Improved rivet nuts

Abstract

An apparatus for providing mating alignment between the internal threads of a rivet nut and the external threads of a mandrel not claimed for installation tooling before anchoring the rivet nut in a hole in a substrate, or after anchoring the rivet nut in the substrate hole. The improvement includes a bushing sleeve disposed in the countersunk hole of the rivet nut for guiding the external threads of the mandrel or fastener to the internal threads of the rivet nut. The sleeve also provides clearance during upsetting of the rivet nut and provides visual confirmation that the rivet nut has been properly anchored in the substrate hole.

Description

Technical Field

[0001] The present invention relates to fastener systems and apparatus. More particularly, the invention disclosed herein relates to rivet nuts and associated fasteners, which are typically used to fasten or join panels or other substrates together. More particularly, the invention disclosed herein relates to improved rivet nuts that receive a bushing / sleeve apparatus that functions to achieve proper upset of the rivet nut during installation and guide the fastener (typically a screw or bolt) into mating alignment with the rivet nut (typically its internal threads). Background Art

[0002] Citation or identification of any reference in this application shall not be construed as an admission that such reference is important as prior art to the present disclosure.The following references disclose rivet nuts and improvements thereto.

[0003] U.S. Patent No. 11,092,184 to Blaski discloses a rivet nut installation method and a rivet nut structural configuration that essentially makes the rivet nut "self-tapping." After the rivet nut is rotatably installed on an externally threaded spindle of an installation tool, the spindle is rotated with the rivet nut while the front end of the spindle, which protrudes beyond the front end of the rivet nut, contacts the outward-facing side of the workpiece at the installation position. The front end of the spindle is driven into and through the workpiece in an insertion direction while continuing to rotate the spindle until a hole is formed through the workpiece and the head of the rivet nut engages the outside of the workpiece. The spindle is retracted in the reverse direction while the head of the rivet nut is held against the outside of the workpiece to collapse the upper wall portion of the rivet nut into a radially outwardly extending bulge or bulb that bears on the opposite side of the workpiece. The head of the rivet nut and the radially outwardly extending bulb apply a compressive force against the outer and inner surfaces of the workpiece at the installation position. Figure 1 As best described in , this patent discloses a countersunk cavity that terminates in an annular flange but has no sloped / converging walls and no bushing sleeve.

[0004] U.S. Patent No. 5,403,135 to Renner discloses a rivet nut having a countersunk cavity with a side parallel to the axis of the internal threads of the lower portion of the rivet nut. The self-tapping cap screw serves as a pulling mandrel when the cap screw is attached to a setting tool. The cap screw is a self-tapping screw. Figure 1 As best described in , this patent discloses a countersunk cavity that terminates in an annular flange but has no sloped / converging walls and no bushing sleeve.

[0005] U.S. Patent No. 7,857,563 issued to Pratt discloses a blind bolt fastener having a core bolt to body mechanical lock and a sleeve to body mechanical lock. The core bolt is mechanically locked to the integrally formed fastener body and sleeve to prevent the core bolt from loosening. Figure 6 As best illustrated in , this patent does not disclose a countersunk bore cavity terminating in an annular flange, but it discloses an area similar to a countersunk opening having an entrance with an inclined / converging wall; however, neither this patent nor any of the aforementioned patents disclose an apparatus that provides for mating alignment between the internal threads of the rivet nut and the external threads of a mandrel of an unclaimed rivet nut installation tool prior to anchoring the rivet nut in a hole in a substrate and provides for mating alignment between the internal threads of the rivet nut and the external threads of an unclaimed threaded fastener after anchoring in the substrate hole.

[0006] None of the known patents disclose an alignment device comprising a bushing sleeve having a maximum outer diameter sized for snug insertion and retention in the countersunk bore of a rivet nut and having an inner diameter sized for guiding the external threads of a spindle of an installation tool (and / or the external threads of a fastener) into optimally aligned rotational fit with the internal threads of a mating chamber of a rivet nut. Summary of the Invention

[0007] The invention disclosed herein is essentially an apparatus for providing alignment between the internal threads of a rivet nut and a rivet nut installation tool or an externally threaded fastener for mating with the rivet nut. More specifically, the invention comprises:

[0008] (a) a rivet nut (10) comprising a countersunk opening and a countersunk cavity (1) leading to an internally threaded shank end (2) having an inner diameter smaller than the inner diameter of the countersunk opening, preferably the countersunk cavity having an inner diameter converging from the countersunk opening to an annular seat flange (16) terminating the countersunk cavity; and

[0009] (b) a substantially cylindrical, resilient and durable sleeve (20) configured for a snug press fit within the countersunk bore cavity, with its front end (22) adjacent the annular seat flange and having a length that causes a rear edge (23) to rest generally flush with the countersunk bore opening when the rivet nut has been properly installed, the sleeve having an inner diameter slightly larger than the outer diameter of the mounting spindle threads of the rivet nut installation tool or the externally threaded fastener for alignment with the internal threads of the shank.

[0010] Generally speaking, the invention disclosed herein comprises an improved rivet nut that includes a bushing sleeve to align the threads of an incoming screw (or installation tool) with the threads defining a mating chamber in the rivet nut. A primary improvement involves the inclusion of a suitably positioned bushing sleeve within the rear portion of the rivet nut to serve as a guide for the rotational engagement of the external threaded tip of the mandrel of the installation tool (or fastener) with the internal threads of the mating chamber of the rivet nut. The bushing sleeve also enhances control over the formation of an annular ball formed by the reverse axial pull of the rivet nut during installation, essentially squeezing or clamping the substrate between the ball and the underside of the head of the rivet nut. Increasing the number of threads in the mating chamber also enhances control over the reverse axial pull. The improved rivet nut can be used in applications where an "over-upset" installation may be encountered, which applies a greater reverse axial pull than would normally be specified for a particular application. In addition to preventing improper installation of the rivet nut and preventing cross-threading during tightening, the improved rivet nut and bushing sleeve achieve a tightening with greater strength, resulting in fewer tightening failures. It can also be designed to provide enhanced tightening after intentionally induced over-upsetting installation without causing deformation of the ball or other aspects of the rivet nut; and as a failsafe to avoid stopping the assembly line after accidental over-upsetting during installation (usually due to incorrect calibration of the installation tool), the rivet nut strength can result in the breaking of the installation tool spindle, which can be easily remedied after the part has been removed from the assembly line.

[0011] A major advantage of the disclosed invention is that the sleeve ensures perpendicular alignment between the two threads, eliminating or reducing the possibility of cross-threading and the defects caused by cross-threading.

[0012] Another major advantage is that the sleeve provides visual confirmation that the rivet nut has been properly seated within the substrate hole.

[0013] Another major advantage is that the improved rivet nut can easily provide a closed end rivet nut that is waterproof or moisture resistant.

[0014] Another advantage is that the rivet nut has improved anchoring to the substrate through the improved ball characteristics as well as the knurling and serrations.

[0015] Another advantage is that the rivet nut provides improved fastening strength through improved threads and improved contact with the substrate hole wall and the outer and inner surfaces surrounding the substrate hole.

[0016] Other advantages will become apparent from a reading of the disclosure herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The novel features believed characteristic of the disclosed subject matter will be set forth in any claims filed later. However, the disclosed subject matter itself, together with the preferred mode of use, other objects and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings.

[0018] Figure 1 is an exploded perspective view of a representative sample of the improved fastener apparatus of the present invention oriented for application to a horizontal substrate panel, including an improved rivet nut with a bushing sleeve ready for insertion therein.

[0019] Figure 2 yes Figure 1 Side view of the rivet nut and bushing sleeve; due to the external symmetry of the rivet nut and bushing sleeve, the side views of the two parts are basically the same after rotating 90 degrees and 180 degrees.

[0020] Figure 3 It is a top plan view of the rivet nut with the bushing sleeve fully inserted into the rear end of the rivet nut and seated in the countersunk cavity against the annular seat flange.

[0021] Figure 4 After the rivet nut has been inserted into the hole in the substrate panel depicted in dotted lines Figure 3 The rivet nut and the insert sleeve along Figure 3 Cross-sectional view of plane 4-4.

[0022] Figure 5 Is that after the rivet nut has been properly upset during the installation process of the rivet nut panel Figure 4 Same view.

[0023] Figure 6 yes Figure 5 Perspective view of the rivet nut and bushing sleeve.

[0024] Figure 7 The second substrate panel (depicted in dotted lines) is laminated to the first substrate panel (and the rivet nut is installed) and the tip of the screw fastener is inserted into the inner cavity of the bushing sleeve in the rear portion of the rivet nut. Figure 5 Same view.

[0025] Figure 8 After the screw fastener has been rotated into the rivet nut mating chamber Figure 7 Same view; also includes waterproof end plugs.

[0026] FIG9 is a bottom plan view of the separated upset rivet nut and bushing sleeve.

[0027] 10 is a top plan view of the upset rivet nut and bushing sleeve separated when upsetting has not caused the ball portion to extend outwardly beyond the diameter of the rivet nut's head.

[0028] Figure 11 is Figure 3 A cross-sectional view of a side view of an upset rivet nut and an inserted bushing sleeve, with the cross section taken at plane 4-4 of FIG. 1; this is an exploded view, wherein the left side depicts the upset of the rivet nut with a longer bushing sleeve for thicker panels, and wherein the right side depicts the upset of the rivet nut with a shorter bushing sleeve for thinner panels.

[0029] These drawings illustrate certain details of certain embodiments. However, the invention disclosed herein is not limited to the embodiments described herein. The invention disclosed herein may have equally effective or legally equivalent embodiments. DETAILED DESCRIPTION

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It will be further understood that the terms "comprises and / or comprising" or "includes and / or including" or "have or having" when used in this specification specify the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0031] For the sake of simplicity and to give the broadest possible interpretation and construction to the claims of this patent application, the conjunction "and" may also be deemed to include the disjunctive "or," and vice versa, where necessary to give the broadest possible interpretation and construction to the claims of this patent application. Similarly, when the plural form is used, it may be deemed to include the singular form, and vice versa.

[0032] It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Similarly, synonyms for the same element, term, or concept may only be used to distinguish one similar element from another, unless the context clearly indicates otherwise.

[0033] The disclosure herein is not limited by the materials of construction, to the extent that other materials meet the structural and / or functional requirements. For example, any material may be used for the bushing sleeve, provided it meets the placement and guidance requirements for its intended use. In one embodiment, the bushing sleeve is constructed of a glass-filled nylon material; however, any material with sufficient rigidity and durability will suffice. Likewise, the disclosed invention is not limited by any particular construction process or method.

[0034] A device or system that is configured in a certain way is configured in at least that way, but it may also be configured in other ways than those explicitly described.

[0035] The terms “comprise” (and any form of comprise, such as “comprises and comprising”), “have” (and any form of have, such as “has and having”), and “include” (and any form of include, such as “includes and including”) are open-ended linking verbs. As a result, an apparatus that “comprises,” “has,” or “includes” one or more elements possesses those one or more elements, but is not limited to possessing only those elements. Similarly, a method that “comprises,” “has,” or “includes” one or more steps possesses those one or more steps, but is not limited to possessing only those one or more steps.

[0036] Any embodiment of any disclosed apparatus, device, system and / or method may consist of or consist essentially of (rather than include / comprise / have) any of the described elements and / or features and / or steps. Thus, in any of the claims, the terms "consisting of" or "consisting essentially of" may replace any of the above-mentioned open-ended linking verbs to change the scope of a given claim relative to what would otherwise be possible when using open-ended linking verbs. Any method comprising multiple steps is not limited to (but may be limited to) the order of the steps recited in the method.

[0037] Features of one embodiment may be applied to or found in other embodiments even if not described or illustrated, unless expressly prohibited by the disclosure or the nature of the embodiment or feature.

[0038] In the context of the rear edge of the seated bushing sleeve after upsetting the rivet nut by reverse axial pulling, the term "substantially flush" means that the rear edge of the bushing sleeve is coplanar with (or slightly below) the countersunk bore opening of the rear portion of the rivet nut.

[0039] The term "fitting chamber" refers to the internal threaded portion of the insertion end of the rivet nut.

[0040] The term "mating component" means the external threads of a non-claimed spindle of a non-claimed rivet nut installation tool or the external threads of a non-claimed externally threaded fastener with which the rivet nut is intended to form a fastened joint.

[0041] The term "screw" may include a bolt or any other externally threaded fastener, and the term "bolt" may include a screw or any other internally threaded fastener.

[0042] Each pair of rivet nut performance requirements and bushing sleeve performance requirements can be sized specifically (depending on the size of the fastener or rivet nut or the substrate dimensions), or designed specifically for the performance needs of a specific application, such as, for example, fastening metal or polymer panels, glass-filled plastics, aluminum, steel, or stainless steel. All thread sizes of the improved rivet nut can be manufactured to conform to ISO fastener property classifications, particularly Grade 8.8 (mild steel), Grade 9.8 (medium carbon grade steel), Grade 10.9 (high carbon grade steel and alloys), and Grade 12.9 (high carbon stainless steel and titanium alloys). For example, the bushing sleeve length can be determined by the thickness of the substrate involved in the fastening plus the thickness of the rivet nut head, and then reduced by a small amount (approximately 1 mm) so that the visible edge of the bushing sleeve is positioned directly below the surface of the rivet nut head to indicate proper sleeve placement and when upset of the rivet nut has occurred. In addition, the matching of the rivet nut and the bushing sleeve pair can be compatible with direct and indirect (either OEM or aftermarket) use in specific industries or fields, such as automotive manufacturers and aerospace platform fastener applications, as well as electrical and other general industry fastener applications. The improved rivet nut bushing sleeve device can be designed to enable the rivet nut to better meet the fastener requirements of the specific grade of material used.

[0043] During installation, after the rivet nut (with the installed bushing sleeve) is rotationally engaged with the mandrel of the installation tool and inserted into the substrate hole, the installation tool applies a reverse axial pulling force to the rivet nut, essentially collapsing the unsleeved portion of the countersunk hole wall to form a ball on the bottom side of the substrate; this is referred to as "upsetting" the rivet nut. During this upsetting, the bushing sleeve reduces the lateral "play" between the rivet nut and the installation tool, maintaining alignment of the rivet nut to facilitate upsetting without creating undesirable tilting or other misalignment of the ball. After the rivet nut's axial pull-up, the inner diameter of the countersunk bushing sleeve provides direct alignment for mating a corresponding externally threaded fastener with the internal threads of the mating chamber of the rivet nut's inserted portion. The inner diameter of the sleeve is typically preferably about 0.0015 inches to about 0.0025 inches larger than the outer diameter of the threaded fastener, although other ranges of difference will suffice as long as the inner diameter of the sleeve is larger than the threaded fastener. The sleeve interacts with the seat flange at the bottom of the countersunk hole to force the screw to nut alignment with the threads of the mating chamber. The sleeve acts to reduce or eliminate so-called cross-threading, which is essentially a misalignment of the threads that prevents or destroys proper fastening. The sleeve greatly enhances the goal of providing a rivet nut that consistently results in a fastening without defects after initial installation, achieving the fastener industry goal of having zero defective parts per million. The sleeve greatly enhances the anti-cross-threading advantages experienced when using screws or bolts with forged ends, dog points, or projectile points.

[0044] These rivet nut improvements have synergistically high utility for automotive and aircraft components. For example, the bushing sleeve can be quickly press-fitted into the inner diameter of the rivet nut countersunk hole, with much greater speed and accuracy verified by visual confirmation that the anchored rivet nut's sleeve is essentially flush with the rivet nut's top surface, verifying proper axial pull during rivet nut (upsetting) installation. The bushing-improved rivet nut with the bushing sleeve also provides a more stable ridged fastening joint when properly "upset" (installed) in the substrate hole. The improvements also provide resistance to vibration failure.

[0045] The deeper countersink design (particularly with the countersink wall angle and bushing sleeve) creates a larger annular ball during upset (installation), increasing fastener anchor strength and stability. The countersink wall length has been increased to provide increased surface area for creating the crimp that compresses the annular ball of the substrate between the underside of the head (with serrations) and the upper side of the ball (with knurls), as well as increased surface area for contact between the sidewalls of the substrate hole and adjacent knurls. The improved design has particular utility with substrate materials including plastic (preferably, but not necessarily, glass-filled), PVC with 33% glass, nylon with glass fillers, and various grades of aluminum, steel, and titanium.

[0046] The length of the bushing sleeve and its countersink can be specific to the substrate material and its thickness. The preferred length of the bushing sleeve and its countersink depends primarily on the needs of the fastened joint (such required strength) and the composition of the substrate material. For example, if a strong fastening is required in a location expected to experience a lot of vibration, the substrate material must be able to withstand a lot of compression during installation of the rivet nut and after tightening, the rivet nut must have sufficient hardness to withstand such compression and tightening, and the fastener (screw or bolt) must be able to withstand the amount of torque required to achieve an optimal tightening.

[0047] In many typical fastening applications, the length of the bushing sleeve is the thickness of the substrate plus the thickness of the head of the rivet nut, so that appropriate axial pull upset causes the visible edge of the sleeve to appear flush with (or just below) the rear end of the rivet nut. However, for intentional over-upset installations where a more secure grip is desired for the applicable substrate, the bushing sleeve length can be reduced by a relatively short distance (typically about an additional 1 mm) to ensure a higher rivet nut substrate surface upset clamping load. In addition, for some fastening joint applications involving softer plastic substrate materials, it may be necessary to reduce rather than increase the surface clamping load. In this case, the length of the bushing sleeve will be increased to the desired rivet nut upset length required by the substrate material used. The bushing sleeve in these cases will prevent undesirable over-upset.

[0048] The amount of threads in the mating chamber that defines the insert portion of the rivet nut has been increased from the minimum required by the Industrial Fastener Association standard to all various threaded fastener sizes (both metric and imperial). The mating chamber of the improved rivet nut contains an additional four (4) to six (6) threads per inch. The additional threads increase thread strength and reduce thread deformation and thread strip-out when high driving torque is applied. The axial pulling tool can even be set to an over-upset pull strength without causing thread deformation / damage to the rivet nut. (For example, when the application requires a very strong grip of the substrate, a sleeve with a shorter depth can be used to allow the installation tool to provide a longer return axial pull during installation / upsetting, resulting in a rivet nut with a wider ball and a more secure compression / grip of the substrate with the underside of the head.) The additional thread strength ensures a secure, properly set fastened joint without the problems of thread strip-out and thread distortion / deformation, especially when using a bushing sleeve, even when installed in an over-upset condition. In a thread strength test where a grade 10.9 screw is mated to a properly installed grade 10.9 rivet nut (with a bushing sleeve of appropriate length) and a torque suitable for grade 12.9 material is applied (a so-called over-torque condition), the head of the screw will break (separate from the threaded shank) without twisting and / or loosening in the substrate of the rivet nut fastened joint.

[0049] Another improvement is the intersection between the serrated underside of the rivet nut head and the knurling on the outer wall of the rivet nut countersunk hole. This intersection area will be referred to as the under-head joint. The length of the knurling ending at the under-head joint will typically (and preferably) not exceed the thickness of the substrate. The knurling is optimized to provide increased contact with the hole wall as the rivet nut is upset by reverse axial pulling. The knurling also helps smooth any sharp edges and burrs in the substrate hole and reshape any out-of-round holes. During upset, the knurling and under-head joint essentially rework the substrate mounting hole. The under-head joint also provides a press or interference fit into the approximately 0.003-inch to approximately 0.006-inch substrate hole. Most importantly, the under-head joint provides a mechanical lock and completely and securely fills the substrate hole with the rivet nut, more securely clamping the substrate between the serrations under the rivet nut head and the knurling within the hole, with the knurling contacting the inner surface of the substrate surrounding the hole. Current conventional rivet nut products in the industry do not completely fill the substrate hole or correct the other aforementioned deficiencies. This is because the typical rivet nut substrate mounting hole is larger than the outer diameter of the rivet nut. Due to the interaction of the angled design of the lower engaging portion of the head, the hole edge strength is increased by approximately 30%. The tensile strength is increased by approximately 48%, and the riveted hole interface area is increased by approximately 26%. The angled press fit of the lower head into the substrate hole also prevents the penetration of most fluids. Completely and securely filling the substrate hole also eliminates fatigue failure loads in the fastened joint. This improvement provides a press fit or interference fit that stabilizes the interface between the substrate hole and the anchoring rivet nut and provides a mechanically locked joint.

[0050] The design of the rivet nut at the bottom of the threaded insert end allows for a plug (epoxy or steel plug) to be locked into the end when required or desired for waterproof or moisture proof applications.

[0051] These and other aspects of the disclosed subject matter, as well as additional novel features, will be apparent from the description provided herein. This summary is not intended to be a comprehensive description of the subject matter, but rather to provide a brief overview of some of the subject matter's functionality. Other systems, methods, features, and advantages provided herein will become apparent to those skilled in the art upon review of the accompanying drawings and detailed description. All such additional systems, methods, features, and advantages included in this description are intended to be within the scope of any claims now or later filed.

[0052] In one general embodiment, the invention disclosed herein comprises an apparatus for providing a mating alignment between the internal threads of a rivet nut and the external threads of a mandrel of an unclaimed rivet nut installation tool before anchoring the rivet nut in a hole in a substrate. Alternatively, the invention comprises an apparatus for providing a mating alignment between the internal threads of a rivet nut and the external threads of an unclaimed threaded fastener after anchoring the rivet nut in a hole in a substrate. The apparatus comprises:

[0053] (a) A rivet nut (1) comprising an insert portion having an outer diameter sized for close insertion into a substrate hole (with the outer wall contacting or in close proximity to the substrate) and having an inner diameter with internal threads (17) defining a substantially cylindrical mating chamber (18); and a rear portion comprising a rear end defining a substantially circular opening having a circumference defined by an inner wall (14) defining a substantially cylindrical cavity leading to the mating chamber, the mating chamber having an inner diameter smaller than the inner diameter of the opening and the cavity; and

[0054] (b) a bushing sleeve (20) having a maximum outer diameter sized for snug insertion and retention in the cavity and having an inner diameter sized to guide the external threads of the spindle of the installation tool or the external threads of the fastener into optimally aligned rotational engagement with the internal threads of the mating chamber.

[0055] The inner diameter of the internally threaded insert of the rivet nut is typically defined by the ridges of the threads (17), forming the boundary of the mating chamber.

[0056] The inner diameter defined by the inner wall (21) of the sleeve is generally equal to or greater than the diameter of the internal threads defining the mating chamber of the insert portion. The sleeve may have an inner diameter ranging from about 0.0015 inches to about 0.0025 inches greater than the diameter of the internal threads defining the mating chamber.

[0057] The sleeve may further include a first end having an annular bevel (25) that reduces the outer diameter of the end to less than the maximum outer diameter of the sleeve and facilitates snug insertion into the cavity. The sleeve may further include a first annular band section (26) adjacent the first end bevel and having an outer diameter that is larger than the outer diameter of the first end bevel but smaller than the maximum outer diameter of the sleeve and facilitates snug insertion of the sleeve into the cavity. The sleeve may further include a second end having an annular bevel that reduces the outer diameter of the end to less than the maximum outer diameter of the sleeve and enables the first end or the second end to facilitate snug insertion into the cavity. The sleeve may further include a second annular band section beveled adjacent the second end and having an outer diameter that is larger than the outer diameter of the second end beveled but smaller than the maximum outer diameter of the sleeve and enables the first end or the second end to facilitate snug insertion into the cavity.

[0058] In a preferred embodiment, the cavity comprises a countersunk cavity (1) terminating in an annular seat flange (16); and the sleeve comprises a hollow cylindrical body having a seat end and a rear end and configured to fit snugly within the countersunk cavity, wherein the seat end is adjacent the annular seat flange. The sleeve preferably has an inner diameter slightly larger than the inner diameter of the annular seat flange; the combination and coordination of the two inner diameters preferably should function to substantially provide optimal mating alignment of the thread tips of the mating component with the threads of the mating chamber. The sleeve inner diameter preferably has an inner diameter that provides just enough leeway for an incoming mating component to align with the mating chamber.

[0059] The inner wall defining the countersunk cavity may have an inner diameter that converges from the opening to the annular seat flange. The convergence may be continuous from the head opening of the cavity to the seat flange. Alternatively, the countersunk wall may be substantially parallel from the head opening to a point before reaching the seat flange, where it continuously converges to the seat flange or begins to converge gradually before continuing to converge onto the seat flange. The convergence substantially provides a snug fit for the bushing sleeve in the countersunk cavity and facilitates reverse axial pulling of the rivet nut to achieve proper upset (ball formation).

[0060] If the rivet nut has been properly installed, the sleeve should be of such length that its rear edge is substantially flush with (or slightly below) the surface of the countersunk cavity opening. This will provide a visual check for proper installation of the rivet nut.

[0061] The annular flange may have a surface that is inclined toward the internal threads defining the mating chamber. This can facilitate alignment of the threaded end of an incoming fastener (or installation tool spindle) with the mating threads of the mating chamber. Preferably, the annular flange has a surface that is inclined at an angle within a range of about 20 degrees to about 40 degrees. More preferably, the angle is within a range of about 25 degrees to about 35 degrees. More preferably, the angle is about 30 degrees. The thread size and characteristics generally determine the ideal angle.

[0062] The insert portion will typically include an open end ("open" at the insert end). However, for applications where waterproofing or moisture resistance is required or desired, the device may further include a member to close the open end selected from the group consisting of a water-tight adhesive and other substances that durably block the insert portion, as well as mixtures and combinations thereof. Rivet nuts may have a water-tight adhesive such as polyamide, 2-part epoxy, and a specially formulated adhesive that blocks its normally open insert end.

[0063] The rear portion of the rivet nut may further include an outer surface opposite the countersunk cavity, which includes knurling (15) parallel to the longitudinal axis of the countersunk cavity for contacting the edge of the substrate hole to resist rotation of the rivet nut anchored in the substrate hole. In order to anchor the rivet nut to the substrate hole and the substrate, the rivet nut insert portion is engaged with an installation tool before the rivet nut is anchored in the substrate hole. The installation tool applies reverse axial pull to the insert portion, and such anchoring is caused by the collapse of the rear portion including the knurling, resulting in the formation of an annular ball portion (19) protruding from the body of the rivet nut (excluding the head), and the substrate is pressed between the head (11) and the ball portion. In addition to the anti-rotation contact between the knurling of the ball portion and the underside of the substrate, the knurling should have a length and number that also optimizes the anti-rotation contact between the knurling and the side wall of the substrate hole.

[0064] The rear end of the rivet nut of the rear portion may further include an annular head flange (11) that surrounds the opening and prevents the rivet nut from passing through the substrate hole. It may further include radial serrations (13) on the underside of the head for contacting the outer edge of the substrate, defining a hole for resisting rotation of the rivet nut anchored in the substrate hole.

[0065] The serrations (13) on the underside of the head of the rivet nut provide better surface contact on the outside of the substrate. This works in conjunction with the parallel knurling on the outer surface of the rear portion of the rivet nut to reduce the direct torque-to-turn-out rotation of the rivet nut within the substrate hole. The serrations and knurling will counteract (offset) the screw group drive torque sequence. These features enable the improved rivet nut's torque-to-turn drive torque value to exceed the DC power tool drive torque parameters set for the mating screw thread size and grade and fastener for secure fastening joints. Under the fastener joint load and material grade (8.8 to 10.9) of the screw or bolt thread size, the rivet nut's ability to exceed the threaded screw or bolt thread size drive torque-to-turn value and prevent the rivet nut from loosening in the substrate. The screw or bolt will self-destruct and fail before the rivet nut loosens in the substrate. The shank knurling and the underside serrations on the head provide additional surface contact. In addition, the length and number and orientation (radial and parallel) of the improved serrations and knurling resist the formation of stress risers on the substrate surface area.

[0066] One specific embodiment of an apparatus provides mating alignment between the internal threads of a rivet nut and the external threads of a mandrel of an unclaimed rivet nut installation tool before anchoring the rivet nut in a hole in a substrate (or provides mating alignment between the internal threads of the rivet nut and the external threads of an unclaimed threaded fastener after anchoring in a hole in a substrate), the apparatus comprising:

[0067] (a) a rivet nut comprising an insert portion having an outer diameter sized for close insertion into the substrate hole and having an inner diameter with internal threads defining a substantially cylindrical mating chamber, and a rear portion comprising a rear end having a substantially circular opening, the substantially circular opening having a circumference defined by an inner wall defining a substantially cylindrical countersunk cavity having an inner diameter converging from the countersunk cavity opening to an annular seat flange terminating the countersunk cavity and leading to the mating chamber, the mating chamber having an inner diameter smaller than the inner diameters of the opening and the countersunk cavity; and

[0068] (b) a hollow cylindrical bushing sleeve including a rear edge and a seat end for snugly seating in the countersunk cavity, wherein the seat end is adjacent the annular seat flange, the sleeve having a maximum outer diameter sized for snugly retaining in the countersunk cavity and having an inner diameter slightly larger than the inner diameter of the threads defining the mating chamber to guide the external threads of the spindle of the installation tool or the external threads of the fastener to optimally align and rotate with the internal threads of the mating chamber, the sleeve also having a length such that its rear edge can be substantially flush with the countersunk cavity opening when the rivet nut has been properly installed.

[0069] The insert portion of the rivet nut may further include an end opening defined by a front edge (12). For applications where waterproofing or moisture resistance is required or desired, the device may further include a member for closing the end opening selected from the group consisting of a water-impermeable adhesive and a substance that durably blocks the insert portion, as well as mixtures and combinations thereof. For example, the water-impermeable adhesive may be a polyamide or a two-part epoxy resin, and a specially formulated sealant.

[0070] As with the previously described embodiments, the seat end may further include an annular bevel (25) that reduces the outer diameter of the seat end to less than the maximum outer diameter of the sleeve and facilitates snug insertion into the countersunk cavity. The sleeve may further include a first annular band section (26) adjacent to the seat end bevel and having an outer diameter that is larger than the outer diameter of the seat end bevel but smaller than the maximum outer diameter of the sleeve and facilitates snug insertion and retention of the sleeve in the countersunk cavity. The rear end may further include an annular bevel (25) that reduces the outer diameter of the rear end to less than the maximum outer diameter of the sleeve and enables the seat end or rear end to facilitate snug insertion into the countersunk cavity. The sleeve may further include a second annular band section (26) adjacent to the rear end bevel (25) and having an outer diameter that is larger than the outer diameter of the rear end bevel but smaller than the maximum outer diameter of the sleeve and enables the seat end or rear end to facilitate snug insertion and retention in the countersunk cavity.

[0071] The rear portion of the rivet nut may further include an outer surface opposite the countersunk cavity, including knurling parallel to the longitudinal axis of the countersunk cavity for contacting the edge of the substrate hole to resist rotation of the rivet nut anchored in the substrate hole. When the rivet nut insert portion is engaged with an installation tool before anchoring the rivet nut in the substrate hole, the installation tool applies reverse axial pull to the insert portion, causing the rear portion including the knurling to collapse, resulting in the formation of a protruding annular ball portion, which presses the substrate between the head portion and the ball portion, thereby causing such anchoring. In addition to the anti-rotation contact between the knurling and the ball portion, the length and number of the knurls also optimize the anti-rotation contact between the knurling and the sidewall of the substrate hole.

[0072] The rear end of the rivet nut of the rear portion may further include an annular head flange that surrounds the opening and prevents the rivet nut from passing through the substrate hole. In addition, on the underside of the head, there may be radial serrations (13) for contacting the outer edge of the substrate, defining a hole for resisting rotation of the rivet nut anchored in the substrate hole.

[0073] The seat flange (16) has an outer diameter defined by the bottom of the countersunk cavity wall (14) and an inner diameter defined by the free edge of the flange. In another embodiment, the seat flange has an inner diameter defined by the inner diameter of the uppermost edge of the threads. In another embodiment, the free edge of the seat flange may open to the start of the threads.

[0074] In addition to the apparatus described herein, the invention disclosed herein also includes a method for anchoring a rivet nut to a substrate. One specific embodiment includes a method comprising the following steps:

[0075] (a) Place the bushing sleeve in the cavity of the rear portion of the rivet nut;

[0076] (b) partially threading the rivet nut onto the installation tool, substantially rotatably engaging the external threads of the installation tool (commonly referred to as a mandrel) with the internal threads of the mating chamber of the insert portion of the rivet nut;

[0077] (c) inserting a tool-engaged rivet nut into a hole in a substrate (e.g., a panel) until the head of the rivet nut contacts the outer surface of the substrate;

[0078] (d) triggering the installation tool to complete the rotational engagement of the rivet nut and the mandrel;

[0079] (e) triggering the installation to apply a reverse pull to "upset" the rivet nut by collapsing the knurled wall portion until the wall crimps and forms an annular ball that protrudes from the rivet nut by approximately the same amount as the head of the rivet nut, and compressing the substrate between the underside of the head and the upper side of the ball; and

[0080] (f) Triggering reverse rotation of the mandrel to release the installation tool from the rivet nut anchored in the substrate.

[0081] The method may further include the following steps: After the complete axial pulling tool sequence as set forth in the previous paragraph has been completed, the operator operating the axial pulling tool can verify the proper joint integrity upset of the fastened joint. The bushing sleeve after upset will be slightly below the surface of the head (or flush with the surface of the head). If the bushing sleeve is visually observed to have traveled only a short distance, for example, leaving a gap between the top of the rivet nut head and approximately one-third (1 / 3) below the exposed countersunk hole, and the bushing sleeve is visually observed to be not in the proper axial pulling upset position after upset, then this determines an out-of-control condition and a weak fastened joint. The bushing sleeve not being in its designated position after upset indicates to the operator using the axial pulling tool that the operator needs to correct the out-of-control tolerance fastened joint condition.

[0082] The method of using an anchored rivet nut may include the following steps:

[0083] (a) inserting the tip of the externally threaded fastener into the inner cavity of a bushing sleeve, said bushing sleeve being positioned within the cavity of the rear portion of the rivet nut; and

[0084] (b) applying a pressure sufficient to allow the sleeve to substantially deliver the tip into rotational mating contact with the threads defining the mating chamber while rotating the fastener in a tightening direction.

[0085] The method may further include the step of: the rivet nut bushing sleeve serving as a positional guide for the male threaded fastener to engage the rivet nut threads for proper thread-to-thread alignment as the threads are rotated to engage. The bushing sleeve is an alignment device that reduces cross-threading conditions when using mating threaded screws and rotating the threaded screws with a screw-driving tool before the threads engage the threads of the rivet nut.

[0086] Although the present disclosure and its advantages have been described in detail, it will be understood that various changes, substitutions and modifications may be made herein without departing from the spirit and scope of the design defined by the appended claims. The scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, components, methods and / or steps described in the specification. As will be readily understood by those skilled in the art from this disclosure, processes, machines, manufactures, compositions of matter, components, methods or steps that currently exist or are to be developed later for performing functions substantially the same as those described herein or achieving substantially the same results may be utilized according to this disclosure. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, components, methods or steps within their scope. The scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, components, methods and steps described in the specification.

[0087] Although preferred embodiments of the present invention have been described, it will be appreciated that various changes, adaptations, and modifications may be made therein without departing from the spirit of the invention. Changes may be made in detail, particularly in shape, size, material, and arrangement of parts, without departing from the scope of the invention.

[0088] Although the forms of apparatus described herein constitute preferred embodiments of the invention, it will be understood that the invention is not limited to these precise forms of apparatus and that changes may be made therein without departing from the scope and spirit of the invention as defined in the appended claims.

[0089] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein and the claims that follow.

Claims

1. An apparatus for providing mating alignment between the internal threads of a rivet nut and the external threads of a mandrel of a rivet nut setting tool before anchoring the rivet nut in a hole in a substrate having a thickness, or for providing mating alignment between the internal threads of the rivet nut and the external threads of a threaded fastener after anchoring the rivet nut in the hole in the substrate, the mandrel of the rivet nut setting tool and the threaded fastener being collectively referred to as mating components, the apparatus comprising: (a) a rivet nut comprising an insert portion having an outer diameter sized for close insertion into the substrate hole and having an inner diameter with internal threads defining a substantially cylindrical mating chamber, and a rear portion comprising a rear end having a substantially circular opening, the substantially circular opening having a circumference defined by an inner wall defining a substantially cylindrical cavity spanning at least the thickness of the substrate and leading to the mating chamber, the mating chamber having an inner diameter smaller than the inner diameter of the opening and the cavity; and (b) a bushing sleeve having a maximum outer diameter sized for snug insertion and retention within the cavity and having an inner diameter sized to guide the external threads of the mating component into aligned rotational engagement with the internal threads of the mating chamber, in: The cavity comprises a countersunk cavity terminating in an annular seat flange; and The sleeve includes a hollow cylindrical body having a seat end and a rear end having a rear edge, the sleeve being configured to fit snugly within the countersunk cavity, wherein the seat end is adjacent the annular seat flange. 2 . The apparatus of claim 1 , wherein the inner diameter of the sleeve is greater than a diameter of the internal threads defining the mating chamber of the insert portion.

3. The apparatus of claim 1, wherein the inner diameter of the sleeve is between 0.0015 inches and 0.0025 inches greater than the outer diameter of the mating component.

4. The apparatus of claim 1, the sleeve further comprising a first end having an annular bevel that reduces an outer diameter of the first end to less than the maximum outer diameter of the sleeve and facilitates snug insertion into the cavity.

5. The apparatus of claim 4, the sleeve further comprising a first annular band section adjacent the bevel of the first end and having an outer diameter that is larger than the outer diameter of the bevel of the first end but smaller than the maximum outer diameter of the sleeve and facilitates snug insertion of the sleeve into the cavity.

6. The apparatus of claim 5, wherein the sleeve further comprises a second end having an annular bevel, the annular bevel of the second end reducing an outer diameter of the second end to be smaller than the maximum outer diameter of the sleeve and enabling the first end or the second end to facilitate snug insertion into the cavity.

7. The apparatus of claim 6 , wherein the sleeve further comprises a second annular band segment adjacent the bevel of the second end and having an outer diameter that is larger than an outer diameter of the bevel of the second end but smaller than the maximum outer diameter of the sleeve, and enabling the first end or the second end to facilitate snug insertion into the cavity.

8. The apparatus of claim 1, said sleeve having an inner diameter slightly larger than an inner diameter of said annular seat flange.

9. The apparatus of claim 1, said sleeve having an inner diameter and said annular seat flange having an inner diameter that provides sufficient clearance to guide said external threads of said mating component into aligned rotational engagement with said internal threads of said mating chamber.

10. The apparatus of claim 1, the inner wall defining the counterbore cavity having an inner diameter converging from the opening to the annular seat flange.

11. The apparatus of claim 1 , said sleeve having a length such that its rear edge can be positioned within said countersunk cavity to provide visual confirmation that said rivet nut has been properly installed.

12. The apparatus of claim 1, the annular seat flange defining a surface that slopes toward the internal threads of the mating chamber.

13. The apparatus of claim 12, wherein the surface defined by the annular seat flange is inclined at an angle between 20 degrees and 40 degrees.

14. The apparatus of claim 13, the annular seat flange defining a surface inclined at an angle of 30 degrees.

15. The device of claim 1 , wherein the insertion portion further comprises an end opening, the device further comprising a member for closing the end opening selected from the group consisting of: a water-impermeable adhesive, other substances that durably block the insertion portion, a mixture of the two, and a combination of the two.

16. The apparatus of claim 1 , wherein the rear portion of the rivet nut further comprises an outer surface opposite the countersunk cavity, the outer surface including knurling parallel to the longitudinal axis of the countersunk cavity for contacting an edge of the substrate hole to resist rotation of the rivet nut anchored in the substrate hole, wherein, while engaging the inserted portion of the rivet nut with the installation tool before anchoring the rivet nut in the substrate hole, the installation tool applies reverse axial pull to the inserted portion, causing the rear portion including the knurling to collapse, resulting in the formation of a protruding annular ball portion, the annular ball portion presses the substrate between the head and the knurling of the ball portion, thereby causing such anchoring.

17. The apparatus of claim 16, wherein the knurls on the ball portion further have a length and number that optimizes anti-rotational contact between the knurls and the sidewalls of the substrate hole.

18. The apparatus of claim 1 , the rear end of the rear portion of the rivet nut further comprising an annular head flange surrounding the opening and preventing the rivet nut from passing through the substrate hole, and further comprising angled and radial serrations on the underside of the annular head flange for contacting an outer edge of the substrate, the outer edge of the substrate defining a hole for resisting rotation of the rivet nut anchored in the substrate hole.

19. An apparatus for providing mating alignment between the internal threads of a rivet nut and the external threads of a mandrel of a rivet nut setting tool before anchoring the rivet nut in a hole in a substrate or providing mating alignment between the internal threads of the rivet nut and the external threads of a threaded fastener after anchoring the rivet nut in the hole in the substrate, the mandrel of the rivet nut setting tool and the threaded fastener being collectively referred to as mating components, the apparatus comprising: (a) a rivet nut comprising an insert portion having an outer diameter sized for close insertion into the substrate hole and having an inner diameter with internal threads defining a substantially cylindrical mating chamber, and a rear portion comprising a rear end having a substantially circular opening, the substantially circular opening having a circumference defined by an inner wall defining a substantially cylindrical countersunk cavity, the substantially cylindrical countersunk cavity having an inner diameter converging from the opening of the countersunk cavity to an annular seat flange at which the countersunk cavity terminates, the substantially cylindrical countersunk cavity leading to the mating chamber, the mating chamber having an inner diameter smaller than the inner diameters of the opening and the countersunk cavity; (b) a hollow cylindrical bushing sleeve including a rear end having a rear edge and a seat end for snugly seating within the countersunk cavity, wherein the seat end is adjacent the annular seat flange, the sleeve having a maximum outer diameter sized for snugly retaining within the countersunk cavity and having an inner diameter slightly larger than the threads defining the mating chamber to guide the external threads of the spindle of the installation tool or the external threads of the fastener into aligned rotational engagement with the internal threads of the mating chamber, the sleeve also having a length such that its rear edge is substantially flush with the opening of the countersunk cavity to provide visual confirmation that the rivet nut has been properly installed.

20. The apparatus of claim 19, the inner diameter of the sleeve being between 0.0015 inches and 0.0025 inches greater than the outer diameter of the mating component.

21. The apparatus of claim 19, said sleeve having an inner diameter slightly larger than an inner diameter of said annular seat flange.

22. The apparatus of claim 19, said sleeve having an inner diameter and said annular seat flange having an inner diameter that provides sufficient clearance to guide said external threads of said mating component into aligned rotational engagement with said internal threads of said mating chamber.

23. The apparatus of claim 19, the annular seat flange defining a surface that slopes toward the internal threads of the mating chamber.

24. The apparatus of claim 23, wherein the surface defined by the annular seat flange is inclined at an angle between 20 degrees and 40 degrees.

25. The apparatus of claim 19, the insertion portion further comprising an end opening, the apparatus further comprising a member for closing the end opening selected from the group consisting of: a water-impermeable adhesive, a substance that durably blocks the insertion portion, a mixture thereof, and a combination thereof.

26. The apparatus of claim 19, the seat end further comprising an annular ramp that reduces an outer diameter of the seat end to less than the maximum outer diameter of the sleeve and facilitates snug insertion into the countersunk cavity.

27. The apparatus of claim 26, wherein the sleeve further comprises a first annular band section adjacent to the bevel of the seat end and having an outer diameter that is larger than the outer diameter of the bevel of the seat end but smaller than the maximum outer diameter of the sleeve, and facilitates snug insertion and retention of the sleeve in the countersunk hole cavity.

28. The apparatus of claim 19 , wherein the rear portion of the rivet nut further comprises an outer surface opposite the countersunk cavity, the outer surface including knurling parallel to the longitudinal axis of the countersunk cavity for contacting an edge of the substrate hole to resist rotation of the rivet nut anchored in the substrate hole, wherein, while engaging the inserted portion of the rivet nut with the installation tool before anchoring the rivet nut in the substrate hole, the installation tool applies reverse axial pull to the inserted portion, causing the rear portion including the knurling to collapse, resulting in the formation of a protruding annular ball portion, the annular ball portion presses the substrate between the head and the knurling of the ball portion, thereby causing such anchoring.

29. The apparatus of claim 19, the rear end of the rear portion of the rivet nut further comprising an annular head flange surrounding the opening and preventing the rivet nut from passing through the substrate hole, and further comprising angled and radial serrations on the underside of the annular head flange for contacting an outer edge of the substrate, the outer edge of the substrate defining a hole for resisting rotation of the rivet nut anchored in the substrate hole.

Images