How to Design a Torsion Spring for a Carousel Loading Mechanism?

[deborah_88]

Hi there, needing some help with a torsion spring application...I'm looking to use a torsion spring to load a carousel (which is about 400mm diameter, 100mm height and weighs about 2.5-3Kg) so someone will turn this carousel (onto a base) which will load the torsion spring...the spring will be prevented from moving back to its original position and held at that position. THEN, through an escapement mechanism and lever arm, will allow a degree of movement when the user requires it. There must be 16 intervals of this movement which will turn the carousel 16 times to specific points.
I'm not sure if that makes sense at all! But any help on where to start, first of all where to start with torsion spring calculations as the 16th interval will have a lower spring force (as it is the closet distance to the original point of the torsion spring arm) so how to make sure this is still "strong" enough to turn the carousel. Also, how to translate the 16 intervals to the turning of the carousel -so maybe the torsion spring will but directly in contact with the carousel or would I be best using gears to increase to movement? (the distance for each interval that the carousel needs to move each time is approx 30-40mm)
ANY HELP WOULD BE APPRECIATED!

 

[Unrest]

Since the spring's force will vary with displacement, you should make sure the spring is only moving through a small displacement relative to the distance from its unloaded position, then the force is approximately constant.

I think the carousel is only moving through half a turn or less, so maybe you can have a cam on the carousel which loads the torsion spring through a lever.

Or use a softer spring connected directly, so the unwound position of the carousel corresonds to, say 2 turns of the torsion spring, and the fully loaded position corresponds to 2.5 turns. Then you can calculate the spring's torque at the two ends of the range to make sure it's always acceptable.

Or use a clockspring which has more constant force over a much wider range of angles.