EuroWire March 2015

Corporatenews

The evolution of trolley wire manufacturing ▲ ▲ Innovation and technology from Cortinovis Sictra

All of this implied a redesign of the Sictra trolley wire integrated drawing line. A modern line capable of drawing Cu Mg 0.5 alloy is usually made of four capstans, the first two with 1,200mm diameter and the last two with 1,000mm diameter. The AC motors provide adequate torque to the capstans to match the higher rod tensile strength of the new alloys and the increased breaking load of the final product. More often the line is designed with five capstans (2 x 1,200mm and 3 x 1,000mm) to be able to draw down copper alloy rod with inlet diameter up to 30mm. The process and the increased powers involved in it require an efficient capstan cooling system via inside chilled water circulation and rotating joints. Wire lubrication and additional cooling is provided with emulsion spray on the capstans’ surface and most efficient lubrication of the round and shaped dies is achieved with specific oil circulation and die holders’ chilled water cooling. All of this requires three separate cooling and circulating circuits. Cortinovis Sictra – Italy Website : www.trafcomachinery.com

It soon became evident to the Industry that competing in the manufacture of trolley wires was no longer possible unless the equipment in use was up to date. The product itself was subject to a significant evolution. The drives of this development have been environmental protection on one side and the increase of operation speed of the railways on the other side. For a long time, copper was utilised for trolley wire alloyed with cadmium. The presence of cadmium gives to copper a much higher resistance to softening at elevated temperatures and also to arc erosion, as extremely heat resistant cadmium oxide forms on the surface of the wire during arcing and protects it from eroding. Cadmium, however, is very toxic, even more than lead or mercury, therefore it has been replaced for this application by other metals to be alloyed with copper. Nowadays the most utilised copper alloys for high-speed trains granting operating speed up to 400km/hour are copper and magnesium alloys; wear and tear is the lowest, while breaking load the highest. Silver copper and tin copper alloys are also used.

Among wire and cable machinery suppliers, Cortinovis and Sictra are recognised for the advanced technology of their products and equipment reliability. Many users with machinery from decades ago are still using their equipment, counting on the continuous supply of original spare parts from Cortinovis Sictra when they are needed. It was at the beginning of the 1980s when Sictra developed its first integrated drawing line for shaped trolley wires, and the development of high-speed railways was still to come. At that time, it was common practice to draw the shaped trolley wires utilising a single deck bull block, with which the rod was drawn down with several subsequent passages until the shaped wire final cross section was achieved. The design and construction from Sictra of an integrated drawing line with four capstans represented a dramatic improvement. Productivity increased by a factor of ten while manpower requirement reduced. Not only that, but the scrap rate was also reduced significantly and the quality of the final product enhanced.

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March 2015