Tooling for molding parts with circumferential compaction from the external face of a preform
The mold design with guide and closing wedges addresses the issue of pinching during circumferential compaction in resin transfer molding, enabling effective and pinching-free compaction of preforms for composite part production.
Patent Information
- Application Number
- FR2023007795
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-07-20
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2043-07-20
AI Technical Summary
Existing resin transfer molding technologies face challenges in achieving circumferential compaction of preforms without pinching, pleating, or folding, especially when using shims with a specific profile that can cause the preform to be pinched between wedges.
The introduction of a mold design featuring a set of removable guide and closing wedges, where the closing wedges first come into contact with the guide wedges before engaging with the preform, preventing pinching and ensuring proper compaction.
This solution allows for effective circumferential compaction of preforms from their external face without pinching, ensuring that the preform is neither creased nor folded, thereby facilitating the production of composite parts with improved quality.
Smart Images
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Abstract
Description
Title of the invention: Tooling for molding parts with circumferential compaction from the external 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 an 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 shims coming into compacting 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.l], it is known to use a mold 10' comprising a belt 40' and a core 50' which delimit a molding volume in which a preform 20' can be impregnated with resin. This preform 20', wound around the core 50', is usually formed of fibers and needs to be compacted before resin injection.
[0004] When molding parts of revolution or parts with an oblong or oval profile, circumferential compaction of the preform 20' can be carried out, from its external radial face 24'. As shown in [Fig.l] and [Fig.2], the belt 40' usually comprises several identical wedges 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 shims 60' currently used, when they are placed around the preform 20', it is common for the latter to be pinched between two shims 60' at the pinching and wedging zones C shown in the figures. Indeed, when a first shim is placed, slightly compacting the preform, and a second shim adjacent to the first is placed, it first comes into contact with the preform before being in contact with the first shim, and the preform is then generally pinched between the first and second shims.
[0006] Before injecting the resin into the mold, however, it is necessary to ensure that the preform is neither pleated, nor folded, nor stuck by the wedges.
[0007] There is therefore a need for a mold capable of carrying out circumferential compaction from the external face of a preform and which is not likely to cause pinching of the preform while also making it possible to ensure that the preform is neither creased 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 wedge to be placed in a defined order so that when one wedge is placed adjacent to another, it first comes into contact with the neighboring wedge before coming to bear on the preform.
[0009] One aspect of the invention relates to a mold for producing a part with a longitudinal axis Y-Y' by molding and comprising a base extending along a main plane P perpendicular to the axis Y-Y', a ring-shaped 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 disc on the Y-Y' axis, 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 side faces of each closing wedge are parallel.
[0010] A first holding and compacting of the preform is advantageously achieved by the installation of the guide wedges, which make it possible to prevent the preform from being pleated or folded. Then, the installation of the closing wedges between two guide wedges, by a radial sliding inwards, makes it possible to finalize the holding and the circumferential compacting of the preform against the core. The sliding of the lateral faces of the closing wedges along the lateral faces of the adjacent guide wedges advantageously makes it possible to guide the installation of the closing wedges and to finalize the compacting of the preform without the latter being pinched between the wedges.When closing the mold, bringing the side faces of the closing wedges into contact with the side faces of the guide wedges before the closing wedges come into contact with the preform, advantageously prevents damage to the preform and, above all, prevents it from being pinched between two wedges. The mold according to the invention thus allows complete forming of the preform, by circumferential compaction from its external 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 a surface area S7 and the internal radial face of each closing wedge has a surface 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 S7 surface area which represents 30% to 50% of the total surface area of the internal radial face of the belt.
[0015] The circumferential compaction of the forming preform is more effective with respect to the possible expansion of the latter when the contact surface of a wedge with the preform is larger for the closing wedges than for the guide wedges. Indeed, the mold according to the invention advantageously makes it possible to reduce the quantity of material subject to expansion which is pushed back by the guide wedges and which is likely to 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 their installation, and advantageously makes it possible to make them interchangeable.
[0017] According to an additional aspect of the invention, in the closed position of the mold, the lateral faces of the closing wedges are parallel to the lateral faces of the guide wedges, which in particular provides an absence of play. Indeed, the presence of play between the guide wedges and the closing wedges is likely to cause pinching of the preform, as illustrated in [Fig.l] and [Fig.2].
[0018] According to one aspect of the invention, the guide shims are identical to each other.
[0019] According to another aspect of the invention, the closing wedges are identical between they.
[0020] The use of identical shims for the same type of removable shims advantageously facilitates the design and manufacture of the mold, while reducing its cost.
[0021] According to an additional aspect of the invention, the number n of guide or closing wedges is between 4 and 8 and preferably equal to 6. Thus, the mold according to the invention preferably comprises between eight and sixteen wedges in total, and preferably twelve wedges.
[0022] Another aspect of the invention relates to a molding method for producing a part from composite material by impregnating a preform with resin and using a mold according to any one of the preceding claims, characterized in that said method comprises the following steps: • installation of the base; • installation of a preform around the core; • placing the preform and the core on the base; • installation of the guide wedges by sliding them on the base along a plane parallel to plane P and compaction of the preform between the internal radial face of the guide wedges and the core; • placing the closing wedges by sliding them on the base along a plane parallel to plane P, each closing wedge being located between two adjacent guide wedges, and compacting the preform between the internal radial face of the closing wedges and the core; • placing the cover on the core and the belt formed by the removable wedges, the belt 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 method 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 method comprises the following steps: • installation of the base; • setting up the core; • installation of a preform on the base around the core; • installation of the guide wedges by sliding them onto the base according to a plane parallel to plane P and compaction of the preform between the internal radial face of the guide wedges and the core; • placing the closing wedges by sliding them on the base along a plane parallel to plane P, each closing wedge being located between two adjacent guide wedges, and compacting the preform between the internal radial face of the closing wedges and the core; • placing the cover on the core and the belt formed by the removable wedges, the belt 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 upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES
[0025] The figures are presented for information purposes only and in no way limit the invention. In the drawings, the white arrows represent pressure forces exerted on the shims.
[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 represented in the dissociated state.
[0027] [Fig.2] is a view similar to [Fig.l], where one wedge is in compacting support on the preform while the other wedges are being moved into this compacting position in order to assemble the belt in 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 internal 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 compacting support on the preform while the closing wedges are set back.
[0030] [Fig.5] is a view similar to [Fig.3], where the guide wedges and the closing wedges are in compacting support on the preform and where the belt is assembled in its molding configuration.
[0031] [Fig.6] is a perspective view from above and exploded of a complete mold according to an exemplary embodiment of the invention.
[0032] [Fig.7] is a perspective view from below and exploded of the mold of [Fig.6].
[0033] [Fig.8] is a vertical sectional view of a complete mold according to an example of realization of the invention in closed molding position. DETAILED DESCRIPTION
[0034] Unless otherwise specified, the same element appearing in different figures has a single reference.
[0035] By convention, in the present application, when referring to the mold according to the invention, by upper, lower, above and below we refer to the mold as shown in the drawings, [Fig.l] to [Fig.5] being top views. Similarly, by vertical we refer to a direction along an axis extending perpendicularly to the main 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 Y-Y' is perpendicular to the plane P. Finally, by interior we refer to a direction directed towards the center of the mold, by exterior we refer to an opposite direction.
[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 a longitudinal axis Y-Y'.
[0037] The preform 20, sometimes also referred to as a 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 can be single-piece or consist of several parts. They are for example made of aluminum, steel or cast iron.
[0039] The base 30 extends along a main 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 disc 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 the plane P. It has a lower face 48, an upper face 49, an external radial face 44 and an internal radial face 45 which is circular and intended to come into compacting support against the external radial face 24 of the preform 20. The belt 40 is characterized in 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 single-piece, 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, a circular external radial face 54 intended to come into compacting support against the internal radial face 25 of the preform 20 or to serve as a winding surface for said preform 20.
[0042] The cover 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 comprises a set of removable wedges comprising at least two removable guide wedges 70 and two removable closing wedges 80. It comprises as many guide wedges 70 as closing wedges 80.
[0044] The belt 40, the core 50 and the guide wedges 70 are preferably centered and held in place on the base 30 in a conventional manner. The centering of these parts is for example obtained by complementarity of shapes and / or by centering devices. The holding of these parts is preferably obtained by laying only 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. It can however comprise any total number of removable wedges 70, 80, this number preferably being 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 closing shims 80 each form a sector of an annular disc. When they are assembled against each other within the mold 10, the guide shims 70 and closing shims 80 form a belt 40 in the form of said annular disc. The belt 40 then comprises an alternation of guide shims 70 and closing wedges 80, where each closing wedge 80 is bordered by two guide wedges 70.
[0048] The guide wedges 70 and closing wedges 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 located between two adjacent removable wedges 70, 80. The lateral faces 81, 82 of the closing wedges 80 have a shape preferably complementary to that of the lateral faces 71, 72 of the adjacent guide wedges 70. These lateral faces are preferably flat.
[0049] The closing wedges 80 are characterized 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 being in 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 disc, which is centered on the axis Y-Y'. Within this disc, 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 the latter. 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 axis Y-Y' and the cover 90 rests on the belt 40 and on the core 50.
[0053] In the molding configuration, the external radial face 54 of the core 50 and the internal radial face 45 of the belt 40 are in compacting support on the preform 20 and delimit between them a molding volume 100 in which the preform 20 can be impregnated with resin to form a part made of composite material. This molding volume 100 can be closed in the upper part by the cover 90 and in the lower part by the base 30.
[0054] In the closed position of the mold 10, the internal radial face 74 of the guide wedges 70 in contact with the preform preferably covers a sector less than or equal to that covered by the internal radial face 84 of the closing wedges 80, for example approximately 30° to 45° in the case of four guide wedges 70 and four closing wedges 80.
[0055] The surface area S7 of the internal radial face 74 of the guide shims 70 is preferably less than or equal to the surface area S8 of the internal radial face 84. closing wedges 80, for example such that 0.4 < S7 / S8 < 1. In fact, the surface area S7 preferably represents from 30% to 50% of the total surface area of the internal radial face 45 of the belt 40.
[0056] The shape of the external 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 internal radial face 45 of the belt 40 defines the external shape of the part molded from composite material obtained. 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 an element acting as a core is intended to remain permanently in the part.
[0057] The molded parts may for example be retention casings, internal casing ferrules or flow bypass spacers (known by the English term Zow bypass spacer).
[0058] A preferred example of producing a part from composite material by impregnating a preform 20 with resin and using a mold 10 according to the invention 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; • positioning of the guide wedges 70 by sliding on the base 30 along a plane parallel to the plane P and compacting of the preform 20 between the internal radial face 74 of the guide wedges 70 and the core 50; • positioning of 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 of 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.
[0059] Depending on their size and mass, the shims can be put in place manually or with mechanical assistance, the closing and / or opening of the mold 10 being able to be fully automated.
[0060] A variation of the previous example includes the following steps: • installation of the base; • setting up the core; • installation of a preform on the base around the core; • installation of the guide wedges by sliding them on the base along a plane parallel to plane P and compaction of the preform between the internal radial face of the guide wedges and the core; • placing the closing wedges by sliding them on the base along a plane parallel to plane P, each closing wedge being located between two adjacent guide wedges, and compacting the preform between the internal radial face of the closing wedges and the core; • placing the cover on the core and the belt formed by the removable wedges, the belt and the core delimiting a molding volume; • injection of resin in liquid form into the molding volume. • installation of the base; • setting up the core; • placing a preform on the base around the core • installation of the guide wedges by sliding them onto the base according to a plane parallel to plane P and compaction of the preform between the internal radial face of the guide wedges and the core; • placing the closing wedges by sliding them on the base along a plane parallel to plane P, each closing wedge being located between two adjacent guide wedges, and compacting the preform between the internal radial face of the closing wedges and the core; • placing the cover on the core and the belt formed by the removable wedges, the belt and the core delimiting a molding volume; • injection of resin in liquid form into the molding volume.
[0061] After curing the resin, for example by polymerization, by heating and / or by cooling, and removal of the cover 90 and the belt 40, the composite material part can be removed from the mold 10.
[0062] In the figures, the distance which separates the preform 20 from the core 50 before compacting said preform 20 has been deliberately exaggerated for reasons of clarity. This distance may be zero, in particular in the case where the preform 20 is wound around the core 50 by rotation of the latter in the manner of 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 wedges (70) and closing wedges (80) 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.
5. Mold (10) according to any one of the preceding claims, characterized in that the guide wedges (70) are identical to each other.
6. 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 made of 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: - placing 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 wedges (70, 80), the belt (40) and the core (50) delimiting a molding volume (100); - injecting 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 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 wedges (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).