Wire or rod, the former term generally referring to a product of smaller cross-sectional size than the latter, is produced in a rolling mill starting from a relatively massive billet that is typically heated to a high temperature so that it can be plastically deformed. The hot billet is passed through a succession of roll stands that incrementally reduce its cross-sectional size and increase its length, simultaneously imparting good grain structure and ductility to the metal.
At the downstream end of the rolling mill the rolled-out rod or wire is passed, typically after being formed into a multiplicity of fanned-out loops, through a cooling unit. Then the cooled loops are moved by a conveyor to a coil- or bundle-forming device that stacks a predetermined number of the loops up to form annular coils or bundles. The workpiece is cut and the bundles are tied together for transport to the end user. Of course other processes—e.g. galvanizing—can take place upstream.
So as to achieve the appropriate material properties when rolling wire, both thin wire measuring up to about 20 mm in diameter and thick wire or rod measuring up to about 50 mm in diameter are subjected to different cooling processes after exiting the multistand production line of the rolling mill. These processes comprise for thin wire, the so-called Stelmor products, and thick wire, the so-called Garrett products, either standard or forced cooling, for example for medium or high carbon steel and austenite, delayed cooling, for example for low carbon steel, screw steel, spring steel and wrought iron, or slow cooling, for example for tool steel and high-speed steel. These prerequisites can be created by a correspondingly configured cooling section.
U.S. Pat. No. 5,568,744 describes a system of the kind described above for Stelmor cooling of a thin wire, in which wire loops of a wire product that is fanned out on a conveyor are cooled with the help of cooling air and open or closed, or partially open and partially closed, covers or hoods of the cooling section or by means of heat retention pots. The cooling of thick wire wound into coils can be achieved at the ambient air or through fans in the area of the longitudinal transport of the cooling section, by the use of water reels, by adding insulated covers, by means of heat retainers or in insulation chambers. This way it is possible to carry out cooling that meets the requirements of the product, above all when a wide range of properties is desired, as is the case particularly for stainless-steel products.
Downstream of the wire-rolling mill of this known system, a coiler is provided following the cooling unit, in which coiling device the wire loops are removed from a feeder conveyor that is provided as a bridge element between the furthest downstream conveying section of the cooling unit and the coiler. The wire coils formed this way are removed, for example fed to a ring pressing and coiling station with a hook conveyor, and distributed further from there.
The feeder conveyors known in practice are made up of arrays or tables formed by rollers at least some of which are driven, conveyor belts or conveyor chains. These feeder conveyors are anchored to the floor in a stationary manner. In the transition region to the coiler, they are associated with a split roller segment that is a separate component and reaches partially around the coiler and comprises pairs of spaced split rollers. The split roller segment is adjustable in different directions of movement and so are the split rollers. This is supposed to enable a more specific placement of the wire loops in the coiler. The split rollers, which are not single-piece continuous rollers, but instead aligned and spaced pairs of short roller, take care of this. Both rollers of each pair of opposing split rollers has the same short length, and these short lengths become shorter from roller pair to roller pair towards the coiler, that is downstream.
It has been shown during operation that with the known systems the transfer of the wire loops from the cooling unit into the feeder conveyor and from there to the split roller segment that is provided on one side and provided directly upstream of the coiler, is problematic. This is due to the fact that gaps are unavoidable between these components, which gaps negatively influence the structure of the wire loops closely following and overlapping each other, which impairs the feeding and/or placement into the coiler.