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Non Accumulating Conveyor Blocking Itself

Solution Partner Valued Contributor Solution Partner Valued Contributor
Solution Partner Valued Contributor

Good day

 

I am busy trying to figure out the reason for the following: (Model attached)

 

  • There is a closed-loop non accumulating conveyor belt with different colour entities arriving at Negexp 0:27.6. 
  • When the colour reaches its matching station it is offloaded only if there is capacity. If there is no capacity the part simply loops around and tries again.
  • The conveyor has a capacity of 8

With the initial simulation the following occurs:

As the one part tries to access the conveyor it causes a grid-lock.(Conveyor Blocking itself)

conveyorpic1.PNG

 

If the simulation is run with Accumulating active the following occurs: (Basically the conveyor blocks itself)

conveyorpic-accumulating.PNG

 

 

If for example I add a "Loading Line" then the same gridlock occurs:

conveyorpicLoadingLine.PNG

 

Any suggestions of how to get around these issues?

 

Regards,

H

3 REPLIES

Re: Non Accumulating Conveyor Blocking Itself

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello

 

non accumulating: the conveyor stops when one part on it stops. So the blocking situation happens when during the entrance of a MU another MU at the end of the conveyor will enter the conveyor at the begin again. Because the entrance is not free this MU will be stopped and also the complete conveyor. You should allow a new MU to enter the conveyor only when it can completly enter the conveyor before a MU reaches the end of the conveyor.

 

capacity: all MU-parts were counted for check of capacity. When 8 parts are on the conveyor the part at the end cannot enter the conveyor at the begin because then there were 9 MU-parts on it.

 

Regards

Karola

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Re: Non Accumulating Conveyor Blocking Itself

Solution Partner Valued Contributor Solution Partner Valued Contributor
Solution Partner Valued Contributor

Hi Karola

 

Thank you for the reply.

I understand what is causing the blockage; I'm just not sure how to get around it exactly.

For example. See below the following case:

  1. Non accumulating conveyor (capacity = 5)
  2. source creates 5 entities only
  3. once the entities reach the end of the line they cannot continue in a continuous loop  (Like a baggage conveyor at the airport) They are blocked because the Line's capacity has been reached and cannot accept new MUs, even from itself

ConvEx.PNG

 

Any ideas of how to get around this?

 

Regards,

H

Re: Non Accumulating Conveyor Blocking Itself

Solution Partner Creator Solution Partner Creator
Solution Partner Creator

Hi Hermias

 

There is an easy fix to get past this problem. Draw a small extra part of the conveyor and connect this between the end and beginning part of your big conveyor:

 

 Capture.JPG

 

In your source create a front exit control:

 

Capture1.JPG

 

This will ensure that no two parts would want to occupy the same space and your conveyor wont get blocked.

 

Regards

 

Chrisni