Pick and place with relay logics.

[davepre5]

I need to build a pick and place device using two pneumatic cylinders, one for the horisontal and one for the vertical movement. Vacuum will be used to pick up the plastic parts; typically 7.0 mm diameter x 1.6 mm thick. I also want to use normal limit switches at the end of each stroke, not magnetic reed switches.
Can some one help me with the design of a basic circuit please?
The device will be used as a good visual display of electrical and pneumatic utilisation.
Thanks,
Dave Pretorius.

 

[Arkham00]

Clarify

It's not clear what you have to do. I suppose it's about this sequence:

1. vertical up
2. horizontal right
3. vertical down
4. pick object with vacuum
5. vertical up
6. horizontal left
7. vertical down
8. release objet (stop vacuum)
9. end of sequence

So you just have two pusbuttons to control the system: one is called "reset to start position" and the other is "do picking sequence". Is this correct?
All this must be done with a relay logic?

 

[davepre5]

Pick and place.

Yes, you are correct, sorry for not givving all the details. Yes I would like to use relays only as I have no experience using a PLC.
The control circuit can be in any voltage. I will buy all the relays, timers etc. You just say what I need.

Thanks,

Dave Pretorius

 

[Arkham00]

It's non so easy ... a simple PLC with few I/O would be the best solution.

Anyway, here is I/O table:

Inputs
------
FU ........ up switch (pressed when arm is up)
FD ........ down switch
FL ........ left switch
FR ........ right switch
PR ........ reset pushbutton
PC ........ start-cycle pushbutton


Outputs
-------
VU ........ up valve (moves arm up)
VD ........ down valve (moves arm down)
VL ........ left valve (moves arm left)
VR ........ right valve (moves arm right)
VV ........ vacuum valve

Here are the movement statuses

              5
 <---------------------------
 |   ------------------->|  ^
 |   ^        2          |  |
 |   |                   |  |
6|   |1                 3|  |4
 |   |                   |  |
 v   |                   v  |
End                      Pick
    Start

Here is a starting poi for the program.
K1, K2, ... are relays, each one is a memory of a movement state

Movement (1)
   PC    FD    FC    K2
---| |---| |---| |-+-|/|------(K1)
                   |
   K1              |
---| |-------------+

Movement (2)
   FU                K3
---| |-------------+-|/|------(K2)
                   |
   K2              |
---| |-------------+

...

where -| |- in an NO contact, -|/|- is an NC contact

Hope this may be of help.

 

[davepre5]

Pick and place.

Hi Arkham00,
Thanks for the diagram, I will get a small PLC and give it a try. Will do some learning in programming a PLC.

Best Regards,

Dave Pretorius