Needling system for producing textile preform

Abstract

To provide a new, more general-purpose needling system.SOLUTION: There is provided a needling system 100 for producing a textile preform, the needling system 100 comprising: a needling head 110; a robotic arm 120 movable in multiple degrees of freedom, carrying the needling head and configured so as to move the needling head following predetermined trajectories and orientations; a textile strip feeding device 130 mounted on the needling head and configured to deposit the textile strip on a support and to cut the textile strip; and a monitoring unit 140 configured to control the robotic arm, the actuation of the needling head and the deposition of the textile strip according to a predefined program for producing the textile preform.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the manufacture of fiber preforms by needling, and more particularly to a needling system for the manufacture of fiber preforms. [Background technology]

[0002] The fibre preform forms the reinforcement of the organic or ceramic matrix composite: it forms the skeleton for the material that absorbs most of the mechanical forces, this skeleton being reinforced and protected by the organic or ceramic matrix of the composite.

[0003] The production of a fibre preform by needling consists of superimposing textile plies and connecting them to one another by needling, in particular by transferring fibres from one ply to another in the Z direction, i.e. along the thickness of the preform, thus creating a mechanical connection between them in this direction.

[0004] The current needling system is therefore capable of producing axisymmetric preforms whose geometry is a through-gap geometry. The current needling means is programmed to follow a specific trajectory so as to needle the preform according to some criteria, for example the density of the Z-fibers. The current programs are specific to the machine used and cannot be used interchangeably. Furthermore, the current programs are capable of following axisymmetric profiles based on an adaptive mode, which makes it possible to correct the position of the machine as a function of the excess thickness encountered during needling.

[0005] However, some preforms, such as atmospheric re-entry thermal protection preforms, may have a spherical cap shape (non-through shape) or a non-axisymmetric shape, and current needling means are not adapted to this type of shape.

[0006] It is therefore desirable to have a new, more versatile needling system that allows for needling preforms whose geometry is non-axisymmetric and / or non-through, or whose geometry is axially symmetric or non-axisymmetric, through or through, and that is capable of needling fiber pieces without trajectory restrictions, whose trajectory is fully parameterizable.

[0007] It is also desirable to have a new solution for programming the needling means that can be used on several needling machines and that can accommodate any type of preform geometry, including non-axisymmetric and non-through geometries. Summary of the Invention

[0008] The present invention relates to a needling system for making a fiber preform, the system comprising: This needling system is A needling head; a robotic arm movable with several degrees of freedom, the robotic arm being configured to carry a needling head and to move the needling head according to a predetermined trajectory and direction; a fiber piece feeder attached to the needling head, the fiber piece feeder configured to deposit the fiber piece on a support and cut the fiber piece; and a monitoring unit configured to control a robot arm, an actuation of the needling head and a deposition of the fiber pieces according to a predetermined program for producing the fiber preform.

[0009] The present invention proposes a modular needling head, since the robot arm can accommodate complex preform geometries. The needling system of the present invention therefore makes it possible to manufacture preforms with non-through or non-axisymmetric shapes, such as for example spherical caps. The needling system of the present invention also makes it possible to parameterize custom fiber piece trajectories without trajectory restrictions.

[0010] Moreover, the presence of a fiber piece feeder on the needling head makes it possible to imagine the deposition of a piece on a previously deposited piece and its needling in a single system. This allows the deposition of fiber pieces in various orientations with thin or thick thicknesses and also allows the automation of the placement of the fiber pieces by a robot arm and a monitoring unit. This also allows without fixed additions between the pieces or other elements that could contaminate the pieces forming the preform and disrupt the fiber / matrix connection during the densification of the needled preform, since the pieces are held together between needlings by the partial lateral transfer of the fibers coming from the deposited pieces. In other words, in the case of the present invention, it is a mechanical and not a chemical bond of the fiber pieces, unlike the methods of the prior art (such as the Automatic Tape Laying ATL and Automatic Fiber Placement AFP techniques) that allow the deposition and holding of fiber pieces and / or threads.

[0011] According to one particular feature of the invention, the fiber piece supplying device comprises an adjustment system, e.g. a braking system, configured to adjust the tension of the fiber piece when it is placed on the support according to predetermined instructions or according to one particular point of the trajectory.

[0012] According to another particular feature of the invention, the fibre piece feeder comprises a system for guiding the fibre pieces.

[0013] According to another particular feature of the invention, the fibre piece guiding system comprises a deflection roller which is adjustable according to at least one spherical three-dimensional reference frame.

[0014] According to another particular feature of the invention, the fiber piece feeder comprises an adjustment system in the lateral position.

[0015] This allows for more accurate guidance of the piece and its placement on the support, which can be particularly useful when spooling is performed, as shown in FIG. 3, by allowing slight translation of the piece to compensate for misalignment that may occur during deposition.

[0016] Another object of the invention relates to a method for producing a fibre preform by needling carried out by means of a needling system according to the invention on a support tool whose shape corresponds to the shape of the fibre preform to be produced, the method comprising depositing and needling fibre pieces on the support tool.

[0017] This method allows for the fiber pieces to be directly needled into the shape of the final preform.

[0018] According to one particular feature of the invention, the support tool has a non-axisymmetric and / or non-through shape.

[0019] This makes it possible to produce preforms having complex shapes.

[0020] According to another particular feature of the invention, the fiber pieces are deposited on a support tool and needled without trajectory constraints.

[0021] According to another particular feature of the invention, the needling head forms an angle between -85° and 85° with respect to a direction perpendicular to the tangent plane of the support tool during all or part of the deposition and needling of the fibre pieces.

[0022] This allows the fibers to be transported during needling in a direction perpendicular or non-perpendicular to the tangent of the preform, i.e. to the tangent of the supporting tool. The fact that it is not limited to the perpendicular direction allows the fibers to be transported in multiple directions to optimize the thermomechanical properties and wear resistance of the final fiber preform according to the application for which the part containing this preform is intended.

[0023] The invention also relates to a method for determining a program of displacements and directions of a needling head for producing a fiber preform by needling a fiber piece on a support tool, the method comprising the steps of: The method comprises: determining a set of three coordinates of a pass point of the needling head as a function of the position of the fiber along the Z axis in the fiber preform to be produced, its local shape and a predetermined minimum distance to be met between the needling head and the support tool or the fiber preform, so as to make it possible to avoid collisions with the support tool or the fiber preform; determining (420) an angular orientation (α, β, γ) of the needling head for each pass point as a function of the angular orientation of the fiber pieces and Z-fibers in the fiber preform to be made.

[0024] According to the method of the invention, the pass point and the direction of the needling head are determined before starting the needling, taking into account the complexity of the geometry of the preform to be made and the density and direction of the Z-fibers, while ensuring that the support tool and the preform do not collide with the needling head. Therefore, the program is not linked to a specific machine, but can be adapted to all machines and desired preform geometries. This therefore allows versatile production of fiber preforms by needling according to the needs and desired thermostructural properties, such as, for example, the density and direction of the Z-fibers.

[0025] Furthermore, the number of pass points is adapted to reduce the calculation time and the program itself by taking into account the complexity of the geometry of the preform to be produced: for example, if a region has a small local radius of curvature, the number of pass points will be greater in this region than in another region with a larger radius of curvature.

[0026] The determination of the three coordinates of the pass point of the needling head and the angular orientation of the head can result from one or several calculations, or several parameters (coordinates or angles) can be predetermined.

[0027] The determination of the three coordinates of the pass point of the needling head can also be performed as a function of the width of the fibre pieces and their possible overlap.

[0028] The angular orientation of the needling head can be determined relative to a normal to the local geometry.

[0029] According to one particular feature of the invention, the support tool is rotated about a rotation axis and the method comprises a mathematical projection of the determined pass-through point on a reference plane that is fixed or movable with respect to the support tool and includes the rotation axis of the support tool.

[0030] This allows the three coordinates (x, y, z) to be converted into polar coordinates (r, θ, z) and therefore makes it easier to implement the coordinates of the pass-point of the needling head in the needling machine.

[0031] According to another particular feature of the invention, the method further comprises determining the local displacement speed of the needling head as a function of the Z fiber content in the relevant area of ​​the preform to be made and the rotation of the support tool.

[0032] This makes it possible to adapt the needling density as a function of the preform geometry, thus increasing, decreasing or keeping this density constant according to the local geometric features of the preform.

[0033] According to another particular feature of the invention, the method further comprises creating a mesh of the geometric shape of the fibre preform to be created, all the determinations of the three coordinates (x, y, z) being carried out with respect to this mesh.

[0034] This mesh allows a more accurate mathematical use of the geometry of the preform and then applies all the operations that determine the pass points and the angular orientation of the needling head, but also allows the number of pass points to be discretized as a function of the geometric complexity of the preform to be made.

[0035] According to another particular feature of the invention, the support tool has a non-axisymmetric and / or non-through shape.

[0036] This allows the fabrication of fiber preforms with complex geometric shapes.

[0037] Another object of the invention is a method for producing a fiber preform by needling, comprising determining a program of displacements and directions of a needling head according to the invention and producing by needling a fiber preform on a support tool whose shape corresponds to the shape of the fiber preform to be produced using the needling head programmed according to the determined program.

[0038] Other characteristics and advantages of the invention will become apparent from the description given below, with reference to the attached drawings, which show exemplary, non-limiting embodiments. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 shows, diagrammatically and partially, a needling system according to one embodiment of the present invention. [Diagram 2]FIG. 2 partially depicts a deposition and needling head according to one embodiment of the present invention. [Diagram 3] FIG. 3 shows, diagrammatically and partially, the needling head of FIG. 2, in particular the orientation of the needles relative to the deposited pieces. [Figure 4] FIG. 4 illustrates a flow chart of a method for determining a needling head displacement and orientation program, according to one embodiment of the present invention. [Figure 5A] FIG. 5A illustrates, in a schematic and partial manner, step 409 of the method described in FIG. [Figure 5B] FIG. 5B illustrates, in a schematic and partial manner, step 410 of the method described in FIG. [Figure 5C] FIG. 5C illustrates, in a schematic and partial manner, step 420 of the method described in FIG. [Figure 5D] FIG. 5D illustrates, in a schematic and partial manner, step 421 of the method described in FIG. [Figure 6] FIG. 6 depicts a flow chart of a method for producing a fiber preform by needling, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] FIG. 1 illustrates, in schematic and partial form, a needling system 100 according to one embodiment of the present invention for making a fiber preform.

[0041] The system 100 comprises a needling head 110 having a fiber piece feeder 130 attached thereto, a robotic arm 120 movable in several degrees of freedom and carrying the needling head 110, and a monitoring unit 140.

[0042] The robotic arm 120 is configured to move the needling head 110 according to a predetermined trajectory and direction.

[0043] The feeder 130 is configured to deposit pieces of fiber onto a support and to cut the deposited pieces of fiber.

[0044] The monitoring unit 140 is configured to control the operation of the robot arm 120, the needling head 110 and the deposition of the fiber pieces according to a predetermined program for producing a fiber preform.

[0045] Figure 2 partially depicts a needling head 210 carrying a fiber piece 233 feeder 230 according to an embodiment of the invention during the production of a fiber preform, in particular during the deposition and needling of a fiber piece 234 on a support tool 250. Figure 3 depicts a schematic diagram of Figure 2, in particular the orientation of the needles of the needling head relative to the deposited piece, and the reference numbers used for these two figures represent the same things.

[0046] The fiber piece 233 supplying device 230 includes a cassette support 232 and a cassette 231 that contains the fiber piece 233 and is disposed on the cassette support 232. The cassette 231 has a width that substantially corresponds to the width of the fiber piece 233 wound on the cassette 231.

[0047] The fiber piece 233 may be a piece or sheet of yarn, such as a yarn or set of yarns, a fabric, a multidirectional nonwoven (or non-crimp fabric, NCF), a braid, or a nonwoven web, whose properties are useful, for example, as a fiber reinforcement in a preform that constitutes a composite material.

[0048] The needling head 210 comprises a number of needles 211 mounted on a needle plate, which make it possible to needle a piece of fibre 234 just deposited on a support tool 250, which is thus needled with a previously deposited piece of fibre 235 in order to produce a fibre preform. In order to obtain the desired geometric shape, the deposition and needling are carried out on a support tool 250 having a shape corresponding to the shape of the preform to be produced. In order to produce a non-axisymmetric preform, the support tool 250 therefore has a non-axisymmetric shape. The support tool 250 is also movable in rotation about an axis, for example to facilitate the movement of the robot arm and the needling head 210.

[0049] The needling head 210 also comprises a stripper 212 comprising a plate with a number of perforations. The plate has an inner and an outer surface, the outer surface of the plate being on the side of the support tool 250. A needle plate faces the inner surface of the stripper, and the needles 211 are aligned with the perforations present on the plate of the stripper 212. During needling of the fibre pieces 234, the needles 211 move alternately from a retracted position in which they do not protrude from the outer surface of the plate of the stripper 212 to a deployed position in which they protrude from the outer surface of the plate in order to penetrate the fibre pieces 234. A fibre piece 233 feeder 230 is fixed to the needling head 210 in a transverse direction to the perforation plate of the stripper 212 that is intended to be traversed by the needles 211.

[0050] The fiber piece 233 feeder 230 may be equipped with a fiber piece guiding system 270 and / or a braking system, making it possible to adjust the tension of the pieces 234 during deposition of the fiber pieces 233. The guiding system 270 may be fixed on the surface of the stripper 212 or on the needling head 210, ideally as close as possible to the surface of the stripper 210 carrying the feeder 230.

[0051] Furthermore, the fiber piece guidance system can be provided with deflection rollers 271 that are adjustable according to a three-dimensional reference frame, in particular a spherical reference frame. These rollers 271 are, for example, adjustable in translation along the direction of the width of the pieces 234 and in rotation along two axes, so that the angle of the pieces 234 relative to the support tool 250 can be adjusted. By means of these deflection rollers 271, the pieces 234 can be guided from the cassette 231 onto the deposition surface of the support tool 250. The width of these rollers 271 can be adapted to the width of the pieces 234.

[0052] Whatever the embodiment, the fibre piece feeder may be configured to store fibre pieces with a width between 5mm and 500mm, preferably between 5mm and 200mm.

[0053] Whatever the embodiment, the needling head can be configured for different needle plate widths (support carrying the needles) and / or different stripper widths, for example to be able to needle fiber pieces with a width between 5 mm and 500 mm, preferably between 5 mm and 200 mm. The needle plate and the stripper can also be removable from the needling head in order to adapt it to the geometry of the preform to be made and / or to the width of the fiber pieces to be needled.

[0054] Whatever the embodiment, the needling head, and in particular the needles, during all or part of the deposition and needling of the fibre pieces, make a variable angle α (as shown in FIG. 3) with respect to an axis 270 perpendicular to the tangent plane 260 of the support tool 250, for example between −85° and 85°, preferably between −30° and 30°. More generally, the needling head is adjustable along all directions about this perpendicular axis 270. This allows the fibre pieces to be needled in different directions, for example obliquely or at an angle, to transfer the fibres in a particular direction, imparting certain thermo-mechanical and / or wear-resistant properties to the final part.

[0055] Whatever the embodiment, the needling head can be programmed by a robotic arm to move and orient itself around the support tool for depositing and needling the fiber pieces, thus the displacement and orientation program of the needling head comprises the pass-through points and angular orientation of the needling head around the support tool.

[0056] To avoid damage to the preform, the pass points can be determined as a function of the position of the Z fibers in the fiber preform to be produced, as a function of the local radius of curvature of the fiber preform, and as a function of the minimum distance to be met between the needling head and the supporting tool or preform. The angular orientation of the needling head can be determined for each pass point as a function of the angular orientation of the Z fibers in the preform to be produced.

[0057] Furthermore, to facilitate programming of the needling head, and in the case where the support tool rotates on its own, the way-points can be expressed in terms of the distance between the needling head and the support tool. To do so, it is possible to project the way-points onto a reference plane fixed relative to the support tool, and thus to program the head according to the distance between the needling head and the support tool.

[0058] Whatever the embodiment, it is also possible to drive the pressure of the stripper by servo control. In particular, the stripper can exert pressure on the strip to hold it in a predetermined position when the needle exits.

[0059] Whatever the embodiment, it is also possible to servo-drive the needling head as a function of the stripper pressure and / or as a function of the stripper position if the stripper is floating and / or as a function of the needle position.

[0060] It is also possible to servo-drive the position of the robot as a function of the stripper pressure and / or as a function of the stripper position if the stripper is floating and / or as a function of the needle position.

[0061] It is also possible to servo-drive the position of the support as a function of the stripper pressure and / or as a function of the stripper position if the stripper is floating and / or as a function of the needle position.

[0062] Figure 4 represents a flow chart of a method 400 for determining the displacement and orientation program of a needling head according to an embodiment of the present invention, and Figures 5A, 5B, 5C and 5D represent different steps of this same method, which will therefore be described with reference to Figures 4, 5A, 5B, 5C and 5D.

[0063] The method 400 is a method for determining a program of displacement and orientation of a needling head 530 for making a fiber preform 500 by needling a fiber piece on a support tool 505. The method 400 comprises determining 410 a set of three coordinates (x, y, z), (x1, y1, z1), (x2, y2, z2), (x3, y3, z3) of pass points 520, 521, 522, 523 of the needling head 530. For the sake of clarity, only a few points are visible in the figure, but the number of pass points is not limited to these four points. Moreover, the position of these points visible in FIG. 5B does not mean that the point 520 (or the point 522) is determined first before the point 521 (or the point 523). In general, the sequence of determination of the different pass points of the head follows the unwinding and needling of the fiber piece on the support tool.

[0064] The passing points 521, 522, 523 are a function of the position of the fibers along the X-axis, the Y-axis and the Z-axis, in particular along the Z-axis in the fiber preform 500 to be produced, as well as a function of the local geometry of the preform 500, e.g. its local radius of curvature, and as a function of the minimum distance d minThis shortest distance d min is the distance at which a collision between the needling head 530 and the preform 500 to be made or the supporting tool 505 can be avoided. min is predetermined by the user. This step 410 is shown in FIG. 5B.

[0065] The number of pass points 520, 521, 522, 523 may depend on the complexity of the preform 500 to be made. For example, if the preform has a complex shape (e.g., a non-axisymmetric shape), the number of pass points will generally be greater than the number of pass points for a preform with a simple shape (e.g., an axisymmetric shape).

[0066] The method 400 then comprises a step 420 of determining an angular orientation of the needling head 530 relative to each pass point 520, 521, 522, 523 determined in step 410 as a function of the angular orientation of the Z fibers in the fiber preform 500 to be produced. This step 420 is illustrated in Fig. 5C. In this step 420, for example, an angle α formed between the needling head 530 and the Z axis of the pass point 520 and / or an angle β formed between the needling head 530 and the X axis of the pass point 520 is determined. More specifically, in the example of determining the angle α, the angle α is formed between the Z axis and the direction of the head, which corresponds to the direction 560 of the Z fibers relative to this pass point 520.

[0067] The method 400 may also comprise a step 409 of creating a mesh 510 of the geometry of the fibre preform 500 to be created. A determination 410 of all three coordinates (x, y, z) of the pass-points is then carried out for this mesh 510. This step 409 is illustrated in Figure 5A. This allows to simplify the geometry of the preform 500 and make it easier to determine the pass-points 520.

[0068] When the support tool 505 rotates about the rotation axis 580, the method 400 may also comprise a step 421 of projecting the pass-through point 520 determined in step 410 into a reference plane 540, which may be fixed or movable with respect to the support tool 505 and may comprise the rotation axis 580 of the support tool 505. The reference plane 540 may be, for example, a plane (YZ) or a plane (XY) or a plane (λ). This allows the polar coordinates (r, θ, z) of the pass-through point 520 to be determined. This step 421 is illustrated in FIG. 5D.

[0069] The method 400 may also comprise determining the local displacement speed of the needling head 530 as a function of the possible displacement of the support tool 505 and as a function of the Z-fiber content in the relevant area of ​​the preform 500 to be produced. For example, if the support tool 505 is rotating during needling, it may be interesting to vary the displacement speed of the needling head 530 between the pass points 520 along the radius of curvature of the geometry of the preform 500 to be produced in order to best adapt the Z-fiber content according to this radius of curvature.

[0070] FIG. 6 depicts a flow chart of a method 600 for producing a fiber preform by needling, according to one embodiment of the present invention.

[0071] The method 600 first comprises determining 610 a program of displacement and orientation of a needling head according to the invention, thus, for example according to the method described above, and then manufacturing 620 a fiber preform by needling on a support tool. The support tool has the same shape as the inner surface of the preform to be made. The needling is carried out using a needling head programmed according to the program determined in step 601.

[0072] The needle system used in the production is e.g. a needling head programmed according to the determined program; a robotic arm movable in several degrees of freedom, the robotic arm carrying a needling head and configured to move the needling head according to a trajectory and direction predetermined in a displacement and direction program; a fiber piece feeder mounted on the needling head and configured to deposit the fiber piece onto a support tool and cut the fiber piece; The robot arm includes a monitoring unit configured to control the actuation of the needling head and the deposition of said fiber pieces according to a program of displacement and direction of the needling head.

[0073] The support tooling used to program the displacement and orientation of the needling head and to manufacture the fiber preforms may have non-axisymmetric and / or non-penetrating shapes, which may produce preforms with non-axisymmetric and / or non-penetrating shapes, for example, that may form atmospheric re-entry thermal protection preforms.

[0074] The support tool can also rotate in both directions about a rotation axis during needling to facilitate the displacement of the robot arm. In this case, the monitoring unit can drive the rotation of the support tool. For example, the monitoring unit can control the rotation axis and / or the rotation speed of the support tool.

[0075] The expression "comprised between... and..." must be understood as inclusive.

Claims

1. A method (400) for determining a program for the displacement and direction of a needling head (530) in order to produce a fiber preform (500) by needling a fiber piece on a support tool (505), The above method (400) is, To enable avoidance of collision with the support tool (505) or the fiber preform, the position of the fibers along the Z-axis in the fiber preform (500) to be manufactured, its local shape, and a predetermined minimum distance (d) that is filled between the needling head and the support tool (505) or the fiber preform. ｍｉｎ (410) As a function of ), determine a set of three coordinates (x, y, z), (x1, y1, z1), (x2, y2, z2), (x3, y3, z3) of the points (520, 521, 522, 523) that the needling head (530) passes through (520, 521, 522, 523), The method comprises at least determining the angular direction (α, β, γ) of the needling head with respect to each passing point as a function of the angular direction of the fiber pieces and Z fibers in the fiber preform to be manufactured (420), The method further comprises determining the local displacement velocity of the needling head as a function of the Z fiber content in the relevant region of the fiber preform to be manufactured and the rotation of the support tool.

2. The support tool rotates around the axis of rotation (580), The method according to claim 1, wherein the method comprises a mathematical projection (421) of the passing point, which is fixed or movable with respect to the support tool and determined on a reference plane (540, λ) including the axis of rotation.

3. The method according to claim 1, further comprising (409) producing a geometric mesh (510) of the fiber preform, wherein all three coordinates (x, y, z) are determined relative to this mesh.

4. The method according to claim 1, wherein the support tool has a non-axisymmetric shape and / or a non-through shape.

5. In a method for producing fiber preforms by needling (600), The above method (600) is, Determining a program for the displacement and direction of the needling head according to any one of claims 1 to 4 (610), A method comprising (620) needling a fiber preform on a support tool whose shape corresponds to the shape of the fiber preform to be manufactured, using a needling head programmed according to a determined program.

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