Re: [CAD_CAM_EDM_DRO] Sorting Steel Balls

Ethan wrote:

> Good morning.
>
> I'm looking for some ideas on how to sort some steel balls. I need to do
> about 4,000 per day. Sizes range from 19/32 to 7/8 with some sizes being
> within .001 from each other.
>
> I'd like to use a PC or PLC based machine that will measure the balls and
> them sort them according to size.

The most obvious method is a tilted track with graded holes in it, the
smaller ones first. You could have a mechanism that holds a track with
20 holes in it, and tubes below that go to 20 different bins. The balls that are
too large for any hole wind up in a reject bin, where all balls are larger than
any hole in your track. You then run these through again after switching
to the next larger track. It will take a little fooling around to find the right
slope, spacing of holes, etc. One thing that comes to mind is to have
wire rails that don't allow the balls to drop into the holes unless they are
very close to being able to fit through the holes. You might need a 'wiper'
to bump the balls out of the holes that they almost can fit through. A
wheel with spokes, kind of like a water wheel could be used to control
the flow of balls into the sorter.

Another method could use bars made of hardened and ground shaft, with
the balls rolling down an incline, and the shafts slightly farther apart at
the downstream end. You might be able to sort a fairly large range of ball
sizes with a few feet of this. Maybe a 1" square funnel leading to a container
for each size, and the rails spreading apart at the rate of .001" per inch.
I see you want 281 different sizes. That would be 23 feet long to do it all
in one pass. But, it would only be 6 feet long to do in 4 passes.

A commercial method I've heard of used a resilient board of some sort, and
the balls were dropped from a calibrated height. They bounced to a different
height depending on size, and fell into troughs based on size. I think this was
in a line where balls were all within a few thousandths of the same size.

I can't see how a PLC or PC would do anything but increase cost (VASTLY)
and slow the process down.

Jon