Patent ID: 7367208

Claim:
Coil winding method for metal bars after a rolling process which provides, at the rolling mill outlet ( 2 ), the following stages: a) cooling of the bar by means of a first water box ( 4 ′) to a second pre-established temperature higher than the temperature at which martensite begins to form; b) performing equalisation in air up to a temperature of between 800° C. and 880° C. and surface tempering; c) cooling by means of one or more water boxes ( 4 ″, 4 ′″), with the product surface dropping below the temperature at which martensite begins to form; d) performing equalisation in air, after each of said water boxes ( 4 ″, 4 ′″), in corresponding stages, to respective pre-established equalised temperatures, wherein the equalisation, after the last of said water boxes ( 4 ″), is performed up to a temperature of between 600° C. and 700° C.; e) winding of the bar in the form of a compact coil by means of coil winder ( 5 ) at a temperature of between 600° C. and 700° C., wherein a first and a last layer of the coil are wound at a temperature higher than the other coil layers; f) cooling the bar in the form of a coil slowly so as to cause tempering of the bainite and martensite formed on the surface of the bar; g) straightening the bar wound in the form of a compact coil; and h) ageing naturally the bar, by maintaining the bar at ambient temperature.