Page 16 - MetalForming May 2009

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Lean
Error-proofing concepts for toolmakers and die designers
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to really fine-tune the draw at its deep- est point, between 12 and 14 in.,” says Quinn. The press is rated for a maxi- mum draw of 16 in.
In addition to dynamic cushion con- trol, another key feature of OCC’s new hydraulic press is four-corner active leveling. Beckwood application and sales engineer Darrell Harrelson explains how the feature works and what it means to OCC’s applications.
“Linear transducers mounted at each of the four corners of the press send position signals to a motion controller (from Delta Computer Systems, Van- couver, WA). The controller manages the data to control proportional valves in each of the four hydraulic cylinders to maintain bed parallelism, critical during off-center loading conditions.”
When does OCC load its press off- center? “This occurs when forming the oddly shaped gas-tank halves,” Harrel- son continues. “The tear-dropped shape of the tanks generates substantially more load on one side of the press bed than the other. Without active leveling at all four corners of the press, this off- center loading would stress the guide bushings, possibly bend the pusher pins or otherwise damage the die. The diemaker would have to look at the part and locate the centerline, then shift the part in the press to even out the load on the press.”
Last but Not Least: A Green Machine
The last press feature noted by Har- relson is its use of a variable-frequen- cy drive, growing in industry accept- ance as a way to “green” the stamping process. When the press is not run- ning—and the nature of OCC’s limit- ed run sizes causes a lot of downtime— the drive consumes only 50 percent of its rated energy, slowing from 1800 rpm during drawing to 900 rpm during idle time.
“This speed reduction conserves energy,” says Harrelson, “and also reduces heat in the hydraulic system and reduces sound level. Generally, pay- back for this feature comes in less than 4 yr. in terms of energy savings.” MF
DieProtection for
Manufacturing By Drew Stevens
Hydraulic Press