Page 22 - MetalForming May 2009

Compact Feed Lines
position so that the operator need not wait for the delivery of another coil.
Another more-expensive option is a dual-shifting cradle system, which requires less overall length since the staged coil is placed in a cradle beside the running coil. When the primary coil runs out, the staged coil shifts directly behind the feeder straightener.
Choosing the cradle option, consid-
er these application guidelines:
1) Will marking be a problem? Since the coil is driven by its OD, the stamper runs the risk of marking the material, so a cradle will not suffice when running cosmetic or polished material. Howev- er, when stamping noncosmetic parts or components that will not be seen— such as those mounted on a car or truck
chassis—a cradle will suffice.
Some compact straightener-feeder heads include a closed-loop measuring wheel that provides feedback to the con- troller to indicate actual movement of the material, not just roll rotation. So, for example, if a slug is picked up in the die and the feed rolls slip on the materi- al, closed-loop feedback from the meas- uring wheel can trigger an emergency stop and prevent die damage.
2) Do you typically run partial coils? Once upon a time, before manufactur- ers focused on operating just in time, many would run out an entire coil and store extra parts. Now most metal- formers stop each run after stamping the required number of parts, and then remove and store each partial coil. With a coil resting in the cradle, rewinding it tightly is difficult. However, holding the coil on a reel allows the straighten- er head and holddown arm to work together to rewind the coil tightly so it can be safely and efficiently banded and placed back into stock.
A note about coil-containment safety:
20 METALFORMING / MAY 2009
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