Flywheels achieving linear motion

[mechanicalbrain]

I need a little help with an idea of mine. I want to take a flywheel (10 pound disk with 10" diameter) and apply all of its stored energy into a single linear movement of a rod. I guess not unlike how a camshaft causes a linear motion with the engine cylinders. I really want to put quite a bit of force into a single thrust, and I really need to be able to spin this up to full potential fairly quickly. I already know the Kinetic Energy = 1/2*I*rpm*rpm equation and I'm making I = 1*Mass*Radius*Radius with a conversion efficiency of 60% (I know optimum is 80% but this is homemade after all). I'm kind of looking for a good guide for making flywheel devices along with any advice people might have.

[gniticxe]

Hi,
It sounds like you may have a cool project behind this, I'll help where I can:

If you have a disc, and not mass on a ring, I = 1/2*M*R*R

I'm sure you know already, but Ek = 1/2*I*(rad/s)*(rad/s), instead of rpm

As far as a physical way to transfer the energy, how about using a commutated shaft and using an electro magnet to extend a piece of steel past the radius of the wheel (you'll need a spring to keep it from deploying early and also a balancing weight on the opposite side, depending on how large/fast this is). In less than a revolution, you'll have contact with the waiting rod.

Using an efficiency of 0.6 for energy transfer calculations is probably plenty conservative, especially since the disc may spin backwards after hitting the rod.

[KenWittlief]

my father use to work at a factory that had big presses. A belt spun a large flywheel (very large - hundreds of pounds) and the energy of the flywheel was transferred to the press (to stamp a piece of metal to an extact length).

Im afraid I dont know the mechanics of how it worked, but since it was a standard factory machine you should be able to look it up and learn the basics behind its operation.

[mechanicalbrain]

Thanks both. yeah I meant a disk with most mass on the outside. Thats an interesting idea about turning a flywheel to transfer to a electromagnet though I wonder if I guess it would work better then an electromagnet powered directly from a battery since the potential power can possibly be greater then that of the battery alone if I'm efficient. Yeah as to the machine press I'm not surprised, if you do the mathematics you realize flywheels can store massive amounts of energy. Actually the centripetal force on it is so great that they can explode if not balanced right (happens in the racing cars sometimes ) I'm looking at carbon composite but I'm also looking at using a medium power motor to power it, hopefully I won't have to worry about it. If I were to use electromagnets would I want to repel the rod or attract it? I'm kind of unsure on how that part would work, this is starting to sound like a rail gun.

[dlavery]

What is the stroke length of the rod motion you are trying to achieve (as an absolute length, and a percentage of the flywheel diameter)? Depending upon the desired output, there are a few neat little examples that I may be able to point you toward.

-dave

[gniticxe]

If dlavery has some examples for you, I'd go with them. But from what you said about the electromagnet, I don't think that I was clear in explaining the idea.

A battery is connected to the flywheel via a commutated shaft and brushes. Once the disc is up to speed, a switch is thrown to allow power to flow from the battery, through the commutator, and through an electromagnet. The magnetic field then pulls a ferromagnetic rod out past the outside of the disc. The rod you want to transfer the energy to is positioned so that the ferromagnetic rod will impact it.

Because of the centripetal force you spoke of, a spring will need to be attached to the disc and the rod to prevent it from extending prematurely.

Be careful in using this especially if you're turning it at speeds where the stress on the materials is close to their yield strength! Is your “medium size” motor a hobby or industrial “medium” ie 0.25hp or 100hp?

[Elgin Clock]

Hmm....

I think I know what you mean. maybe.

Would a modified version of a Geneva Wheel work?

I could be way off base in this I know, if I am, I'm sorry.

[Rickertsen2]

What is this device intended to do? Could you give us some more specifics?

[sciguy125]

This is sort of along the same lines as gniticxe's idea, but what about making the disk with teeth, something like a saw blade. Then, you push the rod toward the disk and it catches on the teeth.

Or, if your rod has relatively low inertia (and friction), you could use a friction disk to connect the flywheel to your rod assembly. Same idea as the clutch on a car, but with a thrusting rod of death.

[mechanicalbrain]

What I want to do is take a 2' bar and move it 1' forward with a ton of force. Yeah I'm looking at using a motor with roughly 100 rpm. My goal it to be able to puncture 1/10" to 1/8" steel. Right now its part of science fair project for centripetal motion but I also am doing this to really learn about flywheels... oh and eventually im going to apply it to a Battlebot

[Rickertsen2]

Originally Posted by mechanicalbrain

What I want to do is take a 2' bar and move it 1' forward with a ton of force. Yeah I'm looking at using a motor with roughly 100 rpm. My goal it to be able to puncture 1/10" to 1/8" steel. Right now its part of science fair project for centripetal motion but I also am doing this to really learn about flywheels... oh and eventually im going to apply it to a Battlebot

Maybie you could have the flywheel coupled to a rack and pinion via a clutch of some sort. It seems to me that somewhere i have seen some electric clutches.

[greencactus3]

Originally Posted by mechanicalbrain

What I want to do is take a 2' bar and move it 1' forward with a ton of force. Yeah I'm looking at using a motor with roughly 100 rpm. My goal it to be able to puncture 1/10" to 1/8" steel. Right now its part of science fair project for centripetal motion but I also am doing this to really learn about flywheels... oh and eventually im going to apply it to a Battlebot

100rpm isnt enough info. my cellphone vibration motor can be geared down to 100 rpm and my truck can also run its wheels at 100rpm.
and 2 feet bar to move it 1 foot?
the lighter the "ram", the more speed it will gain. but well. less mass.
will it just be a bar? or sharpened?
andas for going into battlebots. i would just use the flywheel itself as the weapon rather than add extra stuff which will be less efficient.

nother idea... with not exactly a disk but maybe a disk with large "bars" coming out as the flywheel.. and then somthing moves the "ram" into contact with the flywheel bars. so the bars crash into the back of the ram and it flies forwards. the cool thing about this would be multiple shots.

or just friction on the edge of the flywheel touching the ram. i had a foam dartgun that worked on this priciple a long time ago. although it had 2 flywheels. on on each side of the dart.

[KenWittlief]

you need to start working out the physics equations for this: Force, energy, power...

if you want to puncture 1/8" steel the rod only needs to move about 1/4", right? The idea you are grasping at is getting all the energy from the flywheel into the 1/4" movement of the punch

work out the physics: a 12" movement with one ton of force the whole distance takes 48 times the energy as a 1/4" movement with one ton of force.

[Rickertsen2]

Originally Posted by greencactus3

100rpm isnt enough info. my cellphone vibration motor can be geared down to 100 rpm and my truck can also run its wheels at 100rpm.

Why is 100 rpm not enough? depending on the design of the flywheel, 100rpm could be more than enough. How much energy would be contained in a planet spinning 100rpm!!!!!

[Jimbo5051]

Originally Posted by mechanicalbrain

What I want to do is take a 2' bar and move it 1' forward with a ton of force. Yeah I'm looking at using a motor with roughly 100 rpm. My goal it to be able to puncture 1/10" to 1/8" steel. Right now its part of science fair project for centripetal motion but I also am doing this to really learn about flywheels... oh and eventually im going to apply it to a Battlebot

Very good Idea I think that it would be feasible. But I do think you should gear it up to 350 rpm.