Page 34 - MetalForming August 2012

Servo-Drive Presses
that the cages are actually suspended in mid-air,” says Osborne. “You can see it on the video. The cages immediately lose their timing and position. In this scenario, the ball bearings are forced into a ‘skid’ condition, causing the guide components to overheat and eventually scoring the guide pin and bushing.”
inal TDC and BDC positions. Certain measures must be taken to guard against cage creep.
Help is on the Way
has been done and the press is on the upstroke, you’re sometimes at the mercy of the cam’s slide-return sys- tem,” Osborne says. “Stripping force is critical; give the springs enough time to work. Upstroke too quickly and you can prematurely wear, or even break, punches. Yes, this can occur in a con- ventional press, but the situation is exacerbated with a servo-drive press and the temptation to crank up the speed after BDC.
As described above, equipment sup- pliers must find ways to support stam- pers that take the leap to servo-drive presses. And guide components are no exception. To address the retainer-cage issue described by Osborne, he told us of a patent-pending prototype guidance system Anchor Danly has in field testing that prevents the cage from ever being in freefall.
There are options for dealing with
this condition, explains Osborne, in
particular changing the length of the
guide pin or bushing to ensure the ball
bearings unload as close to TDC as
possible. Or, the stamper can select a
combination of components that
ensures some bearings are always
under preload—commonly referred to
as Type 1 operation. But, as many stam-
pers know (particularly those working
in the high-speed canning industry),
Type 1 operation often can lead to a
phenomenon called “cage creep.” This,
explains Osborne, refers to the ten-
dency of a rolling-element retainer sound practice: will lead you down, but from 180 to cage to gradually deviate from its nom- “With cam-slide units, after the work 360 deg., watch that speed limit. MF
In light of this pending solution, Osborne simply suggests that stam- pers developing procedures for servo- drive presses be mindful of any rapid acceleration from BDC. Instead, they should gradually accelerate to full speed on the upstroke, over 10 to 20 deg. of ram motion. He explains addi- tional reasons why this makes for
“The suggestion is to wait until the cam completely disengages and the tooling completely extracts before hit- ting the accelerator,” Osborne contin- ues. “Then go ahead and accelerate up. The same holds true when per- forming in-die tapping. When you rap- idly accelerate up from BDC, you place additional undue strain on the mech- anism.”
Servo Press Technology Experience
Final warning: Enjoy the exciting, winding road that servo-drive presses
TM
MetalForming magazine is offering executives, engineers and metalforming professionals an opportunity to learn about the latest developments in servo presses at the Servo Press Technology Experience. Participate in the entire experience, which includes a live event at PMA’s headquarters in Cleveland, OH, and a series of 3 free webinars, or sign up just for the individual webinars. It’s your choice—the full package or a la carte.
Free Webinar I: Servo Press Technology—Applications for Today and Tomorrow Thursday, August 23, 2:00 – 3:00 p.m. EST
Featured speaker: Dr. Taylan Altan, professor & director, Center for Precision Forming, The Ohio State University, Columbus, OH
Free Webinar II: Applications for Servo Presses—Drawing, In-Die Secondary Operations, etc. Thursday, August 30, 2:00 – 3:00 p.m. EST
Featured speakers: Rob Bauer, Engineering Manager, Waukesha Metal Products;
Jim Landowski, General Manager, Komatsu America Industries
Free Webinar III: Marrying Your Servo Press to a Metalforming System— Considerations for Controls and Feeds
Thursday, September 6, 2:00 – 3:00 p.m. EST
Featured speakers: Jim Finnerty, Wintriss Controls; Willie Chacko, Dallas Industries; Jim Ward, Coe Press Equipment
LIVE EVENT
September 19, Cleveland, OH (PMA headquarters)
Cost:$49.00 • 8a.m.to12p.m.
An in-depth look at servo-press technology with case-study presentations and breakout sessions with press builders/sponsors in private conference rooms.
Sponsored by:
www.metalformingmagazine.com/servo
6363 Oak Tree Blvd. | Independence, OH 44131 216/901-8800 | fax 216/901-9669
e-mail: metalforming@pma.org
Interested in sponsoring? Contact Andrew Flando, aflando@pma.org
The Official Publication of
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