U.S. patent number 3,849,284 [Application Number 05/375,458] was granted by the patent office on 1974-11-19 for apparatus method and valve for electrodepositing a coating on interior surfaces of container bodies.
This patent grant is currently assigned to American Can Company. Invention is credited to Hans Kossmann.
United States Patent |
3,849,284 |
Kossmann |
November 19, 1974 |
APPARATUS METHOD AND VALVE FOR ELECTRODEPOSITING A COATING ON
INTERIOR SURFACES OF CONTAINER BODIES
Abstract
An electrocoating system comprises an apparatus, method and
valve for electrodepositing a coating on interior
electrically-conductive surface areas of container bodies.
Container bodies having an open end are timely fed onto
circumferentially aligned rows of valves on the exterior of a
rotating cylindrical drum containing an electrolytic fluid.
Continuous anodic cables extend around the drum, exert axial
pressure on the bottoms of the containers, render them anodic,
sealingly engage their rims on the valves and thereby open the
valves to gravity-feed the fluid into the bodies. With fluid
therein, current passed through cathodic electrodes projecting from
the valve exteriors into the bodies, electrodeposits a coating on
the electrically-conductive surface areas of the container bodies.
During continued drum rotation, fluid gravity-drains from the
coated bodies back into the drum, and the empty, coated bodies are
discharged from the system. The fluid valve has a fixed exterior
and a moveable interior housing. A valve member connected to the
exterior housing has an insulated conductive core to which a spring
electrode is connected thereto exterior of the valve member. The
interior housing is axially moveable against a spring bias to open
a passageway in the valve. All parts of the valve are
non-conductive in relation to the fluid.
Inventors: |
Kossmann; Hans (Barrington,
IL) |
Assignee: |
American Can Company
(Greenwich, CT)
|
Family
ID: |
26963301 |
Appl.
No.: |
05/375,458 |
Filed: |
July 2, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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285643 |
Sep 1, 1972 |
|
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Current U.S.
Class: |
204/625 |
Current CPC
Class: |
C25D
13/14 (20130101); B65G 49/0413 (20130101) |
Current International
Class: |
C25D
13/14 (20060101); C25D 13/12 (20060101); B65G
49/04 (20060101); B65G 49/00 (20060101); C23b
013/00 (); C23b 005/68 () |
Field of
Search: |
;204/300,299,275,181,222
;137/535,542 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mack; John H.
Assistant Examiner: Prescott; A. C.
Attorney, Agent or Firm: Aubet; Robert P. Auder; Paul R.
Ziehmer; George P.
Parent Case Text
This is a divisional of application Ser. No. 285,643, filed Sept.
1, 1972.
Claims
I claim:
1. A fluid valve for electrodepositing systems wherein an
electrolytic fluid and electric current insulatedly pass through
the valve, which comprises:
a fixed exterior housing mountable on a wall of a reservoir
containing the fluid, the exterior housing having a back wall with
apertures therein communicating with the interior of the
reservoir,
a moveable interior housing, interior of and slidingly engaged with
the exterior housing, the interior wall of the interior housing
defining a central valve chamber having
a mouth opposite the back wall,
a resilient sealing ring mounted in the mouth,
a valve member fixedly connected at one of its ends to the back
wall, extending axially into the chamber and having legs fixed to
and extending transverse to its axis, the axial portion of the
valve member having a conductive core connectable to circuitry,
an electrode connected to and projecting from the exterior of the
valve member,
means for sealing and preventing fluid from passing between the
housings, and
biasing means between the housings for flexibly biasing the sealing
ring of the interior housing in sealing engagement with the valve
member legs to seal the fluid valve chamber, the biasing means
being inwardly compressible toward the back wall by an axial force,
so that when the force is sufficient to compress the sealing ring
and biasing means, a passageway is created between the valve member
legs and the sealing ring which allows fluid to flow from the
reservoir to the exterior of the valve chamber.
2. The fluid valve of claim 1 wherein all parts of the valve means
excluding the electrode, exposable to the fluid, are non-conductive
in relation to the fluid.
3. The fluid valve of claim 2 wherein the biasing means is a
helical spring extending around and being abuttingly biased against
a support wall of, the interior housing.
4. The fluid valve of claim 3 wherein the biasing means also
includes a rigid backing ring adjacent the back wall of the
exterior housing for backing the spring.
5. The fluid valve of claim 4 wherein the fluid sealing and
preventing means includes an annular flexible resilient interior
sleeve partly within the chamber and sealingly fastened to the
interior of the interior housing and the exterior of the exterior
housing to prevent fluid from passing therebetween.
6. The fluid valve of claim 5 wherein the interior housing has a
continuous annular groove therein and the interior sleeve is
sealingly engaged to the interior housing by means of at least one
lock washer which peripherally forces an adjacent portion of the
sleeve into the interior housing groove.
7. The fluid valve of claim 6 wherein the fluid sealing and
preventing means includes an annular flexible resilient exterior
sleeve sealingly fastened to and for sealing the exteriors of the
interior and exterior housings, exterior of the reservoir wall.
8. The fluid valve of claim 7 wherein the electrode is a helical
spring, the biasing means also includes a rigid lock washer mounted
between the backing ring and the spring for backing the spring and
acting as a stop against outward movement of the interior housing,
and the fluid sealing and preventing means also includes an annular
elastomeric O-ring between the back wall and an interior sleeve
portion that is adjacent the backing ring.
Description
BACKGROUND OF THE INVENTION
This invention relates to the field of electrocoating metal
substrates. More particularly, the invention relates to an
electrocoating system including apparatus, method and valve for
electrodepositing a coating on interior electrically-conductive
surface areas of metal container bodies.
Basically, electrocoating is the electrodeposition of organic
resinous coating materials on electrically-conductive surface
areas, from polyelectrolytic electrocoating material mediums which
can be anodic or cathodic aqueous or nonaqueous base bath
solutions, suspensions or dispersions. The electrocoating mediums
ultimately contain coating ions or polyelectrolytic particles,
which, in the case of anodic mediums, carry a negative charge in
the bath and when a voltage is applied and current is induced to
flow through the medium, migrate to and discharge onto any
positively charged surface of a metal substrate, i.e., the anode,
which may in contact with the medium. Conversely, the
polyelectrolytic particles, in the case of cathodic mediums, carry
a positive charge in the medium, and, upon application of a
voltage, migrate to and discharge onto any negatively charged
surface of a metal substrate, i.e. the cathode, which may be in
contact with the medium.
A layer of particulate coating material is electrodeposited
adjacent the electrically charged metal substrate as the direct
current flows between it and an oppositely electrically charged
electrode such as a wire or rod, immersed in the coating bath. The
process is driven by an electrical potential which can be in the
range of from 1 up to 500 volts, but more typically is from about
50 to 500 volts. The electrodeposition of the coating material
takes place only at electrically-conductive surface areas of the
metal object because only at such areas is there an electrical
circuit and the electrical action which allows the flow of direct
current needed to cause the polyelectrolytic particles to be
electrodeposited adjacent the electrically-conductive surface.
The thickness of the layer of particulate material electrodeposited
is automatically regulated by the characteristically low electrical
conductivity of the particular mediums used. Once a certain layer
thickness of coating material has attached to the
electrically-conductive surface area of the metal substrate, the
electrodeposited coating material, in having a low electrical
conductivity characteristic, increasingly tends to insulate the
surface area from the coating bath in which it is immersed,
transforming it into a non-conductive surface, whereby direct
current flow therein greatly diminishes and eventually ceases, with
the resulting inhibition of further electrodesposition of coating
material.
One particular field where it has been found desirable to coat
metal substrates is in the manufacturing of metal containers or
cans, where it is necessary that all the exposed, uncoated surface
areas on the metal can be coated to protect the metal from
corrosion.
At present, there is no conventional, commercial apparatus or
method of quickly and efficiently electrocoating the interior
surfaces of metal can bodies such as used in the packaging of beer
or carbonated beverages. Presently, a typical method of perfecting
coverage of the coating on the interior of such surfaces to protect
them from environmental product attack, is to use a double coat
system which involves initially applying a base coat by a roller
onto the metal stock while it is in the flat, and, after
fabricating the can from the coated stock, spraying a top coat on
the interior of the fabricated can or component to seal any
scratches, breaks or discontinuities or other electrically porous
or conductive areas formed in the base coat during the fabrication
operation. The top coat usually is an overall coat since the
location of the discontinuities cannot precisely and reliably be
ascertained.
While this two coat system has in general been satisfactory, it
does have a number of disadvantages, especially in relation to the
overall top spray coat. One is that it is relatively difficult to
apply an overall top coat at high speeds because of problems
usually associated with spraying machines. These include
contamination of machine parts due to overspray, the need for
frequent cleanups and adjustments of spray heads, and the need to
bake the finished ends to drive off solvents that have to be used
to obtain the viscosity requisite for spraying top coat materials.
The presence of solvents in the spray coat is problematical because
they are dangerous to inhale and handle. They also pollute and
require expensive exhaust and other pollution-preventing handling
systems.
High speed commercial spray coating machines require deposition of
repair coats in 2 seconds or less. At such speeds, spraying often
does not obtain satisfactory seals of imperfections because the
predetermined amount of material sprayed throughout the interior of
the can body often does not provide enough material adjacent a
particularly large discontinuity to adequately seal it.
Spraying an overall coat often does not provide uniform coatings
since too little solvent results in too little coverage in some
areas and lumps or accumulations in other areas, and too much
solvent causes dripping, sags and runs.
Spraying is wasteful because coating material is applied to the
entire interior surface area rather than limitedly as and where it
is needed.
Lastly, spraying an overall top coat causes webbing and frilling
about the pouring openings of easy-open can ends, due to the top
coat completely covering the base coat and often adhering more
strongly to the base coat than the base coat to the can ends, when
the score-defined easy-open tear out portions are removed
therefrom.
The electrocoating system of this invention solves all of the
aforementioned disadvantages and problems and others as well. It is
fast enough for commercial high speed operation. It has been used
for example to repair coat in 2 seconds or less at rates of 600
cans per minute. There is virtually no contamination of machine
parts due to overuse, and there is less need for clean-ups and
adjustments.
The system is selective, self-limiting and nonwasteful. It deposits
uniform coatings of sufficient quantity to attain satisfactory
single and repair coats which do not web and frill.
The system is advantageous because aqueous electrocoating solutions
can be employed therewith. These are not dangerous to handle and
prevent pollution of the atmosphere by not requiring solvents.
Aqueous materials do not require expensive solvent exhaust and
handling systems. An added advantage is that the system of this
invention can be used in place of four conventional body spray
machines.
This system is especially advantageous because it can be used to
apply a single full coat which satisfactorily coats the entire
interior surface areas of the container bodies, or it can be used
to repair or spot coat only imperfections in a previously applied
base coat.
Numerous other advantages of the electrocoating system of this
invention including apparatus, method and valve will be apparent as
it is better understood from the description which follows, which,
taken in conjunction with the drawings, discloses preferred
embodiments thereof.
SUMMARY OF THE INVENTION
This invention is an electrocoating system including apparatus,
method and a valve for electrodepositing a coating on interior
electrically-conductive surface areas of container bodies having an
open end. The apparatus comprises a rotatable reservoir or drum
having a cylindrical wall, for containing an electrolytic fluid;
means for rotating the drum; valve means mounted preferably
radially in rowed, radially-aligned spaced pairs around the
circumference of the cylindrical wall, for passing the fluid to and
from the interior thereof, all portions of the valve means in
contact with the fluid being non-conductive in relation thereto; an
electrode, preferably a helical spring, connected to and projecting
radially from the exterior of the valve means; the valve means
including: means for carrying electric current therethrough to the
electrode, a housing having fixed and moveable portions, the
moveable portion having a mouth therein, a valve member fixedly
connected to the fixed housing portion, and preferably having a
metal core running therethrough, the core being included within the
current carrying means, biasing means mounted between the fixed and
moveable housing portions, and a resilient sealing ring located on
the mouth of the moveable housing portion and moveably biased by
the biasing means into sealing engagement with the valve member;
means partly mounted on the drum for creating a potential
difference between the electrode and the interior conductive
surface areas of the container bodies, the aforementioned portion
of the potential creating means, preferably being a commutator
assembly means mounted interiorly of the drum and including
intermediate circuitry connecting it to the current carrying means;
and, means for feeding the container bodies onto the valve means so
that the bodies are registered thereon, the electrode projects into
the interior of the bodies and the rims of the bodies sealingly
engage the sealing ring with pressure sufficient to break the
sealing engagement between the valve member and the sealing ring to
create a passageway therebetween which allows the fluid to pass
through the valve means and into the container bodies during a
portion of the reservoir rotation, so that a potential created
electrodeposits a coating on interior electrically-conductive
surface areas of the container bodies.
The feeding means can include means, preferably cradles, mounted
radially on the cylindrical wall adjacent each valve means for
receiving the container bodies from a source and placing the bodies
in register onto the sealing rings so that the electrode projects
into the interior of the bodies. The feeding means can also include
means for holding the can bodies in registered sealing engagement
on the sealing ring and for providing pressure sufficient to create
a passageway between the valve member and the sealing ring which
allows the fluid to pass through the valve means and into the
container bodies during a portion of the drum rotation so that the
potential created during that portion of rotation electrodeposits a
coating on interior electrically-conductive surface areas of the
container bodies.
The apparatus can also include means connected to the interior of
the drum for, preferably pressuredly, charging, leveling and
draining the fluid to, in and from the drum, and it can include
means for removing the container bodies from the valve means and
from the drum. The removing means can include a knife for
separating the rims of the container bodies from the sealing ring
of the valve means.
The axis of the drum can be tilted and its non-cylindrical walls
arcuate, so that liquid on the drum walls does not accumulate
thereon but drains toward the bottom portion of the drum.
The method of the invention comprises rotating, preferably
continuously, a reservoir or drum containing an electrolytic fluid
and having valve means mounted in the exterior walls thereof, the
valve means in turn having an electrode projecting therefrom;
feeding, preferably simultaneously, the container bodies onto the
valve means so that the bodies are registered on the valve means
and the electrode projects into the interior of the container
bodies, providing axial pressure against the container bodies,
preferably against their exteriormost ends, sufficient to sealingly
engage the rims of the can bodies against a portion of the valve
means and to open the valve means; passing the fluid from the
rotating drum through the open valve means and into the sealingly
engaged bodies; creating a potential difference between the
electrode and the interior surfaces of the bodies when they contain
the fluid; and thereby electrodepositing a coating on the interior
electrically-conductive surface areas of the bodies.
The pressure providing step can be maintained throughout a major
portion of the drum rotation and the fluid passing step,
preferably, is effected by gravity. The method can also include the
steps of insulating the means for creating the potential and the
means for carrying the electric current through the valve means to
the electrode, and charging the fluid to the drum and removing the
coated container bodies from the valve means and from the
reservoir.
The fluid valve of this invention for electrodepositing systems
wherein an electrolytic fluid and electric current insulatedly pass
through the valve, comprises: a fixed exterior housing mountable on
a wall of a reservoir containing the fluid, the exterior housing
having a back wall with apertures therein communicating with the
interior of the reservoir; a moveable interior housing, interior of
and slidingly engaged with the exterior housing, the interior wall
of the interior housing defining a central valve chamber and having
a mouth opposite the back wall; a resilient sealing ring mounted in
the mouth; a valve member fixedly connected at one of its ends to
the back wall, extending axially into the chamber and having legs
fixed to and extending transverse to its axis, the axial portion of
the valve member having a conductive core connectable to circuitry;
an electrode, preferably a helical spring, connected to and
projecting, preferably radially, from the exterior of the valve
member; means for sealing and preventing fluid from passing between
the housing; and biasing means, preferably a helical spring
extending around and being abuttingly biased against a support wall
of the interior housing, for flexibly biasing the sealing ring and
the interior housing into sealing engagement with the valve member
legs to seal the fluid valve chamber, the biasing means being
inwardly compressible towards the back wall by an axial force so
that when the force is sufficient to compress the sealing ring and
biasing means, a passageway is created between the valve member
legs and the sealing ring which allows fluid to flow from the
reservoir to the exterior of the valve chamber.
Preferably, all parts of the valve exposable to the fluid excluding
the electrode are non-conductive in relation to the fluid. The
biasing means can also include a rigid backing ring adjacent the
back wall of the exterior housing for backing the spring, and a
rigid lock washer mounted between the backing ring and the spring,
for backing the spring and acting as a stop against outward
movement of the interior housing. The fluid sealing and preventing
means can include an annular, flexible, resilient interior sleeve
partly within the chamber and sealingly fastened to the interior of
the interior housing and the exterior of the exterior housing to
prevent fluid from passing therebetween, and an annular, flexible,
resilient exterior sleeve sealingly fastened to and for sealing the
exteriors of the interior and exterior housings, exterior of the
reservoir wall. The fluid sealing and preventing means can further
include an annular, elastomeric O-ring between the back wall and an
interior sleeve portion that is adjacent the backing ring.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevation showing the electrocoating apparatus of
this invention.
FIG. 2 is a plan view taken substantially along line 2--2 of FIG.
1.
FIG. 3 is an enlarged vertical section taken substantially along
line 3--3 of FIG. 1 showing a portion of the drum and the valves
mounted thereon.
FIG. 4 is an enlarged perspective view of one of the cradles
mounted on, but shown broken away from, the reservoir of FIG.
3.
FIG. 5 is an enlarged vertical section through a portion of the
electrocoating reservoir and through a fluid valve mounted therein
before a can body is placed on the valve.
FIG. 6 is an enlarged vertical section similar to that of FIG. 5,
showing the fluid valve in an open position and liquid passing from
the reservoir into a can body placed on the valve and shown partly
broken away.
FIG. 7 is a plan view taken substantially along line 7--7 of FIG. 6
showing apertures in the valve housing wall.
FIG. 8 is a front view of the commutator assembly of FIG. 3 with
parts broken away showing some of its mechanisms and electrical
circuitry.
FIG. 9 is a top view taken substantially along line 9--9 of FIG.
8.
FIG. 10 is a vertical section taken substantially along line 10--10
of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred, exemplary embodiment of this invention, FIG. 1
shows an electrocoating or electrodepositing system generally
designated 10 comprising a rotatable reservoir or drum 12 rotatably
mounted on a main frame 15. The reservoir (hereinafter drum) is
driven by means for rotating the drum which include drive means
such as motor 16, whose flange 17 is mounted to a frame (not
shown). Motor 16 drives pinion gear 18 mounted on shaft 19 which
drives main ring gear 20 fixed to an interior wall (not shown) of
drum 12. Ring gear 20 in turn drives feeding means generally
designated 22 for feeding container or can bodies 44 onto drum 12,
and discharge or take-off means generally designated 23 (hereafter
discharge means) for discharging coated container bodies 44' from
drum 12. "Coated" in this context means full or repair coated by an
electrolytic fluid 84 in drum 12 according to this invention. Ring
gear 20 drives both feeding means 22 and discharge means 23 by
driving pinion gear 24 rotatably mounted on shaft 25, mounted on
flange 25', and fixed to pulley 26. Pulley 26 drives belt 27 which
in turn drives pulley 28 rotatably mounted on shaft 29, mounted on
flange 29', and fixed to pulley 30. Pulley 30 drives belt 31 shown
connected to pulley 32 which in turn drives belt 34 connected to
pulley 36. Box 37 represents mechanism (not shown) sufficient to
transfer the rotary motion of pulley 36 into timed simultaneous
rotation of feeding means 22 including shafts 38 (shown) and 39
(FIG. 2) respectively fixedly connected to worm feed screws 40
(shown) and 42 respectively having grooves 41 (shown) and 43 for
timedly feeding can bodies 44 to means included within the feeding
means such as cradles generally designated 46 for placing the
container bodies in register on valve means 50 and on electrodes 48
connected to and projecting from valve means 50 mounted in the
exterior of, preferably cylindrical, wall 52 of drum 12.
Pulley 32, driven by belt 31 and also fixed to pulley 54 on a shaft
(not numbered), drives belt 56 which in turn drives pulley 57 fixed
to a set of miter gears 58 (not shown) and 59 connected to other
suitable mechanisms in box 60. The miter gears are connected to
other mechanisms (not shown) sufficient to rotate a series of
vertical shafts 62 (FIG. 2) fixedly connected to drive pulleys 63,
on which are mounted continuous discharge or take-off belts 64,
also mounted on series of idler pulleys 65 on shafts 66 mounted to
a broken away portion of frame 67. Pairs of discharge belts 64
engage the sides of "coated" can bodies 44', lift them from cradles
generally designated 46 and transfer them to removal chutes
comprised of side discharge guard rails 68 and upper and lower
discharge guide rails 70. Coated can bodies 44' can be further
moved along the guide rails away from electrocoating system 10 by
any suitable means such as a series of turrets, guide rails and
moving belts (not shown) which, for example, could reverse their
direction and move them to other stations for further
processing.
As motor 16 drives ring gear 20 to continuously rotate drum 12 in a
clockwise direction, and as it also simultaneously and timedly
drives worm feed screws 40 and 42 to place uncoated can bodies 44
in register on valves 50, the can bodies are held in register by
holding means such as continuous cables 72 (one shown) driven by
the rotation of drum 12. Cable 72 passes over roller 74 mounted on
shaft 78 and insulating sleeve 79, and over roller 76 mounted on
shaft 80, each being respectively rotatably mounted on broken away
arms 81 and 82. Brush 71 on arm 73 (broken away) connected by wire
75 to a negative D.C. source (not shown), engages and thereby
imparts an anodic, negative charge to cable 72. Roller 76 brings
cable 72 into engagement with cradles 46 and the bottom ends of
uncoated container bodies 44. This imparts the negative charge to
bodies 44, renders them anodic and pressuredly holds the bodies
against valves 50 as drum 12 rotates for a major portion of its
360.degree. of rotation. Cable 72 supplies sufficient axial
pressure against bodies 44 that their rims of their open ends
abutting valve 50 sealingly engage sealing ring 156 (described
later) of valve 50, and the rim pressure opens the valves so that,
as substantially hollow drum 12 rotates in a clockwise direction,
electrolytic fluid 84 contained therein passes, preferably by
gravity, through valve 50 and fills cans 44 on the lower portion of
drum 12 without leakage of electrolytic fluid 84 from the system.
As further explained later, when can bodies 44 are filled with
fluid 84, a potential is created between electrodes 48 and interior
electrically-conductive surface areas of can bodies 44 so that a
coating is electrodeposited on the surfaces. As drum 12 continues
to rotate the upper portion of cable 72 separates from coated can
bodies 44' and allows them to be removed from valves 50 and cradles
46 for discharge from the system.
FIG. 2 is an enlarged top view taken along lines 2--2 of FIG. 1 and
shows a portion of discharge means 23 of the apparatus of this
invention. More particularly, FIG. 2 shows an upper portion of
cylindrical drum wall 52 underlying a series of aligned shafts 62
and dummy rollers 63, and 66 and 65, the former of which are
drivingly rotated in such directions that, as shown, the inner
portions of upper and lower pairs of discharge belts 64 cooperate
to engage the sides of coated can bodies 44' and thereby
participate in their removal from sealing rings 156 and electrodes
48 of valves means 50, and from cradles 46. Belts 64 also gradually
move the cans along a horizontal plane. The rotation of drum 12
cooperates in the removal of electrodes 48 and cradles 46 from the
can bodies. As the bodies are so carried along a horizontal plane,
they are passed within the confines of pairs of side guide rails 68
(the uppermost one on each side shown) and upper and lower guide
rails 70, which can pass them to other suitable mechanisms such as
turrets, belts and other guide rails (not shown) to further remove
the coated bodies to other stations for further processing such as
baking and filling.
The right hand portion of FIG. 2 shows the uppermost of can bodies
44 in two respective stacks thereof within guide rails 45, above
their respective worm feed screws 40 (shown in FIG. 1) and 42
respectively having feed grooves 41 and 43 and being mounted on
shafts 38 and 39 for synchronously, simultaneously and timedly
feeding can bodies 44 onto cradles 46 and valves 50 of rotating
drum 12. Also shown are portions of cables 72 broken away on their
respective, also broken away, rollers 74 and 76.
FIG. 3 is an enlarged section taken substantially along line 3--3
of FIG. 1. More particularly, FIG. 3 shows drum 12 having front
convex wall 51, cylindrical wall 52 and rear concave wall 53.
Valves 50 are mounted on cylindrical wall 52 by insulating mounts,
generally designated 49, which also insulatedly mount cradles 46
(broken away) having at their upper ends, notches 134 between and
defined by spaced tines 133.
Fastened or attached to the rear of concave drum wall 53 as by weld
86 are arms 88 of a spider structure 87 whose flanges 89 have
screws 90 passing therethrough and which fasten rear drum wall 53
to main ring gear 20 having peripheral teeth 21. As motor driven
pinion gear 18 (FIG. 1) drivingly rotates main ring gear 20 and
drum 12, the ring gear rotates on friction free ball bearings 92 in
grooves within the inside of main gear 20 and within the exterior
side of track 94 fixedly attached by screws 96 through its flange
to bracket 99 in turn fixedly attached to main frame 15.
Attached to the interior of rear drum wall 53 by means of bolts
280, rubber spacers 282 and fastening rings 284, is a portion of
the means for creating a potential between electrodes 48 and
interior electrically-conductive surface areas of can bodies 44
mounted on valve 50. The aforementioned portion of the potential
creating means can be a commutator assembly generally designated
96, having a housing 97 comprised of a cylindrical wall 98 and
front and rear walls 100 and 102. Housing 97 is mounted on hollow
support 104 whose axis, it is to be noted, is concentric with that
of main ring gear 20. Running through hollow support 104 are means
such as pipes 106 for draining, 108 for leveling, and 110 for
filling drum 12 with an electrolytic fluid. The pipes extend
through hollow support enclosure cap 105 downwardly into the lower
portion of drum 12 to or into the upper level of fluid 84
represented by dashed line 85 (pipe 110 not being shown). The rear
portions of pipes 106, 108 and 110 can be connected to suitable
means such as pumps for pressuredly or otherwise quickly effecting
the draining, leveling and filling actions.
Also extending through hollow support 104 is conduit 112 for
carrying wire 114 which can be connected exteriorly of drum 12 to a
suitable portion of the potential creating means such as a voltage
source (not shown). Conduit 112 carries wire 114 into commutator
assembly 96 where it is attached to other portions of the
aforementioned means for creating a potential.
As mentioned previously, commutator assembly 96 is affixed to drum
12 and rotates therewith. Connected to commutator assembly exterior
cylindrical wall 98 and communicating with a portion of the means
for creating a potential within commutator assembly 96 are offset
fluid-proof terminals generally designated 116 on the upper, front
portion, and 116' on the lower rear portion of cylindrical wall 98.
Also connected to commutator assembly cylindrical wall 98 are bolts
119' in the upper rear end, and 119 at the lower front end of wall
98. Their function will be explained later. Connected to and
running from terminals 116 and 116' is intermediate circuitry
comprising respective wires 120 and 121, and 120' and 121' which
are part of the potential creating means and which pass through the
interior of drum 12, through apertures in guide mounts 125 and are
respectively connected to valves 50 by suitable electrical
connecting means such as fluid-proof terminals 122 on the front and
rear portions of drum 12. Wires 120 and 121 and 120' and 121'
communicate with and are connected to electrodes 48, as shown
later. Guide mounts 125 reduce the slack of the aforementioned
wires and prevent them from flopping around in drum 12 as it
rotates. Mounts 125 also act as nuts for insulating mounts 49 on
the exterior of cylindrical wall 52.
FIG. 3 also shows pinion gear 24 fixed to shaft 25 whose central
axis, it is to be noted, is offset towards the reader from the axis
of hollow support 104. Shaft 25 runs through bearing 128 attached
through its flange by screws 130 to bracket 99, and it runs through
pulley 26 to which it is fixed and drivingly rotates. Pulley 26
drives belt 27 which drives pulley 28 fixedly mounted to shaft 29
running through support bearing 130. Shaft 29 is fixedly connected
to pulley 30 which drives belt 31 shown broken away but connected
to other pulleys for driving the feeding and discharge means (FIG.
1). Support bearing 130 is fastened by means of screws 132 through
its flange to frame 15.
It is to be noted that the axis of hollow support 104 and shafts 25
and 29 are not horizontal but are slightly tipped so that drum 12
is angled slightly outwardly from its top to its bottom. Drum 12 is
slightly angled in this manner so that no interior wall surface of
the drum extends in a horizontal direction. This is to assure that
electrolytic fluid on any interior wall surface of drum 12 can run
in at least a somewhat downward direction toward the bottom of the
drum for draining. This angularity helps to keep the interior
surfaces of the drum clean by preventing fluid material or
particles from accumulating on interior surfaces of the drum.
The lower portion of drum 12 shows the bottom closed ends of can
bodies 44 pressuredly and sealingly engagedly mounted on valves 50,
filled with electrolytic fluid 84 (not shown) and held in such
mounted position by holding means such as continuous cables 72
extending substantially around the circumference of cylindrical
drum wall 52. Cables 72 exert axial pressure against the bottom
ends of the can bodies. Cables 72 can be prevented from falling off
bodies 44 (or 44') and can be held in a substantially diametrical
position relative thereto by being held in notches 134 between and
defined by spaced tines 133 adjacent the ends of cradles 46.
The upper portion of FIG. 3 shows cables 72 no longer pressuredly
engaging the bottom ends of coated can bodies 44'. It shows
separating knives 135 having separated the rims of bodies 44' from
valves 50 so that respective pairs of discharge belts 64 engaging
each side of respective bodies 44' can carry the bodies from the
drum in a substantially horizontal plane as drum 12 cooperatively
continues to rotate and carry valves 50 and electrons 48 in a
circumferential arc downwardly out of the bodies 44'. Belts 64
carry the bodies to guide rails 68 and 70 (not shown).
FIG. 4 is an enlarged perspective view of one of cradles 46 shown
broken away in FIG. 3. More particularly, FIG. 4 shows a cradle
generally designated 46 having leg mount 131, arms 132 and spaced
tines 133 defining notch 134 into which cable 72 fits during a
major portion of the rotation of drum 12. Leg mounts 131 are
fastened by bolts of insulating mounts 49 to drum cylindrical wall
52. Arms 132 help receive, register and keep registered bodies 44
on valve means 50, during rotation of drum 12. They also maintain
bodies 44' in position when cables 72 lose contact with the bottoms
of bodies 44' at approximately the 12 o'clock position (FIG.
1).
FIG. 5 is an enlarged section taken substantially along lines 5--5
of FIG. 1. More particularly, FIG. 5 shows valve means such as a
fluid valve, generally designated 50, mounted in a wall of a
reservoir such as cylindrical wall 52 of reservoir or drum 12, the
valve means being shown in its closed position with no fluid in its
chamber and no container body on its sealing rim 156.
Fluid valve means 50 is comprised of a fixed exterior housing,
generally designated 136, fixedly mounted on cylindrical drum wall
52 by means of a substantially L-shaped sealing gasket 138, the
exterior housing having a side wall 140 abutting gasket 138 and
having a rigid back wall 142 proximate the interior of drum 12 and
having apertures 144 therein (one shown) communicating with a
portion of the interior of drum 12 which does not contain any of
fluid 84. Fluid valve 50 is also comprised of a moveable interior
housing 146 interior of and slidingly engaging exterior housing
side wall 140 and defining a central chamber 148. Interior housing
146 has a mouth generally designated 150 and defined by flanges 152
and 154, in which is mounted and seated a resilient sealing ring
156 which is biased by biasing means such as helical spring 158 in
cutout portion generally designated 160 in the exterior wall of
interior housing 146. The biasing being sufficient to sealingly
engage sealing ring 156 against legs 162 of fixed valve member
generally designated 164 fixedly connected through current carrying
means such as core 166 to back wall 142 adjacent apertures 144 in
exterior housing 136. Connected to and extending or projecting from
valve member 164 is an electrode such as helical spring 48
connected to head 168 of phillips screw 170, also part of the
current carrying means, threadedly engaged to core 166. Biasing
means 158 includes rigid backing ring 172 located adjacent back
wall 142, and one or more rigid lock washers 174 mounted between
ring 172 and spring 158, for backing and biasing the spring and
interior housing 146 outwardly toward and against legs 162 of valve
member 164. Both ring 172 and lock washer 174 are located between
inner housing 146 and exterior housing side wall 140.
Abuttingly engaged between the interiormost edge of backing ring
172 and an adjacent portion of exterior housing wall 140 is a fluid
sealing and preventing means which includes a flexible and
resilient annular interior sleeve 176 and an annular elastomeric
O-ring 178 for sealing and preventing fluid from chamber 148 from
passing between interior and exterior housings 146 and 136.
Interior sleeve 176 extends between annular O-ring 178 and backing
ring 172, around the interiormost edge 180 of interior housing 146
and is abuttingly engaged and compressedly fastened within an
annular groove 182 in the interior wall of interior housing 146
defining chamber 148, by means of one or more rigid lock washers
184 (not shown) which peripherally forces adjacent portion of
interior sleeve 176 into annular groove 182.
Also included as part of the fluid sealing and preventing means is
a resilient flexible annular exterior sleeve 186, having flange 188
engagingly extending around interior housing flange 154 and
abuttingly engaging sealing ring 156. Exterior sleeve 186 has an
interior annular bead 190 abuttingly engaging the corner of
interior housing flanges 152 and 154. Exterior sleeve 186 has at
its interiormost end an integral, annular, exterior bead 192
defining an adjacent annular sleeve groove 194 within which an
annular coiled garter spring 196 sealingly holds exterior sleeve
186 within annular exterior housing groove 198 formed by annular
exterior housing bead 200 and flange wall 202. Exterior sleeve 186
is sealingly fastened to interior housing flange 154 by means such
as annular steel wire 204 which sealingly holds a portion of the
exterior sleeve within annular groove 206 in the exterior of
interior housing flange 154.
The upper portion of FIG. 5 shows conductive metal wire portion 126
of an insulated wire such as designated 120 (or 120', 121 or 122')
(FIG. 3), descending through terminal generally designated 122 and
comprised of a connecting screw plug 123 having a non-conductive
fluid-proof plastic or other suitable tube-shield 208 thereover.
Plug 123 is threadedly engaged within the head of connecting screw
jack 124 having a threaded shaft 212 threadedly engaged within bore
214 of exterior housing backwall 142 and within core 166 of valve
member 164. Wire 120 runs through the center of plug 123 and
extends down to and contacts a portion of jack head 124'. Plug 123
can be fastened to connector screw jack 124 or valve means 50 in
any conventional manner that will provide a fluid-tight seal and
will allow plug 123 to be screwed into jack 124 without unduly
twisting the conductive metal wire portion 126.
FIG. 5 shows electrical circuitry that is part of the potential
creating means of this invention. The circuitry includes conductive
wire portion 126 of wire 120, terminal 122, solid metal core 166,
phillips screw 170, head 168, and helical spring electrode 48.
Solid metal core 166 has a non-conductive moisture-proof polyolefin
shield 167 therearound. Valve member legs 162 are covered with a
similar material (not numbered).
It is to be noted that all portions of fluid valve means 50 which
are or might be exposed to electrolytic fluid 84, excluding
electrode 48, are made of, covered with or otherwise isolated from
the current carrying means by, a suitable non-conductive material.
For example, the housings can be manufactured of a commercially
available rigid, moisture-proof, non-conductive material that will
not gall with each other, such as an acetal resin sold under the
trade designation "Delrin," a trademark owned by I. E. Dupont de
Nemours and Co. Inc., for the interior housing, and a commercially
available polycarbonate thermoplastic for the exterior housing.
Annular sealing ring 156, can be made of an elastomer such as
isoprene, and O-ring 178 and interior and exterior sleeves 176 and
186 of a suitable non-conductive flexible resilient non-permeable,
fluid-sealing elastomer such as a neoprene. The only metal parts
employed interior of exterior housing 136, i.e., spring 158,
backing ring 172, and lock washers 174 and 184, are effectively
non-conductively isolated from electrode 48 or from any fluid 84 in
or flowing through chamber 148. The current carrying portions of
fluid valve means 50, e.g., solid metal core 166 and phillips screw
170, preferably are made of steel and are effectively
non-conductively isolated from contact with electrolytic fluid 84
and will therefore not have a build-up of particles thereon which
would require maintenance, clean-up and possible clogging and
inefficient operation of the valve means.
FIG. 6 is an enlarged cross section taken substantially along line
6--6 of FIG. 3. More particularly, a fluid valve means 50 similar
to that in FIG. 5 is shown in an open position. With sufficient
axial pressure exerted by cable 72 against the bottom of container
44, its rim R is presssuredly sealingly engages sealing ring 156
and pushes interior housing 146 inwardly against the bias of spring
158, such that interior housing flange wall 152 abuts exterior
housing lip 201 and the interiormost edge of interior housing 146
flexes interior sleeve 176 inwardly towards aperture 144 of back
wall 142. As interior housing 146 is so moved inwardly and as
sealing ring 156 about valve mouth 150 is also moved inwardly, its
interior angular wall 157 is moved inwardly away from legs 162 of
valve member 164 to break its sealing engagement therewith and
thereby create a passageway P between sealing ring 156 and legs 162
which allows electrolytic fluid 84, which had been in the bottom of
drum 12 and within valve chamber 148, to gravity-pass downwardly
through passageway P and fill container body 44.
As will be explained in detail in relation to FIG. 8, during a
portion of the rotation of drum 12 when electrolytic fluid 84 is
within container body 44, a potential difference is created between
spring electrode 48 and interior electrically-conductive surface
areas of walls W of container body 44. Due to the potential
created, electric current flows through the circuit comprising the
electrode, the fluid and the metal conductive body surface areas.
Coating particles are thereby deposited on the surface areas to
fully coat their entirety or to repair coat discontinuities in a
base coat thereon.
FIG. 7 is a plan view taken substantially along line 7--7 of FIG. 6
and shows an upper portion of exterior housing back wall 142 having
a bevelled edge 143, and having apertures in the wall defined by
arcuate walls 144 and in part by wall 147 of exterior housing 136.
FIG. 7 also shows a cross section through the threaded, shaft
portion 212 of connector screw jack 124 threadedly fastened within
bore 214 to back wall 142.
FIG. 8 is a front elevation taken from the inside of drum 12 just
interior of front wall 51 in FIG. 3. FIG. 8 shows front wall 216 of
enclosure cap 105 having ports 222 and bolts 218 in holes 220 for
securing enclosure cap 105 to wall 103 of hollow support 104. Wall
103 has a stepped surface 103' therein. Enclosure cap ports 222
join and house pipes 106, 108 and 110 entering from hollow support
104, and their broken away portions descending therefrom towards
the bottom of drum 12 (not shown).
FIG. 8 also shows front wall 100 of commutator assembly 96 having a
protruding stepped portion 101 whose lowermost surface 101' of its
lowermost flange is just above cylindrical surface 224 of enclosure
cap 105.
The lower, broken away portion of commutator assembly 96 shows
mounted within drum 12, a portion of the potential creating means
of this invention. It is to be noted that commutator assembly 96 of
FIG. 3 should be considered as divided transversely in half, and
that the largest broken away portion of FIG. 8 shows a portion of
the front half of the commutator assembly (see FIG. 9). The dashed
upper portion of FIG. 8 is also the front portion of the assembly
interior of housing wall 100.
The large broken away portion of FIG. 8 shows electrical cam bar
228 fastened to crib 230 of cam support 232 by means of bolts 234
whose threaded shafts pass through apertures 236 and are threadedly
engaged to cam bar 228' in the rear portion (not shown) of
commutator assembly 96.
It is also to be noted that cam support 232 on which is mounted cam
bar 228, a fixedly mounted upon fixed hollow support 104 which is
in turn fixed to bracket 99. Commutator assembly housing 97 (FIG.
3) including its exterior front wall 100, protruding stepped
portion 101 cylindrical wall 98 and cylindrical wall rib 238, and
all of the structure shown mounted on wall 98 and its rib 238
peripheral to or below cam bar 228, rotate around the
aforementioned fixed structures 232, 228 and 104.
Cylindrical wall 98 has U-shaped cut-outs 240 in its rib 238 and is
fastened to the periphery of housing wall 100 by means of nuts 242
being threadedly fastened to shafts 243. Wall surface 244 of
cylindrical wall 98 abutting the interior of wall 100 shows shaft
243 in section. Spacers 248 are mounted on shafts 250. Pivot arms
246 are rotatably mounted on shafts 250 (front ends shown) which
pass within bores 241 in rib 238 of cylindrical wall 98. Pivot arms
246 have stop portions 252 which limit their rotation by abutting
interior wall surface 245 of cylindrical wall 98. Pivot arms 246
also have electrical contacts which can be carbon brushes or studs
254 mounted therein by their shafts 256 (FIG. 10) passing through
arm bores 258 (FIG. 10) and being threadedly engaged by nuts 259
(FIG. 10). Secured to shafts 256 between nuts 259 and the bottom
surfaces of pivot arms 246 are electrical connecting lugs 260
having wires 121 therein which extend over spacers 248, down
through holes 262 extending radially through cylindrical wall 98,
through terminals 116 and through the interior of drum 12 to
terminals 122 of valves 50. Each wire 121 is joined as by splicing
to another wire 120 and each wire 120 and 121 extends fairly tautly
within drum 12 to cylindrical wall 52 thereof, where they are
electrically connected to valves 50, as shown in FIG. 3.
FIG. 8 also shows a more deeply broken away portion of cylindrical
wall 98 directly underlying contacts 254. FIG. 8 there shows a
substantially Y-shaped bore 264 in wall 98 having threadedly
secured to its lower portion a threaded stud shaft 266 of a bolt
119, the end of which provides a backing for biasing means, such as
helical spring 268, which abuttingly engages contact shaft 256 and
nut 259 on the lower end of contact 254 and thereby normally biases
contact 254 in its uppermost position. Contacts 254 remain in this
position throughout most of the rotation of cylindrical wall 98,
commutator assembly 96, and drum 12, i.e., except for the period of
rotation during which the contacts engage arcuately shaped surface
229 of cam bar 228. As contacts 254 are rotated clockwise and are
passed upwardly to the left around and against electrical cam bar
228, they are moved downwardly on pivot arms 246 against the bias
of springs 268.
Although FIG. 8 only shows a few of the contacts, rocker-arms,
spacers, terminals, etc., it is to be understood that such
mechanisms are located all the way around the periphery of
cylindrical wall 98 of commutator assembly 96.
As mentioned previously, it is to be noted that commutator assembly
96 should be considered as having two halves and that the broken
away portions of FIG. 8 show only the front portion of the front
half of the commutator assembly. This can be more clearly seen in
FIG. 9 which is an enlarged top view taken in section through lines
9--9 of FIG. 8. The lower portion of FIG. 9 is the front of
commutator assembly 96. If one considered front commutator assembly
wall 100 removed from FIG. 9, the front of FIG. 9 would then show
the largest cut away portion of FIG. 8.
Shown in FIG. 9 are pivot arms 246 having contacts 254 whose shafts
256 (not shown) are mounted in bores 258 therein and secured
thereto by nuts 259 (not shown) which also secure electrical
connecting lugs 260 to pivot arms 246. Pivot arms 246 are mounted
on shafts 250 passing through and mounted in cylindrical wall rib
238 by means of nuts 274 within U-shaped grooves 240, being
threadedly engaged to shafts 250. Shafts 250 pass through bores 241
in rib 238 and have integral nut-shaped flanges 278 acting as
spacers between rib 238 and pivot arms 246. Shafts 250 also have
mounted thereon spacers 248 which cooperate with flange spacers 278
to maintain pivot arms 246 in an aligned position so that the
rotary path of commutator assembly's cylindrical wall 98 will bring
contacts 254 into aligned contact with cam bar 228. FIG. 9 shows
wire 121, crimped to and running from connecting lug 260, passing
over spacer 248 down through hole 262 (dotted circles under spacers
248) in cylindrical wall 98 and down through terminal 116 (not
shown) whose connecting screw jack 118 (not shown) is mounted in
the bottom of cylindrical wall 98. Also shown in FIG. 9 are
Y-shaped bores 264, under contacts 254 (here removed), the bores
having springs 268 mounted therein and biased upwardly towards the
reader by bolt stud shaft 266.
The rear portion of FIG. 9 is a duplication of the structure just
described for the front portion of FIG. 9, except that the rear
structures, it is to be noted, are given primed numerical
designations and they are offset from the structures in the
front.
FIG. 10 is a cross section taken substantially along line 10--10
through commutator asssembly 96 of FIG. 8. More particularly, FIG.
10 shows, mounted within drum 12 on rear wall 53 by means of bolts
280, spacers 282 and ring 284, commutator assembly 96 having rear
wall 102 secured to rear drum wall 53 and front wall 100, and,
fixed therebetween, cylindrical wall 98. The upper portion of FIG.
10 shows rib 238 of cylindrical wall 98 having shaft 250 extending
therethrough and being secured to rib 238 by means of nut 274 in
U-shaped groove 240. Shaft 250 has integral flange spacer 278
betweeen pivot arm 246 and rib 238. Wire 121 is shown passing from
within commutator assembly 96 through bore 262, terminal connecting
screw jack 118, and connecting screw plug 117, where it is joined
by wire 122, both wires passing to valves on cylindrical drum wall
52 (not shown).
That portion of cylindrical wall 98 and commutator assembly 96
shown to the right of rib 238, which in FIGS. 8 and 9 has been
called the rear of the commutator assembly, shows contact 254'
mounted on shaft 256' and secured to rocker arm 246' by nut 259'.
Contact 254' is biased in a downward direction by spring 268' and
by threaded stud shaft 266' of bolt 119'.
The lower portion of FIG. 10 shows front cam bar 228 and rear cam
bar 228' secured to cam support ring 232 by means of bolt 234
passing within apertures 236 (not shown) and being threadedly
engaged to cam bar 228'. FIG. 10 shows contact 254 mounted on
rocker arm 246 and being biased against and contacting cam bar 228
to thereby close a circuit which allows electrodepositing current
to flow from a voltage source (not shown) through wire 114 in
conduit 112, connecting lug 272, bolt 234, cam bar 228, contact
254, shaft 256, connecting lug 260, wire 121, which passes over
spacer 248 and passes down through offset front structure not
shown, i.e., bore 262 and terminal 116 comprising connector screw
jack 118 and connector screw plug 117 (such as shown in FIG. 8). At
the exterior of terminal 116, as in FIG. 8, wire 121 is joined by
wire 120 and both wires run as part of intermediate circuitry to
valves 50 on the lower portion of drum 12 (not shown). The
aforementioned structure not shown in FIG. 10 but shown in FIG. 8,
is the same as the structure through which wire 121' passes at the
lower rear of FIG. 10.
Commutator assembly 96 and all of its housing walls 100, 98 and 102
(affixed to rear drum wall) rotate with drum 12 around fixed hollow
support 104 secured through its flanges to frame bracket 99 by
bolts 286. Commutator assembly 96 rotates around cam support ring
232 fixedly mounted on hollow support 104 by enclosure cap 105
being bolted by bolts 218 to hollow support wall 103 whose recessed
flange surface 226 abuts spacer 288 whose hub 290 abuttingly and
fixedly engages cam support ring 232 against wall stepped surface
103".
FIG. 10 also shows that the lower interior surfaces of protruding
stepped front wall 101 has flange rings (unnumbered) which
cooperate with grooves and opposing flange rings in spacer 288 to
form a labyrinth seal for preventing fluid within drum 12 from
passing through channel 290 and splashing into commutator assembly
96. FIG. 10 also shows drain pipe 106 (broken away) passing through
hollow support 104 and through port 222 downwardly into drum 12.
Conduit 112 passing through the interior of hollow support 104 has
an elbow 113 and is secured to support 104 by nut 292 engaging
flanges of support 104.
As shown in FIG. 9, contacts 254 and 254' are staggered, each
separately sending current through wires 121 and 121', respectively
staggered terminals 116 and 116', and joining wires 120 and 120',
each of which wires 120 and 121 goes to one of an aligned pair of
valves 50 and wires 121 and 121' to the next aligned pair of valves
50 on cylindrical wall 52 of drum 12. This staggered arrangement of
contacts 254 and 254' means that as a front contact 254 engages cam
bar 288, one will leave 288, during which time the number of rear
contacts 254' does not change. This keeps the current load fairly
constant by not making more simultaneous contacts and therefore
larger current demands.
The electrocoating system of this invention for electrodepositing a
coating on interior electrically-conductive surface areas of
container bodies, can be operated by a method which comprises
starting the means for rotating the reservoir, i.e., the drive
means which includes the motor 16, which in turn drives pinion gear
18 in a counterclockwise direction. This drives main ring gear 20
and reservoir or drum 12 attached thereto, in a clockwise
direction. Main ring gear 20 in turn drives pinion gear 24 and the
aforementioned series of belts and pulleys which in turn ultimately
drive feeding means 22 for feeding can bodies 44 onto rotating drum
12, and also drive take-off or discharge means 23 for taking the
coated can bodies 44' off of drum 12 and discharging them from the
system for further processing at other stations.
In the preferred embodiment shown in the drawings, a plurality of
uncoated can bodies 44 from a source are individually passed
through guide rails 45 defining two stacks, the lowermost can body
44 of each stack being taken within respective grooves 41 and 43 of
respective worm feed screws 40 (FIG. 1) and 42 (FIG. 2), which, as
they rotate, simultaneously, synchronously and timedly feed their
respective can bodies onto each cradle 46 of a pair from a
radially-aligned continuous series of such pairs mountedly aligned
in two rows around the circumference of synchronously rotating drum
12. Uncoated can bodies 44 are passed from worm feed grooves 41
onto cradles 46 when the cradles are at an angle which allows the
can bodies to slide down the cradles and over electrodes 48
protruding from each valve 50 mounted in the drum. Thus, worm feed
screws 40 and 42 cooperate with cradles 46 to feed uncoated can
bodies 44 in register onto valve means 50.
As drum 12 continues to rotate in a clockwise direction, the rims
of each row of uncoated can bodies 44 restingly registered on
valves 50 are diametrically, pressuredly engaged by continuous
cables 72 driven by drum 12 to rotate in a clockwise direction over
rollers 74 and 76. The tautness of cables 72 caused by the passage
of cables 72 over the rollers maintains the diametrical pressured
engagement with the bottoms of the can bodies throughout rotation
of drum 12 until the coated can bodies 44', are taken off drum 12.
As shown in FIG. 3, cables 72 are aligned with and are positioned
within cradle notches 134 of spaced tines 133 so that the cables
remain aligned in diametrical position in relation to the can
bodies throughout the rotation of the drum. Cables 72 provide
sufficient axial presssure on the bottoms of the can bodies to
sealingly engage their rims against sealing rings 156 in mouths 150
of valves 50, and to depress or move interior valve housings 146
inwardly against the bias of their springs 158 to create
passageways P between valve member legs 162 and sealing rings 156.
Cables 72 are taut enough to maintain this pressure and to maintain
passageways P from approximately the 3 o'clock to approximately the
12 o'clock rotational position of drum 12 (FIG. 1).
When the uncoated bodies 44 are sealingly engaged against valves 50
and a passageway has been created leading from drum 12 to the
interiors of the bodies, drum 12 continues to rotate. As can bodies
44 on open valves 50 are rotated downwardly, electrolytic fluid 84
within drum 12 gravity-passes through passageways P into the
interiors of bodies 44. Fluid 84 gravity-remains therein during
drum rotation from about the 4 o'clock to about the 8 o'clock
rotation position during which time the electrodeposition process
takes place when contacts 254 and 254' engage cam bars 288 and
288'. Fluid 84 in now coated bodies 44' gravity-passes therefrom
through passageway P and drains back into drum 12. Fluid 84
continues to drain therefrom as the coated bodies 44' continue to
be rotated from about the aforementioned 8 o'clock position to
about the 11 or 12 o'clock position, where coated bodies 44' are
removed from the drum.
Before uncoated bodies 44 on open valves 50 adjacent the 3 o'clock
position are rotated downwardly to a position where fluid 84 begins
to pass into the can bodies, a voltage is created in the potential
creating means, e.g., in a power supply (not shown) sufficient to
pass requisite current through wire 114 in conduit 112 of hollow
support 104, the electrical circuitry of commutator 96, wires 120,
120' and 121, 121', and through valve members 162 of valves 50 to
spring electrodes 48.
In the preferred embodiments shown in the drawings, electrode 48 is
cathodic, and, current created therein and transferred to
electrolytic fluid or coating medium 84 causes coating ions or
polyelectrolytic particles therein and carrying a negative charge
to migrate to and discharge onto interior electrically conductive,
here positively, charged surface areas of the anodic metal can
bodies. This electrodeposition or electrocoating process takes
place during the time that contacts 254 and 254' engage cam bars
288 and 288', generally between about the 6 and 9 o'clock
rotational positions of drum 12, as shown in the broken away
portion of FIG. 8. The length of time of electrodeposition can be
varied by varying the length of the cam bars.
Coated can bodies 44' are held onto drum 12 by cables 72 until
about the 12 o'clock position where the cables angle off the path
of rotation of drum 12, and, as they leave the can bodies, the
bodies are grasped between pairs of take-off or discharge belts 64
in a manner that allows the can bodies to be lifted from cradles 46
and from electrodes 48 without the electrodes contacting interior
surfaces of the bodies or cradles 46 touching previous removed
cans. Both front and rear take-off or discharge means 23 are driven
by main ring gear 20 and by various belts and pulleys and they are
simultaneously operated in timed, synchronous relationship with the
rotation of drum 12 and with feeding means 22.
The reservoir or drum 12 of this invention can be of any suitable
size or shape and can be of any suitable material. Preferably, the
reservoir is drum-like and has a cylindrical wall. When the drum is
made of stainless steel or another conductive material, it is
advantageous to coat the interior of the drum with a suitable
material such as a conventional asphalt-epoxy coating (discussed
later), that will prevent coating ions or electrolytic particles
from depositing upon and accumulating upon the interior walls of
the drum.
Fluid valve means 50 can be mounted in drum 12 in any suitable
number, order, or arrangement, although it has been found
advantageous to mount them in one or more and preferably a
plurality of rows of radially aligned pairs. All parts of valve
means 50 exposed to electrolytic fluid 84 are non-conductive in
relation to fluid 84. They are isolated from electric current so
that all exposed parts and moveable parts are not subject to an
accumulation or build-up of coating ions or electrolytic particles
thereon. For example, conductive parts such as spring 158 and
backing ring 172 are isolated from fluid 84 by interior housing
146, and stainless steel core 166 of valve 50 is insulated from
fluid 84 by non-conductive thermoplastic insulative coatings such
as 167 on valve member 164.
Electrodes 48 preferably are helical springs for preventing can jam
up on sealing rings 156 of valves 50. However, the electrodes can
be of any suitable conductive material or design sufficient to
deposit the requisite amount of coating ions or electrolytic
particles on all interior electrically conductive surfaces areas of
can body walls W. The electrode can be of any size or shape
sufficient to allow the registered feeding of uncoated can bodies
44 thereover and the systematic continuous take-off of can bodies
44' therefrom without the electrodes touching or otherwise
preventing the take-off and discharge from the electrocoating
system.
Cradles 46 can be of any suitable shape and can be of any suitable
conductive or non-conductive materials. However it is advantageous
that the cradle be conductive when the means for holding the
uncoated can bodies 44 on valves 50 has and imparts a negative
charge such as cables 72 so that cradles 46 aid in passing this
negative charge to the can bodies 44. When cradles 46 are
conductive it is advantageous to mount them on non-conductive
mounts to insulate a conductive, e.g., steel drum therefrom.
Feeding means generally designated 22 can include any suitable
means for feeding can bodies 44 in timed, simultaneous synchronous
registered fashion in relation to the rotation of drum 12 so that
the bodies are deposited in cradles 46 and are mounted on
electrodes 48 and registered on sealing rings 156 of valves 50. The
feeding means includes cradles 46 or other suitable means for
registering the can bodies on the sealing ring of valve means 50.
Feeding means 22 also includes any suitable means such as
continuous cables 72 for holding the bodies in registered sealing
engagement on sealing rings 156 and for providing pressure
sufficient to create passageways P between valve member legs 162
and sealing rings 156.
This invention is suitable for use with can bodies having either
one or two open ends. However, when the bodies have two open ends,
the holding means can include means for sealing the exteriormost
open end of such bodies to retain the electrolytic fluid 84 therein
during the electrocoating depositing process.
Take-off or discharge means 23 can include any suitable means such
as knives 134 for separating the rims of the coated can bodies 44'
from the valve means 50, and can include any suitable means for
removing the coated can bodies 44' from radially protruding
electrodes 48 and cradles 46 without electrodes 48 contacting the
can bodies or either structure interferring with their removal.
Discharge means 23 can also include any suitable means such as
guide rails or conveyors for transferring the removed can bodies
from the system to another location for further processing.
Container bodies suitable for having coating ions or electrolytic
particles deposited upon their interior electrically-conductive
surface areas, can be any can body made of conventional materials
such as aluminium, tinplate, tin-free steel (TFS), or black plate.
The container bodies coated according to this invention can be
2-piece bodies for making 3-piece cans, or 1-piece bodies for
making 2-piece cans. The container bodies can have two open ends
but preferably they only have one open end. The two-piece bodies
for coating can have any conventional side seam construction, and
the one-piece cans for coating can be drawn and ironed or
impact-extruded.
As mentioned previously, can bodies 44, herebefore designated
"uncoated" has been meant to include container bodies which do not
have and are intended to receive a full single coat, or cans which
have a base coat which requires a repair coat.
The means for creating a potential between electrodes 48 and can
bodies 44 can include any conventional power source. It has been
found advantageous to employ a standard, conventional, low ripple,
constant voltage source such as that designated Model No. SCR-500,
manufactured by Electronic Measurements Inc.
The amount of voltage employed to electrodeposit a single or repair
coat from an organic polyelectrolytic medium can be any sufficient
amount depending on the circumstances, preferably the least amount
that will give a satisfactory single or repair coat in the time
desired for the particular metal substrate and electrocoating
medium employed. Typical voltages generally utilized in
electrocoating processes are in the range of about 50-500 volts,
more commonly from about 100-400 volts.
The polyelectrolytic electrocoating material mediums which can be
employed in the electrocoating system of this invention can be any
of the organic resin-containing materials utilizable as
electrocoating concentrates or baths in metal electrocoating
systems. The mediums can be aqueous or non-aqueous, i.e., solvent
containing, but preferably they are aqueous. The mediums can be
modified, extended, and stabilized with solutilizers or other
materials.
Examples of aqueous mediums which can be employed are those
disclosed in U.S. Pat. No. 3,230,162 issued to A. E. Gilchrist on
Jan. 18, 1966. Disclosed therein are numerous concentrate
compositions generally comprising about 50 to 95 percent by weight
polycarboxylic acid resin, about 1 to 10 percent water soluble
amino compound and the balance water. The polycarboxylic acid
resins are film-forming at electrodeposition bath temperatures, and
are curable to a tack-free film.
Other aqueous polyelectrolytic electrocoating material mediums
which can be employed according to this invention are disclosed in
U.S. Pat. No. 3,366,563 issued to Hart on Jan. 30, 1968. Generally,
Hart discloses an aqueous electrocoating bath containing a
solubilized vehicle resin which comprises the reaction product of a
drying oil fatty acid ester or a semi-drying oil fatty acid ester
with an alpha, beta-ethylenically unsaturated dicarboxylic acid or
an anhydride of such an acid.
Examples of non-aqueous polyelectrolytic electrocoating material
mediums which can also be employed are disclosed in U.S. Pat. No.
3,463,714 issued to W. D. Suomi and A. R. Ravve on Aug. 26, 1969.
Disclosed therein are electrocoating baths prepared generally by
dissolving a carboxyl-containing polymer and a basic
nitrogen-containing compound in an organic solvent and adding a
sufficient amount of a polar organic non-solvent having a
solubility parameter greater than 12 and a hydrogen bond index
greater than 7.5 to convert the solution into a suspension.
The polyelectrolytic electrocoating material mediums disclosed in
the aforementioned patents are merely examples of some of the many
aqueous and non-aqueous mediums which can be employed. For example,
also utilizable are non-polycarboxylic acid resins such as rubber
lattice suspended resins adsorbed by hydroxyl ions, and resins
formulated for example from phenolics, polyvinyl ethers, cellulosic
resins, polyimides and silicones.
That the electrocoating system of this invention can be employed to
electrocoat interior, electrically-conductive surface areas of can
bodies is shown in TABLE I wherein 2-piece drawn and 3-piece
regular can bodies (respectively 1-piece and 2-piece during the
coating operation), full and repair coated with aqueous
electrocoating mediums or baths at rates as fast as 2 seconds,
approximately 600 cans/per minute, obtained satisfactory quick
tests within the range of from 0 to 1.0 ma.
TABLE I
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BATH EQUIV. Solids Resisitivity TIME *** CANS QUICK TEST** EXAMPLES
TYPE-CAN TYPE Content (ohm/cm) T(.degree.F) VOLTAGE (seconds) MIN.
(milliamperes)
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Full Coating 1 2-piece A 10% 1,980 85.degree. 400 4 300 0-0.25
drawn aapprox. tinplate 2 do. do. do. do. do. 500 2 600 0.5-1.0
approx. Repair Coating 3 3-piece B 2.5% adjusted to 75.degree. -
200 3.5 380 0.57 TFS 4,800 80.degree. approx. Miraseam* 4 do. do.
2.0% adjusted to 80.degree. 100 2.0 600 0-0.4 5,500 approx. 5 do.
do. 2.1% adjusted to 80.degree. 100 2.5 520 0-6.0 4,400 approx.
__________________________________________________________________________
A and B -- Anodic aqueous electrocoating baths prepared by diluting
CS576 (for A) and X1222 (for B) (manufactured by Pittsburg Plate
Glass Co.) to the indicated percent solids solution, with ionized
water. CS576 and X122 are believed to be roughly 22 percent solids
concentrate solutions of butyl acrylate-styrene-methacrylic
acid-hydroxyethyl methacrylate and containing no more than 20 wt. %
of total polymer units derived from methacrylic and containing no
more than 7 wt. % of total polymer units derived from hydroxyethyl
methacrylate. * -- Having thereon an epoxy-type, solvent-containing
base coat designate H50,000, manufactured by M&T Chemicals Inc.
** -- A Quick Test (QT) determines the adequacy of film build-up
and the effectiveness of full and repair coat seals. A typical QT
is to pour an aqueous 1% sodium chloride solution into an
open-ended TFS can having its lap seam cemented with a polymeric
material (Miraseam can), its closed en sealed with a steel end and
its interior roller-coated with a layer of conventional lacquer. An
electrode is placed in the solution and a 6v. potential is induced
in the circuit. Current flowing through the circuit measured in ma,
determines effectiveness of the repair coat. Perfect coverage is
obtained when no current flows. *** -- The time in seconds is
deposition time while contacts 254 engage cam bars 228 and 228'.
However, times listed are approx. since some deposition takes place
before and after the contacts engage the cam bars.
The resistivity of the baths used for full coating the tinplate
bodies was unadjusted, whereas that for the TFS bodies was adjusted
by contacting the unadjusted bath with a weak electrolyte, CO.sub.2
in the manner disclosed in U.S. Pat. application Ser. No. 209,305
filed on Dec. 14, 1971. The method disclosed in the aforementioned
application can advantageously be employed in relation to the
electrocoating system of this invention.
In the electrical coating circuitry of this invention, wire 114
(FIG. 10) is connected to the positive terminal of the power source
(not shown), and is ultimately connected through the cam bars,
contacts and valves to electrodes 48, thereby rendering them
cathodic. Wire 75 (FIG. 1) is connected to the negative terminal of
the power source and is ultimately connected through the brushes
and the cables to container bodies 44 and 44', thereby rendering
them anodic. When, as shown in TABLE I, an anodic electrolytic
fluid or bath such as X1222 fills the container bodies 44, and the
contacts engage the cam bars, negatively charged electrolytic
coating particles in the bath migrate to, discharge onto and coat
any positively charged interior conductive surfaces of the anodic
container bodies.
It has been found highly desirable to isolate, and the embodiment
of this invention essentially isolates, the interior surfaces of
metal drum 12 from the aforementioned coating circuit.
This prevents electrolytic particles in fluid 84 from being
electrodeposited on any such surfaces exposed to the fluid, and it
prevents power loss from the power source through the exposures, to
drum 12 which preferably is grounded.
Although electrolytic particles from electrocoating fluids would
tend to increasingly insulate the exposed area as it coated the
area, some recently developed fluids would not so readily coat the
area and therefore would allow power loss.
The coating used to insulate the interior of drum 12 can be any
coating or coatings suitable for insulating the drum. The type of
coating will vary depending on the type of material used to make
the drum. For the stainless steel drum of this invention, it has
been found advantageous to condition the interior surface as by
sand blasting, and to treat the surface with a 0.3 to 1 mil thick
layer of a material such as an alcoholic solution, e.g., a
"Polyclutch" Wash-Primer preparable by those skilled in the art
according to MIL Specification MIL-C-15328, designated UC-40082, by
PPG Industries, Inc. A conventional, commercially available
material such as a two component system, polyamide-cured, heavy
duty coal tar epoxy sold under the trade designation UC40101 by PPG
Industries, Inc. can be applied over the primed surface in thick
layers of say about 6 mils each.
Of course, when drum 12 is not made of a conductive metal but is
made of say a molded, cured glass filament epoxy material, the
aforementioned coatings would not be employed.
* * * * *