GB2590675A

GB2590675A - A clamping apparatus

Info

Publication number: GB2590675A
Application number: GB1919232.7A
Authority: GB
Inventors: Jackson Anthony; Liaqat Amer; Land Patrick; Cantle David; Clarke Jamie; Janik Karol
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: GB201919232D0

Abstract

The clamping apparatus includes a hexapod 40 having a base 42 and a clamping surface 51. A controller is arranged to control the hexapod. The controller is configured to control the hexapod such that the clamping surface is moveable so as to face normal to a surface of a first component (13, Figure 10b) and be pressed against the surface of the first component. The first component may be a skin cover (14, Figure 4) of an aircraft wing (2, Figure 1). The clamping surface may include an opening (56, Figure 7) for a tool. A drilling tool (31a, Figure 10d) may drill the component whilst the clamping surface is pressed against it. A fastening tool (31b, Figure 10g) may install a fastener for fastening the first component to a second component. A sensor, such as an x-ray backscatter device 60, may be used to determine a datum from a scan of the first and/or second component. The datum is used for positioning a tool and/or controlling the movement of the hexapod.

Description

A CLAMPING APPARATUS FIELD OF THE INVENTION

[0001] The present invention relates to a clamping apparatus, and a method of assembly using a hexapod.

BACKGROUND OF THE INVENTION

[0002] Aircraft wings are closed sections, typically enclosing a series of ribs between upper and lower skin covers. Typically, the ribs are attached to the wings after the skin covers are enclosed to form the closed section by drilling through the wing skin and into the foot of the rib.

[0003] In order to ensure holes are drilled accurately, and thereby fastened accurately, the wing skin and ribs need to be clamped together firmly at a location in close proximity to the proposed drilling site. However, clamping these components presents a number of challenges. For instance, the closed section formed by the wing skins results in restricted access to the inside of the aircraft assembly, making it difficult to clamp from both sides of the wing skin. A wing skin also typically has a curved surface, such that it is firstly difficult to orientate the clamp normal to the wing skin surface, and secondly difficult to apply the clamping force normal to the wing skin surface.

SUMMARY OF THE INVENTION

[0004] A first aspect of the invention provides a clamping apparatus comprising: a hexapod including a base and a clamping surface; a controller arranged to control the hexapod, wherein the controller is configured to control the hexapod such that the clamping surface is moveable so as to face normal to a surface of a first component and be pressed against the surface of the first component.

[0005] A further aspect of the invention provides a method of assembly using a hexapod, the hexapod comprising a base and a clamping surface, the method comprising: orientating the clamping surface relative to the base and normal to a surface of a first component; extending the clamping surface to press against the first component pressing the clamping surface against the surface of the first component.

[0006] A hexapod (also referred to as a Stewart platform, Gough-Stewart platform, 6-DoF platform, or six-axis platform) is a type of jack that provides up to six-degrees of freedom to a top plate relative to a bottom plate. The hexapod can provide a positional accuracy of up to 0.001mm. The degrees of freedom are provided by an arrangement of six actuators, which are generally attached in pairs between the top and bottom plates. Controlling the relative movement of each actuator allows the rotation and translation of the top plate to be determined. A hexapod is therefore able to accurately control its angle and extension using a compact form, in contrast to, e.g., a standard Cartesian machine that is impractically large.

[0007] By orienting the clamping surface relative to the first component and pressing against the surface of the component at a bespoke angle and from a bespoke direction, the first component can be stabilised by the clamping surface in order to improve the accuracy of e.g., drilling and fastening operations. The hexapods six degrees of freedom allow the clamping surface to be oriented into a configuration that maximises the stability of the component without the need to clamp the component from both sides.

[0008] As a result, one-sided operations can be performed, such as drilling and fastening, without needing access to the blind side (i.e. opposing side) of the component.

[0009] A hexapod, due at least to the six degrees of freedom provided to the top plate (clamping surface), is able to apply a force at any desirable vector. This contrasts it to a clamp with a rotatable top plate with only, e.g., vertical movement of the top plate, as the force can only be applied in one direction even if the clamping surface is orientated normal to the surface to be clamped.

[0010] The clamping surface may be configured to be pressed against the surface of the first component to clamp the first component against a second component.

[0011] Clamping is defined as holding one item tightly against another item. Clamping can be permanent or temporary.

[0012] The clamping force can be applied in such a way as to minimise 'chase' between the two components. In other words, undesirable relative movement between the first and second components can be minimised [0013] By using a hexapod to carefully control the clamping surface, one way assembly is achievable with high accuracy and quality possible whilst simultaneously reducing build time and allowing light weight low-cost automation. One way assembly involves the drilling and fastening of an assembly without an intermediate step of disassembling after drilling. This intermediate step is typically required in other manufacturing operations in order to, e.g., deburr 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 interlaminar burring may occur and necessitate the disassembly and cleaning before final fastening.

[0014] The clamping surface may be configured to be pressed normal to the surface of a first component. The clamping surface may be configured to be pressed normal to the surface of a first component after moving the clamping surface to face normal to the surface of the first component. Applying the clamping force normal to the surface typically ensures that any undesirable relative movement between the components is minimised.

[0015] The clamping surface may include an opening for a tool. The opening may be configured to provide access to the surface of the first component through the opening in the clamping surface when the clamping surface is pressed against the surface of the first component. The opening may be a hole, or a slot. With this arrangement, the tool can operate on the component(s) at the clamping location whilst they are clamped together.

[0016] The damping apparatus may further comprise a drilling tool configured to drill the first component whilst the clamping surface is pressed against the first component.

[0017] The clamping apparatus may further comprise a fastening tool configured to install a fastener for fastening the first and second components together whilst the clamping surface is pressed against the first component.

[0018] The clamping surface may be configured to be pressed continuously against the surface of the first component whilst the first component is drilled by the drilling tool and the fastening tool installs a fastener. This ensures that no gap appears between the components between the drilling and fastening operations, which may otherwise allow undesirable deburring to migrate between the two components. Alternatively, the clamping may reduce the gap to an acceptable and/or desired amount. Continuously clamping the two components together may also assist in minimising any misalignment that occurs between the two components after drilling and prior to fastening.

[0019] The clamping apparatus may further comprise a part placement head configured to move a part relative to first component whilst the clamping surface is pressed against the first component.

[0020] The clamping apparatus may further comprise a sensor device configured to scan the first and/or second component, and a controller configured to receive information from the sensor device and to determine a datum from the information. With this arrangement, the position of the apparatus and tooling can be determined accurately in relation to the components [0021] The sensor device may be an x-ray backscatter device. The controller may receive information relating to the backscattered x-rays from the x-ray backscatter device in order to determine the datum. This allows the datum to be determined when access to only one side of a component is available. As a result, one-sided operations can be performed, such as drilling and fastening, without needing access to the blind side (i.e, opposing side) of the component. This can eliminate the need to have a person make a pilot hole from the opposing side, or putting a through-thickness sensor (TSS) target on the opposing side, both of which can be difficult when access to the opposing side is restricted. There is also no need to have any tools or sensors on the inside of, e.g., a wing, which may otherwise be inadvertently left behind.

[0022] The clamping apparatus may further comprise a computer configured to process the information from the x-ray backscatter device in order to produce an image of the first and/or second component, wherein the image is for used in determining the datum.

[0023] The datum may be used for positioning a tool and/or controlling the movement of the hexapod. The position of the tool(s) and/or hexapod can thereby be determined by the information obtained from the blind side of the components. The tool may be a drilling tool, a fastening tool, or part placement head.

[0024] The damping surface may be substantially rigid.

[0025] The clamping apparatus may be configured to apply a first clamping force in a first direction towards the component, and wherein the clamping apparatus is not configured to apply a second clamping force that substantially opposes the first clamping force [0026] In other words, the clamping surface applies a clamping force against the surface of the first component (e.g. on a first side of the component), but there is no reciprocal second clamping surface positioned on the other side of the component (e.g. on a second side of the component) that counteracts the clamping force applied by the clamping surface. This is beneficial if there is restricted access to one side of an assembly, for example the component may form part of a wing assembly forming a closed section.

[0027] The first component may be shaped such that access to the second component is restricted. The first component may be shaped such that access to the second side of the first component is restricted. The components may form a closed section such that access to the inner side of the closed section is restricted.

[0028] The step of pressing the clamping surface against the surface of the first component may involve pressing to clamp the first component against a second component.

[0029] The step of pressing the clamping surface against the surface of the first component may involve pressing normal to the surface of the first component.

[0030] The method may further comprise a sensor device. The method may further comprise the steps of scanning the first and/or second components with a sensor device; and determining a datum on the first and/or second component based on information received from the sensor device [0031] The sensor device may be an x-ray backscatter device, and the step of scanning may further comprise: positioning the x-ray backscatter device adjacent the first component; emitting x-rays from the device towards the first and second component, wherein x-rays are backscattered the first and second component towards the device.

[0032] The step of orientating the clamping surface relative to the base and normal to the surface of a first component may be based on the datum.

[0033] The method may further comprise a tool. The tool may be a drilling tool. The method may further comprise: drilling into the first component and/or second component after the first component is clamped against the second component.

[0034] The tool may be a fastening tool. The method may further comprise: inserting a fastener into the first component and/or second component after the first component is clamped against the second component.

[0035] The tool may be a part placement tool. The method may further comprise: moving a part onto the first component using the part placement head after the first component is clamped against the second component.

[0036] The datum may be used to adjust the position of the tool relative to the first and/or second component.

[0037] The method may further comprise: determining a magnitude of a clamping force, wherein the step of pressing the clamping surface against the first component is based on the determined clamping force [0038] The first component may comprise an aircraft wing skin and the second component comprise a rib foot.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [0040] Figure 1 shows a plan view of an aircraft; [0041] Figure 2 shows a plan view of the starboard wing of the aircraft; [0042] Figure 3 shows a wing box structure at a rib location viewed in the spanwi se direction, [0043] Figure 4 shows the wing box structure at a rib location viewed in the chordwise direction; [0044] Figure 5 shows an apparatus according to a first example of theinvention; [0045] Figure 6 shows a schematic representation of a hexapod; [0046] Figure 7 shows the hexapod with a clamping fixture attached; [0047] Figure 8 shows a side view of the apparatus according to a first example of the invention, and (inset) a side view of the hexapod and clamping fixture: [0048] Figure 9 shows a robot arm mounted on a platform, [0049] Figures 10a-h show a method of assembling a rib foot to a lower wing skin cover; [0050] Figures ii a-b show a method of adjusting the position of a tool using an x-ray backscatter device; [0051] Figure 12a-b shows an x-ray backscatter device and a drilling tool attached to the clamping fixture; [0052] Figures 13a-b show a method of positioning an x-ray backscatter device with a robot arm; [0053] Figures 14a-b show a method of attaching a bracket to the outside of a cover relative to a rib foot on an inside of the cover.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[0054] Figure 1 illustrates a typical fixed wing aircraft I 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 stabiliser 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.

[0055] Each wing 2, 3 has a cantilevered structure with a length extending in a span-wise direction from a root to a tip, the root being joined to an aircraft fuselage 4. The wings 2, 3 are similar in construction so only the starboard wing 3 will be described in detail with reference to Figure 2 [0056] The aircraft 1 includes a centre wing box 10 within the body of the fuselage 4. The centre wing box 10 is joined to an inboard rib 15a which forms the root of the wing 3. The wing 3 includes a series of evenly spaced ribs 15 between the inboard rib 15a and an outboard rib 15b at the starboard wing tip. The ribs 15, 15a, 15b form part of a wing box on the starboard wing 3, wherein the wing box shown in Figure 3 also includes a front spar 11, an upper skin cover 12, a rear spar 13, and a lower skin cover 14. A rib 15 attaches to the front spar and rear spar 11, 13 using brackets 16, as well as to the upper and lower skin covers 12, 14 using brackets 16. The brackets 16 are alternatively referred to as rib feet 16.

[0057] In the assembled wing 3, the rib 15 is typically coupled to each of the front spar 11, rear spar 13, upper skin cover 12 and lower skin cover 14. The lower skin cover 14 is typically the last component to be attached to the wing 3, and in doing so the wing box structure forms a closed section with each rib 15 enclosed inside. Each spar 11, 13 and each skin cover 12, 14 thereby has an inner and an outer surface, with the lower wing skin cover 14 having an inner surface 141 and an outer surface 141.

[0058] Assembly of the lower wing cover 14 to each of the ribs 15 can be challenging, as access to the inside of the wing box structure, and in particular the rib feet 16 and inner side 141 of the lower wing skin 14, is limited. As a result, a person may be needed to climb through the inside of the wing 3, so that a pilot hole can be drilled from the inside of the wing 3 at the correct location, or a sensor device used in combination with a sensor that can be fitted to the inside the wing 3. The pilot hole or sensor can then be used to guide a drill, or other tool, from the outside of the wing 3. It is also challenging to clamp the joint/assembly in such a closed section wing structure. For example, there is the problem of clamping the lower wing skin 14 to the rib feet 16 in order to reduce any gaps that exist between them before drilling/fastening. Solutions may include designing a bespoke shaped clamping device that is contoured to the shape of the wing skin, or a pliable clamp that wraps around the entire wing profile. This can be particularly challenging, as the wing skins 12, 14 typically have complex curvature, wherein the surface has curvature in two orthogonal directions.

[0059] Figure 5 shows an apparatus according to a first example of the invention. The apparatus includes a platform 20 fixed to a floor using fasteners 21. The platform 20 has linear tracks 22 located on its top surface extending in the x-direction (with reference to the axes shown in Figure 5). Positioned on the linear tracks 22 of the platform 20, and able to move linearly along the tracks 22, on followers 23, is a vertical stage 24 (alternatively known as a Z-stage) that is able to extend upwards (z-direction indicated in Figure 5) relative to the platform 20 [0060] Mounted on top of the vertical stage 24 is a hexapod 40 (which will be described in more detail below in reference to Figure 6) that is able to provide multi-axial rotation and translation to a top plate 43 of the hexapod 40 [0061] A hexapod 40 (also referred to as a Stewart platform, Gough-Stewart platform, 6-DoF platform, or six-axis platform) is a type of jack in which the top plate 43 is provided six-degrees of freedom to rotate and translate relative to a base plate 42. The degrees of freedom are provided by an arrangement of six actuators 44a, 44b, 44c, 44d, 44e, 44f, such as hydraulic or electric linear actuators, which are generally attached in pairs in an arrangement similar to that shown in Figure 6.

[0062] The degrees of freedom of the hexapod 40 include three linear movements (i.e. lateral, longitudinal, and vertical movement), as well as three rotational movements (i.e. pitch, roll, and yaw) [0063] The top plate 43 supports a clamping fixture 50 that is fixed on top of the top plate 43 The clamping fixture 50 is arranged on top of the hexapod 40 so that the clamping fixture 50 can be pressed against a surface by adjusting the hexapod 40, for example the clamping fixture 50 may be pressed against the outer surface 14J of the lower wing skin 14 by adjusting the hexapod 40.

[0064] The clamping fixture 50 is shown in Figure 7 in more detail. The clamping fixture 50 has top and base plates 51, 52, with the base plate 52 adjacent the top plate 43 of the hexapod 40. The clamping fixture 50 also has a support structure 55 extending between the top and base plates 51, 52.

[0065] A space 53 is provided in the area between the top and base plates 51, 52 and the support structure 55, as shown in Figure 8. The space 53 allows, for example, a robot arm 28 (shown in Figure 8 and in Figures 9a-h) or other device to access the lower side of the top plate 51. The top plate 51 includes an aperture 56 through which the robot arm 28 can insert a tool 31. The base plate 52 of the clamping fixture 50 also includes an aperture 57, as does the top plate 43 of the hexapod 40, which may be used to provide access for the insertion of a tool 31 (shown in Figures 9a-h).

[0066] The clamping fixture 50 also includes a scanner device 60, such as an x-ray backscatter device 60, attached to the top plate 51 so that the working face of the scanner faces outwards, away from the platform 20 [0067] A robot 26 is shown in Figure 9. The robot 26 has a robot arm 28 extending from a body 27, wherein the body 27 is mounted on a second vertical stage 25 that is substantially the same as the first vertical stage 24 and is positioned adjacent to the first vertical stage 24. The second vertical stage 25 is mounted on the platform 20, and is located on the linear tracks 22 of the platform 20. The robot arm 28 holds a tool 31 on the end of the arm 28 and is able to rotate and translate relative to the body 27 and the vertical stage 24. The robot arm 28 is configured to carry different tools depending on the required task, for example a drilling tool 31a (Figure 9d) or a fastening tool 3 lb (Figure 9g). It will be clear that the robot arm 28 may be arranged to hold any suitable required tool 31, component or item of equipment.

[0068] The robot arm 28 typically provides 6-degrees of freedom to the tool 31, relative to the body 27, however the robot may have different degrees of freedom in other examples [0069] In alternative examples, the apparatus may include a tool 31 coupled to the clamping fixture 50. This is an alternative to the use of a robot arm 28 to hold a tool 31, but may be in addition to the robot arm 28, such that a first tool 31 is coupled to the clamping fixture 50, and a second tool 31 is held by a robot arm 28 [0070] The apparatus will now be described, in Figures 10a-10h, in relation to the drilling and fastening of a lower wing skin cover 14 to a rib foot 16. Only the robot arm 28 and the top plate 51 of the clamping fixture 50 are shown for clarity.

[0071] Figure 10a shows a rib foot 16 attached to a rib 15. A small gap exists between the rib foot 16 and the inner surface 141 of a lower wing skin 14. The apparatus operates by moving the platform 20 into the approximate location of the rib foot 16, so that the first vertical stage 24 is beneath the rib foot 16 and the top plate 51 of the clamping fixture 50 is adjacent the rib foot 16 location.

[0072] Adjustments are then made to the top plate 51 via the hexapod 40. As the top plate 43 of the hexapod 40 is fixed and parallel relative to the top plate 51 of the clamping fixture, any adjustments to the top plate 43 of the hexapod 40 are replicated by the top plate 51 of the clamping fixture 50. Therefore, the top plate 51 is translated and rotated (via adjustments to the hexapod 40) such that its top surface is normal to the location to be drilled/fastened, as shown in Figure 10b.

[0073] The top plate 51 is then pressed against the outer surface 1 4J of the lower wing skin cover 14, so as to close any gaps between the skin 14 and rib foot 16 (as shown in Figure 10c), with the aperture 56 of the top plate 51 centred on the location to the drilled. In an alternative example, the top plate 51 may not be orientated so that its top surface is normal to the location to be drilled/fastened when the top plate 51 is pressed against the lower wing skin cover 14, instead the top plate 51 may initially be misaligned with the surface of the wing skin 14 to which it is pressed, and then the top plate Si orientation adjusted at the same time that it is pressed against the wing skin 14.

[0074] In reference to Figures 10d-10f, a drilling tool 3 la, attached to the end of the robot arm 28 and mounted on the platform 20, is brought beneath the top plate 51 and oriented normal to the wing skin 14. The robot arm 28 inserts the drilling tool 31a through the aperture 56 in the top plate so as to drill through the lower wing skin 14 and the rib foot 16. The drilling tool 31a is then removed to reveal the drilled hole 33.

[0075] The robot arm 28 returns to a tool station (not shown) and replaces the drilling tool 31a with a fastening tool 31b. As in relation to the drilling tool 31, the fastening tool 31 is brought beneath the top plate 51 and oriented normal to the wing skin 14. A fastener 35 is inserted into the drilled hole 33 by the fastening tool 31b so as to secure the lower wing skin 14 to the rib foot 16.

[0076] During this operation the clamping force provided by the clamping fixture 50 and the hexapod 40 arrangement is maintained, so that any gap between the wing skin 14 and rib foot 16 is minimised throughout the drilling and fastening procedure and the interval between the drilling and fastening procedures. In alternative examples the clamping force may be released after the wing skin 14 and rib foot 16 are drilled, and then reapplied prior to fastening the wing skin 14 and rib foot 16.

[0077] The location that the hole is to be drilled, and by extension the location of the fastener 35 placed into the hole, needs to be determined accurately to ensure that the fastener joint is as strong as possible and positioned optimally. For example, the fastener 35 may be placed in the middle of the lower flange of the rib foot 16 away from the edges of the rib foot 16.

[0078] The location of the hole to be drilled can be determined in a number of ways As previously discussed, a pilot hole may be drilled from the inside of the wing 3 at the correct location, and/or a sensor can be fitted to the inside the wing 3 These methods have many associated disadvantages, such as the need to operate from the inside of the wing 3.

[0079] One-sided assembly, wherein all assembly operations are performed from a single side of the assembly, may provide significantly quicker assembly times. One way in which this can be satisfactorily achieved is to use an x-ray backscatter device 60, such as the device 60 shown in Figure 5 attached to the clamping fixture 50.

[0080] Figures 1 la-c show a method, performed prior to the assembly method of Figures 10a-h, in which a datum position can be determined without requiring physical access to the inner surface 141 of the wing 3, such that one-sided assembly can be achieved.

[0081] The method uses an x-ray backscatter device 60. The x-ray backscatter device 60 is a device that detects the radiation that reflects from the target when x-rays are emitted towards an object. It has benefits over traditional x-ray machines in that it can analyse an object even if only one side of the target is visible.

[0082] In the analysis of the lower wing skin 14 and rib foot 16 shown in Figures 1 lab, the x-ray backscatter device 60 is coupled to the top plate 51 of the clamping fixture 50 (as described in relation to Figure 5). However, it will be apparent that the x-ray backscatter device may not be coupled to the clamping fixture 50. Alternatively the x-ray backscatter device 60 may be a handheld device or held on an arm such as a robot arm 28.

[0083] The top plate 51 of the clamping fixture is adjusted via the hexapod 40, as shown previously in Figure 5, such that the x-ray backscatter device 60 is positioned adjacent the outer surface 14J of the wing skin 14 and directed normal to the outer surface 14J of the wing skin 14. X-rays 61 are emitted from the device 60 towards the lower wing skin cover 14, directed towards the outer surface 14T of the wing skin 14 [0084] The device 60 is moved across an area of interest so that an extended area can be analysed. At least some of the x-rays 61 penetrate through the lower skin 14 and are backscattered 62 from the rib 15 and rib foot 16, as well as the lower skin 14, back to the device 60, thereby providing cross-sectional 2D information on the components.

[0085] The backscattered x-rays are detected by the x-ray backscatter device 60, and can be used to analyse the components 14, 15, 16, for example by reconstructing an image of the components. In this particular example, the information obtained from the backscattered x-rays is used to detect a datum on one of the parts or between the parts (for example, a datum on the lower wing skin 14, rib 15, or rib foot 16) that can be used to position a tool 31 into a suitable position for machining, or performing a different operation such as fastening. The datum may be located at a minimum distance from a feature, such as the edge of the rib foot 16, or may be a detected feature, such as the edge of the rib foot 16.

[0086] To do this, the x-ray backscatter device 60 is connected to a computer 70. The computer 70 receives information relating to the backscattered x-rays from the x-ray backscatter device 60 along a first communication line 71. The computer 70 is then able to automatically detect a datum from the received information, or allow a user to manually determine a datum.

[0087] In order to assist in the detection/identification of a datum, the computer may process the information on the backscattered x-rays to produce a digital image of the components.

[0088] The detected datum can then be used to adjust the position of a tool 31, such as a drilling tool 31a, on the outside surface 14J of the wing skin 14 (as shown in Figure 11b) based on, for example, the position of the rib foot 16 adjacent the inner surface 141 of the wing skin 14. For example, the computer 70 can provide the function of a controller, sending a command signal along a second communication line 72 in order to direct the robot arm 28. In this way, the drilling and/or fastening operation can be performed at precisely the required location without having to physically access the inner surface 14I of the wing skin 14 [0089] In the particular example shown in Figures 11a-b the x-ray backscatter device is moved during its scan of the components, so that a wide region can be analysed. In alternative examples, the x-ray backscatter device 60 may be fixed relative to the components whilst it emits x-rays.

[0090] The position of the tool 31 relative to the datum should be known in order that the information collected from the backscattered x-rays can be used to determine a datum point, and therefore a tool 31 can be adjusted relative to that datum. The accuracy of the estimated tool position to the actual tool position determines the tolerances that can be achieved with the current apparatus.

[0091] The datum is determined based on information gathered by the x-ray backscatter device 60. For example, the backscattered x-rays may provide information relevant to the geometry or material properties of the components that can be analysed to determine a datum position. The datum may be a hole, for example a hole in the rib foot 16. The datum may be a point between two detected edges or regions, and/or the mid-point of a region in which a change in thickness or properties is detected. The datum may be a point, line, vector, or surface. The datum may be calculated by taking into account feasible and non-feasible zones of the components, for example zones in which drilling may be performed (feasible zones) and zones in which drilling should not be performed (non-feasible zones). The feasible zones may be calculated based on the data from the backscatter x-rays 62.

[0092] The datum may be an edge of a part, such as the edge of a rib foot 16, or a boundary between two parts that are joined, such as the boundary between the rib 15 and rib foot 16. The boundary may be a contrast in material properties, for example the interface between two materials. The components may comprise different materials, such as carbon fibre composite, glass fibre composite, thermoplastic composite, thermoset composite, aluminium or steel. The intensity of the backscattered x-rays from each material will contrast, and this contrast can be detected.

[0093] The x-ray backscatter device 60 may additionally/alternatively be used to assist in orienting the top plate 51. In the particular example shown in Figure 9b, the top plate 51 is oriented so that it is normal to the outer surface 14J of the wing skin 14. By utilising the information received from the backscattered x-rays, the top plate 51 may be oriented so that it is normal to the inner surface 141 of the wing skin 14 or any other internal feature of the wing 3 [0094] The x-ray backscattered device 60 may additionally/alternatively be used to identify the location to apply the clamping force, and/or the vector of the clamping force relative to a component, and/or the magnitude of the clamping force. For example, the x-ray backscatter device 60 may be configured to assist in determining one or more of the clamping location, clamping vector, and clamping force magnitude so as to reduce the degree of slippage of the clamp and/or to maximise the effectiveness of the clamping on the parts of an assembly.

[0095] As shown, the tools 31 (optionally including the x-ray backscatter device 60) may be moved by the robot arm 28. Other means of moving the tools 31 relative to the clamping fixture 50 may also be used, such as jigs and moveable fixtures Alternatively the tools may be handheld.

[0096] In Figures 12a-12b an example is shown in which the x-ray backscatter device 60 and drilling tool 31a are both coupled to the top plate 51 of the clamping fixture 50. The top plate 51 is moveable relative to the lower wing skin cover 14 in order that the x-ray backscatter device can scan the area of the wing skin 14 around the rib foot 16. Whilst the x-ray backscatter device 60 is in operation, the drilling tool 31a is in a retracted position so that the drill tool 31a does not extend out from the top plate 51, as shown in Figure 12a. In alternative examples a different tool, such as a fastening tool 3 lb, may be used instead of the drilling tool 31a, or in addition to the drilling tool 31a and attached to the top plate 51 adjacent to the drilling tool 31a.

[0097] Once a datum has been determined, the top plate 51 can be adjusted so that the drilling tool 31a is directed towards the target location. The top plate 51 is then clamped against the lower wing skin 14 (as described previously). The target location may be the datum or a location relative to the datum.

[0098] The drilling tool 3 la is coupled to a linear track 58 that allows the drilling tool 31a to move relative to the top plate 51. By moving the drilling tool 31a towards and away from the top plate 51, the drill can be moved to the retracted position shown in Figure 12a, in which the drill does not extend beyond the top plate 51, to a protracted position shown in Figure 12b, in which the drill extends beyond the top plate 51 so that a component/part can be drilled.

[0099] When the top plate 51 is clamped against the lower wing skin 14, with the drilling tool 31a directed towards the target location, the drilling tool 3 la is moved to the protracted position so that the drill extends out from the top plate 51 and drills through the lower wing skin 14, as shown in Figure 12b.

[0100] As shown in Figure 13a, the x-ray backscatter device 60 may be operated by a robot arm 28. In this example the x-ray backscatter device 60 is considered a tool 31 that can be moved by the robot arm 28. The device 60 is inserted through the aperture 56 in the top plate 51 (the aperture as shown in Figure 7), although the device 60 may be operated independently of the top plate 51 and hexapod 40 arrangement. The x-ray backscatter device 60 then emits x-rays 61 towards the components 14, 15, 16, and then at least a proportion of the x-rays are backscattered 62.

[0101] In an alternative example shown in Figure 13b, the top plate 51 is pressed against the outer surface 14J of the lower wing skin 14 to clamp the lower wing skin 14 against the rib foot 16 prior to scanning the components 14, 15, 16 with the x-ray backscatter device 60. The advantage of this approach is that the gap between the components, i.e. the lower wing skin 14 and the rib foot 16, is reduced.

[0102] This may result in the area available to scan on the lower wing skin 14 being reduced, as the scanning region may be limited by the size of the aperture 56 in the top plate 51. Alternatively, the top plate 51 may be formed of a material that is substantially transparent to x-rays.

[0103] In the previous examples of Figures 5 to 13 the x-ray backscatter device 60 is used to assist in the clamping of components (e.g. a lower wing skin 14 to a rib foot 15) and/or the positioning of a drilling tool 31a or fastening tool 31b relative to the components. In an alternative example the x-ray backscatter device 60 may be used to assist in the positioning of a part onto a surface of an assembly, wherein the position of the part is based on the datum determined by the x-ray backscatter device 60.

[0104] For instance, Figures 14a-14b show an example in which a bracket 32 is fitted to an outer surface 14J of a lower wing skin cover 14. The method is similar to the examples described previously, and involves positioning the x-ray backscatter device 60 adjacent to the outer surface 14J of the wing skin 14 so that the device 60 can emit x-rays 61 towards the wing skin 14 and receive backscattered x-rays 62 from wing skin 14, rib 15, and rib foot 16.

[0105] The information is processed by a computer and used to determine a datum. The x-ray backscatter device 60 can then be withdrawn on the robot arm 28, with the robot arm replacing the device 60 with a part placement head 31c configured to position a part On this case a bracket 32) onto the outer surface 14J of the lower wing skin 14 based on the position of the datum. The bracket 32 can then be fixed to the outer surface 14J of the wing skin 14, for example using fasteners or adhesive.

[0106] It will be clear to the skilled person that the examples described above may be adjusted in various ways. The platform 20 shown in Figure 5 is fixed to a floor by fasteners. In an alternative example, the platform 20 may be moveable. For example, the platform 20 may be an automated guided vehicle (AVG), typically guided along set tracks, that is able to move the equipment into the vicinity of the drilling/fastening location.

[0107] The drilling and/or fastening operation may be performed multiple times at different locations for one x-ray scan. For example, the x-ray backscatter device 60 may scan an area to determine a datum point and then use the datum to drill a plurality of locations consecutively in a rib foot 16. The drilling and/or fastening operation may be performed on a series of rib feet 16 using a single datum.

[0108] Alternatively, the x-ray backscatter device 60 may scan an area to determine a datum point, drill a hole and/or insert a fastener, and then re-scan an area to determine a second datum point in order to drill a second hole and/or insert a second fastener. The advantage of this second approach is that any 'drift' between the actual tool position and the estimated tool position relative to the datum can be compensated for.

[0109] The information received relating to the backscattered x-rays may be used to determine one datum point from a single scan of a component/part, or may determine a plurality of datum points in a single scan.

[0110] The information received relating to the backscattered x-rays may be used to define feasible and non-feasible areas for drilling, fastening, or otherwise feasible and non-feasible areas for operating on the wing skin.

[0]11] The clamping fixture 50 may be an integral part of the hexapod 40, i.e. the lower plate 52 of the clamping fixture 50 is the same as the top plate 43 of hexapod 40.

[0112] The invention has been described in relation to the positioning and use of a drilling tool 31a, a fastening tool 31b. In alternative examples, other tools 31 may be used such as extraction fans, milling tools, cutting tools, welding tools, or any other suitable tool known in the art.

[0]13] In the described examples, the robot arm 28 is mounted to the platform 20. In alternative examples, the robot arm 28 may be mounted to the floor, may be on a second platform adjacent to the first platform 20, or may be mounted on top of the vertical stage 24, or any other suitable mounting position.

[0114] The use of an x-ray backscatter device 60 is particularly applicable to determining a datum through a wing skin, as the thin profile of the wing skin means that the quality backscattered information is high and good tolerances can be achieved. However, the invention is also applicable to other applications, in which there may be a trade-off between the thickness of the component analysed and the tolerances that can be obtained.

[0115] In the examples shown, the x-ray backscatter device 60 is coupled to the clamping fixture 50 of the hexapod system 40, or moved by a robot arm 28. However, it will be apparent that the x-ray backscatter device 60 may alternatively be a handheld device, or held on any fixture or assembly arrangement that can be manipulated to move the device 60 relative to a component to be scanned.

[0116] The invention has been described in relation to the assembly of a rib foot to a wing skin of an aircraft wing. In alternative examples, the components may be any other suitable aircraft components, such as the spar, stringers, or fuselage skin.

[0117] In fact, described aspects of the invention are applicable to a range of applications in different industries, for example, the automotive, marine, defence, and space industries The described benefits are particularly applicable to any application in which one sided assembly or one way assembly can be applied.

[0118] 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.

[0119] 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

CLAIMS1 A clamping apparatus comprising: a hexapod including a base and a clamping surface, a controller arranged to control the hexapod, wherein the controller is configured to control the hexapod such that the clamping surface is moveable so as to face normal to a surface of a first component and be pressed against the surface of the first component.
2. The clamping apparatus if claim 1, wherein the clamping surface is configured to be pressed against the surface of the first component to clamp the first component against a second component.
3. The clamping apparatus of claim 1 or 2, wherein the clamping surface is configured to be pressed normal to the surface of the first component.
4. The clamping apparatus of any preceding claim, wherein the clamping surface includes an opening for a tool, the opening configured to provide access to the surface of the first component through the opening in the clamping surface when the clamping surface is pressed against the surface of the first component.
The clamping apparatus of any preceding claim, further comprising a drilling tool configured to drill the first component whilst the clamping surface is pressed against the first component
6. The clamping apparatus of any preceding claim, further comprising a fastening tool configured to install a fastener for fastening the first and second components together whilst the clamping surface is pressed against the first component.
7. The clamping apparatus of claims 5 and 6, wherein the clamping surface is configured to be pressed continuously against the surface of the first component whilst the first component is drilled by the drilling tool and the fastening tool installs a fastener.
8. The clamping apparatus of any preceding claim, further comprising a part placement head configured to move a part relative to first component whilst the clamping surface is pressed against the first component.
9. The clamping apparatus of any preceding claim, further comprising a sensor device configured to scan the first and/or second component, and a controller configured to receive information from the sensor device and to determine a datum from the information.
The clamping apparatus of claim 9, wherein the sensor device is an x-ray backscatter device, arid the controller receives information relating to the backscattered x-rays from the x-ray backscatter device in order to determine the datum.
11 The clamping apparatus of claim 10, further comprising a computer configured to process the information from the x-ray backscatter device in order to produce an image of the first and/or second component, wherein the image is for used in determining the datum.
12 The clamping apparatus of any one of claims 9 to 11, wherein the datum is used for positioning a tool and/or controlling the movement of the hexapod.
13 The clamping apparatus of claim 12, wherein the tool is the drilling tool, fastening tool, or part placement head of claims 5 to 8.
14 The clamping apparatus of any preceding claim, wherein the clamping surface is substantially rigid.
The clamping apparatus of any preceding claim, wherein the clamping apparatus is configured to apply a first clamping force in a first direction towards the component, and wherein the clamping apparatus is not configured to apply a second clamping force that substantially opposes the first clamping force
16. A method of assembly using a hexapod, the hexapod comprising a base and a clamping surface, the method comprising: orientating the clamping surface relative to the base and normal to a surface of a first component, extending the clamping surface to press against the first component, pressing the clamping surface against the surface of the first component.
17 The method of claim 16, wherein the step of pressing the clamping surface against the surface of the first component involves pressing to clamp the first component against a second component.
18 The method of claim 16 or 17, wherein the step of pressing the clamping surface against the surface of the first component involves pressing normal to the surface of the first component.
19 The method of any one of claims 16 to 18, the method further comprising: scanning the first and/or second components with a sensor device, determining a datum on the first and/or second component based on information received from the sensor device.
20. The method of claim 19, wherein the sensor device is an x-ray backscatter device, the step of scanning further comprising: positioning the x-ray backscatter device adjacent the first component; emitting x-rays from the device towards the first and second component, wherein x-rays are backscattered the first and second component towards the device.
21. The method of claim 19 or 20, wherein the step of orienting the clamping surface relative to the base and normal to the surface of a first component is based on the datum.
22. The method of any one of claims 19 to 21, further comprising: using the datum to adjust the position of a tool relative to the first and/or second component.
23. The method of any one of claims 16 to 22, the method further comprising: drilling into the first component and/or second component after the first component is clamped against the second component, and/or inserting a fastener into the first component and/or second component after the first component is clamped against the second component.
24. The method of any one of claims 16 to 23, the method further comprising: moving a part onto the first component using a part placement head after the first component is clamped against the second component The method of any one of claims 16 to 24, the method further comprising: determining a magnitude of a clamping force, wherein the step of pressing the clamping surface against the first component is based on the determined clamping force.