Rivet nuts

Abstract

This device provides a fitting alignment between the internal thread of a rivet nut and the external thread of a mandrel of an installation tool before fixing the rivet nut into a hole in the base material, or the external thread of a threaded fastener after fixing it into a hole in the base material. This improvement includes a bushing sleeve that seats within the counterbore of the rivet nut and guides the external thread of the mandrel or fastener into the internal thread of the rivet nut. The sleeve also reduces lateral play during the setting of the rivet nut and provides visual confirmation that the rivet nut is properly secured in the hole in the base material.

Description

Technical Field

[0001] The present invention relates to fastening systems and devices. More particularly, the invention disclosed herein relates to rivet nuts and related fasteners that are frequently used to fasten or join panels or other substrates. Even more particularly, the invention disclosed herein includes an improved rivet nut that allows for proper installation during attachment of the rivet nut and serves a function of guiding a fastener (typically a screw or bolt) to a mating position with the rivet nut (typically its internal thread), accepting a bushing / sleeve device.

Background Art

[0002] No citation or identification of any reference in this application should be construed as an admission that such reference is important as prior art to this disclosure. The following references disclose rivet nuts and their improvements.

[0003] U.S. Patent No. 11,092,184, patented by Blaski, discloses a method for mounting a rivet nut and a structural configuration of the rivet nut that makes the rivet nut substantially "self-tapping". After the rivet nut is rotatably mounted on a threaded mandrel of a mounting tool, the mandrel rotates with the rivet nut, and the tip of the mandrel protruding from the tip of the rivet nut contacts the outer surface of the workpiece at the mounting position. The tip of the mandrel is driven to penetrate and through the workpiece in the insertion direction, while the mandrel continues to rotate until a hole is formed through the workpiece and the head of the rivet nut engages with the outer surface of the workpiece. The mandrel is retracted in the reverse direction while the head of the rivet nut is held against the outer surface of the workpiece, crushing the upper wall portion of the rivet nut into a radially outward-extending bulge or spherical portion that abuts against the opposite side of the workpiece. The head of the rivet nut and the spherical portion extending radially outward exert compressive force on the inner and outer surfaces of the workpiece at the mounting position. As best shown in Figure 1, this patent discloses a counterbore cavity terminating in an annular step, but does not disclose inclined / converging walls and bushing sleeves.

[0004] U.S. Patent No. 5,403,135, patented by Renner, discloses a rivet nut having a counterbore cavity with a side parallel to the axis of the internal thread at the bottom of the rivet nut. The self-tapping cap screw acts as a pull-out mandrel when the cap screw is connected to a setting tool. The cap screw is a self-tapping screw. As best shown in Figure 1, this patent discloses a counterbore cavity terminating in an annular step, but does not disclose inclined / converging walls and bushing sleeves.

[0005] U.S. Patent No. 7,857,563, patented by Pratt, discloses a blind bolt fastener having a mechanical lock between a core bolt and a body and a mechanical lock between a sleeve and a body. The core bolt is mechanically locked to the integrally formed fastener body and sleeve to prevent the core bolt from loosening. As best shown in Figure 6, this patent does not disclose a counterbore cavity terminating in an annular step, but it does disclose a region similar to a counterbore opening with an entrance having an inclined / converging wall. However, neither this patent nor any of the aforementioned patents discloses a device for providing mating alignment between the internal thread of a rivet nut and the external thread of a mounting tool mandrel before the rivet nut is fixed into a hole in the base material, nor a device for providing mating alignment with the external thread of a threaded fastener after it has been fixed into a hole in the base material.

[0006] None of the known patents disclose a aligning device comprising a bushing sleeve having a dimensioned maximum outer diameter for press-fitting and holding a rivet nut into a counterbore cavity, and a dimensioned inner diameter for guiding the external threads of the mounting tool's mandrel (and / or the fastener's external threads) into an optimally aligned rotational fit with the internal threads of the rivet nut's mating chamber. [Overview of the Initiative]

[0007] The present invention, as disclosed herein, is essentially a device for aligning the internal thread (female thread) of a rivet nut with a rivet nut mounting tool or a fastener with an external thread (male thread) that engages with a rivet nut. More specifically, the present invention is: (a) A rivet nut (10) that includes a counterbore opening and a counterbore cavity (1) and leads to an internally threaded shank end (2) having an inner diameter smaller than the counterbore opening, preferably the counterbore cavity having an inner diameter that converges from the counterbore opening to an annular counterbore step (16) that terminates the counterbore cavity, (b) A rivet nut comprising (including) a substantially cylindrical, elastic, and durable sleeve (20) configured such that its tip (22) is press-fitted into a counterbore cavity adjacent to an annular counterbore step, having a length such that its rear end (23) lies substantially coplanar with the counterbore opening when the rivet nut is properly mounted, and having an inner diameter slightly larger than the threads of the mounting mandrel of the rivet nut mounting tool or the outer diameter of the externally threaded fastener, thereby enabling alignment with the internal threads of the shank. [Problems that the invention aims to solve]

[0008] Existing rivet nuts are prone to cross-threading when fasteners rotate and engage with the rivet nut, leading to fastening failures. Furthermore, it is difficult to detect whether proper "bulbing" of the rivet nut has been achieved during installation. [Means for solving the problem]

[0009] The primary solution to the screw misalignment problem is to provide a bushing sleeve that aligns the external threads of the mating member (mandrel during installation, fastener after installation) with the internal threads of the rivet nut's mating chamber. This sleeve ensures optimal clearance between the sleeve and the mating member, preventing screw misalignment during installation and fastening. Furthermore, a primary solution to detecting improper bulge formation is that this bushing sleeve also provides a visual means of confirming that the rivet nut has been properly installed.

[0010] Generally, the inventions disclosed herein include (or comprise) an improved rivet nut that includes a bushing sleeve for aligning the threads of an incoming screw (or mounting tool) with the threads defining a mating chamber within the rivet nut. One key improvement is the inclusion of a bushing sleeve appropriately fitted within the rear end portion of the rivet nut, which allows the externally threaded tip of the mounting tool's mandrel (or fastener) to act as a guide for rotational mating with the internal threads of the rivet nut's mating chamber. The bushing sleeve also improves control over the formation of an annular valve formed by reverse axial pull of the rivet nut during installation. This valve essentially pinches or clamps the base material between the valve and the underside of the rivet nut head. Increasing the number of threads in the mating chamber also improves control over reverse axial pull. This improved rivet nut can be used in applications where "over-set" installations may be encountered, which apply a greater reverse axial pull than is normally specified for a particular application. In addition to preventing improper installation of rivet nuts and misalignment of threads during fastening, improved rivet nuts and bushing sleeves enable stronger fastening with fewer fastening failures. They can also be designed to provide a reinforced fastening after intentionally induced over-set installation without causing deformation of the valve or other sides of the rivet nut. Furthermore, as a fail-safe to avoid stopping the assembly line after accidental over-set during installation (usually due to miscalibration of the installation tool), the strength of the rivet nut may cause breakage of the installation tool mandrel, which can be easily corrected after the part has moved off the assembly line. [Effects of the Invention]

[0011] One of the main advantages of the disclosed invention is that the sleeve ensures the perpendicularity of the alignment between both threads, eliminating or reducing the possibility of thread misalignment and the resulting defects.

[0012] Another major advantage is that the sleeve provides visual confirmation of whether the rivet nut is properly secured within the hole in the base material.

[0013] Another advantage is that improved rivet nuts can easily provide closed-end rivet nuts that are waterproof or moisture-resistant.

[0014] Another advantage is that rivet nuts improve fastening to the substrate through improved valve characteristics, knurling, and serrations.

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

[0016] Other advantages will become apparent upon examination of this specification. [Brief explanation of the drawing]

[0017] Novel aspects of the disclosed invention that are considered to be characteristic of it are described in the following claims. However, the disclosed invention itself, as well as its preferred uses, further purposes, and advantages, will be best understood by referring to the following detailed description of exemplary embodiments in conjunction with the accompanying drawings.

[0018] [Figure 1] Figure 1 is an exploded perspective view of a typical sample of the improved fastening device of the present invention, arranged for application to a horizontal substrate panel, and includes an improved rivet nut and a bushing sleeve positioned for insertion therein. [Figure 2] Figure 2 is a side elevation view of the rivet nut and bushing sleeve shown in Figure 1. Due to the external symmetry of the rivet nut and bushing sleeve, the side elevation views of both parts after rotating them 90 and 180 degrees are substantially the same. [Figure 3]Figure 3 is a top view of the state where the bushing sleeve is completely inserted into the rear end of the rivet nut and is seated on the annular counterbore step in the counterbore cavity. [Figure 4] Figure 4 is a cross-sectional elevation view of the rivet nut and the inserted bushing sleeve along the plane 4-4 of Figure 3, showing the state after the rivet nut is inserted into the hole of the base material panel indicated by the dashed line. [Figure 5] Figure 5 is the same figure as Figure 4 after the rivet nut is properly installed in the rivet nut panel attachment process. [Figure 6] Figure 6 is a perspective view of the rivet nut and the bushing sleeve of Figure 5. [Figure 7] Figure 7 is the same figure as Figure 5 after the second base material panel (indicated by the dashed line) is overlapped on the first base material panel (and the attached rivet nut), and the tip of the screw fastener is inserted into the inner cavity of the bushing sleeve in the rear end portion of the rivet nut. [Figure 8] Figure 8 is the same figure as Figure 7 after the screw fastener is rotationally fitted into the fitting chamber of the rivet nut. A waterproof end plug is also included. [Figure 9] Figure 9 is a bottom view of the state where the installed rivet nut and the bushing sleeve are separated. [Figure 10] Figure 10 is a top view of the state where the installed rivet nut and the bushing sleeve are separated when the valve does not extend outward beyond the diameter of the head of the rivet nut by installation. [Figure 11] Figure 11 is a cross-sectional view of the side elevation of the installed rivet nut and the inserted bushing sleeve, and is cross-sectioned along the plane 4-4 of Figure 3. This is a split view, with the left side showing the installation of the rivet nut with a longer bushing sleeve for a thicker panel, and the right side showing the installation of the rivet nut with a shorter bushing sleeve for a thinner panel.

[0019] These drawings show certain details of specific embodiments. However, the invention disclosed herein is not limited to only the illustrated embodiments. The invention disclosed herein has embodiments that are equally effective or legally equivalent.

Mode for Carrying Out the Invention

[0020] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the terms “comprises” and / or “comprising,” “includes” and / or “including,” or “have” and / or “having” when used herein specify the presence of the 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.

[0021] For the sake of simplicity and to give the broadest interpretation and construction to the claims of this patent application, the conjunction “and” may be interpreted to include the disjunctive “or” as well, if necessary to give the broadest interpretation and construction to the claims of this patent application, and vice versa. Similarly, when plural forms are used, they may be interpreted to include the singular form, and vice versa.

[0022] While terms such as "first," "second," and "third" may be used in this specification to describe various elements, it will be understood that these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. Similarly, synonyms for the same element, term, or concept may be used solely to distinguish one similar element from another, unless the context clearly indicates otherwise.

[0023] The disclosures herein are not limited by structural materials, insofar as other materials satisfy structural and / or functional requirements. For example, any material may be used for the bushing sleeve, as long as it satisfies the requirements of the counterbore and guide in which it is used. In one embodiment, the bushing sleeve is made of glass-filled nylon material. However, any material with sufficient rigidity and durability will suffice. Similarly, the disclosed inventions are not limited by any manufacturing process or method.

[0024] A device or system configured in a particular way is configured in at least that way, but may also be configured in ways other than those specifically described.

[0025] The terms "comprise" (and all forms of "comprise," such as "comprises" and "comprising"), "have" (and all forms of "have," such as "has" and "having"), and "include" (and all forms of "include," such as "includes" and "including") are open-ended linking verbs. As a result, a device that "comprises," "has," or "includes" one or more elements possesses one or more of those elements, but is not limited to possessing only those elements. Similarly, a method that "comprises," "has," or "includes" one or more steps possesses one or more of those steps, but is not limited to possessing only those steps.

[0026] Any embodiment of the disclosed device, apparatus, system, and / or method consists of (but not comprise / include / have) any of the described elements and / or features and / or steps, or consists essentially of them. Therefore, in any claim, the terms “consisting of” or “consisting essentially of” may be substituted for any of the open-ended linking verbs described above to modify the scope of the claim in a way that differs from that of the open-ended linking verbs used. Any method comprising multiple steps may be limited, but not limited, to the order of the steps enumerated in the method.

[0027] 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.

[0028] The term "substantially flush" means, in the context of the rear end of a counterbore bushing sleeve after upsetting a rivet nut by reverse axial pull-out, that the rear end of the bushing sleeve is coplanar (or slightly below) the counterbore cavity opening of the rear end portion of the rivet nut.

[0029] The term "mating chamber" refers to the internal threaded portion at the insertion end of a rivet nut.

[0030] The term "mating member" refers to either the external thread of a mandrel of a rivet nut mounting tool, or the external thread of an externally threaded fastener intended for a rivet nut to form a fastening joint.

[0031] The term "screw" may include a bolt or any other externally threaded fastener, and the term "bolt" may include a screw or any other externally threaded fastener.

[0032] Each pairing of rivet nut and bushing sleeve performance needs may be size-specific (dependent on the dimensions of the fastener, rivet nut, or base material) or may be specifically designed to meet the performance requirements of a particular application, such as fastening metal or polymer panels, glass-filled plastics, aluminum, steel, or stainless steel. All thread sizes of improved rivet nuts can be manufactured in accordance with the International Organization for Standardization's fastener characteristics classification, particularly classes 8.8 (low carbon steel), 9.8 (medium carbon grade steel), 10.9 (high carbon grade steel and alloys), and 12.9 (high carbon stainless steel and titanium alloys). For example, the length of a bushing sleeve may be determined by adding the thickness of the base material involved in the fastening and the thickness of the rivet nut head, and then subtracting a small amount (about 1 mm) from that length, so that the visible end of the bushing sleeve is positioned just below the surface of the rivet nut head to signal when proper counterboring of the sleeve and upsetting of the rivet nut have occurred. Furthermore, the matching of rivet nuts and bushing sleeves can be adapted for direct and indirect (or OEM or aftermarket) use in specific industries and fields, such as fastening applications in automotive manufacturers and aerospace platforms, as well as fastening applications in home appliances and other general industries. Improved rivet nut bushing sleeve devices can be designed so that the rivet nut better meets the fastening requirements for the specific grade of material used.

[0033] During installation, the rivet nut (with counterbore bushing sleeve) is rotated into the mandrel of the installation tool and inserted into the hole in the base material. The installation tool then applies a reverse axial pull force to the rivet nut, crushing the substantially sleeveless portion of the counterbore wall to form a valve on the underside of the base material. This is known as the "upset" of the rivet nut. During such upsetting, the bushing sleeve reduces lateral "play" between the rivet nut and the installation tool, maintaining the alignment of the rivet nut and facilitating upsetting without tilting or other misalignments creating a defective valve. After upsetting by axial pull of the rivet nut, the inner diameter of the counterbore-counterbore bushing sleeve provides direct alignment for engaging each externally threaded fastener with the internal threads of the mating chamber in the insertion portion of the rivet nut. The inner diameter of the sleeve is typically preferably about 0.0015 inches to 0.0025 inches larger than the outer diameter of the threaded fastener, but other ranges of difference are sufficient as long as the inner diameter of the sleeve is larger than that of the threaded fastener. The sleeve interacts with the counterbore at the bottom of the counterbore to force the alignment of the screw and nut into the threads of the mating chamber. The sleeve functions to reduce or eliminate so-called screw misalignment, i.e., misalignment of the threads that would prevent or damage proper fastening. The sleeve results in consistently defect-free fastening after initial installation, significantly improving the achievement of the goal of providing rivet nuts that meet the fastener industry's goal of zero defective parts per million. The sleeve significantly improves the cross-prevention effect experienced when using screws or bolts with header points, dog points, or projectile points.

[0034] These improvements to rivet nuts offer 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's counterbore, and verification can be performed more quickly and accurately by visually confirming that the fixed rivet nut sleeve is substantially coplanar with the top surface of the rivet nut, verifying that the appropriate axial pull-out distance has occurred during the (upsetting) installation of the rivet nut. The improved rivet nut with the bushing sleeve also provides a more stable and rigid fastening joint when properly "upset" (installed) into the hole in the base material. This improvement also provides resistance to failure due to vibration.

[0035] The design of deeper counterbores (especially with inclined counterbore walls and bushing sleeves) allows for the creation of larger annular valves during upsetting (installation), improving fastening strength and stability. The length of the counterbore walls is increased to increase the surface area for crimping the substrate between the underside of the head (with serrations) and the top surface of the valve (with knurling), and to increase the surface area for contact between the side walls of the hole in the substrate and the adjacent knurling. The improved design has particular utility for substrate materials including plastics (preferably glass-filled but not necessarily), 33% glass-filled PVC, nylon and glass-filled, as well as various grades of aluminum, steel, and titanium.

[0036] The length of the bushing sleeve and its counterbore can be specified for each application depending on the base material and its thickness. The preferred length of the bushing sleeve and its counterbore depends primarily on the needs of the fastening joint (such as the required strength) and the composition of the base material. For example, if a strong fastening is required in a location where significant vibration is expected, the base material must be able to withstand the large compressions during and after the installation of the rivet nut, the rivet nut must be hard enough to withstand such compression and fastening, and the fastener (screw or bolt) must be able to withstand the amount of torque required to achieve optimal fastening.

[0037] In many typical fastening applications, the length of the bushing sleeve is the sum of the substrate thickness and the rivet nut head thickness, resulting in a visible end of the sleeve being coplanar (or just below) the rear end of the rivet nut with proper axial pull-out upset. However, in intentional over-upset installations where a stronger clamping force is desired for the applicable substrate, the length of the bushing sleeve may be shortened by a relatively short distance (often about 1 mm) to ensure a higher rivet nut substrate surface upset clamping load. Furthermore, for some fastening applications involving softer plastic substrate materials, it may be necessary to decrease rather than increase the surface clamping load. In this situation, the bushing sleeve length is increased to match the desired rivet nut upset length required for the substrate material being used. In these situations, the bushing sleeve prevents undesirable over-upset.

[0038] The amount of threads defining the mating chamber of the rivet nut insertion portion has been increased from the minimum required by the Industrial Fasteners Association standards across all different screw fastener sizes, in both metric and inch systems. The improved rivet nut mating chamber contains an additional 4 to 6 threads per inch. The additional threads increase thread strength and reduce thread deformation and thread pull-out / detachment when high driving torque is applied. Axial pull-out tools can even be set to over-set pull-out strength without causing thread deformation / breakage in the rivet nut. (For example, if the application requires a very strong grip on the base material, a slightly shorter depth sleeve can be used to allow the setter tool to provide a longer backstroke axial pull-out during installation / set-up, resulting in a rivet nut with a wider valve, which grips / clamps the base material more firmly on the underside of the head.) The additional thread strength ensures a secure and properly set fastening joint without thread pull-out / detachment and thread distortion / deformation issues, especially when using bushing sleeves installed under over-set-up conditions. In a thread strength test of a Grade 10.9 screw mated to a properly fitted Grade 10.9 rivet nut (with a bushing sleeve of the correct length), when the torque applicable to Grade 12.9 material is applied (so-called over-torque condition), the screw head will break (separate) (from the threaded shank) without torqueing out and / or loosening within the rivet nut fastening joint material.

[0039] Another improvement is the intersection of the serrated underside of the rivet nut head and the knurling on the outer wall of the rivet nut's counterbore; this intersection region is called the underhead joint. The length of the knurling ending at the underhead joint typically (preferably) does not exceed the thickness of the base material. The knurling is optimized to increase contact with the hole wall when the rivet nut is set by reverse axial pull. The knurling also smooths out any sharp edges or burrs in the hole in the base material, making any non-circular holes round. The knurling and underhead joint substantially rework the mounting hole in the base material during setting. The underhead joint also provides a press-fit or rib fit of about 0.003 inches to about 0.006 inches in the hole in the base material. Most importantly, the underhead joint of the rivet nut provides a mechanical lock, completely and firmly filling the hole in the substrate with the rivet nut, more firmly clamping the substrate between the serrations under the head of the rivet nut and the knurling in the hole, and the knurling contacting the inner surface of the substrate surrounding the hole. Conventional rivet nut products in the current industry do not completely fill the hole in the substrate or correct the other defects mentioned above. This is because the substrate mounting hole of a typical rivet nut is larger than the outer diameter of the rivet nut. The interaction of the angled design of the underhead joint increases the edge strength of the hole by approximately 30%, the tensile strength by approximately 48%, and the interface area between the rivet and the hole by approximately 26%. The angled press-fit of the underhead into the hole in the substrate also prevents the penetration of most fluids. Completely and firmly filling the hole in the substrate also eliminates fatigue failure loads in the fastening joint. This improvement provides a press-fit or interlocking fit that stabilizes the interface between the hole in the substrate and the fixed rivet nut, providing a mechanically locked joint.

[0040] The rivet nut design at the bottom of the threaded insertion end allows for locking a plug (epoxy or steel plug) into the end when required or desired for waterproof or moisture-proof applications.

[0041] These and other aspects of the disclosed invention, as well as additional novel features, will become apparent from the description provided herein. The intent of this abstract is not to be a comprehensive description of the subject matter, but rather to provide a brief overview of some of the functionality of the subject matter. Other systems, methods, features, and advantages provided herein will become apparent to those skilled in the art by examining the accompanying drawings and detailed description. Such additional systems, methods, features, and advantages are included in this description and are intended to be within the scope of any claims filed now or later.

[0042] In one general embodiment, the invention disclosed herein includes a device that provides mating alignment between the internal thread of a rivet nut and the external thread of a mandrel of a rivet nut holder before the rivet nut is fixed into a hole in a substrate. Alternatively, the invention includes a device that provides mating alignment between the internal thread of a rivet nut and the external thread of a threaded fastener after it has been fixed into a hole in a substrate. This device is (a) A rivet nut (1) comprising: an insertion portion having an outer diameter sized for tight insertion into a hole in a substrate (outer wall in contact with or close to the substrate) and an inner diameter having an internal thread (17) defining a substantially cylindrical fitting chamber (18); and a rear end portion having a rear end defining a substantially circular opening, the opening having a circumference defined by an inner wall (14) defining a substantially cylindrical cavity leading to the fitting chamber, the fitting chamber having an inner diameter smaller than that of the opening and cavity; (b) A bushing sleeve (20) having a maximum outer diameter sized for tight insertion and retention into the cavity, and an inner diameter sized for guiding the external threads of the mandrel of the mounting tool or the external threads of the fastener into a rotationally fitted into an optimally aligned position with the internal threads of the fitting chamber.

[0043] The inner diameter of the internally threaded insertion portion of a rivet nut is generally defined by the top of the threads (17) that form the boundary of the mating chamber.

[0044] The inner diameter defined by the inner wall (21) of the sleeve is typically equal to or greater than the diameter of the internal threads that define the mating chamber of the insertion portion. The sleeve has an inner diameter in the range of approximately 0.0015 inches to approximately 0.0025 inches larger than the diameter of the internal threads that define the mating chamber.

[0045] The sleeve further includes a first end having an annular chamfer (25) whose outer diameter is smaller than the maximum outer diameter of the sleeve, facilitating tight insertion into the cavity. The sleeve further includes a first annular band (26) adjacent to the chamfer of the first end, having an outer diameter larger than that of the chamfer of the first end but smaller than the maximum outer diameter of the sleeve, facilitating tight insertion of the sleeve into the cavity. The sleeve further includes a second end having an annular chamfer whose outer diameter is smaller than the maximum outer diameter of the sleeve, enabling either the first end or the second end to be facilitated tight insertion into the cavity. The sleeve further includes a second annular band adjacent to the chamfer of the second end, having an outer diameter larger than that of the chamfer of the second end but smaller than the maximum outer diameter of the sleeve, enabling either the first end or the second end to be facilitated tight insertion into the cavity.

[0046] In one preferred embodiment, the cavity comprises a counterbore cavity (1) terminating at an annular counterbore step (16). The sleeve comprises a hollow cylinder having a counterbore end and a rear end, the counterbore end configured to be tightly counterbored into the counterbore cavity adjacent to the annular counterbore step. The sleeve preferably has an inner diameter slightly larger than the inner diameter of the annular counterbore step. The combination and coordination of the two inner diameters should preferably function to substantially funnel-like guide the threaded tip of the mating member to optimal mating alignment with the threads of the mating chamber. The inner diameter of the sleeve preferably has an inner diameter that provides only enough clearance for the incoming mating member to align with the mating chamber.

[0047] The inner wall defining the counterbore cavity has an inner diameter that converges from the opening to an annular counterbore step. The convergence may be continuous from the opening at the head of the cavity to the counterbore step. Alternatively, the counterbore wall may be substantially parallel from the opening at the head to a point before reaching the counterbore step, at which point it may converge continuously to the counterbore step, or it may begin a stepped convergence before initiating continuous convergence to the counterbore step. This convergence substantially funnels the bushing sleeve into the dense counterbore within the counterbore cavity, facilitating the reverse axial withdrawal of the rivet nut and achieving proper upsetting (valve formation).

[0048] The sleeve has a length that allows its rear end to be substantially flush with (or slightly below) the surface of the counterbore cavity opening when the rivet nut is properly installed. This provides visual confirmation of the proper installation of the rivet nut.

[0049] The annular step may have a surface that slopes toward the internal threads defining the mating chamber. This facilitates funnel-like guidance of the threaded end of the incoming fastener (or mandrel of the mounting tool) toward mating alignment with the threads of the mating chamber. Preferably, the annular step has a surface that slopes at an angle in the range of about 20 to about 40 degrees. More preferably, the angle is in the range of about 25 to about 35 degrees. Most preferably, the angle is about 30 degrees. The size and characteristics of the threads often determine the ideal slope.

[0050] The insertion portion typically includes a terminal opening (which is "open-ended") at the insertion end. However, for applications requiring or desiring waterproofing or moisture resistance, the device further includes means for closing the terminal opening, selected from a group of members consisting of water-impermeable adhesives and other materials that durablely seal the insertion portion, as well as mixtures and combinations thereof. Rivet nuts typically seal the insertion end, which is usually open, with water-impermeable adhesives such as polyamide and two-part epoxy, and specially formulated adhesives.

[0051] The rear end portion of the rivet nut further comprises an outer surface on the opposite side of the counterbore cavity, including knurling (15) parallel to the longitudinal axis of the counterbore cavity, which is intended to contact the edge of the hole in the base material to resist rotation of the rivet nut fixed to the hole in the base material. To fix the rivet nut to the hole in the base material and to the base material, while the insertion portion of the rivet nut is fitted with the installation tool before fixing the rivet nut to the hole in the base material, the installation tool applies reverse axial pull to the insertion portion, causing such fixation by crushing the rear end portion including the knurling, resulting in the formation of an annular valve (19) protruding from the body of the rivet nut (excluding the head), and pressing the base material between the head (11) and the valve. The knurling should have a length and number that optimizes rotational resistance contact between the knurling and the side wall of the hole in the base material, in addition to rotational resistance contact between the knurling and the lower surface of the base material.

[0052] The rear end of the rear portion of the rivet nut further includes an annular head flange (11) that surrounds the opening and prevents the rivet nut from passing through the hole in the base material. It further includes radial serrations (13) on the underside of the head for contact with the outer edge of the base material defining the hole in the base material, which are for resisting rotation of the rivet nut fixed in the hole in the base material.

[0053] The serrations (13) on the underside of the rivet nut head provide better surface contact with the outer surface of the substrate. They work in conjunction with the parallel knurling on the outer surface of the rear end portion of the rivet nut to reduce the direct torque-to-rotational spin-out rotation of the rivet nut within the hole in the substrate. The serrations and knurling counteract the screw setting drive torque sequence. These features allow the improved torque-to-rotational drive torque value of the rivet nut to exceed the DC power tool drive torque parameter set for the screw size and grade of the mating screw and the fastener for a secure fastening joint. The rivet nut's ability exceeds the torque-to-rotational drive torque value under the fastener joining load of the screw or bolt's screw size and material grade (8.8 to 10.9), preventing the rivet nut from loosening within the substrate. The screw or bolt self-destructs and fails before the rivet nut loosens within the substrate. The knurling of the shank and the serrations on the underhead provide additional surface contact. Furthermore, the improved length, number, and orientation (radial and parallel) of the serrations and knurling resist the formation of stress concentrations on the substrate surface area.

[0054] In one particular embodiment of the device that provides fitting alignment between the internal thread of a rivet nut and the external thread of a mandrel of a rivet nut mounting tool before fixing the rivet nut into a hole in the base material (or the external thread of an unclaimed threaded fastener after fixing it into a hole in the base material), the device (a) A rivet nut comprising an insertion portion having an outer diameter sized for tight insertion into a hole in a base material and an inner diameter having an internal thread defining a substantially cylindrical fitting chamber, and a rear end portion having a substantially circular opening, the opening having a circumference defined by an inner wall that defines a substantially cylindrical counterbore cavity having an inner diameter converging from the counterbore cavity opening to an annular counterbore step terminating the counterbore cavity, the fitting chamber comprising a rear end portion having an inner diameter smaller than that of the opening and the counterbore cavity, (b) A hollow cylindrical bushing sleeve having a rear end and a counterbore end adjacent to an annular counterbore step for tightly counterbore into the counterbore cavity, the sleeve having a maximum outer diameter sized for tight retention within the counterbore cavity and an inner diameter slightly larger than the inner diameter of the threads defining the mating chamber, for guiding the external threads of the mandrel of the mounting tool or the external threads of the fastener into an optimally aligned rotational mating with the internal threads of the mating chamber, the sleeve also having a length that allows the rear end to be substantially coplanar with the counterbore cavity opening when a rivet nut is properly mounted.

[0055] The insertion portion of the rivet nut further includes a terminal opening defined by the tip (12). For applications requiring or desired waterproofing or moisture resistance, the device further includes means for closing the terminal opening, selected from a group of members consisting of water-impermeable adhesives and other materials for durable sealing of the insertion portion, as well as mixtures and combinations thereof. For example, the water-impermeable adhesive may be a polyamide or a two-part epoxy, and a specially formulated sealant.

[0056] Similar to the embodiments described earlier, the counterbore end further includes an annular chamfered portion (25) that makes the outer diameter of the counterbore end smaller than the maximum outer diameter of the sleeve, facilitating tight insertion into the counterbore cavity. The sleeve further includes a first annular band portion (26) adjacent to the chamfer of the counterbore end, having an outer diameter larger than that of the counterbore end chamfer but smaller than the maximum outer diameter of the sleeve, facilitating tight insertion and retention of the sleeve within the counterbore cavity. The rear end further includes an annular chamfered portion (25) that makes the outer diameter of the rear end smaller than the maximum outer diameter of the sleeve, enabling either the counterbore end or the rear end to facilitate tight insertion into the counterbore cavity. The sleeve further includes a second annular band portion (26) adjacent to the rear end chamfered portion (25), having an outer diameter larger than that of the rear end chamfer but smaller than the maximum outer diameter of the sleeve, enabling either the counterbore end or the rear end to facilitate tight insertion and retention into the counterbore cavity.

[0057] The rear end portion of the rivet nut further comprises an outer surface on the opposite side of the counterbore cavity, including knurling parallel to the longitudinal axis of the counterbore cavity, which is intended to contact the edge of the hole in the base material to resist rotation of the rivet nut fixed in the hole in the base material. While the insertion portion of the rivet nut is fitted with the mounting tool before fixing the rivet nut in the hole in the base material, the mounting tool applies reverse axial pull to the insertion portion, causing such fixing by crushing the rear end portion including the knurling, resulting in the formation of a protruding annular valve that presses the base material between the head and the valve. The knurling has a length and number that optimizes rotational resistance contact between the knurling and the side wall of the hole in the base material, in addition to rotational resistance contact between the knurling and the valve.

[0058] The rear end of the rear portion of the rivet nut further includes an annular head flange that surrounds the opening and prevents the rivet nut from passing through the hole in the base material. Furthermore, the underside of the head has radial serrations (13) for contact with the outer edge defining the hole in the base material in order to resist rotation of the rivet nut fixed in the hole in the base material.

[0059] The counterbore step (16) has an outer diameter defined by the bottom of the counterbore cavity wall (14) and an inner diameter defined by the free edge of the step. In another embodiment, the counterbore step has an inner diameter defined by the inner diameter of the uppermost end of the thread. In another embodiment, the free edge of the counterbore step leads to the beginning of the thread.

[0060] In addition to the apparatus described herein, the invention disclosed herein includes a method for fastening a rivet nut to a substrate. One particular embodiment is: (a) A step of countersinking the bushing sleeve into the cavity at the rear end of the rivet nut, (b) A step of partially screwing the rivet nut into the mounting tool by substantially rotating the external thread of the mounting tool (commonly called a mandrel) with the internal thread of the mating chamber of the insertion portion of the rivet nut, (c) Inserting the tool-fitted rivet nut into a hole in the base material (e.g., a panel) until the head of the rivet nut contacts the outer surface of the base material, (d) The step of operating the mounting tool to complete the rotational fitting of the rivet nut and mandrel, (e) The step of "setting" the rivet nut by operating the installation tool to reverse pull out and crushing the wall portion with knurling until the wall portion is compressed and forms an annular valve that protrudes from the rivet nut by approximately the same amount as the head of the rivet nut, and sandwiching the base material between the lower surface of the head and the upper surface of the valve, (f) A method comprising the step of operating the mandrel in the reverse direction to release the mounting tool from the rivet nut that secures it to the base material.

[0061] This method further includes a step after the complete axial pulling tool sequence described in the preceding paragraph has been achieved, allowing the operator to operate the axial pulling tool to inspect the fastening joint for proper joint integrity upsetting. After upsetting, the bushing sleeve is positioned slightly below (or coplanar with) the surface of the head. If the bushing sleeve is visually observed to have moved only a short distance, leaving a gap from (for example) the top of the rivet nut head to about one-third (1 / 3) below the counterbore, and the bushing sleeve is visually observed not to be in the proper axial pulling upsetting position after upsetting, this is considered an uncontrollable condition and an unsafe fastening joint. The bushing sleeve not being in the specified position after upsetting indicates to the operator using the axial pulling tool that the uncontrollable tolerance of the fastening joint needs to be corrected.

[0062] The method using fixed rivet nuts is, (a) Inserting the tip of the fastener with external threads into the lumen of the bushing sleeve which is counterbore in the cavity of the rear end of the rivet nut, (b) The step of applying pressure while rotating the fastener in the fastening direction, such pressure is applied that allows the sleeve to be guided substantially funnel-shaped to rotational mating contact with the threads defining the mating chamber.

[0063] This method may further include the step of a rivet nut bushing sleeve that acts as a position guide for a male threaded fastener to engage with the threads of a rivet nut for proper thread-to-thread alignment when the threads rotate. The bushing sleeve is a positioning device that reduces cross-thread conditions when a screw drive tool rotates the threaded screw using a mating threaded screw before the threads engage with the threads of a rivet nut.

[0064] While the present disclosure and its merits have been described in detail, it should be understood that various changes, substitutions, and modifications are possible herein without departing from the spirit and scope of the design as defined by the appended claims. The scope of this application is not intended to be limited to specific embodiments of the processes, machines, manufactures, material compositions, means, methods, and / or steps described in the specification. As will be readily apparent to those skilled in the art from this disclosure, any processes, machines, manufactures, material compositions, means, methods, or steps that currently exist or will be developed in the future and perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein may be utilized in accordance with this disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufactures, material compositions, means, methods, or steps. The scope of this application is not intended to be limited to specific embodiments of the processes, machines, manufactures, material compositions, means, methods, and steps described in the specification.

[0065] While preferred embodiments of the present invention have been described, it should be understood that various changes, adaptations, and modifications can be made without departing from the spirit of the invention. These changes can be made particularly in terms of details of shape, size, material, and component arrangement, without exceeding the scope of the invention.

[0066] While the configurations of the apparatus described herein constitute preferred embodiments of the present invention, it should be understood that the present invention is not limited to these exact configurations, and modifications may be made without departing from the scope and spirit of the invention as defined in the appended claims.

[0067] Those skilled in the art will recognize improvements and modifications to preferred embodiments of this disclosure. All such improvements and modifications are deemed to be within the scope of the concepts disclosed herein and the subsequent claims.

[0068] List of References Patent Documents U.S. Patent No. 7,216,520 (granted to Villaneuva on May 15, 2007) U.S. Patent No. 6,102,265 (granted to Stapleton on August 15, 2000) U.S. Patent No. 9,651,080 (granted to Eggers et al. on May 16, 2017) U.S. Patent No. 9,028,185 (granted to Eggers et al. on May 12, 2015) U.S. Patent No. 5,403,135 (granted to Renner et al. on April 4, 1995) U.S. Patent No. 4,321,814 (granted to Martin on March 30, 1982) U.S. Patent No. 11,092,184 (granted to Blaski et al. on August 17, 2021) U.S. Patent No. 9,897,125 (granted to Blaski et al. on February 20, 2018) U.S. Patent No. 7,857,563 (granted to Pratt on December 28, 2010) U.S. Patent No. 3,369,442 (granted to Darby et al. on February 2, 1968) U.S. Patent No. 8,226,339 (granted to Neri on July 24, 2012) U.S. Published Patent Application U.S. Patent Application Publication No. 2020 / 0194,755, dated June 18, 2020, by Maryanski U.S. Patent Application Publication No. 2007 / 0243,035, dated October 18, 2007, by Pratt. U.S. Patent Application Publication No. 2004 / 0247,412, dated December 9, 2004, by Reck. U.S. Patent Application Publication No. 2020 / 0096,032 by Blaski, dated March 26, 2020. U.S. Patent Application Publication No. 2017 / 0335,876, dated November 23, 2017, by Blaski. Foreign patents Chinese Patent Application Publication No. 102,829,056, dated December 19, 2012, by Binquan et al. (inventors) and Hunan Jinwei Section Material (applicant).

Claims

1. An apparatus for providing fitting alignment between the internal thread (female thread) of a rivet nut and the external thread (male thread) of a mandrel, which is an unclaimed rivet nut mounting tool, before fixing the rivet nut into a hole in a substrate having thickness, or the external thread of an unclaimed screw fastener (collectively referred to as "fitting member") after it has been fixed into the hole in the substrate, (a) A rivet nut comprising: an insertion portion having an outer diameter sized for tight insertion into a hole in the base material and an inner diameter having an internal thread defining a substantially cylindrical fitting chamber; and a rear end portion having a substantially circular opening having a circumference defined by an inner wall that leads to the fitting chamber and defines a substantially cylindrical cavity extending at least the thickness of the base material, wherein the fitting chamber has an inner diameter smaller than the opening and the cavity, (b) A bushing sleeve having a maximum outer diameter sized for tight insertion and retention into the cavity, and an inner diameter sized to guide the external thread of the fitting member into an optimally aligned rotational fit with the internal thread of the fitting chamber, A device equipped with the following features.

2. The apparatus according to claim 1, characterized in that the inner diameter of the sleeve is larger than the diameter of the internal thread defining the fitting chamber of the insertion portion.

3. The apparatus according to claim 1, characterized in that the sleeve has an inner diameter in the range of about 0.0015 inches to about 0.0025 inches larger than the outer diameter of the fitting member.

4. The apparatus according to claim 1, wherein the sleeve further comprises a first end having an annular chamfered portion, the outer diameter of which is smaller than the maximum outer diameter of the sleeve, to facilitate tight insertion into the cavity.

5. The apparatus according to claim 4, wherein the sleeve further comprises a first annular band portion adjacent to the chamfered portion of the first end, having an outer diameter larger than the outer diameter of the chamfered portion of the first end but smaller than the maximum outer diameter of the sleeve, and facilitating tight insertion of the sleeve into the cavity.

6. The apparatus according to claim 5, wherein the sleeve further comprises a second end having an annular chamfered portion that makes the outer diameter of the end smaller than the maximum outer diameter of the sleeve, thereby facilitating tight insertion of either the first end or the second end into the cavity.

7. The apparatus according to claim 6, wherein the sleeve further comprises a second annular band portion adjacent to the chamfer of the second end, having an outer diameter larger than that of the chamfer of the second end but smaller than the maximum outer diameter of the sleeve, and enabling tight insertion of either the first end or the second end into the cavity.

8. In the apparatus according to claim 1, (a) The cavity comprises a counterbore cavity that terminates in an annular counterbore step, (b) The apparatus comprising a hollow cylinder having a counterbore end and a rear end having a rear edge, wherein the sleeve is configured such that the counterbore end is adjacent to the annular counterbore step and is tightly counterbored into the counterbore cavity.

9. The apparatus according to claim 8, characterized in that the sleeve has an inner diameter slightly larger than the inner diameter of the annular counterbore step.

10. The apparatus according to claim 8, wherein the sleeve has an inner diameter, and the annular counterbore portion has an inner diameter that provides sufficient clearance to guide the external thread of the fitting member into the rotational fitting which is optimally aligned with the internal thread of the fitting chamber.

11. The apparatus according to claim 8, characterized in that the inner wall defining the counterbore cavity has an inner diameter that converges from the opening to the annular counterbore step.

12. The apparatus according to claim 8, wherein the sleeve has a length that allows its rear edge to be positioned within the counterbore cavity in order to provide visual confirmation that the rivet nut is properly installed.

13. The apparatus according to claim 8, characterized in that the annular stepped portion defines a surface that is inclined toward the internal thread defining the fitting chamber.

14. The apparatus according to claim 13, characterized in that the annular stepped portion defines a surface that is inclined at an angle in the range of about 20 degrees to about 40 degrees.

15. The apparatus according to claim 14, characterized in that the annular stepped portion defines a surface that is inclined at an angle of approximately 30 degrees.

16. The apparatus according to claim 1, wherein the insertion portion further comprises a terminal opening, and the apparatus further comprises means for closing the terminal opening, selected from a group of members consisting of a water-impermeable adhesive, other substances for durablely sealing the insertion portion, and mixtures and combinations thereof.

17. The apparatus according to claim 1, wherein the rear end portion of the rivet nut further comprises an outer surface on the opposite side of the counterbore cavity, which includes knurling parallel to the longitudinal axis of the counterbore cavity, for contact with the edge of the hole in the base material to resist rotation of the rivet nut fixed in the hole in the base material, and while the insertion portion of the rivet nut is fitted with the mounting tool before fixing the rivet nut in the hole in the base material, the mounting tool applies a reverse axial pull to the insertion portion, causing such fixing by crushing the rear end portion including the knurling, resulting in the formation of a protruding annular valve that presses the base material between the head and the knurling of the valve.

18. The apparatus according to claim 17, characterized in that the knurling process has a length and number that optimizes the rotational resistance contact between the knurling process and the side wall of the hole in the base material.

19. The apparatus according to claim 1, wherein the rear end portion of the rivet nut further comprises an annular head flange surrounding the opening and preventing the rivet nut from passing through the hole in the base material, and further comprises an underhead joint inclination and radial serrations on the lower surface of the head for contacting the outer edge of the base material that defines the hole in order to resist the rotation of the rivet nut fixed in the hole in the base material.

20. An apparatus for providing fitting alignment between the internal thread of a rivet nut and the external thread of a mandrel, which is an unclaimed rivet nut mounting tool, before fixing the rivet nut into the hole of the substrate, or the external thread of an unclaimed threaded fastener (collectively referred to as "fitting member") after it has been fixed into the hole of the substrate, (a) A rivet nut comprising: an insertion portion having an outer diameter sized for tight insertion into a hole in the base material and an inner diameter having an internal thread defining a substantially cylindrical fitting chamber; and a rear end portion having a substantially circular opening having a circumference defined by an inner wall that leads to the fitting chamber and defines a substantially cylindrical counterbore having an inner diameter converging from the opening of the counterbore cavity to an annular counterbore step portion terminating the counterbore cavity, wherein the fitting chamber has an inner diameter smaller than the opening and the counterbore cavity, (b) A device comprising a hollow cylindrical bushing sleeve having a rear end with a trailing edge and a seating end adjacent to an annular counterbore step that seats tightly within the counterbore cavity, wherein the sleeve has a maximum outer diameter that is tightly held within the counterbore cavity and an inner diameter that is slightly larger than the inner diameter of the threads defining the mating chamber, to guide the external thread of the mandrel of the mounting tool or the external thread of the fastener into a rotational fit that is optimally aligned with the internal thread of the mating chamber, and the sleeve has a length such that the rear end is substantially coplanar with the opening of the counterbore cavity to provide visual confirmation that the rivet nut is properly installed.

21. The apparatus according to claim 20, characterized in that the sleeve has an inner diameter in the range of about 0.0015 inches to about 0.0025 inches larger than the outer diameter of the fitting member.

22. The apparatus according to claim 20, characterized in that the sleeve has an inner diameter slightly larger than the inner diameter of the annular counterbore step.

23. The apparatus according to claim 20, wherein the sleeve has an inner diameter, and the annular counterbore portion has an inner diameter that provides sufficient clearance to guide the external thread of the fitting member into the rotational fitting which is optimally aligned with the internal thread of the fitting chamber.

24. The apparatus according to claim 20, characterized in that the annular stepped portion defines a surface of the fitting chamber that is inclined toward the internal thread.

25. The apparatus according to claim 24, characterized in that the annular stepped portion defines a surface that is inclined at an angle in the range of about 20 degrees to about 40 degrees.

26. The apparatus according to claim 20, wherein the insertion portion further comprises a terminal opening, and the apparatus further comprises means for closing the terminal opening, selected from a group of members consisting of a water-impermeable adhesive, a substance for durablely sealing the insertion portion, and mixtures and combinations thereof.

27. The apparatus according to claim 20, wherein the counterbore end further comprises a first end having an annular chamfered portion that makes the outer diameter of the counterbore end smaller than the maximum outer diameter of the sleeve, thereby facilitating tight insertion into the counterbore cavity.

28. The apparatus according to claim 27, further comprising a first annular band portion adjacent to the chamfer of the counterbore end, having an outer diameter larger than the outer diameter of the chamfer of the counterbore end but smaller than the maximum outer diameter of the sleeve, which facilitates tight insertion and retention of the sleeve within the counterbore cavity.

29. The apparatus according to claim 20, wherein the rear end portion of the rivet nut further comprises an outer surface on the opposite side of the counterbore cavity, including knurling parallel to the longitudinal axis of the counterbore cavity, which is for contacting the edge of the hole in the base material to resist rotation of the rivet nut fixed in the hole in the base material, and while the insertion portion of the rivet nut is fitted with the mounting tool before fixing the rivet nut in the hole in the base material, the mounting tool applies a reverse axial pull to the insertion portion causing such fixing by crushing the rear end portion including the knurling, resulting in the formation of a protruding annular valve that presses the base material between the head and the knurling of the valve.

30. The apparatus according to claim 20, wherein the rear end portion of the rivet nut further comprises an annular head flange surrounding the opening and preventing the rivet nut from passing through the hole in the base material, and further comprises an underhead joint inclination and radial serrations on the lower surface of the head for contacting the outer edge of the base material that defines the hole in order to resist the rotation of the rivet nut fixed in the hole in the base material.

Images