Manufacturing Bent Z profiles

[Kevin James]

Hi All, structural engineer here, so a bit out of my league.

I am trying to manufacture some Z profiles with a radius is the strong direction.

The Z is 2 flanges of 3/4 and a web of 1 3/4 inches. The thickness is 0.080 inches Lengths are about 8-9 feet.(12 ga) I chose 2024-T3 as the material.

I did a test today with a roll bender with custom dies and some material I had bent from some sheet aluminum and it failed. Imagine the stringers in an airplane or the wall members in a rail car - they have a varying radius along their length. SKin is attached to the outside and interior finish is attached on the inside.

I know its possible because I have some old samples from some 1950's construction that we are trying to re-create.

I'm looking for help on what tooling would do this, is there any standard extrusion out there? Really any advice would help.
Thank you in Advance
James
Drawing of the part I made:

https://files.engineering.com/getfi...0f5-b203-aaa7e09c2c62&file=220301-01-REV-.PDF

 

[3DDave]

The bend is too tight for that alloy and temper combination.

https://www.americanmachinetools.com/bend_radius.htm

6061 seems like a better choice.

 

[Kevin James]

Hi 3D Dave,

I appreciate the feedback on that! Your link is going in my favorites'. However the profile in the drawing is just an example. I want to take that full straight piece of Z and bend a radius in it of down to 25 inches in the "strong" direction.

James

Heres a scketch from a brochure.

https://files.engineering.com/getfi...fe-a83a-4332-bbb2-1bdf7324ef97&file=Z_bow.PNG

 

[3DDave]

OK - I was pointing out that the original profile won't easily work. I would take it to a T0 condition before roll forming.

It looks like you need a thickness change of about 7% between the inside flange and the outside one and also across the web. To roll form you may need pinching rolls to thin the metal on the outer flange and the radius and a portion of the outer section of the web.

I suspect the original fab was more typically done by cutting an arc of material and forming the flanges in a die, maybe rubber/hydraulic press.

 

[mfgenggear]

I forgetting being a while, to my mind it is brake formed to apply the z, then hydroformed to apply the radius that large. typical of that era
and agree with dave use annealed condition T0, while bending and then Heat treat. generally slip rolls is for flat stock, there might be a specialized
vendor that can use rolls for the z but would be high volume.

 

[david339933]

AL - 5052.

 

[berkshire]

To bend that profile, you would need to use T0 then heat treat after forming. As far as bending in the strong dimension a buffalo roller with custom wheels or stretch bending would be your best bet.
B.E.

You are judged not by what you know, but by what you can do.