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Bending brake capacity: 2024-T3 vs. mild steel?



 
 
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  #1  
Old June 4th 05, 09:39 PM
Ihab Awad
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Default Bending brake capacity: 2024-T3 vs. mild steel?

Hi folks,

Most bending brakes rate their capacity by the thickness of mild steel
that can be bent. How does this relate to capacity of 2024-T3 aluminum?
So, what aluminum thickness can a 16ga, 20ga, 22ga, ... brake handle?

Should I simply multiply by the ratio of the yield strengths? That
somehow seems like an oversimplification.....

Thanks a lot. Peace,

Ihab

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Ihab A.B. Awad
email: firstname dot lastname at gmail dot com
Palo Alto, CA, USA
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  #2  
Old June 5th 05, 11:37 PM
guynoir
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According to American Machine Tools, you are correct.
http://www.americanmachinetools.com/...e_strength.htm

More important considerations are bend radius and springback. Most press
brakes come with sharp upper dies and 90 "vee" lower dies. Neither work
very well with hardened aluminum alloy. For aluminum, you need a "U"
channel in the bottom die, and a radiused upper die. 1/8" radius is a good
general purpose choice for the upper die.

To get a 90 bend in 2024 aluminum, you have to over bend it by about 7 to
accomodate springback. For 7075 T-6 it is 20. This can't be done with a
90 "vee" die.


Ihab Awad wrote in news:d9KdnZNva5hK7j_fRVn-
:

Hi folks,

Most bending brakes rate their capacity by the thickness of mild steel
that can be bent. How does this relate to capacity of 2024-T3 aluminum?
So, what aluminum thickness can a 16ga, 20ga, 22ga, ... brake handle?

Should I simply multiply by the ratio of the yield strengths? That
somehow seems like an oversimplification.....

Thanks a lot. Peace,

Ihab




--
J Kimmel

www.metalinnovations.com

"Cuius testiculos habes, habeas cardia et cerebellum." - When you have
their full attention in your grip, their hearts and minds will follow.
  #3  
Old June 6th 05, 09:50 PM
Ihab Awad
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Posts: n/a
Default


guynoir wrote:
http://www.americanmachinetools.com/...e_strength.htm


Ah, thank you!

More important considerations are bend radius and springback. ...


Thanks again for the very helpful info.

Most press brakes come with sharp upper dies and 90 "vee" lower
dies. Neither work very well with hardened aluminum alloy. For
aluminum, you need a "U" channel in the bottom die, and a
radiused upper die.


That's quite interesting. Would the geometry of this bend be such that
the (presumably rounded) edges of the U channel would "wipe" or slide
against the aluminum as it is pressed in between them by the upper die?
If so, does this validate the approach of this homebuilder --

http://www3.sympatico.ca/murray.j/tools.htm

His idea is that the hinge line of his brake need not pass directly
through the exact meeting point of the apron and bed surfaces -- the
metal will slide across the apron to compensate. Thus he is able to use
a series of hinges to support the apron all along its length, and can
therefore get away with a less-stiff apron.

If this builder's idea is correct -- and validated by the geometry and
usage of press brake dies -- why are not more industrial bending brakes
built to take advantage of this? Or, what am I missing?

Thanks a huge lot. Peace,

Ihab

--
Ihab A.B. Awad
email: firstname dot lastname at gmail dot com
Palo Alto, CA, USA
 




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