Require formula for v.large scroll spring

[MJN78]

Hi,

I have a problem where one solution suggested has been to use a scroll spring. However I am finding it hard to track down a formula to calculate the dimensions of the spring for this style of spring. Please can you provide me with a reliable formula. I have been given some different formulae already and they seem to contradict each other, so I want to see what else is out there and to help me understand why I can't get the other formulae to churn out something sensible and near each other. Any help is much appreciated.

The spring in question needs to absorb and transmit the energy from a 13000N fixed force at varying oscillations. The operational load oscillation is between 0.18Hz and 0.12Hz. The operational power input ranges from 5000-15000W. The maximum size of the spring housing is 0.90m in diameter. Although a battery of tension springs would be easier to calculate and purchase, the shape of the rest of the machine means a scroll spring might fit better.

Please share your ideas, all are appreciated.

MJN78

 

[desertfox]

Hi

Do you think it might be a good idea to show us what formula you already have rather than waiting till someone here gives the same formula

 

[chicopee]

A scroll spring is merely a spiral spring, so see the attachment. This attachment is from Kent ME handbook "Design and Production" 12th Ed. which you should buy as reference probably used for a fraction of the cost of a new one.

 

[israelkk]

First of all a "scroll" spiral or torsion springs are designed to take torque not force. When you say 13000N you mean force. Secondly what is the angle that the spring will see under the specified torque? You mentioned 0.9m diameter but what is maximum height? How many oscillations the spring need to see before failure?

 

[MJN78]

Thank you to everyone who replied.

The handbook page was most helpful. I appreciate the time you spent on my question. I will be able to use these formulae to complete my calculations for feasible designs. Hopefully these will resolve my problem, if not I guess you will see another post from me in the coming weeks.

Also thank you to those who gave advice on improving my communication so that when I post again I can write more clearly.

Yours sincerely,

MJN78

 

[chicopee]

If you do post for further communication on your post, let us know of what you have done so far with the information at hand.

 

[tbuelna]

The spiral spring described is sometimes called a "clock spring". Torsion springs are usually helically wound wire springs with a leg at each end where the load is applied and reacted, or something like a metal bar that is loaded (twisted) in torsion between one end and the other.

A spiral or clock spring has the advantage of providing a relatively constant torsional rate over a large angular displacement, but is limited on the amount of torsional force it can accommodate. For the torsional forces and frequencies described, if the angular displacements are modest then it might be better to use some form of torsion bar rather than a clock or spiral type of spring.