Method and system for resin infusion of composite preforms - Patents.com

Abstract

A method and system for resin infusion into a composite preform is provided that ensures that resin that passes through the preform is not drawn into a vacuum source. In one embodiment, a composite preform (10) is placed on an upper tool surface (111), and a resin reservoir element (120) having an inlet and an outlet (122) is located downstream of the composite preform. After sealing the upper tool surface with a vacuum bagging film, a resin supply is provided along a resin flow path through the composite preform, through the reservoir inlet, and to the resin reservoir. A pressure differential is established between the resin supply and the reservoir outlet, and at least a partial vacuum is applied to the reservoir outlet to drive resin from the resin supply through the resin flow path and fill the composite preform with resin. Excess resin is collected in the resin reservoir.

Description

[Technical field]

[0001] The present disclosure relates generally to the manufacturing of composite structures, and more specifically to methods and systems for resin infusion into composite preforms. [Background technology]

[0002] Current methods of manufacturing composite structures use a resin infusion process in which a composite preform formed from multiple plies formed from composite fibers is infused with resin followed by curing of the resin to form the composite structure. According to current methods, the composite preform is placed on an upper tool surface and a vacuum bagging film is placed on the upper tool surface to cover the composite preform and sealed to form a sealed chamber between the upper tool surface and the vacuum bagging film. Resin is infused through the composite preform by applying a vacuum pressure to the downstream end of the sealed chamber, which draws resin through the composite preform from an upstream resin supply. Once the resin has been infused throughout the preform, the entire assembly is heated, typically in an oven, to cure the resin and form the composite structure.

[0003] Resin infuses through the composite preform with a wave front that may or may not progress evenly across the lateral extent of the preform. It is important to ensure that the entire preform is infusible, but that resin that has passed through the preform is not drawn into the vacuum source in the leading area of ​​the wave front. If resin were to be drawn into the vacuum source, there is a risk of damaging the vacuum source. It may also be that the cost of removing the cured resin from the vacuum source and associated vacuum piping between the tool and the vacuum source, or the cost of replacing the vacuum source or piping, is prohibitive.

[0004] Various solutions to this problem have been proposed, but have met with varying degrees of success in terms of efficiency, quality of the finished product, retrofitability, and cost.

[0005] The present disclosure is made with the above problems in mind. Summary of the Invention

[0006] The present disclosure is generally directed to a method of resin infusion for a composite preform and a resin infusion system for resin infusion for a composite preform. According to an embodiment of the present disclosure, a resin reservoir element is used to collect excess resin upstream of a vacuum source that has passed through a resin flow path past the composite preform. The resin reservoir element is located on an upper tool surface of the tool, where the composite preform is placed, and defines a resin reservoir for collection of excess resin.

[0007] According to one aspect, the present disclosure provides a method of resin infusion of a composite preform. The composite preform is placed on an upper tool surface of a tool. A resin reservoir element is located on the upper tool surface downstream of the composite preform. The resin reservoir element and the upper tool surface define a resin reservoir. The resin reservoir has a reservoir outlet and a reservoir inlet located between the upper tool surface and the reservoir outlet. A vacuum bagging film is placed on the upper tool surface to cover the composite preform and the resin reservoir element. The vacuum bagging film is sealed against the upper tool surface to define a sealed resin infusion chamber between the upper tool surface and the vacuum bagging film. The composite preform and the resin reservoir element are placed in the resin infusion chamber. A resin supply is provided. A resin flow path is provided from the resin supply to the resin infusion chamber upstream of the composite preform, through the composite preform, through the reservoir inlet, and to the resin reservoir. At least a partial vacuum pressure is applied to the reservoir outlet, creating a pressure differential between the resin supply and the reservoir outlet to move resin from the resin supply through the resin flow path to fill the composite preform with resin, and excess resin is collected in the resin reservoir.

[0008] In one or more preferred embodiments, the resin reservoir element comprises a channel having a first lower end located toward the composite preform and an opposing second lower end located away from the composite preform, and a gap is formed between the first lower end and the upper tool surface that defines a reservoir inlet.

[0009] The method may further include placing a first permeable flow medium between the first lower end and the upper tool surface to at least partially define the gap.

[0010] The method may further include releasably sealing the second lower end to the upper tool surface.

[0011] In one or more preferred embodiments, the resin reservoir element is positioned to extend along at least a majority of the length of the downstream end of the composite preform.

[0012] A resin flow control occlusion may be positioned in the resin flow path between the composite preform and the resin reservoir.

[0013] The method includes providing a first vacuum between the reservoir outlet and a vacuum outlet port extending from an upper tool surface through the tool and defining a vacuum flow path. 3 At least partial vacuum pressure can be applied through the vacuum flow path.

[0014] According to a second aspect, the present disclosure provides a method of forming a composite article, the method comprising resin infusing a composite preform according to the method defined above to form a resin infused composite preform, and curing the resin infused composite preform.

[0015] Following cure of the resin infused composite preform, the resin reservoir element may be removed from the upper tool surface and excess resin collected in the reservoir may then be removed from the resin reservoir element.

[0016] According to a third aspect, the present disclosure provides a resin infusion system for resin infusion into a composite preform. The system includes a tool having an upper tool surface for receiving a composite preform to be resin infused, and a resin supply. A resin reservoir element is located on the upper tool surface downstream of the composite preform. The resin reservoir element and the upper tool surface define a resin reservoir having a reservoir outlet and a reservoir inlet located between the upper tool surface and the reservoir outlet. A vacuum bagging film covers the composite preform and the resin reservoir element to define a sealed resin infusion chamber between the vacuum bagging film and the upper tool surface. The composite preform and the resin reservoir element are positioned within the resin infusion chamber. A resin flow path extends from a resin supply to the resin infusion chamber upstream of the composite preform, through the composite preform, through the reservoir inlet to the resin reservoir. A vacuum source communicates with the reservoir outlet via the vacuum flow path.

[0017] In one or more preferred embodiments, the resin reservoir element comprises an elongated displacement channel section having both closed ends.

[0018] The channel section can have a first lower end located toward the composite preform and an opposing second lower end located away from the composite preform. In this configuration, the reservoir inlet can include a gap between the first lower end and the upper tool surface.

[0019] The system may further include a first permeable flow medium disposed between the first lower end and the upper tool surface to at least partially define the gap.

[0020] The second, lower end of the channel section may be removably sealed to the upper tool surface.

[0021] In a preferred embodiment, the channel section has a generally semicircular cross-section.

[0022] The reservoir outlet may advantageously be located at or near the top of the resin reservoir element.

[0023] In a preferred embodiment, the resin reservoir element extends along at least the majority of the length of the downstream end of the composite preform.

[0024] The system may further include a permeable resin flow control occlusion positioned in the flow path between the composite preform and the resin reservoir.

[0025] In one or more preferred embodiments, the vacuum flow path extends from an upper tool surface through a vacuum exit port extending through the tool, 3 The permeable flow medium extends from the reservoir outlet through the vacuum outlet port. In this configuration, the vacuum bagging film 3 and a vacuum outlet port.

[0026] In one or more embodiments, a plurality of reservoir outlets are spaced along the resin reservoir element.

[0027] As will be appreciated by those skilled in the art, the above features may be implemented independently in various embodiments of the present disclosure or may be combined in yet other embodiments.

[0028] Preferred embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram of a system for resin infusion into a composite preform according to a first embodiment. [Diagram 2] FIG. 2 is a schematic partial perspective view of the system of FIG. 1. [Diagram 3] FIG. 2 is a schematic cross-sectional view of the system of FIG. 1 taken at section 3-3. [Figure 4]FIG. 2 is a schematic cross-sectional view of the system of FIG. 1 taken at section 4-4. [Diagram 5] FIG. 2 is a schematic, partial perspective view of a modification of the system of FIG. 1. [Figure 6] FIG. 4 is a schematic cross-sectional view of a system for resin infusion of composite materials according to a second embodiment, taken at a section corresponding to FIG. 3; [Figure 7] FIG. 5 is a schematic cross-sectional view of a system for resin infusion of composite materials according to a second embodiment, taken at a section corresponding to FIG. 4. [Figure 8] FIG. 13 is a schematic diagram of a system for resin infusion into a composite preform according to a third embodiment. [Figure 9] FIG. 1 is a flow diagram of an exemplary method for resin infusion of a composite preform. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Systems and methods according to exemplary embodiments of the present disclosure will now be described in detail. In general, a method of resin infusing a composite preform according to the present disclosure includes placing a composite preform on an upper tool surface of a tool. A resin reservoir element is located on the upper tool surface downstream of the composite preform. The resin reservoir element and the upper tool surface define a resin reservoir having a reservoir outlet and a reservoir inlet located between the upper tool surface and the reservoir outlet, whereby the reservoir outlet is located at a higher position than the reservoir inlet. A vacuum bagging film is placed on the upper tool surface to cover both the composite preform and the resin reservoir element. The vacuum bagging film is sealed against the upper tool surface to define a sealed resin infusion chamber between the upper tool surface and the vacuum bagging film. The composite preform and the resin reservoir element are placed in the resin infusion chamber. A single vacuum bagging film may be used. A double vacuum bagging film configuration is also envisaged, in which an outer vacuum bagging film is placed on top of an inner vacuum bagging film with a vent in between. A resin flow path is provided from a resin supply to the resin infusion chamber upstream of the composite preform, through the composite preform, through the reservoir inlet, and to the resin reservoir. At least partial vacuum pressure is applied to the reservoir outlet, and by establishing a pressure differential between the resin supply and the reservoir outlet, resin is moved from the resin supply, specifically through the resin flow path, to fill the composite preform with resin. In a double vacuum bagging film configuration, at least partial vacuum pressure may also be applied to a cavity between the inner and outer vacuum bagging films. Excess resin that passes through the composite preform prior to cessation of the vacuum source is collected in the resin reservoir. The resin-infused composite preform may then be cured, typically in a heated oven. Excess resin collected in the reservoir is typically cured in the resin reservoir. Following curing and dismantling of the system by removal of the vacuum bagging film and associated consumables, the resin reservoir element can be removed from the tool and discarded or cleaned of the cured resin collected in the resin reservoir.

[0031] With reference now to the accompanying Figures 1 to 4, a system 100 for resin infusing a composite preform 10 according to a first embodiment will be described. The system 100 comprises a tool 110 having an upper tool surface 111 on which the composite preform 10 to be resin infused is placed. A resin reservoir element 120 is located on the upper tool surface 111 downstream of the composite preform 10. As will be described further below, in the context of this document, the upstream and downstream sides of the composite preform 10 are specified with respect to the resin flow direction. With particular reference to Figure 3, the reservoir element 120 together with the upper tool surface 111 defines a resin reservoir 121. The resin reservoir 121 has a reservoir outlet 122 and a reservoir inlet 123 located between the upper tool surface 111 and the reservoir outlet 122. A vacuum bagging film 130 covers the composite preform 10 and the resin reservoir element 120 to define a sealed resin infusion chamber 140 between the vacuum bagging film 130 and the upper tool surface 111. The composite preform 10 and the resin reservoir element 120 are placed within the resin infusion chamber 140. The system 100 further comprises a resin supply 141 with a resin flow path 142 extending from the resin supply 141 to the resin infusion chamber 140 upstream of the composite preform 10, through the composite preform 10, through the reservoir inlet 123 and to the resin reservoir 121. Referring to FIG. 4, a first vacuum source 151 communicates with the reservoir outlet 122 via the vacuum flow path 150.

[0032] Tool 110 may be formed from any of a variety of structural materials, including mild steel, stainless steel, Invar, or a carbon composite that will retain its shape under the elevated temperatures associated with curing, thereby providing a geometrically stable upper tool surface 111 throughout the resin curing process. Upper tool surface 111 may be substantially flat for producing composite structures having a substantially flat lower surface, such as wing or fuselage skin panels, or may otherwise have a desired shape for providing a shaped surface for a non-planar composite structure.

[0033] The composite preform 10 may take any form suitable for resin infusion and dictated by the geometric and structural requirements of the laminated composite structure to be fabricated. The composite preform 10 may include a lay-up of multiple plies of reinforcement, each formed of woven or knitted fibers and / or chopped strand mats. The plies of the preform may be formed of any of a variety of reinforcing fibers, such as carbon, graphite, glass, aromatic polyamide, or any other material suitable for forming resin-reinforced laminated composite structures. The plies may form a dry preform that does not contain any resin, or alternatively, the preform may have some pre-existing resin content prior to the resin infusion process. The composite preform 10 is placed on the upper tool surface 111 in an orientation such that the lower surface of the preform 10 is on the upper tool surface 111, so that the lower surface of the resulting composite structure conforms to the shape of the upper tool surface 111. Composite preform 10, positioned on upper tool surface 111, has a laterally extending downstream end 11, an opposite laterally extending upstream end 12, and opposite longitudinally extending side ends 13. Preform 10 may take any desired shape that corresponds to the shape of the laminated composite structure to be formed.

[0034] The resin reservoir element 120 shown in the illustrated first exemplary embodiment comprises an elongated displaced channel section 124 having both closed ends 125. The channel section 124 has a generally semicircular cross section in the illustrated first embodiment, but it is envisioned that it may take any of a variety of alternative forms, including rectangular, square, triangular, semi-hexagonal, or any of a variety of other cross-sectional shapes. A semicircular cross section is advantageous in that it has no sharp edges on its outer surface that may puncture the vacuum bagging film 130 or make sealing difficult. A channel section 124 with a semicircular cross section may also typically be inexpensive to form, and may be formed by cutting a tubular section in half and to a predetermined length. The resin reservoir element 120 may be formed from any of a variety of materials, including metallic materials such as stainless steel or aluminum, or other non-metallic materials, including composite materials or thermosetting plastics, that favorably maintain their shape under the high temperatures associated with the resin curing process. The closed ends 125 of the resin reservoir element 120 may be integrally molded with the channel section 124 or may otherwise be secured to the ends of the channel section 124, such as by adhesive and / or mechanical fastening. The ends 125 of the resin reservoir element 120 may be formed of the same material as the channel section 124. Alternatively, the ends 125 of the resin reservoir element 120 may be formed of a different material than the channel section 124 is formed from.

[0035] In one variation 100' of the first embodiment system 100 shown in Figure 5, both ends 125' of the modified resin reservoir element 120' are formed from multiple pieces of sealing tape that would otherwise be used to seal the vacuum bagging film 130 and other components of the system, as described further below. In this variation, the resin reservoir element 120' may simply be formed from cut portions of the channel area 124'. The channel area 124' may be placed on the upper tool surface 111 with both ends of the resin reservoir defined and then sealed using sealing tape to form the closed ends 125' of the resin reservoir element 120'.

[0036] 1, in a first embodiment, the resin reservoir element 120 is positioned on the upper tool surface 111 such that it extends along at least half of the length of the downstream end 11 of the composite preform 10. Because the resin reservoir element 120 is formed with a length sufficient to extend along at least half of the length of the downstream end 11 of the composite preform 10, a relatively direct flow path is provided from along the downstream end 11 of the composite preform 10 to the resin reservoir 121 along the downstream end 11. In configurations in which the downstream end 11 of the composite preform 10 is straight, the resin reservoir element 120 may advantageously be disposed generally parallel to the downstream end 11 of the composite preform 10.

[0037] As shown in Figures 1 and 2, in a first embodiment, two reservoir outlets 122 are provided, spaced apart along the channel section 124. It is also envisioned that only a single reservoir outlet 122 may be provided. Alternatively, three or more reservoir outlets 122 may be provided, spaced apart along the channel section 124. The reservoir outlets 122 may advantageously be located at or near the top of the resin reservoir element 120. In the embodiment shown, the reservoir outlets 122 are located at the top of the channel section 124, as best shown in Figures 1 and 3. Thereby, the vertical separation between the reservoir inlet 123 and the reservoir outlet 122 is maximized.

[0038] 3 and 4, in the first embodiment of the system 100, the channel section 124 of the resin reservoir element 120 has a first lower end 126 located toward the downstream end 11 of the composite preform 10 and an opposite second lower end 127 located away from the composite preform 10, whereby the first lower end 126 is a substantially upstream end and the second lower end 127 is a substantially downstream end. In the particular configuration shown, the reservoir inlet 123 is defined by a gap formed between the first lower end 126 and the upper tool surface 111. In the embodiment shown, a transversely extending first band 143 of permeable flow medium and a downstream portion 144 of a permeable peel ply 145 (itself constituting a permeable flow medium) placed on the preform 10 extend into and define the gap that defines the reservoir inlet 123 (as described further below). The first strip 143 and the downstream portion 144 of the peel ply 145 support the first lower end 126 of the channel section 124. The first strip 143 of permeable flow medium and the downstream portion 144 of the peel ply 145 are sufficiently permeable to allow resin to pass therethrough to the resin reservoir inlet 123. The first strip 143 of permeable flow medium may suitably be in the form of a nylon mesh material, such as PLASTINET® 15231 available from Airtech International Inc, or any other highly permeable medium that allows resin to pass therethrough. The peel ply 145 also constitutes a permeable flow medium and may suitably be in the form of a PTFE coated fiberglass fabric, such as RELEASE EASE® 234, also available from Airtech International Inc, or any other permeable peel ply material.

[0039] It is envisioned that either the first band 143 of permeable flow medium or the downstream portion 144 of the peel ply 145 may be omitted, with a single permeable flow medium defining the gap of the reservoir inlet 123. The reservoir inlet 123 may be defined by one or more openings provided along the length of the resin reservoir element 120. Although it is still further envisioned, in the arrangement shown, the need to drill or otherwise form such openings in the resin reservoir element 120 is avoided.

[0040] A second lower end 127 of the channel section 124 may be removably sealed to the upper tool surface 111, and in the embodiment shown is removably sealed by a strip of sealing tape 128, which may conveniently be in the form of a mastic sealant tape such as sealant tape GS-213-3 available from Airtech International Inc.

[0041] A resin flow path 142 extends from the resin supply 141 through the resin infusion chamber 140, the composite preform 10, and the reservoir inlet 123 to the resin reservoir 121, and is comprised of a series of piping elements and consumable layup material. The upstream portion of the resin flow path 142 may include one or more resin supply pipes 146 that communicate with one or more resin infusion inlets 112 extending through the tool 110 upstream of the composite preform 10 and deliver resin to the resin infusion chamber 140 upstream of the composite preform 10. The resin supply pipes 146 are typically formed from copper.

[0042] An intermediate portion of the resin flow path 142 is formed by the composite preform 10, the peel ply 145, and the layer of permeable flow medium 147. The peel ply 145 extends throughout the composite preform 10, beyond each end 11, 12, 13 of the composite preform 10. The peel ply 145 both prevents the layer of permeable flow medium 147 from sticking to the composite preform 10 and provides a path for the resin to fill the composite preform 10, both along the upstream end 12 of the composite preform 10 and through the upper surface of the composite preform 10. The layer of permeable flow medium 147, which in the embodiment shown is made from the same material as the first strip of permeable flow medium 143, extends beyond the peel ply 145. In the embodiment shown, the layer of permeable flow medium 147 extends beyond the upstream end 12 of the composite preform 10, over one or more resin infusion inlet ports 112, and beyond the downstream end 11 of the composite preform 10, leaving a gap between the downstream end of the layer of permeable flow medium 147 and the band of permeable flow medium 143. Rather than communicating the resin infusion chamber 140 with the resin supply 141 through a resin flow path 142 passing through the resin inlet port 112 extending through the tool 110, it is also envisioned that the resin flow path 142 may penetrate the vacuum bagging film 130. In such a configuration, an opening may be formed in the vacuum bagging film 130 and the opening may be in communication with the resin supply 141 that seals the periphery of the opening.

[0043] The downstream portion of resin flow path 142 is formed by downstream portion 144 of peel ply 145 and band 143 of permeable flow medium.

[0044] The vacuum flow path 150, which communicates the first vacuum source 151 with the reservoir outlets 122, consists of a series of piping elements and consumable lay-up material. The upstream portion of the vacuum flow path 150, which extends from the reservoir outlets 122, consists of a second permeable flow medium. The second permeable flow medium may conveniently be formed from the same material as the layers 147 and bands 143 of permeable flow medium used in the resin flow path 142, although it is also envisioned that other forms of permeable flow medium may be used, if desired. The second permeable flow medium here includes two bands 152 of permeable flow medium located on the resin reservoir element 120, each covering one of the reservoir outlets 122, and a further band 153 of permeable flow medium extending laterally, which communicates the bands 152 with the vacuum outlet port 113 extending through the tool 110 downstream of the resin reservoir element 120. To prevent the second permeable flow medium bands 152 and 153 from sticking to the sealing tape band 128, a tape 156 may be applied to the exposed surface of the sealing tape band 128 sealing the resin reservoir element 120 to the upper tool surface 111. The vacuum outlet port 113 communicates with the first vacuum source 151 via one or more vacuum outlet pipes 154, forming a downstream portion of the vacuum flow path 150. The vacuum outlet pipes 154 are typically formed from copper. Rather than communicating the reservoir outlet 122 with the first vacuum source 151 through the vacuum outlet port 113 extending through the tool 110, it is also envisioned that the vacuum flow path 150 may penetrate the vacuum bagging film 130. In such a configuration, an opening may be formed in the vacuum bagging film 130, and the opening may be in communication with the first vacuum source 151, sealing around the opening.

[0045] The vacuum bagging film 130 extends across the entire layup formed by the composite preform 10, the peel ply 145, and the layer of permeable flow medium 147, and further extends over the resin reservoir element 120 and the second bands of permeable flow medium 152, 153. Any of a variety of vacuum bagging film materials may be used, including, by way of example and not limitation, Airtech WL7400 or SL800 vacuum bagging films available from Airtech International Inc. The vacuum bagging film 130 is sealed to the upper tool surface 111 by a further band 131 of sealing tape around the outer surface of the vacuum bagging film 130. The band 131 is typically formed from the same material as the band 128 of sealing tape that seals the second lower end 127 of the channel section 124 to the upper tool surface 111. An additional band of sealing tape 132 seals the vacuum bagging film 130 to the resin reservoir element 120 around the second band of permeable flow medium 152 to isolate the resin infusion flow path 142 and the resin infusion chamber 140 from the vacuum flow path 150. As can be best seen in Figures 3 and 4, the vacuum bagging film 130 defines an upper boundary of the resin flow path 142. Between the downstream end of the layer of permeable flow medium 147 and the upstream end of the band of permeable flow medium 143, the vacuum bagging film 130 confines the resin flow path 142 to the downstream portion 144 of the peel ply 145, thereby defining a permeable resin flow control occlusion. The vacuum bagging film 130 also defines an upper boundary of the vacuum flow path 150.

[0046] In practice, once the system 100 is assembled as described above, the resin supply 141 is catalyzed and heated to bring the resin to the appropriate resin infusion temperature. Typically, the entire system is heated in an oven, which is also used for subsequent curing. The temperature of the resin infusion depends on the resin system used and is typically selected to provide an appropriate viscosity that allows the resin to be infused through the resin flow path 142. Any resin may be used that is suitable for use in the resin infusion process and is determined by the desired properties of the composite structure to be formed. Suitable resins may include epoxy, bismaleimide, benzoxazine, polyimide, and polyamideimide resins. At least partial vacuum pressure is applied to the reservoir outlet 123 via the first vacuum source 151 and the vacuum flow path 150. A weaker partial vacuum (i.e., a higher absolute pressure) may be applied to the resin supply 141 by a second vacuum source 155 connected to a second vacuum pipe 157, as best shown in FIG. 4. When a partial vacuum is applied by the second vacuum source 155 to the resin supply 141, a pressure differential may be maintained between the first vacuum source 151 and the second vacuum source 155 such that the absolute pressure applied by the first vacuum source 151 to the reservoir outlet 123 is lower than the absolute pressure at the resin supply 141. In one example, a full vacuum (0 mBar / 0 kPA) may be applied by the first vacuum source 151 and a higher / weaker vacuum of 500-800 mBar (50-80 kPA) may be applied by the second vacuum source 155, thereby providing an equivalent pressure differential to move the resin from the resin supply 141 through the resin flow path 142. A full vacuum may also be applied to the second vacuum source 155 prior to resin infusion to degas the resin.

[0047] Maintaining at least a partial vacuum in the resin supply 141 ensures that at least a partial vacuum is maintained throughout the resin infusion chamber 140. Atmospheric pressure acting on the preform 10 through the vacuum bagging film 130, the layer of permeable flow medium 147, and the peel ply 145 acts to solidify the composite preform 10. The resin travels along the wave front through the resin infusion chamber 142 and through the layer of permeable flow medium 147, which is generally more permeable than both the peel ply 145 and the composite preform 10, thereby providing a path of least resistance. Resin passing through the layer of permeable flow medium 147 seeps through the less permeable peel ply 145 and into the preform 10. Some of the resin also flows laterally through the upstream end 12 of the composite preform 10 and, to a lesser extent, through either side end 13 of the composite preform 10. The downstream end 11 of the layer of permeable flow medium 147 terminates before both the band of permeable flow medium 123 and the downstream portion 144 of the peel ply 145, thereby preventing the resin from bypassing the preform 10 and simply being drawn through the layer of permeable flow medium 147 directly into the resin reservoir 121. After the resin has passed the downstream end 11 of the composite preform 10 and the downstream end of the layer of permeable flow medium 147, the rate of advance of the resin wave front is reduced by forcing the resin to pass vertically downstream through the permeable resin flow controlling occlusion defined by the downstream portion 144 of the peel ply 145 until it reaches the resin reservoir 121. It is also contemplated that, rather than forming a permeable resin flow control occlusion in the downstream portion 144 of the peel ply 145 to control the advancement of the resin wave front, a separate permeable resin flow control occlusion formed by a permeable medium that is typically less permeable than the layer 147 of permeable control medium may be used between the composite preform 10 and the resin reservoir 121.

[0048] Typically, the resin wave front does not advance evenly across the lateral extent of the composite preform 10, especially where there are non-uniformities in the composite preform 10 geometry or thickness. Where a portion of the resin wave front first reaches the reservoir inlet 123, the resin flows into the resin reservoir 121. Because a vacuum is pulled through the resin outlet 122, which is located higher than the resin inlet 123, gravity does not tend to pull the resin through the reservoir outlet 122 and along the vacuum flow path 150 toward the first vacuum source 151. Thus, resin infusion may continue without the resin being moved into the vacuum pipe 154 until visual confirmation is received that the entire resin wave front has reached the downstream end 11 of the composite preform 10, indicating that resin infusion of the composite preform 10 is complete. Once the completion of resin injection is visually identified, a resin inlet valve (not shown) on the resin supply pipe 146 may be closed to prevent further injection of resin. Completion of resin injection may be determined based on a pre-defined resin injection time, rather than relying on visual identification. Once resin injection is complete, rather than closing the resin inlet valve, the oven temperature may be increased to initiate curing of the resin, thereby stopping further injection.

[0049] The resin infused composite preform 10 may be cured by increasing the temperature of the oven to a temperature appropriate for curing the resin. For epoxy resins, a curing temperature on the order of 180°C to 200°C would be typical. A full vacuum is typically maintained on the first vacuum source 151 during the curing process, thereby ensuring that the resin infused composite preform 10 remains solidified and aiding in curing the resin.

[0050] Once the resin has cured and the system has cooled to room temperature, the various consumable layers, including the vacuum bagging film 130, the layer of permeable flow medium 147 and the various strips 143, 152, 153, and the release ply 145, are removed along with the resin reservoir element 120. The resin reservoir element 120 may be removed from the upper tool surface 111 and the excess resin collected and cured within the resin reservoir 121 may be removed, allowing for reuse of the resin reservoir element 120. Alternatively, the resin reservoir element 120 may be discarded. Discarding the resin reservoir element 120 may be particularly appropriate if the element 120 is inexpensively formed by cutting a simple tubular section.

[0051] Vacuum bagging films typically exhibit some air permeability, particularly at the elevated temperatures associated with resin infusion and / or resin curing. As a result, one possible drawback of the single vacuum bag configuration of the first embodiment resin infusion system 100 is that with vacuum applied during the curing process, air may permeate through the vacuum bagging film 130 and into the composite structure 10, potentially resulting in porosity and resin starvation in the cured composite laminate. Thus, a double bag resin infusion system is envisioned in an effort to minimize or avoid such air permeation, providing a second vacuum bagging film over the first vacuum bagging film and applying vacuum pressure to the second vacuum bagging film during both the resin infusion and curing steps.

[0052] Figures 6 and 7 show schematic cross-sectional views (corresponding to Figures 3 and 4) of such a double bag configuration of the first embodiment system 100, forming a second embodiment system 200. The second embodiment system 200 is substantially identical to the first embodiment system 100, but with a second vacuum bagging film 160 and associated venting material layer 161. As a result, features of the second embodiment system 200 that are identical to features of the first embodiment system 100 are given the same reference numbers and will not be discussed further.

[0053] In the second embodiment system 200 shown in Figures 6 and 7, the composite preform 10, resin reservoir element 120, and associated consumable layers such as the layer of permeable flow medium 147 and the various strips 143, 152, 153, the peel ply 145, and the first vacuum bagging film 130 are first assembled in a manner similar to that described above in connection with the first embodiment system 100. A vent layer 161, typically a highly permeable woven fabric made of fiberglass, polyester, or the like, is then placed over and completely covers the first vacuum bagging film 130. A suitable vent layer is a vent cloth made of a high film nonwoven polyester material, such as AIRWEAVE® N10 available from Airtech International Inc. The venting layer 161 extends over the vacuum groove 114 that extends around the periphery of the upper tool surface 111 and is connected to the first vacuum source 151 (or a separate third vacuum source) via a third vacuum pipe 158. A second vacuum bagging film 160 is then placed over the venting layer 161 and sealed to the upper tool surface 111 by a further strip of sealing tape 162, forming a sealed cavity between the first vacuum bagging film 130 and the second vacuum bagging film 160. The composite preform 10 is resin infused and subsequently cured using the same process as described above in relation to the first embodiment system 100. At least a partial vacuum is applied to the sealed cavity between the first vacuum bagging film 130 and the second vacuum bagging film 160 by the first vacuum source 151 (or a separate third vacuum source) throughout the resin infusion and curing. The second vacuum bagging film 160 and the associated vacuum applied to the sealed cavity prevent any micro-leaks associated with the first vacuum bag 130. Any air that permeates through the second vacuum bagging film 160 and through the vent layer 161 towards the composite preform 10 is evacuated by the applied vacuum and cannot permeate to the composite preform 10.

[0054] Now, with reference to Figure 8 in the accompanying drawings, a system 300 for resin infusion of a composite preform 20 according to a third embodiment will be described. The system 300 has the same basic configuration and employs the same principles as the system 100 according to the first embodiment. However, it is particularly suitable for manufacturing elongated composite articles having recesses, such as wing spars and D-noses, movable trailing edge assemblies, movable leading edge assemblies, and vertical and horizontal stabilizers. In Figure 8, only the downstream portion of the system 300 is shown, while the basic configuration of the upstream portion is the same as that of the system 100 of the first embodiment. Features of the system 300 of the third embodiment that are identical to those of the system 100 of the first embodiment are given similar reference numbers in the accompanying figures, increased by 100.

[0055] The composite preform 20, specifically representing a composite preform for a moveable trailing edge spar, has a longitudinally extending central web 25 and opposing flanges 26 extending along opposing side edges 23 of the composite preform 20. The composite preform 20, which is typically flexible when initially laid up, each has opposing end portions that form flanges 26 that rest on the upper tool surface 211 of the tool 210 along side walls 215 of corresponding recesses 216 that extend along the sides of a central flat portion 217 of the upper tool surface 211. In a configuration of the system 200, a resin reservoir element 220 is located downstream of a vacuum outlet 213 extending through the tool 210. A portion of the resin flow path extending between the downstream end 21 of the composite preform 20 and the reservoir inlet 223 is defined by a separate permeable resin flow control closure 244, a laterally extending band 243 of permeable flow medium extending laterally across the downstream portion of the flow control closure 244, and a pair of further vertically extending bands 248 of permeable flow medium connecting the band 243 of permeable flow medium with the reservoir inlet 223, the bands 248 extending below the first lower end 226 of the channel section 224 of the resin reservoir element 220.

[0056] The resin reservoir element 220 is provided with a single centrally located reservoir outlet 222 that communicates with a first vacuum source (not shown) via a vacuum flow path that includes an additional strip 252 of permeable flow medium extending from the reservoir outlet 222 and covering the vacuum outlet port 213. A strip of sealing tape 231 is also used to seal the vacuum bagging film that covers the composite preform 20 and the resin reservoir element 220 (along with the peel ply and the layer of permeable flow medium thereon, not specifically shown in FIG. 8). To isolate the vacuum flow path from the resin infusion chamber, a further strip of sealing tape is also used in the same manner as described above in connection with the first embodiment of the system 100. The composite preform 20 is then resin infused in generally the same manner as described above in connection with the first embodiment of the system 100. In a variation of the third embodiment system 300, an additional vacuum bagging film may be used below the composite preform 20, between the composite preform 20 and the upper tool surface 211, thereby placing the composite preform 20 indirectly on the upper tool surface 211.

[0057] The above general method of resin infusing a composite preform is generally illustrated in the flow diagram of FIG. 9. At block 401, a tool having an upper tool surface is provided. At block 402, a composite preform is placed on the upper tool surface. At block 403, a resin reservoir element is placed on the upper tool surface downstream of the composite preform. The resin reservoir element and the upper tool surface define a resin reservoir, the resin reservoir having a reservoir outlet and a reservoir inlet located between the upper tool surface and the reservoir outlet. Block 403 represents a vacuum bag placed on the upper tool surface to cover the composite preform and the resin reservoir element. Block 405 represents a vacuum bagging film sealed against the upper tool surface and defining a sealed resin infusion chamber between the upper tool surface and the vacuum bagging film. The composite preform and the resin reservoir element are placed within the resin infusion chamber. Block 406 represents providing a resin supply. Block 407 represents providing a resin flow path extending from a resin supply to the resin infusion chamber upstream of the composite preform, through the composite preform, through the reservoir inlet, to the resin reservoir, Block 408 represents applying at least partial vacuum pressure to the reservoir outlet to create a pressure differential between the resin supply and the reservoir outlet to move resin from the resin supply through the resin flow path to fill the composite preform with resin and collect excess resin in the resin reservoir.

[0058] Illustrative, non-exclusive examples of subject matter according to the present invention are set out in clauses A1 to C20 below.

[0059] A1. According to one aspect of the present disclosure, there is provided a method of resin infusing a composite preform 10, comprising: placing a composite preform 10 on an upper tool surface 111 of a tool 110; placing a resin reservoir element 120 on the upper tool surface 111 downstream of the composite preform 10, the resin reservoir element 120 and the upper tool surface 111 defining a resin reservoir 121, the resin reservoir 121 having a reservoir outlet 122 and a reservoir inlet 123 located between the upper tool surface 111 and the reservoir outlet 122; placing a vacuum bagging film 130 on the upper tool surface 111 to cover the composite preform 10 and the resin reservoir element 120; sealing the vacuum bagging film 130 against the upper tool surface 111 to define a sealed resin infusion chamber 140 between the upper tool surface 111 and the vacuum bagging film 130, the composite preform 10 and the resin reservoir element 120 being disposed within the resin infusion chamber 140; Providing a resin supply unit 141; providing a resin flow path 142 from the resin supply 141 to the resin infusion chamber 140 upstream of the composite preform 10, through the composite preform 10, through the reservoir inlet 123 and to the resin reservoir 121; A method is provided which includes applying at least a partial vacuum pressure to the reservoir outlet 122 to move resin from the resin supply 141 through the resin flow path 142 to fill the composite preform 10 with resin by creating a pressure differential between the resin supply 131 and the reservoir outlet 122, wherein excess resin is collected in the resin reservoir 121.

[0060] A2. The method described in clause A1, wherein the resin reservoir element 120 has a channel section 124 having a first lower end 126 positioned toward the composite preform 10 and an opposite second lower end 127 positioned away from the composite preform 10, the method further comprising forming a gap between the first lower end 126 and the upper tool surface 111 defining the reservoir inlet 123.

[0061] A3. The method of clause A2, further comprising disposing a first permeable flow medium between first lower end 126 and upper tool surface 111 to at least partially define the gap.

[0062] A4. The method of any one of clauses A1 to A2, further comprising releasably sealing the second lower end 127 to the upper tool surface 111.

[0063] A5. The method of any one of clauses A1-A4, wherein the resin reservoir element 120 is positioned to extend along at least a majority of the length of the downstream end of the composite preform 10.

[0064] A6. The method of any one of clauses A1-A5, further comprising installing a resin flow control closure in the resin flow path 142 between the composite preform 10 and the resin reservoir 121.

[0065] A7. A second vacuum outlet port 113 is provided between the reservoir outlet 122 and the upper tool surface 111 extending through the tool 110 to form a vacuum flow path 150. 3 The method of any one of clauses A1-A6, further comprising providing a permeable flow medium, wherein the at least partial vacuum is applied to the vacuum flow path 150.

[0066] B8. Resin infusing a composite preform 10 according to a method according to any one of clauses A1 to A7 to form a resin infused composite preform according to a further aspect of the present disclosure; curing the resin infused composite preform. A method of forming a composite article is provided, comprising:

[0067] B9. Following cure of the resin infused composite preform, removing the resin reservoir element 120 from the upper tool surface; Removing excess resin collected in the resin reservoir 121 from the resin reservoir element 120; The method of clause B8, further comprising:

[0068] According to a further aspect of the present disclosure, there is provided a resin infusion system for infusing a composite preform 10 with resin, the system comprising: a tool 110 having an upper tool surface 111 for receiving a composite preform 10 to be resin infused; A resin supply unit 141, a resin reservoir element 120 located on the upper tool surface 111 downstream of the composite preform 10, the resin reservoir element 120 and the upper tool surface 111 defining a resin reservoir 121 having a reservoir outlet 122 and a reservoir inlet 123 located between the upper tool surface 111 and the reservoir outlet 122; a vacuum bagging film 130 covering the composite preform 10 and the resin reservoir element 120, wherein a sealed resin infusion chamber 140 is defined between the vacuum bagging film 130 and the upper tool surface 111, and the composite preform 10 and the resin reservoir element 120 are placed within the resin infusion chamber 140; a resin flow path 142 extending from the resin supply 141 to the resin infusion chamber 140 upstream of the composite preform 10, through the composite preform 10, through the reservoir inlet 123, and to the resin reservoir 121; a vacuum source 151 in communication with the reservoir outlet 122 via a vacuum flow path 150; A system 100 is provided comprising:

[0069] C11. The system 100 of clause C10, wherein the resin reservoir element 120 comprises an elongated displacement channel section 124 having both closed ends 125.

[0070] C12. The system 100 described in clause C11, wherein the channel section 124 has a first lower end 126 positioned toward the composite preform 10 and an opposite second lower end 127 positioned away from the composite preform 10, and the reservoir inlet 123 has a gap between the first lower end 126 and the upper tool surface 111.

[0071] C13. The system 100 of clause C12, further comprising a first permeable flow medium disposed between the first lower end 126 and the upper tool surface 111 to at least partially define the gap.

[0072] C14. The system 100 of clause C12 or C13, wherein the second lower end 127 of the channel portion 124 is removably sealed to the upper tool surface 111.

[0073] C15. The system 100 of any one of clauses C11 to C14, wherein the channel portion 124 has a generally semicircular cross-section.

[0074] C16. The system 100 of any one of clauses C10 to C15, wherein the reservoir outlet 122 is located at or near the top of the resin reservoir element 120.

[0075] C17. The system 100 of any one of clauses C10 to C16, wherein the resin reservoir element 120 extends along at least a majority of the length of the downstream end of the composite preform 10.

[0076] C18. The system 100 of any one of clauses C10 to C17, further comprising a permeable resin flow control occlusion (244) disposed within the resin flow path 142, between the composite preform 10 and the resin reservoir 121.

[0077] C19. The system 100 of any one of clauses C10 to C18, wherein the vacuum flow path 150 extends through a vacuum outlet port 113 extending from the upper tool surface 111 through the tool 110, and the apparatus further comprises a second vacuum outlet port 113 extending from the reservoir outlet 122 to the vacuum outlet port 113. 3 The vacuum bagging film 130 further comprises a permeable flow medium of 3 The system 100 of any one of clauses C10 to C18, wherein the permeable flow medium and the vacuum outlet port 113 extend above the permeable flow medium.

[0078] C20. The system 100 of any one of clauses C10 to C19, comprising a plurality of the reservoir outlets 122 spaced along the resin reservoir element 120.

[0079] It will be understood by those skilled in the art that the above specific embodiments are merely examples of the present disclosure. It will be understood by those skilled in the art that the various features described with respect to the various embodiments can be used in combination or as alternatives. Various modifications and alternatives to the described embodiments will also be understood by those skilled in the art.

Claims

1. placing a composite preform (10) on an upper tool surface (111) of a tool (110); placing a resin reservoir element (120) on the upper tool surface (111) downstream of the composite preform (10), the resin reservoir element (120) and the upper tool surface (111) defining a resin reservoir (121), the resin reservoir (121) having a reservoir outlet (122) and a reservoir inlet (123) located between the upper tool surface (111) and the reservoir outlet (122); placing a vacuum bagging film (130) on the upper tool surface (111) to cover the composite preform (10) and the resin reservoir element (120); sealing the vacuum bagging film (130) against the upper tool surface (111) to define a sealed resin infusion chamber (140) between the upper tool surface (111) and the vacuum bagging film (130), the composite preform (10) and the resin reservoir element (120) being disposed within the resin infusion chamber (140); Providing a resin supply (141); providing a resin flow path (142) from the resin supply (141) to the resin infusion chamber (140) upstream of the composite preform (10), through the composite preform (10), through the reservoir inlet (123) to the resin reservoir (121); providing a first permeable flow medium extending from the reservoir inlet toward the composite preform, the first permeable flow medium forming a portion of the resin flow path; providing a second permeable flow medium extending from the resin supply across the composite preform toward the resin reservoir, the second permeable flow medium forming a portion of the resin flow path; applying at least partial vacuum pressure to the reservoir outlet (122) to move resin from the resin supply (141) through the resin flow path (142) to fill the composite preform (10) with resin by creating a pressure differential between the resin supply (141) and the reservoir outlet (122), where excess resin is collected in the resin reservoir (121); Including, A method of injecting resin into a composite preform (10), wherein a permeable peel ply (145), the downstream portion of which extends into a gap defining a reservoir inlet (123) and forms part of a resin flow path (142), extends throughout the entire composite preform (10), and a resin flow control blocking portion (244) has the function of blocking the flow of resin between a first permeable flow medium and a second permeable flow medium while allowing the flow of resin in the permeable peel ply (145).

2. 2. The method of claim 1, wherein the resin reservoir element (120) comprises a channel portion (124) having a first lower end (126) located toward the composite preform (10) and an opposite second lower end (127) located away from the composite preform (10), the method further comprising forming a gap between the first lower end (126) and the upper tool surface (111) that forms the reservoir inlet (123).

3. 3. The method of claim 2, further comprising disposing a first permeable flow medium between a first lower end (126) and the upper tool surface (111) to at least partially define the gap.

4. 4. The method of claim 1, further comprising providing a third permeable flow medium between the reservoir outlet (122) and a vacuum outlet port (113) extending from the upper tool surface (111) through the tool (110) and forming a vacuum flow path (150), to which the at least partial vacuum is applied.

5. Resin infusing a composite preform (10) according to a method for forming a resin infused composite preform according to any one of claims 1 to 4, curing the resin infused composite preform. A method of forming a composite article comprising:

6. 1. A resin infusion system (100) for infusing a composite preform (10) with resin, comprising: a tool (110) having an upper tool surface (111) for receiving a composite preform (10) to be resin infused; A resin supply unit (141); a resin reservoir element (120) located on the upper tool surface (111) downstream of the composite preform (10), the resin reservoir element (120) and the upper tool surface (111) defining a resin reservoir (121) having a reservoir outlet (122) and a reservoir inlet (123) located between the upper tool surface (111) and the reservoir outlet (122); a vacuum bagging film (130) covering the composite preform (10) and the resin reservoir element (120), wherein a sealed resin infusion chamber (140) is defined between the vacuum bagging film (130) and the upper tool surface (111), and the composite preform (10) and the resin reservoir element (120) are placed in the resin infusion chamber (140); a resin flow path (142) extending from the resin supply (141) to the resin infusion chamber (140) upstream of the composite preform (10), through the composite preform (10) and through the reservoir inlet (123) to the resin reservoir (121); a first permeable flow medium extending from the reservoir inlet toward the composite preform, the first permeable flow medium forming a portion of the resin flow path; a second permeable flow medium extending from the resin supply across the composite preform toward the resin reservoir, the second permeable flow medium forming a portion of the resin flow path; a vacuum source (151) in communication with the reservoir outlet (122) via a vacuum flow path (150); A system (100) in which a permeable peel ply (145), the downstream portion of which extends into the gap defining the reservoir inlet (123) and forms part of the resin flow path (142), extends throughout the composite preform (10), and a resin flow control occlusion portion (244) has the function of blocking the flow of resin between the first permeable flow medium and the second permeable flow medium while allowing resin flow in the permeable peel ply (145).

7. The system (100) of claim 6, wherein the resin reservoir element (120) comprises an elongated displacement channel section (124) having opposite closed ends (125).

8. 8. The system (100) of claim 7, wherein the channel section (124) has a first lower end (126) positioned toward the composite preform (10) and an opposite second lower end (127) positioned away from the composite preform (10), and the reservoir inlet (123) comprises a gap between the first lower end (126) and the upper tool surface (111).

9. The system (100) of claim 8, wherein the second lower end (127) of the channel portion (124) is removably sealed to the upper tool surface (111).

10. 10. The system (100) of claim 6, further comprising a permeable resin flow control occlusion (244) disposed in the resin flow path (142) between the composite preform (10) and the resin reservoir (121).

11. 11. The system (100) of any one of claims 6 to 10, wherein the vacuum flow path (150) extends through a vacuum outlet port (113) extending from the upper tool surface (111) through the tool (110), the system further comprising a third permeable flow medium extending from the reservoir outlet (122) to the vacuum outlet port (113), and the vacuum bagging film (130) extends over the third permeable flow medium and the vacuum outlet port (113).

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