US2312452A - Method and apparatus for continuously electroplating metallic strip - Google Patents

Description

March 2,' 1943. E. s. TAYLERSON 2,312,452

METHOD AND APPARATUS FOR CONTINUOUSLY ELEGTROPLATING METALLIC STRIP Filed April 28, 1939 3 Sheets-Sheet 1 [ya/621507: 5 14/4/97- 5 7Z/YLEE50/V,

March 2, 1943.

E. s. TAY'LERSON METHOD ANIS APPARATUS FOR CONTINUOUSLY ELECTROPLATING METALLIC STRIP Filed April 28, 1959 3 Sheets-Sheet 2 1760922102": 514 467. 5. 7ZYLEe6o/v,

March 1943- E. s. TAYLERSON 2,312,452-

METHOD AND APPARATUS, FOR CONTINUOUSLY ELECTROPLATING METALLIC STRIP Filed April 28, 1939 5 Sheets-Sheet s 5 14 4276. 72Y4E50A 8888 are overcome.

Patented Mar. 2, 1943 UNITED STATES PATENT OFFICE mnon- AND APPARATUS roa CONTINU- OUSLY nmc'raomrma METALLIC STRIP Ewart S. Taylerson, Pittsburgh, Pa asslgnor to I Carnegie-Illinois Steel Corporation, a corporation of New Jersey ApplioatioirApril 2:, 939, Serial No. 270,708

1 tallic strip, when it was desired to replace anodes;

it was necessary to suspend the plating operation, remove the metallic strip from the bath and substitute a fresh supply of anodes thereto.

Similarly, when changes were made in the width of the strip being processed, the necessary changes in the numberand/or arrangement of the anodes within the bath also required the suspension of the plating operation. Such suspension of the plating operation is undesirable since it is a source of lost time and consequently increases the plating costs.

Under the present invention such disadvant- An object or the present invention is to provide a method and apparatus for. continuously electroplating metallic strip wherein the introduction of a fresh an'ode automatically moves all the anodes on the supporting member so that the spent anode on the other. side of the supporting member is moved into position for ready removal from the plating tank without affecting the continuity of the plating operation.

Other objects and advantages will become apparentas the descriptionproceeds and reference is had to the accompanying drawings, in which: Figure 1 is a planviewoi the present invention;

Figure 2 is a sectional elevation on line II-1I of Figure 1; a I V Figure 3 is a sectional elevation on line III-III of Figure 2;

Figure 4 is, a sectional elevation on line IV-IV of Figure 2;

Figure 5 is a sectional elevation on .line V-V of Figure 2;

Figure 6 is a sectional elevation on line VI-VI of Figure 2; and.

Figure 7 is a sectional elevation. online VII-VII of Figure 2.

Figure 8 is a detailed illustration of the top I of the anode; and a Figure 9 is a detailed perspective view of one of the insulated spacers for the anodes.

- In the drawings, the numeral 2 represents a plating tank within which is vertically positioned and arranged a plurality of anodes 8 supported by anode bridges I. These anode bridges extend across the top of the tank and are slidably mounted on blocks 5 rigidly secured to supporting beam members 8, and are electrically insulated therefrom by suitable non-conducting material I.

The anode supporting bridges t are of identical construction, and for the purposes of illustration,

a single bridge will be described in detail. Each bridge comprises a main body member 8 havin secured thereto a conductor plate 8, which conductor plate is connected by suitable leads'(not shown) to the positive pole of the plating gen- I erator (not shown). The conductor plates 8 are insulated from the end portions of the main body member 8 by suitable insulating material l8. The center portion of the main body member 8 is i the current supply is transmitted from the conductor plates 9 to the anodes supported on-said' face plate IS. The race plates I are or the same cross section as the plate I! and are secured to the main body member 8 on each side of the said plate 15. r

plate I! so as to provide an air gap therebetween. Direct electrical contact between the main body member 8 and the face plates It is prevented by the insulating material 18 which, in combination. with the air gap between plates l4 and I5, provides a neutral area at the ends of the anode supporting bridge 4 from which anodes can be suspended and maintained electrically neutral within the tank.

On the upper surface and on each endof the anode bridge 4 is a movable rack l8 engaged by a pinion ll Journalled on a shaft l8 by fixed brackets which is provided with a ratchet or'handler construction I 8 of conventional design. The mov- 55 able rack It at the entry end A of the bridge is The plates it are spaced from each end of l4 and.l5.

provided with a blunt nose :0, while the movable rack at the withdrawal end B of the bridge is hook-like portion 22 by means of'which they may 5 be hung on the bridge 4 from the face plates bridge, their weight, however, is sufllcient .to cause their positive contact with said face plates.

By reason of this slidable mountingmall the anodes on'the bridge can be moved as a group by pushing on the end or outside members of-the group. This permits a fresh anode to be introduced into the bath and moved on the bridge into the active plating area when needed and, in

so doing, causes a mass movement of all of the anodes on the bridge thereby resulting in movement of the spent anode on the opposite end of the bridge into a position where it can bev readily of a fresh anode does not interfere-with the con-- tinuity of the plating operation.

Such mass movement of the anodes requires continuity of contact of all the anodes on the The anodes are not fastened to the tical conditions, thus maintaining removed from the tank. Thus, the"introductionq uniformr ward the withdrawal end a of the anode bridge and results in a tendency toward a streaky coating. The streaky condition ismost prominent near that edge of the strip which is closest to the anode movement across'the tank is opposite in each adjacent plating pass. In this manner, the position of the withdrawal side B of the anode bridge with relation to a given edge and-side of the strip is reversed, and therefore, both halves of a given side of the strip will, in two or any even number of plating passes, be subjected to identhe coating Where rather longanodes are-used, there is a tendency foithe current. density to; decrease along the length and towards the bottom of the anodes. This condition is prevented by inclining bridge. sin ce it is seldom necessary to'complete the anodes so that their lower ends are nearer ly'flll, the ,anode bridge 4 with anodes, spacer blocks 24 are inserted between the anodes.

The size of the spacer block depends on the number of anodes and width of strip to be processed.

the strip. Theresistance tb current flow through the solution between the anodes and strip cathode is thus progressively decreased along the length of the anodes. To obtain the desired in- It/ will be noted that the anode supporting clination tapered wood cross pieces 23 are faswider than necessary to accommodate the maximum width of strip capable of being plated in 1 the tank. Such a construction provides a storage tened in the tank near the bottom of the anodes. Theanodes supported by any given bridge 4 rest against a cross piece 23 and-as the face of this ,cross piece is closer to the strip than are the space at both sides of the tank. -The spaces are face plates of the cooperating bridge, the anodes used for the introduction of new. anodes and the withdrawal of spent anodes.

While these storage spaces must be of suflicient size to hold one canode each, they may, if desired, be made larger.

hanging from the bridge are forced to incline at a small angle. The cross piece 23 is tapered in order that its face will be in a vertical plane approximately parallel to that of the face plate Inasmuch as the uniformity of the tin coating 40 of the cooperating bridge.

is known to be critically dependent on the position of the anodes with respect to the steel strip cathode, it is apparent that only those anodes which are properly located should besmade conplished since the face plates. I4 are positioned immediately above the storage spaces and said plates l4 are electrically insulated from the other members of the bridge 4 as hereinbefore described, thus the extra- -anodes, although supported by the bridge, are-notin electrical con tact with it. a

As previously stated, fresh anodes are putin on one side, gradually movedacross the tank and v removed at the other side. As a result, the thickness of the anodes on the bridge 4 becomes progressively less from the entry end A to the withdrawal end Bv of the bridge due to the various degrees of electrolytic dissolution the anodes have m been-subjected to. In order that this decrease in thickness will not affect the anode to cathode spacing across the tank and thereby result in a variation in' weight of coating from edge to edge of the strip, the withdrawal end B of the bridge 4 is moved closer to the strip than the entry end I}. fI'his' adjustment" of the ends ofthe anode... bridge withj'respect to the I strip is made possible :by, the *slidahle" inountin'g :of thefbridge oin the blocks 5: This adjustment maintains a uniform 7 distance betweencathode and anodefa cesfi In operation, the continuous metallic strip S passes from aconductor roll (not-shown) into the plating tank and downwardly through the first plating pass, aroundya sink roll 26 and upductive; in other words, the anodes in'the storage 45 wardly through the second plating pass. .Posispaces must be made inactive. This is accomtioned on each side of the strip in each of the plating passes are groups of anodes of the coating metal each of which is slidably supported on an anode bridge 4. The anode bridges are shown' anged so that the entry ends of those bridges arr supporting the anodes cooperating with a given side of the strip are on opposite sides of the tank. For example, fresh anodes are supplied to the group of anodes cooperating with the side S in the first or downward plating pass from the left side of the tank, while in the second or upward plating pass, fresh anodes are supplied to the group cooperating with the side S in this pass from the right side of the tank. Similarly, with respect to the side S of the strip, fresh anodes are shown as entering on the right side of the tank in the first plating pass and on the left side in the second plating pass. In this manner, the coating from edge to edge of the strip will be maintained uniform.

When it becomes necessary to supply'a fresh anode to the active plating area, themovable rack 'on' the' entry side -is operated, "forcing th'e fresh anode along the insulated portion of 'the' bridge and out into" the' active plating area and "i n so doing, allof the anodes on said bridge are inoved toward the withdrawal endfi The spentror-end anode of said group is moved to a position on the bridge where it canbecontacted by advancing the rack on the withdrawal end of said bridge' so that the pawl 2| can engage the slot 25 which is. cast in the top of the anode for that purpose.

Retracting the rack pull the spent anode into the insulated portion of the bridge where it can be readily removed from the tank.

The introduction of fresh anodes to the plating tanks is intermittent and periodical. The periods of introduction may be determined in advance, so that the spent anode removed upon the insertion of a fresh anode at the opposite (entry), side of the bridge will have been in service for the maximum time favorable to good plating results.

While I have shown and described a specific embodiment of the present invention, it will be seen that I do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of the invention, as defined by the following claims.

I claim:

1. In the continuous electroplating of metallic strip, the method which includes supporting a series of aligned flat-faced soluble anodes with their fiat faces in adjacent parallelism with a side of the strip, progressively moving said series of anodes across and in a path inclined toward the strip, the progressive movement and inclined path aforesaid coacting to maintain substantially uniform spacing between the strip and the eries of anodes as the erosion of the latter progresses,

means for moving said anodes in the direction of their decreasing cross section transversely of and toward the strip to compensate for erosion of the anodes whereby the substantially uniform spacing aforesaid is maintained.

4. In apparatus for continuously electroplating metallic strip, a series of anodes supported transversely of the strip and substantially uniformly spaced from one side of the latter, said anodes progressively varying in cross section from a maximum adjacent one edge of the strip to a minimum adjacent the other edge thereof,

successively removing worn anodes at one end of said series, and introducing fresh anodes at the other end of said series.

2. In the continuous electroplating of metallic strip, the method which includes supporting a series of aligned flatfaced soluble anodes with their flat faces in adjacent parallelism with a side of the strip, supporting a second series of aligned fiat-faced soluble anodes with their fiat faces in adjacent parallelism with the same side of the strip in spaced relation to' said first series along said strip, progressively moving each series of anodes across and in a path inclined toward the strip, the progressive movements and inclined paths aforesaid coacting to maintain substantially uniform spacing between the strip and the two series of anodes as the eros ,n of

the latter progresses, the inclined paths", y'the two series extending toward opposite edges of the strip, successively removing worn -anodes at one end of each of said series, and introducing fresh anodes at the other end of each of said series.

3. In apparatus for continuously electroplating metallic strip, a series of anodes supportedtransversely-of the strip and substantially uniformly spaced from a side of the latter, said anodes progressively varying in cross section from a maximum adjacent one edge of the strip to a minimum adjacent the other edge thereof, and

a second series of anodes supported transversely of the strip and substantially uniformly spaced from the same side of the latter, said second series being spacedalong the strip from said first series of anodes, the anodes of said second series progressively varying in cross section in the same manner but opposite direction to those of said first-named series, and means for moving the anodes of each series in the direction of their decreasing cross section transversely of and toward the strip to compensate for erosion of the anodes whereby the substantially uniform spacing aforesaid is maintained.

5, In apparatus for continuously electroplating metallic str p, means for conveying the strip through a plurality of passes in an electrolyte, plural series of soluble anodes supported transversely of the strip and substantially uniformly spaced from the faces of the strip at each of said passes, the anodes of said series adjacent the same face of the strip in successive passes varying in cross section across said face from maximum to minimum in opposite directions, thereby compensating for decreasing width and variable spacing between the anodes of any of said series, and means for moving the anodes of each series in the direction of their decreasing.

cross section transversely of the strip.-

6. In apparatus for continuously electroplat- I aforesaid, and means adjacent the lower ends of said anodes inclining the lower ends thereof toward the strip during the said movement of the anodes, thereby maintaining substantially uniform current density throughout the length thereof.

EWAR'I S. TAYLERSQN.

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