METHOD OF MANUFACTURING INNER RACE BY INVOLVING HOT
FORGING PROCESS
Field of the invention
The present invention is relating to a method of manufacturing inner race for
gear component to be fitted with cage gear, more particularly to be used in two
wheelers such as motor bikes; wherein the major structural features of the said inner
race are obtained through hot forging process (mainly by Upsetting & Forming,
Center Hole Piercing), and also involving certain successive steps namely controlled
cooling, phosphating, sizing at KP-250 press, CNC machining, deburring, broaching,
hardening, shot blasting, etc.
Background of the invention
Inner race is an important gear component to be used in motor cycle's power
transmission system, which is to be fitted with cage gear. Such gear component is
conventionally manufactured by mainly machining process. The raw material used
herein is forged rings, which undergo series of machining operations.
Conventional Process (Flowchart)
Forged Rings (De-scaled) as Raw material
Center Less grinding
Heat Treatment i
Hardness testing i
~"r- Honing & Super finishing
Ready for dispatch to assembly
However, this conventional process of manufacturing inner race has some
disadvantages. It is too much time consuming process as it involves various steps of
machining operations and thus, there occurs low productivity of said gear.
Furthermore, it does not provide desired strength and also are not capable of bearing
stress. Moreover, wastage of material occurs in the steps of machining operations.
Therefore, the present invention is proposed to the method of manufacturing
inner race gear through hot forging method, wherein the major structural features of
the said inner race are achieved through hot forging process (mainly by upsetting and
forming; center hole piercing), and also involving certain successive steps namely
controlled cooling, phosphating, sizing at KP-250 press, CNC machining, deburring,
broaching, hardening, shot blasting, etc.
The main objective of the present invention is to propose a method of
manufacturing inner race to be fitted in the cage gear, wherein said method mainly
involve hot forging operation (upsetting and forming, including the central hole
piercing).
Another object of the present invention is to propose a method of
manufacturing inner race, wherein the main operation of hot forging is followed by
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certain secondary operations in continuous manner, namely controlled cooling,
phosphating, sizing at KP-250 press, CNC machining, deburring, broaching,
hardening and shot blasting.
Another object of the present invention is to propose a method of
manufacturing inner race, wherein the secondary continuous operations, following the
hot forging therein, are selected and characterized by improving various
structural/functional properties and improving several manufacturing parameters, such
as high stress bearing capacity, high structural strength, tremendous saving of
material, reduced energy cost, excellent surface finish and higher productivity.
Another object of the present invention is to propose a method of
manufacturing inner race, wherein said method is characterized by economical
production of said inner race gear component.
Statement of the invention:
Present invention is intended to propose:
• a method of manufacturing inner race to be fitted in the cage gear, wherein
said method mainly involve hot forging operation (upsetting and forming,
including the central hole piercing);
• a method of manufacturing inner race, wherein the main operation of hot
forging is followed by certain secondary operations in continuous manner,
namely controlled cooling, phosphating, sizing at KP-250 press, CNC
machining, deburring, broaching, hardening and shot blasting;
• a method of manufacturing inner race, wherein the secondary continuous
operations, following the hot forging therein, are selected and characterized by
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improving various structural/functional properties and improving several
manufacturing parameters, such as high stress bearing capacity, high structural
strength, tremendous saving of material, reduced energy cost, excellent surface
finish and higher productivity; and
• a method of manufacturing inner race, wherein said method is characterized
by economical production of said inner race gear component.
Summary of the invention
A process of manufacturing inner race through hot forging method is
disclosed. The structural features of inner race for gear component are mainly
achieved during hot forging process only, wherein the final component obtained is
much advanced in its strength.
The piece of raw material is initially subjected to the process of hot forging
(Upsetting &. Forming, Central Hole Piercing). The metal piece (known as
workpiece/billet herein) is treated preliminary by the Upset forging, by which the
preliminary dimension and shape of the workpiece is achieved. This process increases
the diameter of the workpiece by compressing its length, wherein the workpiece is
compressed between two dies in a press. Subsequently, secondary phase of hot
forging process, i.e. center hole piercing has been subjected on the workpiece, by
which the hole is created in the center of the said workpiece and while having this, it
takes the desired shape and thickness towards the stage of creation of Inner race. The
whole process of hot forging process is done by closed die, in which the designing of
closed die plays an important role in the formation of desired shape therein.
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The hot forging process takes place in Hatebur machine, which is an automatic
hot former machine, in which it is having three dies and feature to allow the
production of 022mm to 067mm parts.
Once the hot forging process is achieved, the normalization of the said
workpiece is done while controlling the cooling temperature of the forged workpiece
such that it supports the various steps thereafter like phosphating, sizing at KP-250
press, CNC machining, window piercing etc.
Then the phosphating of the normalized workpiece is brought about to
improve the corrosion and abrasion-resistance of inner race structure formed.
After the phosphating stage, the said workpiece is sized at KP-250 press for
the purpose of trimming, piercing and bending operations and also for calibrating of
parts after the actual forming operation to meet dimensional tolerances, improve
surface finish and straightness.
In the next stage, the said workpiece is passed through CNC machining stage,
wherein certain milling operations are carried out, precisely controlled and automated
via Computer Numerical Control (CNC).
And later, the Inner race gear component comes to the desired final shape after
performing proposed steps therein: deburring, broaching, hardening and shot blasting,
washing, assembly fitting and final inspection.
Detailed description of the invention
Inner race is an important gear component in the power transmission systems,
preferably used in the two-wheelers such as motor cycles, which is to be fitted with
cage gear component. The present invention is relating to a method of manufacturing
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Inner race through hot forging process. The structural features of Inner race attained
the much desired mechanical properties during the hot forging process itself
Forging is the working of metal into a useful shape by hammering or pressing.
Forging is often classified according to the temperature at which it is performed:
"cold", "warm", or "hot" forging. When a piece of metal is hot forged it must be
heated significantly. The average temperatures necessary for hot forging are:
• Up to 1150 degrees Celsius for Steel
• 360 to 520 degrees Celsius for Al-Alloys
• 700 to 800 degrees Celsius for Cu-Alloys
During hot forging, the temperature reaches above the recrystallization point
of the metal. This kind of extreme heat is necessary in avoiding strain hardening of
the metal during deformation.
The piece of raw material is initially subjected to the process of hot forging
(Upsetting & Forming, Central Hole Piercing). The metal piece (known as
workpiece/billet herein) is treated preliminary by the Upset forging, by which the
preliminary dimension and shape of the workpiece is achieved. This process increases
the diameter of the workpiece by compressing its length. Upsetting of metals is a
deformation process in which a (usually round or cylindrical) billet is compressed
between two dies in a press or hammer.
During this hot forging method of Upsetting and forming, the desired shape of
workpiece/billet is formed. Subsequently, secondary phase of hot forging process, i.e.
center hole piercing has been subjected on the workpiece, by which the hole is created
in the center of the said workpiece and while having this, it takes the desired shape
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and thickness towards the stage of creation of Inner race. The whole process of hot
forging process is done by closed die, in which the designing of closed die plays an
important role in the formation of desired shape therein. With proper designing and
dimension selection, a suitable closed die is prepared and applied for performing the
proposed hot forging process towards the preparation of inner race gear. The whole
process of hot forging is achieved in Hatebur, which is an automatic hot former
machine, in which it is having three dies and feature to allow the production of
022mm to 067mm parts. One adjustment changes the cutter, feed stroke, transfer &
kick out timing function. Quick change set up allow both punch & die components to
be set up & adjusts off-line, so valuable production time is not washed. These
multistation headers that perform operations have also significantly increased heading
production rates 145 SPM.
Although the forged workpiece takes the desired shape towards the formation
of Inner race gear in the hot forging process itself, the forged Inner race gear
workpiece undergoes several other steps afterwards to provide it more acceptable
features for the automobile industries. Hence after the hot forging process, the
normalization of the said workpiece is done while controlling the cooling temperature
of the forged workpiece such that it supports the various steps like CNC machining,
window piercing etc.
Then the phosphating of the normalized workpiece is brought about to
improve the corrosion and wear-resistance of a steel surface.
After the phosphating stage, the said workpiece is sized at KP-250 press for
the purpose of trimming, piercing and bending operations and also for calibrating of
parts after the actual forming operation to meet dimensional tolerances, improve
surface finish and straightness.
In the next stage, the said workpiece is passed through CNC machining stage,
wherein certain milling operations are carried out, precisely controlled and automated
via Computer Numerical Control (CNC).
And later, the Inner race gear component comes to the final shape and strength
after performing proposed steps therein: deburring, broaching, hardening and shot
blasting, washing, assembly fitting and final inspection. The whole process for
manufacturing the inner race gear component is performed in automated machines,
along with particular set of designed dies.
A schematic flowchart for carrying out the method of manufacturing Inner
race gear component is as under:
NEW PROCESS:
RAW MATERIAL
HOT FORGING (Upsetting & Forming, Center Hole Piercing)
CONTROLLED COOLING (CONTINUOUS FURNACE/ NORMALIZING)
PHOSPHATING
SIZING AT KP-250 PRESS
CNC MACHINING-1
CNC MACHINING -2
DEBURRING
BROACHING
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HARDENING (CASE CARBURIZING)
SHOT BLASTING (HANGER TYPE)
WASHING
ASSEMBLY FITTING
FINAL INSPECTION
OILING AND PACKING
STORAGE IN FINISHED GOODS STORE (FGS)
DESPATCH
Scope of the invention:
Although the invention has been described with reference to specific
embodiments, this description is not meant to be construed in a limiting sense.
Various modifications of the disclosed embodiments, 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 spirit or scope of the
present invention as defined.

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We claim: ,^f^*9
1 2 NOV 2013
1. Method of manufacturing inner race to be fitted with cage gear, wherein said
method involve the major structural features of the said inner race are obtained
through hot forging process (mainly by Upsetting & Forming, Center Hole
Piercing), and wherein it also involve successive steps namely controlled
cooling, phosphating, sizing at KP-250 press, CNC machining, deburring,
broaching, hardening and shot blasting; wherein said method is more
particularly for the manufacturing of cage gear to be used in two wheelers
such as motor bikes.
2. Method of manufacturing inner race, as claimed in claim 1, wherein said cage
gear hot forging operation is characterized by Upset forging towards achieving
the preliminary dimension and shape of the work piece applying suitable
closed dies therein and wherein the center hole piercing is simultaneously
performed on the work piece.
3. Method of manufacturing inner race, as claimed in claim 1, wherein said
method for performing an exemplary and preferred operation of hot forging is
carried out in Hatebur machine, which is an automatic hot former machine, in
which it is having preferably three sets of dies and all supportive feature to
allow the production of 022mm to 067mm parts.
4. Method of manufacturing inner race, as claimed in claim 1, wherein the
normalization of the hot forged work piece of inner race is characterized by
controlling the cooling temperature of said forged work piece such that it
supports the various steps thereafter like phosphating, sizing at KP-250 press,
CNC machining, window piercing etc.
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5. Method of manufacturing inner race, as claimed in claim 1, wherein the | 2 NOV 2013
phosphating of the normalized work piece of inner race is characterized by
improving the corrosion and abrasion resistance of inner race structure formed
therein.
6. Method of manufacturing inner race, as claimed in claim 1, wherein the after
the phosphating stage, the work piece of inner race in an exemplary and
optional instance is sized at KP-250 press towards the purpose of trimming,
piercing and bending operations followed by other successive operations.
7. Method of manufacturing inner race, as claimed in claim 1, wherein the said
method is characterized by formation of optional embodiment of the said inner
race, in various optional and different shapes, sizes, dimensions, features
towards functionality of the said inner race, its surface pattern and
configuration therein, manufactured by the present said method involving the
hot forging (Upsetting & Forming, Center Hole Piercing), using suitable dies
of the corresponding optional shapes, sizes, dimensions, features towards
functionality of the said inner race, its surface pattern and configuration
therein.