Title of Invention

AN APPARATUS AND A RING TOOL FOR BURNISHING THE ROOT PORTIONS OF A HEAT-TREATED EXTERNAL GEAR ELEMENT OF A VEHICLE TRANSMISSION

Abstract An apparatus and method for increasing the operating life of a rotating gear element including a plurality of outwardly-projecting gear teeth each having an involute profile, with each gear tooth having a pair of flanks and a pair of generally semi-circular root portions. A ring tool having a plurality of hardened, inwardly-projecting burnishing teeth is employed to plastically deform only the root portions of the gear element being formed, while avoiding contact with the flanks as the gear element is passed through the ring tool. The ring tool also includes a plurality of broaching surfaces or cutting edges for removing excess stock material from the surfaces of the root portions. The ring tool increases the compressive residual stresses in the root portion of the gear element being formed, thereby creating an optimal residual stress profile and greater bending strength within the root portion of the gear element.
Full Text GP-303246-PTT-DLT
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APPARATUS AND METHOD FOR STRENGTHENING GEAR TEETH
TECHNICAL FIELD
[0001] The present invention relates generally to an improved apparatus and
method for isolated burnishing or plastically deforming the root portions only of
external automotive transmission gear elements to thereby increase gear tooth
bending strength.
BACKGROUND OF THE INVENTION
[0002] Gear sets or gear trains are common to mechanical and electro-
mechanical systems requiring rotational motion and power transmission, and are
therefore often utilized in systems ranging in complexity from a simple wrist watch
or wind-up toy to advanced modern automotive transmissions. A gear set consists
of two or more mechanical gear elements. Each gear element is engageable,
meshable, or otherwise matable with at least one other gear element in the gear set
for the purpose of transmitting power and motion between the various gear elements
comprising the gear set. The specific gear element or series of elements chosen for
any given application will largely depend upon the dynamics of the system into
which the gear set is employed, as well as the respective forces or loads to which the
individual gear elements that comprise the gear set are subjected.
[0003] Complex mechanical systems, for example automotive transmissions,
commonly use a planetary gear set or sets comprised of any number of inter-meshed
external gear elements such as sun gears or ring gears, and internal gear elements
such as pinion gears, with the terms "external" and "internal" referring to the
projecting direction of the gear teeth ringing the gear element. Each mating gear
element within a planetary gear set of a transmission has a plurality of mating or
meshing gear teeth, with each gear tooth typically having an involute surface profile.
In an involute profile, contact between mating gear teeth is retained within a flat
plane as the curved flanks of the gear teeth rotatably engage and disengage, thereby
isolating all physical contact between the mating gear teeth to the active or contact

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surface portions of the gear flanks. Positioned between the mating gear teeth are
non-contactable root portions each having a generally semi-circular profile. The
semi-circular profiles of the root portions of involute gear teeth are, as part of the
gear formation step, typically formed by milling or hobbing processes which cut or
remove excess material from the metal gear blanks. While the involute design has
many known inherent advantages, the rotational forces to which the involute gear
elements are subjected are also known to place substantial tensile stress or bending
force on the root portions of the gear tooth.
[0004] Therefore, it is advantageous to strengthen the gear element to prevent
failure from the various stresses applied to thereto. Strengthening typically takes the
form of hardening by way of initial heat-treating of the entire gear element. Heat-
treated gear elements are then commonly subjected to additional finishing steps
applied to shape the surface asperity profile of the gear flanks in order to increase
the overall micro-level hardness of the gear element. Two of the more common
finishing steps are abrasive grinding and shot peening. With abrasive grinding, a
grinding tool is used to mechanically shave or grind the entire profile of the gear
tooth, including the exposed gear root portions. Complete shaving of the entire
gear tooth profile is often considered necessary in order to avoid "steps" or
unevenness along the continuous gear tooth surfaces. Common abrasive grinding
techniques include diamond grinding and, more commonly, cubic born nitride or
CBN grinding. With shot peening, also known as metal bead blasting, metal shot
or small spheres are blasted or shot into the exposed gear surfaces to plastically
deform the impacted surface layers to thereby introduce compressive residual
stresses and increase the micro-hardness of the surfaces. However, because all of
the exposed surfaces of the gear element are equally affected by the bombardment
of metal shot, the asperity profile of the exposed flanks of the gear tooth may be
altered beyond that which is desirable, and, as a result, the gear elements might
have to be subjected to additional finishing steps such as polishing and/or glass-
bead blasting.

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SUMMARY OF THE INVENTION
[0005] Accordingly, an improved gear tooth strengthening method is
provided for increasing the operating life of a gear element having a plurality of
projecting gear teeth. The method includes heat-treating the gear element as a
preliminary step, and then plastically deforming the surfaces of the exposed gear
roots to a predetermined depth without also thereby plastically-deforming the
exposed active surfaces of the gear flanks. In so hardening only the gear roots, the
compressive residual stress of the gear root is increased without changing the profile
of the gear flanks, resulting in improved overall bending strength of the gear tooth.
[0006] In one aspect of the invention, the root hardness of an external gear
element is increased using an improved ring tool having a plurality of hardened,
inwardly-projecting burnishing teeth that are matable with the gear tooth roots of an
external gear element and are operable to impart a predetermined level of plastic
deformation to the root surfaces without thereby touching the exposed gear flanks of
the gear element when the gear element is passed through the ring tool.
[0007] In another aspect of the invention, the improved ring tool is constructed
at least partially of carbide and further has a plurality of broaching surfaces for
qualifying the size of the gear element being formed, with the gear element being
selected from the external gear element group consisting of sun gear and pinion
gear.
[0008] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of
the best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is a schematic illustration of mating gear elements of a
representative planetary gear set;
[0010] Figure 2 is a fragmentary schematic illustration of a mating gear teeth
each having an involute profile and root portions according to the invention;

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[0011] Figure 3 is a schematic perspective illustration of an improved ring tool
and mating gear element according to the invention; and
[0012] Figure 4 is a fragmentary schematic illustration of a burnishing tooth
portion of the improved ring tool.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to the drawings wherein like reference numbers
correspond to like or similar components throughout the several figures, there is
shown in Figure 1 a gear set 10, shown here as a representative planetary gear set,
consisting of a first external gear element 12, a first internal gear element 13, and
a plurality of second external gear elements 14. Although depicted in Figure 1 as a
planetary gear set, gear set 10 may also take the form of, for example, a linear
gear train or a more complex planetary gear set having a greater number of
meshing gears. Meshing first and second external gear elements 12, 14 are shown
in Figure 1 as a representative sun gear and pinion gear, respectively, which will
be used hereinafter for the purpose of explaining the invention. However, the
invention would be equally suitable for any pair of mating gear elements within a
gear set or gear train.
[0014] As shown in Figures 1 and 2, first and second external gear elements
12, 14 have a plurality of gear teeth 16a, 16b, respectively, extending radially
outward from the gear elements 12, 14. Gear teeth 16a, 16b are equally spaced
around the outer perimeter of gear elements 12, 14. Gear element 12 has a
plurality of gear teeth 16a that are mutually meshable or engageable with the
plurality of identical meshable gear teeth 16b of mating gear element 14. Once so
mutually engaged, gear teeth 16a, 16b then cooperate to transmit rotational
motion, as represented by the various arrows 18 in Figure 1. The profiles of gear
teeth 16a, 16b are preferably the involute profile common to vehicle transmissions
and other high-speed, high-stress systems. Such an involute profile is shown in
greater detail in Figure 2.

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[0015] The plurality of gear teeth 16a of gear element 12 each have a pair of
opposing active surfaces or flanks 20a, the flanks 20a encompassing the entire
expanse of contact surfaces between the mating gears. These contact surfaces are
represented in Figure 2 approximately as the line or path AB. Likewise, identical
gear teeth 16b each have a pair of flanks 20b opposable with the flanks 20a of gear
teeth 16a, with the contact surfaces of flanks 20b described approximately by the
line or path CD. Gear element 12 has a generally or substantially semi-circular
root portion 22a having a plastically-deformable root surface 24a, shown as a
dotted line, disposed between each of gear teeth 16a. Likewise, gear element 14
has a preferably identical generally or substantially semi-circular root portion 22b
having a plastically-deformable root surface 24b, shown as a dotted line, disposed
between each of the gear teeth 16b.
[0016] As mating gear teeth 16a, 16b come into direct dynamic contact and
engage, revolve, and subsequently disengage through one complete rotational cycle,
mutual opposing force is brought to bear on the active surfaces or flanks 20a, 20b of
mating gear elements 12, 14, respectively. Bending fatigue may therefore appear
below or radially inward of the flanks 20a, 20b of the respective root portions 22a,
22b due to the mutual opposing force or tensile stress exerted on the flanks 20a, 20b,
as represented by arrows 21a, 21b of Figure 2. Material failure or crack propagation
could result approximately along the direction of arrows 21a, 21b unless roots 22a,
22b of gear elements 12,14 are strong enough to resist the tensile stresses. In
accordance with the invention, therefore, the life of gear set 10 is increased by
hardening the root portions 22a, 22b to create a plastically-deformed root surface
24a, 24b to thereby increase the bending strength of gear teeth 16a, 16b,
respectively, without also thereby contacting the flanks 20a, 20b, and/or altering the
geometry of the flanks 20a, 20b.
[0017] Looking again to Figure 2, gear elements 12, 14, have substantially
semi-circular root portions 22a, 22b, respectively, each having a plastically-
deformable root surface 24a, 24b, as previously described herein. The root
portions 22a, 22b are typically milled or hobbed out of a gear blank during the

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initial gear manufacturing process, with the kinematics of the gear nobbing process
alone typically determining the final geometry of the root portions 22a, 22b. By
contrast, in accordance with the invention, geometry of the root portions 22a, 22b
are determined by broaching and burnishing which isolates hardening to the root
portions 22a, 22b of gear elements 12, 14.
[0018] To isolate hardening to the root portions 22a, 22b, an improved
forming tool or ring tool 30 is provided as shown in Figures 3 and 4. Ring tool 30
preferably has a circular perimeter 28 and a plurality of radially-inwardly
projecting burnishing teeth 32. Referring to Figure 4, each burnishing tooth 32 has
an identical, generally semi-circular and substantially convex hardened forming
surface 38 configured to plastically-deform the opposing root portions 22a, 22b
(Figure 2) and to broach or cut any excess material from the surfaces of mating
root portions 22a, 22b. Plastic deformation is provided generally by forming or
coating the plurality of burnishing teeth 32 from or with material having a suitably
elevated surface hardness relative to the surface hardness of the root portions 22a,
22b of the gear element being formed. Broaching is provided generally by forming
a cutting surface or broaching edge 36 (see Figure 4) along the entirety of the
forming surface 38 of burnishing teeth 32.
[0019] More specifically, the broaching capability of the invention is
provided by a projecting or protruding broaching edge 36 as shown in Figure 4,
the broaching edge 36 spanning approximately the entire span of generally or
substantially semicircular burnishing edge 38 and being configured to remove
excess stock material from the gear element being formed. Preferably, the
broaching edge 36 of each of burnishing teeth 32 is provided by way of a slightly
concave face 44 ringed or surrounded by a suitably sharp cutting surface, as shown
in Figure 4. Removal of excess material is accomplished as the broaching edge 36
cuts, shaves, or broaches material in excess of the center diameter 42 of the ring
tool 30 as the gear element being formed passes through the ring tool 30, as with
representative gear element 12 in Figure 3. Broaching of excess gear element

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material, specifically excess material around the root portions 22a is necessary in
order to prevent damage to the ring tool 30 and/or gear element 12, due to the
presence of excessive material in and around the root portions 22a. Excessive
material may be present in the root portions of the gear elements being formed
such as 22a, 22b of gear elements 12, 14 due to the larger tolerances used in the
formation of the root portions 22a, 22b during manufacturing of the gear blank
(not shown), or the material may be left behind after the initial hobbing process
used to form the root portions 22a, 22b. Also, heat applied during initial hardening
heat treatment may expand and distort the gear blank after formation, increasing
the geometry of the gear element until the geometry is no longer within tolerance.
Because damage may occur to either or both the gear element and ring tool 30 as
the larger than desirable gear element being formed is forced through the ring tool
30, broaching surfaces 36 operable to cut or broach the excess material and
thereby prevent such damage are provided in accordance with the invention.
[0020] Ring tool 30 also provides a burnishing capability and therefore is
appropriately sized and shaped to impart to the gear element to be formed the
desired depth of plastic deformation. In Figure 3, gear element 12 is used as an
exemplary or representative gear, although one skilled in the art will recognize that
gear element 14 or another external gear element may likewise be used as
explained hereinafter. An external gear such as gear element 12 is passable under
an external force appropriate for providing a predetermined level of plastic
deformation to the root surfaces 24a of contacted root portions 22a. The
plastically-deformed layers 24a of root portions 22a of gear teeth 16a, as well as
the plastically-deformed layers 24b of root portions 22b of gear teeth 16b, are
shown as dotted lines in Figure 2. As ring tool 30 performs as a forming tool,
those skilled in the art of tool making would recognize various methods for holding
ring tool 30 stationary with respect to the gear element being formed. For instance,
ring tool 30 may be secured within a manual fixture or within a fixture-portion of a
piece of capital equipment such as a press, while the gear element, such as gear

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element 12 of Figure 3, is moved through the ring tool 30 under a force suitable to
impart the desired level of plastic deformation to the root surface 24a.
[0021] Variables that will affect the final depth of the plastically-deformable
root surfaces 24a, 24b and the geometry of root portions 22a, 22b include both the
relative hardness and the geometrical variance and/or tolerance between the mating
ring tool 30 and the gear element being formed. Ideally, the gear element being
formed is heat-treated prior to burnishing to prevent the loss of the residual stress
benefits of burnishing due to martensitic transformation. Likewise, the amount of
force used to move the gear element through the ring tool 30 is a function of the
desired predetermined level of broaching and/or burnishing, and may be
manipulated to produce the desired surface hardness on the root surface such as
24a of gear element 12. As stated earlier herewithin, to ensure proper hardening of
the root surfaces such as 24a, the ring tool 30, and in particular the plurality of
burnishing teeth 32, are formed of a material having sufficiently greater surface
hardness than that of the gear element being hardened, so as to adequately
plastically deform the root surface 24a, 24b as a result of mutual, forceful contact
between the ring tool 30 and the gear element.
[0022] Preferably, at least the forming surface 38 portion of burnishing tooth
32 is constructed using carbide or a suitable high-speed tool steel having Rockwell
C hardness (RC) of at least approximately 5-10 Rc greater than that of the gear
element being formed. As representative external gear elements 12, 14 are
preferably constructed of 5120 steel or other suitable material having a hardness of
approximately 55-65 RC, the preferred hardness of the mating burnishing teeth 32
is approximately 60-75 RC, although harder burnishing teeth may also be provided
using specialized 75 RC or harder grades of carbide. Non-forming surface 40 of
burnishing tooth 32, describing the expanse of gear tooth surface not including
forming surface 38 and represented approximately by the line traced along the
curve of the burnishing tooth 32 between points E and F in Figure 4, does not
make contact with any surface of the gear element being formed during the

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broaching or burnishing process. Therefore, hardening of non-forming surfaces 40
is not essential, although equal hardening of all material surfaces of ring tool 30 is
desirable in order to ensure the overall structural integrity of the ring tool 30.
[0023] The size of ring tool 30 and the number, shape, and size of burnishing
teeth 32 are dependent on the design of the gear element to be formed. That is, as
ring tool 30 is a tool or mold through which a formed and heat-treated gear
element such as 12 is passed, the geometry of ring tool 30 is configured to match
the geometry of the gear element 12 to be hardened. For example, as shown in
Figure 3, if gear element 12 were to have twenty separate gear teeth 16a, a ring
tool 30 having twenty separate opposing burnishing teeth 32 would be required,
with ring tool 30 being appropriately sized to allow a pre-selected mating gear
element 12 to pass through ring tool 30 under the required force necessary to
affect the desired changes to the root portion 22a.
[0024] As previously discussed herewithin, mating rotating gear elements such
as gear elements 12, 14 create mutual tensile stress which may then manifest itself
as bending fatigue radiating outward from root portions 22a, 22b, respectively.
Each of gear elements 12, 14 possesses a predetermined material strength. If the
tensile stress imparted to the gear tooth 16a, 16b exceeds such material strength,
one or both of the gear elements 12, 14 will fail in the form of crack initiation,
which may then propragate with the continued application of tensile stress. By
adding compressive residual stress to the root portions 22a, 22b of representative
gear elements 12, 14, the strength of material of the gear elements is thereby
increased, with the object of increasing the strength of material to a level above
that of the tensile stress imparted on the mating gear elements 12, 14. The use of
ring tool 30 as herein described produces the required compressive residual stress
in the form of plastic deformation of the root surfaces such as 24a of a gear
element such as sun gear 12 after the gear element 12 has passed through the
improved ring tool 30.

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[0025] Those skilled in the art will recognize that excessive plastic deformation
may damage the gear element, while insufficient plastic deformation will not
produce compressive residual stress levels sufficient to elevate the strength of
material of the gear element enough to prevent damage from bending fatigue. To
strike the desired balance, the preferred depth of plastic deformation of plastically-
deformable root surfaces 24a, 24b in accordance with the invention is
approximately 2 to 5 micrometers (µ). To impart such a level of deformation, the
profile of gear elements 12, 14 after qualifying broaching are approximately 2 to
5µ larger than the profile of the ring tool 30. In this manner, passing the softer gear
element through the harder ring tool 30 will result in the desired 2 to 5µ deformation
of the root portions 22a, 22b.
[0026] While the invention has been described previously herewithin in relation
to an external gear element, those skilled in the art will recognize that the invention
is equally applicable to internal gear elements such as ring gear 13 of Figure 1 by
reversing the orientation of burnishing teeth 32 of ring tool 30, that is, by so
configuring outwardly-projecting burnishing teeth 32 to burnish only the root
portions of the teeth of the ring gear 13.
[0027] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize
various alternative designs and embodiments for practicing the invention within the
scope of the appended claims.

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CLAIMS
1. A method of extending the operating life of a gear element
having a plurality of projecting gear teeth each having a pair of flank portions,
wherein each of said gear teeth further has a substantially concave root portion
positioned between each of said gear teeth, and wherein each said root portion has a
plastically-deformable root surface, the method comprising plastically-deforming
each said root surface to a sufficient depth to thereby increase the bending strength
of said gear teeth without plastically-deforming said flank portions.
2. The method of claim 1, in which said plastically-deforming of
each said root surface includes using a tool having a design and geometry sufficient
upon movement of said gear element with respect to said tool to control the amount
and depth of compressive stress at said root portion by burnishing only said root
portion.
3. The method of claim 2, wherein said tool has a plurality of
projecting burnishing teeth, wherein each of said burnishing teeth contacts a
respective root portion upon said movement, thereby plastically-deforming said root
portions to said sufficient depth.
4. The method of claim 3, wherein said sufficient depth is
predetermined to approximately 2 to 5 micrometers.
5. The method of claim 3, wherein said burnishing teeth have a
surface hardness of approximately 5 to 10 Re greater than the surface hardness of
said root portion.
6. The method of claim 3, wherein said gear element is selected
from the group of external gears consisting of sun gear and pinion gear.

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7. The method of claim 5, wherein said burnishing teeth are
constructed at least partially of carbide.
8. An apparatus for increasing the bending strength of a gear
tooth or a heat-treated gear element having a plurality of outwardly projecting gear
teeth, wherein said gear teeth each have a plurality of root portions each with a root
surface and a plurality of gear flanks, the apparatus comprising:
a ring tool having a plurality of inwardly-projecting
burnishing teeth, wherein said plurality of burnishing teeth are matable with
respective root portions and are operable to plastically-deform the root surface of a
respective root portion to a predetermined depth without contacting said respective
gear flanks when the teeth of said gear element mate with the teeth of said ring tool.
9. The apparatus of claim 8, wherein said gear teeth have an
involute profile, and wherein said root portions have a generally circular profile.
10. The apparatus of claim 8, wherein said burnishing teeth have
a hardness of approximately 5 to 10 Re greater than that of said root portion.
11. The apparatus of claim 8, wherein said burnishing teeth are
constructed at least partially of carbide.
12. The apparatus of claim 8, wherein said gear element is
selected from the group of external gears consisting of sun gear and pinion gear.
13. The apparatus of claim 8, wherein said predetermined depth is
approximately 2 to 5 micrometers.

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14. A ring-tool for burnishing the root portions of a heat-treated
external gear element of a vehicle transmission, the ring tool comprising a generally
circular main ring having a plurality of hardened burnishing teeth projecting radially
inwardly therefrom, wherein said burnishing teeth are operable to impart a
plastically-deformed layer to said root portions when said gear element is passed
through said ring-tool.
15. The ring tool of claim 14, wherein said main ring and/or said
burnishing teeth are at least partially comprised of carbide.
16. The ring tool of claim 14, wherein said plurality of gear teeth
each have an involute profile, and wherein said plurality of gear tooth roots each
have a generally semi-circular profile.
17. The ring tool of claim 14, wherein said external gear element
is selected from the group consisting of sun gear and pinion gear.
18. The ring tool of claim 14, wherein said plastically-deformed
layer is approximately 2 to 5 micrometers.
19. The ring tool of claim 14, wherein the surface hardness of
said burnishing teeth is approximately 5 to 10 RC greater than that of said root
portions.

An apparatus and method for increasing the operating life of a
rotating gear element including a plurality of outwardly-projecting gear teeth each
having an involute profile, with each gear tooth having a pair of flanks and a pair of
generally semi-circular root portions. A ring tool having a plurality of hardened,
inwardly-projecting burnishing teeth is employed to plastically deform only the root
portions of the gear element being formed, while avoiding contact with the flanks as
the gear element is passed through the ring tool. The ring tool also includes a
plurality of broaching surfaces or cutting edges for removing excess stock material
from the surfaces of the root portions. The ring tool increases the compressive
residual stresses in the root portion of the gear element being formed, thereby
creating an optimal residual stress profile and greater bending strength within the
root portion of the gear element.

Documents:

00782-kol-2007-abstract.pdf

00782-kol-2007-assignment.pdf

00782-kol-2007-claims.pdf

00782-kol-2007-correspondence others 1.1.pdf

00782-kol-2007-correspondence others 1.2.pdf

00782-kol-2007-correspondence others 1.3.pdf

00782-kol-2007-correspondence others 1.4.pdf

00782-kol-2007-correspondence others.pdf

00782-kol-2007-description complete.pdf

00782-kol-2007-drawings.pdf

00782-kol-2007-form 1.pdf

00782-kol-2007-form 18.pdf

00782-kol-2007-form 2.pdf

00782-kol-2007-form 3.pdf

00782-kol-2007-form 5.pdf

00782-kol-2007-priority document.pdf

782-KOL-2007-(12-03-2012)-ABSTRACT.pdf

782-KOL-2007-(12-03-2012)-CLAIMS.pdf

782-KOL-2007-(12-03-2012)-CORRESPONDENCE.pdf

782-KOL-2007-(12-03-2012)-DESCRIPTION (COMPLETE).pdf

782-KOL-2007-(12-03-2012)-DRAWINGS.pdf

782-KOL-2007-(12-03-2012)-FORM-1.pdf

782-KOL-2007-(12-03-2012)-FORM-2.pdf

782-KOL-2007-(12-03-2012)-FORM-3.pdf

782-KOL-2007-(12-03-2012)-OTHERS.pdf

782-KOL-2007-ABSTRACT 1.1.pdf

782-KOL-2007-AMANDED CLAIMS.pdf

782-KOL-2007-AMANDED PAGES OF SPECIFICATION.pdf

782-KOL-2007-ASSIGNMENT.pdf

782-KOL-2007-CORRESPONDENCE 1.1.pdf

782-KOL-2007-CORRESPONDENCE.pdf

782-KOL-2007-DESCRIPTION (COMPLETE) 1.1.pdf

782-KOL-2007-DRAWINGS 1.1.pdf

782-KOL-2007-EXAMINATION REPORT.pdf

782-KOL-2007-FORM 1-1.1.pdf

782-KOL-2007-FORM 18.pdf

782-KOL-2007-FORM 2-1.1.pdf

782-KOL-2007-FORM 3 1.2.pdf

782-KOL-2007-FORM 3-1.1.pdf

782-KOL-2007-FORM 5-1.1.pdf

782-KOL-2007-GPA.pdf

782-KOL-2007-GRANTED-ABSTRACT.pdf

782-KOL-2007-GRANTED-CLAIMS.pdf

782-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

782-KOL-2007-GRANTED-DRAWINGS.pdf

782-KOL-2007-GRANTED-FORM 1.pdf

782-KOL-2007-GRANTED-FORM 2.pdf

782-KOL-2007-GRANTED-LETTER PATENT.pdf

782-KOL-2007-GRANTED-SPECIFICATION.pdf

782-KOL-2007-OTHERS 1.1.pdf

782-KOL-2007-OTHERS.pdf

782-KOL-2007-PA.pdf

782-KOL-2007-PETITION UNDER RULE 137.pdf

782-KOL-2007-REPLY TO EXAMINATION REPORT 1.1.pdf

782-KOL-2007-REPLY TO EXAMINATION REPORT.pdf

782-KOL-2007-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf


Patent Number 253089
Indian Patent Application Number 782/KOL/2007
PG Journal Number 26/2012
Publication Date 29-Jun-2012
Grant Date 25-Jun-2012
Date of Filing 21-May-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC
Applicant Address 300 GM RENAISSANCE CENTER DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 GREGORY MORDUKHOVICH 1997 KLINGENSMITH ROAD NUMBER 54 BLOOMFIELD HILLS, MICHIGAN 48302
PCT International Classification Number B21H5/02; B22F3/16
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/462,165 2006-08-03 U.S.A.