Technical Field This invention relates to a nipple for the spoked wheels of the type incorporating the features mentioned in the precharacterizing clause of claim 1.

The invention also relates to a method for manufacture of the said nipple, and a method for assembling a spoked wheel making use of nipples according to the invention.

Background Art In the manufacture of spoked wheels the-problem of preventing progressive slackening of the nipples as a result of the vibration and stresses caused when the wheel is in use is known. Two pre-eminent technologies have been proposed in this connection: the first, the subject matter of European patent EP 0838352 of which the applicant is proprietor, provides for placing an insert, generally of plastics material, in the nipple, where the free end of the spoke is engaged with slight force in accordance with a technique similar to that of conventional self- locking nuts; the second provides for the use of adhesives of the known type such as thread-locking adhesives which when applied to the threaded zone between the nipple and the spoke in the fluid state solidify preventing subsequent undesirable slackening of the nipple.

Although fully meeting the requirements set out above, both these techniques nevertheless have a number of disadvantages. The former requires that the nipples be machined in a particular way, and this, especially in dimensionally smaller embodiments, can give rise to some problems. It is in fact necessary to machine the nipple in order to provide a housing for the insert and to deform it locally in order to retain the same.

The latter instead requires some control over tightening which becomes substantially poorer when the operation of adjusting the nipple and retightening it is repeated several times.

Disclosure of the invention The technical problem considered and solved by the invention is that of providing a new nipple, with a corresponding method of manufacture and a new method of assembly with a spoked wheel, designed to permit the disadvantages complained of in relation to the abovementioned known art to be overcome.

This problem is resolved by the invention through a nipple constructed in accordance with the following claims.

Brief description of the drawings Other advantages and characteristics of the present invention will become clear from the following detailed description which is given with reference to the appended drawings which are provided by way of non-limiting example and in which: - Figure 1 is a view of a nipple constructed according to this invention in longitudinal cross-section, - Figures 2 to 7 are diagrammatical illustrations of the stages in the machining of the nipple in Figure 1.

Best mode for carrying out the invention In the figures, 1 indicates as a whole a nipple constructed according to this invention. Nipple 1 comprises a cylindrical shank 2 extending predominantly axially, having an enlarged head end 3. Head 3 is preferably shaped with a cylindrical or polygonal skirt 4 (in the latter case capable of constituting an operating key), and/or with a diametral notch 5 which can also act as an operating key. The polygonal skirt and/or notch are used to manipulate the

nipple using a suitable tool (spanner or screwdriver) when screwing up/unscrewing threaded end 6 of a spoke 7.

Nipple 1 has an axial hole 10 which is enlarged at one end to form a mouth 11 and has an intermediate threaded portion 12 which is screwed into end 6 of spoke 7. Opposite mouth 11, that is at head 3, hole 10 is further enlarged to form a cup-shaped seat 13 (a seat of cylindrical shape, enlarged with respect to hole 10, is also to be understood to be included within this term) provided as an extension to the hole and designed to receive a thread-locking liquid, indicated in the figure by 14, capable of immobilising the screwed spoke in the nipple.

Seat 13 is adjacent to and directly-communicates with the threaded portion of the hole and has a greater diameter than the root diameter of the thread in the threaded portion of the hole, or is engaged with radial play by the crests of the threads of the threaded portion of the spoke. In this way there remains ample play between the free threaded end of the spoke projecting into the seat and the side wall of the latter so that the thread-locking resin optimally fills the space around the spoke.

The quantity of thread-locking liquid applied to cup-shaped seat 13 is sufficient for the end of the spoke projecting into it to be substantially immersed in the aforesaid liquid.

With reference to Figures 2 to 7, nipple 1 is manufactured from a metal rod from which a semi-finished product 20 is obtained by shearing and upsetting or through fusion. 21 and 22 in Figure 2 indicate tools for applying or removing the semi-finished product.

Semi-finished product 20 is then subjected to machining of cup-shaped seat 13, on the side of head 3, and centering by the opposite part (Figure 3). Axial hole 10 and mouth 11 are then machined (Figure 4). Subsequently notch 5 is

machined by milling and hole 10 is then completed from the opposite side in order that portion 12 can finally be threaded.

During the assembly of a spoked wheel, once the nipples have been fitted and their tightening has been adjusted, a predetermined quantity of thread-locking liquid is placed in the cup-shaped seat, preferably using automatic metering equipment (or by hand), so that the free end of the spoke screwed into the nipple is immersed. The thread-locking liquid tends to spread along the thread of the nipple, affecting at least a portion thereof and contributing to immobilisation of the threaded connection, but in every case a substantial quantity of the same remains in the cup seat where it exerts a retaining and immobilising action on the spoke between the threaded-shank of the same projecting beyond hole 10 and the walls of the cup, and between the free end of the spoke and the film of liquid covering it.

The invention thus brings about the required technical results but also brings about many advantages in comparison with the known prior art'-including undoubted ease of application of the thread-locking product.

A further advantage is provided by the fact that the efficiency of the spoke/nipple coupling is less prone to adjustment operations, with a consequent improvement in its properties over time.