Patent Description:
Vehicle frames, storage racks, solar panel sub-structures, and other structures can include numerous mechanical fasteners. For example, a fastener can be installed in a bore of a vehicle frame structural component to join individual elements. Failure of a fastener in a structural component can be a result of, for example, fatigue stresses on the fastener or geometric variations in the bore in which the fastener is disposed. Designing a fastener for blind installation presents challenges. <CIT> discloses a blind fastener device for fastening workpieces, including a sleeve and an expander. <CIT> discloses a blind fastener comprising: a nut with a threaded bore; a core bolt having external threads for receipt by the nut; and a sleeve for expansion to form a blind side folded bulb against the backside sheet of a joint.

In one aspect, the present invention provides a blind fastener comprising a sleeve and a mandrel. The sleeve comprises a first sleeve end, a second sleeve end, and a cavity extending from the first sleeve end to the second sleeve end. The mandrel is configured to be at least partially received by the cavity of the sleeve. The mandrel comprises a first mandrel end disposed adjacent to the first sleeve end and comprising an enlarged portion having a diameter greater than a diameter of the cavity, a second mandrel end comprising a pull region, and a shank region extending intermediate the first mandrel end and the second mandrel end. The pull region comprises an axial length no greater than <NUM> times a diameter of the shank region and is configured to be engaged by an installation tool.

In another aspect, the present invention provides a method for fastening. The method comprises inserting a first mandrel end of a blind fastener into a bore in a structure. The blind fastener comprises a sleeve and a mandrel. The sleeve comprises a first sleeve end, a second sleeve end, and a cavity extending from the first sleeve end to the second sleeve end. The mandrel is configured to be at least partially received by the cavity of the sleeve. The mandrel comprises a first mandrel end disposed adjacent to the first sleeve end and comprising an enlarged portion having a diameter greater than a diameter of the cavity, a second mandrel end comprising a pull region, and a shank region extending intermediate the first mandrel end and the second mandrel end. The pull region comprises an axial length no greater than <NUM> times a diameter of the shank region and is configured to be engaged by an installation tool. A collet of the installation tool is engaged with the pull region of the blind fastener. After inserting the blind fastener into the bore in the structure, the second sleeve end of the blind fastener is forcibly contacted with an anvil of the installation tool, and the pull region is moved distal from the second sleeve end utilizing the collet of the installation tool. The portion of the sleeve on a first side of the structure is deformed, and the second sleeve end is swaged onto the shank region of the mandrel on an oppositely disposed second side of the structure, thereby securing at least a portion of the blind fastener in the structure.

It is understood that the invention disclosed and described in this specification is not limited to the aspects summarized in this Summary.

The features and advantages of the examples, and the manner of attaining them, will become more apparent, and the examples will be better understood, by reference to the following description taken in conjunction with the accompanying drawings, wherein:.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate certain embodiments, in one form, and such exemplifications are not to be construed as limiting the scope of the appended claims in any manner.

Various examples are described and illustrated herein to provide an overall understanding of the structure, function, and use of the disclosed articles and methods. The various examples described and illustrated herein are non-limiting on the scope of the appended claims and non-exhaustive. Thus, an invention is not limited by the description of the various non-limiting and non-exhaustive examples disclosed herein. Rather, the invention is defined solely by the appended claims. The features and characteristics illustrated and/or described in connection with various examples may be combined with the features and characteristics of other examples within the scope of the appended claims.

Any references herein to "various embodiments," "some embodiments," "one embodiment," "an embodiment," or like phrases mean that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," "in an embodiment," or like phrases in the specification do not necessarily refer to the same embodiment. Furthermore, the particular described features, structures, or characteristics may be combined in any suitable manner within the scope of the appended claims in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features, structures, or characteristics of one or more other embodiments within the scope of the appended claims.

In this specification, unless otherwise indicated, all numerical parameters are to be understood as being prefaced and modified in all instances by the term "about," in which the numerical parameters possess the inherent variability characteristic of the underlying measurement techniques used to determine the numerical value of the parameter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter described herein should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

As used herein, "intermediate" means that the referenced element is disposed between two elements but is not necessarily in contact with those elements. Accordingly, unless stated otherwise herein, an element that is "intermediate" a first element and a second element may or may not be adjacent to or in contact with the first and/or second elements, and other elements may be disposed between the intermediate element and the first and/or second elements.

Failure of a fastener in a structural component can be a result of in-service fatigue, overload on the structural component, and corrosion. The present disclosure provides a blind fastener and a method of installation that can reduce installation forces and increase corrosion resistance. For example, the blind fastener according to the present disclosure may be installed with an installation force less than a force that can fracture the mandrel. Reducing the installation force requirement and installing without a shock force occurring during fracture of the mandrel can enable lighter weight installation tools, longer life of installation tool components, limit damage to the structural components, and enhance ergonomics for operators using the installation tools.

<FIG> illustrates a cross-sectional side view of an embodiment of a blind fastener <NUM> according to the present disclosure. The blind fastener <NUM> can be adapted to be installed in a bore in a structure (e.g., as illustrated in <FIG>, discussed below). The blind fastener <NUM> can include a sleeve <NUM> and a mandrel <NUM>. In various embodiments, the sleeve <NUM> is generally cylindrical. <FIG> shows a portion of the sleeve removed, exposing the mandrel <NUM> therein. The sleeve <NUM> can comprise a first sleeve end <NUM>, a second sleeve end <NUM>, an elongate portion <NUM> disposed intermediate the first sleeve end <NUM> and the second sleeve end <NUM>, and a cavity <NUM> extending from the first sleeve end <NUM> to the second sleeve end <NUM>.

The cavity <NUM> of the sleeve <NUM> can comprise a diameter, d<NUM>, and be configured to at least partially receive the mandrel <NUM> therein. For example, the mandrel <NUM> can comprise a shape suitable to be received by the cavity <NUM>, such as, for example, a generally cylindrical shape. The mandrel <NUM> can comprise a first mandrel end <NUM>, a second mandrel end <NUM>, and a shank region <NUM>. The shank region <NUM> can extend intermediate the first mandrel end <NUM> and the second mandrel end <NUM> and through the cavity <NUM>. When the mandrel <NUM> is inserted in the cavity <NUM>, the first mandrel end <NUM> can be disposed adjacent to the first sleeve end <NUM>, and the second mandrel end <NUM> can be disposed adjacent to the second sleeve end <NUM>.

The first mandrel end <NUM> can comprise an enlarged portion <NUM> comprising a diameter, d<NUM>, which can be greater than the diameter, d<NUM>, of the cavity <NUM>. The enlarged portion <NUM> can engage the first sleeve end <NUM> of the cavity <NUM> and inhibit further movement of the first mandrel end <NUM> into the cavity <NUM> of the sleeve <NUM>. The enlarged portion <NUM> can apply a force to the first sleeve end <NUM> and can deform the first sleeve end <NUM> during installation of the blind fastener <NUM>. For example, the first sleeve end <NUM> can be crumpled (e.g., into a bulb shape) and/or expanded.

The second mandrel end <NUM> can comprise a pull region <NUM> configured to be engaged by an installation tool (e.g., installation tool <NUM>, as illustrated in <FIG> discussed below). The pull region <NUM> can comprise an axial length, l, that is no greater than <NUM> times, no greater than <NUM> times, no greater than <NUM> times, no greater than <NUM> times, no greater than <NUM> times, or no greater than <NUM> times the diameter, d<NUM>, of the shank region <NUM>. The diameter, d<NUM>, of the shank region <NUM> can be the major diameter (e.g., root) of the shank region <NUM>.

The pull region <NUM> can comprise a taper or a reverse taper. As illustrated, the pull region <NUM> can comprise a taper extending from the shank region <NUM>. For example, as one moves along the pull region <NUM> away from the shank region <NUM> along a longitudinal axis of the blind fastener <NUM>, the diameter of the pull region <NUM> can decrease. In certain other embodiments, the pull region <NUM> can comprise a reverse taper (not shown) where, as one moves along the pull region <NUM> away from the shank region <NUM> along the longitudinal axis of the blind fastener <NUM>, the diameter of the pull region <NUM> increases. In various embodiments, the pull region <NUM> can be generally conical. In various other embodiments, the pull region <NUM> may not comprise a taper and the pull region <NUM> can be generally cylindrical.

The pull region <NUM> can comprise at least one of a generally smooth region, an annular shoulder, a groove, and a bore, or can comprise another feature, configured to be engaged by an installation tool. For example, the pull region <NUM> can comprise grooves <NUM>, as illustrated in <FIG>, that can be engaged by an installation tool.

The shank region <NUM> can define the longitudinal axis of the blind fastener <NUM>. The shank region <NUM> can comprise at least one of a generally smooth region, a threaded region, an annular shoulder, and a groove. The threaded region, annular shoulder, and/or the groove can be external relative to the mandrel <NUM>. In various embodiments, all or a portion of the shank region <NUM> includes grooves. For example, as shown in <FIG>, the shank region <NUM> of the blind fastener <NUM> includes grooves <NUM>. In other embodiments, all or a portion of the shank region <NUM> lacks grooves. In various embodiments, all or a portion of the shank region <NUM> includes an annular shoulder. In other embodiments, the shank region <NUM> lacks an annular shoulder. In various embodiments, all or a portion of the shank region <NUM> includes a threaded portion. In other embodiments, the shank region <NUM> lacks a threaded portion.

In various embodiments of blind fastener <NUM>, the mandrel <NUM> does not comprise a breakneck groove or other feature configured to fracture upon installation of the blind fastener <NUM>. For example, the shank region <NUM> may not comprise a breakneck groove or other feature configured to fracture upon installation of the blind fastener <NUM>. The mandrel <NUM> may remain intact after installing the blind fastener <NUM> into a structure. In various embodiments, the blind fastener <NUM> may comprise a breakneck groove or other feature configured to fracture upon installation of the blind fastener <NUM>, and the blind fastener <NUM> may be installed into a structure without fracturing of the breakneck groove or other feature.

In various embodiments, the blind fastener <NUM> can comprise a single assembly of the sleeve <NUM> and the mandrel <NUM>. In certain embodiments, the blind fastener <NUM> can consist of the sleeve <NUM> and the mandrel <NUM>. In some embodiments, the blind fastener <NUM> can be a structural blind fastener, such as, for example, a structural blind rivet, structural blind bolt, or a structural blind stud.

The blind fastener <NUM> can comprise at least one of a metal, a metal alloy, and a composite material. For example, in various embodiments the blind fastener <NUM> can comprise at least one of aluminum, an aluminum alloy, titanium, a titanium alloy, nickel, a nickel alloy, iron, an iron alloy, and a carbon fiber composite material. In various embodiments, the mandrel <NUM> can comprise a Rockwell hardness of at least HRC <NUM>, such as, for example, at least HRC <NUM>, at least HRC <NUM>, at least HRC <NUM>, at least HRC <NUM>, at least HRC <NUM>, at least HRC <NUM>, or at least HRC <NUM>.

The sleeve <NUM> can comprise a collar <NUM> positioned adjacent to the second sleeve end <NUM>. The collar <NUM> can be configured to be engaged by an installation tool (e.g., installation tool <NUM> illustrated in <FIG>) in order to facilitate installation of the blind fastener <NUM>. The sleeve <NUM> can be configured to deform on the exit side of the structure and swage onto the shank region <NUM> an oppositely disposed entrance side of a structure. For example, the first sleeve end <NUM> can be deformed and the collar <NUM> can be swaged onto the shank portion <NUM>, as illustrated in <FIG>. In various embodiments, the collar <NUM> can be a head portion of the sleeve <NUM>.

As illustrated in <FIG>, the blind fastener <NUM> can be installed into a bore <NUM> in a structure <NUM>. The bore <NUM> can extend through the structure <NUM>. The structure <NUM> can comprise, for example, at least one of a metal, a metal alloy, and a composite. For example, in certain embodiments, the structure <NUM> can comprise at least one of aluminum, an aluminum alloy, titanium, a titanium alloy, nickel, a nickel alloy, iron, an iron alloy, and a carbon fiber composite material.

In various embodiments, the structure into which the blind fastener <NUM> is assembled comprises aluminum and/or an aluminum alloy such as, for example, <NUM> aluminum. With reference to the accompanying figures, the structure <NUM> can be configured as at least one of an aerospace component or structure, an automotive component or structure, a transportation component or structure, and a building and construction component or structure. The structure <NUM> can comprise a single layer of material or at least two layers of material. For example, as illustrated in <FIG>, the structure <NUM> can comprise a first layer <NUM> and a second layer <NUM>. Upon installation into the bore <NUM>, the blind fastener <NUM> can secure the first layer <NUM> and the second layer <NUM> together, as illustrated in <FIG>.

As illustrated in <FIG>, in a first configuration of the blind fastener <NUM> and the structure <NUM>, the first mandrel end <NUM> of the blind fastener <NUM> can be positioned in alignment with the bore <NUM>. To facilitate alignment of the blind fastener <NUM> with the bore <NUM>, the bore <NUM> can have a diameter, db, that is greater than the diameter, d<NUM>, of the enlarged portion <NUM> of the first mandrel end <NUM>, thereby allowing the mandrel <NUM> to readily move into and through the bore <NUM> when passing from a first configuration of the blind fastener <NUM> and the structure <NUM>, illustrated in <FIG>, to a second configuration, illustrated in <FIG>. In various embodiments, the diameter, db, of the bore <NUM> can be greater than the diameter of the sleeve <NUM> to allow the sleeve to readily pass into the bore <NUM>. The diameter, d<NUM>, of the collar can be greater than the diameter, db, of the bore <NUM>. In the second configuration, shown in <FIG>, the first mandrel end <NUM> has passed into the bore <NUM> and the collar <NUM> of the sleeve <NUM> can be in forcible contact with the structure <NUM> at an entrance side 232a of the structure <NUM>. The forcible contact between the collar <NUM> and the structure <NUM> can limit further axial movement of the sleeve <NUM> into the bore <NUM>.

Before or after insertion, a collet <NUM> of the installation tool <NUM> can engage the pull region <NUM> of the blind fastener <NUM>. For example, the collet <NUM> can be configured to forcibly contact an anvil <NUM> of the installation tool <NUM>. The forcible contact can close the collet <NUM> around the pull region <NUM> where the collet <NUM> forcibly contacts the pull region <NUM>. Upon engagement, the collet <NUM> can apply a force to the pull region <NUM> of the mandrel <NUM>.

The collet <NUM> can move the mandrel <NUM> independently of the sleeve <NUM>. For example, the collet <NUM> can retract within the installation tool <NUM> and move the mandrel <NUM> as the collet <NUM> retracts due to the contact between the pull region <NUM> and the collet <NUM>. Upon the collet <NUM> reaching a predetermined retraction distance into the installation tool, the anvil <NUM> can forcibly contact the second sleeve end <NUM>. The forcible contact between the second sleeve end <NUM> and the anvil <NUM> can move the second mandrel end <NUM> in a vector different than a vector in which the second sleeve end <NUM> may be moving. For example, the installation tool <NUM> can move the pull region <NUM> distal from the collar <NUM> utilizing the collet <NUM> of the installation tool <NUM>.

In various embodiments wherein a pull region <NUM> of the mandrel <NUM> comprises grooves and a taper, the collet <NUM> of the installation tool <NUM> may only be able to apply force to the pull region <NUM> to move the mandrel <NUM> if the collet <NUM> and the grooves <NUM> of the pull region <NUM> are fully engaged, such as is illustrated in <FIG>. A partially engaged collet <NUM> may not be able to apply a force to the pull region <NUM> sufficiently to appropriately move the mandrel <NUM> relative to the sleeve <NUM>. The grooves and taper of the pull region <NUM> can reduce potential stripping of the grooves <NUM> due to crest-to-crest engagement.

In a third configuration of the blind fastener <NUM> and the structure <NUM> illustrated in <FIG>, the first sleeve end <NUM> and the elongate portion <NUM> can be deformed on an exit side 232b of the structure <NUM> responsive to forcible contact from mandrel <NUM>. The second sleeve end <NUM> can be swaged onto the shank region <NUM> on an oppositely disposed entrance side 232a of the structure <NUM> responsive to forcible contact from the anvil <NUM>. For example, the collar <NUM> can be swaged onto the shank region <NUM>. The swaging of the second sleeve end <NUM> and/or deformation of the first sleeve end <NUM> and/or elongate portion <NUM> can secure at least a portion of the blind fastener <NUM> in the structure <NUM>. In that way, for example, the first layer <NUM> and second layer <NUM> of the structure <NUM> are secured together. As shown in the embodiments illustrated in <FIG>, the mandrel <NUM> need not include a breakneck groove or other feature configured to fracture upon installation of the blind fastener <NUM>.

In various embodiments, the blind fastener <NUM> can be used in a method for fastening the structure <NUM>. The method can comprise inserting the first mandrel end <NUM> into the bore <NUM> in the structure <NUM>. The collet <NUM> of the installation tool <NUM> can engage with the pull region <NUM> of the blind fastener <NUM>. After inserting the blind fastener <NUM> into the bore <NUM>, the second sleeve end <NUM> of the blind fastener <NUM> can contact the anvil <NUM> of the installation tool <NUM>. The pull region <NUM> can be moved distal from the collar <NUM> utilizing the collet <NUM> of the installation tool <NUM>. The first sleeve end <NUM> can be deformed on the exit side 232b of the structure <NUM>, and the second sleeve end <NUM> can be swaged onto the shank region <NUM> of the mandrel <NUM> on the opposite, entrance side 232a of the structure <NUM>, thereby securing at least a portion of the blind fastener <NUM> in the structure <NUM>.

The blind fastener according to the present disclosure can enable use of a smaller installation tool for installation since the force required to install the blind fastener may be less than a force that can fracture the mandrel. The blind fastener according to the present disclosure can have a variety of uses since the design of the sleeve may not have to accommodate the force required to fracture the mandrel. For example, the sleeve wall thickness can be reduced by, for example, <NUM>% or <NUM>%, which can save material cost.

Claim 1:
A blind fastener (<NUM>) comprising:
a sleeve (<NUM>) comprising
a first sleeve end (<NUM>),
a second sleeve end (<NUM>), and
a cavity (<NUM>) extending from the first sleeve end to the second sleeve end; and
a mandrel (<NUM>) configured to be at least partially received by the cavity of the sleeve, the mandrel comprising
a first mandrel end (<NUM>) disposed adjacent to the first sleeve end and comprising an enlarged portion (<NUM>) having a diameter greater than a diameter of the cavity,
a second mandrel end (<NUM>) comprising a pull region (<NUM>) configured to be engaged by an installation tool, and
a shank region (<NUM>) extending intermediate the first mandrel end and the second mandrel end,
characterized in that the pull region comprises an axial length (I) no greater than <NUM> times a diameter (d<NUM>) of the shank region.