Braiding machine with a reserve region

Abstract

The invention relates to a braiding machine comprising: - a plurality of yarn feed spindles (30) movable along a guide path (100) so as to participate in the braiding, - a reserve zone (20) capable of receiving at least one spindle (30) so as to interrupt its participation in the braiding.

Description

Technical Field

[0001] The present invention relates to braiding machines enabling the production of braided structures, and more particularly braided tubular structures exhibiting large variations in cross-section. Previous technique

[0002] A braiding machine typically comprises a table with intersecting tracks, called guideways, along which yarn feed spindles, connected to a machine draw point, are moved. These yarn feed spindles thus intersect regularly to form a braid. Generally, the braid formation can be carried out on a form, called a forming mandrel, which moves during the braid formation process: this is known as "overbraiding." The movement of the spindles along the guideways is typically achieved by means of rotating notched wheels, preferably arranged in one or more concentric circles. Such braiding machines are described, for example, in documents FR 2 804 133 and US 8 347 772.

[0003] When attempting to manufacture a braided structure with significant variations in cross-section using a prior art machine, the resulting braided structure does not exhibit uniform weaving. Indeed, in areas of the braid with a large cross-section, the yarn density is lower or even insufficient, or the angles between the braided yarns are greater, compared to areas of the braid with a smaller cross-section.

[0004] Documents WO 2015 / 117148 A1 and EP 3 502 332 A1 disclose braiding machines. Document US 2 354 212 A discloses a machine for braiding tubular parts. Document JP H07 18548 A discloses a device for replacing an empty spool of thread with a full one. Description of the invention

[0005] The present invention aims to overcome the aforementioned drawbacks by providing a braiding machine capable of producing a uniform braided structure despite significant variations in cross-section. To this end, according to a first aspect of the invention, the invention provides a braiding machine comprising: a plurality of yarn feed spindles connected to guide supports and movable along a guide path so as to participate in braiding, all or part of the spindles being attached to a positioning element cooperating with a corresponding guide support and removable relative to the latter, a plurality of reserve supports located outside the guide path, said reserve supports being able to receive yarn feed spindles put in reserve so as to interrupt their participation in braiding, the positioning elements being able to cooperate with the reserve supports to carry out this putting in reserve.

[0006] Thus, the use of spindles capable of cooperating with mobile guide supports along the guide path makes it possible to easily remove or add spindles to the braiding, without requiring complex operations such as dismantling the braiding machine table.

[0007] This cooperative system between the positioning elements and the guide supports allows for easy variation in the number of yarn feed spindles involved in braiding the structure. Thus, the number of spindles involved in braiding can be adapted to the cross-section of the structure being braided in order to obtain a constant yarn density and consistent angle values ​​between the yarns despite variations in cross-section.

[0008] Thus, when the cross-section of the braided structure needs to be reduced, spindles are removed from the guide path to interrupt their role in the braiding process. This is achieved by separating the positioning elements of these spindles from the guide supports. Consequently, the number of braided wires is reduced, preventing a significant increase in wire density or an undesired decrease in the angles between the braided wires in the area of ​​smallest cross-section. Conversely, when the cross-section of the braided structure needs to be increased, spindles are added to the main guide path by mounting the positioning elements of these spindles with the guide supports already present on the path. Consequently, the number of braided wires is increased, preventing a significant decrease in wire density or an undesired increase in the angles between the braided wires in the area of ​​smallest cross-section.The braiding structure therefore remains identical and uniform across the entire braided structure thus obtained.

[0009] The use of spare supports makes it easy to store spindles in a reserve area, in particular spindles that have been removed from the guide path in order to interrupt their participation in braiding, and / or spindles that are intended to be added to the guide path to participate in braiding.

[0010] According to a particular embodiment of the invention, the machine includes a drive system for the reserve supports capable of driving at least a part of the reserve supports circumferentially around the guide path.

[0011] The spare supports go around the outer edge of the guide path, or around the inner edge of the guide path.

[0012] Using a reserve zone that includes at least one part rotating circumferentially around the guide path helps limit the occurrence of singularities in the braiding. Indeed, when a spindle is removed from the guide path to interrupt the braiding of the yarn from that spindle, the yarn from that spindle is still in the process of being intertwined. When the yarn is being intertwined, it is neither braided and tightened with the other yarns, nor is it free. There is therefore a transition stage in which the yarn is no longer participating in the braiding, but is still being intertwined, so that part of the yarn is completely braided and tightened with the other yarns, part of the yarn is being intertwined, and part of the yarn is free.This transition stage ends when the part of the yarn that was being intertwined is completely braided and tightened with the other yarns, that is to say that the yarn now only comprises a completely braided and tightened part, and a free part that is not braided and not intertwined.

[0013] If the spindle removed from the guide path is positioned directly on a fixed reserve support relative to the moving guide supports, the yarn emerging from that spindle is abruptly stopped while it may still be intertwining. This can lead to unwanted tension in the yarns or irregularities in the braiding. To support the yarn during the transition phase—that is, while it is still intertwining but no longer participating in the braiding process—the spindle from which the yarn emerged can be positioned on a moving reserve support. This moving reserve support allows the spindle's movement to continue in a clockwise or counterclockwise direction until at least the end of the transition phase. Once the transition phase is complete, the movement of the moving reserve support can be stopped, the spindle can be moved to a fixed part of the reserve area, and / or the yarn emerging from that spindle can be cut.

[0014] According to another particular embodiment of the invention, the spare support drive system comprises at least a first circumferential ring to the guide path and capable of rotating in a first direction of rotation and at least a second circumferential ring to the guide path and capable of rotating in a second direction of rotation opposite to the first direction of rotation, each first or second ring carrying one or more spare supports.

[0015] The first and second rings surround the outer edge of the guide path, or go around the inner edge of the guide path.

[0016] Thus, it is possible to simultaneously accompany in their transition stage threads from spindles that were rotating clockwise on the guide path and threads from spindles that were rotating counterclockwise.

[0017] According to another particular embodiment of the invention, the reserve supports are present around the guide path.

[0018] By placing the reserve area, and any circumferential reserve rings, on the periphery of the guidance path, access to the corridors present in the reserve area is facilitated.

[0019] According to another particular embodiment of the invention, the machine further comprises a shaping mandrel on which the braiding is intended to be carried out.

[0020] The presence of a shaping mandrel makes it easier to braid the structure, the shape of the shaping mandrel providing support on and around which the wires can be braided with the desired cross-section.

[0021] According to another particular embodiment of the invention, the machine comprises an overall drive system including the drive system for the reserve supports and a drive system for the guide supports, the overall drive system being configured such that the angular velocity of at least a part of the reserve supports is a function of the angular velocity of at least a part of the guide supports so that the movement of at least a part of the reserve supports accompanies the movement of at least a part of the guide supports.

[0022] According to another particular embodiment of the invention, the overall drive system includes a transmission system configured to transmit the motion from a drive system of the guide supports to the drive system of the reserve supports.

[0023] Preferably, the drive system for the reserve supports is a rack and pinion system. Preferably, the drive system for the guide supports is a system of slotted wheels rotated by a gear train. Preferably, the transmission system is a belt system connecting the gear train of the guide support drive system to the rack and pinion system of the reserve support drive system. This overall drive system has the advantage of being robust and allowing for high braiding speeds.

[0024] According to another particular embodiment of the invention, the machine further comprises a robotic arm configured to move at least one spindle between a guide support and a reserve support.

[0025] According to another particular embodiment of the invention, the machine further comprises a cutting device configured to cut a wire from a feed spindle whose positioning element cooperates with a reserve support.

[0026] The invention also relates to a method for braiding a braided structure comprising a first zone having a first cross-section and a second zone having a second cross-section different from the first cross-section, the method implementing a machine according to the first aspect of the invention and comprising: the braiding of the first zone of the braided structure with a first number of movable wire feed spindles along the guide path, and the braiding of the second zone of the braided structure with a second number of movable wire feed spindles along the guide path, the second number of spindles being different from the first number of spindles by means of the movement of spindles between the guide supports and the reserve supports by cooperation of the positioning element of said moved spindles with the guide or reserve supports.

[0027] The invention also proposes, according to a second aspect of the invention, a braiding machine comprising: a plurality of movable yarn feed spindles along a main guide path so as to participate in the braiding, characterized in that it further comprises: a reserve zone adjacent to the main guidance path and comprising at least one secondary guidance path capable of receiving at least one corridor and keeping it in the reserve zone so as to interrupt its participation in the braiding, each secondary guidance path being associated with at least one switch element which is movable between a first position preventing communication between the main guidance path and the secondary guidance path, and a second position permitting this communication and configured to allow passage of at least one corridor between the main guidance path and the secondary guidance path.

[0028] The reserve area can be located on the outer edge of the main guideway, or on the inner edge of the main guideway. For example, the reserve area could surround the outer edge of the main guideway, or extend around its inner edge.

[0029] The presence of the reserve zone allows for variation in the number of yarn feed spindles involved in the braiding of the structure. Thus, the number of spindles involved in the braiding can be adapted to the cross-section of the structure being braided in order to obtain a constant yarn density and angle values ​​between the yarns despite variations in cross-section.

[0030] Thus, when the cross-section of the braided structure needs to be reduced, spindles are removed from the main guide path to interrupt their participation in the braiding process. This reduces the number of braided threads, preventing a significant increase in thread density or an undesired decrease in the angles between the braided threads in the area of ​​smallest cross-section. Conversely, when the cross-section of the braided structure needs to be increased, spindles from the reserve area are moved to the main guide path. This increases the number of braided threads, preventing a significant decrease in thread density or an undesired increase in the angles between the braided threads in the area of ​​smallest cross-section. The braid weave therefore remains identical and uniform throughout the entire resulting braided structure.

[0031] According to a particular embodiment of the invention, the machine further comprises a shaping mandrel on which the braiding is intended to be carried out.

[0032] The presence of a shaping mandrel makes it easier to braid the structure, the shape of the shaping mandrel providing support on and around which the wires can be braided with the desired cross-section.

[0033] According to another particular embodiment of the invention, the reserve zone is formed by a plurality of reserve regions distributed along the main guidance path, each reserve region comprising a secondary guidance path separate from the secondary guidance paths of the other reserve regions.

[0034] According to another particular embodiment of the invention, the machine comprises a plurality of main slotted wheels configured to be driven in rotation in order to circulate the feed spindles along the main guide path, said machine further comprising one or more secondary slotted wheels in the reserve area, each secondary guide path in the reserve area being associated with at least one secondary slotted wheel configured to be driven in rotation in order to circulate at least one feed spindle along said secondary guide path.

[0035] According to another particular embodiment of the invention, the machine includes at least one rotation decoupling system configured to make the rotation of at least one secondary slotted wheel independent of the rotation of the main slotted wheels.

[0036] According to another particular embodiment of the invention, at least part of the switching elements is movable in translation to move from the first to the second position.

[0037] According to another particular embodiment of the invention, at least a part of the switching elements is rotationally movable to move from the first to the second position.

[0038] According to another particular embodiment of the invention, the machine further comprises a control unit configured to actuate the switching element.

[0039] According to another particular embodiment of the invention, the machine further comprises a cutting device configured to cut a wire from a feed spindle present in the reserve area.

[0040] The invention also relates to a method for braiding a braided structure comprising a first zone having a first cross-section and a second zone having a second cross-section different from the first cross-section, the method implementing a machine according to the second aspect of the invention and comprising: the braiding of the first zone of the braided structure with a first number of movable wire feed spindles along the main guide path, and the braiding of the second zone of the braided structure with a second number of movable wire feed spindles along the main guide path, the second number of spindles being different from the first number of spindles by means of the passage of spindles between the main guide path and the reserve zone by actuation of the switching element. Brief description of the drawings

[0041] [ Fig. 1 ] There figure 1is a three-dimensional view of a braiding machine according to the first aspect of the invention. Fig. 2 ] There figure 2 is a top-view detail of the braiding machine figure 1 . [ Fig. 3 ] There figure 3 is a schematic exploded view of a spindle cooperating with a guide support. Fig. 4 ] There figure 4 is a schematic view of the operating mechanisms of the braiding machine figures 1 and 2 . [ Fig. 5 ] There figure 5 is a schematic view of the machine figures 1 and 2 during the braiding of a section of thick braid. Fig. 6 ] There figure 6 is a schematic view of the machine figures 1 and 2 during the braiding of a section of braid with a progressively increasing cross-section. Fig. 7 ] There figure 7 is a schematic view of the machine figures 1 and 2 during the braiding of a section of thin braid. Fig. 8 ] There figure 8is a schematic view of a braiding machine according to the second aspect of the invention during the braiding of a section of thick braid. Fig. 9 ] There figure 9 is a schematic view of the braiding machine of the figure 8 during the braiding of a section of braid with a small cross-section. Fig. 10 ] There Figure 10 is a schematic view of a portion of the braiding machine's platform figures 8 and 9 including notched wheels. Fig. 11 ] There figure 11 is a schematic view of a movable switching element in translation in its second position according to a first embodiment. Fig. 12 ] There figure 12 is a schematic view of a movable switching element in translation in its first position according to a second embodiment. Fig. 13A ] There figure 13A is a schematic view of a movable switch element in translation in its second position according to a third embodiment. Fig. 13B ] There figure 13B is a schematic view of a switch element of the figure 13A in its first position. Fig. 14 ] There figure 14 is a schematic view of a rotating movable switch element according to a fourth embodiment. Fig. 15 ] There figure 15 is a schematic view of a rotating movable switch element according to a fifth embodiment. Fig. 16 ] There figure 16 is a schematic view of a rotating movable switch element according to a sixth embodiment. Description of the implementation methods

[0042] A first aspect of the invention is presented in relation to the figures 1 to 7 .

[0043] THE figures 1 and 2 schematically illustrate an example of a braiding machine according to the first aspect of the invention allowing the creation of a braided structure.

[0044] The braiding machine comprises a plate 1 and a plurality of yarn feed spindles 30. The plate 1 is preferably horizontal, in order to facilitate its maintenance and that of the yarn feed spindles 30. However, it is not outside the scope of the invention if the plate 1 is vertical or inclined.

[0045] The plate 1 includes a braiding zone 10. The braiding zone 10 includes a guide path 100 and a plurality of guide supports 51 adapted to cooperate with said guide path 100, and consequently adapted to move along the guide path 100. Preferably, the guide path 100 is machined in the solid of the plate 1 in the form of grooves, having for example a substantially rectangular cross-section, open outwards, and within which the guide supports 51 move.

[0046] Each guide support 51 comprises a guide face 51a and a mounting face 51b opposite the guide face 51a. The guide face 51a is adapted to cooperate with the guide path 100. In particular, the guide face 51a of the guide support 51 comprises a projecting relief configured to move within the groove of the guide path 100. Preferably, all guide supports 51 present in the braiding zone 10 are identical.

[0047] Preferably, the braiding machine includes a mandrel with a specific shape 5, which is a form on which the intertwined yarns rest to form the tight braid. In this case, the braiding machine allows for processes known as "over-braiding." The braiding machine according to the invention is particularly advantageous when it is desired to produce a braid with significant variations in cross-section, and more specifically, a braid whose perimeter varies considerably. Unless otherwise specified, the cross-sections are taken perpendicular to a longitudinal axis of the braided structure. Consequently, the advantages offered by the braiding machine according to the invention are particularly noticeable when said braiding machine includes a mandrel with a specific shape 5 whose form exhibits significant variations in thickness.

[0048] The braiding machine further includes at least one drawing point located at a distance from the plate 1, to which are connected the wires from the feed spindles 30 movable along the guide path 100.

[0049] The braiding machine also includes a reserve zone 20 circumferential to the braiding zone 10, which comprises a plurality of reserve supports 52. In the example illustrated on the figures 1 and 2 The reserve zone 20 is located around the outer edge of the braiding zone 10, allowing easy access to said reserve zone 20. However, it does not depart from the scope of the invention if the reserve zone 20 goes around the inner edge of the braiding zone 10. Preferably, the reserve zone 20 is located in the same plane as the braiding zone 10. Preferably, the reserve zone 20 is adjacent to the guide path 100.

[0050] The reserve area 20 is presented here in the form of several circumferential and concentric rings 21, 22, 23. Each ring 21, 22, 23 includes at least one reserve support 52. Each reserve support 52 includes a mounting face 52b. Preferably, all the reserve supports 52 present in the reserve area 20 are identical.

[0051] As illustrated on the figure 3Each wire feed spindle 30 includes a retaining portion 34 for holding a wire spool, extended by a positioning element 35. The positioning element 35 is integral with the spindle 30. The positioning element 35 is configured to cooperate with the guide supports 51 and with the spare supports 52. In particular, the positioning element 35 includes a mounting face 35b opposite the retaining portion 34, which is configured to cooperate with the mounting face 51b of the guide supports 51 and with the mounting face 52b of the spare supports 52.

[0052] In particular, the mounting face 35b of the positioning element 35 may include a groove, and the mounting faces 51b and 52b of the guide supports 51 and reserve 52 may include a protruding relief, the groove of the mounting face 35b of the positioning element 35 being configured to cooperate with the protruding relief of the mounting faces 51b and 52b of the guide supports 51 and 52. The reverse is also possible.

[0053] Thus, each spindle 30 can be mounted on a guide support 51, by making the mounting face 35b of said spindle 30 cooperate with the mounting face 51b of said guide support 51, and can be mounted on a spare support 52, by making the mounting face 35b of said spindle 30 cooperate with the mounting face 52b of said spare support 52. Preferably, all spindles 30 can be mounted on all guide supports 51 and on all spare supports 52. Preferably, the mounting faces 51b of the guide supports 51 and the mounting faces 52b of the spare supports 52 are identical.

[0054] The spindles 30 mounted on the guide supports 51 in the braiding zone 10 can participate in the braiding, that is to say that the wire or wires coming from the spools of said spindles 30 mounted on the guide supports 51 can be braided.

[0055] Thus, the spindles 30 mounted on the guide supports 51 are mobile along the guide path 100.

[0056] The guide path 100 is configured to be traversed in a first direction of rotation, for example clockwise, by a first plurality of zones 30 and in a second direction of rotation, for example counterclockwise, by a second plurality of zones 30 in order to perform the braiding. Thus, a first plurality of guide supports 51 is configured to be movable at least clockwise and a second plurality of guide supports 51 is configured to be movable at least counterclockwise.

[0057] In the example illustrated on the figures 1 and 2The guide path 100 comprises two regularly intersecting guide sub-paths 110 and 120, the first guide sub-path 110 being configured to be traversed by the first plurality of guide supports 51 on which the first plurality of spindles 30 are mounted, and the second sub-path 120 being configured to be traversed by the second plurality of guide supports 51 on which the second plurality of spindles 30 are mounted. Of course, the invention remains within the scope of the invention if the guide path comprises more than two sub-paths, for example, if it is desired to create a braided structure comprising several layers or having a complex weave, such as an interlock braid.

[0058] The braiding machine according to the invention includes, in a well-known manner, a drive system for the guide supports 51. Preferably and in a well-known manner, the braiding zone 10 of the plate 1 comprises a plurality of slotted wheels 11 configured to be driven in rotation in order to circulate the yarn feed spindles 30 along the guide path 100, as illustrated in the figures 1 and 2 Each slotted wheel 11 preferably comprises four slots. The slotted wheels 11 are preferably driven in rotation in a well-known manner by means of gear trains controlled by one or more motors, the gear trains being preferably located on the face of the plate 1 opposite the face having the guide track 100 and the slotted wheels 11. For example, the reserve area 20 does not include slotted wheels, and the reserve supports 52 are not driven by slotted wheels.

[0059] The braiding machine according to the invention preferably comprises a drive system for the reserve supports 52, capable of driving at least a portion of the reserve supports 52 circumferentially around the guide path 100. In the example illustrated on the figures 1 to 4 The rotation drive system for the reserve supports 20 includes at least one circumferential ring 21, 22 that is rotationally movable around the braiding zone 10, i.e., rotationally movable along the inner or outer edge of the guide path 100. The reserve zone 20 also preferably includes at least one fixed circumferential ring 23.

[0060] Preferably, the reserve zone 20 includes at least a first circumferential ring 21 movable in a first direction of rotation, for example movable in the clockwise direction, and at least a second circumferential ring 22 movable in a second direction of rotation opposite to the first direction of rotation, for example movable in the counterclockwise direction.

[0061] The first circumferential rings 21, which rotate clockwise, can accompany the movement of the first plurality of guide supports 51, which rotate clockwise along the guide path 100, and consequently the movement of the first plurality of spindles 30 mounted on the first plurality of guide supports 51 and therefore also rotating clockwise. Therefore, if it is desired to remove a spindle 30 from the braid and place it in the reserve area 20, for example, to create a portion of the braided structure with a smaller cross-section, but without risking that the yarn from said spindle 30 might create a singularity in the braid or unwanted tension, it is possible to place said spindle 30 on the first clockwise rotating ring 21 by having the positioning element 35 of said spindle 30 cooperate with a reserve support 52 present on the first ring 21.Thus, the thread from said spindle 30 will remain mobile in a clockwise direction in order to accompany the end of its braiding to the braided structure being made, even if spindle 30 has been removed from the braiding area and no longer participates in the braiding.

[0062] Similarly, the second circumferential ring(s) 22 movable in the counterclockwise direction can accompany the movement of the second plurality of guide supports 51 movable on the guide path 100 in the counterclockwise direction, and consequently the movement of the second plurality of zones 30 mounted on the second plurality of guide supports 51 and therefore movable in the counterclockwise direction.Therefore, if it is desired to remove a movable spindle 30 from the braid in the counterclockwise direction to place it in the reserve area 20, for example to create a portion of the braided structure with a smaller cross-section, but without risking that the yarn from said movable spindle 30 might create a singularity in the braid or an unwanted tension, it is possible to place said spindle 30 on the second ring 22 movable in the counterclockwise direction by making the positioning element 35 of said spindle 30 cooperate with a reserve support 52 present on the second ring 22. Thus, the yarn from said spindle 30 will remain movable in the counterclockwise direction in order to accompany the end of its braiding to the braided structure being created, even if the spindle 30 has been removed from the braiding area and no longer participates in the braiding.

[0063] Preferably, the movable circumferential rings 21 and 22 are intended to temporarily hold the bobbins 30 for a short period before said bobbins 30 are placed on the fixed ring(s) 23 for a longer period. The movable circumferential rings 21 and 22 then correspond to a transition zone between the braiding zone 10 and the fixed parts of the reserve zone 20. Preferably, the placement of a bobbin 30 on one of the movable rings 21, 22 is therefore only temporary, for a period preferably corresponding to the time required for the yarn from said bobbin, which is being intertwined with the other yarns when said bobbin is removed from the braiding zone, to be fully braided into the braided structure to be produced. This significantly reduces the risk of anomalies in the final braided structure.

[0064] As illustrated in the example of the figure 4, the machine according to the invention preferably includes an overall drive system which includes on the one hand the drive system 71 of the guide supports 51 and on the other hand the drive system 73, 74, 76, 21, 22 of the reserve supports 52.

[0065] In the example illustrated on the figures 1 to 4 The rotational drive system for the movable rings 21 and 22, which belongs to the drive system for the reserve supports 52, can be mechanically linked to the rotational drive system for the slotted wheels 11, which belongs to the drive system for the guide supports 51. For example, as illustrated in the figure 4The rotational drive system 71 for each slotted wheel 11, preferably in the form of gears, is connected by a belt 72 to a pinion 73 belonging to the reserve area 20. The movable rings 21, 22 each comprise a circumferential rack 74, 76 actuated directly or indirectly by the pinion 73. Thus, in the example illustrated on the figure 4 , the movement of the drive system 71 of the guide supports 51 is transmitted to the drive system 21, 22, 73, 74, 76 of the reserve supports 52 by means of a motion transmission system in the form of a belt 72.

[0066] Preferably, in order to further limit the risk of singularity in the braiding following a change in the number of spindles 30 participating in the braiding, the overall drive system is configured so that the angular velocity of at least a portion of the reserve supports 52 is a function of the angular velocity of at least a portion of the guide supports 51, so that the movement of at least a portion of the reserve supports 52 accompanies the movement of at least a portion of the guide supports 51. Preferably, the angular velocity of at least a portion of the reserve supports 52 is equal to the angular velocity of at least a portion of the guide supports 51, that is to say, at least a portion of the reserve supports 52 travels the same angular range with respect to the central axis of the machine as at least a portion of the guide supports for a given time.The machine's central axis can be defined, for example, as the axis passing through the draw point or the center of the machine's forming mandrel, and through the center of the main guide path. Angular velocity is expressed in radians per second and angular range in radians, with the reference center being a point on the central axis of the braiding machine.

[0067] Thus, at least part of the guide supports makes a complete turn along the guide path 100 when at least part of the guide supports 51 makes a complete turn of the guide path 100.

[0068] In the example illustrated on the figures 1 to 4The movable rings 21, 22 complete a full rotation around the guide track 100 when at least some of the spindles 30 complete a full rotation of the guide track 100. Thus, the spindles 30 on the first clockwise movable ring 21 follow the movement of the clockwise movable spindles 30 on the guide track 100, and the spindles 30 on the second counterclockwise movable ring 22 follow the movement of the counterclockwise movable spindles 30 on the guide track 100. The reduction ratio between the rotation of the slotted wheels 11 and the rotation of each circumferential ring 21, 22 should therefore preferably correspond to half the number of slotted wheels 11 per circumferential row. In the example illustrated on the figure 1The braiding machine comprises a single row of slotted wheels 11 comprising sixteen slotted wheels 11. Thus, the value of the reduction ratio between the rotation of each gear 71 of said slotted wheels 11 and the rotation of the rack 74, 76 of each movable ring 21, 22 will be eight.

[0069] The transfer of the spindles 30 between the braiding zone 10 and the reserve zone 20, or between the different parts or circumferential rings 21, 22, 23 of the reserve zone 20, can be carried out manually or by one or more robotic arms 8 comprising a gripping and ungripping gripper. These robotic arms 8 are, for example, fixed around the braiding zone 10 and the reserve zone 20.

[0070] The braiding machine may also include a cutting system 9 configured to cut the yarns from the spindles 30 arranged in the reserve area 20, and in particular the yarns from the spindles 30 arranged in the fixed parts of the reserve area 20, in order to avoid any risk of entanglement of one of the yarns not participating in the braiding with the yarns participating in the braiding.

[0071] We will now describe, with reference to schematic figures 5 to 7, an example of a braiding process according to the first aspect of the invention for producing a braided structure 300 exhibiting significant variations in cross-section, and more specifically, substantial variations in the perimeter of the cross-section. Thus, the braided structure 300 to be produced comprises, along its length, a first zone with a first cross-section perimeter, a transition zone, and a second zone with a second cross-section perimeter, the second perimeter being different from the first perimeter. In the example illustrated in the figures 5 to 7 , the first perimeter is larger than the second perimeter and the transition zone has a section whose perimeter decreases regularly between the first zone and the second zone.

[0072] In the example illustrated on the figures 5 to 7The braiding is carried out on a mandrel with a specific shape 5, which generally has the shape of the braided structure 300 to be produced. Of course, the invention remains within the scope of the invention if the braiding is not carried out on a mandrel with this specific shape. The yarns from the reels of the yarn feed spindles are fixed to a drawing point.

[0073] We begin by creating the first zone of the braided structure 300 by passing a first number of yarn feed spindles 30 along the guide path 100, inside the braiding zone 10. Thus, the yarns 31 from the spools carried by this first number of spindles 30 intertwine around the shaping mandrel 5 so as to create the first zone of the braided structure 300, as illustrated in the figure 5 .

[0074] In order to create the transition zone of the braided structure 300, whose cross-sectional perimeter decreases while maintaining a wire density and wire angles similar to those of the first zone of the braided structure 300, wire feed spindles 30 are progressively moved from the braiding zone 10 to the reserve zone 20. These feed spindles 30 are thus removed from the guide path 100 either manually or automatically. Preferably, as illustrated in the figure 6, a robotic arm 8 as described above grasps a spindle 30 to be removed from the guide path 100 and separates it from the guide support 51 on which it was mounted by separating the positioning element 35 of said spindle 30 from the mounting surface 51b of the guide support 51. Then, the robotic arm 8 moves the spindle 30 to the reserve area 20, to mount it with one of the reserve supports 52 present in the reserve area 20 by assembling the positioning element 35 of said spindle 30 with the mounting face 52b of said reserve support 52.

[0075] In the example shown on the figure 6In order to create the transition zone and then the second zone of the braided structure 300, the robotic arms 8 progressively remove a part of the clockwise moving spindles 30 on the guide path 100 and a part of the counterclockwise moving spindles 30 on the guide path 100. The clockwise moving spindles 30 that are removed are then placed on the reserve supports 52 of the first clockwise moving ring 21 and the counterclockwise moving spindles 30 that are removed are then placed on the reserve supports 52 of the second counterclockwise moving ring 22.When some of the spindles 30 are placed on the movable rings 21 and 22, the yarns 32 emerging from said spindles 30 on the movable rings 21 and 22 no longer participate in the braiding but are in a transition stage; that is, they are still being intertwined with other yarns without yet being completely braided and tightened. The rotation of the movable rings 21 and 22 facilitates this transition stage for the yarns 32 emerging from the spindles 30 that have left the guide path 100 and the braiding zone 10.

[0076] When the yarn 32 from a spindle 30 placed on a movable ring 21 or 22 has completed the transition stage, i.e., it is no longer being intertwined, the spindle 30 can be removed from the movable ring 21 or 22 and placed on the fixed circumferential ring 23, either manually or automatically. Preferably, as illustrated in the figure 7The robotic arm 8 grasps a spindle 30 to be removed from a movable ring 21 or 22 and separates it from the reserve support 52 on which it was mounted by separating the positioning element 35 of said spindle 30 from the mounting surface 52b of the reserve support 52. Then, the robotic arm 8 moves the spindle 30 towards the fixed ring 23, to mount it with one of the reserve supports 52 present on said fixed ring 23 by assembling the positioning element 35 of said spindle 30 with the mounting face 52b of said reserve support 52 of the fixed ring 23. The yarns 33 from the spindles arranged on the fixed ring 23 can be cut by the cutting device 9, in order to avoid any risk of tangling of one of the yarns 33 not participating in the braiding with the yarns 31 participating in the braiding.

[0077] When the braiding of the transition zone of structure 300 is complete, only a second set of 30 movable spindles remains along the guide path 100, inside the braiding zone 10. In the example illustrated on the figures 5 to 7 , the second number of 30 mobile spindles is less than the first number of 30 mobile spindles when braiding the first zone.

[0078] The second set of spindles 30, moving along the guide path 100, then allows the second zone of the braided structure 300 to be braided, the yarns 31 from the spools carried by this second set of spindles 30 intertwining around the mandrel of the form 5 as illustrated in the figure 7 to create the braided structure 300.

[0079] In an unillustrated variant, a braided structure can be created, having along its length a first zone with a first cross-sectional perimeter, a transition zone, and a second zone with a second cross-sectional perimeter, as in the example illustrated on the figures 5 to 7 but further comprising a second transition zone and a third zone having a third section perimeter. The third perimeter of the third section is greater than the second perimeter of the second section, and may also be less than or greater than the first perimeter of the first section. Of course, the invention remains within the scope of the invention if the third section perimeter is less than the first and second section perimeters.

[0080] In this variant, the first zone, the transition zone, and the second zone are constructed as described previously. In order to create the second transition zone of the braided structure, located in the extension of the second zone and whose cross-sectional perimeter increases, while maintaining a yarn density and angles between yarns similar to the yarn density and angles between yarns of the first and second zones already braided, yarn supply spindles from the reserve zone are progressively transferred to the braiding zone to participate in the braiding process.

[0081] Thus, these feed spindles are removed from the fixed ring of the reserve area manually or automatically. Preferably, a robotic arm as described above grasps a spindle to be removed from the fixed ring and separates it from the reserve support on which it was mounted by separating the positioning element of said spindle from the mounting surface of the reserve support. Then, the robotic arm moves the spindle to one of the moving parts of the reserve area, to mount it with one of the reserve supports present on the first or second moving ring by assembling the positioning element of said spindle with the mounting face of said reserve support.In our example variant, in order to create the second transition zone and then the third zone of the braided structure, the robotic arms place part of the spindles present on the fixed ring onto the moving ring in a clockwise direction and part of the spindles present on the fixed ring onto the moving ring in a counterclockwise direction.

[0082] When the yarns from the spindles positioned on the moving rings follow the movement of the yarns being braided, the robotic arm(s) progressively move the spindles arranged on the moving ring clockwise along the sub-guides traversed by clockwise-moving guide supports, and the spindles arranged on the moving ring counterclockwise along the sub-guides traversed by counterclockwise-moving guide supports. This is achieved by mounting the spindle positioning element with the mounting faces of the guide supports that do not carry spindles. Thus, the yarns from the spindles mounted on the guide supports participate in the braiding process.

[0083] The prior passage of the yarn feed spindles over moving parts of the reserve area before their participation in braiding makes it easier to introduce into the braiding of the yarns from said added spindles.

[0084] When the braiding of the second transition zone of the structure is complete, there is therefore a third number of spindles, greater than the second number of spindles, mobile along the guide path, inside the braiding zone.

[0085] The third number of moving spindles on the guide path then allows the third zone of the braided structure to be braided, the threads from the spools carried by this third number of spindles intertwining around the shaping mandrel.

[0086] The term "yarn" used in this application may refer to a single yarn or single fiber, but may also refer to a strand or braid.

[0087] In particular, the fibers can be carbon fibers, ceramic fibers, or a mixture of carbon and ceramic fibers. The braided structure according to the process of the invention can be a fibrous structure, which may optionally be consolidated or densified by a matrix to form the fibrous reinforcement of a composite material part. The braided structure according to the process of the invention can thus form, for example, all or part of the fibrous reinforcement of a composite material part for the automotive, aeronautical, or space industries. In particular, the resulting braided structure can form, for example, the fibrous reinforcement of a divergent or rocket engine nozzle.

[0088] The braided structure according to the process of the invention can also allow the formation of straps or ropes.

[0089] A second aspect of the invention is presented in relation to the figures 8 to 16 .

[0090] THE figures 8 and 9 The diagrams schematically illustrate an example of a braiding machine according to the second aspect of the invention, enabling the creation of a braided structure. The braiding machine comprises a plate 61 and a plurality of yarn feed spindles 63. The plate 61 is preferably horizontal, to facilitate its positioning and that of the yarn feed spindles 63. However, it does not depart from the scope of the invention if the plate 61 is vertical or inclined.

[0091] The plate 61 comprises a braiding zone 610 and a reserve zone in the form of several reserve regions 620 distributed along the outer edge of the braiding zone 610, and separated or not from each other. The invention remains within the scope of this invention even if the reserve zone does not belong to the plate comprising the braiding zone.

[0092] The invention remains within the scope of the invention if the braiding machine comprises only a single continuous reserve zone circumferential to the braiding zone. Nor does the invention depart from the scope of the invention if the circumferential reserve zone is rotationally mobile around the braiding zone, for example, in the case where the reserve zone is a continuous ring that rotates around the braiding zone.

[0093] The reserve area, whether or not in the form of several disjoint regions, is preferably located on the outside of the braiding area 610, i.e., around the main guide path 6100, to facilitate its accessibility. However, it does not depart from the scope of the invention if the reserve area, whether or not in the form of several disjoint regions, is located on the inside of the braiding area 610.

[0094] The braiding zone 610 includes a main guide path 6100. The yarn feed spindles 63, which move along this main guide path 6100, participate in the braiding of the braided structure. The main guide path 6100 is therefore configured to be traversed clockwise by a first plurality of spindles 63, and counterclockwise by a second plurality of spindles 63. In the example illustrated on the figures 8 and 9The main guide path 6100 comprises two regularly intersecting sub-guide paths 6110 and 6120, the first sub-guide path 6110 being configured to be traversed by the first plurality of spindles 63 and the second sub-guide path 6120 being configured to be traversed by the second plurality of spindles 63. It is of course not outside the scope of the invention if the main guide path comprises more than two sub-guide paths, for example if one wishes to create a braided structure comprising several layers or having a complex weave, such as an interlock braid.

[0095] Each reserve region 620 includes a secondary guideway 6200. Unlike the wire feed channels 63 in the braiding zone 610, the wire feed channels 63 in the secondary guideway 6200 of these reserve regions 620, or more generally of the reserve zone, do not participate in the braiding of the braided structure. Each secondary guideway 6200 is therefore configured to maintain one or more feed channels in one of the reserve regions 620, that is, outside the braiding zone 610 and the primary guideway 6100. Preferably, there is no direct communication between the different secondary guideways.

[0096] Each wire feed spindle 63 carries a spool of braiding wire and includes a guide support suitable for moving along the main guideways 6100 and secondary guideways 6200. In a well-known manner, each spool of braiding wire is connected to a wire tension management and retraction system.

[0097] The braiding machine further includes at least one drawing point located at a distance from the plate 61, to which are connected the yarns from the reels carried by the feed spindles 63 movable along the main guide path 6100.

[0098] Preferably, the braiding machine includes a mandrel with a shape 65, which is a form on which the intertwined yarns rest to form the tight braid. In this case, the braiding machine allows for processes known as "over-braiding." The braiding machine according to the invention is particularly advantageous when it is desired to produce a braid with significant variations in cross-section, and more specifically, a braid whose perimeter varies considerably. Consequently, the advantages offered by the braiding machine according to the invention are particularly noticeable when said braiding machine includes a mandrel with a shape 65 whose form exhibits significant variations in thickness.

[0099] Preferably, the main guide paths 6100 and secondary guide paths 6200 are machined in the solid of the plate 61 in the form of grooves, having for example a substantially rectangular section, open outwards, and inside which the guide supports of the feed spindles 63 move.

[0100] Preferably, and in a well-known manner, the braiding zone 610 of the plate 61 comprises a plurality of main slotted wheels 611 configured to be driven in rotation in order to circulate the yarn feed spindles 63 along the main guide path 6100, as illustrated in the Figure 10 .

[0101] Preferably, each reserve region 620 of the plate 61 also includes at least one secondary notched wheel 622 configured to be driven in rotation in order to circulate one or more wire feed spindles 63 in the secondary guide path 6200 of said reserve region 620, as illustrated in the Figure 10 Preferably, each reserve area 620 and each secondary guideway 6200 comprises a single secondary notched wheel 622. Preferably, each secondary notched wheel 622 is adjacent to a primary notched wheel 611. When a corridor 63 is maintained in the reserve area 620, on a secondary guideway 6200, there is preferably no transition of the corridor 63 from one notched wheel 622 to another. Thus, preferably, the corridor can travel along the secondary guideway 6200, but only over a region of limited angular extent.

[0102] As illustrated on the Figure 10Each main slotted wheel 611 or secondary slotted wheel 622 preferably comprises four slots. The main slotted wheels 611 or secondary slotted wheels 622 are preferably driven in rotation in a well-known manner by means of gear trains controlled by one or more motors.

[0103] Preferably, each secondary slotted wheel 622 of the braiding machine is linked to a rotation decoupling system, configured to make the rotation of said secondary slotted wheel 622 independent of the rotation of the adjacent main slotted wheel 611.

[0104] Each secondary guideway in the reserve area is connected to the braiding area 610 via a switch element. This switch element is movable between a first position that isolates the secondary guideway 6200 of said reserve area 620 from the main guideway 6100, and a second position that connects the secondary guideway 6200 of said reserve area 620 to the main guideway 6100, in order to allow the passage of at least one feeder corridor 63 between the main guideway 6100 and the secondary guideway 6200. Thus, two branches 6101 and 6102 of the main guideway 6100 and two branches 6201 and 6202 of the secondary guideway 6200 terminate at each switch element.

[0105] Several types of switching elements are possible within the framework of the present invention.

[0106] According to a first embodiment of the invention, the switching element is movable in translation, in accordance with the examples illustrated in the Figures 10 to 12 .

[0107] In the example illustrated on the Figures 10 and 11 The switch element 641 is in the form of a flat solid movable in translation along a translation direction DT1 tangent to the junction between the reserve zone 620 and the braiding zone 610. The switch element 641 includes grooves 6411, 6412, 6413 and 6414 of substantially rectangular cross-section, open outwards, and configured to allow the passage of a feeder spindle guide support 63.

[0108] The 641 switch element comprises a first groove 6411, a second groove 6412, a third groove 6413, and a fourth groove 6414. As illustrated on the Figures 10 and 11The first groove 6411 and the second groove 6412 do not have a common intersection, so that when the switch element 641 is in its first position, the first groove 6411 belongs entirely to the main guide track 6100 and the second groove 6412 belongs entirely to the secondary guide track 6200. Thus, when the switch element 641 is in its first position, the first groove 6411 connects the two branches 6101 and 6102 of the main guide track 6100 and the second groove 6412 connects the two branches 6201 and 6202 of the secondary guide track 6200.

[0109] As illustrated on the Figures 10 and 11 , the third groove 6413 and the fourth groove 6414 of the switch element 641 intersect, so that when the switch element 641 is in its second position, illustrated on the figure 11, the third groove 6413 connects the first branch 6101 of the main guide path 6100 to the second branch 6202 of the secondary guide path 6200 and the fourth groove 6414 connects the second branch 6102 of the main guide path 6100 to the first branch 6201 of the secondary guide path 6200.

[0110] Preferably, the first and second grooves 6411 and 6412 have a curved trajectory, while the third and fourth grooves 6413 and 6414 have a straight trajectory.

[0111] In the example shown on the figure 12The switch element 642 is in the form of a flat solid movable in translation along a translation direction D T2 perpendicular to the junction between the reserve zone 620 and the braiding zone 610. The switch element 642 includes grooves 6421, 6422, 6423 and 6424 of substantially rectangular cross-section, open outwards, and configured to allow the passage of a feeder spindle guide support 63.

[0112] The 642 switch element comprises a first groove 6421, a second groove 6422, a third groove 6423, and a fourth groove 6424. As illustrated on the figure 12 The first groove 6421 and the second groove 6422 are isolated from each other and do not have a common intersection, so that when the switch element 642 is in its first position, illustrated on the figure 12The first groove 6421 belongs entirely to the main guide track 6100 and the second groove 6422 belongs entirely to the secondary guide track 6200. Thus, when the switch element 642 is in its first position, the first groove 6421 connects the two branches 6101 and 6102 of the main guide track 6100 and the second groove 6422 connects the two branches 6201 and 6202 of the secondary guide track 6200.

[0113] As illustrated on the figure 12, the third groove 6423 and the fourth groove 6424 of the switch element 642 cross, so that when the switch element 642 is in its second position, the third groove 6423 connects the first branch 6101 of the main guide track 6100 to the second branch 6202 of the secondary guide track 6200 and the fourth groove 6424 connects the second branch 6102 of the main guide track 6100 to the first branch 6201 of the secondary guide track 6200.

[0114] Preferably, the first and second grooves 6421 and 6422 have a curved trajectory, while the third and fourth grooves 6423 and 6424 have a straight trajectory.

[0115] In the example illustrated on the Figures 13A And 13BThe switch element 643 is in the form of two flat solids 643a, 643b movable in translation along a direction of translation perpendicular to the junction between the reserve zone 620 and the braiding zone 610, the first solid 643a translating in a direction opposite to the second solid 643b. Each solid 643a, 643b of the switch element 643 has a rounded edge opposite a straight edge.

[0116] When the switch element 643 is in the first position, the right edge of the first solid 643a is in contact with the right edge of the second solid 643b, so that the rounded edge of the first solid 643a defines a part of the main guide path 6100 by connecting the two branches 6101 and 6102 of the main guide path 6100 and so that the rounded edge of the second solid 643b defines a part of the secondary guide path 6200 by connecting the two branches 6201 and 6202 of the secondary guide path 6200.When the switch element 643 is in the second position, the rounded edge of the first solid 643a is in contact with one of the walls of the main guideway 6100 and the rounded edge of the second solid 643b is in contact with one of the walls of the secondary guideway 6200, so that the gap generated between the straight edge of the first solid 643a and the straight edge of the second solid 643b allows the passage of a feeder channel 63 from the first branch 6101 of the main guideway 6100 to the second branch 6202 of the secondary guideway 6200, and from the second branch 6102 of the main guideway 6100 to the first branch 6201 of the secondary guideway 6200.

[0117] According to a second embodiment of the invention, the switching element is movable by rotation, in accordance with the examples illustrated in the figures 14 to 16 .

[0118] In the example shown on the figure 14The switch element 644 is in the form of a solid circular flat movable in rotation about an axis of rotation perpendicular to the plate 61. The switch element 644 includes grooves 6441, 6442, 6443 and 6444 of substantially rectangular cross-section, open outwards, and configured to allow the passage of a feed spindle foot 63.

[0119] The 644 switch element comprises a first groove 6441, a second groove 6442, a third groove 6443, and a fourth groove 6444. As illustrated on the figure 14The first groove 6441 and the second groove 6442 do not have a common intersection, so that when the switch element 644 is in its first position, the first groove 6441 belongs entirely to the main guide track 6100 and the second groove 6442 belongs entirely to the secondary guide track 6200. Thus, when the switch element 644 is in its first position, the first groove 6441 connects the two branches 6101 and 6102 of the main guide track 6100 and the second groove 6442 connects the two branches 6201 and 6202 of the secondary guide track 6200.

[0120] As illustrated on the figure 14 , the third groove 6443 and the fourth groove 6444 of the switch element 644 intersect, so that when the switch element 644 is in its second position, illustrated on the figure 14, the third groove 6443 connects the first branch 6101 of the main guide path 6100 to the second branch 6202 of the secondary guide path 6200 and the fourth groove 6444 connects the second branch 6102 of the main guide path 6100 to the first branch 6201 of the secondary guide path 6200.

[0121] Preferably, the first and second grooves 6441 and 6442 have a curved trajectory, while the third and fourth grooves 6443 and 6444 have a straight trajectory.

[0122] In the example shown on the figure 15The switch element 645 is in the form of a flat solid of overall triangular shape connected by a pivot joint to the plate 61 and movable in rotation about an axis of rotation perpendicular to the plate 61. When the switch element 645 is in the first position, the tip of the flat solid is positioned between the main guide path 6100 and the secondary guide path 6200, so that a first edge of the flat solid defines a part of the main guide path 6100 by connecting the two branches 6101 and 6102 of the main guide path 6100 and that a second edge of the flat solid, opposite the first edge of said solid, defines a part of the secondary guide path 6200 by connecting the two branches 6201 and 6202 of the secondary guide path 6200.When the switch element 645 is in the second position, the tip of the flat solid is positioned in contact with one of the walls of the main guide track 6100, or in contact with one of the walls of the secondary guide track 6200 as illustrated on the . figure 15 When the tip of the flat solid is positioned in contact with one of the walls of the main guide path 6100, the gap created between said flat solid and the secondary guide path 6200 allows the passage of a feed channel 63 between the first branch 6201 of the secondary guide path 6200 and the second branch 6102 of the main guide path 6100. When the tip of the flat solid is positioned in contact with one of the walls of the secondary guide path 6200, as illustrated in the figure 15, the gap between said flat solid and the main guide path 6100 allows the passage of a feed channel 63 between the second branch 6202 of the secondary guide path 6200 and the first branch 6101 of the main guide path 6100.

[0123] In the example shown on the figure 16 The switch element 646 consists of four flat solids 646a, 646b, 646c, 646d, generally triangular in shape and free to rotate about an axis of rotation perpendicular to the plate 61. The first solid 646a is located on the second branch 6102 of the main guide track 6100. The second solid 646b is located on the second branch 6202 of the secondary guide track 6200. The third solid 646c is located on the first branch 6201 of the secondary guide track 6200. The fourth solid 646d is located on the first branch 6101 of the main guide track 6100.

[0124] Thus, when the switch element 646 is in the first position, the first solid 646a and the fourth solid 646d each define a wall of the main guideway 6100, blocking passage to the secondary guideway 6200. When the switch element 646 is in the second position, according to a first mode, the first solid 646a pivots to connect the second branch 6102 of the main guideway 6100 to the first branch 6201 of the secondary guideway 6200, the second solid 646b and the third solid 646c being positioned to allow this connection, as illustrated in the figure 16 . According to a second mode, the fourth solid 646d pivots to connect the first branch 6101 of the main guide path 6100 to the second branch 6202 of the secondary guide path 6200, the second solid 646b and the third solid 646c being positioned so as to allow this connection.

[0125] In each of the preceding examples, the switching element can be controlled manually, for example via a lever, or automatically, for example via a control unit configured to operate said switching element.

[0126] The switching element(s) can be connected to the gear system enabling the movement of the feed spindles 63, for example to the gear train driving the rotation of the slotted wheels 611 or 622. The use of a rotating movable switching element is particularly interesting in this case, this configuration allowing a simplified mechanism for actuation of the switching element and easy integration under the table 61 of the braiding machine.

[0127] We will now describe in relation to the figures 8 and 9An example of a braiding process according to the second aspect of the invention for producing a braided structure 6300 exhibiting significant variations in cross-section, and more specifically, substantial variations in the perimeter of the cross-section. Thus, the braided structure 6300 to be produced comprises, along its length, a first zone having a first perimeter of cross-section, a transition zone, and a second zone having a second perimeter of cross-section, the second perimeter being different from the first. Unless otherwise specified, the cross-sections are taken perpendicular to a longitudinal axis of the braided structure. In the example illustrated on the figures 8 and 9 , the first perimeter is larger than the second perimeter and the transition zone has a section whose perimeter decreases regularly between the first zone and the second zone.

[0128] In the example illustrated on the figures 8 and 9The braiding is carried out on the forming mandrel 65, which generally has the shape of the braided structure 6300 to be produced. Of course, the invention remains within the scope of practice even if the braiding is not carried out on a forming mandrel. The yarns from the spools of the yarn feed spindles 63 are fixed to a drawing point.

[0129] The first zone of the braided structure 6300 is created by passing a first number of wire feed spindles 63 along the main guide path 6100, inside the braiding zone 610. Thus, the wires 631 from the spools carried by this first number of spindles 63 intertwine around the shaping mandrel 65, thereby creating the first zone of the braided structure 6300, as illustrated in the figure 8 .

[0130] In order to create the transition zone of the braided structure 6300, whose cross-sectional perimeter decreases while maintaining a wire density and wire angles similar to the wire density and wire angles of the first zone of the braided structure 6300, wire feed spindles 63 are progressively moved from the braiding zone 610 to the reserve zone 620. Thus, these feed spindles 63 leave the main guide path 6100 via a switching element to be held in a secondary guide path 6200, so as not to participate in the braiding of the structure 6300. Consequently, the wires 632 from the reels carried by the spindles 63 held in the reserve zone 620 are no longer braided.

[0131] These wires 632 can be cut by a cutting device (not shown) configured to cut the wire 632 coming from a feed spindle 63 present in the reserve area 620 while the braiding operation continues, in order to avoid any risk of entanglement of one of these wires 632 not participating in the braiding with the wires 631 participating in the braiding.

[0132] When the braiding of the transition zone of the structure 6300 is complete, only a second set of movable wire feed spindles 63 remain along the main guide path 6100, inside the braiding zone 610. In the example shown on the figures 8 and 9 , the second number of 63 mobile feed spindles is less than the first number of 63 mobile spindles when braiding the first zone.

[0133] The second set of movable yarn feed spindles 63 on the main guide path 6100 then allows the second zone of the braided structure 6300 to be braided, the yarns 631 from the spools carried by this second set of spindles 63 intertwining around the shaping mandrel 65 as illustrated in the figure 9 .

[0134] In an unillustrated variant, a braided structure can be created, having along its length a first zone with a first cross-sectional perimeter, a transition zone, and a second zone with a second cross-sectional perimeter, as in the example illustrated on the figures 8 and 9but further comprising a second transition zone and a third zone having a third section perimeter. The third perimeter of the third section is greater than the second perimeter of the second section, and may also be less than or greater than the first perimeter of the first section. Of course, the invention remains within the scope of the invention if the third section perimeter is less than the first and second section perimeters.

[0135] In this variant, the first zone, the transition zone, and the second zone are constructed as described previously. To create the second transition zone of the braided structure, located as an extension of the second zone and with an increasing cross-sectional perimeter, while maintaining a wire density and wire angles similar to those of the first and second braided zones, wire feed spindles from the reserve zone are progressively transferred to the braiding zone to participate in the braiding process. These feed spindles leave the secondary guideway, where they were held, via a switching element, and are introduced onto the primary guideway to contribute to the braiding of the structure.Therefore, the wires from the reels carried by the spindles added to the main guide path are braided with the wires from the reels carried by the second number of spindles already present on the main guide path.

[0136] When the braiding of the second transition zone of the structure is complete, a third set of yarn feed spindles move along the main guide path within the braiding zone. This third set of yarn feed spindles, moving along the main guide path 6100, then allows the third zone of the braided structure to be braided, with the yarns from the spools carried by this third set of spindles intertwining around the forming mandrel.

[0137] The term "yarn" used in this application may refer to a single yarn or single fiber, but may also refer to a strand or braid.

[0138] In particular, the fibers can be carbon fibers, ceramic fibers, or a mixture of carbon and ceramic fibers. The braided structure according to the process of the invention can be a fibrous structure, which may optionally be consolidated or densified by a matrix to form the fibrous reinforcement of a composite material part. The braided structure according to the process of the invention can thus form, for example, all or part of the fibrous reinforcement of a composite material part for the automotive, aeronautical, or space industries. In particular, the resulting braided structure can form, for example, the fibrous reinforcement of a divergent or rocket engine nozzle.

[0139] The braided structure according to the process of the invention can also allow the formation of straps or ropes.

Claims

1. A braiding machine comprising: - a plurality of yarn feed spindles (30) connected to guide supports (51) and movable along a guide path (100) so as to participate in the braiding, all or some of the spindles (30) being integral with a positioning element (35) cooperating with a corresponding guide support (51) and removable from the latter, - a plurality of reserve supports (52) located outside the guide path (100), said reserve supports (52) being able to receive yarn feed spindles (30) placed in reserve so as to interrupt their participation in the braiding, the positioning elements (35) being able to cooperate with the reserve supports (52) in order to carry out this placing in reserve, the braiding machine being characterised in that it comprises a drive system (73, 74, 76, 21, 22) of the reserve supports (52) able to drive at least some of the reserve supports (52) circumferentially to the guide path (100).

2. The machine according to claim 1, wherein the drive system (73, 74, 76, 21, 22) of the reserve supports (52) comprises at least one first ring (21) circumferential to the guide path (100) and able to turn in a first direction of rotation, and at least one second ring (22) circumferential to the guide path (100) and able to turn in a second direction of rotation opposite to the first direction of rotation, each first or second ring (21, 22) bearing one or more reserve supports (52).

3. The machine according to claim 1 or 2, wherein the reserve supports (52) are present around the guide path (100).

4. The machine according to any one of claims 1 to 3, said machine comprising a global drive system including the drive system (73, 74, 76, 21, 22) of the reserve supports (52) and a drive system (71) of the guide supports (51), the global drive system being configured so that the angular velocity of at least some of the reserve supports (52) is a function of the angular velocity of at least some of the guide supports (51) in order that the movement of at least some of the reserve supports (52) accompanies the movement of at least some of the guide supports (51).

5. The machine according to claim 4, wherein the global drive system comprises a transmission system (72) configured to transmit the movement of a drive system (71) of the guide supports (51) to the drive system (73, 74, 76, 21, 22) of the reserve supports (52).

6. The machine according to any one of claims 1 to 5, said machine further comprising a shaping mandrel (5) on which the braiding is intended to be carried out.

7. The machine according to any one of claims 1 to 6, said machine further comprising a robotic arm (8) configured to displace at least one spindle (30) between a guide support (51) and a reserve support (52).

8. The machine according to any one of claims 1 to 7, said machine further comprising a cutting device (9) configured to cut a yarn (32, 33) coming from a feed spindle (30), the positioning element (35) of which cooperates with a reserve support (52).

9. A method for braiding a braided structure (300) comprising a first zone having a first cross-section and a second zone having a second cross-section different from the first cross-section, the method using a machine according to any one of claims 1 to 8 and comprising: - the braiding of the first zone of the braided structure (300) with a first number of yarn feed spindles (30) movable along the guide path (100), and - the braiding of the second zone of the braided structure (300) with a second number of yarn feed spindles (30) movable along the guide path (100), the second number of spindles being different from the first number of spindles through the displacement of spindles (30) between the guide supports (51) and the reserve supports (52) by cooperation of the positioning element (35) of said displaced spindles with the guide supports (51) or reserve supports (52).

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