The stories it could tell, the places it's been: Germany during WWII and America after in the U.S. Army's heavy-press program. The Air Force installed the machine at a Dow Chemical facility. Eventually, the press moved to St. Louis where Universal Alloy Corp. acquired it and began moving it to Canton, GA. There it resides today.
The huge press won't be taking it easy either. Universal Alloy, having changed it over from water to oil actuation, will be running hard-alloy aluminum aircraft extrusions out of it as much as three times as fast as it produced them in its glory. Says engineering vice president, Paul Scaglione, the speed increase comes because they've converted the machine to indirect extruding.
An indirect press extrudes faster than a direct press because the container that holds the billet floats with the cross head, the part of the machine that pushes the heated metal through the die. For direct extrusions, the crosshead works against both die friction and the friction of the billet on the container walls. If those walls move with the cross head, as they do in the indirect mode, that friction falls away.
Other advantages of the indirect process are less waste, better grain structure, and fewer kWs needed to do it all.
Less friction, wear
The change from oil to water in itself didn't provide any great performance gains, Scaglione says. Instead, it makes the machine less expensive to own and operate. Valves work better in oil and wear drops off too, thanks to oil's lubricating properties. Still, the company had to go with a high-pressure water and glycol system up on the heated tool platen for fear of possible oil fires there.
Bosch Rexroth Hydraulic Systems and Engineering group of Bethlehem, PA, met with Scaglione and representatives in mid-2003 while the press was still in St. Louis. Systems Engineer Otto Weber says he joined the conversation then when the transformation was just being imagined. Scaglione had a good idea of how he wanted the press to work, and the team came up with a plan for a hydraulic system that could fit inside the machine envelope.
That envelope turned out to be quite large—so large that it took 167 special-permit trucks and seven railcars to move all the pieces down to Georgia. The biggest part, the front platen, weighed 124 tons.
Universal Alloy worked with press-rigging specialist Mamut of Germany, which has been a participant in the raising of the Russian submarine Kursk. Riggers brought the platen within a quarter mile of the site by railcar. Then, they built an overhead gantry to lift the platen onto a Goldhofer transporter, the many-wheeled flat bed mover.
"Only a year passed from the time we broke the first bolt to the time we put the first power to it," says Ed Heffner, Universal Alloy's maintainence manager. He calls it the largest indirect press in the world. Only Russia has a bigger direct press, he adds.
Of the original water over air system, only three things remain, says Rexroth's Weber: the main cylinders, two big accumulators, and the pre-fill valves.
For more information, visit Universal Alloy Corp. and Bosch Rexroth.
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