GB2528851A

GB2528851A - Self-sealing resin inlet port

Info

Publication number: GB2528851A
Application number: GB1413550.3A
Authority: GB
Inventors: Leon Barton; Christopher Owens
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2014-07-31
Filing date: 2014-07-31
Publication date: 2016-02-10
Also published as: GB201413550D0

Abstract

A resin inlet port 52 for use in a vacuum-assisted moulding process includes a conduit 54 and a mount 56. The conduit has an inlet end 58 and an outlet end 60, the inlet end being adapted for connection to a source of resin, and the outlet end comprising a flange 66 defining a sealing surface. The mount has an inlet 74 and a sealing surface 72 surrounding the inlet. In use, the mount is located inside a vacuum bag and the outlet end of the conduit is arranged in fluid communication with the inlet of the mount, such that a source of resin outside the vacuum bag is connectable to the inlet end of the conduit. The flange of the conduit is located outside the vacuum bag and surrounds the inlet in opposed relation with the sealing surface of the mount. A portion of the vacuum bag is located between the respective sealing surfaces of the conduit and the mount. Upon creation of an effective vacuum inside the vacuum bag, and hence inside the inlet of the mount, a pressure differential is created across the flange. The pressure differential causes the flange to bear against the mount and create a seal between the respective sealing surfaces of the flange and the mount around the inlet. Preferably, the outlet end of the conduit comprises a spout that forms a push, or sliding fit with the inlet of the mount forming a thread-free connection. A gasket may be positioned between the respective sealing surfaces in use.

Description

Self-sealing resin inlet port

Field of the Invention

The present invention relates generally to the fabrication of composite structures such as wind turbine blades by vacuum bag moulding. More specifically, the present invention relates to a self-sealing resin inlet port suitable for use in a vacuum-assisted moulding process, and to an associated vacuum-assisted moulding process utilising the resin inlet port.

Background

Vacuum bag moulding or vacuum bagging' is a manufacturing process used to form reinforced composite structures such as modern wind turbine blades. The blades are typically moulded as two half shells, which are subsequently joined together.

The moulding process for a blade shell is illustrated schematically in Figure 1. A lay-up is created by arranging a plurality of structural fabric layers 10 on a surface 11 of a mould 12. These fabric layers are typically made up of glass-fibre fabric and other structural materials. Following this, a vacuum bag, or vacuum film' 14, is placed over the lay-up and is sealed against the mould surface 11 to create a substantially sealed volume containing the laminate 15. A vacuum pump attached to a vacuum port 16 in the vacuum film 14 is used to extract air from the sealed volume in order to create an effective vacuum. The vacuum causes the vacuum film 14 to apply pressure to the laminate 15 and is used to draw resin into the sealed region through resin transfer channels 18 running along the length of the mould 12. The resin permeates the laminate layers, and warm air is circulated around the sealed volume to cure the resin. The vacuum and temperature conditions are maintained for a predefined duration, in order to harden the resin and bond the various laminate layers together.

A plurality of resin inlet ports 20 are arranged at intervals along the resin transfer channels 18. The resin inlet ports 20 serve to connect a source of resin (not shown) to the resin transfer channels 18. The inlet ports 20 are comprised of two parts: a resin inlet elbow 22 and a polystyrene inlet port mount 24. Referring to Figure 2, the elbow 22 is a tubular component comprising first 26 and second 28 ends with a ninety-degree bend 29 between the two ends. The first end 26 is provided with a male screw thread 30, which extends below an annular flange 32 protruding circumferentially from the surface of the elbow 22. The second end 28 comprises a series of axially-spaced circumferential protrusions 34.

Referring to Figure 3, the mount 24 is shaped substantially as a truncated pyramid, and has a flat, square-shaped upper surface 36. A circular bore 38 extends vertically through the centre of the mount and defines a circular aperture 40 in the centre of the upper surface 36. The bore 38 is provided with a female thread 42. The base of the mount is provided with curved cut-out portions 44, which define legs 46 at the respective four lower corners of the mount 24.

Referring also to Figure 4, the resin transfer channels 18 are provided with a plurality of pre-drilled holes (not shown) and the inlet port mounts 24 are each placed over a respective one of these holes in the resin transfer channel 18. The mounts 24 are arranged such that the resin transfer channel 18 runs through the curved cut-out portions 44 of the base of the mount 24 and the legs 46 of the mount 24 are supported against the laminate 15. Vacuum film 14 is applied over the laminate 15 and over the mounts 24. Once the film 14 has been sealed and the vacuum applied, a circular hole is made in the film directly above the aperture 40 in the upper surface 36 of the inlet port mount 24.

The threaded first end 26 (see Figure 2) of the elbow 22 is screwed into the mount 24 and a resin hose 48 is pushed over the second end 28 of the elbow 22, with the circumferential protrusions 34 (see Figure 2) on the second end 28 of the elbow 22 forming an interference fit with the hose 48. The other end of the resin hose 48 is connected to a source of resin, a resin pump and a valve for controlling the flow of resin into the sealed volume.

Each inlet port 20 is tested for air leaks using ultrasonic testing. There are a number of ways by which failure of the inlet ports 20 can occur, resulting in leakage of air or resin.

For example, any gaps between the flange 32 at the first end 26 of the elbow and the inlet port mount 24, or between the second end 28 of the elbow and the inlet hose 48, may act as a path for air to leak into the sealed volume. It is important to prevent air leaks because any resultant air bubbles within the laminate 15 may compromise the integrity of the manufactured composite structure. As shown in Figure 4, the present method for preventing this is to apply a layer of butyl rubber tape, or tacky tape' 49, to the threaded section 30 of the resin inlet elbow 22 and to the lower surface 50 (see Figure 2) of the elbow flange 32. Butyl rubber tape 51 is also applied to the second end 28 of the elbow 22, in order to prevent air leakage at the elbow-hose interface.

The port 20 may also fail through collapse of the inlet port mount 24. The pressure applied by the vacuum film 14 to the mount is significant, and under the operating conditions of the vacuum bagging process, and relatively high temperatures of the curing process in particular, the polystyrene mount 24 can buckle or fracture. This can create air leakage paths between the mount 24 and the vacuum film 14.

In order to safeguard against air leakage a secondary vacuum bag (not shown) is presently placed over the assembled inlet port 20 and sealed against the vacuum film 14, with secondary tubes connecting the bag to the main vacuum pump. In the event that the primary vacuum seal between the laminate 15 and vacuum film 14 is lost, resin is drawn into the secondary vacuum bag. Once this secondary vacuum bag is saturated there is again the possibility of direct air leaks into the infused part.

Since the secondary vacuum bag sits over the resin inlet elbow 22 and resin inlet hose 48, large pressures can be exerted on these parts when the vacuum is applied. Leverage on the resin inlet elbow 22 can cause cracking at the ninety-degree bend 29 of the elbow 22, allowing resin to leak into the secondary vacuum bag. This leverage also stresses the seal between the elbow flange 32 and the upper surface 36 of the mount 24 and this increases the likelihood of resin or air leakage at this interface.

The present invention aims to overcome some or all of these problems.

Summary of the invention

In accordance with the present invention, there is provided a resin inlet port for use in a vacuum-assisted moulding process, the port comprising: a conduit having an inlet end and an outlet end, the inlet end being adapted for connection to a source of resin, and the outlet end comprising a flange defining a sealing surface; and a mount having an inlet and a sealing surface surrounding the inlet; wherein, in use, the mount is located inside a vacuum bag and the conduit is arranged such that the outlet end of the conduit is in fluid communication with the inlet of the mount and the inlet end of the conduit is connectable to a source of resin outside the vacuum bag, the flange of the conduit being located outside the vacuum bag and surrounding the inlet in opposed relation with the sealing surface of the mount and a portion of the vacuum bag being located between the respective sealing surfaces of the conduit and the mount, such that upon creation of an effective vacuum inside the vacuum bag and hence inside the inlet of the mount, a pressure differential is created across the flange, the pressure differential causing the flange to bear against the mount and create a seal between the respective sealing surfaces of the flange and the mount around the inlet.

The system uses the effective vacuum within the vacuum bag to draw the conduit towards the mount, creating a seal between the two sealing surfaces and making the resin inlet port effectively self-sealing. This reduces the time taken to create a seal between the two components and reduces the vacuum loss during assembly, relative to the resin inlet port of the prior art. In the prior ad, the seal is also created between the threaded end of the resin inlet elbow and the threaded bore of the inlet pod mount, with butyl rubber tape used to fill any gaps between the two components. In the present invention, the seal is primarily formed between the sealing surface of the flange of the conduit and the sealing surface of the mount, reducing the likelihood of air leaks forming between the two components. The seal in the present invention is advantageously maintained by the vacuum inside the vacuum bag.

In a particular embodiment, the outlet end of the conduit further comprises a spout configured for insertion in the inlet of the mount, and wherein the flange is located between the spout and the inlet end of the conduit. The spout assists in locating the conduit relative to the mount, such that the sealing surfaces of the respective components are positioned in close relation to one another.

In one example, the spout is configured to form a push fit with the inlet. Further, the spout may form a clearance or sliding fit with the inlet. This increases the ease with which the spout of the conduit is inserted into the mount compared to the prior art, since a turning or screwing action is not necessary. Accordingly, in a preferred embodiment of the invention, the connection between the spout and the inlet is a thread-free connection.

The simplified design of the conduit and the mount of the invention, relative to the elbow and the mount of the prior ad, advantageously reduces the human intervention required to ensure the resin inlet pod is set up correctly without leaks. The conduit is simply inserted into the mount and the vacuum effects the seal, without the need to pack the interface with butyl rubber sealant.

In a preferred embodiment of the invention the spout has a substantially smooth outer surface. This enables the spout to slide within the inlet of the mount under the vacuum pressure as the flange is pressed into engagement with the mount. A clearance region is preferably defined between the spout and the inlet when the spout is inserted into the inlet. This clearance region further facilitates the sliding movement of the spout within the inlet of the mount. In a particular embodiment the size of the clearance region is in the range of 0.1mm to 0.2 mm.

The spout of the resin inlet port may be substantially circular in cross section. In a preferred embodiment of the invention, the inlet of the mount is substantially circular. In the case that the spout is substantially circular in cross section, the inlet is substantially circular and the connection between the two components is thread-free, the two components have infinite rotational synimetry. The spout is therefore able to be inserted in any orientation into the inlet, increasing the ease with which the resin inlet port is assembled.

The sealing surface of the mount is substantially annular in preferred embodiments. The flange of the conduit may also be substantially annular. In a preferred embodiment, the sealing surface of the flange corresponds substantially in shape and size with the sealing surface of the mount. The two sealing surfaces being substantially the same size and shape gives a region of contact which is of a maximum possible size. This creates a seal of greater integrity relative to the prior art, and reduces the likelihood of the user being exposed to leaked wet resin, increasing the safety of the vacuum bagging process. The relatively large contact area between the two parts also serves to increase the stability of the inlet port assembly.

The assembled resin inlet port may also comprise a gasket to be positioned between the respective sealing surfaces in use. The gasket is preferably configured to surround the inlet. The gasket acts as a seal from the atmospheric pressure outside of the vacuum bag, and its provision is an inexpensive way of creating a more effective seal between the two sealing surfaces. In preferred embodiments, the gasket is substantially annular.

In a preferred embodiment of the invention, the mount is substantially frusto-conical in shape. This shape provides the mount with greater strength in resisting the high pressures exerted on it as a result of the pressure differential created across the flange of the conduit, reducing the likelihood of collapse of the mount relative to the prior art.

The shape of the mount also allows for easier application of the vacuum bag, reducing creasing of the bag and therefore improving the integrity of the seal between the bag and the surface of the mount.

The mount may advantageously have a substantially conical side surface that tapers inwardly from a base of the mount towards the sealing surface.

In preferred embodiments, the conduit of the resin inlet port forms an elbow.

The inlet end of the conduit may be adapted for connection to a resin inlet pipe, to allow resin to pass within the conduit and into the inlet of the mount. In a preferred embodiment the inlet end of the conduit includes a plurality of circumferential protrusions that form a push fit seal with the resin inlet pipe. Creation of an effective connection between the resin inlet pipe and the conduit reduces the likelihood of resin leakages at this point.

In accordance with the present invention, there is also provided a method of using a resin inlet port in a vacuum-assisted moulding process, the resin inlet pod comprising: a conduit having an inlet end and an outlet end, the inlet end being adapted for connection to a source of resin, and the outlet end comprising a flange defining a sealing surface; and a mount having an inlet and a sealing surface surrounding the inlet, and the method comprising the following steps, in any suitable order: i) locating the mount inside a vacuum bag such that the vacuum bag extends over the sealing surface of the mount; ii) providing an aperture in the vacuum bag adjacent to the inlet of the mount; iii) arranging the outlet end of the conduit in fluid communication with the inlet of the mount, with the flange of the conduit being located outside the vacuum bag and surrounding the inlet of the mount in opposed relation with the sealing surface of the mount and with a portion of the vacuum bag being located between the respective sealing surfaces; iv) establishing an effective vacuum inside the vacuum bag and hence inside the inlet of the mount, whereby the effective vacuum creates a pressure differential across the flange; v) causing the flange of the conduit to bear against the sealing surface of the mount by virtue of the pressure differential across the flange: and thereby vi) creating a seal between the respective sealing surfaces of the conduit and the mount around the inlet.

In a preferred embodiment of the invention, the outlet end of the conduit further comprises a spout, and the method further comprises inserting the spout into the inlet of the mount. The method of using the resin inlet port may also comprise positioning a gasket between the respective sealing surfaces of the flange and the mount. The gasket preferably surrounds the inlet. In a preferred embodiment, the gasket is positioned between the vacuum bag and the sealing surface of the flange.

In one possible embodiment the method of using the resin inlet port further comprises attaching a source of resin to the inlet end of the conduit and admitting resin into the vacuum bag via the resin inlet port.

Optional features described above in relation to the invention when expressed in terms of an apparatus are equally applicable to the invention when expressed in terms of a method and vice versa. Repetition of such features has been avoided where possible purely for reasons of conciseness.

Brief description of the drawings

Figures 1 to 4 have already been described above by way of background to the present invention. Specific embodiments of the present invention will now be described in more detail with reference to the following figures, in which: Figure 5 is an exploded perspective view of a resin inlet port comprising an elbow and a mount according to an embodiment of the present invention; Figure 6 shows the mount of the resin inlet port of Figure 5 arranged over a resin transfer channel; Figure 7 is a schematic perspective view of the inlet port in use; and Figure 8 is a schematic perspective view of a variant of the inlet port in use.

Detailed Description

Referring to Figure 5, this shows a two-part resin inlet port 52 according to an embodiment of the present invention. The resin inlet port 52 comprises a conduit 54 and a mount 56. In this example, the two parts are injection moulded, with the conduit 54 being made of polypropylene and the mount 56 being made of a plastic, such as acrylonitrile butadiene styrene (ABS).

The conduit 54 has an inlet end 58 and an outlet end 60 and is substantially circular in cross section. The inlet end 58 of the conduit 54 defines an inlet 59 and the outlet end defines an outlet 61. In this example, the conduit 54 is shaped as an elbow, with a ninety-degree bend 62 between the two ends. The conduit 54 is referred to hereinafter as the elbow'. The inlet end 58 of the elbow 54 is adapted for connection to a resin source. To this end, the inlet end 58 includes a series of axially-spaced circumferential protrusions 64 configured to form a push fit with an end of a resin inlet hose; the other end of the resin inlet hose being connected to a source of resin.

The outlet end 60 of the elbow 54 includes an annular flange 66, which extends radially outwards from an outer circumference of the elbow 54. The flange 66 comprises a sealing surface 68, which is the surface of the flange 66 facing the outlet 61 of the elbow 54, i.e. the lower surface of the flange 66 in the orientation of the elbow 54 shown in Figure 5. In this embodiment, the outlet end 60 of the elbow 54 further includes a spout of circular cross section, which extends below the flange 66 in the orientation of the elbow 54 shown in Figure 5, i.e. the flange 66 is located between the spout 70 and the inlet end 58 of the elbow 54. In contrast to the prior art elbow 22 shown in Figure 2, and described above by way of background, an outer surface of the spout 70 is un-threaded and has a substantially smooth outer surface.

The mount 56 is shaped substantially as a conical frustum, i.e. a truncated cone, with a flat, circular upper surface 72, which is referred to hereafter as the sealing surface'. The sealing surface 72 of the mount 56 has an aperture 74 which serves as an inlet for resin.

In this example, the inlet 74 is defined by a circular bore 76, extending vertically and centrally through the mount 56. The sealing surface 72 of the mount 56 has a diameter of approximately 50mm, with the bore 76 having a diameter of approximately 20mm.

Whereas the prior art mount 24 described by way of background with reference to Figure 3 includes a threaded bore 38, the bore 76 in this example is not threaded and has a substantially smooth surface.

A base of the mount 56 is provided with opposed semi-circular cut-out portions 78 that define a passage 79 through the base that extends horizontally in the orientation of the mount 56 shown in Figure 5, i.e. substantially perpendicular to the bore 76. Referring to Figure 6, the mount 56 is positioned in use over a resin transfer channel 18 in the mould.

The resin transfer channel 18 has an omega profile, and the cut-out portions 78 of the mount 56 are complementary in shape to this omega profile in order to facilitate the mount 56 sitting over the resin transfer channel 18. The resin transfer channel 18 thereby extends through the passage 79 defined by the cut-outs 78 in the base of the mount 56.

The resin transfer channel 18 is provided with a plurality of pre-drilled holes (not shown) along its length, and the mount 56 is positioned over one of these holes such that the inlet 74 of the mount 56 lies directly over the hole to allow for the passage of resin from the resin source into the resin transfer channel 18 via the inlet port 52 (see Figure 5). In practice there is a plurality of inlet ports 52 each associated with a respective hole in the resin transfer channel 18.

Use of the inlet port 52 will now be described in further detail with reference to Figure 7, which is a schematic cross-sectional view of the inlet port assembly 52.

Referring to Figure 7, this shows the inlet port assembly 52 located on top of a laminate 82 in a mould 84. The resin transfer channel mentioned above has been omitted from Figure 7 for clarity. A vacuum bag 14 is placed over the laminate 82 and the mount 56 of the inlet port 52, such that the mount 56 is located inside the vacuum bag 14. The vacuum bag 14 is sealed against the mould surface to define a sealed region containing the laminate 82 and the mount 56. A vacuum pump (not shown) attached to a vacuum port (not shown) in the vacuum bag 14 is used to extract air from the sealed region in order to create an effective vacuum. The frusto-conical shape of the mount 56 advantageously allows the vacuum film 14 to lie flat against the sealing surface 72 of the mount 56 and tightly against the conical side surface 86 of the mount 56 with minimal creasing of the film 14.

The inlet end 58 of the elbow 54 is connected to one end of a resin inlet hose 88; the other end of the resin inlet hose 88 is connected to a resin source (not shown). The circumferential protrusions 64 of the elbow 54 form an interference fit with the internal surface of the hose 88. In order to ensure integrity of the seal between the two components 54, 88, butyl rubber tape (not shown) is applied to the outer surface of the second end 58 of the elbow 54 before it is attached to the hose 88. A resin inlet valve (not shown) is provided between the elbow 54 and the resin source for controlling the flow of resin into the mould 84.

With the vacuum pump running and the resin inlet valve closed, a ring of butyl rubber tape 90 is placed over the vacuum film 14 against the sealing surface 72 of the mount 56. The tape 90 surrounds the inlet 74 of the mount 56 and acts as a gasket. Next, a circular hole is cut in the vacuum film 14 directly above the inlet 74 in the sealing surface 72 of the mount 56, and the spout 70 of the elbow 54 is inserted through this hole and into the inlet 74 of the mount 56. In this configuration, the flange 66 and the inlet end 58 of the elbow 54 are located outside of the vacuum bag 14, with the sealing surface 68 of the flange 66 being located in opposed relation to the sealing surface 72 of the mount 56.

The vacuum film 14 and the butyl rubber gasket 90 are located between the respective sealing surfaces 68, 72.

The inlet 74 in the mount 56 conveniently serves as a locating feature for the spout 70 of the elbow 54. As both the spout 70 and the inlet 74 are substantially circular, there is rotational symmetry in the connection between the elbow 54 and the mount 56 about a central axis 92 of the inlet 74. This symmetry in the connection is convenient as it allows the elbow 54 to be connected to the mount 56 easily in any rotational orientation about the central axis 92.

The diameter of the spout 70 is slightly smaller than the diameter of the inlet 74 (in this example, by approximately 1mm) such that a circumferential clearance region 93 is defined between the spout 70 and the inlet 74. This clearance region facilitates relative movement between the elbow 54 and the mount 56, as will be described in further detail later.

With the spout 70 inserted loosely into the inlet 74 and the resin inlet valve closed, the vacuum pump draws air from sealed region and hence from the inlet 74 of the mount 56.

The reduced pressure creates a pressure differential across the flange 66, which causes the flange 66 to bear against the sealing surface 72 of the mount 56. As the flange 66 bears against the mount 56, it compresses the butyl rubber gasket 90 and creates a seal between the sealing surface 68 of the flange 66 and the sealing surface 72 of the mount 56 around the inlet 74. The clearance region 93 between the spout 70 and the inlet 74 allows the spout 70 to slide downwards into the inlet 74 as the flange 66 bears against the mount 56. This is in contrast to the prior art where the threaded connection between the spout and the inlet prevents such axial movement between the two components. The inlet port 52 of the present invention is thereby self-sealing upon establishment of an effective vacuum in the sealed region, with the vacuum inside the sealed region serving to maintain the two components in sealed relation.

Whereas the prior art arrangement relied on a threaded connection between the elbow 22 and the mount 24, in the present invention this connection is thread-free. The thread-free connection advantageously allows the spout 70 simply to be pushed into the inlet 74. As soon as the spout 70 is inserted into the inlet 74, a seal is created.

In contrast to the prior art arrangement, where any movement between the elbow 22 and the mount 24 was likely to disrupt the seal, in the present invention the seal is not disrupted by relative movement between the components. In fact, the seal is enhanced by relative axial movement between the elbow 54 and the mount 56 caused by the vacuum in the sealed region. Accordingly, a tight seal is maintained throughout the vacuum bagging process with the present invention.

In the present invention, the diameter of the flange 66 is relatively large in comparison to the diameter of the elbow 54. In this example, the ratio of the diameter of the flange 66 to the diameter of the outer surface of the outlet end 60 of the elbow 54 is approximately 5:2. While the precise ratio is not critical, the relatively large flange 66 (and similarly sized sealing surface 72 of the mount 56) provides a large sealing region between elbow 54 and the mount 56.

Once the seal between the elbow 54 and the mount 56 has been created, and tested for leaks if required, the resin inlet valve is opened. The vacuum within the sealed region draws resin from the resin source through the resin inlet hose 88, through the inlet end 58 of the elbow 54, out through the outlet end 60 of the elbow 54 and into the resin transfer channel 18 running through the base of the mount 56. The resin transfer channel 18 transfers the resin along the length of the mould 84 to permeate into the layers of the laminate 82. A resin pump may optionally be employed to pump resin from the resin source into the mould 84 via the inlet port 52.

A further benefit of the invention is that in some cases the relatively strong seal between the annular flange 66 of the elbow 54 and the upper surface 72 of the mount 56 obviates the need for a secondary vacuum bag. The purpose of a secondary vacuum bag was described above by way of background. However, as a precautionary measure, a secondary vacuum bag can be applied over the assembled resin inlet port 52, if desired, to further safeguard against any potential air leaks within the assembly. The secondary bag may be sealed against the vacuum film, with secondary tubes connecting the bag to the main vacuum pump.

In comparison to the prior art inlet port 20, the inlet port 52 of the present invention is less likely to incur damage when a secondary vacuum bag is used. This is due to a number of factors. For example, the elbow 54 of the present port 52 is designed to sit relatively close to the inlet port mount 56, and hence leverage on the elbow 54 is reduced in comparison to the prior art. The elbow 54 is therefore less likely to buckle than the prior art elbow 22. Further, any such leverage is less likely to disrupt the seal in the present arrangement because, as mentioned above, the seal in the present invention is not disrupted by relative movement between the elbow 54 and the mount 56. The relatively large flange 66 also serves to support and stabilise the elbow 54 relative to the mount 56, in comparison to the prior art flange 32 which is relatively small and does not have any appreciable stabilising effect. Furthermore, the mount 56 of the present invention is made from plastic rather than polystyrene and so does not fracture in use.

Other embodiments of the invention are envisaged in which the gasket 90 between the flange 66 and the mount 56 is omitted. In such cases a seal is established directly between the respective sealing surfaces of the flange 66 and the mount 56, albeit with the vacuum film 14 being located between these surfaces. The gasket 90 is however preferred as it serves to enhance the seal and maintain the seal in the event of the vacuum being temporality lost in the sealed region.

While it is preferable for the elbow 54 to extend below the flange 66, in order to allow for self-location of the spout 70 within the aperture 74 of the mount 56, this feature is not essential for forming the seal. Accordingly, in another embodiment of the invention (as shown in Figure 8), the first end 60 of the elbow 54 terminates at the annular flange 66, i.e. the spout is omitted. The operation of the apparatus is substantially the same as previously described, other than the process of inserting the spout into the aperture 74 in the mount 56. In this embodiment, a layer of butyl rubber tape 90 may be applied between the sealing surfaces of the flange 54 and the mount 56 and the vacuum film 14 is cut above the aperture 74 in the mount 56. The flange 66 of the elbow 54 is then placed on top of the sealing surface 72 of the mount 56. In the same way as previously described, a vacuum within the sealed region causes the flange 66 to bear down on the mount 56 and effect a seal between the mount 56 and the elbow 54. As with the previous embodiment, the inlet port 52 is self-sealing on creation of a reduced pressure in the sealed region. It will be appreciated that the spout 70 of the first embodiment is advantageous because it ensures correct alignment between the respective sealing surfaces of the flange 54 and the mount 56 when inserted into the inlet 74; this therefore facilitates connection of the two components 54, 56.

The terms vacuum' and effective vacuum' are used herein for convenience to refer to a reduced pressure (relative to atmospheric pressure). The reduced pressure is preferably less than or equal to 100 mbar. It will of course be appreciated that it is impossible to create a perfect vacuum; nevertheless this terminology is used in the art to refer to suitably low pressures, but should not be interpreted in such a way as to unduly limit the scope of protection.

For the avoidance of doubt, relative terms such as vertical', horizontal', upper' and lower' are used herein for convenience and relate to the orientation of features as shown in the accompanying figures. These terms should not be interpreted in a way so as to unduly limit the scope of the invention.

Many modifications may be made to the above examples without departing form the scope of the invention as defined in the accompanying claims.

Claims

Claims 1. A resin inlet port for use in a vacuum-assisted moulding process, the port comprising: a. a conduit having an inlet end and an outlet end, the inlet end being adapted for connection to a source of resin, and the outlet end comprising a flange defining a sealing surface; and b. a mount having an inlet and a sealing surface surrounding the inlet; wherein, in use, the mount is located inside a vacuum bag and the conduit is arranged such that the outlet end of the conduit is in fluid communication with the inlet of the mount and the inlet end of the conduit is connectable to a source of resin outside the vacuum bag, the flange of the conduit being located outside the vacuum bag and surrounding the inlet in opposed relation with the sealing surface of the mount and a portion of the vacuum bag being located between the respective sealing surfaces of the conduit and the mount, such that upon creation of an effective vacuum inside the vacuum bag and hence inside the inlet of the mount, a pressure differential is created across the flange, the pressure differential causing the flange to bear against the mount and create a seal between the respective sealing surfaces of the flange and the mount around the inlet.
2. The resin inlet port Claim 1, wherein the outlet end of the conduit further comprises a spout configured for insertion in the inlet of the mount, and wherein the flange is located between the spout and the inlet end of the conduit.
3. The resin inlet port of Claim 2, wherein the spout is configured to form a push fit with the inlet.
4. The resin inlet port of Claim 2 or Claim 3, wherein the spout forms a clearance or sliding fit with the inlet.
5. The resin inlet port of any of Claims 2 to 4, wherein the connection between the spout and the inlet is a thread-free connection.
6. The resin inlet port of any of Claims 2 to 5, wherein the spout has a substantially smooth outer surface.
7. The resin inlet port of any of Claims 2 to 6, wherein a clearance region is defined between the spout and the inlet when the spout is inserted into the inlet.
8. The resin inlet port of Claim 7, wherein the size of the clearance region is in the range of 0.1mm to 0.2 mm.
9. The resin inlet port of any of Claims 2 to 8, wherein the spout is substantially circular in cross section.
10. The resin inlet port of any preceding claim, wherein the inlet is substantially circular.
11. The resin inlet port of any preceding claim, wherein the sealing surface of the mount is substantially annular.
12. The resin inlet port of any preceding claim, wherein the flange is substantially annular.
13. The resin inlet port of any preceding claim, wherein the sealing surface of the flange corresponds substantially in shape and size with the sealing surface of the mount.
14. The resin inlet port of any preceding claim, further comprising a gasket to be positioned between the respective sealing surfaces in use, the gasket being configured to surround the inlet.
15. The resin inlet port of Claim 14, wherein the gasket is substantially annular.
16. The resin inlet port of any preceding claim, wherein the mount is substantially frusto-conical in shape.
17. The resin inlet port of Claim 16, wherein the mount has a substantially conical side surface that tapers inwardly from a base of the mount towards the sealing surface.
18. The resin inlet port of any preceding claim, wherein the conduit forms an elbow.
19. The resin inlet port of any preceding claim, wherein the inlet end of the conduit is adapted for connection to a resin inlet pipe.
20. A method of using a resin inlet port in a vacuum-assisted moulding process, the resin inlet port comprising: a. a conduit having an inlet end and an outlet end, the inlet end being adapted for connection to a source of resin, and the outlet end comprising a flange defining a sealing surface; and b. a mount having an inlet and a sealing surface surrounding the inlet, and the method comprising the following steps, in any suitable order: i) locating the mount inside a vacuum bag such that the vacuum bag extends over the sealing surface of the mount; ü) providing an aperture in the vacuum bag adjacent to the inlet of the mount; iii) arranging the outlet end of the conduit in fluid communication with the inlet of the mount, with the flange of the conduit being located outside the vacuum bag and surrounding the inlet of the mount in opposed relation with the sealing surface of the mount and with a portion of the vacuum bag being located between the respective sealing surfaces; iv) establishing an effective vacuum inside the vacuum bag and hence inside the inlet of the mount, whereby the effective vacuum creates a pressure differential across the flange; v) causing the flange of the conduit to bear against the sealing surface of the mount by virtue of the pressure differential across the flange; and thereby vi) creating a seal between the respective sealing surfaces of the conduit and the mount around the inlet.
21. The method of Claim 20, wherein the outlet end of the conduit further comprises a spout, and the method further comprises inserting the spout into the inlet of the mount.
22. The method of Claim 20 or Claim 21, further comprising positioning a gasket between the respective sealing surfaces of the flange and the mount, the gasket surrounding the inlet.
23. The method of Claim 22, wherein the gasket is positioned between the vacuum bag and the sealing surface of the flange.
24. The method of any of Claims 20 to 23, further comprising attaching a source of resin to the inlet end of the conduit and admitting resin into the vacuum bag via the resin inlet port.