safe operation of the machinery even during periods when a fork lift truck is loading or unloading the pallet loads in close proximity. Figure 11 Figure 10 Figure 10 shows a hazardous machine surrounded by fixed fences. The open area across the conveyor is safeguarded with two light curtains that operate in a specific sequence. When light curtain 2 is active, or ON then light curtain 1 is muted e.g. the electrical outputs from light curtain 1 do not respond to an interruption of its detection field. When light curtain 2 is muted then light curtain 1 is automatically switched ON. Light curtain 2 is automatically muted with signals derived from the underfloor inductive loops. These signals ‘mute’ light curtain 2 when the metal mass of the fork lift truck is positioned above the loops. When the fork lift truck moves away from the loops the muting signals are removed and light curtain 2 once again becomes active at the same time deactivating or muting light curtain 1. It can be seen that there is always one of the light curtains in an active, ON condition, thus preventing personnel access to the machinery at all times but, industrial still allowing continuous machine operation. Figure 11 shows another packaging machine application using control functionality similar to the system previously described. However, in this case two fork lift truck load / unload stations are installed, each safeguarded with a light curtain and an inductive loop control muting system. 8000 SERIES8000 SERIES