FR2884836A1 - Multi-layer circular braiding machine e.g. for composition material reinforcement has bobbins moving along crossing spiral grooves - Google Patents

Abstract

The braiding machine, designed to produce a triaxial multi layer textile reinforcement, differs by having its bobbins moving along crossing spiral grooves that are connected in pairs by axial grooves. It also has tubes located between the groove intersections for the introduction of axial filaments between those coming from the bobbins, while mechanical devices in the form of rollers (8) running along inclined surfaces allow the bobbins to move in one direction in the grooves and not in the other. In the finished tubular article the surface axial filaments are partially covered by oblique filaments running alternately in opposite directions.

Description

The present invention relates to textile machines for the production

  braided multilayer tubular structures, as well as their applications to the production of fibrous reinforcements for composite material parts. It relates more particularly to a new type of machine for making braids

  consisting of a plurality of braided layers bonded to each other.

  The type of textile machine made according to the invention is generally called braider and this name will be retained in the remainder of this document to designate the machine according to the invention.

  It belongs to the family of multilayer braiders.

  An example of the prior art is US Pat. No. 4,312,261. This patent describes a braiding machine made up of concentric rings having notches. The alignment of these notches frees radial corridors in which can be moved the pads carrying small coils, called spindles in a braider. Circular braiding of the threads is achieved by sequentially rotating the rings and then radially moving the studs. The problem of compacting the wires is not dealt with.

  US Patent No. 4,934,240 describes a sequential braider consisting of rotating circular rings arranged in a cylinder having notches in which can slide axially the supports of the spindles. This machine does not make triaxial braids and its operation is slow because the movement of the spindles is made by a succession of small movements. The compaction of the layers is naturally done by clamping on the central mandrel.

  US Patent 6,129,122 also discloses a concentric ring sequential braider in which a compaction ring is disposed. Its complexity and slowness, due in particular to this compaction, prevents to make large braiders based on this principle. The claimed textile structure includes radial threads whose utility is limited to rare applications.

  French Patent 2,804,133 gives an example of a circular braider made in the usual manner of braiders, that is to say that it comprises concentric circumferential rows of worm wheels driven by gears. Points between the worm wheels determine the path of the spindles. The axial threads pass through the center of the worm wheels. This type of machine is fast and safe operation but does not allow to achieve a fibrous architecture of optimal quality. However, the mechanical characteristics of a composite material part depend on the way in which the wires are arranged according to the direction of the forces, without creating voids in order to be able to reach a volumetric rate in wires of the order of 60%, and without pleats. in the thickness of the woven structure.

  French Patent 2,753,993 provides a fibrous architecture of optimal quality. This machine has waders staggered inside a cylinder. The path of the spindles is obtained by the combination of the rotation of the worm wheels and the tilting of guide needles. A slight desynchronization between the two mechanisms is enough to block the operation. The paths of the spindles are not all circular arcs because the spindles must fit radially into the notches of the worm wheels. These paths are delicate and cause friction that may also block the operation. Gears arranged obliquely are difficult to cut. This braider is expensive, delicate to manufacture and adjust.

  The present invention overcomes these problems of cost and unreliability by simply realizing a braider producing a high quality fibrous architecture.

  The operation of this machine differs fundamentally from the braiders known in the prior art. It will produce a textile structure of comparable quality to that described in the patent 2,753,993, but without any complex mechanism. This simplicity will make it possible to make large weavers according to the invention for a reasonable price because the components can be made in series by plastic molding for a low cost. The quality of the textile architecture created by a braider according to the invention allows the use of large section son without harming the performance of the parts produced. The concept of this braider makes it possible to mount mobile coils of relatively large size to reduce the changes of coils that take time. This size of the coils is an important factor to reduce the cost of reinforcement made. Its operation involves only large simultaneous movements of all the coils of a direction. The braiding speed is therefore relatively high. A braider according to the invention therefore produces cost-effectively textile structures of high quality, used in many areas for a wide range of applications.

  The general arrangement of this braider is close to that described in patents US 4 934 240 or FR 2 753 993, that is to say that the spindles are arranged inside a cylinder and the threads are wound around a central mandrel.

  The machine according to the invention is characterized by the displacement of the spindles in cross helical paths. For this purpose this braider comprises a cylindrical part in which are arranged cross helical grooves. In these grooves slide studs some of which support the spindles, called spindle holders and other intermediate pads. These helical grooves will join two by two in axial grooves at the two edges of the cylinder, giving a Y shape. In these axial grooves are also arranged intermediate pads. These pads will slide under the action of pushers to enter one side of the cylinder in the helical grooves by moving the spindle holders. On the other side of the cylinder, other intermediate pads will emerge from these helical grooves to enter the axial grooves. A mechanical non-return device imposes the direction of movement in the helical grooves.

  Between the crossings of the helical grooves are arranged tubes in which pass the son constituting the axial direction of the textile reinforcement made by this braider.

  This braider therefore has no gears, wheeler wheels, movable turnouts, or mobile circumferential crowns.

  In one example of the invention, three interposed pads are arranged between two spindle holders and seven spacers on each side. The braiding will consist of pushing these 7 studs into all the even axial grooves in order to bring out 7 others on the opposite side in the odd axial grooves. The spindle carriers moved in the helical grooves a distance corresponding to 8 pads. This operation is repeated in the odd grooves, then on the opposite side also in the even and odd grooves.

  The attached drawing figures will show how the invention can be realized.

  Figure 1 is a general view of the machine showing the general arrangement of son coming to be placed on a central mandrel. The coils of the axial threads are arranged in creels on each side of the braider and come out to get on its periphery.

  Figure 2 is a side view also showing the general arrangement of this machine, the son of which arrive from the braiding cylinder on a central mandrel, resting on a ring. It is the displacement of the mandrel relative to this ring which allows the unwinding of the axial threads.

  Figures 3a, 3b, 3c and 3d show the general arrangement of the helical grooves inside the braiding cylinder which meet in axial grooves, and the positions of the pads corresponding to the 4 displacements constituting the braiding sequence.

  Figures 4a and 4b show how is obtained the change of grooves pads between their output of a helical groove, their entry into an axial groove and their output to the adjacent helical groove, with a non-return device disposed in the groove output of the studs.

  Figure 5 shows the sectional view of the passage of a spindle between two axial passage tubes son.

  Figure 6 shows the top view of a cross between the helical grooves. Figure 7 is a section of the machine showing the rings whose displacement controls the movement of the pads in the axial grooves.

  Figure 8 shows how a ring is connected by bars to the control buttons of the pads and the arrangement of these elements on the braider.

  Figure 9 shows the top view of the braid made on the machine.

  Figure 10 shows the path of some son in the wall of the textile structure created by the displacement of the pads.

  We will describe an example of a machine according to the invention.

  The braiding machine shown schematically and partially in FIG. 1 comprises a set of profiles 1, individually visible in FIG. 8, held in the form of a cylinder by an octagonal frame 2 made of welded tubes.

  Under these sections 1 are fixed in staggered square parts 3, visible in Figures 5, 6 and 7. It is the positioning of these parts that creates the grooves in which the intermediate pads 4 and door-pipes 5 slide. In the center of these square pieces 3 are fixed the tubes 17 through which the axial threads 19 pass.

  The circumference and the length of this cylindrical part make it possible to fix 120 sections 1 on which 4 and 5 square parts 3 and tubes 17 for passing axial threads 19 are arranged alternately. These sections 1 thus carry 540 square pieces.

  At the ends are fixed the guide pieces 6 and 7, visible in Figures 3 and 4. The guide piece 7 comprises two rollers 8 which allow free movement of the pads in one direction and prevent it in the opposite direction. Each side has 30 pieces 6 and 30 pieces 7, creating 60 axial grooves.

  Each helical row comprises 4 spindle-bearing studs 5 separated by 3 intermediate studs 4, and 7 intermediate studs on each side.

  This machine includes 2220 studs including 240 spindle holders.

  The shape of the studs 4 and 5 allows them to slide between the square pieces 3 by being able to withstand the tensile force of the wires thanks to the T-shape of the grooves 15 obtained.

  The square parts 3 consist of a square bottom portion covered with a plate 18 on which the studs 4 and 5 slide. This plate has the shape of the cylindrical surface that they constitute to facilitate the sliding of the studs.

  The spindle 16, visible on the stud 5 of FIG. 6, is a well-known component of the braids and is therefore not described. It comprises a braking device of the coil connected to the tension of the thread which makes it possible to deliver a thread under a constant tension and to recall it backwards during certain movements of the spindles.

  The two control rings 10 and 11, visible in FIGS. 7 and 8, are connected to the push-buttons 9 by means of bars 12 in the manner visible in FIG. 8.

  The even pushers on one side are attached to the odd pushers on the other side. Each ring is moved axially by three cylinders 13 arranged at 120 and controlled simultaneously.

  A mandrel 14 is located in the center of the machine. This component is a common component of this type of braider and is therefore not described in detail. It may have a shape other than round, rectangular for example, or be of a variable section. It can be movable to pull the braid, or be fixed and the braid is pulled to be rolled on a drum. A ring 15 surrounds the mandrel and serves as a formation zone for the braided structure.

  This multilayer braider therefore essentially comprises 120 sections 1, 540 square pieces 3, 1980 intermediate pads 4 and 240 bearing blocks 5, 120 pushers 9, 60 connecting rods 12, 60 pieces 6 and 60 pieces 7. It also comprises 240 spindles and 540 coils of axial threads.

  The operation of this braider according to the invention consists of the sequential displacement of the two rings 10 and 11. It is considered that the starting position is that of Figure 3a. This figure is obtained by a symmetrical position of the control rings. Suppose this position is the rings to the outside. The passage in FIG. 3b is then obtained by displacement towards the center of the ring 10, the passage in FIG. 3c is obtained by the displacement towards the center of the ring 11, the passage in FIG. 3d by the displacement towards the the outside of the ring 10 and the return to Figure 3a by the outward movement of the ring 11. Simultaneously the central mandrel 14 has advanced a certain amount to give the oblique son orientation sought. The ring 15 remains globally immobile. For the braiding of certain son, it is mounted vibrating to facilitate the traction of the axial son and avoid blockages between the oblique son 20 and axial 19 to its contact.

  The textile reinforcement created by this braider is shown schematically in FIGS. 8 and 9. It will comprise at most 540 axial threads 19, 120 oblique threads 20 in one direction and 120 oblique threads 20 in the symmetrical direction. This reinforcement consists of 120 radial rows of 5 and 4 axial threads 19, connected by the oblique threads 20 along the paths of FIG. 9.

  The layers of axial threads 19 will have a staggered arrangement which is useful for obtaining good mechanical characteristics by decreasing the angle made by each oblique yarn in the thickness and avoiding the presence of hollow zone without axial threads. The oblique threads turn around the axial threads of one layer, cross the next layer and turn around the axial threads of the new layer encountered. It can thus be said that the layers around which the oblique wires turn are bound layers and the intermediate layers of the crossed layers. During its journey, each oblique wire 19 passes under 6 axial son, then on 6 axial son.

  It is possible not to put all the layers of threads when loading the machine to obtain a thicker reinforcement. It is also possible to put no axial wire to obtain a deformable multilayer braid. It is also possible to cut it axially to obtain a flat ribbon.

Claims (8)

  1) Circular braider for obtaining a multilayer triaxial textile reinforcement characterized by the movement of the spindles in crossed helical grooves.   2) Braider according to claim 1 wherein the helical grooves join two by two in axial grooves.   3) braider according to claim 1 and 2 wherein tubes are arranged between the crossing grooves to introduce axial son between the son from the spindles.   4) braider according to claims 1 and 2 wherein a mechanical device 10 allows movement in one direction of the spindles in a groove and locks in the opposite direction.   5) Braid according to claim 4 wherein the device consists of a roller supported on an inclined ramp to open the passage in one direction and close in the opposite direction.   6) triaxial textile reinforcement made by a braider according to any one of claims 1 to 5 comprising layers of axial son arranged in staggered rows and connected by crossed oblique son characterized by the alternation of bonded layers and crossed layers.   7) A textile reinforcement according to claim 6 wherein the even row surface axial son are partially covered by the oblique son going in one direction and the uneven row surface axial son by the oblique son going in the symmetrical direction.   8) Armature according to claim 6 and 7 wherein each oblique wire passes at the level of the layers it connects under 6 axial son and then 6 axial son and the offset of 2 axial rows of the paths of these son in the thickness .