Abstract:
A method enabling two holes belonging to two parts to be aligned relies on use of a tool, comprising a body, having a first outer surface which gradually wanders from a longitudinal axis of the body as it extends from a first end of the body, and a hollow part having a second outer surface with a complementary section to the section of the holes. The hollow part comprises a hole through which it is removably mounted on the tool so that the second outer surface extends the first outer surface on an opposite side to the first end of the body. The method comprises inserting the first end of the body into the first hole, and then operating the tool to push the body and then the hollow part together into the holes. This method especially applies to the assembly of a floor module to an aircraft fuselage.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to French Patent Application FR 15 63263 filed Dec. 23, 2015, the entire disclosure of which is incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a method for aligning a first hole of a first part with a second hole of a second part, the first and second holes having similar respective cross sections. 
         [0003]    This method is in particular applicable to aircraft parts. For example, one of the parts may be an aircraft floor crosspiece, the other part then being a circumferential frame of an aircraft fuselage. 
       BACKGROUND 
       [0004]    In the known methods for assembling aircraft, the floor crosspieces are installed one by one in a purely structural environment. Indeed, their mode of installation, comprising in particular steps of machining attachment holes, means that system elements cannot be close by since these elements are vulnerable. 
         [0005]    However, it is possible to install multiple floor crosspieces at the same time, with relatively fragile systems close by. 
         [0006]    To that end, it is desirable to be able to avoid steps of machining the attachment holes at this stage of assembly, and thus to carry out assembly using previously machined attachment holes. 
         [0007]    However, the manufacturing tolerances of the parts are such that it is not possible to guarantee that the previously machined attachment holes will line up with one another with sufficient precision to ensure a good structural connection, this precision typically being of the order of a few hundredths of a millimeter. 
         [0008]    Similar considerations apply with regard to the assembly of other types of modules of the aircraft. 
       SUMMARY 
       [0009]    The disclosure herein has in particular the object of providing a simple, economical and effective solution to this problem. 
         [0010]    To that end, a method is disclosed for aligning a first hole of a first part with a second hole of a second part, the first and second holes having similar respective cross sections, the method comprising:
       providing a tool, comprising a body centered on a longitudinal axis and having a first outer surface that is progressively further from the longitudinal axis with increasing distance from a first end of the body, and providing a hollow part having a second outer surface whose cross section matches the cross section of each of the first and second holes and whose longitudinal extent is greater than a depth of the first hole, the hollow part comprising a hole by which the hollow part is removably mounted on the tool such that the second outer surface extends continuously with the first outer surface on a side opposite the first end of the body,   positioning the first part and the second part such that the first and second holes are at least partially facing one another, then   inserting the first end of the body into the first hole, then maneuvering the tool so as to push the body of the tool then the hollow part together into the first hole then into the second hole, then   disconnecting the body of the tool and the hollow part such that the hollow part remains lodged in the first hole and in the second hole.       
 
         [0015]    The variation in cross section of the first outer surface of the body of the tool makes it possible, as the body advances through the holes, to progressively align these holes. 
         [0016]    The method according to the disclosure herein thus provides an effective approach for aligning initially offset holes. 
         [0017]    In the context of its particular application to fitting aircraft modules to the structure of an aircraft, the method according to the disclosure herein makes it possible to avoid carrying out machining operations during assembly, and thus makes it possible to limit the risk of damage to the systems fitted to such modules. Once the holes used for assembling the parts can be machined before the assembly operations, these operations may in effect be reduced to simple bolting operations or the like. 
         [0018]    Preferably, the hollow part has a base, and maneuvering the tool is implemented until the base of the hollow part is pressed against the first part. 
         [0019]    In a preferred embodiment of the disclosure herein, the body of the tool has a longitudinal hole which passes right through it, the hole of the hollow part is a through-hole, the tool comprises a tension screw comprising a shank having a threaded portion and a head, and the tool comprises a tension device comprising a bearing surface and a nut secured to the bearing surface. 
         [0020]    The nut is configured so as to engage with the threaded portion of the shank, as will become more apparent below. 
         [0021]    In the preferred embodiment of the disclosure herein, the method comprises inserting the shank of the tension screw into the hole of the hollow part and into the longitudinal hole of the body of the tool, such that the body of the tool and the head of the tension screw sandwich the hollow part, and such that the threaded portion of the shank projects from the body of the tool beyond the first end of the body. 
         [0022]    In the preferred embodiment of the disclosure herein, the method comprises a subsequent step of pressing the bearing surface of the tension device against the second part, on a side opposite the side of the first part. 
         [0023]    In a preferred embodiment of the disclosure herein, maneuvering the tool comprises or consists of screwing the threaded portion of the shank into the nut of the tension device so as to cause a translation of the tension screw through the first and second holes by a “nut-and-bolt” effect. 
         [0024]    Moreover, the tension device advantageously comprises an antifriction member which locks the nut of the tension device in rotation during maneuvering of the tool. 
         [0025]    Preferably, the hole of the hollow part has an internal thread, and the method comprises a subsequent step comprising or consisting of screwing an attachment screw into the hole of the hollow part so as to press a head of the attachment screw against the second part and to clamp together the first part and the second part. 
         [0026]    Preferably, the body comprises an extension having an outer thread and extending beyond the first outer surface, on the opposite side from the first end of the body, and the method comprises a prior step comprising or consisting of mounting the hollow part removably onto the tool by screwing the extension of the body in the hole of the hollow part. 
         [0027]    In one particular application of the method, one of the first and second parts is an aircraft floor crosspiece and the other of the first and second parts is a circumferential frame of an aircraft fuselage. 
         [0028]    The disclosure herein also relates to a kit comprising, on one hand, a tool comprising a body centered on a longitudinal axis and having a first outer surface that is progressively further from the longitudinal axis with increasing distance from a first end of the body, and on the other hand, at least one hollow part having a second outer surface and comprising a hole by which the hollow part may be removably mounted on the tool such that the second outer surface extends continuously with the first outer surface on a side opposite the first end of the body. 
         [0029]    Preferably, the body has a longitudinal hole which passes through it, the hole of the hollow part is a through-hole, the tool comprises a tension screw comprising a shank able to pass through the hole of the hollow part and the longitudinal hole of the body and having a threaded portion, and a head, and the tool comprises a tension device, comprising a bearing surface, and a nut secured to the bearing surface, spaced apart from the latter, and configured to make it possible to screw the threaded portion of the shank into the nut. 
         [0030]    Preferably, the bearing surface extends perpendicular to the longitudinal axis of the body when the threaded portion of the shank is screwed into the nut. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The disclosure herein will be better understood, and other details, advantages and features thereof will emerge on reading the following description, given by way of non-limiting example and with reference to the appended drawings, in which: 
           [0032]      FIGS. 1 and 2  are partial schematic views in cross section of an aircraft fuselage, respectively before and after attachment of a floor crosspiece to a circumferential frame of the fuselage; 
           [0033]      FIGS. 3 and 4  are perspective views at a larger scale than  FIG. 2 , showing respectively a front side and a rear side of a connection region between the floor crosspiece and the circumferential frame of the fuselage; 
           [0034]      FIG. 5  is a partial schematic view in cross section of an aircraft fuselage, showing a problem of misalignment between attachment holes belonging respectively to the floor crosspiece and to the circumferential frame of the fuselage; 
           [0035]      FIG. 6  is a partial schematic perspective view of a kit designed for implementing an alignment method according to a preferred embodiment of the disclosure herein; 
           [0036]      FIGS. 7 through 14  are partial schematic views in section of two parts provided with respective holes to be aligned, and illustrate implementation of the alignment method according to the preferred embodiment of the disclosure herein, and  FIG. 7 a    is a schematic front view of the holes, showing their initial misalignment; 
           [0037]      FIG. 15  is a schematic perspective section view of the kit, during implementation of the alignment method according to the preferred embodiment of the disclosure herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]      FIG. 1  shows part of an aircraft fuselage  10  comprising in particular circumferential frames, and an aircraft floor module  12  comprising in particular floor crosspieces, before the module is fitted to the fuselage.  FIG. 1  shows in particular two lateral portions of one of the circumferential frames  13 , and a floor crosspiece  14 . 
         [0039]      FIG. 2  shows the same elements after the module  12  has been fitted to the fuselage, and illustrates in particular the floor crosspiece  14  attached to the two lateral portions of the circumferential frame  13 . To that end, the lateral portions of the circumferential frame  13  have respective attachment plates  16  which extend, toward one another, proud of the frame, and which each comprise a respective first hole, and the floor crosspiece  14  has two opposite ends each provided with a respective second hole. 
         [0040]    Attaching each one of the two ends of the floor crosspiece  14  to the corresponding attachment plate  16  is effected by a corresponding hollow part  18  which forms a nut ( FIG. 3 ) and is lodged together in the corresponding first hole of the floor crosspiece  14  and in the corresponding second hole of the attachment plate  16 , and by a corresponding attachment screw  20  screwed into the hollow part  18  ( FIG. 4 ). 
         [0041]    However, attaching the module  12  to the circumferential frames requires a very precise alignment of the first and second holes, which manufacturing tolerances are initially unable to provide, as shown in  FIG. 5  in which the misalignment between a first hole  22  and a corresponding second hole  24  is greatly exaggerated for illustrative purposes, the misalignment being typically of the order of a few millimeters. It is therefore necessary to realign these holes a posteriori. 
         [0042]    The disclosure herein proposes, to that end, a method for aligning a first hole of a first part, such as the hole  22  of the floor crosspiece  14 , with a second hole of a second part, such as the hole  24  of the corresponding attachment plate  16 . 
         [0043]    This method involves the use of a kit comprising a tool  30  associated with at least one hollow part such as the abovementioned hollow part  18 . 
         [0044]    In general terms, the tool  30  comprises a body  32  centered on a longitudinal axis  34  and having a first outer surface  36  that is progressively further from the longitudinal axis  34  with increasing distance from a first end  38  of the body  32  ( FIGS. 6, 7 and 15 ). In other words, the first outer surface  36  has a shape that widens from the first end  38  of the body  32 . 
         [0045]    Moreover, the hollow part  18  has a second outer surface  40  whose cross section essentially matches the cross section of each of the first and second holes  22 ,  24  and whose longitudinal extent L 1  is greater than the depth d 1  of the first hole  22  and preferably equal to or greater than the sum of the depth d 1  of the first hole  22  and the depth d 2  of the second hole  24  ( FIG. 7 ). “Essentially matching cross section” is intended to mean that the cross section of the second outer surface  40  may match or be slightly larger in diameter than the cross section of each of the first and second holes  22 ,  24 , to allow a tight or interference fit of the hollow part  18  in the holes  22 ,  24 , as will be more apparent in the following. 
         [0046]    Finally, the hollow part  18  fits removably onto the tool  30  such that the second outer surface  40  extends continuously with the first outer surface  36  on a side opposite the first end  38  of the body  32 , as will be more apparent in the following. This should be understood as meaning that the second outer surface  40  extends in continuation of the first outer surface  36 , that is to say forming no unevenness with the latter. 
         [0047]    In the preferred example shown, the body  32  is axisymmetric about the longitudinal axis  34 , that is to say that it has, at all points, a circular cross section centered on the longitudinal axis  34  ( FIGS. 6, 7 and 15 ). Of course, the diameter of this cross section increases along the longitudinal axis  34  from the first end  38  of the body  32 . 
         [0048]    In addition, the hollow part  18  is in the form of a flange nut, and therefore has a base  42  and a through-hole  43  provided with an internal thread  44 . Indeed, in the preferred embodiment of the disclosure herein, the method comprises a final step of clamping the two parts by the hollow part  18 , as will be more apparent in the following. 
         [0049]    The continuous nature of the hole  43  is designed to permit the passage of a tension screw, designed to maneuver the tool  30 , through the hollow part  18 , as will be more apparent in the following. 
         [0050]    As a variant, the hole  43  may not be continuous, when another mechanism is provided for maneuvering the tool  30 . The hole  43  is in this case a blind hole that is open on the side of the body  32  of the tool when the hollow part  18  is mounted on the tool  30 . 
         [0051]    As another variant, the method according to the disclosure herein may not comprise the final step of tightening the two parts, and the hollow part  18  may be a simple centering pin or the like. As the case may be, tightening the two parts  14  and  16  may then be done subsequently, for example by bolting through the centering pin. 
         [0052]    In the embodiment shown, the body  32  comprises an extension  46  having an outer thread  48  and extending beyond the first outer surface  36 , on the opposite side from the first end  38  of the body. The outer thread  48  is configured to screw into the internal thread  44  of the hollow part  18 . 
         [0053]    Furthermore, in the preferred embodiment of the disclosure herein, the body  32  has a longitudinal hole  50  which passes right through it. 
         [0054]    Moreover, the tool  30  comprises a tension screw  52  comprising a shank  54  having a threaded portion  56  and a smooth portion  57 , and a head  58 . The threaded portion  56  and the head  58  are arranged on either side of the smooth portion  57 . 
         [0055]    The tool also comprises a tension device  60  ( FIGS. 8 and 15 ), comprising a bearing surface  62  and a nut  64  secured to the bearing surface  62 . In the example shown, the tension device  60  comprises a flat ring  66  on which is formed the bearing surface  62  and which is connected to the nut  64  by arcuate arms  68  creating between them a space for receiving the body  32 . The nut  64  and the flat ring  66  are arranged coaxially, such that the bearing surface  62  extends perpendicular to a screwing axis defined by the nut  64  (and coincident with the longitudinal axis  34  in the figures). 
         [0056]    In addition, the tension device  60  comprises antifriction member which may for example take the form of a first antifriction washer  70  (shown only in  FIG. 15 ). 
         [0057]    The steps of the alignment method according to the preferred embodiment of the disclosure herein are shown in  FIGS. 7 through 14 . 
         [0058]    Initially, the first hole  22  and the second hole  24  are partially facing one another but are offset, as shown in  FIGS. 7 and 7   a.    
         [0059]    The method comprises a prior step comprising or consisting in mounting the hollow part  18  removably onto the tool  30  by screwing the extension  46  of the body  32  into the hollow part  18 , then a step comprising or consisting of inserting the smooth portion  57  of the shank  54  of the tension screw  52  in the longitudinal hole  50  of the body  32 , such that the body  32  of the tool and the head  58  of the tension screw sandwich the hollow part  18 , and such that the threaded portion  56  of the shank projects from the body  32  of the tool beyond the first end  38  of the body, as shown in  FIGS. 6 and 7 . 
         [0060]    More precisely, the body  32  has a shoulder  72  ( FIGS. 7 and 15 ) which connects the extension  46  of the body to the first outer surface  36 , and which forms a stop with regard to the hollow part  18 , preventing displacement of the latter relative to the body  32  parallel to the longitudinal axis  34 . 
         [0061]    In the example shown, a second antifriction washer  74  (shown only in  FIGS. 6 and 15 ) is interposed between the head  58  of the tension screw  52  and the hollow part  18 , in order to limit friction between the head  58  of the screw and the hollow part  18  during subsequent maneuvering of the tool  30 , and thus avoid damaging the hollow part  18 . 
         [0062]    It should be noted that the longitudinal hole  50  has a smooth inner surface to allow rotation of the shank  54  with respect to the body  32 . 
         [0063]    In the example shown, the head  58  of the tension screw  52  has a hexagonal drive socket  76 . Other head shapes are of course possible without departing from the scope of the disclosure herein. 
         [0064]      FIG. 6  thus shows the assembly consisting on one hand of the tool  30  and of the hollow part  18  in its state at the end of the prior method steps described hereinabove. 
         [0065]    The method then comprises a step comprising or consisting of:
       pressing the bearing surface  62  of the tension device  60  against the second part  16 , on a side opposite the side of the first part  14  ( FIG. 8 ), then,   with the body  32  of the tool positioned on the side of the first part  14 , inserting the threaded portion  56  of the shank  54  of the tension screw  52  then the first end  38  of the body  32  into the first hole  22 , then   maneuvering the tool  30  so as to push the body  32  of the tool then the hollow part  18  together into the first hole  22  then into the second hole  24 .       
 
         [0069]    The tool  30  is maneuvered by screwing the threaded portion  56  of the tension screw  52  into the nut  64  of the tension device  60 , preferably by an electric screwdriver. 
         [0070]    Due to the nut  64  being locked in rotation by the antifriction member, in this case the first antifriction washer  70  of  FIG. 15 , screwing the tension screw  52  into the nut  64 , symbolized by the arrow R of  FIG. 8 , results in a reaction F that tends to press the bearing surface  62  of the tension device  60  against the second part  16 , and thus produces translation T of the tension screw  52  through the first and second holes  22 ,  24  by a “nut-and-bolt” effect. 
         [0071]    Hence, the head  58  of the tension screw  52  pushes the body  32  then the hollow part  18  through the first and second holes  22 ,  24 . 
         [0072]    The variable-cross-section shape of the first outer surface  36  of the body  32  then makes it possible, as the body  32  advances through the holes  22 ,  24 , to progressively align these holes, as shown in  FIGS. 8 through 12 . 
         [0073]    At the end of the step of maneuvering the tool  30 , the hollow part  18  is lodged in both the first and second holes  22 ,  24  ( FIG. 12 ). In the preferred embodiment of the disclosure herein, the base  58  of the hollow part  18  is then pressed against the first part  14 . 
         [0074]    Moreover, the body  32  of the tool is received in the space created between the arms  68  of the tension device  60 . In particular, the bearing surface  62  surrounds the body  32  of the tool. 
         [0075]    In general, other shapes are possible insofar as the bearing surface  62  and the mechanism connecting it to the nut  64  are concerned. The bearing surface  62  may for example not be a continuous surface as in the example shown, but be made of several separate surfaces. It is thus possible for the bearing surface  62  not to surround the body  32  at the stage of the method described above with reference to  FIG. 12  but, in all cases, in any cross-sectional plane passing through the longitudinal axis  34 , the bearing surface  62  extends at a distance from the longitudinal axis  34 , this being greater than the distance between the second outer surface  40  of the hollow part  18  and the longitudinal axis  34  in order to permit the passage of the body  32 . 
         [0076]    The method continues with a step comprising or consisting of disconnecting the body  32  of the tool and the hollow part  18 , leaving the hollow part  18  lodged in the first hole  22  and in the second hole  24 , as shown in  FIG. 13 . This step comprises or consists for example of withdrawing the tension device  60  by unscrewing its nut  64  from the threaded portion  56  of the tension screw  52 , then in pulling the head  58  of the tension screw  52  so as to withdraw the tension screw  52  from the body  32 , then finally in withdrawing the body  32  by unscrewing the extension  46  thereof from the hollow part  18 . 
         [0077]    In the preferred embodiment of the disclosure herein, the method comprises a subsequent step comprising or consisting of screwing the attachment screw  20  into the hollow part  18  so as to press a head  92  of the attachment screw  20  against the second part  16  ( FIG. 14 ). The base  42  of the hollow part  18  and the head  92  of the attachment screw  20  thus clamp together the first part  14  and the second part  16 . 
         [0078]    Fitting the hollow part  18  in the holes  22 ,  24  may thus be carried out with great precision of adjustment, which permits optimum transfer of shear forces between the two parts  14  and  16 . 
         [0079]    Optionally, additional tension bolts (not shown in the figures) may be used close to the holes  22 ,  24  in order to ensure that the first part  14  is properly clamped to the second part  16 , and thus guarantee the effectiveness of the shear loading of the hollow part  18 . To that end, these traction bolts are installed with a large amount of play in corresponding holes of the two parts  14  and  16 . 
         [0080]    Moreover, the holes  22  and  24  may be formed directly in the parts  14  and  16 , as in the example described above. As a variant, these holes  22  and  24  may be formed in collars that are themselves installed in holes formed in the parts  14  and  16 . 
         [0081]    In general terms, the method and the kit according to the disclosure herein thus offer an effective means for aligning initially offset holes. 
         [0082]    In their particular application for fitting aircraft modules to the structure of an aircraft, the method and the kit according to the disclosure herein make it possible to avoid the implementation of machining operations during assembly, and thus make it possible to limit the risk of damaging systems fitted to such modules. Indeed, assembly may be reduced to simple bolting operations. 
         [0083]    In the particular case of applying the method and kit according to the disclosure herein to the attachment of the floor crosspiece  14  to the circumferential fuselage frame  13 , the method according to the disclosure herein makes it possible to subject the circumferential frame  13  to a slight stress by deforming it sufficiently to make the holes  22  of the floor crosspiece line up with the corresponding holes  24  of the plate  16  of the circumferential frame  13 . 
         [0084]    While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.