Temporary fasteners

Fastener embodiments include a housing body, a collet body and a central body. The housing body receives a first portion of the collet body, which has internal threads and an external anti-rotation feature, as well as a first portion of the central body. A second portion of the collet body and an exterior portion of the housing body provide work piece contacting surfaces. The central body, which occupies an inner portion of the housing body, is threadably coupled to the collet body and displaces and/or converges radially displaceable portions of the collet body at the second portion thereof. Interaction between the collet body anti-rotation feature and the housing body, which may be a pair of extending pins engaging a pair of slots, prevents rotation of the collet body within the housing body during rotation of the central body, while axial movement thereof remains unaffected within intended operation parameters.

SUMMARY OF THE INVENTION

The invention is directed towards temporary fasteners (also known as “tack” fasteners) used to hold, at least temporarily, at least two work pieces together where a portion of the fastener is disposed in substantially aligned holes or bores formed in the work pieces. In such a configuration, the outer most work pieces are brought into compression with each other either directly or through any intermediary work pieces by portions of the temporary fastener.

Fasteners according to the invention comprise a housing body, a collet body and a translatable central body. The housing body is configured to receive both a portion of the collet body and a portion of the translatable central body wherein another portion of the collet body and a portion of the housing body provide the work piece contacting surfaces and wherein the translatable central body functions to actively and/or passively displace and/or converge or restore radially displaceable portions of the collet body.

Collet bodies of the various invention embodiments each define a longitudinal axis and generally comprise a first or distal end defining a first generally circular opening and a second or proximal end defining a second generally circular opening. Adjacent to the first end is a first wall portion having an inner surface, an outer surface, and defining at least two secondary slots extending longitudinally from the first end to thereby create at least two flexible fingers. Adjacent to the second end is a second wall portion having an inner surface, and an outer surface.

Depending upon the nature of an invention embodiment, the flexible fingers can be characterized as having a converging, diverging or constant progressing radial profile in a nominal or resting state. As used herein, the term “progressing radial profile” means a series of radius measurements taken along a segment of the collet body axis to the relevant wall outer periphery. Many embodiments comprise collet bodies with a converging progressive radial profile for the first wall portion, e.g., the fingers. This profile minimizes the insertion force necessary to insure that the first or distal end of the collet body extends past the most distal work piece, decreases collet body wear, reduces or eliminates undesired work piece deformation, and enhances the removability of the fasteners from the work pieces.

In addition to the foregoing, a generally annular protrusion extends from the first wall portion, preferably at the first or distal end. The annular protrusion comprises a leading face and a trailing face, both of which can be characterized as segmented by the secondary slots formed in the collet body, where the trailing face comprises a portion of the collet body that is in compressive contact with a work piece during clamp up. For the reasons expressed above, a converging progressive radial profile is particularly attractive in embodiments wherein the annular protrusion materially extends from the outer surface of the first wall portion.

Separating the collet body first and second wall portions may be a mid body portion. Fastener embodiments of the invention having a particularly long stroke or working range will also have a mid body portion that is comparatively long with respect to embodiments having a short stroke or working length, which may not have a mid body portion. The collet body may optionally define a primary slot extending from the first end and preferably (although not necessarily) to the second end. The primary slot may be parallel to the collet body axis, linear but skew to the axis or helical, depending upon the embodiment.

As intimated above, the nature of the collet body material affects its performance. While the collet body can be formed from a myriad of materials, any such materials will have memory properties, malleable properties, or a combination of the two. A memory material will permit temporary distortion of the collet body fingers until the distorting force has been removed, where after the affected portions will return to their initial state or as close to the initial state as possible. Suitable memory materials include spring steel, plastics, composites, and the like. A malleable material will cause a distortion resulting from the application of at least one force to permanently alter the physical state of the affected collet body portion. Suitable malleable materials include certain steels, aluminum and its alloys, titanium and its alloys, and the like. A combination material will exhibit a hybrid response, the nature of which depends largely upon the composition of the material and its environment of use. The intended application for fasteners comprising collet bodies will generally determine the most desirable material composition.

For additional disclosure regarding collet bodies, please refer to International Publication No. WO 2003-069971, which is incorporated herein by reference.

Collet bodies according to the invention that rely upon rotation of the translatable central body to effectuate translation/reciprocation of the collet body within the housing body further comprise a first part of a two part anti-rotation means (hereinafter “collet body ARM” with specific reference to the first part, and “ARM” with general reference to both parts). A variety of ARM arrangements are suitable for counteracting induced rotation of the collet body within the housing body; a valid collet body ARM need only use structure of or associated with the collet body that compressionally impinges a portion of the housing body when rotated within at least a portion of the housing body such that further rotation of the collet body is not possible within the design limits of the fastener.

One series of embodiments relies upon the incorporation of a non-circular cross section portion of the collet body to function as the collet body ARM, e.g., (a) symmetrical elliptical, or regular or irregular polygonal cross section. A simple illustration of this form is a key (protrusion) and slot arrangement where the key may be present on a portion of the collet and the slot formed in the housing body, or vice versa. Naturally, a plurality of keys and slots may be used. The geometric cross-section of the key may be rectilinear, curvilinear and/or polygonal. Moreover, while it is preferable that the housing body bore/hole be complementary in geometry to the key arrangement, it is only necessary that the bore/hole rotationally interfere with the key arrangement, but otherwise permit translation of the first part of the ARM in the second part, as described below. Thus, for example, there may be only two key features present on the collet body, but four slots formed in the housing body. So long as at least one key feature operates to prevent collet body rotation, it is considered a suitable collet body ARM.

Another series of embodiments permits the use of collet bodies having circular peripheral profiles, but provides for at least one, and preferably two, radially extending appendages. These appendages or arms can be considered “keys”, but are usually of sufficient radial length from the collet body so as to require through-body slots formed in the housing body, which will be discussed in detail below.

The housing bodies used in various invention embodiments include first or distal ends and second or proximal ends, by convention, as well as exterior surfaces and interior surfaces. The interior surface of a given housing body defines a bore or hole that extends from the proximal end to the distal end, into which a portion of the collet body comprising the collet body ARM is operatively located and is permitted to axially reciprocate therein. While the bore or hole need not be of constant cross sectional dimensions and/or geometry from one end to the other, in many embodiments of the invention, this is true. The interior surface of the housing body in one series of embodiments further defines a second part of the two part ARM (hereinafter “housing body ARM” with specific reference to the second part) while a sectional portion of the housing body in another series of embodiments defines the housing body ARM.

The housing body also includes a first part of a two part translation arresting means (hereinafter “housing body TAM” with specific reference to the first part, and “TAM” with general reference to both parts) for preventing unintentional escapement of the collet body from at least one end of the housing body where the collet body includes a second part of TAM (hereinafter “collet body TAM” with specific reference to the second part). The housing body TAM generally comprises structure defining an orifice having a diameter less than the collet body TAM, which in many cases comprises the collet body ARM.

Finally, the translatable central bodies found in the various invention embodiments are disposed in the housing bodies and selectively operate to affect the radially oriented displacement of the collet body fingers. Each translatable central body includes a working portion for contacting the inside surface of the fingers when axially translated there towards, and a drive portion for receiving rotational and/or axial force(s) that cause, either directly or indirectly, the working portion to engage with or retract from the collet body fingers.

Due to the interaction between the various fastener components, radial displacement of the collet body fingers by the translatable central body occurs when the central body is moved towards the distal end of the housing. As a consequence, the drive portion of the translatable central body is caused to move into the hole/bore of the housing body. At full translation, many invention embodiments have only a minimal portion of the central body exposed beyond the second or proximal end of the housing body. This state is of particular benefit in certain manufacturing environments wherein minimal fastener height on the tool side is desired or required.

As discussed above with reference to collet bodies with or without ARM(s), the translatable central body of any given fastener according to the invention may be subjected to external axially or rotationally applied force, the later being transformed into axial movement through interaction with a threaded portion of the collet body or linked structure. Either of these forces results in movement of the working portion of translatable central body either towards or away from the collet body fingers. For reference purposes, the former is referred to herein as axially induced translation of the translatable central body while the latter is referred to herein as rotationally induced translation of the translatable central body.

In axially induced reciprocating fastener embodiments, it is not necessary to provide an ARM between the collet body and the housing body—an axial force is applied to the drive portion of the translatable central body, which moves the central body towards the collet body, thereby causing reciprocation over multiple instances of such axial force application. In these invention embodiments, however, it is advantageous to have a biasing means for restoring the translatable central body to its initial state of retraction from the collet body (thereby ensuring that the working portion of the central body is not in contact with the inner surfaces of the collet body fingers, and that the fastener is immediately ready for use). In many embodiments, this biasing means comprises a compression spring wherein one end thereof acts on the housing body at the second or distal end, and another end acts on the translatable central body to thereby cause maximum permitted extension of the central body from the collet body. Application of an axial force to the translatable central body in opposition to the spring bias thereby causes compression of the spring, and permits the working portion of the translatable central body to engage with the inner surfaces of the collet body fingers.

In rotationally induced reciprocating fastener embodiments, the translatable central body comprises a threaded portion that interacts with the collet body either directly through a complementary structure on/in the collet body or indirectly through a linkage to the collet body, whereby rotation of the central body results in translation of the collet body within the housing body. As noted previously, rotationally induced reciprocation embodiments will necessarily employ an ARM so that rotation of the translatable central body translates into axial translation (and reciprocation during counter rotation) of the collet body. In one series of rotationally induced reciprocation embodiments, an interior surface portion of the collet body, usually at or proximate to the second or proximal end, defines threads that are functionally complementary to the threaded portion formed on the translatable central body. In another series of embodiments, a threaded element such as a nut or collar, is securely affixed to the second or proximal end of the collet body. An advantage to using a threaded nut is that the outer surface cross sectional profile is a polygon, which beneficially can function as a collet body ARM as well as a collet body TAM.

Having broadly described the various components of the several invention embodiments, specific implementations thereof can be generally characterized into several forms, namely, axially operated embodiments and rotationally operated embodiments, with the latter having internal ARM variants and external ARM variant. Each form of the invention has advantages over the other, but both share many of the same core components.

Internal ARM series embodiments are generally characterized as having a housing body with a radially closed interior surface wherein the interior surface functions as a reactive structure (or second part) of the collet body ARM. As such, the internal surface geometry of the interior surface (i.e., cross section geometry) is sufficiently complementary to the collet body ARM to prevent unmitigated rotation of a collet body therein, and is axially consistent to permit substantial axial translation within the housing body. Preferably, the interior surface has a cross section geometry that is highly complementary to the collet body ARM such that each portion of the collet body ARM has a corresponding reactive structure at the interior surface of the housing body.

For example in a first instance, the interior surface of the housing body has a hexagonal cross section with each facet thereof having a distance from the housing body axis of Rf. The collet body ARM has a rectangular cross section profile where the major axis is ≈2Rfand a minor axis of <<2Rfsuch that there would otherwise be no rotationally interference. When disposed within the housing body and subject to rotation, two sides of the collet body ARM would contact the interior surface of the housing body while two sides would not; only two of the six sides of the interior surface of the housing body would then function as reactive structures or the second part of the two part ARM. In a second instance, the collet body ARM has a hexagonal cross section profile that is nominally smaller than the internal dimensions of the interior surface of the housing body (to permit free translation within the housing body). In this case, when disposed within the housing body and subject to rotation, portions of all six sides of the collet body ARM would contact the interior surface of the housing body; portions of all six sides of the interior surface of the housing body would then function as reactive structures or the second part of the two part ARM.

External ARM series embodiments are generally characterized as having a housing body with at least one generally axially aligned slot extending from the interior surface to the exterior surface of the housing body to receive a corresponding number of collet body ARM(s). Instead of finding a reactive structure at the interior surface of the housing body (second part of the ARM), the reactive structure is a portion of the sectional perimeter of the housing body slot, i.e., the wall(s) that define(s) the at least one slot. Of course, it is possible to have both internal and external ARM functionality in a single fastener.

For purposes of this patent, the terms “area”, “boundary”, “part”, “portion”, “surface”, “zone”, and their synonyms, equivalents and plural forms, as may be used herein and by way of example, are intended to provide descriptive references or landmarks with respect to the article and/or process being described. These and similar or equivalent terms are not intended, nor should be inferred, to delimit or define per se elements of the referenced article and/or process, unless specifically stated as such or facially clear from the several drawings and/or the context in which the term(s) is/are used.

DESCRIPTION OF INVENTION EMBODIMENTS

Preface: The terminal end of any numeric lead line in the several drawings, when associated with any structure or process, reference or landmark described in this section, is intended to representatively identify and associate such structure or process, reference or landmark with respect to the written description of such object or process. It is not intended, nor should be inferred, to delimit or define per se boundaries of the referenced object or process, unless specifically stated as such or facially clear from the drawings and the context in which the term(s) is/are used. Unless specifically stated as such or facially clear from the several drawings and the context in which the term(s) is/are used, all words and visual aids should be given their common commercial and/or scientific meaning consistent with the context of the disclosure herein.

With the foregoing in mind, the following description is presented to enable a person skilled in the art to make and use the claimed invention. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the generic principles disclosed herein may be applied to other embodiments and applications thereof without departing from the spirit and scope of the present invention, as defined by the appended claims. Thus, the claimed invention is not intended to nor should be limited to the disclosed and/or described embodiments, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Turning then to the several embodiments, wherein like numerals indicate like parts, and more particularly toFIGS. 1-10, a first embodiment of the invention relating to an inexpensive temporary fastener20having an external or projecting collet body ARM is shown from initial engagement with a translatable central body in the form of a threaded rod90with a collet body30(FIG. 1) to a fully clamped-up configuration (FIG. 3). As shown in the various Figures, fastener20comprises a collet body30translatably disposed in housing body70and into which threaded rod90may be rotationally engaged whereby rotation of rod90is transformed into translational movement of collet body30in housing body70.

Collet body30, best shown inFIG. 5, includes first wall portion40whereby a plurality of slots42defined thereby establish fingers44that terminate at first or distal end32and that comprise protruding portion46, each segment of which has leading face48and trailing face50. Collet body30further includes second wall portion60, which defines holes64that extend from outer surface56to inner surface54, and which terminates at second or proximal end52, and a mid body portion36there between the first wall portion40and the second wall portion60. Inner surface54defines threads62, which are complementary to threaded portion96of threaded rod90, thereby permitting threadable engagement there between. A threaded element79is also shown inFIG. 5.

Housing body70, best shown inFIGS. 6-10, includes first or distal end72, second or proximal end76, outer surface80, inner surface78, which includes threaded portion82, the threads of which are complementary to threaded portion96of threaded rod90, thereby permitting threadable engagement there between, and slots86a/b, which will be described in more detail below. Distal end72defines reduced diameter bore or opening74, and thereby establishes wall88.

As best shown inFIG. 4, a first part of an external two-part anti-rotation means (“ARM”) is established by engaging set screws66a/bwith holes64, which thereby form a collet body ARM; housing body70defines, inter alia, the second part of the external two-part ARM, namely, two substantially axially aligned slots86a/bsized to functionally receive set screws66a/b, which thereby form a housing ARM. Note that set screws66a/bdo not interfere with the rotation of threaded rod90, and because of their restricted freedom of movement within slots86a/b, there is no need to mill or otherwise create surface features on inner surface78of housing body70(seeFIGS. 6, 8, and 10). Also note that from the time fingers44are radially expanded (FIG. 2), thrust washer94and drive nut98of threaded rod90are in contact with proximal end76of housing body70through maximum stroke (FIG. 3), thereby achieving a very low clamp-up profile.

A feature of the illustrated embodiment is the presence of non-threaded portion93on threaded rod90. As a consequence of feature, rod90cannot be “backed out” from collet body30during normal operation. A swaged collar or deformed threads can similarly function to prevent threaded disassociation between these components. An additional feature of the illustrated embodiment is the presence of wall88, which functions as a first part of a two part translation arresting means (“TAM”) by contacting wall58of collet body30's second wall portion56, which functions as a second part of the two part TAM, upon maximum extension of collet body30from housing body70.

Tangible benefits of fastener30include a limited parts count, scalability of certain parts for disparate applications, and the use of readily available parts as opposed to custom fabricated parts.FIGS. 4-10exemplify many of these benefits. The discrete parts of fastener20are best shown inFIG. 4. With the exception of collet body30and housing body70, it can be seen that threaded rod90is merely a piece sectioned from a longer continuous threaded rod, that drive nut98is a conventional nut that is swaged, welded or, in the illustrated example, fastened via a roll pin to threaded rod90, and that bushing100is a conventional piece as well. And while housing body70is preferably matched to an intended collet body30, a range of collet bodies and threaded rods can be accommodated by modifying the internal diameter of bushing100and using collet bodies with standardized second wall diameters, regardless of the diameter of opening74. In such instances, however, it may be beneficial to introduce another bushing at end72to closely match the working diameter of first wall portion40.

FIGS. 11-21show a second fastener120comprising collet body130, housing body170, which includes bushing200, and threaded rod190to which is attached drive nut198from initial engagement of threaded rod190with collet body130(FIGS. 11A-C) to a fully clamped-up configuration (FIGS. 14A and 14B).

Unlike fastener20, fastener120includes an internal ARM, although most other aspects of the fastener remain similar (for example, collet body130, best shown inFIGS. 19-21, includes first wall portion140whereby a plurality of slots142defined thereby establish fingers144that terminate at first or distal end132and that comprise protruding portion146, each segment of which has leading face148and trailing face150, and second wall portion160, which terminates at second or proximal end152, while inner surface154defines threads162, which are complementary to threaded rod90, thereby permitting threadable engagement there between, and a sleeve156connecting the first wall portion140and the second wall portion160. Thus, a first part of an internal two-part ARM (the collet body ARM) comprise facets166formed on second wall160(seeFIGS. 19-21) while facets186, which comprise part of inner surface178of housing body170, comprise the second part of the external two-part ARM (the housing ARM) as is best shown inFIGS. 17 and 18.

Because of machining consequences when forming facets186, it may be necessary to retrofit housing body170with the first part of a two part TAM. Thus, a snap ring may be introduced in recess188formed near housing body at first or distal end182(seeFIG. 18) to form this part, as did wall88in fastener20. Similarly, bushing200may be necessary to establish the requisite diameter for receiving rod190; recess188is therefore formed at second or proximal end176into which bushing200may be seated.