Apparatus for electropolishing surfaces

An apparatus for electropolishing surfaces includes an inner housing having an open side with a rim facing toward a surface to be electropolished and being otherwise closed. A guide apparatus moves the inner housing along the surface to be electropolished. An inner seal is disposed between the rim of the inner housing and the surface to be electropolished. An electrode is retained in the inner housing. An outer housing has an interior in which the inner housing and the electrode are disposed. The outer housing has an open side with a rim facing toward the surface to be electropolished and is otherwise closed. An outer seal is disposed on the rim of the outer housing. Connections are associated with the outer housing for supplying and removing a rinsing fluid to and from the inner housing. Ducts are associated with the outer housing for supplying and removing electrolyte fluid to and from the inner housing. Auxiliary devices are connected to the connections and the ducts for supplying rinsing fluid and electrolyte fluid.

The invention relates to an apparatus for electropolishing surfaces, 
including a housing being movable along a surface to be electropolished by 
means of a guide apparatus and being closed on all sides except for a side 
oriented toward the surface to be electropolished, a seal disposed between 
a rim of the housing and the surface to be electropolished, an electrode 
retained in the housing, and auxiliary devices attached to the housing for 
supplying current and supplying electrolyte fluid. 
It is known from German Published, Non-Prosecuted Application DE 33 45 278 
Al, corresponding to U.S. Pat. No. 4,634,511, to decontaminate metal 
surfaces of nuclear engineering facilities by means of electropolishing. 
In that apparatus, a sponge electrode, which is retained on a carriage 
supported on an inner surface of a hollow cylindrical body, is pressed 
against the inside surface and moved along the surface with the carriage. 
That apparatus makes quite economical use of the electrolyte, because the 
electrode is built into a housing that is closed on all sides except for 
the side on which the electrode rests on the surface to be 
electropolished. 
Electrolyte fluid dripping from the electrode into the housing, which rests 
with encompassing sealing lips on the surface to be electropolished, is 
removed by suction and pumped back into an electrolyte supply tank. With 
that apparatus, good decontamination of tubes and inner surfaces of 
containers, vessels or tanks has been feasible. Although the spongelike 
electrode is enclosed by a housing that is open only toward the surface to 
be decontaminated and can be brought into contact with the surface to be 
decontaminated by means of a seal, small quantities of electrolyte fluid 
still remain on the already decontaminated portions of the surface when 
the housing is displaced. Such electrolyte residues on the decontaminated 
portions of the surface are a problem when the decontaminated portions of 
the system are put back into operation. Accordingly, the residues must be 
removed beforehand by extensive rinsing procedures. 
It is accordingly an object of the invention to provide an apparatus for 
electropolishing surfaces, which overcomes the hereinafore-mentioned 
disadvantages of the heretofore-known devices of this general type and to 
do so in such a way that as far as possible no electrolyte residues remain 
on the decontaminated portions of the surface, or the quantities of such 
residues are markedly reduced. 
With the foregoing and other objects in view there is provided, in 
accordance with the invention, an apparatus for electropolishing surfaces, 
comprising an inner housing being closed on all sides except for an open 
side with a rim facing toward a surface to be electropolished; a guide 
apparatus for moving the inner housing along the surface to be 
electropolished; an inner seal disposed between the rim of the inner 
housing and the surface to be electropolished; an electrode retained in 
the inner housing; an outer housing having an interior in which the inner 
housing and the electrode are disposed, the outer housing being closed on 
all sides except for an open side with a rim facing toward the surface to 
be electropolished; an outer seal disposed on the rim of the outer 
housing; connections associated with the outer housing for supplying and 
removing a rinsing fluid to and from the outer housing; ducts associated 
with the outer housing for supplying and removing electrolyte fluid to and 
from the inner housing; and auxiliary devices attached to the inner 
housing for supplying rinsing fluid and electrolyte fluid. 
Since the inner housing along with the electrode is built into the interior 
of an outer housing that is closed on all sides except for the side 
oriented toward the surface to be electropolished, and the outer housing 
has a seal on its rim and is provided both with connections for supplying 
and removing a rinsing fluid and with ducts for supplying and removing 
electrolyte fluid to and from the inner housing, it becomes possible for 
the electrolyte residues remaining on the electropolished surface upon 
electropolishing and displacement of the two housings to be diluted and 
rinsed away between the two housings with rinsing fluid. At the same time, 
precleaning of the portions of the surface to be electropolished is 
subsequently also attained. 
In accordance with another feature of the invention, there are provided 
means for supporting the inner housing for displacement relative to the 
outer housing perpendicularly to the open sides of both of the housings. 
Adaptation to various radii of curvature of container walls and pipelines 
is made easier in this way. In this case, if the curvature of the wall 
along with the inner housing is major, the sponge electrode can be 
displaced farther toward the surface to be electropolished and brought 
into better contact therewith. The flexible housing seal takes on the task 
of compensation between the straight housing edge and the curvature of the 
container wall. Thus even with curved surfaces, the danger of leakage at 
the seals can be diminished. 
In accordance with a further feature of the invention, there are provided 
means for supporting the electrode in the interior of the inner housing 
for displacement perpendicularly to the open side of the inner housing. 
This makes it easier to keep the contact pressure of the electrode 
virtually constant, despite varying curvatures of the surface to be 
electropolished. 
In accordance with an added feature of the invention, the rinsing fluid is 
deionized water. Electrolyte contamination of electropolished portions of 
the surface can be minimized in nuclear engineering facilities if 
deionized water is used as the rinsing fluid. In this case, the rinsing 
fluid or deionized water residues that remain on the electropolished 
surface are readily miscible with the deionized water that is already 
usually used in the operation of such systems, rendering further treatment 
or rinsing of the surface unnecessary. 
In accordance with an additional feature of the invention, the rims of the 
inner and outer housings are spaced apart defining a gap therebetween, the 
connections include a rinsing fluid supply line, and there is provided a 
ring line connected to the rinsing fluid supply line and secured to the 
outer housing between the inner and outer housings, the ring line having 
spray nozzles being secured on the outer housing between the outer and 
inner housings and being aimed at the gap. Particularly small amounts of 
electrolyte residue ensue if such a structure is used. In this case, the 
electrolyte residues are flushed out of the surface by the injection 
pressure of the rinsing fluid and diluted and removed by suction along 
with the rinsing fluid. 
In accordance with yet another feature of the invention, the rims of the 
inner and outer housings are spaced apart defining a gap therebetween, and 
there are provided brushes rotating or oscillating and rubbing the surface 
to be electropolished in the gap. 
In accordance with yet a further feature of the invention, the electrode is 
a sponge electrode. 
In accordance with yet an added feature of the invention, the seals are 
high-flexibility lip seals. 
In accordance with yet an additional feature of the invention, the guide 
apparatus includes a central main mast with a lower end, a manipulator arm 
being pivotably supported on the lower end and having an outer end, the 
outer housing being displaceable on the outer end in the longitudinal 
direction of the manipulator arm, and the outer housing together with the 
manipulator arm being rotatably supported about an axis of symmetry of a 
container having the inner surface to be electropolished. 
In accordance with again another feature of the invention, there is 
provided a turntable for rotating the central main mast about a vertical 
axis. 
In accordance with a concomitant feature of the invention, the auxiliary 
devices include supply tanks for the electrolyte fluid and the rinsing 
fluid and associated feed pumps being disposed on the lower end of the 
main mast. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claims. 
Although the invention is illustrated and described herein as embodied in 
an apparatus for electropolishing surfaces, it is nevertheless not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made therein without departing from the 
spirit of the invention and within the scope and range of equivalents of 
the claims.

Referring now to the figures of the drawings in detail and first, 
particularly, to FIG. 1 thereof, there is seen a sectional view of a 
container, vessel or tank 2 to be decontaminated, and a working platform 4 
having a central opening 6 and being mounted on the container 2. A 
turntable 12 is supported through the opening 6 and is rotatable with 
rollers 8, 9 (only two of which are shown) on the working platform 4 about 
an axis of symmetry 10 of the container 2. A central main mast 14 is 
guided on the turntable 12 in such a way that it is displaceable 
perpendicularly to the plane of the platform. The vertical displacement of 
the main mast 14 is effected through a vertical drive mechanism 16 which 
is diagrammatically illustrated in the drawing, by means of a pinion 20 
that meshes with a rack 18 of the main mast. The rotation of the main mast 
14 about the axis of symmetry 10 of the container 2 is effected by a 
horizontal drive mechanism 22 that is secured to the rim of the turntable 
12, by means of a pinion 24 that meshes with a gear ring 26 of the working 
platform 4. A manipulator arm 28 is pivotably supported about a horizontal 
shaft 30 on the lower end of the main mast 14. The pivoted position of the 
manipulator arm is adjusted through a cable drive mechanism 32. An outer 
housing 34 of the apparatus for electropolishing surfaces is secured on 
the manipulator arm 28 to a support arm 36 that is longitudinally 
displaceable on the manipulator arm 28. A deionized water tank 38, an 
electrolyte tank 40, and a respective circulating pump 41, 42 for each of 
the deionized water and electrolyte fluid are secured to the lower end of 
the central main mast 14. Television cameras 44, 45 and a lighting fixture 
46 are secured to the lower surface of the working platform 4 and to the 
lower end of the main mast 14. 
In the view shown in FIG. 2, which is on a larger scale than FIG. 1, the 
outer housing 34 that is retained by means of the support arm 36 on the 
manipulator arm 28, can be seen along with all of its built-in fixtures. 
The outer housing 34 has a cylindrical outline and is closed on all sides, 
except for the side opposite the support arm 36. The rim on the open side 
of the outer housing 34 has a seal 50 facing a surface 48 of the container 
2 to be electropolished A die or plunger 54 is longitudinally displaceably 
supported along the axis of symmetry 52 of the support arm 36, all the way 
through both the support arm 36 and the outer housing 34. A sponge 
electrode 56 is supported by means of a ball joint 58 on the forward end 
of the die 54, in such a way as to be pivotable in two dimensions. A 
somewhat smaller inner housing 60 is longitudinally displaceably supported 
on the die 54 between the sponge electrode 56 and the outer housing 34. 
This inner housing 60 is likewise closed on all sides, except for a side 
facing the surface to be electropolished. In the exemplary embodiment, the 
cross section of the housing 60 is again cylindrical, and it is supported 
with an extensively pierced annular bead 61 on the inner wall surface of 
the outer housing 34. An encompassing seal 62 is likewise attached to the 
rim of the inner housing 60 and can be made to engage the surface 48 to be 
electropolished. The inner housing 60 as well as the die 54 and the sponge 
electrode 56 are pressed out of the outer housing 34 toward the surface 48 
to be electropolished, through the use of a spring 64 which is drawn or 
folded over the die 54. The spring 64 is supported at one end on the inner 
housing 60 and at the other on the outer housing 34. A further spring 68 
is fastened between the outer housing 34 and the manipulator arm 28 and 
presses the outer housing 34 away from the manipulator arm. 
As can be seen in FIG. 1, the die 54 is at the same time a piston rod of a 
hydraulic cylinder 70 which is built into the interior of the manipulator 
arm 28. The die 54 can thus be extended into the manipulator arm 28 or 
retracted from it again counter to the force of the springs 64, 68. A disk 
66 which is secured to the die 54 strikes the inner housing 60 and 
transmits the backward motion of the die 54 to both housings 34, 60. The 
support arm 36, which firmly welded to the outer housing 34, is in turn 
longitudinally displaceably moved by the manipulator arm 28. An adjustment 
path of the support arm 36 on the manipulator arm 28 is defined by a 
contact pin 74 of the support arm that plunges into a longitudinal groove 
72 in the manipulator arm. 
A sponge 76 of the sponge electrode 56 is connected to the electrolyte 
circulating pump 42 through two pipelines 78, 79, which pass through the 
rear wall of both the inner and outer housings to deliver electrolyte 
fluid. The inner housing also communicates with the electrolyte tank 40 
through at least one pipeline 80, 81 which pass through the rear wall of 
the outer housing 34 for the removal of electrolyte fluid by suction. The 
outer housing 34 has a ring line 82 on the inside thereof, which has spray 
nozzles 84, 85 aimed at the electropolishing surface 48. The ring line 82 
is connected to the rinsing fluid pump 41 through a rinsing fluid supply 
line 86. The outer housing 34 is also connected to a suction removal line 
88 for rinsing fluid This suction removal line 88 discharges into the 
rinsing fluid tank 38, which in the exemplary embodiment is filled with 
deionized water. 
For instance, in order to electropolish the inner wall surface 48 of the 
container 2 with this apparatus, first the central main mast 14 is lowered 
to the desired height by means of the vertical drive mechanism 16, and 
then the manipulator arm 28 is pivoted by the cable drive mechanism 32 
into the working position, or in other words into the horizontal position 
in the exemplary embodiment. In this position, the sponge electrode 56, 
the inner housing 60 and the outer housing 34 can be pressed by the 
springs 64, 68 against the surface to be electropolished, or in other 
words, in this exemplary embodiment, against the inner wall surface 48 of 
the container 2, by expansion of the hydraulic cylinder 70. In this 
process the seal 50 of the outer housing 34 is pressed against the 
container wall by the spring 68 which is supported on the outer housing 
and on the manipulator arm 28. The seal 62 of the inner housing 60 is 
pressed against the container wall 48 by the spring 64 which is fastened 
between the inner housing and the outer housing In this position of the 
two housings, the hydraulic cylinder 70 can additionally press the die 54 
and the sponge electrode 56 against the container wall to be polished. 
Once the apparatus has thus been placed in the working position, the sponge 
electrode 56 can be supplied with electrolyte fluid through the pipelines 
78, 79 and the electrolyte circulating pump 42. The excess electrolyte is 
removed by suction back into the electrolyte tank from the inner housing 
60 through the suction removal lines 80, 81. Additionally, the circulating 
pump 41 forces rinsing fluid, which is deionized water in the exemplary 
embodiment, out of the deionized water container 38 into the ring line 82 
and through the spray nozzles 84, 85 (only two of which are shown). The 
deionized water collecting in the outer tank is removed by suction back 
into the rinsing fluid tank 38 through the suction removal line 88. Upon 
closure of the housing through the surface of the container, a superficial 
removal of material from the container wall then takes place when the 
current is switched on The particles that are removed are sponged away by 
the electrolyte fluid and are removed with it by suction into the 
electrolyte tank 40 through the pipelines 80, 81. They can be filtered out 
in a non-illustrated manner through an interposed filter device. The 
electropolished regions of the container wall, which come into view under 
the seal or sealing lip 62 of the inner housing 60 when the housings are 
displaced, are moistened with slight quantities of electrolyte fluid. 
These residues of electrolyte fluid are rinsed away between the inner and 
outer housings by the rinsing fluid that is sprayed with increased 
pressure at the container wall from the spray nozzles 84, 85, so that once 
these electropolished, decontaminated portions of the surface come into 
view at the seal 50 of the outer housing 34, they are substantially no 
longer moistened with anything but rinsing fluid, which in the present 
case is deionized water. 
The removed deionized water can be selectively replaced with fresh 
deionized water, or the removed deionized water can be prepared upstream 
of the return line leading into the rinsing fluid tank in a 
non-illustrated manner. It is also conceivable to install rotating brushes 
between the inner and outer housings, which brush the surface to be 
electropolished. This mechanically wipes away electrolyte residues and 
residues of removed material remaining on the surface. Instead of using 
spray nozzles, the outer housing 34 can also be fully flooded with 
deionized water. It is also possible to keep the pressure in the outer 
housing 34 somewhat above the pressure of the inner housing 60, thereby 
effectively preventing the electrolyte from escaping from the inner 
housing. At the same time, this pressure difference can provide for a 
stronger pressure of the seals or lip seals against the surfaces they 
contact. This also applies to the inner seal or lip seal 62, if it is made 
with an inner and an outer lip, in a manner similar to the way in which 
the outer lip seal 50 is constructed, in a deviation from the exemplary 
embodiment. 
This apparatus effectively prevents electrolyte fluid from escaping through 
the seal 62 of the inner housing 60 and through the seal 50 of the outer 
housing 34. A great advantage of this apparatus is that not only are any 
electrolyte residues still-adhering after electropolishing sponged away, 
but precleaning of the region that is to be subsequently electropolished 
is also attainable upon displacement of the apparatus over the surface to 
be electropolished. Due to its structure, this electropolishing apparatus 
also enables work to be performed under water. This option of working 
under water is also highly advantageous, particularly in nuclear 
engineering facilities, because the radiation load in the surroundings can 
be reduced effectively in this way. Finally, the progress of the work can 
be monitored continuously through the use of the television cameras 44, 45 
that are secured under the working platform 4 and on the lower end of the 
main mast 14.