Patent Description:
Fasteners and various embodiments of threaded nut members manufactured by various methods are well known. For example, typical flange nuts or lock nuts may comprise a hexagonal exterior and a threaded internal cylinder, as well as, an enlarged supporting surface or washer. The hexagonal exterior is configured for engagement with a tool, such as, a lug wrench or a hex key socket screwdriver. Fasteners of this type may be manufactured from a single piece, e.g. via forging, cold-forging, pressing or stamping. or through combining various parts which are joined together. When manufactured from a single piece, fastener nuts may be manufactured from wires or tubes of different thickness and/or material (e.g. steel or stainless steel, or any other ferrous material) and then hardened/strengthened using carbon, boron and/or heat treatment.

When forging or cold forming fasteners, material is often moved to form a desired outer and inner shape or profile. However, this type of fastener is relatively heavy due to relatively thick walls required to have enough material for an inner thread that is suitable to provide sufficient strength when tightened. Further, the manufacturing process of forged or cold-formed fasteners is relatively time consuming and costly. <FIG> shows a variation of conventional fastener nuts that may be replaced by the fastener nut of the present invention including, for example, (a) standard flange nuts, (b) fastener nuts with a nylon ring to prevent loosening (i.e. a locking feature) and (c) flange nuts with a conical washer, e.g. a spring washer to provide axial flexibility and prevent fastening or loosening due to vibrations.

Fastener nuts specifically designed to reduce weight may be formed, for example, from (relatively thin) sheet metal via pressing or stamping. Though, currently available fastener nuts, such as, for example, flange nuts or lock nuts, are not suitable for high-strength connections. In particular, stamped or pressed sheet-metal hexagonal nuts provide relatively "weak" threading engagement due to the relatively thin side walls (reduced thread height) and the significantly reduced thickness of the inner surface comprising the threaded sections. Further, typical fastener nuts, such as, flanged nuts or lock nuts, are prone to loosen due to vibrations or other external forces without additional components or support such as seals, adhesives, locking rings or other locking features. A fastener nut is known from <CIT>.

Consequently, it is an object of the present invention to provide an improved fastener nut capable of mitigating at least some of the drawbacks mentioned above. In particular, it is an object of the present invention to provide a relatively lightweight fastener nut stamped or pressed from sheet metal with improved performance characteristics (e.g. 'Proof-Load' strength, tightening load, torque), but also an improved ease of use during installation or removal, during use.

An aspect of the invention is set out in the independent claim. Dependent claims describe optional features.

In a first aspect of the invention there is provided a fastener nut in accordance with claim <NUM>. The fastener nut formed from an integral piece of sheet metal having a first axial end and an opposed second axial end along a central axis, comprising:.

Advantageously, said head member and said flange member may be integrally formed from sheet metal.

This provides the advantage of a lightweight fastener nut formed from sheet metal having an internal thread that is configured to provide a maximised proof load. In particular, the fastener nut of the present invention provides for optimally shaped side walls where a central portion is moved radially inwards (i.e. to wards the central axis of the annular head member), therefore maximising the material thickness and area that can be utilised to form the internal thread. As a result, an internal thread can be provided within the side walls that has an optimised thread height so as to maximise its proof load and tightening torque, while minimising the amount of material required and its resultant weight. Furthermore, the present invention provides the advantage that the fastener nut can be stamped (i.e. by embossing, punching and/or cutting) or pressed without the need to redistribute material (e.g. metal, steel) to different locations in order to create a polygonal (e.g. hexagonal) nut profile, simplifying and quicken the manufacturing process, minimising time and costs. The outwardly protruding corners of adjoining side walls provide an easily shaped polygonal profile suitable for operable engagement with a standard tool but without the need of adding or shifting material, for example, via hot or cold forging.

The fastener nut further comprises a joining portion integrally formed between said head member and said flange member and configured to transmit, resiliently, an axial force between said first and second axial ends. This provides the advantage of a maximised proof load and allowing higher tightening loads. In particular, the resilient characteristics of the joining portion provides for an increase in based deflection of the axial forces maximising the integrity between the nut the bolt, and the engaged component.

Advantageously, said joining portion may be any one of a substantially dome-shaped and a ball-cone-shaped joining portion.

Advantageously, said joining portion may further be configured to guidingly receive and centre a corresponding fastener during use. This provides the advantage of an improved ease of use, as well as, durability due to minimised wear and tear from optimising the installation.

Advantageously, an inner surface of said central portion of each one of said plurality of side walls may be provided with a thread section, so as to form an internal screw thread within said internal axial passage configured to threadingly engage with the corresponding fastener during use.

Preferably, said external profile defined by said plurality of side walls may be hexagonal.

Advantageously, said sheet metal may be a high-carbon steel.

In a second aspect of the invention, there is provided a fastener nut in accordance with claim <NUM>. The fastener nut formed from an integral piece of sheet metal having a first axial end and an opposed second axial end along a central axis, comprising:.

Advantageously, said head member and said flange member may be integrally formed form sheet metal.

The fastener further comprises a joining portion integrally formed between said head member and said flange member and configured to transmit, resiliently, an axial force between said first and second axial ends.

Preferably, said joining portion may further be configured to guidingly receive and centre a corresponding fastener during use.

Even more preferably, an inner surface of said central portion of each one of said plurality of side walls may be provided with a thread section, so as to form an internal screw thread within said internal axial passage configured to threadingly engage with the corresponding fastener during use.

Advantageously, said external profile may be defined by said plurality of side walls is hexagonal.

Preferably, said sheet metal may be a high-carbon steel.

In a third aspect of the invention there is provided a method for manufacturing a fastener nut according to the first or second aspect, in accordance with claim <NUM>, comprising the steps of:.

This provides the advantage of a simplified method, making the manufacturing process of relatively lightweight fastener nuts less time consuming and more cost effective.

An exemplary embodiment of the invention is explained in more detail hereinbelow with reference to the figures:.

The described example embodiment relates to a fastener nut for use with vehicle components, and particularly, a fastener nut (or light-nut) stamped or pressed from sheet metal material. However, the invention is not limited for use with vehicle components but may be used for any suitable fastening. Through the description, the terms 'fastener nut, sheet-metal nut and 'light-nut' are used interchangeably.

Certain terminology is used in the following description for convenience only and is not limiting. The words 'right', 'left', 'lower', 'upper', 'front', 'rear', 'upward', 'down', 'downward', 'above' and 'below' designate directions in the drawings to which reference is made and are with respect to the described component when assembled and mounted (e.g. in situ). The words 'inner', 'inwardly' and 'outer', 'outwardly' refer to directions toward and away from, respectively, a designated centreline or a geometric centre of an element being described (e.g. central axis), the particular meaning being readily apparent from the context of the description.

Through the description and claims of this specification, the terms 'comprise' and 'contain', and variations thereof, are interpreted to mean 'including but not limited to', and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality, as well as, singularity, unless the context requires otherwise.

The invention is not restricted to the details of any foregoing embodiments.

Referring now to <FIG>, and according to a first example embodiment of the present invention, the fastener nut <NUM> is manufactured by stamping sheet metal without forge-moving material, i.e. by simply bending sheet metal into the desired shape. This particular example embodiment comprises integrally formed head member <NUM>, joining portion <NUM> (also known as smart joint) and flange member <NUM>. The head member <NUM> comprises six side walls 108a - 108f integrally joint and arranged in a hexagonal profile that is suitable for engagement with a standard tool, such as, a wrench or hex key (not shown).

During the forming or stamping process, a central portion 110a - 110f (central portion 110d is representative for the other central portions) of each one of the side walls 108a - 108f is pressed radially inwards (i.e. towards a central axis <NUM> of the annular head member <NUM>) by a predetermined inset distance (e.g. <NUM>% of the thickness of the sheet metal), so as to form an arcuate cross sectional profile of a predetermined radius. The radially inwardly pressed (i.e. inset) central portions 110a - 110f define a substantially cylindrical internal surface <NUM> interrupted by circumferentially spaced voids 116a - 116f of the corners 118a - 118f (void 116f and corner 118f are representatives for the other voids and corners). Each one of the corners 118a - 118f has an arcuate outer surface profile and is protruding radially outwards (i.e. away from the central axis of the annular head member <NUM>).

It is understood by the person skilled in the art, that the inset distance (i.e. radial offset between an outer surface of the corners 118a - 118f and an outer surface of the central portions 110a - 110f) may be any distance suitable to define a desired internal diameter of the cylindrical internal surface <NUM>.

An internal thread <NUM> is provided on the cylindrical internal surface <NUM> formed by the central portions 110a - 110f of the side walls 108a - 108f. The internal thread <NUM> may be a metric sized standardised thread and may be formed by any suitable process, such as, for example, cutting or cold-forming. Because the central portions 110a - 110f of the side walls 108a - 108f are moved inwardly, the maximum thickness of the sheet metal material may be used to form the internal thread <NUM> with a thread height for maximum load strength. This way, a relatively "light weight" (i.e. a weight saving compared to equivalently sized and utilised fastener nuts) fastener nut <NUM> is provided that is specifically designed for "high performance" (i.e. a relatively high torque and high proof load in view of equivalent, "heavier" conventional fastener nuts). In a particular example embodiment, the fastener nut <NUM> of the present invention may be around <NUM>% lighter than conventional, similarly sized and similarly performing fastener nuts.

Referring now to <FIG> and <FIG>, in particular, the joining portion <NUM> may be integrally formed by pressing or stamping, so as to provide a dome-shaped or ball-shaped side wall profile between the head member <NUM> and the flange member <NUM> (with its wider diameter at the flange member end). The joining portion <NUM> is particularly adapted to accept higher torques to minimise or even avoid loosening of the screw during its use. In particular, the axially resilient characteristics help to avoid squeak and rattling by keeping the fasteners tightly together. Further, a higher maximum proof load (compared to conventional fastener nuts for similar use) allows for a higher tightening load that can be applied to the fastener nut <NUM>. In addition, the specific ball- or dome-shaped cross sectional (axially) profile provides for an improved ease of use, because the entering screw is more easily centred by guiding the screw into a correct position before engaging the internal thread <NUM> of the head member <NUM>. Different profiles to the preferred ball- or dome-shaped profile of the present invention (dotted square) are shown for a more direct comparison illustrating the non-deflective structure of the cone or straight radius design.

<FIG> shows an illustration of load and deflection behaviour for a conventional cold headed or single threaded fastener nut and the fastener nut <NUM> of the present invention.

Here, as the clamp force increases, the deflection in the fastener gradually increases. Once assembled, small decreases in joint deflection usually occur, though, the durability provided by the fastener nut <NUM> prevents any loss of joint integrity, as may be the case with the conventional fastener nuts where a minimal deflection can lead to load loss and loosening of the fastener nut.

The flange member <NUM> is integrally formed by pressing or stamping, so as to provide a radially outward extending flange having a predetermined diameter that is greater than the diameter of the head member <NUM> and joining portion <NUM>. Preferably, the flange member <NUM> may have a circular footprint. However, it is understood by the person skilled in the art that any other suitable footprint may be used (e.g. square etc.).

Referring now to <FIG>, example performance test procedures are shown to illustrate the improvements provided by the fastener nut <NUM> of the present invention. For example, <FIG> illustrates an example load test of a hexagonal fastener nut sized M16 (standard metric hex nut size) with 'nut <NUM>' OEM test according to FCA <NUM>/<NUM> being successful at 167kN (kilo Newton) for <NUM> (seconds) with no deformation, the nut can be unscrewed by hand and there was no permanent elongation. 'Nut <NUM>' Class <NUM> was tested according to UNE-EN ISO <NUM>-<NUM>:<NUM> being successful at 185kN for <NUM> with no deformation, the nut can be unscrewed by hand and there was <NUM> (millimetre) elongation due to deformation of the screw.

<FIG> illustrates a tightening torque test according to UNE-EN <NUM>-<NUM>:<NUM>, the nut can be unscrewed by hand and the tested tightening torque was <NUM> (Newton-meter) after <NUM>° (degrees) turn. The maximum tightening torque with a <NUM>% safety coefficient was <NUM> after <NUM>° turn.

<FIG> and <FIG> illustrate example results of residual load after <NUM> (hours) for different samples of the fastener nut. In Test <NUM> (<FIG>), the tightening torque was <NUM> after <NUM>, i.e. a minimal reduction in load (less than <NUM>% reduction) and the residual torque with less than <NUM>% reduction. In Test <NUM> (<FIG>), the tightening torque was <NUM> after <NUM>, i.e. a minimal reduction in load (less than <NUM>% reduction) and the residual torque with less than <NUM>% reduction.

<FIG> shows illustrations of typical applications of the fastener nut <NUM> (i.e. light nut) of the present invention, such as, for example, at a vehicle front suspension (suspension arm) where conventional fastener nuts can be replaced by fastener nut <NUM> (e.g. M16 light nut).

For manufacture of the fastener nut <NUM> of the present invention, a sheet metal is simply stamped or pressed into the desired shape using one or more suitable die(s), to then provide an internal thread via cutting or forming, before a suitable heat treatment is applied to strengthen the material (e.g. hardening). The sheet metal may be a high carbon steel or a Boron steel (weldable).

Claim 1:
A fastener nut (<NUM>) formed from an integral piece of sheet metal having a first axial end and an opposed second axial end along a central axis (<NUM>), comprising:
an annular head member (<NUM>) at said first axial end, comprising a plurality of side walls (108a, 108b, 108c, 108d, 108e, 108f) defining a substantially polygonal external profile configured to engage with a tool and an internal profile comprising a thread with a thread groove configured to engage with a screw, wherein at least a portion of at least one or more, preferably each one, of said plurality of side walls (108a, 108b, 108c, 108d, 108e, 108f) is radially inset so as to form radially outward protruding corners (118a, 118b, 118c, 118d, 118e, 118f) with the radially inset side wall portion being between two such corners (118a, 118b, 118c, 118d, 118e, 118f) and preferably so as to form a substantially cylindrical internal axial passage, preferably concentric with the central axis (<NUM>),
wherein at least one or more, preferably all of the radially inset side wall portions comprises a thread groove with a groove deepness equal or greater as compared to the groove deepness of the thread in the area directly adjacent to said radially inset side wall portion; and
a flange member (<NUM>), extending radially outward from said plurality of side walls (108a, 108b, 108c, 108d, 108e, 108f) at said second axial end; and
a joining portion (<NUM>) integrally formed between said head member (<NUM>) and said flange member (<NUM>) and configured to transmit, resiliently, an axial force between said first and second axial ends.