Device for guiding a fiber texture on an impregnation mandrel, and an associated impregnation mandrel and winding machine

Abstract

A guiding device for guiding a fiber texture on an impregnation mandrel of a winding machine, the device including a first radial spacer for placing facing a first cheekplate of the impregnation mandrel, a second radial spacer for placing facing a second cheekplate of the impregnation mandrel, and a cross-member suitable for supporting the first and second spacers, the cross-member including an adjustment system for adjusting the positions of the first and second spacers and suitable for positioning the first and second spacers apart respectively from the first and second cheekplates of the impregnation mandrel so as to hold a first portion of fiber texture that extends along the first cheekplate pressed against the first cheekplate, and a second portion fiber texture that extends along the second cheekplate pressed against the second cheekplate, without blocking rotation of the impregnation mandrel.

Claims

1. A guiding device for guiding a fiber texture on an impregnation mandrel of a winding machine, the device comprising a first radial spacer for placing facing a first cheekplate of the impregnation mandrel, a second radial spacer for placing facing a second cheekplate of the impregnation mandrel, and a cross-member suitable for supporting the first and second spacers, the cross-member including an adjustment system for adjusting the positions of the first and second spacers and arranged to position the first and second spacers apart respectively from the first and second cheekplate of the impregnation mandrel so as to hold a first portion of fiber texture that extends along the first cheekplate pressed against the first cheekplate, and a second portion of fiber texture that extends along the second cheekplate pressed against the second cheekplate, without blocking rotation of the impregnation mandrel.

2. A guiding device according to claim 1, wherein the adjustment system comprises, for each of the two spacers, a first module arranged to adjust the position of the spacer in a first direction as a function of the thickness of the fiber texture and as a function of the number of turns that the mandrel has already made with the fiber texture.

3. A guiding device according to claim 2, wherein the adjustment system comprises, for each of the two spacers, a second module arranged to adjust the position of the spacer in a second direction both as a function of the shape and the diameter of the impregnation mandrel, and also as a function of the thickness of the fiber texture and of the number of turns that the mandrel has already made with the fiber texture.

4. A guiding device according to claim 1, including an electronic control unit arranged to control automatic actuation of the adjustment system as a function of the winding of the fiber texture on the impregnation mandrel.

5. A guiding device according to claim 1, wherein at least one of the first and second spacers is made of plastics material.

6. A guiding device according to claim 1, wherein, for each of the first and second spacers, said spacer is associated with an additional spacer arranged parallel with said spacer so as to define at least one annular guiding rail portion between the spacer and the additional spacer, the guiding rail being for receiving a portion of fiber texture being wound that is to extend along a corresponding cheekplate while the face of said spacer facing away from said additional spacer holds at least one layer of the portion of fiber texture that has already been wound and that extends along said cheekplate so that it presses against the cheekplate.

7. A guiding device according to claim 6, including two guiding spirals, each arranged to make one complete turn around the central annular wall of the impregnation mandrel that extends between the first and second cheekplates, each guiding spiral having a first end forming said spacer and a second end opposite from the first end forming said additional spacer.

8. A guiding device according to claim 1, wherein the adjustment system comprises, for each of the two spacers, a module arranged to adjust the position of the spacer in a second direction both as a function of the shape and the diameter of the impregnation mandrel, and also as a function of the thickness of the fiber texture and of the number of turns that the mandrel has already made with the fiber texture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention can be better understood on reading the following description given by way of non-limiting indication and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a diagrammatic side view of a machine for winding a fiber texture onto an impregnation mandrel in accordance with the invention, and suitable for including a guiding device of the invention (not shown);

(3) FIGS. 2 and 3 are two fragmentary perspective diagrams of a winding machine in a first embodiment of the invention;

(4) FIG. 4 is a diagrammatic perspective view of an impregnation mandrel in a second embodiment of the invention; and

(5) FIGS. 5 and 6 are perspective views respectively of an impregnation mandrel and of a guiding device in a third embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) The invention is described below in the context of its application to fabricating a gas turbine aeroengine fan casing. In more general manner, the invention applies to fabricating any annular structural part for a turbine engine.

(7) An example of a method of fabricating such a fan casing is described in Document EP 1 961 923, to which reference may be made.

(8) The casing is made of composite material comprising fiber reinforcement densified by a matrix. The reinforcement is made of fibers, e.g. fibers of carbon, glass, aramid, or ceramic, and the matrix is made of polymer, e.g. epoxy, bismaleimide, or polyimide.

(9) Briefly, the fabrication method described in the above-mentioned document consists in making a fiber texture by three-dimensional weaving with take-up in the warp direction onto a drum (referred to below as the take-up mandrel) having a profile that is determined as a function of the profile of the casing that is to be fabricated.

(10) The fiber texture as made in that way is then transferred onto the mandrel of a resin injection mold (referred to below as the impregnation mandrel) of outside profile that corresponds to the inside profile of the casing that is to be fabricated.

(11) With the preform held on the impregnation mandrel, impregnation is then performed using a resin. For this purpose, a shell is applied against the preform and the resin is injected into the mold as constituted in that way. Impregnation may be assisted by setting up a pressure difference between the inside and the outside of the mold in which the preform is located. After impregnation, a step of polymerizing the resin is performed.

(12) The invention, and in particular the guiding device, applies to any type of winding machine having the function of enabling a fiber texture stored on the take-up mandrel to be transferred automatically onto the impregnation mandrel of the resin injection mold, as shown in FIG. 1.

(13) Reference may be made to patent application FR 2 974 026, which describes the structure and the operation of such a machine in detail.

(14) Briefly, the winding machine 10 comprises a frame 12 supporting in particular a take-up mandrel 14 and an impregnation mandrel 16 in accordance with the invention. The mandrels 14 and 16 are removable, i.e. they can be removed from the frame 12.

(15) The take-up mandrel 14 receives the fiber texture 18, e.g. as obtained by three-dimensional weaving. It is carried on a horizontal shaft 20 having one end rotatably mounted on the frame 12 of the winding machine and having its other end coupled to the outlet shaft of an electric motor 22, e.g. an alternating current (AC) electric gear motor.

(16) The assembly constituted by the take-up mandrel 14, its shaft 20, and its electric motor 22 may be mounted in such a manner as to be capable of moving in translation relative to the frame 12 along the axis of rotation 20 of the take-up mandrel 14. This degree of freedom of the take-up mandrel 14 to move in translation enables this mandrel 14 to be put into alignment with the impregnation mandrel 16 prior to winding the fiber texture 18 onto the impregnation mandrel 16.

(17) The impregnation mandrel 16 of the winding machine 10 is for receiving, in superposed layers, the fiber texture 18 that is stored on the take-up mandrel 14. In known manner, it presents a central annular wall 24 having an outside surface of profile that corresponds to the profile of the inside surface of the casing that is to be made, and two cheekplates 26a and 26b of profile that corresponds to the profiles of the outer flanges of the casing at its upstream and downstream ends in order to enable it to be assembled with and connected to other elements.

(18) The impregnation mandrel 16 is carried by a horizontal shaft 28 that is parallel to the axis of rotation 20 of the take-up mandrel 14 and that has one end rotatably mounted on the frame 12 of the winding machine 10 and its other end coupled to the outlet shaft of an electric motor 30, e.g. an AC electric gear motor.

(19) A control unit, e.g. a computer workstation 32, is connected to the electric motors 22, 30 of the two mandrels 14, 16 and it serves to control and monitor the speed of rotation of each mandrel 14, 16. In more general manner, this control unit 32 serves to control all of the operating parameters of the winding machine 10.

(20) With such a machine 10, the fiber texture 18 is wound as superposed layers on the impregnation mandrel 16 while applying an appropriate winding tension to the fiber texture 18. Specifically, a setpoint tension is predefined, in particular as a function of the nature of the fiber texture 18, and it is applied to the mandrel that offers torque opposing winding (generally the take-up mandrel 14) by making use of the computer workstation 32.

(21) By way of example, it may be necessary to wind 4 turns in order to obtain a casing preform having thickness that complies with specifications.

(22) In the invention, the impregnation mandrel 16 has a guiding device 100 for guiding the fiber texture 18.

(23) More precisely, and as shown in FIGS. 2 and 3, the guiding device 100 has two radial spacers 102a and 102b mounted on a cross-member 104.

(24) The first spacer 102a is arranged facing the first cheekplate 26a of the impregnation mandrel 16, and the second spacer 102b is arranged facing the second cheekplate 26b. The first spacer 102a lies in a plane parallel to the first cheekplate 26a and the second spacer 102b lies in a plane parallel to the second cheekplate 26b.

(25) Advantageously, both spacers 102a and 102b are made of Teflon, thereby serving to limit friction and pollution of the fiber texture. Nevertheless, the two spacers could also be made of metal material.

(26) In the first embodiment shown in FIGS. 2 and 3, each of the first and second spacers 102a and 102b possesses the same circularly arcuate shape, forming a crescent-shaped portion.

(27) The circularly arcuate or partially annular shape is easy to make by cutting up an annulus into a plurality of sections.

(28) In the event that a flange being formed by a margin portion 108a or 108b of the already-wound fiber texture 18 has already drooped at least partially onto the portion 180 of the fiber texture 18 that is wound on the central annular portion 24, the half-crescent shape enables the flange to be stood up progressively.

(29) In FIGS. 2 and 3, the already-wound portion of the fiber texture 18 is referenced 180, i.e. the portion that is in contact with the impregnation mandrel 16, and the portion of the fiber texture 18 that has not already been wound is referenced 181, i.e. the portion situated between the take-up mandrel 14 and the impregnation mandrel 16.

(30) The spacers may also be rectangular in shape and positioned so as to extend at least in part along the portion 181 of the fiber texture 18 between the impregnation mandrel 16 and the take-up mandrel 14.

(31) The cross-member 104 includes adjustment means 106 adjusting the positions of the first and second spacers 102a and 102b. The adjustment means 106 are coupled to the first spacer 102a via a first bracket 104a and to the second spacer 102b via a second bracket 104b.

(32) The adjustment means 106 are configured to position the first spacer 102a and the second spacer 102b respectively so as to be spaced apart from the first cheekplate 26a and the second cheekplate 26b of the impregnation mandrel 16 so as to hold a first portion 108a of the fiber texture 18 that extends along the first cheekplate 26a pressing against the first cheekplate 26a, and a second portion 180b of the fiber texture that extends along the second cheekplate 26b pressing against the second cheekplate 26b, while not blocking rotation of the impregnation mandrel 16.

(33) When assembling the guiding device 100 on the impregnation mandrel 16 of the winding machine 10, the first and second spacers 102a and 102b are spaced apart from the first and second cheekplates 26a and 26b respectively by a distance that serves to avoid the margin portions 180a and 180b of the portion 180 of the fiber texture 18 that has already been wound onto the impregnation mandrel 16 drooping between two consecutive turns of the fiber texture 18 on the impregnation mandrel 16 so as to pass under the portion 181 of the fiber texture 18 coming into contact with the impregnation mandrel 16 in order to be wound.

(34) For each of the two spacers 102a and 102b, the adjustment means 106 include a respective horizontal movement module referenced 108a and 108b. Each horizontal movement module 108a, 108b is configured to move the spacer 102a, 102b with which it is associated in a direction that is parallel to the axis of rotation 28 of the impregnation mandrel 16.

(35) The first modules 108a and 108b thus serve to adjust the horizontal positions of the two spacers 102a and 102b as a function of the intrinsic thickness of the fiber texture 18 and as a function of the number of turns that the impregnation mandrel 16 has already made with the fiber texture 18. The spacers 102a and 102b are thus moved horizontally as a function of the thickness of the flanges formed by the margin portions 180a and 180b of the portion 180 of the fiber texture 18 that has already been wound so as to extend along the cheekplates 26a and 26b.

(36) The adjustment means 106 also include respective radial movement modules referenced 110a and 110b for each of the two spacers 102a and 102b. Each radial movement module 110a, 110b is configured to move the spacer 102a, 102b with which it is associated in a direction parallel to the planes in which the corresponding cheekplates 26a, 26b extend.

(37) The radial movement modules 110a and 110b thus serve to adjust the radial positions of the two spacers 102a and 102b as a function both of the intrinsic thickness of the fiber texture 18 together with the number of turns that the impregnation mandrel 16 has already made with the fiber texture 18, and also as a function of the shape and the diameter of the impregnation mandrel 16.

(38) The spacers 102a and 102b are thus moved radially as a function of the thickness of the central portion of the preform formed by the portion extending between the margin portions 180a and 180b of the portion 180 of the already-wound fiber texture 18. Before starting winding, they are also positioned radially as a function of the diameters of the central annular portion 24 of the section situated in the planes in which the spacers 102a, 102b extend parallel to and in the proximity of the corresponding cheekplate 26a, 26b. This is done independently for each of the two spacers 102a and 102b.

(39) While the fiber texture 18 is being wound on the impregnation mandrel 16, the spacers 102a and 102b are also moved radially by means of the radial movement modules 110a and 110b. The first and second spacers 102a and 102b can thus be moved away from the central annular wall 24 of the impregnation mandrel 16 for each new turn so as to accommodate any variation in the diameter of the central annular wall 24 along the axis of rotation 28.

(40) The guiding device 100 also has an electronic control unit connected to the adjustment means 106 so as to control actuation of the horizontal movement modules 108a, 108b and of the radial movement modules 110a, 110b automatically as a function of the winding of the fiber texture 18 on the impregnation mandrel 16.

(41) The electronic control unit is coupled to the control unit 32 of the impregnation mandrel 16 in particular so as to receive information about the number of turns of the mandrel 16.

(42) FIG. 4 is a diagrammatic perspective view of an impregnation mandrel 16 in a second embodiment of the invention.

(43) This second embodiment differs from the first embodiment in that the guiding device, now referenced 100, has a first additional spacer 122a associated with the first spacer 102a, and a second additional spacer 122b associated with the second spacer 102b.

(44) Each of the two additional spacers 122a and 122b is arranged parallel to the spacer 102a and 102b with which it is associated so as to define an annular guiding rail portion 130a, 130b between the spacer 102a, 102b and the additional spacer 122a, 122b.

(45) The guiding rail portion 130a, 130b is arranged around the zone where the fiber texture 18 comes into contact with the second annular wall 24 of the impregnation mandrel 16. The guiding rail portion 130a, 130b is thus configured and arranged to receive a margin portion 181a, 181b of the fiber texture 18 that is to extend along a corresponding cheekplate 26a, 26b while the spacer 102a, 102b of the guiding rail portion 130a, 130b holds at least one margin portion layer 180a, 180b of the already-wound fiber texture 18 that extends along said cheekplate 26a, 26b pressed thereagainst. This makes it possible to initiate the radial, or vertical, orientation of the margin portions 181a, 181b of the portion 181 of the fiber texture 18 prior to being wound onto the impregnation mandrel 16.

(46) The spacer 102a, 102b and the additional spacer 122a, 122b of a guiding rail portion 130a, 130b are secured to each other, e.g. by connecting bars or else they are made integrally out of an upside-down piece of channel-section. This thus makes it possible to move the entire guiding rail portion 130a, 130b as a whole when using the adjustment means 106.

(47) FIGS. 5 and 6 are diagrammatic perspective views respectively of an impregnation mandrel 16 in a third embodiment of the invention and of the guiding device 100 in this third embodiment.

(48) This third embodiment differs from the second embodiment in that the guiding device, how referenced 100, has two guiding spirals, each making one complete turn around the central annular wall 24 of the impregnation mandrel 16. Each guiding spiral has a first end 141a, 141b forming the spacer 102a, 102b and a second end 142a, 142b, opposite from the first end 141a, 141b, forming the additional spacer 122a, 122b. The spacer 102a, 102b and the additional spacer 122a, 122b of each spiral together form an annular guiding rail portion 130a, 130b.

(49) In this embodiment, the radial movement modules 110a, 110b are each configured to act along an axis that is configured to modify the diameter of the annulus formed by the spiral by moving the first end 141a, 141b and the second end 142a, 142b towards each other or away from each other while keeping the horizontal separation distance between them constant, i.e. the distance in a direction orthogonal to the plane in which the spiral extends.

(50) The invention is not limited to the embodiments described. Winding machines provided with impregnation mandrels of the invention thus provide guidance for the flange of the preform that is being formed that makes it possible to master the positions of the flanges of the fiber texture against the cheekplates of the impregnation mandrel immediately before taking on an additional turn.