FIELD OF THE INVENTION
The invention relates to an improved process of restoring dimensional deviations
for Baking wagon used for manufacture of HV Insulation on stator bars for Turbo
generators.
BACKGROUND OF THE INVENTION
In manufacturing process for High Voltage Insulation on TG stator bars, a Baking
wagon (Figure 1) is used for pressing of Impregnated Stator bars of Turbo
Generators (TG). Impregnated Stator bars are pressed with the tooling of the
baking wagon in channels (1) of the wagon and then cured in a oven. Width of
the channels including the dimensions of its tooling determines the dimensions of
cured stator bars. During continuous use, smoothness of the channel surfaces
exceeds the tolerance limit. The known process of rectification of the wagons
exhibit a substantial increase in channel width which consequently increases the
desired height and width of the impregnated stator bars. Prior art solution to this
disadvantages has been to replace the baking wagon periodically leading to
increase in production cost.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved process for
restoring dimensional deviations of a Baking wagon used for manufacture of HV
Insulation on stator bars for Turbo generators.
Another object of the invention is to propose an improved process for restoring
dimensional deviations of a Baking wagon used for manufacture of HV Insulation
on stator bars for Turbo generators which is economic and increases production
of stator bars.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved process of restoring dimensional
deviations for Baking wagon used for manufacture of HV Insulation on stator
bars for Turbo generators, the baking wagon comprising three identical
channels, parallely disposed and having associated tooling in the form of a side
plank (2), an upper plank (4), a pressing plate (5) and a pressing rule assembly,
the baking wagon enabling pressing of impregnated stator bars (3) into said
channels by using the toolings the process comprising the steps of reducing the
height of a middle piece (7) of the pressing rule assembly with predetermined

width, the pressing rule assembly further having right and left pieces (6, 8);
increasing the width of the pressing plate (5) corresponding to the magnitude of
decrease in the height of the middle piece (7), wherein the reduction in the
height of the middle piece (5) is selected to compensate the increase in width of
the baking wagon's channel developed due to long use.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows a baking wagon having at least three channels parallel to each
other, the impregnated stator bars (dipped in hot resin-hardener mixture) being
pressed by a hydraulic pressing device on the baking wagon.
Figure 2 shows a cross sectional view of a single channel, all three channels
including their tooling being identical, only a single channel is illustrated.
Figure 3 shows a cross sectional view of a stator bar (3) pressed with the tooling
i.e. a side plane (2), an upper plank (4), pressing rule assembly (6, 7, 8) and a
pressing plate (5).
Figure 4 shows a channel of a rejected wagon developed with an increased width
(9) of the channel.

Figure 5 shows the press rule assembly having left side part (6), a middle part
(7) and a right side part (8).
Figure 6 shows the working of the pressing rule assembly having a
predetermined width controlled by pressing of the middle part in downward
direction.
Figure 7 shows a wagon channel in which, an increased width is compensated
with the pressing rule assembly.
DETAIL DESCRIPTION OF THE INVENTION
In order to overcome the prior art disadvantages, the inventors initially
conducted an analysis of channel width of the baking wagons which developed
deviations of long use in respect of dimensions and noted the observations in
Table No-01.


To ensure the height of the impregnated stator bars with permissible limit the
increased width of channel of the baking wagon has to be compensated.
The possible solutions noted by the inventors for achieving the desired
dimensions of the stator bars are :-
1- Replacement of the defective baking wagon with a new one which is
costly and time consuming,
2- Designing new tooling to match the increased width of the channel of this
particular wagon, OR,
3- To develop a process through which, the existing cooling can be utilized to
save cost and time.
Solution Developed
The task is to develop a process to compensate the increased width of each
channel, which is possible by increasing width of any one of the tooling in
corresponding amount.
With careful analyzing of all the tooling, it was found by the inventors that a
Press Rule Assembly (Figure 5) is most suitable for this purpose.

Figure 6 shows the operation of the selected press rule assembly. As the middle
part (7) is pressed downward, both the side rules (6 and 7) are shifted
horizontally in opposite direction.
If the height of the middle part (7) is reduced, then it can be pressed further
more which correspondingly increases the total width of the assembly (figure 5).
The relationship between the reduction in height of the middle piece (7) and the
value of increase in the assembly width (Figure 6) can be derived mathematically
through dimensions of the assembly parts (6, 7 and 8).
Conclusion is, the height of the middle part (7) can be reduced up to such extent
so that the increased width of the press rule assembly equals the increased
width of channel of the baking wagon.
To compensate the reduced height of the middle piece, a pressing plate (5)
width is increased in same proportion.
Complete data (for a specific wagon used) are shown in Table No.-2


Figure 7 shows that height of the Middle part (7) has been reduced and the
height of the pressing plate (5) is increased.

WE CLAIM:
1. An improved process for restoring dimensional deviations of a Baking
wagon used for manufacture of HV Insulation on stator bars for Turbo
generators, the baking wagon comprising at least three identical channels
parallely disposed, and having associated toolings in the form of a side
plank (2), an upper plank (4), a pressing plate (5) and a pressing rule
assembly, the baking wagon enabling pressing of impregnated stator bars
(3) into said channels by using the toolings, the process comprising the
steps of:
- reducing the height of a middle piece (7) of the pressing rule assembly
width, the pressing rule assembly further having right and left pieces (6,
8);
- increasing the width of the pressing plate (5) corresponding to the
magnitude of decrease in the height of the middle piece (7),
wherein the reduction in the height of the middle piece (5)is selected to
compensate the increase in width of the baking wagon's channel developed
due to long use.

2. The process as claimed in claim 1, wherein decrease in the height of the
middle piece (7) and increase in the width of the pressing plate (5)
corresponds to the increase in width of channel through a mathematical
relationship of dimensions of assembly parts (6, 7 & 8).
3. The process as claimed in claim 1, wherein decrease in the height of the
middle piece (7) in the second and third channels of the baking wagon is
170% and 80% respectively compared to the width increase in said
channels.
4. The process as claimed in claim 1, wherein increase in the thickness of the
pressing plate (5) in the second and third channels of the baking wagon is
171% and 80% respectively relating to the width increase in said
channels.

ABSTRACT

The invention relates to an improved process for restoring dimensional deviations
of a Baking wagon used for manufacture of HV Insulation on stator bars for
Turbo generators, the baking wagon comprising at least three identical channels
parallely disposed, and having associated toolings in the form of a side plank (2),
an upper plank (4), a pressing plate (5) and a pressing rule assembly, the baking
wagon enabling pressing of impregnated stator bars (3) into said channels by
using the toolings, the process comprising the steps of: reducing the height of a
middle piece (7) of the pressing rule assembly width, the pressing rule assembly
further having right and left pieces (6, 8); increasing the width of the pressing
plate (5) corresponding to the magnitude of decrease in the height of the middle
piece (7), wherein the reduction in the height of the middle piece (5) is selected
to compensate the increase in width of the baking wagon's channel developed
due to long use.