A blind fastening device

Abstract

A blind fastening device (13) for use in clamping a component to a support plate by positioning said fastening device (13) through aligned openings in the component and in the support plate. The fastening device (13) comprises a slotted sleeve (20), an apertured sleeve plate (16), a fastener (14) comprising a threaded fastener portion which can be taken through the slotted sleeve (20), the apertured sleeve plate (16) and the apertured compression means. The fastener (14) further comprises a tightening head (15) for tightening the fastener (14). A washer (38) is positioned between the tightening head (15) and the sleeve plate (16), and a diverging sleeve expanding head (23) mounted on the fastener portion and engageable with the end of the sleeve (20) on tightening of the fastener (14), in order to expand said end rigidly outwards into contact with at least one of said openings to anchor the sleeve (20).

Description

[0001] P608720PC00

[0002] 1

[0003] A Blind Fastening Device

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to a blind fastening device. More particularly, but not exclusively, the present invention relates to a blind fastening device for clamping a component to a support plate.

[0006] BACKGROUND OF THE INVENTION

[0007] Rolled hollow metal sections are increasingly being used as part of the supporting structure in industrial buildings. Such sections are typically manufactured in the form of hollow rectangular or hollow square support columns built up from four metal plate sections. When it is desired to secure fixing brackets, pipe supports, electrical conduits or other similar components to such support columns it is necessary to use a blind fastening device since access cannot readily be obtained to the interior of the column to complete the fastening operation.

[0008] A typical known blind fastening device comprises a threaded bolt having a bolt head extending from one end. A conical expansion head is threaded partly along the length of the bolt. Also threaded along the bolt and abuting against the bolt head is an apertured sleeve plate. Finally, extending between the sleeve plate and the expansion head is a slotted tubular sleeve.

[0009] Before use the expansion head is threaded along the bolt until it abuts against the sleeve. The friction between the sleeve and the expansion head then prevents the expansion head from turning when the bolt is rotated within the sleeve.

[0010] In order to fasten a component to a support plate, an aperture in the component is firstly aligned with a corresponding aperture in the plate. The bolt and the sleeve of the fastening device are then inserted through the aligned apertures until the sleeve plate abuts against the component. The bolt is then tightened. Because the friction between the conical head and the sleeve prevents the conical head from rotating along with the bolt, the tightening of the bolt causes the conical head to be drawn along the bolt towards the bolt head. This forces the slotted sleeve to expand radially outwards. Eventually, the portion of the sleeve in contact with the head grips the outer wall of the aperture of the support plate. In P608720PC00

[0011] 2 this way the component and the support plate become gripped between the sleeve plate and the expanded end of the sleeve.

[0012] Further tightening of the bolt applies a compressive force to the portion of the sleeve located between the conical head and the sleeve plate. However, as the sleeve is essentially axially incompressible this tightening does not produce a reduction in the distance between the sleeve plate and the expanded end of the sleeve. Therefore, once the sleeve has gripped the aperture it is not possible to press the component and the support column together by further tightening of the bolt of the blind fastening device.

[0013] This is particularly problematic in scenarios where it is important that the bolt does not "slip", i.e. become loosened or relax over time. This can occur where the compressive forces between the support plates and the sleeve reduce or weaken over time.

[0014] Such blind fastening devices are often difficult to remove once they have been tightened. Even if one removes the bolt and conical expansion head the single piece comprising the support plate and sleeve will still remain in position, gripping the component and support column. In order to remove this piece it is necessary to apply considerable force to the underside of the support plate with a crowbar in order to deform the fingers of the expanded sleeve inwards. This can often damage the aperture and make it unsuitable for re-use.

[0015] SUMMARY OF THE INVENTION

[0016] A first aspect of the present invention provides a blind fastening device for use in clamping a component to a support plate by positioning, said fastening device through aligned openings in the component and in the support plate, the fastening device comprising: a slotted sleeve; an apertured sleeve plate; a fastener comprising a threaded fastener portion which can be taken through the slotted sleeve, the apertured sleeve plate and the apertured compression means; the fastener further comprises a tightening head for tightening the fastener; a washer positioned between the tightening head and the sleeve plate; and a diverging sleeve expanding head mounted on the fastener portion and engageable with the end of the sleeve on tightening of the fastener, in order to expand said P608720PC00

[0017] 3 end rigidly outwards into contact with at least one of said openings to anchor the sleeve.

[0018] Optionally, the entirety of the underside of the tightening head contacts the surface of the washer contacting the tightening head.

[0019] Optionally, the sleeve plate further comprises a recess, wherein the recess is configured to receive the washer.

[0020] Optionally, the depth of the recess is such that the washer is flush with a surface of the sleeve plate facing the tightening head when received within the recess.

[0021] Optionally, the recess has a base and wall surrounding the base wherein the base and / or wall of the recess are untextured.

[0022] Optionally, the washer is made from materials with differing hardness value to the sleeve plate.

[0023] Optionally, the hardness of the washer is higher than the hardness of the sleeve plate.

[0024] Optionally, the washer comprises carbon or stainless steel.

[0025] Optionally, the washer has a minimum Vickers Hardness of 200HV.

[0026] Optionally, the washer is hardened by heat treatment.

[0027] Optionally, the washer is made from materials of differing hardness to the sleeve plate.

[0028] Optionally, the hardness of the washer is higher than the hardness of the sleeve plate.

[0029] Optionally, the device further comprises an apertured compression means located between the slotted sleeve and the sleeve plate, wherein the compression means is remote from the diverging sleeve expanding head, wherein the compression means is adapted such that on further tightening of the fastener, the compression P608720PC00

[0030] 4 means is axially compressed between said sleeve and said sleeve plate so reducing the distance between said sleeve and sleeve plate.

[0031] Optionally, the compression means comprises an elastomeric washer.

[0032] Optionally, wherein on compression of the compression means, the compression means expands outwardly to form a seal between the sleeve plate and the component.

[0033] Optionally, the device further comprises a visual indicator washer located between the sleeve plate and the washer, wherein the visual indicator washer is remote from the diverging sleeve expanding head, and the visual indicator washer is adapted such that on further tightening of the fastener, the visual indicator washer is axially compressed to provide a visual indication that the fastener reaches a threshold pretension.

[0034] Optionally, wherein the visual indicator washer comprises a visual indicator on a top surface of the washer.

[0035] Optionally, wherein the visual indicator washer comprises a visual indicator on a bottom surface of the washer.

[0036] Optionally, wherein the visual indicator comprises a plurality of protrusions on an upper and / or lower surface of the washer, wherein the protrusions are configured to axially compress during tightening.

[0037] Optionally, wherein the plurality of protrusions comprises an elastomer such that, upon reaching the threshold torque, the elastomer extends beyond the fastener head.

[0038] Optionally, wherein said apertured sleeve plate has a formation offset from the axis of the threaded fastener portion which is engageable with a tool to prevent rotation of the sleeve plate while the fastener is being tightened.

[0039] Optionally, wherein the diverging sleeve expanding head is frustoconical. P608720PC00

[0040] 5

[0041] Optionally, the slotted sleeve and sleeve plate are provided as a unitary component.

[0042] A further aspect of the present invention provides a blind fastening device for use in clamping a component to a support plate by positioning said fastening device through aligned openings in the component and in the support plate, the fastening device comprising: a slotted sleeve; an apertured sleeve plate; a fastener comprising a threaded fastener portion which can be taken through the slotted sleeve, the apertured sleeve plate and the apertured compression means; the fastener further comprises a tightening head for tightening the fastener; a washer positioned between the tightening head and the sleeve plate; and a diverging sleeve expanding head mounted on the fastener portion and engageable with the end of the sleeve on tightening of the fastener, in order to expand said end rigidly outwards into contact with at least one of said openings to anchor the sleeve, wherein the slotted sleeve and sleeve plate are provided as a unitary component.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0045] Figure 1 is a longitudinal cross-sectional view of a known blind fastening device;

[0046] Figures 2 (a) to 2 (c) show, in longitudinal cross section, successive stages in the fastening of a component to a support plate using a known blind fastening device;

[0047] Figure 3A is a longitudinal cross sectional view of a blind fastening device according to the invention;

[0048] Figure 3B is an exploded view of a blind fastening device shown in Figure 3A;

[0049] Figure 3C shows an exploded view of a blind fastening device according to another embodiment of the invention;

[0050] Figures 4(a) to 4(d) show, in longitudinal cross section, successive stages in the fastening of a component to a support plate using a blind fastener device according to the invention.

[0051] Figure 5 shows another exemplary blind fastening device; P608720PC00

[0052] 6

[0053] Figures 6A and 6B show exemplary visual indication means that can be used with a blind fastening device. Figure 6C shows another exemplary visual indication means that can be used with a blind fastening device.

[0054] DETAILED DESCRIPTION OF EMBODIMENT(S)

[0055] Shown in figure 1 is a known blind fastening device 1 comprising a tubular sleeve 2 and a threaded bolt 3. The tubular sleeve 2 comprises an apertured sleeve head 4, a slotted expansion portion 5 and a neck portion 6 extending therebetween. The expansion portion 5 comprises a number of parallel arcuate fingers separated axially by slots.

[0056] Before use, the threaded bolt 1 is inserted axially along the tubular sleeve 3 until the head 7 of the bolt 3 abuts against the sleeve head 4 and a portion of the bolt remote from the head extends beyond the sleeve. A frustoconical expansion head 8 having an engagement face 9 and a base 10 is then threaded along the bolt until it abuts against the sleeve. The diameter of the engagement face 9 is less than the diameter of the tubular sleeve 2 whilst the diameter of the base 10 is greater than the diameter of this tubular sleeve 2. Further tightening of the expansion head by hand is prevented by the friction between the sleeve 2 and the expansion head 8.

[0057] To use this blind fastening device 1 to clamp together a fixing plate 11 and a support plate 12, an aperture in the fixing plate 11 is firstly aligned with a corresponding aperture in the support plate 12. The blind fastening device 1 is then slid through these apertures until the sleeve head 4 abuts against the aperture surround as shown in figure 2(a).

[0058] A gripping tool is attached to the sleeve head 4 to prevent its rotation. A tightening tool is then attached to the bolt head 7. This tool is used to rotate the bolt 3 along its length relative to the sleeve 2 to tighten the fastening device. Because the expansion head 8 is not free to rotate along with bolt 3, rotation of the bolt 3 forces the expansion head 8 towards the bolt head 7. This movement of the expansion head 8 causes the fingers 5 of the sleeve 2 to expand radially outwards and into engagement with the walls of the aperture as shown in figure 2(b). P608720PC00

[0059] 7

[0060] As the bolt 3 is tightened further the expansion head 8 is forced further towards the sleeve head 4. However, as the sleeve 2 is now anchored to the aperture this results in a compression of the portion of the sleeve 2 within the aperture. When the compressional force reaches a predetermined level, the sleeve 2 presses and fixes the support plates together as shown in figure 2(c).

[0061] Once such a blind fastening device 1 has been tightened it can be difficult to remove. In order to remove the bolt 3 from the fastening device one rotates the bolt anticlockwise until the expansion head 8 reaches the end of the thread. As the bolt 3 is turned further, the expansion head 8 will drop off the bolt 3 and into the support plate 12. The bolt 3 can then be pulled free from the fastening device. However, even with the bolt 3 removed, the sleeve 2 will remain in place gripping the component 11 and support plate 12. In order to remove this sleeve 2, one must insert a crowbar beneath the sleeve head 4 and use this to recompress the fingers 5 of the expanded portion of the sleeve 2. Once these fingers 5 have been recompressed the sleeve 2 can be axially withdrawn from the aperture.

[0062] Insertion of the crowbar into the aperture can damage the aperture making it unsuitable for future use.

[0063] Shown in figures 3A and 3B are an exemplary fastening devices 13 according to the present invention. Figure 3A shows an assembled version of the fastening device 13 in longitudinal cross section, while Figure 3B shows the fastening device 13 in an exploded view.

[0064] The fastening device 13 comprises a threaded bolt 14 having a bolt head 15 extending from one end. Positioned along the bolt 14 and abutting against the bolt head is an apertured sleeve plate 16. The walls of the aperture 17 of the sleeve plate 16 are smooth enabling the sleeve plate 16 to be slid along the bolt 14. The outer wall of the sleeve plate 16 is substantially circular but has an offset formation 16b for engagement with a gripping tool to prevent rotation of the sleeve 20.

[0065] The sleeve plate 16 comprises a recess 36. As shown, the recess 36 is arranged to receive a washer 38. The washer 38 is positioned between the bolt head 15 of the bolt 14 and the sleeve plate 16. P608720PC00

[0066] 8

[0067] As shown, the recess 36 has a depth DI that extends into the sleeve plate 16. In this example, the depth DI of the recess 36 is such that when the washer 28 is received in the sleeve plate 16, the washer 38 is flush with the surface 16a of the sleeve plate 16 facing the bolt head 15. The depth DI of the recess 36 is therefore substantially the same as the height of the washer 38. In other examples, the recess 36 may have a depth DI that is greater than the height of the washer 38 so that the washer 38 sits behind the upper surface 16a of the sleeve plate 16, or a depth DI that is smaller than the height of the washer 38 so that the washer 38 extends beyond the upper surface 16a from the sleeve plate 16. In all arrangements, the washer 38 provides an improved clamping force of the fastening device 13.

[0068] As shown more clearly in Figure 3B, the recess 36 is circular. The recess 26 has a base 37 and a wall 39 surrounding the base 37. The wall 39 is continuous around the base 37 as the recess is circular. The recess 36 is preferably sized to receive the washer 38 with minimal distance between the wall 39 and the washer 38. This allows the bolt head 15 to effectively transmit forces through the entirety of the washer 38 once the bolt head 15 is tightened (described in more detail below).

[0069] As shown in Figure 3B, the wall 39 or the base 37 of the recess 26 are untextured. The wall 39 or the base 37 of the recess are therefore smooth to enable the washer 38 sit correctly within the recess 36. The smooth surface improves the clamping force provided by the fastening device 13 in comparison to alternative arrangements where the wall 39 or base 37 of the recess is roughened. In other examples, both the wall 39 and the base 37 of the recess 36 may be smooth.

[0070] The washer 38 may be chamfered so as to receive the bolt head 15 more easily, or may not be chamfered. In the example shown in Figures 3A and 3B, the washer 38 is made from a material that has a different hardness value to the sleeve plate 16. Preferably, the washer 38 has a higher hardness value than the sleeve plate 16so that as the bolt head 15 is tightened, the washer 38 resists the compressive forces applied by the bolt head 15, thereby creating a greater clamping force between the bolt head 15 and the sleeve plate 16, and between the fixing plate 11 and the support plate 12. The washer 38 may also have a higher hardness than the base 25. This reduces the "slip" of the bolt head 15, i.e. the likelihood of the bolt head 15 becoming loosened over time. The washer 38 P608720PC00

[0071] 9 therefore may be made of any suitable material, such as carbon steel or stainless steel. If the washer 38 is made of stainless steel, then the sleeve plate 16 preferably has a minimum Vickers hardness value of 200 HV. This is to ensure that the washer 38 and sleeve plate 16 generates sufficient clamping force.

[0072] The washer 38 may be any standard washer 38, or may be specially hardened by any suitable means, such as mechanical or chemical working. For example, the washer 38 may be further hardened by additional heat treatment. Preferably, the washer 38 is made from a material that has a different hardness to the sleeve plate 16. This ensures that the washer 38 generates a higher clamping force as the sleeve plate 16 is at least partially formed from relatively softer materials. Preferably, the hardness of the washer 38 is higher than the hardness of the sleeve plate 16.

[0073] As shown in Figure 3A, the entirety of the underside of the bolt head 15 is arranged to abut a surface 38a of the washer 38, specifically, the surface 38a of the washer 38 that is nearest the bolt head 15. Therefore, as the bolt head 15 is tightened, the compressive force is distributed evenly across the entirety of the washer 38, which helps improve the clamping force between the bolt head 15 and the sleeve 16, and between the fixing plate 11 and the support plate 12.

[0074] While the washer 38 in Figures 3A and 3B are shown to be received within the recess 36, it will be understood that the washer 38 may alternatively be provided on a surface 16a of the sleeve plate 16 without the recess 36. In this instance, the washer 38 is positioned between an upper surface 16a of the sleeve plate 16 and the bolt head 15. This arrangement is advantageous as it does not require the sleeve plate 16 to be manufactured to fit the washer 26, thereby making it easier to manufacture and assemble the fastening device 13.

[0075] In the exemplary fastening device 13 shown in Figures 3A and 3B, the sleeve 20 and the sleeve plate 16 are provided as a separate components. This allows a compressible washer 19 (discussed further below) to be easily assembled between the sleeve plate 16 and the sleeve 20. In other examples, the sleeve 20 and the sleeve plate 16 may be secured together (e.g. by welding) to form a unitary component, or the sleeve plate 16 and the sleeve 20 may be manufactured as one continuous component, such as the arrangement shown in Figure 3C. The resulting fastening device 13 is therefore cheaper as providing the P608720PC00

[0076] 10 sleeve plate 16 and sleeve 20 as one continuous component reduces the number of parts within the assembly.

[0077] Abutting against the sleeve plate is a compressible apertured washer 19. The washer is manufactured from an elastomeric material which enables the washer to be slightly deformed axially during the tightening of the fastening device 13 if required.

[0078] Abutting against the washer 19 is a tubular sleeve 20 which extends along the threaded bolt 14. An expansion portion of the sleeve 20 remote from the washer 19 is split into fingers 20a by slots which extend parallel to the sleeve 20. A portion of the end wall 22 is inclined to the axis of the sleeve 20 to form a receiving portion for engagement with an expansion head 23 described in greater detail below.

[0079] Threaded along the bolt 14 is a frustoconical expansion head 23. The expansion head comprises an engagement face 24, a base 25 and a contact face 26 extending therebetween. A portion of the contact face 26 proximate to the engagement face 24 is roughened to increase the friction between the sleeve 20 and expansion head 25 in use. The contact face 26 proximate to the engagement face 24 of the sleeve 20 is arranged to be complimentary to the receiving portion so that they initially engage over an extended area.

[0080] Before use the expansion head 23 is threaded along the bolt 14 until the roughened portion of the contact face 26 abuts against the receiving portion of the sleeve 20. The expansion head 23 is then tightened usually by hand, so applying a small compressive force to the compression means 19 and sleeve 20. This slight compression force causes sufficient friction between the compression means 19, sleeve 20 and expansion head 23 to prevent these components from rotating with respect to the sleeve plate 16 during tightening.

[0081] In use the assembled fastening device 13 is inserted through the aligned apertures of a support plate 27 and fastening plate 28 until the sleeve plate 16 abuts against the fastening plate 28, as shown in figure 4a.

[0082] A gripping tool (not shown) is engaged with the sleeve plate 16 to prevent turning of the sleeve plate during tightening of the fastening device 13. A tightening tool P608720PC00

[0083] 11 is then connected to the bolt head 15 and turned to rotate the bolt 14. As previously discussed, the friction between the sleeve plate 16, washer 19 (i.e. the compression means), sleeve 20 and expansion head 23 prevent the expansion head 23 from rotating with the bolt 14. The expansion head 23 is therefore drawn along the bolt 14 towards the bolt head 15 so spreading apart the fingers 20a of the expansion portion of the sleeve 20 until the fingers grip the sides of the aperture wall (as shown in figure 4b).

[0084] During this period of expansion, the sleeve plate 16 and expansion head 23 apply an axial compression force to the sleeve 20 and washer 38. The washer 38 is designed to withstand this axial compressive force without any substantial change in axial length.

[0085] As the bolt head 15 is tightened, the washer 38 axially compresses. Due to the hardness of the washer 38, the bolt head 15 is able to tighten and have an increased clamping force between the washer 38and the bolt head 15. This results in a greater clamping force being transmitted between the support plate 27 and the fastening plate 28, resulting in both structures being gripped together at a higher force. As the washer 38 is manufactured from a harder material than the sleeve plate 16, it also prevents the bolt head 15 from becoming loose. This helps prevent the bolt 14 from "slipping" i.e. from becoming loosened after an extended period of time.

[0086] Once the sleeve 20 has gripped the aperture wall 17 further turning of the bolt head 15 increases the compressive force applied to the sleeve 20 and compressible washer 19. In response, the washer 19 begins to axially compress and expand radially as shown in figure 4(c). As the washer 19 compresses the sleeve 20 is pushed towards the sleeve plate 16 so pressing the support plate 27 and fastening plate 28 together.

[0087] During this compression phase of tightening the axial load, applied to the washer 19 is comparable to the load which would be applied by the use of a standard bolt and nut.

[0088] Most of the torsional force applied to the bolt head 15 is converted to a compressional force. P608720PC00

[0089] 12

[0090] In the final stage of tightening, the washer 19 expands outwards until it reaches the aperture wall 17, so forming a seal between the sleeve plate 16 and fastening plate 28. This seal prevents the entry of water or other fluids into the aperture 18, so extending the bolt life.

[0091] In an alternative embodiment of the invention, the aperture wall 17 of the sleeve 20 plate is threaded and is designed to engage with the thread on the bolt 14.

[0092] In the embodiment of the invention shown in figures 3A, 3B, 3C and 4, the washer 19 is of approximately the same outer diameter as the sleeve 20. In an alternative embodiment, the washer 19 can have a larger diameter than the sleeve 20 to ensure a tight seal between the washer 19 and sleeve plate 16 when the fastening device 13 is fully tightened.

[0093] In an alternative embodiment, the elastomeric washer 19 is replaced by a spring. Alternatively, the elastomeric washer 19 can be a steel washer.

[0094] Figure 5 is an exploded view of another exemplary arrangement of fastening device 13, according to the present invention. The fastening device 13 is substantially identical to the fastening device 13 described above but further includes a visual means indicator 80. The visual means indicator 80 is arranged on the fastening device 13 so that on further tightening of the fastening device 13, the visual means indicator 80 is axially compressed to provide a visual indication that the fastener (i.e. the threaded bolt 14) reaches a threshold pretension. The visual indicator means 80 acts as a safeguard to prevent the operator under tensioning or over tensioning the fastening device 13.

[0095] As shown in Figure 5, the visual means indicator 80 comprises a visual indicator washer 50. In this arrangement, the visual indicator washer 50 is remote from the diverging sleeve expanding head (i.e. the expansion head 23). In this arrangement, the visual indicator washer 50 located between hardened washers 38. In other examples, the visual indicator washer 50 may be arranged adjacent one washer 38 (e.g. "above" the washer 38 and so adjacent an upper surface of the washer 38, or "below" the washer 38 and so adjacent a lower surface of the washer 38). However, it will be understood that the visual indicator washer can be located between any number of washers 38 and the sleeve plate 16. P608720PC00

[0096] 13

[0097] The visual indicator washer 50 includes a visual indicator 50a on a top surface of the washer. In this example, the visual indicator 50a has a plurality of protrusions 51 on the upper surface of the visual indicator washer 50. In another example, the visual indicator 50a could include a plurality of protrusions 51 on the lower surface of the visual indicator washer 50. In another example, the visual indicator 50a could include a plurality of protrusions 51 on the upper and lower surfaces of the visual indicator washer 50. In another example, the visual indicator 50a could include a plurality of protrusions 51 on both the upper and lower surface of the visual indicator washer 50. In Figures 5, 6A and 6C, the protrusions 51 extend away from the respective surface of the visual indicator washer 50. For example, when the protrusions 51 are arranged on an upper surface of the visual indicator washer 50, the protrusions 51 extend away from the upper surface of the visual indicator washer 50. Once assembled, this may be towards a hardened washer 38 or towards the underside of the fastener head 15. In other examples, when the protrusions 51 are arranged on a lower surface of the visual indicator washer 50, the protrusions 51 extend away from the lower surface of the visual indicator washer 50. Once assembled, this may be towards a hardened washer 38 or towards the sleeve plate 16.

[0098] In the example shown in Figure 5, the visual indicator washer 50 includes four protrusions 51 that are arranged radially around the circumference of the visual indicator washer 50. As shown, each protrusion is arranged with a gap between each protrusion 51. Each protrusion 51 is therefore not in contact with the neighbouring protrusion 51. However, it will be understood that any number of protrusions 51 would be suitable. The protrusions 51 are shown to be semicircular, however, in other examples they could be any shape suitable, such as circular, semi-circular, square or rectangle. It will be understood that the shape of the protrusion may be adapted depending on the amount of pretension required by the assembly 13.

[0099] In all examples, the plurality of protrusions 51 are configured to axially compress during tightening. More specifically, as the fastening device 13 is tightened, the washer 38 contacts against the protrusions 51 (or in other examples, the bolt head 15 or the sleeve plate 16). The protrusions 51 are therefore deformed by the compressive axial load, causing them to deform downward into the recesses on the underside of the visual indicator washer 50. This deformation reduces the overall gap between the top surface of the visual indicator washer and the P608720PC00

[0100] 14 underside of the hardened washer 38. After tightening the fastening device 13, an operator can use a tool, such as a feeler gauge (not pictured) to measure the gap between the top surface of the visual indicator washer 50 and the underside of the hardened washer 38. If the tool is unable to fit into a gap, this indicates that a certain value of pretension has been achieved.

[0101] In other examples, the visual indication means 80 may allow the operator to visually inspect the installation of the fastening device 13 without the use of a tool. In such examples, the protrusions 51 may be made of an elastomeric material. In some examples, the protrusions 51 may be formed in accordance with industry standards applicable to visual indication washers 50, such as EN 14399-9, ASTM F959 / F959M, or ASTM F2437 / F2437M.By making the protrusions 51 with the elastomeric material, upon axial compression (and upon reaching the threshold pretension), the protrusions 51 will extend beyond the bolt head 15. More specifically, the elastomer will deform in response to compressive axial load and spread towards the outer circumference of the visual indication washer 50. Preferably, the protrusions 51 will extend toward and beyond the outer perimeter of the bolt head 15. This ensures that upon installation, the protrusions 51 (in the compressed state) will be visible to the operator once the fastening device 13 is correctly installed. This arrangement allows the operator to visually inspect the installation of the fastening device 13 with the advantage of not having to use a tool (such as a feeler gauge) on each fastening device 13. In some arrangement, the protrusions 51 may be brightly coloured for ease of inspection. In other examples, the protrusions 51 may be glow-in-the-dark for ease of inspection in poorly lit environments.

[0102] In other examples, the protrusions 51 may be provided as capsules. In such arrangements, a specified compressive axial load will break the elastomer capsules 51 and release a fluid contained inside. In some examples, the fluid may be an elastomer. Upon compression of the capsule 51, the fluid will be visible to the operator. A specified volume of visible fluid may correspond to verified installation.

[0103] Figures 6A and 6C show another exemplary visual indicator washers 60, 70 with exemplary visual indication means 80 respectively. Figure 6A shows a perspective view of a visual indicator washer 60, while Figure 6B shows the lower surface of the visual indicator washer 60. As shown, the visual indicator washer 60 includes P608720PC00

[0104] 15 visual indication 80 means on the upper and lower surface of the visual indicator washer 60. More specifically, the visual indicator washer 60 includes protrusions 61a on the upper surface. On the lower surface, the visual indicator washer 61b includes protrusions that extend radially around a circumference of the washer. The protrusions 61a on the upper surface of the visual indicator washer 60 are substantially identical to the protrusions 51 shown and described in relation to Figure 5. These protrusions 61a are therefore intended to be inspected with an additional tool (not shown) once the fastening device 13 is installed. The protrusions 61b on the lower surface of the visual indicator washer 60 are elastomeric protrusions that are configured to expand towards an outer edge of the washer 60 once the fastening device 13 is installed. This arrangement allows the operator to have two means of verifying the installation of the fastening device 13.

[0105] In the example shown in Figure 6C, the visual indication washer 70 has protrusions 71 that extend radially around a circumference of the visual indication washer 70. The protrusions 71 may be any suitable protrusion arrangement as described above in relation to the other visual indication washers 50, 60. In this arrangement, the protrusions 71 are elastomeric protrusions 71 that are arranged to operate in an identical manner to the protrusions 61b on the lower surface of the visual indication washer 60 shown in Figure 6B.

[0106] It will be understood that any arrangement and combination of protrusions 51, 61a, 61b, 71 may be used in combination on the upper and / or lower surfaces of a visual indication washer 50, 60, 70. For example, a set of protrusions that are intended to be used with a tool may be used on an upper surface of a washer 50, 60, 70 and an elastomeric protrusion arrangement may also be positioned on the upper surface of the washer.

[0107] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

P608720PC0016Claims1. A blind fastening device for use in clamping a component to a support plate by positioning said fastening device through aligned openings in the component and in the support plate, the fastening device comprising: a slotted sleeve; an apertured sleeve plate; a fastener comprising a threaded fastener portion which can be taken through the slotted sleeve, the apertured sleeve plate and the apertured compression means; the fastener further comprises a tightening head for tightening the fastener; a washer positioned between the tightening head and the sleeve plate; and a diverging sleeve expanding head mounted on the fastener portion and engageable with the end of the sleeve on tightening of the fastener, in order to expand said end rigidly outwards into contact with at least one of said openings to anchor the sleeve.

2. A blind fastening device according to claim 1, wherein the entirety of the underside of the tightening head contacts the surface of the washer contacting the tightening head.

3. A blind fastening device according to any preceding claim, wherein the sleeve plate further comprises a recess, wherein the recess is configured to receive the washer.

4. A blind fastening device according to claim 3, wherein the depth of the recess is such that the washer is flush with a surface of the sleeve plate facing the tightening head when received within the recess.

5. A blind fastening device according to claim 3 or 4, wherein the recess has a base and wall surrounding the base wherein the base and / or wall of the recess are untextured.

6. A blind fastening device according to any preceding claim, wherein the washer is made from materials with differing hardness value to the sleeve plate.P608720PC00177. A blind fastening device according to claim 6, wherein the hardness of the washer is higher than the of the sleeve plate.

8. A blind fastening device according to any preceding claim, wherein the washer comprises carbon or stainless steel.

9. A blind fastening device according to any preceding claim, wherein the washer has a minimum Vickers Hardness of 200HV.

10. A blind fastening device of claim 9, wherein the washer is hardened by heat treatment.

11. A blind fastening device according to any preceding claim, wherein the washer is made from materials of differing hardness to the sleeve plate.

12. A blind fastening device of claim 11, wherein the hardness of the washer is higher than the hardness of the sleeve plate.

13. A blind fastening device according to any preceding claim, wherein the device further comprises an apertured compression means located between the slotted sleeve and the sleeve plate, wherein the compression means is remote from the diverging sleeve expanding head, wherein the compression means is adapted such that on further tightening of the fastener, the compression means is axially compressed between said sleeve and said sleeve plate so reducing the distance between said sleeve and sleeve plate.

14. A blind fastening device according to claim 13, wherein the compression means comprises an elastomeric washer.

15. A blind fastening device according to claim 13 or 14, wherein on compression of the compression means, the compression means expands outwardly to form a seal between the sleeve plate and the component.

16. A blind fastening device according to any preceding claim, wherein the device further comprises a visual indicator washer located between the sleeve plate and the washer, wherein the visual indicator washer is remote from the divergingP608720PC0018 sleeve expanding head, and the visual indicator washer is adapted such that on further tightening of the fastener, the visual indicator washer is axially compressed to provide a visual indication that the fastener reaches a threshold torque / tension.

17. A blind fastening device according to claim 16, wherein the visual indicator washer comprises a visual indicator on a top surface of the washer.

18. A blind fastening device according to claim 16 or 17, wherein the visual indicator washer comprises a visual indicator on a bottom surface of the washer.

19. A blind fastening device according to any one of claims 16 to 18, wherein the visual indicator comprises a plurality of protrusions on an upper and / or lower surface of the washer, wherein the protrusions are configured to axially compress during tightening.

20. A blind fastening device according to claim 19, wherein the plurality of protrusions comprises an elastomer such that, upon reaching the threshold torque, the elastomer extends beyond the fastener head.

21. A blind fastening device according to any preceding claim, wherein said apertured sleeve plate has a formation offset from the axis of the threaded fastener portion which is engageable with a tool to prevent rotation of the sleeve plate while the fastener is being tightened.

22. A blind fastening device according to any preceding claim, wherein the diverging sleeve expanding head is frustoconical.

23. A blind fastening device according to any preceding claim, wherein the slotted sleeve and sleeve plate are provided as a unitary component.

24. A blind fastening device for use in clamping a component to a support plate by positioning said fastening device through aligned openings in the component and in the support plate, the fastening device comprising: a slotted sleeve; an apertured sleeve plate;P608720PC0019 a fastener comprising a threaded fastener portion which can be taken through the slotted sleeve, the apertured sleeve plate and the apertured compression means; the fastener further comprises a tightening head for tightening the fastener; a washer positioned between the tightening head and the sleeve plate; and a diverging sleeve expanding head mounted on the fastener portion and engageable with the end of the sleeve on tightening of the fastener, in order to expand said end rigidly outwards into contact with at least one of said openings to anchor the sleeve, wherein the slotted sleeve and sleeve plate are provided as a unitary component.

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