FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
& The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A hot press machine for curing the coil of a HT(high tension)/LT (low tension) machine
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Neeraj Sharma of Crompton Greaves Ltd, M7 Division, Crompton Greaves Ltd, CG Global R&D Centre, Kanjur (E), Mumbai 400042, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a hot press machine for curing the coil of a HT(high tension)/LT (low tension) machine. BACKGROUND OF THE INVENTION
A HT(high tension)/LT (low tension) machine such as an electric motor includes a HT/LT stator coil comprising loops of conductors stacked one above the other and consolidated together. The stator coil is manufactured by stacking loops of epoxy resin covered conductors one above another and consolidating them by curing under temperature and pressure in a hot press machine. The hot press machine comprises a plurality of platens oriented within the machine such that the coil remains disposed on one of the platens and other plates surround the coil from the sides and top thereof. The top platen is usually movable towards and away from the bottom platen on which the coil is disposed. Each platen is usually an assembly of two sub-platens screwed together. The respective inner surfaces of each sub-platen are provided with profiles such that when held together, a hole is formed within the assembled platen between the top and bottom surfaces thereof. A heater pipe is held within each such hole and connected to an external supply for heating thereof. The platen is consequently heated thereby heating the coil mounted on the platen and/or in the vicinity thereof. Further, an RTD (Resistance Temperature Detector) is provided within the platen disposed below the heaters to detect the temperature of the platen while being heated. Usually, the RTD is provided at the side end portion of the platen opposite to the side from where the heater pipes are inserted within the platen.
The size of the platens is usually very large. To remove the heater pipes therefrom, each platen is first inverted and then unscrewed which is cumbersome, time consuming and risky.

The placement of RTDs as described above does not lead to accurate measurement of the temperature owing to the fact that the RTD is located below the heater pipes and away from the location corresponding to the centre portion of the coil. Since heat waves travel upwards from the heater pipes, placement of RTD below the heater pipes is not ideal. Also, it is critical to measure the temperature at the center of the coil. More often, due to the above placement of RTD, the coil gets overheated.
Usually, after curing the coils, the hot press machine is cooled by placing fans around it. Such is time consuming and there is a scope to cool the hot press machine faster. OBJECTS OF THE INVENTION
An object of the invention is to provide a hot press machine for curing the coil of a HT(high tension)/LT (low tension) machine.
Another object of the invention is to provide a hot press machine for curing the coil of a HT/LT machine wherein the removal of heater pipes therefrom is easy and quick.
Another object of the invention is to provide a hot press machine for curing the coil of a HT/LT machine wherein the placement of RTD within the platen of the machine is such that the temperature of the platen is recorded accurately.
Another object of the invention is to provide a hot press, machine for curing the coil of a HT/LT machine which is easy and quick to cool without requiring any external cooling medium.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a hot press machine for curing the coil of a HT(high tension)/LT (low tension) machine, the machine comprising a

plurality of platens oriented within the machine such that the coil remaining disposed on a platen and surrounded therewith, each platen being an integrated structure and comprising a plurality of heater pipes held therein the between the top and bottom surfaces thereof and at least one water channel formed within the platen below the heater pipe holes, the water pipe having an inlet and outlet opening at the same or different sides of the platen.
Preferably, the heater pipes extend across the width of the platen and the water pipe extends along the length of the platen. A RTD (Resistance Temperature Detector) is placed above the heater pipes at the center of the platen.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is an isometric view of a platen of a hot press machine without the heater pipe therein.
Fig 2 is an isometric view of a platen of a hot press machine with the heater pipe being partially inserted therein.
Fig 3 is a schematic view of the water channel within the platen.
Referring to figures 1-3, a platen 1 of a hot press machine (not shown) for curing the coil of a HT(high tension)/LT (low tension) machine is a huge rectangular plate comprising a plurality of heater pipes 2 and a water channel 3 formed within the platen 1. The heater pipes 2 are held in heater pipe holes 4 opening at one side 5 of the platen 1 in a spaced apart relationship with each other and extending across the width of the platen 1. Each heater pipe 2 is connected to an external supply for heating thereof which in turn heats the platen 1. The water channel 3 is integral within the platen molded therein below the heater pipe holes 4 at the time of casting the platen 1.

A water channel hole 6 opens at the side 7 of the platen adjacent to the side 5 having heater pipe hole 4 openings, extends forward and backward along the length of platen 1 forming a U-shape and opens 8 again at the same side 7, albeit in a spaced apart relationship with the other opening 6. The heater 4 and water pipe 6 holes are mould within the platen 1 at the time of casting the platen 1. To insert/pull out the heater 2 pipes from the platen 1, the platen 1 is held vertically, and the heater 2 pipe pushed/pulled out of the platen 1. According to an embodiment, the heater pipes are made up of a conducting material such as iron or steel. A RTD (Resistance Temperature Detector) (not shown) is placed above the heater pipes 2 at the centre of the platen 1.
The platens 1 are oriented within the hot press machine such that the coil remains disposed on one of the platens 1 and surrounded by other platens 1. Upon switching on the power supply to the heater pipes 2, the platens 1 are heated thereby heating the coil. Usually, the temperature is in the order of hundreds of degree Celsius. The RTD at the center of the base platen 1 records the temperature and passes onto a control system. Upon completion of the curing, the coil is taken off from the machine. Cold water is passed into one opening 6 of the water channel 3 which extends across all the hot heater pipes 2 thereby cooling them. Water is taken out from the other water pipe opening 8. Cooling of the heater pipes 2 is thus easy and quick.
The shape of the platen, heater pipes and holes and water channel may be different that what is shown in the figures. The heater pipes and water channel may run in any orientation within the platen. The water channel may branch out within the platen to cover a maximum area within the platen for cooling. RTD may be provided in one, few or all all the platens within the machine depending on the design.

According to the invention, insertion and removal of the heater pipes within the platen is easy and quick. Placement of RTD at the center of the platen ensures accurate recording of temperature. Cooling of the platen is rendered quick and easy.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. A hot press machine for curing the coil of a HT(high tension)/LT (low tension) machine, the machine comprising a plurality of platens oriented within the machine such that the coil remaining disposed on a platen and surrounded therewith, each platen being an integrated structure and comprising a plurality of heater pipes held therein the between the top and bottom surfaces thereof and at least one water channel formed within the platen below the heater pipe holes, the water channel having an inlet and outlet opening at the same or different sides of the platen.
2. The hot press machine as claimed in claim 1, wherein the machine comprises of at least one RTD (Resistance Temperature Detector) placed within the platen on which the coil is mounted, the RTD being placed above the heater pipes at the center of the platen.
3. The hot press machine as claimed in claim 1, wherein the heater pipes extends across the width or length of the platen.
4. The hot press machine as claimed in claim 1, wherein the water channel is molded within the platen below the heat pipes and extends in a direction across the heater pipes for cooling thereof.
5. The hot press machine as claimed in claim 1, wherein the heat pipes and water channel opens at different sides of the platen.