Light alloy rim with a front covering element in stainless steel and its production method

Field of the invention

This invention concerns the field of light alloy rims for car wheels and, in particular, the covering of at least one visible part, that is, the front, of a light alloy rim with an element in stainless steel in order to increase the value and improve the appearance.

State of the art

There already exist covering elements for light alloy rims for car wheels in a different material, such as stainless steel. These elements are generally limited to the outer area of a rim and are fastened to the rim by means of additional fixtures, which are awkward and liable to work loose, with the risk that the cover will become detached as a result of contact with a pavement or similar, as may easily happen during a parking manoeuvre.

For example, document US 4 530 542 discloses a wheel centre having an outboard side to which a steel cover is attached. The cover has outer and inner axial flanges which are a press fit onto corresponding shoulders of the wheel centre.

However, in order to secure the cover in place even during some vehicle operating conditions, additional locking means, such as adhesive and/or screw-threaded nuts, securing the wheel assembly to the vehicle axle hub and bearing against the outboard surface of the cover, are necessarily used.

Document US 5 595 423 discloses a system for the retention of a cover on a vehicle wheel. According to this system, a part of the cover is folded over the external circumference of the rim, but for permanently securing the cover to the rim, an adhesive is utilized.

Purpose and explanation of the invention

One of the aims of this invention is to propose and produce a light alloy rim equipped with a covering front element in stainless steel, fixed in place with an innovative mechanical means, without the use of glue or other additional means, but, nevertheless, held there permanently and securely.

Another purpose of this invention is to supply a light alloy rim with a covering element that covers the whole front part, from the outer edge to the centre hub.

A further aim of the invention is to supply a light alloy rim with a circular covering element that covers an outer ring of the rim itself.

These aims are achieved by applying a covering element in stainless steel to at least one part of the front surface of a rim, folding at least an outer part of the covering element over an outer external edge of the rim and folding down, by means of upsetting or chamfering, the outer margin of the covering element behind a circular undercut, located around the outer external edge.

The covering element may extend from the outer edge as far as the centre hub of the rim, or be restricted to the most external border or ring of the front of the wheel.

Brief description of the drawings

In any case, the external seaming line of the element is hidden, invisible from the front of the rim.

The enclosed drawings illustrate examples of the light alloy rim with a covering element applied, in accordance with the invention. In said drawings:

Fig. 1 shows a cross-section of a light alloy rim with a complete front covering;

Fig. 2 shows a similar section of a light alloy rim with a covering only on the external border or ring;

Fig. 3 shows, in cross-section, an enlarged detail of the covering in Fig. 2, in correspondence with the centre hole in the rim hub;

Fig. 4 also shows a cross-section of an enlarged detail of the part of the rim border circled in Figs 1 and 2; and

Fig. 5 shows an example of the equipment for applying the covering element to the rim border.

Detailed description of the invention

Generally speaking, the light alloy rim 1 to which this invention can be applied is of the conventional type, with spokes and holes of any aesthetic shape around a central hub 2 and with an external border or ring 3 which projects frontally and ends in an outer edge 4. The hub will have a centre hole 5 and holes 5' for the fixing screws that hold the rim on the car wheel support.

The rim may be completely covered in the front part - Figs 1 - 3. In this case, a sheet of stainless steel 6 will be needed, suitably shaped in such a way as to match the visible front surface of the rim, covering it completely. The sheet will also have folded-back parts which will interact with the corresponding parts on the rim.

In detail and referring to Fig. 3, the centre hole 5 in the hub has a circular protuberance 7 that defines an undercut 7' which interlocks with a turn-up 8 on the internal edge of the steel sheet 6.

Similarly, with reference to Fig. 4, the outer external edge 4 of the rim has an undercut 4' to which is hooked an external turn-up 9 of the steel sheet 6.

In this way, the stainless steel sheet 5 is completely and securely fastened to the rim 1, totally covering it.

In accordance with the invention, the rim 11 may also be only partially covered in front with a stainless steel element, as shown in Fig. 2, at the level of the visible surface of the edge or ring 12. In such a case, this edge or ring surface 12 is finished and covered with a circular strip 14 in stainless steel, extending over the outer edge 13 and fastened to it. The external margin 15 of the strip 14 is folded behind an undercut 16, made around the edge 13. Said undercut 16 may consist of a rim gutter, as shown in the drawing - Figs 2 and 4 - or by a shoulder or step, turned over towards the rear of the edge.

The covering strip 14 may be applied to the rim with a piece of equipment 17, such as that shown in Fig. 5, for example. This equipment consists of various functional devices 17, 18, designed to hold the circular strip 14 to the internal surface of the edge or ring 12 of the rim, to turn up an outer part of the strip so that it grips the outer edge 13 and to fold over, by either the mechanical means of upsetting or chamfering, the external margin of the strip 14 behind the undercut 16, that is, into the rim gutter around the edge.

As a result, the covering strip in stainless steel will be tightly and securely fastened to the rim, covering the surfaces in question. The upset or chamfered margin 15, acting with the undercut or rim gutter, guarantees the solidity and stability required for the covering strip, producing the desired effect.