METHODS OF INSTALLING FASTENERS AND APPARATUS RELATING THERETO

Abstract

A method of installing a plurality of nut and bolt fasteners upon a structure is disclosed. The method includes placing a jig around the nut of a first fastener and the nut of a second fastener, securing the jig to the first fastener, and then using a power tool to tighten the nut of the second fastener to a target torque. The step of tightening the nut comprises engaging a socket portion of the power tool with the nut, securing the power tool to the jig such that a handle portion of the power tool is prevented from rotating about an axis of rotation of a socket portion of the power tool when the nut is being rotated by the socket portion. A jig, jig fasteners for securing a jig to a fastener, and a fastening head for a power tool are disclosed.

Claims

1. A method of installing a plurality of nut and bolt fasteners upon a structure, wherein the bolt of a first fastener is located in a first hole of the structure and a bolt of a second fastener is located in a second hole of the structure and the nuts of the first and second fasteners are engaged with their respective bolts and have been tightened to an initial torque, the method comprising steps of: placing a jig around the nut of the first fastener and the nut of the second fastener, securing the jig to the first fastener, using a power tool to tighten the nut of the second fastener to a target torque, the power tool comprising a handle portion and a socket portion, wherein the step of tightening the nut comprises performing the following nut tightening steps: engaging the socket portion of the tool with the nut, securing the power tool to the jig such that the handle portion is prevented from rotating about an axis of rotation of the socket portion when the nut is being rotated by the socket portion, and operating the power tool to tighten the nut to the target torque.

2. The method of claim 1, wherein, once the nut of the second fastener has been tightened, the method comprises the step of using the power tool to tighten the nut of one or more other fasteners of the plurality of fasteners to the target torque, the nut(s) being tightened by following the nut tightening steps.

3. The method of claim 1, wherein, after the step of tightening the nut of the second fastener, the method comprises the steps of: unsecuring the jig from the first fastener securing the jig to the second fastener, and using the power tool to tighten the nut of the first fastener to the target torque by following the nut tightening steps.

4. The method of claim 1, wherein the plurality of nut and bolt fasteners comprises a third fastener, the bolt of the third fastener being located in a third hole of the structure and the nut of the third fastener being engaged with the bolt and having being tightened to an initial torque, and wherein, during the step of placing the jig around the nut of the first fastener and the nut of the second fastener, the jig is also placed around the nut of a third fastener, and wherein the nut of one of the fasteners is tightened while the jig is secured to both of the other two fasteners.

5. The method of claim 4, comprising the step of: unsecuring the jig from the third fastener, using the power tool to tighten the nut of the third fastener to the target torque by following the nut tightening steps.

6. The method of claim 4, wherein the plurality of nut and bolt fasteners comprises a fourth fastener, the bolt of the fourth fastener being located in a fourth hole of the structure and the nut of the fourth fastener being engaged with the bolt and having being tightened to an initial torque, and wherein, during the step of placing the jig around the nut of the first fastener, the nut of the second fastener, and the nut of the third fastener, the jig is also placed around the nut of the fourth fastener, and wherein the nut of one of the fasteners is tightened while the jig is secured to each of the other three fasteners.

7. The method of claim 6, comprising the step of: unsecuring the jig from the fourth fastener, using the power tool to tighten the nut of the fourth fastener to the target torque by following the nut tightening steps.

8. The method of claim 1, wherein the target torque is at least 50 Newton metres.

9. The method of claim 1, wherein the jig is secured to a nut and bolt fastener by a jig fastener that is configured to engage with the jig, and with the nut and/or bolt of the nut and bolt fastener.

10. The method of claim 1, wherein the power tool comprises formations configured to engage with corresponding formations on the jig, and the step of securing the power tool to the jig comprises engaging the formations of the power tool with the corresponding formations on the jig.

11. The method of claim 1, wherein the step of placing the jig around the nut of the first fastener and the nut of the second fastener comprises positioning a projecting feature of the structure in a cut-out of the jig.

12. A jig for use as the jig in the method of claim 1, wherein the jig comprises a plate portion formed with a plurality of holes therein, wherein each hole is configured to receive the bolt of a fastener and adjacent each of the holes the plate comprises formations configured to engage with corresponding formations on a fastening head of a power tool in order to secure the fastening head of the power tool to the jig.

13. A jig according to claim 12, wherein the formations adjacent each hole provide a bayonet fitting for engagement with the fastening head of the power tool.

14. A jig according to claim 12, wherein the plate is formed with a cut-out, and wherein one or more of the holes of the plurality are positioned on a first side of the cut-out and one or more of the holes of the plurality are positioned on a second, opposite side of the cut-out.

15. A jig fastener for use as the jig fastener of claim 9, wherein the jig fastener comprises a body portion configured to engage with a jig and a fastener engaging portion configured to engage with the nut and/or bolt of a fastener thereby being configured to secure the jig to the fastener.

16. The jig fastener of claim 15, wherein the body comprises a socket portion for engagement with the nut of a fastener.

17. The jig fastener of claim 16, wherein the fastener engaging portion comprises a clamping mechanism for clamping the body to the nut of the fastener to secure the jig upon the fastener.

18. The jig fastener of claim 15, wherein the fastener engaging portion comprises a thread-engaging member for screwing on to the bolt of the fastener.

19. The jig fastener of claim 15, wherein the body portion comprises a lip configured to engage with a jig in use to secure the jig to the fastener.

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

Description

DESCRIPTION OF THE DRAWINGS

[0036] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0037] FIG. 1 shows a load reaction jig held in place upon an aircraft structure by three nut covers;

[0038] FIG. 2 shows an embodiment of a nut cover in isolation;

[0039] FIG. 3 is a cross-sectional view of FIG. 1, showing a nut cover engaged with a fastener to hold the jig in place upon the aircraft structure;

[0040] FIG. 4 shows the portion of the jig labelled “A” in FIG. 1;

[0041] FIG. 5 shows a fastening tool fitted with a fastening head;

[0042] FIG. 6A is a rear view of the portion of the jig shown in FIG. 4 with the fastening head of the tool positioned in a hole of the jig in an unlocked position;

[0043] FIG. 6B corresponds to FIG. 6A but with the fastening head of the tool positioned in a locked position;

[0044] FIG. 7 shows the steps of fastening together two aircraft structures in accordance with an embodiment of the invention;

[0045] FIG. 8 shows a second embodiment of a nut cover in isolation; and

[0046] FIG. 9 shows the second embodiment of a nut cover in use with a second embodiment of a load reaction jig.

DETAILED DESCRIPTION

[0047] FIG. 1 shows a first aircraft structure 100 and a second aircraft structure 200 which have been prepared for fastening together according to an embodiment of the invention. The first structure 100 and second structure 200 are configured to be fastened together by a plurality of nut and bolt fasteners 300 of the type which are well known in the art. As can be seen in FIG. 1, the first aircraft structure 100 and a second aircraft structure 200 are both formed with a plurality of holes 101, 201 therein and have been placed together such that their respective holes 101, 201 are aligned. FIG. 1 also shows a load reaction jig 400 which has been placed against the first structure 100 such that it is aligned with the holes 101, 201 of the structures 100, 200. The load reaction jig 400 is held in place upon the first structure 100 by three nut covers 500.

[0048] A single nut cover 500 is shown in isolation in FIG. 2. The nut cover 500 comprises a bolt-engaging member 510 contained within a housing 520. The bolt-engaging member 510 is formed by an internally-threaded head 511, which is visible in the cross-sectional view of FIG. 3, and a cylindrical shaft 513 which projects from the head 511. The internally-threaded head 511 has a first outer diameter, and the cylindrical shaft 513 has a second, smaller diameter. A slot 515 is formed in the distal end 517 of the shaft 513 so that the bolt-engaging member 510 can be rotated using a flat-head screwdriver, as described below.

[0049] The housing 520 is formed by a substantially cylindrical hollow body 521 which has an internal diameter that is slightly larger than the outer diameter of the head 511 of the bolt-engaging member 510. The bolt-engaging member 510 is contained inside the housing 520 in co-axial alignment with the body 521. As shown in the cross-sectional view of FIG. 3, the housing 520 is formed with a reduced diameter at a first, fastener-receiving end 522 of the housing that provides a nut-receiving socket 523. At a second, opposite, end 524 of the housing 520, the housing 520 is formed with a lip portion 526 that projects outwardly from the body 521 in a radial direction. An annular plate 530 formed with a hole having a diameter that is slightly larger than the diameter of the shaft 513 is bolted to the lip portion at the second end 524 of the housing 520. The head 511 of the bolt-engaging member 510 is thereby retained within the housing 520 by the reduced-diameter of the socket 523 at the first, fastener-receiving end 522 of the housing 520 and by the annular plate 530 at the second, opposite, end of the housing 520.

[0050] The section of the load the jig 400 labelled A in FIG. 1 is shown in more detail from a front view in FIG. 4 and from a rear view in FIG. 6A and FIG. 6B. The load reaction jig 400 comprises a plate 402 formed with a plurality of holes 401 therein. The holes 401 are positioned so that they align with the holes 101, 201, in the aircraft structures 100, 200 when the load reaction jig 400 is in place upon the first structure 100, as shown in FIG. 1. The diameter of each hole 401 is slightly larger than the outer diameter of the body 521 of the nut cover housing 520, and is formed with two notches 405 that extend in a radial direction on opposite sides of the hole 401. On the rear-face 407 of the plate 402, recesses 409 are formed on either side of the notches 405. The plate 402 is also formed with an elongate cut-out 430 which results in the plate 402 have a “U” shape. The cut-out 430 is configured to receive a protruding feature 103 of the first structure 100 when the jig 400 is in place upon the first aircraft structure 100, as shown in FIG. 1.

[0051] The jig 400 is configured for use with a fastening tool 600 which has been fitted with a specially adapted fastening head 700 that is shown in FIG. 5. The fastening head 700 comprises a mounting portion 701 which is configured so that the head 700 can be mounted upon the fastening tool 600, which is an off-the-shelf model. In this case the mounting portion 701 is bolted to the tool 600 via bolts 703. The fastening head 700 comprises a cylindrical arm portion 705 having an outer diameter that is approximately equal to the outer diameter of the body 521 of the nut cover housing 520, so that the arm portion 705 can be inserted into a hole 401 of the jig 400. The arm portion 705 projects from the mounting portion 701 and, at the distal end 707, the arm portion 705 comprises two key portions 725 which project from the arm portion 705. The key portions 725 are positioned on radially opposite sides of the arm portion 705 and are configured to be received in the notches 405 of the jig 400, as described in more detail below. Also at the distal end 707 the arm 705, the fastening head comprises a socket portion 709. The socket portion 709 is mechanically coupled to the tool 600 and is configured to engage with the nuts 301 of the fasteners 300 so that the nuts 301 can be tightened using the tool 600 to drive rotation of the socket portion 709.

[0052] Use of the jig 400, nut-covers 500, and fastening head 700 in a method of fastening together two aircraft structures in accordance with an embodiment of the invention will now be described with reference to FIG. 7. In step 1000, the fasteners 300 are loosely installed in the holes 101, 201 of the of the aircraft structures 100, 200 and tightened to a nominal torque. The fasteners 300 may be tightened by hand at this stage or, for example, by using a run-down tool to tighten them to around 30 Nm. In step 2000, the jig 400 is moved into position upon the first structure, as shown in FIG. 1, with the holes 101, 201 of the aircraft structures 100, 200 aligned with the holes 401 of the jig 400, and with the protruding portion 103 of the first aircraft structure 100 received in the cut-out 430 of the jig 400.

[0053] The jig 400 is then clamped in place in step 3000 using the nut covers 500. To engage a nut cover 500 with the jig 400, first the housing 520 of the nut cover is moved into the hole 401 to engage the socket portion 523 of the housing 520 with the nut 301 of the fastener 300 that is positioned in the hole 101, 201. In this configuration, the housing 520 of the nut cover 500 is prevented from rotating by the engagement of the socket portion 523 with the nut 301.

[0054] As can be seen in FIG. 3, a distal portion 303 of the bolt 302 projects past the nut 301 towards the nut cover 500. With the housing 520 of the nut cover 500 engaged with the nut 301, the head 511 of the bolt-engaging member 510 is then moved into engagement with the distal portion 303 of the bolt 302 and screwed onto the distal portion 303 of the bolt 302 using a flat-head screwdriver in the slot 515. As the bolt-engaging member 510 is screwed onto the bolt 302, the head 511 abuts the rear surface 527 of the socket portion 523 and pushes the housing 520 into abutment with the first structure 100. The housing 520 is then clamped to the first structure by tightening the bolt-engaging member 510. As can be best seen in FIG. 3, with the nut cover 500 secured to the fastener 300, the jig 400 is prevented from being moved away from the first structure 100 by the lip 526 of the nut cover housing 520, which extends to a diameter that is greater than the hole 401 of the jig 400. FIG. 1 shows the jig 400 being held in place by three nut covers 500. However, any number of nut covers 500 can be used. In principle, only one nut cover 500 could be used.

[0055] With the jig 400 clamped in place, the fastening tool 600 fitted with the fastening head 700 is then used in step 4000 to tighten the nuts 301 of the fasteners 300 which are not covered by nut covers 500. In order to tighten a nut 301, the key portions 725 of the fastening head 700 are inserted into the notches 405 of the hole 401 in the jig 400 that surrounds the nut 301, as shown in FIG. 6A. The tool 600 is then moved to a locked position, shown in FIG. 6B, by rotating the tool 600 to move the key portions 725 of the fastening head 700 into the recesses 409 formed in the rear face 407 of the jig. The notches 405 and recesses 409 of the jig 400 thereby provide a “bayonet” or “twist-to-lock” mount for the fastening head 700.

[0056] The purpose of the jig 400 is to prevent the fastening tool 600 counter rotating when tightening the nuts 301 to a high torque, which may cause injury to the operator or damage the tooling and/or structure. The jig 400 does this by reacting the counter-rotation forces imparted by the fastening tool 600 when the nut 301 is being tightened by the tool 600. Where the nut 301 is tightened by rotating it clockwise from the perspective of the operator of the tool 600, as is the case here, there is a risk that the tool 600 itself will rotate clockwise if it is not held firmly. Therefore, the tool 600 must be moved to a locked position by rotating the key portions 725 of the fastening head 700 clockwise into the recesses 409 of the jig (FIG. 6B is a view of the rear face 407 of the jig, so the key portions appear to have moved anticlockwise to the locked position from FIG. 6A). With the tool in the locked position, clockwise rotation of the tool 600 during the fastening process is prevented by the key portions 725 of the fastening head rotating clockwise into abutment with the walls 411 of the recesses 409.

[0057] When the nut 301 is being unfastened, or where a nut 301 is tightened by rotating it anticlockwise from the perspective of the operator of the tool, the key portions 725 of the fastening head 700 must be rotated anticlockwise into the recesses 409 of the jig so anticlockwise rotation of the tool 600 during the fastening process is prevented by the key portions 725 of the fastening head rotating anticlockwise into abutment with the walls 411 of the recesses 409. With the fastening head 700 correctly located in the jig 400, the tool 600 can be operated to tighten the nut 301 to the desired torque.

[0058] The operator tightens all accessible fasteners 300 using the tool 600 and fastening head 700 in this way. Once all accessible fasteners 300 are tightened, the operator then removes the nut covers 500 from the loosely tightened fasteners 300 in step 5000. Steps 3000 and 4000 are then repeated by repositioning the nut covers 500 onto the fully torqued fasteners 300 and by tightening the now accessible loosely tightened fasteners 300 using the tool 600 and fastening head 700 engaged with the jig 400 as described.

[0059] A second embodiment of a nut cover 800 is shown in isolation in FIG. 8. Like the first embodiment of the nut cover 500, shown in FIG. 2 and FIG. 3, the nut cover 800 has a hollow cylindrical body 821 with a socket portion 823 formed in a first end 801 of the body 821 and a lip 826 formed at a second end 809 of the body 821. The diameter of the body 821 of the nut cover 800 is slightly smaller than the diameter of the holes 401′ in the jig, so that the body can be inserted into a hole 401′ in the jig. A split 803 is formed in the body 821, along the length of the body 821, and a groove 805 is formed along the inner surface 807 of the body 821, diametrically opposite the split 803. At the second end 809 of the body 821, the nut cover comprises a lever-operated cam system 810 of the type commonly seen, for example, on bicycles for clamping the seat post. The system 810 comprises a skewer 811 which bridges the split and is connected to a cam lever 813. The lever-operated cam system 810 is arranged such that operation of the cam lever causes the opposing faces of the split 803 to be moved closer together.

[0060] FIG. 9 shows the nut cover 800 in use with a second embodiment of a jig 400′. The jig 400′ is formed with fewer holes 401′ than the first embodiment of the jig 400 and also comprises a handle 403′. The nut covers 800 function by moving the body 821 into a hole 401′ in the jig 400′ and engaging the socket portion 823 of the nut cover 800 with a nut 301. The lever-operated cam system 810 is then operated to clamp the body 821 upon the nut 301. This jig is then held in place between the circumferential lip 826 of the nut cover 800 and the first aircraft structure 100.

[0061] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.