Cold working - tube bending

[athomas236]

Does anyone know how I can calculate the extent of cold working (as a percentage since this seems to be how it is quoted in technical papers) when a tube is bent through an angle alpha at room temperature.

Thanks

athomas236

 

[metengr]

The best approach is to apply two light scribe (gage) marks on the presumed extrados location of the tube bend and measure the distance between the gage marks before and after cold bending. As the tube is bent, the OD surface will be exposed to a tensile bending stress that will increase the distance between the gage marks. The delta change in length between the gage marks/original length between the gage marks x 100 = percent elongation. Percent elongation translates to percent cold work.

 

[ijzer]

1/2D devided by Rm times 100%.
D=OD tube
Rm=Bend radius at neutral line.

 

[athomas236]

Than you both for your useful advice. Is there a theoretical derivation for the formula ijzer.

Regards,

athomas236