Like Oil For Water

The stories it could tell, the places it’s been: Helping the German war effort during WWII and then shipping over to America afterward in the hands of the U.S. Army and its heavy-press program. There, in Madison, IL, the Air Force installed the machine in a Dow Chemical facility. Eventually, the press moved to St. Louis under the ownership of the Spectrulite Consortium. That’s where Universal Alloy Corp. acquired it and began moving it to Canton, GA, where it resides today.

The huge press won’t be taking it easy there, 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 can extrude faster than a direct press because the container that holds the billet floats with the cross head, Scaglione explains. The cross head is 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, he says. If those walls move with the cross head, as they do in the indirect mode, that friction falls away. Another advantage of the indirect process is less waste, he says. For the same 70 inch billet, the direct process produces 20 percent scrap while the indirect process lowers that percentage to three. Add to that list better grain structure and fewer kilowatts needed to do it all. Of course, the indirect process can’t make parts as large as those made by a direct process. So, Universal Alloy made the press convertible. It can switch from direct to indirect modes in about a day, according to Ed Heffner, maintenance manager of Universal Alloy’s Anaheim, CA operation. 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.

Universal Alloy was able to raise press force by a couple thousand tons by using the piercer, ordinarily used for making hollows, to back up the press’s three main rams. Among the parties involved in the project, 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 said 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, in fact, 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, one of those machines that looks like a flat-bed trailer but with many, many wheels.“Only a year passed from the time we broke the first bolt to the time we put the first power to it,” Heffner says of the machine, which he calls the largest indirect press in the world. Only Russia has a bigger direct press, he adds. As the press was going back together with new hydraulics and a new control system, a building was going up around it.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 on Universal Alloy Corp., visit
http://www.menzaero.com/

For information on Bosch Rexroth, see
http://www.boschrexroth-us.com/country_units/america/united_states/en/products/bri/index.jsp