Bi stable belleville spring design

[bblazie]

There was a great thread a while back about this, and I was looking for some more help. I understand to get the bi stable effect i need a h/t of 2.82 or greater. I need a combined travel of .025" and am constrained to a diameter of .096. I need about 50 Grams of force at the top, and have about 150 grams of actuation force available. If I get the same travel up and down, then the h=.0125 and t= about .0046 I should get the bi stable action, What materials will put me in the range I need?

thanks for the help
Bryan

 

[desertfox]

here is the belville washer website where you can get washer dimensions:-

http://www.bellevillesprings.com/belleville-washers.html

 

[israelkk]

Do you need the snap force to be equal from both sides or the 50 grams from one side and other force to snap it back?
This will have an influence on the h/t you need.
You are asking for a travel between both stable positions of 0.025" which is also influence the h/t greatly.
Adding all this and the very small OD of the spring you will need h/t so high and the thickness of spring to be very very small resulting in very very high stresses in the range of thousands of ksi (1 ksi = 1000 psi).

 

[bblazie]

israelkk

I have about 150 grams of Driving force, I would like something close to 50 grams of holding force on one side. There is very little force needed in opposite position. The travel I need is .025" between stable positions. I have room to move on the 50 grams at the top 25 to 50? I kind of pulled the 50 out of the air. The critical design piece is the Travel, and force to drive from one side to the other. I am working on .01" centers but I could do layers if I need to to get more OD. the shape is another variable that I could work with, How does notching the inside and outside change the equations? (see attachment)
I really thank you for your help with this.
Bryan

 

[israelkk]

There is a product similar to the notching you offer called "Clover® Dome Spring Washers" but they all offered in the linear range and not for bi-stable applications. You can contact

http://www.asraymond.com/Clover® Dome Spring Washers

and try to check if your requirements can be met but I still believe it is not possible.

I have know knowledge of any design formulation literature that deals with such springs as compared to the vast literature regarding belleville springs. Basically, those springs are three times more flexible than bellevile springs however, there is the issue of stresses too. The point I wanted to present in the previous post was that to my best experience and the theory of belleville springs you are climbing on a very high tree and you are in an charted area as long as the space for the belleville spring is so limited for the 0.025" travel no matter the forces.