Conveyor accumulation

I have a conveyor with 6 stops and PE's in front and back of each stop. Normally cartons cross in front of all this one at a time, about 5 seconds apart. If our packer gets shut down, we want the cartons to back up to 8 cartons, then have stop 1 extend, as the next set of 8 cartons backs up, extend stop 2, ect. But when the packer is ready, I want the first stop to release its 8 carton load to the packer, then when it's clear, release stop 2 and not crush a carton as it passes stop 1, same for the other stops as it unloads.

My thoughts were using the entry and exit PE's of each stop as a condition of a timer where the first PE has to be clear for an amount of time (based on conveyor speed) before allowing the stop to extend, *clear*. The exit PE on a timer to extend the stop if it is *clear* and is blocked for a time (full), meaning the section is full of 8 cartons.

The tricky part is when an 8 carton section is released, and blocks the exit PE of the next section, will it not extend because of the *clear*, and will it close when it is past the *clear*.

I think this will work, but then I'm not good at this stuff. Thoughts?

Thanks for helping!

I'm not sure that I understand, but I am doubtful that a simple timer and a bit of combinational logic will do what you need without messing up normal operation.

If it were my system, I'd set a 'staging' bit when the packer is down and have logic execute only then, do extend stop 1, then 2, then 3, etc. The 'staging' bit would disable your normal logic so they don't conflict

When the packer is up again, the logic to reverse the staging could use a timer to clear the cartons before the next block is released. When all is de-staged, clear the 'staging' bit and let your system go back to normal.

How do you keep the cartons from running into each other on the main conveyor? Do all 8 cartons run into each other while stop 1 is extended?

I'm also not clear on how the cartons are separated (a gap is pulled between them) when they are de-staged

Or I could be seeing things completely wrong .. and maybe a sketch would help.

Could you do a cascading release? In other words release box group 1 and wait until the "Box group 1 " eye is clear for X amount of time? Then Box group 2 so on and so forth?

As far as them entering if you know the FPM of the conveyor then you could time off of the clear eye to send the stop up.

Hopefully this helped I am not sure if I am imagining this correctly .

thingstodo said:

I'm not sure that I understand, but I am doubtful that a simple timer and a bit of combinational logic will do what you need without messing up normal operation.

If it were my system, I'd set a 'staging' bit when the packer is down and have logic execute only then, do extend stop 1, then 2, then 3, etc. The 'staging' bit would disable your normal logic so they don't conflict

When the packer is up again, the logic to reverse the staging could use a timer to clear the cartons before the next block is released. When all is de-staged, clear the 'staging' bit and let your system go back to normal.

How do you keep the cartons from running into each other on the main conveyor? Do all 8 cartons run into each other while stop 1 is extended?

I'm also not clear on how the cartons are separated (a gap is pulled between them) when they are de-staged

Or I could be seeing things completely wrong .. and maybe a sketch would help.

Click to expand...

The conveyor is a two part. First is slow running so cartons usually stack up close to each other, the second is slightly faster so there is a gap of a few feet between them. When the packer is down, the stop will come out and allow 8 cartons to stack up behind it, when that "area" is full, the next stop extends and allows another 8 cartons, and on to stop 6. If cartons before stop 1 empty out, stop 1 will open, when cartons at stop 1 are emptied out, stop 2 opens. So there is also the slow conveyor may or may not have cartons on it, so if it is empty, I want to keep it running till a carton shows up in front of the 6th stop. In front of the 6th stop, we can have only a maximum of 8 cartons, so that is when we stop the slow conveyor if it shows a carton at the end of it.

I think I have the logic worked out, and I'll find out soon enough as we're going to run it soon!

you mentioned an accumulation conveyor.
is this a motorized conveyor with a motor at each stop or a clutch type accumulation conveyor?
please explain the conveyor in more detail.
james

James Mcquade said:

you mentioned an accumulation conveyor.
is this a motorized conveyor with a motor at each stop or a clutch type accumulation conveyor?
please explain the conveyor in more detail.
james

Click to expand...

Two regular VFD controlled conveyors. First is slow running, transfers cartons onto the second faster running conveyor.

It looks like it's working so far. We set up a PE at the transfer to stop the cartons by stopping the first conveyor when the last stop is activated. This allows a few cartons to stack up behind that stop, as it is a few feet away from the transfer from one conveyor to the other.

I thought we could count cartons going by, but if the stop is extended and releases, I would loose the count. Unless...