Page 36 - MetalForming November 2012

Tooling Technology
Cushions Part of the Servo Revolution
Adecade after arriving on North American shores, servo-drive mechanical presses truly are tak- ing over. Automotive OEMs are installing the machines in plants across the land, with their tier suppliers, and even job shops, following suit.
To complement servo presses, man- ufacturers have unveiled servo-con- trolled cushions. The cushions provide flexibility and controllability, allowing metalformers to dial-in and fluctuate pressure on downstrokes and upstrokes, thus aiding in precision forming and drawing while nearly eliminating the evils of reverse tonnage.
“Automotive manufacturers and press builders see servo technology as the next big innovation in the industry and have embraced it,” says applica- tions engineer Darrell Quander Jr., of Hyson, Brecksville, OH. “The flexibili- ty and controllability in servo-con- trolled hydraulic cushions complement
servo-press
flexibility and controllability
—the idea with servo presses is to fine- tune the process and servo-controlled cushions do the same. Stampers can dial force up or down to move the cush- ion prior to the die actually contacting it, decreasing press wear. And, built-in adjustable-force profiles add flexibili- ty where, before, only one cushion pres-
sure was available. Now we can change pressures on the fly as the servo press changes characteristics on the fly.”
New hydraulic cushions employing servo control have already entered the field.
“One automotive OEM recently switched to servo presses to avoid hav- ing to tweak each press after a die change, spending weeks making it right and scrapping a lot of material in the process,” says Michael Culbertson, Hyson senior project engineer. “Com- bining the presses with the new cush- ions allows even greater force control to ease job setup and increase produc-
tion of quality parts. For example, during forming, the cushion can adjust pressure
A screenshot from a press-cushion control panel shows how operators and man- agement can monitor and control cushion functions to best assist the press during part forming.
Designed to complement servo presses, servo- controlled hydraulic cushions promise fine-tuning
to produce better parts, save presses from shock, reduce scrap and tame tough steels.
BY LOUIS A. KREN, CONTRIBUTING EDITOR
This illustration depicts a servo-controlled hydraulic cushion with double-acting cylinders, linear transducers and pressure
transducers. The unit can be stud-mounted to the bottom of a press bolster.
34 MetalForming/November 2012
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