For purposes of this specification, the term"wheel frame" shall be used to denote the portion of a road wheel without a tyre, and without a hub bearing arrangement.

The invention is expected to be particularly advantageously applicable to motorcycle wheels, especially two-wheeled motorcycle wheels with which corners are negotiated by"leaning into the corner", i. e. without imparting substantial lateral forces via the wheels.

The kind of wheelframe to which this invention relates is conventionally formed generally of first and second side members in the form of shells of moulded synthetic polymeric material, each side member including a rim formation at an outer periphery thereof, a hub formation at an inner periphery thereof, and a plurality of circumferentially spaced spoke portions extending outwardly from the hub formation to the rim formation ; the spoke portions, in cross-section, being complementary convex to be closable onto each other in pairs to form hollow spokes.

The side members are secured side by side i. e. coaxially and the rim and the hub are formed, thus providing a wheel with hollow spokes.

in accordance with a first aspect of this invention, there is provided a method of moulding a wheel frame of synthetic polymeric material, the method including the steps of forming spoke members, ultimately to provided spokes for the wheel frame, by wrapping each of a plurality of elongate-intensifiers of predetermined shape and size and of a resilient, thermo-expanding material in layers of reinforced, resin pre-impregnated moulding material, leaving at least one end open; arranging the spoke members in a mould and integrating the spoke members with moulding material such as to form a rim toward a radially outer circumference of the mould, and such as to form a hub member toward a radial centre of the mould ; curing the moulding while in the mould under high temperature and high pressure, and causing the intensifiers to expand to compress the wrapped material around the intensifiers between an outer surface of each intensifier and a complemental mould surface; removing and reclaiming the intensifiers intact via said at least one open end after curing.

Said open end may preferably be at a radially inner end of each spoke.

Arranging the spoke members in the mould and integrating the spoke members with moulding material toward the centre of the mould may include forming a central aperture into which said open ends open, removing the intensifiers then being via said central aperture.

Each intensifier is in the form of an intensifier assembly which includes an elongate limb and at least one locking insert adjacent an end of the limb, removing each intensifier then including initially removing said locking insert and then removing the limb. Removing the intensifier may advantageously, conveniently, include stretching each component forming the intensifier longitudinally to cause it to shrink or contract laterally to facilitate removal.

Advantageously, further to facilitate removal, each limb may be a composite limb, comprising a plurality of superimposed layers or laminates, the method including stretchingly removing the individual layers or laminates in sequence.

In accordance with the above method, the wheel frame is produced as a one-piece or unitary or integral moulding. It is to be appreciated that the spokes are the only components which are hollow.

It is thus a feature of this invention that during curing in the mould under high temperature and high pressure, the spoke walls-are supported against the thermo-expanding intensifiers causing the walls to be subjected to pressure without risking collapsing the spoke walls.

In accordance with a second aspect of the invention, there is provided a method of forming a motor vehicle wheel frame, of the general kind to which this invention relates, including forming the wheel frame as a one-piece or unitary moulding by way of laying up resin impregnated fibre reinforced layers in a first side portion or side portions of a mould to form a first side of the wheel ;

laying up resin impregnated fibre reinforced layers in a second side portion or side portions of the mould to form a second side of the wheel, the first and the second sides being mating sides ; wrapping spoke core or intensifier bodies in resin impregnated fibre reinforced layers ; locating the wrapped spoke core or intensifier bodies in operative positions on either one of the first or the second side members respectively in spoke defining recesses provided for this purpose in the respective side portion or side portions of the mould ; mating the first and the second side members with the located spoke core or intensifier bodies therebetween by operatively securing the two side portions of the mould together ; wrapping resin impregnated fibre reinforced layers circumferentially around the mated side members on a rim defining recess defined by the operatively intersecured side portion or side portions of the mould to form a rim; curing the assembly thus formed under high pressure and high temperature; and removing the spoke core or intensifier bodies and splitting the moulds only after curing of the assembly.

Typically, curing may take place at a temperature of about 120 C and a pressure of about 600kPa.

Wrapping the spoke core or intensifier bodies in the resin impregnated fibre reinforced layers may include causing the layers of said

material to extend outwardly beyond operatively outer ends of said bodies, the method then including making circumferentially spaced cuts in the outwardly extending portions of said material and splaying open said portions to interleave said material laid up in the rim defining recess and said material wrapped around the side members, thereby to enhance bonding of the rim to the spokes.

Locating the spoke core or intensifier bodies in the spoke defining recesses may include checking operatively inner ends of the bodies against inward and tangential movement. The method may include restricting radially outward movement of the spoke core or intensifier bodies, by means of their particular shapes, for example by having the spoke forming portions and the spoke defining recesses tapering radially outwardly.

The method may include forming a hub cavity by means of located, operatively inner ends of the spoke core or intensifier bodies.

The method may include removing the spoke core or intensifier bodies by withdrawing them inwardly into the hub cavity.

In accordance with a third aspect of this invention, there is provided a motor vehicle wheel frame in the form of a moulding of fibre reinforced synthetic polymeric material, which wheel frame includes an outer, circular rim of channel section for seating a tyre in use; a plurality of hollow spokes extending inwardly from the rim; and a concentric, central hub cavity at inner ends of the spokes, and providing hub mounting formations for mounting components which will

form a hub in use, in which the moulding is a one-piece or unitary moulding.

The spokes may be curved. The spokes may be tapered toward the rim.

The hub mounting formations may be in the form of central, c-axial apertures in opposing faces of the hub cavity.

In accordance with a fourth aspect of this invention, there is provided a moulding assembly for moulding a motor vehicle wheel frame as a one-piece or unitary or integral moulding, the moulding assembly including a circular wheel mould split into side portions closable onto each other, one side portion of which, in use, will be a mould lower part and the other side portion a mould upper part, each side portion including an outer, circular rim formation defining a rim recess; a plurality of spoke portions extending inwardly from the rim formation and defining respectively spoke portion recesses; a concentric, central hub mounting formation at inner ends of the spoke portions and defining a hub recess; securing formations for securing one side of the mould to the other side of the mould in use; and a plurality of spoke core or intensifier bodies generally complemental to and locatable with annular clearance within the spoke portion recesses.

The moulding assembly may include a locating or locking arrangement for locating the spoke core or intensifier bodies, when in the spoke portion recesses, against inward and tangential movement. The locating arrangement may include a locating shoulder provided by a periphery of a central protuberance fast with one of the mould parts, conveniently the mould lower part, the shoulder being arranged for abutment by operatively inner ends of the intensifier bodies in use, thereby locating them against inward movement. The locating arrangement may thus include a round cylindrical, or polygonal, sleeve complemental to and placeable on the protuberance. The mould upper part may then provide a central, round cylindrical recess for receiving the sleeve when the mould sides are closed on to each other.

The locating arrangement may include separate locking or locating inserts snugly, removably insertable inbetween the inner ends of adjacent spoke core or intensifier bodies to restrict said bodies against inward and tangential movement.

The spoke portions of the two sides of the mould may extend curvingly toward the hub mounting formations. The spoke portions may taper toward the rim formations.

The spoke core or intensifier bodies may be of a thermo expansive material and may advantageously be re-usable. They may be in the form of mouldings.

Inner end portions of the spoke core or intensifier bodies may be extended, having tongue-like inner ends, the extended portions defining, partially, a hub cavity and locating the bodies against outward movement toward the rim in use, said tongue-like inner ends preventing withdrawl of the bodies inwardly into the hub cavity unless said inner ends are deformed.

The spoke core or intensifier bodies may be of composite structure, being lengthwise split to form laminates to facilitate damage- free withdrawal thereof from a moulded wheel frame in use.

The locking or locating inserts may define, partially, a hub cavity, and may be withdrawable inwardly into the hub cavity.

The locking or locating inserts may be of a material similar to that or identical to that of the spoke core or intensifier bodies, and may be in the form of mouldings. They may be re-usable.

Further in accordance with the invention, broadly, there is provided a method of moulding a fibre reinforced, synthetic polymeric wheel frame comprising an outer rim, an inner hub and hollow spokes extending generally radially from the hub to the rim, the method including the steps of locating intensifiers of resilient, heat expanding material in the hollow spokes by means of locking inserts intermediate radially inner end portions of the inserts which inserts project from radially inner ends of the spokes, expanding the intensifiers to compress moulding material forming walls of the spokes against mould surfaces during curing,

removing the locking inserts after curing and resiliently, stretchingly withdrawing the intensifiers from the spokes.

The invention is now described by way of example with reference to the accompanying diagrammatic drawings In the drawings, Figures 1 shows, in three dimensional view, a lower mould portion of a mould assembly in accordance with the invention during the process of laying up moulding material in the mould portion; Figure 2 shows, to a larger scale, a view corresponding to section ll-ll in Figure 1; Figure 3 shows, in a view corresponding to that of Figure 1, a wheel frame in accordance of the invention during the final stages moulding ; and Figure 4 shows, in a view corresponding to Figure 3, the wheel frame moulded in accordance with the invention in finished form.

With reference to the drawings, more specifically Figures 1 and 2, a wheel rim is moulded in a split mould comprising a lower mould portion 12 shown in Figure 1 and a complemental upper mould portion which is not shown in the drawings (other than fragmentarily in Figure 2) but which can easily be visualised by a person skilled in the art.

Generally, each component or feature of the lower mould portion has a complemental counterpart in the upper mould portion.

The lower mould portion comprises a plurality, in this embodiment 5, spoke forming formations generally indicated by reference

numerals 12.1. The spoke forming formations form hollow, channel-like recesses 12.2 for moulding spokes. The spoke forming formations of the lower and upper mould portions are closable onto each other, as can be visualised from Figure 2, to form an enclosed cavity for forming the spokes.

The lower mould portion 12 comprises a circumferential rim forming formation 12.3 which, together with the corresponding formation of the upper mould portion, form a well for forming a rim.

Likewise, the lower mould portion 12 includes a hub forming formation 12.4 which, in conjunction with a corresponding formation of the upper mould portion, form a hub during moulding. The spoke forming formations extend generally radially to interconnect the hub forming formations and the rim forming formations.

During a first step, layers of reinforced, resin impregnated moulding material are laid up in the respective mould portions against the moulding surfaces.

In accordance with the invention, in respect of each spoke, there is provided a composite intensifier generally indicated by reference numeral 20 and comprising a pair of laminates 20.1 and 20.2 moulded from a silicone based, heat expanding, resilient material. Each pair of intensifier laminates form a composite intensifier which will be used as a core for forming a hollow spoke.

Each composite intensifier 20 is wrapped in layers of reinforced, resin impregnated moulding material 24, as can best be seen from Figure 2 to form spoke members. The wrapped intensifiers or spoke members are then placed within respective spoke forming formations 12.1, being seated in the respective recesses 12.2 of the lower mould portion 12.

It is to be appreciated that radially outer ends of the intensifiers are flush with an open end of the spoke forming formation.

End portions of the wrapping 24 extend beyond the open end of the spoke forming formation. The wrapping projects into the rim forming formation cavity.

Inner ends of the intensifiers 20 extend inwardly beyond inner mouths of the spoke forming formations. In accordance with the invention, a central cylinder 18 in the form of a sleeve is positioned in the mould portion 12 via a central protuberance to be at the centre of the mould portion 12 and to extend axially. The inner ends of intensifiers are checked against the cylinder 18 such that the intensifiers 20 are exactly, radially, located. It is to be appreciated that the wrapping 24 does not extend to the inner end of each intensifier 20.

Further, in accordance with the invention, locking inserts 22 are positioned intermediate adjacent inner projecting ends of the respective intensifiers 20 to fill up cavities intermediate such inner ends of the intensifiers. Also the locking inserts 22 are inwardly checked against the cylinder 18. Outwardly, the locking inserts 22 are positioned

against the hub forming formations 12.4. In this fashion, the intensifiers 22 are precisely located with no lost motion, neither in tangential nor in radial direction. The intensifiers and locking inserts form intensifier assemblies in accordance with the invention.

Bridging layers 26 of reinforced, resin impregnated material are provided in the areas of the hub forming formations 24 overlapping inner ends and sides of the wrapped intensifiers and positioned intermediate radially outer ends of the locking inserts 22 and the hub forming formations 12.4. When the wrapped intensifiers have been put in position, the bridging layers 26 are folded inwardly over the wrapped intensifiers and the upper mould portion can then be closed over and secured to the lower mould portion 12.

The projecting outer ends of the wrapping 24 around the intensifiers are cut and turned back to form flaps 24.2 which are splayed open over the pre-laid up layers of, reinforced resin impregnated moulding material in the rim forming formations. Further, superimposing layers of moulding material are then laid up in the well formed by the rim forming formations to form a rim.

When the moulding assembly has been fully laid up, -it is cured under high pressure and high temperature.. All of the surfaces of the moulding material, with the exception of the spokes, are exposed to external pressure and such moulding material is then pressurised against the supporting mould surfaces to ensure that that moulding material is cured under high pressure and high temperature conditions.

As can best be perceived from Figure 2, the walls of the spokes being formed are externally covered by the spoke forming formations 12.1 and 14.1 of the upper mould portion. Their internal surfaces are supported by the outer surfaces of the respective intensifiers 20. Because the intensifiers 20 are of heat expanding material, during curing under high temperature conditions, the intensifiers 20 expand and compress the moulding material forming these spokes against the spoke forming formations of the mould portions thus ensuring that also that moulding material is cured under conditions of high temperature and high pressure.

After curing, the mould portions are split, the cylinder 18 is removed and the radially inner ends of the intensifier laminates 20.1, 20.2 and also the radially inner ends of the locking inserts 22 are exposed. Removal of the cylinder 18 provides a central round cavity enabling the locking inserts 22 to be removed, bearing in mind that the material is resilient and can be stretched. When the locking inserts have been removed, the respective laminates 20.1, 20.2 of the respective intensifiers 22 can be retracted from the spoke cavities, bearing in mind that the material of the intensifiers is resilient and longitudinal stretching thereof shrinks them in cross-section thus facilitating removal.

The wheel frame moulding is thus de-moulded and can be finished off.

It is of extreme importance that the wheel frame is formed as a unitary moulding. Bearing in mind that it is regarded by the applicant as essential that curing, also of the spoke walls, must take place at high temperature and high pressure, it is a very important advantage that this invention allows intensifiers to be placed within the spokes and to be reclaimed intact after moulding to be available for re-use.