Mattison

product gaping on 3 conveyors

6 posts in this topic

Hi,

been given the task of gaping dough pieces over 3 conveyors to reduce/correct the error in position

I will know the rate a which the dough pieces 'should' be coming at me (7000 per hour) so around 0.5 seconds between dough pieces

I plan to use power-flex 525 drives over Ethernet in studio 5000

my thoughts would be to have a photocell timing falling edge to falling edge of product and then working out a % to increase or decrease speed of the next conveyor.

not 100% on how i would do it to achieve an accurate result. the 3 conveyors are spanning a gap of 1 meter so need to work out whether these need to be equal in length or not.

and ideas that would a better solution or any sample code for something similar would be great.

Thanks

Ben

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Mattison, not to throw ice water on what you're doing, because it has been done, but it's not easy.

First you will only change gap when more than 1/2 the dough piece is on the faster/slower conveyor.

Second if you try to change the gap too much you'll stretch or bunch the dough, also not a good idea I would think.

For what I discuss following I'm assuming Conveyor A feeds Conveyor B feeds Conveyor C.

Conveyor A runs a constant speed and has two sensors.  Sensor 1 is in the middle of Conveyor A and measures Window Size {Lead Edge to Lead Edge},  Dough Piece Size {Lead Edge to Trail Edge} and Gap Size {Trail Edge to Lead  Edge}. I'd measure the sizes in mm and not seconds.

Obviously you'll have an ideal condition where all three require no change. 

You'll have a condition where the dough piece is fine, but the gap is too small or too large.

This will be what you use to calculate your adjust.

The second sensor at the outfeed of Conveyor A will determine when you want to ramp up or ramp down Conveyor B.

If you've measure distance (mm) and not time, then you can run a confirming set of measurements on Conveyor B with it's sensor 1 and if needed repeat the process going onto C.

You'll also need to handle the case where the Dough Piece is oversize or undersized.

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In my experience, the divider drops 4 dough pieces at once onto a conveyor that is mechanically geared to the stroke rate of the divider. Are you trying to change the gaps between each of the 4? or between groups of 4? Again, from my experience, the dough pieces drop off the divider's conveyor onto a slightly faster conveyor feeding the hander/rounder. Don't understand how the gap is critical.

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2 hours ago, Gerry said:

In my experience, the divider drops 4 dough pieces at once onto a conveyor that is mechanically geared to the stroke rate of the divider. Are you trying to change the gaps between each of the 4? or between groups of 4? Again, from my experience, the dough pieces drop off the divider's conveyor onto a slightly faster conveyor feeding the hander/rounder. Don't understand how the gap is critical.

Yes, you are correct. we drop 4 pieces back to back then pull a gap on the next conveyor into the conical rounder. i think what is happening is the dough pieces are getting stuck in the rounder and then end up in two pockets of the 1st prover.

 

the 3 'smart' conveyors are directly after the rounder feeding the prover.

its an old plant and the customer with it may be a cheaper fix than replacing the actual problem. usual customer is always right...... 

Edited by Mattison

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I guess you mean 2 doughs in 1 pocket??

In the plants I've worked on, there wouldn't be room for 3 conveyors between the rounder and 1st prover. And I don't think the bucket loader was ever intended to operate at 7000/hr. I'm assuming this is a Baker-Perkins/APV plant, with the buckets indexing with a clutch/brake system. Here they used a capacitive prox to sense the dough piece and trigger the clutch. As the rate increases, PLC scan time, I/O response time, and prox switching time all become issues - not to mention the clutch/brake - due to their innate variations becoming more significant relative to the dough rate. I don't think those loaders ever perform 100%.

 

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4 hours ago, Gerry said:

I guess you mean 2 doughs in 1 pocket??

In the plants I've worked on, there wouldn't be room for 3 conveyors between the rounder and 1st prover. And I don't think the bucket loader was ever intended to operate at 7000/hr. I'm assuming this is a Baker-Perkins/APV plant, with the buckets indexing with a clutch/brake system. Here they used a capacitive prox to sense the dough piece and trigger the clutch. As the rate increases, PLC scan time, I/O response time, and prox switching time all become issues - not to mention the clutch/brake - due to their innate variations becoming more significant relative to the dough rate. I don't think those loaders ever perform 100%.

 

it is APV. 

its the old pusher type rather than bucket feed. the pusher doesn't push relative to where the dough piece is. purely on a pulse every swing of the prover.

it didnt help when i went to site to look at it the divider was running faster than the prover, so more dough pieces than the prover could handle. was never going to work. few tweeks sorted this out. 

 

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