阅读说明：本技术 桶形螺母保持器 (Barrel nut retainer ) 是由 威廉·塔洛克 保罗·迪安 于 2021-03-29 设计创作，主要内容包括：一种用于将桶形螺母保持在部件的孔中的桶形螺母保持器,该保持器包括：本体,该本体适于配装在孔内并且在第一端部与第二端部之间延伸,并且其中,本体在第一端部与第二端部之间具有构造成接纳桶形螺母的间隙部；以及头部,该头部位于本体的第一端部处,头部适于坐置在孔的敞开端部上。(A barrel nut retainer for retaining a barrel nut in a bore of a component, the retainer comprising: a body adapted to fit within the bore and extend between the first and second ends, and wherein the body has a clearance portion between the first and second ends configured to receive the barrel nut; and a head at the first end of the body, the head adapted to sit on the open end of the bore.)

1. A barrel nut retainer for retaining a barrel nut in a bore of a component, the retainer comprising:

a body adapted to fit within the bore and extend between a first end and a second end, and wherein the body has a gap between the first end and the second end configured to receive a barrel nut, an

A head at the first end of the body, the head adapted to seat on an open end of the bore.

2. The barrel nut retainer according to claim 1, wherein said head is configured to cover said open end of said bore to prevent debris from entering said bore.

3. The barrel nut retainer according to claim 1 or 2, wherein the head portion includes a tool engaging portion for engaging a tool.

4. Barrel nut holder according to any preceding claim, wherein the head comprises an orientation indicator for indicating the orientation of a barrel nut held by the holder relative to the bore.

5. The barrel nut holder according to any preceding claim, wherein the clearance portion is configured to releasably engage the barrel nut.

6. The barrel nut retainer according to claim 5, wherein said clearance portion is sized to form an interference fit with said barrel nut.

7. The barrel nut retainer according to any preceding claim, wherein the body includes a shoulder extending between the first and second ends of the body, wherein the shoulder includes a through hole perpendicular to a longitudinal axis extending between the first and second ends of the body, the through hole configured to align with a corresponding threaded through hole of the barrel nut.

8. The barrel nut retainer according to claim 7, wherein said through hole is equidistant from said first and second ends of said body.

9. Barrel nut holder according to any preceding claim, wherein the clearance portion comprises a recess for receiving a projection of a barrel nut.

10. The barrel nut retainer according to any preceding claim, including a tail at the second end of the body, wherein the tail includes a clip configured to move between:

a first configuration in which the diameter of the clip is substantially equal to or less than the diameter of the body such that the retainer can move through the aperture, an

A second configuration in which the diameter of the clip is greater than the diameter of the body such that the tail is operable to locate the retainer relative to the bore, and preferably the clip in the second configuration is adapted to sit on a second open end of the bore opposite the first open end.

11. The barrel nut retainer according to claim 10, wherein said clip is a spring clip biased toward said second configuration.

12. The barrel nut retainer as recited in any preceding claim, wherein the barrel nut retainer comprises a plastic material.

13. Barrel nut holder according to any preceding claim, wherein the barrel nut holder is manufactured by additive layer manufacturing or injection moulding.

14. Barrel nut holder according to any preceding claim, wherein the holder is integrally formed, preferably as a single piece.

15. A barrel nut assembly comprising:

the barrel nut retainer according to any preceding claim; and

a barrel nut located in the gap portion.

16. An assembly, comprising:

a member having a first hole and a second hole perpendicular to the first hole,

the barrel nut assembly as defined in claim 15, said barrel nut assembly being insertable into said first bore, and

a bolt insertable into the second bore to threadably engage a threaded through-hole in the barrel nut.

17. The assembly of claim 16 when dependent on claim 10,

wherein the component has a pair of opposing faces and the first aperture is a through-hole extending between the pair of opposing faces,

wherein the head portion and the tail portion are each configured to engage a respective one of the pair of opposing faces.

18. The assembly of claim 16 or 17, wherein the assembly is an aircraft assembly and the component is an aircraft component, or wherein the assembly is an automotive assembly and the component is an automotive component.

19. A method for assembling an aircraft assembly, the method comprising:

providing a first component having a first hole and a second hole perpendicular to the first hole and intercepting the first hole at a depth of the first hole,

selecting a barrel nut holder as in any of claims 1 to 14, wherein the barrel nut holder is selected based on the depth of the first bore at which the second bore intercepts the first bore,

inserting a barrel nut into the barrel nut holder,

inserting the barrel nut retainer with the barrel nut into the first bore until the head of the retainer seats on the open end of the first bore and the threaded through bore of the barrel nut is aligned with the second bore.

Technical Field

The invention relates to a barrel nut holder, a barrel nut assembly comprising the holder and a barrel nut, an assembly comprising a component having the barrel nut assembly therein, and a method for assembling an aircraft assembly.

Background

Barrel nuts are used in many applications, particularly in the aerospace industry where it is undesirable for the ends of the fasteners to protrude through the surface of the component or to have no accessible opposing surface between which the nut may be tightened onto the fastener.

Assembly typically involves placing the barrel nut into a bore of the component such that the threaded through bore of the barrel nut is aligned with the fastener passing through the component. The barrel nut can be tightened onto the fastener because rotation of the barrel nut relative to the longitudinal axis of the fastener is limited by the fastener.

However, while rotation of the barrel nut relative to the longitudinal axis of the fastener is limited when the barrel nut is attached to the fastener, when the barrel nut is not attached to the fastener, the barrel nut is free to rotate relative to its longitudinal axis and is able to translate along the bore into which it is placed. This makes alignment of the barrel nut with the fastener difficult and time consuming.

Disclosure of Invention

A first aspect of the invention provides a barrel nut retainer for retaining a barrel nut in a bore of a component, the retainer comprising: a body adapted to fit within the bore and extend between the first and second ends, and wherein the body has a clearance portion (clearance) between the first and second ends configured to receive the barrel nut; and a head at the first end of the body, the head adapted to sit on the open end of the bore.

Another aspect of the present invention provides a barrel nut assembly, including: a barrel nut retainer; and a barrel nut located in the gap portion.

Another aspect of the invention provides an assembly comprising: a member having a first hole and a second hole perpendicular to the first hole; a barrel nut assembly insertable into the first bore; and a bolt insertable into the second bore to threadedly engage the threaded through-hole in the barrel nut.

Another aspect of the invention provides a method for assembling an aircraft component, the method comprising: providing a first component having a first hole and a second hole perpendicular to the first hole and intercepting the first hole at a depth of the first hole; selecting a barrel nut holder as claimed in any preceding claim, wherein the barrel nut holder is selected based on the depth of the first bore at which the second bore intercepts the first bore; inserting a barrel nut into a barrel nut retainer; the barrel nut retainer and barrel nut are inserted into the first bore until the head is seated on the open end of the first bore and the threaded through bore of the barrel nut is aligned with the second bore.

Barrel nuts are nuts having a body with a threaded through bore extending through the body perpendicular to the longitudinal axis of the body. The barrel nut is typically fitted within a first bore of a first component such that a threaded fastener (e.g., a bolt) may pass through a bore in the second component, a second bore of the first component that is perpendicular to and intercepts the first bore, and into a threaded through-bore of the barrel nut that is mounted in the first bore of the first component to secure the second component to the first component.

The barrel nut holder allows the barrel nut to be (pre) installed in the assembly and subassembly at an earlier stage of the supply line, thereby potentially saving a lot of time during the final stage of assembly. The barrel nut is securely held in the components by the retainer, and therefore the number of separate components during assembly can be reduced. The retainer also prevents foreign objects from entering the hole in which the barrel nut is to be installed prior to assembly. The barrel nut retainer allows for the use of existing barrel nuts without modifying the design of the existing barrel nut so that an off-the-shelf barrel nut can be selected and used in a given bore without enlarging or otherwise modifying the bore in which the barrel nut is placed. The head ensures that the barrel nut is positioned in the desired axial position in the bore and can thus be easily aligned with the corresponding fastener.

Optionally, the head is configured to cover the open end of the bore to prevent debris from entering the bore.

Optionally, the head comprises a tool engagement portion for engagement with a tool. With this arrangement, the holder and barrel nut retained within the holder can be easily rotated to rotationally align the barrel nut with its corresponding fastener.

Optionally, the head includes an orientation indicator for indicating the orientation of the barrel nut held by the holder relative to the bore.

Optionally, the clearance portion is configured to releasably engage the barrel nut.

Optionally, the clearance portion is sized to form an interference fit with the barrel nut.

Optionally, the body comprises a shoulder extending between the first and second ends of the body, wherein the shoulder comprises a through-hole perpendicular to a longitudinal axis extending between the first and second ends of the body, the through-hole configured to align with a corresponding threaded through-hole of the barrel nut.

Optionally, the through-hole is equidistant from the first end and the second end of the body.

Optionally, the clearance portion comprises a recess for receiving a projection of the barrel nut. The mating recesses and protrusions may align the barrel nut in the gap portion of the retainer.

Optionally, the barrel nut retainer includes a tail at the second end of the body, wherein the tail is a clip configured to move between: a first configuration in which the diameter of the clip is substantially equal to or less than the diameter of the body such that the retainer can move through the aperture; and a second configuration in which the diameter of the clip is greater than the diameter of the body such that the tail is operable to position the retainer relative to the bore. Optionally, the clip in the second configuration is adapted to sit on a second open end of the aperture opposite the first open end. With this arrangement, the retainer can be releasably fitted within the through-hole.

Optionally, the clip is a spring clip biased towards the second configuration. By this arrangement, the tail may be moved between the first and second configurations when entering and/or exiting a hole in the component without requiring direct manipulation or access to the clip, for example when positioning the retainer in a blind hole or through hole without accessing the distal end. The holder can simply be pushed into the hole.

Optionally, the barrel nut retainer comprises a plastic material. Plastics are generally lightweight and inexpensive materials that can be manufactured quickly and in large quantities and to acceptable tolerances.

Alternatively, the barrel nut retainer is manufactured by additive layer manufacturing or injection molding.

Alternatively, the holder is integrally formed, preferably as a single component. By forming the retainer as a one-piece component, there are no secondary components that may be lost or misplaced during assembly.

Optionally, the component has a pair of opposed faces and the first bore is a through bore extending between the pair of opposed faces, wherein the head and tail portions are each configured to engage a respective one of the pair of opposed faces.

Optionally, the component is an aircraft component and the part is an aircraft part. The retainer is particularly advantageous during aircraft assembly, in part because the barrel nut can be pre-installed in the aircraft component (which may form part of an aircraft assembly or subassembly) prior to joining the aircraft component to another aircraft component. This may be particularly advantageous in cases where the part holding the barrel nut is a supplier part or is transported/transported to another location for joining to another part.

Optionally, the component is an automotive component and the part is an automotive part. The retainer is particularly advantageous for automotive components, in part due to the fast moving supply chain and assembly process.

Drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows a plan view of an aircraft;

FIG. 2A shows a wing box having a rear spar with a forward facing flange;

FIG. 2B shows the rear of a wing box having a rear spar with a forward facing flange;

FIG. 3A shows a wing box having a rear spar with a rearwardly facing flange;

FIG. 3B shows the rear of a wing box having a rear spar with a rearward facing flange;

figure 4 shows a control surface actuation mechanism attached to a wing box;

FIG. 5 illustrates components of a control surface actuation mechanism;

fig. 6 shows a barrel nut holder according to a first example;

FIG. 7A shows a side view of a barrel nut retainer within a bore of a control surface actuation mechanism;

FIG. 7B shows a cross section of a barrel nut within a bore of a control surface actuation mechanism;

fig. 8A shows a barrel nut holder according to a second example;

fig. 8B shows an end view of the head of a barrel nut holder according to a second example.

Detailed Description

Fig. 1 shows an aircraft 1, which aircraft 1 comprises a port fixed wing 2 and a starboard fixed wing 3 and a fuselage 4 with a nose 5 and a tail 6. The aircraft 1 is a typical jet transonic passenger aircraft, but the invention is also applicable to a variety of fixed wing aircraft types, including commercial, military, passenger, freight, jet, propeller, general aviation, etc., having any number of engines 9 attached to the wing or fuselage.

Each wing 2, 3 has a cantilevered structure with a length extending in a spanwise direction from a wing root 7 to a wing tip 8, the wing root 7 being joined to the fuselage 4. The wings 2, 3 are similar in construction and therefore only the port wing 2 will be described in detail with reference to the accompanying drawings.

In the following description, the term "forward" refers to components towards the leading edge 11 of the wing and the term "aft" refers to components towards the trailing edge 12 of the wing. The terms "forward" and "rearward" should be construed accordingly. The position of the features may be explained with respect to other features, e.g. the front part may be arranged on the front side of the other part, but towards the rear of the carrier. Similarly, the terms "upper" and "lower" refer to the position of a feature relative to other features and according to the normal orientation of the aircraft 1.

Fig. 2A shows a schematic view of a wing box 10 of a port wing 2 of an aircraft 1. The wing box 10 is a support structure arranged to support the majority of the loads on the wing 2. The wing box 10 has a front spar 13, a rear spar 14, an upper cover 15 and a lower cover 16, each extending over substantially the entire length of the wing 2. The upper and lower covers 15, 16 have an outer aerodynamic surface. The wing 3 further comprises a leading edge structure (not shown) and a trailing edge structure (not shown) aerodynamically shaped to form an airfoil shaped body in combination with the wing box 10.

The front and rear spars 13, 14 are "C-shaped", each spar 13, 14 including an inwardly facing flange 13a, 13b, 14a, 14b, the inwardly facing flanges 13a, 13b, 14a, 14b providing attachment for attaching the spar 13, 14 to the cover 14, 16. By "inwardly facing" it is meant that the flanges extend towards the centre of the wing box 10 such that the flanges 13a, 13b of the front spar 13 extend rearwardly towards the trailing edge 12 of the wing 2 and the flanges 14a, 14b of the rear spar 14 extend forwardly towards the leading edge 11 of the wing 2.

Figure 2B shows a schematic view of the rear of the wing box 10 with the attachment brackets 21, 22 of the control surface actuation mechanism connected to the rear spar 14.

Typically, after the wing box 10 has been assembled such that the rear spar 14 is connected to the upper and lower caps 15, 16, the attachment brackets 21, 22, as well as any other systems and movable structures, are connected to the rear spar 14. Thus, the space within the rear region of the spar 14 is limited, and this may make fitting/attachment of the system challenging.

Fig. 3A shows a schematic view of a wing box 110 according to a second example, wherein the front and rear spars 113, 114 comprise outwardly facing flanges 113A, 113b, 114a, 114b, respectively, the outwardly facing flanges 113A, 113b, 114a, 114b providing attachment for attaching the spars 113, 114 to the covers 114, 116. By "outwardly facing" it is meant that the flanges extend away from the centre of the wing box 10 such that the flanges 113a, 113b of the front spar 113 extend forwardly towards the leading edge 11 of the wing 2 and the flanges 114a, 114b of the rear spar 114 extend rearwardly towards the trailing edge 12 of the wing 2.

An advantage of the outwardly facing flanges 113a, 113b, 114a, 114b on the spars 113, 114 is that they enable the spars 113, 114 to be fastened to the covers 115, 116 from the outside of the wing box 110.

As a result, the space near the spars 113, 114 to attach the aircraft system is further reduced. For example, fig. 3B shows a schematic view of the rear of the wing box 110, with the attachment brackets 21, 22 of the control surface actuation mechanism connected to the rear spar 114. As such, it may not be possible or possible to utilize standard nut and bolt fasteners.

Fig. 4 shows a control surface actuation mechanism 20, e.g. for a flap or aileron, coupled to attachment brackets 21, 22. The control surface actuation mechanism 20 includes an actuator 23 attached to the upper attachment bracket 21, and a link 24 rotatably coupled between the lower attachment bracket 22 and the actuator 23. The actuator 23 comprises an attachment portion 25 for attachment to a control surface.

The connection between the actuator 23 and the upper attachment bracket 21 is achieved via a captive nut solution. The fastener 30 extends through the actuator 23 and into a barrel nut (not shown) that locks within the bore 45 of the upper attachment bracket 21.

Due to the limited access of the upper rear portion of the wing box 110, and in particular the lack of opposing surfaces to tighten the nut onto the fastener 30, a barrel nut and fastener combination is required.

The connection is made by inserting the barrel nut into a hole 45 in the upper attachment bracket 21, passing the fastener 30 through the actuator 23 and the holes in the upper attachment bracket 21, wherein the fastener hole connects with the hole 45 into which the barrel nut is inserted and the fastener hole is perpendicular to the hole 45. In this manner, the fastener 30 may be inserted into the threaded through-hole of the barrel nut. Because rotation of the barrel nut relative to the longitudinal axis of the fastener is limited by the fastener, the barrel nut can be tightened onto the fastener as the fastener is inserted through the barrel nut.

However, while rotation of the barrel nut relative to the longitudinal axis of the fastener is limited when the barrel nut is attached to the fastener, when the barrel nut is not attached to the fastener, the barrel nut is free to rotate about its own longitudinal axis and can translate along the bore into which it is placed. This makes alignment of the barrel nut with the fastener difficult and time consuming. The limited access at the rear of the wing box 110 shown in figure 4 also means that the handling of the barrel nut within the bore becomes more challenging.

Barrel nuts also run the risk of slipping out of the hole and being lost, a problem that is of particular concern in aircraft assembly.

Fig. 5 shows a perspective view of the attachment brackets 21, 22, wherein two barrel nut holders 50 according to a first example are shown. The barrel nut holder 50 is designed to hold the barrel nut in the bore of the first attachment bracket 21.

The design of the barrel nut retainer 50 ensures that the retainer can retain a barrel nut without modifying the design of an existing barrel nut so that an off-the-shelf barrel nut can be selected and the bore in which the barrel nut is placed need not be enlarged or otherwise modified. Further, the barrel nut retainer 50 includes a plurality of features to ensure that the barrel nut retained by the barrel nut retainer 50 can be positioned in a desired axial and rotational position and, thus, can be easily aligned with a corresponding fastener. The barrel nut holder 50 ensures that the barrel nut is secured within the bore of the component and the barrel nut holder 50 also enables the barrel nut to be installed in the component and subassembly at an earlier stage of the supply line, thereby potentially saving a significant amount of time during the final stage of assembly, since the component is already pre-installed with the barrel nut and can be physically transported in the supply chain.

A barrel nut retainer 50 is shown in fig. 6. The barrel nut holder 50 is made of Acrylonitrile Butadiene Styrene (ABS) and is manufactured by additive layer manufacturing.

The barrel nut retainer 50 includes a cylindrical body 51 adapted to provide an interference fit within the bore of the component. The body 51 extends along a longitudinal axis of the holder between a first end 52 and a second end 53, the body 51 having a gap 54 between the first end 52 and the second end 53, the barrel nut being configured to be received in the gap 54. At the first end 52 of the gap portion 54 is a first end face (not shown). At a second end of the gap portion 54 is a second end face 53 a. The first and second end faces 53a are opposing faces orthogonal to the longitudinal axis of the retainer 50, and are configured to engage with corresponding end portions of the barrel nut received in the gap portion 54.

The clearance portion 54 is arranged to form an interference fit with the barrel nut so that the barrel nut is held between the first and second ends 52, 53 of the barrel nut holder 50, but is releasable when required. For example, the barrel nut may be manually removed from the holder 50 by a user.

The head 55 is positioned at the first end 52 of the body 51. The head 55 is arranged to sit on the open end of the bore so as to completely cover the opening of the bore. This, together with the interference fit of the retainer 50 in the hole, helps prevent debris from entering the hole.

The head 55 includes a recess 61, the recess 61 serving as a tool engagement portion with which a tool, such as a screwdriver or other device, can mate and enable the holder 50 to rotate within the bore.

Surrounding the recess 61 of the head 55 is an inscribed arrow 62, which indicates the orientation of the barrel nut holder 50. This allows the orientation of the barrel nut held by the retainer 50 to be determined so that the barrel nut can be more easily aligned with the fastener.

The body includes a shoulder 58 extending between the first end 52 and the second end 53 of the body. Equidistant between the first end 52 and the second end 53 is a through hole 59 perpendicular to the longitudinal axis of the body 51, the through hole 59 being arranged in alignment with a corresponding threaded through hole of the barrel nut.

The clearance portion 54 includes a recess 65, the recess 65 surrounding the through hole 59, and the recess 65 being configured to receive a correspondingly shaped portion of the barrel nut to assist in retaining the barrel nut in the retainer 50.

The tail 56 is positioned at the second end 53 of the body 51. The tail 56 is a clip configured to be movable between a first configuration and a second configuration having spring clip elements 57a, 57b disposed radially about a longitudinal axis of the retainer 50 (although only two of the spring clip elements are shown in fig. 6, the tail 56 may include two, three, four, or more spring clip elements). The spring clip elements 57A, 57B extend beyond the radial extent of the portions of the body 51 between the head 55 and tail 56 such that when the tail 56 is unconstrained, the diameter of the tail 56 is greater than the diameter of those portions of the body 51, but the spring clip elements 57A, 57B are able to flex resiliently to reduce the diameter of the tail 56 when necessary, as will be explained with respect to fig. 7A and 7B.

Fig. 7A shows the barrel nut holder 50 and barrel nut 40 received within the bore of the component, in this case the upper attachment bracket 21 shown in fig. 4 and 5.

Assembly of an aircraft component, for example, is accomplished by inserting the barrel nut 40 into the gap 54 of the retainer 50 such that the barrel nut 40 is retained by the interference fit of the gap 54 with the barrel nut 40. Barrel nut 40 may also be partially retained in retainer 50 by placing protrusion 46 into recess 65 of gap 54 as previously discussed.

The retainer 50 is then placed into the hole 45 on the first side 21a of the member 21 by first inserting the tail 56. In this way, clip elements 57a, 57b (shown in fig. 6) bend relative to body 51 of retainer 50 such that tail 56 is constrained by the wall of the hole and the diameter of tail 56 is reduced to the diameter of the hole. This ensures that the retainer 50 can be inserted through the hole without damaging the hole or the retainer 50.

Hole 45 is a through hole so that retainer 50 can be inserted directly through the hole until tail 56 exits on second side 41 of the hole, at which point clip elements 57a, 57b are once again unconstrained and can spring back to their nominal diameter, which is greater than the diameter of the hole. In this way, the body 51 is locked within the bore until the spring clip elements 57a, 57b flex again to reduce the diameter of the tail 56. When the retainer 50 is locked within the bore 45, the tail 56 is arranged to sit on the open end of the bore 45, covering the opening of the bore to prevent debris from entering the bore.

As shown in fig. 7A, the retainer 50 is thereby secured between the head 55 and tail 56, thereby locking the longitudinal position of the retainer 50 and barrel nut 40 within the bore 45.

The position of the barrel nut 40 in the bore 45 is determined by the dimensions of the retainer 50, i.e., the position of the clearance portion 54 relative to the first and second side surfaces 21a, 21b of the member 21 determines the position of the barrel nut 40 relative to those same side surfaces 21a, 21 b.

Thus, retainer 50 is selected based on the total depth 70 of hole 45 (i.e., the depth of hole 45 measured between first side 21a and second side 21 b-see fig. 7A) such that the distance between head 55 and tail 56 matches the total depth 70 of hole 45, thereby allowing retainer 50 to be secured within hole 45. Further, the dimensions of the clearance portion 54 and the recess 65 of the clearance portion 54 are each selected based on the dimensions of the barrel nut 40, and the relative distance of the clearance portion 54 from the head portion 55 and the tail portion 56 (and thus the position of the barrel nut 40) is selected based on the desired position of the barrel nut 40 in the bore, and in particular, such that the threaded through bore of the barrel nut 40 is aligned with the fastener 30.

The fastener 30 is inserted through a second bore 35 perpendicular to the first bore 45 and through a threaded through-hole in the barrel nut 40.

The fastener 30 may also pass at least partially through the through hole 59 of the shoulder 58, although the space provided by the through hole 59 is typically arranged to receive an excess (burrs) and burrs off the barrel nut 40 when the bolt 30 is inserted into the barrel nut.

The relative positions of the clearance portion 54, the head portion 55 and the tail portion 56, respectively, help to ensure that the barrel nut 40 is aligned with the fastener 30 along the axial direction of the bore 45.

Fig. 7B shows a cross-section of the assembly partially taken between the first side 21a and the second side 21B of the member 21, where the barrel nut 40 has been rotated into alignment with the fastener 30 so that the fastener 30 can pass through the threaded through-hole of the barrel nut 40.

To assist in rotationally aligning the barrel nut 40 with the fastener 30, the head 55 includes a recess 61 (shown in fig. 6), the recess 61 being engageable by a flat head screwdriver, thereby allowing the holder 50 to be easily rotated within the bore 45.

The head 55 also includes an inscribed arrow 62, which arrow 62 may be used as an indication of the orientation of the barrel nut 40 held by the barrel nut holder 50. Thus, the arrow 62 may serve as a guide to align the threaded through-hole of the barrel nut 40 with the fastener 30. In an alternative example, the orientation of the barrel nut retainer 50 may alternatively be indicated by any asymmetric feature visible on the head 55. Alternatively, the retainer 50 may be blindly rotated until alignment with the fastener 30 is achieved.

Fig. 8A and 8B show a barrel-shaped nut holder 150 according to a second example, the barrel-shaped nut holder 150 being substantially identical to the barrel-shaped nut holder 50 of the first example, and wherein the same reference numerals are used to identify the same components as in the first example, and similar reference numerals, but numbered in the 100 series, are used to identify similar components as in the first example.

As shown in fig. 8A, the barrel nut holder 150 is substantially identical to the first barrel nut holder 50. The barrel nut holder 150 of the second example differs in that the head 155 is adapted to engage with a wrench or spanner, for example. The profile of the head 155 is hexagonal with six flat sides 66a, 66B, 66c, 66d, 66e, 66f arranged radially around the head 155, as shown in fig. 8B.

It will be clear to a person skilled in the art that the above examples can be adapted in various ways.

In alternative examples, the recess 61 may alternatively be adapted to engage with a differently shaped tool, or may be a protrusion that provides a surface on which a tool (or user) may grasp the holder 50.

The retainer 50 is described as being formed from ABS, in alternative examples, the retainer 50 may be formed from other plastic materials such as polylactic acid (PLA) and polycarbonate. The retainer 50 may also be formed from other materials such as stainless steel, nickel alloys, aluminum, or any other suitable metal.

The retainer may be manufactured by additive layer manufacturing techniques. Alternatively, the retainer may be manufactured by fuse fabrication (FFF), Selective Laser Sintering (SLS), injection molding, or any other suitable technique.

In some examples, clip elements 57a, 57b may not be spring clip elements 57a, 57b, but may be clip elements 57a, 57b that are manually moved or switched between a first configuration sized to fit within bore 45 and a second configuration that wedges retainer 50 within bore 45. In further examples, the retainer 45 may be suitably adapted to be inserted into a blind hole. The tail 56 may include one or more spring elements that open into a groove formed in the circumference of the blind bore partially along the length of the bore to position the retainer in the blind bore. The spring element may be, for example, a circlip, or may be similar to the clip elements 57a, 57 b.

In some examples, the retainer may not have an interference fit with the bore, but rather the retainer may be designed to have some degree of movement to account for any angular misalignment of the barrel nut relative to the fastener.

Where the word "or" is present, this should be construed as meaning "and/or" such that the items referred to are not necessarily mutually exclusive and may be used in any suitable combination.

Although the invention has been described above with reference to one or more preferred embodiments, it should be understood that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.