Blind fastener system having electromagnetic effect protective coating - Patents.com

Abstract

To provide blind fastener systems with coatings that provide electromagnetic effects (EME) protection.SOLUTION: A blind fastener system 100 includes a sleeve 104 and optionally, a core bolt 150 insertable into the sleeve 104, where at least one of the sleeve 104 and the core bolt 150 includes a lubricious metallic coating containing at least one of tin, bismuth, indium and aluminum.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] This application relates to blind fastener systems, and more particularly to coatings that provide electromagnetic effect (EME) protection to blind fastener systems. [Background technology]

[0002] Mechanical fasteners are widely used to join two or more components in a structural assembly, for example, mechanical fasteners are widely used to join structural components in aircraft airframes.

[0003] A blind fastener system, also commonly referred to as a one-sided installation fastener, is a specific type of mechanical fastener. A blind fastener system includes a core bolt and a sleeve, both of which are inserted into appropriate bores in a structural assembly to engage the structural assembly from only one side of the structural assembly, without requiring access from the other side of the structural assembly. Thus, blind fastener systems are suitable for use in applications where access to one side of a structural assembly is difficult or unavailable.

[0004] Aircraft experience electromagnetic effects (EME) from a variety of sources, including lightning strikes and precipitation static. Metallic aircraft structures are relatively insensitive to electromagnetic effects because they conduct electricity well. However, composite (e.g., carbon fiber reinforced plastic) aircraft structures cannot easily guide and shed the large currents and forces resulting from electromagnetic effects. When mechanical fasteners, such as blind fasteners, are used in composite aircraft structures, steps must be taken to protect against electromagnetic effects.

[0005] Accordingly, those skilled in the art continue to conduct research and development efforts in the field of blind fastener systems. Summary of the Invention

[0006] In one embodiment, the disclosed blind fastener system includes a sleeve having a lubricious metallic coating containing at least one of tin, bismuth, indium, and aluminum.

[0007] In another embodiment, the disclosed blind fastener system includes a sleeve having a lubricious metallic coating containing at least one of tin, bismuth, and indium.

[0008] In another embodiment, the disclosed blind fastener system includes a sleeve having a lubricious metallic coating that includes aluminum (such as substantially pure aluminum).

[0009] In another embodiment, the disclosed blind fastener system includes a sleeve and a core bolt insertable into the sleeve, at least one of the sleeve and the core bolt including a lubricious metallic coating containing at least one of tin, bismuth, indium, and alumina.

[0010] In another embodiment, the disclosed blind fastener system includes a sleeve and a core bolt insertable into the sleeve, at least one of the sleeve and the core bolt including a lubricious metallic coating containing at least one of tin, bismuth, and indium.

[0011] In yet another embodiment, the disclosed blind fastener system includes a sleeve and a core bolt insertable into the sleeve, at least one of the sleeve and the core bolt including a lubricous metallic coating containing aluminum (such as substantially pure aluminum).

[0012] In one embodiment, a method is disclosed for providing electromagnetic effect protection to a blind fastener system including a sleeve and a core bolt, comprising coating at least one of the sleeve and the core bolt with a coating composition including at least one of tin, bismuth, indium, and aluminum.

[0013] In another embodiment, a method is disclosed for providing electromagnetic effect protection to a blind fastener system including a sleeve and a core bolt, comprising coating at least one of the sleeve and the core bolt with a coating composition including at least one of tin, bismuth, and indium.

[0014] In yet another embodiment, a disclosed method for providing electromagnetic effect protection to a blind fastener system including a sleeve and a core bolt includes coating at least one of the sleeve and the core bolt with a coating composition including aluminum (such as substantially pure aluminum).

[0015] Other embodiments of the disclosed blind fastener system having an electromagnetic effect protective coating, as well as associated methods for providing electromagnetic effect protection to the blind fastener system, will become apparent from the following detailed description, the accompanying drawings and the appended claims. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a side view of a core bolt of the blind fastener system. [Diagram 2] FIG. 2 is an end view of the core bolt of FIG. 1 with a frangible driving provision included in the core bolt head. [Diagram 3] FIG. 2 is a side cross-sectional view of a sleeve of a blind fastener system having a softened portion along a portion of the length of the sleeve. [Figure 4] FIG. 4 is an end view of the sleeve of FIG. 3. [Diagram 5] 4 is a side cross-sectional view of the core bolt of FIG. 1 combined with the sleeve of FIG. 3 prior to installation in a hole in a structure. [Figure 6] 5 is a side cross-sectional view of the core bolt of FIG. 1 and the sleeve of FIG. 3 installed in the structure of FIG. 5, illustrating the function of the fastener system at minimum and maximum grip. [Figure 7]A side cross-sectional view of the fastener system of FIG. 6 at maximum grip setting, showing the frangible drive provision and core bolt translated rearward along the axis from the front of the structure and buckling of the softened portion of the sleeve. [Figure 8] A side cross-sectional view of the fastener system of FIG. 7 at the minimum grip setting, showing the frangible drive provision and core bolt translated rearward along the axis from the front of the structure and buckling of the softened portion of the sleeve. [Figure 9] 9 is a cross-sectional side view of the fastener system of FIG. 8 illustrating the rotation of the frangible drive provision and core bolt relative to the sleeve to tension the fastener system at minimum and maximum grip settings. [Figure 10] 1 is a cross-sectional side view of the core bolt, sleeve, and structure, further illustrating the separation of the frangible drive provision from the core bolt head at a given fastener preload at minimum and maximum grip settings. [Figure 11] FIG. 13 is a side cross-sectional view of an installation tool configuration. [Figure 12] FIG. 12 is an end view of the installation tool of FIG. [Figure 13] FIG. 12 is a cross-sectional end view of the installation tool of FIG. [Figure 14] 13A-13C are side cross-sectional views of further configurations of an installation tool. [Figure 15] FIG. 15 is a side view of a frangible drive provision configured to complement the installation tool shown in FIG. 14. [Figure 16] FIG. 13 is a side view of a frangible drive provision configuration. [Figure 17] FIG. 17 is an end view of the frangible drive provision shown in FIG. 16. [Figure 18] 13A-13C are side cross-sectional views of further configurations of an installation tool. [Figure 19] FIG. 19 is a side view of a frangible drive provision configured to complement the installation tool shown in FIG. 18. [Figure 20] 13A-13C are side cross-sectional views of further configurations of an installation tool. [Figure 21]FIG. 21 is a cross-sectional end view of the installation tool shown in FIG. 20. [Figure 22] FIG. 21 is a side view of a frangible drive provision configured to complement the installation tool shown in FIG. 20. [Figure 23] FIG. 1 is a flow diagram having one or more operations that may be included in a method of installing a two-piece single-sided attachment fastener system. [Figure 24] FIG. 1 is a flow diagram of an aircraft production and service methodology. [Diagram 25] FIG. 1 is a block diagram of an aircraft. [Figure 26] 4 is a cross-sectional view of a portion of the sleeve of FIG. 3 with a disclosed electromagnetic effect protective coating. [Figure 27] 2 is a cross-sectional view of a portion of the core bolt of FIG. 1 with the disclosed electromagnetic effect protective coating. [Figure 28] FIG. 13 is a side view of a core bolt according to one alternative configuration of the disclosed blind fastener system. [Figure 29] FIG. 29 is a perspective view of a frangible drive provision of the core bolt of FIG. [Diagram 30] FIG. 13 is a side view of a core bolt according to another alternative configuration of the disclosed blind fastener system. [Diagram 31] FIG. 31 is a perspective view of a frangible drive provision of the core bolt of FIG. [Diagram 32] FIG. 13 is a side view of a core bolt according to another alternative configuration of the disclosed blind fastener system. [Diagram 33] FIG. 33 is a perspective view of a frangible drive provision of the core bolt of FIG. [Diagram 34] FIG. 13 is a side view of a core bolt according to another alternative configuration of the disclosed blind fastener system. [Diagram 35] FIG. 35 is a perspective view of a frangible drive provision of the core bolt of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] It has been found that advantages can be obtained by covering the sleeve (or both the sleeve and the core bolt) of a blind fastener system with an electromagnetic effect protective coating as disclosed herein. The electromagnetic effect protective coating of the present disclosure may be used with a variety of blind fastener systems including a core bolt received in a sleeve, whether or not the sleeve is threaded, without departing from the scope of the present disclosure.

[0018] Turning now to the figures to illustrate various embodiments, FIG. 1 shows a side view of a core bolt 150 of an exemplary blind fastener system 100 according to one particular non-limiting example of the present disclosure. FIG. 3 shows a side view of a sleeve 104 sized and configured to mate with the core bolt 150 of FIG. 1 for installation in a hole 302 (FIG. 5) of a structure 300. In FIG. 1, the core bolt 150 may include a core bolt head 152 having a core bolt shank 158. The core bolt shank 158 may have external core bolt threads 160 formed along at least a portion of the length of the core bolt shank 158 and terminating in a core bolt end 162. Although the core bolt shank 158 is shown as being substantially unthreaded along a majority of the length 164 of the core bolt, the core bolt shank 158 may be threaded along any portion of the length 164 of the core bolt from the core bolt head 152 to the core bolt end 162.

[0019] 1, the core bolt threads 160 may be formed with a diameter less than the core bolt diameter 166. However, the core bolt threads 160 may be formed with any diameter relative to the core bolt diameter 166. The core bolt 150 is shown as having a countersunk head 156 with a core bolt bearing surface 154 in a tapered configuration. However, the core bolt head 152 may be provided in any configuration, including a raised head configuration (not shown), where the core bolt bearing surface 154 may have a generally flat or non-tapered configuration.

[0020] 1 and 2, the frangible drive provision 180 may be included in the core bolt head 152. In one configuration, the frangible drive provision 180 may be integrally formed with the core bolt head 152 and the core bolt shank 158. The frangible drive provision 180 may have a generally elongated shape and may project outwardly from the core bolt head 152. The frangible drive provision 180 is generally aligned with the fastener axis 102 of the core bolt 150 and may generally have a smaller outer diameter than the core bolt head 152.

[0021] The frangible drive provision 180 may include an axial translation mechanism 192 and a rotation mechanism 186. The axial translation mechanism 192 may be configured to facilitate axial translation or displacement of the core bolt head 152 along a rearward direction away from a front face 304 (FIG. 5) of the structure 300 (FIG. 5) to induce buckling of the softened portion 132 (FIG. 5) of the sleeve 104 (FIG. 3) against a rear face 306 (FIG. 5) of the structure 300 during an initial portion of installation of the blind fastener system 100. The rotation mechanism 186 may be configured to rotate the core bolt 150 relative to the sleeve 104 (FIG. 5) to apply a tension preload to the blind fastener system 100 after buckling of the softened portion 132 against the rear face 306 of the structure 300, as described in more detail below.

[0022] In FIG. 2, the axial translation feature 192 comprises at least one of a helical thread 194 (FIG. 15), an annular groove 196, or other geometric shape that may be formed in the frangible drive provision 180 to axially translate the core bolt 150. The helical thread 194 may be formed on the exterior of the frangible drive provision 180 and may be configured to be engaged by an installation tool 400 (FIGS. 11-14) to install the blind fastener system 100. For example, the helical thread 194 may be formed with the same thread pitch and thread size as the internal threads of a collet 410 of the installation tool 400 (FIGS. 11-14), as described below. The helical thread 194 may be interrupted by a pair of opposed flats of the rotation feature 186 of the frangible drive provision 180, or the helical thread 194 may be continuous (not shown) around the circumference of the frangible drive provision 180. As shown in Figures 7 and 8, the helical threads 194 may be formed with a length sufficient to allow for sufficient engagement by the threads of the collet 410 so that the installation tool 400 can transmit a sufficient axial load (not shown) to the frangible drive provision 180 to flatten the buckled sleeve portion 138 against the back surface 306 of the structure 300.

[0023] The axial translation mechanism 192 may optionally include an annular groove 196 (FIGS. 1, 19, and 22) configured to complement the collet 410 (FIGS. 18 and 20) of the installation tool 400, such that the collet 410 may grip the annular groove 196 and axially translate the core bolt 150 away from the front surface 304 of the structure 300. The annular groove 196 of FIG. 19 may be formed with a groove pitch and diameter that complements the collet 410 of FIG. 18. Additionally, as shown in FIG. 10 and described below, the annular groove 196 is configured to facilitate the release of the frangible drive provision 180 from the collet 410 when the frangible drive provision 180 breaks from the core bolt head 152. For example, the annular groove 196 may have an angled surface to allow the collet 410 to slidably release the frangible drive provision 180 after it breaks from the core bolt head 152.

[0024] Although the axial translation feature 192 is shown as being formed on the outside of the frangible drive provision 180, it may also be formed on the inside of the frangible drive provision 180, such as in a bore (not shown) that may be formed within the frangible drive provision 180. The rotation feature 186 may be formed on the inside or outside of the frangible drive provision 180 and may include one or more cut surfaces 188 or other features configured to facilitate rotation of the frangible drive provision 180 and the core bolt 150. For example, FIG. 2 shows a frangible drive provision 180 having an outer cut surface 188 with opposing flats 190 for receiving a rotation drive member (e.g., a rotation socket with a rectangular slot, not shown) of an installation tool described below.

[0025] The frangible drive provision 180 may be configured to separate from the core bolt head 152 after applying a tension preload to the blind fastener system 100. For example, the frangible drive provision 180 includes a frangible pin tail 182 having a break groove 184 at an interface 198 between the frangible pin tail 182 and the core bolt head 152. The break groove 184 may provide a reduced cross-sectional area at the interface 198 relative to the cross-sectional area along the remainder of the frangible pin tail 182.

[0026] 3, a side view of the sleeve 104 of the blind fastener system 100 is shown. The sleeve 104 may have a sleeve head 106 and a sleeve shank 114 having a generally hollow tubular configuration extending from the sleeve head 106 to a sleeve tail 126 to define a sleeve length 118. The sleeve 104 may have a sleeve inner diameter 122 sized to complement the diameter 166 (FIG. 1) of the core bolt. The sleeve 104 may have a sleeve outer diameter 120 sized to complement the diameter of the hole 302 (FIG. 5) of the structure 300 (FIG. 5). For example, the sleeve outer diameter 120 may be sized and configured to provide a clearance fit or an interference fit in the hole 302 of the structure 300 (FIG. 5), as described below. The sleeve shank 114 may be provided with a sleeve wall thickness 124 that may be determined in part by the sleeve outer diameter 120. For example, for a sleeve outer diameter 120 of approximately 0.25 inches, the sleeve wall thickness 124 can be approximately 0.015 to 0.030 inches. For a sleeve outer diameter 120 of approximately 0.38 inches, the sleeve wall thickness 124 can be approximately 0.030 to 0.050 inches. However, the sleeve 104 may be provided with any sleeve wall thickness 124 and is not limited to the above ranges.

[0027] In FIG. 3, the sleeve 104 may include a softened portion 132, such as an annealed portion extending along at least a portion of the sleeve length 118. The softened portion 132 may be disposed along the sleeve length 118 such that the softened portion 132 buckles against the back surface 306 (FIG. 5) of the structure 300 to form a buckled sleeve portion 138 (FIG. 7). The softened portion 132 may be annular or band-shaped and may have high ductility, high flexibility, high tendency to buckle under axial compressive load, and / or high formability to the ductility, flexibility, tendency to buckle, or formability of the sleeve 104 at locations outside of the softened portion 132. For example, the softened portion 132 may be formed in the sleeve 104 by any one of a variety of different means, including localized heat treatment or annealing of the sleeve 104, such as by using an induction coil (not shown) placed over the sleeve 104 at locations where softening of the sleeve 104 material is desired. The softened portion 132 may be formed in the sleeve 104 by altering the sleeve cross-section (not shown), such as by reducing the sleeve wall thickness (not shown), which may result in a higher tendency to buckle under axial loading. However, the softened portion 132 may be formed in the sleeve 104 by any one of a variety of different means and is not limited to annealing by localized heat treatment.

[0028] In FIG. 3 , the sleeve shank 114 may include an inner sleeve thread 116 formed at an end of the sleeve 104. The inner sleeve thread 116 is formed to complement the core bolt thread 160 and terminates in a sleeve tail 126. The sleeve tail 126 may include a locking mechanism 128 configured to limit rotation of the core bolt 150 relative to the sleeve 104, such as after installation of the blind fastener system 100 to a structure. The locking mechanism 128 may include a sleeve annular groove 130 that may be formed on the sleeve shank 114 adjacent the sleeve tail 126. However, the locking mechanism 128 may be configured in any one of a variety of different configurations and is not limited to the sleeve annular groove 130. In this regard, the locking mechanism 128 may include any mechanism that may limit rotation of the core bolt thread 160 relative to the inner sleeve thread 116. For example, the locking mechanism 128 may include a nylon patch formed on the inner sleeve thread 116 adjacent the sleeve tail 126. Alternatively, the locking mechanism 128 may include a local formation of the inner sleeve threads 116 that limits rotation of the core bolt 150 relative to the sleeve 104 after installation of the blind fastener system 100 in a structure.

[0029] 3 and 4, the sleeve 104 is shown having a countersunk head 110 with a sleeve bearing surface 108 that bears against the structure 300 (FIG. 5) by a tapered configuration. However, the sleeve head 106 may be provided in a projecting head configuration (not shown) in which the sleeve bearing surface 108 is generally flat and / or parallel to the surface of the structure 300. In this regard, the sleeve head 106 may be provided in any configuration and is not limited to a countersunk head configuration or a projecting head configuration. The sleeve head 106 may include a core bolt pocket 112 that may be sized and configured to receive a core bolt head 152. In the configuration shown, the sleeve head 106 is sized and configured to receive a core bolt 150 having a countersunk head configuration shown in FIG. 1. However, as indicated above, the sleeve head 106 and the core bolt head 152 may be provided in any one of various combinations of countersunk, projecting head (not shown), or other head configurations.

[0030] 4, the sleeve head 106 may include an anti-rotation feature 134 that provides a means for preventing rotation of the sleeve 104 relative to the core bolt 150 and / or relative to the hole 302 (FIG. 5) in the structure 300 (FIG. 5) during installation of the blind fastener system 100. For example, the sleeve head 106 may include one or more recesses or protrusions 136 that may be sized and configured to be engaged by an installation tool (not shown) to prevent rotation of the sleeve 104 relative to the core bolt 150 and / or the hole 302 (FIG. 5) through which the sleeve 104 extends.

[0031] The sleeve 104 and the core bolt 150 may be formed from any one of a variety of different materials, including any metallic and / or non-metallic material. For example, the core bolt 150 and / or the sleeve 104 may be formed from titanium alloys, including 6-6-2Ti, 6-4Ti, 3-8Ti, and other titanium alloys. The core bolt 150 and / or the sleeve 104 may also be formed from steel and / or stainless steels, including A286, A304, and A266 CRES, or other stainless steel alloys. The core bolt 150 and / or the sleeve 104 may also be formed from Inconel, nickel, cobalt, and any alloy, or combinations thereof.

[0032] Referring to FIG. 5, the core bolt 150 is shown assembled with the sleeve 104 prior to installation of the core bolt 150 / sleeve 104 assembly in a hole 302 in a structure 300. The structure 300 may have a front face 304 and a rear face 306. The core bolt 150 is preferably sized such that the core bolt shank 158 of the core bolt 150 does not engage the locking feature 128 of the sleeve 104 when the blind fastener system 100 is first installed in the hole 302 and axially translates the core bolt 150. In FIG. 5, the locking feature 128 of the sleeve 104 may occupy 2-3 or more threads of the inner sleeve threads 116. The softened portion 132 of the sleeve 104 is preferably positioned along the sleeve length 118 such that at least a portion of the softened portion 132 is located immediately below the rear face 306 of the structure 300, as will be described in more detail below.

[0033] In FIG. 5, the front surface 304 of the structure 300 may have a structure bearing surface 308 that may be configured to complement the sleeve bearing surface 108. For example, for a sleeve head 106 having a countersunk configuration with a tapered bearing surface, the structure bearing surface 308 may be similarly tapered. The bore 302 may have a bore 302 diameter that is preferably sized and configured to complement the sleeve outer diameter 120. The bore 302 may be sized and configured to provide a clearance fit with the sleeve outer diameter 120 or to provide an interference fit with the sleeve outer diameter 120. In some configurations, the blind fastener system 100 may be installed by coating the sleeve 104 with a sealant prior to insertion into the bore 302 of the structure 300. For example, for installation of a metal sleeve 104 / core bolt 150 assembly within a composite structure 300, the sleeve 104 may be coated with a wet sealant to protect against galvanic corrosion. The sleeve 104 may also include one or more types of coatings as part of the finish. Such coatings may reduce friction upon insertion of the sleeve 104 into the bores 302 (e.g., interference fit bores) or to facilitate installation in other types of bores, such as clearance bores. Such coatings may include aluminum pigment coatings, lubricious coatings such as dry film lubricants (e.g., molybdenum disulfide), or any one of a variety of other types of coatings.

[0034] Referring to Figure 6, a side view of the core bolt 150 and sleeve 104 installed within a structure 300 is shown illustrating the minimum grip 312 and maximum grip 310 capabilities of the blind fastener system 100. Figure 6 illustrates the structure 300 shown in solid lines representing the application of minimum grip 312 to the blind fastener system 100. In the application of minimum grip 312, the sleeve 104 may be configured such that the softened portion 132 of the sleeve 104 extends above and below the surface of the back surface 306 of the structure 300 to allow buckling of the softened portion 132 against the back surface 306. Figure 6 also illustrates the structure 300 shown in dashed lines representing the application of maximum grip 310 to the blind fastener system 100. In a maximum grip 310 application, the sleeve 104 can be configured such that the softened portion 132 of the sleeve 104 extends above and below the back surface 306 of the structure 300, allowing buckling of the softened portion 132 relative to the back surface 306.

[0035] Advantageously, the disclosed blind fastener system 100 may be installed over a relatively large grip range 314 (e.g., large thickness variations) of the structure 300. For example, a single configuration of the disclosed blind fastener system 100 may include a softened portion 132 that provides a grip range 314 of at least 0.10 inches. Such a relatively large grip range 314 provided by the disclosed blind fastener system 100 is advantageous because it minimizes the number of fasteners of different lengths that must be stocked, as opposed to conventional fastener systems having a relatively small grip range 314 (e.g., 0.050 or 0.063 inches). In addition, the relatively large grip range may provide additional gripping capability that may exceed the range of thicknesses of the structure for which installation is anticipated due to manufacturing tolerances of the structure.

[0036] Referring to FIG. 7, a side view of the blind fastener system 100 is shown during an initial stage of installation with maximum grip 310 applied. The frangible drive provision 180 and the core bolt 150 are axially translated along a rearward direction away from the front face 304 of the structure 300. Axial translation of the core bolt 150 may be provided by engaging the axial translation mechanism 192 of the frangible drive provision 180 with an installation tool, as described below. The sleeve head 106 may be maintained in contact with the structure bearing surface 308 (FIG. 5) during axial translation of the core bolt 150. Displacement of the core bolt head 152 away from the front face 304 results in buckling of the softened portion 132 against the rear face 306 of the structure 300. The softened portion 132 may buckle radially outwardly into a flattened annular buckled sleeve portion 138 against the rear face 306 of the structure 300.

[0037] Referring to Figure 8, the blind fastener system 100 is shown during installation with minimum grip 312 applied. The core bolt head 152 has been moved farther away from the front surface 304 of the structure 300 compared to the displacement of the core bolt head 152 with maximum grip 310 applied as shown in Figure 7. Additionally, the diameter 140 of the buckled sleeve portion with minimum grip 312 applied as shown in Figure 8 is larger than the diameter 140 of the buckled sleeve portion with maximum grip 310 applied as shown in Figure 7.

[0038] Advantageously, the sleeve 104 may be sized and configured such that the softened portion 132 buckles against the back surface 306 to provide a flat buckled sleeve portion 138 having a relatively large bearing area. For example, the sleeve 104 may be sized and configured such that the softened portion 132 buckles to provide a buckled sleeve portion 138 having a minimum diameter that is 1.2 times the sleeve outer diameter 120 (FIG. 3). In this regard, the sleeve 104 may be sized and configured such that the buckled sleeve portion diameter 140 is within a range of approximately 1.2-1.5 times the sleeve outer diameter 120 (FIG. 3). However, the sleeve 104 may be sized and configured such that the buckled sleeve portion diameter 140 is greater than or less than 1.2-1.5 times the sleeve outer diameter 120.

[0039] Referring to FIG. 9, the blind fastener system 100 is shown in which a rotational force can be applied to the core bolt 150 using a rotation mechanism 186 provided on the frangible drive provision 180. The top of the structure 300 in FIG. 9 shows a maximum grip 310 setting on the structure 300, and the bottom of the structure 300 in FIG. 9 shows a minimum grip 312 setting. In FIG. 9, the buckled sleeve portion 138 is nearly fully formed so that the core bolt 150 can be rotated without twisting deformation of the buckled sleeve portion 138, which could otherwise compromise the integrity of the tension preload from fastener to fastener. The core bolt 150 can be rotated relative to the sleeve 104 by engaging a cut surface 188 of the rotation mechanism 186 on the frangible pintail 182 to cause rotation of the core bolt 150 relative to the sleeve 104. For example, an installation tool (not shown) can include a rotational drive bit configured to engage the rotation mechanism 186 on the frangible pintail 182.

[0040] Advantageously, rotation of the core bolt 150 relative to the sleeve 104 applies a tension preload to the blind fastener system 100 or increases the tension preload induced in the blind fastener system 100 as a result of the axial translation of the core bolt 150 (FIGS. 7 and 8). In FIG. 9, because the core bolt threads 160 are engaged with the locking feature 128 of the sleeve tail 126, rotation of the frangible pin tail 182 translates the core bolt head 152 rearward toward the sleeve head 106. The tension preload may be built up in the blind fastener system 100 (e.g., in the sleeve 104 and core bolt 150) while the core bolt 150 is rotated relative to the sleeve 104 until the predetermined fastener preload 316 is reached.

[0041] 10, the blind fastener system 100 is shown set at maximum grip 310 and minimum grip 312 settings for a structure 300. Once a predetermined fastener preload 316 (FIG. 9) is reached, the frangible drive provision 180 may separate from the core bolt head 152 by breaking at the interface 198 between the frangible pintail 182 and the core bolt head 152. For example, the frangible pintail 182 may separate from the core bolt head 152 due to a torsional load causing a break at a fold groove 184 formed at the interface 198 between the frangible pintail 182 and the core bolt head 152. The frangible pintail 182 may also be separated from the core bolt head 152 by axially translating (e.g., pulling) the frangible drive provision 180 until the tension load capacity at the interface 198 between the frangible pintail 182 and the core bolt head 152 is exceeded. Additionally, the frangible pintail 182 may be separated from the core bolt head 152 by bending the frangible pintail 182 relative to the core bolt head 152, causing it to fracturing under a bending load.

[0042] The fastener preload 316 may include a tension preload on the core bolt 150 / sleeve 104 and may correspond to a compression preload on the structure 300 signifying the fastening of one or more components making up the structure 300. The blind fastener system 100 may be configured to control the point (i.e., fastener preload) at which the frangible pintail 182 rotatably breaks (e.g., twists) from the core bolt head 152. For example, the fastener preload 316 may be characterized by the amount of rotation of the frangible pintail 182 relative to the sleeve 104 after the buckled sleeve portion 138 is flattened against the back surface 306 of the structure 300.

[0043] 11-14, an installation tool 400 is shown configured for installation of the blind fastener system 100 (FIG. 9). The installation tool 400 may include a housing 402 having a sidewall 408 and a bearing flange 404. A collet 410 is axially slidable within the housing 402 and may bear against a taper 412 that may be formed in the housing 402. The installation tool 400 may include an ejection spring 418 for ejecting the frangible drive provision 180 from the installation tool 400 after the frangible drive provision 180 (FIG. 10) or the frangible pin tail 182 (FIG. 10) breaks from the core bolt head 152 (FIG. 10). The collet 410 may be segmented as shown in FIG. 13 and the collet 410 segments may expand axially so that the collet 410 may be moved axially over an axial translation feature 192 (e.g., helical threads 194, annular groove 196, FIG. 15) that may be formed on the frangible pintail 182 (FIG. 15). A rotational drive member 416, such as a hex pin, may slide axially within the collet 410. The rotational drive member 416 (e.g., hex pin) may engage a rotational feature 186 (e.g., hex bore) of the frangible pintail 182 (FIG. 15).

[0044] Referring to Figure 12, an end view of the installation tool 400 of Figure 11 is shown illustrating a sleeve engagement feature 406 that may be included on the bearing flange 404 for engaging an anti-rotation feature 134 that may be formed on the sleeve head 106 (Figures 3 and 4). Figure 12 further illustrates the hexagonal shape of the rotational drive member 416 (e.g., hex pin) for engaging a hexagonally cut surface 188 (e.g., hex bore) formed on the frangible pin tail 182 (Figure 15). Figure 13 is a cross-sectional end view of the installation tool 400 illustrating the segmented collet 410 and the rotational drive member 416.

[0045] 11-15 , in operation, the installation tool 400 may be applied over the frangible pintail 182 such that the sleeve engagement feature 406 on the bearing flange 404 engages the anti-rotation feature 134 of the sleeve head 106. As the installation tool 400 is applied over the frangible pintail 182, the free end of the collet 410 contacts the free end of the frangible pintail 182, which causes the segmented collet 410 to expand radially and move axially over the helical threads 194 that may be formed on the frangible pintail 182. The installation tool 400 may include a biasing spring 414 within the housing 402 to bias the rotational drive member 416 against the rotational feature 186 (e.g., a hexagonal bore) of the frangible pintail 182 such that the collet 410 is moved axially over the helical threads 194 of the frangible pintail 182. The biasing spring 414 may have a diameter greater than the outer diameter or width of the rotational drive member 416 so that the biasing spring 414 can bear against an annular flange 417 formed on the rotational drive member 416 .

[0046] After the bearing flange 404 of the installation tool 400 is positioned against the sleeve head 106 and the collet 410 threads are engaged with the helical threads 194 of the frangible pintail 182, the collet 410 and core bolt 150 may be translated axially rearwardly away from the front face 304 (FIGS. 7 and 8) of the structure 300. The outer surface of the collet 410 bears a taper 412 formed on the interior of the housing 402, which may increase the locking force of the collet 410 threads on the helical threads 194 of the frangible pintail 182. As rotation of the collet 410 translates the core bolt 150 axially rearwardly away from the front face 304 (FIGS. 7 and 8), the rotational drive member 416 is configured to initially prevent rotation of the core bolt 150. Rotation of collet 410 continues until softened portion 132 (FIGS. 7 and 8) of sleeve 104 buckles and assumes a flat shape against back surface 306 of structure 300, as shown in FIGS.

[0047] Once flattening of the softened portion 132 (FIGS. 7 and 8) is complete, the rotary drive member 416 may be retracted into a hexagonal bore 419 formed in the collet 410. The collet 410 and rotary drive member 416 may then be rotated (FIG. 9) causing rotation of the core bolt 150 resulting in an increase in the tension preload of the blind fastener system 100 until a predetermined fastener preload is reached. The crease 184 of the frangible pintail 182 may be configured to separate or break (FIG. 10) from the core bolt head 152 at the predetermined fastener preload. The ejection spring 418 urges the outer surface of the collet 410 away from the taper 412 of the housing 402, which allows the segmented collet 410 to expand and release the frangible pintail 182. The frangible pintail 182 may be ejected from the collet 410 by the ejection spring 418.

[0048] 16 and 17, there is shown a configuration of a frangible drive provision 180 having an external rotation mechanism 186. The rotation mechanism 186 may include a pair of tapered flats 422 that may be sized and configured for engagement by a complementary rotation drive member 416 (not shown) of an installation tool (not shown). Engagement of the frangible drive provision 180 of FIGS. 16 and 17 may be similar to the engagement described with respect to operation of the installation tool 400 shown in FIGS. 11-15.

[0049] 18 and 19, an arrangement of an installation tool 400 (FIG. 18) and a complementary frangible drive provision 180 (FIG. 19) is shown. The installation tool 400 may include an internal wrench flat 430 configured to engage an external wrench flat 432 that may be formed in the frangible drive provision 180. The installation tool 400 may include a collet 410 having a complementary annular groove 196 formed in the frangible drive provision 180 for axially translating the core bolt 150 relative to the sleeve 104. The external wrench flat 432 of the installation tool 400 may then be rotated to rotate the core bolt 150 to apply a desired tension preload to the blind fastener system 100.

[0050] 20-22, there is shown an arrangement of an installation tool 400 having a segmented collet 410 with an interior annular groove for engaging an exterior annular groove 196 formed in the frangible drive provision 180 to pull or axially translate the core bolt 150 away from the sleeve 104. FIG. 21 illustrates a pair of inner diameter flats 440 formed on the collet 410 for engaging a pair of complementary outer diameter flats 442 on the frangible drive provision 180 (FIG. 22). Operation of the installation tool 400 of FIGS. 20-22 may be similar to that described above with respect to the installation tool 400 shown in FIGS. 11-15.

[0051] 23 is a flow diagram of a method 500 of implementing the blind fastener system 100 (FIG. 1) as described above. Advantageously, the blind fastener system 100 and method disclosed herein provide a means to achieve a relatively high preload for the blind fastener system 100, providing a relatively large bearing area on the back surface of the structure 300. Additionally, the blind fastener system 100 and method accommodates relatively large structure thickness variations due to the relatively large grip range provided by the blind fastener system 100.

[0052] Step 502 of the method 500 of Figure 23 may include inserting the core bolt 150 and sleeve 104 into a hole 302 of a structure 300, such as an aircraft structure 300 having a front side 304 and a rear side 306, as shown in Figure 6. Although the figure illustrates the structure 300 as comprising a single component, the structure 300 may be comprised of two or more components that may be attached via the blind fastener system 100. As mentioned above, the core bolt 150 has a frangible drive provision 180 coupled to the core bolt head 152. The frangible drive provision 180 may include an axial translation mechanism 192 (Figure 1) and a rotation mechanism 186 (Figure 1).

[0053] Step 504 of the method 500 of FIG. 23 may include translating the core bolt 150 backwards, away from the front face 304 of the hole 302, as shown in FIG. 7 and FIG. 8. As shown in FIG. 7 and FIG. 8, the core bolt 150 may be translated by engaging the axial translation mechanism 192 of the frangible drive provision 180. The sleeve head 106 may be maintained against the structure 300 to prevent axial translation of the sleeve head relative to the hole 302. In one configuration, the core bolt 150 is preferably translated without translation or rotation of the sleeve 104 and / or without rotation of the core bolt 150 relative to the sleeve 104, and without rotation of either the core bolt 150 or the sleeve 104 relative to the hole 302.

[0054] Step 506 of the method 500 of Figure 23 may include buckling the softened portion 132 of the sleeve 104 against the back surface 306 of the structure 300 to form a buckled sleeve portion 138, as shown in Figures 7 and 8. The softened portion 132 may buckle radially outward into an annular sleeve bulb as the core bolt head 152 is translated away from the front surface 304 of the structure 300, as shown in Figures 7 and 8.

[0055] Step 508 of the method 500 of Figure 23 may include flattening the buckled sleeve portion 138 against the back surface 306 of the structure 300, as shown in Figures 7 and 8. In this regard, the core bolt 150 may be generally translated along a direction away from the front surface 304 of the structure 300 until the buckled sleeve portion 138 is generally flattened against the back surface 306 of the structure 300, as shown in Figures 7 and 8. However, the process of buckling of the softened portion 132 (Figures 7 and 8) may be stopped at any point prior to flattening of the softened portion.

[0056] Step 510 of the method 500 of FIG. 23 may include rotating the core bolt 150 relative to the sleeve 104, as shown in FIG. 9. The core bolt 150 may be rotated by engaging a rotation feature 186 formed on the frangible drive provision 180, as shown in FIG. 9. In one configuration, the rotation feature 186 may comprise one or more cut surfaces 188 or other rotation feature geometry that may be provided on the frangible drive provision 180, as shown in FIG. 9. During rotation of the core bolt 150, the core bolt head 152 may return and nest within the core bolt pocket 112 of the sleeve head 106, as shown in FIG. 9. During rotation of the core bolt 150, the core bolt threads 160 may engage a locking feature 128 on the sleeve tail 126, as shown in FIG. 9. The method may include preventing rotation of the sleeve 104 relative to the hole 302 when rotating the core bolt 150 relative to the sleeve 104 by engaging an anti-rotation feature 134 (e.g., a recess or protrusion) that may be formed in the sleeve head 106, as shown in FIG.

[0057] Step 512 of the method 500 of FIG. 23 may include increasing tension in the fastener in response to rotation of the core bolt 150 relative to the sleeve 104 (FIGS. 9 and 10). Advantageously, after flattening the buckled sleeve portion 138, the sleeve 104 may be restrained against rotation relative to the hole 302 (FIGS. 9 and 10), which may facilitate preloading the fastener. The preload may be increased (e.g., within the sleeve 104 and core bolt 150) until a predetermined fastener preload 316 level (FIG. 9) is reached.

[0058] Step 514 of the method 500 of FIG. 23 may include separating the frangible drive provision 180 from the core bolt head 152 at a predetermined fastener preload 316 (FIG. 10). The frangible drive provision 180 may be rotated until separated from the core bolt 150 by exceeding a deformation capacity of an interface 198 (FIG. 9) between the frangible drive provision 180 and the core bolt head 152, by pulling the frangible drive provision 180 (FIG. 10) until a tensile capacity at the interface 198 is exceeded, or by bending the frangible drive provision 180 until a bending capacity of the interface 198 is exceeded. The process may include separating the frangible drive provision 180 from the core bolt head 152 at a fold groove 184 (FIG. 10), which may be formed at the interface 198 between the frangible drive provision 180 and the core bolt head 152.

[0059] 24 and 25, configurations of the present disclosure may be described in the context of an aircraft manufacturing and service method 600, and an aircraft 602, as shown in FIG. 25. During pre-production, the example method 600 may include specification and design 604 of the aircraft 602 and material procurement 606. During production, component and subassembly manufacturing 608 and system integration 610 of the aircraft 602 occurs. The aircraft 602 may then undergo certification and delivery 612 and be placed into service 614. While in service by a customer, the aircraft 602 is scheduled for routine maintenance and service 616, which may include modifications, reconfigurations, refurbishments, etc.

[0060] Each process of example method 600 may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). For purposes of this specification, a system integrator may include, but is not limited to, any number of aircraft manufacturers and subcontractors of major systems, a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and an operator may be an airline, a leasing company, a military entity, a service organization, etc.

[0061] 25 , an aircraft 602 produced by example method 600 may include an airframe 618 with a number of systems 620 and an interior 622. Examples of high level systems 620 include one or more of a propulsion system 624, an electrical system 626, a hydraulic system 628, and an environmental system 630. Any number of other systems may also be included. Although an aerospace example is shown, the principles of the present disclosure may be applied to other industries, such as the automotive industry.

[0062] Apparatus and methods configured herein may be employed in any one or more processes of aircraft manufacturing and service method 600. For example, components or subassemblies corresponding to manufacturing process 608 may be made or manufactured in a similar manner as components or subassemblies manufactured while aircraft 602 is in service 614. Also, one or more apparatus configurations, method configurations, or combinations thereof may be utilized in manufacturing processes 608 and 610, for example, by speeding up assembly of aircraft 602 or reducing costs of aircraft 602. Similarly, one or more of the apparatus configurations, method configurations, or combinations thereof may be utilized while aircraft 602 is in service, for example, but not limited to, maintenance and service 616.

[0063] 26, an electromagnetic effect protective coating 1000 is applied to the body 1002 (FIG. 5) of the sleeve 104 of the blind fastener system 100. Thus, the body 1002 of the sleeve 104 may have a body composition (e.g., titanium alloy, stainless steel, etc., as disclosed herein) and the coating 1000 may have a different coating composition than the body composition of the sleeve 104.

[0064] The disclosed electromagnetic effect protective covering 1000 may cover the entire sleeve 104. However, covering less than the entire sleeve 104 is also contemplated. In one expression, at least 50% of the surface area of ​​the sleeve 104 may be covered by the covering 1000. In another expression, at least 60% of the surface area of ​​the sleeve 104 may be covered by the covering 1000. In another expression, at least 70% of the surface area of ​​the sleeve 104 may be covered by the covering 1000. In another expression, at least 80% of the surface area of ​​the sleeve 104 may be covered by the covering 1000. In another expression, at least 90% of the surface area of ​​the sleeve 104 may be covered by the covering 1000.

[0065] 26, the sleeve 104 can include an exterior surface 1004 and an interior surface 1006. The disclosed electromagnetic effect protective coating 1000 is shown applied to both the exterior surface 1004 and the interior surface 1006. However, in one variation, the coating 1000 can be applied to only one surface, for example, only the exterior surface 1004 of the sleeve 104.

[0066] 27, the disclosed electromagnetic effect protective coating 1000 may also optionally be applied to the body 1010 of the core bolt 150 of the blind fastener system 100 (FIG. 5). Thus, the body 1010 of the core bolt 150 may have a body composition (e.g., titanium alloy, stainless steel, etc., as disclosed herein) and the coating 1000 may have a coating composition that is different from the body composition of the core bolt 150.

[0067] The disclosed electromagnetic effect protective coating 1000 may cover the entire core bolt 150 (e.g., the entire exterior surface of the core bolt 150). However, coating less than the entire core bolt 150 is also contemplated. In one expression, at least 50% of the surface area of ​​the core bolt 150 may be covered by the coating 1000. In another expression, at least 60% of the surface area of ​​the core bolt 150 may be covered by the coating 1000. In another expression, at least 70% of the surface area of ​​the core bolt 150 may be covered by the coating 1000. In another expression, at least 80% of the surface area of ​​the core bolt 150 may be covered by the coating 1000. In another expression, at least 90% of the surface area of ​​the core bolt 150 may be covered by the coating 1000.

[0068] The disclosed electromagnetic effect protective coating 1000 is lubricious, thereby facilitating installation of the blind fastener system 100, such as via the disclosed method 500 (FIG. 23). The disclosed coating 1000 is also electrically conductive, thereby providing protection against electromagnetic effects. The disclosed coating 100 is also electrically compatible with carbon fiber, facilitating use with structures 300 (FIG. 5) formed from carbon fiber reinforced plastic.

[0069] The disclosed electromagnetic effect protective coating 1000 is metallic. In other words, the disclosed electromagnetic effect protective coating 1000 is a metal or a metal alloy.

[0070] In one embodiment, the disclosed electromagnetic effect protective coating 1000 is a metallic coating including at least one of tin (Sn), bismuth (Bi), and indium (In). The coating composition of the coating 1000 may be a design consideration, and the selection of the coating composition may depend on a number of factors, such as the body composition of the lower body 1002, 1010, and the composition of the structure 300 (FIG. 5) in which the blind fastener system 100 (FIG. 5) is to be used.

[0071] The disclosed electromagnetic effect protective coating 1000 can consist essentially of one metal (e.g., tin, bismuth, or indium). Alternatively, the coating 1000 can be an alloy including at least one of tin, bismuth, and indium.

[0072] In one expression, the disclosed electromagnetic effectiveness protective coating 1000 may be (or may include) tin. In other words, the coating 1000 may consist essentially of tin (e.g., substantially pure tin) or may be a tin alloy. A suitable tin alloy may include at least about 50% tin by weight, such as 60% tin or 75% tin by weight. One specific non-limiting example of a suitable tin alloy is tin-indium (Sn-In). Another specific non-limiting example of a suitable tin alloy is tin-bismuth (Sn-Bi), where the bismuth addition may be about 1 to about 3% by weight of the tin-bismuth alloy. Yet another specific non-limiting example of a suitable tin alloy is tin-zinc (Sn-Zn), where the zinc addition may be about 8 to about 15% by weight of the tin-zinc alloy. Yet another specific non-limiting example of a suitable tin alloy is tin-bismuth-zinc (Sn-Bi-Zn), for example, 65.5Sn-31.5Bi-3Zn.

[0073] In other words, the disclosed electromagnetic effectiveness protective coating 1000 can be (or can include) bismuth. In other words, the coating 1000 can consist essentially of bismuth (e.g., substantially pure bismuth) or can be a bismuth alloy. A suitable bismuth alloy can be applied by electroplating, mechanical plating, or vapor deposition and can include at least about 50% bismuth by weight, e.g., at least about 60% bismuth by weight, or at least about 70% bismuth by weight, or at least about 80% bismuth by weight, or at least about 90% bismuth by weight.

[0074] In yet another embodiment, the disclosed electromagnetically effective protective coating 1000 may be indium (or may include indium). In other words, the coating 1000 may consist essentially of indium (e.g., substantially pure bismuth) or may be a bismuth alloy. A suitable indium alloy may be applied by electroplating, mechanical plating, or vapor deposition and may include at least about 50% indium by weight, e.g., at least about 60% indium by weight, or at least about 70% indium by weight, or at least about 80% indium by weight, or at least about 90% indium by weight. One specific, non-limiting example of a suitable indium alloy is indium-tin (In-Sn).

[0075] In one alternative embodiment, the disclosed electromagnetic effect protective coating 1000 is a metallic coating consisting essentially of aluminum. For example, the coating 1000 may be substantially pure aluminum.

[0076] In another alternative embodiment, the disclosed electromagnetic effect protective coating 1000 is a metallic coating that includes aluminum. In other words, the coating 1000 may be an aluminum alloy.

[0077] A variety of techniques may be utilized to apply the disclosed electromagnetic effect protective coating 1000 to the blind fastener system 100 (FIG. 5) without departing from the scope of the present disclosure. One example of a suitable application technique is electroplating. Another example of a suitable application technique is mechanical plating. Yet another example of a suitable application technique is vapor deposition.

[0078] The disclosed electromagnetic effect protective coating 1000 may be applied to the blind fastener system 100 to achieve a desired coating thickness T (FIGS. 26 and 27) of the coating 1000. The coating thickness T may be a design consideration and may depend on a number of factors, such as the coating composition, the size of the blind fastener system 100, and the geometry of the blind fastener system 100. For example, the coating thickness T may vary from about 0.00001 inches to about 0.01 inches, such as from about 0.00001 inches to about 0.001 inches, such as from about 0.00001 inches to about 0.0001 inches.

[0079] Optionally, the disclosed electromagnetically effective protective coating 1000 may be subjected to a conversion treatment, such as a phosphating or chromate conversion treatment. Those skilled in the art will appreciate that the use of a conversion treatment may facilitate the coating (e.g., painting) of all or a portion of the disclosed blind fastener system 100.

[0080] Although the disclosed electromagnetic effect protective coating 1000 is presented with reference to the blind fastener system 100 including a sleeve and a core bolt, as shown and described in detail herein, those skilled in the art will understand that the disclosed electromagnetic effect protective coating 1000 may be used with various sleeve-including blind fastener systems with or without a core bolt (or other mechanism, such as a mandrel received in the sleeve) without departing from the scope of the present disclosure, for example, the disclosed electromagnetic effect protective coating 1000 may be applied to the sleeve (tubular portion) of a blind rivet, such as a pop rivet.

[0081] A method of providing electromagnetic effect protection to a blind fastener system is also disclosed, the blind fastener system including a sleeve and, optionally, a core bolt configured to be received in the sleeve. In one embodiment, the disclosed method includes coating at least one of the sleeve and the core bolt with a coating composition including at least one of tin, bismuth, and indium. In another embodiment, the disclosed method includes coating both the sleeve and the core bolt with a coating composition including at least one of tin, bismuth, and indium. In another embodiment, the disclosed method includes coating at least one of the sleeve and the core bolt with aluminum (e.g., substantially pure aluminum) or an aluminum alloy. In yet another embodiment, the disclosed method includes coating both the sleeve and the core bolt with aluminum (e.g., substantially pure aluminum) or an aluminum alloy. The coating step may be followed by a conversion treatment.

[0082] 28-35, a new core bolt, and more specifically, a drive provision for the core bolt, is disclosed. The new drive provision improves installation of the blind fastener system while reducing manufacturing complexity. Once installation is complete, the new drive provision can be removed from the new core bolt by separation, cutting, etc.

[0083] 28 and 29, the core bolt 1100 includes a core bolt shank 1102 that is extended to include a first end 1104 and an opposing second end 1106. A core bolt head 1108 is disposed on the first end 1104 of the core bolt shank 1102. The core bolt shank 1102 may be threaded (e.g., fully or partially).

[0084] A drive provision 1110 is connected to the core bolt head 1108 of the core bolt 1100. The drive provision 1110 is intended to be engaged by an installation tool, similar to the installation tool 400 (FIG. 11) disclosed herein, such that the installation tool can pull the core bolt 1100 axially along the fastener axis 102 (traction) and rotate the core bolt 1100 about the fastener axis 102 (torque generation). The drive provision 1110 has a maximum transverse dimension D1 that is greater (e.g., substantially greater) than a maximum transverse dimension D2 (diameter) of the core bolt shank 1102.

[0085] The drive provision 1110 includes a head portion 1112 and a shank portion 1114. The head portion 1112 of the drive provision 1110 is configured as a truncated cylinder with laterally opposed cuts 1116, 1118 and defining serrated surfaces 1120, 1122. Those skilled in the art will appreciate that the opposed cuts 1116, 1118 may facilitate torque generation, while the serrated surfaces 1120, 1122 may facilitate traction.

[0086] 30 and 31 , a core bolt 1200 includes a core bolt shank 1202 that is extended and includes a first end 1204 and an opposing second end 1206. A core bolt head 1208 is disposed on the first end 1204 of the core bolt shank 1202. The core bolt shank 1202 may be threaded (e.g., fully or partially).

[0087] A drive provision 1210 is connected to the core bolt head 1208 of the core bolt 1200. The drive provision 1210 is intended to be engaged by an installation tool, similar to the installation tool 400 (FIG. 11) disclosed herein, such that the installation tool can pull the core bolt 1200 axially along the fastener axis 102 (traction) and rotate the core bolt 1200 about the fastener axis 102 (torque generation). The drive provision 1210 has a maximum transverse dimension D1 that is greater (e.g., substantially greater) than a maximum transverse dimension D2 (diameter) of the core bolt shank 1202.

[0088] The drive provision 1210 includes a head portion 1212 and a shank portion 1214. The head portion 1212 of the drive provision 1210 is hexagonal. One skilled in the art will appreciate that the hexagonal head portion 1212 may facilitate torque generation while the larger maximum transverse dimension D1 of the drive provision 1210 may facilitate traction.

[0089] 32 and 33, a core bolt 1300 includes a core bolt shank 1302 that is extended and includes a first end 1304 and an opposing second end 1306. A core bolt head 1308 is disposed on the first end 1304 of the core bolt shank 1302. The core bolt shank 1302 may be threaded (e.g., fully or partially).

[0090] A drive provision 1310 is connected to the core bolt head 1308 of the core bolt 1300. The drive provision 1310 is intended to be engaged by an installation tool, similar to the installation tool 400 (FIG. 11) disclosed herein, such that the installation tool can pull the core bolt 1300 axially along the fastener axis 102 (traction) and rotate the core bolt 1300 about the fastener axis 102 (torque generation). The drive provision 1310 has a maximum transverse dimension D1 that is greater (e.g., substantially greater) than a maximum transverse dimension D2 (diameter) of the core bolt shank 1302.

[0091] The drive provision 1310 includes a head portion 1312 and a shank portion 1314. The head portion 1312 of the drive provision 1310 is configured as a truncated cylinder with laterally opposed cuts 1316, 1318. Those skilled in the art will appreciate that the opposed cuts 1316, 1318 facilitate torque generation while the larger maximum transverse dimension D1 of the drive provision 1310 may facilitate traction.

[0092] 34 and 35, a core bolt 1400 includes a core bolt shank 1402 that is elongated and includes a first end 1404 and an opposing second end 1406. A core bolt head 1408 is disposed on the first end 1404 of the core bolt shank 1402. The core bolt shank 1402 may be threaded (e.g., fully or partially).

[0093] A drive provision 1410 is connected to the core bolt head 1408 of the core bolt 1400. The drive provision 1410 is intended to be engaged by an installation tool, similar to the installation tool 400 (FIG. 11) disclosed herein, such that the installation tool can pull the core bolt 1400 axially along the fastener axis 102 (traction) and rotate the core bolt 1400 about the fastener axis 102 (torque generation). The drive provision 1410 has a maximum transverse dimension D1 that is greater (e.g., substantially greater) than a maximum transverse dimension D2 (diameter) of the core bolt shank 1402.

[0094] The drive provision 1410 includes a head portion 1412 and a shank portion 1414. The head portion 1412 of the drive provision 1410 is bulb shaped and includes laterally opposed cuts 1416, 1418. One skilled in the art will appreciate that the opposed cuts 1416, 1418 facilitate torque generation while the bulb shape of the head portion 1412 may facilitate traction.

[0095] While various blind fastener systems having electromagnetic effect protective coatings have been shown and described, modifications will occur to those skilled in the art upon reading this specification, and the present application includes such modifications and is limited only by the scope of the claims.

[0096] According to one aspect of the present disclosure, a blind fastener system is provided that includes a sleeve that includes a lubricious metallic coating that includes at least one of tin, bismuth, indium, and aluminum.

[0097] The blind fastener system disclosed herein further comprises a core bolt insertable into the sleeve.

[0098] A blind fastener system is disclosed in which the core bolt is provided with a lubricous metallic coating.

[0099] A blind fastener system is disclosed in which at least 50% of the surface area of ​​the sleeve is provided with a lubricious metallic coating.

[0100] A blind fastener system is disclosed in which the sleeve is formed from a metallic material.

[0101] A blind fastener system is disclosed in which the lubricious metallic coating comprises tin.

[0102] A blind fastener system is disclosed in which the lubricious metallic coating comprises tin and bismuth.

[0103] A blind fastener system is disclosed in which the lubricious metallic coating comprises tin and zinc.

[0104] A blind fastener system is disclosed in which the lubricious metallic coating includes tin, bismuth and zinc.

[0105] A blind fastener system is disclosed in which the lubricious metallic coating comprises tin and indium.

[0106] A blind fastener system is disclosed in which the lubricious metallic coating includes bismuth.

[0107] A blind fastener system is disclosed in which the lubricious metallic coating comprises indium.

[0108] A blind fastener system is disclosed in which the lubricious metallic coating comprises aluminum.

[0109] A blind fastener system is disclosed in which the lubricious metallic coating comprises nearly pure aluminum.

[0110] A blind fastener system is disclosed in which a core bolt comprises a core bolt shank and a drive provision connected to the core bolt shank.

[0111] A blind fastener system is disclosed in which the drive provision has a first maximum transverse dimension and the core bolt shank has a second maximum transverse dimension, the first maximum transverse dimension being substantially greater than the second maximum transverse dimension.

[0112] A blind fastener system is disclosed in which the drive provision has a head portion and a shank portion, the head portion being a truncated cylinder with laterally opposed cuts.

[0113] A blind fastener system is disclosed in which the cutting portion comprises a serrated surface.

[0114] A blind fastener system is disclosed in which the drive provision comprises a head portion and a shank portion, the head portion being hexagonal.

[0115] A blind fastener system is disclosed in which the drive provision has a head portion and a shank portion, the head portion having bulb-shaped, laterally opposed cutting portions.

[0116] According to another aspect of the present disclosure, there is provided a method for providing electromagnetic effect protection to a blind fastener system including a sleeve, the method comprising coating the sleeve with a lubricious metallic coating composition including at least one of tin, bismuth, indium, and aluminum.

Claims

1. 1. A blind fastener system comprising: a sleeve having a lubricious metallic coating; and a core bolt insertable into the sleeve, the lubricious metallic coating comprises at least one of tin, bismuth, indium, and aluminum; the core bolt comprises a core bolt shank and a drive provision connected to the core bolt shank; the drive provision having a head portion and a shank portion, the head portion being a truncated cylinder with laterally opposed cuts, the cuts having serrated surfaces; the drive provision having a first maximum transverse dimension and the core bolt shank having a second maximum transverse dimension, the first maximum transverse dimension being greater than the second maximum transverse dimension; Blind fastener system.

2. The blind fastener system of claim 1 , wherein said core bolt is provided with said lubricious metallic coating.

3. The blind fastener system of claim 1 , wherein at least 50% of a surface area of ​​said sleeve is provided with said lubricious metallic coating.

4. The blind fastener system of claim 1 , wherein the sleeve is formed from a metallic material.

5. The blind fastener system of claim 1 , wherein the lubricious metallic coating comprises tin.

6. The blind fastener system of claim 1 , wherein the lubricious metallic coating comprises tin and bismuth.

7. The blind fastener system of claim 1 , wherein the lubricious metallic coating comprises tin and zinc.

8. The blind fastener system of claim 1 , wherein the lubricious metallic coating comprises tin, bismuth and zinc.

9. The blind fastener system of claim 1 , wherein the lubricious metallic coating comprises tin and indium.

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