| GCR Eurodraw SpA, Italy, has developed a full range of cleaning equipment for installation in-line with wire drawing machines. Of particular interest are the company�s electrolytic cleaning units for the production of lubricant-free wire, including welding wire, stainless steel wire to be annealed, plating-quality wire for the tyre industry and for other plating process. These units can be used with both dry and wet drawing machines, to clean the wire and take off remaining lubricant before spooling or coiling. The cleaning unit consists of a multi-section working tank mounted over a storage and recycling tank. The working principle is electrolytic, usually with a sodium hydroxide degreasing solution, although other cleaning agents can also be used.
The end sections of the working tank contain grooved turrets and the middle section contains the cleaning solution. The wire is wound back and forth around the turrets more or less times, to vary the length immersed in the solution, depending on diameter and speed. The walls between the middle and end sections have two vertical slits through which the wire passes and are designed to prevent the escape of solution. The middle section contains cells with electrodes that, without coming into contact with the wire, charge the wire itself with alternate polarities through the degreasing solution. The gaseous development of the electrolysis on the wire surface provokes the small particles of lubricant to crack-off within a couple of seconds. The electrolytic unit is also equipped with a recycling pump and current rectifier and a heating/cooling system when necessary.
The cleaning unit is followed by a double rinse, where wires pass through a series of channels in which heat and/or water is circulated under pressure at high-speed. This creates turbulence that considerably increases efficiency of the unit. The working channels are mounted on a double "cascade" recycling tank that operates on the principle of progressive dilution. In other words, the first section has a higher concentration of polluting agents than the second section. Some water from the second section is directed to the cleaning unit to compensate for evaporation and to minimise discharge of polluted water. The water can be heated via electrical resistance or with steam or hot water coils. After rinsing, the wire is dried with compressed air blowers and wire squeezers, to assure perfect drying before take-up. Electrolytic units efficiently clean low or high-carbon steel wire, as well as stainless steel wire or special alloys. They are manufactured in different sizes for wire diameters ranging from 0.50 to 3.50mm. Cleaning speed depends on the wire diameter, the submerged length and the type of lubricant to be removed.
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