DESCRIPTION

Technical field

This invention relates to a method for forming and assembling a wheel for vehicles.

Background art

In particular, the definition of wheels for vehicles in this specification relates to a wheel forming, together with the tyre, a complete wheel for vehicles, such as, for example: motorcycles, automobiles, agricultural vehicles, industrial vehicles, etc.

Currently, the wheels for these vehicles may be obtained cold and worked with automatic machines or by casting in a single body.

In both cases, the components which form the wheel are:

- a rim on which is mounted the tyre;

- a disc formed by a supporting element, or wheel hub, and a plurality of connecting flanges, or wheel spokes.

The plurality of spokes extend radially from the wheel hub and join at predetermined points inside the rim.

The disc is designed to stiffen the rim (spokes) and define a connection point with the hub of the vehicle, as well as, obviously, transmitting to the hub and supporting the loads acting on the wheel in operation.

As already mentioned, the wheel may be obtained by a process of fusion in a single piece formed by the shape of the mould, or with a cold forming process.

In the case of a cold forming process, to which this invention is aimed, the wheel is usually pressed/machined with machine tools, whilst the disc is usually forged in different lightweight alloys (such as aluminium alloys). The two components are then joined to each other through different solutions: - the first is of the permanent type, such as: welding, brazing, assembling by interference, riveting, bolting or gluing;

- the second is of the removable type with fastening means preferably threaded.

In other words, the wheel is formed, usually, through these steps:

- positioning of the rim:

- moving the disc towards to the rim in such a way that the ends of the spokes coincide with the areas of the rim provided with corresponding joining means;

- joining the spokes to the rim (permanently or in a removable fashion). In the current market, the formation of the wheels according to the two processes is used as a function of the market segments to which the products are aimed.

In the case of a product by fusion, there is relatively lightweight and precise product, but there are high production costs and difficulties.

In the case of the cold forming process, there are low production costs, but the weights of the end product are greater than those of the product formed by fusion and they do not always guarantee the same efficiency in terms of rigidity/weight ratio of the wheels made by fusing of an aluminium alloy.

Moreover, the steps for assembly between the rim and wheel hub may be particularly lengthy and must be accurate to guarantee wheels which are safe in operation and have an acceptable appearance.

In order to make the wheels made with cold forming process more competitive and efficient, wheels defined as "bimetallic" currently exist, aimed at luxury cars, consisting of an aluminium alloy rim preferably cold formed and a disc forged in aluminium alloy joined to each other by threaded elements of the removable type.

This type of product, which is extremely versatile and better performing, has a high cost and must comprise an assembly process which is extremely precise and slow and, consequently, it has limitations both in terms of the various types of product which can be offered and the so- called "after market" retail.

Disclosure of the invention

The aim of this invention is provide a method for cold forming a wheel for vehicles which overcomes the above-mentioned drawbacks of the prior art.

More specifically, the aim of this invention is to provide a method for cold forming a wheel for vehicles which is able to assemble the components with a high precision and quickly.

A further aim of this invention is to propose a method for cold forming a wheel for vehicles which is able to produce a large number of products per unit time and with a high production flexibility and with variants in terms of geometry and/or appearance, increasing the mechanical efficiency of the wheels.

These aims are fully achieved by the method for forming and assembling a wheel for vehicles according to this invention and as characterised in the appended claims.

More specifically, the method for forming and assembling a wheel for vehicles comprises the following steps in succession:

- preparing a rim with a predetermined orientation of its first axis;

- deforming the rim through a direct thrust towards the first axis and along at least one edge of its outer surface so as to define a configuration of the rim having a plurality of lobes along the rim;

- preparing the disc in such a way as to orient its second axis coaxial with the first axis;

- moving the disc to the deformed rim along an axial direction of translation parallel to the first and second axis, and in such a way as to bring the plurality of free ends of the spokes inside the lobes formed;

- restoring the annular configuration of the rim by the release of the thrust force and - joining the spokes to anchoring elements by fastening means.

Preferably, the step of deforming the rim defines a configuration of the rim having a plurality of lobes along the rim at least with a number corresponding to the plurality of spokes present on the disc.

Thanks to this method there are numerous advantages, including reducing the times for the execution of orders (for example, in the "after market" segment) even in the presence of a large number of rim/disc combinations requested.

This makes it possible to keep finished rims and discs in the store and to carry out their assembly, upon receiving the orders, in significantly shorter times than those necessary to complete and finish an entire wheel which is semi-processed and with similar aesthetic requirements.

Brief description of drawings

This and other features will become more apparent from the following description of a preferred embodiment, illustrated by way of non-limiting example in the accompanying drawings, in which:

- Figure 1 illustrates an exploded perspective view of a wheel for vehicles which can be formed with the method according to this invention;

- Figures 2 to 5 illustrate front views of corresponding steps of the method for forming the wheel of Figure 1 in a first solution;

- Figure 6 illustrates a side view and with a partial cross section of its outer part of the wheel of the preceding figures already assembled with the method according to the invention;

- Figure 7 is an enlarged detail of Figure 6;

- Figure 8 illustrates a front view of an alternative step of the method for forming the wheel according to the invention.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings and in particular with reference to Figure 1 , the method according to the invention is used for forming a wheel 1 for vehicles.

In this specification, the term wheel is used to mean that component which forms, together with a tyre (not illustrated), a complete wheel for a vehicle, such as, for example, motorcycles, automobiles, agricultural vehicles, industrial vehicles, etc.

The wheel 1 (see Figure 1 ) comprises an annular element or rim 2 extending about a first axis X2 and having an outer surface 2a, designed to support the tyre, and an inner surface 2b.

Moreover, the wheel 1 comprises a plurality of anchoring elements 3 positioned along an edge of the inner surface 2b of the rim 2.

Again, the wheel 1 comprises a disc 4 comprising a central element 5 with an annular shape, extending about a second axis X5, and a plurality of connecting portions or spokes 6, equal in number to the plurality of anchoring elements 3, and projecting radially from the central element 5. The wheel 1 comprises fixing means 7 for mutually fixing the plurality of anchoring elements 3 and the corresponding free ends of the plurality of spokes 6.

This invention illustrates, by way of a non-limiting example, a disc having five spokes, but the method according to the invention may be used for discs having less than five spokes or more five spokes, without thereby limiting the scope of protection.

As illustrated, the method for forming and assembly the wheel 1 comprises at least the following steps in succession:

- preparing the rim 2 with a predetermined orientation of the first axis X2 (horizontal or vertical or inclined) (Figure 1 );

- deforming (preferably elastically) the rim 2 through a direct thrust towards the first axis (X2) and along at least one edge of its outer surface 2a so as to define a configuration of the rim 2 having a plurality of lobes 8 along the rim 2 (Figure 2);

- preparing the disc 4 in such a way as to orient the second axis X5 coaxial with the first axis X2 (Figures 1 and 3); - moving the disc 4 towards the rim 2 deformed along an axial direction A of translation parallel to (preferably coincident with) the first X2 and the second X5 axis, and in such a way as to bring the plurality of free ends of the spokes 6 inside the plurality of lobes 8 formed (Figures 4 and 8);

- restoring the annular configuration of the rim 2 by the release of the thrust force (Figure 5);

- joining the spokes 6 to the anchoring elements 3 using the fixing means 7.

Preferably, the step of deforming the rim 2 defines a configuration of the rim 2 having a plurality of lobes 8 along the rim 2 at least with a number corresponding to the plurality of spokes 6 present on the disc 4.

In the latter operating mode, as already mentioned, there are five spokes 6 shown in the accompanying drawings and, in this case, the thrust step for deforming the rim 2 is performed in five different points of the rim 2.

In light of this, the pushing step is performed radially along an outer edge of the outer surface 2a of the rim 2 and in the plurality of points, spaced apart from each other around the rim 2, as a function of the number of spokes 6 present on the disc 2.

According to a first embodiment (see Figures 3 to 5), the step of deforming the rim 2 defines a plurality of lobes 8 angularly offset relative to the position on the rim 2 of the (corresponding) plurality of anchoring elements 3 (see Figure 3).

Preferably, after the step of moving the disc 4 towards the deformed rim 2, there is a step of rotation of the disc 4 and the spokes 6 about the second axis X5 to allow the positioning of the free ends of the plurality of spokes 6 at the corresponding plurality of anchoring elements 3 (Figure 4).

In light of this, the step of rotation of the disc 4 is performed before the step of restoring the annular configuration of the rim 2.

According to the type of anchoring elements 3 (as described below), after the step of moving the disc 4 towards the deformed rim 2, there may be a step of roto-translation of the disc 4 and the spokes 6 about and along the second axis X5 to allow the positioning of the free ends of the plurality of spokes 6 at the corresponding plurality of anchoring elements 3.

Also in light of this, the step of rotating the disc 4 is performed before the step of restoring the annular configuration of the rim 2.

It should be noted that the step of moving the disc 4 towards the rim 2 occurs in such a way as to bring the free ends of the plurality of spokes 6 to the most protruding part, radially away from the first axis X2, of the corresponding plurality of lobes 8 present temporarily on the rim 2.

In this way, there is a fast and precise positioning and centring of the disc with spokes relative to the rim.

It should also be noted that the step of rotation of the disc 4 about the second axis X5 defines a stable coupling, by interference (with clearance) or in a snap-on fashion, between the free ends of the plurality of spokes 6 with the corresponding plurality of anchoring elements 3.

According to a second embodiment of the method, illustrated in Figure 8, the step of deforming the rim 2 defines a plurality of lobes 8 coincident to the position on the rim 2 of the corresponding plurality of anchoring elements 3.

In this case, the step of moving the disc 4 towards the rim brings the free ends of the plurality of spokes 6 in direct contact with the corresponding plurality of anchoring elements 3.

In other words, two different steps are used for centring and joining as a function of the type and shape both of the anchoring elements 3 and the ends of the spokes 6.

In both cases the joining portions are hidden outside from view, obtaining a wheel with a good appearance.

As may be inferred by the steps according to the method, in the case of deformation with subsequent rotation, the joining portions may be hidden both inside and outside from view.

In both cases, the step of restoring the an annular shape of the rim 2 determines a stable positioning of the disc 4 with respect to the rim 2 by means of the contact of the free ends of the plurality of spokes 6 with the inner edge of the rim 2.

This feature guarantees an immediate and correct relative centring between disc and rim.

Preferably, but without limiting the scope of the invention, the fixing means are of the removable type (for example, threaded bolts and/or nuts).

In light of this, the joining step comprises a step of locking, by screwing the fixing means 7, between the plurality of spokes 6 and the corresponding plurality of anchoring elements 3.

In the case illustrated in Figures 6 and 7, by way of a non-limiting example, each anchoring element 3 comprises at least one flange 9, positioned along a plane parallel to the edge of the inner surface 2b of the rim 2 and connected to the inner edge of the rim 2 in such a way as to protrude radially towards the first axis X2.

Preferably, each flange 9 is provided with one or more holes for the passage of the fixing means 7 for the joining with the corresponding spoke

6.

In turn, each free end of the plurality of spokes 6 has a first wing 10 and a second wing 1 1 parallel to each other and spaced to define a channel 12 (transversal to the second axis X5).

Moreover, each spoke 6 has corresponding holes for the passage of the fixing means 7.

In light of this, the step of rotation of the disc 4 about the second axis X5 allows the coupling, either by interference or with snap-on connection, of each flange 9 in the corresponding channel 12 of the free ends of the plurality of spokes 6.

If the flange 9 has a geometrical configuration which is inclined relative to the edge of the inner surface 2b of the rim 2, the step of attaching the spokes 6 to the anchoring elements 3 will be performed with the roto- translation of the disc 4 to allow the correct coupling between the two components. After these couplings have been performed, which render coaxial the corresponding holes of each flange 9 and each spoke 6, the two components are joined together mechanically.

As mentioned, the fixing means are preferably removable connections of the threaded type (for example, nuts and screws), but the method according to the invention may also comprise other forms of threaded connection or permanent connection systems by means of riveting, bolting, press-fitting, welding, brazing or even gluing.

Summing up the method, the rim is positioned inside a suitable apparatus (not illustrated), which comprises a number of centring devices (pushing means) preferably equal to the number of spokes fitted to the disc.

A positioning/centring of the disc relative to the rim is then performed.

A suitable calibrated force is applied to the centring devices in such a way as to deform the rim which, temporarily, adopts a multi-lobed shape, that is to say, with a number of lobes preferably equal to the number of centring devices (therefore, the number of spokes).

Then, maintaining the calibrated force of the centring devices on the rim, the disc is positioned inside the rim, by transferring the disc along the axial direction, taking care to position each spoke at the most protruding part of each lobe in which the rim is temporarily deformed, preferably with relative clearance between the spoke and the protruding part of the corresponding lobe.

In the first embodiment illustrated, again maintaining the calibrated force from the centring devices to the rim, the disc is also rotated (or roto- traslated) about the second axis according to a circumferential direction.

This action moves the ends of the spokes to house the anchoring elements in the rim.

At this point, before proceeding with the joining of the spokes with the anchoring elements, it is possible to eliminate the force applied by the centring devices to the rim, in such a way that the rim recovers its initial geometry and the disc is centred correctly inside the rim. According to the second embodiment of the method, on the other hand, after the positioning of the disc inside the rim, with anchoring elements and spokes already positioned one against the front of each other, one passes directly to the step of restoring the initial geometry of the rim.

At this point, in both cases, it is possible to connect the disc to the rim, for example by tightening nuts and bolts, or with another removable fastening system.

The different solutions for assembling, with or without rotation of the disc, depend on the geometry of the ends of the spokes and the final appearance sought for the wheel.

If the latter, as described, consist of an inner part and an outer part, the positioning of the disc in the rim must be performed in such a way that each spoke is positioned laterally to the corresponding anchoring element and from both sides of it, relative to the direction of translation.

For this type of geometry is necessary to rotate the disc inside the rim when the latter is temporarily forced, by elastic deformation, to adopt the multi-lobed shape.

If the geometry of the ends of the spokes (for example, with a C-shaped flanged cross section) is such as to allow a total coverage of the anchoring element, it is possible to achieve the coupling only with a translation along the axial direction of the disc inside the rim, and taking care to position the disc in such a way that each spoke corresponds with the most protruding part of each lobe in which the rim is temporarily deformed.

Therefore, thanks to this method, the present aims are achieved and there are considerable advantages, including:

- combining high resistance and reliability of a rim preferably made of steel with the lightness and the aesthetic value of a disc preferably made of lightweight aluminium alloy;

- it is possible to make families of wheels which are modular in terms of width, having the same disc but different widths of the rim;

- it is possible to make families of wheels which are modular in terms of diametric dimension, given that the raw geometry of the disc can be configured in such a way as to be finished with different machining programs and, thus, be assembled on rims with different diameters;

- it is possible to make families of wheels which are modular and "dedicated" in terms of finishing appearance, that is, wheels having rims and discs with different options of colour and/or surface treatment, which can be combined according to various options;

- it is possible to make families of wheels which are modular and "dedicated" in terms of performance (rigidity and lightness), that is, wheels having rims and/or discs made from different metallic or non-metallic materials.