Page 18 - MetalForming May 2009

Rollforming
The entry end of this rollforming line contains a prenotching press (at left) to produce variable hole patterns in the strip. That necessitates gag dies near the press feeds and a modulating drive on the straightener (center) to feed the loop.
Demands More from Coil Handling
Longer than Traditional Stamping Lines
Rollforming lines occupy more floor space than typical stamping lines owing to multiple roll stands used to form long products, with cutoff equipment at the end of the line adding to length. Entry- end equipment on rollforming lines also are longer than their stamping brethren, especially where prenotching and other processes occur prior to rollforming.
“A line may contain an uncoiler and straightener with a material loop lead- ing to the servo feeder,” Pennuto explains. “In a rollforming line with a prenotching station for instance, it is necessary to place another material loop between the prenotching press and the rollformer. Why? Though the rollformer forms product at a relatively constant speed, strip travels at varied speeds into and out of the straightener and through the prenotching press, so both of those areas need slack to enable constant strip speed down the line. That translates to a longer line footprint.”
Required strip slack may necessitate a pit to provide a significant material loop, more than an above-floor loop can provide.
Coil-handling equipment may offer other features to meet the unique require- ments of rollforming. For example,
The long feed lengths, and the starting and stopping due to inline operations prior to rollforming, make careful attention to coil handling a must.
BY LOUIS A. KREN, SENIOR EDITOR
Plain and simple, rollforming is a dif- ferent animal. The process strays from typical stamping as it demands long feed lengths and often an excessive amount of starts and stops as a variety of notching, punching and other tasks occupy the line prior to the actual roll- forming process. All of this demands much from coil-handling equipment on the entry end, according to Jack Pennu- to Jr. of Formtek, Inc., Cleveland, OH, a supplier of rollforming equipment including feeds and even entire lines.
Programmable Servo Feeds Ideal
Programmable servo feeds enable precise starts and stops as well as the varying, and sometimes exceedingly long, feed lengths.
“Servo feeds offer the ability to turn on and off features within an overall prepunching, prenotching die—air- actuated gagging features, for example —to allow programming of a pattern along a longer-length product,” Pennu- to explains. “To do that, the servo feeds require output signals to activate and deactivate air cylinders or manifolds.”
The ideal rollforming line also would require either a straightener for a heav- ier-gauge product or powered uncloil- er for lighter-gauge products, both with variable-speed or modulated drives to speed up and slow down to match large variations in feed length.
And of course, feed systems designed with rollforming in mind do not limit users with regard to product length.
16 METALFORMING / MAY 2009
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