Field of the invention
The present invention relates to automobile clutches in general and more particularly to method and apparatus for manufacturing clutch plate having a friction material on the surface of the clutch plate.
Background of the invention
Modern day wet friction clutch plate includes a plurality of spaced adjacent segments made of a suitable friction material that is adhesively bonded on to the two annular surfaces of the friction clutch plate (or core). The wet friction clutch plate further includes channels or grooves between edges of adjacent segments to provide passageways for oil movement for lubrication, between the radially inner and outer portions of the clutch plate. The segments can be asymmetric or symmetric in shape and arrangement.
Many methods are known for manufacturing a wet friction clutch plate. One such conventional method includes subjecting a sheet or a strip of friction material to a cutting operation to provide a predetermined sized cut. The method further includes subjecting the cut to a punching operation to provide an annular friction segment and bonding the annular friction segment to an annular core on the clutch plate. Other methods include feeding the friction material sheet (band or strip) from different directions (e.g. tangential, radial, etc.) towards the friction clutch plate and cutting the frictional material sheet into identical segments and bonding the cut segments onto the annular surface of the friction clutch plate.

Simultaneous cutting and bonding of the friction material segments results in poor quality of friction clutch plates due to lack of accuracy in alignment of the segments and the annular surface, and spreading of minute particles of friction material during the cutting operation. The particles thus generated fall on the core plate resulting in poor bonding of the segments and rough oil grooves surfaces respectively.
In addition, the conventional feeding mechanisms for the cutting and bonding process do not utilize the complete friction material resulting in a poor yield of the process. Furthermore, the cutting process alongside the bonding process increases overall vibrations in the machinery and adds to the manufacturing time. In some of the existing methods, the cutting and bonding operation is performed continuously and sequentially wherein a strip of friction material is cut into segments and each segment is placed on the annular surface of the friction clutch plate. In most of these methods, the manufacturing time becomes almost double considering the time taken for similar operation on the second annular surface of the friction clutch plate.
In cases, where a single apparatus performs the cutting, positioning, and bonding operations, the accuracy tends to be poor due to physical vibrations of the apparatus during the cutting operation. Moreover, the existing methods and systems are less flexible in adopting various shapes and sizes of friction material segments.
Some of the above mentioned shortcomings were addressed by the manufacturing method of friction plate for clutch as disclosed in US Patent no. 6596119. The method included steps of containing plural friction material segments on a surface of a holding body circumferentially and a step of bringing the surface of the holding body and an adhesive coated surface of the clutch plate in close proximity to each other. The method further included

adhering the friction material segment held by the holding body to the adhering surface of the clutch plate.
However, the disclosed method provides lesser degree of freedom for positioning the segments onto the clutch plate. In addition, there is limitation on the number of segments that can be placed onto the surface of the holding body. In certain scenarios, it may be desirable to utilize segments of different shapes and sizes without adding to the cost and complexity of the apparatus. Most importantly, the efficiency of the apparatus and the method depends heavily on the cutting operation that produces segments to be placed over the surface of the holding body. Hence, it is desirable to separate the cutting process from the bonding process in manner such that the manufacturing time is considerably reduced and the yield/efficiency of the method and associated apparatus is further improved.
In order to obviate at least one or more of the aforementioned problems, there is a well-felt need to provide an improved method and system for manufacturing wet friction clutch plate that at least reduces the manufacturing time, increases yield of the process, and provides consistently a high quality clutch plate.
Summary of the invention
The principal object of the present invention is to provide a system and method for manufacturing friction clutch plate in which the cutting operation is separated from the rest of the process.
Another object of present invention is to reduce manufacturing time for friction clutch plates, particularly wet friction plate. Another object of present invention is to provide systems

for a cost efficient manufacture of friction clutch plates wherein segments of different shape and size may be used interchangeably.
It is yet another object of the present invention to provide accurate spacing between adjacent segments of frictional material and different orientations of oil grooves without increasing the complexity of the manufacturing process and the equipment thereof.
Still further object of the present invention is to provide an improved mechanism to feed the segments of friction material in a cost and time effective manner.
Methods and systems for manufacturing a wet friction clutch plate are disclosed. A friction plate typically includes a core plate and a large number of friction material segments adhered to the annular bonding surface in the circumferential direction of the core. Between the adjacent frictional material segments are provided a gap typically referred to as "oil grooves".
According to an embodiment, the method for manufacturing a clutch disc comprising the step of cutting friction material into segments and transferring the segments to a storage. The stored segments are aligned in a substantially vertical direction. The method further includes spraying adhesive on an annular surface of a core plate by an adhesive discharging member and discharging the segments vertically on the annular surface of the core plate while rotating the core plate. Finally the segments are pressed on the core plate to produce clutch disc.
According to another embodiment a system for manufacturing a clutch disc having a core plate and a plurality of friction material segments sequentially bonded thereon is disclosed. The system has a disc holder, an adhesive spraying apparatus and a segment storage apparatus. The disc holder rotateably holds the core plate. The adhesive spraying apparatus have an adhesive discharging member for spraying adhesive on an annular surface of the core plate. The segment storage apparatus includes at least one friction material segments holder for holding the friction

material segments and vertically discharging the segments in a sequential pattern on the annular surface of the core plate, while disc holder rotates the core plate to produce clutch disc. The system may further have a press for pressing the segments on the core plate so as to rigidly attach the friction material segments on the core plate. The disc holder finally ejects the manufactured clutch disc.
Brief Description of the drawings
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings in which:
Fig. 1A, 1B, 1C, and 1D illustrate various views of an adhesive spraying apparatus according to an embodiment of the present invention;
Fig. 2A, 2B, 2C, and 2D illustrate various views of a segment storage apparatus according to an embodiment of the present invention; and
Fig. 3 A, 3B, 3C, and 3D illustrate a various views of a press according to an embodiment of the present invention.
Detailed description of drawings
According to an embodiment, the system for manufacturing a clutch disc having a core plate and a plurality of friction material segments sequentially bonded thereon. Figure la, lb, lc,

and 1d illustrate various views of an adhesive spraying apparatus 100 performing the spraying of adhesive during the manufacture of clutch disc according to an embodiment of the present invention. As shown, a core plate 102 is mounted on a disc holder 104. The disc holder 104 securely holds the core plate and discharge it only once the clutch disc manufacturing process is complete. The disc holder may have a discharging means for discharging the manufactured clutch disc. Further the disc holder 104 is configured to rotate the core plate 102 and move from one apparatus to other as required in the manufacturing process illustrated in henceforth description.
The adhesive spraying apparatus 100 includes an adhesive discharging member 106 that sprays a suitable adhesive through a nozzle 108 onto an annular surface 110 of the core plate 102. The adhesive may include any industry standard adhesives for bonding of friction material segments on the core plate 102. The core plate 102 is continuously rotated by the disc holder 104 while the adhesive is applied on the annular surface 110.
Once the adhesive is applied on the complete annular surface 110 of the core plate 102, the disc holder 104 is relocated from the adhesive spraying apparatus 100 to a segment storage apparatus 200. The various views of the segment storage apparatus 200 are illustrated in figure 2a, 2b, 2c, and 2d according to an embodiment of the present invention. The segment storage apparatus 200 holds pre-cut friction material segments 204.
The pre-cut segments of the friction material are obtained by an independent process of cutting of segments from a friction material such as, but not limited to, strip or band of fiber, cellulose etc. Existing methods and systems may be used for obtaining pre-cut segments. The pre-cut segments are filled into the segment storage apparatus 200 to form a stack of segments. It is to be noted that the pre-cut segments resulting from the cutting operation can be directly fed

to the segment storage apparatus 200 or they may be filled at a separate location to form a pre-filled holding member.
The segment storage apparatus 200 includes at least one holding member 202 that is pre-filled with segments of friction material (e.g. 204). The holding member 202, in an embodiment, corresponds to a hollow chamber of a suitable shape (for e.g. a cylinder or a cuboid) having a first opening to fill the holding member with pre-cut segments of friction material, and a second opening to release a segment of friction material onto the core plate 102. According to an embodiment any number of segments may be stored in one holding member 202. Preferably 100 segments are stored in one holding member 202 at a time.
In one of the implementations, the pre-filled holding member 202 corresponds to a pre-filled magazine of predetermined dimensions to accommodate pre-cut segments of friction material. In addition, the holding member 202 can be isolated and separated from the apparatus (assembly) to enable the pre-filling of segments. Particularly, during operation, a pre-filled holding member 202 can be mounted onto the apparatus 200 by means of a supporting member 206 to replace an empty holding member.
In yet another embodiment the support member 206 may be configured to continuously receive pre-cut segments of the friction material. According to this embodiment the support member 206 continuously fed the friction material to the holding member 202 so as to reduce the production time.
The holding member 202 of the segment storage apparatus 200 is further configured to vertically discharge the segments 204 in a sequential pattern on the annular surface of the core plate on which an adhesive was applied. In an implementation, the process includes positioning the one or more holding members 202 onto the top of the annular surface 110 of the core plate

102. The holding member 202 is usually held in an upright position over the annular surface 110 of the core plate 102 such that one of the first opening of the holding member is positioned just above the annular surface. The positioning further includes orienting the one or more holding member 202 and the core plate 102 such that the segments are accurately placed onto the annular surface 110. For example, in one of the embodiments, the positioning involves rotating the core plate 102 by a pre-determined angle in a clockwise or anti-clockwise direction for receiving the subsequent segment of friction material while keeping the holding member 202 at a fixed position to obtain the sequential pattern. The degree of rotation can be predetermined based at least in part on the number of segments per annular surface and the segment size and shape. The sequential pattern formed on the annular surface 110 has a suitable gap typically referred to as "oil grooves" between two consecutive friction material segments.
It may be appreciated that relative motion (and position) between the holding member 202 and the core plate 102 can be changed by other methods and all such methods can be used without departing from the scope of the ongoing description. For example, the holding member 202 can also be positioned independently above or below the clutch plate to discharge the segments on to the annular surface 110 having adhesive. In an alternative embodiment, one or more holding members (not shown) can simultaneously be employed to discharge multiple segments onto the annular surface of the core plate. In still further implementation, one or more holding members (not shown) can be positioned above and below the friction plate for simultaneously bonding one or more segments on both the annular bonding surfaces of the clutch plate. This has the advantage of reducing the manufacture time by an order of about 15 % to 40 % due to reduction of operational steps & operation shift time.

In yet another embodiment the segment storage apparatus 200 may include a pneumatic control system 208 for applying pneumatic pressure onto the top of the holding member 202 to selectively release a segment of friction material at a time. The released segment falls on the annular surface of the core plate 102 on which an adhesive was applied and get bonded with the core plate 102. It is to be appreciated that the bonding step results in a friction plate with a plurality of segments of friction material placed and bonded onto the annular surface of the core plate 102 on which an adhesive was applied. The pneumatic control system 208 may be configured to apply pressure for bonding the segment on the core plate.
In a successive progression, the method further includes the step of a holistic pressing of the plurality of segments of friction material to securely bond the segments to the annular surface 110 of the core plate 102. Once the friction material segments 204 are bonded on the annular surface 110 of the core plate 102, the disc holder 104 is relocated from the segment storage apparatus 200 to a press 300.
Referring to figure 3a, 3b, 3c, and 3d that illustrate various views of the press 300 that perform the pressing operation according to an embodiment of the present invention. Accordingly, the press 300 includes a pressing component 302 that is mounted onto the press 300 suitably over the core plate having segments of friction material. As shown in the figure, the plurality of segments 204 has been bonded onto the annular surface 110 of the core plate 102. The pressing component 302 mechanically presses d the bonded segments against the core plate 102 thereby fixing the segments securely. In yet another embodiment the press may be operated using pneumatic pressure.
In an alternative embodiment, the method involves simultaneous bonding and pressing operation. In such an embodiment, the one or more holding members 202 bond a plurality of

segments on both the annular surfaces simultaneously. The timing of the bonding on the opposite annular surfaces can be so configured to have simultaneous bonding and pressing of two segments on the opposite annular surfaces by two holding members. In such an embodiment, the pneumatic pressure applied by both the holding members on opposite surfaces of the clutch plate securely fixes the segments onto the surfaces thereby obviating the need for a separate holistic pressing operation. This has an advantage of saving a lot of time in placing (bonding) the plurality of segments individually and pressing the plurality of segments.
According to yet another embodiment, a method for manufacturing a clutch disc is disclosed. The disclosed method includes the step of cutting friction material into segments 204 and transferring the segments to a storage 200. The stored segments 204 are aligned in a substantially vertical direction. The method further includes spraying adhesive on an annular surface of a core plate 102 in by an adhesive discharging member 100 and discharging the segments 204 vertically in a sequential pattern on the core plate 102 while rotating the core plate 102. Finally the segments 102 are pressed on the core plate to produce clutch disc.
Industrial application
The disclosed methods separate the cutting operation from the manufacturing process of the friction clutch plate and hence eliminate the numerous disadvantages associated with an integrated process that involves simultaneous cutting and bonding operation.
In conventional methods, a friction material tape or a band is fed in a tangential direction to a clutch plate and the cutting, bonding, and pressing operations are performed in succession. The disclosed process replaces the cutting blade with the holding member 202, which is pre-filled with the segments. The associated advantage is an easier, faster, and economic method for

manufacturing a friction plate. The disclosed method also replaces the friction material tape or band used in the conventional methods with a pre-cut segment filled in a holding member (e.g. 202) thereby increasing the yield. Further, the automated and independent positioning of the holding member and the rotation of the core plate provides for a precise pre-determined control of placement and profiling of the segments.
Due to the use of the holding member and the separation of the cutting process from the manufacturing process, no fiber/ foreign particle comes in the oil grooves area between the adjacent segments. Moreover, the shape and size of the oil grooves area can be modified by changing the shape of the segments and precisely controlling the positioning of the segments.
In addition, the disclosed method provides for a higher degree of freedom to choose for different shapes of the segment. For example, the shape of the segments may be changed by making modifications in the cutting process without affecting the manufacturing process of the friction clutch plate.
Since, the number of steps is less; the whole process is faster. As discussed earlier, employing a plurality of holding members brings down the manufacturing time. The steps or processes in the disclosed methods can include automation of the spraying of adhesive, positioning of the holding member, rotation of the clutch plate and bonding respectively. Such automation results in very high accuracies in the profiling and placing of the segments and the oil grooves. Moreover, the disclosed method does not need very high operating temperature and hence the working environment is cool and healthy. In an exemplary embodiment, the method can be performed at room temperature.
The disclosed design of the apparatus eliminates any vibrations thus resulting in consistent high quality wet friction clutch plates. The disclosed apparatus also eliminates any

chance of deposition of dusts thus resulting in proper bonding and better oil grooves. The disclosed design also incorporates auto sensors that avoid wastage of material or the clutch plate.
Although the methods have been described with reference to fig. 1, fig. 2, and fig. 3, in the context of apparatus 100, 200, and 300, it may be appreciated that the three apparatuses (100, 200, and 300) can be integrated into a single apparatus for manufacturing friction clutch plate. Therefore, it is to be understood that figures 1, 2, and 3 are illustrative embodiments of the three steps being performed and a single apparatus may perform all the steps as disclosed. In such a case, the three apparatuses 100, 200, and 300 would act as components of the single apparatus.
While certain present preferred embodiments of the invention and certain present preferred methods of practicing the same have been illustrated and described herein, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

We Claim:
1. A system for manufacturing a clutch disc having a core plate (102) and a plurality
of friction material segments (204) bonded thereon, the system comprising:
a disc holder (104) for rotateably holding the core plate (102);
an adhesive spraying apparatus (100) having an adhesive discharging member (106) for spraying adhesive on an annular surface (110) of the core plate (102), while the core plate (102) is rotated by the disc holder (104); and
a segment storage apparatus (200) having at least one friction material segments holder (202) for holding the friction material segments (204) and vertically discharging the segments (204) on the annular surface (110) of the core plate (102) in a sequential pattern to form a clutch disc.
2. The system for manufacturing a clutch disc as claimed in claim 1, further comprises a press (300) for pressing the segments (204) on the core plate (102) so as to rigidly attach the friction material segments (204) on the core plate (102).
3. The system for manufacturing a clutch disc as claimed in claim 1, wherein the disc holder (104) further comprises a discharging means for ejecting the clutch disc.
4. The system for manufacturing a clutch disc as claimed in claim 1, wherein the sequential pattern formed on the annular surface (110) has a suitable gap between two consecutive friction material segments.
5. The system for manufacturing a clutch disc as claimed in claim 1, wherein the friction material segments holder (202) is a removeable cartridge.
6. The system for manufacturing a clutch disc as claimed in claim 1, wherein friction material segments holder (202) holds 100 friction material segments (204) at a time.
7. The system for manufacturing a clutch disc as claimed in claim 1, further
comprises a pneumatic control system associated with the segment storage apparatus (200) for
discharging the segments using a pneumatic pressure.
8. The system for manufacturing a clutch disc as claimed in claim 2, wherein the
press (300) is a pneumatic press.
9. A method of manufacturing a clutch disc comprising the step of:
cutting friction material into segments;
transferring the segments to a storage, such that the segments are stored in a stack;
spraying adhesive on an annular surface of a core plate by an adhesive discharging member while rotating the core plate;
discharging the segments vertically on the annular surface while rotating the core plate; and
pressing the segments on the core plate to produce clutch disc.
10. The method of manufacturing a clutch disc as claimed in claim 9, wherein said
pressing is performed by pneumatic pressure.
11. The method of manufacturing a clutch disc as claimed in claim 9, wherein said discharging of segments is performed by a pneumatic control system.