Force to cold-bend steel plate 1

[DavidCR]

I need help to estimate how much force is needed to bend a plate. It is for a 11m diameter welded surge tank for a hydroelectric project.

Plate material: Carbon steel, tensile strenght: 70000 psi (There is also an option of using a 50000 psi plate)
Thickness: 50mm (1.97").
Wide of plate 3m (118").
Diameter (Bending diameter): 11m (433")

The guy who is asking this says that they think to perform this in cold with a roller over the plate between two rollers spaced 0.3m (12"), but he does not know what is the force needed to be sure is they can do it.

So I´d appreciate a lot if somebody can help me with a formula to calculate the force required, or with an estimation of the force also is somebody wants to help with recomendations on how to bend the plate in an easy way, that would be welcome.

Hi and blessings to everybody there.

 

[JoeTank]

David,
Check out the following website. It mentions 1.25 inch plate, 10 feet wide, 50 ksi yield material requiring 900 tons of roller force to roll-bend a plate. For the 2 inch plate you mention, the force would increase substantially as the plate bending resistance will increase as a function of t cubed.

http://www2.thefabricator.com/Articles/Fabricating_Article.cfm?ID=662

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[metengr]

Here is a web site from one of the major steel companies that specifically addresses press load requirements for forming steel plate. The equation that is referenced is as follows;

Press load = 0.833 X Ultimate Tensile Strength X thickness ^2 X Length/width of the die opening

dimensions are in inches.

The web site is below. The attachment is "Guidelines for Fabricating and Processing Plate Steel". This is excellent reference material to keep handy.

http://www.intlsteel.com/PDFs/products/duracorravail.pdf

 

[unclesyd]

The reference by metengr is just one of the very good papers and books put out by Bethlehem Steel when they were still alive and kicking.
As he states this one is a very good one to keep around.

Anecdotal for metengr
The photomicrograph of the lead inclusion with cracking reminds me of my first ever encounter with a steel producer, no less than the Chief Metallurgist of Bethlehem concern incipient cracking in A2 tool steel caused by lead inclusions. A very similar picture, Glass Plate, won the day. Two plates went back with the gentleman, he would settle for a print.

 

[DavidCR]

Thanks to all and especially to Metengr.

The 0.833 formula, leads me to a value of 2260 tons. That surely is making our "shop-man" wondering.

I wonder, in consideration of the thickness, if the formula has a range of application, but the value provided is quite useful as an initial aproach, and at the moment is the best reference since other formulas I´ve found are for sheet and plate for other applications.

 

[metengr]

DavidCr;
If you have your "shop man" wondering, I would not risk it. As I mentioned earlier, you can hot bend the plate but the equipment may not be suitable to handle this type of work.

Follow the advice from deanc (the original post was in the Boiler and Pressure Vessel forum) and shop around, you should be able to locate another vendor to sub-contract this work.