WCA January 2011
The object is to present profiled material to the strander. The round wire is re-shaped into the optimum format for the desired strand con- struction and finished cable size. This roll form system can be as simple as a two-layer (1+6) construction or as intricate as a five-layer (1+6+12+18+24) construction. The scope of the strand design determines the application confi- guration; there are many different designs available for each layer. (a) Roll forming of the input wires. This is achieved with a driven roll stand shaping each wire in a layer to a precisely designed shape. (b) Round wire layers where a number of round wires are closed without any change in section. Depending on the strand design, up to four layers of roll forming strand may be produced. Each roll strand is driven individually, allowing slight changes in speed to be made at each position to compensate for the variances in the spiral length.
Figure 1 ❍ ❍ : Close up of roll formers
Figure 2 ❍ ❍ : Roll form unit and closing point
Single input wire schedules
Compact
Six wire sizes required using a conventional system One wire size required using SIW system
Figure 3 ❍ ❍
It further allows more precise distribution of wire tension in each layer, optimising the straightness of the resulting conductor. The shaped conductors are formed into a compact unilay strand using a high-speed double twist strander. The machine is a side-loading unit equipped with a standard floor loader, designed to load and unload the take-up reel with minimum operator effort.
The scope of products that can be manufactured includes: Copper and aluminium stranded conductors between • 8AWG and 600kcmil or 10mm 2 and 300mm 2 Bunched conductors to compact strand with fill factors • between 76% and 97% Aluminium conductors steel reinforced (ACSR) using • a single steel wire core All aluminium and aluminium alloy conductors (AAC • & AAAC) Cabling of insulated conductors •
Figure 4 ❍ ❍ : Process cost/twist comparison
$ Planetary Strander Planetary Strander
$ Rigid Strander Rigid Strander
$ Drum Twister
Capital cost/ Twist
$ Tubular Strander
$
Double twist Strander Double Twist Strander
Tubular Strander
Drum Twister
Factors
Capital cost/twist
1
3-5
7-16
9-12
16-24
“Working factor”
Significant (rigid)
Almost none (planetary)
Significant (rigid)
Significant (rigid)
Almost none (planetary)
Lay limitations
Unilay only
Not applicable
None
None
None
Layer limitations
Up to 4 layers
2 layers
None
None
None
Typical payoff package
Stem
Bobbin
Stem
Bobbin
Bobbin
Required loading cycle
Required loading cycle
Required loading cycle
Continuous
Payoff mode
Continuous
64
Wire & Cable ASIA – September/October 2007 January/February 2011
Made with FlippingBook