GB2580131A

GB2580131A - Threaded fastener assembly

Info

Publication number: GB2580131A
Application number: GB1821061.7A
Authority: GB
Inventors: Fleming Barry
Original assignee: Raytheon Systems Ltd
Current assignee: Raytheon Systems Ltd
Priority date: 2018-12-21
Filing date: 2018-12-21
Publication date: 2020-07-15
Anticipated expiration: 2038-12-21
Also published as: GB201821061D0; GB2580131B

Abstract

A threaded fastener assembly 2 has an axis, and comprises a head 12, a cylindrical section 17 and a threaded section 10. A first fixed outwardly extending support, such as a washer 5 is located between the head 12 and the cylindrical section 17 at a first fixed axial position. A second moveable outwardly extending support, such as a releasable clip 3, is located between the cylindrical section 17 and the threaded section 10 and has a constrained range of axial movement.

Description

THREADED FASTENER ASSEMBLY

[0001] The present application relates to a threaded fastener assembly and a threaded fastener.

Background

[0002] It is often necessary to secure fragile and/or breakable objects to one another and to a supporting structure. For example, when manufacturing electronics assemblies it may be required to secure printed circuit boards (PCBs) to opposite sides of a wall of an enclosure, such as an aluminium wall, and to connect the PCBs together with push fit electrical connectors passing through apertures in the wall. This can conveniently be done by using bolts to secure each PCB to a respective side of the wall. In such an example it may be necessary to subsequently remove one of the PCBs, for example during repair or maintenance of the electronics assembly. However, even after the bolts have been removed from the PCB to be removed it may be difficult to separate the connectors connecting the PCBs, and it may be necessary for the PCB to be pried or levered away from the wall to release the connectors. This can lead to problems of damage to the PCB by the stress and flexing generated in the PCB by the applied forces, which can damage components, electrical connections and solder joints on the PCB, including the solder joints securing the pins of the electrical connectors to the PCB. This can lead to faults on the PCB, and also to foreign object damage to the PCBs and other parts of the electronics assembly caused by fragments, such as solder flakes, released from the PCBs. This can also lead to problems that it can be physically difficult to access the PCBs in order to apply the necessary force.

[0003] It has been proposed to use special fasteners to secure the PCBs to the wall, the special fasteners being arranged to be able to urge the PCBs apart. However, such fasteners have proved unsatisfactory in practice because they are relatively bulky and complex, increasing cost and the space required by the PCBs. Further, such fasteners are generally permanently fixed to the PCBs, preventing re-use of the fasteners and making it difficult to repair the PCBs after removal. Further, such fasteners generally require specialist jigs to be used to fit them, increasing costs and inconvenience, and generally have multiple separable parts, increasing the risk of foreign object damage.

[0004] Jack screws are a known type of bolt having a washer permanently attached, or a removable clip releasably attached, at a fixed position along the length of the bolt.

[0005] The embodiments described below are not limited to implementations which solve any or all of the disadvantages of the known approaches described above.

Summary

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to determine the scope of the claimed subject matter.

[0007] In a first aspect, the present disclosure provides a threaded fastener assembly having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first outwardly extending support located between the head and the at least one cylindrical section and having a first constrained range of axial movement; and a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a second constrained range of axial movement.

[0008] In a second aspect, the present disclosure provides a threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first outwardly extending support located between the head and the at least one cylindrical section and having a first constrained range of axial movement; and a second circumferential groove arranged for cooperation with a releasable clip to form a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a second constrained range of axial movement.

[0009] In a third aspect, the present disclosure provides a threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a circumferential groove arranged for cooperation with a releasable clip to form a first fixed outwardly extending support located between the head and the cylindrical section at a first fixed axial position; and a second moveable outwardly extending support located between the cylindrical section and the threaded section and having a constrained range of axial movement.

[0010] In a fourth aspect, the present disclosure provides a threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first circumferential groove arranged for cooperation with a first releasable clip to form a first fixed outwardly extending support located between the head and the at least one cylindrical section at a first fixed axial position; and a second circumferential groove arranged for cooperation with a second releasable clip to form a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a constrained range of axial movement.

[0011] The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.

Brief Description of the Drawings

[0012] Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which: [0013] Figure 1 is a side view of a threaded fastener used in a threaded fastener assembly according to a first embodiment; [0014] Figure 2a is a side view of a bolt used in the threaded fastener of figure 1; [0015] Figure 2b is an end view of the bolt of figure 2a [0016] Figure 3 is a view of a washer used in the threaded fastener of figure 1; [0017] Figure 4 is a view of a releasable clip used with the threaded fastener of figure 1 to form the threaded fastener assembly according to the first embodiment; [0018] Figures 5A to 5E show stages in the use of the a fastener assembly of the first embodiment to secure a PCB to a wall; [0019] Figures 6A and 6B show stages in the use of the a fastener assembly of the first embodiment to remove a PCB from a wall; [0020] Figures 7A and 7B show stages in the use of the a fastener assembly of the first embodiment to remove a PCB from a wall and to disconnect two PCBs; [0021] Figure 8 is a side view of a threaded fastener assembly according to a second 20 embodiment; [0022] Figure 9 is a side view of a threaded fastener assembly according to a third embodiment; and [0023] Figure 10 is a side view of a threaded fastener assembly according to a fourth embodiment.

[0024] Common reference numerals are used throughout the figures to indicate similar features.

Detailed Description

[0025] Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0026] The threaded fastener assembly 1 according to a first embodiment comprises a threaded fastener 2 and a releasable clip 3. Figure 1 shows a side view of a threaded fastener 2 according to the first embodiment.

[0027] The threaded fastener 2 comprises a bolt 4 with a captive washer 5, and arranged to receive the releasable clip 3. Figures 2A and 2B respectively show a side view and an end view of the bolt 4. Figure 3 shows a plan view of the captive washer 5, and figure 4 shows a plan view of the a releasable clip 3. The bolt 4, the captive washer 5, and the releasable clip 3 are all formed of stainless steel. In some examples one, some, or all of the components of the threaded fastener assembly 1 may be coated, for example to render them inert, or chemically resistant, or electrically insulating, or to modify their properties in some other way, as desired in any particular application.

[0028] In the illustrated embodiment, the threaded fastener 2 comprises a bolt 4. However, this is not essential, and in other examples different types of threaded fastener 1 may be used.

[0029] As shown in figures 2A and 2B, the bolt 4 has a central axis 20, and has a head 12 at a first end lla and a threaded section 10 at a second end llb opposite the first end 11a. As shown best in figure 2B, the head 12 has a hexagonal driving socket 13 recessed into an end face 14 of the head 10 at the first end 11a. The hexagonal driving socket 13 is arranged to receive and engage with a matching hexagonal driver (not shown) in a conventional manner, to allow the bolt 4 to be rotationally driven using the driver to engage or release the bolt 4 with a matching threaded aperture.

[0030] In the illustrated embodiment the bolt 4 has a hexagonal recessed driving socket. This is not essential. In other examples different driving arrangements may be provided. For example, the bolt 4 may have a recessed driving socket having a different number of faces or shape, or may have a driving slot or cross to receive a screwdriver tip, or may have external driving surfaces, such as a hexagonal head, for cooperation with a spanner.

[0031] As explained above, the threaded fastener 2 comprises a captive washer 5. The arrangement of the threaded fastener 2 and captive washer 3 may, for example, be of the type referred to as a screw with pre-assembled washer (SEMS). To secure the captive washers, the bolt 4 of the threaded fastener 2 has a necked section 15 adjacent the head 12 at the first end lla of the bolt 4. The necked section 15 comprises a first tapered region 15a located adjacent to the head 12 and tapered with a diameter reducing along the axis 20 of the bolt 4 in a direction towards the second end llb of the bolt 4. The necked section 15 further comprises a second tapered region 15b located towards the second end 11b of the bolt 4 from the first tapered region 15a, and tapered with a diameter increasing along the axis 20 of the bolt 4 in a direction towards the second end 11b of the bolt 4. Finally, the necked section 15 further comprises a central region 15c located between the first and second tapered regions 15a and 15b, and having a constant diameter. Accordingly, the first tapered region 15a has a maximum diameter at an end adjacent the head 12, and a minimum diameter at an end adjacent the central region 15c, while the second tapered region 15b has a minimum diameter at an end adjacent the central region 15c and a maximum diameter at an end remote the central region 15c. The central region 15c has a constant diameter which is the same as the minimum diameters of the first and second tapered regions 15a and 15b.

[0032] As shown in figure 3, the washer 5 is a flat circular washer having a central hole 16 with a diameter slightly larger than the diameter of the central region 15c of the necked section 15 of the bolt 4, and smaller than the respective maximum diameters of the first and second tapered region 15a and 15b of the bolt 4, so that the washer 5 is free to rotate relative to the bolt 4, and is retained on the bolt 4 at a fixed axial position between the first and second tapered regions 15a and 15b as a captive washer 5. Accordingly, the washer 5 forms a fixed first outwardly extending support located between the head 12 and the cylindrical section 17 at a first fixed axial position.

[0033] In the illustrated embodiment the first tapered region 15a has a maximum diameter larger than the maximum diameter of the second tapered region 15b. This is not essential.

There is no specific required relationship between the maximum diameters of the first and second tapered regions 15a and 15b, and these maximum diameters may be selected as desired.

[0034] In other examples, the bolt 4 and the vvasher 5 may be arranged to use other washer capture techniques and/or geometries to retain the washer 5 as a captive washer on the bolt 4.

[0035] The bolt 4 further comprises a cylindrical section 17 having a constant diameter extending from the second tapered region 15b of the necked section 15 towards the threaded section 10. The cylindrical section 17 has a diameter which is the same as the maximum diameter of the second tapered region 15b of the necked section 15.

[0036] The bolt 4 further comprises a circumferential groove 18 located between the cylindrical section 17 and the threaded section 10. The groove 18 has a smaller diameter than each of the cylindrical section 17 and the threaded section 10, so that the groove 18 is defined between first and second side surfaces 18a and 18b. The first side surface 18a is formed by an end of the cylindrical section 17, and the second side surface 18b is formed by an end of the threaded section 10. The groove 18 and the releasable clip 3 are sized and arranged to cooperate with one another so that the releasable clip 3 can be releasably retained in the groove 18 of the bolt 4 with the releasable clip 3 having a range of movement along the axis 20 of the bolt 4 constrained by the first and second side surfaces 18a and 18b of the groove 18.

[0037] As shown in figure 4, the releasable clip 3 is an e-clip. The releasable clip 3 comprises a part circular annulus 21 broken by a radial gap 22, and three arms 23a to and 23c extending radially inwardly from the circular annulus 21. The three arms 23a to 23c are arranged with the first and second arms 23a and 23b located on either side of the gap 22, and the third arm 23c located diametrically opposite the gap 22. The dimensions of the releasable clip 3 are arranged for cooperation with the bolt 4 so that the releasable clip 3 can be releasably retained in the groove 18 of the bolt 4 with a circumferential surface of the groove 18 of the bolt 4 located between inner ends of the three arms 23a to 23c. The gap 22 of the releasable clip 3 is narrower than a diameter of the groove 18 of the bolt 4, and a substantially circular space defined between the radially inner ends of the three arms 23a to 23c of the releasable clip 3 is smaller than diameters of the cylindrical section 17 and the threaded section 10 of the bolt 4. Accordingly, when the releasable clip 3 is not deformed, the releasable clip 3 cannot be attached to or released from the groove 18 of the bolt 4. The releasable clip 3 can be deformed using a suitable tool in order to widen the gap 22 to enable the groove 18 of the bolt 4 to pass through the gap 22 so that the releasable clip 3 can be attached to, or released from, the threaded fastener 2. E-clips, and the necessary tools and techniques to use them, are well known to the skilled person, and so the precise shapes, dimensions and materials used for the releasable clip 3 do not need to be described in detail herein.

[0038] In the illustrated embodiment the releasable clip 3 is an e-clip. This is not essential. In other examples different forms of releasable clip may be used, for example a circlip.

[0039] The width of the groove 18 of the bolt 4, that is, the distance X between a first side surface 18a of the groove 18 and a second side surface 18b of the groove 18, is greater than a thickness of the releasable clip 3. This allows the releasable clip 3 to move within the groove 18 axially along the threaded fastener 2. Accordingly, the releasable clip 3, when attached, forms a moveable second outwardly extending support located between the cylindrical section 17 and the threaded section 10, and having a range of axial movement constrained by the first side surface 18a and the second side surface 18b of the groove 18.

[0040] As is set out above, the groove 18 of the bolt 4 has a smaller diameter than the of the cylindrical section 17 and the threaded section 10, and the first side surface 18a of the groove 18 is formed by an end of the cylindrical section 17, and the second side surface 18b of the groove 18 is formed by an end of the threaded section 10. At least the second side surface 18b of the groove 18 comprises a substantially smooth surface.

[0041] Figures 5A to 5E show a first illustrative example of the use of the threaded fastener assembly 1 according to the first embodiment. In the illustrated example of figures 5A to 5D the threaded fastener assembly 1 is used to attach a printed circuit board (PCB) 30 to a metal wall 31. The metal wall 31 may be an aluminium wall forming a part of an electronics housing. In the figures 5A to 5E the PCB 30 and the metal wall 31 are shown cut away so that the threaded fastener assembly 1 is visible.

[0042] As illustrated in figure 5A, the threaded fastener 2, without the releasable clip 3, is passed through a hole 32 in the PCB 30. The dimensions of the threaded fastener 2 are selected based on the thickness of the PCB 30 and the diameter of the hole 32. The dimensions of the threaded fastener 2 are selected so that the outer diameters of the threaded section 10 and the cylindrical section 17 of the bolt 4 are slightly smaller than the diameter of the hole 32 in the PCB 30, so that the threaded fastener 2 can pass through the hole 32, and the outer diameter of the captive washer 5 is larger than the diameter of the hole 32 so that the threaded fastener assembly 1 cannot pass entirely through the hole 32. It will be understood that as a result, movement of the PCB 30 transverse to the axis 20 of the bolt 4 is substantially prevented.

[0043] The dimensions of the threaded fastener 2 are further selected based on the thickness of the PCB 30 which the threaded fastener 2 is intended to secure. Specifically, a distance Y between the captive washer 5 and the first side surface 18a of the groove 18 is selected to be less than the expected minimum thickness of the PCB 30. It will be understood that in practice the thickness of the PCB 30 will fall within a range having a minimum value and a maximum value. The thickness of the PCB 30 may, for example, be defined as a nominal thickness and a tolerated variation from the nominal thickness, the limits of this tolerated variation defining the minimum and maximum thickness values of the PCB 30. In some preferred examples the distance Y may be only slightly less than the expected minimum thickness of the PCB 30.

[0044] The distance Y is the minimum distance between first fixed outwardly extending support formed by the captive washer 5 and the second moveable outwardly extending support formed by the releasable clip 3. Accordingly, the minimum distance between first fixed outwardly extending support and the second moveable outwardly extending support is less than the expected minimum thickness of the PCB 30.

[0045] As explained above, the distance X between the first and second side surfaces 18a and 18b of the groove 18 of the bolt 4 is greater than a thickness of the releasable clip 3.

More specifically, the distance X between the first and second side surfaces 18a and 18b of the groove 18 of the bolt 4 is selected to be equal to or greater than the sum of the thickness of the releasable clip 3 and the tolerated variation in the thickness of the PCB 30. The tolerated variation in the thickness of the PCB 30 is the difference between the minimum value and maximum value of the thickness of the PCB 30.

[0046] Accordingly, the range of axial movement of the releasable clip 3, and thus of the moveable second outwardly extending support formed by the releasable clip 3, is equal to or greater than the tolerated variation in the thickness of the PCB 30. In some examples this range of axial movement is substantially equal to the tolerated variation in the thickness of the PCB 30.

[0047] For cooperation with typical PCBs the distance X may be 0.9 mm and the distance Y may be 1.7 mm. The use of these dimensions is not essential. As is explained herein, the dimensions X and Y are dependent, at least in part, on the nominal thickness and permissible variations in thickness of the object, in the illustrated example referred to above a PCB, which the threaded fastener assembly is intended to be used with.

[0048] When the threaded fastener 2 is in the hole 32 in the PCB 30 and the captive washer 5 is in contact with a first face 30a of the PCB 30, at least a part of the groove 18 projects beyond an opposite second face 30b of the PCB 30, as shown in figure 5A. This projecting part of the groove 18 of the bolt 4 provides the necessary clearance to allow the releasable clip 3 to be attached to the groove 18.

[0049] As illustrated in figure 5B, the releasable clip 3 is then attached to the threaded fastener 2, so that the releasable clip 3 is retained in the groove 18 of the bolt 4. When the releasable clip 3 is attached to the threaded fastener 2, the threaded fastener assembly 1 is retained on the PCB 30, because both the captive washer 5 and the releasable clip 3 have a greater diameter than the hole 32 in the PCB 30, so that they cannot pass through the hole 32 and release the threaded fastener assembly 1 from the PCB 30. Further, when the releasable clip 3 is attached to the threaded fastener 2 the releasable clip 3 provides a radially outwardly extending support structure having constrained axial movement. That is, a constrained range of movement in the direction of the axis 20 along the bolt 4. As is explained above, the axial movement of the releasable clip 3 is constrained by the first and second side surfaces 18a and 18b of the groove 18.

[0050] As illustrated in figure 5C, the PCB 30 is then placed adjacent the metal wall 31 and the threaded section 10 of the bolt 4 of the threaded fastener 2 is screwed into a threaded bore 33 in the metal wall 31. As the bolt 4 is screwed into the threaded bore 33, the captive washer Swill contact the first face 30a of the PCB 30 and urge the PCB 30 towards the wall 31. The bolt 4 and captive washer 5 are arranged to allow mutually rotation about the axis 20 of the bolt 4, so that the captive washer 5 not driven to rotate against the first face 30a of the PCB 30 which could potentially cause damage to the PCB 30.

[0051] As the bolt 4 is screwed further into the threaded bore 33, the releasable clip 3 will contact the wall 31, as illustrated in figure 5D. After the releasable clip 3 contacts the wall 31, the bolt 4 can still move axially through the releasable clip 3, as allowed by the distance X between the first and second side surfaces 18a and 18b of the groove 18 being greater than the thickness of the releasable clip 3. Accordingly, bolt 4, and in particular the threaded section 10, can be screwed further into the threaded bore 33, causing the bolt 4 to move axially through the releasable clip 3, and the captive washer 5 to urge the PCB 30 closer to the wall 31.

[0052] As the bolt 4 of the threaded fastener 2 is screwed further into the threaded bore 33 and tightened, the PCB 30 is compressed and gripped between the captive washer 5 and the releasable clip 3, so that the threaded fastening assembly 1 secures the PCB 30 in position against the wall 31, as shown in figure 5E. The releasable clip 3 is located between the PCB 30 and the wall 31, but it will be understood that because the releasable clip 3 can move axially relative to the bolt 4 within the groove 18 the releasable clip 3 does not interfere with compressive forces generated between the captive washer 5 and the wall 31, and acting through the releasable clip 3, which compress and grip the PCB 30.

[0053] As is explained above, the distance Y between the captive washer 5 and the first side surface 18a of the groove 18 is less than the expected minimum thickness of the PCB 30. That is, the minimum thickness which the PCB 30 can have, taking into account both the nominal thickness and allowed variance in thickness of the PCB 30. Accordingly, when the bolt 4 of the threaded fastener 2 is screwed into the threaded bore 33 the PCB 30 can be compressed and gripped between the captive washer 5 and the wall 31, and it is not possible for the necessary compressing movement of the releasable clip 3 axially along the bolt 4 to be stopped by contact with the first side surface 18a of the groove 18 before the PCB 30 is compressed and gripped with a desired compressive force. It will be understood that if such contact did occur the PCB 30 could, in theory, be left loose to move back and forth axially along the bolt 4.

[0054] Further, in order to enable the threaded fastening assembly 1 to secure the PCB 30 to the wall 31 the relative dimensions of the threaded fastener 2 and the threaded bore 33 are arranged so that, as the threaded fastener 2 is screwed into the threaded bore 33 the PCB 30 is compressed and gripped to a desired degree between the captive washer 5 and the PCB 30 through the releasable clip 3 before the first end lla of the threaded section 10 of the bolt 4 contacts the base of the threaded bore 33 and 'bottoms out', preventing further rotation of the bolt 4 and further compression of the PCB 30.

[0055] In some examples the relative dimensions of the threaded fastener 2 and the threaded bore 33 are arranged so that the threaded section 10 of the bolt 4 contacts the base of the threaded bore 33 when a desired degree of compression of the PCB 30 has been applied, preventing further rotation of the bolt 4 and over-compression of the PCB 30. It will be understood that the actual degree of compression of the PCB 30 and the compressive force applied will depend upon the thickness of the PCB 30. Accordingly, the desired degree of compression may, for example, be regarded as a range corresponding to the possible variance in thickness of the PCB 30, or as a maximum value corresponding to the PCB 30 having the maximum expected thickness, that is, the maximum thickness which the PCB 30 can have, taking into account both the nominal thickness and allowed variance in thickness of the PCB 30.

[0056] Figures 6A and 6B show a second illustrative example of the use of the threaded fastener assembly 1 according to the first embodiment. In the illustrated example of figures 6A and 6B the threaded fastener assembly 1 is used to remove the PCB 30 from the metal wall 31. In the figures 6A and 6B the PCB 30 and the metal wall 31 are shown cut away so that the threaded fastener assembly 1 is visible [0057] The threaded fastener assembly 1 and PCB 30 begin in a secured condition as shown in figure 5E, where the PCB 30 is compressed and gripped between the captive washer 5 and the wall 31, so that the threaded fastening assembly 1 secures the PCB 30 to the wall 31.

[0058] In order to release the PCB 30, the bolt 4 of the threaded fastener 2 is unscrewed so that the threaded section 10 of the bolt 4 begins to move out of the threaded bore 33. As the bolt 4 moves out of the threaded bore 33, the bolt 4 moves axially through the releasable clip 3 and the PCB 30, releasing the compression and gripping of the PCB 30. As the bolt 4 is unscrewed the second face 5b of the captive washer 5 separates from the first face 30a of the PCB 30, until the second surface 18b of the groove 18 contacts the releasable clip 3, as shown in figure 6A.

[0059] As the bolt 4 is further unscrewed, the threaded section 11 of the bolt 4 continues to move out of the threaded bore 33, so that the second side surface 18b of the groove 18 of the bolt 4 moves away from the wall 31. Accordingly, the releasable clip 3 is urged by the second side surface 18b of the groove 18 away from the wall 31 and against the second face 30b of the PCB 30, applying a force to the PCB 30 which urges the PCB 30 away from the wall 31, as shown in figure 68. In effect, as the bolt 4 is unscrewed the second side surface 18b of the groove 18 and the releasable clip 3 cooperate to urge the PCB 30 away from the wall 31. This urging may conveniently be regarded as a lifting or jacking force.

[0060] The urging, lifting or jacking force applied to the PCB 30 by the threaded fastener assembly 1 as the bolt 4 is unscrewed may also be used to disconnect push fit electrical connectors linking the PCB 30 to other components, for example other PCBs, as will be discussed in more detail below.

[0061] As discussed above, the second side surface 18b of the groove comprises a substantially smooth surface. This enables smooth rotation of the threaded fastener 2 relative to the releasable clip 4, so that the releasable clip 3 is not driven to rotate against the second face 30b of the PCB 30, which could potentially cause damage to the PCB 30.

[0062] As the bolt 4 is further unscrewed, the threaded section 11 of the bolt 4 is released from the threaded bore 33, so that the threaded fastener assembly 1 and the PCB 30 are released from the wall 31, returning to the configuration shown in figure 5B. After the threaded fastener assembly 1 and the PCB 30 are released from the wall 31, the threaded fastener assembly 1 is retained on the PCB 30, because both the captive washer 5 and the releasable clip 3 have a greater diameter than the hole 32 in the PCB 30, so that they cannot pass through the hole 32 and release the threaded fastener assembly 1 from the PCB 30. If it is desired to remove the threaded fastener assembly 1 from the PCB 30 it will be necessary to remove the releasable clip 3 from the groove 18 of the bolt 4 so that the threaded fastener 2 can be withdrawn from the hole 32 in the PCB 30.

[0063] As is clear from the above description, all parts of the threaded fastener assembly 1 are retained to the PCB 30 throughout the processes of attaching the PCB 30 to the wall and removing the PCB 30 from the wall 31. This may simplify use of the threaded fastener assembly 1 by preventing the loss of components during attachment and removal of PCBs. Further, the risk of foreign object damage (FoD) to the PCB 30 or other components by inadvertently dropped or misplaced parts of the threaded fastener assembly 1 may be reduced.

[0064] Further, as is clear from the above description, after the PCB 30 is removed from the wall 31, the releasable clip 3 can be detached from the groove 18 of the bolt 4, and the threaded fastener 2 can be removed from the hole 32 in the PCB 30. Accordingly, all parts of the threaded fastener assembly 1 can be removed from the PCB 30. This capacity to remove all parts of the threaded fastener may avoid problems when the PCB 30 is to be repaired or worked on by a process which could be impacted by the presence of additional components on the PCB, for example a wave soldering process.

[0065] Further, as is clear from the above description, all parts of the threaded fastener assembly 1 can be removed from the PCB 30 and are then available for re-use. This may reduce costs and minimise waste and environmental impact.

[0066] In the illustrated examples set out above only a single threaded fastener assembly 1 is shown. It will be understood that in practice multiple threaded fastener assemblies 1 may be used to secure a single PCB.

[0067] Figures 7A and 7B show a third illustrative example of the use of the threaded fastener assembly 1 according to the first embodiment. In the illustrated example of figures 7A and 7B the threaded fastener assembly 1 is used to simultaneously disconnect a first PCB 40 from a second PCB 41 and to remove the first PCB 40 from a metal wall 42. In the figures 7A and 7B the first and second PCBs 40 and 41 and the metal wall 42 are shown cut away so that the threaded fastener assembly 1 is visible.

[0068] As shown in figure 7A, the first PCB 40 is secured to a first side of the metal wall 42 by a first threaded fastener assembly 43 received in a first threaded bore 44 in the metal wall 42. The second PCB 41 is secured to a second side of the metal wall 42 opposite to the first side by a second threaded fastener assembly 45 received in a second threaded bore 46 in the metal wall 42. The first and second fastener assemblies 43 and 45 are each examples of the threaded fastener assembly 1 as discussed above.

[0069] The first PCB 40 and the second PCB 41 are electrically connected by a plurality of electrical contacts 47 which are attached to the first PCB 40. The electrical contacts 47 extend through an aperture 48 in the metal wall 42 and are retained in a plurality of sockets 49 attached to the second PCB 41. The In some examples the sockets 49 may be spring loaded sockets which grip the contacts 47 to ensure good and reliable electrical contact. In general, a significant applied force is required to remove the electrical contacts 47 from the sockets 49.

[0070] When the first PCB 40 is to be removed from the metal wall 42, for example to allow replacement or repair of the first PCB 40, the first threaded fastener assembly 43 is unscrewed from the first threaded bore 44 in the metal wall 42.

[0071] As the first threaded fastener assembly 43 is unscrewed the releasable clip 3 of the first threaded fastener assembly 43 contacts and applies a force to the first PCB 40, as shown in figure 7B. This applied force urges the first PCB 40 away from the wall 42, in the manner discussed above with reference to figures 6A and 6B, so that the first threaded fastener assembly 43 urges, lifts, or jacks, the first PCB 40 away from the wall 42. In addition to moving the first PCB 40 away from the wall 42, the force applied to the first PCB 40 by the first threaded fastener assembly 43 also urges the electrical contacts 47 from the sockets 49, as shown in figure 7B.

[0072] Accordingly, the use of a threaded fastener assembly as described above enables a controlled force to be applied to a PCB to separate electrical connectors linking the PCB to another structure, such as a second PCB, without any risk of the applied forces bending or deforming the PCB sufficiently to cause damage.

[0073] In some examples where multiple threaded fastener assemblies are provided in the same PCB it may be arranged to follow a procedure of unscrewing the different threaded fastener assemblies by predetermined amounts in sequence. This may limit the differences in the amount of movement of the different threaded fastener assemblies as they are unscrewed, and so minimise the amount of bending or deformation of the PCB as a result of the forces applied to the PCB by the different threaded fastener assemblies.

[0074] In the illustrated examples the releasable clip 3 is located between respective flat surfaces of the PCB 30 and the wall 31. Accordingly, when the threaded fastener 2 is fully screwed in and the PCB 30 is compressed and held in place, the PCB 30 will be separated from the wall 31 by a distance corresponding to the thickness of the releasable clip(s) 3. In some examples recesses may be provided in the wall 31 to receive the releasable clip(s) 3 so that the PCB 30 can contact the wall 31. This may provide better thermal contact between the PCB 30 and the wall 31, for example for cooling purposes.

[0075] In the illustrated first embodiment the threaded fastener assembly 1 comprises a releasable clip 3 and a captive washer 5. This is not essential.

[0076] In alternative embodiments the releasable clip could be replaced by a captive washer, and/or the captive washer could be replaced by a releasable clip.

[0077] Figure 8 shows a side view of a threaded fastener assembly 100 according to a second embodiment, located in a hole 31 in a PCB 30. In figure 8 the PCB 30 is shown cut away so that the threaded fastener assembly 100 is visible.

[0078] As shown in figure 8, the threaded fastener assembly 100 comprises a threaded fastener 50, a releasable clip 3, and a second releasable clip 51. The threaded fastener 50 comprises a bolt 52 arranged to receive the releasable clips 3 and 51.

[0079] The bolt 52 is similar to the bolt 4 of the first embodiment, having a central axis 20, a head 12 at a first end 11a, and a threaded section 10 at a second end 11b opposite the first end 11 a.

[0080] The bolt 52 comprises a groove 53 located between the head 12 and a cylindrical section 17 having a greater diameter than the groove 53. The groove 53 is sized to receive the second releasable clip 51 so that the releasable clip 51 is retained at a fixed axial position, and is free to rotate, relative to the bolt 52.

[0081] Accordingly, in the second embodiment the second releasable clip 51, when attached, forms a fixed first outwardly extending support located between the head 12 and the cylindrical section 17 at a first fixed axial position.

[0082] The releasable clip 3 is retained in a groove 18 and, when attached, forms a moveable second outwardly extending support located between the cylindrical section 17 and the threaded section 10, and having a range of axial movement constrained by the first side surface 18a and the second side surface 18b of the groove 18, in the same way as in the first embodiment.

[0083] Accordingly, the threaded fastener assembly 100 according to the second embodiment can be used in the same manner as the threaded fastener assembly according to the first embodiment described above, but with the second releasable clip 51 taking the place of, and providing the functionality of, the captive washer 5.

[0084] Figure 9 shows a side view of a threaded fastener assembly 200 according to a third embodiment, located in a hole 31 in a PCB 30. In figure 9 the PCB 30 is shown cut away so that the threaded fastener assembly 200 is visible.

[0085] As shown in figure 9, the threaded fastener assembly 200 comprises a threaded fastener 60, comprising a bolt 61, a captive washer 5, and a second captive washer 62.

[0086] The bolt 61 is similar to the bolt 4 of the first embodiment, having a central axis 20, a head 12 at a first end 11a, and a threaded section 10 at a second end 11b opposite the first end 11 a.

[0087] The bolt 61 comprises a groove 18 located between the cylindrical section 17 and the threaded section 10. The groove 18 is sized to retain the second captive washer 52, so that the second captive washer 52 is has a range of axial movement constrained by the first side surface 18a and the second side surface 18b of the groove 18, and is free to rotate, relative to the bolt 4.

[0088] Accordingly, in the third embodiment the second captive washer 52 forms a moveable second outwardly extending support located between the cylindrical section 17 and the threaded section 10, and having a range of axial movement constrained by the first side surface 18a and the second side surface 18b of the groove 18. Similarly to the releasable clip 3 of the first embodiment, the range of axial movement of the second captive washer 52, and thus of the moveable second outwardly extending support formed by the second captive washer 52, is equal to or greater than the tolerated variation in the thickness of the PCB 30.

[0089] A captive washer 5 forms a fixed first outwardly extending support located between the head 12 and the cylindrical section 17 at a first fixed axial position, in the same way as in the first embodiment.

[0090] Accordingly, the threaded fastener assembly according to the third embodiment can be used in the same manner as the threaded fastener assembly according to the first embodiment described above, but with the second captive washer 52 taking the place of, and providing the functionality of, the releasable clip 3.

[0091] Figure 10 shows a side view of a threaded fastener assembly 300 according to a fourth embodiment.

[0092] As shown in figure 10, the threaded fastener assembly 300 comprises a threaded fastener 70, a releasable clip 3, and a washer 71. The threaded fastener 70 comprises a bolt 72 arranged to receive the releasable clip 3 and the washer 71.

[0093] The bolt 72 is similar to the bolt 4 of the first embodiment. The bolt 72 has a central axis 20, a head 12 at a first end 11a, and a threaded section 10 at a second end 11b opposite the first end 11a.

[0094] The bolt 72 comprises a groove 73 located between the head 12 and a cylindrical section 17. The groove 73 has a smaller diameter than the diameters of the head 12 and the cylindrical section 17. The groove 73 is sized to receive the washer 71 and a spring element 74 located between the washer 71 and the head 12 of the bolt 72, so that the washer 71 is urged into contact with an end face 17a of the cylindrical section 17 nearer to the first end lla of the bolt 72. Accordingly, the washer 71 is retained at a predetermined axial position, where it is in contact with the end face 17a of the cylindrical section 17, and is free to rotate, relative to the bolt 72. The spring element 74 is a split washer.

[0095] Accordingly, in the fourth embodiment the washer 71, forms a first outwardly extending support located between the head 12 and the cylindrical section 17 at a first constrained axial position. An internal diameter of the washer 71 is smaller than a diameter of the head 12 and the cylindrical section 17, so that the washer 71 is a captive washer.

[0096] The releasable clip 3 is retained in a groove 18 and, when attached, forms a moveable second outwardly extending support located between the cylindrical section 17 and the threaded section 10, and having a range of axial movement constrained by the first side surface 18a and the second side surface 18b of the groove 18, in the same way as in the first embodiment.

[0097] Accordingly, the threaded fastener assembly 300 according to the fourth embodiment can be used in the same manner as the threaded fastener assembly according to the first embodiment described above, but with the washer 71 taking the place of, and providing the functionality of, the captive washer 5.

[0098] In the threaded fastener assembly 300 according to the fourth embodiment the axial position of the washer 71 is constrained. The range of axial movement of the washer 72 is limited in a direction towards the second end 11b of the bolt 72 by the washer contacting the end face 17a of the cylindrical section 17.

[0099] Accordingly, the distance between the washer 72 and the first side surface 18a of the groove 18 has a minimum distance Y. This minimum distance Y is the distance between the end face 17a of the cylindrical section 17 and the first side surface 18a of the groove 18. In the illustrated example this minimum distance is the axial length of the cylindrical portion 17.

[00100] In a similar manner to the first embodiment described above, this minimum distance Y is less than the expected minimum thickness of the PCB. That is, the minimum thickness which the PCB can have, taking into account both the nominal thickness and allowed variance in thickness of the PCB. Accordingly, when the bolt 72 of the threaded fastener 70 is screwed into a threaded bore the PCB can be compressed and gripped between the washer 71 and a wall and it is not possible for the necessary compressing movement of the releasable clip 3 axially along the bolt 72 to be stopped by contact with the first side surface 18a of the groove 18 before the PCB is compressed and gripped with a desired compressive force.

[00101] In use of the threaded fastener assembly 300 of the fourth embodiment, the spring element 74 will yield if subject to forces above a predetermined value by the washer 71 in the direction of the first end 11a of the bolt 72, allowing the washer 71 to move axially along the groove 73 towards the head 12 of the bolt 72. This movement may continue until the spring element 74 is fully compressed between the washer 71 and the head 12.

[00102] The use of a washer 72 having a constrained range of axial movement against a spring element 74 according to the fourth embodiment may be advantageous in situations subject to vibration in order to prevent damage to the secured PCB by vibration forces.

[00103] The use of a washer 72 having a constrained range of axial movement against a spring element 74 according to the fourth embodiment may be used to limit the amount of compressive force applied to the secured PCB by the threaded fastener assembly 300 and/or to limit the amount of torque applied when tightening the bolt 72 of the threaded fastener assembly 300. The yielding of the spring element 74, and the resulting axial movement of the washer 72, will limit the applied compressive force and/or torque, and may provide a visual indication to a user that a desired limit to the applied force and/or torque has been reached.

[00104] In some examples it may be desired to limit the amount of compressive force applied to the secured PCB to prevent damage to the PCB.

[00105] In some examples it may be desired to limit the amount of torque applied. For example, if the bolt 72 is formed of steel and the threaded fastener assembly 300 is screwed into a threaded bore in an aluminium wall it may be desirable to limit the amount of torque applied in order to avoid damaging, or stripping, the aluminium threads within the threaded bore.

[00106] In the illustrated embodiments the wall is a metal wall. This is only by way of example, and walls of other materials may be used.

[00107] In the illustrated embodiments the captive washer(s) are plain washers. In some examples one or more of the captive washer(s) may instead be spring washers.

[00108] In the illustrated embodiments a first outwardly extending support at the head end of the threaded fastener is formed by a captive washer at a fixed position. In alternative examples the captive washer may be able to move [00109] In some examples additional components may be used. For example, in addition to the disclosed captive washer(s) and/or releasable clips additional washers may be used. These additional washers may, for example, be plain washers or spring washers [00110] In the embodiments described above the captive washer(s) and/or releasable clip(s) are arranged to be able to rotate relative to the threaded fastener. This is not essential, and in other examples one, some, or all of the captive washer(s) and/or releasable clip(s) may be rotationally fixed to the threaded fastener. In such examples additional components, for example additional washers, may be used.

[00111] In the illustrated embodiments the disclosed threaded fastener is used to secure a PCB. In some examples, the thickness of the PCB may be in the range 0.9mm to 4.0mm. In other examples the PCB may have other thicknesses.

[00112] In the illustrated embodiments the disclosed threaded fastener assemblies are used to secure a PCB to a wall. This is by way of example only. In other examples the threaded fastener assemblies may be used to secure PCBs, or other fragile and/or breakable components to other supporting structures.

[00113] Further, the disclosed threaded fastener assemblies may be used in other fields than electronics.

[00114] The disclosed threaded fastener assemblies may be used in the field of aeronautics to secure, and lift and remove potentially fragile components, for example to avoid bending or scratching aircraft body panels.

[00115] In the illustrated embodiments the bolt, the captive washer, and the releasable clip of the threaded fastener assembly are all formed of stainless steel. In other examples alternative materials may be used. In some examples one or more of the components of the threaded fastener assembly may be made, wholly or in part, from one or more of: Monel; Inconel; Aluminium; Naval brass; Titanium; Steel; Mild Steel; Spring Steel (such as Elgiloy); and Plastics materials. It will be understood that this list is purely exemplary, and is not intended to be exhaustive.

[00116] The disclosed threaded fastener assemblies may be used in the field of medicine to secure, and to separate and remove potentially fragile implants or medical components, and also to separate and remove medical components from potentially fragile or damageable biological structures, for example bones.

[00117] In medical applications suitable materials for the threaded fastener assemblies may be made from suitable biocompatible materials. Exemplary biocompatible materials include: (1) metals or metal alloys, for example stainless steel, titanium or titanium alloys, alloys with cobalt and chromium, such as cobalt chrome, etc.; (2) plastics/polymers, for example, ultrahigh molecular weight polythylene (UHMVVPE), polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), nylon, polypropylene, polyurethanes, and/or PMMAJpolyhydroxyethylmethacrylate (PHEMA); (3) ceramics, for example alumina, beryllia, and/or zirconia, among others; (4) composites, e.g., a polymer matrix (such as PEEK) containing carbon fibers and/or ceramic, a carbon composite, etc.; (5) bioreasorbable (bioabsorbable) materials or polymers, for example polymers of a-hydroxy carboxylic acid, e.g., polylactic acid (such as PLLA, PDLLA, and/or PDLA), polyglycolic acid, lactide/glycolide copolymers, etc.), polydioaxones, polycaprolacetones, polytrimethylene carbonate, polyethylene oxide, poly-p-hydroxybutyrate, poly-p-hydroxypropionate, poly-6-valeroactone, other biosorbable polyesters, resorbable polyacfic acid (PLA), polyglycolic acid (PGA), etc; (6) combinations or alloys of such materials, or any other appropriate material that has sufficient strength while also having sufficient biocompatibilty to be implanted into a body, and/or the like. The above list is given purely by way of example, and is not intended to be exhaustive.

[00118] The disclosed threaded fastener assemblies may also be used in the fields of space and marine structures [00119] In some examples the disclosed threaded fastener assemblies may be used to secure items having thicknesses up to 80mm, in some examples the disclosed threaded fastener assemblies may be used to secure items having thicknesses in the range 0.9mm to 4.0 mm.

[00120] In some examples one, some, or all components of the threaded fastener assembly may have a coating. In such examples different components may have the same coating or different coatings.

[00121] The examples of possible uses set out above are not intended to be exhaustive.

[00122] In the embodiments described above the threaded fastener has a cylindrical section located between the first and second outwardly extending supports. For example, between the necked section 15 and the groove 18 in the first embodiment. This is not essential. In some examples this cylindrical section may comprise two or more cylindrical sections.

[00123] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

[00124] Any reference to 'an' item refers to one or more of those items. The term 'comprising' is used herein to mean including the method steps or elements identified, but that such steps or elements do not comprise an exclusive list and a method or apparatus may contain additional steps or elements.

[00125] Further, as used herein, the term "exemplary" is intended to mean "serving as an illustration or example of something".

[00126] Further, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

[00127] The figures illustrate exemplary methods. While the methods are shown and described as being a series of acts that are performed in a particular sequence, it is to be understood and appreciated that the methods are not limited by the order of the sequence. For example, some acts can occur in a different order than what is described herein. In addition, an act can occur concurrently with another act. Further, in some instances, not all acts may be required to implement a method described herein.

[00128] The order of the steps of the methods described herein is exemplary, but the steps may be carried out in any suitable order, or simultaneously where appropriate. Additionally, steps may be added or substituted in, or individual steps may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[00129] It will be understood that the above description of preferred embodiments is given by way of example only and that various modifications may be made by those skilled in the art. What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable modification and alteration of the above devices or methods for purposes of describing the aforementioned aspects, but one of ordinary skill in the art can recognize that many further modifications and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the scope of the appended claims.

Claims

Claims: 1. A threaded fastener assembly having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first outwardly extending support located between the head and the at least one cylindrical section and having a first constrained range of axial movement; and a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a second constrained range of axial movement.
2. The threaded fastener assembly of claim 1, wherein the first outwardly extending support is a first fixed outwardly extending support having a fixed axial position.
3. The threaded fastener assembly of claim 2, wherein the first fixed outwardly extending support comprises a captive washer.
4. The threaded fastener assembly of claim 2, wherein the first fixed outwardly extending support comprises a releasable clip.
5. The threaded fastener assembly of claim 1, wherein the first outwardly extending support comprises a washer retained in a first circumferential groove located between the head and the at least one cylindrical section, the first groove having a smaller diameter than a diameter of the head and a diameter of the at least one cylindrical section.
6. The threaded fastener assembly of claim 5, wherein the first groove is defined between a side surface formed by an end of the at least one cylindrical section and the head.
7. The threaded fastener assembly of claim 5 or claim 6, further comprising a spring element located between the washer and the head and arranged to urge the washer against the side surface.
8. The threaded fastener assembly of claim 7, wherein the spring element is a split washer.
9. The threaded fastener assembly of any one of claims 1 to 8, wherein the second moveable outwardly extending support comprises a releasable clip retained in a second circumferential groove located between the at least one cylindrical section and the threaded section, the second groove having a smaller diameter than a diameter of the at least one cylindrical section and a diameter of the threaded section.
10. The threaded fastener assembly of claim 9, wherein the second groove is defined between a first side surface formed by an end of the at least one cylindrical section and a second side surface formed by an end of the threaded section.
11. The threaded fastener assembly of claim 10, wherein the range of axial movement of the second moveable outwardly extending support is limited by the releasable clip contacting the first and second side surfaces.
12. The threaded fastener assembly of any one of claims 1 to 8, wherein the second moveable outwardly extending support comprises a captive washer retained in a groove located between the at least one cylindrical section and the threaded section, the groove having a smaller diameter than a diameter of the at least one cylindrical section and a diameter of the threaded section.
13. The threaded fastener assembly of claim 12, wherein the groove is defined between a first side surface formed by an end of the at least one cylindrical section and a second side surface formed by an end of the threaded section.
14. The threaded fastener assembly of claim 13, wherein the range of axial movement of the second moveable outwardly extending support is limited by the captive washer contacting the first and second side surfaces.
15. The threaded fastener assembly according to any one of the preceding claims, wherein: the threaded fastener assembly is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; 30 and the range of axial movement of the second moveable outwardly extending support is equal to or greater than the difference between the maximum thickness and the minimum thickness of the object.
16. The threaded fastener assembly according to any one of the preceding claims, wherein: the threaded fastener assembly is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the ranges of axial movement of the first and second outwardly extending supports is constrained so that the minimum distance between the first outwardly extending support and the second outwardly extending support is less than the minimum thickness of the object.
17. The threaded fastener assembly according to claim 15 or claim 16, wherein the object is a printed circuit board 'PCB'.
18. The threaded fastener assembly according to any preceding claim wherein the threaded fastener assembly comprises a bolt, and the bolt comprises the head, the at least one cylindrical section, and the threaded section.
19. A threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first outwardly extending support located between the head and the at least one cylindrical section and having a first constrained range of axial movement; and a second circumferential groove arranged for cooperation with a releasable clip to form a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a second constrained range of axial movement.
20. The threaded fastener of claim 19, wherein the first outwardly extending support is a first fixed outwardly extending support having a fixed axial position.
21. The threaded fastener of claim 20, wherein the first fixed outwardly extending support comprises a captive washer.
22. The threaded fastener of claim 19, wherein the first outwardly extending support comprises a washer retained in a first circumferential groove located between the head and the at least one cylindrical section, the first groove having a smaller diameter than a diameter of the head and a diameter of the at least one cylindrical section.
23. The threaded fastener of claim 22, wherein the first groove is defined between a side surface formed by an end of the at least one cylindrical section and the head.
24. The threaded fastener of claim 22 or claim 23, further comprising a spring element located between the washer and the head and arranged to urge the washer against the side surface.
25. The threaded fastener assembly of claim 24, wherein the spring element is a split washer.
26. The threaded fastener of any of claims 19 to 25, wherein the second groove has a smaller diameter than a diameter of the cylindrical section and a diameter of the threaded section, and the second groove is defined between a first side surface formed by an end of the at least one cylindrical section and a second side surface formed by an end of the threaded section.
27. The threaded fastener according to claim 26, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the first side surface and the second side surface are separated by a distance equal to or greater than the difference between the maximum thickness and the minimum thickness of the object.
28. The threaded fastener according to any one of claims 19 to 27, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the ranges of axial movement of the first and second outwardly extending supports is constrained so that the minimum distance between the first outwardly extending support and the second outwardly extending support is less than the minimum thickness of the object.
29. The threaded fastener according to claim 27 or claim 28, wherein the object is a printed circuit board 'PCB'.
30. The threaded fastener according to any one of claims 19 to 29, wherein the threaded fastener assembly comprises a bolt, and the bolt comprises the head, the cylindrical section, the threaded section, and the circumferential groove.
31. A threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a circumferential groove arranged for cooperation with a releasable clip to form a first fixed outwardly extending support located between the head and the cylindrical section at a first fixed axial position; and a second moveable outwardly extending support located between the cylindrical section and the threaded section and having a constrained range of axial movement.
32. The threaded fastener of claim 31, wherein the second moveable outwardly extending support comprises a captive washer retained in a groove located between the t least one cylindrical section and the threaded section, the groove having a smaller diameter than a diameter of the at least one cylindrical section and a diameter of the threaded section.
33. The threaded fastener of claim 32, wherein the groove is defined between a first side surface formed by an end of the at least one cylindrical section and a second side surface formed by an end of the threaded section.
34. The threaded fastener of claim 33, wherein the range of axial movement of the second moveable outwardly extending support is limited by the captive washer contacting the first and second side surfaces.
35. The threaded fastener according to any one of claims 31 to 34, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the range of axial movement of the second moveable outwardly extending support is equal to or greater than the difference between the maximum thickness and the minimum thickness of the object.
36. The threaded fastener according to any one of claims 31 to 35, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the range of axial movement of the second moveable outwardly extending support is constrained so that the minimum distance between first fixed outwardly extending support and the second moveable outwardly extending support is less than the minimum thickness of the 35 object.
37. The threaded fastener according to claim 35 or claim 36, wherein the object is a printed circuit board 'PCB'.
38. The threaded fastener according to any one of claims 31 to 377 wherein the threaded fastener assembly comprises a bolt, and the bolt comprises the head, the cylindrical section, the threaded section, and the circumferential groove.
39. A threaded fastener having an axis and comprising: a head; at least one cylindrical section; a threaded section; and a first circumferential groove arranged for cooperation with a first releasable clip to form a first fixed outwardly extending support located between the head and the at least one cylindrical section at a first fixed axial position; and a second circumferential groove arranged for cooperation with a second releasable clip to form a second moveable outwardly extending support located between the at least one cylindrical section and the threaded section and having a constrained range of axial movement.
40. The threaded fastener according to claim 39, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the range of axial movement of the second moveable outwardly extending support is equal to or greater than the difference between the maximum thickness and the minimum thickness of the object.
41. The threaded fastener according to claim 39 or claim 40, wherein: the threaded fastener is arranged for cooperation with an object having a thickness falling in a defined range having a maximum thickness and a minimum thickness; and the range of axial movement of the second moveable outwardly extending support is constrained so that the minimum distance between first fixed outwardly extending support and the second moveable outwardly extending support is less than the minimum thickness of the object.
42. The threaded fastener according to claim 40 or claim 41, wherein the object is a printed circuit board 'PCB'.
43. The threaded fastener according to any one of claims 39 to 42 wherein the threaded fastener assembly comprises a bolt, and the bolt comprises the head, the cylindrical section, and the threaded section, and the first an second circumferential grooves.