FIELD OF THE INVENTION:
The present invention relates to an improved device adaptable to silver
plating in current carrying hole of slip ring shaft to increase electrical
conductivity.
BACKGROUND OF THE INVENTION:
Slip ring shaft is mounted between the exciter shaft and general shaft.
Slip rings are two rings used for conveying current from exciter to
general rotor poles.
Each part of the slip ring is provided two M82 holes on periphery radially
opposite to each other up to a depth of dia 40 mm. Further, these holes
are extended up to the full thickness by dia 38 holes for fitting of current
carrying hole.
The M82 holes are silver plated to increase electrical conductivity. While
carrying out silver plating, a device is used which holds anode at the
centre and inlet and outlet connections for supply of solution. Slip ring
acts cathode during electroplating operation. Before silver plating, the
slip ring is subjected to degreasing for cleaning up thread part followed

by copper plating up to the thickness of 5 micron and finally silver
plating is done to achieve 15 micron thickness of plating followed by
water flow to clean the traces of the solution if present in the holes.
The problems existing in the present system of silver plating are:-
1. The present plug like device when fitted in M82 holes covers the
entire length of the threaded portion of the hole which needs
electroplating.
2. The present device is incapable to serve the purpose of
electroplating M82 holes in slip ring.
In order to overcome the existing problem, the inventors propose an
improved device for slip ring holes for successful silver plating and with
a pair of such improved devices, when placed on the two M82 holes of
the slip ring disposed diagonally opposite side, simultaneously silver
plating takes place.
OBJECTS OF THE INVENTION:
It is therefore an object of the present invention to propose an
improved silver plating device adaptable for silver plating on current
carrying hole of slip ring shaft which eliminates the disadvantages of

the existing state of Art.
Another object of the present invention is to propose an improved silver
plating device which makes perfect plating only on threaded part of
current carrying holes.
A further object of the present invention is to propose an improved
silver plating device which increases productivity.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
Fig. 1 shows a schematic isometric view of the invented device.
Fig. 2 shows a sectional isometric view of Fig. 1.
Fig. 3 shows a schematic diagram showing a pair of devices acting on
two sides of a slip ring.
Fig. 4 shows a schematic diagram showing a pair of devices acting on
two sets of slip ring on the same side.
BRIEF DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION:
As shown in Fig. 1, the silver plating device comprises a box (1) shape
structure having a radial shaped surface at proximate end (2) to match
with the outer circumference of slip ring when placed on it. The box (1)

Is made from 140 X 140 X 120 mm piece of polypropylene. It is provided
with one interior hole of diameter Ml4 at the centre (3) for holding an
anode (4) (as shown in Fig. 2). The box is provided with another two
interior holes (5, 6) of diameter Ml 2 radially opposite at a distance of 60
mm from the centre for holding inlet and outlet nipples (9, 10). Bottom
surface of the device (2) is machined to the radius equal to that of slip
ring for providing proper sitting of the black on the curved surface of
the slip ring. The device is also provided two interior holes (7, 8) of
diameter 8 mm at both distal end for bolting the device with slip ring.
The device is provided with an inlet nipple (9) for ingress of liquid silver
solution and an outlet nipple (10) for exit of liquid silver solution disposed
at holes (5, 6). These nipples (9, 10) are bent tubes of size diameter 13.5
mm. The first end of the nipple is fitted on the device and the second
end of the nipple is connected with a flexible pipe for supply and
discharge of the solution.
METHOD OF WORKING THE SILVER PLATING DEVICE:
- plugging the centre hole of 38 mm diameter (11) of slip ring
(Fig. 4);
- degreasing the current carrying hole of 82 mm diameter (12)
of slip ring (Fig. 4);

fitting of a pair (A & B) of device on the two holes (82 mm
dia) in the same side of the slip two rings (Fig. 4);
fitting a rubber packing in between the device and slip ring
to ensure a leak proof joint between the device and the slip
ring during fluid flow;
connecting inlet nipple (13) of the device (A) with the
solution tank by means of a flexible pipe (Fig. 4);
connecting the outlet nipple (15) of the device (A) with the
inlet nipple (14) of the device B;
returning back the solution from the outlet nipple (16) of
device B to the tank;
connecting anodes (A4) of device (A) and (B4) of device (B)
with a wire;
connecting cathode (17, 18) of the slip ring (A) and slip ring B
with a wire;
flowing silver solution from tank to 1st inlet (13) device (A) and
fills the cavity of current carrying holes (12) and the excess

solution exits from the 1st outlet (15) of device A and passes
on to the 2nd inlet (14) of device (B) and fills the cavity (17) of
the current carrying hole of slip ring B and excess solution
exits from the 2nd outlet (16) of device (B) and return back to
solution tank (Fig. 4);
connecting anodes and cathodes to the supply line and
start silver plating on the exposed surface of the current
carrying holes containing silver solution.

WE CLAIM:
1. An improved silver plating device adaptable to silver plating in
current carrying hole of slip ring shaft comprising:
- a box shaped structure having a radial surface (2) at the
proximate end;
- the box is provided a plurality of interior holes disposed
intermittently along the central axial path out of which
(i) A plurality of holes (7, 8) disposed at two distal end of
the box engaged for mounting with the slip ring;
(ii) A centre hole (3) for fitting an anode (4);
(iii) A plurality of holes (5, 6) disposed on both sides of
the central hole engaged for flowing fluid via a
plurality of nipples with elbow bend (9, 10);
2. The device as claimed in claim 1 wherein the box is made of
polypropylene material.

3. The device as claimed in claim 1 wherein the size of the box is 140
mm X 140 mm X 120 mm.
4. The device as claimed in claim 1 wherein centre hole size of M4
for holding anode.
5. The device as claimed in claim 1 wherein the size of two holes of
dia Ml2 radially opposite at a distance of 60 mm from the centre
for flow of silver solution.
6. The device as claimed in claim 1 wherein the method of
functioning of the device comprising the following steps:
- plugging the centre hole of 38 mm diameter (11) of slip ring;
- degreasing the current carrying hole of 82 mm diameter (12)
of slip ring;
- fitting of a pair (A & B) of device on the two holes (82 mm
dia) in the same side of the slip two rings;
- fitting a rubber packing in between the device and slip ring
to ensure a leak proof joint between the device and the slip
ring during fluid flow;

- connecting inlet nipple (13) of the device (A) with the
solution tank by means of a flexible pipe;
- connecting the outlet nipple (15) of the device (A) with the
inlet nipple (14) of the device B;
- returning back the solution from the outlet nipple (16) of
device B to the tank;
- connecting anodes (A4) of device (A) and (B4) of device (B)
with a wire;
- connecting cathode (17, 18) of the slip ring (A) and slip ring B
with a wire;
- flowing silver solution from tank to 1st inlet (13) device (A) and
fills the cavity of current carrying holes (12) and the excess
solution exits from the 1st outlet (15) of device A and passes
on to the 2nd inlet (14) of device (B) and fills the cavity (17) of
the current carrying hole of slip ring B and excess solution
exits from the 2nd outlet (16) of device (B) and return back to
solution tank;

- connecting anodes and cathodes to the supply line and
start silver plating on the exposed surface of the current
carrying holes containing silver solution.
7. The device as claimed in claim 1 wherein a rubber packing of
150 X 110 X 5 mm is placed in between the adopter and slip ring
to ensure a leak proof joint between the device and slip ring
during fluid flow.
8. The device as claimed in claim 1 wherein the nipples are bend
tubes of size dia 13.5 mm, one end is fitted on the device and the
other end is connected with flexible pipe for supply and discharge
of the solution.
9. The device as claimed in claim 1 wherein the thickness of silver
plate deposits is 15 micron.

ABSTRACT

An improved silver plating device adaptable to silver plating in current
carrying hole of slip ring shaft comprising a box shaped structure having
a radial surface (2) at the proximate end and the box is provided a
plurality of interior holes disposed intermittently along the central axial
path out of which a plurality of holes (7, 8) disposed at two distal end of
the box engaged for mounting with the slip ring, a centre hole (3) for
fitting an anode (4) and a plurality of holes (5, 6) disposed on both sides
of the central hole engaged for flowing fluid via a plurality of nipples
with elbow bend (9, 10).