Rolling sheet metal into a curve 1

[geoffthehammer]

We have a piece of sheet aluminium 1.6mm thick. We have to punch/drill a series of holes in the piece and then roll it into a single direction curved shape with the holes around the curve.
We will roll the sheet using a standard 3 roller machine. The chordal pitch of the holes is important. I have been told that rolling sheet metal with a 3 roller machine stretches the material - is this correct. Is there a formula (function of material, radius etc)available to predict the change in length. How do I predict what the starting (flat) hole pitch should be?

 

[CorBlimeyLimey]

Any time you bend metal, stretching of the outer surface & compression of the inner surface occurs.

Lots of good sheet metal information at

http://www.sheetmetalguy.com/

Helpful SW websites FAQ559-520
How to get answers to your SW questions FAQ559-1091

 

[rb1957]

why not punch the holes after you roll the sheet ?

 

[JStephen]

I'd assume that the length at centerline remains the same.

 

[CorBlimeyLimey]

That depends on the radius and temper (of the material not the operator) and the accuracy required.


Helpful SW websites FAQ559-520
How to get answers to your SW questions FAQ559-1091