FIELD OF INVENTION:
The invention relates to themanufacturing of the water wall panels
of the steam generators which has a long cycle time due to the
defects and reworks arising due to the oxidation of the flat fins that
are used in between the boiler water wall tubes for increasing the
heat transfer area inside the steam generator.Therefore, for the
reduction of the defect rate and rework, an effective method for
cleaning the flat fins is required. The present invention particularly
relates to a low cost and highly energy efficient cleaning of the fin
plates before being welded together in the Panel Processing
Machine.
BACKGROUND OF THE INVENTION:
The water wall panels used in the steam generators are made in
the Panel Processing Machines which is an automatic welding
machine. The water wall panels consist of boiler grade steel tubes
welded together by boiler grade flat fins that are fed into the
machine simultaneously for forming by welding. The quality of the
welding depends mainly on the quality of the surface being welded
together i.e. the tube and the flat fin surfaces. Thus in order to
achieve the required surface quality, the fin is to be cleaned
effectively and made free from rust and foreign matter.
Shot blasting being the most common method of cleaning the
surface is highly energy consuming process which utilizes huge
amount of compressed air to pressurize the chamber containing
the shots. Then a separate air stream is required to move the shots
and impinge on the surface to be cleaned. Then after a vacuum
mechanism containing a blower is required for removing the
harmful dust generated inside the blasting chamber. Hence this
conventional method is very cumbersome process and requires a
lot of floor space which might be an issue in some cases.

Therefore, due to the above constraints, a high energy efficient and
compact system has been developed that is very functional in
cleaning the rusted fins for achieving a defect free welding in the
Panel Processing Machines during forming of water wall panels by
welding together the boiler tubes with the flat fins.
OBJECTIVE OF THE INVENTION:
It is therefore the objective of the present invention is to provide an
automatic device for removing and cleaning rust and grease on the
flat fins that are fed into the Panel Processing Machine
continuously during the forming of water wall panels by welding
together the boiler tubes with the flat fins.
Another objective of the invention is to ensure thelinkingof the rust
removal operation with cleaning and welding operation in the panel
processing machine.
A further objective of the invention is to reduce the welding defects
arising due to the use of rusted flat fins in the panel processing
machine.
SUMMARY OF THE INVENTION:
This invention exploits the method of continuous mechanical
cleaning of rust and grease by buffing on the flat fins used in the
water wall panels of the steam generators before being fed into the
Panel Processing Machine. This is achieved by the abrasive
cleaning using the buffing wheel arrangement on all the sides of
the flat fin to be welded where a total of 04 buffing wheels are
used. The buffing wheels are actuated pneumatically with the help
of pneumatic grinding machine. The air supply to these grinding
machines are fed from a common header so that there is even
distribution of air to all the four machines for even cleaning. The
automatic start / stop of the cleaning according to the machine

welding operation is achieved via a pneumatic solenoid valve which
energizes according to the fin start / stop. This prevents the fin
from getting damaged during removal of rust material by the
buffing wheel if prolonged on a specific point. Hence the rust and
oxides on the flat fins are cleaned before being fed into the Panel
Processing Machine for a defect free welding joint.
BRIEF DESCRIPTION OF THE DRAWINGS:
The present invention is now described herein below with reference
to the accompanying drawings, wherein,
Fig 1 shows the arrangement of the device used for automatic rust
and grease cleaning on a flat fin.
Fig 2 shows the compressed air distribution system for the
grinding machine.
Fig 3 shows the automatic start / stop mechanism of the
compressed air supply system.
Fig 4 shows the circuit diagram of the invented apparatus for
automatic rust cleaning on flat fins before being fed into the
Panel Processing Machine.
DETAILED DESCRIPTION OF THE INVENTION:
Fig 1 illustrates the working principle of this invention i.e. the
continuous abrasive cleaning of the rusted flat fins using
pneumatic grinding machine (1) and buffing wheel (5)arrangement.
The grinding machine (1), held rigidly with a c-clamp (4), is
mounted on a set of upper plate (9) and lower plate (10) clamped
together with the help of an expansion spring (12) and fasteners (2)
& (3). This set up is mounted on an angle (7) that is fixed to the fin
calibration machine (11) for support. As the compressed air is fed
into the hose (8) the grinder (1) gets energized, in turn actuating

the abrasive buffing wheel (5) in a set direction of the movement of
the rusted fin (6), thus cleaning the rust and grease as shown in
the fig. The continuous process of cleaning leads to the erosion of
the buffing wheels (5) which isfurther tightened by the expansion
springs (12) so that the cleaning is effective for entire life of the
wheel. The same arrangement is available on all the sides of the
flat fin.
Fig 2 illustrates the compressed air distribution system for the
grinding machine (1). It consists of an air header (13) receiving
compressed air via air hose (19). This hose (19) is fixed over a
nipple (17) with the help of a worm clip (18). The header (13) have
04 nos of outlets (14), distributing compressed air via one touch
hoses (15), one for each grinder (1). This arrangement is mounted
on a common plate (16) that is fixed to the calibration machine (11)
for support. The electrical feedback from the control panel
controlling the movement of fins, is given to the solenoid (21) (fig 3)
so as to open the valve (20) and pass the compressed air to the
grinding machine (1) which rotates the buffing wheel (5). Thus the
buffing wheel (5) operates only when the fins (6) moves. This is the
salient feature in this invention. This is done to avoid damage to
the fins (6) due to excess material removal at a particular point on
the fins and also to avoid wasting of the precious compressed air.
Fig 3 illustrates the arrangement of automatic start / stop
mechanism of the compressed air supply system. The pneumatic
valve (20) is energized by the electrical solenoid (21) which receives
the electrical signal via the connector (24) and cable (25). The valve
(20) receives air via hose (22) and discharges air via hose (23) as
and when the solenoid (21) is energized. This setup if fixed on an
angle (26) for support. Flat fin (6) are moved using an electrically
driven flat fin pull conveyor which is present in the machine itself.

This operation is not related to the pneumatic valve (20) and
electric solenoid (21). This pneumatic valve (20) and solenoid (21)
is used to operate the grinding machine (1) and buffing wheel (5),
which is synchronized with the movement of the fin (6).
Fig 4 illustrates the circuit diagram of the invented apparatus for
automatic rust cleaning on flat fins (6) before being fed into the
Panel Processing Machine (29). The fins (6), in the form of coils (27)
are fed into the fin calibration machine (28). Then after the fin (6)
enters the rust cleaning area consisting of 04 pneumatic grinders
(1) and then fed into the Panel Processing Machine (29).
Compressed air from the main header (32) enters the solenoid
valve (31) and then the common header (30) before energizing the
grinders (1). Only when the flat fin (6) moves, the buffing takes
place and removes the rust and small amount of grease/oil present
on the flat fins due to storing in open area. All 04 nos of buffing
wheels (5) are used on single fin (6) i.e. on all the four corners of
the fin (6) to clean the surface of the fin up to a distance of 10 mm
from the edge of the fin (6). It is to be noted that complete top and
bottom surface of the flat fin (6) need not be buffed. Similarly, the
two outside surfaces need not be buffed. Only the portion where
welding is carried out i.e. the corners surfaces up to a distance of
10 mm from the edge needs to be buffed and cleaned from any
foreign matter.

We Claim
1. A device for automatic rust removal of fin plates prior to
feeding to the panel processing machine, comprising;
• an arrangement of pneumatic grinding machine (1) with a
buffing wheel (5);
• the grinding machine (1) held rigidly with a c-clamp (4) on a
set of upper plate (9) and lower plate (10) with the help of an
expansion spring (12) and fasteners (2,3) and mounted on an
angle (7), the said angle (7) being fixed to a fin calibration
machine (11) for support;
• the grinding machine (1) connected with a hose (8) for supply
of compressed air for running the buffing wheel (5);
• a compressed air distribution system consisting of air feeder
(13) and air hoses (15) & (19) disposed for uniform supply of
compressed air to each hose connection (8) of the grinding
machine (1);
• an arrangement of automatic start / stop mechanism of
compressed air supply system consisting of pneumatic valve
(20) energized by electrical solenoid which receives electrical
signal via connector (24) and cable (25) from the panel
processing machine.