When the wear ring in the approach angle of a wire drawing die becomes too deep, it causes the coating to be loosened and stretching and further ringing results. Just when to service dies has to be determined by experience and use in the mill. It is advisable to clean and examine dies each time they are taken out of a machine. The greatest amount of wear will occur in the first few hundred kilograms of wire drawn through the die, thereafter the die becomes work and lubricated, and the rate of wear per tonne reduce to a uniform factor related to miles passing a point per minute and the hardness of the material drawn.
Next operation after wire drawing is stranding. Two types of stranded are employed-the sun and planet type and the tubular type. In the former, bobbins or spools of wire are charged in two or more cages which can be rotated independently in either direction. As the machine operates the cage revolve round the central wire which moves forward and layers of wire are formed on the central wire which move forward and layer of wire. For alternate layers the cages are rotated in the opposite direction. In the tubular type straddler, bobbins are carried in candles inside a tube. In the usual stranding operation a single wire is used as the base; it is wound first with six wires followed by multiples of six in the consequent operations. Sometimes a tranded conductor containing wires is employed as base. Stranded conductors are designated by numbers such as 13/2.11, the first number indicating the total number of wire in the strand and the second the diameter of the wire in mm.
First article of AAC/ACSR Conductor
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