METHOD OF MAKING DOG HOLE IN GEAR THROUGH HOT
FORGING PROCESS
Technical field of invention :-
This invention relates to a new method for manufacturing Dog Hole in gears through
hot forging process. The unique feature of the present invention is the raw material
receipt, which is the solid metallic bar of certain diameter, from which workpiece of
certain thickness is freshly cut before subjecting it to the proposed hot forging
(upsetting and forming) operation. The process often progressed through a number
of mechanical operations to produce the final product.
Background & Objects of the invention:-
A gear is a rotating machine part having cut teeth, or cogs, which mesh with
another toothed part in order to transmit torque. Two or more gears working in
tandem are called a transmission and can produce a mechanical advantage through
a gear ratio and thus may be considered a simple machine. Geared devices can
change the speed, torque, and direction of a power source. The most common
situation is for a gear to mesh with another gear; however, a gear can also mesh
with a non-rotating toothed part, called a rack, thereby producing translation instead
of rotation.
Some of the gears are fixed and/or machined to the transmission shafts. The
other gears slide or spin on these shafts. The gears that slide back and forth on the
shafts have what are called Dogs. These Dogs are knobs of metal that fit into holes
in the gears beside them, locking the two gears together.
Dog holes are most important and unavoidable mechanical part in the gear
box of automobiles. At present, the dog holes are manufactured by using a method
namely, the VMC [Vertical machining centre] method. This method consists of a
machining centre, with a spindle that is perpendicular to the ground floor. The dog
holes are manufactured by vertical drilling/grinding technology, which is not accurate
and the final product will not get a polished finishing.
At certain instant application of forging operation to the work-piece towards
preparation of dog hole is known, but it is not widely established practice in the
industry due to several reasons. Some of the reasons being the production of final
and finished product with sub-standard structural strength and lesser functional life,
high yield of wastage material, involvement of less economical means and steps in
the said manufacturing, ineffective set of mechanical and secondary operations not
supporting the strength, functioning and life of the final product.
According to the present invention, the dog holes are manufactured by using
an advanced hot forging process, supported an effective and synchronized set of
secondary operations, leading to enhanced structural strength, better functional
features and higher functional life. The proposed method particularly regulates
manufacturing parameters such as temperature range, geometry of raw material,
and quality of die-set in its designing and preparation. The proposed method herein
is also cost effective for mass scale production.
Prime object of the present invention is to propose a novel and advanced Method of
making dog hole in gear through hot forging process, supported by unique set of
stepwise operations towards finishing the product.
Another prime object of the present invention is the application of hot forging
operation to the initially received piece of raw material and performing dog hole
forging on such hot forged work-piece after conditioning it by way of controlled
cooling (continuous furnace/ normalizing), annealing, shot blasting and phosphating.
Another object of the present invention is to propose a novel and advanced set of
operations to be performed in step-wise manner towards production of finished dog
hole component, which is as under:
hot forging (upsetting and forming), controlled cooling, annealing, shot blasting,
phosphating. Dog Hole Forging, drilling, CNC machining, deburring, bobbing,
hardening, shot blasting (hanger type) and honing/hard bore turning.
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said method is primarily characterized
by receipt of raw material as solid metallic drawn bar and creation of Dog Hole
component in hot forging operation (upsetting and forming).
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said hot forging operation towards
producing the Dog Hole is performed using suitable set of closed dies.
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said Dog Hole in Gears is optionally of
different shape, size, dimension, teeth profile, surface pattern and configuration is
manufactured by the said method involving Dog Hole hot forging step using a
suitable closed die of corresponding shape, size, dimension, teeth profile, surface
pattern and configuration therein.
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said method of manufacturing, apart
from its essential steps of controlled cooling, annealing, shot blasting, phosphating,
Dog Hole Forging, drilling, and CNC machining (CNC-1 and CNC-2), involves
secondary operations, namely deburring, bobbing, hardening, shot blasting (hanger
type) and honing/hard bore turning.
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said method of manufacturing is
characterized by manufacture of said Dog Hole components with different optional
dimensions/diameters and optional number of holes of variable dimensions.
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the raw material receipt and the initial
workpiece is characterized by receiving of solid metallic bar (drawn bar) of certain
diameter and cutting the work-piece afresh of certain thickness, before subjecting it
to hot forging (upsetting and forming).
Another object of the present invention is to propose a method of making dog hole in
gear through hot forging process, wherein the said Dog Hole prepared is
characterized by enhanced structural strength, increased stress tolerance and
enhanced working in high temperature environment.
Statement of the present invention:
The present invention is intended to propose:
• a novel and advanced Method of making dog hole in gear through hot forging
process, supported by unique set of stepwise operations towards finishing the
product;
• the application of hot forging operation to the initially received piece of raw
material and performing dog hole forging on such hot forged work-piece after
conditioning it by way of controlled cooling (continuous furnace/ normalizing),
annealing, shot blasting and phosphating;
• a novel and advanced set of operations to be performed in step-wise manner
towards production of finished dog hole component, which is as under:
hot forging (upsetting and forming), controlled cooling, annealing, shot
blasting, phosphating, Dog Hole Forging, drilling, CNC machining,
deburring, hobbing, hardening, shot blasting (hanger type) and
honing/hard bore turning.
• a method of making dog hole in gear through hot forging process, wherein the
said method is primarily characterized by receipt of raw material as solid
metallic drawn bar and creation of Dog Hole component in hot forging
operation (upsetting and forming);
• a method of making dog hole in gear through hot forging process, wherein the
said hot forging operation towards producing the Dog Hole is performed using
suitable set of closed dies;
• a method of making dog hole in gear through hot forging process, wherein the
said Dog Hole in Gears is optionally of different shape, size, dimension, teeth
profile, surface pattern and configuration is manufactured by the said method
involving Dog Hole hot forging step using a suitable closed die of
corresponding shape, size, dimension, teeth profile, surface pattern and
configuration therein;
• a method of making dog hole in gear through hot forging process, wherein the
said method of manufacturing, apart from its essential steps of controlled
cooling, annealing, shot blasting, phosphating. Dog Hole Forging, drilling, and
CNC machining (CNC-1 and CNC-2), involves secondary operations, namely
deburring, hobbing, hardening, shot blasting (hanger type) and honing/hard
bore turning;
• a method of making dog hole in gear through hot forging process, wherein the
said method of manufacturing is characterized by manufacture of said Dog
Hole components with different optional dimensions/diameters and optional
number of holes of variable dimensions;
• a method of making dog hole in gear through hot forging process, wherein the
raw material receipt and the initial workpiece is characterized by receiving of
solid metallic bar (drawn bar) of certain diameter and cutting the work-piece
afresh of certain thickness, before subjecting it to hot forging (upsetting and
forming); and
• a method of making dog hole in gear through hot forging process, wherein the
said Dog Hole prepared is characterized by enhanced structural strength,
increased stress tolerance and enhanced working in high temperature
environment.
Short details of the invention:-
According to this invention, there are several steps are required for the
manufacturing of dog holes. These steps are carried out under controlled conditions
of temperature and pressure. The list of the steps under which the process is
progressed is given below.
R.M. Receipt (Drawn bar)
Raw material as per HMCL Spec
Hot forging (Upsetting & Forming), Hatebur
Controlled cooling (Continuous furnace/
Normalizing)
Annealing
Shot blasting
Phosphating
Dog hole forging
Visual inspection
Drilling
CNC machining 1
CNC machining 2
Deburring
Hobbing
Hardening (Case Carburizing)
Shot blasting (Hanger type)
Honning/ Hard bore turning
Gear rolling
Final Inspection
Oiling & Packing
Storage in finished goods store (FGS)
Despatch
In the proposed method, an alloy of steel is used as the raw material for the
manufacturing of dog holes. Forging (hot forging) method is being used for its
manufacturing, which is easier and cost effective as compared to the existing one.
During hot forging, the temperature reaches above the recrystallization point of the
metal. Using this method, the bar (i.e., the raw material) can give shape using
localized compressive forces. The cross-sectional area of the bar can be enlarged
and reshaped through the process of upsetting & forming. This hot upset forging is
accomplished by confining one end of the said bar and applying pressure to the
other end that is unconfined. This axial pressure, applied by the heading tool, causes
the bar [herein after referred as the work piece/billet] to spread (upset) in a manner
to achieve the desired shape.
Hot forging take place at a high temperature. The billet/ work piece is
heated to obtain a high temperature and then cooled slowly in a controlled way.
Temperature of the work piece is so lowered as to get a particular temperature. The
said work piece is then go through another process called annealing. It is a heat
treatment. The bar is heated to a specific temperature/color and then allowed to cool
slowly. Thus the billet will become softer after annealing. So that it can be cut and
shaped more easily. Annealing increases the ductility of the billet and it will become
more workable. In this process, the said billet is heated to above its critical
temperature, maintaining a suitable temperature. These processes are repeated
along with the upsetting and forming process.
The forging temperature is obtained by using oil or gas fired furnace. And
using the Forging press the hot component will get the desired shape as shown in
thefigure(l).
Upsetting is the process of enlarging and reshaping the cross- sectional area
of the said billet. It is done by confining one end of the said billet and applying
pressure to the other end that is unconfined. This axial pressure applied by the
heading tool causes the bar to spread [upset] in a manner to achieve the desired
shape.
The annealed work piece is then undergoing another process called shot
blasting. It is the process of cleaning the surface with high pressure to remove all
surface contaminants.
The hot bar is fixed at a particular position using heavy metal equipments.
The annealed bar is now press with the suitable die on the upper end (open end).
Now the said bar will get the suitable shape with respect to the die used.
The bar then undergoes a process of phosphating. Phosphate coatings are
used for corrosion resistance, lubricity, or as a foundation for subsequent coatings or
painting. It serves as a conversion coating in which a dilute solution of phosphoric
acid and phosphate salts is applied via spraying or immersion and chemically reacts
with the surface of the part being coated to form a layer of insoluble, crystalline
phosphates.
The produced dog hole is then subjected to visual examination. After that, the
bar will get the required shape and design through the process of drilling, CNC
machining1& CNC machining 2.
Machining is any of various processes in which a piece of raw material is cut
into a desired final shape and size by a controlled material-removal process. The
many processes that have this common theme, controlled material removal, are
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today collectively known as subtractive manufacturing, in distinction from processes
of controlled material addition, which are known as additive manufacturing.
Due to the processes above mentioned, the surface of the billet often creates
ragged edges or protrusions. The raised particles and shavings that appear when
metal blanks are machined are referred to as burrs, so it should be removed. For
that the billet Is applied for the deburring process, which is the process of removal of
such impurities form the surface of the metals after machining processes.
The billet is then undergoing another process called bobbing. It is a machining
process for making gears, splines, and sprockets on a bobbing machine. The teeth
or splines are progressively cut into the work piece by a series of cuts made by a
cutting tool called a hob.
The billet is then applied for another process called hardening. For which, the
billet is heated to a very high temperature. Since the billet is of high quality [high
carbon steel] the hardness is also will become very high after heating. When a very
high heat intensity is applied to the area that to be hardened, the part will become
turn red, then it removed from heat and place direct to cool water. Reheat it until it
turns blue in color, then allow to cool. After these processes, the forged dog hole will
become more hardened.
The product is then shot blasted to remove all impurities from its surface. It is
honed to improve its surface texture. Honing is an abrasive machining process that
produces a precision surface on the work piece by scrubbing an abrasive stone
against it along a controlled path. Honing improves the geometric form of surface of
the work piece and also improve its surface texture. Honing improves a form
characteristic such as roundness, flatness, cylindricity, or sphericity etc.
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Y
The dog hole is then subjected to final inspection by experts. The final product
is then coming under another process called oiling, which helps for lubrication and
then packed and stored carefully.
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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3323Da j 3 r ORIGINAL
We claim:
1 2 NOV 2013
1. Method of making dog hole in gear through hot forging process wherein the
said Dog Hole formation is achieved by hot forging operation to the initially
received piece of raw material and performing dog hole forging on such hot
forged work-piece after conditioning it by way of controlled cooling
(continuous furnace/ normalizing), annealing, shot blasting and phosphating;
and wherein the said method is primarily characterized by following stepwise
operations:
hot forging (upsetting and forming), controlled cooling, annealing, shot
blasting, phosphating. Dog Hole Forging, drilling, CNC machining, deburring,
bobbing, hardening, shot blasting (hanger type) and honing/hard bore turning.
2. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said method for manufacturing the Dog Hole component
is primarily characterized by receipt of raw material as solid metallic drawn bar
and creation of Dog Hole component in hot forging operation (upsetting and
forming).
3. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said hot forging operations towards producing the Dog
Hole is performed using suitable closed dies.
4. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said Dog Hole in Gears is optionally of different shape,
size, dimension, teeth profile, surface pattern and configuration and is
manufactured by the said method involving Dog Hole hot forging step using a
13
T
ORIGINAL 3323DELI3
suitable closed die of corresponding shape, size, dimension, teeth profile,
1 2 NOV 2013
surface pattern and configuration therein. "^
5. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said method of manufacturing, apart from its essential
steps of controlled cooling, annealing, shot blasting, phosphating. Dog Hole
Forging, drilling, and CNC machining (CNC-1 and CNC-2), involves
secondary operations, namely deburring, bobbing, hardening, shot blasting
(hanger type) and honing/hard bore turning.
6. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said method of manufacturing is characterized by
manufacture of said Dog Hole components with different optional
dimensions/diameters and optional number of holes of variable dimensions.
7. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, as claimed in claim 1, wherein the raw material receipt and the initial
workpiece is characterized by receiving of solid metallic bar (drawn bar) of
certain diameter and cutting the work-piece afresh of certain thickness, before
subjecting it to hot forging (upsetting and foiming).
8. Method of making dog hole in gear through hot forging process, as claimed in
claim 1, wherein the said Dog Hole prepared is characterized by enhanced
structural strength, increased stress tolerance and enhanced working in high /
temperature environment.