building a wire cutter...

[Charlie's68]

Ok, so in my manufacturing process class for mechanical engineering today, the prof asked two groups, one being mine to make a device that will unspool 20 gauge galvanized steel wire....cut it at either a) 6" lengths, b) 2.5" lengths, or advanced c) variable lengths of >14" lenths. The spool drive will be either mechancial or electric, but that part isn't as important as the cutting/measuring part. Any ideas?

We have a full machine shop to make this in, all the steel and aluminum stock we need, but no actual motors, or pneumatics to play with. I have thought of some complex designs, but being as there will only be 4 of us working on this, with 4 labs to complete it, i need some basic, simple ideas. It needs to also repeat the cut, say 3 6" cuts, then say you can move something, then make a few 2.5" cuts, so on so forth.

[russlaferrera]

The cutting part ... a of bolt cutter head operated by a solenoid. You need a clamping devise to pull the wire...jaws with a solenoid. The length... an adjusting screw with micro switches to stop the motor at the adjusted length.

Hope it helps start you on a good path. This is above me. I am still looking for the missing sock in the washing machine kind of guy.

[rsanter]

how about pulling the wire through 2 rollers, one on top the other on the bottom.
one roller will turn a gear, if you choose the gear ratio right then you cna get a cam to actuate a cutter that will always cut it at the set interval

bob

[Franz©]

You've been suckered by an evil professor. He only gave you part of the information on the wire you'll be cutting. Hard -v- soft wire require different aproaches. Hard wire will either need straightening first, or need to be clamped to hold an exact length.

KISS
Downsize a Greenlee wire pusher electricians use to feed the wire, don't forget to add a spool brake to control backlash. OR, grab a wire drive mechanism from a MIG welder.

Feed the wire thru a 2 plate cutter like a wireshear, and employ either a large solonoid or a pneumatic cylinder to operate the cutter.

Length, simple rod holding a microswitch and paddle on a slider sets length. End of wire hits switch, and stops wire drive. X time after drive stops, cutter cycles one cycle. Machine lackey removes cut wire, machine cycles again.

No need to reinvent anything, and most of what you need is off the shelf product.

[Jononon]

Length, simple rod holding a microswitch and paddle on a slider sets length. End of wire hits switch, and stops wire drive. X time after drive stops, cutter cycles one cycle. Machine lackey removes cut wire, machine cycles again.

If you've already got timing set up, it would be simple to have a solenoid operated 'kicker' that knocks the wire into a basket prior to the next cycle. No machine lackey's then needed until the receiver is full, and nobody's fingers have to go near the cutting component. In my experience, manufacturing engineering lecturers are impressed by prototypes that are fast and involve minimum human input.

If there are any points for additional paper prototypes (and you'd need an electrical engineer to do the hard bits of this one for you ;) ) an alternative method to measure the wire would be to use a two wheel wire drive and a stepper motor. A 1.8D stepper on a 1" drive wheel would measure (ignoring wire stretch, backlash, etc.) to 16/1000ths of an inch.

If you don't have a MIG welder you can open up, there's a clear picture of a two wheel wire drive here (http://www.millerwelds.com/about/news_releases/2007/images/MM252_212SideOpenLoaded.jpg)

[Charlie's68]

well i had a general idea last night before i posted this, i should have just posted my idea and seen if anyone could give some hints to make it better.

i think i am gonna use a wheel, and so the wire will feed through a shaft, onto a wheel, that has blades, and as the wheel rotates it will shear the wire, and run a pully off that wheel, and a pulley and belt of the drive wheel, and we have a simple but effective cutter. Hopefully work just like a shear.

[kbs2244]

Different dia wheels will give you different cut lengths

[Kevin54]

Ok, so in my manufacturing process class for mechanical engineering today, the prof asked two groups, one being mine to make a device that will unspool 20 gauge galvanized steel wire....cut it at either a) 6" lengths, b) 2.5" lengths, or advanced c) variable lengths of >14" lenths. The spool drive will be either mechancial or electric, but that part isn't as important as the cutting/measuring part. Any ideas?

How complex or simple it is would depends on what kinds of quantities you are theoretically looking at. Then is the wire allowed to be pinched on the ends or would it have to be a square cut? For example...and it is just a basic rough figure and idea, take two pulleys (not considering wire size at the moment) the bottom pulley being .796 diameter with one single v-notch cut into it. The top pulley being 3.184 diameter with 4 v-cutters inserted at every 90 degrees. Timed out, when these rotate together it would cut the wire length at 2.500. So for every revolution of the top pulley you get four wires cut. Just one idea without thinking too much on it. If you wanted something manual, I had one basically like that the other day that had a lever, a series of pins to trap the wire and a cam on it. The wire fed from the left thru a hole thry a set of double pins, you pull the lever to the right, the pins trapped the wire and held it, the lever went against a stop to the right length, and with another lever you came down and sheared the wire. This was held between two other pins, then the lever went back and grabbed the wire again. I'll see if I can sketch something up in a little while. Errands to run at the moment.

[sethbriancollins]

Different dia wheels will give you different cut lengths
hey,,, thats my idea

[Kevin54]

hey,,, thats my idea

My bad. I went back and reread the thread and man I feel stupid. What I said was almost exactly what you stated. I didn't mean to steal your idea, I just need to be a little more thorough in my reading. Sorry about that.

[kbs2244]

Peace be with you, my child.
All is forgiven.

[goodfellow]

Forget about building it -- just design it, and patent the design. Some Chinese company will steal the design, build it and sell it at Harbor Freight within three weeks.

Then just buy it for 19.99 and submit it as your work -- :beer: