EoW November 2010

technical article

Reducing cost in manufacturing compact conductors using roll

form stranding by Sean Harrington, sales and marketing manager for Ceeco Bartell Products Abstract

Process steps

The roll form stranding process combines the advantages of two highly productive processes, namely roll forming and double- twist stranding. These two systems are forged together to create one high-speed continuous manufacturing cell. This system not only produces compact strand at high speeds, but also allows significant savings to be made throughout the stranding process, from wiredrawing all the way through to the extrusion process. Introduction Recent years have presented a great challenge to the cable industry, especially through the current world recession when demand for cable has reduced, in some cases, by 50 per cent. At the same time raw material prices and energy costs have continued to rise. This has made the competition between manufacturers increasingly aggressive in terms of product range, product quality and costs. The aim of this paper is to present a cost saving technological solution for the wire drawing process. This is the use of the roll form strander, which allows the use of a single input diameter wire to be utilised throughout the stranding process giving significant process savings and advantages, including: Higher stranding productivity (typically I. 40 tonne/day compact Al) Higher productivity in wire drawing II. Lower drawn wire scrap III. Lower insulating costs IV. Lower capital investment V. Improved return on investment VI. Quicker set-up VII. Reduced work in process VIII. Shorter cycle times IX. Smaller input wire storage area X. 75% more energy efficient than a XI. typical rigid strander

Double twist

Roll forming

Coil payoff

Assembly into compact conductor

Roll formed profiles

Round wire

Process steps ▲ ▲

The object is to present profiled material to the strander. The round wire is re-shaped into the optimum format for the desired strand construction 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 configu- ration; 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.

The roll form stranding process combines the advantages of two highly productive processes: roll forming of shaped wire and double twist stranding of conductors. These two systems are forged together to create one high-speed continuous manufacturing cell. This system not only produces compact strand at high speeds, but also allows significant savings to be made throughout the stranding process, from wire drawing through to the extrusion process. Round wire is paid off from stem-type payoff packages allowing up to 1,000kg (2,000lb) of aluminium or 3,000kg (6,000lb) of copper conductor material to be staged behind the roll form strander. The stem package allows continuous operation and is the preferred solution for this process, maximising productivity when the single input wire method is an integral part of the manufacturing process. The round wire passes into the external roll forming section, an integral part of the roll form strander.

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EuroWire – November 2010