WCA May 2013

Niehoff multiwire drawing technology

The machine can be operated using drawing oil or drawing emulsion, and two drawing compound feed systems can be attached. The machine is also equipped with a suction unit for removing oil dust from the drawing chamber, which is returned to the drawing compound circulation system by a return path. The machine is plugged with an RMA 201 type continuous resistance annealer specially designed for round aluminium and aluminium alloy wire with single driven contact pulleys working under protective gas. Annealing is realised by the two-zone annealing principle, which promotes the economical and ecological consumption of annealing current. Annealing paths have been kept short, and the entire wire path right up to the end of the annealing process is completely encapsulated from the outside to prevent oxidation on the wire surface. Nitrogen is used as protective atmosphere. To provide the best match between wire throughput speed and the different properties of the wire alloys, every contact sheave is driven by its own AC motor. An automatic cleaning device for the contact pulleys and further constructive features regarding the wire path ensure a long service life of the contact pulleys. The individually cooled wires leave the annealer with a residual lubrication layer and can be spooled directly onto plastic spools, eg, the spools of the Niehoff Package System (NPS). Because of their lubrication the wires can be paid-off at high speeds without risk of damages. An MMH 104 / RMA 201 drawing line is designed to draw simultaneously 8 or 16 wires with a maximum wire feed diameter of 2.5mm in 23 drafts to a finish diameter of 0.15 to 0.60mm. The maximum operating speed is 36m/s. In the case of 16 wires, the wires can be split to 8 plus 8, 7 plus 7 or 16 wires on one spooler. The further processing of the wires can be realised on Niehoff’s double-twist bunching machines of the D series. A typical line for the pre-stranding of the individual components for battery cables is composed of three pay-offs for 800mm spools, 2 x 16 wires and 1 x 8 wires (16 + 16 + 8), plus one D 801 double-twist bunching machine specially adapted for the manufacturing of aluminium wires. Maschinenfabrik Niehoff GmbH & Co KG – Germany Website : www.niehoff.de

There is an increasing demand for wires made of aluminium and aluminium alloys. For weight reasons overhead power lines are made of aluminium wire, mostly reinforced with steel or composite material wires. In order to reduce weight and to replace the expensive copper material, also in the automotive industry aluminium and aluminium alloy wires are increasingly in demand. More than ten years ago, Maschinenfabrik Niehoff started to develop both aluminium rod wire drawing technology and aluminium multiwire drawing and annealing technology. Because aluminium oxidises very quickly at higher temperatures if air and moisture are present, Niehoff’s proven copper wire drawing and processing technology required certain process modification. An ideal manufacturing line for the production of both round and trapezoidal-shaped aluminium wires required for overhead power lines is the electronically controlled MSM 85 type rod breakdown machine with integrated RA 501 continuous annealer. The MSM drawing machines were developed to draw wires made of copper or aluminium, and their respective alloys, as well as other special materials like superconductor wires to a finish diameter from 1mm to 4.5mm while the RA 501 continuous annealers are specially designed for the inline annealing of aluminium and aluminium alloy wires. The line control system minimises slip throughout the drawing and annealing process. It is also possible to work with different wire elongations for each draft according to the wires’ material, properties and shapes. Capstans not used can be switched off. The total energy consumption of MSM machines is up to 20% lower than conventional rod breakdown machines. The MMH multiwire drawing technology, initially developed for copper wire and introduced to the market in 1985, was also adapted to the characteristics of aluminium. The constructive outcome has been the MMH 104 / RMA 201 type drawing line. One of the differences between the MMH 104 and the MMH version for copper wire is the die holder with drawing capstan spray, which is designed specifically to address aluminium wire drawing requirements.

❍ ❍ MMH 104 / RMA 201 type multiwire drawing line for aluminium and aluminium alloy wires

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Wire & Cable ASIA – May/June 2013