Peak Behind the Curtain

Roll Levelling Machine
with detail of the sheet bending between the rolls

When I hear about 'infrastructure' in discussions about the economy, I think of roads and bridges and dams, huge things that you can't friggin' miss if you go outside. What isn't often mentioned, and what you seldom see is all of the machinery inside of all of the factories that are busy making all the widgets that make our cushy, civilized life possible.

Driveshafts connecting the gearbox (foreground) to the 'large leveler' (background)

Bustednuckles has a post up that gives us a peak behind the curtain. He  had a very long day at work yesterday installing a gear box for a 'large leveler'. This machine is for relieving internal stresses in sheet metal as it is taken off of big rolls. The way it works is nuts. Why would bending sheet metal back and forth multiple times relieve stress? Sounds like it would just add more stress, but what do I know? Evidently it's a proven technique, so every place that is taking in big rolls of sheet metal direct from the rolling mill is going to have at least one of these.