Systems and methods for improving bolted joints

A mechanical fastener assembly is provided for joining two or more workpieces. The assembly includes a mechanical fastener and a slotted insert. The mechanical fastener has a shaft received within aligned bores of the workpieces. The slotted insert surrounds at least a portion of the shaft and has a body portion received within the aligned bores, while an enlarged head portion of the slotted insert is positioned outside of the bores. The mechanical fastener assembly may further include a retaining sleeve when the bores of the workpieces have different diameters. In such case, a midsection of the retaining sleeve is at least partially received within the bore having the smaller diameter, while an enlarged end section of the retaining sleeve is at least partially received within the bore having the greater diameter. The retaining sleeve may be used in combination with or independently of the slotted insert.

FIELD OF THE DISCLOSURE

The present subject matter relates to bolted joints. More particularly, the present subject matter relates to methods and systems for strengthening bolted joints.

DESCRIPTION OF RELATED ART

It is well known to secure two or more components of an assembly together using mechanical fasteners. Among the typical mechanical fasteners used, which depend upon a number of factors, are bolts and rivets. Each type of mechanical fastener has strengths and weaknesses. Compared to a rivet, a bolt is typically much easier to service, as it is typically readily inserted and removed as required, whereas rivets are typically not intended to be removed and serviced. In contrast, a riveted joint is typically stronger than a bolted joint, as a bolt merely creates friction between the joined components to secure the joint, whereas a rivet creates a stronger shear joint. As such, a relatively great number of bolts and/or relatively heavy bolts must be employed to create a joint that is comparable to a joint secured with fewer and/or lighter rivets.

As both bolts and rivets have their disadvantages, it would be advantageous to be able to provide a mechanical fastener capable of creating a joint with serviceability comparable to a bolt and strength comparable to a rivet.

SUMMARY

In one aspect, a mechanical fastener assembly is provided for securing first and second workpieces having aligned bores. The mechanical fastener assembly includes a mechanical fastener and a slotted insert. The mechanical fastener has a shaft configured to be at least partially received within the aligned bores of the first and second workpieces. The slotted insert surrounds at least a portion of the shaft of the mechanical fastener and has a body portion and an enlarged head portion. The body portion is configured to be at least partially received within the aligned bores of the first and second workpieces, while the head portion is configured to be positioned outside of the bores. An inner surface of the slotted insert is configured to engage at least a portion of the shaft of the mechanical fastener and an outer surface of the body portion of the slotted insert is configured to engage at least a portion of the aligned bores of the first and second workpieces.

In another aspect, a joint comprises first and second workpieces, a mechanical fastener, and a slotted insert. The first workpiece has a first bore and the second workpiece has a second bore aligned with the first bore. The mechanical fastener has a shaft at least partially received within the aligned bores of the first and second workpieces. The slotted insert surrounds at least a portion of the shaft of the mechanical fastener and has a body portion and an enlarged head portion. The body portion is at least partially received within the aligned bores of the first and second workpieces, while the head portion is positioned outside of the bores. An inner surface of the slotted insert engages at least a portion of the shaft of the mechanical fastener and an outer surface of the body portion of the slotted insert engages at least a portion of the aligned bores of the first and second workpieces.

In yet another aspect, a retaining sleeve is provided for securing first and second workpieces having aligned bores with different diameters. The retaining sleeve includes a generally tubular midsection and an enlarged end section. The midsection defines an axially extending gap and is configured to be at least partially received within the bore having the smaller diameter. The end section has a greater diameter than the midsection and is configured to be at least partially received within the bore having the greater diameter.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The embodiments disclosed herein are for the purpose of providing the required description of the present subject matter. They are only exemplary, and may be embodied in various forms and in various combinations. Therefore, specific details disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims.

FIGS. 1-3show a first workpiece10and a second workpiece12that are joined by a mechanical fastener assembly14according to an aspect of the present disclosure.FIGS. 4-9show an exemplary method of joining the workpieces10and12using the mechanical fastener assembly14. In the illustrated embodiment, the first workpiece10comprises a vehicle axle and the second workpiece12comprises an axle wrap or suspension system component, but mechanical fastener assemblies according to the present disclosure may be employed to join together any of a variety of suitable workpieces. Thus, it should be understood that the workpieces described and illustrated herein are merely exemplary, and that the assemblies and methods described herein may be used in combination with other workpieces without departing from the scope of the present disclosure.

Each workpiece10and12is provided with a bore or through-hole or aperture for receipt of at least a portion of the mechanical fastener assembly14, as can be seen inFIGS. 4-9. In the illustrated embodiment, the workpieces10and12are joined together at multiple locations, such that each workpiece10,12includes a plurality of bores, with multiple mechanical fastener assemblies14being employed; however, it is also within the scope of the present disclosure for each workpiece to include only one bore or through-hole or aperture and to join the workpieces using a single mechanical fastener assembly.

More particularly, in the illustrated embodiment, the axle or first workpiece10includes a pair of generally parallel vertical walls16aand16b, with each vertical wall16a,16bincluding a bore18a,18bthat is substantially aligned with the bore of the other wall. As best seen inFIG. 16, each vertical wall16a,16bmay include a plurality of bores, with each bore being substantially aligned with a bore defined in the other vertical wall. As shown inFIGS. 2-9, each pair of bores may include a rigid brace20extending between the vertical walls16aand16bfor preventing deformation of the vertical walls16aand16bwhen a force is applied thereto by a mechanical fastener assembly14during the joinder process, as will be described in greater detail herein.

Similar to the first workpiece10, the axle wrap or second workpiece12also includes a pair of generally parallel vertical walls22aand22b, with each vertical wall22a,22bincluding a bore24a,24bthat is substantially aligned with the bore of the other wall. Further, each vertical wall22a,22bmay include a plurality of bores, with each bore being substantially aligned with a bore defined in the other vertical wall.

Prior to joinder, each vertical wall of the first workpiece10is positioned adjacent to and/or in contact with an associated vertical wall of the second workpiece12, with each bore of the first workpiece10being positioned directly adjacent to and in alignment with a bore of the second workpiece12. More particularly, bores18aand24aare positioned directly adjacent to and in alignment with each other, while bores18band24bare positioned directly adjacent to and in alignment with each other (FIGS. 4-9). In the illustrated embodiment, these four bores18a,18b,24a, and24bare positioned in alignment with each other, although not necessarily directly adjacent to each other.

With the first and second workpieces10and12properly aligned, one or more components of the mechanical fastener assembly14may be inserted into the bores. According to one method of joining the first and second workpieces10and12, a slotted collar26a,26bof the mechanical fastener assembly14is partially inserted into each pair of adjacent, aligned bores. One of the slotted collars26ais shown in greater detail inFIGS. 10-13, but it should be understood that the other slotted collar26bmay be substantially identical. In other embodiments, two slotted collars of a single mechanical fastener assembly may be differently configured or, if there is only one set of adjacent, aligned bores, a mechanical fastener assembly may include only one slotted collar.

As shown in greater detail inFIGS. 10-12, the slotted collar26amay be generally annular, with a slot28defined in the wall of the slotted collar26ato prevent the slotted collar26afrom defining a complete 360° ring. The illustrated slot28is substantially parallel to a central axis of the slotted collar26aand extends between the ends30and32of the slotted collar26a, but it is also within the scope of the present disclosure for the slot to be oriented at an angle with respect to the central axis of the slotted collar. In other embodiments, the slot may extend only part of the way between the ends of the slotted collar and/or have a varying width, rather than the substantially uniform width shown in the illustrated embodiment. It is also within the scope of the present disclosure for the slot to be relatively narrow or thin, as in the illustrated embodiment, or to be relatively wide, thereby limiting the arcuate extent of the wall of the slotted collar.

In the illustrated embodiment, the inner surface34of the slotted collar26ahas a substantially uniform diameter, while the outer surface36of the slotted collar26ahas a non-uniform diameter. In particular, the outer surface36of the illustrated slotted collar26ais tapered to define a generally frusto-conical surface with a greater diameter at one end32than at the other end30. The end30of the slotted collar26ahaving the smaller outer diameter is referred to herein as the “lead-in end,” as it is the end of the slotted collar that is preferably first inserted into the aligned bores of the workpieces, as will be described in greater detail herein.

In one embodiment, the outer surface36is tapered at approximately 1.5° with respect to the central axis of the slotted collar26a, such that the outer surface36has a maximum diameter at one end32that gradually decreases in the direction of the other end30. In other embodiments, the outer surface of the slotted collar may be tapered at a different angle or at a varying angle. It is also within the scope of the present disclosure for the outer surface of the slotted collar to be substantially un-tapered and to have a substantially uniform diameter or to have a diameter that varies without being tapered (e.g., having a stepped outer surface).

According to an aspect of the present disclosure that may be employed in combination with or separately from the above-described taper, one end30may include a chamfer38. If provided in combination with a tapered outer surface36(as in the illustrated embodiment), it is preferable for chamfer38to be associated with the lead-in end30for improved performance when the slotted collar26ais inserted into aligned bores, as will be described in greater detail herein. In other embodiments, where the diameter of the outer surface of the slotted collar is substantially uniform except in the location of the chamfer, it may be advantageous for the chamfered end to be inserted first into the aligned bore, as a chamfer provides the slotted collar with a self-alignment feature during insertion.

Turning back now toFIG. 4, the slotted collars26aand28bare at least partially inserted into the aligned bores, preferably with the lead-in end30first. If the outer surface of a slotted collar is tapered, it is preferable for at least a portion of the associated aligned bores to also be tapered. Most preferably, the associated set of aligned bores have a taper that matches the tapered outer surface of the slotted collar (e.g., with the aligned bores defining an approximately 1.5° taper when the outer surface of the slotted collar is tapered at approximately 1.5°). On the other hand, if the outer surface of a slotted collar is un-tapered, it is preferable for the associated aligned bores to also be un-tapered or to have a substantially uniform diameter. Preferably, at least a portion of the outer surface of the slotted collars26aand26bhas a greater diameter than the associated set of aligned bores (for reasons that will be described in greater detail herein), in which case a tapered slotted collar and set of aligned bores may be preferred to an un-tapered slotted collar and aligned bores to the extent that it may be easier to partially insert a tapered slotted collar into a tapered set of aligned bores.

With the slotted collars26aand26bin place, other components of the mechanical fastener assembly14may be inserted into the aligned bores. In particular, the shaft or shank or elongated body40of a mechanical fastener42may be at least partially inserted into the aligned bores, as shown inFIG. 5. In the illustrated embodiment, the mechanical fastener42comprises a bolt, with a shaft40having an enlarged head or end piece44associated with one of its ends according to conventional design, but other mechanical fasteners having a shaft or shank or elongated body (e.g., a screw or tube) may also be used without departing from the scope of the present disclosure. The shaft40has a smaller outer diameter than the minimum inner diameter of the associated set of aligned bores, and may have a smaller outer diameter than the minimum inner diameter of the associated slotted collar or collars26a,26b, such that at least a portion of the shaft40is surrounded by or received within the collar(s). In such a configuration (as illustrated inFIG. 5), there is a gap between the outer surface of the shaft40and the aligned bores, with the slotted collar or collars26a,26boccupying at least a portion of that gap. Although the shaft40of the mechanical fastener42is shown as being inserted into the aligned bores after the slotted collars26aand26b, it is also within the scope of the present disclosure for the shaft to be inserted prior to or substantially at the same time as a slotted collar is inserted into a set of aligned bores.

With the shaft40of the mechanical fastener42at least partially inserted into the aligned bores, one or both of the slotted collars26a,26bmay be further advanced into the associated set of aligned bores. If the outer surface of a slotted collar is tapered and/or includes a chamfered end, such a configuration may provide a self-centering or aligning feature as the slotted collar is further advanced into the adjacent, aligned bores. In the illustrated embodiment, the mechanical fastener assembly14is provided with a pair of rigid plates46aand46b, with one rigid plate46apositioned adjacent to one of the slotted collars26aand the other rigid plate46bpositioned adjacent to the other slotted collar26bto contact the associated slotted collar and press it further into the associated set of aligned bores. Each rigid plate46a,46bincludes a bore or through-hole or aperture48(FIG. 4) configured to receive the shaft40of the associated mechanical fastener42. If multiple mechanical fasteners are provided (as in the illustrated embodiment), each rigid plate46a,46bmay include one bore or through-hole or aperture for each mechanical fastener. Preferably, the bore48of the rigid plate or plates46aand46bhave a diameter substantially the same as or slightly greater than the outer diameter of the shaft40of the associated mechanical fastener42, such that the shaft40may pass through the bore48of rigid plate or plates46aand46b, but the associated slotted collar26a,26bcannot. In other embodiments, the rigid plate or plates may be differently configured (e.g., substantially annular rigid members or washers50, as inFIG. 16) or the mechanical fastener assembly may be provided without a rigid plate. It may be preferable, however to provide a washer50or rigid plate46a,46bor the like in order to provide a substantially smooth contact surface for the end32of the slotted collar or collars26aand26band/or to distribute any force applied to the workpieces10and/or12by the mechanical fastener42over a larger area.

If the mechanical fastener42is provided as a bolt, as in the illustrated embodiment, a second enlarged end piece or nut52may be provided for connection to the end of the bolt opposite the bolt head44. As shown inFIGS. 6-8, the nut52contacts one of the rigid plates46ato move it along the shaft40and into contact with one of the slotted collars26a, while the bolt head44contacts the other rigid plate46bto move it into contact with the other slotted collar26b. In the illustrated embodiment, tightening the nut52(FIGS. 7 and 8) brings the bolt head44and the nut52closer together, thereby pressing the rigid plates46aand46bagainst the slotted collars26aand26b, respectively, which are advanced further into the associated set of aligned bores until the rigid plates46aand46bcontact the associated vertical walls22aand22bof the second workpiece12(FIG. 9). If provided, the brace20positioned between the vertical walls16aand16bof the first workpiece10helps to prevent deformation of the vertical walls16a,16b,22a, and22bwhen the nut52is tightened onto the mechanical fastener42. While the slotted collars26aand26bare fully received within the associated aligned bores in the final configuration ofFIG. 9, it is also within the scope of the present disclosure for a slotted collar to be only partially received within a set of aligned bores in a final configuration.

At least a portion of the outer surface of the slotted collar or collars26aand26bhas a greater diameter than the associated set of aligned bores, such that fully pressing each slotted collar into its associated set of aligned bores causes the slot of the slotted collar to at least partially close, thereby decreasing the outer and inner diameters of the slotted collar. The slot28, therefore, gives the slotted collar26a,26bimproved flexibility to be usable in a variety of different applications, as the slot28effectively adjusts to a variety of tolerances between the bores and the shaft40of the mechanical fastener42, as well as any other surfaces in the bores.

Preferably, the slotted collar or collars26aand26bare configured such that the associated set of aligned bores presses the slotted collar26a,26binto contact with the shaft40of the mechanical fastener42, thereby placing at least a portion of the inner surface34of the slotted collar26a,26binto contact or engagement with the shaft40of the mechanical fastener42and placing at least a portion of the outer surface36of the slotted collar26a,26binto contact or engagement with the associated aligned bores. By contacting both the shaft40of the mechanical fastener42and the aligned bores, the slotted collar or collars26aand26bcreate a shear joint to secure the workpieces10and12together, effectively transforming a bolted joint into a riveted joint. Employing a shear joint instead of a bolted joint allows for a sufficiently strong connection between the workpieces10and12using fewer and lighter mechanical fasteners than would be necessary in a bolted joint connecting the workpieces10and12. Preferably, all or a large percentage of the inner surface34of the slotted collar or collars26aand26bcontacts the shaft40, while all or a large percentage of the outer surface36of the slotted collar or collars26aand26bcontacts the aligned bores to create a stronger shear joint.

Preferably, the slotted collar or collars26aand26bare configured to elastically deform to the final configuration ofFIG. 9, rather than inelastically or permanently deforming. By such a configuration, the mechanical fastener assembly14may be used to create a shear joint (as described above), while still being fully removable from the workpieces10and12for servicing. In one embodiment, the slotted collar or collars26aand26bare formed of a metal material, such as steel (e.g., 1008-1050 steel in a preferred embodiment), but other materials may also be used without departing from the scope of the present disclosure.

Once the shear joint has been formed, additional structures (e.g., a spacer54and a leaf spring56, in the illustrated embodiment) may be connected to the workpieces10and12, as shown inFIGS. 14 and 15. Alternatively, one or more of the additional structures may be connected to one or both of the workpieces10and12prior to joining the workpieces10and12.

As referenced above,FIG. 16illustrates an alternative embodiment of a mechanical fastener assembly14′ that may be used to join the two workpieces10and12. The mechanical fastener assembly14′ ofFIG. 16is substantially identical to the embodiment ofFIGS. 1-9, except that the rigid plates46aand46bare replaced by washers50. Other such variations to the mechanical fastener assembly (e.g., using a screw or tube instead of a bolt as the mechanical fastener) may also be employed without departing from the scope of the present disclosure.

It should again be emphasized that the embodiments of mechanical fastener assemblies and workpieces ofFIGS. 1-16are merely exemplary. The illustrated embodiments employ multiple mechanical fastener assemblies, with the shaft of each mechanical fastener assembly passing through multiple sets of adjacent, aligned bores and each mechanical fastener assembly including multiple slotted collars (one for each set of adjacent, aligned bores). In other embodiments, more or fewer mechanical fastener assemblies may be employed, with the shaft of each passing through more or fewer than two sets of adjacent, aligned bores and with each mechanical fastener assembly having more or fewer than two slotted collars. For example,FIGS. 17-21show a relatively simple embodiment of the present disclosure, in which a shear joint between two workpieces is formed using a mechanical fastener and a single slotted collar.

In the embodiment ofFIGS. 17-21, a first workpiece100comprises a bottom cap of a vehicle suspension system and a second workpiece102comprises a D-pin bushing secured to the bottom cap100at two locations by two substantially identical, separate mechanical fastener assemblies104. As best seen inFIGS. 19-21, each mechanical fastener assembly104comprises a mechanical fastener106having a shaft108configured to be at least partially received within a single set of adjacent, aligned bores110and112of the workpieces100and102. The mechanical fastener assembly104also includes a slotted collar114of the type described in greater detail above, which is also at least partially received within the adjacent, aligned bores110and112of the workpieces100and102to form a shear joint between the workpieces100and102. Similar to the mechanical fastener42described above, the mechanical fastener106ofFIGS. 17-21includes an enlarged head or end piece116, with a separate second enlarged end piece or nut118that may be secured to an opposite end of the shaft108by mating threads or the like. In contrast to the embodiments ofFIGS. 1-16, it is the second enlarged end piece118that bears against the trailing end of the slotted collar114to seat it within the aligned bores110and112of the workpieces100and102as the second enlarged end piece118is advanced onto the shaft108of the mechanical fastener106, but the slotted collar114operates otherwise as described above to provide a shear joint connection. The mechanical fastener assembly106ofFIGS. 17-21may include additional components (e.g., a rigid plate/washer of the type described above in connection with the embodiments ofFIGS. 1-16), but any such additional components are merely optional. Further, it is also within the scope of the present disclosure for the two mechanical fastener assemblies104illustrated inFIGS. 17-21to be differently configured, rather than being identical.

FIGS. 22-26illustrate another example of two workpieces200and202connected by one or more mechanical fastener assemblies204that provide a shear joint connection. In the embodiment ofFIGS. 22-26, the first workpiece200comprises a frame hanger of a vehicle suspension system and the second workpiece202comprises a vehicle frame to which the frame hanger200is secured at multiple locations by a plurality of substantially identical, separate mechanical fastener assemblies204. As best seen inFIGS. 24-26, each mechanical fastener assembly204comprises a mechanical fastener206having a shaft208configured to be at least partially received within a single set of adjacent, aligned bores210and212of the workpieces200and202. The mechanical fastener assembly204also includes a slotted collar214of the type described in greater detail above, which is also at least partially received within the adjacent, aligned bores210and212of the workpieces200and202to form a shear joint between the workpieces200and202. Similar to the mechanical fastener42described above, the mechanical fastener206ofFIGS. 22-26includes an enlarged head or end piece216, with a separate second enlarged end piece or nut218that may be secured to an opposite end of the shaft208by mating threads or the like. Similar to the embodiment ofFIGS. 17-21, it is the second enlarged end piece218that bears against the trailing end of the slotted collar214to seat it within the aligned bores210and212of the workpieces200and212as the second enlarged end piece218is advanced onto the shaft208of the mechanical fastener206to provide a shear joint connection. The mechanical fastener assembly204ofFIGS. 22-26may include additional components (e.g., a rigid plate/washer of the type described above in connection with the embodiments ofFIGS. 1-16), but any such additional components are merely optional. Further, it is also within the scope of the present disclosure for the mechanical fastener assemblies204illustrated inFIGS. 22-26to be differently configured, rather than being identical.

FIGS. 27-31illustrate yet another example of two workpieces300and302connected by one or more mechanical fastener assemblies that provide a shear joint connection. In the embodiment ofFIGS. 27-31, the first workpiece300comprises a steering knuckle and the second workpiece302comprises a brake component, both of a vehicle steering and braking system, which are secured together at multiple locations by a plurality of separate, differently configured mechanical fastener assemblies304and306. As best seen inFIGS. 29-31, each mechanical fastener assembly304,306comprises a mechanical fastener308,310having a shaft312,314configured to be at least partially received within a single set of adjacent, aligned bores316and318of the workpieces300and302. Each mechanical fastener assembly304,306also includes a slotted collar320of the type described in greater detail above, which is also at least partially received within the adjacent, aligned bores316and318of the workpieces300and302to form a shear joint between the workpieces300and302. Similar to the mechanical fastener42described above, the lower mechanical fastener308ofFIGS. 27-31includes an enlarged head or end piece322, with a separate second enlarged end piece or nut324that may be secured to an opposite end of the shaft312by mating threads or the like. As in the embodiments ofFIGS. 1-16, the first enlarged end piece322bears against the trailing end of the slotted collar322to seat it within the aligned bores316and318of the workpieces300and302as the second enlarged end piece324is advanced onto the shaft312of the mechanical fastener308to provide a shear joint connection.

As for the upper mechanical fastener assembly306, its mechanical fastener310includes a first enlarged end piece326integrally formed with the shaft314and configured to contact the trailing end of the slotted collar320to seat it within the aligned bores316and318, but there is no second enlarged end piece provided. Instead, at least a portion of the bore of one or both of the workpieces (illustrated as a portion328of the bore316of the first workpiece300) is configured to engage and retain the shaft314as the shaft314is advanced into the aligned bores316and318. In a preferred embodiment, the outer surface of the shaft314includes threads that are mated with threads defined in one or both of the bores316and318of the workpieces300and302to retain the shaft314as it is rotatably advanced into the bores316and318to seat the slotted collar320and provide a shear joint connection. If the second enlarged end piece324of the lower mechanical fastener assembly304is configured to be secured to the associated shaft312by mating threads, the mechanical fasteners308and310of the lower and upper mechanical fastener assemblies304and306may be identical; otherwise, it is also within the scope of the present disclosure for the mechanical fasteners308and310to be differently configured. Other means of securing the shaft314of the upper mechanical fastener assembly306within the bores316and318may also be provided without departing from the scope of the present disclosure. The mechanical fastener assemblies304and306ofFIGS. 27-31may include additional components (e.g., a rigid plate/washer of the type described above in connection with the embodiments ofFIGS. 1-16), but any such additional components are merely optional.

FIGS. 32-34illustrate a pair of substantially identical mechanical fastener assemblies400having a differently configured slotted component. More particularly, each illustrated mechanical fastener assembly400includes two slotted inserts or plugs402, although it should be understood that a single slotted insert may be used instead of two slotted inserts. It is also within the scope of the present disclosure for a mechanical fastener assembly to include both a slotted insert and a slotted collar of the type described above.

The slotted inserts402perform a function similar to the function performed by the slotted collars described above, but have a different configuration. The slotted inserts402ofFIGS. 32-34include a body portion404and a head portion406(FIGS. 35 and 36). Preferably, the slotted inserts402are integrally formed components, with the body portion404and head portion406provided as sections of a single-piece component, but it is also within the scope of the present disclosure for the body portion404and the head portion406to be separately provided and then secured together.

The illustrated body portion404is shaped similarly to the slotted collars described above, being sized to be at least partially received within the aligned bores of first and second workpieces, such as the axle10and suspension system component12ofFIG. 1. As shown in greater detail inFIGS. 35 and 36, the body portions404of the slotted inserts402may be generally tubular or annular, with at least one slot408defined in the wall of the body portion404. As best shown inFIG. 36, the body portion404may include a plurality of slots, such as a pair of slots408diametrically opposed to each other, which may be substantially identical to each other (as illustrated) or differently configured.

The illustrated slots408are substantially parallel to a central axis of the slotted insert402, but it is also within the scope of the present disclosure for the slots to be oriented at an angle with respect to the central axis of the associated slotted insert. As best shown inFIG. 36, the illustrated slots408begin at a free or lead-in end410of the body portion404(i.e., the end of the body portion404that is spaced away from the head portion406) and extend along only a portion of the length of the body portion404, rather than extending along the entire length of the body portion404or the slotted insert402. The slotted section of the body portion404will typically be more flexible (i.e., more capable of being moved toward and away from the central axis of the slotted insert402) than the section of the body portion404that does not include the slots408. Thus, the flexibility profile of the body portion404may be varied by varying the length of the slots408. The flexibility of the slotted section may be varied by varying any of a number of factors, such as the number of slots, the location of the slots, and the angular extent or width of the slots. Other slot configurations (e.g., slots having a varying or non-uniform width, rather than a substantially uniform width) may also be employed without departing from the scope of the present disclosure.

FIGS. 37-41illustrate two examples of slotted inserts412and414having differently configured slots. In the illustrated embodiments, eight slots are evenly spaced around the perimeter of the body portion416of the slotted inserts412and414, with each slot beginning at the lead-in end418of the body portion416. Seven of the slots420(“minor slots”) are substantially identical, while the eighth slot422(“major slot”) is differently configured. In the illustrated embodiments, the seven minor slots420extend along a minor portion of the length of the body portion416(e.g., only approximately 25% of the length of the body portion416), while the major slot422has a length approximately three times greater than the length of the other slots420and extends along the majority of the length of the body portion416(e.g., approximately 75% of the length of the body portion416), as best shown inFIGS. 38-39 and 41. Compared to the slotted inserts402ofFIGS. 35 and 36, the slotted inserts412and414ofFIGS. 37-41tend to have a more flexible body portion due to the increased number of slots and the addition of the major slot422, which may be advantageous for creating a shear joint to join two workpieces together.

Similar to the above-described slotted collars, the inner surface424of the body portion404(FIG. 36) may have a substantially uniform diameter, while the outer surface426may have a non-uniform diameter. For example, the outer surface426of the body portion404may be tapered to define a generally frusto-conical surface with a greater diameter at one end than at the other end. If the body portion404is so configured, it may be preferable for the lead-in end410to have a smaller outer diameter than the opposite end of the body portion404(i.e., the end directly adjacent to the head portion406). As in the above-described slotted collars, the lead-in end410of the body portion404of the slotted insert402may include a chamfer428, which may be employed in combination with or separately from the above-described taper.FIGS. 34A and 34Bshow a body portion404with an exaggerated taper to better illustrate a slotted insert402with a body portion404having a tapered outer surface.FIGS. 34A and 34Billustrate the combination of a body portion with a tapered outer surface and workpieces with aligned bores in which at least a portion of the associated aligned bores is also tapered, as described above.

In addition or instead of having a taper and/or a chamfer, the outer surface of the body portion of a slotted insert may include other features or formations. For example, the outer surface of the body portions416of the slotted inserts412and414shown inFIGS. 37-41are provided with a textured or knurled section430. In the illustrated embodiments, the knurled section430defines a continuous ring around the head portion416of the slotted insert412,414adjacent to the head portion432, but other configurations and orientations may also be employed without departing from the scope of the present disclosure. While this feature is not illustrated in the drawings of the other slotted collars and inserts described herein, it should be understood that they may also include one or more textured or knurled sections or surfaces, which may provide any of a number of advantages and functions, such as modifying the flexibility of the slotted collar/insert and/or providing an improved fit with one or more of the bores of the associated workpieces.

As for the head portion406of the slotted insert402, it has a larger diameter than the associated body portion404. The head portion406is intended to be positioned outside of the aligned bores of the first and second workpieces10and12during use, so it may be advantageous for it to have a larger diameter than the bores. In the embodiment ofFIGS. 32-36, the head portion406is generally annular, without being circular. Instead, the perimeter of the head portion406includes a flat section434that provides an anti-rotation feature, as will be described in greater detail below. In other embodiments, the head portion may have a substantially circular shape (seeFIG. 37-41) or a different non-circular shape (e.g., a shape configured to be engaged by a wrench or another tool, such as a hexagonal shape).

In addition to the slotted inserts402, the mechanical fastener assemblies400illustrated inFIGS. 32-34may each include a mechanical fastener42and pair of rigid plates46a,46bof the type shown inFIGS. 1-9, although it is also within the scope of the present disclosure for a slotted insert to be used in a differently configured mechanical fastener assembly. It will be seen that the mechanical fastener assembly400ofFIGS. 32-34omits a nut secured to the threaded portion of the mechanical fastener42, as the nut is effectively replaced by one of the slotted inserts402, as will be described in greater detail herein.

To assemble the mechanical fastener assembly400(thereby securing the first and second workpieces10and12together), the bores18a,18band24a,24bof the first and second workpieces10and12are aligned (FIG. 34). The rigid plates46aand46bare placed against the workpieces10and12, with the bores48of the plates46aand46bin alignment with the bores18a,18band24a,24bof the workpieces10and12. The body portions404of the slotted inserts402are then pressed through the bores48of the plates46aand46b, and into the bores18a,18band24a,24bof the workpieces10and12. If two mechanical fastener assemblies400are to be used to secure the workpieces10and12, it may be advantageous for the head portions406of the slotted inserts402to be configured such that the flat sections434of the head portions406of two adjacent slotted inserts402are substantially flush with each other, as best shown inFIG. 33. By such a configuration, the head portions406cooperate to prevent each other from rotating within the aligned bores.

With the slotted inserts402in place, the shaft40of the mechanical fastener42may be at least partially inserted into the aligned bores, passing through the central bores or openings of the slotted inserts402, such that at least a portion of the shaft40is surrounded by or received within the slotted inserts402(FIG. 34). The shaft40has a smaller diameter than the bores18a,18band24a,24bof the workpieces10and12, such that there is a gap between the outer surface of the shaft40and the aligned bores, with the slotted inserts402occupying at least a portion of that gap.

With the shaft40of the mechanical fastener42at least partially inserted into the aligned bores, the slotted inserts402may be further advanced into the associated set of aligned bores. Preferably, at least a portion of the outer surface of the body portion404of the slotted inserts402has a greater diameter than the associated set of aligned bores, such that fully pressing each slotted insert into its associated set of aligned bores causes the slot or slots of the slotted insert to at least partially close, thereby decreasing the outer and inner diameters of the slotted section of the body portion404. Preferably, the slotted inserts402are configured such that the workpiece bores press the body portions404into contact with the shaft40of the mechanical fastener42, thereby placing at least a portion of the inner surfaces424of the body portions404into contact or engagement with the shaft40of the mechanical fastener42and placing at least a portion of the outer surface426of the body portions404into contact or engagement with the associated aligned bores. By contacting both the shaft40of the mechanical fastener42and the aligned bores, the body portions404of the slotted inserts402create shear joints to secure the workpieces10and12together, effectively transforming a bolted joint into a riveted joint.

Preferably, the slotted inserts402are configured to elastically deform to the final configuration ofFIG. 34, rather than inelastically or permanently deforming. By such a configuration, the mechanical fastener assembly400may be used to create a shear joint (as described above), while still being fully removable from the workpieces10and12for servicing. In one embodiment, the slotted inserts402may be formed of a metal material, such as steel, but other materials may also be used without departing from the scope of the present disclosure.

If the mechanical fastener42is provided as a bolt having an enlarged head or end piece44and a threaded section spaced from the enlarged head44, the slotted inserts may be advanced into the bores18a,18band24a,24bby mating engagement between one of the slotted inserts and the threaded section of the mechanical fastener shaft40. For example,FIGS. 37-41illustrate two slotted inserts412and414having differently configured inner surfaces. The slotted insert412ofFIGS. 37-39(which may be referred to as the “first insert” or the “proximal insert”) has a relative smooth and/or featureless inner surface436, whereas the inner surface438of the slotted insert414ofFIGS. 40 and 41(which may be referred to as the “second insert” or the “distal insert”) includes a threaded section440, with the threads of the second insert414being configured to mate with the threads of the threaded section of the associated mechanical fastener of the mechanical fastener assembly. The illustrated threaded section440is present in both the body portion416and head portion432of the distal insert414, but it is also within the scope of the present disclosure for the threaded section to be present in only the body portion416or only the head portion432.

To install a mechanical fastener assembly having slotted inserts412and414as illustrated inFIGS. 37-41, the body portions416of the first and second slotted inserts412and414may be at least partially inserted aligned bores of first and second workpieces. The mechanical fastener may then be inserted into the bores, with the enlarged head of the mechanical fastener positioned adjacent to the proximal insert412and the threaded section of the mechanical fastener positioned adjacent to the distal insert414. When the mechanical fastener has been inserted sufficiently so as to place the threaded sections into contact with each other, the mechanical fastener and/or the distal insert414may be rotated to cause the threads of the threaded sections to mate with each other, which effectively advances the mechanical fastener and the slotted inserts412and414further into the aligned bores of the workpieces. Preferably, the slotted inserts412and414are advanced into the aligned bores until their head portions432contact one of the workpieces (or any other physical obstacle, such as a plate of the mechanical fastener assembly, if provided). It should be understood that this is only one manner of securing the mechanical fastener and slotted insert(s) of a mechanical fastener assembly, and other means may be provided for maintaining the components of the mechanical fastener assembly in place, including a threaded bolt, as described above. Additionally, it should be understood that the first and second inserts412and414may be used either in combination with each other or separately.

According to another aspect of the present disclosure a mechanical fastener assembly or joint may include a retaining sleeve.FIGS. 42-44illustrate an exemplary retaining sleeve500, whileFIGS. 45 and 46illustrate the retaining sleeve500in partially formed states. While the retaining sleeve500will be described herein in the context of a mechanical fastener assembly that is suitable for effectively transforming a bolted joint into a riveted joint, thereby creating a shear joint, it should be understood that retaining sleeves according to the present disclosure may be practiced independently. For example, retaining sleeves according to the present disclosure may be particularly useful in joining workpieces having differently sized aligned bores, regardless of whether the resulting joint is a bolted joint or a shear joint or a riveted joint.

In the illustrated embodiment, the retaining sleeve500includes a generally tubular midsection502and an enlarged end section504. Depending on the configuration of the workpieces to be joined, it may be advantageous for the retaining sleeve500to have two enlarged end sections504separated by the midsection502, as shown inFIGS. 42 and 43. In the illustrated embodiment, the end sections504are substantially identical, but it is within the scope of the present disclosure for the end sections of a retaining sleeve to be differently configured.

In one embodiment, the retaining sleeve500is formed from a generally flat or planar piece of material506(FIG. 44) that is processed into a tubular configuration (FIG. 45). In the tubular configuration, the facing edges508of the material506may be spaced from each other to define an axially extending gap510, rather than being in contact to form a complete tube. In other embodiments, the retaining sleeve500may be initially provided as a tube, with the gap510being later defined, such as by a cutting operation or the like. In yet other embodiments, the retaining sleeve may be substantially tubular, without an axially extending gap. If a gap510is provided between the facing edges508, the retaining sleeve500will have a measure of flexibility, which may vary according to any of a number of factors (e.g., the thickness of the material506and the material composition of the retaining sleeve500). In one embodiment, the retaining sleeve500is made of a metallic material, such as steel, but it is within the scope of the present disclosure for the material composition of the retaining sleeve500to vary without departing from the scope of the present disclosure.

Each end section504has a greater outer diameter than the midsection502, although the particular dimensions of the midsection502and the end sections504may vary depending on the nature of the workpieces to be joined. In the illustrated embodiment, the opposing edges512of the material506are processed (e.g., by a cutting operation or the like) to form with a plurality of deformable projections or teeth or fingers514. In other embodiments, the deformable projections or teeth or fingers514may be separately provided and secured or associated to the midsection502, rather than being integrally formed with the midsection502.FIGS. 42 and 43show the projections514as being outwardly bent or disposed (i.e., directed away from the central axis of the retaining sleeve500), but they may initially have substantially the same outer diameter as the midsection502(as shownFIG. 45) or a smaller outer diameter before being outwardly deformed to define a greater diameter than that of the midsection502. In the illustrated embodiment, the projections514are substantially identical and rectangular, but it is also within the scope of the present disclosure for the projections to be non-identical and/or differently shaped (i.e., non-rectangular).

FIG. 47illustrates a pair of retaining sleeves500received within bores of a first workpiece or vehicle axle10of the type described above and illustrated inFIGS. 1-9. As inFIGS. 1-9, a brace or bracket20is provided within the interior of the first workpiece10, extending between the vertical walls16aand16bfor preventing deformation of the first workpiece10when force is applied thereto in joining it with a second workpiece12(FIG. 50). Each brace20defines a bore516into which a retaining sleeve500may be inserted, preferably with the projections514in the unexpanded or non-deformed configuration ofFIG. 46, rather than the expanded or deformed configuration ofFIGS. 42-45. If the outer diameter of the retaining sleeve500is greater than the diameter of the bore516, then the diameter of the retaining sleeve500may be temporarily decreased (on account of the flexibility provided by the gap510) to allow the retaining sleeve500to be slid through the bore516.

Each retaining sleeve500is advanced through the bore516of the associated brace20until the projections514are positioned at least partially outside of the two ends of the bore516. In this position, the projections514are at least partially received within the bores18a,18bof the first workpiece10, which have a greater diameter than the bore516of the brace20. The projections514are then deformed outwardly to come into contact with the bores18a,18bof the first workpiece10(FIG. 47). The projections514in their final expanded configuration serve to hold the first workpiece10in place with respect to the brace20, with the bore516of the brace20in alignment with the bores18a,18bof the first workpiece10.

Preferably, the projections514are each deformed to the same extent, which may improve the alignment between the bore516of the brace20and the bores18a,18bof the first workpiece10. This may be achieved by any of a number of methods and using any of a number of tools. In one embodiment, a generally annular expansion or deformation device or tool600(FIGS. 48 and 49) may be used to move the projections514from the unexpanded or non-deformed configuration ofFIG. 46to the deformed or expanded configuration ofFIGS. 42-44. One end of the deformation device600includes a contoured shoulder602having a varying outer diameter. The diameter of the shoulder602preferably varies from a minimum which is smaller than the inner diameter of the retaining sleeve500in the vicinity of the projections514to a maximum diameter that is greater than the inner diameter of the retaining sleeve500in the vicinity of the projections514. Preferably, the maximum diameters of the shoulder602and the deformation device600are no greater than the diameter of the bores18a,18bof the first workpiece10, to allow the deformation device600to be advanced into the bores18a,18bto contact the unexpanded or non-deformed projections514. Pressing the shoulder602of the deformation device600against the projections514causes the projections514to deform outwardly until the projections514come into contact with the associated bore18a,18bof the first workpiece10or until the projections514reach the maximum deformation as defined by the maximum diameter of the shoulder602.

With the retaining sleeve500in place and the projections514in their expanded or deformed configuration, additional components of a mechanical fastener assembly may be provided. For example,FIG. 50shows a second workpiece12of the type described above and illustrated inFIGS. 1-9, with a retaining sleeve500spanning the bores of the brace20and the first workpiece10and a slotted insert402spanning the bores of the first and second workpieces10and12. As illustrated, both the slotted insert402and the projections514of the retaining sleeve500are partially received within the bore18aof the first workpiece10. It may be preferable for the slotted insert402and the projections514to be spaced from each other, otherwise the presence of the projections514could prevent the slotted insert402from pressing against the bore18aof the first workpiece10. Other components of a mechanical fastener assembly (e.g., a mechanical fastener) may also be installed to join the workpieces. Additionally, in other embodiments, the slotted insert402may be replaced with a slotted collar, or the retaining sleeve500may be used in combination with a mechanical fastener assembly omitting a slotted collar or insert.

It will be understood that the embodiments described above are illustrative of some of the applications of the principles of the present subject matter. Numerous modifications may be made by those skilled in the art without departing from the spirit and scope of the claimed subject matter, including those combinations of features that are individually disclosed or claimed herein. For these reasons, the scope hereof is not limited to the above description but is as set forth in the following claims, and it is understood that claims may be directed to a mechanical fastener assembly alone, a mechanical fastener assembly in combination with multiple workpieces to define a joint, individual components of a mechanical fastener assembly, and/or a method of joining multiple workpieces.