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
Device for holding the stator body of an AC motor
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400 030, Maharashtra, India, an Indian Company
INVENTOR
Bhujbal Eknath Ramdas and Pinnamaraju Saibabu, both of Crompton Greaves Ltd, Engineering Department, LT Motors Division (M3), A-6/2 MIDC, Ahmadnagar 414 001, Maharashtra, India, both Indian nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a device for holding the stator body of an AC motor.
BACKGROUND OF THE INVENTION
An AC motor comprises a cylindrical rotor concentrically rotatably mounted within a cylindrical stator in spaced apart relationship with the stator. The stator comprises a cylindrical wound stator pack concentrically located within a cylindrical stator body which is usually cast iron. The wound stator pack comprises a cylindrical wound structure of stator windings with overhangs at the ends thereof. The stator body comprises a spigot (step) internally at each end thereof and a uniform inner diameter between the spigots. The spigots are for locating the endshields of the motor. Prior to assembling the wound stator pack within the stator body, the spigots and the inner diameter of the stator body between the spigots are machined to accurate dimensions.
The machining of the spigots and the inner diameter of the stator body is carried out by first aligning the stator body on an aligning body comprising a base and atleast one tapered spigot aligning portion at the top of the base. The stator body is aligned on the aligning body by locating the spigot at one end of the stator body against the spigot aligning portion of the aligning body. The stator body is clamped in position and taken to a vertical turret lathe machine to carry out the machining of the spigot at the other end of the stator body. On completion of the machining of the spigot at the said other end of the stator body, the stator body is dismantled from the lathe machine, inverted and the spigot at the said other end of the stator body is positioned on the spigot locating surface of a spigot plate mounted on the chuck of another vertical turret lathe machine. The spigot plate may comprise one or more spigot locating surfaces. Machining of the spigot at the said one end of the stator body and inner surface of the

stator body between the spigots is carried out on this lathe machine. On completion of the machining operation, the stator body is dismantled from the lathe machine.
Machining of the stator body to accurate dimensions as described above, requires two separate vertical turret lathe machines and separate components, namely aligning body and spigot plate. Therefore, the capital investment for machining of the stator body to accurate dimensions is very high. Labour and machining time are high thereby further increasing cost and reducing productivity. Machining is also cumbersome and difficult to carry out.
OBJECTS OF THE INVENTION
An object of the invention is to provide a device for holding the stator body of an AC motor, which device reduces capital investments for the machining operation and also the number of components required for the machining operation and the labour and time for the machining operation and is substantially economical.
Another object of the invention is to provide a device for holding the stator body of an AC motor, which device increases productivity and renders the machining operation simple and easy to carry out.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a device for holding the stator body of an AC motor, the device comprising a base having a locating recess at the bottom adapted to locate the base on the chuck of a vertical turret lathe machine and atleast one pair of a tapered spigot aligning

portion and a spigot locating surface at the top of the base with a common centre line passing therethrough, wherein the spigot locating surface is at the foot of the spigot aligning portion, the base further having mounting means for mounting the base on the chuck of the lathe machine, levelling means for maintaining the level of the stator body when located against the spigot aligning portion or spigot locating surface and handling means to facilitate handling of the base.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is an isometric view of the device for holding the stator body of an AC motor according to an embodiment of the invention without the leveling pads;
Fig 2 is plan view of the device of Fig 1;
Fig 3 is a crosssectional view of the device of Fig 1 including the leveling pads;
Fig 4 is an enlarged view at the portion marked X in Fig 3;
Figs 5 and 6 are elevations of the device of Fig 1 having the stator body of an AC motor located over a tapered spigot aligning portion and corresponding spigot locating surface of the device,
respectively.

The device I for holding the stator body 2 of an AC motor (not shown) as illustrated in Figs I to 6 of the accompanying drawing comprises a base 4 having a locating recess 5 at the bottom thereof. The base also comprises three pairs of a tapered spigot aligning portion and a spigot locating surface at the top thereof, one above another in a stepped configuration. The spigot aligning portions and the corresponding spigot locating portions are marked 6a and 7a, 6b and 7b and 6c and 7c, respectively. Each spigot locating surface is at the foot of a spigot aligning portion. All the spigot aligning portions and spigot locating surfaces have a common centre line passing therethrough. The base further comprises four spaced mounting holes 8 corresponding to and matching with the mounting holes (not shown) in the chuck (not shown) of a vertical turret lathe machine (not shown). The base also comprises an engaging hole 9 at the center thereof. A plurality of lateral slots 10 are provided in the base in a spaced apart manner across the spigot aligning portions and spigot locating surfaces.
The device is mounted on the chuck of the vertical turret lathe machine by engaging the recess at the bottom of the base over the chuck and tightening bolts (not shown) in the mounting holes in the base and corresponding mounting holes in the chuck. In order to machine the stator body, the stator body is held in position aligned on one of the spigot aligning portions 6a, 6b or 6c of the device by locating the spigot at one end of the stator body against the said one spigot aligning portion matching with the spigot at the said one end of the stator body. The stator body is clamped in this position and machining of the spigot at the other end of the stator body is carried out. On completion of the machining of the spigot at the said other end of the stator body, the stator body is declamped, inverted and the spigot at the said other end of the stator body is engaged over the corresponding spigot locating surface of the device. The stator body is

clamped in position and machining of the spigot at the said one end of the stator body and inner surface of the stator body between the spigots is carried out. During machining of the stator body in case levelling of the stator body is required to be carried out, levelling pads 11 are inserted in the lateral slots and the respective end of the stator body is supported against the levelling pads. The engaging hole 9 at the center of the device helps to handle the device easily by lifting or the like. A hook or the like (not shown) is engaged in the engaging hole to handle the device. Preferably the base is made of mild steel or teflon. However, the base also can be made of any other mechanically strong and durable material. Provision of multiple pairs of spigot aligning portions and spigot locating surfaces helps to machine stator bodies with different inner diameters and spigots of different dimensions.
A main advantage of the invention is that the entire machining operation of the stator body is carried out in the same vertical turret lathe machine. The invention eliminates the second vertical turret lathe machine and a separate aligning body and spigot plate. The invention reduces the capital cost for the machining operation and the number of components required for carrying out the machining operation. Further, labour and time required for carrying out the machining operation of the stator body are reduced. Machining operation is rendered easy and convenient to carry out and productivity is increased.
The number of pairs of spigot aligning portions and spigot locating surfaces can be different. Instead of mounting holes other mounting means can be used for mounting the device on the chuck. Instead of lateral slots and levelling pads, other levelling means can be used to maintain the level of the stator body. Instead of engaging hole other handling means can be used to

handle the device. The number of mounting holes and lateral slots can vary. Such variations of the invention are obvious to those skilled in the art and are to be construed and understood to be within the scope of the invention.

We claim:
1. A device for holding the stator body of an AC motor, the device comprising a base having a locating recess at the bottom adapted to locate the base on the chuck of a vertical turret lathe machine and atleast one pair of a tapered spigot aligning portion and a spigot locating surface with a common centre line passing therethrough, wherein the spigot locating surface is at the foot of the spigot aligning portion, the base further having mounting means for mounting the base on the chuck of the lathe machine, levelling means for maintaining the level of the stator body when located against the spigot aligning portion or spigot locating surface and handling means to facilitate handling of the base.
2. The device as claimed in claim 1, wherein the mounting means comprises a plurality of spaced mounting holes corresponding to and matching with the mounting holes in the chuck of the lathe machine.
3. The device as claimed in claim 1 or 2, wherein the handling means comprises an engaging hole at the centre of the base.
4. The device as claimed in claims 1 to 3, wherein the levelling means comprises a plurality of levelling pads located within a plurality of spaced apart lateral slots across the spigot aligning portion and spigot locating surface.
5. The device as claimed in claims 1 to 4, which comprises 3 pairs of spigot aligning surface and spigot locating surface in a stepped configuration.

6. The device as claimed in any one of claims 1 to 5, which is made of mild steel or teflon.