GB2590653A

GB2590653A - Clamp

Info

Publication number: GB2590653A
Application number: GB1919134.5A
Authority: GB
Inventors: Jackson Anthony; Redman Michael; Cantle David; Foster Matthew
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2021-07-07
Also published as: GB201919134D0

Abstract

A clamp 20 has a pair of openable and closeable jaws 21 for clamping either side of a stack of components. A first jaw of the pair of jaws has a U-shaped first pressure plate at a distal end of the jaws, and a second jaw of the pair of jaws has a second pressure plate partially aligned with the first pressure plate when the jaws are closed for clamping either side of the stack of components. Also disclosed is an automated one way assembly system for fastening together a stack of components, the system comprising a clamp, a drilling module, and a method of automated one way assembly for fastening together a stack of components.

Description

CLAMP

FIELD OF THE INVENTION

[0001] The present invention relates to a clamp, an automated one way assembly system for fastening together a stack of components using the clamp, and a method of assembly using the clamp.

BACKGROUND OF THE INVENTION

[0002] Aircraft wings typically include a series of chordwise extending ribs between upper and lower skin covers, and at least one spanwise extending spar also between the upper and lower skin covers. Typically, the ribs are attached to the skin covers by drilling holes through the wing skin and into the foot or flange of the rib at fastener locations, and then installing fasteners in the holes. In particular, where the landing gear connects to the wing structure there is provided a strengthened and thickened skin cover and a rib, known as a 'gear rib', extending between the covers aft of the rear wing spar, with lugs for pivotal connection to the landing gear. The thickness of the rib flanges for connection to the skin covers, and the thickness of the skin covers, requires large fasteners, which fit in correspondingly large fastener holes.

[0003] In order to ensure these holes are drilled accurately, and thereby fastened accurately, the wing skins and the gear rib need to be clamped together firmly at a location in close proximity to the proposed drilling site. However, due to their size, clamping these components presents a number of challenges. For instance, the closed section formed by the wing skins and the front and rear spar results in restricted access to the inside of the aircraft wing during assembly.

SUMMARY OF THE INVENTION

[0004] A first aspect of the invention provides a clamp having a pair of openable and closeable jaws for clamping either side of a stack of components, wherein a first jaw of the pair of jaws has a U-shaped first pressure plate at a distal end of the jaws, and a second jaw of the pair of] aws has a second pressure plate partially aligned with the first pressure plate when the jaws are closed for clamping either side of the stack of components [0005] The invention is advantageous in that the U-shaped first pressure plate can provide a high and substantially uniform clamping load around a fastener location or a row of fastener locations. The partial alignment of the first and second pressure plates can assist with applying clamping pressure in a region on one side of the stack of components even when space constraints would prevent the clamp from applying clamping load on the other side of the stack of components in that region, whilst clamping pressure on both sides of the stack can still be applied adjacent that region.

[0006] The first pressure plate may be shaped to provide a clamping load around a row of fastener locations [0007] The first pressure plate may define a central void for allowing tooling access to the row of fastener locations.

[0008] The U-shaped first pressure plate may include a pair of limbs projecting away from the distal end of the jaws [0009] The second pressure plate may include a pair of limbs projecting towards the distal end of the jaws.

[0010] The second pressure plate may define a central void between the pair of limbs [0011] The pair of limbs of the second pressure plate may have an extent which is shorter than an extent of the first pressure plate in the direction towards the distal end of the jaws [0012] The pair of j aws may be pivotally coupled.

[0013] A second aspect of the invention provides an automated one way assembly system for fastening together a stack of components, the system comprising the clamp of any preceding claim, a drilling module and a fastening module, wherein the drilling module is adapted to drill a hole through the stack of components and the fastening module is adapted to install a fastener in the hole to fasten the stack of components whilst the clamp applies a clamping load on either side of the stack of components [0014] The drilling module and the fastening module may be adapted to access the stack of components through a central void in the U-shaped first pressure plate of the clamp.

[0015] The clamp, the drilling module and the fastening module may each be positioned by computer control.

[0016] The system may be configured to drill a row of holes and then install a fastener in each hole whilst the clamp applies a clamping load on either side of the stack of components, and without removing the clamping load between the drilling and fastener installation steps [0017] A third aspect of the invention provides a method of automated one way assembly for fastening together a stack of components, the method comprising: a) applying a clamping load on either side of a stack of components using a clamp according to the first aspect; then b) drilling a row of holes in the stack of components by accessing the stack of components through a central void in the U-shaped first pressure plate of the clamp whilst the clamping load is applied; then c) installing a series of fasteners in the holes by accessing the stack of components through the central void in the U-shaped first pressure plate of the damp whilst the clamping load continues to be applied; and then d) removing the clamping load.

[0018] The steps of applying the clamping load, drilling the row of holes, and installing the series of fasteners may be under computer control.

[0019] The method may further comprise: moving the clamp from a first position around a first row of fastener locations to a second position around a second row of fastener locations then repeating steps a) -d).

[0020] The stack of components may include an aircraft wing cover and a gear rib [0021] The gear rib may include a web and flanges projecting from both sides of the web adjacent the wing cover, and the clamp may be positioned such that the first pressure plate extends over an outer surface of the wing cover such that the central void in the first pressure plate overlays both the gear rib flanges, and the second pressure plate extends over an inner surface of the wing cover up to the gear rib web.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [0023] Figure 1 shows an aircraft with landing gear attached to the wings, [0024] Figure 2 shows a region of the rear wing of an aircraft during assembly with the clamp applied during joining of the gear rib between the upper and lower wing skin covers; [0025] Figure 3 shows in detail the upper wing cover at the start of the drilling operation to join the wing cover to the gear rib, and the footprint of the clamp at the fastener locations; [0026] Figure 4 shows an aircraft wing during assembly, with the clamp held by a first robot arm, and a second robot arm having drilling and fastening heads.

[0027] Figures 5 and 6 show the clamp: [0028] Figures 7 to 9 show top plan, underneath plan and side views respectively of the clamp in operation around a wing skin cover and gear rib, [0029] Figure 10 shows a variant in which the first pressure plate of the clamp has a longer distal end to clamp around a longer row of fasteners; and [0030] Figure II shows a variant in which the pressure plate of the clamp is laterally offset from the jaws

DETAILED DESCRIPTION OF EMBODIMENT(S)

[0031] Figure 1 illustrates a typical fixed wing aircraft 1 having a port wing 2 and starboard wing 3 carrying wing mounted engines 9, the wings 2, 3 extending from a fuselage 4. The fuselage has a nose 5 and a tail 6 with horizontal and vertical stabilizer surfaces 7, 8 near the tail 6. The aircraft 1 is a typical jet passenger transonic transport aircraft but the invention is applicable to a wide variety of fixed-wing aircraft types, including commercial, military, passenger, cargo, jet, propeller, general aviation, etc. with any number of engines attached to the wings or fuselage.

[0032] Each wing 2, 3 has a cantilevered structure with a length extending in a spanwise direction from a root to a tip, the root being joined to the aircraft fuselage 4. A nose landing gear 10 is connected to the fuselage 4 near the nose 5. Main landing gear 11 are connected to each of the port and starboard wings 2, 3. The aircraft wing structure at the location where the top of the main landing gear 11 strut is connected to the wing structure is indicated by the box detail A in Figure 1.

[0033] The wings 2, 3 are similar in construction and so only the starboard wing 3 will be described in detail below. The wing 3 includes an upper skin cover 12, a rear spar 13, a front spar 14 and a lower skin cover 15. The upper and lower skin covers 12, 15 form the upper and lower aerodynamic surfaces respectively of the wing 3. The spars 13, 14 extend in a generally spanwise direction and a plurality of internal ribs each extend in a generally chordwise direction between the spars 13, 14 and generally vertically between the upper and lower wing covers 12, 15.

[0034] The ribs are spaced apart in the wing spanwise direction between an inboard rib, which forms the root of the wing there it joins with a centre wingbox structure of the body of the fuselage 4, and an outboard rib at the starboard wing tip. The ribs, spars 13, 14 and upper and lower wing covers 12, 15 together define the major components of the 'box' structure of the wing 3.

[0035] This wing box structure carries the major wing loads and defines an internal fuel carrying volume for storing the liquid fuel for feeding to the main engines 9. In line with the ribs which form the internal structure of the wing box, there are further ribs which project forwards of the front spar and yet further ribs which project rearwards from the rear spar. These further ribs support loads from leading and trailing edge flight control surfaces, loads from the engines 9 and loads from the main landing gear 11, amongst others [0036] Where the main landing gear 11 connects to the wing structure there is provided a strengthened and thickened region of the upper and lower wing covers 12, 15, and an aft rib, known as a 'gear rib' 16. The gear rib 16 is fastened to the rear spar 13 and is also fastened to the upper and lower skin covers 12, 15 [0037] It is desirable to manufacture the wing 3 in a 'one way assembly' process. One-way assembly involves the drilling and fastening of an assembly without an intermediate step of disassembly after drilling and prior to fastening. This intermediate step is typically required in other manufacturing operations in order to, e.g. debun-or otherwise prepare the drilling site in preparation for fastening. If a clamping force is not applied then one way assembly is typically not practical, as inter-laminar burring may occur during drilling and necessitate the disassembly and cleaning before reassembly and final fastening.

[0038] To enable one way assembly of the aircraft wing 3, all of the ribs and spars need to be drilled and fastened to the upper and lower skin covers 12, 15 without removing one or other of the skin covers once assembly has begun. If any one component of the primary wing structure cannot be assembled by this one way assembly process then the benefit of the one way assembly process of reducing build time cannot be realised.

[0039] The gear rib 16 is particularly challenging to incorporate into a one way assembly process for manufacturing the aircraft wing 3 for a number of reasons. Due to the loads transferred between the main landing gear 11 and the wing 3 the gear rib 16 and the adjacent regions of the upper and lower skin covers 12, 15 are reinforced and have relatively high material thickness through which relatively large diameter fasteners 17 must pass in order to fasten the gear rib 16 to the upper and lower skin covers 12, 15 [0040] Drilling relatively large diameter fastener holes at fastener locations 18 through the upper and lower skin covers 12, 15 and into flanges of the gear rib 16 requires a particularly high clamping load to be applied throughout the drilling and subsequent fastening at each fastener hole location 18. To achieve the clamping conditions required where access for the clamping, drilling and fastening operations is constrained, a clamp 20 having a pair of openable and closeable jaws 21 has been devised as best shown in figure 2.

[0041] Figure 3 illustrates a portion of the wing structure and shows a portion of the upper skin cover 12, the rear spar 13 and front spar 14, and the gear rib 16. The gear rib 16 generally comprises an upper flange 30, a lower flange 3], a web 32 extending between the upper flange 30 and the lower flange 31, a forward lug 33 and an aft clevis 34. The forward lug 33 and aft clevis 34 both project away from the gear rib web 32 in the aircraft wing inboard spanwise direction towards the wing root. The upper flange 30 and the lower flange 31 project both inboard and outboard in the aircraft wing spanw-ise direction away from the web 32 [0042] As can be seen in figure 3, the many fastener hole locations 18 are in the upper and lower flanges 30,31 on both sides of the web 32. In particular, a plurality of rows of fastener hole locations 18 are in the upper and lower flanges 30, 31 on the inboard side of the web 32 and a plurality of rows of fastener hole locations 18 are also provided in the upper and lower flanges 30, 31 on the outboard side of the web 32. Access to clamp in the vicinity of at least some of these fastener hole locations is constrained, especially in the region of the upper and lower flanges 30, 31 on the outboard side of the web 32.

[0043] Figure 4 illustrates an automated one way assembly system 40 for assembling the aircraft wing 3. The automated one way assembly system 40 includes a first robot 41 having the clamp 20 coupled to the end of the robotic arm, and a second robot 42 having a multi-functional positioning/ drilling/ fastening attachment 43 connected to the end of the arm of the second robot 42.

[0044] The positioning/ drilling/ fastening attachment 43 is configured to drill the fastener holes at locations 18 in the upper arid lower skin covers 12, 15 and in the upper and lower flanges 30, 31 of the gear rib 30 to a high positional accuracy, and then to install the fasteners 17 for fastening the gear rib 30 to the upper and lower skin covers 12, 15, all whilst the clamp 20 applies a desired clamping load to clamp the upper skin cover 12 to the upper gear rib flange 30, or to clamp the lower skin cover 15 to the lower gear rib flange 31 [0045] The clamp 20 will now be described in detail with particular reference to figures 5 and 6. The clamp 20 has the pair of openable and closeable jaws 21 including a first jaw 22 pivotally connected at pivot 23 to second jaw 24.

[0046] The second jaw 24 has a proximal end 24a fixedly connected to a base 25 having an end effector connection 26 for connecting to the first robot arm 41. The second jaw 24 has a distal end 24b opposite the proximal end 24a. The first jaw 22 has a proximal end 22a coupled to one end of a jack 27 which is mounted at its other end to the base 25.

[0047] The jack 27 may be driven by motor 28. The jack 27 may be a hydraulic jack. The first jaw 22 has a distal end 22b opposite the proximal end 22a. The pivot 23 is located intermediate the proximal ends 22a, 24a and the distal ends 22b, 24b of the first and second jaws 22, 24. Activation of the jack 27 causes a shortening or lengthening of the distance between the proximal ends 22a, 24a of the first and second jaws which, by rotation about the pivot 23, causes opening and closing of a gap between the distal ends 22b, 24b of the first and second jaws 22, 24.

[0048] As best shown in figure 6 the first jaw 22 has a U shaped first pressure plate 28 at the distal end 22b. The second jaw 24 has a second pressure plate 29 which is only partially aligned with the first pressure plate 28 when the jaws 21 are closed for clamping either side of a stack of components, e.g. the upper or lower skin covers 12, 15 and the flanges 30, 31 of the gear rib 16. The partial alignment of the first and second pressure plates 28, 29 may relate to the partial overlap of the first and second pressure plates 28, 29 in the direction normal to the surfaces of those pressure plates 28, 29 which contact either side of the stack of components.

[0049] As best shown in figure 7, which is a plan view from above of the clamp 20 engaged to clamp the upper skin cover 12 and the gear rib 16 it can be seen that the first pressure plate 28 is shaped to provide a clamping load around a row of fastener locations 18. In an illustrated example the distal end 22b of the first jaw 22 of the pair of j aws 21 projects over the upper skin cover 12 so that the U shaped first pressure plate 28 at least partially surrounds a row of fastener locations 18.

[0050] The first pressure plate 28 defines a central void 28a bounded at least partially by the U-shaped first pressure plate 28. This central void 28a provides an unobstructed path for tooling to the fastener locations 18 enclosed by the pressure plate 28 towards the component, e.g. the upper skin cover 12, with which the first pressure plate 28 is in contact. The U shaped first pressure plate 28 is configured to provide a substantially uniform clamping pressure around the fastener hole 18 nearest the distal end of the jaws 21 of the row of fastener locations 18 enclosed by the first pressure plate 28.

[0051] The first pressure plate 28 has a generally U shaped distal end 28b and a pair of limbs 28c arranged generally parallel to one another and which project away from the distal end of the jaws 21. The generally parallel limbs 28c of the first pressure plate 28 extend alongside and are spaced substantially equidistantly from the row of fastener locations 18 positioned within the central void 28a of the first pressure plate 28 when the clamp 20 is pressed against the component, e.g. the upper skin cover 12.

[0052] The second pressure plate 29 has a pair of limbs 29a spaced generally parallel and equidistantly on either side of the row of fasteners 18 on the other side of the stack of components, e.g. the upper skin cover 12 and gear rib 16 serves to define a central void 29b between the pair of limbs 29a, as best shown in figures 6 and 8.

[0053] The pair of limbs 29a of the second pressure plate 29 may be aligned with the pair of limbs 28c of the first pressure plate 28. The alignment of the pairs of limbs 29a, 28c may be such that the full extent of the length of the limbs 29a are aligned with at least a portion of the limbs 28c of the first pressure plate 28 such that the first pressure plate frilly overlaps the second pressure plate 29 in the direction normal to the contact surfaces of the first and second pressure plates when the jaws 21 of the clamp 20 are closed.

[0054] The pair of limbs 29a of the second pressure plate 29 may have an extent which is shorter than the extent of the first pressure plate 28 in the direction towards the distal end of the jaws 21 As best shown in figure 8 the shortened extent of the second jaw 29 to extend over as great a distance as possible of the flange 30 of the gear rib 16 but without the distal end 29c of the second jaw 29 clashing with the web 32 of the gear rib [0055] As can be seen in figure 8 the rows of fastener locations 18 extend on the flange 30 of the gear rib 16 on both sides of the gear rib web 32 but the second jaw 29 of the clamp 20 extends alongside the row of fastener locations 18 over the gear rib flange 30 on one side of the web 32 With both the first and second jaws 22,24 the first and second pressure plates 28, 29 are adapted to apply the clamping pressure to the stack of components 12, 16 at a predetermined minimum clearance from the centre of the fastener hole locations 18 [0056] Returning to figure 4, the automated one way assembly system 40 and its method of operation will now be described in detail. In particular, the multifunctional positioning / drilling / fastening module 43 attached to the arm of the second robot 42 is adapted to access the stack of components, 12, 16 or 15, 16, through the central void 28a in the first pressure plate 28 of the clamp 20. Movement of the robot and operation of the multifunctional drilling and fastening module 43 are positioned by computer control. A vision system may be incorporated within the system 40 for positioning the clamp 20 and/or the drilling module and fastening module 43.

[0057] The positioning system, e.g. the vision system may be located by referencing a datum from one or more components of the aircraft wing assembly 3, e.g. from the hinge axis through the lug 33 and clevis 34 of the gear rib 16. The clearance provided by the second pressure plate 28, 29 away from the fastener hole locations 18 means that positioning the clamp 20 does not require especially high accuracy, although improved accuracy of positioning the clamp 20 may aid the application of a uniform clamping pressure around the fastener hole location.

[0058] Once the clamp 20 is brought into position and closed to clamp on either side of the stack of components, e.g. the upper skin cover 12 and gear rib 16, around a row of fastener hole locations 18 the drilling module will then drill one or more holes in the stack of components 12, 16 by accessing the stack of components through the central void 28a in the U shaped pressure plate 28 of the clamp 20 whilst the clamping load is applied.

[0059] The fastening module of the system 43 attached to the second robot 42 will then install a respective fastener 17 in each hole drilled by the drilling module of the system 43. The fasteners 17 are installed by accessing the stack of components 12, 16 through the central void 28a in the U shaped first pressure plate 28 of the clamp 20 whilst the clamping load continues to be applied.

[0060] In the region bounded by the first pressure plate 28 either all of the fastener holes 18 in the row may be drilled and then the fasteners 17 installed in each of the respective holes drilled, or each hole 18 may be drilled and the fastener 17 installed before the next hole is drilled. Once all of the fasteners 17 have been installed in the region bounded by the first pressure plate 28 only then is the clamping load applied by the clamp 20 removed [0061] In the example shown in figure 7 where the row of fastener hole locations 18 bounded by the first pressure plate 28 includes 3 fastener hole locations then the middle hole 18 of the row of three holes may be drilled first followed sequentially by the other two holes 18 on either side of the middle hole. If the number of fastener hole locations bounded by the first pressure plate 28 is four or more, then one of the middle holes in the row may be drilled first and then the other holes may be drilled in sequence extending away from the middle hole.

[0062] As can be seen in figure 7, the joint for fastening the stack of components 12, 16 comprises a plurality of rows of fastener locations 18. The clamp 20 may initially be positioned around a middle row of the array of fastener locations and once the fastener holes 18 have been drilled and the fasteners 17 installed in that first row then the clamp 20 may be removed and repositioned around the next adjacent row of fastener locations to repeat the drilling and fastening operations. This process of clamping, drilling and fastening prior to removing the clamp then continues for each of the rows of fastener locations progressing sequentially away from the middle row of fastener locations until all of the rows of fasteners 17 have been installed.

[0063] Of course, it will be appreciated that depending on requirements the selection of which hole in a row of fasteners should be drilled first and which row of fasteners in an array of fastener locations should be made first may vary.

[0064] Figure 10 illustrates a first variant in which the clamp 20' is identical to the clamp 20 described previously which the exception that the first pressure plate 28' has an extent in the direction towards the distal end of the jaws 21 which is longer than the extent of the first pressure plate 28 of the clamp 20 so that the first pressure plate 28' of the clamp 20' extends over the upper skin cover 12 so as to surround all of the fastener locations in one row of the array of fastener locations 18. Figure 9 illustrates the corresponding side view of the clamp 20' in operation [0065] To clamp the lower skin cover 15 and the lower flange 31 of the gear rib 16, the clamp may be rotated 180 degrees on the arm of the robot 42, so that the first pressure plate 28 engages the outer surface of the lower skin cover 15 and the second pressure plate 29 engages the lower flange 31, for drilling and installing fasteners in the fastener locations 18 to join the lower skin cover 15 to the gear rib 16.

[0066] Figure 11 illustrates a further variant in which the clamp 20-has the first pressure plate 28" offset to one side of the distal end 22b of the first jaw 22. The second jaw 24 has a second pressure plate 29-which is similarly offset to one side of the second jaw 24 such that the second pressure plate 29" is again partially aligned with the first pressure plate 28" when the jaws 21 are closed for clamping either side of the stack of components.

[0067] When installing the fastener 17 in each of the fastener holes 18 the automated fastener installation may comprise measuring the stack thickness of the components through which each individual fastener 17 is to be installed. Once the stack thickness at the respective fastener location has been measured, a fastener of appropriate length may be selected. Automated sealant application may be required around the countersink of the hole drilled at the respective fastener location 18. The automated fastener installation may comprise torque tightening of the respective fastener to a predetermined torque tightened load appropriate for each fastener location and/or each selected fastener length.

[0068] The drilling module and fastening module controlled by the second robot 42 may be an integrated drilling and fastening system 43 or alternatively the second robot 42 may select either a drilling module or a fastening module for performing the required operation. The positional accuracy of the drilling module for drilling the holes 18 at the respective fastener locations may be achieved to a high positional accuracy using an appropriate vision system. The accuracy of the drilling module may be higher than that of the clamp 20 controlled by the first robot 41.

[0069] The clamp 20 incorporated in an automated one-way assembly system 40 for fastening together a stack of components may compliment other tooling used in a one way assembly process for manufacturing an entire assembly or sub-assembly of components, such as an aircraft wing, or other aircraft structure, or any other complex structure in manufacturing. The fastener 17 may be installed from only one side of the stack of components if one sided fasteners are used, or alternatively the fastener 17 may be installed from both sides of the stack of components if two sided fasteners are to be used. The clamp 20 may apply a maximum load of up to around 80 k_N.

[0070] Where the word 'or' appears this is to be construed to mean 'and/or' such that items referred to are not necessarily mutually exclusive and may be used in any appropriate combination.

[0071] 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

CLAINIS1 A clamp having a pair of openable and closeable jaws for clamping either side of a stack of components, wherein a first jaw of the pair of jaws has a U-shaped first pressure plate at a distal end of the jaws, and a second jaw of the pair ofjaws has a second pressure plate partially aligned with the first pressure plate when the jaws are closed for clamping either side of the stack of components.
2 A clamp according to claim 1, wherein the first pressure plate is shaped to provide a damping load around a row of fastener locations.
3 A clamp according to claim 2, wherein the first pressure plate defines a central void for allowing tooling access to the row of fastener locations 4 A clamp according to any preceding claim, wherein the U-shaped first pressure plate includes a pair of limbs projecting away from the distal end of the jaws.A clamp according to any preceding claim, wherein the second pressure plate includes a pair of limbs projecting towards the distal end of the jaws.6 A clamp according to claim 5, wherein the second pressure plate defines a central void between the pair of limbs 7 A clamp according to claim 5 or 6, wherein the pair of limbs of the second pressure plate have an extent which is shorter than an extent of the first pressure plate in the direction towards the distal end of the jaws.8 A clamp according to any preceding claim, wherein the pair ofjaws are pivotally coupled.9 An automated one way assembly system for fastening together a stack of components, the system comprising the clamp of any preceding claim, a drilling module and a fastening module, wherein the drilling module is adapted to drill a hole through the stack of components and the fastening module is adapted to install a fastener in the hole to fasten the stack of components whilst the clamp applies a clamping load on either side of the stack of components.A system according to claim 9, wherein the drilling module and the fastening module are adapted to access the stack of components through a central void in the U-shaped first pressure plate of the clamp.11 A system according to claim 9 or claim 10, wherein the clamp, the drilling module and the fastening module are each positioned by computer control.12 A system according to any of claims 9 to 11, wherein the system is configured to drill a row of holes and then install a fastener in each hole whilst the clamp applies a clamping load on either side of the stack of components, and without removing the clamping load between the drilling and fastener installation steps.13 A method of automated one way assembly for fastening together a stack of components, the method comprising: a) applying a clamping load on either side of a stack of components using a clamp according to any of claims 1 to 8; then b) drilling a row of holes in the stack of components by accessing the stack of components through a central void in the U-shaped first pressure plate of the clamp whilst the clamping load is applied; then c) installing a series of fasteners in the holes by accessing the stack of components through the central void in the U-shaped first pressure plate of the clamp whilst the clamping load continues to be applied; and then d) removing the clamping load 14 A method according to claim 13, wherein the steps of applying the clamping load, drilling the row of holes, and installing the series of fasteners are under computer control.A method according to claim 13 or claim 14, further comprising: moving the clamp from a first position around a first row of fastener locations to a second position around a second row of fastener locations then repeating steps a) -d).16 A method according to any of claims 13 to 15, wherein the stack of components includes an aircraft wing cover and a gear rib.17 A method according to claim 16, wherein the gear rib includes a web and flanges projecting from both sides of the web adjacent the wing cover, and the clamp is positioned such that the first pressure plate extends over an outer surface of the wing cover such that the central void in the first pressure plate overlays both the gear rib flanges, and the second pressure plate extends over an inner surface of the wing cover up to the gear rib web.