FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
A Method For Manufacturing Synchronizing Ring Having External Teeth With Asymmetric Teeth Roofing And A Special Fixture
Bharat Forge Limited
An Indian company registered under the Indian Companies Act, 1956. Mundhwa, Pune - 411036, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the Invention:
The present invention relates to a method of manufacturing a synchronizing ring. In particular, it relates to the method of manufacturing of synchronizing ring having external teeth with asymmetric teeth roofing. More particularly, it relates to machining of the synchronizing ring having external teeth with asymmetric teeth roofing using a general purpose machine preferably 5-axis machining centre.
Background of the invention:
A synchronizing ring is used in transmission system of automobiles for smooth engagement of gears. It synchronizes the rotational speed of two rotating objects like gears by locking them together. It consists of an array of inner or internal splines (4) and outer/external teeth (17A). The array of outer teeth (17A) has symmetric or asymmetric roofing (2). In the case of asymmetric teeth roofing (2), the machining operation for creating asymmetric teeth roofing (2) is carried out on a special purpose external tooth roofing machine. As the asymmetric teeth roofing is difficult to produce on general purpose machines (GPMs), special purpose machines (SPMs) are built for producing synchronizing rings having external teeth with asymmetric teeth roofing only. Understandably, this involves heavy capital investment and increases the space and infrastructure requirement. In case of new development of synchronizing rings with asymmetric teeth roofing, building special purpose machines incur cost that typically hamper their development. Therefore, there is a need to provide a manufacturing method for

producing the synchronizing rings with asymmetric teeth roofing on general purpose machines.
Objects of the invention
It is an object of the invention to provide a method of manufacturing of synchronizing ring having external teeth with asymmetric teeth roofing on general purpose machines such as a 5-axis machine.
It is another object of the invention to provide specially developed fixtures to be used with a general purpose machine such as a 5-axis machine for manufacturing a synchronizing ring having external teeth with asymmetric teeth roofing.
It is a further object of the invention to provide a manufacturing method that achieves required tolerances and accuracy of asymmetric teeth roofing during machining operation on general purpose machines.
Summary Of Invention:
The invented process elaborates a manufacturing process where specially
developed fixtures are used during manufacturing of asymmetric teeth roofing (2)
on the external teeth (17A) of synchronizing ring using a general purpose machine
and thereby eliminating the use of a special purpose external tooth roofing
machine.

In order to achieve the required tolerances and accuracy of asymmetric teeth roofing during machining operation, 5-axis machining centre is used as general purpose machine. Manufacturing process design is developed along with fixtures used during the manufacturing process. CNC programming and 3D CAD model is developed for the manufacturing of synchronizing ring.
Special purpose machines are built for producing synchronizing ring having external teeth with asymmetric teeth roofing. However, such machines require heavy capital investment and elaborate space and infrastructure. The present invention relates to a method of manufacturing a synchronizing ring (1) having external teeth (17A) with asymmetric teeth roofing (2) using a general purpose machine, preferably a 5-axis machining centre, thereby eliminating the need for a special purpose external tooth roofing machine. The invention also discloses special fixture having special features such as an upper stub (16CA) of Fixture-2 (16) for mounting and affixing taper hobbed component (30), and loading diameter (29) of Fixture-2 (16) for mounting Fixture-2 (16) onto the 5-axis machining centre. The Fixture-2 (16) also has tooth locating provision from where tooth roofing (creation of tooth roofing) program will start. To accommodate the tool path during tooth roofing operation, the Fixture-2 (16) has a number of sub-bodies that are cylindrical and conical in shape.
Brief Description of Figures:

Figure 1 shows views of typical synchronizing ring having external teeth with asymmetric teeth roofing. View A shows top view and View B shows the isometric view of the synchronizing ring (1). View C shows the detailed view of the external tooth (17A) of synchronizing ring with asymmetric teeth roofing (2).
Figures 2a and 2b show the details of asymmetric teeth roofing parameters of synchronizing ring
Figure 3 shows the conventional manufacturing method for producing synchronizing ring having external teeth with asymmetric teeth roofing Figure 4 shows the Fixture-1 (15) with taper hobbed component (30) clamped on it
Figure 4a shows the detailed view A of taper hobbed component (30) clamped /located on the Fixture-1 (15).
Figure 5 shows the Fixture-2 (16) with taper hobbed component (30) clamped on it
Figure 5a shows the detailed view B of taper hobbed component (30) clamped/located on the Fixture-2 (16)

Figure 5b shows the top view of taper hobbed component (30) clamped/located on the Fixture-2(16)
Figure 5c shows the isometric view of the Fixture-2 (16) with taper hobbed component (30) clamped on it
Figure 6 shows steps involved in an invented manufacturing method for typical synchronizing ring (1) having external teeth with asymmetric teeth roofing (17A)
Figure 7 shows sub steps involved in an invented asymmetric teeth roofing machining operation for typical synchronizing ring (1) having external teeth with asymmetric teeth roofing
List of Parts
1 - Synchronizing Ring with 7 - Asymmetric Distance Asymmetric Teeth Roofing 25 8 - Flank angle-1
2 - Asymmetric Teeth Roofing 9 - Flank angle-2
3 - Gap 10 - Roofing Top Angle
4 - Internal Spline 11 - Internal Diameter
5 - Face-1 (Synchronizing ring's 12 - Tooth Tip Centerline
top face) 30 13 - Face-3 (Top face of Fixture-
6 - Face-2 (Taper hobbed 1)
component's bottom face)

14-Face-4 (Top face of Fixture- 20 19 - Locating pin
2) 20 - Upper Stub Diameter of
15 - Fixture-1; 15 A - lower body Fixture-2
of Fixture-1, 15B - middle body of 21 - Bolt
Fixture-1, 15C - top body of 22 - Washer
Fixture-1, 15CA - Upper Stub of 25 24 - Face A of Tooth
Fixture-1, 15D- Mounting face of 25 - Face B of Tooth
Fixture-1 26 - Tooth Centerline
16 - Fixture-2; 16A - lower body 27 - Synchronizing ring gear flank
of Fixture-2, 16B-middle body of angle face
Fixture-2, 16C - top body of 30 28 - Fixture-2 mounting holes
Fixture-2, 16-CA - Upper Stub of 29 - Locating stub of Fixture-2
Fixture-2, 16D-Mounting face of 30 - Taper Hobbed Component
Fixture-2 31 - Face-5 (Synchronizing ring's
17 - External Teeth without bottom face)
asymmetric teeth roofing
17A - External Teeth with asymmetric teeth roofing
18 - Lever
Detailed Description of the Invention:
The present invention is applicable to manufacturing method of producing a synchronizing ring (1) with asymmetric teeth roofing (2) on the external teeth

(17A) (see Figure 1) which is used in vehicular transmission systems for shifting the gears through a sleeve and shift lever arrangement for smooth gear changeover.
A typical synchronizing ring (1) with asymmetric teeth roofing (2) on its external teeth (17A) is shown in Figure 1 with view A, B and C. View A shows top view of synchronizing ring (1). View B shows an isometric view of synchronizing ring (1). View C shows one of the external teeth (17A) of synchronizing ring having asymmetric roofing (2). The array of internal/inner splines (4) is present on internal diameter (11) of synchronizing ring as shown in View A and B of Figure 1. Array of external teeth (17A) having asymmetric roofing (2) on outer diameter of synchronizing ring is also shown in View A and B of Figure 1. View C of Figure 1 shows various parameters and features present on each external tooth (17A) having asymmetric teeth roofing (2). There is a gap (3) between two external teeth (17A) having asymmetric roofing (2) of synchronizing ring. Top face and bottom face of synchronizing ring are represented by Face 1 (5) (Refer Figure 1 - View B) and Face-5 (31) (Refer Figure 2b), respectively. These faces play important role in manufacturing of teeth having asymmetric roofing (2) by the invented process. There are some parameters which are related to asymmetric teeth roofed (2) external teeth (17A) of synchronizing ring (1). Figure 2a and 2b show these parameters. These parameters are roofing top angle (10), flank angle-1 (8), flank angle-2 (9) and asymmetric distance (7).

The above mentioned parameters/terminologies are further elaborated with the help of Figure 1, 2a and 2b as follows.
1. Flank angle-1 (8) and Flank angle-2 (9) are the angles which assist in the proper engagement and shifting of the sleeve during change of the gear in transmission system.
2. Flank angle-1 (8) is the angle between tooth tip centerline (12) and face B of tooth (25).
3. Flank angle-2 (9) is the angle between face A of tooth (24) and face B of tooth (25). These angles are achieved by doing machining on the top of tooth along the face width of synchronizing ring (1).
4. Roofing top angle (10) is the angle between Face-5 (31) i.e. synchronizing ring’s bottom face and synchronizing ring gear flank angle face (27).
5. Asymmetric distance (7) is the distance from centerline of synchronizing ring teeth (26) to the Tooth Tip Centerline (12).
Conventionally the synchronizing ring having external teeth with asymmetric teeth roofing is manufactured using manufacturing process as shown in Figure 3. The conventional manufacturing method comprises following steps:
- Turning
- Spline Broaching
- Taper Hobbing of external teeth
- Asymmetric Teeth Roofing on Special Purpose Machine (SPM)
- Heat Treatment

- Grinding the surface (Face-2) below teeth
- Inspection
The inventors realised that developing SPM only for Asymmetric Teeth Roofing can be avoided in case of new development of a synchronizing ring by performing asymmetric teeth roofing operation on a General Purpose Machine (GPM).
The key inventive feature of the present invention is to manufacture the asymmetric teeth roofing (2) on external teeth (17A) of synchronizing ring (1) using general purpose machine with the help of special fixture/Fixture-2 (16) and thereby eliminating the use of special purpose external tooth roofing machine. In one of the embodiment 5-axis machine is used as the general purpose machine.
The invented manufacturing method for the synchronizing ring (1) having external teeth (17A) with asymmetric teeth roofing (2) is as shown in Figure 6. This invented manufacturing method of synchronizing ring (1) with asymmetric teeth roofing comprises following steps:
- Turning
Turning outer diameter and inner diameter from a forged billet to form a turned component. The tooth roofing top angle (10) is maintained during turning operation which leads to the turned component which is effectively rough-machined.
- Broaching

Forming the splines (4) at internal diameter of turned component by broaching to produce broached component
- Taper Hobbing
Forming teeth without asymmetric roofing (17) on outer diameter of broached component by taper hobbing to produce taper hobbed component (30)
- Asymmetric Teeth Roofing
Forming asymmetric teeth roofing (2) on the external teeth (17) of taper hobbed component (30) on a General Purpose Machine with the help of Fixture-2 (16) to produce asymmetric teeth roofed synchronizing ring.
- Heat Treatment
Heat treating the asymmetric teeth roofed synchronizing ring to achieve specified hardness to produce heat treated synchronizing ring
- Grinding
Grinding the heat treated synchronizing ring component’s bottom face i.e. Face-2 (6) to required dimensions to produce synchronizing ring (1)
- Inspection
Final Inspection is done on the synchronizing ring (1) using optical measurement machine instead of CMM. Inspection using CMM requires high level of skill. It is also a time consuming process as

compared to the optical measurement technique, which also provides greater accuracy of measurement.
The synchronizing ring produced using above method meets the final drawing requirements.
In one embodiment, a 5-axis machining centre is used as the general purpose machine (GPM) in asymmetric teeth roofing machining operation.
Parameters like roofing top angle (10), flank angle-1 (8), flank angle-2 (9) and asymmetric distance (7), related to asymmetrical teeth roofing of a synchronizing ring (1), are considered to be critical as they have very small tolerances. These tolerances are difficult to achieve using a general purpose machine. Along with that, performing machining operation for producing asymmetric teeth roofing (2) on external teeth (17A) of a synchronizing ring (1) using GPM, requires 3D CAD model, special tooling/fixtures and CNC programming which is not required in case of SPM. Also, in GPM (5-axis machine), machine spindle can’t move in a direction opposite to top angle of synchronizing ring (1).
These challenges and constraints are overcome by designing special fixture (Fixture-2 (16)) for holding the taper hobbed component (30) during the machining operation for generating asymmetric teeth roofing (2). Also 3D CAD model, CNC programming and special tooling are used on GPM.

In one embodiment, the parameters for asymmetric teeth roofing (2) of synchronizing ring’s (1) external teeth (17A) are as follows.
. Roofing top angle (10) = -4° (±30’),
. Flank angle-1 (8) = 25° (±30’),
. Flank angle-2 (9) = 90° (±1°)
. Asymmetric distance (7) = 1.6 (-0.2).
In first iteration, to perform asymmetric teeth roofing (2) and to achieve the critical parameters of asymmetric teeth roofing (2) mentioned above for a synchronizing ring (1), Fixture-1 (15), as shown in Figure 4, is developed. Fixture-1 (15) has a lower body (15A), a middle body (15B), and a top body (15C), which further has an upper stub (15CA). The lower body (15A) is preferably cylindrical in shape, however, it may be of any polygonal shape. The middle body (15B) is preferably of a conical shape, however, it also may be of any polygonal cross-section. The top body (15C) is preferably of a cylindrical shape with a circular cross-section, however, it also may have any polygonal cross-section. The upper stub (15CA) is also preferably of cylindrical shape, with a circular cross-section. A mounting face (15D) is provided on the Fixture-1 (15), for mounting the mechanism comprising the lever (18) and the locator pin (19). Depending on the size of the mounting face (15D), it may cut across any or all of the three parts (15A, 15B, 15C) of the Fixture-1 (15). The base of the Fixture-1 (15) is so designed as it can be affixed to the 5-axis machining centre. The top

body (15C) of the Fixture-1 (15) is so redesigned as to accommodate the taper hobbed component (30) for the purpose of asymmetric teeth roofing (2).
Figure 4a shows the orientation of the taper hobbed component (30) in assembled condition with the designed Fixture-1 (15). The taper hobbed component’s bottom face or Face-2 (6), is placed over the top face, or Face-3 (13), of Fixture-1 (15) as shown in Figure 4 and Figure 4a. However, in this configuration of Fixture-1 (15), particularly, the cylindrical shaped top body (15C), the GPM’s spindle constraint does not allow manufacturing of the desired tooth top roofing angle (10), i.e. -4°±30’ in finished condition, as the spindle cannot travel in the negative direction. The spindle belongs to the general purpose 5-axis machining centre on which various tools can be mounted. A number of iterations have been verified by trying different resting positions of the taper hobbed component (30) on Fixture-1 (15).
It is observed that the Fixture-1 (15), particularly its top body (15C) needed to be redesigned to achieve critical parameters of synchronizing ring (1) and eliminate the GPM’s spindle constraint by placing the taper hobbed component (30) in inverse position as compared to earlier position shown in Figure 4 and Figure 4a.
For this purpose, Fixture-2 (16) is developed by redesigning the Fixture-1 (15). In particular, the top body (15C) of Fixture-1 (15) is reshaped from its cylindrical shape, having substantially constant diameter, to a conical part having varying diameter. In doing so, the top surface or Face-3 (13) of Fixture-1 (15), which had

a much wider berth to accommodate the taper hobbed component’s bottom face or face-2 (6), becomes the top surface or face-4 (14) of Fixture-2 (16) with a much narrower berth. The resultant Fixture-2 (16) has a lower body (16A), a middle body (16B), and a top body (16C) which also further has an upper stub (16CA), and a mounting face (16D). Of these, the lower body (16A), the middle body (16B) and the mounting face (16D) correspond almost exactly to the respective counterparts in Fixture-1 (15).
The taper hobbed component (30) is placed on the top surface or face-4 (14) of Fixture-2 (16) in inverse position as shown in Figure 5. The inverse position of taper hobbed component (30) on Fixture-2 (16) is achieved by placing taper hobbed component’s top face or the synchronizing ring’s top face, or Face-1 (5), on the top face of Fixture-2, or Face-4 (14), of the Fixture-2 (16) as shown by Figure 5 (and also in Figures 5a and 5c). This is called as inverse positioning of taper hobbed component (30). Figure 5b shows the top view of Fixture-2 (16) with taper hobbed component (30) clamped on it.
The special fixture or Fixture-2 (16) is specifically designed for asymmetric tooth roofing operation on 5-axis machine/machining centre. The special features include provisions such as upper stub (16CA) of Fixture-2 (16) for mounting and affixing taper hobbed component (30), locating stub (29) of Fixture-2 (16) for mounting Fixture-2 (16) onto the 5-axis machining centre. The Fixture-2 (16) also has tooth locating provision from where tooth roofing (creation of tooth roofing)

program will start. To accommodate the tool path during tooth roofing operation, the Fixture-2 (16) has a number of sub-bodies that are cylindrical and conical in shape. The Fixture-2 (16) is mounted on GPM with the help of locating stub (29) located on hollow portion of the bed of GPM having similar diameter as of locating stub (29). The hollow portion is present at the centre of the bed of GPM (5-axis machining centre). The Fixture-2 (16) is then bolted through mounting holes (28) to the bed of GPM.
The details of sequential sub steps performed with the help of 5-axis machine as GPM and Fixture-2 (16), during Asymmetric Teeth Roofing Step of Figure 6, is shown in Figure 7. These are as follows:
1. In the first alignment, the Fixture-2 is placed on the bed of the 5-axis machining centre with the help of locating stub (29) which is located into a recess provided on the bed of GPM (not shown) having similar diameter as of locating stub (29). Next, Fixture-2 (16) is clamped onto the bed of 5-axis machining centre with the help of bolts or any other known clamping arrangement. Then the 5-axis machining centre’s probe identifies the position of Fixture-2 (16) which is clamped on its bed and confirms that Fixture-2 (16) is positioned correctly. First alignment is completed here.
2. In the second alignment, taper hobbed component (30) is clamped on the Fixture-2 (16). The Face-1 (5) of taper hobbed component (30), which remains unchanged in synchronizing ring (1) also, is placed on Face-4 (14) of the Fixture-2 as shown in Figure 5, 5a, 5b and 5c. During this

placement, internal diameter (11) of taper hobbed component (30), which remains unchanged in synchronizing ring (1), and upper stub diameter (20) of Fixture-2 (16) share same centerline. After this, the gap (3) between two consecutive teeth (17) of taper hobbed component (30) is located using locating pin (19). The locator pin’s (19) diameter is equal to the gap (3) between the two teeth. In one embodiment of present invention, the pin diameter is 4.5 mm. The locating pin (19) is lifted up to verify the gap between the two consecutive teeth (17) of taper hobbed component (30). If the gap (3) is found ok (which means both the gap (3) and diameter of locating pin (19) have same dimensions) then the locating pin (19) will be positioned between the two teeth of taper hobbed component (30). This locating pin (19) is attached to the lever (18) and the lever (18) is attached to Fixture-2 (16). The second alignment is completed here.
3. In third alignment, the probe of 5-axis machining centre ensures proper position of the gap (3) before clamping taper hobbed component (30). The taper hobbed component (30) is then clamped to Fixture-2 (16) by using bolt (21) and washer (22). The taper hobbed component (30) is said to have proper alignment when the tool attached to 5-axis machining centre is able to enter into the gap (3) to start the machining. The third alignment ensures machining of taper hobbed component (30) using a machining tool which will start from the gap (3).
4. The CNC program for creating asymmetric roofing (2) on all teeth (17) present on taper hobbed component (30) is generated and provided as an

input to 5-axis machining centre. Rough and finish Machining is started from the oriented gap (3) between two teeth (17) to complete the asymmetric tooth roofing (2). An end mill of 1.5 mm diameter is used as tool in rough and finish machining operation to perform the asymmetric teeth roofing. The asymmetric teeth roofed synchronizing ring is produced after rough and finish machining. In this step, the tooth roofing parameters such as Roofing Top Angle (10), Flank angle-1 (8), Flank angle-2 (9) and Asymmetric Distance (7) are achieved within the required tolerances.
It is evident that the invention has a number of embodiments.
In the preferred embodiment of the invention, a method is disclosed for manufacturing synchronizing ring (1) with external teeth (17A) having asymmetric teeth roofing (2). The synchronising ring has a top face (5) and a bottom face (31). The method comprises the steps of:
a. turning an outer diameter and an inner diameter from a forged billet to
form a turned component;
b. spline broaching of the internal diameter of the said turned component
to produce a broached component with splines (4) at internal diameter;
c. forming external teeth (17) without asymmetric roofing on said outer
diameter of said broached component using taper hobbing operation to
produce a taper hobbed component (30);

d. carrying out asymmetric teeth roofing (2) on the external teeth (17) of
taper hobbed component (30) to produce a asymmetric teeth roofed
synchronising ring (1) with external teeth (17A) having asymmetric
teeth roofing (2);
e. heat treating said asymmetric teeth roofed synchronizing ring (1) with
asymmetric teeth roofing (2) to produce a heat treated synchronizing
ring;
f. grinding the bottom face (6) of said heat treated synchronizing ring to
produce a finished synchronizing ring (1);
g. inspecting the finished synchronising ring (1) for desired accuracy.
In particular, the aforementioned step d is carried out using a general purpose machine.
In another embodiment of the invention, the aforementioned general purpose machine is a 5-axis machining centre.
In yet another embodiment of the invention, the aforementioned general purpose machine is provided with a Fixture-2 (16), wherein said Fixture-2 has a lower body (16A), a middle body (16B), a top body (16C), a upper stub (16CA), a mounting face (16D), and a locating stub (29), and wherein said top body (16C) is conical in shape having a top surface (14) on which said top face (5) of said taper

hobbed component (30) rests during said step d, and wherein on said mounting face (16D), the lever (18) and locating pin (19) are mounted.
In a still further embodiment, it is disclosed that the step d of the method of the preferred embodiment has the following sub-steps:
i. carrying out a first alignment, wherein a Fixture-2 (16) is placed by positioning a locating stub (29) provided on said Fixture-2 (16) in alignment with a recess provided on the bed of said 5-axis machining centre and then clamped onto the bed of 5-axis machining centre with help of bolts or any other known clamping arrangement;
ii. carrying out a second alignment, wherein said taper hobbed component (30) is concentrically placed around the upper stub (16CA) of said Fixture-2 (16) and the gap (3) between two consecutive teeth (17) of said taper hobbed component (30) is located by a locator pin (19) mounted on said Fixture-2 (16) using a lever (18);
iii. carrying out a third alignment, whereby location of said gap (3) is so positioned as to accommodate a machining tool into said gap (3), following which said asymmetric teeth roofing (2) on external teeth (17) of the taper hobbed component (30) is carried out
In another embodiment of the invention, the invention discloses that the aforementioned step d is carried out to produce a synchronising ring (1) with asymmetric teeth roofing, said teeth having a roofing top angle (10), a flank

angle-1 (8), a flank angle-2 (9), and an asymmetric distance (7) between Tooth Centreline (26) and taper tooth tip centreline (12).
In a further embodiment of the method disclosed herein, it is disclosed that the lower body (16A), and said middle body (16B) of the aforementioned Fixture-2 (16) are cylindrical and conical in shape respectively.
In a further embodiment of the invention, the Fixture-2 (16) is disclosed for mounting on a 5-axis machining centre and thereby carrying out the method of the preferred embodiment. As is evident from the foregoing disclosure, the Fixture-2 (16) has a lower body (16A), a middle body (16B), a top body (16C), and a mounting face (16D), and wherein said top body (16C) is conical in shape having a top surface (14) on which said top face (5) of said taper hobbed component (30) rests during said step d, and wherein on said mounting face (16D) is mounted the lever (19), and wherein said top body (16C) has a protruded upper stub diameter (20).
It is further disclosed that the lower body (16A) of the Fixture-2 (16) is substantially cylindrical in shape and that the middle body (16B) is substantially conical in shape.
In another embodiment, depending on the size of the mounting face (16D), it may cut across any or all of the three parts (16A, 16B, 16C) of the Fixture-2 (16)

Advantages of the invention:
During the development stage of newly designed synchronizing ring with asymmetric teeth roofing, need of special purpose machine is eliminated by using general purpose machines and fixtures developed. This saves cost and time in procuring and building the Special purpose machine and establishing the process on it. The tolerances achieved using invented process are accurate and precise which ensured the smooth gear changeover in transmission assembly.

We claim:
1. A method for manufacturing synchronizing ring (1) having external teeth (17A) with asymmetric teeth roofing (2), said synchronising ring having a top face (5) and a bottom face (31), characterised in that said method comprises the steps of:
a. turning an outer diameter and an inner diameter from a forged billet
to form a turned component;
b. spline broaching of the internal diameter of the said turned
component to produce a broached component with splines (4) at
internal diameter;
c. forming external teeth (17) without asymmetric roofing on said
outer diameter of said broached component using taper hobbing
operation to produce a taper hobbed component (30);
d. carrying out asymmetric teeth roofing (2) on the external teeth (17)
of taper hobbed component (30) to produce a asymmetric teeth
roofed synchronising ring (1) with external teeth having
asymmetric teeth roofing (17A);
e. heat treating said asymmetric teeth roofed synchronizing ring (1)
with asymmetric teeth roofing to produce a heat treated
synchronizing ring;
f. grinding the bottom face (6) of said heat treated synchronizing ring
to produce a finished synchronizing ring (1);
g. inspecting the finished synchronising ring (1) for desired accuracy;

wherein said step d is carried out using a general purpose machine.
2. The method as claimed in claim 1, wherein said general purpose machine is a 5-axis machining centre.
3. The method as claimed in claim 2, wherein said general purpose machine is provided with a Fixture-2 (16), wherein said Fixture-2 (16) has a lower body (16A), a middle body (16B), a top body (16C), a upper stub (16CA), a mounting face (16D), and a locating stub (29), and wherein said top body (16C) is conical in shape having a top surface (14) on which said top face (5) of said taper hobbed component (30) rests during said step d, and wherein on said mounting face (16D), the lever (18) and locating pin (19) are mounted.
4. The method as claimed in claim 1 to 3, wherein said step d has the following sub-steps:
i. carrying out a first alignment, wherein a Fixture-2 (16) is placed by positioning a locating stub (29) provided on said Fixture-2 (16) in alignment with a recess provided on the bed of said 5-axis machining centre and then clamped onto the bed of 5-axis machining centre with help of bolts or any other known clamping arrangement;
ii. carrying out a second alignment, wherein said taper hobbed component (30) is concentrically placed around the upper stub (16CA) of said Fixture-2 (16) and the gap (3) between two consecutive teeth (17) of said taper hobbed component (30) is located by a locator pin (19) mounted on said Fixture-2 (16) using a lever (18);

iii. carrying out a third alignment, whereby location of said gap (3) is so positioned as to accommodate a machining tool into said gap (3), following which said asymmetric teeth roofing on external teeth (17) of the taper hobbed component (30) is carried out
5. The method as claimed in claim 1 to 4, wherein said step d is carried out to produce a synchronising ring (1) with asymmetric teeth roofing (2), said teeth (17A) having a roofing top angle (10), a flank angle-1 (8), a flank angle-2 (9), and an asymmetric distance (7) between Tooth Centreline (26) and taper tooth tip centreline (12).
6. The method as claimed in claim 3, wherein said lower body (16A), and said middle body (16B) are cylindrical and conical in shape respectively.
7. A Fixture-2 (16) for mounting on a 5-axis machining centre, characterised in that said Fixture-2 (16) has a lower body (16A), a middle body (16B), a top body (16C), and a mounting face (16D), and wherein said top body (16C) is conical in shape having a top surface (14) on which said top face (5) of said taper hobbed component (30) rests during said step d, and wherein on said mounting face (16D) is mounted the lever (19), and wherein said top body (16C) has a protruded upper stub diameter (20).
8. The Fixture-2 (16) as claimed in claim 7, wherein said lower body (16A) is substantially cylindrical in shape.
9. The Fixture-2 (16) as claimed in claim 7 and 8, wherein said middle body (16B) is substantially conical in shape.

10. The Fixture-2 (16) as claimed in claim 7 to 9, wherein depending on the size of the mounting face (16D), it may cut across any or all of the three parts, namely, said lower body, middle body and top body (16A, 16B, 16C).