GB2456565A

GB2456565A - Moulded article ejecting tool

Info

Publication number: GB2456565A
Application number: GB0800983A
Authority: GB
Inventors: Dale Edmunds; Andrew Smith
Original assignee: GKN Aerospace Services Ltd
Current assignee: GKN Aerospace Services Ltd
Priority date: 2008-01-18
Filing date: 2008-01-18
Publication date: 2009-07-22
Anticipated expiration: 2028-01-18
Also published as: GB2456565B; GB0800983D0

Abstract

The present invention relates to a moulding tool for moulding a polymer matrix composite component 2. The tool comprises a primary mould portion 4 and a secondary mould portion 5, which defines a mould recess 3 with the portion 4 and which is selectively releasable from said primary mould portion, in use, to leave a release or leverage surface 7 between the moulded component 2 and said primary mould portion 4. A release tool 8 is then used to prise off the component from the portion 4. The secondary portion 5 includes a projection 6 to form the release surface 7.

Description

2456565

Eiector Tool

The present invention relates to a tool and associated method for forming composite components such as polymer matrix composite (PMC) components.

Polymer Matrix Composites (PMC), also known as Fibre-Reinforced Polymers (FRP) can be formed using glass, carbon, aramid or hybrid fibres. They are generally formed by laying a series of fibre fabric or mesh layers into a mould corresponding to the shape of the desired component. The fabric may be pre-impregnated with a resin, the resin may be applied to the carbon fibre layers as the product is built in the mould or the resin can be injected into the mould after the carbon fibre layers have been built within the mould. The resin is then cured to form the final product.

Assemblies of moulded composite components or parts formed using these and other materials are commonly used in the automotive and aerospace industries in a range of products.

In order to form a composite component, a laminate is formed from layers of fibres and resin being arranged in a mould recess within a mould tool. The layers are then cured, typically using an autoclave, and the final part is removed from the mould for finishing.

1

c

The tool or mould is formed from a material having suitable strength and heat resistant properties such that it maintains its shape during the moulding process. The mould may for example be formed of steel or a composite material such as carbon fibre.

Once the component part is cured, an operator must separate the cured component part from the mould. Separating the part from the mould is often difficult because the surface layer of the component in contact with the mould surface has a tendency to adhere to the mould. Consequently, the parts are generally removed from the moulds by inserting an implement, such as a screw driver or the like between an edge of the component and the mould recess and applying a force to the free end of the implement in order to lever the component part out of the mould. Use of these methods can result in damage to the edge of the component at the point where the leverage force is applied. In addition, it has been recognised that the application of a leverage force in a localised region on the component can cause separation of the laminate layers resulting in damage to the surface layer of the component. Severe separation of the laminate layers may also compromises the integrity of the entire component rendering it unsafe for use in its ultimate application.

Whilst separation of layers may be of little consequence in many applications for particular applications, such as the aerospace industry this can render a part unusable and in this instance the component must be discarded resulting in wasted time and resources.

2

The present invention has been made, at least in part, in consideration of the problems and drawbacks of conventional systems.

According to a first aspect of the invention, there is provided a polymer matrix composite component moulding tool, said tool comprising: a primary mould portion and a secondary mould portion selectively releasable from said primary mould portion and defining a mould recess therebetween, wherein the secondary mould portion comprises means adapted in use to form a release surface between said component and said primary mould portion.

The release surface is arranged to receive a release tool having a profile engageable with the surface. Manipulation of the tool, when the profile is engaged with the surface, may advantageously be used to separate the component from the primary mould portion. Thus, there is provided a simple and effective tool for moulding components.

The release surface may advantageously be formed by means of a projection arranged to extend from the secondary mould portion into the mould recess i.e. into the region of the mould defined between the two mould portions. Thus, the release surface can be formed by one portion of the mould thereby minimising the mould components and manufacturing costs. The projection is arranged to create an area between the primary mould portion within the mould recess and the component so that a release tool or member can be used to separate the component from the mould. This is advantageously achieved by exposing a release area i.e. an area of the primary

3

c mould portion within the mould recess against which a force can be applied to the component.

The projection may advantageously be arranged to correspond to a particular feature of the component being cured. Thus, the separating force can be applied to a part of the required component to separate the component from the mould. In such an arrangement the second mould portion may be arranged to align with an edge of the . component comprising such a feature i.e. the location of the second mould portion may be defined by a portion of the required component which can advantageously provide a surface against which a tool (described below) may engage. Alternatively, the portion of the component formed by the projection may be sacrificial i.e. it may be machined from the resulting component once the component has been removed from the mould.

The release surface may extend along a portion of the perimeter of the mould recess. Advantageously the release surface may extend along all or substantially all of the edge of the mould recess to maximise the contact area of a release tool and minimise the pressure applied by a release tool against the component. Thus, damage to the component can further be limited.

When the mould is assembled the projection from the secondary mould portion may advantageously rest on a lower surface of the mould recess so as to seal the recess of the mould along the region where the primary and secondary mould portions abut. The shape of the projection and the distance to which the projection

4

extends into the mould recess may be selected to correspond to the required shape of the component to be formed.

The projection may additionally be provided with an upper surface which is inclined to the inner surface of the primary mould i.e. the lower surface of the mould recess so as to form a generally tapered or wedge like shape extending into the recess. The projection thereby provides a region extending into the mould recess which can be adapted at least in part to correspond to the desired shape of the component whilst providing a release surface discussed in more detail below.

The inclined surface may be arranged at any suitable angle to the lower surface of the mould recess but is advantageously at 45 degrees to the surface. The surface may alternatively or additionally be curved.

Viewed from a second aspect there is provided a mould ejection system comprising a tool as discussed above and a release tool, wherein the release tool is adapted to cooperate with the release surface provided in the tool to eject a moulded component.

The release tool may be any suitable shape which can apply a separating force between the primary mould portion and the component within the mould. The release tool may for example be in the form of a lever arrangement to maximise the separation force. Alternatively, to minimise the pressure on the component the release tool may be in the form of an elongate member arranged to align with the release surface and comprising a projection arranged in use to engage with the

5

c component on relative movement of the primary mould portion and the release tool. A tool using an elongate portion in combination with a lever arrangement may also be employed depending on the forces required to separate the tool.

The release tool may for example be provided with an inclined portion such as a tapered portion arranged to engage with a corresponding tapered portion of the component (formed by the projection of the secondary mould portion) so as to apply a separating force to the component.

The mould tool may be formed from any suitable material such as a metal, for example a steel. However, there may be disadvantages associated with creating composite component parts with a metal mould as the relative thermal expansion rates of the composite material and metal during the curing process may differ. This may compromise the final geometry of the component. In order to overcome this limitation, the mould tool and removable part may be made from the same composite material as the component so that the expansion rates are the same resulting in a more accurate component size being achieved.

Use of a mould tool for moulding a composite component part and a mould ejection system as described above reduces the likelihood of separation of the laminate layers and damage to the component part. The mould tool also provides a set procedure for separation of the component part from mould tool. This removes the need for an operator to go through a trial and error procedure in order to work out an effective method of separation.

6

c

Specific embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a mould tool in accordance with an embodiment of the invention;

Figure 2 is a part exploded view of the mould tool;

Figure 3 is a view of the mould tool, shown with the second mould portion removed and a release tool positioned adjacent the primary mould portion and component part;

Figure 4 is a perspective view of the mould tool of Figure 3, shown with the release tool engaged with the release surface between the component part and the primary mould portion; and

Figure 5 is an enlarged perspective view of area A, as indicated in Figure 4.

While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

Referring to the figures, there is provided a tool 1 for moulding a composite component part 2. The component part 2 may be made from any suitable Polymer Matrix Composite (PMC), also known as Fibre-Reinforced Polymers (FRP), and may include glass, carbon, aramid or hybrid fibres.

7

c

The tool 1 is in the form of a rectangular prism and includes a mould recess 3. However, many different tool shapes and mould recess shapes may be utilised depending on the component shape desired. The tool may be formed from any material which is able to maintain its shape during the curing process. In one embodiment the tool is formed of a PMC and may be sacrificial in the production process i.e. discarded after curing.

The tool 1 includes a primary mould portion 4 and a secondary mould portion 5, as shown in Figures 1 and 2. The primary mould portion 4 and secondary mould portion 5 can be connected together to form at least a portion of the perimeter of the mould recess 3, as shown in Figure 1. In such an arrangement the remaining peripheral sides of the tool (and thereby the sides of the component) may be defined by additional mould portions (not shown). The connection between the primary mould portion and secondary mould portion is selectably releasable i.e. the primary and secondary mould portions can be decoupled. This may be achieved using integral screw-jack mechanisms or the like to facilitate easy coupling and decoupling of the mould. However, any suitable mechanism for releasably connecting the two components may be used.

According to the present embodiment the secondary mould portion 5 is in the form of an elongate side panel which forms an edge of the rectangular tool 1. Part of the secondary mould portion 5 is arranged to extend into the space defined by the mould recess 3. Thus, the secondary mould portion 5 also defines part of the inside surface of the mould recess 3 as seen in Figures 1 and 2.

8

It will be recognised that the secondary mould portion 5 may be any suitable shape which allows it to connect to the primary mould portion 4 and which defines the required internal shape of mould recess 3.

As shown in Figures 1 and 2, a part of the the secondary mould portion S is arranged to extend into the mould recess 3. This part of the secondary mould portion S is adapted to create a space between the component part 2 and the primary mould portion 4 when the part is cured. In the embodiments shown in Figures 1 and 2, this is achieved by means of an elongate projection 6 which extends along the length of the secondary mould portion 5 facing the recess 3. When the primary mould portion 4 and secondary mould portion 5 are connected together, as shown in Figure 1, the elongate projection 6 lies immediately adjacent to the lower surface of the mould recess 3 formed in the primary mould portion 4.

Arranging the elongate projection 6 in this way during curing creates a corresponding elongate space or release surface between the component part 2 and the primary mould portion 4. When the secondary mould portion 5 is subsequently disassembled from the primary mould portion 4 (as shown in Figure 2) the elongate space remains which is accessible from the side of the mould. This space provides a release or leverage surface 7 which can be used to separate the component part 2 from the primary mould portion 4 as discussed below.

Although an elongate projection 6 is shown in this embodiment of the invention, any suitably shaped projection for creating the required surface or region

9

between the component part 2 and the primary mould portion 4 during the curing process may be used.

Returning to Figure 1, this illustrates how the mould and component appear both pre-and post-curing. The composite component is built or inserted into the mould recess in an un-cured state. The mould is then inserted into an autoclave (if autoclave curing is to be used) at a temperature and pressure determined by the particular materials being used. The autoclave process is well known in the art and will not therefore be described here. After the curing process the mould is removed from the autoclave and the component can then be separated from the mould. It will be recognised that the invention is not limited to curing by means of an autoclave and that the invention can equally be applied to self heated tooling or by vacuum curing.

Figure 3, 4 and 5 illustrate the steps of separating the component from the mould.

The component is removed from the mould using a release tool 8. In the embodiment shown the release tool 8 is in the form of an elongate member extending along one side of the tool 1. In the embodiment shown the cross-section of the release tool 8 corresponds generally to that of the projection 6 formed on the portion 5. However, the tool is adapted to have at least a portion thereof which is arranged such that a force is imparted by the tool to the part 2 generally along the z axis (shown by the axes in Figure 3) when a force is applied to the tool along the x axis. In the embodiment shown this is achieved my means of a wedge, chamfered or tapered profile 9 of the tool 8 as illustrated in Figures 3 to 5.

10

t

The release tool 8 includes a first surface which corresponds generally to the surface 7 formed on the bottom of the recess 3. This surface is arranged in use to move along the surface 7 in the x direction. The release tool 8 is also provided with a surface 10, generally opposing the tapered profile 9, upon which a force may be applied in order to apply a resultant force against the release surface 7 causing the component 2 to be forced out of the mould recess 3 of the primary mould portion 4.

In use, the primary mould portion 4 and secondary mould portion 5 are assembled together to form the mould recess 3, as shown in Figure 1. A composite component part 2 is then formed in the shape of the mould recess 3. Once the component part 2 is cured, the secondary mould portion 5 is separated from the primary mould portion 4, exposing the release surface 7, as shown in Figure 2. The release tool 8 is then engaged with the release surface 7, as shown in Figures 4 and 5. As the tool is moved in the x direction the tapered profile 9 of release tool engages with a portion 11 of the component 2 (see Figure 4). A force is then applied to the release tool surface 10 of the tool 8 causing the component to be forced out of the mould recess 3.

The profile 9, be it tapered or wedge shaped, may advantageously be arranged to contact the component 2 along substantially all of the length of the exposed edge shown in the figures. Thus, the pressure applied to the component by the release tool is minimised thereby reducing the chance of damage to the component such as separation of laminate layers.

11

It will be appreciated that the illustrated tool and release arrangement provides an efficient device for separating a composite component part from a mould tool, whilst reducing the likelihood of damage occurring to the component part during separation. The tool also provides a set process for an operator to separate the component from the mould tool, hence the need for trial and error to find a suitable implement and procedure for separation is no longer required.

Although the invention has been described with reference to the above specific examples, it will be appreciated by those skilled in the art that the invention can be embodied in many other forms.

12

Claims

1. A polymer matrix composite component moulding tool, said tool comprising: a primary mould portion and a secondary mould portion selectively releasable from said primary mould portion and defining a mould recess therebetween, wherein the secondary mould portion comprises means adapted in use to form a release surface between said component and said primary mould portion.

2. A tool as claimed in claim 1, wherein the means adapted to form said release surface is a projection arranged in use to extend into said mould recess from a face of said secondary mould portion adjacent to the primary mould portion.

3. A tool as claimed in claim 2, wherein the projection extends substantially along the entire length of the secondary mould portion.

4. A tool as claimed in claim 2 or claim 3, wherein a first surface of said projection is arranged in use to extend along a portion of the inner surface of the primary mould portion.

5. A tool as claimed in any of claims 2 to 4, wherein a second surface of said projection is arranged in use to be inclined relative to the inner surface of the primary mould portion.

13

6. A tool as claimed in any preceding claim, wherein the secondary mould portion defines an edge of said tool and is arranged to move laterally away from said primary mould portion when released from said primary mould portion.

7. A mould ejection system comprising a tool according to any preceding claim and a release tool, wherein the release tool is adapted to cooperate with said release surface to eject a moulded component.

8. A mould ejection system as claimed in claim 7, wherein the release tool is in the form of an elongate member arranged to align with the release surface and comprising a projection arranged in use to engage on a first surface with the release surface and on an opposing second surface with the component.

9. A mould ejection system as claimed in claim 7 or claim 8, wherein the profile of the release tool adjacent to the release surface is configured such that movement of a portion of the release tool along the release surface and into the recess ejects the component.

10. A mould ejection system as claimed in claim 8 or claim 9, wherein the release tool incorporates a wedge shaped cross-section to eject the component.

11. A tool as substantially hereinbefore described with reference to the accompanying drawings.

14

12. A mould ejection system as substantially hereinbefore described with reference to the accompanying drawings.

\%

13. A method of forming a polymer matrix composite component as substantially hereinbefore described with reference to the accompanying drawings.

15

4. A tool as claimed in claim 2 or claim 3, wherein a first surface of said projection is amuiged in use to extend along a portion of the inner surface of the primary mould portion.

It

U.A tool as substantially hereinbefore described with reference to the accompanying drawings.

n