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 device for uniform skew setting of a stack of rotor core segments.
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
Inventors
Chandrashekhar Keluskar and Sharad Vilas Patil of Stamping Division, Crompton Greaves Ltd, Kanjur Marg, Mumbai, Maharashtra, India, Indian Nationals
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
The present invention relates to a device for uniform skewing setting of rotor core
segments.
BACKGROUND OF THE INVENTION
Electrical machines, ceiling fans in particular generally include a stator and rotor, with one typical design including a cylindrical stator which rotates within an annular rotor. It is well known that such a rotor will include a plurality of windings comprising electrical wire which are laid in a plurality of channels formed by winding slots along the inner periphery of a plurality of stacked annular plate-type rotor core segments (laminations). The plurality of stacked rotor core segments when skewed and welded together forms a rotor core pack. The angle with which the rotor core segments are skewed is a critical angle and needs to be uniformly precise for each of the rotor core segments to facilitate a the creation of necessary electric flux that is needed to produce a required torque for the stator in a ceiling fan. With the available mechanisms currently employed the skew setting imparted to each of the rotor core segments tend to be non uniform because of manual interventions. The non uniformity in skew setting for the rotor core segments results in an insufficient electric flux that gets generated.
As can be appreciated by one skilled in the relevant art it is desirable to have a device that facilitates a uniform skew setting across the rotor core segments that comprises a rotor core pack.

OBJECTS OF THE INVENTION
An object of this invention is to provide a device for providing a uniform skew setting to each of the rotor core segments.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention a device to provide a uniform skew setting to a linearly arranged rotor core segments that have peripheral winding slots and defines a circular space. The device comprises of a base plate firmly mounted over a support surface to receive the plurality of rotor core segments, the rotor core segments being mutually aligned with adjacent rotor core segments ; and a mandrel plate fixedly mounted over the base plate within the said circular space to retain the alignment of the rotor core segments and substantially constricting their lateral movements along a central axis of the plurality of rotor core segments ; and a plurality of longitudinal constraining members, a portion of the longitudinal constraining members engaging with corresponding winding slots of the plurality of rotor core segments; and a rotatable plate disposed over the mandrel plate for providing the longitudinal constraining members a pre-determined tilt and allowing each of the rotor core segments to be proportionally displaced whereby the uniform skew setting is imparted to each of the rotor core segments.
Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the

relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well known structures or operations are not shown in detail to avoid obscuring the features of the invention.
The following is a detailed description of the invention with reference to the accompanying drawings, in which;
Figure 1 is a front and top view of the device according to a preferred embodiment of the invention.
Figure 2 is a magnified view of the enlarged view of the arrangement of rotor core segments, the alignment of the mandrel plate and the skew plate and the bolts which form a part of the device according to a preferred embodiment of the invention.
Figure 1 represents the top view and the front side view of the device and is shown to contain the base plate 1, rotor core segments 2, bolts 3, rotatable plate 4 and mandrel plate 5, a central rod 6, a motor 7 and a motor switch 8. Base plate I is a circular plate that can be mounted over a support surface to hold annular shaped rotor core segments 2. As readily known by one skilled in the arts, multiple rotor core segments are made available as a rotor core pack (auto stitched pack) of different thicknesses. Rotor core segments have winding slots across their periphery which and are arranged in a way such that the corresponding winding slots of each rotor core segment are arranged linearly. A

mandrel plate 5 is disposed within the circular space enclosed by rotor core segments 2. Mandrel plate avoids the lateral movement of the rotor core segments. Mandrel plate may restrict the motion in at least two positions across the length of the rotor core segments to restrict the lateral movement of the rotor core segments. A rotatable plate 4 is disposed above the mandrel plate 5, and bolts 3 (four in number) are positioned through the winding slots of rotor core segments. Mandrel plate 5 and rotatable plate 4 are of a shape that allows for relative movement between the two with the bolts being positioned in their respective positions as shown in the top view. A centra! rod 6 is disposed from the centre of the rotatable plate 4 and is secured with a nut and bolt arrangement. The central rod 6 is provided an angular motion by means of a motor 7 arranged below the support surface as seen in the front view. Motor switch 8 controls the operation of the motor 7.
Figure 2 represents a enlarged view of the arrangement of the rotatable plate 4, the mandrel plate 5 and the bolt 3. As can be seen the rotatable plate 4 and mandrel plate 5 allow for a radial movement of the bolt 3. Bolt 3 is initially positioned perpendicularly through the winding slots of the rotor segments. Rotatable plate 4 when rotated tilts the bolt 3, causing each of the rotor core segments to get proportionally displaced resulting in a skewed arrangement of the rotor core segments as desired. The amount skew depends on the tilt delivered to the bolt 3. Motor 7 can be controlled to deliver a pre-determined tilt to the bolt 3.
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 device to provide a uniform skew setting to a linearly arranged plurality of rotor core segments which define a circular space therein, each of rotor core segments having a plurality of peripheral winding slots , the device comprising of:
a base plate firmly mounted over a support surface to receive the plurality of rotor core segments, the rotor core segments being mutually aligned with adjacent rotor core segments; and
a mandrel plate fixedly mounted over the base plate within the said circular space to retain the alignment of the rotor core segments and substantially constricting their lateral movements along a central axis of the plurality of rotor core segments ; and
a plurality of longitudinal constraining members, a portion of the longitudinal constraining members engaging with corresponding winding slots of the plurality of rotor core segments; and
a rotatable plate disposed over the mandrel plate for providing the longitudinal constraining members a pre-determined tilt and allowing each of the rotor core segments to be proportionally displaced whereby the uniform skew setting is imparted to each of the rotor core segments.

2. The device of claim ], further comprising a drive means is operated upon to provide
the pre-determined tilt by rotating a central rod disposed below from the centre of the
rotatable plate extending through the mandrel plate, the base plate and the support
surface; and
3. The device of claim 1, wherein the drive means is a motor.
4. The device of claim 1, wherein the longitudinal constraining members are bolts.