You have to tell us more about your application

and you have to understand that unless you are willing to give us this information we probably wont help with your problem. If you are just looking for information on springs and types it is available at any library. ■

Bhaskar

(1) What is the spring outside diameter?

(2) Are the 8.9 coils the total number of coils - or the number of active coils?

(3) What speed is your screen operating at? ■

Bhaskar

I have done a very quick review of your spring selection, which I understand to be:

26mm wire dia

242mm outside spring dia

350mm free spring height

7.43 number of active coils

8.94 total number of coils

Total screen mass = 6,000 kg supported on 8 springs

Vibrating frequency = 850 rpm

By calculation I figure the solid height of the spring would be 232mm, and the spring rate would be approx 6.22 kg/mm.

Assuming that the screen mass (6,000 kg) is equally distributed between the 8 support springs, then each spring will carry 750 kg.

Therefore under the static load of the screen, each spring will compress (750kg / 6.22 kg/mm) = 121 mm, and the compressed height of the spring would be (350mm – 121mm) = 229 mm.

Compare this compressed height (229mm) with the solid spring height at 232mm,and you can see that you have compressed the spring solid just by resting the screen on it !!!

I would be selecting a spring with about 65mm compression under static load, and at least 30mm difference between compressed height and solid height to accommodate the increase bounce at stop/start, and also any heavy material loadings, surges, or material build up around the coils.

As to your original question regarding temperature limitations. Talk to your spring supplier, but I would think that spring steel should be OK up to about 220 degrees centigrade. ■

Bhaskar

From my understanding of your problem you need to increase the spring rate (make the spring stiffer), not decrease. ■

Bhaskar,

Some spring steels have better temperature ratings than others. What sort of temperature range do you want to operate at? ■

I don't understand how you can reduce the rate of a given spring from 6 to 4. Unless....Anyway; there is no need to account for fatigue in a spring that is bottomed out all the time: which rather makes the issue of the tempering temperatures irrelevant for the time being. Which is how you might reduce the spring rate...if that was the drift of the question. ■

Bhaskar,

By my quick check all the springs should work fine (at better than 98% isolation you have done well).

My only comment is that I have assumed that the screen weight is distributed evenly between all 8 springs. On circular motion screens this is generally a reasonable assumption, but on low angle linear motion screens the load is usually much greater on the discharge end mounts. To determine this you need calculate reactions at the mounting points. ■