US2676599A

US2676599A - System for pickling

Info

Publication number: US2676599A
Application number: US268442A
Authority: US
Inventors: Ernest C Mchenry
Original assignee: Allegheny Ludlum Steel Corp
Current assignee: Allegheny Ludlum Steel Corp
Priority date: 1952-01-26
Filing date: 1952-01-26
Publication date: 1954-04-27
Anticipated expiration: 1971-04-27

Description

April 27, 1954 E. c. Mol-IENRY SYSTEM FOR PICKLING Filed Jan. 26, 1952 Patented Apr. 27, 1954 UNITED STATES TENT OFFICE SYSTEM FOR PICKLING Application January 26, 1952, Serial No. 268,442

Claims. l

4This invention relates to rolls and in particular to a system utilizing hold-down rolls for use in pickling baths of steel mills.

According to prior steel mill practice, strip material of stainless and other types of steels is passed through a pickling solution to remove scale from the surfaces thereof. In order to maintain the strip immersed in the pickling solution hold-down rolls have been widely used, the hold-down rolls being so mounted with respect to the pick-ling tank that the lower portion of the roll is in the pickling solution and the strip of steel passes beneath but in contact with the roll, the roll thereby maintaining the strip immersed in the picliling solution.

The rolls are usually formed of a metallic housing having a coating of rubber or other elastomer applied thereto in adhering relation to protect the metallic housing from the acid of the pickling solution. However, in practice it is found that the elastomer protective coating is often cut or otherwise pmictured byreason of burs or rough or uneven edges found on the strip material which is being treated.

'Under such circumstances when the protective coating is punctured the acid is admitted into contact with the metallic housing with the result that the metal of the housing is attacked and destroyed without any evidence to the operator of the destruction of the roll until such destruction has advanced to the point that the roll collapsed and it was impossible to repair it. Since the pickling step is usually only one portion of a continuous annealing and pickling operation it is appreciated that the destruction of one of the hold-down rolls effects a complete shutdown of the continuous operation of treating the metal strip until the roll could be replaced with a new roll.

An object of this invention is to provide, in a hold-down roll for a pickling line, for limiting damage to the roll when the protective coating thereof is punctured or otherwise vcut to admit acid to the metallic portions of the roll.

Another object of this invention is to provide for limiting damage to the metallic housing of a hold-down roll when the protective coating thereof is punctured and to simultaneously provide for indicating such limited damage so that the roll can be repaired.

Other objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawing in which:

Fig. 1 is a view in side elevation and partly in (Cl. 13d-122) section of apparatus embodying the teachings of this invention;

Fig. 2 is a view in section, greatly enlarged, of a portion of the apparatus of Fig, 1; and

Fig. 3 is a view in section, greatly enlarged, of

a portion of the roll or Fig. 2 illustrating the limiting of damage to a roll embodying the teachings of this invention.

Referring to Fig. l of the drawing this invention is illustrated by reference to apparatus utilized for pickling the surface of a strip l0 of stainless or other type of steel. The apparatus includes a tank i2 formed of an outer metallic housingl Hi and having a layer I6 of rubber or the like disposed over the inner surface thereof for protecting the metal housing lli of the tank from the action of a pickling solution I8. The pickling solution may be any of the well known piclrlng solutions, such as a 4 to 6% hydlO- iluoric acid solution, or 10 to 14% nitric acid solution, or up to a 20% solution of sulfuric acid, the pickling solution i8 being usually maintained in a heated condition at a temperature of between 1&0 to 200o F. The picklng solution i8 usually lills the tank i2 to a level represented at I9 closely adjacent its upper edges.

Associated with the tank i2 are guide rolls 2E! and 22 at the opposite upper ends thereof over which the strip it passes as it enters and emerges .from the pickling solution i8.

In order to hold the strip it immersed in the piclsling solution it as it passes from the roll 2i) to the roll 22 one or more so-called hold-down rolls 2t and 2t are disposed in mounted relation with the upper edge of the tank l2 so as to be supported thereon, the lower edge of the holddown rolls 24 and 25 being immersed in the pickling solution IS as illustrated in Figs. 1 and 2 and in contact with the strip Iii. While in this embodiment only two hold-down rolls 2i and 26 are illustrated, it will, of course, be appreciated that the number of hold-down rolls will depend upon the length of time it is desired to maintain the strip immersed in the pickling solution i8 as well as the speed with which the strip it is drawn through the pickling solution it and the condition of the surfaces of the strip lil.

Referring to Fig. 2 of the drawing the structure of the roll 2d is illustrated it being understood that the structure of roll 25 and other holddown rolls which are used in conjunction therewith will be the same. As illustrated the holddown roll 2i comprises an inner metallic housing 28 usually formed of common steel of the .10 to .20% carbon grade and is provided with a shaft 3d which, in the embodiment illustrated, extends through the metallic housing and is provided with projecting

ends

32 and 34. The shaft 30 and the metallic housing 28, the latter being of any desirable diameter, are welded into an integral leak-proof structure, such procedure being so Well known that it is unnecessary to illustrate such welding. Since the roll 25 is to operate partially immersed` in the pickling solution I8, the outer surfaces of the metallic housing 24 and at least a portion of the

projecting ends

32 and 34 of the shaft 3E! are provided with a protective layer S6 of rubber, synthetic rubber or other elastomer, the protective layer 36 effectively covering the entire metallic surface of the housing 28 and the welded joints (not shown) between the shaft 3Q and the metallic housing. The elastomers, polychlorobutadiene and polyisobutylene, or the modified isobutylene synthetic rubbers are other examples of elastomers satisfactory for use as lthe protective layer 35; The layer 36 is applied in adhering relation to the housing 28 and the shaft 39 by any of the Well known methods suchmethods being so -well known that they need not be described-herein. As illustrated the extensionof the protective layer 36 outwardly along the outer ends 32 and'34 of the shaft 39 is provided with outwardly extending annular projections 33 and 46, respectively, which projections function to prevent runoff of the pickling solution from the main body of the roll 24 outwardly along'the

projecting ends

32 and 34 of the shaft 3G so as to prevent the solutions coming in contact with -the exposed metallic portions of vthe projecting ends-32 and 34 of the shaft 3e.

In accordance with this invention each of the projecting endsY 32; and 34 of the shaft Sii are so drilled as' to provide passageways i2 and d4, respectively, from a point at the outer end of the projecting ends of the shaft inwardly of the metallic housingt; The purpose of such pas sageways 42and44will be explained more fully hereinafter;

1n order to' mount the pickling roll 2d in operative relationwvith rrespect to the piclrling solution IB, the metallic casing i4 ofthe tank i2 is provided'with outwardly extendingflanged edges 46 andatitsupperv edge thereof for receiving bearing Vhousings 5d and 52, respectively, such housings being provided with bearings d4 and 56'.' respectively, for receivingthe vprojecting ends 32 andLd, respectively, ofthe shaft fill.

In most instances4 the hold-down roll 24 is of the idler-type, thatfis, no powert is applied to the roll' 24'for effecting rotation thereof, the rota- L tion' in the bearings 5d and 56 being effected merely by the frictional contact of the strip l withthe lower lportionof the roll 24. However, in some instances it may be desirable to apply driving power to the roll 2li and for this reason the roll 24 is illustrated'in Fig. 2 as being disposedA for 4having driving power applied thereto. Thus the mounting assembly at the opposite ends of the shaftl are so illustrated that power can be applied to the shaft 3% at the end of the projecting end 32, although it will be understood that if power is not to be applied thereto then the projecting end'32 may be formed and mounted inthe same manner `as the projecting end 34 of the shaft 30;

As illustrated in Fig. 2 in order to supply wa ter or other fluid medium to the hold-down roll 24; the purpose of which will be explained more fully hereinafter, a coupling 5l is provided at theend of projecting end 34 ofthe shaft. Thus sil a terminal plate 53 is disposed to be secured as by means of the hold-down bolts 6G to the bearing housing 52, a suitable gland packing S2 bcng provided and disposed about the end of the projecting end 34 and bearing 5t to prevent leakage thereabout. The terminal plate 58 is provided with a suitable threaded opening $4 disposed in alignment with the passageway 44 in the projecting end 34 of the shaft 39. A suitable conduit 63 is connected in threaded engagement with threaded opening 64 for `connecting such threaded'opening to a source of water or other fluid supply as represented by the pipe line 6B in Fig. l. When so connected water or other fluid is supplied internally of the roll 24, preferably under pressure of ten or more pounds per square inch, the. purpose of which will be more fully explained hereinafter.

Where the other projecting end 32 of the shaft 3G is disposed to have power applied thereto, an opening lf! is drilled through the shaft into registry with the passageway d2, the end of the passageway 42 being plugged as by means of a threaded stopper 12. In such a structure a coupling i3 comprisingia terminal plate ill seated against an annular ring 7S having a threaded passage-'i8 therein, is secured to the bearing housing-5t as by means of the bolts B9. As in the other example, a suitablepacking 82 is provided between the terminal Aplate 14, annular ring l, bearing Stand the projecting end 32 of the shaft 33 for effecting a leak-proof seal therebe ween. Power can be applied by any suitable mechanism (not-shown) to the end of the proiecting end 32 of the shaft 3l) which exten-:is Iloeyond the terminal plate i4. As illustrated a sta-ndpipe 8d is disposed irl-threaded engagement with the threaded opening 'i8 of the annular ring 'i6 to permit escape of the water or other fluid medium from the housing through the passage 42, openings 'ida-nd '.'B` and the standpipe Sii, suitable means suchas a catch basin 86, as illustratedin Fig, l, being provided for receiving and carrying the iiuid away from the standpipe 84 the fluid is discharged therefrom.

If instead'of applyingv power to the projecting end 32 ofthefshaft S theroll 2i is to be operated as an idler roller, then the simpler coupling structureillustrated as applied to the end of the projecting end 34 of the shaft may be utilized instead of the more complicated coupling structure iilustrated'asapplied to the .prof jecting'end 320i the shaft 39, the difference being that thestandpipe B4 would be substituted for the supplypipe 6G.

Where a plurality of the hold-down rollsarc employed, such -fasfrolls 24y and 2B, the couplings 5l thereof are usually connected to a common source of water supply such as the pipe 68 and the standpipes 84 dischargeinto similar catch basins 881 in the manner illustratedin Fig. 1.

With the'structurel formed andassembled. as described hereinbefore the strip Iii of metal is passed over a roll I2li-'and 'beneath .thechold-down roll 2.4i; and other hold-down rolls where such areused; immersed inthe pickling solution I8 and emerges from the pickling solution i8. over the roll.22. Inoperation, water or other fluid medium is supplied under, pressure frointhe source as represented by the conduit or pipe 5S throughthe conduit Gland passagewayl 44 of the projectingendv 3ft-ofthe shaft 3|) internally of the metallic housingfZS of the, roll 24. The standpipe 84 at the other end of the shaft- 30 is of a suiicient'` height tdprevent` escape ofthe water or other fluid from the housing 28 until the housing is completely filled with the fluid medium. n practice the standpipe 84 is usually provided with a height of about seven feet so as to insure that the housing 28 is completely filled with the fluid medium.

As the strip lli passes underneath the roll 24 in contact with the protective layer 36 thereof, if burrs on the edge of the strip or unevenness of an edge of the strip punctures or cuts the layer te of elastomer into the metal surface of the housing 2li, it is found that the acid of the pickling solution i8 will penetrate such puncture or cut in the layer 3d as the roll 2d rotates with an edge thereof in the solution I3. The acid admitted through such a puncture, illustrated in Fig. 3 as being shown at BB, contacts the outer surface of the metallic housing 23 and so attacks such metal as to effect a destruction thereof over an area closely adjacent the puncture 88. rihe area so attacked is illustrated in Fig. 3 as at ed and is shown as being slightly larger at the outer surface of the metallic housing 2s than the area of the puncture 83 and is usually found to decrease in size towards the inner surface of the metallic housing 28 as the acid eats through the metallic housing 28. As soon as the acid of the pickling solution I8 succeeds in penetrating the metallic housing Zit to the extent that an opening is formed therethrough as represented at Sli, the water or other iiuid medium under pressure Within the metallic housing 23 flows through the opening Si? and the puncture 88 thereby eectively so diluting the acid present on the exposed surface of the metallic housing as to prevent further attack thereby on the metallic housing and the pressure of the iiuid medium within the housing 2d eiectively prevents any further admission of the pickling solution through the puncture 3a so as to prevent further attack by the acid of the solution on the metallic housing 28. Simultaneously with the flow of the fluid medium through the zone of the destruction 9b and the perforation 38 it is found that because of the pressure cf the uid medium such iiuid medium actually sprays outwardly through the puncture 88 so that as the roll 2li rotates to expose the puncture above the level of the pickling solution i8, the spray 92, as illustrated in Fig. 2, gives a visible indication of such a puncture and of the start of the destruction of the metallic housing 28 of the roll 24.

When such a signal is given steps should be taken to repair the damaged surface of the protective layer 36 of the housing 24 although since the fiow of the fluid medium outwardly through the opening 96 and puncture 88 prevents further attack by the acid of the metallic housing 23, the line need not be shut down immediately to eiect such a repair. In practice such repairs can often be made by a simple vulcanization of the elastomer layer at the point of puncture and thereafter dressing or smoothing the repaired surface without having to remove the roll 2d from its assembled relation with the pickling tank i2 thus eifecting further economies in the maintenance of the pickling line. It will also be appreciated that the opening 90 can be repaired by a simple weld prior to repairing the puncture in the layer 35.

The invention has effected considerable economies in the operation of continuous annealing and pickling lines for strip material as it prevents complete destruction of the hold-down rolls with the resultant saving in the cost of the roll per se, the visible indication of the start of such a destruction making it possible to correct dainage to the outer protective layer of the roll with out too great an interpretation in the continuous operation of the mill. Maintenance costs of the rolls in one pickling line have been reduced as much as through the installation of the system of this invention.

While reference has been made herein to strip material it is of course to be understood that such term has been employed generically as applying to a continuous strip or to a plurality of sheets suitably tack welded or otherwise secured together.

I claim:

l. In a system for holding metallic strip material in an acid solution as the strip passes therethrough, the combination comprising, a holddown roll having a metallic housing, a shaft having projecting ends for supporting the housing, a layer of elastomer disposed in adhering relation over the metallic housing and covering at least a portion of the projecting ends of the shaft adjacent the housing, the elastomer on the housing being disposed to contact the strip material and being subject to being punctured thereby during use, the shaft having an opening through each end thereof into the housing, a source of water under pressure, one of the openings being connected to the source of water, the other of the openings being disposed to drain the water from the housing, and means connected to said other of the openings to control the level of the Water in the housing to maintain the housing filled with Water under pressure, the Water Within the housing limiting damage to the housing, when the elastomer layer is punctured and admits acid, to the area of the housing closely adjacent to the area of the puncture.

2. n a system for holding metallic strip material in an acid solution as the strip passes therethrough, the combination comprising, a holddown roll having a metallic housing, a shaft having projecting ends for supporting the housing, a layer of rubber disposed in adhering relation over the metallic housing and covering at least a portion of the projecting ends of the shaft adjacent the housing, the rubber on the housing being disposed to contact the strip material and being subject to being punctured thereby during use, the shaft having an opening through each end thereof into the housing under pressure, a source of water, couplings connected to the projecting ends of the shaft in communication With the openings therein, one of the couplings being connected to the source of water for admitting Water through the opening associated therewith to fill the housing, the other of the couplings cooperating with the opening associated there- With to provide a drain for the housing, and a standpipe connected to said other of the couplings, the standpipe having a height sufficient to insure maintaining the housing filled with water under pressure, the water within the housing limiting damage to the housing, when the rubber layer is punctured and admits acid thereto, to the area of the housing closely adjacent to the area of the puncture.

3. In a system for holding metallic strip material in an acid solution as the strip passes therethrough, the combination comprising, a rotatable hold-down roll having a metallic housing, a shaft having projecting ends for supporting the housing, a layer of elastomer disposed in 7 adhering relation over the metallic housing and covering at least a. portion of the projecting ends of the shaft adjacent the housing, the elastomer on the housing being disposed to be immersed in the acid solution as the roll is rotated in vcontact with the strip. material and being subject to being punctured thereby during use, the'shaft having an opening through each end thereof into the housing, a source of Water under pressure of at least ten pounds per square inch, one of the openings being connected to the source of Water, the other of the openings being .disposed to drain the Water from the housing' and means' connected to saidftlier of the openings to control the level of the water in the housing to maintain the housing iilled with water under pressure, the water within the housing limiting damfage to the housing, when the elastomer layer is punctured and admits acid, to the area of the housing closely adjacent to the area of the puncture andproviding a visible indication of said damage as the roll is rotated. 4. In a system for holding metallic strip material in an acid solution as the strip passes therethrough, the ,y combination. comprising, a rotatable hold-dowri-roll having a metallic housing, shaft means. disposed to extend from the opposite ends of the housing for supporting it, a layer of elastomer disposed in adhering relation over the metallic housing and covering at least a portion of the shaft means at the opposite ends of the housing, the roll being disposed to be supported with respect to the acid solution whereby the elastomer on the housing is immersed in the acid solution as the roll is rotated in contact with the strip material, the elastomer being subject to being punctured by the strip material during contact therewith, the shaft means at the opposite ends of the housing having openings therethrough into the housing, a source of Water under pressure, one of the openings being connected to the source of Water to admit Water into the housing, the other of the openings being disposed to drain the Water from the housing, and means connected to said other of the openings to control the level of the Water in the housing to maintain the housing filled with Water under pressure, the water Within the housing limiting damage thereto, When the layer of elastomer is` punotured and admits acid, to the area of, the housing closely adjacent to the area of the puncture and providing a visible indication of said damage as the roll is rotated.

5. In a system for holding metallic strip material in an acid solution as the strip passes therethrough, the combination comprising, a rotatable hold-down roll having a metallic housing, a shaft disposed through the housing with the ends of thel shaft extending outwardly therefrom for supporting the housing, a layer of elastomer disposed in adhering relation over the metallic housing and covering at least a portion of the extending ends of the shaft adjacent the housing, an annular projection of elastomer carried by the elastomer cover of each of the extending ends of fthe-shaft, the elastomer on the housing being disposed to be immersed in the acid solution in contact with the strip material 'and .being subject to being puncturedby the strip during use, the. annular projections of elastomer carried by the extending ends of the shaft being disposed to limit the er:- tent of flow of acid solution outwardly from the housing to only the covered portions of the ends, the shaft having an opening through each end thereof into the housing, a source of water under pressure, one of the openings being connected to the source or" water to admit Water into the housing, the otherl of the openings being disposed to drain the Water from the housing, and means connected to said other of the openings to control the level of the water in the housing to maintain the housing filled with Water under pressure, the water under pressure Within the housing limiting damage thereto, when the layer of elastomer is punctured and admits acid to the metallic housing, to the area of the housing closely adjacent the area of. the puncture, the Water under pressure Within the housing also providing a visible indication of said damage to the housing as the roll is rotated.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,900,556 l Hitchcock Mar. '7, 1933 2,145,613 Shenk Jan. 31, 1939 2,321,777 Schelhammer June 15, 1943 2,404,606 Trst July 23, 1946 2,608,982 Zademach Sept. 2, 1952