Page 37 - MetalForming-May-2018-issue

Advantages of
Servo-Hydraulic
Presses
...include significantly less energy and
maintenance needs than traditional hydraulic machines, quicker acceleration and deceleration, and more.
Find out what these new presses can do, and why.
BY LOUIS A. KREN, SENIOR EDITOR
Developments in stamping-press technology since the North American introduction of mechanical-servo presses at the turn of the 21st century have continued unabat- ed. Newer materials, and newer meth- ods to form these materials, boosted by the need for parts designed with safety and weight in mind, have driven the press-innovation trend. So, what’s next?
How about servo-hydraulic presses? Servo drives deliver benefits now famil- iar in the industry, and those benefits have migrated over to hydraulic-press platforms. The technology’s relative newness deserves a close look into just what it can do for metalformers.
Toward that end, AP&T (www.apt- group.com) provided MetalForming with an overview of servo-hydraulic press technology and its benefits, along with some details on development of the company’s own hydraulic test press.
As servo-mechanical presses have shown, the addition of servo-motor drives and controls enable program- mability for stroke movement and
force. Precisely dialed-in settings can customize a press for each particular job, tool and material, and allow for new ways to form new materials.
Traditionally, mechanical and hydraulic presses each have offered specific benefits, with mechanicals pro- viding higher stroke speed, simpler set up and maintenance, and high repeata- bility. Hydraulic presses deliver full energy throughout the press stroke along with freely programmable slide motion and energy control. Introduc- ing servo motors into the hydraulic- press equation retains the stated advantages, with plenty more added.
About 10 years ago, AP&T studied the idea of controlling hydraulic presses less via hydraulic means and more through the use of electric motors, offers Patrik Haglund, the company’s product manager for presses, and Troy Hamilton, sales account manager. This arose from energy losses that long have been seen as a disadvantage in hydraulic-press use—from the drive system’s motor-pump operation and
from the hydraulic system, including pipes, valves and the main cylinder.
Improved Drive Technology Drives Development
“Ten years ago,” explains Haglund, “the big drives needed for our hydraulic-press applications—motors that don’t run continuously but can be controlled in a high-performance man- ner and which are key to energy savings and improved performance—were too expensive or did not exist.”
Taking a new look at the studies when Haglund became product man- ager in 2014, AP&T found improved drive technology and developed its own press ideas, and thus an economic case to develop servo-hydraulic press- es. The rise in automotive applications for high-strength aluminum also con- tributed to development of these press- es. Forming high-strength aluminum requires relatively high press speeds and high accuracy, notes Haglund, but running hydraulic presses at higher
www.metalformingmagazine.com
MetalForming/May 2018 35