US3391073A - Anodizing apparatus - Google Patents

Description

July 2, 1968 RUSCH ET AL ANODIZING APPARATUS 4 Sheets-Sheet 1 Filed Aug. 24, 1964 lwvamons RONALD L. RUSCH CHARLES H.ORDING KW V ATTYS.

ly 2, 1968 R. 1.. RUSCH ET AL 3,391,073

ANODIZING APPARATUS 4 Sheets-Sheet 2 Filed Aug. 24. 1964 201 33 37 r INVENTORS Romw L. RuscH CHARLES H. ORDING July 2, 1968 R. L. RUSCH ET Al. 3,391,073

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July 2, 1968 Filed Aug. 24, 1964 R. L. RUSCH ET AL.

ANODIZING APPARATUS 4 Sheets-Sheet 4 RONALD L. RuscH CHARLES H. Gnome United States Patent 3,391,073 ANODIZING APPARATUS Ronald L. Rusch, Northbrook, and Charles H. Ording,

Palatine, lll., assiguors to Aluminum Coil Anodizing Corporation, Fox River Grove, Ill., a corporation of Illinois Filed Aug. 24, 1964, Ser. No. 391,617 11 Claims. (Cl. 204-202) ABSTRACT OF THE DISCLOSURE A continuous anodizing apparatus having a titanium or zirconium endless conveyor belt on which are mounted a multiplicity of removable strip article holders, each holder supporting a multiplicity of articles to be anodized, said articles being moved by the apparatus through the anodizing electrolyte by the endless belt in a predetermined tortuous path so that the position of each article is repeatedly varied about 90 each direction from the vertical during the anodization.

The present invention relates to apparatus for anodizing metal particles, such as aluminum. (The anodizing process is generally one wherein the surface of a metal, such as aluminum, is oxidized by immersing the metal connected to a source of positive voltage in an acid electrolyte such as sulfuric acid.)

In the anodizing process as heretofore practiced, the articles to be anodized were generally placed in metal baskets or racks carried on a conveyor. The conveyor moved the article carrying baskets or racks sequentially over an open-top tank containing the anodizing electrolyte and then lowered the baskets or racks into the tank for the required period after which the baskets were raised and then carried to other tanks containing various chemicals for rinsing, dyeing, and/ or sealing the anodized surfaces of the articles. The baskets or racks carrying the articles to be anodized must be electrically connected to the positive terminal of a source of direct current voltage so that the articles to be anodized have a positive voltage thereon through their contact with the baskets or racks. In general, the equipment which has been used for anodizing articles is similar to the equipment generally used in electroplating articles. In the electroplating process, the articles to be plated are connected to the negative terminal of a source of direct current voltage and metal is deposited by a reduction process upon all of negatively charged metal surfaces within the electrolyte. In such case, for example, the basket or rack carrying the articles would be plated along with the articles involved. It is generally impractical, therefore in electroplating equipment to physically immerse the conveyor equipment carrying the baskets or racks into the electrolyte, although such immersion was suggested from time to time. It was perhaps not appreciated by the people who designed anodizing equipment that there are important advantages to immersing the conveyor equipment in the electrolyte without the accompanying disadvantages, since the anodizing process, unlike the electroplating process, will not affect all immersed metal surfaces having the same charge as the articles to be anodized. Thus, titanium and zirconium will not be anodized or corroded when immersed 3,391,073 Patented July 2, 1968 in an aluminum anodizing electrolyte like sulfuric acid with a positive voltage applied thereto.

The type of equipment heretofore used in conveying articles to be anodized to the open-top electrolyte containing tanks, as above indicated, suffers from a number of disadvantages. In the first place, the conveyor equipment and the controls therefor which intermittently caused longitudinal and then transverse up and down movement of the baskets required frequent replacement. Also, such equipment, for reasons to be explained, frequently did not produce a uniform finish, particularly where imperforate cup-shaped articles were involved which became inverted in the racks or baskets.

The present invention represents a marked improvement in anodizing equipment. Thus, in the anodizing equipment of the present invention to be described, the articles to be anodized are carried into and out of the open-type electrolyte containing tank by a positively charged continuously longitudinally moving, endless conveyor which passes directly into the electrolyte. The positively charged conveyor is made of a material like titanium which is not affected by the electrolyte and the guide supports for the conveyor located within the electrolyte are preferably insulated from the voltage source involved so that it can be made of a material like stainless steel which is not affected by the anodizing electrolyte if, kept electrically neutral. The conveyor, is most advantageously an endless belt made of sheet metal, which moves in a steeply undulating path in the electrolyte so that there is a maximum path length for a tank or given length to minimize floor space requirements, and so that the articles are turned over appreciable angles as the direction of the path reverses in the electrolyte to prevent the collection of gas pockets in imperforate cup-shaped articles which will prevent the formation of a uniform anodized coating thereon.

Other features of the invention relate to the manner in which the articles are attached to the belt conveyor and are automatically removed therefrom. For example, the articles are preferably carried on spring metal clips attached to carrier strips or bars which are readily removable from the belt. The equipment is thus usable with different articles by merely removing one set of carrier strips and substituting another set with differently sized or shaped clips. Some other features of the invention relate to the construction of roller carrying frame assemblies which guide the belt conveyor in and out of the various tanks involved.

The above and other advantages and features of the invention will become apparent by making reference to the specification to follow, the claims and the drawings wherein:

FIG. 1 is a side elevational view of anodizing apparatus incorporating features of the present invention;

FIG. 2 is a fragmentary view of the anodizing tank portion and associated belt supporting and guiding assembly supported therein of the apparatus shown in FIG. 1 with parts thereof shown in exploded view;

FIG. 3 is an enlarged vertical sectional view of the anodizing tank portion and associated belt supporting and guiding assembly supported therein of the apparatus of FIG. 2, taken substantially along the lines 3-3 in FIG. 1;

FIG. 3A is an enlarged sectional view of a portion of the apparatus shown in FIG. 3;

FIG. 4 is an enlarged vertical sectional view of a portion of the apparatus shown in FIG. 1 taken substantially along the lines 4-4 thereof, and illustrating the construction of a drive roller and the support units therefor;

FIG. 5 is a side elevational view of one of the drive roller support units shown in FIG. 4;

FIG. 6 is a partial horizontal sectional view through the apparatus of FIG. 4;

FIG. 7 is a fragmentary plan view of the discharge end of the apparatus shown in FIG. 1;

FIG. 8 is a vertical sectional view of the apparatus through the portion of the apparatus shown in FIG. 7 taken along the lines 8-8 therein; and

FIG. 9 is an enlarged fragmentary sectional view through the sheet metal belt forming a portion of the apparatus of FIG. 1.

Referring now more particularly to FIG. 1, the anodizing apparatus there illustrated includes a series of opentop tanks into which aluminum articles 1 shown in FIG. 3 to be anodized are sequentially carried by a unique conveyor system 2 to be described. The first tank 4 to which the articles are carried from a loading station 3 contains a suitable aluminum cleaning non-etchant material as, for example, a non-silicated cleaner sold under the name Redi Aluminum Cleaner No. 1, manufactured by the Redi Chemical Co. of Barrington, Ill. Next, the articles are delivered to a water rinsing tank 5 which rinses the cleaning material. The articles are then carried into a pair of anodizing tanks 6 and 6a which contain a solution of sulfuric acid, the level of the acid in the tanks 6 and 6a being identified by reference numeral 7. As will appear, the conveyor system is insulated from the anodizing tanks 6 and 6a and is connected to the positive terminal of a source of direct current voltage. The tanks 6 and 6a are connected to the negative terminal of the voltage source. The articles are then delivered to a water-filled rinsing tank 8 and then to a tank 10 containing a sealing material, such as a solution of nickel-acetate, which seals the pores of the oxide coating resulting from the anodizing treatment in a well known manner. Following the sealing operation, the articles 1 are delivered to a drying tank 12, which may be a well known type of tank containing suitable sources of heat, such as gas burners, for drying the articles involved. After removal from the tank 12, the articles are delivered to a discharge station 14 where the articles are automatically discharged in a manner to be explained. If desired, additional treatment tanks may be added to the apparatus shown for carrying out additional operation, such as dyeing and the like. The various steps in the anodizing process just described are exemplary only.

One of the important aspects of the present invention is the manner in which the articles 1 are carried into and out of the various tanks. As previously indicated, it was common in anodizing apparatus to utilize a rather complex conveyor system where the articles were carried in racks or baskets which are first longitudinally moved into position over a given tank and then dropped into a tank where the racks or baskets remain in a stationary condition for a given period after which the baskets or racks are raised out of the tank and then moved longitudinally over the next tank. In the preferred form of the invention, the conveyor system 2 most advantageously is an endless belt of titanium or zirconium sheet metal which is rugged and is not corroded or anodized by any of the liquid materials in the tanks 4, 5, 6, 6a, 8 and 10. The belt 20 is continuously advanced through the various tanks through a steeply undulating path. Particularly in the anodizing tanks 6 and 6a, the steeply undulating path comprises a number of long vertical segments connected by short horizontally curving segments occurring when the direction of movement of the belt is reversed. Such a configuration has a number of important advantages. In the first place, relatively long dipping operations can be effected with a continuous movement of the belt 20 with modest longitudinal tank dimensions, so that the tanks require a minimum of floor space. In the aluminum anodizing process being described, it can be seen that the total vertical path length in the tanks 6 and 6a is quite substantial relative to the length of the tanks. In the second place, as will appear, where the articles to be anodized are placed in inverted position against the upper surface of the belt, any liquid collecting in the articles as they are moved through the electrolyte will be dumped back into the tank when the belt moves out of the tank. Also, as the articles are varied in position in being carried into a new vertical path, any gas pockets which may be present in the articles are moved substantially about and usually escape from the articles, so that the anodizing electrolyte will contact all interior as well as exterior surfaces of the articles.

Referring, for example, to FIGS. 4, 7 and 9, the endless sheet metal belt 20 is provided with longitudinally spaced pairs of laterally spaced slits 25-25 distributed over the full length thereof. Each pair of slits 25-25 form means for resiliently and removably mounting a narrow, elongated, fieXible, resilient carrier strip or bar 29. Each of the strips has a pair of reduced projections 31-31 at the ends thereof which fit into a pair of the slits 25-25. The carrier strips 29 can be remove-d from the belt by simply pulling the same from the slits, the flexibility thereof enabling the same to flex and shorten about a transverse axis.

The carrier strips 29 each carry a number of spaced spring metal clips 33 which removably carry the cup-shaped articles 1. Each clip 33 has two pairs of upwardly and outwardly extending fingers 33a-33a, each of which has an inwardly curved outer end 33b. The fingers have an extent somewhat greater then the size of the Opening of the articles 1. The inverted cup-shaped articles 1 can, therefore, be readily applied to the clips by inverting the same and pressing the same down over the rounded ends of the clips which causes the fingers to be cammed inwardly to allow the article to be telescoped over the clip and securely held on. As previously indicated, the provision of carrier strips 29 which are readily removable from the belt 20 enables the ready substitution of different sized clips on the belt 20 for carrying various sized and shaped articles. The carrier strips 29 are attached to the outside of the belt 20 so that they are on the top of the upper section 20a of the belt and on the bottom of the lower section 20b of the belt.

The lower section 20b of the belt rests upon the upper surfaces of idler rollers 37 supported upon the vertical webs 39a-39a of I beams 39-39 which form a support base for the entire apparatus. The upper flanges 3911-3917 of the I beams 39-39 support the various tanks 4, 5, 6, 6a, 8, 10 and 12, as well as other portions of the apparatus to be described. The anodizing tanks 6 and 6a are preferably insulated from the I-beams flanges by layers of insulation 41 (FIG. 3) placed beneath the tanks.

As best shown in FIG. 3, each of the anodizing tanks 6 and 6a has a terminal post 42 to which is connected a conductor 43 extending to the negative terminal of a suitable source of direct current voltage (not shown) of a magnitude, for example, in the neighborhood of from 20 to 30 volts.

The lower section 2012 of the belt 20 passes upwardly around endmost bottom cylindrical drive rollers 45-45 and joins the upper section 20a of the belt at endmost upper drive rollers 45-45. The upper and lower endmost drive rollers 45 are rotatably supported between pairs of vertical frame side walls 47 and 48 supported in a suitable manner from the I-beams 39-39. Each drive roller 45 is driven by a common endless chain 49 engaging a sprocket wheel 50 attached to a shaft 51 of the roller. The bottom section of the chain 49 passes beneath the upper flange of one of the I-beams 39 where it is engaged and guided by sprocket wheels 50" rotatably supported on the I-beam web 39a (FIG. 3).

The upper section 20a of the endless belt 20 passes around a series of similar drive rollers 45 above and adjacent the ends of the various tanks and beneath various guide rollers 52 and, in the case of the anodizing tanks, around contact rollers 52', supported in a manner to be described within the various tanks. The latter drive rollers 45 have similar sprocket wheels 50 driven by the chain 49. At the discharge station 14, the belt 20 passes straight down between the upper and lower endmost drive rollers 45, but the chain 49 passes around adjustable sprocket wheels 53.

The upper endmost drive roller 45 at the discharge station has a second sprocket wheel 50" attached thereto which is engaged by a chain 54 driven by a drive sprocket wheel 55 carried on a shaft 56 which carries another sprocket wheel 57 engaged by a chain 58. The chain 58 is driven by a sprocket wheel 60 carried on the shaft of a motor unit 62. The motor unit 62 is illustrated as supported upon a support base 64 carried upon the upper flanges 39b of the I-beams 39-39.

The various guide rollers 52 in the various tanks form part of belt supporting and guiding assemblies 72, 74, 76, 78, 80 and 82, suspended respectively in the tanks 4, 5, 6, 6a, 8, or 12. A description will now be given of the belt supporting and guiding assembly 76 associated with each anodizing tank 6 and 6a, it being understood that the other assemblies have similar constructions. Corresponding elements of these assemblies are similarly numbered.

The belt supporting and guiding assembly 76 associated with each of the tanks 6 and 6a include a pair of vertical support plates 84 and 84 which extend downwardly into but in spaced relation to the associated tanks, as best illustrated in FIG. 3. The plates are rigidly tied together by a spacer sleeve and rod assembly 85 anchored thereto. Rotatably supported between the bottom portions of the plates 84-84 are three longitudinally spaced guide rollers 52. At least the belt contacting surfaces of the rollers 52 are coated with a suitable layer 86 (FIG. 3) of insulating material like Teflon, which is not affected by the anodizing electrolyte and insulate the rollers from the voltage on the belt, and each of the guide rollers 52 has a shaft 88 which is rotatably supported in suitable bearings 90-90 secured to the support plates 84-84. A pair of transverse end walls 91-91 are secured to the end portions of the shaft 88. The end walls have confronting axially inwardly extending flanges 92-92 which, together with the ends of the end wall projecting therebeyond, define guideways for the upper section a of the belt passing around the bottom portions of the guide rollers. The aforesaid insulating layer 86 is applied at least to the surfaces of guideways.

The plates 84-84 rotatably support a pair of upper cylindrical contact rollers 52' which are positioned preferably above the level of the associated tank 6 or 6a at points between the guide rollers 52. The upper section 20a of the belt thus passes around the bottom of each of the guide rollers 52 and around the tops of the contact rollers 52. (The contact rollers 52 are replaced by guide rollers 52 in the belt supporting and guiding assemblies of the tanks 10 and 12.)

Each of the contact rollers 52 has a cylindrical metal outer wall 102 which makes good electrical contact with the belt 20 passing therearound over substantially the entire length of the outer wall 102. The contact roller 52 has metal end walls 104 which terminate in metal bosses 106 which are electrically and mechanically connected to a shaft 108 journalled in suitable bearings 110 anchored to the support plates 84-84 by bolts 111. The positive terminal of the aforesaid source of direct current voltage is connected to the ends of the shaft 108 associated with each of the contact rollers 52 by a pair of brushes 112- 112 riding upon the rotating ends of the shaft 108. The brushes 112 are carried by suitable bus bars 114 which are connected by suitable conductors to the aforesaid positive terminal. The bearings and shaft 108 are preferably insulated from the bolts 111 and the support plates by suitably placed insulation 115 so that support plates and the guide rollers 52 supported thereon will not have any voltage thereon.

All the parts of the belt supporting and guiding assembly 76 which are contacted by electrolyte are preferably made of stainless steel. (The stainless steel would be corroded by the electrolyte if the positive voltage on the belt 20 were applied thereto, hence the need for the insulating layer 86 thereon.) The cylindrical outer wall 102 of each of the contact rollers 52' which contact the wetted belt 20 is also preferably made of stainless steel. The shaft 108 and the end walls 104 of each of the contact rollers 52 as shown are not made of stainless steel and so, to prevent damage to these parts of the rollers by dripping acid, a suitable coating 11-6 of rubber is placed on the exposed surface of the end walls 104, the associated bosses 106 adjacent portions of the shaft 108.

Each of the support plates 84 has a pair of laterally extending wings 84a-84a at the upper outer ends thereof that are anchored as by bolts and nuts or the like to a vertical flange of a pair of take-up units 122 positioned at opposite ends of the associated tank. (There is a takeup unit 122 at each end of the various tanks 4, 5, 6, 6a, 8, 10 and 12.) It is apparent that by unbolting the support plates 84-84 of any be-lt supporting and guiding assembly, the entire assembly can be removed as a unit from the associated tank. This feature is useful for servicing the apparatus or alleviating jamming which might occur within the tanks.

Each take-up unit other than the ones at the outer ends of the endmost tanks 4 and 12 are supported on a vertical post 124 having a base 126 secured in any suitable way and insulated from the upper flange 39b of one of the I- beams 39. The outermost pairs of take-up units 122 are mounted upon the associated vertical frame plates 47 and 48. Each take-up unit includes a vertical bearing carrying slide member which, in the illustrated embodiment of the invention, is provided with spaced vertical side channels 128-128 (FIG. 6) slidably encompassing spaced vertical guide edges 130-130 of the take-up unit. A screw 132 is anchored to the slide member 125, the screw passing through an upper wall 133 of the take-up unit. A nut 135 threads around the end of the screw above the upper Wall 133 and thus, by rotating the nut 135, the screw and the slide member 125 attached thereto is raised and lowered. Each slide member 125 has a bearing 139 for journalling one end of the shaft 51 of a drive roller 45 or the shaft 108 of a contact roller 52. (All of the take-up units except the one at the left hand end of the tank 6 support drive rollers.) By varying the elevation of the slide member 125 and the associated drive or contact roller rotatably supported thereon, the tension of the belt 20 can be readily varied.

Referring now more particularly to FIG. 4 which illustrates the construction of the drive rollers 45. Each drive roller 45 has a cylindrical outer wall 149 carrying a rubber sleeve 150 which makes a good frictional contact with the belt 20, and end Walls 151-151 terimnating in bosses 152-152 secured to the shaft 51. A sprocket wheel 50 is fixed to the end of the shaft 51.

As previously indicated, means for automatically stripping articles are carried on the clips 33 at the discharge station 14. This means includes a plurality of pairs of stripping fingers 156-156. The stripping fingers 156 are carried on brackets 158 (see FIGS. 7 and 8) mounted on a rod assembly 159 anchored to the vertical frame plates 48-48. The stripping fingers 156 extend to a point contiguous to the top of the endmost drive roller 45 and they incline at a substantial angle extending downwardly and outwardly away from the drive roller. Each pair of stripping fingers 156-156 are spaced apart and positioned to enable one of the rows of the clips 33 to pass therebetween as the belt passes down around the latter drive roller. The spacing of each pair of stripping fingers is, however, less than the overall width of the articles sup ported upon the clips 33. Thus, as the belt 29 passes down around the endmost drive roller 45 and the clips 33 move below the stripping fingers 156156, the articles 1 are stripped from the clips. A pair of hold down bars 157- 157 extend over and close to the drive roller 45 to hold the carrier strips 29 down as the articles are stripped from the clips 33. The stripped articles slide by force of gravity down the inclining upper surfaces of the stripping fingers where they finally slide olf the fingers into a suitable container or on a conveyor (not shown).

It is apparent from the exemplary apparatus shown in the drawings, that the present invention provides a very simple, reliable, and efficient means for conveying articles to be anodized into and out of the various open-top tanks. Also, due to the steeply undulating paths of the belt within the liquid of the various tanks, a maximum path length is achieved in each of the tanks with a minimum tank size. Also, the path configuration of the conveyor in the anodizing tanks prevents collection of the gas pockets which cause non-uniform anodizing in imperforate cupshaped articles. In this connection also since the cupshaped articles are in inverted position held on the outside of the belt they will automatically be drained of all liquid as the belt curves into a horizontal position upon leaving each tank. Furthermore, the construction of the belt supporting and guiding assemblies is such that the equipment can be readily assembled and dis assembled for servicing and eliminating jamming and the like.

It should be understood that numerous modifications may be made in the most preferred form of the invention described above without deviating from the broader aspects of the invention.

We claim:

1. In combination with an open-top tank containing an electrolyte for anodizing metal articles, a conveyor sys tem for carrying articles into and out of the electrolyte in said tank from the top of the tank, said conveyor system comprising: an endless conductive conveyor immune to said electrolyte and non-anodizable therein and having article carriers distributed therealong for removably holding articles to be anodized, said conductive conveyor comprising an endless belt provided with longitudinally spaced pairs of laterally spaced slots, and said article carriers being carried on resilient sheet metal bars each having projections on the ends thereof fitting into a pair of said slots and removable therefrom by bending the bars along a transverse axis to shorten the same, means within and without said tank for guiding said endless conveyor for continuous longitudinal movements along a predetermined continuous path which passes an article feeding station before entering the open-top of said tank and an article discharge station after leaving the open-top of said tank, means for continuously driving said conveyor along said path, a source of direct current voltage having positive and negative terminals, and means connecting the positive terminals of said source of direct current voltage to the articles to be anodized through said endless conductive conveyor.

2. In combination with tank means holding electrolyte for anodizing metal articles, a conveyor system for carrying articles into and out of the electrolyte in said tank means, said conveyor system comprising: an endless conductive conveyor made of one of the group consisting of titanium and zirconium immune to said electrolyte and non-anodizable therein and having article carriers distributed therealong, said article carriers including means for removably holding articles to be anodized, guide means within and without said tank means guiding said endless conveyor for continuous longitudinal movement along a predetermined continuous undulating path which passes an article feeding station before entering said tank means and an article discharge station after leaving said tank means, means for continuously driving said conveyor along said path, a source of direct current voltage having positive and negative terminals, and means connecting the positive terminal of said source of direct current voltage to the articles to be anodized through said endless conductive conveyor comprising a series of current carrying members making physical contact with said endless conveyor at a number of longitudinally spaced points of the path of travel thereof between the point of entry of the endless conveyor into said tank means and the point of exit thereof from the tank means, to feed current thereto at a number of different locations between said entry and exit points.

3. The combination of claim 2 wherein said endless path is a steeply undulating path between said points of entry and exit into said tank means and which path repeatedly enters and momentarily leaves the electrolyte in said tank means, and said current carrying members making physical contact with said endless conductive convcyor at the points where the endless conductive conveyor momentarily leaves the electrolyte in said tank means.

4. The combination of claim 2 wherein said current carrying members also act as part of said guide means.

5. The combination of claim 4 wherein said combination current carrying members and guide means are rotatably mounted conductive cylinders around the periphery of which passes the endless conductive conveyor.

6. The combination of claim 2 wherein said endless conductive conveyor is an endless sheet metal belt.

7. The combination of claim 2 wherein said endless conductive conveyor is an endless belt which has distributed across the width and length thereof said article carriers.

8. The combination of claim 7 wherein the belt has a width somewhat less than the corresponding dimensions of said tank means.

9. The combination of claim 2 wherein said guide means within said tank means supporting said endless conveyor being immersed in the electrolyte and being a material which will not anodize in the electrolyte or corrode therein if maintained electrically neutral, said guide means within said tank means being insulated from said source of direct current voltage.

10. The combination of claim 2 wherein the metal articles to be anodized are imperforate cup-shaped metal articles, said article carriers removably hold said cupshaped articles to be anodized, and said undulating path of said conveyor in the electrolyte following a curve where the angular position of the cup-shaped articles is varied as much as 9 0 degrees to allow any entrapped air to escape to eliminate the presence of unanodized areas.

11. The combination of claim 2 wherein said tank means includes at least one tank, a conveyor supporting and feeding assembly raisable and lowerable as an unit in and insulated from each tank, said assembly including a pair of support members extending down into said tank on opposite sides thereof, a first series of horizontally spaced rotatable means mounted between the bottom portions of said support members where the rotatable means are located in the lower regions of the electrolyte in said tank,.and a second series of horizontally spaced rotatable means mounted between the upper portions of said support members above and between said first series of rotatable means, said support members having portions extending outside said tank; support means outside said tank supporting said portions of said support members extending outside said tank; a pair of rotatable means above the level of and at opposite ends of said tank and extending generally .parallel to said first and second series of rotatable means and adjustably supported on said last mentioned support means for vertical movement relative thereto and to said first and second series of rotatable means; and said endless conductive conveyor passing beneath said first series of rotatable means and around the tops of said second series of rotatable means and said pair of rotatable means to form a steeply undulating conveyor path in the electrolyte.

References Cited UNITED STATES PATENTS Rabezzana 204204 Jording 204297 XR Smith 20428 Yeager 204202 Tuttle 204297 XR Kronsbein 204202 10 Altenpohl 20428 Chapman et a1 20428 Lockwood 20428 Lloyd 20428 FOREIGN PATENTS Germany.

JOHN H. MACK, Primary Examiner.

0 W. VAN SISE, Assistant Examiner.

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