Mike Mayer avatar image
Mike Mayer asked Felix Möhlmann answered

Keep fixed conveyors from stopping/starting as flowitems leave/enter the sides?

Accumulating conveyors (like free gravity rollers) are nice because if a flowitem departs from, or arrives onto, the conveyor (like left or right either to/from another conveyor at a Tee junction, or to/from an Exit/Entry Transfer to/from a sink or processor or something), the accumulating conveyor will continue moving. Regardless of flowitems coming on/off of it.

A fixed (non-accumulating, like a rubber belt) conveyor however, pauses briefly as each flow item transitions on/off from the side. For a long fixed conveyor with lots of side entries/exits, and lots of things coming on/off from the sides, the conveyor tends to stutter from it stopping and starting so much. I suspect the reason is that it keeps items from "skidding" onto or off of the fixed belt, thus it must pause to allow the entry/departure to happen correctly (which does not happen with accumulating conveyors).

So, is there a way I can tell a fixed conveyor to keep moving regardless of what's coming on/off from the sides? Of course, all conveyors must stop if it cannot push a tire off the end - so that's not the issue.

I guess what I'm looking for is a hybrid conveyor that keeps moving, but does not accumulate.


FlexSim 21.1.4
flexsim 21.1.4stopstartnon accumulating conveyor
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1 Answer

Felix Möhlmann avatar image
Felix Möhlmann answered

You could use an accumulating conveyor and manually stop it, if an item arrives at the end and the exit is not free by using a Photo Eye or Decision Point.

Depending on how complex your conveyor system is, this might be quite a bit of work though.


Note: The "On Message" trigger of the Photo Eye doesn't normally support the "Set Conveyor Speed" option as it does not contain a reference to the conveyor. I simply copied the code from the "On Cover" trigger and get the reference to the conveyor with

Conveyor conveyor = ownerobject(current.find(">variables/conveyorPoint/1+"));

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Mike Mayer avatar image Mike Mayer commented ·
Thank you for your clever example Felix. The effect is that of a belt conveyor that allows flowitems to "slide" onto the belt from the side, yet not cause the belt to briefly stop (because it's still an accumulating conveyor). In most of our models, we have a long main "spine" conveyor with lots of side entrys/exits, and there are not too many of these big "spine" units, so implementing such an end-stopper via photo eye and message, may just be what we need. - Mike
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