FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
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 mechanism and method for pressing shaft in a rotor.
APPLICANT (S)
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S)
Dandavate Amol Anil and Dikonda Rajendra Baburao , both of Crompton Greaves Limited, LT Motor Division, A-6/2 MIDC Industrial Area, Ahmednagar-414111, Maharashtra, India; both 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
This invention relates to the field of mechanical assemblies and mechanical engineering.
Particularly, this invention relates to motors.
Specifically, this invention relates to a mechanism and method for pressing shaft in a rotor.
BACKGROUND OF THE INVENTION
A motor for electrical purposes, i.e. an electric motor, is a device which converts electrical energy to mechanical energy. A motor contains two main components; stator, rotor. The rotor is the non-stationary part of a rotary motor, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotor's axis. The stator is the stationary part of a rotor system. The rotor has a fanning action.
The rotor is die cast. There is a step of pressing of shaft in die cast rotor.
According to the prior art, the following steps are followed:
A. Placement of rotor on cup.
B. Placing the skewed keyway shaft inside the rotor.
C. Putting the shaft fitting cup on shaft shoulder.
D. Pressing the shaft from top till it touches to the shoulder of shaft.

This conventional method has disadvantages, as explained below:
I. After pressing of shaft pulley run out goes beyond specification limit of IEC
standard. II. The shaft twists and is then rejected according to standards that need to be
followed for manufacturing of motor.
Hence, there is a need for a mechanism and method for pressing shaft in a rotor which obviates the limitations of the prior art.
OBJECTS OF THE INVENTION
An object of the invention is to provide a mechanism and method for pressing shaft in a rotor wherein shaft does not twist.
Another object of the invention is to reduce wastage of electro-mechanical equipment.
Yet another object of the invention is to provide a mechanism and method wherein shaft, after pressing in rotor, does not get rejected.
Still another object of the invention is to provide a mechanism and method which aids in providing a shaft inserted in a die cast rotor such that localized repairing techniques are eliminated.
An additional object of the invention is to provide a mechanism and method such that shaft run out after rotor insertion can be controlled precisely.

Another additional object of the invention is to provide a mechanism and method such that shaft run out dimension remains unchanged before and after pressing.
Yet another additional object of the invention is to provide a mechanism, assembly, and method which facilitates cold pressing method of shaft in rotor.
SUMMARY OF THE INVENTION
According to this invention, there is provided a mechanism for pressing shaft in a rotor, which rotor being rested on a rotor cup in a co-axial manner, and, which shaft being pressed by a co-axial shaft pressing cup, said mechanism comprises:
a. first locating means adapted to locate said shaft within said rotor and to
provide support from an operative top side, said first locating means adapted
to operate from said operative top of said shaft and being located along with
said shaft pressing cup; and
b. second locating means adapted to locate said shaft within said rotor and to
provide support from an operative bottom side, said second locating means
adapted to operate from operative bottom of said shaft and being located
along with said rotor resting cup.
Typically, said first locating means comprises a set of thrust ball bearings adapted to be annularly located about said shaft pressing cup.
Typically, said second locating means comprises a set of taper roller bearings adapted to be annularly located about said rotor resting cup.
Typically, said second locating means comprises a set of angularly inclined roller bearings adapted to be annularly located about said rotor resting cup.

According to this invention, there is also provided a method for pressing shaft in a rotor, which rotor being rested on a rotor cup in a co-axial manner, and, which shaft being pressed by a co-axial shaft pressing cup, said method comprises:
i. first step of placing said rotor cup on second locating means;
ii. second step of placing rotor on said rotor cup; iii. third step of placing said shaft inside said rotor; iv. fourth step of putting first locating means on shaft shoulder;
v. fifth step of putting said shaft fitting cup on said first locating means; and vi. sixth step of pressing said shaft from top till it touches the shoulder of shaft.
Typically, said first step of placing said rotor cup on second locating means comprises a step of placing said rotor cup on taper roller bearings.
Typically, said fourth step of putting first locating means on shaft shoulder comprises a step of putting thrust bearings on shaft shoulder.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates a schematic illustration of shaft pressing in die cast rotor.
The invention will now be described in relation to the accompanying drawings, in which,
Figure 2 illustrates a schematic illustration of shaft pressing in die cast rotor.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates a schematic illustration of shaft pressing in die cast rotor.
A rotor (12), preferably a die cast rotor, is placed / located in a rotor resting cup (14). This placement is, typically, a co-axial placement. A shaft fitting cup (16) is located on shaft shoulder. The shaft fitting cup (16) comprises shaft pressing collars are also placed on the operative top of the rotor (12) such that the annular gap in between the collars, or inside the cup (16), is co-axial with the rotor (12). A shaft (18), that is to be pressed into the rotor (12), is passed through the annular gap between the collars (16). Shaft (18) is pressed from its operative top till it touches the shoulder of shaft (18).
This system, mechanism, and method has several problems relating to shaft skewing, which have been elaborated above.
According to this invention, there is provided a mechanism for pressing shaft in a rotor.
Figure 2 illustrates a schematic illustration of shaft pressing in die cast rotor, according to this invention.
Reference numeral 12 refers to rotor, typically to die cast rotor. Reference numeral 18 refers to shaft which is to be pressed in to rotor (12). Reference numeral 14 refers to rotor cup for resting rotor. Reference numeral 16 refers to shaft cup for pressing on to shaft (18).
In accordance with an embodiment of this invention, there is provided a first

locating means (30) adapted to locate the shaft (18) within the rotor (12) and to provide support from the operative top side. The first locating means (30) operates from the operative top of the shaft (18) and is located along with the shaft pressing cup (16). The first locating means (30) is a set of thrust ball bearings adapted to be annularly located about the shaft pressing cup (16).
In accordance with an embodiment of this invention, there is provided a second locating means (40) adapted to locate the shaft (18) within the rotor (12) and to provide support from the operative bottom side. The second locating means (40) operates from the operative bottom of the shaft (18) and is located along with the rotor resting cup (14). The second locating means (40) is a set of taper roller bearings adapted to be annularly located about the rotor resting cup (14).
The combination of thrust ball bearing (first locating means) (30) and tapered roller bearing (second locating means) (40) allows for rotation of shaft while pressing. The shaft rotation, therefore, avoids the twisting of shaft pulley and, hence, pulley run out gets within desired standards.
According to this invention, there is provided a method for pressing shaft in a rotor.
The method comprises a first step of placing the rotor cup (14) on second locating means (tapered roller bearing).
The method comprises a second step of placing rotor (12) on rotor cup (14).
The method comprises a third step of placing a skew key way shaft (18) inside the rotor (12).

The method comprises a fourth step of putting the thrust ball bearing (30) on shaft shoulder.
The method comprises a fifth step of putting the shaft fitting cup (16) on thrust bearing (30).
The method comprises a sixth step of pressing the shaft (18) from top till it touches the shoulder of shaft (18).
The following are the technical advantages of using the mechanism and method of this invention:
1. Shaft run out after rotor insertion can be controlled precisely.
2. Shaft run out dimension remains unchanged before and after pressing,
3. This is the only one cold pressing method which gives a relatively bettwe result compare with method of the prior art.
4. The technical modifications of the current invention can be retrofitted on to the mechanisms and methods of the prior art.
5. With the mechanism and method of the prior art, rejection for shaft run out was relatively high (almost 500,000 PPM), while with the mechanism and method of the current invention, rejection is relatively less (almost 10,000 PPM).
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A mechanism for pressing shaft in a rotor, which rotor being rested on a
rotor cup in a co-axial manner, and, which shaft being pressed by a co-axial
shaft pressing cup, said mechanism comprising:
a. first locating means adapted to locate said shaft within said rotor and
to provide support from an operative top side, said first locating
means adapted to operate from said operative top of said shaft and
being located along with said shaft pressing cup; and
b. second locating means adapted to locate said shaft within said rotor
and to provide support from an operative bottom side, said second
locating means adapted to operate from operative bottom of said shaft
and being located along with said rotor resting cup.
2. A mechanism as claimed in claim 1, wherein said first locating means comprising a set of thrust ball bearings adapted to be annularly located about said shaft pressing cup.
3. A mechanism as claimed in claim 1, wherein said second locating means comprising a set of taper roller bearings adapted to be annularly located about said rotor resting cup.
4. A mechanism as claimed in claim 1, wherein said second locating means comprising a set of angularly inclined roller bearings adapted to be annularly located about said rotor resting cup.

5. A method for pressing shaft in a rotor, which rotor being rested on a rotor
cup in a co-axial manner, and, which shaft being pressed by a co-axial shaft
pressing cup, said method comprising:
i. first step of placing said rotor cup on second locating means; ii. second step of placing rotor on said rotor cup; iii. third step of placing said shaft inside said rotor; iv. fourth step of putting first locating means on shaft shoulder; v. fifth step of putting said shaft fitting cup on said first locating means;
and vi. sixth step of pressing said shaft from top till it touches the shoulder of shaft.
6. A method as claimed in claim 5, wherein said first step of placing said rotor cup on second locating means comprising a step of placing said rotor cup on taper roller bearings.
7. A method as claimed in claim 5, wherein said fourth step of putting first locating means on shaft shoulder comprising a step of putting thrust bearings on shaft shoulder.