Page 18 - MetalForming January 2012

Unwinding the Coil
Another version of the coil-reel concept is the double- ended version (Fig. 4), featuring two mandrels facing in opposite directions, with a rotating head. This style suits applications requiring quick coil changes, since the empty mandrel can be reloaded with a fresh coil while the other mandrel runs. With the addition of dual-holddown arms, double-ended reels also gain favor for running partial coils.
Yet another option is the dual-cone or double-stub-arbor version, typically used only for very wide coils or for heavy coils with small inside diameters. Here, a mandrel is insert- ed into both ends of the coil for support. This style, howev- er, can carry a high purchase price, as the metalformer basi- cally must purchase two complete traveling-reel assemblies with stubby mandrels.
Pallet Decoiler/Pan Reel
The third type of unwinder is the pallet decoiler, or pan reel. This style typically finds use only with coils of narrow, light-gauge materials. Using this style, the metalformer lays the coils on their sides and stacks them on a pallet placed on a motorized turntable for unwinding. The top coil runs first and when complete, the next coil in the stack can immedi- ately be threaded without actually having to load a coil. The range of material width and thickness is limited, since the

Fig. 4—The double-ended coil reel features
two mandrels facing in opposite directions, with
a rotating head. This style suits applications requiring quick coil changes.
strip must make the transition from vertical to horizontal as it unwinds.
Advantages of this style include its efficiency in terms of run time between reloading, minimal floor-space require- ments and fairly low purchase price. Pallet decoilers often get the call in applications where straightening is not required or in conjunction with a free-standing powered straightener or a pull-through straightener at the feed. MF
16 MetalForming/January 2012
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