Page 24 - MetalForming April 2012

Piper
Picked a
Perfect Press
...on which it could offload sheet-hydroforming of smaller airframe parts, saving its large-bed fluid-cell presses for bigger parts. Aside from the cute tongue teaser, Piper’s new small-footprint precisely controlled press is performing perfectly.
BY BRAD F. KUVIN, EDITOR
Major aircraft manufacturers press. These presses have proved very parts, to extend the life of our larger
presses and optimize cycle times.”
A Familiar Tune
See’s desire to reduce the workload of the company’s larger bladder press- es has been a familiar tune in the aero- space-fabrication world, says Cecil Sterne, vice president of sales for Pryer Technology Group. Pryer manufactur- ers exactly the type of presses See and his coworkers at Piper envisioned. Cer- tain models from its line of 5000- and 10,000-psi Triform presses cycle in as little as 15 sec., as is the case with Piper’s new Triform Model 16-5BD.
“While big presses such as the Ver- son Wheelon and Asea models at Piper allow you to form 15 or 20 parts in one cycle,” says Sterne, “the lengthy setup and cycle times yield fewer parts/hr. than we typically see with the Triform presses. And, we also see other manufacturers experiencing similar issues to what Piper is experi- encing regarding maintenance—aging bladder presses undergoing more frequent and costly maintenance
around the world have long
relied on sheet-hydroforming presses—fluid-cell and rubber-pad styles—for economic production of low-volume parts. Rubber-pad forming in a hydraulic press took flight (so to speak) in the 1930s and ’40s. In the 1950s and ’60s came fluid-cell tech- nology, which replaced the rubber-pad upper forming tool with a thin and flexible rubber fluid-filled diaphragm. Fluid-cell capabilities surpassed those of traditional rubber-pad forming, pro- viding more consistent results with evenly applied pressure over every square inch of the part.
To learn how the fluid-cell hydro- forming process has evolved since those early days, we spoke with Piper Aircraft, Inc., which operates a 754,000- sq.-ft. manufacturing plant in Vero Beach, FL. The plant—of which 280,000 sq. ft. is dedicated to fabrication and forming operations—has long operat- ed a pair of huge and aging fluid-cell presses, an 800-ton Verson Wheelon and an Asea (now Avure) 1000-ton
versatile for fabricating a variety of air- frame parts and skins of all shapes and sizes, primarily of Type 2024 aluminum sheet 0.020 to 0.125 in. thick. Alu- minum alloy 2024 is an age-harden- ing alloy that contains 3.8-4.9 Cu, 1.21.8 Mg, 0.5 Si and 0.3-0.9 Mn, and boasts a tensile strength of 68,000 PSI, yield strength of 47,000 PSI and an elonga- tion of 20 percent in 2 in.
As Piper’s Asea press began to show its age, beginning around 2008, main- tenance technicians were required to replace the bladder every 12 to 18 months—an expense engineers quick- ly found annoying and disruptive.
“That press uses two large trays, each 30 by 92 in., and has a large, expensive bladder that can take as long as a week to replace,” says Piper man- ufacturing engineer Chris See. “In addi- tion, the time to pressurize such a large press leads to forming-cycle times as high as 90 sec. We thought it would make sense (going back to late 2010) to investigate purchasing a smaller sheet- hydroforming press to run smaller
22 MetalForming/April 2012
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