WO2009090407A1

WO2009090407A1 - Method of securing a fastener

Info

Publication number: WO2009090407A1
Application number: PCT/GB2009/000133
Authority: WO
Inventors: Richard David Hughes; Stephen Joseph Ainsworth
Original assignee: NORTHELFER UK Ltd; AB Electronic Ltd
Current assignee: NORTHELFER UK Ltd; AB Electronic Ltd
Priority date: 2008-01-18
Filing date: 2009-01-19
Publication date: 2009-07-23
Anticipated expiration: 2010-07-18
Also published as: EP2234741B1; EP2234741A1; GB0800965D0; GB2456560A; GB2456560B

Abstract

The present invention relates to a method of securing a fastener (18, 24) having a fastening member (18) and a retaining member (24), the method comprising providing a magnetic field in the vicinity of an end of said fastening member (18), sensing said magnetic field using an array of magnetic field sensors (28) positioned in the vicinity of an opposing end of said fastening member (18), the array of magnetic field sensors (28) being coupled with a retainer fitting means (30), said retainer fitting means (30) being operable to secure said retaining member (24) to said fastening member (18), determining responses sensed by said array of magnetic field sensors (28) so as to determine the displacement between the fastening member (18) and the retainer fitting means (24), moving the array (28) and/or the retainer fitting means (30) to a position in which the displacement is minimum, and securing said retaining member (24) to the fastening member (18).

Description

METHOD OF SECURING A FASTENER

Field of the Invention

The present invention relates to a method of securing a fastener having a fastening member and a retaining member. More particularly, but not exclusively, it relates to a method of securing a fastener in a manufacturing process such as assembly of an aeroplane or an automotive vehicle, for example wing panels of an aeroplane.

Background of the Invention

Conventionally, manufacturing industries such as the aerospace industry have been highly labour-intensive. As manufacturers in the aerospace industries are constantly striving to reduce costs while maintaining quality, automated manufacturing has gained credibility in the aerospace industries over recent years. For instance, a variety of automated systems have been developed to perform the task of assembling panels, such as wing panels.

However, the task of installing mechanical rivets in order to secure wing panels to a framework of a wing structure is carried out manually. This is time consuming and requires high labour intensity as the task of securing a nut to the rivet is usually carried out by a technician.

Summary of the Invention

Aspects of the present invention provide a simple and highly effective method of securing a fastener onto wing panels of an aeroplane.

In a first aspect of the present invention, there is provided a method of securing a fastener having a fastening member and a retaining member, the method comprising providing a magnetic field in the vicinity of a first end of said fastening member, sensing said magnetic field using a magnetic field sensing means in the vicinity of an opposing second end of said fastening member, the magnetic field sensing means being coupled with a retainer fitting means, said retainer fitting means being operable to secure said retaining member to said fastening member proximate said second end, determining responses sensed by said magnetic field sensing means so as to determine the displacement between the fastening member and the retainer fitting means, moving the array and/or the retainer fitting means to a position in which the displacement is minimum, and securing said retaining member to the fastening member.

In a preferred embodiment of the above aspect, there is provided the step of loading said fastening member through an aperture of an object.

Preferably, said providing said magnetic field includes using a magnetisable component to load said fastening member through said aperture of said object.

Preferably, said magnetisable component comprises an end for holding said fastening member when said fastening member is loaded.

In a preferred embodiment of the above aspect, there is provided the step of coupling a magnetic component at an opposing end of said magnetisable component so as to magnetise said magnetisable component thereby providing magnetic field in the vicinity of said end of said fastening member.

Preferably said magnetisable component is a ferrous metal.

Alternatively, said providing said magnetic field includes using a magnetic component to load said fastening member through said aperture of said object.

Preferably, said magnetic component comprises an end for holding said fastening member when said fastening member is loaded.

Preferably, said array and said retainer fitting means are moved simultaneously. The magnetic field sensing means may comprise an annular array of magnetic field sensors.

In a second aspect of the present invention, there is provided an apparatus for securing a fastener having a fastening member and a retaining member, the apparatus comprising means for generating a magnetic field in the vicinity of a first end of said fastening member, a magnetic field sensing means positioned in the vicinity of an opposing second end of said fastening member, the magnetic field sensing means being operable to sense said generated magnetic field, a retainer fitting means coupled with said array, said retainer fitting means being operable to secure said retaining member to said fastening member, a processing means coupled with outputs of said magnetic field sensing means, said processing means being operable to determine responses sensed by said magnetic field sensing means so as to determined the displacement between the fastening member and the retainer fitting means, and wherein said array and/or said retainer fitting means are/is operable to move to a position in which the displacement is minimum.

Brief description of the drawings

Embodiments of the present invention will now be described with reference to the accompanying drawings, wherein:

Figure 1 is a side view representation of an apparatus in accordance with a first embodiment of the present invention before a retaining member is fastened onto a fastening member;

Figure 2 is a side view representation of the apparatus of figure 1 when a retaining member is fastened onto a fastening member;

Figure 3 illustrates a magnetic field sensor comprising an annular array of sensors in the apparatus of figure 1; Figure 4 is a schematic representation of a processing unit in accordance with the first embodiment;

Figure 5 illustrates an annular array of magnetic field sensors with a retainer-fitting tool attached to the side in accordance with a second embodiment of the present invention;

Figure 6 is a side view representation of an apparatus in accordance with the second embodiment of the present invention when the annular array of sensors is aligned with the axis of a fastening member;

Figure 7 is a side view representation of an apparatus of figure 6 when a retainer-fitting tool is aligned with the axis of a fastening member; and

Figure 8 is a side view representation of an apparatus of figure 6 when a retaining member is fastened onto a fastening member.

Detailed description

A specific embodiment of an apparatus for securing a fastener onto wing panels of an aeroplane is described in the following paragraphs.

An overview of the set up of an apparatus 10 in accordance with a first embodiment of the present invention is illustrated in Figure 1. For the sake of simplicity, a single through hole 12 is shown in the wing panel 14 with a plate 16 attached to the wing panel 14. The plate 16 has a corresponding through hole 17. Referring to Figure 1, the through holes 12,17 are aligned such that a rivet 18 of a fastener 18, 24 can be loaded into the holes 12,17. The rivet 18 provides means for retaining the wing panel 14 and the plate 16 together, and it is a fastening member of the fastener 18, 24. It will be appreciated by the person skilled in the art that other forms of fastening member, such as bolt, screw and so on, may also be used. The rivet 18 has a countersink head, cooperating as illustrated with a countersink of the hole 12 of the wing panel 14. In this example, the rivet 18 has a threaded end 18a such that it is suitable for engaging with a corresponding internally threaded nut. The surface (not shown) of the head 22 of the rivet 18 also has preformed slot(s) for receiving a cooperating tool to allow the tool to hold or rotate the rivet.

Rivets can be introduced by means of a loading magazine (not shown) and a loading operation at the same robot head.

It will also be appreciated by the person skilled in the art that any suitable methods for drilling the holes 12,17 and loading the rivet into the hole may be employed. For this reason, details of drilling the hole and loading the rivet into the hole will not be described.

As shown in Figure 1, a fastener retention tool 20 engages with the preformed slots at the head 22 of the rivet 18 to hold the rivet 18 in the holes 12,17 while a nut 24 is applied to the rivet 18. The nut 24 provides means for fastening/securing the rivet 18, and it is a retaining member of the fastener 18,24. In this example, the nut 24 is internally threaded so as to engage with the corresponding rivet 18.

However, threading engagement of the nut 24 and the rivet 24 is but an example for purposes of providing a specific embodiment, and is not intended to limit the scope of application of the invention.

In this embodiment, the fastener retention tool 20 is made of magnetisable material such as tungsten carbide. However, any other forms of magnetisable material may be used, for example, a ferrous material such as steel or iron.

Located at the top of the fastener retention tool 20, as shown in Figure 1, is a magnet 26 for magnetising the fastener retention tool 20 so as to produce a strong magnetic field at the head 22 of the rivet 18. It will readily be appreciated that any form of magnetic field generating means may be employed to produce the magnetic field at the head of the rivet 18. For instance, the fastener retention tool 20 may be a magnet itself.

A sensor head 28 comprising an array of sensors is located at the opposite side of the wing panel 14 where the rivet 18 protrudes through the holes 12, 17. As shown in Figure 3, sensor head includes a plurality of sensors 281a arranged in a ring array arrangement. The skilled person in the art would appreciate that a larger number (for example 4, 16 or 32 and so on) of sensors would enhance the accuracy of the sensor. The sensors 281 in this embodiment are essentially magnetic field sensors, such as Hall effect sensors or eddy-current sensors.

The outputs (not shown in Figure 1) of the array of magnetic field sensors are connected to a microcontroller to process the received signals. Figure 4 shows schematically the components of the microcontroller 50. The microcontroller 50 includes an Input/Output (I/O) interface 52, a working memory 54, a signal processor 56 and a mass storage unit 58. The signal processor 56 is operable to execute machine code instructions stored in a working memory 54 and/or retrievable from a mass storage unit 58.

The outputs of the magnetic field sensors 281 are connected to the signal processor 56 via the I/O interface 52 of the microcontroller 50. By this connection, incoming signals can be input to the signal processor 56. The I/O interface 52 also includes an analogue- to-digital converter (ADC) (not shown) which converts the analogue output signals from the magnetic field sensors into digital input signals. By means of a general purpose bus 60, external devices (such as the magnetic sensors 281 and the retainer- fitting tool 30) through the I/O interface 52 are in communication with the signal processor 56.

The microcontroller 50 processes the incoming signals and determines the position of the strongest magnetic field strength. If the sensor head 28 is shifted from its position, the detected magnetic field strengths will vary at the individual sensors 281 and the detected signals can be appropriately analysed to determine the displacement between the axis of the sensor head 28 and the axis of the rivet 18. By moving the sensor head to minimise the displacement, the axis of the sensor head 28 may be aligned with the axis of the rivet 18. It will be appreciated that if the axis of the aperture 32 of the sensor head 28 is positioned coaxially with the axis of the rivet 18 then the detected magnetic field strength will be greatest and of equal value for all the sensors 281 in the sensor head 28. As shown in Figure 1, a retainer-fitting tool 30 is provided to load and fasten the internally threaded nut 24 onto the rivet 18, thereby securing the plate 16 onto the wing panel 14. It will be appreciated by the person skilled in the art that any other means of fitting the nut 24 may be employed. Furthermore, the nut 24 may be loaded to the retainer-fitting tool by means of a loading magazine (not shown). The operation of the retainer-fitting tool is also controlled by the microcontroller 50. As shown in Figures 1 and 2, the retainer-fitting tool 30 may be attached to the sensor head 28 such that the longitudinal axis of the retainer-fitting tool 30 is aligned with the axis of the sensor head 28. In this arrangement longitudinal axis of the retainer-fitting tool 28 aligns with the axis of the rivet 18 when the axis of the sensor head 28 is aligned with the axis of the rivet 18.

In this example, the nut 24 is of hexagonal profile, and the retainer-fitting tool 30 defines a corresponding hexagonal socket.

Once the axis of the sensor head 28 (and axis of the retainer-fitting tool 30) substantially coincides with the axis of the rivet 18, the retainer-fitting tool 30 may then load and fasten the nut 24 onto the rivet 18. Figure 2 illustrates the fastening operation of the retainer-fitting tool 30 loading and fastening a nut 24 onto the rivet 18.

It will be appreciated by the person skilled in the art that the. movement of the sensor head 28 and the retainer-fitting means can be performed by means of a movable fixture (not shown), for example a robot arm. This robot arm can be connected to the microcontroller 50 and the movement of the robot arm is controlled according to the calculated displacements between the axis of the aperture 32 of the sensor head 28 and the axis of the rivet 18.

In this example, the fitting operation of the nut 24 onto the rivet 18 involves threading engagement, therefore it will be understood that the precision of the positioning of the retainer-fitting tool can be defined with a particular tolerance, given the extent to which threaded rivets and threaded nuts can be engaged together successfully though they may not be introduced exactly coaxially. To this end, the operation may include an opposite- sense half turn (to take an example) to enhance the engagement of the cooperating threads.

It is considered that the person skilled in the art would appreciate that the sensor head need not be a ring array arrangement. It is further considered that the axis of the retainer-fitting tool may not be coaxial with the axis of the sensor head. As illustrated in Figure 5, the sensors 721 may be arranged in a cross hair configuration around a centre point 72. The retainer-fitting tool 74, as illustrated in Figure 5, is attached to the side of the sensor head 70 as a single assembly system 68. By appropriate programming and calibration, the position of the longitudinal axis of the retainer-fitting tool 74 relative to the centre point 72 can be compensated accordingly. In this case, the sensor head 70 would first determine the location of the rivet 18 by aligning the centre point 72 with the axis of the rivet 18. Once this is determined, the system 68 then moves by a predetermined distance (determined in a calibration process) such that the longitudinal axis of the retainer-fitting tool 74 is substantially aligned with the axis of the rivet 18. Figures 6 to 8 illustrate this process.

The apparatus set up of the present invention may be implemented using two robot arms, one on each side of the wing panel 14, both controlled by the same microcontroller 50. Essentially, one of the robot arms provides the function of loading and holding the rivet 18 (that is the fastener retention tool 20), and the other robot arm provides the function of loading and fastening the nut 24 onto the rivet 18 (that is the retainer-fitting tool 30).

It will be appreciated that the foregoing provides description of specific embodiments of the invention and that no limitation on the scope of protection sought herein is to be implied therefrom. The scope of protection sought is to be determined from the claims, read with reference to, but not bound by, the description and drawings.

Claims

CLAIMS:

1. A method of securing a fastener having a fastening member and a retaining member, the method comprising providing a magnetic field in the vicinity of a first end of said fastening member; sensing said magnetic field using an array of magnetic field sensors positioned in the vicinity of an opposing second end of said fastening member, the array of magnetic field sensors being coupled with a retainer fitting means, said retainer fitting means being operable to secure said retaining member to said fastening member, proximate or at said second end; determining responses sensed by said array of magnetic field sensors so as to determine the displacement between the fastening member and the retainer loading means; moving the array and/or the retainer fitting means to a position in which the displacement is minimum; and securing said retaining member to the fastening member.

2. A method according to claim 1 includes loading said fastening member through an aperture of an object.

3. A method according to claim 1 or claim 2 wherein said providing said magnetic field includes using a magnetic component to load said fastening member through said aperture of said object.

4. A method according to claim 3 wherein said magnetic component comprises an end for holding said fastening member when said fastening member is loaded.

5. A method according to claim 1 or claim 2 wherein said providing said magnetic field includes using a magnetisable component to load said fastening member through said aperture of said object.

6. A method according to claim 5 wherein said magnetisable component comprises an end for holding said fastening member when said fastening member is loaded.

7. A method according to claim 6 further includes coupling a magnetic component at an opposing end of said magnetisable component so as to magnetised said magnetisable component thereby providing magnetic field in the vicinity of said end of said fastening member.

8. A method according to any one of claims 5 to 7 wherein said magnetisable component is a ferrous metal.

9. A method according to any one of the preceding claims wherein said array and said retainer fitting means are moved simultaneously.

10. A method according to any one of the preceding claims wherein said array is a ring array arrangement.

11. An apparatus for securing a fastener having a fastening member and a retaining member, the apparatus comprising means for generating a magnetic field in the vicinity of a first end of said fastening member; an array of magnetic field sensors positioned in the vicinity of an opposing end of said fastening member, the array of magnetic field sensors being operable to sense said generated magnetic field; a retainer fitting means coupled with said array, said retainer loading means is operable to secure said retaining member to said fastening member, proximate or at said second end thereof; a processing means coupled with outputs of said array of magnetic field sensors, said processing means being operable to determine responses sensed by said array magnetic field sensors so as to determined the displacement between the fastening member and the retainer fitting member; and wherein said array and/or said retainer loading means is operable to move to a position in which the displacement is minimum.

12. An apparatus according to claim 11 wherein means for generating said magnetic field includes a magnetic component having an end for holding said fastening member when the fastening member is been fastened.

13. An apparatus according to claim 11 wherein means for generating said magnetic field includes a magnetisable component having an end for holding said fastening member when fastening member is been fastened.

14. An apparatus according to claim 13 wherein said means for generating said magnetic field further includes a magnetic component coupled to an opposing end of said magnetisable component so as to magnetised said magnetisable component thereby providing magnetic field in the vicinity of said end of said fastening member.

15. An apparatus according to any one of claims 13 to 14 wherein said magnetisable component is a ferrous metal.

16. An apparatus according to any one of claims 11 to 15 further comprises means for moving said array and said retainer fitting means simultaneously.

17. An apparatus according to any one of claims 11 to 16 wherein said array is a ring array arrangement.

18. A method substantially as herein described with reference to any one of the accompanying drawings.

19. An apparatus substantially as herein described with reference to any one of the accompanying drawings.