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 INVENTION
An apparatus for making the stator or rotor core of an electric motor
INVENTOR
Name : Karnik Suryakant
Nationality: Indian National
Address Crompton Greaves Limited, Stamping Division (M6), Kanjur (E),
Mumbai 400 042, Maharashtra, India
APPLICANTS
Name : CROMPTON GREAVES LIMITED
Nationality: Indian Company
Address : CG House, Dr Annie Besant Road, Worli, Mumbai 400025, Maharashtra, India
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 INVENTION
This invention relates to an apparatus for making the stator or rotor core of an electric
motor.
BACKGROUND OF INVENTION
The rotor or stator cores of electric motors are formed by stacking magnetic material laminations or plates one above the other manually to form a cylindrical block. The laminations or plates are stamped or punched out from a magnetic feed material such as metal sheet, coil or strip in a press machine using press tools like notching tools, gang slotting tools, segmental blanking tools or progression tools. In order to ensure efficient and smooth operation of the motor it is essential that there is no tilt in the height of the stack of laminations when the same is placed in the motor housing. Tilt in the height of the stacked core is determined by measuring the height of the stacked core at four diagonal ends of the stack and is known as core length variation. Tilt in the height of the core stack can occur when the laminations do not have a uniform surface area. Non -uniformity in the surface area of the laminations occurs due to non - uniform thickness or waviness of the magnetic feed material from which the laminations are punched out. Core length variation creates imbalance in the motor and the motor tends to malfunction thereby reducing its life. In order to decrease core length variation in the lamination stack of a rotor or stator core, it is known to make the core of a stator or rotor by stacking the laminations at different orientations at discrete intervals. This is done manually thereby increasing the assembly time and labour and reducing productivity.
2

OBJECTS OF INVENTION
An Object Of the invention is to provide an apparatus for making the stator or rotor core of an electric motor, which apparatus automates the making of the stator or rotor cores and reduces core length variation, assembly time and labour and increases productivity.
Another object of the invention is to provide an apparatus for making the stator or rotor core of an electric motor, which apparatus is simple in construction and easy and convenient to operate.
DETAILED DESCRIPTION OF INVENTION
According to the invention there is provided an apparatus for making the stator or rotor core of an electric motor, the apparatus comprising an open ended drum rotatably held in the bore in the bottom bolster of a press machine, the drum comprising an inner diameter corresponding to the outer diameter of the laminations to be punched out from a magnetic feed material by the press machine, an inlet portion provided with an inner diameter slightly eccentric to the inner diameter of the drum and an outlet portion comprising two sections, the first section describing an inner diameter slightly smaller than the inner diameter of the drum followed by the second section describing an inner diameter slightly eccentric to the inner diameter of the drum, the outlet portion opening into a chute located below the bore in the bottom bolster of the press machine for
3

collecting the laminations being punched out by the press machine and drive means for rotating the drum.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is a schematic assembled view of the apparatus according to an embodiment of the invention;
Fig 2 is an exploded view of the apparatus of Fig 1 without the drive means;
Fig 3 is a schematic exploded partial view of a press machine comprising the apparatus of Fig 1; and
Fig 4 is an enlarged scrap view at X in Fig 3.
As illustrated in Figs 1 to 4 of the accompanying drawings the apparatus comprises an open ended drum 1 rotatably held in the bore 2 in the bottom bolster 3 of a press machine. The inner diameter of the drum corresponds to the outer diameter of the laminations (not shown) to be punched out from a feed material 4 by the press machine. The inlet portion of the drum comprises a first ring 5 abutting and fitted to a flange 6 provided at the inlet end of the drum. The first ring describes an inner diameter slightly eccentric to the inner diameter of the drum. The outlet portion of the drum comprises a
4

second ring 7 fitted to the outlet end of the drum and describing a diameter slightly smaller than the inner diameter of the drum. 8 is a third ring fitted to the second ring and
describing a diameter slightly eccentric to the inner diameter of the drum. The inner
diameter of the first ring and third ring is eccentric to the inner diameter of the drum by
0.4mm to 0.6mm with respect to the center of the drum and the inner diameter of
the second ring is smaller than the inner diameter of the drum by 0.02mm to 0.03mm with respect to the center of the drum. The outlet portion of the drum opens into a chute (not shown) for collecting the laminations being punched out by the press machine. The chute is located below the bore in the bottom bolster of the press machine. A drive means comprising a rack 9 and pinion 10 are mounted on a bracket 11 fitted to the bottom bolster of the press machine. A driver gear 12 is mounted on the shaft 13 of the pinion. A driven gear 14 is mounted on the drum in mesh with the driver gear. 15 is a pneumatic cylinder horizontally mounted on two upright members 16,16 on a base 17 extending laterally from the bottom bolster of the press machine. The to and fro linear movement of the rack is provided by the pneumatic cylinder and the movement of the rack in the channel 18 in the bracket 11 is guided by two C - shaped guides 19, 19 fitted on the bracket 10.
During operation of the press machine, magnetic feed material 4 is continuously moved forward and laminations (not shown) are punched out from the feed material by the tool 20 and die 21 of the press machine. The laminations being punched out by the press machine fall down into the bore and the rotating drum in a single file or column as the
adjacent laminations are very close to each other. As the diameter of the ring 5 is slightly
5

eccentric to the inner diameter of the drum and hence the outer diameter of the laminations, the ring interrupts the file of laminations entering the drum and allows only
a group of laminations to enter the drum at a time, Each group of laminations entering the
drum rotates with the drum and falls down into the chute. As the diameter of the ring 7 is slightly smaller than the inner diameter of the drum and hence outer diameter of the laminations, each group of laminations is momentarily retained in the drum and rotates with the drum before falling down into the chute located below the bottom bolster. As the diameter of the ring 8 is slightly eccentric to the inner diameter of the drum and hence outer diameter of the laminations, the laminations being collected in the chute in the form of a stack are prevented from moving up and entering the drum. Since each group of laminations falling down into the drum is rotated before its exit from the drum, the stack formed by the laminations exiting the apparatus of the invention comprises groups of laminations stacked at different orientations thereby reducing the core length variation of the stack. Also manual intervention is not required for making the stator or rotor cores as the whole process is automated. This reduces labour and cost and increases productivity. The apparatus of the invention is simple in construction and easy and convenient to operate.
The drive means can be of a different construction and configuration. Instead of rings the inlet portion and outlet portion of the drum can be differently configured or profiled to perform the respective functions. Such variations in the construction and configuration of the apparatus are obvious to those skilled in the art and are to be construed and understood to be within the scope of the invention.
6

We Claim
1. An apparatus for making the stator or rotor core of an electric motor, the
apparatus comprising an open ended drum rotatably held in the bore in the bottom bolster of a press machine, the drum comprising an inner diameter corresponding to the outer diameter of the laminations to be punched out from a magnetic feed material by the press machine, an inlet portion provided with an inner diameter slightly eccentric to the inner diameter of the drum and an outlet portion comprising two sections, the first section describing an inner diameter slightly smaller than the inner diameter of the drum followed by the second section describing an inner diameter slightly eccentric to the inner diameter of the drum, the outlet portion opening into a chute located below the bore in the bottom bolster of the press machine for collecting the laminations being punched out by the press machine and drive means for rotating the drum.
2. An apparatus for making the stator or rotor core of an electric motor as claimed in claim 1, wherein the inlet portion comprises a first ring abutting and fitted to a flange at the inlet end of the drum, the first ring describing an inner diameter slightly eccentric to the inner diameter of the drum and the first section of the outlet portion comprises a second ring fitted to the outlet end of the drum and describing a diameter slightly smaller than the inner diameter of the drum and the second section of the outlet portion comprises a third ring fitted to the second ring and describing a diameter slightly eccentric to the inner diameter of the drum.
7

3. An apparatus as claimed in claim 1, wherein the inner diameter of the inlet portion and the second section of the outlet portion is eccentric to the inner diameter of the drum by 0.4mm to 0.6mm with respect to the center of the drum and the inner diameter of the first section of the outlet portion is smaller than the inner diameter of the drum by 0.02mm to 0.030mm with respect to the centre of the drum.
4. An apparatus as claimed in claim 2, wherein the inner diameter of the first ring and third ring is eccentric to the inner diameter of the drum by 0.4mm to 0.6mm u-with respect to the center of the drum and the inner diameter of the second ring is smaller man the inner diameter of the drum by 0.02mm to 0.030mm with respect to the center of the drum.
5. An apparatus for making the stator or rotor core of an electric motor as claimed in any one of claims 1 to 4, wherein the drive means comprises a rack and pinion mounted on the bottom bolster of the press machine, a driver gear mounted on the shaft of the pinion and a driven gear mounted on the drum in mesh with the driver gear, the rack being linearly reciprocally held in the bottom bolster of the press machine and a
pneumatic cylinder mounted on the bottom bolster of the press machine horizontally with its piston rod coupled to the rack, the pneumatic cylinder being connected to the


controller of the press machine.
Dated this 5th day of January 2006
8

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 INVENTION
An apparatus for making the stator or rotor core of an electric motor
INVENTOR
Name : Karnik Suryakant
Nationality: Indian National
Address Crompton Greaves Limited, Stamping Division (M6), Kanjur (E),
Mumbai 400 042, Maharashtra, India
APPLICANTS
Name : CROMPTON GREAVES LIMITED
Nationality: Indian Company
Address : CG House, Dr Annie Besant Road, Worli, Mumbai 400025, Maharashtra, India
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 INVENTION
This invention relates to an apparatus for making the stator or rotor core of an electric
motor.
BACKGROUND OF INVENTION
The rotor or stator cores of electric motors are formed by stacking magnetic material laminations or plates one above the other manually to form a cylindrical block. The laminations or plates are stamped or punched out from a magnetic feed material such as metal sheet, coil or strip in a press machine using press tools like notching tools, gang slotting tools, segmental blanking tools or progression tools. In order to ensure efficient and smooth operation of the motor it is essential that there is no tilt in the height of the stack of laminations when the same is placed in the motor housing. Tilt in the height of the stacked core is determined by measuring the height of the stacked core at four diagonal ends of the stack and is known as core length variation. Tilt in the height of the core stack can occur when the laminations do not have a uniform surface area. Non -uniformity in the surface area of the laminations occurs due to non - uniform thickness or waviness of the magnetic feed material from which the laminations are punched out. Core length variation creates imbalance in the motor and the motor tends to malfunction thereby reducing its life. In order to decrease core length variation in the lamination stack of a rotor or stator core, it is known to make the core of a stator or rotor by stacking the laminations at different orientations at discrete intervals. This is done manually thereby increasing the assembly time and labour and reducing productivity.
2

OBJECTS OF INVENTION
An Object Of the invention is to provide an apparatus for making the stator or rotor core of an electric motor, which apparatus automates the making of the stator or rotor cores and reduces core length variation, assembly time and labour and increases productivity.
Another object of the invention is to provide an apparatus for making the stator or rotor core of an electric motor, which apparatus is simple in construction and easy and convenient to operate.
DETAILED DESCRIPTION OF INVENTION
According to the invention there is provided an apparatus for making the stator or rotor core of an electric motor, the apparatus comprising an open ended drum rotatably held in the bore in the bottom bolster of a press machine, the drum comprising an inner diameter corresponding to the outer diameter of the laminations to be punched out from a magnetic feed material by the press machine, an inlet portion provided with an inner diameter slightly eccentric to the inner diameter of the drum and an outlet portion comprising two sections, the first section describing an inner diameter slightly smaller than the inner diameter of the drum followed by the second section describing an inner diameter slightly eccentric to the inner diameter of the drum, the outlet portion opening into a chute located below the bore in the bottom bolster of the press machine for
3

collecting the laminations being punched out by the press machine and drive means for rotating the drum.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is a schematic assembled view of the apparatus according to an embodiment of the invention;
Fig 2 is an exploded view of the apparatus of Fig 1 without the drive means;
Fig 3 is a schematic exploded partial view of a press machine comprising the apparatus of Fig 1; and
Fig 4 is an enlarged scrap view at X in Fig 3.
As illustrated in Figs 1 to 4 of the accompanying drawings the apparatus comprises an open ended drum 1 rotatably held in the bore 2 in the bottom bolster 3 of a press machine. The inner diameter of the drum corresponds to the outer diameter of the laminations (not shown) to be punched out from a feed material 4 by the press machine. The inlet portion of the drum comprises a first ring 5 abutting and fitted to a flange 6 provided at the inlet end of the drum. The first ring describes an inner diameter slightly eccentric to the inner diameter of the drum. The outlet portion of the drum comprises a
4

second ring 7 fitted to the outlet end of the drum and describing a diameter slightly smaller than the inner diameter of the drum. 8 is a third ring fitted to the second ring and
describing a diameter slightly eccentric to the inner diameter of the drum. The inner
diameter of the first ring and third ring is eccentric to the inner diameter of the drum by
0.4mm to 0.6mm with respect to the center of the drum and the inner diameter of
the second ring is smaller than the inner diameter of the drum by 0.02mm to 0.03mm with respect to the center of the drum. The outlet portion of the drum opens into a chute (not shown) for collecting the laminations being punched out by the press machine. The chute is located below the bore in the bottom bolster of the press machine. A drive means comprising a rack 9 and pinion 10 are mounted on a bracket 11 fitted to the bottom bolster of the press machine. A driver gear 12 is mounted on the shaft 13 of the pinion. A driven gear 14 is mounted on the drum in mesh with the driver gear. 15 is a pneumatic cylinder horizontally mounted on two upright members 16,16 on a base 17 extending laterally from the bottom bolster of the press machine. The to and fro linear movement of the rack is provided by the pneumatic cylinder and the movement of the rack in the channel 18 in the bracket 11 is guided by two C - shaped guides 19, 19 fitted on the bracket 10.
During operation of the press machine, magnetic feed material 4 is continuously moved forward and laminations (not shown) are punched out from the feed material by the tool 20 and die 21 of the press machine. The laminations being punched out by the press machine fall down into the bore and the rotating drum in a single file or column as the
adjacent laminations are very close to each other. As the diameter of the ring 5 is slightly
5

eccentric to the inner diameter of the drum and hence the outer diameter of the laminations, the ring interrupts the file of laminations entering the drum and allows only
a group of laminations to enter the drum at a time, Each group of laminations entering the
drum rotates with the drum and falls down into the chute. As the diameter of the ring 7 is slightly smaller than the inner diameter of the drum and hence outer diameter of the laminations, each group of laminations is momentarily retained in the drum and rotates with the drum before falling down into the chute located below the bottom bolster. As the diameter of the ring 8 is slightly eccentric to the inner diameter of the drum and hence outer diameter of the laminations, the laminations being collected in the chute in the form of a stack are prevented from moving up and entering the drum. Since each group of laminations falling down into the drum is rotated before its exit from the drum, the stack formed by the laminations exiting the apparatus of the invention comprises groups of laminations stacked at different orientations thereby reducing the core length variation of the stack. Also manual intervention is not required for making the stator or rotor cores as the whole process is automated. This reduces labour and cost and increases productivity. The apparatus of the invention is simple in construction and easy and convenient to operate.
The drive means can be of a different construction and configuration. Instead of rings the inlet portion and outlet portion of the drum can be differently configured or profiled to perform the respective functions. Such variations in the construction and configuration of the apparatus are obvious to those skilled in the art and are to be construed and understood to be within the scope of the invention.
6

We Claim
1. An apparatus for making the stator or rotor core of an electric motor, the
apparatus comprising an open ended drum rotatably held in the bore in the bottom bolster of a press machine, the drum comprising an inner diameter corresponding to the outer diameter of the laminations to be punched out from a magnetic feed material by the press machine, an inlet portion provided with an inner diameter slightly eccentric to the inner diameter of the drum and an outlet portion comprising two sections, the first section describing an inner diameter slightly smaller than the inner diameter of the drum followed by the second section describing an inner diameter slightly eccentric to the inner diameter of the drum, the outlet portion opening into a chute located below the bore in the bottom bolster of the press machine for collecting the laminations being punched out by the press machine and drive means for rotating the drum.
2. An apparatus for making the stator or rotor core of an electric motor as claimed in claim 1, wherein the inlet portion comprises a first ring abutting and fitted to a flange at the inlet end of the drum, the first ring describing an inner diameter slightly eccentric to the inner diameter of the drum and the first section of the outlet portion comprises a second ring fitted to the outlet end of the drum and describing a diameter slightly smaller than the inner diameter of the drum and the second section of the outlet portion comprises a third ring fitted to the second ring and describing a diameter slightly eccentric to the inner diameter of the drum.
7

3. An apparatus as claimed in claim 1, wherein the inner diameter of the inlet portion and the second section of the outlet portion is eccentric to the inner diameter of the drum by 0.4mm to 0.6mm with respect to the center of the drum and the inner diameter of the first section of the outlet portion is smaller than the inner diameter of the drum by 0.02mm to 0.030mm with respect to the centre of the drum.
4. An apparatus as claimed in claim 2, wherein the inner diameter of the first ring and third ring is eccentric to the inner diameter of the drum by 0.4mm to 0.6mm u-with respect to the center of the drum and the inner diameter of the second ring is smaller man the inner diameter of the drum by 0.02mm to 0.030mm with respect to the center of the drum.
5. An apparatus for making the stator or rotor core of an electric motor as claimed in any one of claims 1 to 4, wherein the drive means comprises a rack and pinion mounted on the bottom bolster of the press machine, a driver gear mounted on the shaft of the pinion and a driven gear mounted on the drum in mesh with the driver gear, the rack being linearly reciprocally held in the bottom bolster of the press machine and a
pneumatic cylinder mounted on the bottom bolster of the press machine horizontally with its piston rod coupled to the rack, the pneumatic cylinder being connected to the


controller of the press machine.
Dated this 5th day of January 2006
8

Abstract
An apparatus for making the stator or rotor core of an electric motor. The apparatus
comprises an open ended drum (1) rotatably held in the bore (2) in the bottom bolster
(3) of a press machine. The drum comprises an inner diameter corresponding to the outer diameter of the laminations (not shown) to be punched out from a magnetic feed material
(4) by the press machine. The drum further comprises an inlet portion provided with an inner diameter slightly eccentric to the inner diameter of the drum and an outlet portion comprising two sections. The first section (7) of the outlet portion describes an inner diameter slightly smaller than the inner diameter of the drum followed by a second section (8) describing an inner diameter slightly eccentric to the inner diameter of the drum. The outlet portion opens into a chute located below the bore in the bottom bolster of the press machine for collecting the laminations being punched out by the press machine. The apparatus also comprises a drive means for rotating the drum (Fig 3).