US2754485A - Contact roll for electrolytic tin lines - Google Patents

Description

y 10 1 6 R. M. WlCK ET AL 2,754,485

CONTACT ROLL. FOR ELECTROLYTIC TIN LINES Filed Dec. 25, 1949 7 Sheets-Sheet 1 HIH w I c 1, N

July 10, 1956 R w AL 2,754,485

CONTACT ROLL. FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7 Sheets-Sheet 2 AZZOI'M July 10, 1956 R. M. WICK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7 Sheets-Sheet 3 g s E Q 0 w w S\ u] f 5 I13". 51. A p Q N a Herbert EIZI'WZ'JLU.

Aliornqy y 0, 1956 R. M. WlCK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7 Sheets-Sheet 4 III III Ill! Illllll lnvfe ziors J M W121 Herfierlfi fiancisco.

15 $14. flag/g Attorney y 10, 1956 R. M. WlCK w AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7 Sheets-Sheet 5 Herb 61% E fialzalls''o.

July 10, 1956 R. M. WICK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7 Sheets-Sheet 6 R Inventors mzilm-d M Wm];

Herberi E lTralzczlsz'a y 0, 1956 R. M. WICK ET AL CONTACT ROLL FOR ELECTROLYTIC TIN LINES 7 Sheets-Sheet 7 Filed Dec. 23, 1949 NS Wm \m MN lluzmlors N Herfiert H. EQIZL'Z25'60.

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CONTACT RoLr. FOR nrsncrnorrrrc rrN LINES Application December 23, 1949, Serial No. 134,722

3 Claims. (Ci. 339--) This invention relates in general to electrolytic apparatus, and more particularly to a high-current contact roll and collector head assembly for continuously electroplating metal strip.

The modern continuous electrolytic processes of plating steel strip with tin must necessarily operate at high speeds, and therefore at high current inputs, to be commercially practical. it is the function of the contact rolls to introduce ethciently the electric current into the strip that is being electroplated. Each increase in speed will obviously shorten the plating period, and therefore require additional current, yet space and other considerations limit the number and size of contact rolls which can be profitably employed. It is therefore preferable to increase the current input to each contact roll, up to the point Where the current-carrying capacity of the strip, rather than that of the roll assembly, becomes the limiting factor.

With a current input of 60,000 amperes to an electrolytic tin line, for example, existing 12% diameter contact rolls have been required to handle about 2,500 amperes each. The electrical demand for carrying even this load was not adequately met by the cross-section of the conductor elements used in the roll assembly, especialiy the shaft serving the dual function of support and electrical conductor, and excessive heating was the result.

A short brush life was also found to be characteristic f the conventional collector assemblies. This was true even when the brushes were immersed in oil for more effective cooling. The need for frequent brush adjustments and replacements, therefore, made the time and cost required for maintenance extremely high. With oil immersion there results an excessive voltage drop at the brush contact surface.

From a mechanical standpoint, the usual roll bodies made of heavy walled pipe were always considerably. out of balance, resulting in substantial drag and power waste and undue vibration even at very low speeds. The use of concentric forged cylinders for the rolls reduces vibration to a minimum, and has also produced a 25% decrease (spot reading) in the power required to pull the strip through the plating unit.

The present improved contactor roll and collector assembly of the same size, however, will handle in excess of 5,000 amperes without undue heating or any of these undesired conditions. Maintenance expense is reduced very substantially, largely because the brush life is much longer, being increased to several years. Since a set of brushes for a plating line is costly the value of this improvement is apparent.

One object of this invention, therefore, is to produce a contact roll assembly for electroplating strip which is characterized by very high current carrying capacity and practically uniform voltage distribution across the strip.

Another object is a balanced roll assembly which is substantially free from mechanical drag and vibration, and having extremely low maintenance costs.

Another object is a contact roll assembly with integral end closure plates and arbor of steel, and with an inner conductive spindle and flange of copper.

Another object is a contact roll assembly provided with an externally spirally grooved collector ring and air cooled brushes, and protected against the effects of corrosive platin g atmospheres.

Still another object is a compact collector assembly which is completely interchangeable, easily removable, and exceptionally well insulated electrically, with a well protected and accessible bus-bar connection and a ganged brush holder assembly affording improved conduction to the collector ring.

Other and further objects, purposes and advantages of this invention will appear in the following detailed description, in the attached seven (7) sheets of drawings, and in the appended claims.

in the drawings: Fig. l is a transverse vertical section of the collector assembly, taken on the line 1-1 of Fig. 2, with the current introducing end of the contact roll shown in broken section;

Fig. 2 is a vertical section on the line 22 of Fig. 1;

Fig. 3 is a side elevation of the contact roll, but with brushes and collector assembly omitted;

Fig. 4 is a detail view showing the mounting of one of the brush holder support studs;

Fig. 5 is a detail view showing the attachment of one of the enclosure fastening rods;

Fig. 6 is a detail view of one of the support studs with brush holder and brush;

Fig. 7 is a vertical section taken on the line 7--7 of Fig. 1;

Fig. 8 is a vertical section on the line 8-8 of Fig.7;

Fig. 9 is a rear view of a modification of the collector assembly from which the protective cover has been removed;

Fig. 10 is a side elevation of the collector assembly shown in Fig. 9 but having the cover in place;

Fig. ll is an enlarged detail view of a ganged brush holder unit;

Fig. 12 is a vertical section taken substantially on the line l2-l2 of Fig. ll;

13 is a horizontal section on the line 1313 of Fig. 12; and

Fig. 14 is a detail view of the flexible ventilator hose connection.

Referring particularly to Figs. 1 and 3, the shell 1 of the contact roll is a hollow cylindrical forging, preferably of steel, and machined inside and out for exact balance. A roll shell 1 /2" thick and 12%" in outside diameter is sufiicient to carry the 5000 ampere current and produc a voltage drop of less than .020 volt from the near to the far side of a 30" Wide strip contacting the roll. With the usual 18 distance between the point of tangency of strip and roll and the point of introduction of the strip into the solution, this means in practice a substantially uniform voltage across the strip by virtue of equalizing currents within that distance. At each end the shell 1 is beveled as at 2 and interiorly recessed as at 3 to provide a press fit with the integral closure plates and arbors 4 and 5 which are also machined for proper balance and welded thereto as shown. As shown in Fig. 3, the combined closure plate and arbor 4 consists of a single steel forging, the roll closure portion comprising a thick inner disc 6 and a beveled collar portion 7 of the same outer diameter as the shell 1, and the arbor portion 8 being reduced and extended to form a bearing journal 9 and an end portion 14 with a slotted keyway 11. The combined closure plate and arbor 5 is likewise an integral forging, with an inner disc closure portion 12 and beveled collar portion 13, and with an arbor portion 14 having a bearing journal 15 and a reduced intermediate portion 16 and a further reduced end portion 17 and keyway 18.

of the collector assembly The arborportion 14 is, however, larger in outside diameter thanthe corresponding arbor portion 8 on the other end of the roll, since it is centrally bored on its longitudinal axis as at 19 (Fig. 1) to permit the introduction of a solid electrolytic copper cylindrical spindle 20 provided on its outer end with a conical taper 21 and external threads 22. As the roll body is securely welded shut,'it is of the utmost importance that said current conductor spindle 24) be permanently attached. This attachment is accomplished, in part, through an annular copper conductor flange 23 Which is secured by the setbolts 24 and lock washers 25 to the inner closure disc 12. The bore 19 of the roll closure plate and the corresponding portion of the copper spindle 20 are mutually machined so as to afford a tight press fit within the closure discQlZ and flange 23. Besides improving the electrical contact, this method of attachment provides mechanical stability and lessens vibrational stresses that mightpossibly tend to loosen the connection between the spindle and the flange. The flange 23 is shrunk onto the .spindle end 26, which is important to give a mechanical and electrical connection thatis substantially integral and permanent. Following their assembly as indicated, the inner end of the spindle is peened over the flange as at {26,Qthus obtaining a further locking-in of the elements and adding to the permanence of the electrical contact.

Any suitable bearing such as the ball bearing 27, mounted on supports 28 on angles 29 forming the upper rim of the plating tank, may be used for substantially frictionless rotation of the journal 15. A similar hearing (not shown) is also required'for the journal 9 on the opposite end.

Referring further to Figs. 1 and 3, the peripherally slotted ring guard 30 is a pressed fit on the reduced intermediate portion 16 of the arbor 14. The tubular :copper collector head 31 is likewise a pressed fit on the reduced end portion 17 of said arbor and the conically tapered end section 21 of the inner copper spindle 20, being guarded against separate rotation by the key 32 in keyway'lS and by the washer 33 and nut 34 on the copper spindle threads 22 in the end recess 35 of the collector head 31. The inner threads 36 in said end recess 35 permit the use of a screwed-in pulling tool (not shown) to allow ready removal and replacement of the copper spindle 20.

The outer surface of said collector head 31 is provided with a plurality of continuous spiral grooves 37. Quintuple grooves of rectangular form about 0.0 deep and wide with a pitch and 1%" lead have been found to be particularly eflfective in providing an interruption of surface which extraordinarily prolongs the life of the contacting brushes.

'In the assembly shown in Figs. 1 to 8 inclusive, the current ,flow into the strip being electroplated is from the main bus bar (notshown) to the jumper bus 38 shown in Fig. 1 as attached by bolts 39 to the rectangular copper conductor plate 40 and the copper distributing ring 41. Referring now to Fig. 8, said distributing ring 41 is held tightly against the circular steel backing plate 42 and spaced from the upright support angle 43 by means of bolts 44 having insulating spacers 45, insulating collars 46 and outer insulating plates 47 of Synthane or .similar material. From the copper distributing ring 41 the current is introduced into six evenly spaced studs 48 thereon, each of which studs projects parallel to the axis of the conductor roll and is held in proper alignment by the cadmium-plated steel support ring'4 9. As shown in Fig. 4, each stud 48 is provided with a tapered end portion 50 secured to the copper ring 41 and the backing pl'ate 42 by the lock-washer 51 and nut 52, and istapped at its other end to receive the small bolt 53 holding it to the'support ring 49. Each stud 48 carries four brush-holders .54 in each of which a spring 55 presses abrush 56 against thesurface of the collector head While in 1 and 2 four brushholders 54 and four brushes 56, are shown on each stud 48,01 a total of twenty-four of each for the complete apparatus, their number is obviously not critical, and may be increased or decreased to correspond to the current demand. Brush-holders 54 are standard electrical equipment, being shown for example in the United States patent to Bassett, No. 930,337, issued August 10, 1909, and the accompanying 70% graphite-copper brushes are -also standard, hence require no further description. Current may even be fed into both ends of the roll, if desired, by simple duplication of the collector assemblies, but-the single ended arrangement shown will transmit all the current the strip itself will carry, and has the further advantage of much greater compactness than double ended designs.

The drum-like welded metal cover 57, which may optionally be provided with end and top sight windows 58 and 59 of Plexiglas or similar transparent plasticmaterial, is provided with a pair ofinner rod guides 60, through which as shown inFig. 5 afastening rod 61 terminally threaded as at 62 and having a Welded plate handle 63 and stop nut '64 holds the cover to the copper ring 41 and backing plate 42.

T his enclosed collector assembly is kept under positive air pressure through the bottom air inlet pipe-65, which is secured by welded plate 66 and rubber washer 67 as in Fig. 1. A clean air flow of the order of 50 cubic feet per minute has been found normally suflicient for all cooling purposes. The low air demand is made possible by the favorable electrical characteristics, including the low brush contact voltage drop, by means of which the Waste heat generated is held to a low figure. This also provides assurance that the mechanism is well protected from the corrosive atmospheres characteristic of the environment around a production plating operation, since the air is vented through the space 68 between the ring guard 30 and the concentric and co-planar copper ring 41 and'back ing plate 42, in the direction of the plating tank and hence of the greatest concentration of corrosive fumes. The protection against dirt and corrosion thus afforded is a substantial contributing element to reduced maintenance costs.

The major factor in prolonging the life of the brushes 56, however, is the interrupted contact surface provided by the spiral grooves 37 on the collector head 31. In the absence of such grooving, with a collector head otherwise the same and with the same brushes, operations under normal loads resulted in such gross roughening of the collector surface as to preclude extended use. Upon the application of the grooving, the entire characteristic of mutual wear was altered. In a short time the collector ring surface became smoother until it was coated with a glaze, presumably of graphite. Likewise the brushes wore smooth. The voltage drop on passage of current between brush and collector surface was reduced to the very low value of .040 volt, which is substantially lower than the least loss obtained previously.

Chromium plating the roll surface, and silver plating all the fixed contacts between electrical current carrying members will improve operations generally. The surface of the collector head 31, however, should be left unplated. Upon tests of a silver plated collector head it was found that the silver soon coated the brushes, and when this occurred the contact was between silver and silver. The silver contactor surface then roughened up and was soon abraded off, becoming apparent as afinesilverdust.

In the modification shown in Figs. 9 to 14 inclusive, the roll elements remain the same, but the collector assembly is made more easily removable and interchangeable with other collector assemblies in a plating line, the brush holders arearranged in sub-assemblies of'ganged units; the b u s-bar connections are removed from the zone of splash and'spray close to the plating cell and.-made' more accessible;.and thesinsulating and ventilating arrangements are somewhat changed.

Referring particularly to Figs. 9 and 10, the modified collector assembly is mounted in alignment with the roll arbor 14 by means of the support brackets 68 and the angles 69 secured to the upper rim 29 of the plating tank at each side of the bearing 27. Elongated cross-slotted bolt-holes 70 in the angles 69, together with the bolts 71 and nuts 72, permit vertical and horizontal adjustments of said brackets relative to the angles 69, to compensate for different collector assemblies. When properly positioned the adjustment bolts 71 are tightened, and the mounting may even be made more rigid if desired by tack welding the angles 69 together.

The round steel backing plate 73 is provided with four evenly spaced peripheral mounting lugs 74, which may either be made integral or welded thereto in a jig for the uniformity of positioning required to assure perfectly interchangeable assemblies. Said lugs 74 are rigidly attached by means of the mounting bolts 75 and 76 and insulators 77 to the support brackets 68. Moisture proof insulating members which are designed to support substantial loads, such as the Keystone Type EE insulators, are preferable for this purpose.

Against the steel backing plate 73 is placed the heavy copper current distributing ring 78, which is provided with an outwardly and downwardly extending integral lip 79. Said lip 79 is attached by the bolts 80, washers 81 and nuts 82 to the laminated jumper bus-bar 83, thus permitting the connection to be made straight up from the main bus-bar (not shown), under the desirable conditions of more free working space and practically no spray contamination.

With reference to Figs. 11 to 13 inclusive, open terminal 84 on each brush lead or shunt 85 is firmly attached by means of a burred steel stud 86, nut 87 and washer 88 to the L-shaped copper bracket 89. Said bracket is shaped to cover only a portion of one brush-holder 54, leaving ample space for the full swing of the spring pressure arm 90. Each group of four brush-holders 54 with their respective shunt brackets 89, is mounted on a copper assembly tube 91, together with a large tapered contact bushing 92, and the ganged assembly is jig-aligned and brazed together as a unit. To assist replacements when necessary of springs 55 and pressure arms 90, a full length holder pin 93 is preferably used instead of individual holder pins, and is held in place by the rings 49 and 78. Each unit is maintained in correct alignment by a locating pin 94 mounted into the distributing ring 78 and backing plate 73 and engaging in a hole 95 in the first shunt bracket, and is supported by means of a /4" bolt 96 or the like extending through the steel support ring 49, end spacer 97, the center of assembly tube 91, and said distributing ring 78 and backing plate 73, terminating with a washer 98 and nut 99 at the rear side of the backing plate 73.

It will be noted that the radial positions of the brushholders 54 in Fig. 9 are modified somewhat from those in Fig. 2, primarily for added accessibility to the brush shunt connections. Lateral offsetting or staggering of alternate brush holder units, by inch for example, is also desirable and may be accomplished by using three sets of such units with A; inch long tapered bushings and inch end spacers, and three sets with A3 tapered bushings and inch spacers.

The cover 57 and its securing means are substantially as previously described. The air inlet connection, however, has been relocated to one side of the bus bar connection, and is made by means of a length of flexible ventilation hose 1'90 having a bayonet type connector 191 to the cover which permits ready removal, as shown in Fig. 14.

When it is desired to remove the cover 57, the endthreaded rods 61 are withdrawn, the flexible hose 100 is detached from the cover, and the hose may then be swung clear of the collector assembly to give more free working space. Removal and replacement of any brush holder unit at the line without interfering with the remaining five holders or the outer support ring 49, may be done by removing the center bolt 96 and the end spacer 97 and pulling the unit toward the support ring 49 until it is disengaged from its socket 102 in the distributing ring 78 and the locating pin 94, when it can be raised free of the collector assembly and a replacement unit re-installed by reversing the procedure. The entire assembly can be disconnected from the line by removing the four mounting bolts 75' from the insulators 77 and the three bus-bar attaching bolts 80, and a substitute assembly aligned and re-connected. It is thus possible to make repairs or replacements with a minimum of disassembly of contacts or joints.

To summarize the functional aspects of this invention, it is to be noted that all the mechanical and electrical requirements have been met so as to achieve substantially vibrationless operation, very nominal bending, adequate strength and rigidity, low voltage losses in collecting and transmitting the current, and remarkably long brush life and freedom from maintenance at very high currents and high strip speeds.

Although we have hereinabove shown and described this invention in considerable detail, we do not wish to be limited to the exact and specific details of the construction so shown and described, but we may also use such substitutions, modifications, or equivalents thereof as are embraced within the scope and spirit of the invention, or as are pointed out in the appended claims.

We claim:

1. A collector device for supplying current to a horizontally disposed plating roll having an outwardly extending contact portion, comprising a pair of upright support brackets adjustably mounted adjacent said contact portion, a plurality of insulating members mounted on said support brackets, a backing plate removably secured to said insulating members, a distributing ring thereagainst concentric with said roll contact portion and having an extended portion adapted for connection to current source, an outer support ring in axially spaced parallel relation to the distributing ring, and a plurality of radially arranged ganged brush units interposed between and supported by said distributing and outer support rings.

2. in the combination described in claim 1, each ganged brush unit comprising an assembly tube; a contact bushing and a plurality of alternately disposed brush-holders and shunt brackets on said tube and made integral therewith as by brazing; brushes in said brush-holders with their shunts connected to the shunt brackets; an end spacer aligned with the assembly tube; a bolt extending through the outer support ring, the end spacer, the assembly tube, the distribution ring and the backing plate, and holding them in unitary relationship; and a locating pin mounted in the distributing ring and backing plate and engaging in a hole in the first shunt bracket.

3. A collector device for supplying current to a plating roll having an extended contact portion, comprising a backing plate, a current distributing ring thereagainst concentric with the contact portion and having a plurality of radially s aced tapered sockets, an outer support ring in axially spaced relation to the current distributing ring and having a plurality of bolt holes in alignment with the sockets, and a plurality of brush units interposed between said spaced rings, each brush unit comprising a conductive assembly tube; a tapered socket-engaging contact bushing and a plurality of alternately disposed brushholders and shunt brackets mounted on said tube and brazed thereto as a unit; a single spring holder rod extending through said brush-holders; brushes in said brushholders having their shunts individually connected to said brackets; an end spacer aligned with said tube; and a bolt extending through a bolt-hole in the outer support ring,

References Cited in the file ofthis patent Watson Dec. 16, 1941 UNITED STATES PATENTS Apple Feb. 2, 1915 Hobart "Feb. 24, 19 31 Hague et al Feb.,1, 1938 10 .Hague et al Oct. 25, 1938 .18 Hollander m Ian. 16, 1 943 Mu'ddiman-et a1 A pr.'2 0, 1943 'Na'chtman AIgg..10,1 9. 4 8 'Sprague Aug. 10,1948 Powers 'July 4, 1950 'Winterhalter Oct. 17, f 1950 Cooper-et a1 Nov. 20, 1951 FOREIGN PATENTS Germany Feb. 11, 1909

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