Patent Description:
Temporary fasteners are frequently used in manufacturing to hold workpieces together while permanent fasteners are installed. Such fasteners are installed in a few holes in the workpieces to align and pull the parts together that are to be joined so that permanent fasteners may be installed in the remaining holes, after which the temporary fasteners are removed for installation of permanent fasteners in these holes also.

Ideal temporary fasteners may have various characteristics, depending on their application. In general, as previously mentioned, temporary fasteners are intended to align and pull the parts together so that permanent fasteners may be installed. Consequently, a temporary fastener should have the capability of pulling together workpieces that may initially have a substantial separation (commonly referred to as "sheet takeup"), so that the installer does not have to resort to other means to pull the workpieces together sufficiently to properly install the temporary fastener.

Also, while the workpieces will not be subjected to the same loads they may encounter in use after the permanent fasteners are installed, the temporary fasteners typically will only be installed in a small percentage of the fastener holes in the workpieces, such as every tenth hole or so. This, plus a desired large and strong sheet takeup capability, makes temporary fastener strength an important parameter.

Other important parameters for temporary fasteners include low fastener cost, and ease of installation and removal. Simplicity of fastener design and assembly, together with a simple installation operation contributes to low cost and ease of operation, as does a large and strong sheet take-up capability. Removal of temporary fasteners varies with the fastener design, some fasteners being disassembled for removal and others being drilled out for removal. Drilling out of temporary fasteners is perfectly acceptable and may be a favored method of temporary fastener removal, provided the fastener is a low cost fastener and the drilling operation itself doesn't foster other complications.

In an example, rivets fasten workpieces for a fuselage of an airplane. Temporary fasteners are typically installed into adjacent parts to insure that the workpieces do not become separated during the installation of the permanent rivets. The temporary fasteners are eventually removed and replaced with a permanent rivet. Blind rivets are typically utilized when workpieces are not fully accessible. These blind rivets only require one side of the workpiece to be accessible. As described in our <CIT> entitled "Tacking Fastener", temporary blind fasteners typically contain a pull stem and a sleeve which extends through a hole drilled through the workpieces. The sleeve has a head which prevents the fastener from falling into the "blind" side of the assembly. The pull stem has a head that is completely pulled through the sleeve to expand the sleeve and secure the fastener to the workpieces. The temporary fastener is eventually removed by drilling through the head and the sleeve with a drill of the proper diameter for the sleeve of the permanent rivet to be installed.

Drilling of temporary fasteners often results in scratching or other damage to the workpiece. Moreover, chips that break off from the fastener may lead to damage of the workpiece, may fall into components, or may bind a drill bit. It would be beneficial to provide a fastener that does not break into large chips, reduces potential for damage to a workpiece, and provides for more efficient fastening.

Among known permanent fasteners, <CIT> describes a blind rivet assembly in which the head of the stem is fully enclosed in the end of the sleeve both before and after use. In the conventional way, the stem breaks in use at a swaged neck formed at a distance from the head. Our <CIT> describes a blind rivet fastener in which the stem has a break groove between a thick stem part near the head and the serrated pull portion, and a locking groove in the thick stem part, near the break groove, into which a locking collar is deformed during installation. Another blind tacking fastener of the prior art is shown in <CIT> which discloses that the stem head (tension pin head 2b) is separated from the sleeve (hollow shank 1b) following the fracturing of the stem head (tension pin head 2b) from the stem body (cylindrical shank 2a) at a breaking neck 2c on the stem.

The following presents a summary of this disclosure to provide a basic understanding of the invention. This summary is not intended to identify key or critical elements or define any limitations of embodiments. Furthermore, this summary may provide a simplified overview of some aspects that may be described in greater detail in other portions of this disclosure.

In a first aspect we provide a blind tacking fastener with the features of claim <NUM>. The diameter of the stem head may be generally equal to a diameter of a body of the sleeve. The sleeve may comprise at least one of aluminum or an aluminum alloy. The stem may comprise steel. The sleeve may further comprise a first end comprising an annular shoulder and a second end. The second end may comprise an inner perimeter and an outer perimeter, the inner perimeter generally offset from the outer perimeter. The blind tacking fastener may comprise a bulb disposed between the stem head and end of the sleeve.

In a second aspect a method of installing a blind tacking fastener comprises the steps as set out in claim <NUM>. The pulling force may deform a surface of the sleeve abutting the stem head. The stem may be removed from the sleeve while the stem head is removed from the stem. The method may also include drilling out the sleeve to apply a permanent fastener. In at least one embodiment, the method may include selecting at least one of a material used or dimension of the sleeve to allow for removal of the stem head from the sleeve. In another example, the method may include selecting at least one of a material used or dimension of the sleeve to allow for embedding of the stem head within the sleeve.

As mentioned above, a bulb may be positioned about the body of the stem, between the stem head and the sleeve. The bulb may be a separate construction from the stem or may be a unitary construction with at least one of the stem head or the body. The bulb may include a generally frustoconical cross-sectional shape when not deformed. An end of the sleeve proximal to the bulb may be angled towards the inner channel to direct the bulb towards the channel.

The following description and the drawings disclose various illustrative aspects. Some improvements and novel aspects may be expressly identified, while others may be apparent from the description and drawings.

The accompanying drawings illustrate various systems, apparatuses, devices and related methods, in which like reference characters refer to like parts throughout, and in which:.

Reference will now be made to exemplary embodiments, examples of which are illustrated in the accompanying drawings. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made. Moreover, features of the various embodiments may be combined as long as they fall within the wording of the appended claims. As such, the following description is presented by way of illustration only and should not limit in any way the various alternatives and modifications that may be made to the illustrated embodiments. In this disclosure, numerous specific details provide a thorough understanding of the subject disclosure. It should be understood that aspects of this disclosure may be practiced with other embodiments not necessarily including all aspects described herein, the invention being limited solely by the wording of the appended claims.

As used herein, the words "example" and "exemplary" mean an instance, or illustration. The words "example" or "exemplary" do not indicate a key or preferred aspect or embodiment. The word "or" is intended to be inclusive rather than exclusive, unless context suggests otherwise. As an example, the phrase "A employs B or C," includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). As another matter, the articles "a" and "an" are generally intended to mean "one or more" unless context suggests otherwise.

As used herein, terms such as "user," "operator," and the like are employed interchangeably throughout the subject specification, unless context suggests otherwise or warrants a particular distinction among the terms. It is noted that such terms may refer to human entities or automated components such as automated robotic assembly devices. Such devices may be controlled by a user, supported through artificial intelligence (e.g., a capacity to make inference), programmed for a particular user, or the like. For instance, examples describing a user drilling a tack rivet may include a human user with a hand held drill, a human operating a robotic arm having a drill, an automated machine that utilizes a drill, or the like.

Described embodiments generally refer to temporary tack rivets that may hold two workpieces together. Such rivets may be utilized in a variety of applications including automotive and aerospace applications. As such, references to particular applications (e.g., automotive applications or aerospace applications) are for illustrative purposes. Moreover, the term "workpiece" may refer to any piece of material that is to be held together with another piece of material. While workpieces may be described as metal, the materials utilized may vary.

Tack rivets described herein may provide structural integrity to the workpieces. Moreover, the tack rivets may be drilled out and a permanent rivet or other fastener may be installed in the workpieces. Disclosed rivets may comprise various materials, such as aluminum alloys (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> aluminum alloy), other metals, plastics, or the like.

The disclosed tack rivets generally comprise a shank or sleeve and a pin or stem. It is noted that the terms "sleeve" and "shank" may be used interchangeably, likewise the terms "pin" and "stem" may be used interchangeably. The stem may be solid or hollow. Moreover, the stem includes a head on one end and a gripping portion (e.g., a grooved or serrated region). The sleeve comprises a body having an inner channel. Once installed into a workpiece, the stem is pulled and the head of the stem is removed. In examples, the head of the stem deforms a blind side of the sleeve. The head is operatively separated from the stem and is discarded. In some not claimed examples, the head may be embedded within the sleeve but according to the invention it is completely detached from the sleeve and the stem. The installed sleeve may fasten together workpieces and may be drilled out or otherwise removed at a later time.

For instance, a body of the stem is disposed through an inner channel of the sleeve. The assembled stem and sleeve are inserted into apertures of workpieces. A collar of the sleeve abuts a workpiece on the non-blind side and prevents the sleeve from passing through the apertures. The pull stem includes a detachable head on the blind side. The head is sized generally smaller in diameter or perimeter than the apertures so that it may pass therethrough but is larger than the perimeter of the inner channel of the sleeve. A user pulls the pull stem from the non-blind side via the serrated portion. The head deforms the blind side of the sleeve as the pull stem is pulled from the non-blind side. The head becomes detached therefrom. According to the invention, the head is not embedded in the sleeve and is discarded. The sleeve may be later drilled out with a drill head. The drill head may comprise a diameter that is larger than the diameter of a head of the sleeve.

The head of a sleeve of disclosed embodiments may include three or more recesses or cut-outs formed around the periphery of the head of the sleeve. The head may include four recesses that are spaced apart from each other. As the head is drilled, chip pieces from the head are removed by the drill bit. The recesses break up the chip sizes. The reduced chip sizes prevent or reduce the chances of scratching the workpiece, binding flutes of a drill bit, or the like. It is noted that four cut-outs have been found to provide particularly desirable results even as opposed to heads with three cut-outs. Furthermore, four evenly spaced cut-outs prevent the head from coming apart in large sections, which may be particularly undesirable as such sections may bind a drill bit, scratch a workpiece, become lost in a part, or otherwise provide negative effects. It is noted, however, that some embodiments may not include recesses in the head of the sleeve.

<FIG> depict a tack rivet <NUM> in pre-installation, installing, and installed phases, respectively. The tack rivet <NUM> primarily includes a stem <NUM> and a sleeve <NUM>. The stem <NUM> and the sleeve <NUM> are operatively inserted within an aperture <NUM> to secure together a first work piece <NUM> and a second work piece <NUM>. The tack rivet <NUM> may comprise a temporary tack rivet that may be removed at a later time, such as when permanently fastening together the first and second work pieces <NUM>, <NUM>. It is noted that the tack rivet <NUM> may be assembled or constructed according to various methods. Moreover, components of the tack rivet <NUM> may comprise various materials, such as appropriate metals and alloys.

Stem <NUM> may generally comprise a generally cylindrical body <NUM> extending from a stem head <NUM> to a serrated portion <NUM>. The body <NUM> may be solid, hollow, or the like. In an aspect, the body <NUM> may be inserted within an inner channel <NUM> of the sleeve <NUM> as described herein. The serrated portion <NUM> may comprise formations that provide a gripping surface. As such, the serrated portion <NUM> may comprise a portion of the body <NUM> that has serrations, ridges, a roughened surface, or the like. The stem head <NUM> comprises a generally annular protrusion or ring member. In an aspect, the outer perimeter of the stem head (e.g., circumference for annular stem heads) may generally prevent the stem head <NUM> from passing through the inner channel <NUM> of the sleeve <NUM>.

The sleeve <NUM> may comprise the sleeve body <NUM> extending from the first end <NUM> to the second end <NUM>. The first end <NUM> may include an annular shoulder <NUM>. The annular shoulder <NUM> may be operatively sized to prevent the annular shoulder <NUM> from passing through the aperture <NUM>. For instance, the annular shoulder <NUM> may extend away from a center of the sleeve <NUM> a greater distance than the sleeve body <NUM>. It is noted that the annular shoulder <NUM> may comprise one or more sections, chip break areas (as described herein), or the like. In at least one embodiment, the annular shoulder <NUM> may include a transition portion <NUM>. The transition portion <NUM> may comprise an annular generally concave portion, frustoconical portion, chamfered portion, or the like.

The second end <NUM> may comprise an angled or otherwise tapered end <NUM>. The second end <NUM> may be angled inwards. For instance, an inner perimeter <NUM> of the second end <NUM> may extend a lesser distance from the body <NUM> than an outer perimeter <NUM> of the body. In an aspect, this may allow for alignment of the stem head <NUM> and bulb <NUM> when the body <NUM> is pulled or removed for installation as described herein.

In exemplary embodiments, a user drills a hole or aperture through the first work piece <NUM> and the second work piece <NUM> during an assembly process. While the assembly process is occurring, the user may need to temporarily hold the first work piece <NUM> and the second work piece <NUM> so that they maintain operative alignment. Thus, the user may insert the tacking rivet <NUM> into the aperture <NUM>. The user operatively selects a drill bit for drilling the aperture <NUM> that will result in generally the same or slightly larger aperture relative to the outer perimeter of the body <NUM>.

The user then pulls the serrated portion <NUM> of the stem <NUM> from a first side or a side where the user has access and can see, such as the sight side <NUM>. The backside or blind side <NUM> is generally not accessible to the user. As the stem is pulled, the bulb <NUM> aligns with the second end <NUM>. A portion of the body <NUM> extends beneath the blind surface <NUM>. Thus, as the stem <NUM> is pulled, this portion is not supported by the aperture <NUM> and the bulb <NUM> may force this portion to flare outward as an upset portion <NUM>. The annular shoulder <NUM>, likewise, may be deformed against the top surface <NUM>. As the annular shoulder <NUM> and the upset portion <NUM> are deformed, the body <NUM> is secured within the aperture <NUM>.

The serrated portion <NUM> can be pulled until the bulb <NUM> and the stem head <NUM> may become detached from the body <NUM>. The stem head <NUM> which may be referred to as a fraction ring <NUM> and body <NUM> separate at fracture points <NUM>. It is noted that one or more of the bulb <NUM> may become embedded within the upset portion <NUM>. This may prevent the bulb <NUM> from falling or becoming lost. In other embodiments, the bulb <NUM> may be allowed to fall or otherwise not be embedded within the upset portion <NUM>. It is noted that the selection of materials may, for instance, dictate whether the bulb <NUM> or stem head <NUM> become embedded or not. For instance, the sleeve <NUM> may generally comprise a softer material than the stem head <NUM> and bulb <NUM>. If the softness of the sleeve <NUM> is sufficiently low relative to the stem head <NUM> and bulb <NUM>, they may be embedded into the sleeve <NUM>. If the softness of the sleeve <NUM> is increased, the stem head <NUM> and bulb <NUM> will not be embedded. Moreover, it is noted that the stem head <NUM> may comprise a material selected such that the stem head <NUM> becomes detached and not embedded, while the bulb <NUM> comprises a material selected to be embedded. It is noted that whether the bulb <NUM> or stem head <NUM> become embedded or not may depend on a number of adjustable or selectable variables, such as the materials used, the dimensions of the component parts, or the like. For instance, the dimensions of the sleeve <NUM> may be selected to allow for or prevent the bulb <NUM> or stem head <NUM> embedding. In examples, the length of the sleeve <NUM>, thickness of side walls of the sleeve <NUM>, and materials used may be selected such to allow or prevent embedding. It is noted that the if inner diameter of the sleeve <NUM> and outer diameter sleeve <NUM> is too thick it will prevent driving of the bolt.

In embodiments, the bulb <NUM> may comprise a bead-like body having an aperture that receives the body <NUM> of the stem <NUM>. This may allow the bulb <NUM> to comprise a separate construction from the stem head <NUM> and body <NUM>. The surface <NUM> of the stem head <NUM> that abuts the bulb <NUM> may be operatively shaped to align the bulb <NUM>. For instance, the surface <NUM> may be angled, curved (e.g., concave or convex), tapered, chamfered, or the like.

In other embodiments, the bulb <NUM> may be unitarily formed with the stem head <NUM> or body <NUM>, or may be operatively attached thereto (e.g., such as via welding, adhesives, magnetic connections, etc.). For example, the bulb <NUM> may be cast with the stem head <NUM> or body <NUM>, welded to the stem head <NUM> or body <NUM>, or the like.

The bulb <NUM> may comprise a U-shaped cross section or may comprise other shapes. For instance, the bulb <NUM> may be cylindrical, spherical, an n-side polygonal shape (where n is a number), irregular in shape, or the like. In some embodiments, the bulb <NUM> generally tapers towards the body <NUM> such that a portion of the bulb <NUM> proximal the stem head <NUM> has a larger perimeter than the portion of the bulb <NUM> proximal the second end <NUM> of the sleeve <NUM>. This may allow the bulb <NUM> to align with the second end <NUM> during installation.

Turning to <FIG>, there is a tacking rivet <NUM> in accordance with various disclosed embodiments. Tacking rivet <NUM> may comprise similar aspects as tacking rivet <NUM> of <FIG>. For instance, tacking rivet <NUM> may primarily comprise a stem <NUM>, a sleeve <NUM> and a bulb <NUM>. Moreover, the tacking rivet <NUM> may be inserted within an aperture <NUM> formed through a first workpiece <NUM> and a second workpiece <NUM>. The tacking rivet <NUM> may be similarly installed within the aperture <NUM> as the tacking rivet <NUM> of <FIG>. As an example, the user may pull a serrated portion <NUM> of a body <NUM> of the stem <NUM> through an inner channel <NUM> of the sleeve <NUM>. A stem head <NUM> and bulb <NUM> exert pressure or force on a second end <NUM> of the sleeve <NUM>. This may cause deformed or upset portion <NUM> to mushroom or extend outwards and prevent the sleeve <NUM> from passing through the aperture <NUM>. The first end <NUM> of the sleeve <NUM> may be flattened (which may result from pulling the stem <NUM> and/or mechanically flattening the second end <NUM> from the non-blind side.

The bulb <NUM> is shown as comprising a frustoconical outer surface with a vertex pointed towards the second end <NUM>. As the serrated portion <NUM> is pulled, the bulb <NUM> is aligned with the second end <NUM>. Various embodiments may be embedded or may allow for release of at least one of the bulb <NUM> or the stem head <NUM> as described herein. Moreover, bulb <NUM> may comprise similar aspects as described with reference to bulb <NUM>.

<FIG> illustrate a tacking rivet <NUM> in accordance with various disclosed embodiments. Like-named components of tacking rivet <NUM> may comprise similar aspects as those of tacking rivets <NUM>, <NUM>, and other tacking rivets described herein. For instance, the sleeve <NUM> and stem <NUM> may comprise similar aspects as sleeves <NUM>, <NUM> and stem <NUM>, <NUM>.

The tacking rivet <NUM> primarily comprises a stem <NUM>, sleeve <NUM>, and a stem head <NUM>. It is noted that the tacking rivet <NUM> may not include a bulb in at least some embodiments though variations of tacking rivet <NUM> may include a bulb. Similar to tacking rivets <NUM> and <NUM>, the tacking rivet <NUM> may comprise a temporary rivet, which may be a blind rivet. The sleeve <NUM> and stem <NUM> are positioned within an aperture <NUM> formed through work pieces <NUM> and <NUM>. The stem <NUM> may be removed by pulling serrated portion <NUM>. As the stem <NUM> is pulled, the stem head <NUM> may flatten or otherwise deform a second end <NUM> of the sleeve <NUM>. This may secure the sleeve <NUM> in an operative position as described herein.

The stem head <NUM> may comprise a diameter <NUM>, or cross-sectional width for non-annular embodiments, that is generally equal to a diameter <NUM> of a sleeve body <NUM>. As such, the stem head <NUM> and the sleeve body <NUM> may pass through the aperture <NUM> to the blind side of the work pieces <NUM>, <NUM>. Moreover, the stem head <NUM> may be positioned at an end <NUM> of a body <NUM> or may be offset from the end <NUM> as illustrated. A surface <NUM> of the stem head <NUM> that is proximal or abuts the end <NUM> of the sleeve <NUM> may be generally angled or curved. As the stem <NUM> is pulled, the surface <NUM> may flatten or deform from pressure or force of the upset portion <NUM>.

When installing, the annular shoulder <NUM> may be held in place and the stem <NUM> may be pulled. As the stem head <NUM> fractures at fracture point <NUM>, the stem head <NUM> may be embedded within the upset portion <NUM> (as shown in <FIG> and according to a not claimed embodiment) or may be freed as shown in <FIG>. It is noted that the surface <NUM> may comprise protrusions, anchors, spikes, or other formations that bite or dig into the surface <NUM> such that the stem head <NUM> is embedded within the upset portion <NUM>.

<FIG> illustrate a tacking rivet <NUM> that may primarily comprise a stem <NUM>, a sleeve <NUM>, and a stem head <NUM> in accordance with various disclosed and not claimed embodiments. As described herein, the tacking rivet <NUM> may comprise similar aspects to the various tacking rivets of the other figures. The tacking rivet <NUM> may be installed into an aperture <NUM> of first and second workpieces <NUM>, <NUM>.

The stem head <NUM> may comprise a "Y" or "V" shape comprising one or more flanges <NUM> extending from the stem <NUM>. As the stem <NUM> is pulled, the flanges <NUM> deform an end <NUM> of the sleeve <NUM>, so that the upset portions <NUM> secure the sleeve <NUM> in the aperture <NUM>. The end <NUM> may be angled, curved, or the like as described herein. <FIG> illustrates a nut <NUM> that may act as a wedge or bulb to deform the sleeve <NUM> during installation.

Turning to <FIG>, there is an exemplary sleeve <NUM> in accordance with various disclosed embodiments. It is noted that the sleeve <NUM> may be utilized with various tacking rivets described herein. The annular sleeve <NUM> may comprise a chip-break feature <NUM>, such as at least three cutouts <NUM> (e.g., three, four, five, etc.). The cutouts <NUM> may be spaced apart the annular sleeve <NUM>. In an aspect, when the sleeve <NUM> is installed in one or more workpieces, the user drills out the annular sleeve <NUM>. The cutouts <NUM> may prevent a drill from forming a wire or ribbon of material. Such ribbons may scratch or damage a surface of a workpiece. Moreover, the cutouts <NUM> may prevent the annular sleeve <NUM> from generating chips during the drilling process.

<FIG> are an exemplary prototype <NUM> of a tacking rivet in accordance with various disclosed embodiments. The prototype <NUM> may comprise similar aspects as the tacking rivets described with reference to the various figures.

Claim 1:
A blind tacking fastener (<NUM>-<NUM>) comprising:
a stem (<NUM>-<NUM>) comprising:
a gripping portion (<NUM>-<NUM>);
a stem head (<NUM>-<NUM>) having a ring member (<NUM>); and
a body (<NUM>-<NUM>) extending from the stem head to the gripping portion; and
a sleeve (<NUM>-<NUM>), the sleeve comprising an inner channel (<NUM>-<NUM>), wherein the body of the stem passes through the inner channel of the sleeve, and
wherein the stem comprises a first material and the sleeve comprises a second material, wherein the ring member (<NUM>) is fracturable from the body of the stem along fracture points (<NUM>-<NUM>) and detachable from the sleeve (<NUM>-<NUM>) and the body of the stem by a pulling force exerted on the gripping portion.