tonnage required to bend

[jaykay]

Blank is 144" x 18" x 3-1/4" thk, 100 ksi yield, 115-135 ksi tensile, will be heated to 1700 deg F before bending into a half pipe. I need the tonnage required to do this job. I would appreciate it if someone could help me figure out the tonnage required and (or) point me in the right direction so I could do this calculation.

 

[blmcghee]

Aren't the yield and tensile strengths given only applicable to cold stock? Depending on your material I think at those temperatures the molecular structure would change and depending on how the material was cooled the final product would have properties unlike the material properties intially considered.

 

[butelja]

You will need to know the yield stress of the material at the working temperature. To compute the bending moment required to form the plate, consider the plastic moment of the section. This is computed by assuming that all material above and below the nuetral axis is at the positive and negative yeild stress, respectively. Apply a "safety factor" (factor of ignorance) to factor the load somewhat higher than computed. As the plate is bent, the curved beam theory and relocation of the nuetral axis effects should probably be considered.

 

[mikerr]

plastic bending moment = w*t^2*Sy/4 = 144*3.25*3.25*Sy/4...you need to determine what Sy (mat'l yield) is.....what is the material??