Method of assembling a part by riveting and associated assembly station

Abstract

Method for assembling a part by riveting and associated assembly station The present invention relates to a method for assembling a part, the method comprising riveting a stiffener (6) and a panel (4), the riveting comprising the following steps: - inserting a rivet (8) into the positioned assembly (44) of the stiffener (6) and the panel (4), the rivet (8) comprising a head (16) and a shank (18), - acquiring a protruding shank height (A) of said positioned assembly (44), - determining a target crushing height so that a maximum diameter of a rivet button (20), after crushing, is between an authorized lower limit and an authorized upper limit, the target crushing height being determined as a function of the acquired protruding shank height (A), - crushing the rivet (8) to form the rivet button (20) until the rivet button (20) has the target height determined crushing. Figure for abstract: 5

Description

Title of the invention: Method of assembling a part by riveting and associated assembly station

[0001] The present invention relates to a method of assembling a part, the part comprising at least one stiffener and one panel, the method comprising riveting the stiffener and the panel,

[0002] riveting comprising the following steps:

[0003] - positioning of the stiffener and the panel, the positioned assembly of the stiffener and of the panel delimiting a through hole,

[0004] - inserting a rivet into the through hole, the rivet comprising a head and a shank,

[0005] - crushing the rivet to form a rivet button opposite said head by report audit set positioned.

[0006] The crushing is notably for example implemented by a riveting system comprising two robot arms facing each other: a master robot arm carrying the effector for the crushing, and a slave robot arm carrying the effector with the counter-pile, the master robot arm and the slave robot arm being arranged for example on either side of the positioned assembly of the stiffener and the panel.

[0007] In known assembly methods, it is common to use the same rivet reference for several thicknesses to be assembled of the panel and the stiffener. A rivet reference is associated with the same calibrated dimensions within predetermined manufacturing tolerances. The riveting system is then controlled solely as a function of the rivet reference used to implement the crushing.

[0008] Furthermore, by regulation, it is necessary that a maximum diameter of the rivet button, after crushing, is between an authorized lower limit and an authorized upper limit. It is also necessary that a maximum height of the rivet button, after crushing, is likewise between authorized lower and upper limits.

[0009] However, the methods known above are not satisfactory in this regard, insofar as they generate an unsatisfactory number of non-conformities, the non-conformities including cases where the rivets are crushed too much or not enough. In such cases of non-conformities, it is then necessary to carry out curative actions of manual retouching by an operator, which involves a loss of time and additional costs.

[0010] The origin of these non-conformities corresponds to an uncontrolled combination of numerous parameters, such as the manufacturing tolerance of the dimensions of the rivets. for the same rivet reference, the tolerance on the countersink depth, variable thicknesses to be assembled, operators who manually determine the settings by a heavy process including crushing tests, target adjustment, and confirmation tests.

[0011] In particular, the inventors have shown that determining the same target crushing height for several thicknesses to be assembled is not possible: in certain cases the diameter and height of the rivet button obtained would not be compliant.

[0012] An aim of the invention is therefore to provide a method and an assembly station making it possible to assemble a part, improving reliability and reducing costs.

[0013] The invention relates to an assembly method of the aforementioned type, characterized in that the riveting comprises, before the crushing step, the following steps:

[0014] - acquisition of a barrel height exceeding said positioned assembly,

[0015] - determination of a target crushing height so that a maximum diameter of the rivet button, after crushing, is between an authorized lower limit and an authorized upper limit, the target crushing height being determined according to at least one determining parameter including the acquired exceeding barrel height;

[0016] and in that the rivet crushing step is carried out until the rivet button has the determined crushing target height.

[0017] The method according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:

[0018] - the crushing step is implemented by a riveting system comprising at minus a counter and a hammer, the inserted rivet being crushed between the counter and the hammer during crushing, the riveting system being controlled by a processing unit to implement the crushing step, the determining step being implemented by the processing unit;

[0019] - the riveting system comprises at least one robot arm carrying one of the counter-pile and of the hammer, preferably at least two robot arms carrying the counter and the hammer respectively;

[0020] - the rivet extends along a longitudinal axis from the head to one end opposite, the positioned assembly of the stiffener and the panel defining a distal face through which the shank of the rivet protrudes, the height of the protruding shank corresponding to the height between the distal face and said opposite end of the rivet;

[0021] - the determination of the target crushing height is such that, for the same rivet, the determined target crushing height is different for different acquired overhanging barrel heights;

[0022] - the determining parameters according to which the target crushing height is determined further include a diameter of the barrel of the inserted rivet and / or a parameter representative of a swelling of the rivet in the through hole during crushing;

[0023] - the step of determining the target crushing height comprises a sub-step of acquiring said authorized lower and upper limits of maximum diameter of the rivet button, after crushing; and a sub-step of acquiring authorized lower and upper limits of maximum height of the rivet button, after crushing;

[0024] - the step of determining the target crushing height comprises:

[0025] - a sub-step of acquiring an evolution curve, associated with the height of the barrel acquired excess, linking the evolution of the rivet height to the evolution of the rivet diameter during crushing;

[0026] - a sub-step of determining a maximum height conforming from the evolution curve and a sub-step of determining a minimum compliant height from the evolution curve, to obtain, after crushing, a maximum diameter of the rivet button between the lower authorized diameter limit and the upper authorized diameter limit, the target crushing height being determined to be between the maximum compliant height and the minimum compliant height.

[0027] - the sub-step of determining the maximum compliant height comprises the determination mination of the point of intersection between the evolution curve and the lower authorized diameter limit, and:

[0028] * if the height associated with the point of intersection is between the limits in lower and upper permitted height, then the maximum conforming height is determined to be said intersection height, and

[0029] * if the height associated with the intersection point is greater than or equal to the bound su upper permitted height limit, then the maximum compliant height is determined as being said upper permitted height limit,

[0030] and / or, in which the sub-step of determining the minimum compliant height comprises determining the point of intersection between the evolution curve and the authorized upper diameter limit.

[0031] * if the height associated with the point of intersection is between the limits in lower and upper permitted height, then the minimum conforming height is determined to be said intersection height, and

[0032] * if the height associated with the intersection point is less than or equal to the in terminal lower permitted height limit, then the minimum conforming height is determined as being said lower permitted height limit,

[0033] - the target crushing height is determined according to a linear relationship depending of the maximum compliant height and the minimum compliant height;

[0034] - the determining parameters according to which the target crushing height is determined also include a safety factor a, such that the target crushing height depends on the relationship a + CB, the safety factor being less than 1.0;

[0035] - the safety coefficient is strictly greater than 0.5;

[0036] - the sub-step of acquiring the evolution curve comprises the interrogation of a abacus curve database and retrieving the abacus curve associated with the acquired overhang height from among said curves in the database; and

[0037] - the lower limit allowed for diameter and the upper limit allowed for diameter depend respectively on the diameter of the barrel of the inserted rivet.

[0038] Furthermore, the invention relates to a station for assembling a part, the part comprising at least one stiffener and one panel, the assembly station comprising:

[0039] - a system for positioning the stiffener and the panel,

[0040] - a riveting system suitable for implementing the crushing of a rivet inserted in a through hole defined in the positioned assembly of the stiffener and the panel, the rivet comprising a head and a shank, the crushing being implemented to form a rivet button opposite said head relative to said positioned assembly,

[0041] characterized in that the assembly station also comprises:

[0042] - a system for acquiring a barrel height protruding from the positioned assembly, And,

[0043] - a processing unit configured to determine a target crush height so that a maximum diameter of the rivet button, after crushing, is between an authorized lower limit and an authorized upper limit, the target crushing height being determined according to at least one determining parameter including the height of the protruding barrel acquired by the acquisition system;

[0044] the processing unit being configured to control the riveting system to implement the crushing until the rivet button has the determined crushing target height.

[0045] The invention will be better understood on reading the following description, given solely by way of example, and made with reference to the attached drawing, in which:

[0046] [Fig-1] [Fig.l] is a schematic sectional view of an example of a part produced by an assembly method according to the invention;

[0047] [Fig.2] [Fig.2] is a schematic view of an assembly station according to one embodiment of the invention;

[0048] [Fig.3] [Fig.3] is a schematic flowchart of an assembly method according to one embodiment of the invention;

[0049] [Fig.4][Fig.5][Fig.6] Figures 4 to 6 are schematic views of stages of the method of [Fig.3];

[0050] [Fig.7] [Fig.8] [Fig.9] Figures 7 to 9 are schematic graphs illustrating evolution curves representative of the trajectory of the geometry of the rivet button as it is crushed.

[0051] An example of part 2 produced by an assembly method 100 according to the invention is illustrated in [Fig.l].

[0052] The part 2 is preferably an aircraft part. The part 2 forms, for example, an exterior surface element of an aircraft. Alternatively, the part 2 is an interior surface element of an aircraft, for example, a partition.

[0053] For example, part 2 forms a fuselage element. Alternatively, part 2 is a wing or empennage element. Part 2 is, for example, a lower or upper wing surface.

[0054] Alternatively, part 2 is a part intended for an application other than an aircraft.

[0055] Part 2 comprises the assembly of a panel 4 and at least one stiffener 6, by means of a rivet 8.

[0056] The panel 4 is preferably plate-shaped. For example, it has a curved three-dimensional profile.

[0057] The panel 4 comprises a first surface 12, and a second surface 14 opposite the first surface 12.

[0058] Each stiffener 6 is applied to the first surface 12 of the panel 4 and has a profile complementary to the profile of the first surface 12.

[0059] The thickness of the panel 4 is for example greater than the thickness of the stiffener 6.

[0060] The thickness of the panel 4 taken between the first surface 12 and the second surface 14 is typically between 1 mm and 5 mm. For a wing element, the thickness is typically between 5 mm and 20 mm.

[0061] The panel 4 and the stiffener 6 are made of metal, advantageously aluminum or aluminum alloy.

[0062] The panel 4 and the stiffener 6 are of the same metal shade or of different metal shades.

[0063] The rivet 8 comprises a head 16, a shank 18 and, once assembled, a rivet button 20, the rivet button 20 being formed during the crushing of the rivet 8.

[0064] The rivet button 20 is opposite the head 16, the barrel 18 connecting the head 16 to the rivet button 20.

[0065] In one embodiment, the rivet button 20 has a rounded peripheral lateral face, due to crushing.

[0066] The part 2 is advantageously manufactured using an assembly station 22 illustrated schematically in [Fig.2].

[0067] The assembly station 22 is in particular suitable for implementing the method assembly 100 which will be described later.

[0068] The assembly station 22 comprises a positioning system 24 for the panel 4 and the stiffener 6, a riveting system 26, a system 28 for acquiring a protruding barrel height and a processing unit 30.

[0069] The assembly station 22 also preferably comprises a device 32 for machining a through hole 36.

[0070] The assembly station 22 also advantageously comprises a device 34 for inserting a rivet 8 into the through hole 36.

[0071] The positioning system 24 is suitable for implementing the positioning of the stiffener 6 and the panel 4 for assembly.

[0072] The positioning system 24 comprises, for example, a frame 38 for holding the panel 4 in position.

[0073] The frame 38 comprises hooks 40 suitable for holding the panel 4 in position in a predetermined assembly position, in particular relative to the riveting system 26 during the crushing of the rivet 8.

[0074] The frame 38 is capable of supporting the forces generated during riveting by the riveting system 26.

[0075] The positioning system 24 comprises, for example, at least one member 42 for holding the stiffener 6 in position against the panel 4, in particular when the rivet 8 is crushed.

[0076] Other positioning systems 24 are known to those skilled in the art and will not be described in more detail hereinafter.

[0077] The machining device 32 is suitable for machining a through hole 36 in the positioned assembly 44 of the panel 4 and the stiffener 6.

[0078] The through hole 36 is preferably countersunk, as illustrated in Figures 1, 5 and 6. In this case, the machining device 32 is suitable for countersinking the machined through hole 36.

[0079] Such machining devices are known to those skilled in the art and will not be described in further detail hereinafter.

[0080] The insertion device 34 is suitable for inserting a rivet 8 into the through hole 36.

[0081] The insertion device 34 is for example suitable for gripping a rivet 8 and inserting it in through hole 36.

[0082] The rivet 8 then comprises a head 16 and a shank 18, the insertion device 34 being suitable for inserting the rivet 8 so that the head 16 is in abutment in the through hole 36.

[0083] Such insertion devices are known to those skilled in the art and will not be described in further detail hereinafter.

[0084] The acquisition system 28 is capable of acquiring, after insertion of the rivet 8, a barrel height exceeding A of the positioned assembly 44 (figures 4 and 5).

[0085] The acquisition system 28 operates for example by laser telemetry.

[0086] Other acquisition systems are known to those skilled in the art and will not be described in more detail below.

[0087] The riveting system 26 is capable of implementing the crushing of a rivet 8 inserted into the through hole 36 delimited in the positioned assembly 44 of the stiffener 6 and the panel 4 to form a rivet button 20 opposite said head 16 relative to said positioned assembly 44.

[0088] To do this, the riveting system 26 comprises at least one counterpile 46 and a hammer 48, the inserted rivet 8 being crushed between the counterpile 46 and the hammer 48 during crushing.

[0089] Advantageously, the riveting system 26 also includes a control system 50 for the counterpiece 46 and the hammer 48.

[0090] The control system 50 is capable of moving and positioning the counterpile 46 and / or the hammer 48, relative to the positioned assembly 44 of the panel 4 and the stiffener 6.

[0091] The control system 50 is also capable of exerting a force, applied respectively by the counter 46 and / or the hammer 48, on the positioned assembly 44 of the panel 4 and the stiffener 6.

[0092] In the case of the hammer 48, this is in particular a crushing force of the rivet 8 at the head 16 of the rivet 8, and in the case of the counter-pile 46, this is in particular a counter-support force at the end 62 of the rivet 8 opposite the head 16.

[0093] In a preferred embodiment, the control system 50 comprises at least one robot arm 52A, 52B carrying one of the counterpile 46 and the hammer 48. As illustrated in [Fig.2], the control system 50 advantageously comprises at least two robot arms 52A, 52B carrying respectively the counterpile 46 and the hammer 48.

[0094] Each robot arm 52A, 52B comprises a control head 54 and a mechanical chain 56 for controlling the control head 54.

[0095] One of the robot arms is a master robot arm 52A carrying the hammer 48, the hammer 48 being for example secured to its control head 54, and the other of the robot arms is a slave robot arm 52B carrying the counterpile 46, the counterpile 46 being for example secured to its control head 54.

[0096] One of the robot arms 52A, 52B, for example the master robot arm 52A, also preferably carries the machining device 32 and / or the insertion device 34, the machining device 32 and / or the insertion device 34 being for example integral with its control head 54. In this case, the control system 50 is capable of moving and positioning the machining device 32 to implement the machining and / or the insertion device 34 to implement the insertion.

[0097] In the assembly station 22, as illustrated in [Fig.2], the robot arms 52A, 52B are arranged relative to the frame 38 of the positioning system 24 of so as to be on either side of the positioned assembly 44 of the panel 4 and the stiffener 6.

[0098] The mechanical control chain 56 of each robot arm 52A, 52B is capable of moving and positioning the control head 54, relative to the positioned assembly 44 of the panel 4 and the stiffener 6, and of exerting said force on the positioned assembly 44 by its control head 54.

[0099] Advantageously, each robot arm 52A, 52B is capable of moving the control head 54 in at least two distinct spatial directions, and preferably at least three distinct spatial directions.

[0100] The robot arm 52A, 52B is articulated and the mechanical control chain 56 then comprises at least two axes of rotation, preferably at least three axes of rotation, advantageously at least four axes of rotation, better still at least five axes of rotation and in particular at least six axes of rotation.

[0101] At least two, preferably at least three, of the axes of rotation are non-parallel in pairs. Advantageously, all the axes of rotation are non-parallel in pairs.

[0102] Generally, for each axis of rotation, the mechanical control chain 56 comprises two articulation elements and an articulation joining the two articulation elements, the axis of rotation passing through the articulation. By means of the articulation, the two articulation elements are movable relative to each other around the axis of rotation.

[0103] For each joint, the robot arm 52A, 52B comprises at least one drive motor capable of driving in rotation, around the axis of rotation of the joint, one of the articulation elements of the joint relative to the other.

[0104] Each drive motor is for example an AC servo motor.

[0105] The processing unit 30 is also configured to control each drive motor of each robot arm 52A, 52B.

[0106] The processing unit 30 is configured to control at least the riveting system 26, and in particular the control system 50.

[0107] To do this, the processing unit 30 comprises for example a computer processing device 58 and a memory 60, the computer processing device 58 being operatively connected to the memory 60.

[0108] The processing device 58 comprises for example at least one processor, the memory 60 then receiving software modules suitable for being executed by the processor to carry out functions described subsequently for the steps of the assembly method 100.

[0109] The computer processing device 58 comprises, for example, a single processor. Alternatively, the computer processing device 58 comprises several processors, which are located in the same geographical area, or are, at least partially, located in different geographical areas and are then able to communicate with each other.

[0110] By the term "memory" is meant any volatile or non-volatile computer memory suitable for the subject matter now disclosed, such as random access memory (RAM), read only memory (ROM) or other electronic, optical, magnetic or other computer-readable storage medium on which data and control functions as hereinafter described are stored.

[0111] Therefore, the memory 60 is a tangible storage medium where the data and control functions are stored in a non-transitory form.

[0112] Alternatively, the processing device 58 comprises a microcontroller, a field programmable gate array (FPGA) and / or a dedicated integrated circuit (ASIC) capable of executing various data processing operations and functions, in particular capable of executing at least the functions described below for the steps of the assembly method 100.

[0113] As will be described subsequently for the method 100, the processing unit 30 is configured to determine a target crushing height CT so that a maximum diameter of the rivet button 20, after crushing, is between an authorized lower limit Bmin and an authorized upper limit Bmax, the target crushing height CT being determined as a function of at least one determining parameter comprising the height of the barrel exceeding A acquired by the acquisition system 28.

[0114] The processing unit 30 is also configured to control the riveting system 26 to implement the crushing until the rivet button 20 has the determined crushing target height CT. For example, the processing unit 30 is also configured to control the control system 50.

[0115] The processing unit 30 is further configured to communicate with the acquisition system 28 to recover the height of the barrel exceeding A acquired, preferably to control the acquisition system 28. The communication (represented in dotted lines in [Fig.2]) is for example made via a wired link or a wireless link.

[0116] Furthermore, where appropriate, the processing unit 30 is further configured to control the machining device 32 and / or the insertion device 34.

[0117] A method of assembling 100 the aircraft part 2 will now be described, with reference to FIGS. 3 to 6. The assembly method 100 is for example implemented by the assembly station 22 described above.

[0118] The method 100 comprises the provision 102 of the stiffener 6 and the panel 4, described above, and of at least one rivet 8, initially separated.

[0119] The rivet 8 provided comprises a head 16 and a shank 18. The rivet 8 extends along an axis longitudinal X from the head 16 to an opposite end 62.

[0120] The rivet 8 has a total height defined as the distance, taken along the longitudinal axis X, between the head 16 and said opposite end 62.

[0121] The barrel 18 has, for example, a constant cross-section, along the longitudinal axis X, from the head 16 to the opposite end 62. The barrel 18 is cylindrical, for example of revolution. Alternatively, the barrel 18 has any other cross-section.

[0122] The head 16 has, for example, a conical shape widening from the shaft 18. Alternatively, the head 16 is round, flat or has any other shape.

[0123] According to the invention, the method 100 comprises the riveting 104, by the rivet 8, of the stiffener 6 and the panel 4 provided. At the end of the riveting 104, as illustrated in [Fig.l], the rivet button 20 must have a maximum diameter between an authorized lower limit Bmin and an authorized upper limit Bmax and a maximum height between an authorized lower limit Cmin and an authorized upper limit Cmax.

[0124] In the assembly method 100, the entire riveting 104 described below is for example repeated for a plurality of separate rivets 8 on the same panel 4 and stiffener 6.

[0125] The riveting 104 comprises a step 106 of positioning the stiffener 6 and the panel 4.

[0126] The positioning step 106 is for example implemented by the positioning system 24 of the assembly station 22.

[0127] The panel 4 is arranged and held in position in the predetermined assembly position by the holding frame 38 and the stiffener 6 is held in position against the panel 4 by the holding member.

[0128] In method 100, the positioned assembly 44 of the stiffener 6 and the panel 4 then delimits a through hole 36.

[0129] To do this, in an exemplary embodiment, following positioning 106, riveting 104 comprises a step 108 of machining the through hole 36 in the positioned assembly 44 of the panel 4 and the stiffener 6.

[0130] The machining step 108 is for example implemented by the machining device 32 of the assembly station 22.

[0131] In the embodiment of [Fig.2], the processing unit 30 controls the control system 50 to move and position the machining device 32 to implement the machining 108.

[0132] The through hole 36 has a shape suitable for cooperating with the rivet 8.

[0133] The through hole 36 has at least one cylindrical portion, having for example a cross-section corresponding substantially to the cross-section of the barrel 18 of rivet 8.

[0134] The cylindrical portion of the through hole 36 has a height less than the height of the shank 18 of the rivet 8. In other words, once inserted as described below, the rivet 8 has a portion of the shank protruding from the positioned assembly 44 of the panel 4 and the stiffener 6. Said portion of the protruding shank 18 is intended to form the rivet button 20 by crushing.

[0135] The through hole 36 is preferably countersunk, as illustrated in Figures 1, 5 and 6. In this case, the machining step 108 comprises countersinking the through hole 36.

[0136] The through hole 36 is countersunk for example at the level of the second surface 14 of the panel 4.

[0137] The through hole 36 then further has a countersunk section extending from the cylinder portion. The countersunk section corresponds substantially to the shape of the head 16 of the rivet 8.

[0138] The riveting 104 subsequently comprises a step 110 of inserting the rivet 8 into the through hole 36.

[0139] The rivet 8 is inserted so that the head 16 is in abutment in the through hole 36.

[0140] In particular, the head 16 is in abutment, being received in the countersunk section of the hole. crossing 36, for example so that the head 16 is flush with the second surface of the panel 4.

[0141] At this stage, the positioned assembly 44 of the stiffener 6 and the panel 4 defines a distal face 64 through which a portion of the shaft 18 of the rivet 8 protrudes. The distal face 64 is in this example a face of the stiffener 6.

[0142] The insertion step 110 is for example implemented by the insertion device 34 of the assembly station 22.

[0143] In the embodiment of [Fig.2], the processing unit 30 controls the control system 50 to move and position the insertion device 34 to implement the insertion 110.

[0144] In the invention, the riveting 104 also comprises the steps of acquiring 112 a height of barrel exceeding A of said positioned assembly 44, of determining 114 a target crushing height CT, then of crushing 116 of the rivet 8 to form a rivet button 20 opposite said head 16 relative to said positioned assembly 44.

[0145] The acquisition step 112 is for example implemented by the acquisition system 28, preferably being controlled by the processing unit 30.

[0146] The height of the barrel extending beyond A corresponds to the height between the distal face 64 of the positioned assembly 44 and the end 62 of the inserted rivet 8 opposite the head 16.

[0147] In other words, the height of the barrel exceeding A corresponds to the height of the portion of the inserted rivet 8 projecting relative to the positioned assembly 44.

[0148] The height of the barrel exceeding A is in particular taken along the longitudinal axis X.

[0149] The height of the barrel exceeding A is thus taken locally perpendicular to the set positioned 44.

[0150] To do this, in an exemplary embodiment illustrated in Figures 4 and 5, the acquisition system 28 carries out the acquisition ([Fig.4]) of a first measurement of the position of the stiffener 6, for example relative to the longitudinal axis X; the acquisition ([Fig.5]) of a second measurement of the position of the end 62 of the inserted rivet 8 opposite the head 16, for example relative to the longitudinal axis X; and the determination of a height of the shaft exceeding A of said positioned assembly 44 from said measurements.

[0151] In the invention, during the determination step 114, the target crushing height CT is determined so that a maximum diameter of the rivet button 20, after crushing 116, is between the authorized lower limit Bmin and the authorized upper limit Bmax.

[0152] The determination step 114 is for example implemented by the processing unit 30.

[0153] Step 114 of determining the target crushing height CT comprises a sub-step 117A of acquiring authorized lower and upper limits Bmin, Bmax of the maximum diameter of the rivet button 20, after crushing 116.

[0154] Step 114 of determining the target crushing height CT also comprises a sub-step 117B of acquiring authorized lower and upper limits Cmin, Cmax of the maximum height of the rivet button 20, after crushing 116.

[0155] The limits Bmin, Bmax, Cmin, Cmax are for example determined by a design office prior to the implementation of method 100, for example to comply with regulatory requirements.

[0156] The terminals Bmin, Bmax, Cmin, Cmax each depend for example respectively on the diameter of the barrel 18 of the inserted rivet 8, advantageously according to a linear function of the diameter of the barrel 18 of the inserted rivet 8.

[0157] The terminals Bmin, Bmax, Cmin, Cmax are for example stored in the memory 60 of the processing unit 30.

[0158] During the determination step 114, the target crushing height CT is determined as a function of at least one determining parameter comprising at least the acquired exceeding barrel height A.

[0159] Thus, the determination of the target crushing height CT is such that, for the same rivet 8, the target crushing height CT determined is different for different acquired protruding barrel heights.

[0160] In particular, the target crushing height CT is not determined based on of a rivet reference 8 used.

[0161] As described below, the determining parameters further comprise a diameter d of the shaft 18 of the inserted rivet 8 and / or a parameter g representative of a swelling of the rivet 8 in the through hole 36 during crushing 116.

[0162] The determining parameters are acquired by communication between the processing unit 30 and the acquisition system 28, or are for example stored in the memory 60 of the processing unit 30.

[0163] The determining parameters stored in the memory 60 include for example the diameter d of the barrel 18 of the inserted rivet 8 and / or the parameter g representative of a swelling of the rivet 8 described below.

[0164] Step 114 of determining the target crushing height CT also comprises a sub-step 118 of acquiring an evolution curve, associated with the acquired protruding barrel height A, linking the evolution of the rivet height C to the evolution of the rivet diameter B during the crushing 116 from an initial height corresponding to the acquired protruding barrel height A.

[0165] In other words, the evolution curve is representative of the trajectory of the geometry of the rivet button as the crushing 116 progresses. The rivet button designates the portion of the barrel 18 protruding from the rivet 8 during the crushing 116.

[0166] Examples of evolution curves are illustrated in Figures 7 to 9. The curves illustrate a restricted zone 66 corresponding to the framing of the graph by the limits Bmin, Bmax, Cmin, Cmax.

[0167] The rivet height C is defined as the height of the protruding barrel, taken along the longitudinal axis X of the rivet 8.

[0168] The rivet diameter B is defined as the maximum diameter of the rivet button, taken perpendicular to the longitudinal axis X of the rivet 8. This is in particular the maximum diameter of the domed rivet button, due to the crushing 116.

[0169] The acquired evolution curve has an initial rivet height substantially equal to the acquired protruding barrel height A. The evolution curve has an initial rivet diameter equal to the diameter of the barrel 18 of the inserted rivet 8.

[0170] The evolution of the rivet height C is a strictly decreasing function of the rivet diameter B, during crushing 116.

[0171] The inventors have shown that the evolution curve is representative of a model curve verifying:

[0172] A(d+8y-i{^^ C -

[0173] Where C = rivet height (mm)

[0174] B = maximum diameter of the rivet button (mm)

[0175] A = height of barrel exceeding acquired (mm)

[0176] d = diameter of the rivet barrel (mm)

[0177] g = parameter representative of a swelling of the rivet in the through hole (in the cylindrical portion of the hole in particular) during crushing (mm)

[0178] L = total height of the rivet, before crushing (mm)

[0179] This model curve is derived from the conservation of the volume of the inserted rivet 8, taking into account the swelling of the part of the rivet 8 present in the through hole 36. The parameter g is for example determined experimentally during a preliminary phase before the implementation of the riveting 104 of the method 100.

[0180] In one embodiment, the sub-step 118 of acquiring the evolution curve comprises querying a database of abacus curves and retrieving the abacus curve associated with the acquired exceeding height A from among said curves in the database.

[0181] The database is for example stored in the memory 60 of the processing unit 30.

[0182] Each abacus curve was for example determined experimentally during a preliminary phase before the implementation of the riveting 104 of the method 100.

[0183] For example, the acquired evolution curve corresponds to the curve among said curves of the database which presents the initial rivet height closest to the acquired protruding barrel height A from step 112 and which presents a diameter of the barrel of the rivet closest to the diameter d of the inserted rivet.

[0184] Step 114 of determining the target crushing height CT comprises a sub-step 120 of determining a maximum compliant height CA from the evolution curve and a sub-step 122 of determining a minimum compliant height CB from the evolution curve, to obtain, after crushing 116, a maximum diameter of the rivet button 20 between the authorized lower limit Bmin and the authorized upper limit Bmax.

[0185] Sub-step 120 of determining the maximum compliant height CA comprises determining the point of intersection between the evolution curve and the authorized lower limit of the diameter Bmin.

[0186] * if the height associated with the intersection point is between the limits in lower and upper permitted Cmin, Cmax, then the maximum compliant height CA is determined as being said intersection height (figures 7 and 8), and

[0187] * if the height associated with the intersection point is greater than or equal to the bound su upper authorized limit Cmax, then the maximum compliant height CA is determined as being said upper authorized limit Cmax ([Fig.9]),

[0188] Preferably, if the height associated with the intersection point is less than the authorized lower bound Cmin, an alert is generated. The alert generated is for example representative of a height of the acquired exceeding barrel A too small to implement a proper crush.

[0189] The generated alert is for example communicated to an operator via a human-machine interface, for example in audio and / or visual form.

[0190] Sub-step 122 of determining the minimum compliant height CB comprises determining the point of intersection between the evolution curve and the authorized upper limit of the diameter Bmax.

[0191] * if the height associated with the intersection point is between the limits in lower and upper permitted Cmin, Cmax, then the minimum compliant height CB is determined as being said intersection height (figures 8 and 9), and

[0192] * if the height associated with the intersection point is less than or equal to the in terminal lower authorized limit Cmin, then the minimum conforming height CB is determined as being said lower authorized limit Cmin ([Fig.7]),

[0193] Preferably, if the height associated with the intersection point is greater than the authorized upper limit Cmax, an alert is generated. The alert generated is for example representative of a height of the barrel exceeding acquired A too great to implement a compliant crushing.

[0194] The generated alert is for example communicated to an operator via a human-machine interface, for example in audio and / or visual form.

[0195] The target crush height CT is subsequently determined to be between the maximum compliant height CA and the minimum compliant height CB, preferably according to a linear relationship depending on CA and CB.

[0196] The determining parameters according to which the target crushing height CT is determined also preferably comprise a safety coefficient a, for example stored in the memory 60 of the processing unit 30.

[0197] The target crush height CT depends on the relationship (CA - CB)*a + CB. The target crush height CT is for example equal to this relationship. We then have:

[0198] [Math.2] CT- (CA-CB)a + CB

[0199] The safety coefficient a is constant and is less than 1.0.

[0200] The safety coefficient is intended to take into account an uncertainty on the implementation of the crushing 116, for example by the control system 50.

[0201] Preferably, the safety coefficient a is strictly greater than 0.5.

[0202] Such a choice is advantageous, insofar as a crushing error is more easily correctable. Indeed, the target crushing height CT is then closer to the maximum compliant height CA than to the minimum compliant height CB. In the event of a crushing error, it will be possible in particular to correct the riveting by further crushing the rivet button 20 obtained. The correction is therefore easier in comparison with a target height chosen too close to the minimum height CB compliant and for which a crushing error presents the risk of falling below the minimum CB compliant height and therefore requiring the total removal of the rivet inserted 8.

[0203] The target crushing height CT then makes it possible to obtain, after crushing 116, a maximum diameter of the rivet button 20 between the authorized lower limit Bmin and the authorized upper limit Bmax.

[0204] More precisely, the maximum diameter of the rivet button BT, after crushing 116, associated with the target crushing height CT determined above verifies, in agreement with the model curve of the equation Math 1:

[0205] [Math.3] bt - “y (CA~CB)a+CB

[0206] Preferably, the target crushing height CT is determined as a function of the evolution curve according to at least three cases.

[0207] In the case ([Fig.7]) where the height associated with the point of intersection between the evolution curve and the Bmin terminal is between the Cmin, Cmax terminals and the height associated with the point of intersection between the evolution curve and the Bmax terminal is less than or equal to the Cmin terminal, then the target height CT can be determined, in accordance with the model curve of the Math 1 equation, according to the relation:

[0208] [Math.4] c L[(d+g)2-d2]a / \ V--- JL n * ■? n » V—wire I wire J- CZ 1 Bmin£ Bmin~ \ j

[0209] Furthermore, in the case ([Fig.8]) where the height associated with the point of intersection between the evolution curve and the Bmin terminal is between the Cmin, Cmax terminals and the height associated with the point of intersection between the evolution curve and the Bmax terminal is also between the Cmin, Cmax terminals, then the target height CT can be determined, in accordance with the model curve of the Math 1 equation, according to the relation:

[0210] [Math.5] CT= (d+gy(-^ + T^) A -L[(d + gŸ^

[0211] Furthermore, in the case ([Fig.9]) where the height associated with the point of intersection between the evolution curve and the Bmin terminal is greater than or equal to the Cmax terminal and the height associated with the point of intersection between the evolution curve and the Bmax terminal is also between the Cmin, Cmax terminals, then the target height CT can be determined, in accordance with the model curve of equation 1 above, according to the relation:

[0212] [Math.6] c L[(d+g)2-d^ ~ Bmax2 “ Bmax

[0213] Following step 114 of determining the target crushing height CT, the riveting 104 of the method 100 comprises step 116 of crushing the rivet 8, illustrated in [Fig.6].

[0214] Step 116 of crushing the rivet 8 is implemented until the rivet button 20 has the target crushing height CT determined in step 114.

[0215] Once the target crush height CT is reached, the crushing is stopped.

[0216] The crushing step 116 is for example implemented by the riveting system 26 of assembly station 22.

[0217] The riveting system 26, and in particular the control system 50, is then in particular controlled by the processing unit 30 to implement the crushing step 116.

[0218] During the crushing step 116, the inserted rivet 8 is crushed between the counter 46 and the hammer 48 to form the rivet button 20. The maximum diameter of the rivet button 20 is greater than the diameter of the through hole 36.

[0219] To do this, for example, the hammer 48 is moved and positioned on the side of the head 16 of the inserted rivet 8 and the counter 46 is moved and positioned on the side of the barrel 18 protruding from the inserted rivet 8.

[0220] Alternatively, the machining steps 108 and / or insertion steps 110 are implemented manually, the assembly station 22 is then devoid of the machining device 32 and / or the insertion device 34.

[0221] Alternatively, any other method for determining the target crushing height CT could be implemented provided that said target height CT is determined at least as a function of the acquired exceeding barrel height A.

[0222] Indeed, the inventors have surprisingly shown that it is the determining parameter of the height of the barrel exceeding A before crushing of the inserted rivet 8 which determines the trajectory corresponding to the evolution of the diameter B as the crushing C of the rivet 8 progresses.

[0223] Furthermore, this protruding barrel height must be acquired to the extent that it is not totally controlled, this height depending in particular on the manufacturing tolerance of the rivet 8 itself, the tolerance of the thickness to be assembled of the positioned assembly 44, and the tolerance on the countersink depth.

[0224] The invention makes it possible to remedy the problems identified by individualizing the target crushing height as a function of the acquired protruding barrel height A, in particular to recenter it in a restricted tolerance zone 66. Thus, for the same rivet reference 8, the determined target crushing height is different for different acquired protruding barrel heights.

[0225] Thanks to the characteristics previously described, it is possible to considerably improve the reliability of riveting to achieve compliance rates close to 100%. Method 100 of the invention thus reduces the costs and time required for riveting assembly.

Claims

Claims

1. Method of assembling (100) a part (2), the part (2) comprising at least one stiffener (6) and one panel (4), the method (100) comprising riveting (104) the stiffener (6) and the panel (4), the riveting (104) comprising the following steps: - positioning (106) of the stiffener (6) and the panel (4), the positioned assembly (44) of the stiffener (6) and the panel (4) delimiting a through hole (36), - insertion (110) of a rivet (8) into the through hole (36), the rivet (8) comprising a head (16) and a shank (18), - crushing (116) of the rivet (8) to form a rivet button (20) opposite said head (16) relative to said positioned assembly (44), characterized in that the riveting (104) comprises, before the crushing step (116), the following steps: - acquisition (112) of a height of barrel exceeding (A) of said positioned assembly (44), - determination (114) of a target crushing height (CT) so that a maximum diameter of the rivet button (20), after crushing (116), is between an authorized lower limit (Bmin) and an authorized upper limit (Bmax), the target crushing height (CT) being determined as a function of at least one determining parameter comprising the acquired protruding barrel height (A); the determination step (114) comprising: * a sub-step (117A) of acquiring said authorized lower and upper limits (Bmin, Bmax) of maximum diameter of the rivet button (20), after crushing (116), * a sub-step (117B) of acquiring authorized lower and upper limits (Cmin, Cmax) of maximum height of the rivet button (20), after crushing (116), * a sub-step (118) of acquiring an evolution curve, associated with the acquired protruding barrel height (A), linking the evolution of the rivet height (C) to the evolution of the rivet diameter (B) during crushing (116), * a sub-step (120) of determining a maximum conforming height (CA) from the evolution curve and a sub-step (122) of determining a minimum conforming height (CB) from the evolution curve, to obtain, after crushing (116), a diameter maximum of the rivet button (20) between the lower authorized diameter limit (Bmin) and the upper authorized diameter limit (Bmax), * the target crushing height (CT) being determined to be between the maximum compliant height (CA) and the minimum compliant height (CB); and in that the crushing step (116) of the rivet (8) is implemented until the rivet button (20) has the determined target crushing height (CT).

2. An assembly method (100) according to claim 1, wherein the crushing step (116) is implemented by a riveting system (26) comprising at least one counterpiece (46) and a hammer (48), the inserted rivet (8) being crushed between the counterpiece (46) and the hammer (48) during the crushing (116), the riveting system (26) being controlled by a processing unit (30) to implement the crushing step (116), the determining step (114) being implemented by the processing unit (30).

3. An assembly method (100) according to claim 2, wherein the riveting system (26) comprises at least one robot arm carrying one of the counterpiece (46) and the hammer (48), preferably at least two robot arms (52A, 52B) carrying the counterpiece (46) and the hammer (48) respectively.

4. An assembly method (100) according to any one of the preceding claims, wherein the rivet (8) extends along a longitudinal axis (X) from the head (16) to an opposite end (62), the positioned assembly (44) of the stiffener (6) and the panel (4) defining a distal face (64) through which the shank (18) of the rivet (8) protrudes, the height of the protruding shank corresponding to the height between the distal face (64) and said opposite end (62) of the rivet (8).

5. Assembly method (100) according to any one of the preceding claims, in which the determination of the target crushing height (CT) is such that, for the same rivet (8), the target crushing height (CT) determined is different for different acquired protruding barrel heights.

6. An assembly method (100) according to any preceding claim, wherein the determining parameters according to which the target crushing height (CT) is determined further comprise a diameter of the shank (18) of the inserted rivet (8) and / or a parameter representative of a swelling of the rivet (8) in the through hole (36) during crushing (116).

7. An assembly method (100) according to any one of the preceding claims, wherein the sub-step (120) of determining the maximum compliant height (CA) comprises determining the point of intersection between the evolution curve and the lower authorized diameter limit (Bmin), and: * if the height associated with the point of intersection is between the lower and upper authorized height limits (Cmin, Cmax), then the maximum compliant height (CA) is determined as being said intersection height, and * if the height associated with the point of intersection is greater than or equal to the upper authorized height limit (Cmax), then the maximum compliant height (CA) is determined as being said upper authorized height limit (Cmax), and / or,wherein the sub-step (122) of determining the minimum compliant height (CB) comprises determining the point of intersection between the evolution curve and the authorized upper diameter limit (Bmax). * if the height associated with the point of intersection is between the authorized lower and upper height limits (Cmin, Cmax), then the minimum compliant height (CB) is determined as being said intersection height, and * if the height associated with the point of intersection is less than or equal to the authorized lower height limit (Cmin), then the minimum compliant height (CB) is determined as being said authorized lower height limit (Cmin),

8. An assembly method (100) according to claim 7, wherein the target crush height (CT) is determined according to a linear relationship depending on the maximum conformal height (CA) and the minimum conformal height (CB).

9. An assembly method (100) according to claim 8, wherein the determining parameters according to which the target crushing height (CT) is determined also comprise a safety coefficient a, such that the target crushing height (CT) depends on the relationship (CA - CB)a + CB, the safety coefficient being less than A 1 H

10. d 1,V. Assembly method (100) according to claim 9, wherein the safety coefficient is strictly greater than 0.

5.

11. Assembly method (100) according to any one of the preceding claims, in which the sub-step (118) of acquiring the evolution curve comprises querying a database of abacus curves and retrieving the abacus curve associated with the acquired exceeding barrel height (A) from among said curves of the database.

12. An assembly method (100) according to any preceding claim, wherein the lower permissible diameter limit (Bmin) and the upper permissible diameter limit (Bmax) respectively depend on the diameter of the shank (18) of the inserted rivet (8).

13. Assembly station (22) for a part (2), the part (2) comprising at least one stiffener (6) and one panel (4), the assembly station (22) comprising: - a positioning system (24) for the stiffener (6) and the panel (4), - a riveting system (26) suitable for implementing the crushing (116) of an inserted rivet (8) in a through-hole (36) delimited in the positioned assembly (44) of the stiffener (6) and the panel (4), the rivet (8) comprising a head (16) and a shank (18), the crushing (116) being implemented to form a rivet button (20) opposite said head (16) relative to said positioned assembly (44), characterized in that the assembly station (22) also comprises: - a system (28) for acquiring a shank height exceeding (A) by the positioned assembly (44), and, - a processing unit (30) configured to determine a target crushing height (CT) so that a maximum diameter of the rivet button (20), after crushing (116),is between an authorized lower limit (Bmin) and an authorized upper limit (Bmax), the target crushing height (CT) being determined as a function of at least one determining parameter comprising the acquired protruding barrel height (A) by the acquisition system (28); the determination of the target crushing height (CT) by the processing unit (30) comprising: * a sub-step (117A) of acquiring said authorized lower and upper limits (Bmin, Bmax) of maximum diameter of the rivet button (20), after crushing (116), * a sub-step (117B) of acquiring authorized lower and upper limits (Cmin, Cmax) of maximum height of the rivet button (20), after crushing (116), * a sub-step (118) of acquiring an evolution curve, associated with the acquired protruding barrel height (A), linking the evolution of the rivet height (C) to the evolution of the rivet diameter (B) during crushing (116), * a sub-step (120) of determining a maximum conforming height (CA) from the evolution curve and a sub-step (122) of determining a minimum conforming height (CB) from the evolution curve, to obtain, after crushing (116), a maximum diameter of the rivet button (20) between the lower authorized diameter limit (Bmin) and the upper authorized diameter limit (Bmax), * the target crush height (CT) being determined to be between the maximum compliant height (CA) and the minimum compliant height (CB); the processing unit (30) being configured to control the riveting system (26) to implement the crushing (116) until the rivet button (20) has the determined crushing target height (CT).

Images