Scrap reduction at end of machine clean out process

[ziyaddin2015]

Hi All,
I was assigned a project to help to reduce cup scrap during a clean out process. The cups travel on four conveyors prior entering robot area and we have a diverter setup that diverts cups onto these four conveyors. We don’t have it where even amount of cups entering these conveyor which then all that product ends up in the scrap bin. I want to control how many cups entering these conveyors but not sure how I can achieve this. As of now it’s setup to work based of timers not counters? How can I allow only let say 50 cups to enter conveyor at a time? Do I need to instal add additional sensors if so what type? We have a few photo eyes that look for product jam and can I use same sensors to count cups entering the conveyor? Do I need to instal add additional sensors if so what type?
Thank you in advance.
RSlogix5000
Panel view 1000
AB PLC

 

[cjd1965]

so 4 conveyors feed onto a single conveyor?

Consider creating a zone that when empty calls for a single feed conveyor to push cups to the single conveyor. This could be some prox switches or a camera to detect empty

Consider alternating the feed conveyor or perhaps run a conveyor until empty then move to next

Is hard to say based on what you stated

 

[parky]

From what your saying you have one conveyor diverting to four conveyors is that right ? then providing at least one of the sensors is in a position to count the cups and allow the diverter to change position then you would probably not need a sensor but it would be a good idea to have a separate sensor for the counting.
Also will one of the four conveyors be empty when the others have their 50 cups?
Do you need to stop the infeed conveyor if all four have their 50 cups without some kind of scaled diagram it would be difficult to work out what is needed.
Assumptions:
one conveyor feeding a diverter that diverts to four conveyors to feed the robot. for example how does the diverter work is it divert to conv.1 then to 2 then to 3 then to 4 and then back to 1 ? or does it go 1 to 4 then 4 to 1 in order, without some real information we cannot give you any real ideas.

 

[ziyaddin2015]

Cups on two conveyors are diverted to four different conveyors/lanes 1-2 and 3-4 using a diverter. The 1-2 & 3-4 lanes feed cups to two separate robots that load cup into the cartons. The diverter is the only area where I need to do some counting to distribute even number of cups into these lanes.

 

[drbitboy]

Simple algorithm:


i) Maintain acount of cups in each conveyor
i.a) Every time a robot takes a cup from a conveyor, subtract 1 from that conveyor's count
i.b) Every time diverter sends a cup to a conveyor, add 1 to that conveyor's count


ii) Divert next cup to conveyor with lowest count
ii.a) If all conveyors have the same count, divert next cup to lowest-numbered conveyor.

---[mov             ]-----
   [source         0]
   [dest    low_conv]

---[les                     ]---[mov             ]--
   [sourcea  count[low_conv]]   [source         1]
   [sourceb         count[1]]   [dest    low_conv]



---[les                     ]---[mov             ]--
   [sourcea  count[low_conv]]   [source         2]
   [sourceb         count[2]]   [dest    low_conv]


---[les                     ]---[mov             ]--
   [sourcea  count[low_conv]]   [source         3]
   [sourceb         count[3]]   [dest    low_conv]

I am not sure about the 1-2 vs. 3-4 notation, as I am assuming 1 and 2 and 3 and 4 are different lanes, but maybe you can adapt that algorithm as needed.


Caveats:

• What about startup? How to determine the number of cups in each lane when the PLC starts?
• Similar to startup, need a way for operator to reset counts e.g. stop conveyor upstream of diverter, send all cups to scrap, reset counters to 0.

 

[kamenges]

This is the part I don't understand:

Originally posted by ziyaddin2015:

We don’t have it where even amount of cups entering these conveyor which then all that product ends up in the scrap bin.

The title of the thread infers that you have more cups on the four conveyors than are needed for the order. So you finish the order and all the cups on the conveyors are scrapped because they aren't needed.

Fundamentally, it doesn't matter if Conv 1 has 50 cups and Conv 2 has 0 cups OR if Conv 1 and 2 both have 25 cups. In the end you have 50 too many cups. So, as I see it, you really aren't concerned about all the conveyors having the same number of cups. You are worried about the total number of cups on the four conveyors being more than what you need.

Keith

 

[drbitboy]

This is the part I don't understand:

yeah, I may be completely misunderstanding the issue.

 

[ziyaddin2015]

yeah, I may be completely misunderstanding the issue.

Please see attachment below.

 

[drbitboy]

Is it a problem if Robot 1 gets two cups (Lanes 1-2) at the same time Robot 2 get zero cups (lanes 3-4)?

 

[parky]

Even more info is required:
1. How many cups can be on each conveyor feeding the robot.
2. What tells the robot there are cups ready to be picked up
3. What is the signal the robot gets to say there are cups ready to be picked.
4. is 3 part of the robot i.e. a sensor to say a cup is ready to be picked and is this part of the robot or a signal from the feed system.
and probably many more without actually seeing it in action it is difficult to understand a video of it working would be more helpful.
One thing that stands out is if two cups have to be in place then two sensors on each lane so that the signal to pick would only occur when at least two cups are in place. this seems like a simple solution but without knowing how it all works it's a guess.

 

[ziyaddin2015]

We have two optic sensors on each robot one per lane which signals to the robot that it’s ready to be picked up. Robot 1 conveyors each can hold 50 cups and other two 80 cups per lane on Robot 2. I will attach a video this Friday. In the instance where robot 1 left side conveyor might get 50 cups while right side only 10 then other 40 ends up in the scrap bin. Thank you

 

[cjd1965]

dont you simply need a signal to the robot that both lanes are ready

 

[Nova5]

How cleanly do the cups come through? reasonably spaced, or in close packed groups?

 

[drbitboy]

We have two optic sensors on each robot one per lane which signals to the robot that it’s ready to be picked up. Robot 1 conveyors each can hold 50 cups and other two 80 cups per lane on Robot 2. I will attach a video this Friday. In the instance where robot 1 left side conveyor might get 50 cups while right side only 10 then other 40 ends up in the scrap bin. Thank you

When it detects only one cup, can the robot rotate it's pickup gubbinzes 180 degrees and put the single cup into the empty lane and start over?



Of course, if there is only one cup, it could do that for a while.


Better to keep the lanes even, perhaps, but with this approach you could charge money for the folks on this list to watch the video; even more if you inset the code in real time.

 

[ziyaddin2015]

The robots will continue pick and place even with a single cup in lane to empty out the conveyor but those single picked cups will go to reject bin. The cups are reasonably spaced as they travel on the conveyor the sensor light beam makes through no problem.