METHOD OF MANUFACTURING CAGE GEAR BY INVOLVING HOT
FORGING PROCESS
Field of the Invention
The present invention is relating to a method of manufacturing cage for
gear component; wherein the major structural features of the said cage gear
are obtained through hot forging process, (preferably involving Upsetting &
Forming, Center Hole Piercing). The proposed manufacturing process also
involves selectively chosen set of certain successive steps, namely controlled
cooling (continuous furnace/normalization), CNC machining, window piercing,
deburring, VMC, hardening and shot blasting (hanger type).
Background and object of the present Invention:
Cage gear is an important gear component in certain power
transmission system. Particularly in two wheelers, and more particularly in
motor cycles, such cage gear, duly engaging the inner race, plays important
role in the functioning of the engine and power transmission mechanism.
Such case gear component is conventionally manufactured by casting and
complex machining processes. In casting, it mainly involves die casting
process, wherein firstly dies are prepared, then the dies are closed and
molten metal is injected into the dies under high pressure and once the mold
cavity is filled, the pressure is maintained until the casting solidifies. The dies
are then opened and mold cavity is ejected. While after the die casting
process, machining is done for surface refinement and finishing operations to
achieve the final shape and strength in the development of the cage gear.
However, this conventional process of manufacturing cage gear has
certain drawbacks. The die casting process involved in the conventional
manufacturing of cage gear needs high capital cost, while the product quality
and its strength is not satisfactory. A die casted component involves
substantial voids in the Internal structure therein and consequently the
strength of the component is always compromised. In the alternative
machining method, it involves substantial machining operations, leading to
generation of large quantity of wastage material. At the same time, the
machining process is very time consuming, resource involving and it also
does not produce product of enough strength against abrasion because of
cutting and disturbing the internal pattern of metallic lattice structure of the
work-piece. Therefore it is not an economical and preferred process.
Therefore, in the present invention generally a method of
manufacturing cage gear through hot forging method is proposes wherein, the
major structural features of the said cage gear are achieved in single step hot
forging process (preferably by upsetting and forming and performing center
hole piercing too). Further mechanical operations, selected and performed in
stepwise manner are mainly towards achieving other desired and required
structural and functional features in the said cage gear, including window
creation therein, refining and smoothening of the surface profile of the
component.
The main objective of the present invention is to propose to a method
of manufacturing cage for gear component; wherein the major structural
features of the said cage gear are obtained through hot forging process.
Another object of the present invention is to propose a group of
optimized optional/secondary machining operations which is so selected and
performed in stepwise manner, mainly towards achieving desired and
required structural and functional features in the said cage gear, including
window creation therein, refining and smoothening of the surface profile of the
component.
Another object of the present invention is to propose a product, cage
component, which is manufactured by the herein proposed process, involving
the proposed hot forging operation; and wherein the said cage component is
much advanced in its properties like 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 set of closed
dies of suitable dimension, which is applied for performing the said hot forging
operation towards creating the cage gear component of corresponding
dimension of said die-set, wherein said hot forging operation preferably
involve upsetting and forming and simultaneous central hole piercing.
Another object of the present invention is to propose involvement of
selectively chosen set of certain successive steps, namely controlled cooling
(continuous furnace/normalization), CNC machining, window piercing,
deburring, VMC, hardening and shot blasting (hanger type), which are
stepwise performed after performing the said hot forging operation.
Statement of the present invention:
The present invention is intended to propose:
a method of manufacturing cage for gear component; wherein the
major structural features of the said cage gear are obtained through hot
forging process;
a group of optimized optional/secondary machining operations which is
so selected and performed in stepwise manner, mainly towards achieving
desired and required structural and functional features in the said cage gear,
including window creation therein, refining and smoothening of the surface
profile of the component;
a product, cage component, which is manufactured by the herein
proposed process, involving the proposed hot forging operation; and wherein
the said cage component is much advanced in its properties like high stress
bearing capacity, high structural strength, tremendous saving of material,
reduced energy cost, excellent surface finish and higher productivity;
a set of closed dies of suitable dimension, which is applied for
performing the said hot forging operation towards creating the cage gear
component of corresponding dimension of said die-set, wherein said hot
forging operation preferably involve upsetting and forming and simultaneous
central hole piercing; and
Involvement of selectively chosen set of certain successive steps,
namely controlled cooling (continuous furnace/normalization), CNC
machining, window piercing, deburring, VMC, hardening and shot blasting
(hanger type), which are stepwise performed after performing the said hot
forging operation.
Summary of the invention
The present invention is mainly intended to the process of
manufacturing cage gear through hot forging method. The structural features
of cage gear component are mainly achieved during hot forging process only,
wherein the final component obtained is much advanced in its strength, more
resistant to shocks and stresses.
The piece of raw material, suitably separated from the drawn solid bar
is initially subjected to the process of hot forging (Upsetting & Forming and
Central Hole Piercing). Said hot forging operation, mainly forges the solid
metallic piece of the work-piece into a ring of certain inner diameter, as well
as simultaneously it preferably performs the centre hole piercing. This process
increases the diameter of the workpiece by compressing its length, wherein
the workpiece is compressed between two dies in a press. During the said
process of upsetting & forming in hot forging process, the convex shaped
forged work-piece is formed. Subsequently, in one preferred practice of the
proposed hot forging, center hole piercing on the workpiece is achieved by
which the hole is created in the center of the said workpiece and it takes the
desired shape and thickness towards the creation of Cage gear, before
undergoing to the successive steps therein. The designing of closed die plays
an important role in the whole process of hot forging and desired shape
formation therein. The whole process of hot forging is achieved preferably in
Hatebur, which is an automatic hot former machine.
Then the normalization of the said gear 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.
After normalization step, 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).
In the next stage, the said CNC machined workpiece is pierced around
the convex side of the workpiece to give a look of cage. This step is called as
window piercing.
Thereafter the Cage gear component comes to the final shape and
strength after performing proposed steps therein: deburring, VMC machining,
hardening and shot blasting.
The proposed product, due to specific set of manufacturing operations,
including hot forging and other supporting manufacturing processes, is of very
strong internal structure, high abrasion resistant and of high functional
durability.
Detailed description of the invention
Cage is an important gear component in the power transmission
systems, preferably used in the two-wheelers such as motor cycles. The
present invention is relating to a method of manufacturing Cage gear through
hot forging process. The structural features of Cage attained the much
desired 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.
When a hot solid cylindrical workpiece is compressed axially between two
dies, the friction between the workpiece and the dies at their surfaces of
contact causes heterogenous deformation, which in turn produces barreling of
the workpiece as shown in fig. 1.
During this hot forging method of Upsetting and forming, convex shape
forged workpiece/billet is formed. Subsequently, center hole piercing of hot
forging is done to the workpiece, by which the hole is created in the center of
the said workpiece and it takes the desired shape and thickness towards the
creation of Cage gear as shown in fig.2, before undergoing to the successive
stages therein. The designing of closed die plays an important role in the
whole process of hot forging and desired shape formation 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 Cage 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. This multi-station
header that perform operations have also significantly increased heading
production rates 145 SPM.
Although the forged workpiece takes the desired shape towards the
formation of Cage gear in the hot forging process itself, the forged Cage gear
workpiece undergoes several other steps afterwards to provide it more
acceptable features or properties 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.
Thereafter, visual inspection of the normalized billet is done to check
whether during the process of forging, the said billet has achieved required
parameters/properties or not.
After visual inspection, the said workpiece is passed through CNC
machining, wherein certain milling operations are carried out, precisely
controlled and automated via Computer Numerical Control (CNC).
In the next stage, the said CNC machined workpiece is pierced around
the convex side of the workpiece to give a look of cage as shown in fig.3. This
step is called as window piercing.
And later, the Cage gear component comes to the final shape and
strength after performing several stepwise processes therein: deburring,
VMC, hardening, shot blasting, fitting with inner race and final inspection. The
whole process for manufacturing the cage gear component is performed in
automated machines, along with particular set of designed dies.
A schematic flowchart scheme for carrying out the method of
manufacturing Cage gear component is as under:
NEW PROCESS:
RAW MATERIAL
HOT FORGING (Upsetting & Forming, Center Hole Piercing)
CONTROLLED COOLING (CONTINUOUS FURNACE/ NORMALIZING)
VISUAL INSPECTION OF FORGING
CNC MACHINING-1
10
CNC MACHINING -2
WINDOW PIERCING
DEBURRING
VMC
HARDENING (CASE CARBURIZING)
SHOT BLASTING (HANGER TYPE)
FITTING WITH INNER RACE
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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o^-^"- : 3 3 2 ^ 1 We claim: ^ •"»•»
1. A method of manufacturing of cage gear component involving hot
forging operation (upsetting & forming and also central hole piercing),
followed by a group of optimized optional/secondary machining
operations; wherein said method is characterized by obtaining of major
structural features of the said cage gear in said hot forging process.
2. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claiml, wherein said group of
optimized optional/secondary machining operations is so selected and
performed in stepwise manner, that it is characterized by achieving the
final structural and functional features in the said cage gear, particularly
window creation therein, refining and smoothening of the surface
profile of the cage component.
3. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claim 1, wherein said method is
characterized by the advanced and improved properties of the final
cage component product, mainly in terms of comparatively more
compact internal structure, high strength against abrasion, high stress
bearing capacity, excellent surface finish and higher productivity.
4. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claim 1, wherein it involves a set of
closed dies of suitable dimension, which is applied for performing the
said hot forging operation towards creating the cage gear component
of corresponding dimension of said die-set, wherein said hot forging
12
operation preferably Involve upsetting and forming and simultaneoasF HQf 20^
central hole piercing.
5. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claim 1, wherein after performing the
said hot forging operation (upsetting and forming, and central hole
piercing) towards cage preparation, the said method involves stepwise
performance of selectively chosen set of certain successive steps,
namely controlled cooling (continuous furnace/normalization), CNC
machining, window piercing, deburring, VMC, hardening (case
carburizing) and shot blasting (hanger type).
6. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claim 1, wherein said method is
characterized by tremendous saving of material, less resource
involvement and reduced energy cost.
7. A method of manufacturing of cage gear component involving hot
forging operation, as claimed in claim 1, wherein said cage gear
component, optionally of different shape, size, dimension, central
hole size, surface pattern and configuration is manufactured by
the said method involving the hot forging process using suitable
closed die of corresponding optional shape, size, dimension,
central hole size, surface pattern and configuration therein.