US2395397A - Apparatus for cleaning strip metal - Google Patents

Description

Feb. 26, 1946. G. M. cRoFT Y APPARATUS FOR CLEANING STRIP METAL Filed March 20, 1940V 3 Sheets-Sheet l Feb. 26, 19416. G, M CRQFT 2,395,397

. APPARATUS FOR CLEANING STRIP METAL FiledvMarch 20, 1940 5 sheets-sheet 2 i fl Fig 2 M WMW.

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APPARATUS FORCLEANING STRIP METAL Filed March 20, .w40 5 sheets-sheet 3 Patented Feb. 26, 1946 UNITED] STATES PATENT OFFICE APPARATUS FOR CLEANING STRIP METAL George M. Croft,

Pittsburgh, Pa., assgnor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application March 20, 1940, Serial No. 325,081

2 Claims.

This invention relates to the surface treating of strip metal, and is for an apparatus for effectively cleaning the surface of a continuously moving strip by a `succession of alternate scrubbing and liquid spraying operations with rinsing and drying of the strip at certain stages in the treatment.

In treating moving metal strip particularly y where the strip is to be moved at a high rate of speed such as 1500 to 3000 feet per minute, it is apparent that even a few thousandths of an inch thickness of liquid lm on the surface of the strip will amount to a large quantity of liquid carryover within a short period of time, thus emphasizing the need for a practical method of, in effect,

restricting each liquid treating step and preventparatus for cleaning metal strip in which both mechanical scrubbing and chemical cleaning and final washing and drying are economically and effectively accomplished, and with practically no carry-over of chemical solutions used in one stage to another, and without the carry-over of appreciable amounts of solids on the surface of the metal resulting from the evaporation of alm `of such liquid. According to this invention, suction devices are used at certain stages of the treatment in order to remove any adhering film of liquid on the sheet, thereby avoiding the carryover of the liquid lm from one stage of the treatment to another, and also avoiding the deposit which the evaporation of such a film, if not removed, would leave.

In the drawings: y

Figure 1 is a vertical view in elevation and in partial section of a complete layout somewhat diagrammatically illustrated for treating continuous strip in accordance with the principles` of the present invention;

Figure 2 is an enlarged front end view in sectional elevation of a detail of the apparatus arrangement of Figure 1;

Figure 2a is a reduced view constituting a con# tinuation of Figure 2 and showing an apparatus arrangement for producing suction;

Figures 3-6, inclusive are `somewhat diagrammatic side views in elevation showing details of liquid removing apparatus.

As shown, for example, in Figure l, I may employ a coil or reel 5 of strip metal 6. The strip is subjected to a series of cleaning operations or treatments in compartments Ato E, inclusive,

and is pulled through such compartments or treatment stations at a suitable tension ty a pair of motor driven pinch rolls l. .After treatment, the strip may be recoiled or subjected to other treatments as desired. The operation of the present apparatus is not limited to interrupted lengths of strip, b-ut maybe and is preferably employed to treat continuous lengths or coiled lengths that are welded together to form a continuous length.'

The pinch rolls 'I pull the strip past treatment stations at a desired speed, provide a tension `suitable to overcome frictional and other losses, and maintain the strip` in a substantially` horizontal plane during its movement and thus during its treatment.

In compartment A, the strip is wet-'brushed or scrubbed on both of its sides by roll and brush pairs I0, I2. Previously-used hot washing solution or water is applied in any suitable manner-as by jets I3. Thence, clean wash water is applied to both sides of the strip, preferably under a relatively higher pressure, by such means asrjets I4 to remove the dirt and grit and the previouslyused washing solution. Finally, the thin film of liquid remaining on the surface portions is removed by a suction or vacuum cleaningapparatus 30. j b Y 'I'he strip enters compartment `B dry and as clean as hot water scrubbing can make it and is then subjected to a series of concentrated 40 chemical cleaning solution sprays I8. Additional sprays 23 apply the chemical solution in compartment C while the strip is being brushed and scrubbed by roll-brush pairs 20, 22. Finally, the strip is again washed with a clean washing iluld at Ila and the liquid film removed at 30a. If` desired, the step of washing at Illa may be omitted, and the chemical solution instead of Wash water removed at 30a, suitable changes in the piping system being made to return the chemical solution for re-circulation.

In compartment D, the chemically cleaned strip is subjected to a series of suitable applications of clean heated wash or rinsing water by sprays or jets 24. In compartment E, the strip is initially subjected to` a cleaning jet or spray to the chemical solution settling tank 5I.

e application at I4b that is preferably of a high i shown somewhat diagrammatically in Figure 1,

is primarily chosen for the purpose of illustrating the principles of the present invention, and it will be apparent that other suitable arrangements may be employed. The compartment A, the compartments B-and C, the compartment D, and the compartment E, have,- as shown, collecting -tanks for the solutionsv or fluids employed in treating the strip therein. I have also provided a water settling tank 50 and a chemical solution settling tank 5I that may be employed in a conventional manner to remove sediment and prepare the liquids for reuse. Although I have shown representative pumps, heat exchangers, valves, etc., it will be apparent that they may be rearranged and others may be added in accord- -ance with the requirements of a given installation. The iloat valves have been given a common designation a; the `heat exchangers have been given the common designation H followed by a suffix; the` pumps have been designated PV iollowed by a suffix; and the battling within the tanks 60 and 6I for separating the space into compartments has been indicated `as j and g, respectively. f r

- Fresh or clean water is supplied through a main 5II and is pumped by pump P4 through heat exchanger H4, line 5I, and heat exchanger H5, line `52,'to the cleanwater sprays or Jets 24. Conden- 'sate from the heat'exchanger H5 ilows by gravity through line 53 to heat exchanger HI that is employed to heat previously-used wash water which is taken oi! from the wash water settling tank $0 through piping 55 and forced by pump PI through line 55 and sprays I3. The condensate line 53 also has a branch lineA 54 that is providedv with inlets or oric'es b `for supplying the settling tank il! with warm condensate as needed. v

Wash water or dilute solution used in compartmentA drains o il by gravity through lines 51 and 58 toreturn to the settling tank 50 for reuse. Likewise, liquid taken oil by the vacuum suction apparatus flows through lineI 31 'past suction unit I5 through line 45 to the settling tank return line 53.

I'he chemical solution sprays IIIy and 23 of compartments B and C are supplied with chemical cleaning solution by a takeoi 65 from their common collecting tank. The pump P2 moves'the takeoff liquid through heat exchanger H2 and into the spray supply line 65. The levelof the chemical ysolution in the collecting tank of compartments B and C is maintained by a float valve a and a solution supply line 58. Pump'P3 delivers solution from the chemical solution settling tank 5I through the line 68 as required.

It will be noted that vacuum cleaning devices 30h of compartment E are connected through branch line 31h, vacuum unit I5, line 45h, line 1I, and liquid return line 58, to the water'settling tank 50, while the cleaning device 30a is connected through line 31a, -vacuum unit I5, line 45a, A branch line 12 from the collecting tank of compartment D is connected to the washing fluid return line 45h, 1I to supply settling tank 6I with water as needed to compensate for evaporation losses and as controlled by a float valve a.

The water supply line 50 is provided with a branch line 13 that introduces clean wash water into the tanks 60 and 5I through upper inlet openings or nozzles d and lower inlet openings or nozzles c.

In Figures 2 and 2A, I have shown a cleaning unit` that may be termed a suction or vacuum unit. An upper suctionv hood 3l is preferably positioned to extend for substantially the full width of the strip being moved and may be provided with a lower cooperating hood 30'. Both hoods are connectedby flexible conduits 36 to a vacuum line 31 oi vacuum tank 38. This tank serves to separate air and vapor from the liquid. The gases (air and vapor) are drawn out near the top of tank 38 through pipe 35 by a motordriven `wet-vacuum pump unit 4l, while the liquid is constantly removed from the bottom of the tank through pipe 43 by a motor-driven centri!- ugal pump unit 44. Water for sealing the Wet-l vacuum pump is supplied by pipe 42, and the air and vapor are discharged to the atmosphere through pipe 4 I Pump 44 serves to prevent tank 33 from filling with accumulated liquid and to deliver the liquid to the sewer or to return liquid through lines 45, 45a, or 45h to the settling tanks and 6I.

Other apparatus, such as more elaborate means for separating the liquid from the gases combined with a dry vacuum pump, or a. Vfurther liquid and gas separating stage treating the ,exhaust from wet-vacuum pump unit 45, may be employed if desired, such substitutions or further refinements being within the scope of the claims;

' ,It will be noted that on Figure 1, I show heated liquid applied tothe strip for washing and treating steps, butthat cold or unheated liquid is applied at sprays I4, I4a, and |417, prior to the vacuum removal of liquid by umts 3l, 3la,.and 30h, respectively. These `cold sprays are `not necessary except where hot treating liquids are employed which would iiash into vapor when subiected to a vacuum. Removal of the liquid by evaporation, ashas lbeen pointed out previously, is particularly objectionable where'th'e solutions contain dissolved solid constituents such as salts which then remain on the surface of the strip. If the liquid which is in aqueous solution-is too hot, its vapor pressure is relatively high and the applicationof suction for theshort period during which the strip is passing the nozzle results in evaporationof the solution such as water place, withoutappreciably cooling the strip itself,

which remains at substantially the same temperature after passing between the suction heads. However, under some conditions, particularly after a iinal washing with pure water, evaporation may be desired, in which case the cold liquid sprays may be eliminated, or where a cool solution is used, heat may be applied thereto by suitable heating elements in the region occupied by the cold sprays shown on Figure l.

As shown in Figure 2, the hood portions 30 or 30 are provided with ltransversely-extending brackets 3l that are mounted upon a suitable support frame 34 by adjustable'bolt means 32. Springs 33 are held in compression between the frame 311 and the brackets 3| to flexibly mount and support the suction hood portions 30 and30'. The bolt means 32 is tightened to compress the spring 33 when the hood is to be moved away from the strip and is loosened to move the hood towards the surface of the strip.l

Although in a preferred arrangement, I employ a pair of upper and lower suction hood portions 30 and 3U', it will be apparent, as shown in Figure 5, for example, that single hood portions may be employed and may be staggered in such a manner as to aid pinch rolls such as 'la in supporting or holding the strip 6 in a substantially horizontal plane during its movement.

In the arrangement of Figure 3, I h'ave shown high pressure clean water jets I4 for washing away the previously used solutions and leaving a relatively thin film of clean solution. This, of course, will lessen the burden of the suction apparatus 3B. In the arrangement of Figure 4, a forward pair of pinch rolls 1b is employed in oooperation with pinch' rolls 1a to hold the strip tightly in position during the suction operation. 'I'his arrangement is particularly advantageous to avoid deection of the strip when an extremely high suction pressure or force is employed. The rolls 'lb are preferably drawn closely enough to deflect surplus liquid edgewise to either side of the strip, to thereby leave only a very thin film to be removed by the suction unit 30.'

I have found that the speed of the strip should also be considered with reference to the eiectiveness of the lm removal. If under high speed conditions th'e amount of liquid to be removed cannot be taken care of by one set of suction nozzles, any suitable number of successive nozzles or suction d evices in sequence may be provided as needed.

In Figure 2 I have shown a representative type of suction nozzle arrangement and it will be apparent that other suitable arrangements may be employed depending upon particular requirements and the size and type of impervious material `being cleaned. For example, in Figure 6 I have shown an anti-friction non-scratching type of shoe 'l0 attached to bottom edge portions of the suction nozzles 30 and 30' of Figure 2 by suitable brackets 'H and bolts 12. This ligure also illustrates th'e nature of the suction action upon the uid film 8. The movement of liquid isolate each cleaning operation to conserve the cleaning fluids and to prevent dilution. The ar-` rangement is such that the liquid illm will be removed regardless of the speed of the operation and can Ibe accomplished without the necessity of intermittent pauses. It will be apparent that the strip enters a successive treating station with its surfaces practically free from liquid film, such that the succeeding operation can be more effectively accomplished. It will also be apparent that in such an arrangement where there is no carryover of liquid nlm, the need for additional successive washing applications has been eliminated as well as the need for additional collecting tanks to provide a re-use of the material washed of! 'by such successive applications. In view of the above considerations, I have been able to eilect a high speed treatment of strip whereby it is cleaned at maximum effectiveness and at a minimum expense. It will b'e also apparent lthat my invention is not limited to speciilc apparatus or apparatus arrangements shown, and that various modications, substitutions, and rearrangements may be made without departing from the spirit and scope of the invention as indicated by the appended claims.

I claim:

l. Apparatusl for cleaning continuously mov-` liquid to the metal. and vacuum instrumentalitiesv for removing substantially completely from the metal all adhering liquid without substantial evaporation thereof from the metal, the said carried by the strip is partially arrested upon encountering the shoe 'l0 and the liquid tends to accumulate in such a manner as to prevent contact of the strip with the shoe. YAir enters chiefly from th'e opposite end of the shoe between the shoe and the strip and has a high velocity. This results in the liquid being arrested at the suction nozzle and removed from the strip at the nozzle orifice, as somewhat diagrammatically illustrated in Figure 6. For this reason, I preferably provide the entry portion of the shoe 10 or the suction nozzle with a greater clearance on its incoming side than on its outgoing side. This provides the outgoing side with a narrow orifice to increase the effectiveness of the removing action. The larger size orifice at the incoming side permits a quick removal of the liquid film such that the greater portion of it is removed before the strip has moved past a substantially central point of unit 30.

'I'he hood portions of the suction device 30 are preferably resiliently or flexibly mounted for independent adjustment and also to prevent damage when any solid material, obstruction, or uneven portion of the strip moves therepast.

Itv will be apparent from the above description that suction or liquid removing vacuum units can be employed along the cleaning line to, in effect,

metal thereby passing into a second treating compartment as clean as the mechanical scrubbing can make it. and dry. instrumentalities inthe second compartment for applying a concentrated-` cleaning solution to the metal as it moves through the second compartment into a third compartment. mechanism in the third compartment for mechanically scrubbing the thus-treated metal as it moves therethrough, means intermediate the said mechanicallv scrubbing mechanism in the third compartment for applying liquid to the metal as the metal is scrubbed, meansin the said third compartment following `the liquidapplying means and the mechanically scrubbing mechanism for applying clean wash liquid to the metal. vacuum-drying means in the third com partment for removing substantially completely all liquid lm from the metal, the said metal passing into a fourth compartment dry and as mechanically clean as the scrubbing can make it. means in the fourth compartment for applying clean wash liquid to the metal, the metal being passed into a iifth. or outlet. compartment. means in the said fifth compartment for applying clean wash liquid to the metal under high pressure, and vacuum-drying instrumentalities operating on the resulting washed metal to remove all liquid adhering thereto. the metal pass"- ing from the said compartment dry and in chemically clean condition.

2. Apparatus for cleaning continuously moving indeterminate lengths of metal strip from'a coil thereof, which comprises, in combination, a. series of successive treating compartments for the strip, extending from an intake compartment for the strip to an outlet compartment therefor, means for continuously moving the strip through the said compartments, means in the intake compartment for alternately mechanically scrubbing the moving strip and for applying hot cleaning l0 liquid theretofmeans for heating the cleaning liquid, means for recirculating the cleaning liquid from the said intake compartment through the heating means, mechanism for. iinally applying clean cold wash liquid to the strip in the intake 15 compartment, vacuum-drying means for the intake compartment for closely applying suction to the strip for removing therefrom substantially all adhering liquid without appreciable evaporation of the `liquid from the strip, the said strip 20 cal scrubbing mechanism for applyinghotconcem' tratedcleaning solution to the strip as the strip is scrubbed, mechanism for continuously recirculating the concentrated cleaning solution through the second and third compartments, means in the third compartment for rinsing the cleaned and mechanically scrubbed strip with clean, cold wash liquid, vacuum-drying means inthe third compartment for removing by suction at `least substantially all liquid adhering to the strip without any appreciableevaporation of the liquid, the strip thereby passing dry `and mechanically clean into a fourth compartment, means for washing the strip in the. fourth compartment with clean hot wash liquid, the resulting cleaned strip passing from the fourth compartment into aIfth' compartment, means in the lifth compartment for spraying the strip with hi'ghl pressure sprays of cold wash liquid, and final vacuum-drying.

means in the fifth compartment for removin all adhering liquid from the strip. q y

GEORGE Ml; caor'r.

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