Press brake question

Question

Press brake question

justhumm (Structural)

(OP)

3 Aug 18 16:56

I am designing and detailing a bridge-mounted, steel, tapered (roughly) cylindrical light pole that could be readily fabricated, without a shop having to get special equipment.

I'm getting snubbed for information from a few manufacturers...is there a reference (machinist's handbook, etc) where I can find this info (or estimate it):

What's the highest ratio (tightest bend) of plate thickness / pole diameter that a press brake (that a light pole manufacturer would have) can handle?

i.e.:
can a shop fold or roll a 1/2" plate into a 6" O.D. tube? Or is that too impractical?

Thanks!

MikeHalloran (Mechanical) · Answer 1 · 2018-08-06 02:46:21

That's mighty stiff stuff.
The length also makes a huge difference in whether a given shop can fab what you want.
You didn't tell us; did you tell them?

Mike Halloran
Pembroke Pines, FL, USA

justhumm (Structural) · Answer 2 · 2018-08-07 20:53:28

Quote (MikeHalloran)
You didn't tell us; did you tell them?

I'm just talking about standardized DOT traffic lights and signal poles, nothing "specialized". So I don't expect piece length would be an issue for one of the shops that regularly supplies transportation projects (Valmont, etc).

For argument sake, the poles are probably c. 40-ft. Anything longer is going to be field spliced.

Mainly just interested in finding out some practical rule-of-thumb / back-of-a-napkin guidelines.

EdStainless (Materials) · Answer 3 · 2018-08-08 14:34:53

Well look at the Valmont catalog.
They show a heavy duty steel pole, round, 50' tapering from 13" base to 6" top in 3 ga (0.240") as the heaviest.
They also give all of the load factors.

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P.E. Metallurgy, Plymouth Tube

DAVIDSTECKER (Mechanical) · Answer 4 · 2018-08-16 21:45:31

Have you thought about 6" x 1/2" WL DOM mechanical tubing?
If you must have a taper you could cut a "V" down the length and then press the opening closed and weld it shut.

igor_pbt (Industrial) · Answer 5 · 2018-11-08 17:10:30

Hello, try to add some of my thougts.
1/2" plate means 12,5 mm
Under rough theoretical calculation it goes 100 t/meter.
So to get pole 12 meters you need to find the press brake solid or tandem with the capacities 1200 t/12 meters
So the main question about not the highest ratio but to find the suitable machine to do the job. Moreover under mine experience poles steel was much thinner, yours is too thick. Probably based on the application.
About the diameter really do not know what to say. Never heard about so small and thick metal poles.
Is the question to weld it after is cleared?

EdStainless (Materials) · Answer 6 · 2018-11-09 02:29:36

We used to press form pipe. I recall doing 6 (6.625" OD) x 0.430" wall in the press, we also did some 12"OD x 1" wall and other stuff up to 72"OD.
I don't recall the press rating.
Something this size didn't come out very round, more like 10 sided.
We made marks at each end of the piece of plate, used contoured nose and shoes, and the started forming from the outside edges.
Once formed we would clamp it up and use an automatic track welded to finish it.

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P.E. Metallurgy, Plymouth Tube

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