Calculations Out There to Figure Interference Fit

I'm looking at the sloped part of the outer piece and thinking of bending the lower third or so about 20° to the left. This would make a "funnel" that would ease the snap-on operation.

Then I would make a few prototype samples, adjusting things until the fit was good. You might have to do this anyway to verify the adequacy of any calculations.

That is a solution that I have done previously, but did not work out structurally. The seam has to be able to withstand a minimum 3000 lb. static load, from the open side of the seam, and not deflect any more than 0.500". That test provided results well over the deflection limit and I theorize it is due to the design allowing the seam metal to slide past each other during its deflection. So I'm looking to have a much tighter joint profile, which would provide more resistance to bending. I'm trying to get to a design that will not require the need of mechanical fasteners to reinforce the seam joint.

Also, I'm thinking that such a design would involve the flexibility of the steel to mate the parts in such a way as originally proposed and maybe some compression of the mating steel surfaces. The flexure would have to stay below the steel's yield point, so that it would spring back.

I was hoping there may be some sort of calculation out there that may get me closer to the actual required allowances quicker without having to fabricate too many prototypes.

I appreciate your time on this Tornado. Interesting handle when considering all of the twisters that touched down in the south this week!

23.4.11

Sorry to sound like a spoilsport, but I wouldnt look at interference fit as a design approach at all for sheet metal components.I have a reasonably big tool holding practice. If I were to extrapolate the surprises thrown up by well designed interference fit systems elsewhere, I would steer clear of sheet metal components from a long term perspective

Vinay Isloorkar

drill down in this search tree and see if anything fits.

sheet metal snap seams

For a brief period of 3 months (back in about 1986) I had worked with the folks at Ford Motor Company. These folks had a wealth of programs for what was called 'spring back'. The applications were not just geared to the stamping and forming of metal but also the reactions of folds and related stress lines and effected areas and the compensations needed for formation. You may have some additional insight if one of these fine retired folks were party to your question or some of the data from some related site or subcontractor. Just a thought.

Goodness point for that. Here is a search on spring back.

http://www.google.ca/search?hl=en&source=hp&biw=1440&bih=759&q=%22metal+forming%22+%2B%22spring+back%22&btnG=Google+Search&aq=f&aqi=&aql=&oq=