GB2143254A

GB2143254A - Method of and cleaning apparatus for cleaning a strip of metallic material

Info

Publication number: GB2143254A
Application number: GB08417778A
Authority: GB
Inventors: Werner Schimion; Richard Reisinger
Original assignee: SMS Schloemann Siemag AG; Schloemann Siemag AG
Current assignee: SMS Siemag AG
Priority date: 1983-07-13
Filing date: 1984-07-12
Publication date: 1985-02-06
Also published as: DE3325198C2; GB8417778D0; DE3325198A1; FR2549089A1; JPS6064719A

Abstract

A cleaning method for metallic strip, particularly cold-rolled steel strip or fine steel strip, comprises the steps of spraying cleaned emulsion at over 60 bar through spray devices (15 to 18) against the surfaces of the strip (1) with a component directed against its direction of advance, and fresh water or fresh diluted emulsion at a temperature exceeding that of the 21 cleaned emulsion is sprayed at a pressure exceeding 5 bar through spray devices (19, 20) after removal of some or all of the emulsion by squeezing rollers (11, 12). Finally, any liquid left on the strip surfaces is removed by squeezing rollers (13, 14) or by compressed air jets. <IMAGE>

Description

SPECIFICATION Method of and cleaning apparatus for cleaning a strip of metallic material The present invention relates to a method of and cleaning apparatus for cleaning a strip of metallic material, particularly a cold-rolled steel strip or a fine steel strip, such as through spraying of lubricating, cooling or cleaning liquids and/or of pure water behind a last roll stand and/or before a coiling drum.

In the production of metal strips, particularly the rolling of steel strip, contaminants remain on the strip surface after the last roll pass, which contaminants impair succeeding operations and, through defective surface properties, reduce the value of the produced strip. In particular, residues of metal and oil or emulsion may firmly adhere to the strip surfaces and then adhere even more firmly after succeeding annealing processes, so that later expensive cleaning processes may not be capable of providing a complete remedy.

It has been recognised that careful preparation of the employed emulsion and copious spraying of same onto the roll somewhat reduces the contaminants left on the issuing metal strip. According to DE-OS 27 09 979, mechanical cleaning processes employing brushes are carried out to avoid expensive electrolytic cleaning, and warm water, mixed with a wetting or cleaning agent, is fed as coolant or lubricant to the last roll stand without the desired surface cleanliness having been attained.This specification therefore teaches a two-stage process, according to which a wetting agent is at first applied to the surfaces of the metal strip after leaving the last roll stand and fresh water is sprayed in a downstream station against the strip surfaces after the action of the wetting agent, so that the previously applied wetting agent, any adhering roll lubricant and any metal residues are removed simultaneously. It is emphasised in this case that the spraying of fresh water is to take place at a pressure exceeding 5 bar, possibly 8 bar. Alkaline solutions, hydrocarbons and halogenated hyderocarbons are recommended as wetting agents. Apart from the only moderate cleaning effect, the consumption of the wetting agent and the fresh water is high and it is necessary to make provisions for discharge of water.

According to DE-OS 30 28 285, the rolled strip is acted on in front of as well as behind the last roll stand by a cleaning liquid, which has an increased temperature and to which grinding granules, a rust protection agent, a tenside and so forth are admixed, 3 bar being the recommended spraying pressure. Also shown in apparatus which is arranged in front of a coiling drum and in which a cleaning liquid of like kind is sprayed at 20 bar and a 0.2% washing liquid is sprayed in a subsequent step at 100 bar. Although the solution utilised in the first process and that used in the first place in the second process are prepared by being freed of oil, complete cleaning is not possible due to the grinding additives, so that a large part of the rinsed-off contaminants are re-introduced into the washing circuit.When both the solutions are reused cyclically, it is then necessary to continuously renew active components in order to achieve the desired cleaning. It is also a problem that not only is the last roll pair subject to increased wear due to defective lubrication and the intentional addition of a grinding agent, but also corresponding reactions at the strip surface takes place at the same time.

It would thus be desirable to provide a cleaning method which, with a low energy and materials requirement, enables a reliable and almost complete cleaning of metallic strip surfaces.

According to a first aspect of the present invention there is provided a method of cleaning a strip of metallic material, comprising the steps of advancing the strip in a given direction, spraying a cleaning liquid against the major surfaces of the strip at a pressure of at least substantially 60 bar and in a direction having a component counter to the direction of advance of te strip, removing at least part of residual sprayed cleaning liquid from the strip major surfaces, spraying rinsing liquid against the cleaned major surfaces of the strip at a pressure of at least substantially 5 bar, the temperature of the rinsing liquid being higher than that of the cleaning liquid, and removing residual sprayed liquid from the strip major surfaces.

In a preferred example of the method, cleaned emulsion is sprayed at over 60 bar against the surfaces of the strip with a component directed against the running direction and the strip surfaces, after squeezing away of the emulsion, is rinsed by spraying fresh water at a pressure exceeding 5 bar and heated to a temperature above that of the emulsion, any liquid remaining on the surface being subsequently squeezed and/or blown away. Through the use of relatively high pressures preferably between 60 and 140 bar, rinsing away of even relatively firmly adhering contaminants is achieved without need of a liquid requiring special preparation procedures or need of provision for drainage.Any emulsion residues on the strip surfaces in spite of the removal of excess emulsion are rinsed away by clean water, which can be conducted in a circuit and continuously regenerated through supply of further fresh water.

It has proved advantageous to effect spraying of the emulsion, as well as subsequent squeezing removal of the emulsion, several times so that the same cleaning process is repeated. The preparation of the clean water can be carried out by feeding fresh clean water to water conducted in the circuit and collecting and transferring a proportion of the rinsing liquid to a reservoir for the emulsion.

It is also expedient to spray the rinsing liquid onto the strip surfaces with a component directed against the running direction of the strip. The separation of individual spraying and rinsing units can be improved and the workload of squeezing roller pairs reduced if spray jets having an oppositely directed component are arranged in upstream of jets having a component directed against the running direction of the strip. It has proved expedient to operate the upstream spray lets at a lower pressure than the downstream jets. Although the respective spray stages can spray an emulsion heated to at least the temperature of that employed in an associated rolling mill, it is expedient for the rinsing stage to heat this up to a temperature at least 10 to 20 higher.

According to a second aspect of the present invention there is provided cleaning apparatus for cleaning a strip of metallic material, comprising means for advancing the strip in a given direction along a cleaning path, a cleaning liquid spray unit which comprises a pair of cleaning liquid spray devices arranged to spray cleaning liquid against both major surfaces of a strip advancing along the path in a given direction, cleaning liquid pump means to supply the cleaning liquid at a pressure of at least substantially 60 bar to said pair of spray devices of the cleaning liquid spray unit, cleaning liquid removal means arranged downstream of the cleaning liquid spray unit to remove at least part of residual sprayed cleaning liquid from the strip major surfaces, a rinsing liquid spray unit which comprises a pair of rinsing liquid spray devices arranged downstream of the cleaning liquid removal means to spray rinsing liquid against the strip major surfaces, rinsing liquid pump means to supply the rinsing liquid at a pressure of at least substantially 5 bar to said pair of spray devices of the rinsing liquid spray unit, and further liquid removal means arranged downstream of the rinsing liquid spry unit to remove residual sprayed liquid from the strip major surfaces.

Preferably, spray beams are provided at both sides of the strip path, extend over its width and are fed through high pressure pumps effecting at least 60 bar from a reservoir of cleaned emulsion, wherein a squeezing roller pair is provided in strip running direction behind the spray beams and is followed by at least one further spray beam pair which is fed through a pump effecting at least 5 bar from a reservoir of clean water, at least one further squeezing roller pair and/or a compressed air stripper being arranged downstream of the last-mentioned spray beam pair.

It is advantageous to so arrange the spray beam pairs that nozzles thereof are directed against the strip and spray in a direction having a component counter to the strip running direction, and also to arrange a respective further spray beam pair, having nozzles arranged to spray in a direction having a component in strip running direction, upstream of each of the spray beam pairs. In this case, the spray beams arranged in front of the high pressure spray beams are operable at 4 to 25% of the pressure of the latter. The certainty with which complete cleaning can be achieved can be increased if more than one high pressure spray beam unit is provided and respective squeezing rollers are arranged behind the spray beam units.In order in this case to carry out the downstream cleaning with largely cleaned emulsion, each spray beam group is preferably arranged above a respective reservoir from which the pumps supplying the spray beams of that group are fed, the reservoir associated with the last spray beam group being fed with fresh water and/ or fresh emulsion. The reservoirs are connected by overflows in sequence directed opposite to the strip runing direction; the reservoir following the reservoir supplied with fresh water and/or fresh emulsion is, in this case, supplied with an emulsion which is withdrawn from the last reservoir through a pump and conducted through a cleaning filter.

The performance and effective width of the spray beams can be adapted to different strip widths by division of the spray beams into spray elements which can be fed selectively. It is expedient to equip at least the reservoir which is supplied with fresh water and/or fresh emulsion, with a heating device.

An example of the method and an embodiment of the apparatus of the present inventhion will now be more particularly described with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional elevation of cleaning apparatus embodying the invention, in which a method exemplifying the invention can be carried out; Figure 2 is a schematic cross-section of part of the apparatus of Fig. 1, showing spray beams arranged at both sides of a rolled strip and supplied through pumps; Figure 3 is a schematic cross-section of the apparatus, showing a squeezing roller pair thereof and strip entraining means; and Figure 4 is a schematic sectional view, to an enlarged size, of the entraining means shown in Fig. 3.

Referring now to the drawings, there is shown in Fig. 1 cleaning apparatus in which a rolled strip 1 to be cleaned is advanced in the direction of arrow 39 over s support roller 2 and through a subdivided container 3. Arranged in the lower part of the container 3 are two intermediate walls 4 and 5, which are effective as overflows and partly divide the container up into compartments 6, 7 and 8.

Arranged above each of the intermediate walls 4 and 5 are respective recesses 9 and 10, which include outlets directed into the compartments 6 and 7 and in which squeezing roller pairs 10 and 11 are arranged. Arranged downstream of the container 3 are two further squeezing roller pairs 1 3 and 14 positioned above a metal guide plate opening into the compartment 8.

Spray beam pairs 1 5 to 20 with six slot nozzles are so mounted in the upper part of the container 3 that two pairs are disposed above a respective one of the compartments and one of the spray beams of each pair sprays the lower surface and the other the upper surface of the strip. Moreover, the slot nozzles are so directed that the spray jets, indicated in Fig. 1, of adjacent spray beams converge in direction towards the associated strip surface.

The compartment 8 is continuously supplied with fresh water through a valve 21 and pipe ducts. Excess fresh water flows over the wall 5 into the compartment 7, into which a metered quantity of an emulsion concentrate is transferred so that an emulsion results in the compartment 7, the concentration of the emulsion preferably being matched to that of the emulsion employed during rolling. A pump 22 withdraws liquid from the compartment 8 serving as a reservoir for fresh water or fresh emulsion and sprays this in a quantity of, for example, 30 cubic metres per hour at a pressure of 6 bar by means of the spray beam pairs 1 9 and 20 against the strip surfaces.

The sprayed water flows away laterally or is held back by the squeezing roller pairs 1 3 and 1 4 and conducted back into the compartment 8. The spray beam pair 1 8 is fed at high pressure from the compartment 7 by means of a high pressure pump set 23, whilst the spraying beam pair 1 7 in the illustrated embodiment is fed at a rate of about 1 5 cubic metres per hour and a pressure of 1 2 bar by means of a pump 24. The spray beam pairs 1 5 and 1 6 are supplied from the reservoir 6 with emulsion at corresponding pressures and feed rates by means of a high pressure pump set 25 and a pump 26.Emulsion for cleaning is withdrawn from the compartment 6 by means of a pump 27 and conducted through a cleaning filter 28 and a pump 31 to the compartment 7 as cleaned emulsion. To supplement the returned emulsion quantity, a filter 29 and a reservoir 30 of the emulsion plant are arranged downstream of the pump 27, expediently by way of controlling valves, so that cleaned emulsion is withdrawable by the pump 31 also from this source. However, it has proved that the emulsion provided as cleaning liquid, with appropriate dimensioning of the filters, is withdrawn in better conditions from the filter 28.

In operation, the strip 1 to be cleaned is conducted in the direction of the arrow 39 into the cleaning apparatus. The strip runs over the support roller 2 and between the spray beams of the spray beam pairs 1 5 to 20, during which it is largely cleaned of adhering liquid by the squeezing roller pairs 11,12, 13 and 14. The spray beam pairs 16 and 18 spray emulsion at a high pressure and between 60 and 140 bar, wherein the spray jets do not impinge perpendicularly against the strip, but have a component directed against the strip running direction. An enhanced cleaning effect is thereby achieved in conjunction with the high pressure. Foreign bodies are detached from the strip surfaces and rinsed away with the emulsion.A counteracting barrier with an oppositely directed component is provided by the spray beam pairs 1 5 and 1 7 operated at a substantially lower pressure, so that the running of the liquid against the strip running direction is limited and liquid surges are kept away from the recesses 9 and 10 and the squeezing roller pairs. Foreign bodies which have been detached but not yet floated away, are washed off together with emulsion residue by the clean water rinsing, which is also performed at lower pressure and in place of which, however, a further rinsing by emulsion of diluted emulsion can take place.Following this rinsing by means of the spray beam pairs 1 9 and 20 is a further freeing of the strip surfaces from water by the two squeezing roller pairs 1 3 and 14, which are arranged one after the other and which can be replaced entirely or in part by one or more air blowing devices. Heating of the emulsion, expediently to the temperature of the emulsion employed for rolling, can be carried out by electrical or tubular heaters. The rinsing liquid used in the compartment 8, however, is expediently heated through heating pipes 32 to a temperature higher by at least 10 to 20 .

Although an adaptation to the width of the rolled strip can be undertaken with the spray beam pairs 15, 17, 1 9 and 20 operated at relatively low pressure, this adaptation is not absolutely necessary in view of the lower power requirement. If is, however, recommended for the spray beam pairs fed at high pressure.

In Fig. 2, the spray beam pair 18, consisting of the spray beams 18 and 1 8a, is illustrated schematically along with the strip 1. The spray beams are divided by partitions into individual chambers, for example a middle chamber 33, adjoining side chambers 34 and 35, and outer chambers 36 and 37. In the case of strip widths up to 1050 millimetres, only high pressure pumps 41 and 42 of the pump set 23 are operated so that only the middle chambers 33 of the spray beams 1 8 and 1 8a are supplied, in accordance with the schematic illustration of the jets, with 200 litres per minute at 1 20 bar. If a wider strip is processed, a high pressure pump 43 of the set 23 is operated and feeds the four chambers 34 and 35 at the same rate for each chamber.If the width of the strip extends up to 2050 millimetres, then a supply of the outside chambers 36 and 37 is also effected through a high pressure pump 44 of the set 23, whereby the spray beams 18 and 1 8a will be effective over their entire width. The illustration of the spray jets is only schematic; instead of individual nozzles, slot nozzles may be arranged to extend over the respective chamber.

In order to simplidy Figs. 1 and 2, the arrangements necessary for the introduction of the leading end of the strip 1 are not shown, the relevant components instead being shown separately in Figs. 3 and 4.

In Fig. 3 there is shown, in front of the squeezing roller pair 11, chain wheels 45, which are arranged in front of and behind, or in the inlet and behind, the outlet of the container 3 and between which endless chains 46 and 47 so extend that either they are guided externally past the bearings of the squeezing roller pairs or, as illustrated in Fig.

3, they engage around the shaft spigots of the roller pairs. In order to avoid sagging to the chains, further chain wheels, supporting at least the upper run, can be arranged between the outer chain wheels 45. The chain wheels of both sides can be driven in common and/ or synchronously through a drive device.

Extending between the chains 46 and 47 is an entraining beam 48, which is connected at both ends with the chains and equipped with a number of connecting devices, one of which is shown in section in Fig. 4. The connecting devices are mounted at regular spacings on the upwardly directed face of the beam 48 and each comprise a fork 49, the two fork ends of which are connected by a bolt 50 on which a clamping dog 51 is pivotably retained. The fork limbs are connected with both the ends of a bridge 52, which has respective spigot centring a spring 53. The spring bears against a tensioning arm 54 of the dog 51, which has a bore receiving the free end of the spigot. The dog 51 is so constructed that its lower shell surface has a radial spacing from the axis of the bolt 50 which increases from the front to the rear.

Upwardly, a control arm 55 is formed, which after execution of the working stroke, i.e. after introduction of a strip leading end 59 and the transport thereof through the container 3, bears against a control rail 56, which is arranged behind the container and pivots the control arm 55 of the dog back and thereby opens the dog. This control rail is illustrated only in chain-dotted lines in Fig. 4, since the same Figure shows guiding and centring elements 57 and 58, which facilitates the introduction of the initial end 59 of the rolled strip 1.

For the introduction of a new rolled strip 1, this is led through the guiding and centring elements 57 and 58, which can be arranged in a fixed position in front of or directly behind the support roller 2. Alternatively, for the purpose of centring they can be pushed forward into the illustrated position only on the advance of a strip leading end 59. The leading end 59 is thereby fed towards the clamping gap, which narrows in wedge shape and is formed between the lower web of the beam 48 and the lower surface of the dog 51, and enters this gap under pivotation of the dog 51 in clockwise sense against the force of the spring 53.

When the strip leading end 59 has been pushed into the illustrated position, the chain guide is driven and the entraining beam 48 is moved to the left in the sense of the strip advance. If in this case it moves more rapidly than the strip leading end 59, then this turns the dog 51, through friction at the shell surface thereof, in the lefthand sense so that the end 59 is now retained not solely through the spring 53, but also by the blocking effected through the friction.

The beam 48 with the strip leading end now traverses the entire container 3, while the squeezing roller pairs are driven apart sufficiently for the entraining beam to be able to be advanced free of contact. It is possible to move the squeezing rollers of each pair by equal amounts or by different amounts. Similarly, it is possible to remove only one of the rollers from the strip running plane, so that a simpler starting mechanism results.

After completion of the working stroke of the entraining beam, i.e. after drawing in of the strip leading end, the control arms 55 of the dogs 51 abut, in the course of the further movement, against a control rail 56, which is locally fixed or else brought into the desired setting only for the purpose of the introduction of the strip, so that the dog rotates slightly in the righthand sense against the force of the spring 53 and frees the leading end 59. Through an increasing vertical component of the guidance, for example that of the chains at the last chain wheels, the entraining beam can be guided out of the movement path of the strip.

For greater spacings of strips to be processed, the beam can be returned to its initial position. It is, however, possible to conduct the beam back through more complicated chain guides above or below the container 3 or to detach the beam from the chain, guide it back on a special path and recouple it to the guide at the inlet.

The illustrated embodiment of the apparatus is to be provided behind a roll stand or in front of a coiling drum or between both. The apparatus has a relatively simple construction and the cleaning and rinsing liquids are easily produced without the need to discharge used liquids or to prepare used liquids for drainage into a sewage system. Within the three compartments corresponding to the three spray beam groups in the illustrated embodiment, the first is charged with clean water or a preferably weak emulsion which then overflows into the following compartment, from which flow to the third compartment also takes place through overflow. Expediently, an emulsion, which corresponds to that employed in the rolling mill, is utilised in the upstream compartment. However, it is also possible to use weaker emulsions when supplementing through the emulsion system is dispersed with.

The liquids are so conducted in circuit within the containers and the assiciated spray beams that only relatively small transfer currents are-required for topping-up and cleaning. The emulsion itself is prepared through filtering and conducted to the compartment 7.

The inflow of fresh water is expediently so dimensioned that it balances the emulsion losses in the rolling mill so that the emulsion delivered by the cleaning process requires no particular cleaning or preparation. For this reason, a somewhat larger current is withdrawn from the compartment 6 through the pump 27 than is conducted back through the pump 31. The liquid withdrawn by the pump 27 is regenerated substantially through the cleaning filter 28 and conducted to the compartment 7 and only the quantity coresponding to the flow out of the compartment 8 is added through the filter 29 to the emulsion system.

Claims

1. A method of cleaning a strip of metallic material, comprising the steps of advancing the strip in a given direction, spraying a cleaning liquid against the major surfaces of the strip at a pressure of at least substantially 60 bar and in a direction having a component counter to the direction of advance of the strip, removing at least part of residual sprayed cleaning liquid from the strip major surfaces, spraying rinsing liquid against the cleaned major surfaces of the strip at a pressure of at least substantially 5 bar, the temperature of the rinsing liquid being higher than that of the cleaning liquid, and removing residual sprayed liquid from the strip major surfaces.

2. A method as claimed in claim 1, wherein the cleaning liquid is a regenerated cleaning emulsion and the rinsing liquid is one of fresh water and fresh cleaning emulsion.

3. A method as claimed in either claim 1 or claim 2, wherein at least one of the steps of removing comprises squeezing the strip between squeezing devices.

4. A method as claimed in any one of the preceding claims, wherein the final step of removing residual sprayed liquid comprises blowing air against the strip major surface.

5. A method as claimed in any one of the preceding claims, comprising at least one further such step of spraying cleaning liquid and subsequent step of removing residual sprayed cleaning liquid, said further steps being carried out prior to the step of spraying rinsing liquid.

6. A method as claimed in any one of the preceding claims, comprising the step of collecting the sprayed rinsing liquid and transferring at least a part of the collected liquid to a reservoir for the cleaning liquid.

7. A method as claimed in any one of the preceding claims, wherein the step of spraying rinsing liquid comprises spraying in a direction having a component counter to the direction of advance of the strip.

8. A method as claimed in any one of the preceding claims, wherein each of the steps of spraying comprises spraying with upstream jets having a component in the direction of advance of the strip and with downstream jets having a component counter to the direction of advance.

9. A method as claimed in claim 8, wherein the upstream jets have a lower pressure than the downstream jets.

10. A method substantially as hereinbefore described with reference to the accompanying drawings.

11. Cleaning apparatus for cleaning a strip of metallic material, comprising means for advancing the strip in a given direction along a cleaning path, a cleaning liquid spray unit which comprises a pair of cleaning liquid spray devices arranged to spray cleaning liquid against both major surfaces of a strip advancing along the path in a given direction.

cleaning liquid pump means to supply the cleaning liquid at a pressure of at least substantially 60 bar to said pair of spray devices of the cleaning liquid spray unit, cleaning liquid removal means arranged downstream of the cleaning liquid spray unit to remove at least part of residual sprayed cleaning liquid from the strip major surfaces, a rinsing liquid spray unit which comprises a pair of rinsing liquid spray devices arranged downstream of the cleaning liquid removal means to spray rinsing liquid against the strip major surfaces, rinsing liquid pump means to supply the rinsing liquid at a pressure of at least substantially 5 bar to said pair of spray devices of the rinsing liquid spray unit, and further liquid removal means arranged downstream of the rinsing liquid spray unit to remove sprayed liquid from the strip major surfaces.

1 2. Apparatus as claimed in claim 11, each of the removal means comprising a pair of squeezing rollers for squeezing of the strip therebetween.

1 3. Apparatus as claimed in either claim 11 or claim 12, and further liquid removal means comprising a device for blowing compressed air against the strip major surfaces.

14. Apparatus as claimed in any one of claims 11 to 13, wherein the cleaning liquid spray unit comprises a further pair of such cleaning liquid spray devices immediately upstream of the first-mentioned pair of spray devices of that unit and wherein the rinsing liquid spray unit comprises a further pair of such rinsing liquid spray devices immediately upstream of the first-mentioned pair of spray devices of that unit, each of the spray devices of the further pairs being arranged to spray in a direction having a component in the strip advance direction and each of the spray devices of the first-mentioned pairs to spray in a direction having a component counter to the strip advance direction.

1 5. Apparatus as claimed in claim 14, comprising further cleaning liquid pump means to supply cleaning liquid to the further pair of cleaning spray devices at a pressure of substantially 4 to 25 percent that of the cleaning liquid supplied to the first-mentioned pair of cleaning liquid spray devices.

16. Apparatus as claimed in any one of claims 11 to 15, comprising at least one further cleaning spray unit arranged downstream of the cleaning liquid removal means and upstream of the rinsing liquid spray unit, and respective further cleaning liquid removal means arranged downstream of the or each further cleaning liquid spray unit to remove from the strip major surfaces at least part of residual cleaning liquid sprayed by the devices or that unit.

17: Apparatus as claimed in any one of claims 11 to 16, comprising a plurality of reservoirs which are each arranged under a respective one of the spray units and which are interconnected by overflow means in a flow direction opposite to the strip advance direction, each pump means being arranged to supply liquid or rinsing liquid, as the case may be, to the associated spray devices of each unit from the reservoir associated with that unit, and means being provided to supply at least one of fresh rinsing liquid and fresh cleaning liquid to the downstream end one of the reservoirs, to withdraw and to filter cleaning liquid from the upstream end one of the reservoirs, and to supply the filtered cleaning liquid to the reservoir adjoining said downstream end reservoir.

1 8. Apparatus as claimed in claim 17, comprising heating means arranged in said downstream end one of the reservoirs.

1 9. Apparatus as claimed in any one of claims 11 to 18, wherein at least one of the spray devices is divided transversely of the path into a plurality of spray elements, the pump means for supplying cleaning liquid or rinsing liquid, as the case may be, to the or each divided spray device being operable to supply the spray elements of that device selectively.

20. Apparatus as claimed in any one of claims 11 to 19, comprising guide means extending alongside the path, an entraining device guided by the guide means and operable to releasably entrain a leading end portion of a strip, and drive means to drive the entraining device along the guide means, the guide means being arranged to guide the entraining means away from the path after release of the strip.

21. Apparatus as claimed in claim 20, the guide means comprising a chain guide.

22. Apparatus as claimed in either claim 20 or claim 21, the entraining means comprising a cross-bar provided with connecting means.

23. Apparatus as claimed in claim 22, the connecting means comprising a resiliently biassed pivotable clamping element displaceable into a release position by displacing means at the end of the path.

24. Apparatus as claimed in claim 23, wherein the clamping element has a curved clamping surface radially spaced from an axis or pivotation of the element by an amount which progressively increases generally in the downstream direction of the path, the clamping element being pivotable about said axis for clamping between the clamping surface and a surface portion of the cross-bar of a strip of a thickness within a predetermined range of thicknesses.

25. Apparatus as claimed in any one of claims 20 to 24, comprising strip centring and guide means to guide the upstream end portion of the strip to the entraining means in an entraining position thereof.

26. Cleaning apparatus substantially as hereinbefore described with reference to the accompanying drawings.