GB2146278A

GB2146278A - Cooling hot-rolled elongate stock

Info

Publication number: GB2146278A
Application number: GB08422704A
Authority: GB
Inventors: Arthur Edward Cooper
Original assignee: ASHLOW Ltd
Current assignee: ASHLOW Ltd
Priority date: 1983-09-10
Filing date: 1984-09-07
Publication date: 1985-04-17
Also published as: EP0141511A1; GB8324292D0; JPS6076215A; GB2146278B; GB8422704D0

Description

1 GB 2 146 278A 1

SPECIFICATION

Apparatus for and method of cooling elongate stock This invention relates to a method of and apparatus for cooling elongate stock, such as wire rod, after hot rolling in a rolling mill.

Wire rod from a hot rolling mill is conveni- ently cooled by a passage through a series of cooling zones in each of which the rod is passed through a cooling tube into which liquid coolant is injected and, at the downstream end of the cooling tube there is a stripper injector which directs liquid coolant in a direction so as to strip coolant from the wire rod emerging from the cooling tube. Generally, in each zone, there is at least one further cooling tube into which liquid coolant is in- jected, upstream of said first mentioned cooling tube. Such an arrangement is shown in German specification OS 2151210.

In this, and all similar arrangements, after the tail end of a length of rod has passed through the tube or tubes of a zone, and before the nose end of a next following length of rod can be permitted to enter the tube or tubes, any liquid coolant remaining in the or each tube must have drained out. This is because at high speeds of operation if the nose end of the next following wire rod were to encounter water in a tube, a cobble would occur.

The period of time which must be allowed for any coolant present in the tube or tubes to drain therefrom limits the rate of production.

It is accordingly one object of the present invention to provide a new or improved apparatus for cooling elongate stock, such as wire rod after hot rolling which permits of increase in the rate of production compared with that hitherto obtainable.

According to one aspect of the present invention, we provide an apparatus for cooling elongate stock after hot rolling in a rolling mill 110 comprising a cooling zone having a cooling tube, a coolant injector to inject liquid coolant into the cooling tube, means downstream of the cooling tube to strip the liquid coolant from the stock wherein a purge injector is provided to inject a gaseous fluid into the cooling tube to displace liquid coolant therefrom.

Thus the injection of gaseous fluid causes any liquid coolant remaining in the cooling tube when the injection of coolant has ceased, to be positively purged from the cooling tube rather than merely allowing the liquid to drain therefrom. This allows for the period of time between feeding lengths of stock to be reduced thereby increasing production rates.

The purge injector is preferably provided downstream of the coolant injector, in which case the purge injector for introducing the gaseous fluid into the cooling tube may be adjacent the upstream end thereof.

The gaseous fluid may be injected into the cooling tube in a direction lying in a conical surface, the apex of the cone pointing in the downstream direction although alternative arrangements are no doubt possible.

Alternatively, the purge injector may be provided in combination with the coolant injector, means being provided to permit of substitution of the gaseous fluid supply used for purging with a liquid coolant supply used for cooling.

Alternatively, where the means to strip the liquid coolant from the stock comprises a stripper injector which injects a fluid, such as a liquid, in an upstream direction, the purge injector may be provided in combination with the stripper injector.

The stripper fluid could comprise a gaseous fluid, but where the stripper fluid is a liquid, means are required to permit of substitution of the gaseous fluid supply used for purging with a liquid fluid supply used for stripping.

A guide tube may be provided downstream of said cooling tube but upstream of the stripper means and a second purge injector may be provided to inject a gaseous fluid into the guide tube to displace liquid coolant therefrom.

The second purge injector may be provided at the downstream end of the guide tube and the gaseous fluid may be injected by the second purge injector in a direction lying in a conical surface, the apex of the cone pointing in an upstream direction.

A further guide tube may be provided downstream of said stripper means and a further purge injector may be provided to inject a gaseous fluid into the -stripper--- guide tube to displace liquid coolant therefrom.

Gaseous fluid may be introduced into the further guide tube adjacent the upstream end thereof.

Again, the gaseous fluid may be introduced into the further guide tube in a direction lying in a conical surface, the apex of the cone pointing in the downstream direction.

The or each purge injector may comprise a manifold extending around, for example surrounding, or partly surrounding, an associated cooling or guide tube and there may be a plurality of passages extending through the wall of the tube to permit of passage of gaseous fluid from the manifold to the interior the tube, the passages each having a central axis lying on said conical surface.

The cooling zone may include at least one further cooling tube and associated coolant injector and first purge injector, upstream of said first mentioned cooling tube.

In that case, an intermediate guide tube may be positioned downstream of the additional cooling tube, the intermediate guide tube being provided with a purge injector as 2 GB 2146 278A 2 defined above.

A plurality of cooling zones may be pro vided in series.

A rolling mill may be positioned upstream of the cooling zone or zones and where the stock is wire, a coil former and a cooling conveyor downstream of the cooling zone or zones.

According to another aspect of the inven tion, we provide a method of cooling elongate stock after hot rooling in a rolling mill corn prising the steps of passing the stock through a cooling tube, injecting liquid coolant into the cooling tube at an upstream end thereof, stripping the coolant from the stock at the downstream end of the cooling tube, terminat ing the injection of liquid coolant approxi mately as the tail end of the stock leaves the rolling mill, injecting a gaseous fluid into the cooling tube to displace liquid coolant there from.

The fluid may be injected in an upstream direction to strip liquid coolant from the stock, and the injection of liquid coolant may be re started as the nose end of a new length of stock is subsequently fed through the thus cleared tube at high speed.

Preferably, the injection of liquid coolant is re-started after the nose end of the length of stock leaves the cooling tube.

The invention will now be described in more detail by way of example, with reference to the accompanying drawings, wherein:

Figure 1 is a diagrammatic side elevation of a wire rod cooling line; Figure 2 is a diagrammatic side elevation, to an enlarged scale, of one of the cooling zones of the line of Fig. 1; Figure 3 is a cross-sectional view, to an enlarged scale, of part of the zone of Fig. 2; 105 and Figure 4 is a cross-sectional view, to an enlarged scale, of another part of the zone of Fig. 2.

Referring to the drawings, a rod cooling line 110 comprises a series of five cooling zones Z1 5. If desired, the number of cooling zones may be more or less than five. In the present example, each cooling zone is similar and hence only one cooling zone, i.e. that identi- 115 fied at Z2 in Fig. 1, will be described in detail with reference to Fig. 2.

The cooling zone shown in Fig. 2 has a cooling tube 10 and an associated liquid coolant injector 11 at the upstream end of the 120 cooling tube 10. Downstream of the cooling tube 10 is a guide tube 14, and further downstream of the tube 10 is a stripper injector 12. Still further downstream is a further tube 13.

Upstream of the cooling tube 10 and associated liquid coolant injector 11 is an additional cooling tube 1 Oa and associated liquid coolant injector 11 a, as well as a further guide tube 14a between the further cooling tube 1 Oa and coolant injector 11, as well as a still further guide tube 1 4b upstream of the coolant injector 11 a.

Thus in the present example, the cooling zone Z2 shown in Fig. 2 has two cooling tubes 10, 1 Oa and associated liquid coolant injectors 11, 11 a respectively, together with a single stripper injector 12. If desired, the cooling zone Z2 could contain only the cool- ing tube 10 and associated injector 11 together with the stripper 12. Alternatively, further additional cooling tubes and associated coolant injectors with, as required, intermediate guide tubes, may be provided upstream of the cooling tube 1 Oa.

Also, if desired, different ones of the cooling zones Z1 to Z5 may have a different number of cooling tubes and associated coolant injectors.

The series of cooling zones Z1 -Z5 are provided, in the example described, downstream of the last stand S of a hot rolling finishing mill and upstream of a coil former F and cooling conveyor C on which the coils are laid.

Adjacent the upstream end of the cooling tube 10 there is provided a first air purge injector 15 positioned as close as practicable to the coolant injector 11. A second air purge injector 17 is provided at the downstream end of the guide tube 14 whilst a still further air purge injector 16 is provided at the upstream end of the guide tube 13.

An air purge injector 1 5a analogous to the purge injector 15 is provided at the upstream end of the cooling tube 1 Oa and purge injectors 17 a, 17 b, analogous to the injector 17, are provided at the downstream ends of the guide tubes 14a, 14b respectively.

Each of the cooling tubes 10, 1 Oa, and associated liquid coolant injectors 11, 11 a are similar, purge injectors 15, 1 5a, 16, are similar and purge injectors 17, 17 a, 17 b are similar, and hence only cooling tube 10 and purge injectors 15 and 17 will hereinafter be described with reference to Figs. 3 and 4.

In the present example, cooling tube 10, in addition to guide tube 13 and 14 each have an internal diameter of 1 9mm and the wire rod to be cooled may have a diameter lying anywhere in the range 5mm to 16mm. If desired, the cooling and guide tubes may have an internal diameter lying the range 12mm to 25mm.

The liquid coolan injector 11 provided at the upstream end of the tube 10 comprises a cylindrical body 20 within which is defined a generally annular in cross-section manifold 21 to which liquid coolant, in the present example water, is fed via an inlet 22. A sleeve 23 is removably and adjustably mounted at the upstream end of the body 20 by means of a screw-threaded connection 23a and has an internal passage 24 of 20mm diameter. The diameter of the passage 24 can be varied to 3 GB 2 146 278A 3 suit varying rod sizes. Typically, the following relationship between rod dameter and the diameter of passage 24 is arranged:- Rod Diameter Passage Diameter 5.Omm- 8.5mm 15mm 8.5mm-1 2.5mm 20mm 12.5mm-16mrn 25mm The above mentioned typical figures ensure that there is a minimum difference of 6mm in total between the diameter of rod and the 80 sleeve.

The external surface of the sleeve 23 at the downstream thereof is frusto-conical as indi cated at 25 and co-operates with a frusto conical recess 26 of a further sleeve 27 which is received in the body 20 by means of a further screw threaded connection as indi cated at 28. As a result, a conical passage 29 is provided between the surfaces 25 and 26, the width of which can be adjusted by axial movement of the sleeve 23 by virtue of the threaded connection 23a and typically the width of the passageway lies in the range 0.5mm to 6mm. The apex angle of the coni cal passage 29 is 10' but may lie in the range 5' to 40'. The sleeve 27 has a cylindri cal inlet passage 29a of a diameter related to the wire rod diameter in the same way as the internal passage 24 as mentioned above. Of course, any alternative form of coolant injector could be provided in place of either or both of the injectors 11, 11 a if required.

Downstream of the coolant injector 11, and as close as practicable thereto, is provided the purge injector 15 which comprises a generally cylindrical body 31 having end walls 32 aper tured to receive the pipe 10 and providing an annular in cross-section reservoir 33 to which gaseous fluid under pressure is fed via an inlet 34. Thus the purge injector 15 extends completely around the tube 10, but may only partly surround the tube 10 where a different construction is used.

The cooling tube itself 10 is provided within the reservoir 33, with a plurality of circumfer entially disposed inlet passages 35 each of which has a central axis 36 which lies on a conical surface, the apex of which points downstream, and has an apex angle of 45, and may lie in the range 20' to 60.

The stripper injector 12, as shown in Fig.

4, is similar to the liquid coolant injector 11 except that the parts thereof are orientated in the reverse direction so that the conical space 29' converges in an upstream direction and 125 thus as liquid is injected, this has the effect of stripping liquid coolant from the wire rod in the region indicated at 40 between the strip per injector 12 and tail end of the upstream guide tube 14. Thus when, in use, liquid 130 coolant, leaves the frusto-conical space 29', it moves in a direction having a component extending upstream of the cooling line and thus serves to strip liquid coolant surrounding the wire rod as it emerges from the upstream guide tube 14.

At the downstream end of the guide tube 14, a purge injector 17 is provided which is similar to the purge injectors 15, 1 5a and 16 described hereinbefore but in this case, the guide tube 14 is formed with cylindrical passages 35a having central axes 36a lying on a conical surface, the apex of which points upstream and again having an apex angle of 45' but which may lie in the range of 20 to 60'.

The guide tubes 14a, 14b are identical to the cooling guide tube 14.

In use of the apparatus, wire rod leaves the last stand 5 of a hot rolling finishing mill at a temperature of approximately 1 0OWC and emerges from the downstream end of the cooling line, i.e. cooling zone Z5, at approximately 75WC. The wire rod as it leaves the finishing mill, may attain a speed of 100 metres per second or may even exceed this speed and the time interval between rolling billets in the rolling mill is approximately five seconds. In this five second interval, as the tail end of a wire rod leaves the last stand S, the passage of the tail end is detected, by conventional means, to provide a signal to cause the liquid coolant supply to the coolant injectors 11, 11 a and stripper injector 12 to be interrupted. If desired, means may be provided to detect the egress of the tail end from each cooling tube 10, 1 Oa and for the liquid coolant to be cut off progressively downstream but the above described proce- dure of interrupting all the coolant of all the zones as the tail end of the wire rod leaves the last stand S is conventional practice.

In a conventional arrangement, coolant remaining within the cooling tubes 10, 1 Oa and guide tube 14, 14a, 14b must drain from the tubes, for example through the gaps shown at G and 40 between adjacent tubes, before the nose end of the next following wire rod can be introduced into the cooling line, and thus a relatively long time delay of five seconds must be allowed.

In accordance with the present invention, the signal provided by the leaving of the tail end of the wire rod from the stand S not only causes interruption of the cooland supply to injectors 11, 11 a but also initiates the supply of gaseous fluid, i.e. air under pressure, into the purge injectors 15, 15 a, 16, 17 17 a, 1 7b to drive coolant from within the tubes 10, 10a, 13, 14, 14a, 14b. In the present example the air pressure is 90 p.s.i, but may lie in the range 30 p.s.i. to 100 p.s.i.

As a result of the present invention, the time interval between the rolling of billets can be reduced to the order of three seconds and 4 GB 2 146 278A 4 this results in increase in the production rate by approximately 5%, which is a significant improvement. In addition, any risk of cobbles due to coolant being accidentally present in the cooling tubes 10, 1 Oa or guide tubes 14, 14a, 14b, 13 as a result of a leak is reduced.

Besides positively driving coolant from the tubes, the purge injectors also ensure that any debris, such as scale, is driven from the tubes.

As the nose end of a new length of wire rod leaves the most upstream cooling tube 1 Oa of the first zone Z1, it provides a signal to re start the coolant supply to the injector 11 a and this is repeated progressively as the nose end progresses down the cooling line, so that the coolant supply is only initiated as the nose end enters the next downstream cooling tube thereby ensuring that the nose end has passed completely through a cooling tube 85 before any coolant is supplied.

Of course, if desired, some other means for re-starting coolant supply may be adopted, for example a signal may be provided to supply the coolant to all the coolant injectors at the zone simultaneously as the nose end leaves the downstream end of the cooling zone but this would result in a longer nose portion requiring to be scrapped.

In the present example, the coolant has 95 been described as water and the purge fluid as air. If desired other coolant liquid than water may be used, such as a mixture of water and lubricant. or cooling oil alone, and a gaseous fluid other than air may be used, such as nitrogen, for purging.

Although in the pesent example separate purge injectors have been described, it is envisaged that one or more of the separate purge injectors may be provided combined with a coolant injector, or the stripper injector. In each case means would be required whereby the supply of liquid for cooling or stripping may be substituted by gaseous purge fluid, when appropriate.

However, it is also envisaged that a gaseous fluid could be used for stripping, rather than a liquid fluid, in which case, such substitution means may not be required.

Any alternative means for stripping liquid 115 coolant from the wire rod could be provided instead of the liquid or gaseous fluid stripping means described.

Although the invention has been described in relation to cooling wire rod, the invention 120 may be used for cooling other elongate stock, as required.

Claims

1. Apparatus for cooling elongate stock after hot rolling in a rolling mill comprising a cooling zone having a cooling tube, a coolant injector to inject liquid coolant into the cooling tube, means downstream of the cooling tube to strip the liquid coolant from the stock 130 wherein a purge injector is provided to inject a gaseous fluid into the cooling tube to displace liquid coolant therefrom.

2. Apparatus according to Claim 1 wherein the purge injector is provided downstream of the coolant injector.

3. Apparatus according to Claim 1 or Claim 2 wherein the purge injector for introducing the gaseous fluid into the cooling tube is adjacent the upstream end thereof.

4. Apparatus according to Claim 3 wherein the gaseous fluid is injected into the cooling tube in a direction lying in a conical surface, the apex of the cone pointing in the downstream direction.

5. Apparatus according to Claim 1 or Claim 2 wherein the purge injector is provided in combination with the coolant injector, means being provided to permit of substitution of the gaseous fluid supply used for purging with a liquid coolant used for cooling.

6. Apparatus according to any one of the preceding claims wherein said means to strip the liquid coolant from the stock comprises a stripper injector which injects a stripper fluid in an upstream direction.

7. Apparatus according to Claim 6 wherein the purge injector is provided in combination with the stripper injector.

8. Apparatus according to Claim 6 or Claim 7 wherein the stripper fluid is a liquid filuid.

9. Apparatus according to Claim 8 where appendant to Claim 6 wherein means are provided to permit of substitution of the gaseous fluid supply used for purging with a liquid fluid supply used for stripping.

10. Apparatus according to any one of the preceding claims wherein a guide tube is provided downstream of said cooling tube but upstream of the stripper means, a second purge injector being provided to inject a gaseous fluid into the guide tube to displace liquid coolant therefrom.

11. Apparatus according to Claim 10 wherein the second purge injector is provided at the downstream end of the guide tube.

12. Apparatus according to Claim 11 wherein the gaseous fluid is injected by the second purge injector in a direction lying in a conical surface, the apex of the cone pointing in an upstream direction.

13. Apparatus according to any one of Claims 10 to 12 wherein a further guide tube is provided downstream of said stripper means and a further purge injector is provided to inject a gaseous fluid into the further guide tube to displace liquid coolant therefrom.

14. Apparatus according to Claim 13 wherein gaseous fluid is introduced into the further guide tube adjacent the upstream end thereof.

15. Apparaus according to Claim 14 wherein the gaseous fluid is introduced into the further guide tube in a direction lying in a conical surface, the apex of the cone pointing in the downstream direction.

16. Apparatus according to any one of the preceding claims wherein the or each purge injector comprises a manifold extending around an associated cooling or guide tube and there being a plurality of passages extending through the wall of the tube to permit of passage of gaseous fluid from the manifold to the interior of the tube, the passages each having a central axis lying on a conical surface.

17. Apparatus according to any one of the preceding claims wherein the cooling zone includes at least one further cooling tube and associated coolant injector and first purge injector, upstream of said first mentioned cooling tube.

18. Apparatus according to Claim 17 wherein an intermediate guide tube is positioned downstream of the cooling tube, the intermediate guide tube having a purge injector.

19. Apparatus according to any one of the preceding claims wherein a plurality of cooling zones are provided in series.

20. Apparatus according to any one of the preceding claims wherein a rolling mill is positioned upstream of the cooling zone or zones and the stock is wire rod, a coil former and a cooling conveyor being provided downstream of the cooling zone or zones.

21. Apparatus for cooling wire rod substantially as hereinbefore described with refer- ence to and shown in the accompanying drawings.

22. A method of cooling elongate stock after hot rolling in a rolling mill comprising the steps of passing the stock through a cooling tube, injecting liquid coolant into the cooling tube of an upstream end thereof, striping the coolant from the stock at the downstream end of the cooling tube, terminating the injection of liquid coolant approxi- mately as the tail end of the stock leaves the rolling mill, injecting a gaseous fluid into the cooling tube to displace liquid coolant therefrom.

23. A method according to Claim 22 wherein fluid is injected in an upstream direction to strip liquid coolant from the stock.

24. A method according to Claim 22 or Claim 23 wherein the injection of liquid coolant is re-started as the nose end of a new length of stock is subsequently fed through the cooling tube.

25. A method according to Claim 24 wherein liquid coolant is re-started after the nose end of the new length of stock leaves the cooling tube.

26, A method of cooling substantially as hereinbefore described with reference to the accompanying drawings.

27. Any novel feature or novel combina- tion of features disclosed herein and/or GB 2 146 278A 5 shown in the accompanying drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office Dd 8818935. 1985 4235 Published at The Patent Office 25 Southampton Buildings London, WC2A 'I AV from which copies may be obtained