RESIN BARRIER DEVICE, GASKET AND METHOD FOR INFUSING A PREFORM

Abstract

A resin barrier device for connection in a vacuum line, for use in resin infusion during composite manufacture, includes a housing having an inlet port for connection to a resin source and an outlet port for connection to a vacuum source. A flow path extends between the inlet and outlet ports. A gas-permeable membrane is disposed across the flow path to prevent resin from flowing to the vacuum pump. A gasket supports the membrane and is adapted to prevent resin leakage. A method of infusing a preform with a resin also is provided.

Claims

1. A gasket for use to support a gas-permeable membrane in a resin barrier device, the gasket comprising: an outer flange portion extending around the periphery of the gasket; first and second inner flange portions extending inwardly from the outer flange portion around the periphery of the gasket; and a peripheral slot between the first and second inner flange for receiving a membrane.

2. The gasket of claim 1, further comprising a peripheral bead around at least one of two faces of the outer flange portion.

3. The gasket of claim 2, wherein the peripheral bead is a continuous protrusion extending around the periphery of the gasket.

4. The gasket of claim 1, further comprising two peripheral beads extending from opposing faces of the outer flange portion in opposing directions.

5. The gasket of claim 4, wherein the two peripheral beads are continuous protrusions, each extending around the periphery of the gasket.

6. The gasket of claim 1, wherein the gasket is formed of an elastomeric material.

7. A method of infusing a composite preform with a resin, comprising: applying a reduced pressure to a vacuum cavity comprising the composite preform, using a vacuum source; and whilst the reduced pressure is applied: flowing resin into the vacuum cavity from a resin source; flowing the resin out of the vacuum cavity and along a flow path towards the vacuum source; flowing the resin into a portion of the flow path between the vacuum cavity and the vacuum source, having an increased flow area; and blocking the resin flow along the flow path using a gas-permeable membrane disposed across the increased flow area portion of the flow path.

8. The method of claim 7, comprising flowing the resin out of the vacuum cavity through a vacuum conduit or a plurality of vacuum conduits.

9. The method of claim 8, blocking resin flowing along the vacuum conduit or each of the plurality of vacuum conduits using a resin barrier device.

10. The method of claim 9, wherein the resin barrier device comprises: a housing having an inlet port fluidly coupled with the resin source and an outlet port fluidly coupled with the vacuum source, wherein the flow path extends through the inlet port and the outlet port, and the gas-permeable membrane disposed across the increased flow area portion of the flow path, wherein the increased flow area portion of the flow path is located between the inlet port and the outlet port.

11. The method of claim 10, wherein the increased flow area portion has a cross-sectional area that is larger than a cross-sectional area of the flow path extending through either the inlet port or the outlet port.

12. The method of claim 11, wherein the housing further comprises separable first and second portions.

13. The method of claim 12, wherein the resin barrier device further comprises: a gasket positioned between the first and second portions of the housing, the gasket comprising: an outer flange portion extending around a periphery of the gasket, first and second inner flange portions extending inwardly from the outer flange portion around the periphery of the gasket, and a peripheral slot between the first and second inner flange portions, wherein the gas-permeable membrane is received in and supported around a periphery thereof in the peripheral slot across the increased flow area portion of the flow path.

14. A method of infusing a composite preform with a resin, comprising: applying a reduced pressure to a vacuum cavity comprising the composite preform, using a vacuum source; and whilst the reduced pressure is applied: flowing resin into the vacuum cavity from a resin source; flowing the resin out of the vacuum cavity and along a flow path towards the vacuum source, wherein the flow path extends through a resin barrier device comprising a gas-permeable membrane; flowing the resin into a portion of the flow path between the vacuum cavity and the vacuum source, having an increased flow area; and blocking the resin flow along the flow path using the gas-permeable membrane disposed across the increased flow area portion of the flow path.

15. The method of claim 14, wherein the resin barrier device comprises: a housing formed from separable first and second portions having an inlet port fluidly coupled with the resin source and an outlet port fluidly coupled with the vacuum source, wherein the flow path extends through the inlet port and the outlet port, and the gas-permeable membrane disposed across the increased flow area portion of the flow path, wherein the increased flow area portion of the flow path is located between the inlet port and the outlet port.

16. The method of claim 15, wherein the increased flow area portion has a cross-sectional area that is larger than a cross-sectional area of the flow path extending through either the inlet port or the outlet port.

17. The method of claim 16, wherein the resin barrier device further comprises: a gasket positioned between the first and second portions of the housing, the gasket comprising: an outer flange portion extending around a periphery of the gasket, first and second inner flange portions extending inwardly from the outer flange portion around the periphery of the gasket, and a peripheral slot between the first and second inner flange portions.

18. The method of claim 17, wherein the gas-permeable membrane is received in and supported around a periphery thereof in the peripheral slot across the increased flow area portion of the flow path.

19. The method of claim 18, wherein the gasket further comprises at least one continuous peripheral bead protruding outward from at least one of two faces of the outer flange portion.

20. The method of claim 19, wherein the at least one peripheral bead is received in at least one channel of at least one of the separable first and second portions of the housing.

Description

DESCRIPTION OF THE DRAWINGS

[0103] Example embodiments will now be described with reference to the following figures in which:

[0104] FIG. 1 shows a perspective cross sectional view of a resin barrier device.

[0105] FIG. 2 shows the resin barrier device of FIG. 1 with a tri-clover clamp retaining the body portions together.

[0106] FIG. 3(a) shows a perspective view of a gasket for use in a resin barrier device, and FIG. 3(b) shows an expanded cross sectional view of the gasket through plane B.

[0107] FIG. 4(a) shows a perspective view of an alternative embodiment of a resin barrier device and FIG. 4(b) shows a cross sectional view of the resin barrier device.

[0108] FIGS. 5(a) and (b) are schematic drawings of steps of a resin transfer infusion process, using a resin barrier device. FIG. 5(c) is a close-up view of the resin barrier device.

[0109] FIG. 6 shows photographs of (a) upstream and (b) downstream faces of a membrane used in a resin barrier device during a resin transfer infusion process.

[0110] FIG. 7 shows photographs of (a) a downstream and (b) an upstream face of a membrane used in a resin barrier device during a resin transfer infusion process.

[0111] FIG. 8 shows an end-on view of an alternative body portion of a resin barrier device.

[0112] FIGS. 9(a) and (b) shows schematic cross sectional side views of housing body portions of a resin barrier device.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0113] FIG. 1 shows a cross sectional view of a resin barrier device 1. The resin barrier device has a housing 3 having separable first and second portion 5, 7. The housing has an inlet port 9 and an outlet port 11. In use these are connected to a resin source and a vacuum source, respectively.

[0114] A flow path 13 extends through the housing between the inlet port 9 and the outlet port 11. A gas-permeable membrane 15 is disposed across the flow path, within the housing 3.

[0115] The first portion 5 and the second portion 7 of the housing 3 are sealed together by a sealing 30 arrangement, in the form of a gasket 17, which is described in further detail below.

[0116] A portion of the flow path 13 has an increased flow area 14, in comparison to either the inlet or the outlet ports. The membrane 15 is across the increased flow area portion 14 of the flow path 13. In the embodiment shown, the flow area through the membrane is around 70 times 35 the flow area at the inlet port 9. In an embodiment shown, the flow area of inlet may be for example around 28 mm2, with and around 2000 mm2 at the membrane. The opposed faces 21, 23 of the respective first and second portions 5, 7 of the housing are spaced apart (in the embodiment shown, by the gasket 17), such that the flow path has an increased flow area around 1-2 mm either side of the membrane 15.

[0117] The volume within the housing 3 downstream of the membrane 15 (i.e. in the flow path 13 between the membrane and the second portion 7 of the housing) also includes a pad of breather material 19 (a nylon mesh). The breather material provides a degree of structural support to the membrane and in addition prevents the effective flow area of the membrane from being reduced by direct contact between the membrane and housing.

[0118] In alternative embodiments, the resin barrier device may further include a flow media upstream of the membrane, to promote event distribution of any resin flowing into the resin barrier device, in use.

[0119] The first and second portions of the housing are secured together by a conventional tri-clover fitting, as shown in FIG. 2. An articulated clamp 25 surrounds the housing 3, and outer parts of the tapered surfaces 27, 29 of the housing portions fit within a slot (not visible in the figure) running around the inner circumference of the collar. A wing nut 31 is used to secure the collar 25 around the housing, so that radial compression of the collar around the housing is translated to compression along the axis A between the housing portions, as the collar rides up the opposed tapered surfaces 27, 29 of the housing.

[0120] To replace the membrane 15, the collar can be removed, so as to access the gasket 17.

[0121] FIG. 3(a) shows a perspective view of the gasket 17. A schematic cross sectional view of the region B of the gasket is shown in FIG. 3(b). The gasket has an outer flange portion 40 and, extending inwardly therefrom, first and second inner flange portions 42, 44. Between the first and second inner flange portions 42, 44 is a peripheral slot 46.

[0122] In use, the membrane 15 is supported within the slot 46. It will be appreciated that FIG. 3(b) shows the configuration of the gasket 17 when in an uncompressed configuration, with any spacing between the first and second inner flange portions 42, 44 greatly exaggerated so that the features of the gasket can be clearly seen.

[0123] Also shown in FIG. 3(b) is the location of the disc of breather material 17, against the inner face 15a of the downstream inner flange portion of the membrane 15. The inner face 52 of the inner flange portion 44 and the exposed downstream face 15b of the membrane define a shallow recess for the breather material, which abuts the face 52 and is thereby prevented from slipping to one side and exposing the membrane as the gasket and membrane are assembled together in the housing.

[0124] In use, when pressure is applied between the separable portions of the housing, the inner flange portions 42, 44 are pressed against the membrane 15, such that the membrane is sealed around its periphery within the slot 46. This prevents resin from leaking outwardly of the edge 48 of the membrane 15.

[0125] The gasket 17 also has a raised bead 50 extending around the periphery of the outer flange portion 40, on both faces thereof. These rest in corresponding channels 33 in the opposing surfaces 21, 23 of the first and second portions 5, 7 of the housing 3 (see FIG. 1).

[0126] Accordingly, the interface between the gasket and the surfaces 21, 23 of the first and second portions of the housing are somewhat convoluted, to improve the integrity of the seal.

[0127] Alternatively, one or more conventional gaskets and/or O-rings may be used as a sealing arrangement.

[0128] FIG. 4(a) shows a perspective view of an alternative embodiment of a resin barrier device 100. A schematic cross sectional view of the resin barrier device 100 is shown in FIG. 4(b). Features in common with the resin barrier device 1 are provided with like reference numerals, incremented by 100.

[0129] Unlike the circularily symmetric body 3 of the resin barrier device 1, resin barrier device 100 has a polygonal (square) body 103 disposed symmetrically around an axis A. The first portion 105 of the body 103 is attached to the second portion 107 of the body 103 by a series of bolts 125 and nuts 126 extending through the body 103 around its periphery. A gas permeable membrane 115 is located within the body in the flow path 113 that extends between the inlet port 109 and the outlet port 111.

[0130] The sealing arrangement between the first and second portions includes a gasket 117 a between the membrane 115 and the first body portion 105, and a further gasket 117 b between the membrane and the second body portion 107. Optionally, a silicone sealant may also be applied.

[0131] In the volume 116 between the separable portions of the body 103 (i.e. along the length of the increased flow area of the flow path), on the upstream side of the membrane 115 is a flow media 119 and on the downstream side there is a pad of breather material 119. FIG. 5(a) is a schematic illustration of apparatus used in a method of resin transfer infusion.

[0132] A dry carbon fibre preform 200 is laid up on a mould surface 201 of a tool 202. The preform is covered with layers of a flow media 204, a porous release fabric 206 (also known as a “peel ply”) and then a vacuum foil (typically formed from a silicone material) or, in the embodiment shown, a mould tool 208. These layers are then sealed against the mould surface 201 of the tool 202 using a mastic sealant tape 210 and optionally O-rings, so as to define a vacuum cavity 212 between the tool and the mould tool 208. At least one outlet port 214 extends through the tool, and a vacuum conduit 216 is connected to a vacuum source, typically a vacuum pump (not shown).

[0133] A resin barrier device 1 as disclosed herein is connected in line with the vacuum conduit, close to the outlet 214. A close-up view of the resin barrier device 1 and vacuum line is shown in FIG. 5(c), with tri-clover fittings at the inlet and outlet ports. The resin barrier device 1 is positioned as close to the tool 202 as possible (around 5 to 10 cm—to allow a sufficient length of vacuum conduit 216 to make a gas-tight connection with both the outlet 214 and the inlet port 9 of the resin barrier device). This is made possible because the resin barrier device is capable of functioning in any orientation, including with the inlet port above the outlet port as shown.

[0134] An inlet conduit 218 extends from a resin source, typically a vessel containing a reservoir of resin (not shown) to an inlet nozzle 220 in the vacuum cavity. The inlet nozzle communicates with the flow media 204.

[0135] Various sealant and release layers, as known in the art, are omitted for clarity. It should also be understood that while a single outlet from the vacuum cavity is shown, in practice multiple outlets may be present.

[0136] With an inlet valve 222 in the inlet conduit 218 dosed, the vacuum pump is used to reduce the pressure in the vacuum cavity, in practice resulting in the contents of the vacuum cavity being compressed due to a resulting pressure differential between the vacuum cavity and its surroundings (typically at ambient pressure). The gas-permeable membrane in the resin barrier device 1 allows air to be pumped from the vacuum cavity in this way.

[0137] With the vacuum still applied to the vacuum conduit 216, the valve 222 is opened and resin from the resin source flows through the conduit 218 and the inlet nozzle 220 under the action of the pressure differential. The resin perfuses through the relatively high permeability flow media 204 and is drawn into the preform 200 and towards the outlet 214. During this process, residual air and evaporated solvent from the resin is pumped from the vacuum chamber and passes through the resin barrier device's gas-permeable membrane 15.

[0138] Optionally, the resin transfer infusion is conducted in an autoclave, and the pressure within the autoclave increased when the preform has been infused (and while the vacuum is still applied). This typically results in further excess resin flowing out of the vacuum cavity.

[0139] As shown in FIG. 5(b), when the infusion is complete, the vacuum cavity 212 is filled with resin, and excess resin flows through the outlet 214 and along the vacuum conduit 216. The resin flows along the flow pathway in the resin barrier device 1 but, unlike the gaseous components, is blocked by the membrane. Resin is thereby prevented from flowing downstream of the resin barrier device and damaging the vacuum pump.

EXAMPLES

[0140] FIG. 6 shows (a) the upstream face and (b) the downstream face of a series of test membranes.

[0141] The membranes were used for a resin infusion process generally as described above with reference to FIG. 5. Initial pumping rate from the vacuum cavity through the resin barrier devices was between around 2-4 litres per minute.

[0142] Cycom 890 epoxy resin (Cycom is a trademark of Cytec Industries Inc.) was infused into a test preform at an elevated temperature, at which the resin viscosity was relatively low (ca. 200-250 cps).

[0143] Test were conducted using a sealing arrangement between the housing portions of hand-cut silicone gaskets (having a ShoreA hardness of 50-60) positioned around the periphery of hand-cut gas porous membranes, with approximate exposed membrane surface diameters of around 7.5 cm (3 inches), 6.3 cm (2.5 inches) and 5 cm (2 inches).

[0144] The membrane material used was a laminate construction including a two-layer microporous polymer foam and polyester textile outer faces, obtained from Trans-Texti® GmbH. Freilassing, Germany. The membrane has an airflow permeability of 2-4 Ipm over 20 cm2 (determined using standard method EN ISO 9237), a maximum operating temperature of 190° C. and a resin barrier effectiveness to resins with viscosities as low as 10 cps.

[0145] On the downstream face of each membrane, was positioned a hand-cut disc of coarse weave breather material.

[0146] The sealing arrangements were removed following infusion and curing. As shown in the Figures, resin had collected on the upstream face of the membrane, with minimal or no resin permeating through the membrane. No resin was seen on the downstream face of the breather material.

[0147] FIGS. 7(a) and (b) show analogous results using a gasket 17, configured as described above in relation to FIGS. 1 and 3.

[0148] FIG. 8 shows an alternative embodiment of a second portion 209 of a resin barrier device housing. The figure shows the surface 223 which in use faces the first portion of the resin barrier device, and seals against the gasket 17.

[0149] The surface 223 includes a peripheral channel 233 which in use receives a bead 50. In addition, the surface is engraved with a flow pattern 252 (in this case in a spider web pattern radiating away from the outlet port 211).

[0150] The portion 209 is adapted for the resin barrier device to be used without a breather material between the membrane and the surface 223. In use, when the membrane contacts the surface 223 (when a pressure differential builds up across the membrane during initial evacuation and/or as resin builds up on the upstream face during infusion), the membrane surface and the flow pattern 252 together define channels providing fluid communication between the inlet and outlet ports, across the membrane surface. The non-engraved regions 254, between the engraved channels 256 of the flow pattern, provide support to the membrane, in use.

[0151] FIG. 9 shows cross sectional view of a further embodiment of (a) a first housing portion 305 and (b) a second housing portion 307 of a barrier device 300. Features in common with the barrier device 1 are provided with like reference numerals, incremented by 300. The first housing portion is adapted for placement downstream of the membrane in use, and comprises the outlet port 311. To assist with identification, the first housing portion is provided with indicia 360, in the form of grooves around the housing.

[0152] The second housing portion has an inlet port 309.

[0153] As described above in relation to the device 1, the first and second housing portions 305, 307 in use define a flow path 313 that extends through the housing between the inlet port 309 and the outlet port 311. A gas-permeable membrane as disclosed herein is disposed across the flow path.

[0154] The first and second housing portions 305, 307 and both the inlet and outlet pots 309, 311 in the embodiment shown provided with tri-clover fittings.

[0155] In use the membrane facing surfaces 321, 323 of the housing portions are separated by a gasket, such that the flow path has an increased flow area at the membrane, as described above.

[0156] Each housing portion has a tapered bore 362, 364. The bores are narrower close to the membrane facing surfaces 321, 323, so that the membrane facing surface provide maximal support to the membrane in use. The taper facilitates removal of “plugs” of cured or partially cured resin from the housing portions (in the direction of the inlet/outlet ports) after use.

[0157] Whilst exemplary embodiments have been described herein, these should not be construed as limiting to the modifications and variations possible within the scope of the invention as disclosed herein and recited in the appended claims.