Flatting Round Stock
Flatting Round Stock
(OP)
How do you determine the geometry of a round bar if it has been flatten in a punch press? The area of the resulting part should be equal to the area of the original round bar stock. If you know the height of the flatten portion, can you determine the width of the flatten area and the resulting radii on the sides? I figure there has to be a formula that relates the two areas.





RE: Flatting Round Stock
RE: Flatting Round Stock
RE: Flatting Round Stock
area1 = pi*d*t
area2 = W*2t+pi*t^2
so W = (pi*d*t-pi*t^2)/2t
W = pi*(d-t)/2
practically you need tobe careful squeezing the tube, to avoid cracking on the bend radius; there are several ways of doing this.
RE: Flatting Round Stock
Get out your materials text book and lookup "Poison's ratio".
RE: Flatting Round Stock
but i think it's a second (or third) order effect ...
i've got a terminal lug on my desk, and to the accuracy of a scale in 1/64" the equation above works.
RE: Flatting Round Stock
Handy site.
RE: Flatting Round Stock
Thanks rb1957 for your input!
RE: Flatting Round Stock
if it's a rod then
area1 = pi*d^2/4
area2 = Wt+pi*t^2/4 (t now is the thickness of your flattened bar)
W = pi/4*(d^2-t^2)/t
neglecting 2nd order effects
RE: Flatting Round Stock
what will happen to the rod, is that that as it is being flattened, the end will bulge, (an effect not particularly significant with a tube) so the post above is not quite right ... instead of considering cross sectional area you need a constant volume approach. unfortunately this is alot more complex
RE: Flatting Round Stock
All the students go for constant volume, except for the few that read the book and apply poison.
RE: Flatting Round Stock
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Flatting Round Stock
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Flatting Round Stock
RE: Flatting Round Stock
Is that an awful analogy?
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Flatting Round Stock
Upon release of the elastic strain (either during elastic-only deformation or after elastic + plastic strain), the bonds relax, interatomic spacing decreases, density increases to its original value. Hence, volume constancy is an acceptable assumption.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.