Tool for moulding parts with circumferential compacting from the outer surface of a preform

Abstract

The invention relates to a mould (10) for producing a part with a longitudinal axis (Y-Y'), comprising a base (30) extending along a plane (P) perpendicular to the axis (Y-Y'), a belt (40) extending parallel to (P), a core (50) and a cover (90) extending parallel to (P). The belt (40) comprises n removable guide shims (70) and n removable closure shims (80), with n ≥ 2, the guide shims (70) and the closure shims (80) each forming a sector of an annular disc on the axis (Y-Y'), and each closure shim (80) being located between two guide shims (70). The guide shims (70) and the closure shims (80) each have an inner radial face (74, 84) and two side faces (71, 72, 81, 82) provided at the interface located between two adjacent removable shims (70, 80). The two side faces (81, 82) of each closure shim (80) are parallel.

Description

Tooling for molding parts with circumferential compaction from the outer face of a preform TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of molding parts of revolution or parts with oblong or oval profile in composite material by resin transfer.

[0002] The present invention relates to a tool for molding such parts and comprising a base, a cover and a set of wedges providing compaction support on a preform positioned inside a belt and intended to be impregnated with resin. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] For resin transfer molding, and as shown in [Fig. 1], it is known to use a 10' mold comprising a 40' belt and a 50' core that define a molding volume in which a 20' preform can be impregnated with resin. This 20' preform, wrapped around the 50' core, is usually made of fibers and requires compaction before resin injection.

[0004] During the molding of parts of revolution or parts with oblong or oval profiles, circumferential compaction of the preform 20' can be carried out from its external radial face 24'. As shown in [Fig. 1] and [Fig. 2], the belt 40' usually comprises several identical shims 60' which are placed against each other by sliding them radially and horizontally in a plane P', compacting the preform 20' locally each time.

[0005] Due to the shape of the profile of the 60' spacers currently used, when they are placed around the 20' preform, it is common for the preform to be pinched between two 60' spacers at the pinching and wedging zones C shown in the figures. Indeed, when a first spacer is placed, slightly compacting the preform, and a second spacer adjacent to the first is then placed, it comes into contact with the preform before the first spacer, and the preform is then generally pinched between the first and second spacers.

[0006] Before injecting the resin into the mold, however, it is necessary to ensure that the preform is neither creased, nor folded, nor jammed by the shims.

[0007] There is therefore a need for a mold capable of achieving circumferential compaction from the external face of a preform and which is not likely to cause pinching of the preform while also ensuring that the preform is neither pleated nor folded by the shims. SUMMARY OF THE INVENTION

[0008] The invention offers a solution to the problems mentioned above, by providing a molding tool comprising two types of shim to be put in place in a defined order so that when one shim is put in place adjacent to another, it first comes into contact with the neighboring shim before coming to rest on the preform.

[0009] One aspect of the invention relates to a mold for producing a part with longitudinal axis Y-Y' by molding and comprising a base extending along a principal plane P perpendicular to the axis Y-Y', an annular belt extending along a plane parallel to the plane P, a core, a cover extending along a plane parallel to the plane P, said mold being characterized in that: the belt comprises a set of n removable guide wedges and n removable closing wedges, with n > 2, the guide and closing wedges each forming a sector of an annular disk on the axis Y-Y', and each closing wedge being located between two guide wedges within the belt; the guide and closing wedges each have an internal radial face and two lateral faces provided at the interface located between two adjacent removable wedges; the two lateral faces of each closing wedge are parallel.

[0010] Initial support and compaction of the preform is advantageously achieved by installing guide shims, which prevent the preform from wrinkling or folding. Next, the placement of the closing shims between two guide shims, by sliding them radially inward, completes the support and circumferential compaction of the preform against the core. Sliding the lateral faces of the closing shims along the lateral faces of the adjacent guide shims advantageously guides the placement of the closing shims and completes the compaction of the preform without this The last one is not pinched between the shims. During mold closure, bringing the lateral faces of the closing shims into contact with the lateral faces of the guide shims before the closing shims contact the preform advantageously prevents damage to the preform and, above all, prevents it from being pinched between two shims. The mold according to the invention thus allows for complete forming of the preform, by circumferential compaction from its outer face, without pinching it.

[0011] According to one aspect of the invention, in the closed position of the mold, the belt rests on the base, the core is centered on the Y-Y' axis, the cover rests on the belt and on the core, and each closing wedge is located between two guide wedges.

[0012] According to another aspect of the invention, the internal radial face of each guide wedge has an area S7 and the internal radial face of each closing wedge has an area S8, with S7 < S8.

[0013] According to a further aspect of the invention, 0.4 < S7 / S8 < 1.

[0014] According to one aspect of the invention, the internal radial face of each guide wedge has an area S7 which represents 30% to 50% of the total area of ​​the internal radial face of the belt.

[0015] Circumferential compaction of the forming preform is more effective in preventing its potential bulging when the contact surface of a shim with the preform is larger for closing shims than for guide shims. Indeed, the mold according to the invention advantageously reduces the amount of material subject to bulging that is pushed away by the guide shims and that could cause buckling of the preform.

[0016] According to another aspect of the invention, the lateral faces of the guide wedges and the closing wedges are flat, which in particular simplifies their design and installation, and advantageously allows them to be interchangeable.

[0017] According to a further aspect of the invention, in the closed position of the mold, the lateral faces of the closing shims are parallel to the lateral faces of the guide shims, which notably provides an absence of play. Indeed, the The presence of play between the guide shims and the closing shims is likely to cause pinching of the preform, as illustrated in [Fig. 1] and [Fig. 2].

[0018] According to one aspect of the invention, the guide wedges are identical to each other.

[0019] According to another aspect of the invention, the closing wedges are identical to each other.

[0020] Using identical shims for the same type of removable shims greatly facilitates the design and manufacture of the mold, while reducing its cost.

[0021] According to a further aspect of the invention, the number n of guide or closing shims is between 4 and 8 and preferably equal to 6. Thus, the mold according to the invention preferably comprises between eight and sixteen shims in total, and twelve shims preferably.

[0022] Another aspect of the invention relates to a molding process for producing a part made of composite material by impregnating a preform with resin and using a mold according to any one of the preceding claims, characterized in that said process comprises the following steps: positioning the base; positioning a preform around the core; positioning the preform and the core on the base; positioning the guide shims by sliding them on the base along a plane parallel to plane P and compacting the preform between the inner radial face of the guide shims and the core; positioning the closing shims by sliding them on the base along a plane parallel to plane P, each closing shim being located between two adjacent guide shims, and compacting the preform between the inner radial face of the closing shims and the core;placement of the cover on the core and the band formed by the removable shims, the band and the core delimiting a molding volume; injection of resin in liquid form into the molding volume.

[0023] A further aspect of the invention relates to a molding process for producing a part made of composite material by impregnating a preform with resin and using a mold according to any one of the preceding claims, characterized in that said process comprises the following steps: placement of the base; placement of the core; placement of a preform on the base around the core; placement of the guide shims by sliding them on the base along a plane parallel to plane P and compaction of the preform between the inner radial face of the guide shims and the core; placement of the closing shims by sliding them on the base along a plane parallel to plane P, each closing shim being located between two adjacent guide shims, and compaction of the preform between the inner radial face of the closing shims and the core;placement of the cover on the core and the band formed by the removable shims, the band and the core delimiting a molding volume; injection of resin in liquid form into the molding volume.

[0024] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0025] The figures are shown for illustrative purposes only and are not intended to limit the scope of the invention. In the drawings, the white arrows represent pressure forces exerted on the wedges.

[0026] [Fig. 1] is a top view of a mold according to the prior art, where a preform is arranged around a core and where a belt formed of a plurality of wedges is shown in the dissociated state.

[0027] [Fig. 2] is a view similar to [Fig. 1], where one wedge is in compaction support on the preform while the other wedges are being moved into this compaction position in order to assemble the belt into its molding configuration.

[0028] [Fig. 3] is a top view of a mold according to an exemplary embodiment of the invention where a preform is arranged around the inner core and where the belt is shown in the dissociated state.

[0029] [Fig. 4] is a view similar to [Fig. 3], where the guide wedges are in compaction support on the preform while the closing wedges are recessed.

[0030] [Fig. 5] is a view similar to [Fig. 3], where the guide shims and closing shims are in compaction support on the preform and where the belt is assembled in its molding configuration.

[0031] [Fig. 6] is a top perspective and exploded view of a complete mold according to an exemplary embodiment of the invention.

[0032] [Fig. 7] is a perspective view from below and an exploded view of the mold of [Fig. 6],

[0033] [Fig. 8] is a vertical cross-sectional view of a complete mold according to an example of an embodiment of the invention in the closed molding position. DETAILED DESCRIPTION

[0034] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0035] By convention, in this application, when referring to the mold according to the invention, the terms upper, lower, top, and bottom refer to the mold as shown in the drawings, [Fig. 1] to [Fig. 5] being top views. Similarly, vertical refers to a direction along an axis extending perpendicularly to the principal plane P in which the base of the mold extends. In the figures, the longitudinal axis Y-Y' of the part to be molded is vertical. This longitudinal axis Y-Y' is perpendicular to plane P. Finally, inside refers to a direction directed toward the center of the mold, and outside refers to a direction opposite to it.

[0036] The mold 10 according to the invention makes it possible to produce a part in composite material by impregnating a preform 20 with resin. The part in composite material is preferably a part of revolution or a part with an oblong or oval profile, with longitudinal axis Y-Y'.

[0037] The preform 20, sometimes also referred to as reinforcement, usually comprises a fibrous structure, the fibers of which may be pre-impregnated.

[0038] As shown in [Fig. 3] and following, the mold 10 comprises a base 30, a belt 40, a core 50, and a cover 90. All these elements are preferably rigid. They may be one-piece or made of several parts. They are, for example, manufactured from aluminum, steel, or cast iron.

[0039] The base 30 extends along a principal plane P perpendicular to the axis Y-Y'. It serves in particular as a support for the other elements of the mold 10 and closes the lower part of the mold 10. It is preferably in the form of a substantially flat disk having a lower face 38 and an upper face 39.

[0040] The belt 40 is annular in shape and extends along a plane parallel to plane P. It has a lower face 48, an upper face 49, an external radial face 44, and a circular internal radial face 45 designed to provide compaction support against the external radial face 24 of the preform 20. The belt 40 is distinguished by the fact that it comprises several different wedges 70, 80 to be assembled edge-to-edge to form the belt 40. These wedges 70, 80 are preferably monolithic, as shown in the figures, but they can also be in several parts.

[0041] The core 50 is preferably circular, oblong or oval in shape, centered on the axis Y-Y' and it extends along a plane parallel to the plane P. It has a lower face 58, an upper face 59, an external circular radial face 54 intended to provide compaction support against the internal radial face 25 of the preform 20 or to serve as a winding surface for said preform 20.

[0042] The lid 90 extends along a plane parallel to the main plane P and serves in particular to close the upper part of the mold 10. It is preferably in the form of a substantially flat disc having a lower face 98 and an upper face 99.

[0043] The belt 40 includes a set of removable shims comprising at least two removable guide shims 70 and two removable locking shims 80. It includes the same number of guide shims 70 and locking shims 80.

[0044] The belt 40, the core 50, and the guide shims 70 are preferably centered and held in place on the base 30 in a conventional manner. The centering of these parts is achieved, for example, by complementary shapes and / or by centering devices. The retention of these parts is preferably obtained by positioning alone or by means of clamping elements, for example by screws.

[0045] According to a preferred embodiment shown in the figures, the belt 40 comprises four guide wedges 70 and four closing wedges 80. However, it may comprise any total number of removable wedges 70, 80, this number being preferably even and greater than or equal to 4.

[0046] The guide wedges 70 are preferably identical to each other and the closing wedges 80 are preferably identical to each other.

[0047] The guide shims 70 and the closing shims 80 each form a sector of an annular disc. When assembled against each other within the mold 10, the guide shims 70 and the closing shims 80 form a belt 40 in the shape of said annular disc. The belt 40 then comprises an alternating pattern of guide shims 70 and closing shims 80, where each closing shim 80 is bordered by two guide shims 70.

[0048] The guide shims 70 and the closing shims 80 each have a lower face 78, 88, an upper face 79, 89, and two lateral faces 71, 72, 81, 82 provided at the interface between two adjacent removable shims 70, 80. The lateral faces 81, 82 of the closing shims 80 have a shape that is preferably complementary to that of the lateral faces 71, 72 of the adjacent guide shims 70. These lateral faces are preferably flat.

[0049] The closing wedges 80 are distinguished in that the two opposite lateral faces 81, 82 of each closing wedge 80 are parallel to each other.

[0050] Thus, when the guide wedges 70 are put in place, slightly compacting the preform 20, and a closing wedge 80 is then put in place edge to edge between two guide wedges 70, this closing wedge 80 first comes into contact with these two guide wedges 70 before it comes into contact with the preform 20, which prevents the preform 20 from being pinched between the lateral faces 71, 72, 81, 82 of two adjacent wedges 70, 80.

[0051] In the closed position of the mold 10, each closing wedge 80 is located between two guide wedges 70, and the guide wedges 70 and closing wedges 80 together form the aforementioned annular disk, which is centered on the Y-Y' axis. Within this disk, each lateral face 71, 72 of a guide wedge 70 is in contact against a lateral face 82, 81 of a closing wedge 80 and preferably parallel to it. The lateral faces 81, 82 of the closing wedges 80 are then preferably parallel to the lateral faces 71, 72 of the guide wedges 70.

[0052] When the mold 10 is closed in the molding configuration, the belt 40 rests on the base 30, the core 50 is centered on the Y-Y' axis and the cover 90 rests on the belt 40 and on the core 50.

[0053] In the molding configuration, the outer radial face 54 of the core 50 and the inner radial face 45 of the belt 40 rest against the preform 20 for compaction, defining a molding volume 100 within which the preform 20 can be impregnated with resin to form a composite part. This molding volume 100 can be closed at the top by the lid 90 and at the bottom by the base 30.

[0054] In the closed position of the mold 10, the internal radial face 74 of the guide shims 70 in contact with the preform preferentially covers a sector less than or equal to that covered by the internal radial face 84 of the closing shims 80, for example from about 30° to 45° in the case of four guide shims 70 and four closing shims 80.

[0055] The area S7 of the internal radial face 74 of the guide wedges 70 is preferably less than or equal to the area S8 of the internal radial face 84 of the closing wedges 80, for example such that 0.4 < S7 / S8 < 1. Indeed, the area S7 preferentially represents 30% to 50% of the total area of ​​the internal radial face 45 of the belt 40.

[0056] The shape of the outer radial face 54 of the core 50 defines at least partially the internal shape of the part to be produced, while the shape of the inner radial face 45 of the belt 40 defines the external shape of the resulting composite molded part. This part may, for example, be cylindrical, conical, frustoconical, barrel-shaped, or half-barrel-shaped, but must have at least one open upper or lower face to allow the removal of the core 50, unless a core element is intended to remain permanently in the part.

[0057] The molded parts can, for example, be retention housings, internal housing ferrules or flow bypass spacers.

[0058] A preferred example of producing a part in composite material by impregnating a preform 20 with resin and using a mold 10 according to the invention comprises the following steps: setting up the base 30; setting up a preform 20 around the core 50; setting up the preform 20 and the core 50 on the base 30; setting up the guide blocks 70 by sliding them on the base 30 along a plane parallel to the plane P and compacting the preform 20 between the internal radial face 74 of the guide blocks 70 and the core 50; setting up the closing wedges 80 by sliding them on the base 30 along a plane parallel to plane P, each closing wedge 80 being located between two adjacent guide wedges 70, and compacting the preform 20 between the internal radial face 84 of the closing wedges 80 and the core 50;placement of the cover 90 on the core 50 and the belt 40 formed by the removable shims 70, 80, the belt 40 and the core 50 delimiting a molding volume 100; injection of resin in liquid form into the molding volume 100.;

[0059] Depending on their size and mass, the wedges can be put in place manually or with mechanized assistance, the closing and / or opening of the mold 10 can be fully automated.

[0060] A variation of the previous example includes the following steps: positioning the base; positioning the core; positioning a preform on the base around the core; positioning the guide shims by sliding them onto the base along a plane parallel to plane P and compacting the preform between the inner radial face of the guide shims and the core; positioning the closing shims by sliding them onto the base along a plane parallel to plane P, each closing shim being located between two adjacent guide shims, and compaction of the preform between the inner radial face of the closing shims and the core; placement of the cover on the core and the belt formed by the removable shims, the belt and the core delimiting a molding volume; injection of resin in liquid form into the molding volume.setting up the base; setting up the core; setting up a preform on the base around the core; setting up the guide shims by sliding them on the base along a plane parallel to plane P and compacting the preform between the inner radial face of the guide shims and the core; setting up the closing shims by sliding them on the base along a plane parallel to plane P, each closing shim being located between two adjacent guide shims, and compacting the preform between the inner radial face of the closing shims and the core; setting up the cover on the core and the belt formed by the removable shims, the belt and the core delimiting a molding volume; injecting resin in liquid form into the molding volume.

[0061] After hardening of the resin, for example by polymerization, by heating and / or by cooling, and removal of the cover 90 and the belt 40, the part made of composite material can be removed from the mold 10.

[0062] In the figures, the distance between the preform 20 and the core 50 before compaction of said preform 20 has been deliberately exaggerated for clarity. This distance may be zero, particularly when the preform 20 is wound around the core 50 by rotating the latter like a mandrel.

Claims

CLAIMS

1. Mold (10) for producing a part with a longitudinal axis (Y-Y') by molding and comprising a base (30) extending along a main plane (P) perpendicular to the axis (Y-Y'), a belt (40) of annular shape extending along a plane parallel to the plane (P), a core (50), a cover (90) extending along a plane parallel to the plane (P), said mold (10) being characterized in that: - the belt (40) comprises a set of n removable guide wedges (70) and n removable closing wedges (80), with n > 2, the guide wedges (70) and closing wedges (80) each forming a sector of an annular disc on the axis (Y-Y'), and each closing wedge (80) being located between two guide wedges (70) within the belt (40); - the guide (70) and closing (80) wedges each have an internal radial face (74, 84), and two lateral faces (71, 72, 81, 82) provided at the interface located between two adjacent removable wedges (70, 80); - the two lateral faces (81, 82) of each closing wedge (80) are parallel; and in that - the lateral faces (71, 72, 81, 82) of the guide wedges (70) and the closing wedges (80) are flat.

2. Mold (10) according to claim 1, characterized in that, in the closed position of the mold (10), the belt (40) rests on the base (30), the core (50) is centered on the axis (Y-Y'), the cover (90) rests on the belt (40) and on the core (50), and each closing wedge (80) is located between two guide wedges (70).

3. Mold (10) according to claim 1 or 2, characterized in that the internal radial face (74) of each guide wedge (70) has a surface area S7 and the internal radial face (84) of each closing wedge (80) has a surface area S8, with S7 < S8.

4. Mold (10) according to claim 3, characterized in that 0.4 < S7 / S8 < 1. [Claim s] Mold (10) according to any one of the preceding claims, characterized in that the guide wedges (70) are identical to each other. [Claim s] Mold (10) according to any one of the preceding claims, characterized in that the closing wedges (80) are identical to each other.

7. Mold (10) according to any one of the preceding claims, characterized in that the number n of guide or closing wedges is between 4 and 8 and preferably equal to 6.

8. Molding method for producing a part from composite material by impregnating a preform (20) with resin and using a mold (10) according to any one of the preceding claims, characterized in that said method comprises the following steps: - installation of the base (30); - placing a preform (20) around the core (50); - placing the preform (20) and the core (50) on the base (30); - placing the guide wedges (70) by sliding them on the base (30) along a plane parallel to the plane (P) and compacting the preform (20) between the internal radial face (74) of the guide wedges (70) and the core (50); - placing the closing wedges (80) by sliding on the base (30) along a plane parallel to the plane (P), each closing wedge (80) being located between two adjacent guide wedges (70), and compacting the preform (20) between the internal radial face (84) of the closing wedges (80) and the core (50); - placing the cover (90) on the core (50) and the belt (40) formed by the removable shims (70, 80), the belt (40) and the core (50) delimiting a molding volume (100); - injection of resin in liquid form into the molding volume (100).

9. Molding method for producing a part from composite material by impregnating a preform (20) with resin and using a mold (10) according to any one of the preceding claims, characterized in that said method comprises the following steps: - installation of the base (30); - installation of the core (50); - placing a preform (20) on the base (30) around the core (50); - placing the guide wedges (70) by sliding them on the base (30) along a plane parallel to the plane (P) and compacting the preform (20) between the internal radial face (74) of the guide wedges (70) and the core (50); - placing the closing wedges (80) by sliding on the base (30) along a plane parallel to the plane (P), each closing wedge (80) being located between two adjacent guide wedges (70), and compacting the preform (20) between the internal radial face (84) of the closing wedges (80) and the core (50); - placing the cover (90) on the core (50) and the belt (40) formed by the removable shims (70, 80), the belt (40) and the core (50) delimiting a molding volume (100); - injection of resin in liquid form into the molding volume (100).

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