Ot Building a automatic pneumatic can crusher ideas.

I would like to try and build a aluminum can crusher with a small plc controlling it. I would like to be able to hold a wal-mart bag full of cans in the hooper and push start.

I have
-Siemens logo plc
-small control panel
-1/2 inch shaft 5 inch stroke cylinder with solinoid.
-2 1/8 bore 1.5 inch stroke cylinders with solinoid.

This is my idea.
Put the cans into hopper
They would fall till the get to small cylinder 2 at which time cylinder 1 would engage and hold the pile up. When the pile is held up cylinder 2 would release can into crush area. Cylinder 2 would engage and cylinder 1 would allow the next can down into the ready position. The crush area would be notch out so only a crushed can could make it to the trash barrel to be recycled.


|O O O O O |
| O O O O /
|O O O O /
| O O O /
|O O O /
| O O /
|O O /
| O |----SMALL CYLINDER 1
| O |----SMALL CYLINDER 2
| O |----LARGE CRUSHING CYLINDER
----- this would be cut so that only crushed can will fall through.

TRASH CAN BELOW TO CAUGHT CANS.


What should i build this out of? This is a home project so something inexpensive would be great.
Do you see any problems with this design.

Sorting of the cans would be required in this application as they will need to be positioned correctly at cyl.3. This will also require that the opening be opened when cyl. 3 is retracted after a can is crushed and close when the next can is feed.

Cyl.1 & 2 will need to be fitted with an appropriate end deflector to avoid spearing of the cans.

The system could be built out of a number of materials as long as the crush area is well re-enforced.

The wooden hopper i am thinking about would be as wide as the cans with a little extra room. The hopper would be placed directly above the crush area which would be built out of metal. The small cylinder would have a rubber end so prevent the spearing. The big cylinder would have a plate a little bigger then a can attached to it.

Thanks for any help

For US$13, you might want to buy one of THESE to use as the hopper (and maybe other parts)... :nodi:



-Eric

I had one of the can crushers in the past. It work good but is very poor quality. Cheap plastic which broke in a very short time. I might try and build that same design with wood opr metal. I would like to be able to put 1 walmart bag of cans in the machine at a time.(15-25) I would like to make this as automatic as possible. This is something i found on the internet http://www.designnews.com/article/CA6328350.html I like how it operates but not enough hopper capacity

thanks

Personally would probably make a big compactor so you could crush plastic, paper, etc. too. My concept would probably need hydraulics because I would crush the cans all at once.

The hard part about crushing one can at a time, as mentioned, would be making sure the cans fall correctly.

I have been thinking about building one just so I could recycle some of my trash instead of sending it to a landfill. With a family of 7 we generate more waste then we can put into the one (1) garbage can we are allowed.

2004sk4,

Is the list in your first post all that you have to work with? If so then you will have a hard time getting the job done with your "crusher" cylinder. The size of your cylinder is too small to crush the cans in one cycle. Will you be orienting the cans like either of the links are doing, or are you planning on dumping out the "Wallmart bag" into the hopper? How will you handle the "off sized" cans like energy drinks? How will you handle any partialy flattened cans?

If you are married to the exsiting crusher cylinder, I think you should consider crushing in cycles. Perhaps something with a wedge shaped chamber that has a hinge on the bottom.


This would multiply the force of the cylinder by using the moving side as a lever and fulcrum against the can. when you retract the can would drop lower into the cavity and you would cycle again. To eject the crushed can you would need a wedge shaped pusher to push the crushed can out sideways.

Edit,
I see Ron has posted with a good suggestion. I would like to add a twist to what Ron said. That twist would be to use truck suspension air bags instead of hydraulics. The truck style bags are easy to obtain and tend to be lower priced than the industrial ones. This is presuming you already have an air compressor and don't have any hydraulics at home. The tricky thing about air bags is to not let them over extend and to get them to retract.

If you search for "can crusher" on YouTube, there are quite a few different ideas. Some are a bit odd...



-Eric

I watched the videos on youtube. Some of them are very interesting. What size air cylinder would i need to crush a can with one cycle. I have a 80 gal two stage 135 psi compressor to feed it with. I like Mildrone's idea but would like to build something that crushes in one shot.

thanks

That would be the first thing to detemine i.e. how much force would be needed to crush a can. I assume all cans would be 12oz sodas? These are approximately 5" in height so I would add an inch for accleration.

Using an air cylinder the formula for area in sq. in. is (pi*diameter^2)/4

Force = Pressure * Net area in sq. in.

We know the approximate stroke will be 6" so a 2" bore would give you 3 sq. in. of area. 120 (PSI) * 3 = 360 in lbs of force. Or 360/12 = 30 foot lbs.

Since I do not know the exact amount of force needed I just provided this to get you started. Since it is possible to stroke several times a minute in some cases you may get away with 2-3 strokes to crush the can before ejecting and new can is inserted. If you used a 4 inch bore the force would quadruple.

2004sk4,

I believe if the force is evenly distributed and the can is not dented in any fashion then some where arround 500 lbs is needed. If the can is pre dented and the force is concentrated on one edge of the circular face as little as 150 lbs will work. the key to this is getting the un equall end force on the circular face to line up with the dent in the side of the can. Not a very good explanation but thats the only thing I can come up with, even with caffene irrigation.

The other day I saw a home-made can crusher that was about as 'redneck' as you could get, but it worked, and worked well! It was an electric motor attached to a gearbox similar to what may be in a riding lawn mower rear axle.

On each of the two shafts where the wheels would normally be was a short piece of iron with a 'connecting rod' going to a horizontal 'piston'. So when the machine ran, it was similar to the operation of an internal combustion engine with one 'piston' compressing as one was retracting.

The pistons were simply a smaller pipe, capped off on one end, sliding inside of a larger pipe. The top of the outer pipe was cut off on one end large enough to drop in a can, with a slot in the bottom large enough for only a compressed can to drop through.

As I said, this was a really cobbled together machine, which could have used some safety improvements. For example I would definately have added a hopper of some sort since dropping the cans into the piston area could produce a smashed finger at a minimum very easily. Also, I would suggest a spring either in the connecting rod or at the compression end so as to eliminate 'bottoming out' and bending or breaking something.

But it worked well! This old guy could crush a can every second or so as long as he could keep up with putting the cans in.

Now that some of the caffene has circulated and partialy discharged. I see that I need to clarify my numbers.

The numbers I quoted are right but there is no adjustment in the numbers for speed. To get the speed numbers that I have seen mentioned in this thread (1 can a second). We need to multiply them by 180 %. So for an undented can with evenly distributed force on the circular end 900 lbs of eventual theoretical force (area X psi) is needed. This is because the build up of pressure in an air cylinder rises very fast untill a pressure of 58 psi (gauge) then the process slows down.

Why not two short inward turning textured conveyors with a narrowing gap?

How many six packs per second was our goal?

OkiePC,

Excellent concept!