- Joined Jan 17, 2007
I'm opposing the rotation of the coil winder. And no, I'm not going to go into so much sophistication as using feedback on this. But what I did is make the spool's minimum radius much larger than the coil. For instance, the spool's inner diameter is about 50mm, while the coil's is 10mm. That way I expect to ease the fluctuations in tension a little bit. Also, I plan to run the winder at a low speed. This is not for a production application, but rather for prototype testing.Are you controlling the motor in the same rotation as the spool rotation, or opposing it, are you using feedback to concur with the ever increasing rpm of the spool?
For stable continuous torque you should feed motor not by voltage but by current.I'll be applying PWM (8-bit resolution) to the dc motor, so I don't think I'll be needing a resistor o rheostat ... would I?
I had already considered using an air turbine, but unfortunately I have no access to pressured air where I am. On the other hand, air blown from a hair dryer would be too weak for my purpose, I think ... but I'll give your suggestion some more thought anyway ... thanks for sharingCan you use air pressure to provide resistance and retraction when the wire slackens? Once ran an EDM (Electric Discharge Machining) unit. It had a spool of brass wire that was kept constantly tensioned against the feed using air pressure. If the wire broke the tensioner would rewind the spool. That never happened, but when threading the machine you had to turn off the tensioner and lock the brake so that it only gave resistance but allowed you to spool out the wire as needed. During threading you ALWAYS had slack at some point. During operation, because the spool was so large that momentum would tend to unwind the spool every time the EDM operation ended. Keeping a constant back pressure using air pressure is what they use to keep the spool from slackening up.
Perhaps a couple fans on your spool. One providing air flow and the other connected to your spool. As one fan spins (electrically) the other spins due to air flow. Don't know how fast that would react to a slack wire but it's one quick and dirty way of solving the problem. I think. I could be wrong.
You're right ... but first I'll try it using only pwm, and if that doesn't work well enough, then I'll put a current sensor in the circuit and adjust pwm accordinglyFor stable continuous torque you should feed motor not by voltage but by current.
Only way is to convert PWM to analog signal and send it to input of current stabilizer then to motor. Still same rheostat, if stabilizer will not works in switching mode.
Yes, some like this. Inductance will provide continuous motor current:You're right ... but first I'll try it using only pwm, and if that doesn't work well enough, then I'll put a current sensor in the circuit and adjust pwm accordingly
That's a very interesting circuit, Danko. Why is there a resistor in the loop, to minimize oscillations/resonance?Yes, some like this. Inductance will provide continuous motor current:
yup, that's the way it's usually done.. but I consider it overkill for the machine that I'm building.Actual tension measurement is usually done with a spring loaded arm and you measure angle.
This time you've outdone yourself, and gone beyond the call of duty. Many thanks, my friend.Two cheapest Permanent-Split Capacitor Induction Motors:
Not yet...This time you've outdone yourself...
|Thread starter||Similar threads||Forum||Replies||Date|
|Adding remote controlling to my car audio head unit||General Electronics Chat||4|
|Controlling a Dc motor||Analog & Mixed-Signal Design||42|
|Controlling current for kanthal wire||General Electronics Chat||27|
|Controlling a 4 wire servo||General Electronics Chat||30|
|J||Controlling Auger via 2 wire Capacitive sensor/starter & replay single phase||Sensor Design & Implementation||2|
by Jake Hertz