FIELD OF INVENTION
The present invention relates to the development of an Automated Special
Purpose Machine for ironing of insulation of stator coils adaptable to electrical
motors.
BACKGROUND OF THE INVENTION
BHEL is venturing into the manufacturing of New range of electrical motors,
which requires coil insulation to be smoothened.
The New range of electrical motor coils are to be formed into diamond shape
(Refer Figure-1) and thereafter covered by insulated tape and varnished.
Subsequently, the same is covered by multiple layers of brown paper which is
required to be smoothened, for duration of 2 to 4 minutes, under constant
pre4ssure from heated platens at a temperature of around 80°C to 100°C.
In order to cater to the above job requirements, a stand alone automated
Special Purpose machine was proposed to be developed. The process was laid
out such that once the coil was loaded & clamped on the machine. The
desired rotation of the pressing heads, controlled electrical heating, set
pressure application, cycle stopping & positioning and platen disengagement
are to be done as programmed. The total cycle is to be controlled and
sequenced by a Programmable Logic Controller (PLC) and necessary program
selection/ modification are to be fed by a Man Machine Interface (MMI).

OBJECTS OF THE PRESENT INVENTION
It is therefore, an object of the present invention to propose an Automated
Machine for ironing of Insulation of stator coils adaptable to electrical motors
which eliminates the bottleneck for the manufacturing of New range of
electrical motors in the prior art.
Another object of the present invention is to propose an Automated Machine
for ironing of Insulation of stator coils adaptable to electrical motors which is
highly productive Machine which caters to the exponential increase in
production rates in the coming years and multiplying the same.
A further object of the present invention is to propose an Automated Machine
for ironing of Insulation of stator coils adaptable to electrical motors which
produces Machine at low cost & multiply the same, if required, to minimize
fixed asset overhead of the company & help boost bottom-line.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig-1- a schematic diagram of Diamond coil
Fig-2- a schematic diagram of Plan, Elevation and side view of Automatic
Machine for smoothening.
Fig-3- a schematic diagram of plan view of machine with Job
Fig-4- a schematic diagram of Rotary head Assembly.
Fig-5- Heating platen unit
Fig-6- Pneumatic circuit
Fig-7- Power Diagram
Fig-8- Pavel layout & PLC scheme
Fig-9- A photo view of ironing machine.

DETAILED DESCRIPTION OF INVENTION
According to the invention, there is developed a Special Purpose Machine for
Smoothening/ironing of stator coils of new range of electrical motors. The
machine has a fabricated bed with a pair of Rotating heads adjustable on the
same. Pair of Clamping units are also incorporated into the each rotating head
assembly. The diamond shaped coil is loaded & clamped onto the 3-axis
clamping units and the process is started. In the smoothening process the
electrically heated platens are actuated by a pair of diagonally opposite
clamping cylinders, press the coil and smoothening operation starts. The
rotating heads rotates to a pre determined no. of rotations & stops
automatically. The rotation of the heads is arranged by machine drive
assembly. Once the cycle stops, the coil is released by the heating platens by
the retraction of the pneumatic clamping cylinders and the coil is released
from the 3-axis clamping units. The sequencing of the various operations, no.
of cycles, platen heating and automatic control of the system is being
monitored by a control means having a Programmable Logic Controller. The
newly developed Ironing machine (Refer Figure-IX) is a properly integrated
self standing unit (Refer Figure-II) and broadly comprises the following
means/devices/arrangements/:
MACHINE BASE UNIT(Refer Figure-II):-
The machine base unit is the basic frame of the machine which provides for
the various mountings on the machine. It is a self standing rigid base
structure made out of various structural sections for an economically
acceptable working height of around 1000mm. Over the same is an integrated
fabricated bed with T-slots machined parallely over the same. The t-slots are
provided at the bed top, which acts as a guidance for the head assemblies.
The base unit is suitable for catering to the job lengths upto 1500 mm and
smoothening length upto 1200 mm. Further, it houses the pneumatic control

panel & the heating transformer & is grouted on the floor to provide stability
to the machine.
ROTATING HEAP ASSEMBLY(Refer Figure-IV):-
As the ironing operation is meant for smoothening of coil insulation, it
involves rotational pressing & heating of the fixed covered coils. These
operations are achieved by means of two nos. of rotary heads.
Each rotary head comprises of a rotary air drum unit, fabricated out of two
slotted machined hollow chambers & a spur gear, rotating on the ID o cast
iron housing (in two halves). Turcite lining has been provided on ID for
minimizing friction. The spur gear on the rotary drum receives drive from the
main drive unit through pinion & drive rods. Further, it receives electrical
input by means of NRV's provided on the drum periphery at 180°. The
electrical I/P is given by thyristorised controlled 6 KVA supply means and the
pneumatic I/P at the set pressure from 3 to 10 bar, from the compressor unit.
Each rotating drum acts as air accumulator and gives pneumatic I/P to the
four nos. of double guided special cylinders, which inturn manipulate &
provide pressing force to a pair of heating platens, which finally perform
ironing operation. The slip rings provided electrical I/P to the heating platens.
The signal line comprises of various sensing elements like limit switches,
proximity sensors, etc. provided for necessary feedback for controlling &
sequencing various activities by a Programmable Logic Controller (PLC). A 35
mm slot in the housing, air drum, slip rings & gear unit provides for
loading/unloading of the coils/platens.
MAIN DRIVE UNIT(Refer Figure-III):-
The main drive unit comprises of a flange mounted, Brake motor, a Speed
reducer unit to bring the input speed to the desired level, a Dual output unit
which comprises of a pair of worm & worm wheel assemblies (with worms

mounted on a common drive shaft), a pair of splined Drive rods and a Motion
pickup Unit for each head. For each head the Motion pickup Unit comprises of
a pair of pinions PCD 146mm & a mating slotted spur gear PCD 274mm. Each
of the two pinions receives drive from each of the splined drive rods, which
inturn are connected to the O/P shafts Dual O/P unit thru MUF couplings. The
two synchronously driven pinions enable the slotted gear to retain drive even
when the disengagement from one of the pinions. The slotted spur gear
provides rotation to the rotary heads. Further a suitable AC Vector drive has
been provided for soft starting as well as stopping of the head rotation as well
as for adjustment of the head RPM. In addition a mechanical brake release
arrangement has been provided. Further the Signal Line stops the Rotary
Head in such a position that the slot matches with the opening on the top of
head body. The transmitted through the splinned shafts enables each of the
rotating heads to be adjusted independently to cater to various sizes of
diamond coils/jobs.
HEATING PLATEN UNIT(Refer Figure-V):-
A pair of heating platens of sizes catering to various coil sizes is provided for
each rotating head. Further the heating system has been designed to provide
maximum power input of upto 4400 watts and continuous heating at
temperature of upto 100°C from 1 to 10 mins. The heating rate is adjustable
by means of a toroidal core transformer with output variation for 0-220V AC.
The heating platens are made up of stainless steel 7 the tubular heating
elements are embedded into the heating platens for heaters of the same.
Suitable adjustment arrangement is provided for keeping the heating
elements in continuous & uniform contact with the job contact surface. Also
suitable thermal insulation arrangement is incorporated for limiting heat
transfer from the electrically heated platens to the pneumatic cylinders &
subsequent seal damage. Further the cylinders are provided with high
temperature seals. Heating time, depending on the radial thickness of the

insulation, is fed through the MMI to the PLC. Power fed into the coils is
displayed & recorded digitally.
UTILITY DEVICES:-
COIL CLAMPING UNIT:
The coils are clamped by a pair of coil holding clamps, for each rotating head.
These clamps are simple & manually adjustable in all the 3 axes. These
clamps hold the coil, rigidly at its position, prior to the initiation of the
smoothening cycle.
PNEUMATIC CIRCUIT(Refer Figure-VI):-
The rotational pressing in the machine is done, pneumatically for the same a
well laid out pneumatic circuit comprising of Special double guided cylinders,
Special valves, Rotary air chambers, NRV's, DC valves, Flow control valves,
FRL unit & compressor has been implemented the opartional sequencing of
the same is achieved & controlled by the PLC. As per the job requirement
input air pressure can be controlled from 3 to 10 bars.
ELECTRICAL CIRCUIT(Refer Figure-VII & VIII):-
The automatic controlling sequencing and interfacing of the various
systems/arrangements is achieved by means of Siemens S7-200
Programmable Logic Controller unit. The PLC co-ordinates the function &
sequencing of various pneumatic, heating, electrical & power electronic
circuitaries for the automatic operation of the newly developed Ironing
machine. A Man Machine Interface has been provided on the swivellable type
Control Pendent for communicating with the PLC and making desired cycle
changes/interruptions. Further for heating a 6 KVA transformer & thyristor
controller has been provided.

SEQUENCE OF OPERATION:-
The sequence of operation of the Ironing machine is as follows:
1. Linear adjustment of Rotary heads to cater to the various job(coil)
sizes.
2. Changing of Heating platens for varying coil sizes.
3. Loading & clamping of the paper wound coils on the coil clamping unit.
4. Adjustment of pneumatic pressure & electrical heating rate based on
coil sizes.
5. Start the cycle in Auto Mode.
6. Once the desired number of turns is achieved, the cycle stops with slot
on the top & pneumatic cylinders retract.
7. Unload the coil & load fresh coil.

10

WE CLAIM
1. Development of an automated machine for ironing of insulation of
stator coils of electrical motors comprising:-
- a machine base unit for supporting and providing various
mountings;
- a rotating head assembly with opening on top for simultaneous
rotational pressing and heating of the fixed cover coils;
- a main drive unit for providing desire rotation to the rotary
head;
- a pair of heating plates for continuous and uniform heating of
diamond shape coils under pressure;
- a plurality of services like coil clamping unit, pneumatic circuit,
electrical/electronic circuit, PLC unit etc. for sequencing and
controlling required operating.

2. The automated machine as claimed in claim 1 wherein the said
machine has a fabricated bed with a pair of rotating heads adjustable
on the same and houses the pneumatic control panel and heating
transformer.
3. The automated machine as claimed in claim 1 wherein the said
machine is also provided with a pair of 3-axis clamping units into each
rotating head assembly.

4. The automated machine as claimed in claim 1 wherein the said
machine is provided with electrically heated platen for smoothening
process which is actuated by a pair of diagonally opposite clamping
cylinders and pressing the coil to start smoothening operation.
5. The automated machine as claimed in claim 1 wherein the said
machine is provided with a programmable logic controller to monitor &
control sequencing of the various operations, no. of cycles, platen
heating and automatic control of the system.
6. The automated machine as claimed in claim 2&3 wherein the said
rotary head comprises

- a spur gear, rotating on the 10 of cast iron housing (in two
halves), turcite lining has to be provided on ID for minimizing
friction;
- the spur gear on the rotary drum receives drive from the main
drive unit through pinion & drive rod;
- it receives electrical input for heating by means of slip ring &
carbon brush arrangement and air input by means of NRV's
provided on the drum periphery at 180°;
- the electrical input is given by thyristorised controlled 6KVA
supply means;
- the pneumatic input at the set pressure from 3 to 10 Bar from
the compressor unit;
7. The automated machine as claimed in claim 4 wherein the said heating
platens are made up of stainless steel and the tubular heating
elements are embedded into the heating platens for hater and
maximum supplied power input 4400 watts and continuous heating at
temperature of 100°C-110°C from 1 to 10 mins and is controlled by
means of a toroidal core transformer with output variation for 0-220V

AC and a suitable thermal insulation arrangement is incorporated for
limiting heat transfer from the electrically heated platens to pneumatic
cylinders & subsequent seal damage.
8. The automated machine as claimed in claim 1,2&4 wherein the
rotational pressing in the machine is done pneumatically which
comprises a well laid out pneumatic circuit comprising of special double
guided cylinders, special valves, rotary air chambers, NRV's, DC valves,
flow control valves, FRL unit & a compressure which is controlled by
the PLC.
9. The automated machine as claimed in claim 1 wherein the automatic
controlling, sequencing and interfacing of various
system/arrangements is achieved by means of Siemens S7-200
programmable logic controller unit.
Dated this 6th day of May 2008.

Development of an automated machine for ironing of insulation of
stator coils of electrical motors comprising:-
- a machine base unit for supporting and providing various
mountings;
- a rotating head assembly with opening on top for simultaneous
rotational pressing and heating of the fixed cover coils;
- a main drive unit for providing desire rotation to the rotary
head;
- a pair of heating plates for continuous and uniform heating of
diamond shape coils under pressure;
a plurality of services like coil clamping unit, pneumatic circuit,
electrical/electronic circuit, PLC unit etc. for sequencing and
controlling required operating.