Page 32 - MetalForming January 2017

Not Your Father’s Feeder
his insight into what today’s press feeds can do.
Servo-Motor Performance Spells Improved Feeding
“Years ago, when servo motors debuted, metalformers buying servo- driven press feeds were trying to solve the problems they had in their tooling, and a servo feed was not always a fix,” Crider recalls. “If a mechanically driven unit had a problem feeding accurately, chances are the servo did, too.”
Then again, back then servo motors were no bargains themselves.
“Servo drives were unstable or not tuned correctly for the material run- ning through them,” says Crider. “That caused problems with accuracy and stability. But over the years, servo sup- pliers have gotten much better at pro- viding motors with accurate control— the resolution of the servo motor, how accurately it can be positioned, and how easily it can be tuned.”
The newer generations of servo
motors also are much heartier.
“On a stamping press, a feeder is subjected to a lot of shaking and vibra- tion, and must perform in all kinds of nasty environments,” Crider continues. “The encoder systems on servo motors have become more robust, as have the motors themselves, to better handle
that shock and vibration.”
The increased use of gag tooling in
presses, where material must be indexed in multiple, not just single, fixed lengths, owes to improved servo- motor performance and the advances in the resolution of encoders within those motors.
“By alternating the indexing lengths, unique actions can be performed in the tooling, allowing additional processes to occur in the press,” Crider says. “That indexing is controlled by the feeder, allowing punching to occur in sequence with the indexing.
“With a standard progressive die where feed length does not vary,” he continues, “pilot pins in the die locate
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the part material. But as soon as a stamper is running multiple feed lengths, the process must rely on feeder accuracy to control material placement and ensure part accuracy.”
Improved Controls, Communication Ease Press-Line Fit
“Feeders now can talk to the press control and share information, and incor- porate job and tool storage,” notes Crider. “From the press control, feeders can be programmed for index length, when to index and a host of other parameters, all set and available for recall.
“We always are asked about increas- ing capacity for job storage,” he con- tinues. “Before, an operator would dial in a feed length and set acceleration and the feeder would be ready. Now, when the job number is called up on the press control, feed parameters change automatically.”
This ability makes newer press feeds ideal components in press lines tasked
mechanical and CNC vertslides to produce
a variety of metal and wire formed parts from simple stampings to complicated assemblies using a multitude of options such as tapping, welding, and automated assembly. Represented in North America by Gibraltar Corp.