The present invention relates to a method of bonding a friction facing and carrier plate assembly and to an assembly for use in the method.

The method is to be used in the bonding, using adhesive, of at least one facing of friction material to a side of a carrier plate to form a friction facing and carrier plate assembly which can be used in the construction of a friction clutch driven plate. That driven plate can be of a type for use in a friction clutch interposed between an internal combustion engine and a change-speed gear box in a drive line of a motor vehicle.

Previous bonding methods have involved the use of mechanical or pneumatic means for maintaining the position of the friction facing relative to the carrier plate. This complicates the bonding method and can impair productivity.

It is an object of the present invention to provide a simplified bonding method and an assembly for use therein.

According to a first aspect of the present invention there is provided a method of bonding a friction facing to a side of a carrier plate to form a friction facing and carrier plate assembly, the method comprising; locating the friction facing flat against a base of a recess in a first

platen; applying a layer of adhesive to the exposed surface of the friction facing; locating the carrier plate between the first platen and a second platen; and bringing the first and second platens together so that the carrier plate is urged into contact with the adhesive layer and is bonded to the friction facing; characterised in that a plurality of resilient members are provided between the friction facing and carrier plate, these resilient members being compressed against the friction facing when the first and second platens are brought together, thereby urging the friction facing flat against the base of the recess.

The method may include the step of urging a further friction facing flat against a base of a recess provided in the second platen, resilient members being provided between the carrier plate and the further friction facing and adapted to urge the further friction facing away from the carrier plate and against the base of the recess in the course of the carrier plate being bonded to the further friction facing by adhesive interposed between the further friction facing and the carrier plate.

According to a second aspect of the present invention there is provided a friction facing and carrier plate assembly comprising a carrier plate for rotation about a central axis, a friction facing disposed on a side of the carrier plate and bonded to the carrier plate by a layer of adhesive, characterised in that a plurality of resilient

members are provided between the carrier plate and the facing, the resilient members being held in compression between the friction facing and the carrier plate by the adhesive bond therebetween.

The assembly may comprise first and second friction facings each respectively disposed on first and second opposite sides of the carrier plate and bonded to the carrier plate by respective first and second layers of adhesive, and a plurality of resilient members provided between the carrier plate and the first and second facings, the resilient members being held in compression between the first and second friction facings and the carrier plate by the adhesive bonds therebetween.

The or each friction facing may be annular.

The adhesive may be an elastomer.

The resilient members may extend in the circumferential direction of the carrier plate, preferably with the resilient members extending between radially spaced bead portions of adhesive.

The resilient members may comprise spring fingers extending circumferentially from radially outwardly extending paddles provided at the outer periphery of the carrier plate. The paddles may be alternately provided with spring fingers at

the radially outer portions of the paddles and at the radially inner portions of the paddles. The spring fingers are preferably provided in pairs with the spring fingers being offset axially relative to the plane of the carrier plate in opposite axial directions.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a plan view, partially fragmented, of a friction facing and carrier plate assembly according to one aspect of the present invention;

Figure 2 is a plan view, on a larger scale, of a part of a carrier plate of the assembly shown in Figure 1;

Figure 3 is a partial view, on a larger scale, of the friction facing and carrier plate assembly shown in Figure 1 looking in the direction of the arrow III in Figure 1;

Figure 4 is a plan view of one embodiment a bonding apparatus for performing the method according to the present invention; and

Figure 5 is an elevational view, partly in section, of the apparatus shown in Figure 4.

Referring first to Figures l to 3, a friction facing and carrier plate assembly comprises an annular carrier plate 4 of, for example, metal substantially centered on axis X and having a plurality of resiliently pliable, radial paddles or blades 6 at its outer periphery. The paddles 6 are spaced from each other by radial slots 8. Two friction facings 10,12 each formed by a pliable, integral annulus of friction material, are bonded to opposite sides of the paddles by respective layers 14,14' of adhesive. The adhesive can be an elastomer, for example a room temperature vulcanisable silicone rubber. Each elastomer layer 14,14' is formed by a plurality of radially spaced bead portions of the elastomer. For example the elastomer layer 14 is formed by a plurality of elastomer beads 14A, 14B, 14C, 14D and 14E arranged as radially spaced, substantially concentric circles centred on axis X. The layer 14* is also formed, for example, of elastomer beads in the form of concentric circles.

The carrier plate 4 has apertures 16 to receive rivets (not shown) for securing the assembly to a side plate (not shown) on a central hub of a clutch driven plate incorporating the assembly 2.

As shown in Figures 1 to 3, alternate paddles 6 are provided with circumferentially extending spring fingers 18,20. The paddles 6 provided with spring fingers are alternately provided with fingers 18 at the radially outer

portions of the paddles and with fingers 20 at the radially inner portions of the paddles. The spring fingers 18,20 are provided in pairs with one finger of each pair being positioned radially outwardly of the other finger. As can be seen from Figure 3, the spring fingers 18,20 in each pair are each offset axially relative to the plane of the carrier plate 4 in opposite axial directions. The spring fingers 18,20 therefore act to urge the friction facings 10,12 away from the carrier plate 4 in the axial direction with the spring fingers 18 acting on the radially outer portions of the friction facings and the spring fingers 20 acting on the radially inner portions of the friction facings. As can be seen from Figure 1 , the spring fingers 18,20 extend between adjacent beads of the elastomer layers.

Apparatus useful in the manufacture of the assembly 2, and to ensure that the adhesive layers 14,14' are each of a desired predetermined thickness, is shown at 22 in Figures 4 and 5. The apparatus 22 comprises a circular upper platen 24 which can sit on a circular lower platen 26. The platen 26 has a central bore 28 in which a shank 30 of a cylindrical boss 32 is an interference fit. The platen 26 has a circular land 34 with a flat horizontal surface which surrounds the bore 28. An annular recess arrangement 36 in the platen 26 surrounds the central land 34 and is surrounded by a peripheral, annular land 40.

The upper platen has a central bore 42 which is a sliding fit on the boss 32. The upper platen 24 also has a central circular land 44 with a flat horizontal surface. An annular recess arrangement 46 in the platen 24 surrounds the central land 44 and is encircled by a peripheral, annular land 48.

Four vertical dowels 50 are interference fits in the land 34 and are disposed in respective through vertical bores 52 in the upper platen 24, which bores are a close sliding fit on the dowels. The dowels 50 are all spaced one from another by substantially 90° of arc and are so arranged that when the dowels fit into the bores 52 the recess arrangements 36 and 46 combine to form a substantially continuous and enclosed annular chamber.

Upper platen 24 is provided with a pair of handles 54 so that it can be manually lifted off the lower platen.

To use the apparatus 22 in the manufacture of an assembly 2, the platen 24 is initially lifted off the platen 26 and inverted so that the entrance to the recess arrangement 36 is from above. An annular friction facing 10 is applied flat against the base of the recess arrangement 36 and a layer 14 of adhesive in a paste or flowable form is applied to the facing. A carrier plate is now placed on the lower platen 26 so that its paddles 6 come into contact with the adhesive layer 14. The dowels 50 engage in four of the

holes 16 of the carrier plate which is thus located and held against rotation. A layer 14' of adhesive is applied to the paddles of the carrier plate 4 and an annular friction facing 12 is located and applied to the layer 14* .

Thereafter the platen 24 is lowered onto the lower platen 26. As the platen 24 is lowered, the carrier plate 4 is clamped between the lands 34,44, inwardly of the paddles 6 and lands 40,48, outwardly of the paddles 6. Further, the spring fingers 18,20 provided on the paddles 6 urge the friction facings 10,12 away from the plane of the paddles towards the bases of the annular recess arrangements 36,46 thereby holding the friction facings flat and controlling the thickness of the adhesive layers 14 ,14' . Thus it is preferred that the upper platen 24 is relatively heavy.

Now the adhesive is allowed to set. In the case of the adhesive being an elastomer, for example a silicone rubber, the expression "setting" is to be understood as "curing" or "vulcanising". This may be promoted by exposing the elastomer to an ambient atmosphere of a predetermined character, for example air of predetermined temperature and relative humidity.

When the adhesive has set to the desired extent, the upper platen 24 is lifted off the lower platen 26 leaving behind the newly formed friction facing and carrier plate assembly. The newly formed assembly 2 can then be removed

from the lower platen 26.

The bonded friction facing and carrier plate assembly 2 can be of the kind described in our published European Patent Application No. 0 252 583. The spring fingers 18,20 will provide some cushioning in the finished carrier plate assembly 2, so that as an axial load is applied to the friction facings 12, a degree of compression will be permitted to cushion the load. In the finished carrier plate assembly, the adhesive layers 14,14' will be stretched axially, opposing the resilience of the spring fingers 18,20 tending to force friction linings 12 apart. Consequently the cushioning effect will initially be softer during low loads on initial take up and will harden up as the loads increase and the assembly 2 is compressed and stretching of the adhesive layers 14,14' reduced.

The axial distance between the surface of the land 34 and the base of the recess arrangement 36 and between the surface of the land 44 and the base of the recess arrangement 46 determines the axial thickness of the adhesive layers 14,14' respectively, for a given axial thickness of the friction facings.

It is not essential that a friction facing should be bonded to each side of the carrier plate by way of an elastomer.

A friction facing could be bonded to one side of the carrier plate by a synthetic resin adhesive such as a

phenolic resin adhesive. Further, the friction facing need not be annular, but could comprise, for example, an array of discrete pads of friction material. Moreover, the friction facing need not be bonded directly to the carrier plate by way of the adhesive, but may be bonded to a backing or support plate which is subsequently bonded to the carrier plate.