Note: Descriptions are shown in the official language in which they were submitted.
1049~5S
SP~3CIFICATION
The present invention relates to the field of electro-
plating or electrodepositing. In one of its aspects the invention
relates to electroplating the surface of an electrically conduc-
tive strip or web of material. In another of its aspects the in-
vention relates to the use of an electroplating drum or roll in an
electroplating operation. In one of its concepts the invention
relates to electroplating a surface of a strip of electrically
conductive material passed around an electroplating roll with the
strip of material in contact with the roll submerged in an elec-
trolytic solution during the period of electroplating.
In the electroplating of a strip or web of material itis common practice to pass the strip of material around an elec-
troplating roll so that there is contact between one surface of
the strip and an electrically conductive circumferential ring on
the surface of the cylindrical roll. The electroplating roll is
submerged in a bath of electrolyte to a depth, usually to the
center of the circular end plane of the cylinder, that assures
maximum contact between the surface of the strip and electrolyte
on one side of the strip while contact is maintained between the ;;
electroplating roll and the opposite side of the strip. During
the plating cycle the cylindrical roll is rotated moving the
strip around the roll as electrical current is passed from an in-
soluble anode in the electrolytic bath through the electrolytic
bath and the strip to the electrically conductive circumferential
ring on the roll, thereby causing deposition from the electrolyte
onto the surface of the strip exposed to the electrolyte.
,One of the major problems associated with the operation
of a continuous coating roll as described above is that arcing
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1049~55
occurs between the strip and the conductor ring of the coating roll
at the point of first contact. In continuous plating operations
the circumferential conducting ring on the electroplating roll is
maintained at a constant voltage which it is believed causes a
preferential flow of current at the first area of contact between
the strip and the conductor roll. This can establish a transfer
of current called "line" contact in which all of the current is
transferred within the small area which is the width of the ini-
tial line of contact times its length. At the high current flows
required in electroplating operations, intense arcing takes place
along this line of contact. The arcing is of sufficient intensity
to burn this strip. The degree of arcing is intensified when ini-
tial contact between the strip and the circumferential conductor
occurs above the surface of the electrolytic bath.
It is therefore an object of this invention to provide a
method for electroplating a strip or web of electrically conduc-
tive material by which arcing of the strip and consequent burning
of the strip can be made negligible.
It is a further object of this invention to provide a
method for electroplating a strip of material in which the initial
application of an electroplating current to the strip can be con-
trolled to take place along a line beneath the surface of the
electrolytic bath as the strip is moved in contact with an elec-
troplating roll through an electroplating bath.
It is another object of this invention to provide an
electroplating apparatus in which the electroplating current -~
passed from the anode through the electrolyte to the conductive
electroplating roll can be varied as the submerged portion of the
conductive roll surface is rotated in the electrolyte bath.
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1049955
It ~s st~ll anothex object of this invention to
provide an electroplatin~ conductive roll comprising a plur-
alit~ of electrically conductive mem~ers, ~lectricall~ in-
sulated from one another extending in the direction of the
axis of rotation of t~e roll and to form a segmented cir-
cumferential ring of electrical conductors around the
cylindrical surface of the roll.
Accordingly there is provided in accordance with
the present invention a method of electroplating comprising
(a~ passing a strip of conductive material around an
electroplating contact roll, which has only a portion of its
peripheral surface area submerged in electrolyte
(b) positioning an anode in the electrolyte contiguous
to but spaced from the strip on the contact roll
(c~ setting up an electric potential between the anode
and the contact roll, and
(d) confining the flow of electroplating current to a
path between the anode and an area of the strip which is in
contact with a portion only of the submerged surface of the
2a contact roll.
There is also provided in accordance with the
present invention an electroplating apparatus comprising
ta) container means
(b) an electroplating cylindrical roll journalled for
rotation and positioned so as to ~e partially submerged in
an electrolyte contained in said container means, said roll
having a plurality of electrically conductive longitudinally
extending elements on the outer peripheral surface thereof
spaced apart from one another circumferentially around said
3Q roll and electrically insulated from one another '!
(c~ an anode structure located in the container and
having arcuate surface portions extending longitudinally
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10~9955
along the lo~e~ surface portion of the electroplating roll
and spaced therefrom , and
~ d~ means for delivering electrical current selectively
to different ones of said conductive elements during rota-
tion of the electroplating roll.
The invention is illustrated by way of example
with reference to the accompanying drawings wherein:
Figure 1 is a perspective view of an electroplating
apparatus incorporating the present invention;
Figure 2 is a schematic view in section taken on
the line 2~2 of Figure l;
Figure 3 is a schematic view in section taken on
the line 3-3 of Figure l;
Figure 4 is a schematic representation of an
apparatus of Figures 3 and 4 showing a split commutator
brush joined electrically to a split anode;
Figure 5 is a schematic representation of electro-
plating apparatus in accordance with this invention arranged
in series so that both sides of the strip can be plated in
continuous operation, and
Figure 6 lS a perspective view of a preferred em-
bodiment of the electroplating roll structure shown schemati-
cally in the preceding figures.
Referring now to Figure 1 for the general arrange-
ment of an apparatus of the invention, it can be seen that
an electrically conductive strip 1 is passed across a
directing roll 3 ana thence around a conductive electro-
plating roll indicated generally at 5
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lO~99SS
partially submerged in an electrolytic solution 9 in a bath tank 7
for containing the electrolyte solution, and thence around second
directing roll 11. The directing rolls 3, 11 are aligned with the
electroplating conductive roll 5 so that the strip 1 is maintained
against the circumferential surface of the conductive electroplat-
ing roll 5 rotating in a clockwise direction.
The electrolyte solution 9 is in contact with the side
10 of the strip 1 that is away from the conductive electroplating
roll.
Contained within the electrolytic bath 9 in a position
sufficiently removed from strip 1 to prevent direct contact with
the strip 1 passing around the electroplating roll 5 is an insol-
uble anode 13. In general application, this anode means will have
a configuration that conforms to the surface contours of the elec-
troplating roll 5 so that the anode means can be described gener-
ally as a hollow cylindrical shape with diameter sufficiently
larger than the electroplating roll 5 to accommodate the electro-
plating roll and the strip being plated within its cylindrical arc
without direct contact between the surface of the anode and the
near adjacent surface of the strip. The electrolyte solution 9
within the bath tank 7 is in contact with the surface of the anode
13 so that the passage of electrical current from the anode 13
through the electrolyte 9, through the strip 1 being treated, and
to the discontinuous conductive ring 16 formed by the electrically
conductive segments 15 of the electroplating roll will cause depo-
sition of metal from the electrolyte onto the surface of the strip
with which the electrolyte is in contact.
The electrically conductive roll designed for use in
this invention is schematically illustrated in Figure 1 as an
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10~9955
elongated cylinder compos~d of electrically conductive segmental
elements 15 spaced in side-by-side circum~erential arrangement to
form the major portion of the cylindrical surface of the roll and
insulated each from the other by electrically nonconductive mem-
bers 17 which join together to form a core carried by a shaft 18
(Fig. 2). Electrically conductive elements lS are inaividually
connected to a means by which the flow of current through each
member can be selectively controlled. In Figure 1 the connecting
means are shown as electrically conductive members 19 forming part
of a drive shaft indicated generally at 21. These conductive
members 19 are spaced each from the other and can be insulated
from one another by electrically nonconductive members 23 forming
part of the drive shaft 21. This shaft is connected in turn to a
commutator roll indicated generally at 25 which is also divided
into electrically conductive elements 27 insulated each from the
other by electrically nonconductive members 29 which join together
to form a core carried by a shaft 30 IFig. 3). Thus the electro-
plating roll 5, the connecting shaft 21 and the commutator roll 25
each contains electrically conductive elements spaced around a
cylindrical insulating core and electrically insulated each from
the other to form in the case of roll 5 and roll 25 a segmented
electrically conductive ring.
If desired insulation (not shown) may cover the electri-
cally conductive elements of connecting shaft 21. This shaft
passes through an electrolyte retainer 37 with either the shaft
rotating relative to the retainer or the retainer rotating rela-
tive to bath tank 7. The discontinuous commutator ring formed by
the electrically conductive elements 27 of the commutator roll 25
is connected through a brush member 33 into an electrical circuit
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1049955
34 including a source of electrical potential 35 and anode 13 in
the bath tank 7.
As can be seen, the electrical connection between brush
member 33 and the ~lectrically conductive ring of the commutator
is so arranged that only a predetermined number of the electri-
cally conductive members 27 are energized at any one time. As the
electroplating roll 5 is rotated by movement of strip l, shaft 21
causes commutator roll 25 to be rotated and electrically conduc-
tive elements 27 of the commutator roll 25 are energized and then
de-energized as the elements pass in contact with the brush of the
commutator. This causes current flow through the corresponding
electrically conductive elements l9 and 15 of the shaft and elec-
troplating roll, respectively.
Basic to the electroplating apparatus and method of this
invention is the segmented electroplating roll 5 as schematically
illustrated in Figure 1 and as described above. The provision of
the electrically conductive segmented ring at the roll surface
permits control, hitherto unknown in the art, of the area of elec-
trical contact between the strip being plated and the surface of
the electroplating roll.
As will be shown in the discussion of the method of
electroplating using the apparatus of the invention, the electro-
plating roll 5 can have its surface divided into any number of
electrically conductive elements 15 with four conductive members
being the minimum efficiently operating number. It can readily be
seen that the greater the number of conductive members, up to the
number where practicality is the limit, the greater the control
that can be exercised over the portion of the surface of the
roller through which electrical current is passed. For reasons of
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1049955
practicality, the number of conductive segments will generally be
between four and twelve.
Referring now to Figures 2 and 3 of the drawing, an
operation for electroplating one face of a strip by the process of
this invention can be described. As illustrated in Figure 2, the
strip of material 1 is passed around a portion of the circumferen-
tial face of electroplating roll 5. The electroplating roll as
shown in this view has its eight electrically conductive elements
identified separately as 15A through 15H for better elaborating on
the method of using the apparatus. Sirnilarly the drive shaft 21
has its eight electrically conductive elements separately identi-
fied as l9A through l9H. Each of the electrically conductive ele-
ments 19 of the drive shaft is aligned to connect with an electri-
cally conductive element 15 of the electroplating roll. Similarly
in Figure 3 the commutator roll 25 has its eight electrically con-
ductive elements separately identified as 27A through 27H, each
aligned with a conductive element 19 of the drive shaft so that in
Figures 2 and 3 electrically conductive elements 15A of the elec-
troplating roll, l9A of the drive shaft, and 27A of the commutator
roll form a continuous electrical conductor or conductive element.
Similarly, each of the elements marked B through H are connected
to form continuous electrical conductors comprising a conductive
element of the electroplating roll, a conductive element of the
drive shaft and a conductive element of the commutator roll.
As shown schematically in Figure 2, in operation, a
strip 1 is passed around the circumferential face of electroplat-
ing roll 5 so that the initial point of contact 6 between the roll
5 and the strip 1 can be in the neighborhood of but preferably at
or above the surface ~ of the electrolyte solution 9 contained in
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1049~5~
the electrolytic bath 7. Electrolyte 9 is supplied through con-
duit 45 and withdrawn through conduit 46 to maintain the level
within the bath and also to maintain the desired temperature
within the bath.
The commutator roll 25, the same drive shaft 21 and the
electroplating roll 5 rotate synchronously so that the electric
current can be caused to flow successively through electrically
conductive elements of the electroplating roll 5, the drive shaft
21 and the commutator roll 25. As can be seen in Figure 3 with
the commutator brush 33 positioned so that electrical contact is
established between electrically conductive elements 27G and 27H
and the correspondingly numbered electrically conductive elements ;
of shaft 21 and electroplating roll 15G and 15H, a clockwise rota-
tion of the roll will establish electrical contact between the
commutator brush and electrically conductive element 27A soon
after the corresponding electroplating electrically conductive
element 15A is submerged in the electrolyte 9. Electrical con-
tact is maintained with element 27G until the leading edge of cor-
G responding element 15G is just below the surface ~7 of the elec- ~-
trolyte 9 and before element 15G emerges from the surface ~ of
the electrolyte 9. By this arrangement electrical current can be
caused to flow through three elements at a time of the electro ~-
plating roll 5, e.g. 15G, 15H, 15A. Electrical flow is maintained
only in that portion of the commutator roll 25 that is connected
to the portion of the electroplating roll 5 that is submerged in
the electrolyte 9. Similarly, element 27B and each of the other
conductive commutator elements 27 is successively rotated into
contact with the brush member 33 as elements 27G, 27H and 27A are
lO~99SS
passed out of contact. No current flows to the electrically con-
ductive elements 15 of the electroplating roll 5 that are not sub-
~erged in the electrolyte 9. Line contact above the surface of
the electrolyte between the strip 1 being plated and an energized
portion of the electroplating roll 5 is avoided. Suitable adjust-
ment of the size of the area of contact between the commutator
roll 25 and the commutator brush 33 can be made to expand or limit
the area of electrical contact in which current will be passed
between the electroplating roll 5 and the strip 1 being plated.
Since the strip 1 is electrically conductive, some electric cur-
rent will flow along the length of the strip from each side of an
energized element 15. In view of the higher resistance of this
path the current flow will be minimal; however with a larger num-
ber of elements 15 and 27 in the rolls 5 and 25, the brush area
must be limited to prevent an energized element 15 from coming too
close to the electrolyte surface 38.
It is also within the scope of the invention to provide
a split commutator brush 33 or other control means by which the
flow of current can be increased and decreased through certain
conductive members of the electroplating process. This is illus-
trated in Figure 4 using a split commutator brush 33. As c~mmuta-
tor member 27A rotates clockwise into successive contact with mem-
bers 33A, 33B and 33C of the brush having each of these brush mem-
bers connected individually through controlled electrical sources
35A, 35B, 35C, to corresponding members of a split anode 13A, 13B
and 13C, current of differing intensities are passed through the
aligned members. The plating current can be made progressively
greater through each successive member of the brush 33A-33C or the
current of greatest intensity can be that applied as the strip is
10499S5
at the midpoint of travel through the plating bath tin electrical
connection with 33B). The sizing and spacing of the conducting
portions of the brush can also be advantageously varied causing
the current flow to fluctuate in any conductive element of the
roll 5 as contact between the commutator roll elements and any
conductive element of the brush is made or broken. Referring to
Figure 4, as the conductive elements move clockwise, there will be
an interval in which both 27H and 27A are in contact with 33A and
27H is also in contact with 33s. During this period the current
flow in 33A and 33B can be held equal but the current flow in 33B
can be sequenced by variable resistances 48 to increase as soon as
27H is no longer in contact with 33A. Similarly the current flow
in 33B can be decreased coincident with contact of 27H with 33C.
Referring to Figure 5, a two step system is illustrated
with a strip 1 being passed around two electroplating rolls 5, 5
of this invention in series so that both sides 10, ln of the strip
1 can be electroplated. The system illustrated involves the use
of two electroplating rolls 5, 5 as described above, so arranged
that a continuous strip 1 of material is passed around the elec-
troplating roll 5 and then a second roll 5 in series, with theelectroplating rolls 5, 5 operated to rotate in opposite direc-
tions. The illustrated counter rotation arrangement is most prac-
tically arranged with one electroplating bath 7 located above the
other with the electrically conductive web 1 passed around suit-
able intervening rolls 39, 41 which permit the spacing necessary
to cause the side 10 of strip 1 left unplated in passage around
roll 5 to be in contact with the electrolyte 9 in passage around
roll 5.
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104995S
Means for completing the electrical circuit through the
roll system can be made a part of a drive shaft as illustrated in
Figure 1. A preferred embodiment of the roll system of the pres-
ent invention is lllustrated in Figure 6 in which like elements
are numbered as in Figure 1 but primed. In Figure 6 the eleetri-
cally nonconductive drive shaft 21' is surrounded by rigid elec-
trically conductive rods 19' equal in number to the number of
eleetrically conductive segmental elements 15' of the eleetroplat-
ing roll 5'. Eaeh eonduetive rod 19' is attaehed at one end to
one conduetive element 15' of the eleetroplating roller 5' and
attaehed at the other end to one eleetrically conductive element
27' of the commutator roller 25'.
This eonfiguration requires a special sealing member 50
for sealing the drive shaft 21' and conductive rods 19' as they
pass through the end 36' wall of the electrolytic bath tank 7.
The seal ean be formed from a round disc 52 of electrieally non-
eonduetive material, inert to the eleetrolyte, whieh is suffi-
eiently greater in diameter than the distanee of the conduetive
rods 19' from the eenter of the drive shaft 21' so that the eon-
duetive rods 19' are insulated from eontaet with the electrolyticbath tank 7 and the material of the sealing member forms a liquid
tight seal with the conneeting rods 19' and shaft 21'. As shown,
the seal can be suitably grooved at 54 to maintain rotating, seal-
ing eontaet with the wall of the eleetrolytie bath tank 7 to pre-
vent flow of eleetrolyte 9 from bath tank 7. In such a eonfigura-
tion the seal can or need not be formed of a material of suffi-
eient strength to bear part of the weight of the electroplating
roll apparatus, bearings, not shown, being supplied for the shaft
21' in any ease. Sueh a sealing member is similar to that
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iO49955
required for passing the drive shaft 21 alone, as shown in Figure
1, through the wall of the electrolytic bath tank 7.
The roll system of the embodiment illustrated in Figure
6 is formed by taking a steel shaft 21' and mounting on it cylin-
drical insulating core members 17' and 29' which have channels
machined in them to receive electrical conductive segmental ele-
ments 15' and 27'. These electrically conductive elements are
firmly affixed in place in the channels by any suitable means with
their outer surfaces forming part of the overall cylindrical sur-
faces of roll 5' and commutator member 25'. Rreferably core mem-
ber 17' entirely encloses the inner sides of conductive e]ements
15' over that portion of the roll 5-5 which contacts the strip,
leaving exposed to the electrolyte bath only the cylindrical sur-
face of each conductive element in that portion of the roll sur-
face which contacts the strip, herein termed the effective portion
of the roll surface. Prior to assembly of the conductive elements
15' and 27' and insulating core members 17' and 29' into the roll
system, conductive rods 19' and nonconductive sealing disc 50 are
assembled on and around shaft 21'. The entire assemblage is then
brought together with conductive elements 15' and 27' snugly
receiving the ends of conductive rods 19' in electrically conduct-
ing relationship. In this manner, each conductive element 27',
associated rod 19' and associated conductive member 15' together
form a continuous electrically conductive structure for supplying
current for carrying out the desired plating operation.
It will be apparent that the structure illustrated in
Figures 1-3, like that of Figl~re 6, can be considered as having
two cores made up of nonconductive members 17 and 29 with their
- internal connecting structure carried by a shaft which extends
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1049955
between the cores and in the Figures 1-3 embodiment carries con-
necting electrically conductive members 19 and nonconductive mem-
bers 23.
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