Torsion spring question

[nadsab]

Can a torsion spring be twisted in both directions without weakening it?

In other words, can it be twisted in the direction of tension (thus slightly reducing it's diameter), and also be twisted in the opposite direction which would thus increase or expand the diameter? With out pre mature failure? Or are most such springs only designed to be twisted in direction of compression (smaller diameter)?

I have an application for a 180 degree torsion spring, I would like to twist it 90 degrees in either direction...

Thanks for any input.

[mike_Kilroy]

testing my ol gray cells, from college engineering class days, I would say you can extend or contract any spring, as long as you dont do it past its design limits.

[nadsab]

Thanks.

Is the spring force or torque uniform in both directions?

[mike_Kilroy]

i think it should if symmetrical spring design.

[keebler303]

Obviously I don't know your application but one disadvantage to using a single spring is that there is zero spring torque at the center position so it may not stay centered reliably. If you used two springs, you could have them back to back so one would travel 0 to 90 and the other 0 to -90, add stops so that they dob't go past 0 and you can have a fair amount of force at the center and it is still bidirectional.

Matt

[handlewanker]

Keebler is right, but you also, depending on the length of the springs, get increasing tension as you go from the 0 to 90 deg twist, even if'n you add a preload twist, which you must, or you'll get some dead motion at the centre point.

BTW, as you wind one spring up, you also unwind the other spring, so doubling the torque needed to apply the twist, and in both directions too, and the torque increases with the twist.......but it helps to even out the torque if'n the springs have a number of coils in each.

Garden gate hinge closers have only one spring to do the closing and the spring is pre wound up to exert force for closing, but always has force stored when at rest.
Ian.