Author Topic: Designing motherboard for PNP auto feeders?  (Read 1439 times)

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Offline shaiTopic starter

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Designing motherboard for PNP auto feeders?
« on: March 17, 2019, 07:33:05 pm »
I'm working on a pick and place machine and designing my own auto feeder. Still kinda new to EE, so this project is a great opportunity for me to advance my knowledge on circuit board design.

I've finished designing the feeder itself and now I need to design the "motherboard" that will control all ~30 feeders. The feeders work by (see attached pic) using an N20 motor to pull the cover off the tape and therefore advance it. The sprocket simply acts as an encoder. So four "pad clicks" by the springs, means it's moved 4mm pitch. The TWO springs on the back of the sprocket short themselves when touching a pad. (wether this is a good way to make an auto feeder is another topic). I am trying to understand, what's the best way to design the motherboard? I was going to use the Arduino Mega 2560 schematics and retrofit it onto this custom shaped board (attached pic) since I think using Arduino to write the code would be the easiest way to program this motherboard to communicate with OpenPNP software.


Basically I have one PWM powered mosfet that acts as the "GND" to 30 other mosfets (motors). Each of the feeder mosfets is opened/closed using GPIO pin since Arduino Mega 2560 only has a limited number of PWM pins, but many GPIO pins. All the individual feeders' encoders feed to one pin since they will never be used at the same time (one feeder at a time). The encoder will only turn one direction all the time since turning the reverse will not move the tape.

Is there a better way of doing this after looking at my description/pics? Suggestions?

Thanks!
 

Offline jmelson

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Re: Designing motherboard for PNP auto feeders?
« Reply #1 on: March 17, 2019, 08:18:46 pm »
A mechanical encoder?  No, I don't like that at all.  How many parts will be exposed when the cover tape is lifted?  Do you have a blade or cover to keep the parts from jumping out of the tape pockets?  This is a REAL problem in P&P, see comments in manufacturing forum section, where P&P has been discussed a lot.
My CSM84 feeders have no more than 5 parts uncovered, and the clamp covers 4 of them, and the retractable blade covers the most forward one until the nozzle is about to make the pickup.

Jon
« Last Edit: March 17, 2019, 08:22:50 pm by jmelson »
 

Offline shaiTopic starter

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Re: Designing motherboard for PNP auto feeders?
« Reply #2 on: March 18, 2019, 01:43:46 am »
Thanks, but as I mentioned, this post is not about the mechanics of it.
 

Offline ebclr

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Re: Designing motherboard for PNP auto feeders?
« Reply #3 on: March 18, 2019, 02:12:10 am »
Why not stepper motor ? it's  made for this
 


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