Rolled Shell Elongation

[LUAY_89]

Anyone knows how to calculate the stretch of rolled shell (cold working)? Is there any equation that take into its consideration the thickness and chemical composition of plate? I have problem with circumference of shell after rolling it always bigger than required and we had to cut the extra length and roll it again to get the required circumference. My equation I use on flat plate is The (actual thickness + ID)x pi +/- 1/8"

Thanks

 

[david339933]

That is the correct cut length calc (one I use daily)....Circumference at mid-thickness. Do you crimp the ends prior to rolling?

 

[LUAY_89]

Yes I always check that but after closing and fit up the shell the circ.is bigger than required. It usually 1/4" to 1/2" bigger on Circ and I do not know how much the tolerance allowed if the circ. is bigger than required.

 

[Don56]

How thick is your material?
Is there a root opening of the weld?

 

[LUAY_89]

The thickness of material is 1 3/4" and three is no root opening.

 

[r6155]

Please, do not repeat the same question
See

https://www.eng-tips.com/viewthread.cfm?qid=449917

Regards
r6155

 

[SnTMan]

It usually 1/4" to 1/2" bigger

If you are confident of that, decrease the plate length. How close you trying to get anyway?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

The neutral axis of plate may not be coincident with centroid of section
See ROARKS "TABLE 9.1 Formulas for curved beams subjected to bending in the plane of the curve".
Use the formula for dimension "e" = distance from centroidal axis to neutral axis measured toward center of curvature.

Regards
r6155