METHOD AND EQUIPMENT FOR CONTROLLED PATENTING OF STEEL WIRE

Abstract

A method of continuous controlled cooling of a plurality of heated steel wires having a diameter larger than 2.8 mm and having an austenite microstructure and of transformation to a pearlite microstructure of the steel wires. The method comprises the steps of: a) Providing a first coolant bath comprising a first coolant liquid. The first coolant liquid comprises water and a stabilizing additive. b) Guiding the plurality of previously heated steel wires parallel to each other along individual paths through the first coolant liquid contained in the first coolant bath; and directing impinging liquid immersed inside the first coolant bath towards each of the steel wires over a certain length L. The impinging liquid decreases the thickness of or destabilizes the steam film around each of the plurality of steel wires, resulting in an increase of the speed of cooling over said length L. The intensity of the impinging liquids is individually set and/or controlled for each individual steel wire or for subsets of the plurality of steel wires. c) Guiding the plurality of steel wires parallel to each other through air for further cooling.

Claims

1-15. (canceled)

16. A method of continuous controlled cooling of a plurality of heated steel wires having an austenite microstructure and of transformation to a pearlite microstructure of the steel wires, wherein the plurality of steel wires comprises steel wires having a diameter larger than 2.8 mm; the method comprises the steps of: a) providing a first coolant bath, wherein the first coolant bath comprises a first coolant liquid, wherein the first coolant liquid comprises water and a stabilizing additive, b) guiding the plurality of previously heated steel wires parallel to each other along individual paths through the first coolant liquid contained in the first coolant bath, and directing impinging liquid immersed inside the first coolant bath towards each of the steel wires over a certain length L; wherein the impinging liquid decreases the thickness of or destabilizes the steam film around each of the plurality of steel wires, thereby increasing the speed of cooling over said length L; wherein the intensity of the impinging liquids is individually set and/or controlled for each individual steel wire or for subsets of the plurality of steel wires; c) guiding the plurality of steel wires parallel to each other through air for further cooling.

17. Method as in claim 16, comprising after cooling the plurality of steel wire in the first coolant bath by means of the impinging liquidthe additional step of guiding the plurality of steel wires along individual paths parallel to each other through a second coolant bath; wherein the second coolant bath comprises a second coolant liquid, wherein the second coolant liquid comprises water and a stabilizing additive.

18. Method as in claim 17, wherein an air gap is provided between the first coolant bath and the second coolant bath, such that the plurality of steel wires is cooled by air in between the first coolant bath and the second coolant bath.

19. Method as in claim 17, wherein the first coolant bath and the second coolant bath are the same bath.

20. Method as in claim 16, wherein the intensity of the impinging liquid is individually set and/or controlled for each individual steel wire of for subsets of the plurality of steel wires, by means of setting and/or controlling the flow rate of the liquid flows creating the impinging liquids.

21. Method as in claim 20, wherein one or a plurality of sensors are provided, wherein control of the intensity of the impinging liquids for each individual steel wire or for subsets of the plurality of steel wires is provided by means of a measurement by the one or the plurality of sensors for or at each individual steel wire; or for or at subsets of the plurality of steel wires; and setting of or feedback control to the flow rate of the liquid flows creating the impinging liquids using the measured signals and a controller.

22. Method as in claim 21, wherein the sensor or sensors comprise pressure sensors or flow sensors, and wherein the pressure sensors are provided for measurement of the liquid pressure at the nozzles creating the impinging liquids, or wherein the flow sensors are provided for measurement of the flow at the nozzles creating the impinging liquids; and wherein the sensor measurements are used for setting of or feedback control of the flow rate of the liquid flows creating the impinging liquids.

23. Method as in claim 16, wherein one or a plurality of magnetic sensors are provided to measure the magnetic response of one or of subsets of the steel wires; and to provide feedback to adapt in a closed loop control the impinging liquids in the first coolant bath.

24. Method as in claim 16, wherein the first coolant bath is provided with partitioning walls separating the steel wires or the subsets of steel wires in the first coolant bath along the full length of the steel wires along which the steam film around the steel wires is affected by the impinging liquids.

25. Method as in claim 16, wherein the impinging liquid is immersed below each steel wire itself along each individual path; or wherein the impinging liquid is immersed partially below some of the plurality of steel wires along their individual paths.

26. Method as in claim 16, wherein the length of the individual paths of each of the steel wires through the first coolant bath and/or through the second coolant bath is adjustable.

27. Method as in claim 16, wherein the speed of the steel wires through the continuous process is individually adjustable in order to optimize the transformation of each of the steel wires in function of their diameter and/or alloy composition.

28. Method as in claim 17, wherein the steam film created in the second coolant bath around each of the steel wires is undisturbed.

29. Method as in claim 16, wherein the length through which each of the steel wires runs through the first coolant bath is the same.

30. Equipment for performing the method as in claim 16, comprising a first coolant bath for comprising a first coolant liquid, means for guiding the plurality of previously heated steel wires parallel to each other along individual paths through the coolant liquid contained in the first coolant bath, impinging liquid generator(s) immersed inside the first coolant bath(s), wherein the impinging liquid generator(s) are adapted to direct impinging liquid towards the steel wires over a certain length L; means for individually setting or controlling the intensity of the impinging liquids for each individual steel wire or for subsets of the plurality of steel wires; means for guiding the plurality of steel wires parallel to each other through air for further cooling.

Description

BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS

[0041] FIG. 1 illustrates an example of the invention.

[0042] FIG. 2 shows a cross section along line II-II of FIG. 1.

MODE(S) FOR CARRYING OUT THE INVENTION

[0043] FIG. 1 illustrates an example of a preferred method and equipment according to the present invention. FIG. 2 shows a cross section along line II-II of FIG. 1. The cooling length with impinging liquid in the first coolant bath (CB1) is fixed. The first coolant bath comprises a first coolant liquid. The first coolant liquid comprises water and a stabilizing additive. The first coolant liquid in the first coolant bath has a temperature of more than 80 C. A short air gap (AG) has been added to separate the first coolant bath (CB1) and the second coolant bath (CB2). The second coolant bath (CB2) is adjustable in length. The second coolant bath comprises a second coolant liquid; which has in this example the same composition and the same temperature as the first coolant liquid. No turbulence is present in the second coolant bath; the steam film created in the second coolant bath around each of the steel wires is undisturbed. Laminar flow of coolant liquid is present in the second coolant baths, ensuring refreshment of coolant liquid in the second coolant baths. The first coolant bath is provided with partitioning walls separating the first coolant bath in different lanes; each subset of steel wires is treated in a separate lane (or even one single steel wire per lane). Preferably, as shown in FIG. 1, in the first coolant baths, the impinging liquid generators and the air gaps along each individual path have a fixed length and the length of the second coolant baths is adjustable for each of the subsets of steel wires. A plurality of steel wires is patented at the same time, parallel to each other. The intensity of the impinging liquids in the first coolant bath is individually set and controlled in each lane, thus for each subset of steel wires.

[0044] As shown in FIG. 2which shows a cross section along line II-II of FIG. 1, steel wires 10 are led out of a furnace 12 having a temperature T of about 1000 C. The wire running speed can be adjusted according to the diameter of the wire, e.g. about 20 m/min. The first coolant bath 14 of an overflow-type is situated immediately downstream the furnace 12; the steel wire is led between partitioning walls in the first coolant bath. A plurality of jets 16 from the holes 20 of a perforated plate 22 immersed inside the first coolant bath are forming an impinging liquid, whose flow rate is set and controlled by a circulation pump and control system 18 outside the first coolant bath. The cooling rate is adjusted by tuning the coolant flow by means of the pressure in front of the jets, via control of the pumps providing the liquid flow for the impinging jets. To this end, pressure sensors can be used at the perforated plate to measure the coolant liquid pressure; the measurement signal can be used in a closed feedback control system towards the pump generating the liquid flow for that subset of steel wires. The flow rate can be set individually for each subset of steel wires. The flow rate of the jets for forced cooling and the length of air gap region are so chosen as to avoid the formation of martensite or bainite. The partitioning walls can be provided vertically; and positioned onto the perforated plate and attached onto the plate to avoid that impinging jets acting on one subset of wires in a lane affect the boiling film present on steel wires in another lane, meaning in another subset of steel wires. The impinging liquid under pressure from the holes 20 is jetting towards the steel wire 10. As illustrated in FIG. 2, the first length L.sub.1 is the distance from the exit of furnace 12 to the impinging liquid. The second length L.sub.2 indicates the length used for forced coolant cooling processforced coolant cooling lengthin the first coolant bath. The steel wire 10 is then led out of the first coolant bath and subjected to an air gap region with a length L.sub.4 as indicated in FIG. 2. Thereafter, the steel wire 10 is guided into a second coolant bath 17 to further cool down. The immersion length of the steel wire 10 in the second coolant bath 17 is indicated as L.sub.5. The length L.sub.5 can be variable depending on the diameter and the desired tensile strength of the steel wire 10. After the second coolant bath, the steel wires are guided through air to be further cooled.