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 pressing fixture for pressing stator laminations of a ceiling fan
APPLICANT
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030,
Maharashtra, India, an Indian Company
INVENTOR
Abhijit Zaware and Sonali Sangamkar of Crompton Greaves Ltd, Stamping (M6) Division, B-110, MIDC Industrial Area, Ahmednagar - 414III 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
[001] The present invention relates generally to pressing fixture for pressing stator
laminations of a ceiling fan.
DESCRIPTION OF THE BACKGROUND ART
[002] Pressing fixtures are generally well known for pressing a plurality of stator
laminations or stator packs. Typically, stator laminations are positioned within a central bore of the die mounted over of the fixture and then the laminations are pressed along a pressing axis by a pressing tool. Further, within the central bore a locating pin is also disposed over which the stator laminations are mounted within the central bore. During the pressing operation, the pressing tool strikes the stator laminations with a pressing force thereby allowing the stator laminations to be pressed. It is quite well known that the reason for pressing the laminations is twofold. First, pressing allows the stack of laminations to be matched together due to the lancing operation, the laminations stitched together due to lancing, pressing operation needs for to avoid any unwanted gaps present within the laminations. Unwanted gaps may lead to the increased height of the laminations stack which may be unnecessary from the adaptability point of view in varied applications.
[003] If we are directly press the stator pack without any locating pin it is generally
observed that the stamped stator packs are skewed due to which the overall configuration of the stamped laminations is disturbed. Skewed stamped laminations are highly undesirable and in all possibility are rejected by the local vendors. Further, during pressing operation it is also observed that pressed stator packs are subjected to flaring which is not desirable by the customer. Additionally, once the pressing stroke is over, the pressed laminations are removed manually from the bore of the fixture. Such manual removal after completion of each pressing stroke is

quite a cumbersome job on part of the workman and results in loss of productivity. The above issues encountered during pressing ultimately result in rejection and loss of production.
[004] Thus, there is a need for developing a pressing fixture that at least addresses
some of the above problems.
SUMMARY OF THE INVENTION
[005] Accordingly disclosed herein is a pressing fixture for pressing stator
laminations including a punch holder rigidly mounted on a bottom plate and having an exposed top surface and a bottom surface, the punch holder including a pair of locating pins inserted centrally therein and attached to the bottom surface, a plurality of elongated rods insertable within the punch holder through a peripheral portion of the top surface and fixedly disposed in spaced apart relationship with each other, a spacer plate and a die plate insertable within the plurality of elongated rods for being mounted over the top surface of the punch holder, both the spacer and the die plates having a central opening that defines a central bore when mounted over the punch holder, an ejection mechanism disposed within the central bore including, a resting plate having a central slot that is insertable within the pair of locating pins and positioned within the central bore so as to contact the top surface of the punch holder, the resting plate having a plurality of seating spaces formed thereon, each of the seating spaces holding a vertically oriented biasing member, and an ejector disposed within the central bore and supported over each of the biasing members, the ejector including a pair of openings and a top surface, the top surface supporting the stator laminations that has a pair of openings corresponding to the pair of openings of the ejector, the pair of openings of both the ejector and the stator laminations receivable within the pair of locating pins when assembled within the central bore, the ejector movable from an unbiased position to a biased position within the central bore when impacted by a pressing force, and a pressing member having a pair of passageways attached to a top plate that is axially aligned with the bottom plate and capable of describing a guided reciprocal movement

against the bottom plate when the pressing fixture is in operation, the pressing member cooperating with the die plate to exert a pressing force on the stator laminations along a pressing axis, a portion of the pair of locating pins slidably received within the corresponding passageways when the ejector moves from the unbiased position to the biased position.
[006] According to several embodiments, the size of the resting plate is chosen in
such a manner when disposed within the central bore the resting plate fits within the peripherally arranged plurality of elongated rods and touches an inner surface of the spacer plate.
[007] According to several embodiments, the diameter of the central opening of the
die plate is smaller than the diameter of the spacer plate, and wherein an exposed peripheral portion of a bottom surface of the die plate acts as a stopper to restrict movement of the ejector within the central bore when the ejector moves from the biased position to the unbiased position.
[008] According to several embodiments, a portion of the pair of locating pins
protrudes from the stator laminations when the stator laminations and the ejector is assembled within the central bore, the protruding portion of the pair of locating pins acts as a reference to the pressing member during the pressing operation.
[009] According to several embodiments, the bottom plate further includes a pair of
guide pillars positioned oppositely to the punch holder, and wherein the top plate further includes a pair of guide bushes positioned oppositely to the pressing member, and wherein the guide bushes are insertable within the corresponding guide pillars to provide a guided reciprocal motion to the top plate against the bottom plate during pressing operation.
[0010] It is to be understood that both the foregoing genera] description and the
following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the

invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
A BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above-mentioned and other features and advantages of the various
embodiments of the invention, and the manner of attaining them, will become more apparent and will be better understood by reference to the accompanying drawings, wherein:
[0012] FIG. 1 is a perspective view of a pressing fixture according to an embodiment
of the present invention;
[0013] FIG. 2 is an exploded view of the pressing fixture of FIG. 1;
[0014] FIG. 3 is a perspective elevational view of the pressing fixture of FIG. lin an
open condition;
[0015] FIG. 4 is perspective elevational view of the pressing fixture of FIG. I in a
closed condition; and
[0016] FIG, 5 is a cross-sectional view of the pressing fixture of FIG. 4 in closed
condition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] FIG. 1 shows a pressing fixture 100 that is used for stamping stator
laminations 102 according to an embodiment of the present invention. It should be noted that the embodiments of the present invention are designed to press stator laminations 102 of ceiling fans having stack of thickness of 15mm, However, the pressing fixture 100 may also be used for stamping laminations 102 having other applications and that may have varied thickness and should be construed to be within the scope of the present invention. As seen in FIG. 1, the

pressing fixture 100 is constructed to have a stamping assembly 104 and a pressing assembly 106. The stamping assembly 104 comprises of a flat bottom plate 108 having a punch holder 110 mounted thereon with the help of fasteners 112 (See FIG. 5), The punch holder 110 is preferably mounted in a centre of the bottom plate 108 that also includes a pair of guide pillars 114 disposed on opposite sides of the punch holder 110. The pair of guide pillars 114 and the punch holder 110 is linearly aligned along a length of the bottom plate 108 in a manner as shown in FIG. 1. The guide pillars 114 are rigidly fastened to the bottom plate 108 by usage of fasteners 112 as shown in FIG. 5.
[0018] FIG. 2 shows the punch holder 110 having an exposed surface top surface 116
and a bottom surface that contacts the bottom plate 108 when the punch holder 110 is mounted on the bottom plate 108. Further, the punch holder 110 includes a pair of locating pins 118 insertable within the bottom plate and fixedly attached to the bottom surface of the punch holder 110. One of the locating pins 118 is preferably formed to have a larger cross-sectional area than the second locating pin 118 (See FIG. 1). However, in various other embodiments both the pair of locating pins 118 may be formed to have an equal cross-sectional area and should be construed to be within the scope of the present invention. The pair of locating pins 118 has a length and extends outwardly from the centre of the punch holder U0. Furthermore, the punch holder 110 also includes a plurality of elongated rods 120 that are insertable within the punch holder 110 through a peripheral portion of the top surface 116 and rigidly attached thereto. The plurality of elongated rods 120 extend perpendicularly outside from the top surface 116 of the punch holder 110. Each of the elongated rods 120 are arranged in a spaced apart relationship with each other when inserted within the punch holder 110. Preferably, each of the elongated rods 120 is arranged at equal distance from the adjacent elongated rod 120 and also each of the elongated rods 120 are designed in such a manner that the length of each of the elongated rod 120 extending outside the exposed top surface 116 of the punch holder 110 is equal.

[0019] Through each of the elongated rods 120 a spacer plate 124 having appropriate
matching holes is inserted within the elongated rod and positioned on the punch holder 110. Once the spacer plate 124 is positioned, a die plate 126 that also has appropriate matching holes is inserted within the plurality of elongated rods 120 and positioned over the spacer plate 124 in a manner as shown in FIG. 1. Both the spacer plate 124 and the die plate 126 have central openings 128 formed therein. In one embodiment of the present invention the central opening of the die plate 126 is formed to be relatively smaller than the central opening of the spacer plate 124. The central openings 128 of both the spacer plate 124 and the die plate 126 when mounted over the punch holder 110 define a central bore in which an ejection mechanism may be disposed. Preferably, the punch holder 110. the die plate 126, the spacer plate 124 and the central openings 128 of the spacer and die plates 124, 126 is formed to have circular profile however the circular profile may not be construed to be limiting as various other shapes other than the circular profile may be possible. Such alternatives should be construed to be within the scope of the present invention.
[0020] Reference is now given to FIGS. 2 and 5 that show constructional features of
the ejection mechanism and its arrangement within the central bore. The ejection mechanism includes a resting plate 130 that has a central slot formed therein. Through this central opening, the resting plate 130 is inserted within pair of locating pins 118 and mounted over the top surface 116 of the punch holder 110. Preferably, the size of the resting plate 130 is chosen in such a manner that once the resting plate 130 is positioned within the central bore, peripheral edge of the resting make contact with an inner surface 132 of the spacer plate 124. The resting plate 130 is also preferably formed to have a circular profile so that the resting plate 130 properly fits within the central bore. The resting plate 130 is tied to the top surface 116 of the punch holder 110 within the central through fasteners. A top surface of the resting plate 130 has provisions for

seating spaces within which vertically oriented biasing members, such as compression springs, is positioned.
[0021] Again referring to FIGS. 2 and 5, the ejection mechanism also includes an
ejector 134 that is disposed within the central bore. The ejector 134 is defined by a top surface, a bottom surface and a body 136 that extends between the top surface and the bottom surface. Further, a pair of openings 138 is also formed within the body 136 of the ejector 134 and that extends from the top surface to the bottom surface. Through the openings 138 the ejector 134 is insertable within the pair of locating pins 118 so as to allow the bottom surface to contact each of the biasing members seated on the resting plate 130 in vertical orientation. Further, on the top surface of the ejector 134 the stator laminations are allowed to be seated in a manner as shown in FIG. 2. Preferably, a stack of 91 laminations 102 having a circular profile is taken and joined together before allowing the laminations 102 to be seated on the top surface of ejector 134 within the bore. The laminations 102 also have a pair of openings 138 that corresponds the pair of openings 138 of the ejector 134. Preferably, the length of the pair of locating pins 118are chosen in such a manner that even after positioning the stator laminations 102 on the ejector 134, a portion 140 of the pair of locating pins 118 protrudes outside the stator laminations 102 as shown in FIGS. 2 and 3. Furthermore, the ejector 134 is generally positioned in an unbiased position in which the ejector 134 and the stator laminations 102 are not under the influence of any pressing force that is normally exerted to stamp the stator laminations 102. However, the ejector 134 along with the stator laminations 102 are movable from the unbiased position to a biased position within the central bore when the pressing force us exerted on the stator laminations 102.
[0022] FIG. 3 shows the pressing fixture 100 in open condition in which the pressing
assembly 106 includes a top plate 142 that has a pressing member 144 attached on an exposed surface of the top plate 142. The pressing member 144 is formed of a profile that matches and corresponds to the die plate 126 mounted over the bottom plate 108. Preferably, the pressing

member 144 is formed of a circular profile and includes a pair of passageways exposed on a pressing face 148 of the pressing member 144. Furthermore, a pair of guide bushes 150 is also disposed on opposite sides of the pressing member 144 in a manner as shown in FIG. 3. The top plate 142 is axially aligned with the bottom plate 108 and the guide bushes 150 are inserted within the corresponding guide pillars 114 so as to allow the top plate 142 to describe a guided reciprocal movement against the bottom plate 108 when the pressing fixture 100 is in operation. The top plate 142 may be actuated by some external means (not shown).
[0023] FIG. 4 shows the pressing fixture 100 in closed condition during which the
pressing stroke along a pressing axis takes place. During pressing stroke, the pressing member 144 cooperates with the die plate 126 and exerts the pressing force on the stator laminations 102 along the pressing axis. The pressing surface of the pressing member 144 contacts the top surface of the stator laminations 102. At this point of time, the protruding pair of locating pins 118 acts as a reference to the openings of both the passageways 146. The pair of locating pins 118 is further received within the corresponding passageways 146 of the pressing member 144 when the top plate 142 travels downwards. As a result this, the pressing face 148 of the pressing member 144 pushes the stator laminations 102 on the ejector 134 which is positioned in the unbiased position. However, further application of the pressing force results in downward movement of the ejector 134 to the biased position in which the biasing members are in their compressed state. At this stage the stator laminations 102 are stamped. The benefit of having two locating pins 118 is that during pressing operation, the locating pins 118 ensure that the stator laminations 102 are stamped correctly while minimizing the possibility of skewing which may have been therein with only one locating pin 118. It should be noted that during the entire pressing stroke the ejector 134 as well as the stator laminations 102 slidably move within the pair of locating pins 118. Once the pressing stroke is completed, the top plate 142 moves away from the bottom plate 108 resulting in the pressing member 144 to lose contact with the die plate 126.

So, in the absence of the pressing force the biasing members, which were in their compressed states, by virtue of their properties return to the normal state. Returning of the biasing members to the normal state pushes the ejector 134 within the central bore again to the unbiased position and results in ejection of the stamped stator laminations 102. The stamped stator laminations 102 may be manually received from the ejector 134. This ejection of the stamped stator laminations 102 saves manual labour that was earlier needed to remove the plates to access the stamped stator laminations 102. Thus, work productivity is significantly increased due to this ejection mechanism.
[0024] As noted above and as shown in FIG. 5, the central opening of the die plate
126 is formed to be relatively smaller than the central opening of the spacer plate 124. This difference results in a portion of the bottom surface of the die plate 126 to be exposed within the central bore. The exposed portion sets the unbiased position of the ejector 134 and when the ejector 134 travels towards the unbiased position in the absence of the pressing force, the exposed portion stops further movement of the ejector 134 within the central bore.
[0025] It will be apparent to those skilled in the art that various modifications and
variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim:
1. A pressing fixture for pressing stator laminations comprising:
a punch holder rigidly mounted on a bottom plate and having an exposed top surface and a bottom surface, the punch holder including a pair of locating pins inserted centrally therein and attached to the bottom surface thereof, a plurality of elongated rods insertable within the punch holder through a peripheral portion of the top surface and fixedly disposed in spaced apart relationship with each other;
a spacer plate and a die plate insertable within the plurality of elongated rods for being
mounted over the top surface of the punch holder, both the spacer and the die plates having
a central opening that defines a central bore when mounted over the punch holder;
an ejection mechanism disposed within the central bore including:
a resting plate having a central slot that is insertable within the pair of locating pins and positioned within the central bore so as to contact the top surface of the punch holder, the resting plate having a plurality of seating spaces formed thereon, each of the seating spaces holding a vertically oriented biasing member; and
an ejector disposed within the central bore and supported over each of the biasing members, the ejector including a pair of openings and a top surface, the top surface supporting the stator laminations that has a pair of openings corresponding to the pair of openings of the ejector, the pair of openings of both the ejector and the stator laminations receivable within the pair of locating pins when assembled within the central bore, the ejector movable from an unbiased position to a biased position within the central bore when impacted by a pressing force; and
a pressing member having a pair of passageways attached to a top plate that is axially aligned with the bottom plate and capable of describing a guided reciprocal movement against the bottom plate when the pressing fixture is in operation, the pressing member cooperating with

the die plate to exert a pressing force on the stator laminations along a pressing axis, a portion of the pair of locating pins slidably received within the corresponding passageways when the ejector moves from the unbiased position to the biased position.
2. The pressing fixture according to claim 1, wherein the size of the resting plate is chosen in such a manner that when disposed within the central bore, the resting plate fits within the peripherally arranged plurality of elongated rods and touches an inner surface of the spacer plate.
3. The pressing fixture according to claim 1, wherein the resting plate is bolted to the top surface of the punch holder via fastening members.
4. The pressing fixture according to claim 1, wherein the diameter of the central opening of the die plate is smaller than the diameter of the spacer plate, and wherein an exposed peripheral portion of a bottom surface of the die plate acts as a stopper to restrict movement of the ejector within the central bore when the ejector moves from the biased position to the unbiased position,
5. The pressing fixture according to claim 1, wherein a portion of the pair of locating pins protrudes from the stator laminations when the stator laminations and the ejector is assembled within the central bore, the protruding portion of the pair of locating pins acts as a reference to the pressing member during the pressing operation.
6. The pressing fixture according to claim 1, wherein the bottom plate further includes a pair of guide pillars positioned oppositely to the punch holder, and wherein the top plate further includes a pair of guide bushes positioned oppositely to the pressing member, and wherein the guide

bushes are insertable within the corresponding guide pillars to provide a guided reciprocal motion to the top plate against the bottom plate during pressing operation