Patent Description:
Although the invention may be useful in connection with assembling various components and/or subassemblies in aircraft or spacecraft production, in particular involving joints that include installation of a large number of fasteners and preparation of corresponding holes, the invention and the underlying problem will be explained in the following in exemplary manner with reference to the assembly of an aircraft fuselage, in particular a fuselage of an airplane, but without limiting the invention to that effect.

A conventional way of producing a fuselage structure for an airplane involves assembling several essentially barrel-shaped fuselage sections from individual shells by connecting the latter along joints that extend e.g. approximately parallel to a longitudinal direction of the fuselage, and then joining the assembled sections along circumferential or "orbital" joints.

Such a conventional approach still requires a significant fraction of work, especially regarding the installation of fasteners at joints, to be carried out manually. Automated systems are generally integrated into workstations specific to either longitudinal or orbital joints assembly. This circumstance is leading to a high number of different automated systems which are integrated into a mainly manual process flow, which may result in automated systems that are less efficient than desired.

It would be desirable to be able to produce an aircraft in an improved manner that is suitable for implementing an efficient, automated execution of connections at joints.

In the context of producing components for aircraft, it has already been proposed to bond parts using a cold or hot curing adhesive and to perform steps of drilling and installation of rivets after curing of the adhesive. During curing, the parts are held in a large, complex and expensive jig.

Furthermore, <CIT> describes a method for joining aircraft structural components, e.g. at an orbital junction of fuselage segments. A process is described which includes positioning and temporarily clamping parts to be joined, drilling a number of pilot holes through the temporarily clamped parts, removing the temporarily clamped parts from one another and cleaning them of burrs and/or metal swarf, preparing the parts for sealing and performing sealing, re-positioning the parts, installing temporary fasteners in the number of pilot holes, and, using an automated robotic drilling and assembly system, drilling a remaining number of holes required in addition to the number of pilot holes as well as installing permanent fasteners in the number of pilot holes and the remaining number of holes.

Another process for assembling two assemblies, such as aircraft fuselage assemblies, is described in <CIT>, which aims at application of required pressure in a simple manner over an overlap zone during drilling of holes through this zone, in order to avoid burring and to avoid swarf entering an interface between assembled panels, usually coated with interposition sealant.

A method for assembling parts, including clamping a workpiece using magnetic forces, is described in <CIT>.

Against this background, the problem to be solved by the present invention is to provide an improved approach of assembling a structure in aircraft or spacecraft production, which facilitates automation and helps to reduce cost and effort for producing structures of this kind.

According to the invention, this problem is solved by a method having the features of claim <NUM>.

Accordingly, a method of assembling a structure in aircraft or spacecraft production is provided, which comprises:.

An idea underlying the invention is that via the clamping of the sealant layer during curing thereof, it is possible to obtain a layer thickness of the sealant after curing that does not exceed a pre-defined, required maximum sealant layer thickness in the area of the fasteners. The pre-defined maximum sealant layer thickness helps to ensure that a pre-load of the installed fasteners and a fatigue performance of the joint are obtained that are in accordance with those specified for the joint. With the proposed method, it is advantageously not necessary to install the final fasteners within a period of time during which the sealant is still wet and uncured. Thereby, undesirable constraints e.g. regarding the cycle times in a production process for the structure can be avoided. Furthermore, excessive preliminary tacking of the components at a large number of tacking locations, or large, expensive and inflexible jigs, can be avoided with the aid of the present invention.

The invention facilitates the implementation of automated processes and systems for performing drilling and installation of final fasteners at the joint, preferably along with drilling and installation of fasteners at one or more further joints, in a single station or automated cell with high efficiency, and in particular for a large number of fastening positions and/or for large components and structures.

With the invention, the sealant compound can be applied and the requirements on the sealant layer thickness can be met in a flexible manner without interfering with a highly efficient and automated process of drilling and installing final fasteners. At the same time, the cost and the space requirements for large and immobile jigs can be avoided.

In other words, the present invention makes it possible to easily shift the application of the sealant, within the production workflow, to an earlier station, upstream of drilling and installation of the final fasteners. Accordingly, the present invention enables drilling through a layer of cured sealant compound, fulfilling pre-defined layer thickness requirements.

In this way, workloads such as drilling and fastening can be shifted to other stations which are far beyond in the workflow, as seen from the station where the components are positioned in their target positions and/or the sealant is applied. In particular, these workloads can be shifted from section assembly workstations to an efficient automated station. Integration of automated stations into a highly manual process can be avoided or reduced. Thereby, the capacity of automated systems can be utilized in a significantly improved manner, which makes it possible to improve efficiency and reduce cost.

With the present invention, the tacking of the components in the joining regions can advantageously be confined to a relatively small number of tacking points, or the tacking may even be avoided altogether. Thereby, an unfavourable impact of an excessive number of tacking locations, where the components in particular have been pre-drilled, on the efficiency and performance of subsequent automated processes, as well as high manual workload for tacking, can be avoided.

Moreover, the sealant which is cured to the pre-defined degree may be capable of providing bonding of the joining regions at least to some degree, which can help to reduce the efforts for counter holding during drilling and fastener insertion.

In addition, the invention may help to reduce the exposure of operators to wet sealants compared to installation of fasteners through wet sealant layers.

The pre-defined degree of curing can in the context of the present invention in some embodiments correspond to substantially complete curing of the sealant before proceeding to the drilling of holes of final dimension. In preferred embodiments a pre-defined degree corresponding to a curing degree of e.g. <NUM> to <NUM> percent, corresponding to about <NUM> to <NUM> percent of a hardness considered to indicate complete curing, may be sufficient. In particular, the pre-defined degree of curing may be defined as a Shore hardness threshold. For example, a Shore A hardness of about <NUM> may in some embodiments be considered to correspond to substantially complete curing of the sealant. In other words, according to the invention, a pre-defined degree of curing in this context corresponds to a curing degree in which the sealant does not flow anymore, and in which without external mechanical effect the joining regions with the sealant in the pre-defined degree of curing inbetween remain unchanged in terms of their spatial arrangement relative to each other.

Advantageous improvements and developments of the invention are contained in the dependent claims as well as in the description referring to the drawings.

In a development, the drilling in order to obtain the hole of final dimension and the installation of the final fastener at each of the plurality of fastening positions are each performed in an automated manner, in particular in an automated assembly station. Accordingly, the drilling and installation of the final fasteners can be accomplished in an efficient, cost-saving and time-saving manner.

According to an improvement, the method includes removing the clamping device at least partially before performing the drilling in order to obtain the holes of final dimension and the installation of the final fasteners at the plurality of fastening positions. Thereby, the joint can be accessed in a convenient manner for the drilling and final fastener installation. In a variant, at least a part of the clamping device may remain installed on the arrangement during drilling the holes of final dimension, wherein the remaining part may for example be adapted to serve as a counter support for the drilling.

In a development, the clamping may be performed in such a manner that the thickness of the layer of the sealant after curing, in the area of each of the fastening positions within the joining regions at which a final fastener is to be installed, is equal to or less than a pre-defined maximum sealant layer thickness of <NUM>.

In a development, during clamping the associated joining regions, the clamping device applies a clamping force at each of a plurality of clamping force application locations within the associated joining regions. In particular, the clamping device may apply individual, and for example different, clamping forces depending on the clamping force application location. The clamping forces may be adjustable or selectable, for example, e.g. by adjusting or pre-configuring the clamping device. Further preferably, the clamping device is configured to apply a clamping force individually at each clamping force application location, wherein the clamping force may e.g. be selectable or adjustable. This makes it possible to locally apply clamping force or pressure, preferably at each fastening position, in order to ensure that in a region of each of the clamping force application locations, and preferably in a region of each of the fastening positions, the sealant layer thickness does not exceed the pre-defined maximum sealant layer thickness after curing. Adjustable or selectable clamping forces that may be different depending on the clamping force application location contribute to achieving the desired layer thickness at all fastening positions.

The clamping forces can be applied, for example, using elastic forces or in pneumatic or hydraulic manner. For example, the clamping device may be adapted to apply the clamping force using a plurality of spring-loaded force application elements, or using the Young's modulus of a material from which a plurality of force application elements are formed, e.g. a solid body made from solid material such as for example PTFE or an elastomer, acting like a spiral spring. In alternative developments, the clamping device may be provided with actuators, e.g. pneumatic or hydraulic actuators. For example, the pneumatic or hydraulic actuators may comprise pressurizable caps or membranes.

In particular, the clamping force at each of the plurality of clamping force application locations is applied substantially transverse, for example normal, to the uncured layer of the sealant.

In a development, the clamping forces are applied using a first clamping device part arranged on a first side of the joint and adapted to apply a plurality of individual forces acting from the first side, and using a second clamping device part arranged on a second side of the joint opposite the first side and adapted to apply a plurality of individual forces acting from the second side. In this manner, individual clamping forces can be applied precisely at each of the clamping force application locations.

According to another development, the clamping forces are applied using a first clamping device part arranged on a first side of the joint and adapted to apply a plurality of individual forces acting from the first side, and using a second clamping device part configured as a common rigid counter support part and arranged on a second side of the joint opposite the first side. In this way, the effort and cost for the clamping device can be reduced, while the clamping device is still adapted to provide individual clamping forces at each of the clamping force application locations. In some configurations, a common rigid counter support part on the second side can be sufficient to obtain the desired sealant layer thickness after curing.

In still another development, the clamping forces are applied using a clamping device part arranged on a first side of the joint and adapted to apply a plurality of individual forces acting from the first side, and using at least one retaining piece on a second side of the joint opposite the first side. In some configurations, it may be sufficient to apply individual forces from the first side using the clamping device part on the first side, which is retained on the arrangement via the retaining piece on the second side, and without a counter support part placed opposite the plurality of the clamping force application locations. This may be appropriate in some configurations to obtain the desired sealant layer thickness with a relatively simple and cost-effective configuration of the clamping device.

In particular, the components include at least one shell-type component. The shell-type component may in particular be a fuselage shell as part of the structure. In further developments, the at least two components may each be a shell-type component such as a fuselage shell, for instance. Joining such shell-type components to each other and/or to other additional components may in many cases require a considerable number of fasteners and considerable effort, and accordingly, the improvements e.g. regarding efficiency, flexibility and suitability for automation of the method proposed herein may be particularly advantageous. Efficient use of automation for assembling a complex joint as in the case of joining fuselage shells can lead to important savings in terms of effort, time and costs. In other implementations, an application of the invention to other types of shell-type components, e.g. for a wing to produce a wing structure, is conceivable.

More particularly, the joint may be a longitudinal joint, in particular a longitudinal joint extending substantially parallel to a longitudinal axis of a fuselage. However, in other implementations, it is conceivable to apply the invention to other joints.

In particular, in further developments, the invention can be applied to any other fastening of an individual part as a first one of the components to an outer skin of a fuselage or fuselage shell as a second one of the components, wherein the individual part may in examples be a stringer, a crackstopper, or a clip ensuring a coupling of a frame to the skin. In particular, in some developments a stringer, a crackstopper and/or a clip as one of the components may be adhered to one or both of the shell-type components using the sealant, wherein automated installation of final fasteners may be performed using an automated device operating in an inner region of a fuselage section.

Further, the invention may in further developments be applied to other joints which require sealing, e.g. a frame coupling as a first one of the components, which may be adhered to one or more adjacent frame segment(s) as (a) second one(s) of the component(s) using the sealant.

In a further development, the drilling in order to obtain the hole of final dimension and the installation of the final fastener at each of the plurality of fastening positions at the joint are performed at an automated station that is configured to additionally perform automated drilling of holes and automated installation of final fasteners at further fastening positions at a further joint, in particular at an orbital joint. In this manner, a considerable advantage compared to traditional section assembly of an aircraft fuselage can be obtained, for example. Such an automated station may be a Combined Automation Station, which is configured to perform drilling and installation of final fasteners at the longitudinal joints and at at least one orbital joint at the same automated station. In this manner, the number of automated systems in the production line can be reduced and the efficiency of the automated processes can be improved.

According to a further development, in order to support reaction forces induced by the clamping action, the clamping device is supported on the arrangement. In this manner, the clamping device can be easily and flexibly transported along with the arrangement, for example from one assembly station to a subsequent one, if required. In particular, the clamping device may be supported on the arrangement using a mechanical connection extending through the components in the associated joining regions thereof, and/or may be supported on the arrangement using magnetic force and/or using negative pressure or vacuum. A mechanical connection extending through the components in the joining regions requires only little space and can be implemented also if space for installing the clamping device is restricted. Supporting the clamping device on the arrangement using magnetic force or using a negative pressure or vacuum does not require a through-opening in the components and may be useful if there is sufficient space for installing a magnetic device or a device capable of using negative pressure or vacuum for coupling to the arrangement such as vacuum pads. In some developments, a mechanical connection may be combined with the use of magnetic force and/or of negative pressure or vacuum for supporting the clamping device on the arrangement.

In a further development, the plurality of fastening positions is or comprises a plurality of first fastening positions. In this development, the method comprises tacking the components at at least one second fastening position, preferably at each of a plurality of second fastening positions, after the uncured layer of the sealant has been formed between the associated joining regions. In this way, the components can be pressed against each other by tacking at the second fastening position(s), and in particular, the tacking can also provide a way of supporting the clamping device in a simple and expedient manner.

In particular, the plurality of first fastening positions may correspond to a first fraction of an entire set of fastening positions that is pre-defined for the joining regions, while the plurality of second fastening positions may correspond to a second fraction of the entire pre-defined set of fastening positions, wherein the first fraction is larger than the second fraction. For example, the number of second fastening positions may correspond to approximately <NUM> percent and the number of first fastening positions may correspond to approximately <NUM> percent of the number of fastening positions included in the entire pre-defined set thereof at the joint. Accordingly, a simple way of supporting the clamping device can be provided, while the number of tacking locations is limited and a high efficiency of the entire process can be obtained. In the present context, a pre-defined set of fastening positions should be understood as a set of positions that have been defined during the design of the structure as locations where fasteners are to be installed, even if at the outset of the process of joining the components for assembling the structure, the components do not yet comprise any physical feature corresponding to the pre-defined fastening positions, except for pilot holes, for example, at a few fastening positions in some embodiments.

In a development, tacking the components comprises tacking the components to each other in the joining regions using a tacking assembly comprising a coupling element extending through a preliminary hole at the second fastening position, preferably at each of two or more of the second fastening positions. In particular, the preliminary hole has a non-final dimension. In this development, the method further comprises installing the clamping device on the arrangement by coupling the clamping device to the arrangement using at least the coupling element installed in the preliminary hole, preferably using several coupling elements, each installed in one of several preliminary holes. In this way, the coupling element can advantageously be used both for tacking the components and for supporting the clamping device and coupling the latter to the arrangement. Only little space is required, and a mechanical connection between two sides of the joint can be easily established.

In a further improvement, the coupling element is formed as a rod, in particular a threaded rod, or as a bolt or a screw. Accordingly, both the tacking and the coupling of the clamping device to the arrangement are possible in a simple manner and can be easily released.

In a development, the tacking assembly may further comprise at least one nut that is engageable with the coupling element, e.g. the threaded rod, bolt or screw.

In a development, the tacking of the components and the installation of the clamping device on the arrangement, e.g. using the coupling element(s), may be performed in one step or in subsequent steps.

It may in further developments be provided that tacking of the components at some of the second fastening positions is performed beforehand in a separate step, while tacking at others of the second fastening positions may be performed along with the installation of the clamping device in the same step. In this way, the components may be securely held together beforehand while the tacking at the other second fastening positions can be accomplished in a time-saving manner.

In a development, de-installing at least one of the coupling elements, enlarging the preliminary hole used to accommodate the de-installed coupling element at the second fastening position, and installing a final fastener in the enlarged hole at the second fastening position are performed after automated drilling and automated installation of the final fasteners at the first fastening positions. In this way, the coupling elements may serve, during the automated drilling and installation of the final fasteners at the first fastening positions, for additionally tacking and holding the components together at the joint, and may help to improve the stability of the arrangement while the connections at the first fastening positions are completed.

In another development, de-installing at least one of the coupling elements, enlarging the preliminary hole used to accommodate the de-installed coupling element at the second fastening position, and installing a final fastener in the enlarged hole at the second fastening position are performed before automated drilling and automated installation of the final fasteners at the first fastening positions. In this manner, the final fasteners at the second fastening positions may contribute to an improved stability of the arrangement during the completion of the connections at the first fastening positions in automated manner.

In particular, enlarging the preliminary hole and installing the final fastener in the enlarged hole in the preceding improvements at the second fastening position, before or after automated drilling and installation of the final fasteners at the first fastening positions, may be performed at least partially manually and/or using hand-held tools.

According to a further development, at least one of the coupling elements is dein-stalled, and after de-installing the at least one of the coupling elements, drilling and installation of the final fasteners at the first fastening positions, enlarging the preliminary hole used to accommodate the de-installed coupling element at the second fastening position, and installing a final fastener in the enlarged hole at the second fastening position are performed in an automated manner. Accordingly, the efficiency of the process can be improved further as the final connections at the second fastening position(s) can be formed in an automated way.

In some developments, the connections at the second fastening positions are not necessarily finalized all in the same manner, but various combinations of the preceding developments are possible. For instance, at one or more of the secondary fastening positions, the coupling element(s) can be removed, the preliminary hole(s) can be enlarged and the final fastener(s) can be installed before automated completion of fastener installation at the first fastening positions, while at one or more other(s) of the second fastening positions, the coupling element(s) can be de-installed, the preliminary hole(s) can be enlarged and the final fastener(s) can be installed after the automated completion of fastener installation at the first fastening positions. At still one or more other of the second fastening positions, the preliminary hole may be enlarged and the final fastener may be installed in an automated process, e.g. along with the first fastening positions. Various combinations of installing final fasteners at second fastening positions in the way just described before and/or after an automated process at the first fastening positions and/or in automated manner along with the first fastening positions is conceivable. In this way, reliable handling of the arrangement of the components is made possible, for example, while significant improvements in efficiency can be obtained.

According to a development, before the sealant is applied to the at least one of the components, the components are temporarily positioned relative to each other, and subsequently, pre-drilling is performed at the second fastening position(s) to obtain the preliminary hole(s) through the associated joining regions. In particular, if the pre-drilling is performed in this manner before the sealant is applied, the preliminary hole(s) can be deburred and/or the joining regions can be cleaned, in particular at the interface between the joining regions, after pre-drilling. For example, the gap between the joining regions can be opened again after the pre-drilling step for cleaning and/or deburring. In this way, chips and burrs can be reliably removed from within the gap in order to obtain a joint of high quality.

In a further development, pre-drilling is performed at the second fastening position(s) to obtain the preliminary hole(s) through the associated joining regions, after the uncured layer of the sealant has been formed between the associated joining regions. In this way, the efficiency of the process may be further improved, as it is not required to re-open the joint before applying the sealant. Preferably, in this case, it is ensured that burrs and contamination of the gap by chips from the pre-drilling are prevented, for example by a proper clamping of the joining regions during the pre-drilling process. This may contribute to achieving short station lead times.

In a further development of the method, the preliminary hole or preliminary holes or some of these may already be present in the components at the one or more of the second fastening positions at the time the components are delivered, so that no pre-drilling needs to be performed at these positions.

The improvements, enhancements and developments of the present invention may be arbitrarily combined with each other whenever this makes sense. Moreover, other possible enhancements, implementations and developments of the present invention comprise combinations of features of the invention which have been described above or will be described in the following in relation to the detailed description of embodiments, even where such a combination has not been expressly mentioned.

In particular, the improvements, enhancements and developments of the invention described above may be applied in analogous manner to each of the method and the clamping device proposed herein.

The invention will be explained in the following with reference to the schematic figures of the drawings which illustrate embodiments of the invention.

The enclosed drawings are intended to illustrate embodiments of the invention so that the invention may be further understood. The drawings, in conjunction with the description, are intended to explain principles and concepts of the invention. Other embodiments and many of the advantages described may be inferred from the drawings. Elements of the drawings are not necessarily drawn to scale.

Elements, features and components which are identical or which have the same function or effect have been labeled in the drawings using the same reference signs, except where explicitely stated otherwise.

<FIG> displays an aircraft <NUM>, for example a commercial passenger aircraft, comprising a fuselage <NUM>, a nose <NUM>, an empennage <NUM> as well as wings <NUM>. <FIG> shows a first, barrel-shaped fuselage section <NUM> and a second, barrel-shaped fuselage section <NUM>, joined to each other at a circumferential or orbital joint <NUM>. The fuselage sections <NUM> and <NUM> are structural assemblies that form part of a structure <NUM> of the fuselage <NUM>, in <FIG> in exemplary manner in the rear part of the fuselage <NUM>. The fuselage structure <NUM> is displayed partially in schematic manner in <FIG> in cross-section and comprises circumferentially extending frames <NUM>, longitudinally extending stringers <NUM>, and a skin <NUM> stiffened by the frames <NUM> and stringers <NUM>.

Each of the sections <NUM> and <NUM> is formed with several fuselage shells, connected to each other at longitudinal joints that extend essentially parallel to a longitudinal direction X of the aircraft <NUM>. In exemplary manner, one longitudinal joint <NUM> of the first section <NUM> and one longitudinal joint <NUM> of the second section <NUM> are schematically indicated in <FIG>. The fuselage shells each include a portion of the skin <NUM> as well as several stringers <NUM> and frame segments for forming the frames <NUM>.

The shells, in particular the segments of the frames <NUM> and/or stringers <NUM> and/or the portions of the skin <NUM> may for example be made from an aluminum material, e.g. an Al-alloy, but may instead be made from another type of material suitable for the formation of joints using fasteners and involving the application of a sealant compound at the joints <NUM>, <NUM>, <NUM>.

In order to assemble the structure <NUM>, a multitude of fasteners, for example rivet-type or bolt-type fasteners, are installed in holes that are drilled at the longitudinal and orbital joints <NUM>, <NUM>, <NUM>. Drilling of final holes at least for a large, predominant percentage of all of these fasteners and installation thereof along the joints <NUM>, <NUM>, <NUM> are carried out in an automated manner in accordance with embodiments described in more detail below, in a so-called combined automation station.

In the following, a first component <NUM> is considered to correspond to a first fuselage shell and a second component <NUM> is considered to correspond to a second fuselage shell. For assembling the structure <NUM>, components <NUM> and <NUM> are designed to be joined to each other at a joint <NUM>, which may be one of the longitudinal joints <NUM> or <NUM> or any other longitudinal joint at one of the sections <NUM>, <NUM>, for instance. The components <NUM>, <NUM> each comprise a joining region <NUM> and <NUM>, respectively, which e.g. may be portions of the skin <NUM>. In order to form the joint <NUM>, the joining regions <NUM>, <NUM> are overlapped and connected using fasteners, e.g. rivets. A third component <NUM> in the form of a stringer <NUM> and/or a crackstopper and/or a clip, not shown in the figures, can also be provided and connected using fasteners to one or both of the components <NUM>, <NUM>. The following discussion is provided with reference to the shell-type components <NUM>, <NUM>, but it is understood that the description given is applicable in analogous manner to the connection of other components, e.g. a stringer, clip or crackstopper to one or both of the shells <NUM>, <NUM>.

A schematic overview of the method according to the embodiments is provided in <FIG>. Steps <NUM>-<NUM> relate to section <NUM>, while steps <NUM>-<NUM> relate to section <NUM>, in exemplary manner. In steps <NUM> and <NUM>, pre-assembled shells in the form of the components <NUM>, <NUM> are provided for each of the sections <NUM> and <NUM>. Further components such as the third component <NUM> may additionally be provided, as an individual, still unconnected part.

In steps <NUM> and <NUM>, shell integration is performed, wherein a sealant compound is applied to at least one of the components <NUM>, <NUM> in the joining region <NUM> or <NUM>, and an arrangement <NUM> is formed for each section <NUM>, <NUM> by positioning the components <NUM>, <NUM> relative to each other in their target positions.

Thereby, a still uncured layer <NUM> of sealant <NUM> is formed between the associated joining regions <NUM>, <NUM>. The joining regions <NUM> and <NUM> are clamped to each other and the clamping is maintained until the sealant layer <NUM> has cured at least to a pre-defined degree. The clamping during curing ensures that the sealant layer thickness requirements are met. Accordingly, in steps <NUM> and <NUM>, sections <NUM> and <NUM>, respectively, are obtained wherein the components are connected at the longitudinal joints <NUM> and <NUM> by the sealant layer <NUM> that is cured to a pre-defined and appropriate degree, but in which the joints <NUM> and <NUM> have not been finally completed by installing the complete set of final fasteners. In other words, at least the greater part of the entire set of final fasteners has not yet been installed at each of the joints <NUM> and <NUM>. Some adhesive connection at the joints <NUM>, <NUM> may be provided by the sealant <NUM>.

In step <NUM>, the sections <NUM> and <NUM> obtained in steps <NUM>, <NUM>, including the unfinished joints <NUM>, <NUM>, are introduced into an assembly station to finish the joints, e.g. a combined automation station configured for positioning the sections <NUM> and <NUM> relative to each other as well as for performing automated drilling and installation of final fasteners at both the orbital joint <NUM> and/or the longitudinal joints <NUM> and <NUM>. In such combined automation station, the joints <NUM>, <NUM> and <NUM> are completed within a single automated station, configured for drilling a large number of final holes and installing final rivets in these. Sealant may be applied to seal the orbital joint <NUM> at the combined automation station. Alternatively the positioning of the sections <NUM> and <NUM> relative to each other and the sealant application to seal the orbital joint <NUM> can be done in a specific station prior to a combined automation station.

Thereby, the number of automated systems necessary can be reduced and an efficient process can be obtained. Further assembly tasks may also be performed in the combined automation station.

Alternatively the joints <NUM>, <NUM>, <NUM> can be finished semi-automated and/or manually in step <NUM>.

Performing steps analogous to <NUM>-<NUM>, <NUM>-<NUM> for all or most sections of the fuselage makes it possible to obtain a fuselage structure <NUM> in step <NUM> that is complete or complete to a large extent.

Part P1 of the process schematically illustrated in <FIG>, encompassing steps <NUM>-<NUM>, <NUM>-<NUM>, is performed at specific production stations for shell positioning and for some remaining assembly tasks, e.g. assembly of a clip or frame coupling. Part P2 in <FIG> encompasses steps <NUM>, <NUM> and is performed at the combined automation station and/or subsequent stations.

<FIG> shows several variants of a method for assembling the structure <NUM> in more detail. Steps illustrated in <FIG> are described below referring to the first fuselage section <NUM> and the longitudinal joint <NUM>, <NUM>, but these steps apply in analogous manner to the second fuselage section <NUM> and the joint <NUM>, or to other sections of the fuselage with corresponding joints.

In step <NUM>, the components <NUM>, <NUM> are positioned relative to each other in their target positions and preliminary holes of non-final dimension, having a diameter smaller than a specified final diameter, are drilled at a pre-defined and comparatively small fraction, e.g. about <NUM> percent or similar, of the entire set of fastening positions that have been defined during the design of the section for installation of fasteners such as rivets along the joint <NUM>. After the pre-drilling in step <NUM>, the joint <NUM> is opened again in step <NUM>. The step <NUM> can include pre-drilling of preliminary holes in the skin <NUM> as well as in a clip and/or crackstopper and/or stringer <NUM>.

Then, in step <NUM>, chips and burrs resulting from the pre-drilling at the interface between the associated joining regions <NUM>, <NUM> are removed, the interface, in particular the opposing surfaces of the joining regions <NUM>, <NUM>, is cleaned, and the sealant compound is applied to at least one of the joining regions <NUM>, <NUM>. The opposing surfaces preferably are activated before applying the sealant.

In step <NUM>, the components <NUM>, <NUM> are realigned to re-position them in the target positions relative to each other.

The joining regions <NUM>, <NUM> are tacked to each other using a tacking assembly at each or a fraction of the preliminary holes in step <NUM>. For the tacking, preferably about <NUM> percent or similar tacking points may for example be used per frame bay at a longitudinal joint <NUM>, <NUM>.

In the subsequent step <NUM>, one or more clamping devices or fast-clamping template(s) is/are installed using elements of the tacking assemblies at the tacking points. Alternatively or in addition additional tacking assemblies are installed at each or a fraction of the preliminary holes together with the clamping devices or fast-clamping template(s).

Curing of the sealant occurs in step <NUM>. During the period of curing, which may last e.g. approximately <NUM> hours to approximately <NUM> hours (depending on the sealant type used and suitability to perform clamping device or fast-clamping template(s) installation) further work may be performed parallel to the curing and/or before removing the fast-clamping template(s). For example, additional elements can be fastened on one or both of the shell-type components <NUM>, <NUM> in step 607a, e.g. by riveting a frame coupling to the segments of the frame <NUM> that are to be connected and/or by riveting a clip to the frame <NUM>.

In step <NUM>, the clamping devices or fast-clamping template(s) is/are de-installed when the sealant has cured to the pre-defined degree, which may, for example, be defined by a hardness threshold. For example, the template(s) may be de-installed if the Shore A hardness exceeds <NUM>. The sealant in this state adhesively bonds the components <NUM>, <NUM> in the overlapping joining regions <NUM>, <NUM> at least to some degree. In step <NUM>, the joining regions <NUM>, <NUM> still remain tacked or partially tacked. The clip may be riveted to one of the stringers <NUM> before removing the clamping template(s) or if the clamping templates have been removed in step 608a.

After completion of step <NUM>, the method may proceed according to one of several variants. Whether option I, II or III, or a combination thereof, is selected may depend on the components that are joined and on the suitability of the arrangement for drilling and installation of fasteners without any tacking, and/or on loading requirements for transport means such as a crane or a transport vehicle, or both.

Option I: In step <NUM>, all of the tacking assemblies serving as temporary fasteners are de-installed from the preliminary holes. The preliminary holes may be cleaned. Then, in step <NUM>, the section <NUM> in which the joining regions <NUM>, <NUM> are not tacked any more, i.e. in which none of the pre-defined fastening positions are tacked and the adjoining regions <NUM>, <NUM> are essentially held together by the sealant layer, is loaded into the combined automation station, along with the first section <NUM>, prepared in analogous manner. In step <NUM>, the automated station performs automated drilling of final holes at all of the pre-defined set of fastening positions within the adjoining regions <NUM>, <NUM> so as to obtain holes of final dimension at each of these positions, and further performs installation of the final fasteners at all of these positions in an automated manner. In order to do so, the automated station performs, in step <NUM>, secondary drilling at the positions of the preliminary holes which have been used for tacking, by enlarging the preliminary holes to reach the final diameter, and further performs one-shot drilling into the full material at the other positions where no pre-drilling and tacking has been carried out. Because the number of preliminary holes and hence of positions at which secondary drilling is performed is comparatively small, for example <NUM> percent, and drilling into full material can be performed at approx. <NUM> percent of the positions, a highly efficient automated process is obtained.

Option II: Subsequent to step <NUM>, in step <NUM> the section <NUM> is loaded into the combined automation station, together with a further section <NUM> prepared in analogous manner. In step <NUM>, the joining regions <NUM> and <NUM> still remain tacked. Then, in step <NUM>, at fastening positions pre-defined for the joint <NUM> where no tacking has been carried out, one-shot drilling of holes of final dimension and installation of final fasteners are performed in automated manner. In a subsequent step <NUM>, the tacking assemblies are removed from the tacking positions, and secondary drilling to enlarge the preliminary holes to the final diameter is performed at each of the positions previously used for the tacking. The secondary drilling is performed, in step <NUM>, in particular manually, and can be performed at a manufacturing station subsequent to the combined automation station. The removal of the tacking assemblies can also be performed at that subsequent station. In each of the holes enlarged by secondary drilling, a final fastener is installed, in particular manually.

Option III: In step <NUM>, following step <NUM>, the tacking assemblies are de-installed, the preliminary holes may be cleaned, and subsequently, in step <NUM>, secondary drilling is performed at the positions previously used for tacking. In particular, the secondary drilling in step <NUM> may be carried out manually. Further, in step <NUM>, final fasteners are installed in the enlarged holes at the positions used for tacking, e.g. manually as well. Afterwards, in step <NUM>, the section <NUM> in which the joining portions <NUM>, <NUM> are adhesively connected by the sealant layer cured to the predefined degree, and additionally by the number of final fasteners installed at a comparatively small part of the entire set of fastening positions, i.e. those used for tacking, is loaded into the combined automation station, together with a further section <NUM>, which has been prepared in analogous manner. In step <NUM>, at the remaining, larger fraction of the fastening positions pre-defined at the joint <NUM> and not used for the tacking, one-shot drilling of holes of final dimension into the full material and installation of the final fasteners in each of these final holes are performed in automated manner in the combined automation station.

Combinations of the options I, II, III are possible as well. In other words, not all of the fastening positions <NUM> used for tacking must necessarily be treated in the same way, but some thereof might be handled in automated manner as in option I, while at others the connection might be completed via manual or partially manual secondary drilling and manual or partially manual installation of a final fastener subsequent to or ahead of the combined automation station, as in options II or III.

A first embodiment is described in the following in more detail with reference to <FIG>, along with variants thereof.

At (a) and (b), <FIG> illustrates step <NUM>. As schematically illustrated in <FIG> at (a), the first and second components <NUM> and <NUM> are provided, with the first component <NUM> comprising pilot holes <NUM> at fastening positions <NUM>. Three pilot holes <NUM> are shown in <FIG> in exemplary manner. In <FIG>, sheet-like joining regions <NUM>, <NUM> of the components <NUM>, <NUM>, respectively, are shown and may correspond to overlapping sheet-like portions of fuselage shells that are intended to be connected. One or both of the joining regions <NUM>, <NUM> may be formed each with a portion of the skin <NUM>. In particular, one joining region, e.g. <NUM>, may be formed with a portion of the skin <NUM> in an upper shell <NUM> and the other joining region <NUM> may be formed with a portion of a crackstopper as an element of the shell <NUM>.

The components <NUM>, <NUM> are temporarily aligned and positioned relative to each other in relative target positions. At (b), <FIG> shows that the pilot holes <NUM> in the joining region <NUM> are transferred by drilling to the joining region <NUM> of the second component <NUM>. At each of the fastening positions <NUM>, a preliminary hole <NUM> is obtained, the diameter of which is smaller than the diameter of a final hole which will be introduced at a later step and will be used later for installation of a final fastener.

In order to obtain holes of good quality, a counter force F is applied from the side of the second component <NUM>, using a counter support C, while drilling is performed from the side of the first component <NUM>. <FIG> shows, from right to left, that the drilling location is determined by the pilot hole <NUM>, which is transferred to the second component <NUM> by a first worker by drilling, while the counter force F is applied e.g. by a second worker. In this manner, sheet misalignment can be prevented. After the pilot hole <NUM> has been transferred, chips <NUM> can remain at the interface between the components <NUM>, <NUM>. <FIG> shows that after the completion of the pre-drilling, the interface between the joining regions <NUM>, <NUM> is opened again for removal of the chips <NUM>, denoted above by steps <NUM>-<NUM>.

After opening the interface, see <FIG> at (a), the components <NUM>, <NUM> are deburred and the opposing surfaces of the joining regions <NUM>, <NUM> are activated and cleaned, and a sealant compound <NUM> is applied to the joining region <NUM>, corresponding to step <NUM>.

It may be noted that in case the components <NUM>, <NUM> are delivered, at the beginning of the process, with the preliminary holes <NUM> already provided at the appropriate positions, the pre-drilling step to transfer the pilot holes <NUM>, as well as the opening of the joint <NUM>, removal of chips <NUM> and deburring can be omitted. In this case, it may be sufficient to clean and activate the opposing surfaces of the joining regions <NUM>, <NUM> before the sealant <NUM> is applied, unless this has been performed beforehand, and to proceed with step <NUM>.

Furthermore, if appropriate clamping of the overlapping joining regions <NUM>, <NUM> during pre-drilling of the preliminary holes <NUM> is ensured and capable of preventing contamination of the interface, for instance using one or more devices not shown in the figures, it may not be necessary to re-open the joint <NUM> for removing chips <NUM> and burrs. Instead, the sealant <NUM> may in this case be applied before the joining portions <NUM>, <NUM> are positioned and pre-drilled as in <FIG> at (a) and (b). In such a variant, the opposing surfaces of the joining regions <NUM>, <NUM> which the sealant <NUM> should contact are cleaned and activated before applying the sealant compound <NUM> ahead of the pre-drilling step of <FIG>. After pre-drilling, the process proceeds to step <NUM>, see <FIG> at (b).

An arrangement <NUM> is formed by aligning or re-aligning the components <NUM>, <NUM>, step <NUM>, see <FIG> at (b), and thus arranging the components <NUM>, <NUM> in their relative target positions. An uncured layer <NUM> of sealant <NUM> is thereby formed which contacts and extends between the opposing surfaces of the associated joining regions <NUM>, <NUM>.

In line with step <NUM>, the components <NUM>, <NUM> are tacked to each other at each of the fastening positions <NUM> using a tacking assembly 164a. The tacking assembly 164a comprises a coupling element configured as the threaded rod <NUM>, as well as washers <NUM> made from e.g. a synthetic material and nuts <NUM> adapted to threadingly engage the rod <NUM>. In <FIG> at (b), the insertion of the coupling element <NUM> into the preliminary hole <NUM> is shown, with a nut <NUM> already threaded onto the rod <NUM> and a washer <NUM> arranged on the upper side of the nut <NUM>. Next, <FIG> shows, at the centre, a second washer <NUM> and a second nut <NUM> being arranged and threaded, respectively, onto the rod <NUM> from the side of the first component <NUM>. On the right, a detail D1 displays a completed tacking assembly 164a, with the washers <NUM> abutting on the arrangement of components <NUM>, <NUM> on a first side 118a and a second side 118b of the joint <NUM>, the second side 118b being opposite the first side 118a. The nuts <NUM> shown in detail D1 are tightened against the washers <NUM> on the rod <NUM> from the opposite sides 118a, 118b, whereby a compression force is applied to the components <NUM>, <NUM> at the position <NUM>. D1 illustrates that the joining regions <NUM>, <NUM>, with the layer <NUM> of sealant <NUM> therebetween, are clamped to each other at the positions of the preliminary holes <NUM> using the tacking assembly 164a. The rod <NUM> may comprise a metric thread M2. <NUM> or M3, or an imperial thread <NUM>-<NUM> UNF thread, for example. The nuts <NUM> and the rod <NUM> are e.g. formed from metal. Preferably, the rod <NUM> has a high strength.

<FIG> shows the installation of a clamping device 155a, indicated above by step <NUM>. <FIG> shows in exemplary manner three tacking assemblies at three of the fastening positions <NUM>. An associated one of the coupling elements <NUM> extends through each of the preliminary holes <NUM> in <FIG>.

The clamping device 155a comprises the tacking assemblies 164a at the fastening locations <NUM> as well as a first clamping device part 157a arranged on the first side 118a, and a second clamping device part 158a, arranged on the second side 118b. The part 158a can be an inner clamping device part, while the part 157a can be an outer clamping device part. Each of the first and second clamping device parts 157a and 158a is adapted to apply a plurality of individual forces at a multitude of clamping force application locations <NUM> onto the arrangement <NUM>. Specifically, the first clamping device part 157a applies a plurality of individual forces Fc onto an outer side of the joining region <NUM> of the first component <NUM> from the first side 118a, and the second clamping device part 158a applies a plurality of individual forces Fc acting onto an outer side of the joining region <NUM> of the second component <NUM> from the second side 118b. The clamping force application locations <NUM> are located within the joining regions <NUM>, <NUM>. In <FIG>, each of the device parts 157a, 158a is capable of applying an individual clamping force Fc at each clamping force application location <NUM>, wherein some or all of the clamping forces Fc may differ. The clamping force Fc is preferably individually adjustable for each application location <NUM>.

Using the clamping device 155a, the associated joining regions <NUM> and <NUM> are clamped against each other and are maintained in the clamped state at least until the layer <NUM> of sealant has cured to a predefined degree, for example reaches or exceeds a Shore A hardness of <NUM>. The clamping during curing ensures that the layer <NUM> does not exceed a maximum predefined layer thickness, for example <NUM>, after curing at least in the region of each intended fastening position, which may correspond to the force application locations <NUM>. <FIG> shows that using the clamping device 155a, it is not necessary to tack the components <NUM>, <NUM> at an excessive number of fastening locations and only few preliminary holes <NUM> are required. A very flexible process is obtained which is not restricted by a requirement of drilling and riveting through uncured, wet sealant, using the final fasteners, within a narrow timeframe as long as the sealant compound is still wet. The time between the application of the sealant, e.g. in steps <NUM>, <NUM>, and the completion of the joints in step <NUM> can therefore be significantly longer than the period that would be appropriate for installing the final fasteners through the wet sealant layer. In this manner, the implementation of a combined automated process of drilling and final fastening in particular at a large number of positions at the longitudinal and orbital joints <NUM>, <NUM>, <NUM> is significantly facilitated.

As the clamping device 155a applies the clamping forces Fc, reaction forces Fs arise which are supported on the arrangement <NUM> using the tacking assemblies 164a. Only one of the reaction forces Fs is schematically indicated in <FIG> as a force acting on the part 157a. Each clamping device part 157a, 158a has a number of openings <NUM> corresponding to each of fastening positions <NUM>, each of the openings <NUM> being slightly larger than an outer diameter of the rod <NUM>. Through each of the openings <NUM>, one of the rods <NUM> can be inserted with its free end 166a. A nut <NUM> is threaded onto the end 166a and tightened against the clamping device part 157a or 158a, with a plastic washer <NUM> analogous to the washer <NUM> being arranged between the nut <NUM> and the part 157a or 158a. Each of the openings <NUM> may, as shown in <FIG>, be formed slightly conical to facilitate the insertion of the rod <NUM>.

The clamping device 155a is supported on the arrangement <NUM> by tightening the nuts <NUM>, is thereby coupled to the arrangement <NUM> and installed thereon, and can be easily and flexibly transported along with the arrangement <NUM>, which may be an arrangement of shells corresponding to an entire section <NUM> or <NUM>. The device parts 157a and 158a may be designated as fast-clamping templates. A mechanical connection through the components <NUM>, <NUM> is provided between the device parts 157a, 158a via the coupling elements <NUM> extending through the holes <NUM>.

While the clamping device 155a is installed and curing of the sealant compound <NUM> is in progress, additional work such as further assembly tasks may be carried out on the arrangement <NUM>. For example, parallel to curing or before removing the parts 157a, 158a, a frame coupling, not shown in the figures, may be riveted to adjacent frame segments of frame <NUM>, and/or a clip, not shown in the figures may be riveted to the frame <NUM>. Furthermore, before the parts 157a, 158a are removed, or afterwards, the clip already riveted to the frame <NUM> can also be riveted to a stringer <NUM>.

Step <NUM> is illustrated in more in <FIG> for the first embodiment. The first clamping device part 157a, which may be an inner clamping template with respect to the section <NUM>, and the second clamping device part 158a, which may be an outer clamping template with respect to the section <NUM>, are removed after the sealant layer <NUM> is sufficiently cured. In <FIG>, the joining regions <NUM>, <NUM> are still tacked via the tacking assemblies 164a.

The entire set of fastening positions defined for fastening in the joining regions <NUM>, <NUM> encompasses a plurality <NUM> of first fastening positions <NUM> and a plurality <NUM> of second fastening positions, wherein the second fastening positions correspond to the tacking positions <NUM>.

<FIG> illustrates Option I, steps <NUM>-<NUM>. After de-installing the tacking assemblies 164a completely, final holes <NUM> and <NUM> are drilled in automated manner, e.g. at a combined automated station, at all of the positions <NUM> and <NUM>, respectively, and final fasteners <NUM>, <NUM> such as rivets are installed in an automated way at all these positions. In order to do so, automated drilling into full material, so-called one-shot drilling, followed by automated fastening using the final fasteners <NUM> is carried out at the first fastening positions <NUM>. At the second fastening positions <NUM>, so-called secondary drilling, whereby the preliminary holes <NUM> are enlarged to reach the intended final diameter, followed by installing of the final fasteners <NUM> is carried out. <FIG> shows the drilled final holes <NUM>, <NUM> and schematically indicates a few final fasteners <NUM>, <NUM>.

<FIG> illustrates Option II, steps <NUM>-<NUM>. The tacking assemblies 164a remain at the second positions <NUM> during one-shot drilling of final holes <NUM> into full material at the plurality <NUM> of first fastening positions <NUM> e.g. at the combined automation station, followed by installation of the final fasteners <NUM> at the positions <NUM>. Afterwards the tacking assemblies 164a are removed e.g. at a subsequent manufacturing station, secondary drilling to enlarge the holes <NUM> is performed manually or partially manually at the second positions <NUM>, and final fasteners <NUM> are manually or partially manually installed at the positions <NUM>. <FIG> shows the drilled final holes <NUM> before insertion of the final fasteners <NUM>, the components still being tacked at the positions <NUM>.

<FIG> illustrates Option III, steps <NUM>-<NUM>. The tacking assemblies 164a are de-installed after removal of the device parts 157a, 158a, and a manual or partially manual process of secondary drilling at the plurality <NUM> of second fastening positions <NUM> to obtain final holes <NUM> as well as installation of final fasteners <NUM> in the final holes <NUM> is performed. Accordingly, the components <NUM>, <NUM> are already finally connected at the second positions <NUM> when one-shot drilling at the plurality <NUM> of the first fastening positions <NUM> to obtain the final holes <NUM> and the subsequent installation of the final fasteners <NUM> in the holes <NUM> are performed e.g. at the combined automation station. <FIG> shows the drilled final holes <NUM>, <NUM> and the installed final fasteners <NUM>, while one final fastener <NUM> to be installed is schematically depicted.

The drilling in order to enlarge the preliminary holes <NUM>, and the drilling of final holes <NUM> in one-shot manner, is carried out in a state in which the layer <NUM> of sealant is cured at least to the pre-defined degree. Accordingly, the gap at the interface of the joining regions <NUM>, <NUM> is closed, the components <NUM>, <NUM> are bonded in these regions, and the drilling can be performed without chips or burrs penetrating between the components <NUM>, <NUM>. A counter support for the drilling and/or fastener insertion hence may in some variants not necessarily be required at this stage.

The manual, partially manual or automated installation of a final fastener <NUM>, <NUM> may be performed directly after drilling a single final hole <NUM>, <NUM> or may be performed after drilling a plurality of several final holes <NUM>, <NUM>.

<FIG> illustrates a variant of the first embodiment in which tacking the components <NUM>, <NUM> in the joining regions <NUM>, <NUM> is performed in a modified manner. In <FIG> on the left, a preliminary hole <NUM> is shown where tacking is performed using a tacking assembly 164a as described above. At another tacking position <NUM>, shown on the right in <FIG>, a different tacking assembly 164b is used, which differs from the assembly 164a in that the washers <NUM> and nuts <NUM> tightened against the components <NUM>, <NUM> are replaced by annular elements <NUM>, e.g. configured as spacer sleeves which may part of clamping devices 157b, 158b, abutting on the arrangement <NUM> from either side thereof. Hence, tacking by the tacking assembly 164b is accomplished when first and second clamping device parts 157b, 158b, substantially corresponding to parts 157a, 158a, are placed on the rod <NUM> and tightened against the annular elements <NUM> and the arrangement <NUM> using the nuts <NUM> and the washers <NUM>. The tacking assemblies 164a, 164b can be combined in one clamping device 155b, see <FIG>, or a clamping device including only tacking assemblies 164b may be used.

<FIG> and <FIG> show individual clamping forces Fc being applied from the first, outer side 118a and from the second, inner side 118b of the joint <NUM>. Regarding the tacking assembly 164b, the tightening torque applied to the nuts <NUM> takes account of reactions forces resulting from the clamping forces Fc which reduce the tacking force at the location of the tacking assembly 164b in <FIG>, in order to apply sufficient tacking there.

In a variant illustrated in <FIG>, clamping forces Fc are applied from both sides 118a, 118b as well. <FIG> shows a clamping device 155c comprising clamping device parts 157c, 158c. Coupling elements <NUM> are inserted through the preliminary holes <NUM> at the second fastening positions <NUM>, but different from <FIG> and <FIG>, the coupling elements <NUM> are each configured as bolts or screws comprising a head at one end thereof, in <FIG> at the lower end. Tightening is carried out using a single washer and a single nut for each coupling element <NUM>, the nut <NUM> being threaded on the screw <NUM> from the first side 118a. Between each device part 157c, 158c and the arrangement <NUM>, a washer-like annular element <NUM> is disposed or integrated to clamping devices 157c, 158c. Tacking at the positions <NUM> is performed in <FIG> when the nuts <NUM> are tightened, and at the same time, the clamping forces Fc are applied. The clamping device 155c comprises tacking assemblies 164c each formed with the screw <NUM>, the elements <NUM>, the washer <NUM> and nut <NUM> in cooperation with the device parts 157c, 158c. The nuts <NUM> are tightening in a manner taking account of reaction forces Fs in order to apply sufficient tacking by the assemblies 164c.

<FIG> shows a variant including a clamping device 155d, which differs from the device 155c in that one of the clamping device parts is replaced by a common rigid counter support part 158d. The counter support part 158d is arranged on the second side 118b, while a clamping device part 157d corresponding the clamping device part 158c of <FIG> is arranged on the first side 118a. A plurality of individual, in some examples separately adjustable, clamping forces Fc are applied from the first side 118a, while on the second side, pressure across an outer surface of the second component <NUM> in the joining region <NUM> is provided by the common rigid counter support part 158d, which may be a metal bar comprising through-holes for a shaft of each screw <NUM>. Also in <FIG>, tacking is accomplished using tacking assemblies 164d at the time of clamping by tightening the nuts <NUM>.

In <FIG>, a variant is shown including a clamping device 155e comprising a clamping device part 157e corresponding to the device part 157d of <FIG>, which is supported on the arrangement <NUM> using an annular element <NUM> at each second fastening location <NUM>. While in <FIG>, a backing bar 158d is provided in the form of the counter support part 158d, in the variant of <FIG> washers <NUM> directly abut on an outer surface of the second component <NUM> in the joining region <NUM>, from the second side 118b. Tacking is carried out by tightening nuts <NUM> on the second side 118b. In <FIG>, there is no backing bar, and the clamping device part 157e, adapted to apply individual forces Fc, is coupled to the arrangement <NUM> via the screws <NUM>, and via the washers <NUM> and nuts <NUM> acting as retaining pieces at the fastening positions <NUM>, for tacking and for supporting reaction forces resulting from the application of the clamping forces Fc.

The plurality <NUM> of second fastening positions <NUM> corresponds to a comparatively small fraction of the entire set of positions where fastening is to be carried out. For example, the plurality <NUM> corresponds to approximately <NUM> percent of the entire set of positions, while the plurality <NUM> of first fastenings positions corresponds to approximately <NUM> percent thereof. This enables a sufficient number of holes <NUM> for load transfer between the inner and outer sides 118b, 118a through the components <NUM>, <NUM>. However, the number of second fastening positions <NUM> and preliminary holes <NUM> can be modified and may be more or less than <NUM> percent.

While, for example, it is shown in <FIG> to remove both clamping device parts 157a, 158a before performing drilling, it is conceivable to remove only one of the device parts 157a, 158a, while the other one remains coupled to the arrangement <NUM> in order to serve as a counter support for drilling the final holes <NUM>, if desired. The remaining clamping device part may be adapted accordingly.

As in <FIG>, clamping and tacking are performed at the same time using the assemblies 164b-e, the clamping device parts 157b-e, 158b-d are removed after the sealant layer <NUM> has cured to a sufficient degree, and the tacking assemblies 164b-164e are de-installed along with the removal of the device parts 157b-e, 158b-d. In the variant of <FIG>, if desired, the tacking assembly 164a may temporarily remain in a manner analogous to <FIG>. Further, in the case of <FIG>, the tacking assemblies 164a may, if desired, be removed along with the device part 158a if the rod <NUM> as well as nuts and washers <NUM>-<NUM> should remain connected to part 158a.

Using the clamping devices 155a-e, the region of each drilling point or fastening position can be loaded with a specific clamping force during curing of the sealant <NUM>. In the area of the tacking positions <NUM>, a clamping force sufficient to ensure the required maximum sealant layer thickness is applied by installing and tightening the tacking assemblies 164a-e accordingly.

A clamping device 155f in accordance with a second embodiment is shown in <FIG>. The clamping device 155f comprises a first clamping device part 157f and a second clamping device part 158f each adapted to apply a plurality of individual clamping forces Fc onto the components <NUM>, <NUM> in the joining regions <NUM>, <NUM> as described above. However, the clamping device 155f is not coupled to the arrangement <NUM> using a mechanical connection established via preliminary holes. Instead, in <FIG>, forces for coupling the device parts 157f, 158f on the arrangement <NUM> and for accomplishing the clamping and for supporting reaction forces resulting from the individual forces Fc are transferred through the components <NUM>, <NUM> in a magnetic manner. In exemplary manner, <FIG> shows two magnetic device parts 186a coupled to the clamping device part 157f at the ends of the latter, on the first side 118a. In analogous manner, two magnetic device parts 186b are coupled to the clamping device part 158f on the second side 118b. Corresponding ones of the magnetic device parts 186a and 186b, arranged opposite to each other with a portion of one of the components <NUM> or <NUM> therebetween, form a magnetic device <NUM>. For example, the parts 186a can each be configured with a permanent magnet or with an electromagnet. The parts 186b can each be configured for example with a ferromagnetic core, so that the magnet in part 186a may exert a magnetic attraction force FM onto the part 186b. Alternatively, both parts 186a, 186b may be configured with permanent magnets or electromagnets in such a manner as to enable a magnetic attraction force FM between the parts 186a, 186b of each magnetic device <NUM>.

Preferably, the magnetic devices <NUM> are arranged in regions of the arrangement <NUM> where the components <NUM> and <NUM> are comparatively thin, further preferably outside of the joint <NUM> but next to it, for effective magnetic coupling of the magnetic device parts 186a-b.

In a method in line with the embodiment of <FIG>, it is not necessary to provide preliminary holes <NUM>. Accordingly, steps <NUM>-<NUM> in <FIG> may be reduced in such an embodiment to cleaning and activating the opposing surfaces of the joining regions <NUM>, <NUM>, applying the sealant compound <NUM> and positioning the components <NUM>, <NUM> to form the joint <NUM>. In a modified step <NUM>, clamping the components <NUM>, <NUM> in the joining regions <NUM>, <NUM> is accomplished by arranging the clamping device 155f on the arrangement <NUM> and magnetically coupling the magnetic device parts 186a-b, e.g. by supplying electric current to the electromagnets.

In particular, in accordance with the second embodiment, after the sealant layer <NUM> has sufficiently cured, the entire clamping device 155f is removed. Then, the arrangement <NUM>, with the joining regions <NUM>, <NUM> adhesively bonded, can be loaded e.g. into the combined automation station as described above, and drilling and installation of final fasteners can be carried out at substantially all fastening positions that are pre-defined by the design. In this manner, substantially no secondary drilling may be required and preliminary holes may not be needed. Instead, essentially all final fasteners can be installed following one-shot drilling.

A clamping device <NUM> according to a third embodiment is illustrated in <FIG>, comprising first and second clamping device parts <NUM>, <NUM> adapted to apply clamping forces Fc as in the case of <FIG>. Instead of magnetic forces, the clamping device <NUM> is coupled to the arrangement <NUM> and is retained on the arrangement <NUM> using vacuum pads <NUM>. In exemplary manner, at least one vacuum pad <NUM> is coupled to each end of each of the clamping device parts <NUM>, <NUM>. The vacuum pads <NUM> are retained on outer surfaces of the arrangement <NUM> using a negative pressure difference -Δp relative to the ambient pressure within a cavity <NUM> of each pad <NUM>.

Within a method according to the third embodiment, the clamping device <NUM> is used in a manner analogous to the process described above in relation to <FIG>, without the need for preliminary holes <NUM>, except in that after arranging the device <NUM> in place, a source of negative pressure is connected to the cavities <NUM>, e.g. via a valve. Preferably, the vacuum pads <NUM> are arranged in regions of the components <NUM> and <NUM>, respectively, where a surface thereof is substantially undisturbed or flat, to facilitate sealing the cavities <NUM> tightly with respect to the environment. Combinations of the embodiments 155f and <NUM> according to <FIG> with variants how to react clamping forces Fc according to <FIG> and/or <FIG> and/or <FIG> are possible.

Claim 1:
Method of assembling a structure (<NUM>) in aircraft or spacecraft production, comprising:
providing at least two components (<NUM>, <NUM>) to be joined to each other at a joint (<NUM>) in order to form a structural assembly (<NUM>, <NUM>), each of the components (<NUM>, <NUM>) comprising a joining region (<NUM>, <NUM>);
applying sealant (<NUM>) to at least one of the components (<NUM>, <NUM>) in the joining region (<NUM>, <NUM>) thereof;
forming an arrangement (<NUM>) by positioning the components (<NUM>, <NUM>) relative to each other, whereby an uncured layer (<NUM>) of the sealant (<NUM>) is formed between associated joining regions (<NUM>, <NUM>);
clamping the associated joining regions (<NUM>, <NUM>) against each other to achieve a clamped state using at least one clamping device (155a-<NUM>) and maintaining the clamped state of the associated joining regions (<NUM>, <NUM>) at least until the layer (<NUM>) of sealant therebetween and contacting the associated joining regions (<NUM>, <NUM>) has cured to a pre-defined degree, the clamping device (155a-155e) being installable on and transportable along with the arrangement (<NUM>); and
after the layer (<NUM>) of sealant has cured at least to the pre-defined degree, performing drilling at at least a plurality (<NUM>; <NUM>, <NUM>) of fastening positions (<NUM>; <NUM>, <NUM>) within the joining regions (<NUM>, <NUM>) in order to obtain a hole (<NUM>; <NUM>, <NUM>) of final dimension at each of the plurality of fastening positions (<NUM>; <NUM>, <NUM>), and performing installation of a final fastener (<NUM>; <NUM>, <NUM>) at each of the fastening positions (<NUM>; <NUM>, <NUM>), characterised in that the moment at which the sealant has cured to a pre-defined degree corresponds to a curing degree in which the sealant does not flow anymore and without external mechanical effect the joining regions (<NUM>, <NUM>) with the sealant in the pre-defined degree of curing inbetween remain unchanged in terms of their spatial arrangement relative to each other.