GB2438267A

GB2438267A - Apparatus for cooling of coiled steel rod

Info

Publication number: GB2438267A
Application number: GB0609993A
Authority: GB
Inventors: Andrew James Douglas; John David Massingham
Original assignee: Corus UK Ltd
Current assignee: Corus UK Ltd
Priority date: 2006-05-19
Filing date: 2006-05-19
Publication date: 2007-11-21
Also published as: GB0609993D0

Abstract

Apparatus for cooling steel rod comprises means for laying the rod in overlapping rings (2, Fig. 2), means 5 for conveying the overlapped rings and cooling means 7-11 for blowing a cooling gas upwardly through the overlapped rings. The cooling means comprises a nozzle 8 which has means such as a perforated barrier 12 for reducing the velocity of the cooling gas directed towards the central part of the overlapped rings relative to the velocity of the cooling gas directed towards the edges of the overlapped rings. The nozzle may divided by walls 11, thereby having a plurality of inlets 9 and outlets 10. The perforated barrier is preferably positioned at or near the inlets and can be retro-fitted to existing cooling apparatus.

Description

APPARATUS FOR COOLING STEEL ROD AND METHOD OF MANUFACTURING

SUCH AN APPARATUS

The invention relates to an apparatus for cooling steel rod and a method of manufacturing such an apparatus.

Steel rod is manufactured by deforming a hot steel usemifl, normally billet or small bloom feedstock, in a hot rolling mill. The steel rod is cooled after rolling.

In a known apparatus, this is done by blowing cooling air upwardly on to the steel rod as it is conveyed on a conveyor. For a given steel composition, the final metallurgical properties of the rod are critically dependent on the rate of cooling after rolling. Higher rates of cooling give higher levels of tensile strength and many rolling mills use high velocity air blown from below the rod to achieve the cooling rates required. However, as the steel rod is deposited on the conveyor in overlapping rings, the density of steel rod is greater at the edges of the conveyor than it is in the centre of the conveyor. This results in less effective cooling at the edges of the conveyor, a problem which can be overcome by directing the cooling air through a nozzle having a larger outlet at the edges of the conveyor than in the central region of the conveyor. This means that the steel rod at the edges of the conveyor is exposed to the cooling air for longer than the steel rod in the central region of the conveyor. Another problem, particularly with small diameter rod, is that a limit is reached whereby the rod is lifted off the conveyor by the force of the air impacting from below. This causes operational problems and must be avoided.

It is an object of the invention to seek to mitigate this problem.

According to a first aspect, the invention provides apparatus for cooling steel rod, the apparatus comprising laying means for laying the steel rod in overlapping rings, conveyor means for conveying the overlapping rings of steel rod, cooling means for blowing a cooling gas upwardly through the overlapping rings of steel rod, the cooling means comprising a nozzle for directing the cooling gas towards the steel rod, the nozzle comprising means for reducing the velocity of the cooling gas which is directed towards the central region of the conveyor.

The term "central region" as used herein means that area of the conveyor which, in use, lies beneath the rings, excluding the area at the each edge of the conveyor where the rings overlap.

In the known apparatus, the velocity of the cooling gas is substantially constant across the width of the conveyor. The applicant has found that by reducing the velocity of the cooling gas which is directed towards the central region of the conveyor, lifting of the steel rod is reduced, but cooling is maintained at the edges of the conveyor, where it is most important.

The velocity reducing means may comprise a perforated barrier. The perforated barrier may be positioned in the central region of the nozzle. Such a velocity reducing means is inexpensive, and is readily installed in an existing cooling apparatus.

The nozzle may comprise one or more inlets and outlets, the perforated barrier being positioned at or near the inlet(s) of the nozzle. If the perforated barrier is positioned at or near the inlet(s) of the nozzle, then it will be possible to achieve a more uniform air velocity profile at the nozzle outlet.

The nozzle may comprise a plurality of inlets and outlets, the inlets and outlets being provided by dividers positioned inside the nozzle.

The percentage of open area in the perforated barrier may be in the range 10-50%, preferably in the range 15-35%.

The outlet(s) may be substantially open. Leaving the outlet(s) substantially open makes it possible to achieve a more uniform air velocity profile at the nozzle outlet.

The cooling means may comprise a fan and a guide means for directing the cooling gas from the fan to the nozzle. As the velocity reducing means is positioned in the nozzle, the fan and guide means may be the same as in the known apparatus. This means that there is no need for modification of the fan and guide means when converting the known apparatus into the apparatus of the invention.

According to a second aspect, the invention provides a method for manufacturing an apparatus for cooling steel rod, the method comprising the step of modifying a nozzle of an existing cooling means for directing a cooling gas towards steel rod so that it is no longer arranged so that it directs gas at a substantially constant velocity, but instead directs gas towards the central region of the conveyor at a reduced velocity.

The invention will now be illustrated by way of example with reference to the following drawings of which: Figure 1 shows a side view of a known apparatus for cooling steel rod; Figure 2 shows a cross-sectional side view of part of the apparatus of Figure 1; Figure 3 shows a plan view of the outlets of a nozzle of the apparatus of Figure 1; Figure 4 shows a plan view of the outlets of a nozzle according to the invention; Figure 5 shows a photograph of the outlets of a nozzle according to the invention; and Figure 6 shows a photograph of the inlets of a nozzle according to the invention.

The apparatus shown in Figures 1 to 3 comprises a laying head (1) for laying steel rod in overlapping rings (2) or waps" on to a conveyor (3), which conveys the ring (2) of steel rod to a reform tub (4) which forms the rings (2) of steel rod into coils.

The conveyor (3) comprises a plurality of rollers (5). Beneath the rollers (5) are a plurality of fans (6) each of which blows cooling air via a plenum chamber (7) and a nozzle (8) on to the rings (2) of steel rod.

Each nozzle (8) comprises a plurality of nozzle inlets (9) and a plurality of nozzle outlets (10). The nozzle inlets and outlets (9, 10) are formed by a plurality of dividers (11) positioned inside the nozzle (8). The nozzles are designed for high aerodynamic efficiency, acting to accelerate the air from the plenum chamber (7) such that it impacts the lower surface of the rings (2) of steel rod at optimum velocity.

As can be seen from Figure 3, the density of steel rod at the edges of the conveyor (3) is greater than the density of steel rod in the central region of the conveyor (3). Also, the nozzle outlets (10) have a greater area at the edges of the nozzle (8) than in the central region of the nozzle (8). This means that the steel rod at the edges of the conveyor (3) is exposed to the cooling air for longer than the steel rod in the central region, thereby compensating for the greater density of steel rod at the edges of the conveyor (3).

A problem with the known apparatus shown in Figures 1 to 3 is that, particularly with small diameter steel rod, high velocity cooling air results in the rod being lifted off the conveyor, which causes operational problems.

The apparatus of the invention is the same as the known apparatus shown in Figures 1 to 3 apart from the design of the nozzle.

Figures 4 to 6 show a nozzle according to the invention. As can be seen, the nozzle outlets (10) have the same area across the full width of the nozzle.

In addition, a perforated metal sheet (12) is positioned over the inlets (9) in the central region of the nozzle (8).

This means that, unlike the known apparatus shown in Figures 1 to 3 where velocity of the cooling air is substantially constant across the width of the conveyor, the velocity of the cooling air is reduced in the central region of the nozzle, so that the velocity of the cooling air which is directed towards the central region of the conveyor is reduced, thereby reducing lifting of the steel rod, while maintaining cooling at the edges of the conveyor.

Claims

CLAIMS

1. Apparatus for cooling steel rod, the apparatus comprising laying means for laying the steel rod in overlapping rings, conveyor means for conveying the overlapping rings of steel rod, cooling means for blowing a cooling gas upwardly through the overlapping steel rings of rod, the cooling means comprising a nozzle for directing the cooling gas towards the steel rod, the nozzle comprising means for reducing the velocity of the cooling gas which is directed towards the central region of the conveyor.

2. Apparatus accordingly to claim 1, wherein the velocity reducing means comprises a perforated barrier positioned in the central region of the nozzle.

3. Apparatus according to claim 2, wherein the nozzle comprises one or more inlets and outlets, the perforated barrier being positioned at or near the inlet(s) of the nozzle.

4. Apparatus according to claim 3, wherein the nozzle comprises a plurality of inlets and outlets, the inlets and outlets being provided by dividers positioned inside the nozzle.

5. Apparatus according to claim 3 or claim 4, the outlet(s) being substantially open.

6. Apparatus according to any of claims 2 to 5, the percentage of open area in the perforated barrier being in the range 1O-50%.

7. Apparatus according to claim 6, wherein the percentage of open area in the perforated barrier is in the range 15-35%.

8. Apparatus according to any preceding claim, the cooling means comprising a fan and a guide means for directing the cooling gas from the fan to the nozzle.

9. Apparatus for cooling steel rod substantially as described herein or as shown in the drawings.

10. Method for manufacturing an apparatus for cooling steel rod, the method comprising the step of modifying a nozzle of an existing cooling means for directing a cooling gas towards the steel rod so that it is no longer arranged so that it directs gas at a substantially constant velocity, but instead directs gas towards the central region of the conveyor at a reduced velocity.