US2146488A

US2146488A - Apparatus for electrolytically pickling metal

Info

Publication number: US2146488A
Application number: US737653A
Authority: US
Inventors: Sykes Wilfred
Original assignee: Inland Steel Co
Current assignee: Inland Steel Co
Priority date: 1934-07-30
Filing date: 1934-07-30
Publication date: 1939-02-07
Anticipated expiration: 1956-02-07

Description

w. sYKEs 2,146,488

APPARATUS FOR ELECTROLYTICALLY PIGKLING METAL Feb. 7, 1939.

Filed July 30, 1934 9 Sheets-Sheet 4l Feb# 7, 1939,

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APPA-RATUS FOR ELECTROLYTICALLY PICKLING METAL l Filed July 50, 1954` SheetS-She'et 4 xx um k n, I'il C@ www W will Ulf@ j h Trl# 4 M@ k Nw mi Q s 3 MW l| 55K *kg-':L-g

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APPARATUS FOR ELECTROLYTICALLY PICKLIMS METAL Filed July 50, 1934 9 Sheets-Sheet 6 Feb. 7, 1939. 2l46,488 l APPARATUS Fon ELECTROLYTIGALLY PIGKLING METAL w. sYKEs $5 heetrwsheet 7 Filed July 50, 1934 NNN Feb. 7, 1939. w. sYKEs 2,146,488

APPARATUS FOR ELECTROLYTICALLY PICKLING METAL Filed July 30, 1934 9 Sheets-Shaet 8 Feb. 7, 1939. w. sym-:s 2,146,488

APPARATS FOR ELECTROLYTICALLY PICKLING METAL Filed July so, 1934 9 Sheng-sheet 9 Patented Feb.A 7, 1939 PATENT ori-ica APPARATUS. FOB ELEUI'ROLYTICAILY y PICKLING METAL wnfrea Sykes, chime, nl.. mignon- 'tp mima Steel Company, Chicago, lli., a corporation of Delaware Application July 30, 1934, Serial No'. 737,653

10 Claims.

My invention relates to the electrolytic pickling of metal objects in general, but more particularly,

\ though not exclusively, to ferrous sheet material,

by which term I intend to include all sheet material such as that known tothe trade by the technical terms strip sheet, strip, sheets, plates, etc., it having been found in practice that by passing an electric current through the pickling solution 'provided for pickling the metal object the pickling operation is accelerated with the manifest advantages.

Heretofore, so far as I am aware, the only use made of electric current for accelerating the pickling operation, has involved the use of direct l5 current introduced into the material to be pickled by some contact means whereby the material itself became one of the electrodes, which procedure, while presenting certain advantages over nonelectrolytic pickling, presents disadvantages and limitations which it is one of my objects to overcome.

Broadly stated, my invention, as to one phase `thereof,contemplateslthe use of alternating -curfrent for effecting tlie electrolytic action, and as to another phase thereof, the application of the current, either alternating current or direct current, to' the pickling bath without direct contact between the metal of either electrode and the metal object to be pickled. Si) Referring to the accompanying drawings:

Figure 1 lrepresents by a view in side'elevation and of diagrammatic nature, apparatus embodying my invention and by which my improved nthod may be practiced in the pickling of ferrous 55 sheet material, the portion of the apparatus shown at the lower end of the sheet of drawingsrepresenting a continuation of the portion thereof located at the upper end of the sheet.

Figure 2 is a view in side elevation of approxi-V 4o mately one-half of one of the similar electrolytic pickling tanks of Fig. l.

Figure 3 is a similar view of the remainder of the tank of Fig. 2.

Figure 4 is an enlarged plan view of a portion 45 of the structure shown in Fig. 2.

Figure 5 is a similar view of the remainder'of the structure shown in Fig. 2.

Figure 6 is `an enlarged longitudinal sectional view of the structure shown in Fig. 4, the section 50 being taken at the line 6 on Fig. 4 and viewed in the direction of the arrow. Figure '7 is an enlarged longitudinal sectional view of the portion o'i.' the apparatus shown in Fig. 5, the section being taken at the line 1 on Fig. 5 66 and viewed in the direction of the arrow.

(o1. coi-s) Figure 8 is an enlarged cross sectional view, through one of the similar electrolytic pickling tanks, the section being taken at the irregular line 8 8 on Fig. 2 and viewed in the direction of the arrows. 5

Figure 9 is a diagrammatic view of a series of two electrolytic pickling tanks showing the circuit connections between the electrodes thereof and a source of supply of three-phase alternating current. Figure 10 is a diagrammatic view of a series of three electrolytic pickling tanks showing the circuit connections between the electrodes thereof and a source of supply of three-phase alternating currentu Figure 11 is a diagrammatic view of one of the electrolytic pickling tanks showing the circuit connections-between the electrodes therein and a source of supply of single phase alternatingcurrent.

Figure 12 is a diagrammatic view of a series of two electrolytic pickling tanks and apparatus for supplying direct current to the electrodes thereof. Figure 13 is a view in longitudinal sectional elevation of a modification of the apparatus of Figs. 1 to 8, inclusive, and of a construction suitable for simultaneously batch pickling large numbers of sheets of lengths not in excess of the length of the tank, the section being taken at the line I3 on Fig. 14 and viewed in the direction of the arrows: and

AFigure 14, a section taken at the line Il on Fig. 13 and viewed in the direction of the arrow.

Referring to Figs. 1 -to 8, inclusive, the particular apparatus shown therein and provided for the pickling of relatively long lengths of sheet material, such as ferrous sheet material, of relatively small cross section and relatively great widths commonly supplied in coiled condition on reels and which may be stitched together at their ends to render the strip continuous, comprises a pair of pinch rolls l5 which operate to feed the strip of sheet material to be pickled and represented at I6,

to the picklingtanks I1, Il, i9 and 20, shown as four in number and arranged in series with rolls 2| at the ends of the series of tanks and between each tank for supporting the strip i6 in looped condition in each tank, the tanks I12l| containing any suitable pickling solution, such as any of the acid solutions commonly used in .the pickling of the -kind of sheet material to be' operated on.

Beyond the pickling tanks areA a cold water tank 22, for rinsing the acid from the strip. and a hot 55 water tank 29 for heating and further washing the strip, rollers 24 extending into the tanks 22 and 23 and rollers 25 and 26 located,respectively,

between the tanks 22 and 23 andl adjacent the discharge end of the tank 23, serving to guide the trs I6 for movement through the liquid in these Beyond the tank 23 are pinch rolls 21 for drawing the strip through the tanks and feeding it to shearing mechanism 28 for cutting out the material at which the stitches between the strips were made.

Beyond the shearing mechanism 28 is oiler mechanism 29 for olling the strip if found to be necessary or desirable, the strip in accordance with common practice being again wound into coiled condition by the coiling means represented generally at 30.

In the particular illustrated apparatus provision is made for the electrolytic pickling in two tanks only, namely, tanks I8 and I9, but as will4 be readily understood the number of tanks in g which such pickling is eiected may be greater or less than those illustrated.

As both tanks I8 and i9 and the electrolytic pickling apparatus of each is of the same construction, the following description, directed to tank I8 and its equipment, will suice.

The tank i8 is formed of a trough-like shell 3l preferably of sheet steel, the inner surface of which is lined with any suitable material, such as porcelain tile represented at 32, with an interposed current-insulating sheet-lining 33, as for example, of vulcanized rubber, between the shell 3| and lining 32.

The body of the tank thus formed and in which the pickling bath is located is provided with a cover portion represented generally at 34 and shown as formed of a metal frame 35 at which the cover rests on the body of the tank and comprising side girders 36 and cross beams 31 secured thereto and sheathed with current-insulating material; a plate portion 38 secured to the frame 35 and formed of metal sheeting 39 sheathed with current-insulating material; and a series of endframes 40 and two intermediate frames 4 I superposed on, and secured to, the plate portion 38. The end frames 40 are shown as formed of side, end, and

cross angle bars

42, 43 and 44, respectively, and the intermediate frames 4I are shown as formed of side and

end angle bars

45 and 46, respectively, hooks 41, by which to lift the cover and the parts carried thereby, as for example by a crane, being carried by the

side angle bars

42 and 45.

The cover 34 is also shown as provided midway between its ends with a chamber 48 opening downwardly into the tank I8 and connected with a pipe 49 through which fumes rising from the pickling bath may be drawn from the tank.

The ends of the cover 34 incline upwardly in spaced relation to the end-walls of the body of the tank as shown in Fig. 6, to present openings to receive the strip I6.

Located in the bottom of the tank I8 beneath, and in spaced relation to, the strip I6 to be pickled, and extending lengthwise of the tank and submerged in the pickling bath l arek two groups, respectively, of plate electrodes 50, 50a, 50h, 5I, 5Ia and 5I", which are spaced apart in end-to-end relation, are of the same length and of a width greater than that of the strip I6 to be pickled, these two groups of electrodes being connected i with buss-bars 50 and 5Ic, respectively, by means of strip-leads 53d and Bld which lead outwardly through channels in the side walls of the tank I8, as represented at I8a.

The electrodes 58, 50B, 50h, 5I, 5Ia and 5Ib are supported on stoneware blocks 52, having reduced end-portions 53, which extend upwardly through openings in these electrodes to a position in which they serve to prevent the strip I6, in its travel through the tank, from contacting with the electrodes.

Located in the tank I8 directly above the

electrodes

50, 50, 50h, and 5I, SIB and 5Ib, respectively, and in spaced atwise-opposed relation thereto and to the strip I6 are two groups, respectively, of

plate electrodes

54, 55, 56, 51, 58 and 59, which are spaced apart in end-to-end relation, extend lengthwise of the tank, and are immersed in the pickling bath, each electrode 54-59 being preferably composed of a metal plate 60, as for example, of copper encased in a lead sheathing 6I, the

end electrodes

54 and 59 carrying depending blocks 62 of insulating material, as for example, of stoneware, as represented of the electrode 54, to insure against contact of the strip I6 with the metal of these elec trodes.

In the particular illustrated apparatus, the electrodes 54-59, inclusive, are mounted to be movable vertically in the tank for adjustment from the operative position shown in Figs. 6, 7 and 8, in which they extend into the pickling bath, into such a position above the bath as to permit the strip I6 When drawn taut to be wholly above the pickling bath, and avoid undue eating away of the strip by the bath in the event of the shutting down of the tanks. Thus the re-threading of a strip to the tanks after each shut down which would be required if the strip remained immersed in the bath due to the destruction of the strip by the bath, is rendered unnecessary.

The mounting and adjusting means for this purpose comprise rods 63 sheathed with acidresisting material 64 connected with the plates 60 of the electrodes 54-59, inclusive, each of these electrodes being shown as carried bythe four of the rods 63, which are vertically slidable in insulated bushings 34"L in the cover 34 and are connected above the cover with current leads hereinafter referred to and forming portions of the electrical circuit by which the electrolytic action is eiectedl The upper ends of the rods 63 are pivotally connected by bolts 65 with the lower ends of rack bars 66 from which they are electrically insulated by fiber bushings and washers on the bolts. 'I'he rack bars 66 are vertically slidable in guideways 61 in heads 68 carried by supplemental frames 69 and 10 secured to the frames 40 and 4I respectively, the racks on the rods 66 meshing with pinions 1I secured to cross-shafts 12 journaled in the heads 68.

One of the shafts 12 carrying the pinions 1I for the

electrodes

54 and 55 is connected through suitable speed-reduction mechanism 13 with an actuating hand-wheel 14 and the others of these shafts are connected together for vsimultaneous rotation by sprockets 15 and sprocket-chains 16.

Those of the shafts 12 carrying the pinions 1I for the

electrodes

56 and 51 are also connected together by sprockets and sprocket-chains, as above referred to, those shown v being represented Aat 11 and 18, and power for rotating these shafts applied to one thereof as by an actuating hand-wheel19 and interposed speed-reduction mechanism 83. Likewise those of the shafts `12v carrying ythe pinions 1I for the

electrodes

66 and 59. are connected together by sprockets and sprocket-chains, those shown being represented at 8| and `82, respectively, and power for rotating these shafts applied thereto through an actuating hand-wheel 83 with interposed speed-reduction mechanism 94. I

I'he end electrodes

54 and 59 are shown as provided with additional guide means to insure against such binding of these electrodes as would interfere with the desired freedom of vertical adjustment thereof, should the strip I8 be drawn taut against them, these additional guide means being shown as comprising channel bars 85 depending from certain. of the crossbeams 31 at opposite sides of the tank and guidingly receiv- Ving projections 88 extending from the side edges of these electrodes.

,l age current, as for example in the As will be understood, high amperage low voltorder of 20,000 amperes at about 9 to 1 5 volts', imposed on the vertically spaced electrodes, causes the current to pass through the pickling bath and strip I8 thereby. accelerating the action of the bath on the strip and greatly reducing the time required for effecting the desired picklin'g of the strip,

over that required where no electrolytic action is produced, thus permitting vof the relatively rapid movement of the strip through the apparatus.

As stated above, one phase of my invention relates to .the feature of interposing the metal object to be pickled between, and in spaced relation to, the opposed electrodes of the electric circuit for producing the electrolytic action, the current used being either alternating current, as for example of 25 or 60 cycles, or direct current. Accordingly', I have illustrated some of the various ways in which' the current either alternating current or dir'ct current, 'may be supplied to the electrodes of the electrolyiiic pickling tanks.

Referring to Fig. 9 which shows a circuit dia- /graminvo'lving the use of alternating current -employing a three-phase circuit, the three line f current conductors leading from a suitable generator (not shown), for Supplying current to such a circuit, are represented at 81, 88 and 89. Two

single-phase step-down transformers 90 and 9| are employed, the primary windings' 92 and 98 of which areconnected to the three leads 81, 88 and 89 and with each other by the current conductor 94 in accordancewith'common practice. The secondary winding 85 of the transformer 90 is connected, in parallel, by

current conductors

lower electrodes

50, 50* and 50b of the tank I8 through bussbars 50 and, by a current conductor |08 and branch current conductors |08, ||0 and III, with the

upper electrodes

54, 55 and 58.

The secondary winding I|2 of the transformer |88 connects by a current conductor I I8 with the lower electrodes V5|, through the buss-bar 5I, and by a current conductor ||4 and branch current conductors II5, ||8 and ||1 with the

electrodes

51, 58 and 59,

The secondary winding I I8 of transformer 9| is connected,`in parallel, with the primary windings ||9 and`|20 of single-phase transformers |2| and |22, by current 'conductors |23, |24, |25 and |28 with interposed tap selector ,switches |21l and |28, as explained of the connections between the secondary winding 95 and the primary windings |00 and IOI. The secondary winding |29 of the transformer |2| connects by a current conductor |30 with the lower electrodes 50, 50a and 50b of tank I9 through the buss-bar 50 connecting these electrodes, and by a current conductor I3| and branch current conductors |32, |33 -and |34 with the

upper electrodes

The three-phase current is thus converted by the transformers 90 and 9| into two-phase current, the strip I8 itself representing the neutral connection of the. two-phase secondary circuit each phase of the two-phase current being connected with the electrodes of a tank so that a substantially balanced load is maintained on the three-phase circuit.

It may be here stated that the number of tanks in which the electrolytic action is to be produced and the matter of the grouping of electrodes in the tank or tanks as the case may be, may be varied to suit the particular conditions presented. vThus in some cases, the electrolytic action may be confined to a single pickling tank; two as illustrated in Figs. 1-9, inclusive; three as illustrated and further commented upon herein, or even more; the purpose being to provide as many pickling tanks, connected in series, with the electrolytic pickling' provided for in certain thereof, as may be necessary to effect the exposing of as much surface to be pickled, to the electrolytic pickling action, as may be required to correspond with the speedof the strip through the tanks.

'I'he matter of the dividing of the electrodes into several sections as for example as illustrated `in Figs. 1-9, inclusive, and above described, is

rent ow throughout the length of the tank may be balanced; and, in the case of alternating current, reducesexcessive voltage losses.

The use of three electrolytic pickling tanks in series andsupplied with alternating current from a three-phase source is illustrated in Fig. 10 wherein the tanks corresponding with tanks' I8, I9 and 20, are represented at I8', I9 and 20', each. being equipped as described above-as to tanks I8 and I9, to-electrolytically pickle the strip.

In this arrangement, the three line current'l conductors of the three-phase alternating current circuit, supplied from a suitable generator ,(not shown), are represented at I4I, |42 and |43 and, in accordance with common practice, are connected with the primary windings |44, |45 and |48 of step-down single-phase transformers |41, |48 and |49, respectively.

The secondary winding |50 of the transformer |41 supplies current to the

electrodes

50, 50, 50h, 5|, 5|* and 5I", and 54- to 59, inclusive, of

tank .I8' through single-phase transformersv |5| clusive, of the respective tanks |9' and 20', as-

explained above of the supplying f current through the transformers |61, |5| and |52 to the electrodes of tank |62 The use of a single tank in which the electrolytic pickling is effected is represented in Fig. 11 wherein the pickling tank represented at I6" is provided with electrodes 50, 60B, 50h, 5|, 5| and 5|b, and 56 to 59, inclusive, as in the case of tank i8. In this arrangement the current for electrolytically pickling is shown as single phase alternating current supplied from any suitable source, the line current conductors being represented at |69 and |60 and connecting with the primary winding |6| of a step-down transformer |62. The secondary winding |65 of the transformer |62 supplies current to the

electrodes

80, 50", 5|, 5|, and 6|, and 54 to 59, inclusive, through single-phase transformers |64 and |66 as described oi' the supplying of current from the transformer 90 of Fig. 9 to the electrodes of tank I8 as shown in said ligure and as above described.

Referring to Fig. 12, which represents, by way of example, an arrangement whereby direct cur rent is utilized to produce the electrolytic action, the pickling tanks therein shown are each represented, but without intention of restricting the invention thereto, as containing a pair of single electrodes |66 and |61 corresponding, respectively, to the six

electrodes

50, 50, 50h, 5|, 5|n and 5|h and the six electrodes 5449, inclusive, of the preceding figures of the drawings and spaced from the strip i6 as explained of the grouped electrodes above referred to.

The direct current i'or these two tanks which may be provided in multiples thereof, if desired, y

is shown as supplied from low-voltage high-amperage direct current generators |66 so connected, as shown, with the two sets of electrodes |66 and |61 that the flow of current between the electrodesin one ofthe tanks is in a direction opposite to the now of current in the other tank, whereby the accelerated pickling action is ei'- fected rst on one face oi' the strip I8 in its passage through the rst tank, and then on its opposite i'ace in its passage through the second tank, producing substantially uniform pickling of both faces ofthe strip:-

The generators |68 may be driven in any suitable way, as for example by alternating current or direct current high voltage motors represented at |69.

In Figs. 13 and i4 I have shown my invention as utilized in the batch pickling oi lengths oi' metal material less than that of the pickling tank, 'such as so-called sheets, supported on a suitable holder adapting the sheets to be lowered and raised in the tank, as for example by a crane.

'I'he cradle structure thus provided and such of the parts of which as may be made of metal being covered by current-insulating material, such as rubber, is adapted to be lowered for the complete immersion of the sheets |10 in the pickling bath contained in the tank represented at |8I, the cradle structure resting at the cross bars |14 on spaced apart girders |82 provided on the bottom of the tank.

This construction as shown involvesthe use of stationary opposed plate electrodes located in the tank and completely submerged in the pickling bath and in spaced relation to the cradle, these electrodes, shown as in the form of plates, and which may extend substantially the full length of the tank either as single plates or in groups, as for example as explained above of the constructions in the preceding gures of the drawings, being represented at |83 and |84 and to which the desired electrolytic pickling current would be supplied. Such current may be either direct current or alternating current and may be supplied in any suitable way, as for example in accordance with the various electrical arrangements shown in the preceding iig'ures of the drawings and described above. In the case of the use of direct current any suitable means may be provided for reversing the direction bf flow oi' the current relative to the ilacessy of the sheets |10. In the arrangement shown this may be effected by lifting the cradle and the sheets carried thereby clear of the tank after subjecting corresponding faces of the sheets to the electrolytic pickling action, and turning the 4cradle end for end through a half revolution and again lowering the cradle into the tank to subject the other corresponding faces of the sheets to the electrolytic picklingv action.

As will be understood, the ilow of current will be from onev of the electrodes |83 and |84, thence through the bath to the nearest sheet and from the latter, through the bath, to the next sheet, and so on to the last sheet and thencefrom the bath to the other of the electrodes |89 and |84.

'I'he feature of applying the electric current to the pickling bath without direct contact between the metal of the electrodes and the metal object to be pickled is of great advantage particularly in the case of the pickling of sheet material of relatively great width andv of small cross section. To obtain effective electrolytic pickling action current density in the order of 100 amperes per square foot of surface oi' the sheet material to be pickled, is necessary, requiring, where the thin sheet material constitutes one of the electrodes, as in the case of prior practice, a great` multitude of contacts at relatively close intervals along the length of the sheet material. otherwise the resistance of the sheet material is such that the electric current will leak oiI close to the contacts and considerable portions oi the strip material will be unailected by the electric current. By providing for the sep- .aration of the electrodes from the material to be pickled, as above referred to, the above disadvantage is avoided and the action of the electric current is such as to cause the sheet material to be acted on substantially uniformly throughout the faces thereof exposed to the electrolytic action.

'I/'he use of alternatingv current to perform the electrolytic action is also of great advantage. Even when used under conditions in which one of the terminals of the alternating current circuit is electrically connected with the strip material (which would require an arrangement in which provision is made for causing the current to pass through the pickling bath to opposite faces of the sheets in succession', as by reversing the position of the electrode spaced from the sheet material so that for a suilicient length of time current would pass through the bath to one face of the sheet material to effectively pickle this face and then through the bath to the other face of the sheet material to eifectually pickle it) the use of such current is of advantage as thereby great economies are effected in that the stationary transformer required in view of the large currents necessary, is much more economical of construction and more easily built, thana dynamo which is required when direct current is used.

The use of alternating current where the sheet o material is run through the tanks in long strip form, as in the construction shown in Figs. 1-8, inclusive, or when relativelyshort length sheets are pickled in a batch operation as for example as shown in Figs. 13 and 14, and the metal of the electrodes is maintainedv out of contact with the `material being pickled, presents the additional advantage in' that the current ows into r.and away from the sides of the strip alternately, the variation depending upon the frequency used, and both sides of the sheet material are pickled equally effectively.v

It may be stated by way of example, but without intending to th'ereby limit the invention in any way, that in the installation shown in Figs. 1 to 8, inclusive, each tank |8-2I may be approximately 60 feet long and the lower electrodes and the upper electrodes each of a total length of approximately 40 feet and where sheet material 48 inches wide is to be pickled the total area exposed between the electrodes may be approximately 160 square feet.

While I have illustrated and described certain particular constructions of apparatus `embodying my invention and by which my novel method,l

may be practiced', I do not wish to be understood as intending to limit lit ythereto as various changes and alterations may be made in the apparatuses shown, and the method practiced by other forms of apparatus (such as for example,v provision made for simultaneously electrolytically pickling a plurality of the moving strips immersed inthe pickling bath and flatwise opposed in spaced re. lation to each other between, and out of contact with, the metal of the electrodes between which the strips would travel, the current passing from one electrode through the bath to the strips in succession and thence to the other electrode) without departing from the spirit of my invention.

What I claim as new, and desire to secure by Letters Patent, is:

1. In electrolytic pickling apparatus, the combination of a tank containingy a pickling bath,

upper andlower electrodes, means for supporting sheet material to be pickled 'for movement through said bath and between, and out of electrical contact with, said electrodes, and means l for adjusting the upper electrode into, and out of, 'immersed position in said bath, whereby the 5 sheet material may be raised out of contac with the bathl 2. In electrolytic pickling apparatus, the combination of tanks containing metal pickling baths and through which the objects to be pickled are passed in succession, means for producing electrolytic action in said baths comprising electrodes in contact with said baths, a 3-phase electric current supply, and means dividing the current'from said supplyand applying it to said electrodes, whereby the load on the circuit' is balanced.

3. In electrolytic pickling apparatus, the cornbination of a tank containing a metal pickling bath, spaced apart electrodes of opposite polarity in contact with said bath and means for supporting strip material to be pickled for movement in'the bath between, and out of electrical contact with. said electrodes, certain of said electrodes being formed of spaced apart sections in end to end relation.

4. In electrolytic pickling apparatus, the combination of a, tank containing a metal pickling bath, spaced apart electrodes of opposite polarity in contact with .said bath and means for supporting strip material to be pickled for movement in the bath between, and out of electrical contact with, said electrodes, each of said electrodes being formed of spaced apart sections in end to end relation.

5. In electrolytic pickling apparatus, the combination of a tank containing a metal pickling bath, spaced apart electrodes of opposite polarity in contact with said bath and means for supporting strip material to be pickled for movement in the-bath between,'and out of electrical contact with, said electrodes, certain .of said electrodes being formed of spaced apart sections in end to end relation and of the same polarity.

6. In electrolytic pickling apparatus, bination of a tank containing a-metal pickling bath, spaced apart electrodes of opposite polarity in contact with said bath and means for supporting stripvmaterial to be pickled for movement in the bath betwe'n; and out of electrical contact with, said electrodes, both of said electrodes being formed of sections spaced apart in end to end relation lengthwise of the tank.

7. In electrolytic pickling apparatus, the combination of a tank containing a metal pickling bath, spaced apart electrodes in contact with said bath and means for supportingv strip material to be pickled for movement inthe bath between, and out of electrical contact with, said electrodes, certain of said electrodes being formed of spaced apart sections, certain of said electrodes opposing each other crosswise of the path of movement of the strip material and being of opposite polarity, traverses the strip crosswise whereby current thereof.

8. In electrolytic pickling apparatus, the combination of a tank containing a metal pickling bath, spaced apart electrodes in contact with said bath and means for supporting strip material to be pickled for'movementv in the bath between and. out of electrical contact with, said electrodes, each of said electrodes being formed of spaced apart sections, certain of said electrodes opposing each other crosswise-'of the path of movement of the strip material and being of opposite polarity, whereby current traverses the strip crosswise thereof,

9.- In electroyltic pickling apparatus, the combination of a tank containing a metal pickling bath, spaced apart electrodes in contact with said clsv bath and means for supporting strip material to be pickled for movement in the bath between,

and out of electrical contact with, said electrodes, certain of said electrodes being formed of spaced apart sections of the same polarity, certain of said electrodes opposing each other crosswise of the -path of movement of the strip material and being of opposite polarity, whereby current traverses the strip crosswise thereof.

10. In electrolytic pickling apparatus, the combination of a tank containing a metal pickling