Page 22 - MetalForming-Aug-2018-issue

Developments in Motors, Drives and Controls
“Yes, the long-emerging servo-press technology has taken hold,” Barry stresses, “providing trackable improve- ments in press performance, product complexity and output, in addition to noise and energy reduction. However, updating existing presses with the latest drives and controls also can provide additional, measureable improvements in production and reliability. You’re either going to make more parts, run
at the same rate but stop less frequent- ly, or, when production does pause, you can bring the machine back up and running more quickly due to better diagnostics.”
Better Servo Motors and Drives
The bullet-point list of recent tech- nology enhancements to drivetrain components promising pressroom advantages:
• New servo motors, which feature radically improved accuracy and pro- vide the ability to apply maximum torque at any point in the ram descent to BDC;
• Regenerative drives, which can apply cyclic ram-action power savings to other components or back to the grid; and
• Positioning encoders, which signal power and positioning requirements more accurately than ever.
“Drives themselves are getting smaller, providing more power in less space,” Barry says. “One-cable tech- nology is another biggie gaining momentum. Instead of separate power and feedback cables that run in and around the press cell, we see that migrating to one cable.”
With regenerative drives, “you get your most bang for the buck on the big stuff—big flywheel drives, for exam- ple,” Barry notes. “For example, we’re working through some projects with a major press supplier and one of the Big 3 automotive companies to retrofit several older AC main press motors with fully regenerative drives. At first look, such a project might appear as spending more money than necessary. But the faster you’re able to stop the ram by using a newer regenerative drive, the better we can capture the stored power and send it back to the line. Over time, the cost savings can be significant.
“In fact, regarding the above-men- tioned Big 3 project,” Barry continues, “we originally pitched non-regenerative drives but the customer said, ‘as often as we start-stop these presses, we want to capture that stored energy and reuse it/send it back to the line.’ We’re starting to see this more as shops become more energy-conscious.”
Barry also notes the increased inter- est in regenerative drives on other equipment in sheetmetal-processing lines—tension levelers for example— where shops have retrofitted fully regenerative drives and common bus systems and can share the load within the line. “So, a shop might be process- ing the strip with one motor developing
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20 MetalForming/August 2018
www.metalformingmagazine.com
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