Tuesday, February 13, 2001
Augsburg, Germany--Landing its first production application
at the Augsburg plant of the European Aeronautic Defense and Space Company
(EADS), a new patented three-axis spindle carrier from DS Technologie (DST) GmbH
(Monchengladbach, Germany) has been busy making center-section components for
the new Eurofighter fuselage.
EADS Leader of NC Programming Alfred Lilla says that the new
spindle carrier's parallel kinematics contributed to a 30-50% reduction in
production time compared to gimbal-type heads. Other advantages he cites include
improved surface finish, greater accuracy, better reliability, and a more
compact design.
For engineers it means designing new types of floor beams, wing
ribs, and fuselage frames. Now, instead of building up structural components
from an assembly of plates, angles, channels, and fasteners, airframe designers
think in terms of larger, single-piece, monolithic structures. Using larger
parts yields stronger, more reliable, and lower-cost designs.
Cincinnati Machine (www.cinmach.com) recently formed a strategic
alliance to incorporate the DST head into its HyperMach™ line of
high-performance machines for the aerospace industry. Through this alliance the
giant U.S. machine tool manufacturer sells and supports DST technology,
including the new spindle carrier, which it calls the Z3 Head.
The Z3 Head differs from gimbal or contouring-style heads
typically used in 5-axis milling in that it doesn't rely on its host machine to
provide Z-axis travel. Instead, it supplies its own Z-axis motion using three
parallel ballscrew drives connected to the spindle housing by universal joints
from INA (www.ina.com). Moving all three
ballscrews simultaneously creates the traditional Z path, while moving them
differentially creates A and B-axis motion.
"By eliminating the whole-head rotation, which typically slows
down fork-type [gimbal] head operation, the Z3 head moves the tool to any point
within the workspace more quickly. And it eliminates rotary couplings and slip
rings to simplify the design, reduce cost and maintenance, and improve
reliability," says Dr. Norbert Hennes, design and development chief at DST.
While DST may hold the patent, the Z3's 14-month development time
from concept to full production was a team effort. EADS and DST, together with
Siemens (www.siemens.com) and subsidiary
company RTS (Real Time Software GmbH) of Schwieberdingen, developed a Siemens
840D CNC-based control concept that uses Heidenhain (www.heidenhain.com) encoders for position
feedback.
"It's nothing new to have a tripod," Hennes explains, "but
combining a hinge joint on one end of each linear axis with a universal joint on
the other end creates an extra degree of freedom. That's what makes our tripod
design unique."
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