EP0098762A1 - Three-dimensional hollow armature, process and apparatus for making the same - Google Patents

Abstract

The invention relates to the production by three-dimensional weaving of hollow frames of deformable revolution. In a network of rods (18), maintained and rotated around a vertical axis (11) by rotary perforated plates (52, 53, 54), wires are inserted in oblique crossed directions, that is ie non-radial, in the form of chain loops made by a knitting device (32). The chains are packed down by the lower edge of the plate (52), inclined for this purpose.

Description

The present invention relates to the manufacture of hollow pieces of revolution by three-dimensional weaving.

Woven parts of this kind serve as reinforcements in the manufacture of cylindrical, conical or cylindro-conical hollow bodies obtained by impregnation using a suitable binder followed by machining at the precise dimensions desired for the hollow bodies. Such hollow bodies are used in particular in the aeronautical field for rockets and ballistic devices such as nozzles, heat shields or propulsion bases. More generally, this type of part can be used in industry whenever there is a need for high characteristics both with respect to mechanical stresses, thermal insulation or good resistance to shocks and 'ablation.

Various processes are known for producing hollow cylinders or hollow revolution parts.

US Patent No. 3,904,464 describes a process for producing a hollow body of revolution. It consists, on a specialized tool having the internal shape of the part, to make a hedgehog of radial pins in fibers and polymerized resin. Inside the pins which delimit corridors, wires preimpregnated with resin are wound. Polymerization is then carried out, followed by machining. To improve the mechanical and thermal characteristics of the material, the operation can be repeated. This process has drawbacks: the making of the reinforcement is long and complex, the manufacturing operations are numerous and are not applicable to all types of fibers.

French patent n ° 73/14 956 (in the name of the applicant) describes an apparatus for the production by three-dimensional weaving of hollow revolution parts. Using a tapping head, circumferential and radial wires are simultaneously deposited through a network of longitudinal rods made of fibers and polymerized resin. This process makes it possible to produce cylindrical, or, with some difficulties, conical parts, but does not allow make pieces of complex shapes.

The two embodiments which have just been mentioned have another drawback relating to the quality of the parts obtained, which depends on the fiber content of the latter. This quality is conditioned by regular compaction during manufacture; however, this compaction is most often manual and does not take place after the deposition of each layer. The part obtained, if it is thick, is heterogeneous, which affects its mechanical and thermal characteristics.

Progress appears in French patent n ° 77/18 831 also belonging to the applicant. The production of hollow parts of cylindrical, conical or cylindro-conical shape is carried out by introducing between metal rods, kept vertical, a helical layer of circumferential and radial wires over the entire height of the part. This process is characterized by the deposition of circumferential wires under low tension and by the realization of a radial weaving at the chain stitch. During the entire weaving operation, the layers are constantly packed. Next, the rods are eliminated and replaced by threads according to an automatic lacing process described by the applicant in French patent application No. 80/17666.

This process made it possible to produce parts of cylindrical or complex shape having good mechanical and thermal characteristics. However, the tools used remain relatively complicated and the final shape of the parts is fixed by the weaving operation. An adaptation of the manufacturing equipment is necessary for each type of shape to be obtained.

The invention therefore aims to achieve by three-dimensional weaving of hollow cylinders which are deformable thanks to a particular structure and allow, by simple deformation, to obtain parts offering such or such desired complex shape.

The first object of the invention is thus first of all a part or frame in the form of a hollow cylindrical body of revolution, produced in a known manner by weaving three-dimensional of three systems of wires intersecting substantially in the directions of a trirectangle trihedron, namely a first system of wires parallel to the axis of the reinforcement and arranged equidistantly in coaxial sheets which are themselves equidistant, and a second and a third system of wires contained substantially in planes perpendicular to said axis, forming superimposed layers and fitting into two respective series of crossed corridors defined by the wires of the first system. According to the invention, the wires of the first system are staggered from one layer to the next and the two series of crossed corridors which they define between them cross the thickness of the armature obliquely, that is to say say no radially. This arrangement leads to a deformable structure mainly due to the absence of circumferential wires and radial wires, replaced by oblique wires which do not oppose deformations tending to vary the local diameter of the woven hollow part (with concomitant variation of its wall thickness). Preferably, the corridors of the two above-mentioned series have an obliquity of the same value, but in opposite directions, with respect to the radial directions of their intersections .; In other words, any two corridors which intersect are symmetrical with respect to the radial plane passing through their intersection. The corresponding wires therefore form squares, one of the diagonals of which is radial and which easily deform into diamonds.

In a preferred embodiment, the wires of the second and third systems are formed by the loops of two respective chains made up of helical turns in the network of wires of the first system.

The subject of the invention is also a method of producing such woven reinforcements with a triple system of constituent threads, in which, in a known manner, an odonned network is formed around an axis, filiform elements parallel to this axis, materializing the wires of the first system and regularly arranged in successive coaxial layers, and we introduce into the two series of crossed lanes that the wires of the second and third systems show up in this layer in superimposed layers. According to the invention, said filiform elements are staggered staggered from one ply to another and the wires of the second system as well as the wires of the third system are introduced respectively in two oblique crossed directions, into the corridors defined obliquely at through the network of filiform elements thanks to the staggered arrangement of these. These threads are preferably introduced in helical layers by knitting in the chain stitch of two separate threads, the loops of each of the two chains thus made up respectively forming said threads of the second and third systems inserted in the aforementioned crossed corridors. It should de.prévoir said son, which are deposited in superimposed layers, are packed as and when they are introduced into the network.

The aforementioned filiform elements can be tensioned threads (directly constituting the first system of threads). They can also be temporary rods which, after completion of the weaving, are replaced by threads. It is also possible to use hollow provisional rods into which threads have been previously introduced and which are eliminated after completion of the weaving, only the threads which they contain remain.

The invention finally relates to a machine for implementing the process defined above (with the use of temporary rods). This machine comprises, in a known manner, a fixed frame supporting a set of rotary elements centered on a generally vertical axis, driven in rotation about this axis and ensuring the holding of the rods which materialize the wires of the first system in regular network of coaxial plies, the longitudinal maintenance of these rods and the rotation of said network around said axis, as well as the packing of the layers of yarns woven in the network of rods, and a knitting device, placed on said frame in a location fixed at the level where the weaving of the frame takes place, said rotary elements being constituted by plates provided perforations regularly arranged in circles centered on the axis and crossed by the rods, one of these perforated plates being animated, in addition to its rotational movement, a controlled and progressive downward movement during the weaving of the frame, and supporting it by allowing its descent along the rods. According to the invention, the perforations of said plates are arranged in staggered rows on the aforementioned successive circles and the knitting device is equipped with two sliding needles driven by a clean longitudinal reciprocating movement and oriented obliquely to the axis of rotation, the direction of one passing to the right of this axis and that of the other to the left, the arrangement of these needles being such that, during their back-and-forth movement, they penetrate and are move in the oblique corridors defined by the network of rods, one in the corridors of one of the series, the other in those of the other series of corridors, each to come and grab a respective thread and knit it in one chain, the loops of these two chains thus made during the rotation of the network of rods respectively forming the wires of the second system and the wires of the third system.

In practice, the oblique corridors may be slightly curved, the needles then being curved in correspondence and guided in their back-and-forth movement by similarly curved slides.

With a view to compacting the mass woven into the network of baguettes, the machine advantageously comprises, at the top of the network of baguettes, a perforated plate carried by a fixed support in a slightly inclined position, and the needles of the knitting device are arranged on the side and slightly below the upper part of this perforated tray, while, on the other side, its lower part rests on the helical layers formed in the network of rods by the chains knitted by said needles and in ensures compaction during the production of the woven reinforcement. Furthermore, under the network of rods is preferably arranged a fixed plate (not perforated) provided with a vibrating bar ensuring the maintenance longitudinal of the rods at a constant height on average, without them having to bear and rub continuously on said fixed plate.

• La figure 1 représente en perspective une machine de tissage tridimensionnel selon l'invention.
• La figure 2 représente en perspective de manière simplifiée la partie de la machine correspondant à la zone de tissage, vue de dessus.
• La figure 3 représente schématiquement une vue fragrentaire d'une pièce en cours de confection dans la machine, la flèche III de la figure 1.
• La figure 4 représente en perspective le mécanisme d'actionnement de l'une des aiguilles du dispositif de tricotage de la machine.
• Les figures 5 et 6 représentent, respectivement en section transversale et en perspective, un fragment de pièce en cours de confection et en montrent la structure interne.
• Les figures 7 à 9 représentent trois exemples de pièces de forme complexe obtenues par déformation de pièces cylindriques réalisées conformément à l'invention.

The description which follows, with reference to the accompanying drawings by way of nonlimiting examples, will make it possible to understand clearly how the present invention can be put into practice.

• Figure 1 shows in perspective a three-dimensional weaving machine according to the invention.
• FIG. 2 is a simplified perspective view of the part of the machine corresponding to the weaving area, seen from above.
• FIG. 3 schematically represents a fragmentary view of a part being made in the machine, arrow III of FIG. 1.
• Figure 4 shows in perspective the actuation mechanism of one of the needles of the knitting device of the machine.
• Figures 5 and 6 show, respectively in cross section and in perspective, a fragment of a piece being made and show the internal structure.
• Figures 7 to 9 show three examples of parts of complex shape obtained by deformation of cylindrical parts made in accordance with the invention.

It will first be noted that, if the number of coaxial plies of rods in the part being produced varies from one figure to another, this is so for simple reasons of convenience of representation. In practice, the number of these layers is chosen in each case according to the dimensions of the part to be produced.

The machine shown in Figure 1 is intended for the production by three-dimensional weaving of parts or armatures in the form of a hollow cylinder of revolution with a structure giving them significant deformability.

This machine essentially comprises a base 1 carrying a vertical frame 2 provided with three horizontal supports 3, 4, 5 in the form of a fork. The upper support 3 is fixed to the frame 2. The intermediate support 4 is movable vertically and guided by a pair of vertical slides 68 fixed to the frame 2. It can go up or down under the action of a vertical threaded rod 55 driven in rotation, with which is engaged a nut 58 secured to said support. The lower support 5 maintains a fixed position during the operation of the machine, but adjustable (depending on the height of the part to be produced) using an appropriate device not visible in the figure, by sliding along the slides 68 cited above. Each of the supports 3, 4, 5 carries a circular frame. These frames 8, 9, 10 are aligned along a vertical axis 11 which coincides with the axis of the reinforcements to be produced, and each of them concentrically carries a rotating crown. To each of these crowns 12, 13, 14 is fixed a concentric annular plate situated in the same plane as the corresponding crown and frame. These plates 52, 53, 54 are perforated to receive and hold in position a network of metal rods 18 parallel to the axis 11. They are rotated around this axis by means of toothed belts 19 passing respectively over the crowns 12, 13, 14 and on drive pulleys 20 mounted on a vertical shaft 21 rotated by a motor 22 to which it is coupled by a transmission comprising at its output a toothed belt 23 and a pulley 24. The intermediate supports 4 and lower 5 being capable of moving vertically, the shaft 21 is grooved and the corresponding pulleys 20 can slide longitudinally while remaining in engagement therewith. Between the perforated plates 53 and .54 can be provided additional perforated plates 62, suspended by chains 63. The upper frame 8 is, as shown, slightly inclined to the horizontal, for a reason which will appear later. This fact explains the presence of return pulleys 25 over which the corresponding belt 19 must pass.

Each of the plates 52, 53, 54 is identically pierced with perforations 30 (FIG. 2) regularly distributed over equal concentric circles, each circle having the same number of equidistant perforations. The perforations of a circle are staggered compared to those of a neighboring circle, that is to say that the rays passing through the perforations of one share in two halves the intervals separating the perforations from the other. Thanks to these perforations, the rods 18 are engaged through the plates 52, 53, 54 and are held there in a regular network composed of coaxial sheets 65 where two series of oblique rows 26, 27 of rods 18 appear (slightly) curved, extending in crossed directions symmetrical with respect to the radial planes such as 31 passing through rods situated at the intersection of rows of the one and the other series. These oblique rows of rods delimit two series of oblique corridors 36, 37 (FIG. 6), that is to say non-radial, likewise crossing each other substantially at right angles and intended to receive wires 46 (for one of the series) and 47 (for the other series), contained in planes perpendicular to the axis 11 and obliquely crossing in the two above-mentioned substantially orthogonal directions the thickness of the strip network 18 (FIGS. 5 and 6).

The oblique threads 16, 17 are inserted into the network of rods 18 by knitting two chains 56, 57 from threads 46, 47 from two supply tubes 66, 67 by means of hook needles 6, 7 ( Figure 2) successively introducing each into the oblique corridors 36, 37 of one and the other of the above series of corridors. These hook needles are part of a knitting device 32 (FIG. 1) fixed to the support 3. This device is shown in detail in FIG. 4 where, for reasons of clarity, only one needle is shown, know the needle 6, and its own mechanism, the other needle and its mechanism being symmetrical with respect to a radial plane. The needle 6, curved to fit perfectly in the corridors 36 of the corresponding series, moves in a longitudinal-reciprocating movement, guided in a slide 33 likewise curved which is fixed to a part 34 belonging to the support 3. This slide has a lateral slot 43 through which emerges a tab 35 for driving the needle, connected by an articulated rod 38 to one of the arms of a spreader 39 in the shape of a T, oscillating around a pivot 40 with a vertical axis secured to the part 34 under the action of a control cable 41 actuated by the motor 22, the other arm of the lifter 39 symmetrically receiving an actuating rod of the another needle 7. The needles 6, 7 therefore penetrate alternately in the oblique passages 36, 37 of the network of rods 18. The needle 6 (like needle 7) is a sliding needle, which is formed by the end a rod 42 (Figure 2) which can slide longitudinally inside the needle to open or close the eye thereof. This rod has a tab 44 which projects from the body of the needle by a notch 51 and from the slide 33 by the slot 43 and to which is articulated a rod 45 which slides in a part 48 mounted on a fixed fitting 49 and which is braked by a friction tongue 50.

The needle 6 having advanced, eye open, through the network of rods 18 as far as the extreme position shown in FIG. 4, it hooks the wire 46, then retreats by pulling a loop of this wire in the corridor 36 where it is finds, as far as the other extreme position shown in FIG. 2 for the needle 7. In this recoil movement, the rod 42 remains stationary at first (due to the braking of the tongue 50), so that its end closes the eye, then moves back with the needle, its tab 44 abutting against the anterior edge of the notch 51. The needle comes to stop outside the network of rods so as to form a loop of wire. Its eye having opened thanks to a reverse movement of the rod 42, the needle releases the thread and again enters the network by passing through the loop that it has just formed. The needle 7 performs the same operations, but at a height slightly greater than that of the needle 6 and in a different direction (FIG. 2).

In operation, the motor 22 of the machine drives the network of rods 18 in continuous rotation. This network thus continuously scrolling past the knitting device 32 fixed, the needles 6, 7 thereof insert two chains 56, 57 which overlap in helical layers in said network. The loops are formed around the oblique rows 26, 27 of rods and constitute the oblique wires 16, 17, crossed between themselves and with the rods 18. The wires 16, 17 thus form a second and a third system of wires s ^t intersecting with a first system of rods 18, which will then be replaced (according to the method described by the applicant in patent application No. 80/17666 by wires of the same kind as the wires of the second and third systems. As and as the woven mass 15 is formed in the network of rods 18, the perforated plate 53, initially close to the upper support 3, descends by supporting this woven mass of increasing height, which is continuously packed by the upper perforated plate 52 thanks to the inclination given to it (at an angle depending on the diameter of the part to be produced and normally less than or equal to 15 °). We can see in FIG. 3 that the chains 56, 57 made up by the knitting device 32 (placed on the side of the upper part of the plate 52) are biased downwards and compacted by the lower part of the plate 52. The continuous downward movement of the plate 53 drives down the woven mass 15 and the rods 18, which are periodically wound up as they pass over a vibrating bar 59 carried by a circular plate 60 linked to the lower support 5 by a fitting 61. Thus, the rods 18 retain an invariable mean position in the direction of the height.

Figures 7 to 9 illustrate the ability to deform the woven reinforcements obtained, by clamping or stretching some of their parts according to the shape that is desired. The deformations are produced by modifications of the crossing angle of the wires 16 and 17. We see in FIG. 7 a conical frame 62 obtained by widening on one side and narrowing on the other side of a cylindrical frame shown in dashed lines. Figure 8 shows an armature 63 for nozzle with converging, neck and diverging. Figure 9 shows a woven piece 64 which has been given the shape of a shouldered washer. Once the desired shape has been obtained, the part is impregnated and then baked to solidify it definitively.

Claims (13)

1. Armature in the form of a hollow cylindrical body of revolution, produced by three-dimensional weaving of three systems of wires crossing each other substantially along the directions of a trirectangle trihedron, namely a first system of wires parallel to the axis of the armature and arranged equidistantly in coaxial sheets which are themselves equidistant, and a second and a third system of wires contained substantially in planes perpendicular to said axis, forming superimposed layers and fitting into two respective series of crossed corridors defined by the wires of the first system, characterized by a deformable structure in which the wires of the first system are staggered from one layer to the next; while the two series of crossed corridors which they define between them cross the thickness of the reinforcement obliquely, that is to say not radially. 2. Reinforcement according to claim 1, characterized in that the corridors of the two above-mentioned series have an obliquity of the same value, but in opposite directions, with respect to the radial directions of their intersections. 3. Reinforcement according to claim 1 or 2, characterized in that the wires of the second and third systems are formed by the loops of two respective chains made up of helical turns in the network of wires of the first system. 4. A method of producing woven reinforcements with a triple system of constituent wires according to any one of claims 1 to 3, in which an ordered network is formed around an axis of filiform elements parallel to this axis, materializing the wires. of the first system and regularly arranged in successive coaxial layers, and the wires of the second and third systems in superimposed layers are introduced into the two series of crossed lanes, this process being characterized by the fact that said filiform elements ( 18) are arranged in staggered offset from one ply (65) to the other and that the wires of the second system (16) as well as the wires of the third system (17) are introduced respectively in two crossed oblique directions, in the corridors (36, 37) defined through the network of filiform elements (18) thanks to the staggered arrangement of these. 5. Method according to claim 4, characterized in that the son (16, 17) of the second and third systems are introduced in helical layers by knitting in the chain stitch of two separate son (46, 47), the loops of each two chains (56, 57) thus made up respectively forming said wires of the second and third systems inserted in the aforementioned crossed corridors (36, 37). 6. Method according to claim 4 or 5, characterized in that the son (16, 17) are packed as and when they are introduced into the network. 7. Method according to any one of claims 4 to 6, characterized in that the filiform elements are stretched son. 8. Method according to any one of claims 4 to 6, characterized in that the filiform elements are rods (18) which, after completion of weaving, are replaced by son. 9. Method according to any one of claims 4 to 6, characterized in that the filiform elements are hollow rods (18) in which threads have been previously introduced and which are eliminated after completion of the weaving. 10. Machine making it possible to implement the method according to claim 8 or 9, comprising a fixed frame supporting a set of rotary elements centered on a general vertical axis, driven in rotation about this axis and ensuring the holding of the rods which materialize the yarns of the first system in a regular network of coaxial plies, the longitudinal maintenance of these rods and the rotation of said network around said axis, as well as the compaction of the layers of son woven in the network of rods, and a knitting device placed on said frame in a fixed location at the level where the weaving of the frame takes place, said rotary elements being constituted by plates provided with perforations regularly arranged in circles centered on the axis and crossed by the rods, one of these perforated plates being animated, in addition to its rotational movement, of a controlled and progressive descending movement during weaving of the frame and supporting it allowing it to descend along the rods, machine. characterized by the fact that the perforations (30) of said plates are staggered on the aforementioned successive circles and that the knitting device (32) is equipped with two sliding needles (6, 7) animated by a movement of back and forth clean and obliquely oriented relative to the axis of rotation (11), the direction of one passing to the right of this axis and that of the other to the left, the arrangement of these needles (6, 7) being such that, during their back-and-forth movement, they penetrate and move in the oblique corridors (36, 37) defined by the network of rods (18), one in the corridors of the one of the. series, the other in those of the other series of corridors, each to pick up a respective thread (46 or 47) and knit it into a chain (56 or 57), the loops of the two chains (56, 57) as well made during the rotation of the network of rods (18) respectively forming the wires of the second system (16) and the wires of the third system (17). 11. Machine according to claim 10, characterized in that the oblique passages (36, 37) are slightly curved and that the needles (6, 7) are curved in correspondence and guided in their reciprocating movement by similarly curved runners (33). 12. Machine according to claim 10 or 11, characterized in that it comprises, at the top of the network of rods (18), a perforated plate (52) carried by a support (3) fixed in a slightly inclined position, and that the needles (6, 7) of the knitting device (32) are arranged on the side and slightly below the upper part of this perforated plate (52), while, on the other side, its lower part rests on the helical layers formed in the network of rods (18) by the chains (56, 57) knitted by the needles (6, 7) and ensures their compaction. 13. Machine according to any one of claims 10 to 12, characterized in that under the network of rods (18) is disposed a plate (60) fixed provided with a vibrating bar (59) ensuring the longitudinal maintenance of the rods (18) at a constant height on average.

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