Push Solenoid Question 3

[stcross0]

Hi,

Im currently seeking some very basic information on a push solenoid. My question is, can I control the amount of force a push solenoid exerts by using a rheostat. Im aware that the solenoid comes out very fast but for this projectile project im making, one of the requirements is to have a projectile device that can change the the amount of force exerted on the projectile(ping pong ball in this case). Would using a rheostat change the amount of force exerted by the push solenoid? even if it was a very small difference in striking force? I can project the ball further if needed by using simple kinematics and change the angle of the barrel. I just need it to "meet requirements". Incase your wondering, im using the solenoid in the back of a PVC pipe to launch the ping pong ball. All the other students used spring loaded devices and I wanted to try the electrical power of a solenoid. I would greatly appreciate any help. Thanks for your time,

Steve

 

[ScottyUK]

This post will probably disappear soon because this forum is for working professional, but your post is polite, well-written, clearly stated and in plain English instead of the infernal txtspk which some members here use so I'm gonna bend the rules a little. I wish some supposedly professional engineers took the time to write their questions in the way you have. If (when) you get booted off the forum then please come back here once you're working - we could do with some more decent members.

The short answer to your question is 'yes'. A slightly longer answer is that the solenoid is a current-operated device, so if you can vary the current - using a resistance for example, although there are other ways too - then you can vary the force exerted by the solenoid. Good luck, and kudos for not being afraid to do things a little differently to the herd.

 

[zeusfaber]

One thing you might want to look at early on in the design process is how fast you can get the current in your solenoid to rise when you apply power. Be a little embarrassing if the projectile has already dribbled out of range before the coil develops peak effort.

A.

 

[MikeHalloran]

Zeus is not quite saying that you have to learn about how the coil inductance and the applied voltage affect the performance of a solenoid. Basically, lower inductance and/or higher voltage will make it move faster. You also have to severely limit the time for which the current flows if you jack the voltage up above the rated number. ... or be able to replace a burned solenoid quickly.




Mike Halloran
Pembroke Pines, FL, USA

 

[stcross0]

Thank you all for your valuable input and time.

Steve

 

[itsmoked]

!) Consider a rotary solenoid as the speed can be somewhat controlled by the length of the arm.
2) Check out DC solenoids verses AC solenoids.
3) Learn what PWM is.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

The inverse square law makes it difficult to control. Your minimum force will be the result of the minimum voltage required to start the solenoid moving. Not impossible, but difficult. Short voltage pulses in the order of less time than it takes the solenoid to complete a stroke may work for you. You may need a freewheeling diode to keep the smoke in your control circuit when switching the solenoid supply at high speed.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[VEBill]

As others above have hinted, this type of driving system isn't likely to provide a reliable demonstration of Newton's 2nd Law (F=ma). It's going to be all about either simple velocity at the end of the stroke (if the ball remains in contact with the plunger), or much more complicated impact (if there's any gap).

Perhaps that doesn't matter if you're just whacking ping pong balls for a higher purpose.

 

[Compositepro]

Use a capacitor to power the solenoid. You can charge the capacitor to different voltages to vary the impulse of the solenoid. This will give a very controlled amount of energy to each shot. Use a resistor to limit the capacitor charging current to a low value.

 

[Pud]

Go for broke:

http://en.wikipedia.org/wiki/Spud_gun

Just vary the gas input...

Have much fun and watch your peers' slack jaws..

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[ScottyUK]

Ha-ha, as a kid I spent many happy hours launching golf balls from a potato cannon fuelled by Zippo fuel.

 

[VEBill]

Here's the king of Mad Science, home-made, hyper-velocity launchers: Sam Barros' PowerLabs. He's been experimenting with various technologies including rail guns.

The ping pong ball (and ceiling) would require extensive modifications to survive.

 

[IRstuff]

One thing to consider is to NOT use the solenoid to directly impact the ping pong ball, if that was your intent. The battery operated Airsoft guns use the solenoid to push a piston that generates the air pressure that launches the Airsoft pellet. This avoids any extreme impacts on the projectile itself.

TTFN
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