Technical field of the present invention:
The present invention relates to a method for manufacturing gear, particularly Spur gears or straight-cut gears to be used in motor cycles; wherein the whole structural features of said gear, along with its teeth pattern therein, is achieved in continuous multi-stapes on hot former. Though the forged ingot achieves all its structural features in the forging stage only, it is further subjected to a series of optional auxiliary operations towards strengthening and smoothening of structural features and surface pattern thereof, including the teeth pattern of the said gear component.
Background and object of the present invention:

Gears are important auto components, being used in the engine transmission of motor cycles. Spur gears are the most commonly used gear type. They are characterized by teeth which are perpendicular to the face of the gear. Spur gears are by far the most commonly available, and are generally the least expensive.
Due to conventional processes of the production of gear, the said auto component is associated with certain types of drawbacks, such as more consumption of resources and time; involvement of various machining steps towards formation of the central hole as well as formation of teeth profile; formation of substantial amount of wastage material etc.
Due to multiple machining operations, the grain or the internal structure of the work piece gets affected and therefore properties like very high stress bearing capacity, corrosion resistance, high temperature tolerance and very high structural strength etc. get adversely affected.

Due to involvement of large number of machining tools in the preparation of gear, a number of instrumental errors, work-piece handling errors and incidental errors are possible, which mainly depend on the expertise of tool designing and proper handling of various operations thereafter. These unintentional errors, involved in the production of gear, become reasons for accidental breakdown of the said gear, much prior to the expected life of the gear component.
Application of single step forging process for the production of Gear is not conventionally being practiced, mainly due to following reasons:
(i) Technical complications in die designing for commercial production of the said component;
(ii) Non-achievement of ideal forging conditions for producing commercially acceptable gear;
(iii) Involvement of so many dimensional aspects of the said auto component of various size range, namely the central hole creation, size optimization of the said component, teeth formation etc., which are difficult to consider in one single standardized process, mainly towards achieving all required and preferred structural and functional features of the said auto component.
Therefore the present invention is mainly intended to propose a manufacturing method, which mainly involve multi station hot former towards production of the auto component gear, wherein the process further involves supporting secondary steps after accomplishing said forging towards gear teeth formation, such as control, CNC machining, dog hole milling, deburring, hobbing (optional as per gear class accuracy “less than din class11”), hardening (case carburizing), shot blasting, honing/hard part turning and gear rolling. The said invention proposes a gear through hot former auto component, which is much advanced in its properties in comparison to the similar conventional auto components

prepared through conventional processes, namely in terms of very high stress bearing capacity, corrosion resistance, high temperature tolerance and very high structural strength etc.
The main object of the present invention is to manufacture a gear by involving multi station hot former, mainly in the teeth formation therein and with performing hobbing (optional) and deburring processes; and therefore the said produced gear is expected to have much advanced properties like yield improvement, better thermal and mechanical properties, very high stress bearing capacity, corrosion resistance, high temperature tolerance and very high structural strength etc.
Another prime object of the present invention is to propose a new method of manufacturing gear through multi station hot former, wherein the said method primarily involve billet cutting, upsetting and gear tooth forming towards creation of teeth in the said gear component, followed by secondary operations, namely control operation, CNC machining, dog hole milling, deburring, hobbing (optional as per gear class accuracy “less than din class11”), hardening (case carburizing), shot blasting, honing/ hard part turning, gear rolling in step wise manner; and wherein the said method proposed herein involve the optional hobbing operation towards teeth formation in the said gear component.
Further other object of the present invention is to propose a new die, suitable for hot former towards manufacturing of a gear through multi station hot former of variable range of desired shape, size, dimension, surface pattern and configuration, as being produced herein.

Description of the present invention:

Gears are used extensively for transmission of power. They find application in automobiles, gear-boxes, oil engines, machine tools, industrial machinery, agricultural machinery, geared motors etc. To meet the strenuous service conditions the gears should have

robust construction, reliable performance and high efficiency, economical and long life. Gears should be fatigue free and free from high stresses to avoid their frequent failures. The gear drives should be free from noise, chatter and should ensure high load carrying capacity at constant velocity ratio. To meet all the above conditions, the gear manufacturing has become a highly specialized field.
The present invention describes a new method for manufacturing a gear through hot former, which achieve the gear teeth formation by multi station hot former using a suitably designed new closed die and involve the optional hobbing operation for the same. After forging, the work piece is subjected to other supporting operations like control operation, CNC machining, dog hole milling, deburring, hobbing (optional as per gear class accuracy “less than din class11”), hardening (case carburizing), shot blasting, honing/hard part turning, gear rolling are performed in stepwise manner.
This hot former have three dies and feature to allow the production of Ø22mm to Ø67mm 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 multi station headers that perform operations have also significantly increased heading production rates 145 SPM.
Hot forging provides a means for the economical production of certain automotive parts designs. The production & capabilities of this machine is produce all type of automotive transmission gear blanks, bearing rings, lug gears blanks, inner race, cam lobe, which having below 700gm weight & diameter is Ø67mm. The dies are usually designed up to the internal pressure of 2000N/mm2. The temperature of billet is 1150°C to 1250° C at forging time & water is using for cooling of dies. The profile accuracy & surface finish is excellent, so that we always forged gear banks inner profile as forged & maintain tol. In hot forging within
±00.15

The raw material, that is the piece of steel billet, after inspection undergoes hot/warm forming wherein, using a suitable closed die of preferred size and dimension of the gear through multi station hot former, the main body of the gear with teeth is forged and prepared. Due to such gear with teeth making process, the whole set of conventional processes involved in gear making and teeth creating activities get eliminated or completely changed. The present invention uses optional hobbing operation, followed by case carburizing, shot blasting, honing/hard part turning and gear rolling, mainly due to performing hot forging operation towards creating all necessary structural features of said gear through hot former in forging only. The schematic chart representing the set of steps involved in the present proposed manufacturing method is depicted in figure1.
After billet cutting, upsetting is performed; it increases the diameter of the work-piece by compressing its length. The initial work-piece is usually wire or rod, but some machines can accept bars up to 25 cm (9.8 in) in diameter and a capacity of over 1000 tons. The standard upsetting machine employs split dies that contain multiple cavities. The dies open enough to allow the work-piece to move from one cavity to the next; the dies then close and the heading tool, then moves longitudinally against the bar, upsetting it into the cavity.
Apart from above forging process as well as other supportive processes, certain additional gear making processes are performed towards finalizing the gear with teeth component, which are mainly CNC machining, dog hole milling, deburring, hobbing, case carburizing, shot blasting and honing/hard part turning. These additional steps performed towards making of present gear with teeth further enhance the structural features, performance and life of the said gear with teeth component.
With proper designing and dimension-selection pertaining to dog hole diameter and tooth length/shape/orientation etc.; a suitable closed die is prepared and applied for performing the proposed process towards preparing the present gear through hot former.

Case hardening is usually done after the part in question has been formed into its final shape. Carburizing basically is a heat treatment process in which iron or steel is heated in the presence of another material (in the range of 900 to 950 °C (1,650 to 1,740 °F)) which liberates carbon as it decomposes. Depending on the amount of time and temperature, the affected area can vary in carbon content. Longer carburizing times and higher temperatures lead to greater carbon diffusion into the part as well as increased depth of carbon diffusion.
In shot blasting or abrasive blasting stage, the work piece undergoes smoothening of its rough surface, shaping of the surface and removal of surface contaminants therein. A pressurized fluid, typically air, or a centrifugal wheel is used to propel the media in the operation.
The honing/hard part turning is the process of hardening the surface of metal, often low carbon steel, by infusing elements into the material's surface, forming a thin layer of a harder alloy.
The description of the invention is further depicted in firgure1 as under:

Figure 1: It is a schematic chart diagram, representing the major steps like Inspection of Raw Material (Steel), Billet Cutting, Upsetting, Gear Tooth Forming (Hot Part Former), Control operation, CNC Machining, Dog Hole Milling, Deburring, Hobbing (Optional As Per Gear Class Accuracy “Less Than Din Class11”), Hardening (Case Carburizing), Shot Blasting, Honing/Hard Part Turning and Gear Rolling operations towards creation of central hole and teeth pattern formation in the said gear therein.
Figure 2: It depicts the Gear teeth in hot forging. Figure 3: It depicts the CNC machining in DIN 11.
Figure 4: It depicts the optional hobbing Machined in Din 9.

Figure 5: It depicts the front cross-sectional view of finished gear formed through hot/warm forging process.

Figure 6: it depicts the side cross-sectional view of finished gear formed through hot/warm forging process.
Scope of the present 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.

We claim:
1. A Process of Gear Manufacturing involving Hot/Warm Forging, towards forming teeth pattern on the circumferential surface of its gear section at the outer diameter therein, wherein such forging operation is performed on hot former in automation towards making of the gear with all structural and functional features;
Wherein said method basically involves:

a) cutting of billet in automation and its transfer for heating/warming upto desired temperature suitable for hot/warm forging;
b) upsetting the hot/warm billet on first forging station followed by its hot/warm forging towards complete gear formation; and
and wherein said method is characterized by:

• Saving of raw material upto 25%;

• improved yield and structural/functional quality of said gear;

• 2~3 times fatigue life improvement in said gear w.r.t. those gears made by other conventional methods;
• improved material grain flow structure for said gears;

• improved thermal and mechanical properties;

• optimized gear train transmission ration and weight;

• improvement in the life of hob cutter involved therein; and

• reduced cycle time in said gear hobbing to maintain upto DIN 8~10.

2. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein it involves hot forming of the initial billet piece towards creating the gear blank, which is created around the central hole and central axis therein.
3. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein said operation applies a suitable closed die for creating structural features

like central hole, teeth profile and other major surface elevations/depressions of the said gear component.
4. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein it is characterized by obviating the application of machining operations like teeth shaping and hobbing (optionally as per gear class accuracy “less than DIN class 11) mainly towards creating teeth pattern on the circumferential surface of the gear section on its outer diameter herein by stepwise operations.
5. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein after completion of forming the complete gear is subjected to continuous step-wise finishing operations, mainly involving CNC machining, case carburizing, shot blasting and honing/hard part Turning and gear rolling.
6. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein multi station headers that perform operations have also significantly increased heading production rates 145 SPM.
7. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein the dies are usually designed up to the internal pressure of 2000N/mm2. The temperature of billet is 1150°C to 1250° C at forging time & water is using for cooling of dies. The profile accuracy & surface finish is excellent, so that it always forged gear banks inner profile as forged & maintain tol. In hot forging within ±00.15.
8. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein the said gear and its teeth profile, optionally of different shape, size, dimension, central hole size, surface pattern and configuration is manufactured by the said method involving suitable closed die of corresponding optional shape, size, dimension, central hole size, surface pattern and configuration therein during the said hot forging (upsetting and forming).

9. A Process of Gear Manufacturing involving Hot/Warm Forging, as claimed in claim

1, wherein the said method is characterized by structural and functional properties of the said manufactured gear with teeth component, mainly in terms of its yield improvement, increased life of cutter, reduced cycle time in gear hobbing to maintain upto DIN8~10, better material grain flow structure for gears, improved thermal and mechanical properties, high stress bearing capacity, corrosion resistance, high temperature tolerance and high structural strength.